EPA-650/2-75-006
DECEMBER 1974
Environmental Protection Technology Series
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RESEARCH REPORTING SERIES
Research reports of the Office of Research and Development, U.S. Environ-
mental Protection Agency, have been grouped into series. These broad
categories were established to facilitate further development and applica-
tion of environmental technology. Elimination of traditional grouping was
consciously planned to foster technology transfer and maximum interface
in related fields. These series are:
1. ENVIRONMENTAL HEALTH EFFECTS RESEARCH
2. ENVIRONMENTAL PROTECTION TECHNOLOGY
3. ECOLOGICAL RESEARCH
4. ENVIRONMENTAL MONITORING
5. SOCIOECONOMIC ENVIRONMENTAL STUDIES
6. SCIENTIFIC AND TECHNICAL ASSESSMENT REPORTS
9. MISCELLANEOUS
This report has been assigned to the ENVIRONMENTAL PROTECTION
TECHNOLOGY series. This series describes research performed to
develop and demonstrate instrumentation, equipment and methodology
to repair or prevent environmental degradation from point and non-
point sources of pollution. This work provides the new or improved
technology required for the control and treatment of pollution sources
to meet environmental quality standards.
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EPA-650/2-75-006
A THEORETICAL
AND EXPERIMENTAL STUDY
OF THE LIME/LIMESTONE
WET SCRUBBING PROCESS
by
D. Ottmers Jr., J. Phillips, C. Burklin,
W. Corbett, N. Phillips, and C. Shelton
Radian Corporation
8500 Shoal Creek Boulevard
Austin, Texas 78766
Contract No. 68-02-0023
ROAP No. 21ACY-031
Program Element No. 1AB013
EPA Project Officer: Julian W. Jones
Control Systems Laboratory
National Environmental Research Center
Research Triangle Park, North Carolina 27711
Prepared for
OFFICE OF RESEARCH AND DEVELOPMENT
U.S. ENVIRONMENTAL PROTECTION AGENCY
WASHINGTON, D.C. 20460
December 1974
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EPA REVIEW NOTICE
This report has been reviewed by the National Environmental Research
Center - Research Triangle Park, Office of Research and Development,
EPA , and approved for publication. Approval does not signify that the
contents necessarily reflect the views and policies of the Environmental
Protection Agency, nor does mention of trade names or commercial
products constitute endorsement or recommendation for use.
This document is available to the public for sale through the National
Technical Information Service, Springfield, Virginia 22161.
I i
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ABSTRACT
This report describes results of Radian technical
assistance to EPA in several areas concerning the development
of the lime/Limestone wet scrubbing process: (1) review of
a portion of the test plan for EPA’s Prototype Test Facility
at TVA’s Shawnee Station; (2) laboratory studies concerning
key reaction steps, including Lime and limestone dissolution
rates and calcium sulfite and sulfate precipitation rates;
(3) engineering and chemistry support for pilot unit studies
at Combustion Engineering’s Kreisinger Development Laboratory,
including test program design, on-site sampling and chemical
analysis of test samples at Radian, and engineering analysis
of test results; and (4) chemical analysis support at Shawnee,
incLuding assistance with the analytical data system.
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TABLE OF CONTENTS
Page
1.0 SUMMARY . 1
1.1 Shawnee Test Plan Review 1
1.2 Laboratory Rate Studies 2
1.3 Pilot Unit Studies 7
1.4 Analytical Support for Shawnee 13
1.5 Solubility Product of CaSO ½H 2 O 13
2.0 INTRODUCTION 15
3.0 REVIEW OF SHAWNEE TEST PLAN 17
3.1 Background 18
3.2 Statistical Approach 19
3.3 Engineering Aspects 21
3.4 Summary 24
4.0 LABORATORY RATE STUDIES 27
4.1 Experimental Techniques 27
4.2 CaS0 2H 2 O Precipitation 34
4.2.1 Metastable Limit for Nucleation of CaSO 2H 2 O.. 36
4.2.2 Growth Rate Versus Supersaturation Within the
Metastable Region 36
4.2.3 Effects of Temperature on CaSOL,2H2O Growth
Rate 43
4.2.4 Agitation Effects 45
4.2.5 Dependence of Precipitation Rate on Amount of
Seed 45
4.2.6 Conclusions 48
4.3 CaSO 3 ½H 2 0 Precipitation 49
4.3.1 Metastable Limit for Nucleation of CaSO 3 ½H 2 O.. 49
4.3.2 CaSO 3 .½H 2 O Growth Rate Versus Supersaturation
Within the Metastable Region 54
4.3.3 Effects of Temperature and Agitation on
CaSO 3 ½H 2 0 Growth Rate 58
4.3.4 Dependence of CaSO 3 •¾H 2 0 Precipitation Rate on
Amount of Seed 58
iv
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TABLE OF CONTENTS (cont.)
Page
4.3.5 Conclusions 59
4.4 Limestone Dissolution 62
4.4.1 Limestone Dissolution in Dilute HC1 Solutions.. 62
4.4.2 Limestone Dissolution in Simulated Scrubbing
Liquor 76
4.4.3 Summary and Conclusions 80
4.5 Lime Dissolution 83
4.5.1 Simplified Beaker Experiments 83
4.5.2 Packed Bed Reactor Experiments 89
4.5.3 Spray Tower Experiments 90
4.5.4 Analysis of Experimental Spray Tower Data 96
4.5.5 Conclusions 101
5.0 SO 2 SCRUBBING TESTS AT THE WINDSOR PILOT
FACILITY 103
5.1 Windsor Pilot Test Unit 104
5.1.1 Equipment 104
5.1.2 Instrumentation 110
5.1.3 Instrument Calibration 111
5.1.4 Sampling and Analytical Procedures 111
5.2 Test Program and Objectives 112
5.2.1 Phase I - Soluble Sodium Carbonate Tests 113
5.2.2 Phase II - Limestone Injection Wet Scrubbing
Tests 115
5.2.3 Phase III - Limestone Tail-End Addition Tests.. 118
5.3 Soluble Sodium Carbonate Test Results 120
5.3.1 Analytical Results 120
5.3.2 Vapor-Liquid Mass Transfer Rates 128
5.3.3 Conclusions 132
5.4 Limestone Injection Wet Scrubbing Tests 134
5.4.1 Analytical Results 134
5.4.2 Precipitation and Dissolution Rates 138
5.4.3 Vapor-Liquid Mass Transfer Rates 145
V
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TABLE OF CONTENTS (cont.)
Page
5.4.4 Prediction of Scaling Conditions 145
5.4.5 Conclusions 148
5.5 Limestone Tail-End Addition Tests 151
5.5.1 Analytical Results 151
5.5.2 Precipitation and Dissolution Rates 153
5.5.3 Vapor-Liquid Mass Transfer Rates 159
5.5.4 Prediction of Scaling Conditions 163
5.5.5 Conclusions 166
5.6 Application of CE/Windsor Test Experience to
EPA’s Shawnee Program 167
5.6.1 Sampling Procedures 168
5.6.2 Steady State Criteria 169
5.6.3 Material Balance Data Interpretation 171
5.6.4 Precipitation and Dissolution Rate Calculations 171
5.6.5 SO 2 Removal in the Marble Bed Scrubber 172
5.6.6 Prediction of Scaling Conditions 173
6.0 ANALYTICAL SUPPORT FOR SHAWNEE 174
7.0 SOLUBILITY PRODUCT OF CaSOk .½H 2 0 176
7.1 Data Collection and Evaluation 177
7.2 Data Correlation 178
7.3 Results 180
8.0 NOMENCLATURE AND UNITS CONVERSION 183
8 .1 Nomenclature 183
8.2 Units Conversion 185
9.0 BIBLIOGRAPHY 186
10.0 APPENDICES 188
vi
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TABLE OF CONTENTS (cont.) Page
10.1 APPENDIX A - RADIAN TECHNICAL NOTE 200-014-04
- CALCIUM SULFATE HEMIHYDRATE SOLUBILITY 189
10.2 APPENDIX B - RADIAN TECHNICAL NOTE 200-014-07 -
DISSOLUTION KINETICS LITERATURE REVIEW AND
SCREENING EXPERIMENTS 213
10.3 APPENDIX C - TRIP REPORTS OF SHAWNEE ANALYTICAL
SUPPORT 244
10.4 APPENDIX D - TEST DATA FROM WINDSOR PILOT
STUDIES 261
10.5 APPENDIX E - SAMPLE CALCULATIONS ON WINDSOR
TEST DATA 303
vii
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LIST OF TABLES
Page
TABLE 4-1 Experimental Results - Precipitation of
CaSO 1 •2H 2 0 35
TABLE 4-2 Experimental Results - Precipitation of
CaSO 3 ’½H 2 0 50
TABLE 4-3 Experimental Results - Limestone Dissolution
in Dilute HC1 Solutions 63
TABLE 4-4 Limestone Dissolution in Simulated Scrubber
Liquor 78
TABLE 4-5 Bench-Scale Spray Column SO 2 Sorption
Results 95
TABLE 5-1 Scrubber Operating Conditions 114
TABLE 5-2 Operating Conditions - Limestone Injection/
Wet Scrubbing Tests 117
TABLE 5-3 Operating Conditions - Limestone Tail-End
Addition Tests 121
TABLE 5-4 Chemical Analysis of CE Soluble Test Samples 122
TABLE 5-5 Total Sulfur Material Balance 129
TABLE 5-6 Vapor-Liquid Equilibrium Calculations for
Na 2 CO 3 Tests 131
TABLE 5-7 Total Sulfur Material Balance Summary - CE
Prototype Tests 17R-20R 136
TABLE 5-8 Limestone Injection Wet Scrubbing Tests -
Rate Calculation Summary 139
TABLE 5-9 Hold Tank Precipitation Rate Correlation
Injection - Wet Scrubbing Tests 142
TABLE 5-10 Marble Bed Vapor-Liquid Equilibrium
Calculations 146
TABLE 5-il Relative Mass Transfer Coefficients 146
TABLE 5-12 Prediction of Scaling Using Calculated
Relative Supersaturations 149
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TABLES (cont..) Page
TABLE 5-13 Total Sulfur Material Balance Summary -
CE Limestone Tests 152
TABLE 5-14 Rate Calculation Summary for Limestone
Tail-End Addition Tests 154
TABLE 5-15 Hold Tank Precipitation Rate Correlation
Tail-End Addition Tests 156
TABLE 5-16 Hold Tank Limestone Dissolution Rate
Correlation 160
TABLE 5-17 Relative Mass Transfer Coefficients 161
TABLE 5-18 Prediction of Scaling Using Calculated
Relative Supersaturations 165
TABLE 7-1 Results of Investigation to Determine Opti-
mum Number of Constants for Correlation 181
TABLE 7-2 Results of Correlation of 25-90°C Data 182
ix
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LIST OF FIGURES
Page
FIGURE 4-1 Reactor Configuration 31
FIGURE 4-2 Experimental System for Precipitation Rate
Study 32
FIGURE 4-3 CaSO •2HzO Precipitation Rate Versus
Relative Saturation 37
FIGURE 4-4a Seed Crystals for CaSO 2H2O Precipitation
Experiments 38
FIGURE 4-4b Product Crystals from Run 66 at Low Super-
saturation (1.02 x Ksp) 38
FIGURE 4-4c Product Crystals from Run 62 at Intermediate
Supersaturation (1.27 x K 5 ) 39
FIGURE 4-4d Product Crystals from Run 53 at High Super-
saturation (1.38 x K )
FIGURE 4-5 Comparison of Hypothesized Driving Force
Forms for CaSO •2H2O Precipitation (Seed
Batch No. 2) 41
FIGURE 4-6 Comparison of Hypothesized Driving Force
Forms for CaSOk•2H20 Precipitation (Seed
Batch No. 3) 42
FIGURE 4-7 Effect of Temperature and Agitation on
CaSOI. .2H20 Precipitation Rate 44
FIGURE 4-8 CaSO3½H20 Precipitation Rate Versus Rela-
tive Saturation 51
FIGURE 4-9a CaSO3½H20 Seed Crystals 52
FIGURE 4-9b Product Crystals from Run 18 at Low Super-
saturation (2.71 x K p) 52
FIGURE 4-9c Product Crystals from Run 15 at High Super-
saturation (3.55 x K 5 ) 53
FIGURE 4-9d Product Crystals from Run 15 Showing Surface
Nucleation on Seed 53
FIGURE 4-10 Comparison of Hypothesized Driving Force
Forms for CaSO 3 •½H 2 0 Precipitation 55
x.
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FIGURES (cont.) Page
FIGURE 4-11 Effects of pH,Temperature, and Agitation
on CaSO 3 • H 2 O Precipitation Rate 57
FIGURE 4-12 Numerical Approximation of Reactor Composi-
tion for Run 14 60
FIGURE 4-13 Limestone Dissolution Rate Versus Hydrogen
Ion Activity - Type 2 Limestone in Dilute
HC1 68
FIGURE 4-14 Normalized Dissolution Rate [ Rate/(a 0 = -
aC )] Versus Hydrogen Ion Activity-
Ty9e 2 Limestone in Dilute HC1 69
FIGURE 4-15 Effect of Limestone Type on Dissolution
Rate in Dilute HC1 71
FIGURE 4-16 Effect of Temperature on Dissolution Rate
in Dilute HC1 72
FIGURE 4-17 Effect of Stirring on Dissolution Rate in
Dilute HC1 74
FIGURE 4-18 Effect of Particle Size on Dissolution Rate
- Type 2 Limestone in Dilute HC1 75
FIGURE 4-19 Limestone Dissolution in Simulated Scrubber
Liquor 79
FIGURE 4-20 pH Electrode Response 86
FIGURE 4-21 Dissolution of Ca(OH) 2 Reagent in Deionized
Water 87
FIGURE 4-22 Dissolution of CaCO 3 Reagent in Deionized
Water 88
FIGURE 4-23 Experimental Apparatus 91
FIGURE 4-24 Diagram of Spray Scrubber Used in Lime
Dissolution Rate Study 92
FIGURE 4-25 Gas Phase Transfer Units Obtained as a
Function of the Scrubber Liquid Feed Rate... 99
FIGURE 4-26 NTU Values Obtained for Scrubbing Liquors
Containing < 0.3 wt.7 0 Solids 100
xi
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FIGURES (cont.) Page
FIGURE 5-1 Scrubber System Flow Sheet for Once-Through
Soluble Na 2 CO 3 Runs 105
FIGURE 5-2a Scrubber System Flow Sheet for Run 17R 106
FIGURE 5-2b Scrubber System Flow Sheet for Runs 18R-22R. 107
FIGURE 5-3a Scrubber System Flow Sheet for Tail-End
Addition Tests (Single Bed) 108
FIGURE 5-3b Scrubber System Flow Sheet for Tail-End
Addition Test (Double Bed) 109
FIGURE 5-4 Relative Mass Transfer Rate Vs. pH for
Soluble Tests 133
FIGURE 5-5 CaSO 3 Precipitation Rate in Hold Tanks for
Limestone Injection Tests 143
FIGURE 5-6 CaS0 Precipitation Rate in Hold Tanks for
Limestone Injection Tests 144
FIGURE 5-7 Relative Mass Transfer Rate Vs. pH for
Soluble Test and Limestone Injection Tests.. 147
FIGURE 5-8 CaSO 3 Precipitation Rate in Hold Tank for
Limestone Tail-End Tests 157
FIGURE 5-9 CaSO 1 . Precipitation Rate in Hold Tank for
Limestone Tail-End Tests 158
FIGURE 5-10 Comparison of Lab and Pilot Unit Limestone
Dissolution Rates 162
FIGURE 5-11 Relative Mass Transfer Coefficient Vs. pH... 164
xii
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ACKNOWLEDGEMENTS
The authors wish to acknowledge the assistance of
EPA personnel under whose guidance this program was carried
out. Mr. Julian Jones was EPA’s Project Officer on this
contract. We appreciate his cooperative spirit and understanding
during the conduct of this program.
xiii
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1.0 SUMMARY
Under EPA Contract No. 68-02-0023, Radian provided
technical assistance in several areas concerning the development
of the lime/limestone wet scrubbing process: (1) review of
Bechtel t s preliminary test plan for EPA ’s test facility at TVA’s
Shawnee Station; (2) laboratory studies concerning key reaction
steps; (3) engineering and chemistry support for pilot unit
studies at Combustion Engineering’s Kreisinger Development Lab-
oratory; and (4) trouble-shooting at the analytical system at
Shawnee.
L.l Shawnee Test Plan Review
Radian reviewed the preliminary Shawnee test plan pro-
posed by Bechtel in June 1971. The review was concentrated in
the two month period of June - July 1971 and involved an in-depth
examination of three Bechtel documents:
(1) Bechtel Corporation, “Alkali Scrubbing
Test Facility - Screening Experiments
for Venturi Scrubber System”, Progress
Report to APCO, Bechtel Corporation,
San Francisco, May 1971.
(2) Bechtel Corporation, t rAlkali Scrubbing
Test Facility - Mathematical Models for
Venturi Scrubber and After Scrubbers”,
Progress Report to APCO, Bechtel Corpora-
tion, San Francisco, February 1971.
(3) Bechtel Corporation, “Alkali Scrubbing
Test Facility - Outline of Preliminary
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Test Program for the Break-In Period”,
Report to APCO on Job No. 6955, Bechtel
Corporation, San Francisco, May 1971.
Based upon its review of these documents, Radian’s
primary areas of concern were:
(1) The proposed test plan was a highly
fractional factorial design. This
design placed a strong dependence upon
a good process model. The models proposed
had several questionable assumptions.
(2) Even if the proposed model were correct,
statistically significant conclusions
would be very difficult from the number
of experiments proposed. This is because
neglected effects would mask the calculated
effects.
(3) Further documentation of the test plan
basis was needed in several key areas to
establish its validity.
The test plan was modified somewhat to accommodate these criticisms.
1.2 Laboratory Rate Studies
Laboratory studies were conducted at Radian to measure:
(1) the precipitation rates of calcium sulfate and sulfite; (2)
the dissolution rates of lime and limestone; and (3) the solu-
bility product constant for CaSO 4 ½H 2 O. 1here possible, these
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results were correlated with process chemistry variables such as
ion activities, amount and size of crystal seeds, and temperature.
Experimental measurements of CaSO 4 2H 2 O precipitation
rates support the following conclusions.
(1) A “metastable region” bounded by a rela-
tive saturation of 1.3 - 1.4 times the solu-
bility product was observed. Below this
level of supersaturation, precipitation
occurs only on existing seed crystals.
Above this level, nucleation begins.
(2) The precipitation rate of CaSO 4 2H 2 O
within the metas table region may be
described by a rate expression of the
form
R = k • M (r-l) (1-1)
where R is the precipitation rate, k is the rate constant,
M is a term dependent upon the amount of solid phase present,
and r is the relative saturation.
For the seed crystal batches used in this study, the
rate constant was correlated using the Arrhenius relation:
______ = 2.1± .7 x 106 exp(-9600/T) (1-2)
where T is measured in °K.
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The kinetics behavior of CaSO 3 ½H 2 O is qualitatively
similar to that of CaSO 4 ’2H 2 0. Experimental results show that:
(1) The metastable limit for CaSO 3 ½H 2 0
nucleation is about three times the
solubility product. Above this level
of supersaturation, nucleation and
dendritic growth occur on the surface
of existing seed crystals. Scaling
on equipment surfaces was aLso noted
under these conditions. Pilot data seem
to indicate that scrubbers may be operated
free from calcium sulfite scale at
super saturations above three. Thus
calcium sulfite supersaturations of
three wouLd be a very conservative
design basis.
(2) Within the metastable region, CaSO 3 .½}1 2 0
precipitation is adequately described
by the expression
R = k M • (r—l) (1—1)
The rate was shown to be independent of
changes in mass and area of growing
crystals. For the seed crystals used in
this study
_______ = 7.3 x 10° exp(-l0,600/T) (1-3)
where T is measured in °K.
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Limestone dissolution rate experiments were conducted
in dilute HC1 solutions and simulated scrubbing liquors. In the
dilute HC1 test series, the following variable effects were noted.
(1) Limestone reactivity varied by as much
as a factor of three for the four stones
inves tigated.
(2) The temperature dependence of the disso-
lution rate corresponded to an Arrhenius
activation energy of about 14,000 calories!
g-mole.
(3) A significant agitation effect was seen
at high and low levels of temperature and
pH.
(4) The dissolution rate is approximately
inversely proportional to particle size.
The dissolution rate per unit of surface
area is thus nearly constant.
These experimental observations indicate that limestone
dissolution is probably limited by both surface phenomena and
liquid film resistance. General correlation of results in this
case would be particularly difficult.
Limestone dissolution rates in simulated scrubbing
liquor could not be related to the dilute HC1 test results in
any consistent fashion. Experimental results for these tests
showed that dissolution rates can be expected to be a strong
function of pH. Soluble magnesium and chloride, on the other
hand, do not appear to affect the dissolution rate in simulated
scrubber liquor.
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For purposes of process design estimates, the following
guidelines may be used.
(1) Limestone dissolution rates in a hold
tank environment (pH 6) should be on
the order of lx1O g-moles per minute
per gram of limestone for 60 micron
particles. The rate on a per gram of
stone basis is inversely proportional
to particle size.
(2) Limestone dissolution rates in a scrubber
environment (pH 5) should be 30 to 40
times the hold tank rate. Thus significant
limestone dissolution will occur in most
scrubbers in spite of the low liquid hold
up compared to that of a hold tank.
In view of the demonstrated complexity of limestone
dissolution rate correlation, laboratory evaluation of candidate
limestones is recommended as a standard design procedure. These
tests should be conducted using a liquor typical of design opera-
ting conditions for the hold tank and scrubber environments.
Although the lime dissolution experiments did not
successfully quantify the dissolution rate of lime in aqueous
solutions, the following conclusion may be drawn from the
qualitative results of this study:
(1) Subject to equilibrium constraints,
lime particles of a given size will
dissolve faster in aqueous solutions
than limestone particles of the same
size.
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(2) This intrinsic rate difference is
often enhanced by the fact that lime
particles are typically smaller than
limestone particles. This is particu-
larly true of commercially prepared
lime and limestone samples.
(3) Well-stirred process hold tanks containing
solid phase hydrated lime can probably be
assumed to be saturated with respect
to Ca(OH) 2 in the liquid phase.
(4) The dissolution rate of a typical lime
sample is so rapid that a significant
contribution to the total alkalinity of
the system can be expected to be supplied
by lime species which initially enter
a scrubber in the solid phase. The effects
of this rapid dissolution rate should be
taken into account whenever attempting to
model or design a lime scrubbing system for
SO 2 removal.
1.3 Pilot Unit Studies
Radian provided technical assistance during an EPA-
sponsored pilot program on Combustion Engineering’s 10,000 ACFM*
marble-bed scrubber in Windsor, Connecticut. Radian’s participa-
tion included test program design, on-site sampling and chemical
* Engineering units in this report are expressed in English
units. A list of conversion factors for determining metric
equivalents is given in Section 8.2 of this report, page 185.
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analysis, chemical analysis of test samples at Radian, and engi-
neering analysis of the test results. Key process rate steps
were measured.
Three types of pilot tests were performed. First,
scrubber performance was measured using Sixteen experiments in
which sodium carbonate was used as the alkali. Following these
tests, six limestone injection/wet scrubbing tests were per-
formed. Six limestone tail-end wet scrubbing tests were performed
to conclude the EPA/CE/Radian pilot program.
The following conclusions were drawn from the results
obtained in the soluble sodium carbonate tests:
(1) The liquor sampling and analytical
techniques applied were adequate to
investigate chemical processes occurring
in soluble sodium carbonate/wet scrubbing
systems.
(2) A vapor-liquid equilibrium approach of
95% can be obtained in single marble bed
with a high pH sodium carbonate scrubbing
liquor.
(3) Operating variables such as gas velocity
and temperature do not appear to have a
strong effect on the overall vapor-liquid
mass transfer rate. This may indicate that
the gas-film mass transfer rate does not
limit the overall vapor-liquid mass transfer
rate.
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(4) The correlation between overall mass transfer
rate and liquor pH exhibited in Figure 4-4
indicates that a liquid phase resistance is
a substantial portion of the overall vapor-
liquid mass transfer resistance.
From the results obtained in the limestone injection!
wet scrubbing tests the following conclusions were drawn.
(1) The slurry sampling and analytical
techniques applied in these tests ade-
quately revealed the chemical processes
occurring in limestone injection/wet
scrubbing systems. Difficulty was en-
countered in characterizing the marble
bed due to its non-uniform composition,
however.
(2) Operating variables such as additive
rate,flue gas flow rate, liquid to gas
ratio, and liquor flow rate appear to
affect the overall vapor-liquid mass trans-
fer rate jj?hrough their effect on the
operating pH of the marble bed. This
correlation between vapor-liquid mass
transfer and pH indicate that a liquid
phase resistance is a significant portion
of the overall vapor-liquid mass transfer
rate.
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(3) The precipitation rates observed in the
limestone injection/wet scrubbing tests
could be described by the same general
form as the rate correlation observed in
Radian laboratory research.
R = kM(r—l) ( 1-1)
Therefore, circulation of large amounts
of solids in the slurry increases the
precipitation of and decreases the super-
saturation of CaSO 3 and CaSO 4 in the
scrubbing system. The magnitude of sulfite
precipitation rate was considerably lower
in the pilot unit than in the laboratory
study, however. Sulfate precipitation
rates were comparable.
(4) Over one-half of the system additive
dissolution occurs in the scrubber in
spite of low liquid residence times. The
additive dissolution rate is apparently
a strong function of liquor p11.
(5) Safe supersaturation limits for scale-free
operation agree with those established in
the laboratory for calcium sulfate (1.3 -
1.4), but appear to be higher for calcium
sulfite. The limestone injection/wet
scrubbing system operated in a scale-free
condition with calcium sulfite super-
saturations up to 6-8.
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The data and calculations obtained for the six limestone
tail-end addition/wet scrubbing tests support the following
conclusions.
(1) The analytical and hold tank sampling
methods employed were adequate for
investigating important vapor-liquid and
solid-liquid reaction rates in the
process vessels. Poor results caused
by marble bed sampling probe problems
indicate the importance of very short
sampling times.
(2) The amount of CaSO 4 2H 2 O precipitation
in the scrubber is always a substantial
fraction of the total CaS0 4 2H 2 O pre-
cipitation for the system ( 50%) in
spite of the low liquid residence time
in the marble bed. This is presumably
due to high supersaturations and high
nucleation rates in the marble beds.
CaSO 3 ½H 2 O precipitation in the marble
bed is low, but significant ( 10%).
(3) Over 50% of the CaCO 3 dissolution in the
wet scrubbing system occurs in the scrubber
in spite of its relatively small liquid
hold up. This is due to the high driving
force for dissolution occurring in the
marble beds. This is consistent with
laboratory results showing a strong rela-
tionship between limestone dissolution
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rate and pH. Limestone dissolution rates
in the hold tank agree well with laboratory
results.
(4) There are significant amounts of precipita-
tion and dissolution occurring in the surge
tanks which should be taken into account in
pilot plant studies, and perhaps in process
design.
(5) Vapor-liquid mass transfer rates are
similar to those experienced in previous
slurry and soluble test series. Their
correlation with marble bed pH is again
significant. It is also evident that
there is a direct relationship between
the vapor-liquid mass transfer rates and
the number of marble beds. These facts
indicate that SO 2 removal is limited by
liquid phase mass transfer resistance and
by interfacial area, not by the equilibrium
partial pressure of SO 2 .
(6) Increasing the total scrubber liquid-to-
gas ratio decreases the sulfite super-
saturation significantly but does not
appear to affect the sulfate supersaturation.
One goal of the SO 2 scrubbing tests at Windsor was to
gain experience in the characterization of processes that may be
helpful during EPA ’s on-going prototype program at Shawnee.
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Several aspects of the sampling and data interpretation pro-
cedures used at Windsor were discussed as to their relevance to
the Shawnee tests. Other aspects, particularly those dependent
on reLative fl.ow rates, vessel configurations, and modes of
operation, would not be related. A major difficulty in re-
lating the two programs was the differences in test goals and
proposed data interpretation procedures.
1.4 Analytical Support for Shawnee
Analytical support for the Shawnee Alkali Scrubbing
Test Facility involved several trips to Paducah to correct
hardware and software problems in the Laboratory Analysis
System.
1.5 Solubility Product of CaSO 4 I ,O
In order to allow for a more complete and accurate
mathematical description of the precipitation of calcium
sulfate salts in lime/limestone wet scrubbing systems, the
solubility of calcium sulfate hemihydrate (CaSO 4 . H 2 O) was in-
vestigated. Solubility data for calcium sulfate hemihydrate
was collected from the literature and correlated. The fol-
lowing correlation form was selected:
-R gn Kr —81.826056 + 12.707705 nT (1-4)
+3429 .0616T’ + .054204619T
where R is the gas constant in calories/g-moLe °K, KT is the
solubility product constant and T is the absolute temperature
in °K. Equation (1-4) is based upon an investigation to
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to determine the optimum number of constants so as to result in
a correlation form having the Least number of terms but an error
still in accordance with the accuracy of the experimental data.
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0
2.0 INTRODUCTION
Limestone-based scrubbing processes are considered one
of the most promising means of controlling sulfur dioxide and
particulate emissions from fossil fuel-fired power plants. The
Environmental Protection Agency has sponsored a number of research
and development programs to accelerate the commercialization of
limestone scrubbing processes for stack gas cleaning. They are
presently conducting an extensive program to test a prototype
lime/Limestone scrubbing system at TVA’s Shawnee generating
station at Paducah, Kentucky with Bechtel as the primary en-
1” gineering contractor.
Radian has been actively involved in EPA’s lime/lime-
stone scrubbing programs for the past four years. The work re-
ported here represents the fourth major EPA-Radian contract. In
Radian’s first contract (CPA 22-69-138), a theoretical irtterpreta-
tion of the complex chemistry and chemical engineering aspects of
lime/limestone scrubbing processes was developed. Under Contract
“ No. CPA 70-45, Radian developed and exercised a process model of
lime/limestone scrubbing processes such that the sensitivity of
system performance to various process parameters was demonstrated.
Radian also provided technical assistance to EPA in a series of
pilot unit tests conducted at EPA’s Cincinnati laboratories under
the same contract. Under Contract No. CPA 70-143, Radian de-
veloped sampling and analytical chemistry techniques for deter-
mining the key chemical species in liquid and slurry streams of
lime/limestone scrubbing processes. These methods are being used
by TVA in the conduct of the Shawnee test program.
Under the present contract, Radian (1) reviewed the
preliminary test plan proposed by Bechtel in June 1971 for the
Shawnee program, (2) conducted laboratory studies to measure and
correlate key reaction steps, (3) provided technical support in
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the conduct of pilot studies at Combustion Engineering’s
Kreisinger Development Laboratory, and (4) performed trouble-
shooting tasks to insure proper operation of the analytical system
at Shawnee. Each of these task areas will be reported in a
major section of this report.
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3.0 REVIEW OF SHAWNEE TEST PLAN
EPA is currently conducting demonstration tests of the
lime/limestone wet scrubbing process at TVA’s Shawnee power
plant at Paducah, Kentucky. The purpose of these tests is to
demonstrate the operability and performance of lime/limestone
scrubbing systems and to obtain valuable design data for commer-
cial application of such systems. Bechtel Corporation was
responsible for the design and construction of this alkali
scrubbing test facility. In addition, Bechtel has primary
responsibility for directing the test program, including the
devising of an experimental plan which would effectively accom-
plished the program objectives. TVA was the constructor and is
responsible for the operation of the test facility.
Radian as part of EPA Contract No. 68-02-0023 was
responsible for reviewing a portion of the preliminary
Shawnee test plan proposed by Bechtel, which was aimed at the
development of mathematical models of the scrubbing facility.
This section of the report will summarize the key aspects of
Radian’s review of the Bechtel test plan.
It should be noted here that Radian’s review of the
Shawnee test plan essentially involved an in-depth examination
of three Bechtel documents:
(1) Bechtel Corporation, “Alkali Scrubbing Test
Facility - Screening Experiments for Venturi
Scrubber System”, Progress Report to EPA,
Bechtel Corporation, San Francisco, May 1971.
(2) Bechtel Corporation, “Alkali Scrubbing Test
Facility - Mathematical Models for Venturi
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Scrubber and After Scrubbers”, Progress Report
to EPA, Bechtel Corporation, San Francisco,
February 1971.
(3) Bechtel Corporation, “Alkali Scrubbing Test
Facility - Outline of Preliminary Test Program
for the Break-In Period”, Report to EPA on
Job No. 6955, Bechtel Corporation, San Francisco,
May 1971.
Radian’s review was concentrated in the two month period of
June-July 1971.
3.1 Background
The alkali scrubbing test facility at Shawnee consists
of three parallel systems. These systems were designed to permit
simultaneous testing of Venturi, Turbulent Contact Absorber (TCA),
and Marble Bed (Hydro-Filter) scrubbers. A six month break-in
period was proposed by Bechtel whereby each of the systems is
operated to familiarize personnel with plant performance charac-
teristics, define laboratory manpower requirements, and obtain
some preliminary test data. Screening experiments on each of
the scrubber systems were to follow the break-in experiments.
The major goal of the screening experiments as stated by Bechtel
was to obtain correlations of dependent variables such as SO
removal, particulate removal, and scrubber pressure drop with
the independent variables of the scrubbing system. A set of
primary experiments were to follow the screening experiments.
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The test plan proposed by Bechtel for the screnning
experiments using the Venturi scrubber system involved perform-
ing 80 experiments. The experimental plan was a statisticaLly
designed set of experiments using a fractional factorial design
which was intended to allow for computation of all first-order
effects and selected higher order effects.
Radian’s review resulted in criticisms regarding both
the statistical design utilized and the engineering aspects of
the program. Radian’s major comments in these two areas will
be summarized below.
3.2 Statistical Approach
The Bechtel screening experiments were based on a
fractional factorial experiment plan. The effects on a set
of desired output (criterion) variables of a number of different
factors were to be investigated simultaneously. Because of the
complexity of the Venturi scrubber system, there are a large
number of possibly significant independent variables (factors).
To completely determine the interactions of the factors, a
prohibitively large number of experiments would be necessary,
even if only two levels are to be considered for each factor.
A fractional factorial plan consists of performing only a por-
tion of the total number of experiments necessary to completely
determine the interactions.
The hazard of a fractional factorial test plan is that
the results may easily be misinterpreted, especially if the
process studied is not well understood. The results are obtained
in the form of “effects” of the interactions of the independent
variables. For a complete factorial design, a unique expression
relates the experimental measurements of the criterion variable
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to each possible interaction of the factors. For a fractional
replication, however, the same expression may be used to compute
the estimate of several interaction effects. Those interactions
which have the same effect expressions are said to be “aliases”
of each other.
Interpretation of the experimental results is made
possible by comparing expected interaction effects with a model
of the process studied. If the total effect of the aliases
of each significant interaction is known to be negligible, the
experimental results can be unambiguously interpreted. Thus,
effects in a fractional factorial experiment will be correctly
attributed to specific interactions only if the following con-
ditions are satisfied.
First, a model of the process studied must be exercised
to predict values of interaction effects. The interactions with
largest predicted effects are selected as the “significant
interactions” to be tested. The fractional factorial experiment
is then designed so that only “negligible” interactions are
aliased with the significant interactions. If the sum of all
aliased interaction effects is small compared with that signi-
ficant interaction effect, the experimental results can be
unambiguously interpreted. If the model is sufficiently accurate,
the unambiguous interpretation will be correct.
The factorial experiment plan proposed by Bechtel
involved thirteen two-level factors, one three-level factor,
and one four-level factor, for a total of 98,304 possible
combinations of factor levels. For the 80 experiment plan
proposed, the fractionality is 80/98,304, or approximately
1/1200. This means that each measured interaction effect is
aliased with about 1200 other interactions. A particular mea-
sured effect will therefore be the sum of the effects of 1200
aliased interactions. Interpretation of the effect as due to
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a particular interaction is based upon a process model predicting
correctly the sum of 1199 effects is negligible compared with
the l2OO !l interaction effect.
As may be seen from the above discussion, a highly
fractional factorial experiment design must be based on an
accurate process model if meaningful conclusions are to be
expected. For portions of the process in which the mechanisms
are in doubt, alternate plausible models should be developed.
significant interactions for alternate models should be computed
and tested in a factorial experiment. This would tend both to
decrease the masking of interaction effects and to provide a
method for choosing between alternate models.
In summary, the test plan proposed by Bechtel was
highly fractional. It was questionable whether the proposed
mathematical model could be demonstrated to be a good repre-
sentation of the physical system.
3.3 Engineering Aspects
In addition to the statistical points mentioned above,
several comments concerning the major engineering aspects of
the experimental plan are noteworthy. These comments are con-
cerned with (1) choice of variables, (2) selection of experimental
design, (3) ability to perform the proposed experiments, and
(4) determination of model and its constants.
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The proper choice of process variables is extremely
critical to the success of any experimental program. On the one
hand, all of the important variables must be included before
correlation of the experimental data is possible. If a signifi-
cant independent variable is omitted from the experimental
design, any significant effect of this “hidden variable” will
be attributed to other factors. Possible hidden variables in
the proposed program include composition of the coal and lime-
stone.
Bechtel had used a mathematical model to devise a
statistical experiment plan. However, a number of steps were
involved in selecting which interactions should be considered
in the fractional factorial design. Bechtel formulated mathe-
matical models. These models were then converted to test
equations. The resulting set of test equations were then
programmed on the computer. Simulation runs were performed
using the “test equation” programs and the results of these
simulation runs were analyzed to select the significant interac-
tions in a “sum of effects” representation. Thus, the validity
of experimental design depended not only upon the model assump-
tions, but it also depends upon the soundness of each of the steps
described above.
In reviewing the mathematical models presented
by Bechtel, it appeared they generally did a fairly com-
plete treatment consistent with technology available at the
time. One major discrepancy was their assumption of the vapor-
liquid mass transfer rate being controlled by the gas-film
resistance only. Experimental results from EPA’s in-house experi-
ments using a pilot Venturi scrubber (LO-027) indicate that
liquid phase composition had a significant influence upon the
v-2 mass transfer rate. This assumption was a serious limita-
tion of the Bechtel model. Radian recommended the model be
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appropriately modified. A second area of Bechtel’s mathematical
model which was potentially weak was their treatment of solids
dissolution and precipitation. Bechtel’s treatment needed re-
examination in three areas: (1) some of their assumptions were
questionable, (2) several plausible models should be postulated
and tested, and (3) additional details concerning their models
were needed.
The ability to conduct the experiments required by the
test plan is an important consideration. The process must be
operable in each of the modes designated in the design. The
independent variables must be controllable to a suitable level
of precision and the desired quantities must be quantitatively
measurable. Bechtel did not address these points in their
screening experiments test plan. One potential difficulty
in controlling significant variables involves the sequencing of
experiments to treat different batches of additives and coals.
Uncontrollable variations between batches could cause the inde-
pendent variables to vary significantly. The test plan did not
comment on this potential problem.
The Bechtel test plan involved performing 80 experiments
to determine the effects of 15 independent variables. Test equa-
tions were developed to determine the significant interactions
in the fractional factor design. These test equations involve 28
undetermined coefficients (B coefficients). Bechtel described a
method of determining these B coefficients that are based upon
considering “subsystems”. The concept of determining coefficients
in the model or test equations by dividing the process into its
component parts and then making selected measurements is a good
one from the standpoint of efficiency in constant determination.
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However, a number of specific points concerning the manner in
which Bechtel planned to determine constants was raised in the
Radian review.
3.4 Surrinary
Bechtel proposed a set of 80 experiments based
upon a fractional factorial design with 15 independent vari-
ables. Radian reviewed Bechtel’s proposed test plan with
respect to their statistical approach and with respect to the
engineering aspects of their design. The following conclusions
were drawn:
(1) The proper design of a highly fractional
factorial experiment plan is based upon
having a good understanding of the physical
phenomena occurring within the process and
expressing this in the form of a valid mathe-
matical model. It was questionable whether
this much faith should be placed in the model
proposed by Bechtel.
(2) Interpretation of highly fractional
factorial designs is extremely difficult
because many interaction terms are aliased.
It was questionable whether the proposed
mathematical model could be demonstrated to
be a good representation of the physical
system based upon Bechtel t s test plan for
the Venturi screening experiments.
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(3) The proper choice of process variables is
extremely critical to the success of an
experimental program. Bechtel’s choice of
variables could have resulted in some hidden
variables and in some unnecessary interac-
tion terms.
(4) The experimental design for “screening”
experiments should examine all of the
plausible models. Bechtel’s design
ignored the liquid-film resistance in
v-L mass transfer step and did not con-
sider all aspects of s- . mass transfer
phenomena.
(5) Each of the steps in developing a fractional
factorial design from a mathematical model
is critical to the validity of the resulting
design. Not enough information was available
to properly evaluate the validity of these
steps.
(6) The ability to conduct the experiments
(operating modes, adequate variable control,
and analytical measurements) required by the
test plan is an important consideration.
Bechtel did not specifically mention this point.
(7) One of the objectives of the proposed set
of “screening” experiments is to determine test
equation coefficients. Bechtel’s method of sub-
dividing the test equations system into component
parts was not necessarily consistent with their
test plan design.
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(8) All plausible models should be considered in
the interpretation of the experimental results.
Analysis of variance techniques can be used to
test hypotheses so that the proper model is
selected.
It is important to note that the Bechtel test plan was subsequently
modified, partly as a result of Radian’s comments. The revised
plan was reported by EPA at the Second International Lime!
Limestone Wet Scrubbing Symposium (EP-002). In addition,
the current Shawnee test program places more emphasis on
demonstration of reliable and economically attractive operating
conditions.
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4.0 LABORATORY RATE UDIES
The rates of three solid-liquid reaction steps are
known to be important in design and operation of lime or limestone
wet scrubbing processes for SO 2 removal. These steps are (1)
additive (lime or limestone) dissolution, (2) calcium sulfite
precipitation, and (3) calcium sulfate precipitation. Quantita-
tive prediction of process performance requires information
relating the rates of these reactions to important process design
parameters 0
Laboratory investigation of the kinetics of these
reactions was undertaken as a first step in developing a general
process design technique. The objective of this study was to
formulate a useful rate expression for each of these reactions.
4.1 Experimental Techniques
It is convenient to formulate a rate expression for
solid-liquid mass transfer in terms of measurable process vari-
ables. A suitable rate expression may be written in the form
of Equation 4-1.
R = k.M•O (4-1)
where R is the reaction rate of a given solid, k is a rate
“constant” which may vary with liquor temperatures, composition,
and transport parameters, M is a term dependent on the amount of
solid phase present, and 0 is some function of the actual and
equilibrium concentration of the dissolving species. The typical
experimental approach involves measurement of R at known or
constant values of M and/or 0. The rate constant k is then
calculated. Applicable parameters are varied over ranges expected
to prevail in a typical process and the measured rates or rate
constant correlated for use in large scale design.
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The reaction rate, R, is most cornnionly determined by
chemical analysis of the liquid phase to detect an increase or
decrease in concentration of the dissolving or precipitating
species. Alternately, the increase or decredse in weight of the
solid phase may be measured. The tItv II term is usually assumed to
be proportional to the exposed surface area of the solid phase.
This obviously may be difficult to quantify in experiments with
suspensions of many fine particles. For dissolution and precipi-
tation reactions, 0 is nearly always taken to be the difference
between the actual and equilibrium concentrations of the reacting
species, perhaps raised to some power.
In order to quantify R, M, and 0, a means of contacting
the two phases must be selected. Three categories generally
considered are fixed—solid/moving—liquid, moving—solid/fixed—liq-
uid (agitated only by the solid itself), and agitated—liquid!
suspended—solid. The first two techniques are generally used
in more fundamental studies where it is desirable to have quan-
titative descriptions of liquid velocity profiles and well
defined surfaces for dissolution. Since the present study is
intended for direct application to limestone scrubbing process
design where agitated tanks will be used, only the third technique
will be considered here. Quantitative application of data from
flow situations other than an agitated suspension does not appear
to be practical, given the present knowledge of phenomena involved.
There are at least three choices regarding experimental
operation of an agitated vessel. These are as follows:
a. batch_liquid/batch-solid,
b. continuous-liquid/batch-solid,
c. continuous-liquid/continuous-solid.
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The first of these is simplest from the operational standpoint
but the most complex in terms of data analysis. A characterized
batch of solids is introduced to a prepared solution and the
concentration of the liquor monitored with time. For slow reac-
tions, grab samples give adequate results. For faster rates,
in-situ measurement using ion electrodes or conductivity is re-
quired. Calculation of the rate involves differentiation of the
concentration versus time data as well as correction for any
significant changes in area of the solids during an experiment.
An additional complication can arise if the rate is both particle
size and area dependent as happens in some cases.
The continuous-liquid/batch-solid method is very
convenient for systems in which the change in the amount, area,
and size of solids is negligible during an experiment. Under
these conditions, a “steady state” material balance for the
liquid phase gives the rate directly without differentiation
of a concentration curve.
The third method is the most difficult to achieve
experimentally since continuous addition of solids is necessary.
It does, however, offer a true steady-state rate regardless of
changes in the solid mass, area, and size. The rate is calculated
directly from a steady state liquid or solid species balance.
For the present study, the continuous-liquid/batch-solid
method was selected. Subsequent experiments proved successful
for limestone dissolution and for calcium sulfite and sulfate
precipitation. The selected apparatus and technique were
not suitable for lime dissolution studies, however. A separate
approach was taken using lime. This is described further
in Section 4.5.
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One problem addressed in the present investigation
was design of an experimental apparatus permitting continuous
liquid throughput while retaining a well-agitated suspension of
small solid particles within the vessel. A successful method
was eventually devised to retain even very fine solids in sus-
pension during an experiment. A porous “Millipore” membrane was
fixed across the reactor effluent port. A combination of a very
large ratio of membrane area to reactor throughput and good
agitation succeeded in preventing solids from accumulating on
the membrane during a run. The flexibility and smoothness of
the membrane contributed to the success of this technique since
the agitation was sufficient to “ripple” its surface and dis-
lodge any solids before a cake could form.
The final reactor configuration is shown in Figure
4-1. A single 142 mi l1imeter membrane placed on a support
screen fixed to the bottom of the reactor was used for liquid
flow rates up to 400 milliliters/minute. For flows above this
and for experiments using low agitator speeds, a second membrane
was used at the top of the vessel.
The complete apparatus used to measure limestone
dissolution and CaS0 3 H 2 O or CaSO 4 2H 2 O precipitation rates is
shown schematically in Figure 4-2. Feed solutions are premixed
in two separate 16 gallon polyethylene tanks. Na 2 SO 3 , Na 2 SO 4 ,
and CaC1 2 were used as sources of sulfite, sulfate, and calcium
ions, respectively. Mg(OH) 2 , MgC1 2 , NaC1, HC1, and Ca(OH) 2 were
also used to adjust the concentration of various species in the
feed liquor. To prevent possible oxidation during sulfite
experiments, deionized water was deaerated by nitrogen sparging
before adding the reagents. The tanks were also fitted with
floating lids to minimize oxidation of sulfite ion by atmospheric
oxygen. The reactor was situated in a constant temperature bath
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“Mi hip ore”
Membrane
Temperature Control
Probe
5½” O.D. , ¼” Wall
Plexiglas Tube
Support
Screen
FIGURE 4-1 - REACTOR CONFIGURATION
Feed Liquor Port
0 Ring Seal
Soft
t)
3/8” Plexiglas
Sheet
Effluent Port,
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FIGURE 4-2
EXPERIMENTAL SYSTEM FOR PRECIPITATION RATE STUDY
TWO -LIT ER
STI RED
RE CTOR
N.)
EFFLUENT
TO ANALYSES
CONSTANT PRESSURE DROP
REGULATOR
HEATING
COILS
---------1
CONSTANT TEMPERATURE BATH
-------
and held at the desired experimental temperature by a controller
powering a 750 watt immersion heater. Each feed solution was
pumped through a separate train. Constant differential pressure
flow controllers maintained selected flow rates through precision
needle valves. The flows were measured by carefully calibrated
rotameters. Both feed streams passed through about ten feet of
316 S.S. tubing in the bath before entering the reactor. The
temperature within the vessel was held within about 0.5°C of the
set point during a run.
Each experiment was initiated by introducing a known
amount of solids to the reactor after it had been filled with
feed solutions. The reactor was then closed and the feeds
introduced as the desired flow rates. During a run, effluent
samples were taken at intervals to evaluate whether steady
state was reached. In most cases less than two residence times
were required to approach the steady state reactor composition.
The “steady state” reaction rate for each experiment
was calculated by straightforward material balance:
Reaction Rate (niole/min) = (4-2)
Feed Rate (L/min) x Feed Concentration (niole/L Ca or S)
- Effluent Rate (L/min) x Effluent Concentration (mole/L Ca or S)
An additional check was provided by a total solids material balance.
The amount of product solids for a run is easily determined by
emptying the reactor through the bottom port following shutdown
so that the solids are retained on the effluent membrane. After
air drying, the product cake is weighed and compared to the
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amount of solids introduced at start-up. The difference of
these weights is the time integral of the reaction rate. This
corresponds closely to the steady state rate multiplied by the
total run time since the reaction was found to approach the
steady state rate in a short period of time compared to the
total run time.
4.2 CaSO 4 2H O Precipitation
Experimental results for the CaSO 4 2H 2 0 system have
been summarized in Table 4-1. Calculated rates for the sulfate
experiments are based on the total sulfur (total S) species
balance in Runs 44-58 since the large excess of calcium intro-
duces high uncertainty in the total calcium (total Ca) balance.
An average of the total Ca and total S species balances was
used for Runs 59-77.
Supersaturations for CaSO .2H 2 were calculated
using the chemical equilibrium computer routine developed
under EPA contractCPA22-69-138 and subsequently revised
under contract CPA 70-45. The indicated relative supersatura-
tions are ratios of the calculated ion activity products for
each run divided by an equilibrium activity product calculated
by inputting chemical analyses of an equilibrium solution of
CaSOe2H 2 O to the same computer routine. This method of calcu-
lation minimizes the effect of errors in the activity coefficient
correlation used in the program. The ttexperimenta1 t values of
were 2.12x10 5 , 2.15x10 5 , and 2.19x10 5 at 45°, 400, and 35°C
respectively. These compare with values of 2.29, 2.34 and 2.38x
1O used in the program originally.
The effects of experimental variables on precipitation
rates are discussed below.
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TABLE 4-1
EXPERIMU4TAL RESULTS - PRECIPITATION OF CaSO 4 2H 2 0
S + Cs balances re used in Runs 59-71.
Total $ balance only in Runs 44-58.
Ca C l 1
Batch
No.
2
Feed Conc.
( iamo le/L )
294
Flow Rate
/ r a i n)
96
Feed Conc.
( mzaole/L )
25.0
U,
U,
Run
No.
44
Mount
of Seed
(g)
10.50
Na 1 S0
Temp.
1°c )
45
stirrer
speed
High
Steady State
Effluent Conc.
(rrnole/i)
Supersaturation
a
aCa+s.eSOeaflO
K 1 ,
Precipitation
Rate*
fmmole/g-niin)
.036
Flow Rate
(mi/mm)
123
Ca
127
S
12.3
1.23
47
10.55
“
288
“
41.0
“
“
“
124
14.5
1.41
.177
49
10.35
“
284
“
31.3
“
“
“
119
13.6
1.33
.084
50
10.47
“
284
“
36.2
“
“
“
119
14.3
1.39
. 126
52
10.35
‘
284
“
27.9
“
U
‘
120
13.1
1.29
.054
53
10.39
“
284
“
41.5
“
•
“
116
14.7
1.38
.181
54
10.35
“
290
“
22.2
“
“
“
125
11.5
1.15
.020
55
10.38
“
271
°
24.5
“
“
“
120
12.3
1.22
.031
56
10.40
“
274
“
26.4
‘ •
ti
“
116
13.0
1.28
.038
57
10.36
“
274
“
26.7
“
“
“
118
13.2
1.30
.038
58
10.29
“
274
“
30.9
“
“
“
116
14.1
1.37
.069
59
10.25
3
56.2
97
45.8
“
“
“
23.0
23.5
1.22
.0415
61
10.26
61.1
“
48.8
“
“
“
24.2
24.0
1.26
.0645
62
10.31
‘
63.2
“
50.7
“
“
°
25.0
24.1
1.27
.076
63
10.28
It
53 3
“
43.8
“
“
“
21.6
23.0
1.17
.0365
64
10.26
“
51.7
“
42.6
“
“
“
21.6
22.3
1.15
.0995
65
10.31
“
47 .9
“
39 .9
“
“
“
19.8
21.6
i.oa
.0215
66
10.28
“
44.8
“
37.0
“
I ’
‘
18.8
20.4
1.02
.013
71
10.23
“
53.2
‘
45.8
“
‘•
“
23.1
23.2
1.21
.030
73
10.32
4
50.3
“
45.2
“
“
Low
21.0
23.2
1.15
.0345
74
20.60
“
50.2
‘
44.5
“
“
High
20.0
22.5
1.09
.024
75
10.29
“
50.2
“
44.6
“
“
“
20.0
23.6
1.13
.034
76
10.26
“
49 .7
“
46.1
1
35
“
21.1
24.4
1.24
.023
77
10.29
Il
48.1
105
46.2
105
40
22.4
21.9
1.19
.029
* Average of Total
• S denotes total sulfur and Ca denotes total calcite.
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4.2.1 Metastable Limit for Nucleation of CaSO 4 2H 2 O
Previous investigators have developed the concept of
a metastable region for many crystal systems. This region is
bounded by the solubility curve for a particular compound and
a certain level of supersaturation below which crystal growth
will occur but additional nuclei will not form. Since nuclea-
tion potential and scaling may be closely related, it is
desirable to determine metastable limits for growth of CaSO 4 2H O
seed crystals without nucleation.
Calculated precipitation rates for CaSO 4 2H O at the
base temperature of 45°C have been plotted versus supersatura-
tion in Figure 4-3. Photomicrographs comparing seed crystals
with product crystals were used to detect the degree of forma-
tion of new crystals during a run. These photographs showed
that the rapid rise in CaSO 4 2H 2 O precipitation rates at relative
supersaturations of 1.3-1.4 is due to nucleation. This is
illustrated in Figures 4-4a through 4-4d.
4.2.2 Growth Rate Versus Supersaturation Within the
Metastable Region
Various driving force functions have been proposed or
used to correlate precipitation rates with supersaturation.
Intuitively, it is clear that an adequate driving force function
cannot be defined in terms of concentration of Ca , SOT, or
S0 in the solution. This follows from the fact that the thermo-
dynamic solubility constant is a product of ion activities
rather than concentrations. Thus, whether or not precipitation
will occur (i.e., whether or not the driving force function is
greater than zero) must be related to some comparison of the
actual ion activity product to the solubility product. A function
based on concentration would be valid only under conditions of
-36-
-------
.20
.18
0
0
U )
‘ 4 - I
m
I -i
00
0
a)
.1-I
0
. 1 -I
4J
. 1 -I
c i
U)
‘.1
p4
Seed Batch 2
.16
.14
.12
.10
.08
.06
.04
.02
0
1.0
FIGURE 4-3
Seed Batch 3
0
1.1 1.2 1.3 1.4 1.5
Relative Saturation
- CaSO 4 •2H 2 0 PRECIPITATION
SATURATION
RATE VERSUS RELATIVE
-37-
-------
0-50 = 500 Microns
FIGURE 4-4a
Li
SEED CRYSTALS FOR CaSO 1 . 2H 2 0 PRECIPITATION EXPERIMENTS
II ,
FIGURE 4-4b - PRODUCT CRYSTALS FROM RUN 66 AT LOW SUPERSATURATION
(1.02 x K 5 )
V 7
r- J
Vk•
-38-
-------
FIGURE 4-4c
21
PRODUCT CRYSTALS FROM RUN 62 AT
INTERMEDIATE SUPERSATURATION
(1.27 x K )
FIGURE 4-4d - PRODUCT CRYSTALS FROM RUN 53 AT HIGH
SUPERSATURATION (1.38 x K )
-39-
-------
constant ionic strength. It is known, however, that this is a
major variable in limestone wet scrubbing applications.
Recent literature (NA-033) suggests that the
precipitation kinetics of many slightly soluble ionic substances
may be correlated by a driving force function of the form:
= [ (ar a )” - Vii n
Here, a+ and a_ are the activities of the precipitating cation
and anion, and n_ the number of cations and anions in the
formula, and n the sum of n+ and n_. Thus, for CaSO 4 2H 2 O,
Equation 4-3 becomes (assuming the activity of water is one):
0 = [ (a a a 0 =)2 - K ] (4-4)
Figures 4-5 and 4-6 show plots of CaSO 4 ’2H 2 0
precipitation rate versus supersaturation. Two separate seed
batches possibly having different size distributions were used
for these runs so that each series must be considered indepen-
dently. In each plot, a function of the form given in Equation
4-4 has been drawn through a reference datum. The reference
run was selected on the basis of the best agreement between
the total Ca and total S species balances for all the runs in
each series. Also shown on each plot is a straight-line
representation of the data fitting Equation 4-5.
0 = a 5 a 50 = - K (4-5)
Since the CaSOe2H 2 O experiments were conducted at
relatively low supersaturations, the data are somewhat scattered.
Qualitatively, the linear driving force appears to offer a
-40-
-------
0
0
0
.16
a .14
0
.12
• j .10
. 1 -I
.,.4
• .-4
C)
14
p4
0
.06
.04
.02
0
1.0
FIGURE 4-5 - COMPARISON OF HYPOTHESIZED DRIVING FORCE FORMS
FOR CaSO 4 , 2H 2 O PRECIPITATION (Seed Batch No. 2)
.18
0
0
Equation
4-4
4-5
00
1
Relative Saturation
-41-
-------
4J
00
a
0
1 O8
c i .)
4 - I
o O6
.r4
4-I
..-1
FIGURE 4-6 - COMPARISON OF HYPOTHESIZED DRIVING FORCE FORMS
FOR CaSO 4 2H 2 0 PRECIPITATION (Seed Batch No. 3)
Equation 4-4
Equation 4-5
1.0 1.1
Relative Saturation
-42-
-------
better representation of the data at lower supersaturations.
The quadratic form follows the observed increase in precipita-
tion rate at higher supersaturations, but this curvature is
probably due to incipient nucleation rather than crystal growth.
Therefore, Equation 4-5 is a good representation of the precipitation
rate.
4.2.3 Effects of Temperature on CaSO .2H 2 O Growth Rate
Definite temperature effects on precipitation rate
were observed with both the sulfite and sulfate systems.
Temperature effects on chemical reaction rate constants are
normally correlated using the Arrhenius relationship
k = A exp (E*/RT) (4-6)
where k is the rate 1t constant’ 1 , A a temperature independent
constant, E* the so-called activation energy for the reaction,
R the gas constant, and T the absolute temperature. Temperature
effects for the CaSO 4 2H O system were investigated in a series
of runs using a new seed batch. These data are shown in Figure
4-7. For purposes of estimating an activation energy, precipita-
tion rates are assumed to be linear with relative supersaturation.
Calculations using the 45°C and 40°C plots result in E* = 20.5
kcal/gmole. The 40°C and 35°C comparison shows E* ‘ 17.5 kcal/
gmole for an average of about 19 kcal/mole. A value of 15.0
kcal/mole for E* of CaSO 1 •2H 2 0 was reported in a recent study by
Liu (LI-0l2).
-43-
-------
4 - i
•rl
.08
.06
0
1 -i
. 1- I
O4
w
I - ’
1.0 i:i
o 200 rpm
1600 rpm
45°C
o°c
12 1:3
Relative Saturation
FLCURE 4-7 - EFFECT OF TEMPERATURE AND AGITATION ON CaSOe2H 2 O
PRECIPITATION RATE
- 44-
-------
4.2.4 itation Effects
Nearly all of the precipitation experiments were
conducted with a high level of mixing in the reactor. In order
to screen for possible effects of agitation on the rates, a run
was conducted for each system at a stirring speed of about 200
rpm compared to the normal 1600 rpm. This low level was just
sufficient to maintain a good seed suspension in the vessel.
Results for the CaSO 4 2H 0 system were shown on the
previous plot (Figure 4-7). The difference in precipitation
rate between the 200 rpm and 1600 rpm runs at 45°C does not
appear to be significant.
4.2.5 Dependence of Precipitation Rate on Amount of Seed
With reference to the expression for the precipitation
rate given in Equation 4-1, the dependence of the rate on the amount
of seed crystal remains to be quantified. Experiments demon-
strating the effect of the initial amount of seed in the reactor
do riot provide a complete description of the seed-dependent
term in the rate expression. This procedure does not demonstrate
whether the r?te is proportional to the number, area, or mass of
seed crystals. The rates of many two-phase chemical reactions
have been assumed to be directly proportional to surface area,
but some hypothetical mechanisms for crystallization do not
necessarily lead to this conclusion. The dislocation theory of
crystal growth, for example, hypothesizes that growth occurs by
addition of ion pairs at the ends of screw dislocations, the num-
ber of which may remain constant as the area of a growing crystal
increases.
One method of distinguishing between number, area, or
mass-proportional rate mechanisms is to conduct an experiment
during which the amount of crystal precipitated is substantial
compared to the amount of initial seed. Under these circumstances,
-45-
-------
the present experimental procedure will result in a steady state
reactor concentration only if the rate is proportional to the
number of seed crystals rather than the area or mass.
Quantitative interpretation of these observations is
not straightforward. While the effluent concentration of the
reactants should change with time if the rate is area dependent,
the magnitude of this effect is not readily estimated. The fact
that the rate decreases significantly with concentration could
tend to offset an increase due to an area change, making the
net result difficult to detect. Also, the lag time inherent in
a continuous stirred tank reactor (CSTR) would lessen the rate
of change of the effluent concentration. In order to derive a
conclusion regarding crystal growth rate versus surface area, a
computer routine was written to approximate an unsteady state
material balance for the reactor.
The material balance for a well-stirred vessel with
reaction is given by
V = -R() (-)
where C is the concentration of the reactant of interest,
is the initial concentration, V the volume of the vessel, F
the flow rate, and R(C) the reaction rate (rate of precipitation).
For known initial conditions, C(t) can be estimated using
C(t + At) = C(t) + [ c - C(t)lAt - R(C ) (4-8)
For each successive time increment a new value of C(t) is
calculated using a precipitation rate R(C) evaluated at the
previous increment. For purposes of this calculation
-46-
-------
the precipitation driving force given by Equation 4-5 in terms
of individual ion activities was reformulated in terms of
concentration:
R(C) = k A 0 ( C 2 - K ) (4-9)
The factor V 2 was established as a function of C so that
V 2 C 3 = aCa aSO= - (4-10)
over the range of concentrations experienced. This was done
so that the complete individual ion activity calculation need
not be executed at each time increment in the calculation.
The product k A 0 was calculated from the experimental
precipitation rate. During a computer simulation of the reactor,
this product could either be held constant or increased according
to the increasing area of the seed crystals to compare hypothe-
sized rate forms.
Numerical results for growth of CaS0 4 •2H 0 showed
that the expected change in reactor effluent concentration
versus time caused by an increase in seed area was within the
accuracy of analytical techniques used. This is a consequence
of operation near saturation. Even a small percentage change
in composition in this region represents a large change in pre-
cipitation driving force. Thus, no conclusive evidence regarding
the size dependence of CaSO 4 •2H 2 0 growth rates could be obtained
with the present experimental method.
-47-
-------
4.2.6 Conclusions
Experimental measurements of CaSO ,.2H 2 O precipitation
rates support the following conclusions.
A “metastable region” bounded by a relative
saturation of 1.3 - 1.4 times the solubility
product was observed. Below this level of
supersaturation, precipitation occurs only on
existing seed crystals. Above this level,
nucleation begins. This phenomenon was
verified in the Windsor pilot unit studies
(see Section 5.4.4).
The precipitation of CaSO . 2H 2 0 within the
metastable region may be described by a
rate expression of the form
Rate (g-mole/min) = k . M . (r-l)
where k (g-mole/gram minute) is a temperature
dependent rate constant, M (grams) is the mass
of seed crystals, and r is the relative
saturation defined by the ratio of the
activity product and solubility product for
the precipitating species. For the seed
crystal batches used in this study the rate
constant was
k (g-mole/gram-minute) = 1.4-2.8 x 1O exp _(E*/RT)
where: E’ = 19,000 calories/g-mole,
R = 1.98 calories/g-mole °K,
T = temperature, °K.
-48-
-------
The smaller seed crystals in Batches 3 and
4 provided a higher reactivity per unit
weight than those of Batch 2.
4.3 CaS0 3 ¾H 2 O Precipitation
A series of experiments similar to those described in
Sections 4.1 and 4.2, was carried out using calcium sulfite
seed crystals. CaSO 3 %H 2 O is the other major precipitating
species of interest in limestone scrubbing processes. In general,
the kinetic behavior was similar to the CaS0k 2H0 system.
Experimental results are summarized in Table 4-2. All of
the sulfite precipitation rates except Runs 13, 14, and 20
are an average of the total Ca and total S calculations.
No unreasonable differences between these two values were
noted. Important variable effects are discussed below.
4.3.1 Netastable Limit for Nucleation of CaSO 3 ½H 2 0
Figure 4-8 is a plot of experimental CaS0 3 ½H 2 0
precipitation rates versus relative saturation. A very
rapid increase in rate occurs at a supersaturation of about
three times the solubility product. Photomicrographs of
seed and product crystals from runs at various supersaturations
were again compared.
Figures 4-9a, b and c are phototnicrographs of
CaSO 3 ½H 2 0 seed and product crystals from Run 18 at a
supersaturation (2.71) below the sharp increase in the rate
curve and Run 15 at a supersaturation (3.55) above the
increase in the rate curve. These again show that the seed
crystals experience regular growth below a certain critical
level of supersaturation but that nucleation predominates
-49-
-------
TABLE 4-2
rvnrflTMflI?AI DrCIIT te — DDLPTDYPAPTfltJ
OP CaSOs ½Ha0
Run
No.
7
10
13
14
15
16
‘ I ,
17
18
20
21
22
25
28
Amount
of Seed
(R)
10.26
10.35
10.27
10.25
1.00
U I
I I
I I
Na;50 3 •
Feed Cotic.
(mrrsolel L)
SO !Qa_
5.58 0.52
6.35 0.76
137
“ 18.85 0.30
12.25
7.54 0.16
5.82
3.81 0.15
“ * *
4.19 0.22
35.7 2.0
36.5 2.6
3.69 0.41
Precip itation
Rate**
( uimole/g-mi n )
0.041
.048
.125
.191
.901
.529
.301
.121
.108
.147
.531
1.17
.106
* Analyala not made.
** Average of total sulfur and total calcium balancea.
• SO denotes total aulfite sulfur, S0 denotes total sulfate sulfur, and Ca denotes total calcium.
Feed
Flow Rate
( ml/m in )
125
II
Steady State
Effluent Conc.
(mole/a)
Supersaturation
5 Catf 5 sorto
CaCla
Feed Conc.
( mole/ I )
5.42
6.36
*
*
9.96
7.92
5.85
4.10
4.04
451
364
380
4.17
( ‘C)
45
Speed
high
Ca
1.19
SO,
0.94
Q _
*
I I , ,
1.69
“
“
1.17
1.14
0.42
1.91
“
“
1 93
1 32
39
2.68
II
•II
1.79
1.62
.11
2.92
“
“
1.54
2.35
.01
3.55
“
“
1.85
1.64
.09
3.34
“
“
1.80
1.49
.14
3.14
It
“
1 63
1 28
15
2.71
50
“
159
109
21
2.26
40
“
1.67
1.41
.20
3.06
45
“
15.9
14.9
2.0
2.63/3.95
“
“
14.2
13.9
1.1
4.35
•
low
1.64
1.18
0.47
2.51
-------
1.0
.90
8
4J
•r l
cu .70
1 - 4
tic
a)
0
.60
a)
U
Cu
ci .50
C
0
- ‘-4
U
.40
o .30
S
C l ,
Cu,
0
.10
0
FIGURE 4-8 - CaSO,’%H 2 0 PRECIPITATION RATE VERSUS RELATIVE
SATURAT ION
Definite Scaling
on Reactor Surfaces
-51-
-------
FIGURE 4-9a
S.
1 t
I
:
I
CaSO 3 ½H 2 0 SEED CRYSTALS
0-50 = 500 i
_ A
FIGURE 4-9b PRODUCT CRYSTALS FROM RUN 18
AT LO 1 SUPERSATURATION (2.71 x
0-50 = 5O0 .i
K)
sp
4 1
1’
40
•1
-52-
-------
5°
.111
(‘S
PRODUCT CRYSTALS FROM RUN 15
AT HIGH SUPERSATURATION (3.55 x K 8 )
0-50 = 500i.i
FIGURE 4-9c
o Ho 20..
/IIiIsIIIsi IIIIIIIjjIjlI /;IIIi:lj
FIGURE 4-9d
PRODUCT CRYSTAL FROM RUN 15
SHOWING SURFACE NUCLEATION ON SEED
0-50 =
-53-
-------
above this level. Note that nucleation in the CaSO 3 ½H 2 0 occurs
as formation of new growth sites on the seed surfaces rather
than new smaller crystals. This phenomenon is easily seen
in Figure 4-9c as dark areas on the previously translucent
seed. Figure 4-9d is a photograph of a single seed crystal
cluster with surface nucleation at higher magnification.
During Run 15, definite scaling was noted on all
surfaces of the reactor. This scale was particularly ad-
herent to the 316 S.S. material and to a lesser extent to
the Plexiglas surfaces.
In summary, the CaSO 3 .½H 2 0 results showed that the
seed crystals experience regular growth below a certain
critical level of supersaturation but that nucleation
predominates above this level. Nucleation of CaSO 3 ½H 2 O
occurs as formation of new growth sites on the existing
seed surfaces rather than new smaller crystals as in the
case of CaSO 2H 2 O.
4.3.2 CaSO 3 H O Growth Rate Versus Supersaturation
Within the Metastable Region
The experimentally observed precipitation rates for
CaSO 3 H 2 O are compared with hypothesized driving force expres-
sions in Figure 4-10. As in the CaSO 4 2H 2 O comparison, the
curves were driven through a datum having the best agreement
between total sulfur and total calcium balances.
-54-
-------
.10
0
0
Equation 3-4
0
tion 3-5
.09
.08
0
.06
a)
.05
.-i .04
0 . .
Q
c i)
o .03
Ni
0
c .
0
.01
0
FIGURE 4-10 - COMPARISON OF HYPOTHESIZED DRIVING FORCE
FORMS FOR CaS0 3 . H 2 0 PRECIPITATION
Relative Saturation
.0
-55-
-------
The linear driving force function as indicated by Equa-
tion 4-5 is again seen to offer a somewhat better fit for data at
low supersaturation. Neither form is adequate above a relative
supersaturation of about 3.0 where nucleation becomes significant.
The observed curvature in the rate above a relative supersatura-
tion of about 2.5 probably is due to an increasing contribution
from nucleation in addition to simple crystal growth.
Because of the bisulfite-sulfite equilibrium shift,
calculated values of CaSO 3 supersaturation can be extremely
pH sensitive in acid regions. For this reason, most of the
experimental investigation of CaSO 3 H O precipitation was con-
ducted in slightly alkaline liquors where nearly all of the
total sulfite (total SO 2 ) in solution was in the form of so;.
To check the validity of the observed rate curve in more acid
regions, two runs were conducted at low pH levels. The pH of
the reactor was adjusted by adding HC1 to the CaC1 2 feed solution.
Figure 4-li shows the results of these acid runs. Two
data points bracketing the neutral rate curve are given for Run
22. These correspond to a measured pH range of 4.9 to 5.1
during this experiment and demonstrate the sensitivity of calcu-
lated sulfite saturations to pH variations. An improved
technique for determining the reactor pH was used in Run 25.
A constant pH of 5.22 was observed throughout this experiment.
The resulting data point is reasonably close to the neutral
solution rate curve. The driving force function and activity
calculations appear to extrapolate well over a wide range
of liquor compositions.
-56-
-------
A denotes acid solution
1 -i
Cu
I - .
U
0
U
4.1
0
1-I
•rl
C.
-1
U
U
I-i
0
C l
0
C-)
.0
Relative Saturation
FIGURE 4-11- EFFECTS OF pH,TEMPERATURE, AND AGITATION ON
CaS0 3 H 2 O PRECIPITATION RATE
o denotes temperature
other than 45°C
i denotes low stirring 25
speed (pH=5.2)
22
(pH = 5.1)
.6
Neutral Rate
Curve
.4
A22
(pH = 4.9)
20
(5O°C)
0
1.0
3.0
4.0
—57-
-------
4.3.3 Effects of Temperature and Agitation on CaSO 3 .½H 2 0
Growth Rate
Results of CaS0 3 H 2 0 experiments at temperatures
other than 45°C and at a low level of agitation are also pre-
sented in Table 4-2 and Figure 4-11. As in the CaSO 4 2H 2 0
experiments there was no significant agitation effect with the
CaS0 3 H 2 0 system. Run 28, conducted at 45°C and 200 rpm, was
shown in Figure 4-11. Its rate is identical to the 1600 rpm
45°C rate curve within experimental error.
Temperature effects are again significant. Comparison
of Run 20 at 50°C to the 45°C rate gives E 19.8 kcal/gmole.
A similar calculation with Run 21 at 40°C gives E* 22.5 kcal/
gmole for an average of about 21 kcal/gmole.
The relatively high estimated activation energies and
absence of agitation effects for both the sulfite and sulfate
systems indicate a chemical reaction limited rather than a dif-
fusion limited mechanism. A conservatively estimated mass
transfer coefficient using literature correlations indicates a
diffusion rate at least four times the observed rate.
4.3.4 Dependence of CaSO 3 ½H 2 0 Precipitation Rate on Amount
of Seed
As discussed in Section 4.2, a growth rate dependence
on crystal size or area should result in a change in reactor
effluent concentration with time. Although this change was
estimated to be below analytical detection for the sulfate
experiments, it is significant for the sulfite data since these
experiments were conducted at much higher relative saturations.
-58-
-------
Runs 13 and 14 of the CaSO 3 ½H O series were conducted
over periods of 75 minutes during which the mass of the seed
crystals in the reactor increased by factors of about 2.3 and
2.8, respectively. This corresponds to an increase in seed area
of about 757 for Run 13 and lOO7 for Run 14. In spite of this,
the reactor effluent composition appeared to be constant with
time, indicating that the rate is apparently independent of
total surface area for a given batch of seed.
Figure 4-12 shows the results of computer simulations
for the crystallizer based on conditions for Run 14. For the
steady state case, the rate constant was held constant. For the
unsteady state case,,it was increased in proportion to the area
of the growing crystals.
These numerical results show that the reactor effluent
composition would decrease about 15% over the period from 15
minutes to 75 minutes during a run if the rate were proportional
to the seed area. A decrease of this magnitude should be easily
detected. No such decrease was observed during Run 14. Thus,
the growth rate of CaSO 3 4H 2 0 seed crystals appear to be indepen-
dent of surface area.
4.3.5 Conclusions
The kinetics behavior of CaSO 3 •½HaO is qualitatively
similar to that of CaSO 2H 2 O. Experimental results show that:
the metastable limit for CaSO 3 3 H 2 O
nucleation is about three or four times
the solubility product. Above this
level of supersaturation, nucleation
and dendritic growth occur on the
-59-
-------
10
,-1
0
0
C
Cu
07
Co
0
H 6
0
0
4J
4 - i
Q)
C-)
0
0
4 -i
w
4 3
2 Steady State
Unsteady State
1
0
0 10 20 30 40 50 60 70
Time - minutes
FIGURE 4-12 - NUMERICAL APPROXIMATION OF REACTOR COMPOSITION
FOR RUN 14
-60-
-------
surface of existing seed crystals.
Scaling on equipment surfaces was
also noted under these conditions.
This phenomenon was not substantiated
during the Windsor pilot tests (see
Section 5.4.4).
within the metastable region, CaSO 3 ¾H 2 O
precipitation is adequately described
by the expression
Rate (g-mole/min) = k . (r-l)
where k (g-mole/gram minute) is a
temperature-dependent rate constant,
M 0 (grams) the initial mass of seed
crystals, and r is the relative
saturation as previously defined. The
rate was shown to be independent of
changes in mass and area of growing
crystals. For the seed crystals
used in this study
k (g-mole/gram-minute) = 7.3 x 108 exp (_E*/RT)
where E* = 21,000 calories/g-mole.
-61-
-------
4.4 Limestone Dissolution
A literature review conducted prior to this experimental
study (see Radian Technical Note 200-014-07 in Appendix B of this
report) suggested that a kinetic expression describing limestone
dissolution under conditions typical of a limestone scrubbing sys-
tern could be quite complex. The dissolution rate behavior of a
solid which reacts with the solvent liquor can be a strong function
of liquor composition. Not only can the overall rate vary markedly
with liquor composition, but the dissolution mechanism or rate
limiting step may also change.
Two basic series of limestone dissolution experiments
were completed. The initial group of tests used simple dilute
HC1 solutions as the feed liquor. Effects of temperature, agita-
tion, pH, limestone type, and particle size were screened. The
second test series used synthetic liquors typical of those en-
countered in a closed-loop limestone scrubbing operation.
Dissolution rates more suitable for design application were
obtained in these experiments.
4.4.1 Limestone Dissolution in Dilute HC1 Solutions
Results of dissolution experiments using dilute HC1
feed solutions are summarized in Table 4-3. These runs covered
a pH range from 4.9 to 8.6. Important experimental parameters
shown in this table are explained briefly below.
Limestone Type - Four different limestone types
were used during the HC1 test series. Types 1
and 2 were locally available high-calcium lime-
stones. Types 3 and 4 were obtained from Dr. D. C.
Drehmel of EPA. Type 3 is a hard calcite and 4 a
soft marl. The petrographic and chemical character-
istics of these stones were described by Drehmel in
-62-
-------
TABLE 6-3
EXPERIM ff AL RESULTS - LIMESTONE DISSOLUTION IN DILUTE HC1 SOLUTIONS
Equilibrium
Activity
(emioie/ z)
Run
o.
Temp.
(CC)
Limestone
wt.(g)
Approx.
Mean
Particle
Size
(microns)
Stirrer
Speed
(RPM)
Feed
Flow
(mi/mm)
HC1 Conc.
(mmoles/L)
Effluent
Concentration*
(mmolefL) -
Activity
(mmole/L)
Relative
Saturation
aCa4_facxr
Dissolution
Rate (mmole/
g-mtn)
Frac cion
of Sample
Dissolved
at 3i
Equilibrium
Solubilit’.
( nmio le/1)
L_ Ca
C& CO ’
Ca
CO
14
50
1 5
60
.4000
400
0.500
6.50 .365
.262
.313 3.4lxlO
6.6x10 3
.029
.04
.42
4.3 x10 3
.51
15
50
1 5
60
—1000
400
0.500
6.70 .346
.293
.305 6.92x1O
i.i i 0 _a
.028
.04
.42
4.3 x10 3
51
16
50
1 5
60
—1000
400
0.790
6.35 .463
.395
.387 2.93xlO
6.2x10 3
.037
.06
.62
2.9 xlO
.78
17
50
1 5
60
—.1000
400
0.790
6.30 .449
.401
.376 2.51x10 6
5.2x10 3
.036
.05
.62
2.9 x10 3
.78
15
25
1 5
60
—1000
400
0.380
6.05 .239
.259
.212 4.63xlO
2.0x10’
.019
.03
.34
1.3 x10’
.40
19
25
1 5
60
—1000
400
0 380
6.05 .245
.278
.217 4.74x10’
2.1xi0 4
.020
.03
.34
1.3 xlO
.40
20
50
2 5
60
—1000
400
0.240
7.65 .245
.269
.214 7.49x10 4
8.8xlO
.020
.03
.24
7.6 x10 3
.28
21
50
2 5
60
—1000
400
0.240
7.80 .204
.241
.180 9.96x10 4
9.9x10’
.016
.02
.24
7.6 x10 3
.28
23
27
3 5
60
1000
400
0.247
6.40 .204
.246
.182 l.58x10’
6.4x10 4
.0165
.02
.245
1.8 x10
.29
24
27
3 5
60
850
400
0.247
6.00 .167
.251
.151 3.80x10’
1.3x10 4
.0135
.02
.245
1.8 x [ 0
.29
25
48
3 5
60
1000
400
0.207
8.25 .221
.247
.193 2.78xl0
3.0x10’
.0175
.03
.218
8.25x10 3
.26
27
50
3 5
60
1000
400
0.193
7.45 .225
.279
.198 4.79x10’
5.2x10
.018
.03
.210
8.60x10 3
.24
28
49
3 5
60
850
400
0.193
7.10 .206
.229
.182 1.62x10’
1.6x10 3
.0165
.02
.210
8.60x10
.24
I
29
50
4 5
60
1130
400
0.199
8.60 .237
.253
.205 6.27xl0
7.1x10’
.019
.03
.213
8.45x10 3
.25
I
30
32
26
50
4 5
4 2
60
60
1130
1130
400
400
0.199
0.341
8.50 .237
6.30 .251
.302
.216
.208 4.29x10 3
.220 j.45x10’
l.9x10 1
1.8x10 3
.019
.050
.03
.07
.213
.307
2.06’cIO’
5.90x10 3
.25
.36
33
50
4 2
60
815
400
0.341
5.70 .206
.126
.183 8.68x10’
8.8xl0
.041
.06
.307
5.90x10 3
.36
35
50
2 10
60
1100
200
8.50
5.04 4.01
4.13
2.51 1.62x1O
2.25x10 3
.080
.24
3.42
5.28x10’
6.16
36
50
2 10
60
1100
100
8.56
5.22 4.18
4.19
2.59 3.65xlO’
5.24x10 3
.042
.25
3.42
5.28x10’
6.20
37
50
2 10
60
1100
100
7.11
5.30 3.46
3.61
2.22 4.46x 10’
5.50x10 3
.0345
.21
3.05
5.93x10 4
5.31
38
50
2 10
60
1100
100
4.80
5.47 2.37
2.49
1.63 6.43x10’
5.79x10 3
.024
.14
2.35
7.69x10 4
3.84
40
50
2 5
60
1100
200
.841
5.90 .688
.69
.560 l.05x10
3.27x10 3
.0275
.08
.645
2.83x10’
.82
41
50
2 5
60
1100
250
.841
5.74 .649
.62
.532 5.00x10
1.47x10 3
.0325
.08
.645
2.83xl0
.82
42
50
2 5
60
1100
300
.841
5.60 .614
.62
.506 2.80x10’
7.86x10 4
.037
.07
.645
2.83x10 3
.82
43
50
2 5
60
1100
200
1.63
5.33 1.09
1.09
.847 1.55x10’
7.26x10 4
.0435
.13
1.09
l.65x10 3
1.51
64
50
2 5
60
1100
200
1.63
5.38 1.11
1.05
.860 1.85x10’
8.82x10 4
.0445
.13
1.09
l.65x10 3
1.51
45
46
50
50
2 5
2 5
60
60
1100
1100
200
250
.454
.452
6.50 .512
6.25 .475
.53
.45
.427 6.77x10
.400 2.52x10’
1.6i x1O 5
5.58x10 3
.0205
.024
.06
.06
.385
.384
4.70xl0
4.72x10 3
.46
.46
47
50
2 5
60
1100
100
2.86
5.28 1.38
1.38
1.03 1.57x10’
8.95x10 4
.0275
.16
1.65
l.10x10 3
2.92
49
50
2 5
60
1100
150
2.86
4.88 1.35
1.35
1.01 2.59x10’
1.45x10
.0405
.16
1.65
1.l0x10 3
2.92
* Ca denote, total calcL* concentration and CO , denote, total carbonate concentration.
-------
TABLE 4-3 - EXPERIM TAL R S1JLTS -
LIMESTONE DISS0U1 ION IN DILUTE MCi SOLUTIONS (cont.)
aun
.o
Temp.
(CC,
Limestone
Wt.(g)
Approx.
Mean
Particle
Size
(microns)
Stirrer
Speed
(RPM)
Feed
Flow
(mi/mm)
HCI Conc.
(rnmoles/L)
Effluent
Concentration
(mmole/L)
Activity
(mrnole/L)
Relative
Seturitton
aca++aCO.
K,
Dissolution
Rate (mmoie/
a-m m
Praction
of Sample
Dissolved
at 3r
Equilibrium
Acti ’ity
Equtlibriur
SolubLIir
jrmnole/t)
(mmole/L)
Ca ’ co
.2 i_ Ca
QL ..
Ca CO
50
50
2
7.5
60
1100
150
2.86
5.18 1.38
1.38
1.03 1.01x10’
5.77x10’
.028
.11
1.10x10 3
51
50
2
10
60
1100
150
2.86
5.43 1.44
1.44
1.07 3.15x10’
l.86xl0
.022
.09
1.65
2.92
52
50
2
5
60
1100
200
1.58
5.44 .811
**
.645 1.86x10’
6.63x10 4
.032
.10
1.65
2.92
53
50
2
5
60
1100
250
1.58
5.42 .814
**
.647 l.7l.lO
6.13x10’
.04L
.10
1.07 l.69x10 3
1.47
5’
50
2
5
60
1100
300
1.58
5.35 .793
**
.632 l.23x10’
4.30x10’
.048
.10
1.07
I.69x10 3
1.47
55
SO
2
3
60
1100
200
1.58
5.00 .774
.619 2.55xl0’
8.74x10
.052
.15
1.07
1.47
56
50
2
4
60
1100
200
1.58
5.38 .811
**
.645 l.43x10’
5.12x10 4
.041
.12
1.07 l.69xlO
1.47
57
50
2
7
60
1100
200
1.58
5.60 .838
**
.664 3.78x10’
1.39x10’
.024
.07
1.07 l.69xl0 3
1.47
65
50
3
4
60
1100
250
1.64
5.40 .855
**
.677 l.65x10’
6.17x10 4
.053
.13
1.07 l.69x10’
1.47
66
50
3
4
60
1100
300
1.64
5.02 .831
--
.660 2.99x10’
1.09x10 4
.062
.12
1.10 1.64x10 3
1.51
67
50
3
4
60
1100
200
1.64
5.20 .812
**
.646 6.52x10’
2.33x10 4
.041
.12
1.10
1.51
68
50
3
4
60
1100
200
1.64
5.50 .858
**
.678 2.54x10
9.53x10
.043
.13
1.10
1.51
72
50
2
5
-325/4400
mesh
1100
300
1.72
4.89 .790
**
.629 1.59x10’
5.53x10 ’
.047
.09
1.10 1.64x10’
1.16 1.58x10 3
1 51
1 58
73
74
50
50
2
2
5
7
“
•
1100
1100
200
200
1.72
1.72
5.20 .793
5.46 .817
**
**
.631 6.37x10’
.647 2.04x10’
2.22x10’
7.30x10 4
.032
.023
.09
.07
1.14 1.58x10 3
1.14 1.58’c10 3
1.58
1.58
75
85
86
87
50
50
50
50
2
2
2
2
5
5
5
3
‘
<5
<5
<5
1100
1100
1100
1100
250
200
300
200
1.72
1.63
1.63
1.63
4.73 .853
6.3* 1.07*
6.3* 1.07*
6.3* 1.07*
**
**
**
**
.676 8.31x10’
.82 7.0 x10 5
.82 7.0 x10
.82 7.0 x10 5
3.11x10 ’
3.2 x10
3.2 x10 5
3.2 x10
.043
.043
.064
.071
.10
.13
.13
.14
1.14 1.58’c10
1.09 1.65x10 3
1.09 1.65x10°
1.09 1.65x10 3
1.58
1.51
1 51
1.51
88
50
2
5
35
1100
300
1.63
5.26 .84
**
.67 8.79x10’
3.2 x10 4
.040
.08
1.09 1.65x10 3
1.51
89
50
2
3
35
1100
200
1.63
5.19 .82
**
.65 6.30x10’
2.3 x10 4
.043
.13
1.09 1.65x10 3
1 51
90
50
2
5
35
1100
200
1.63
5.50 .88
**
.69 2.60x10’
1.0 x10
.028
.08
1.09 1.65x1O
91
50
2
3
120
1100
200
1.63
4.48 .78
**
.62 2.43x10’
8.4 x10’
.052
.16
1.09 1.65x10’
1.51
q3
50
2
5
120
1100
200
1.63
4.90 .80
.64 l.68x10’
5.9x 10
.032
.10
1.09
94
50
2
7
120
1100
200
1.63
5.09 .81
**
.645 3.99x10’
1.4x 1O
.023
.07
1.09 i.65x10”
1 5!
-------
Paper le (DR-004) at the Second International Lime/
Limestone Wet Scrubbing Symposium (stone types 2 and 11,
respectively, in the referenced paper).
Limestone Weight - The weight of each sample
initially charged to the reactor.
Approximate Particle Size - These particle sizes
were estimated from photomicrographs of limestone
samples. Each size was obtained from a close screen
cut so that a narrow distribution was assured.
Stirrer Speed - Stirrer speed was set using a
calibrated rheostat. In Runs 14-21, it was later
noted that the stirring speed was not reproducible
because of friction in the stirrer seal. This
problem was solved by using a high-torque stirrer
for the remaining runs.
Feed Flow and HC1 Concentration - The dilute HC1
feed was premixed in the 16-gallon feed tank. The
exact concentration was determined by chemical
analysis. The feed flow rate through the reactor
was measured by a calibrated rotameter.
Effluent Composition - Effluent samples were taken
at elapsed times corresponding to 2, 3, 4, and 5
reactor residence times. In Runs 14-51, each sample
was analyzed for both total calcium and total carbo-
nate. For experiments using HC1 solutions stronger
than one mmole/liter, the carbonate concentration
was normally within a few percent of the calcium con-
centration. The carbonate analysis was thus discon-
tinued after Run 51. Analytical results listed in
-65-
-------
Table 4-3 are representative steady state values.
Analyses for the 3, 4, and 5-residence time samples
were typically identical within the accuracy of the
techniques used. The effluent pH was measured con-
tinuously using a laboratory pH meter with a flow cell
arrangement for the electrode.
Ion Activities - The individual ion activities shown
in Table 4-3 were calculated using the indicated
chemical analyses as input to the previously mentioned
chemical equilibrium computer routine. The relative
saturation is defined as the ion activity product
aCa aCO divided by the solubility product for CaCO 3 .
Dissolution Rate - Dissolution rates were calculated
using the feed flow rate and steady state calcium
concentration for each run. The fraction of the ini-
tial limestone sample that had dissolved before
steady state was approached was also estimated for
each run.
Equilibrium Activities and Solubility - These
quantities were calculated using the equilibrium
computer routine to simulate a saturated solution
of limestone in an 1-IC1 solution of indicated
concentration.
Quantitative interpretation of variable effects such
as agitation, temperature, limestone type, and particle size
requires a relationship between dissolution rate and liquor
composition. When a variable change causes a rate change, a
new steady state reactor composition results for a given flow
rate and feed composition. This new composition must be con-
sidered when comparing dissolution rates among experiments.
-66-
-------
Dissolution rates for all dilute HC1 experiments
using Type 2 limestone at the same levels of temperature,
particle size, and agitation are plotted versus hydrogen ion
activity in Figure 4-13. For these experiments the variations
in liquor composition include concentrations and activities of
calcium, carbonate, bicarbonate, hydrogen, and chloride ions.
An attempt was made to correlate results for a single
limestone in terms of various measured and calculated parameters
describing liquor composition. No generally applicable “driving
force” function was found, however. Correlating parameters
investigated (in addition to pH) included experimental and equi-
librium values for concentrations and activities of calcium,
carbonate, and bicarbonate ions.
As may be seen in Figure 4-13, the level of FIC1 in the
reactor feed appears to have some consistent effect on dissolu-
tion rates for the same limestone. Least squares lines drawn
through data obtained using various acid strengths are shown.
At a given pH, the rate of dissolution decreases with chloride
concentration for test series at .45, .84, 1.58, and 2.85 mmole
Cl/liter. An exception to this trend is noted, however, for
Runs 35, 36, 37, and 38 using stronger acid solutions. No expla-
nation for this discrepancy has been found. A duplicate run was
conducted to check Run 35 for possible procedural error. Run 117
shown on Figure 4-13 yielded a similar dissolution rate under the
same conditions as those used in Run 35.
Experimental and equilibrium activities of dissolving
species were calculated for the various runs so that the effect
of chloride concentration might be correlated on a more funda-
mental basis. The difference between equilibrium and actual
carbonate ion activities (a 0 - a 0 ) appears to correlate ob-
served dissolution rates quite well, again with the exception of
Runs 35-38. Figure 4-14 shows a plot of dissolution rates for
-67-
-------
.10
I Normal Operating Range of
Limestone Scrubbing Systems
I HC1 = 0.84 mmole/liter 4
HC1 = 0.45 mrnole/liter
1O -,
1 1
0
ib- 1O
HC1 = 8.50 mmole/liter
HC1 = 1.58 rnTnole/liter
= 2.85 mmole/ljter
Hydrogen Ion Activity - mole/liter
FIGURE 4-13 - LIMESTONE DISSOLUTION RATE VERSUS HYDROGEN ION ACTIVITY -
.08
4J
Cu
0 1 - i
.06
0
CI)Cu
.-I
I —I
00
CI)E
a)
.02
0
10-s
03
54
0
0
4
4
1
TYPE 2 LIMESTONE IN DILUTE HC1
-------
U
1 J
Co
00
U
4- i
- 1
U
4 - i
0
.1-i
0•’
—
CI
U
N
..-
Co
I-I
0
z
70.
60
50
40
30
20
l0
0
10-8 10:.8 10_b
Hydrogen Ion Activity - moles/liter
FIGURE 4-14 - NORMALIZED DISSOLUTION RATE [ Rate/(a 0 - aCO=)] VERSUS HYDROGEN ION ACTIVITY
- TYPE 2 LIMESTONE IN DILUTE HC1
055
4
0
1
‘4 1
10
-------
the Type 2 limestone normalized with respect to the carbonate
activity driving force (Rate/(a 0 = - aCO=). A substantial
improvement over Figure 4-13 is seen. Since experiments intended
to examine effects of limestone type, agitation, and temperature
were conducted within this range of feed liquor concentrations,
Figure 4-14 will be used as a basis for interpreting these vari-
able effects.
Experiments using different limestone types are
compared to the base case Type 2 limestone dissolution rates
in Figure 4-15. Four different limestone types were investi-
gated. Referring to Figure 4-15 experiments using different
limestones at similar temperature and agitation include Runs 14,
15, 16, and 17 (Type 1, Austin Limestone), Runs 25, 27, 65, 66,
67, and 68 (Type 3, EPA Hard Calcite), and Runs 29 and 32 (EPA
Soft Marl). Significant differences in reactivity between stones
are evident in both high and low pH regions. The Type 1 lime-
stone is approximately twice as reactive as the Type 2 (base case)
limestone in pH range 6.3 to 6.7. The soft marl appears to be
two to three times as reactive as the base case limestone, even
under conditions quite close to saturation. The reactivity of
the Type 3 limestone is comparable to that of the base case stone
over the range of conditions investigated.
Experiments conducted at temperatures other than the
usual 50°C temperature include Runs 18, 19, 23, 24, and 30.
Dissolution rates for these experiments can be compared with
50°C runs with similar levels of other variables to estimate
the temperature dependence of the rate. These runs are shown
in Figure 4-16 along with the base case (Type 2) results. Com-
paring Run 30 to Run 29, for example, a factor of 5.7 difference
in dissolution rate (corrected for liquor composition using the
carbonate driving force) is seen for a temperature difference
of 24°C. This corresponds to an Arrhenius activation energy
-70-
-------
60
O = Type 1 - Austin Limestone
= Type 3 - EPA Hard Calcite
V = Type 4 - EPA Soft Marl
U
“-I
50
bO
U
40
a)
U
Cu
0
U
0
CS)
U)
a)
10
I-I
I -i
0
Z 0
30
I-I
20
S
V29
S
10
v 32
10
Hydrogen Ion Activity - mole/liter
— 5
FIGURE 4-15 - EFFECT OF LIMESTONE TYPE ON DISSOLUTION RATE IN DILUTE HC1
-------
o = Type 1, 50°C
• = Type 1, 25°C
A= Type 3, 50°C
£= Type 3, 27°C
V= Type 4, 50°C
v= Type 4, 26°C
Hydrogen Ion Activity - mole/liter
a)
.,-I
00
I -i
a)
1J
.-1
a)
0
. -4
4J
0
U)
(1)
a)
N
•r4
V- 4
C U
0
z
-J
29
V
10
0
10
001 7
\
lo-
10
FIGURE 4-16 - EFFECT OF TEMPERATURE ON DISSOLUTION RATE IN DILUTE HC1
-------
of 14 kcal/mole for dissolution of the soft marl in the pH 8.5
range. A factor of six difference in rate is observed for the
hard calcite at a pH of 6.4. This also leads to an activation
energy of 14 kcal/mole. A third comparison using Runs 18 and 19
with Austin limestone shows a similar temperature dependence.
The effect of stirring rate may be seen by comparing
Runs 23 and 24 using calcite at 27°C, Runs 27 and 28 with calcite
at 50°C, and Runs 32 and 33 using marl at 50°C. These results
are shown in Figure 4-17. In each of these cases, a significant
effect of stirring is seen. A quantitative estimate of this
effect would require more difinitive data describing the rate
dependence on liquor composition. The observed stirring effect
is significant both at high and low temperatures and pH levels.
Experiments intended to investigate the effect of
particle size on dissolution rate were conducted using the
Type 2 limestone. Dissolution rates of 120 micron and 5 micron
limestone samples are compared to those of the base case (60
micron) limestone in Figure 4-18. The dissolution rate of 60
micron limestone particles is approximately twice that of 120
micron particles. A sample having a mean size of approximately
5 microns dissolved 5 to 8 times faster than the 60 micron
material.
The scatter in the small particle size data shown in
Figure 4-18 is due to the broad size distribution of these
samples. All samples larger than a 400 mesh screen could be
classified into reasonably narrow size cuts. The fines used
in Runs 85, 86, and 87 had a wider range of particle sizes,
however. With the batch dissolution technique used in this
study, a steady state composition is not achieved under these
circumstances. The indicated pH of 6.3 for these three tests
is a representative estimate. Actual operating pH typically
ranged from 5.8 to 6.7 over the course of a run.
-73-
-------
60
C t
bO
S..- —
U)
I.i
40
30
0
•d
-S I
I-I
20
C l )
C t
. 10
‘-I
Cu
I -i
0
z
= Type 3 Limestone, High Stirring
A= Type 3 Limestone, Low Stirring
W= Type 4 Limestone, High Stirring
y= Type 4 Limestone, Low Stirring
10
32
V
Hydrogen Ion Activity - mole/liter
l0-
10
FIGURE 4-17 - EFFECT OF STIRRING ON DISSOLUTION RATE IN DILUTE HC1
-------
a)
E
0 )
.,-1
a)
0
4J
0
C l )
C l )
a.)
N
Co
‘-1
0
z
Qe8
3
2
5 micron limestone
085
60
d 3
0
120 micron limestone
94
0
10—’
Hydrogen Ion Activity - mole/liter
FIGURE 4-18 - EFFECT OF PARTICLE SIZE ON DISSOLUTION RATE - TYPE 2 LIMESTONE
IN DILUTE HC1
10
-------
4.4.2 Limestone Dissolution in Simulated Scrubbing Liquor
Since no fundamental rate correlation was developed
for limestone dissolution in dilute HC1 solutions, additional
experiments were run using liquors typical of those encountered
in closed-loop limestone scrubbing units. These data should be
more directly applicable to full scale system design.
Selection of liquor compositions for these tests was
based both on computer simulation of limestone scrubbing systems
and actual analyses of samples from operating pilot units.
This information has shown that the concentrations of important
species in solution vary substantially only according to the
characteristic ionic strength of the particular system. A
typical limestone scrubbing liquor is essentially a slightly
supersaturated solution of calcium sulfite and sulfate. The
solubilities of these compounds determine the amounts of cal-
cium, sulfite, and sulfate in solution. Their solubilities are
in turn influenced strongly by the presence of other “soluble”
species, particularly sodium, magnesium, and chloride. Concen-
trations of soluble species are determined by trace constituents
in limestone, flue gas, and fly ash. The degree to which solid
waste is dewatered also has a major impact on concentration
levels reached by soluble species.
Two types of simulated scrubbing liquor were used.
These were estimated to represent a range of compositions which
might be experienced in field application of the process. Runs
95-98 were conducted in a high ionic strength liquor containing
high levels of soluble magnesium and chloride. Sulfite and
sulfate concentrations in the feed for these runs were estimated
so that the steady state reactor composition would be in the
appropriate range of supersaturations for these species.
-76-
-------
Steady state levels of calcium concentration for
this series ranged from 36.9 to 39.7 tnillimole/liter. Calcium
sulfite supersaturations were in the 4-5 range and sulfate
supersaturations ranged from 1.0 to 1.05. These are typical
of hold tank operating conditions measured at several pilot
units.
Runs 107-110 used a feed liquor with no soluble
magnesium and only small amounts of sodium and chloride.
Operating concentrations of calcium were much lower in this
case; about 22 niilliniole/liter. Calcium sulfite and sulfate
supersaturations were about 2 and 1.3, respectively.
A third series of experiments, Runs 111-115, was
carried out using a similar low ionic strength feed liquor with
a slightly higher HC1 concentration. The operating combination
of a stronger acid feed at a lower flow rate using large lime-
stone samples yields a larger change in calcium concentration
from feed to effluent and, thus, a more accurate dissolution rate
calculation.
Complete operating conditions and analytical results
for the simulated scrubbing liquor test series are summarized
in Table 4-4. Dissolution rates observed in these simulated
scrubber liquors are not related to the dilute HCI experimental
results by the carbonate ion activity expression discussed in
Section 4.4.1. No satisfactory expression has been found to
quantitatively account for increased dissolution rates in simu-
lated scrubbing liquor.
Figure 4-19 shows dissolution rates for the Type 2
limestone in simulated scrubbing liquor experiments. A least
squares fit of data from dilute HC1 runs in the same pH range is
also shown for comparison. The rates in scrubber liquor are
-77-
-------
Approx. Feed
Mean Plow Effluent
Limeacone Particle Stirrer Rate Feed Composition Concertration
Run Temp. Vt. Size Speed (eli ( uino lelltter) ( i mncleid )
No. C izl ( Micron) ( RPM ) rnlnL ..&!. .. S_ ..is.. ... .L. ... _iQa .2L &8_. Qa_.
TABLE 4-4
M TN TMIJtATPl1 RIJRRER LI0I10R
Activity
(tnno1eit
Ca co.
Relative
8a itteui
£CO e C0
g .
Diseolu-
lion
Rate
(emiol./
aram-min)
Fraction
of Sample
Dissolved
et 3’
Equilibrium
Activity
( Lei )
Ca CD
Equilib.
SolubiL
(m i nnIe / i)
95
50
2
5
60
1100
200
36.3
168
18.7
322
11.6
70.4
5.40
39.1
96
50
2
3
60
1100
300
36.4
168
18.7
322
11.6
70.4
5.30
39.7
97
50
2
3
60
1100
200
34.3
168
18.7
322
11.6
70.4
5.25
36.9
98
50
2
7
60
1100
200
34.3
168
18.7
322
10.8
70 4
5.60
37.6
107
50
2
5
60
1100
200
19.4
—
13.2
6.60
3.53
22.4
5.53
22.7
108
109
110
50
50
50
2
2
2
3
3
7
60
60
60
1100
1100
1100
300
200
200
19.4
19.4
19.4
—
—
—
13.2
13.2
13.2
6.60
6.60
6.60
3.67
3.37
3.08
22.3
22.6
22.8
5.33
5.04
5.59
22.2
22.0
21.4
111
50
2
20
60
1100
50
16.7
—
10.0
15.35
—
19.9
5.70
23.0
112
50
2
30
60
1100
30
15.7
—
10.0
15.35
—
19.9
5.80
22.7
113
50
2
20
60
1100
30
17.6
—
10.0
15.35
—
19.9
5.77
33.1
114
50
2
30
60
1100
50
19.35—
10.0
15.35
—
19.9
6.00
22.6
2.1 7.36
2.0 7.51
1.3 7.01
2.2 7 01
5.74
1.54 5.66
1.37 5.63
1.62 5.33
9.26 6.20
9.26 6.08
6.93 6.24
4.95 6.10
3.78x10
2 .40x10’
1. 19x10’
8.69x10’
4. 84x 10°
2.14x10
5. 36x10’
6.7xL0
5.9x10
9. 3x10
5.9x l0
9.9x10
L.3zLO’
1.5x10’
I .0x10’
4.6x10
3.4xL0’
1.5x10’
6.7x10
1.7x10’
2.OxlO’
2 .0xL0
3.1x10
2 .0x10’
3.4x10’
4.6x10’
115 30 2 30 60 1100 50 20.5 — 10.0 15.7 — 19.6 6.16 22.9 3.76 6.23
.11
.20
.17
.094
132
.168
.173
.057
.016
.012
.014
.0034
.004
.33
.40
.51
.28
.40
.36
.52
.17
.19
.14
.17
.06
.03
7.8
7.8
7.8
7.8
5.3
3.3
5.3
5.3
6.69
6.69
6.63
6.63
6.40
2.3x10
2 .3x10’
2.3x10
2.3x10’
3.3xL0
3.3x10’
3. 3x10’
3. 3xL0
2.70x10
2.70x10
2.73x 10’
2. 73x 10’
2 .8 z10
6.8
6.8
6.8
6.8
3.6
3.6
3.6
3.6
8.4
9.4
7.1
5.4
3.0
-------
.2C
.18 ®109
1 O8 O
.16
a)
O)1 )
14
Q , Q7
.12
1J 4
Oa)
U) 0 .08
..-1
.06
.04
02
o 114
10- ’
Hydrogen Ion Activity - mole/liter
FIGURE 4-19 - LIMESTONE DISSOLUTION IN SIMULATED SCRUBBER LIQUOR
0 ‘
icc- 5
-------
lower than those for the dilute HC1 solution for pH levels above
about 5.7. This is not unreasonable since the liquor in which
Runs 111-118 were conducted is very close to saturation with
respect to CaCO 3 . The pH of the saturated scrubber liquor is
approximately 6.2 while the equilibrium pH of the dilute HC1
runs shown in Figure 4-19 is about 7.3.
Below pH 5.7, the dissolution rate of limestone in
simulated scrubbing liquor exhibits a substantial increase,
roughly proportional to the hydrogen ion activity. The dis-
solution rate at pH 5 is approximately 30 to 40 times that
at pH 6. This behavior compares very well with dissolution
rate behavior observed in pilot units. For example, in the
pilot studies conducted at Combustion Engineering’s Windsor
laboratory, the amount of limestone dissolution in the
scrubber at pH 5 was comparable to that in the hold tank
at pH 6 even though the volume of liquor in the scrubber
was a factor of 20 less than that in the hold tank.
Figure 4-19 also shows that the presence of large
amounts of soluble magnesium and chloride does not appear to have
a significant effect on dissolution in simulated scrubber liquor.
Runs 95-98 resulted in rates comparable to Runs 108-110.
4.4.3 Summary and Conclusions
Limestone dissolution rate experiments have been
conducted in dilute HC1 solutions and simulated scrubbing
liquors. In the dilute HC1 test series, the following variable
effects were noted.
Limestone reactivity varied by as much
as a factor of three for the four stones
investigated.
-80-
-------
• The temperature dependence of the dissolution
rate corresponds to an Arrhenius activation
energy of about 14,000 calories/gram-mole.
• A significant agitation effect was seen at
high and low levels of temperature and pH.
• The dissolution rate is approximately inversely
proportional to particle size. The dissolution
rate per unit of surface area is thus nearly
constant.
These experimental observations indicate that limestone
dissolution is probably limited by both surface phenomena and
liquid film resistance. General correlation of results in this
case would be particularly difficult.
Limestone dissolution rates in simulated scrubbing
liquor could not be related to the dilute HC1 test results in
any consistent fashion. Experimental results for these tests
showed that dissolution rates can be expected to be a strong
function of pH. Soluble magnesium and chloride, on the other
hand, do not appear to affect the dissolution rate in simulated
scrubber liquor.
For purposes of process design estimates, the following
may be used.
Limestone dissolution rates in a hold tank
environment (pH 6) should be on the order
of lx10 moles per minute per gram of lime-
stone for 60 micron particles. The rate on a
per gram of stone basis is inversely propor-
tional to particle size.
-81-
-------
Limestone dissolution rates in a scrubber
environment (pH 5) should be 30 to 40 times
the hold tank rate. Thus significant lime-
stone dissolution will occur in most scrubbers
in spite of the low liquid hold up compared to
that of a hold tank.
In view of the demonstrated complexity of limestone
dissolution rate correlation, laboratory evaluation of candidate
limestones is recommended as a standard design procedure. These
tests should be conducted using a liquor typical of design opera-
ting conditions for the hold tank and scrubber environments.
-82-
-------
4.5 Lime Dissolution
The experimental apparatus and technique discussed in
previous sections did not prove suitable for measurement of lime
dissolution kinetics. Instead, other methods were used to
demonstrate qualitatively the high dissolution rate of conimer-
cially available hydrated lime.
4.5.1 Simplified Beaker Experiments
Initial experimental work was directed toward
determining rough order-of-magnitude values for the dissolution
rates of lime in aqueous solutions. Samples of the lime used
by Southern California Edison in their pilot SO 2 scrubber at
Mohave were obtained for these experiments.
A microscopic examination of this material showed that
it was composed mainly of 1-2 micron diameter particles. A
chemical analysis of a sample of this lime yielded the results
shown below:
Sample: Hydrated Lime
Source: Southern California Edison Company, Mohave
Generating Station (Manufactured by
Flintkote)
Component Wt.7 0
Na 0.8
Mg 0.25
Ca 48.2
-83-
-------
During these initial experiments, one gram samples
of this material were dropped into a stirred beaker containing
either deionized water or dilute hydrochloric acid solutions.
The dissolution of the lime was monitored with a divalent cation
electrode which measured the activity of the Ca (or other
divalent) ions in the solution.
Based on the output of this electrode observed during
these experiments, it was obvious that the Ca ion activity
approached its equilibrium value very rapidly. For all of the
cases considered, greater than 90% approach of the measured
activity to its equilibrium value was achieved 15-20 seconds
after the lime sample was added to the beaker. Limestone samples
tested in this manner dissolved considerably slower, however
it was not known how much of this observed rate difference was
due to the smaller size of the lime particles involved. (1-2 micron
for lime vs. 5O micron for limestone).
In order to minimize the rate effects caused by particle
size differences between samples of commercial lime and lime-
stone, these tests were repeated using reagent samples of CaCO 3
(limestone), CaO (quicklime), and Ca(0H) (hydrated lime).
Microscopic examination of these reagents showed that all three
samples were composed of particles which were approximately
1 micron in diameter.
Samples of 0.1 grams each of these reagents were added
to a well-stirred one liter beaker. Dissolution rates were monitored
with a pH electrode. This electrode was used in these experi-
ments because its response characteristics were better than
those obtained with the divalent ion electrode.
-84-
-------
The response time of the pH electrode and the mixing
time of the agitated vessel were determined by dumping small
samples of concentrated HC1 or NaOH solutions into the vessel.
A typical response curve for this type of experiment is shown
in Figure 4-20. It can be seen from this curve that the pH
electrode output reached its new steady state value about two
seconds after the alkaline liquid was added to the reactor.
This response time was lower for less drastic changes in pH.
The divalent ion electrode took about five seconds to respond
to the addition of a saturated lime solution.
Prior to the start of each dissolution experiment
the reactor was filled with deionized water and the initial pH
was adjusted using dilute solutions of HC1 and NaOH. Experiments
were conducted using each of the three reagents at initial pH
values of 5 and 7. Typical pH electrode response curves for
these experiments are shown in Figures 4-21 and 4-22.
No significant differences in dissolution rate could
be observed between the CaO and Ca(OH) 2 reagent samples at
either pH. As cart be seen from Figures 4-21 and 4-22, however CaCO 3
was observed to dissolve much slower than either CaO or Ca(OH) 2 .
Based upon these results, it was concluded that
commercial lime samples can be expected to dissolve considerably
faster than limestone. This observed rate difference is due to
a combination of the following two factors.
• the intrinsic dissolution rate of lime
is greater than that of limestone, and
commercial lime particles are usually
much smaller in size than limestone
particles.
-85-
-------
CD
C
(D
3 4 5 6 7 8 9 10
pH
FIGURE 4-20 - pH ELECTRODE RESPONSE
-------
r
- - - ---H H
L - __
FIGURE li-21 - DISSOLUTION OF Ca(OH) REAGENT IN DEIONIZED WATER
r4 H I
I I
——-- -
- -—--j.-:-
-.--- -.-
-- 4 —r---1---•1—
-
- - -
- —I— -
1
- -
-
— —
-. — -i --1-H--
- -±H-
- —--
—
1
—H-- --
- --
- -
-
- -
-
— —
4--
-H-----
EF
4-H-- i--
HLL
I iiIr
- - -
-— —---—4.-.
i-it
t
Time
z ITiI4Ii:T_itiI
I I
a
I
6
—r-— --r
- —-———j-—
r
—
±
: :
— —
— —
: :
iji : :
—r +
— I
ILL :f:
ic ‘
— .1—i
— —
* t±
: :
F —
— —
± :E:
I:r:J:
L._ —
:i:i:
: ::
:i± :1:
: :
: :
: : :
: : :
:
—1 —..
: :1±:
I
7
I i I I
8
pH
9
10
11
-87-
-------
L
H-
TJJI
t
-.-
- -
nit i 1 pH
-: 1- t
_1 _t I !_iai _iii!j IJ
-H-
:±
6 7 8
pH
It-
L4T
FIG1J E 4-22 - DISSOLUTION OF CaCO 3 REAGENT IN DEIONIZED WATER
H+rn
4
Time
- - - - i
H
9
-88—
-------
The process implications of these findings can be
summarized as follows. Because of the high dissolution rate of
lime, a circulating lime slurry leaving an SO scrubber hold tank
or other long residence time vessel will be essentially saturated
with respect to Ca(OH) 2 in the liquid phase. This will not
necessarily be the case in a low residence time vessel such as
a spray scrubber.
4.5.2 Packed Bed Reactor Experiments
In an attempt to quantitatively describe the
dissolution rate of lime in aqueous solutions, a low-residence-
time plug flow reactor was constructed. Irt this reactor the
liquid phase was forced down through a fixed bed of lime particles.
The residence time of the liquid in the packed bed was controlled
by adjusting the flow of liquid to the reactor.
Unfortunately, this reactor design proved to be
unsuitable because of the small sizes of the lime particles
used. Apparently, these particles plugged the pores of the
Nillipore filter which supported the bed. This resulted in
the buildup of a large pressure drop across the reactor and
severely limited the amount of liquid which could be forced
through the reactor.
In an effort to circumvent this problem, several
attempts were made at growing larger lime particles. This was
done by adding a dilute aqueous solution of CaC1 2 dropwise to
a solution of NaOH. A small number of lime crystals greater than
10 micron in diameter were successfully grown using this tech-
nique; however, the yield of large crystals was so poor that
this approach had to be abandoned.
-
-------
4.5.3 Spray Tower Experiments
As noted previously, there is no real incentive
from a process standpoint for investigating the rate of lime
dissolution in a typical stirred process hold tank. When lime
particles are present in any agitated, long residence time vessel,
the liquid phase will become essentially saturated with respect
to Ca(OH) 2 . In a short residence time vessel (i.e., a scrubber),
however, a consideration of the kinetics of lime dissolution
might be of interest. This is particularly true if the lime
dissolves so fast that a significant portion of the effective
alkalinity in the scrubber can be contributed by lime species
which enter the scrubber initially in the solid phase. If this
is the case the concentration of lime solids in the inlet liquor
must be considered as an important scrubber design variable.
In order to investigate this phenomenon, a series of
SO 2 sorption experiments was conducted using Radian’s bench-
scale scrubbing apparatus. These experiments were designed to
determine whether or not a significant quantity of lime can
dissolve in a typical short residence time contactor.
A schematic diagram of the experimental apparatus used
for this study is shown in Figure 4-23. This equipment was
designed to supply a three-inch diameter glass scrubber with
known quantities of a blended gas mixture which simulated a
typical power plant flue gas. Inside the scrubber the gas mix-
ture was countercurrently contacted with the liquid sorbent.
In all of the SO sorption experiments reported here, the scrub-
ber was equipped with a single spray nozzle as shown in Figure
4-24.
-90-
-------
TO VEI4T
4 jJA L’C1ICAL
TO VE 4T
4 MIAL’(T C L
I S12UMEMT5
FEED UCUO
Til ERMOSW
Co 2
- _ 1401 OX
5PEI. T LIQUO2.
G S MI U14G SECTIOI4
TOTAL FLOW COIJTEOL
ECTIOI..i
SCRUBBING CT%OIJ
FIGURE 4-23 - EXPERIMENTAL APPARATUS
1-_
PREHE? TI F4G
CT(OIJ
-------
Liquid
In
CasOut—4
J Spray Nozzle (# YeC 1 )
Thertnometer Systerns Company Spraying
A A = Vertical distance
I between spray
1 ’ nozzle and point
at which liquid
begins to contact
wall of scrubber.
_______ 17”
3” Diameter A 6” at low flows
Glass Column (50 mi/mm)
2” at high flows
(400 mi/mm)
— —Gas In
2”
Liquid
Out
FIGURE 4-24 - DIAGRAM OF SPRAY SCRUBBER USED IN
LIME DISSOLUTION RATE STUDY
-92-
-------
Sampling connections were provided on all streams
entering and leaving the scrubber. The capability for obtain-
ing on-line vapor phase SO 2 analyses was supplied by a DuPont
Model 400 photometric analyzer. Gas and liquid phase flow rates
were determined by using calibrated rotameters.
The rate of lime dissolution could not be determined
by conventional slurry sampling techniques since the residence
time of a pump/filter combination would be perhaps five to ten
times that of the spray tower. Instead, interpretation of these
experiments had to be based on the degree of SO 2 removal ob-
tained in the scrubber.
First, the efficiency of the spray tower was determined
using NaOH solutions at various liquid rates. These runs em-
ployed very high pH liquors to minimize the liquid film resistance
to mass transfer. This provided a means of estimating the amount
of interfacial mass transfer surface area generated in the scrub-
ber as a function of the mass flow of liquid through the spray
nozzle. This information was needed to normalize the results
obtained from sorption experiments which were conducted using
lime slurries of varying solids content.
Liquid rates which were used during the lime slurry
experiments were chosen in such a way that different scrubbing
liquors were compared under conditions at which the total
alkalinity (liquid + solid) fed to the spray tower was constant.
The effect upon the SO removal of having the alkalinity in the
solid rather than the liquid phase was then considered, once a
correction was made for liquid rate effects.
-93-
-------
The raw data obtained during the lime scrubbing
experiments are presented in Table 4-5. Shown in this table
are data from runs which were made using a 0.5 M NaOH scrubbing
solution (Runs 1-6), a saturated lime solution (Runs 7-15),
and lime slurries containing from 0.1 to 0.5 wt.% Ca(OH) 2 solids
(Runs 16-60).
The calculated stoichiometric ratios shown in this
table were determined by assuming that the following SO 2 sorp-
tion reactions take place.
Reaction with NaOH :
2NaOH + SO 2 Na 2 SO 3 + H 2 0 (4-il)
Reaction with Lime :
Ca(OH) 2 + SO 2 Ca SO 3 + H 2 0 (4-12)
A calculated stoichiometric ratio of 1.0 is obtained when the
molar flow rate of NaOH [ or Ca(OH) 2 ] is exactly equal to the
amount required to react with 1OO7 of the inlet vapor phase SO 2
according to the reaction given in Equation 4-il (or 4-12).
A detailed analysis of the experimental results
presented in Table 4-5 is presented in the following section.
-94-
-------
TABLE 4-5
BENCH- SCALE SPRAY COLUMN SO 2 SORPTION RESULTS
(Temperature 50°C)
C e o S0 •
Run Flow Concentration
l b. XFHt inlet Outlet Scrubbiny. L iqu Id
1 95 2950 1550 .5 H NaOH
2 95 3000 910
3 95 3000 630
4 95 3000 395
5 95 3000 240
6 95 3000 100
7 95 3000 2325 .016 H Ca (Oil),
(saturated)
8 95 3000 1975
9 95 3000 1765
10 95 3000 1175
it 95 3000 975
12 95 3000 750
13 95 3000 575
14 95 3000 450
15 95 3000 325
Liquid Stotchtoe.etry l b. of Transfer Un Ite
Plow Hol.t SO, (based on (assuming zero SO.
mlleitn Scrubbed toter SOa beck 9r I ssure )
80 47.5 3.32 0.64
112 69.7 4.66 1.19
157 79.0 6.53 1.56
240 86.8 9.93 2.03
300 92.0 12.48 2.53
400 96.7 16.64 3.40
93 22.5 0.24 0.25
135 34.2 0.36 0.42
180 41.2 0.48 0.53
220 60.8 0.58 0.96
263 67.5 0.70 1.12
305 75.0 0.81 1.39
345 80.8 0.92 1.65
VS 85.0 1.03 1.90
428 89.2 1.14 2.22
10.8
29.2
40.8
60.8
75.8
85.8
90.0
91.7
94.2
65.0
74.2
81.7
86.3
94.2
95.3
96.7
97.0
97.5
76.7
80.8
85.8
90.0
91.7
93.3
93.3
93.7
96.7
10.0
33.3
34.2
40.0
50.8
85.0
91.7
94.2
96.3
96.7
0.30
0.44
0.69
0.86
1.13
1.55
1.75
1.97
2.18
0.22
0.54
0.86
1.17
1.65
1.94
2 • 25
2.40
2.61
0.47
0.66
1.09
1.52
1 • 90
2.38
2.99
3.33
4.47
0.44
0.70
0.96
1.23
1.47
1.98
2.49
3.38
4.35
4.96
0.11
0.34
0.52
0.94
1.42
1.95
2.30
2.48
2.84
1.05
1.35
1.70
2.1 .5
2.84
3.06
3.40
3.51
3.69
1.46
1.65
1.95
2.30
2.48
2.71
2.71
2.76
3.40
0.1.0
0.41
0.42
0 • 51.
0.71
1.90
2.48
2.84
3.31
3.40
53 95 3000 2800
54 93 3000 2000
55 95 3000 1500
56 95 3000 750
51 95 3000 560
58 95 3000 450
59 95 3000 350
60 95 3000 250
.5 wt.t Ca(OH), Slurry 40
87
130
168
240
300
368
• 1 420
* Standard Conditions 32°F. 1 atm.
16 95 3000 2675 .1 iIt.t Ca(0Ifl, Slurry 60
t l 95 3000 2125 89
18 93 3000 1775 138
19 95 3000 1175 172
20 95 3000 725 225
21 95 3000 425 “ 310
22 95 3000 300 350
23 95 3000 250 393
24 95 3000 175 435
25 95 3000 1050 .2 wt.7. Cs(0I1), Slurry 31
26 95 3000 775 75
27 95 3000 550 119
26 95 3000 350 141
29 95 3000 175 228
30 95 3000 140 267
31 95 3000 100 310
32 95 3000 90 330
33 95 3000 75 360
34 95 3000 700 .3 Wt.t Ca(CH), Slurry 50
35 95 3000 575 70
36 95 3000 427 115
37 95 3000 300 160
38 95 3000 250 200
39 95 3000 200 250
40 95 3000 200 315
41 95 3000 190 355
42 95 3000 100 470
43 95 3000 2100 .4 Wt.t Ce(OE), Slurry 38
44 95 3000 2000 60
45 95 3000 1975 82
46 95 3000 1800 1 .05
47 95 3000 1475 125
48 95 3000 450 169
49 95 3000 250 212
50 95 3000 175 288
5 1 95 3000 110 370
52 95 3000 100 422
6.7
0.56
0.07
33.3
1.21
0.41
50.0
1.82
0.69
75.0
2.35
1.39
81.3
3.36
1.68
85 0
4.20
1.90
88.3
5.15
2.15
91.1
5.88
2.48
-95—
-------
4.5.4 Analysis of Experimental Spray Tower Data
An equation which is commonly used to correlate
vapor-liquid mass transfer data is given below.
= NTU (4-13)
where:
= overall mass transfer coefficient,
lb-moles/hr-ft 2 -atm;
a = interfacial mass transfer area per unit
scrubber volume, ft /ft 3 ;
G = scrubber vapor flow rate, lb-moles/hr;
P = scrubber operating pressure, atm;
V = scrubber volume, ft 3
NTU = number of overall gas-phase transfer units.
Actually, Equation 4-13 is obtained by integrating
the following differential equation which describes the mass
transfer process taking place inside a scrubber.
dV = (y y*) (4-14)
where:
y = mole fraction SO 2 in vapor phase,
y* = mole fraction SO in vapor phase in
equilibrium with liquid phase.
-96-
-------
In order to integrate this relationship to obtain the
form shown in Equation 4-13, it is necessary to assume that the
value of the term KGaP/G does not vary with position inside the
scrubber. For this case, the integrated form of Equation 4-14
becomes
yout
KGaPV — — - f dy 4-15
G - — J (y...y*)
Yj
A rigorous treatment of this equation requires that
an expression for y* as a function of y be known. For the
case where y* is negligibly small compared to y, the simplified
form of the mass transfer equation shown below is obtained.
KGaPV = = NTI.J (4-16)
yout
In this analysis it has been assumed that there is negligible
mass transfer back pressure (y = 0).
Because the physical properties of the different
scrubbing liquors evaluated did not vary significantly, the
performance characteristics of the spray nozzle used here
should not have been noticeably affected by changes in scrub-
bing solution. At some given volumetric liquid flow rate, the
interfacial mass transfer surface area (the fla” term in Equation
4-16) should have been reasonably constant for all of the solu-
tions considered.
Because of this fact, the easiest way to compare the
experimental results reported here is to plot the calculated NTU
values shown in Table 4-5 as a function of the scrubber liquid
flow rate. Since the values of G, P, V and a should all have
remained reasonably constant at a given liquid rate as the
-97—
-------
scrubbing solution was varied, this method of analysis should
reveal whether the presence of solid phase lime species signifi-
cantly affected the value of KG.
A plot of NTU as a function of the scrubber liquid
rate is shown in Figure 4-25. The data shown in this figure
are somewhat confusing. This is particularly true of the cases
where the concentration of lime solids in the scrubbing liquor
is greater than 0.3 wt.°h. Presumably, these anomalies are due
to liquid distribution problems which occurred as the concen-
tration of solids in the scrubber liquid increased. In the
runs in which lime slurries were evaluated, the small spray
nozzle used sometimes became plugged with lime particles. The
result of this was a non-uniform spray pattern within the scrub-
ber (i.e., most of the liquid sprayed to one side). This could
account for the unusual behavior of those curves shown in Figure
4-25 for which the lime solids content was greater than 0.3 wt.7 0 .
If these questionable experimental data are dropped from con-
sideration, the result is the set of curves shown in Figure 4-26.
It can be seen from the data presented in Figure 4-26,
that the rate of lime dissolution is apparently sufficiently
large that it does influence the rate of SO 2 mass trans-
fer in a short-residence time spray scrubber. As the wt.% solids
content of the slurry was increased from 0 to 0.2 wt.7 0 , a signi-
ficant increase in the mass transfer rate was observed even though
the initial soluble alkalinity entering the scrubber was the
same in each case. It can be concluded from these results that
lime particles which are 1 micron in diameter do dissolve
rapidly enough to affect the sorption rate of SO 2 in a typical
spray scrubber.
-98-
-------
J
::
.
T:tTiI
_::i
..
- - t-
IItT
i± 4L4 L
::.:i
iTfleS1urr
ii ii:___
—L
JI I
ILL I iitI
iEi
t
77T
7 / L
.tHJ I
r: L
.
“.—
MNaOHSo
ii
ni Slurry
T
J L!
---j I:-t
-‘ H
. .
.. .i
1 - - r-
4:
i
TI iL
1
n.
--
I
Th
ry
3 wt .
pL 1tm e
L nie-S .urry
r c
—o
.1
• 2b0 ,T.1• O. i:..
Scrubber Liquid Rate ( m1/min • 1 — — ____
‘FIGURE 4-25- GAS P1 IASE TRANS ’ER UNITS bBTAINED A SAFL CTI)N OF
Ii . !I• THE RUBBERLIQUIDFEED ATE, .• ___ ___
-99-
-------
±
I .
-t±{--
1fTh
J±
i irT
-
E
±
T
i :
- / .
. 4tt — —
/ A ., - + i . — II
JL. z VIIi
/
L_ :: :I 00 . . .::. 200.: : ii.3 O. IjiL 4 ).0.____
fsciubber 4sui& -Feedi. Rate . rni in j I
• .H .-. .-—- .-
FIGURE 4-26- NTU VALUES 0BTAT. D FOR .sqRuBBING L1 U0R CONTAINING
03 r.7, SOLIL S-- • -• 1: -•1
)
±f
II I I /iii ::/
-100-
-------
4.5.5 Conclusions
The major conclusions of this qualitative study of
lime dissolution are:
subject to equilibrium constraints, lime
particles of a given size will dissolve
faster in aqueous solutions than limestone
particles of the same size.
this intrinsic rate difference is often
enhanced by the fact that lime particles
are typically smaller than limestone
particles. This is particularly true of
commercially prepared lime and limestone
samples.
well-stirred process hold tanks containing
solid phase hydrated lime can probably be
assumed to be saturated with respect to
Ca(OH) 2 in the liquid phase.
the dissolution rate of a typical lime sample
is so rapid that a significant contribution
to the total alkalinity of the system can be
expected to be supplied by lime species which
initially enter a scrubber in the solid phase.
The effects of this rapid dissolution rate should
be taken into account whenever attempting to
model or design a lime scrubbing system for SO 2
removal.
-101-
-------
Although these experiments did not successfully
quantify the dissolution rate of lime in aqueous solutions
or the factors affecting that rate, they did serve to indicate
the magnitude of the difference between lime and limestone
dissolution rates. These observed rate differences could have
a significant effect upon the relative performance character-
istics of lime and limestone based SO 2 scrubbing systems.
-102-
-------
5.0 SO 2 SCRUBBING TESTS AT THE WINDSOR PILOT FACILITY
To accelerate the commercial deveLopment of the
Lime/limestone wet scrubbing systems, EPA contracted Combustion
Engineering to conduct research and development on pilot scale
and prototype scale lime/limestone wet scrubbing systems. EPA
contracted Radian Corporation to provide Combustion Engineering
with technical support for their lime/limestone wet scrubbing
research. Radian Corporation’s primary responsibilities were:
(1) test program design,
(2) sampling and chemical analysis of process streams,
(3) engineering analysis and interpretation of test
results,
(4) dynamic updating of the test program,
(5) recommendations for future tests,
(6) reporting the anaLysis of test results and
describing their significance to EPA’s limestone
scrubbing demonstration program at TVA’s Shawnee
station.
This section of the final report reviews Radian
Corporation’s findings and conclusions evolved in support of
Combustion Engineering’s lime/limestone wet scrubbing tests at
their pilot scale facilities in Windsor, Connecticut.
-103-
-------
5.1 Windsor Pilot Test Unit
The lime/limestone wet scrubbing tests were performed
at the Combustion Engineering pilot test facilities located at
the Kreisinger Development Laboratory in Windsor, Connecticut.
This pilot test unit was designed and built by Combustion
Engineering and is similar to several of their field installations
such as those at Kansas Power and Light and Kansas City Power
and Light.
5.1.1 Equipment
The CE pilot test unit is basically of modular
arrangement, designed to allow rapid system modifications and
alterations. The piping and pumps are arranged to allow several
different processing schemes. The five flow schemes utilized
in the lime/limestone wet scrubbing test program are presented
in Figures 5-1 through 5-3b.
The gas-liquid contactor used in the pilot tests was
a 25 sq. ft. marble bed scrubber, constructed such that it could
be altered from a single bed to a double bed scrubber. The
piping of the marble bed scrubber was designed for above-bed
and/or below-bed slurry sprays. Spent scrubbing slurry was
withdrawn from the scrubber through the scrubber bottom and
through downcomers in the marble bed.
Flue gas for the pilot tests was supplied by an
oil-fired package boiler which had a flue gas output of 12,500
ACFM to 15,000 ACFM (measured at 14.7 psia and 125°F). A heat
extractor before the scrubber and a reheater after the scrubber
allowed variations in the inlet flue gas temperature to the
scrubber. In order to simulate coal-fired boilers and boiler
-104-
-------
- Indicators
Vibratory
Feeder
Pump Discharge Sample Point
To Clarifier
Flue Gas
SO From Heat Extractor
Cylinder
FIGURE 5-1 - SCRUBBER SYSTEM FLOW SHEET - ONCE-ThROUGH
SOLUBLE Na 1 CO 3 RUNS
To I.D. Fan
and Stack
Raw Water
y
a
Solid
Na 2 CO 3
I
Feed
Scrubber
Downcomer
Sample Point
Feed
Tank
502
Flow (U.V.)
Bottoms
( .$OOO gal) Sample Point
-------
Gas
Water
Q ct Make-Up
\\ n .Liquid
— \ 1 Point
I I
Hold
Tank
‘ —a
0
C ’
Scrubber
Flue Gas
Liquor
Filter
Solids
Blowdown
FIGURE 5-2a - SCRUBBER SYSTEM FLOW SHEET FOR RUN hR
-------
Liquid Sampling
Point
Flue Gas
1
—
Filter
Solids
Stack Gas
Water
Boiler
I-I
D
\ rubber
SO 2
Liquor
FIGURE 5-2b - SCRUBBER SYSTEM FLOW SHEET FOR RUNS 18R-22R
-------
LIMESTONE
STACK GAS
_ ft
SCRUBBER
HOLD
TANK
DOWNCOMER
i I I ____________
FLUE GAS
0
BOTTOMS
LIQUOR
SCRUBBER SPRAY
Slurry Sampling
P oth t
SOLIDS’ [ IE J
FILTER I
FIGURE 5-3a - SCRUBBER SYSTEM FLOW SHEET FOR TAIL-END ADDITION
TESTS (SINGLE BED)
-------
STACK GAS c? 1 1
LIMESTONE
DOWNCONER
‘V
1
1
A
0
.0
FLUE GAS
SO 2
Slurry Sampling
Paint
SOLIDS
FILTER
FIGURE 5-3b - SCRUBBER SYSTEM FLOW SHEET FOR TAIL-END ADDITION
TEST (DOUBLE BED)
-------
injected limestone scrubbing processes, an additive feeder
was installed in the inlet flue gas system which fed metered
quantities of coal fly ash and/or boiler calcined limestone into
the flue gas stream.
The process hold tank had a maximum capacity of
6,000 gallons and was designed to allow operation at lower
capacities. A variable speed stirrer was mounted on the
process hold tank for keeping the solids suspended and the
tank well mixed. There was also an additive feed system
connected to the process hold tank which allowed the metered
feeding of an additive to the hold tank.
The Combustion Engineering pilot unit also was
equipped with a 20,000 gallon clarifier and a vacuum filter
for dewatering clarifier sludge.
5.1.2 Instrumentation
The flow rate of the flue gas stream leaving the
marble bed contactor was measured with a calibrated pitot tube
and the inlet flue gas flow rate was calculated by accounting
for a 77 air leak in the scrubber and a change ih the flue gas
humidity. The temperature and humidity of both the inlet and
the outlet flue gases were measured using dry and wet bulb
mercury thermometers. A DuPont 400 U.V. analyzer was used to
measure the SO 2 concentrations of the inlet and the outlet flue
gases. This SO, analyzer was calibrated before each test with
a standard S0 2 -air mixture.
-l10 -
-------
The instrumentation for aqueous streams included
magnetic flow meters for primary slurry flows. Pumps and valves
were manually regulated.
5.1.3 Instrument Calibration
Two preliminary sodium carbonate tests were performed
in August 1971 and calculations by Radian indicated a 30-40%
error in the sulfur material balance. Recalibration of the
liquid flow meters by Combustion Engineering showed that the
liquid flow rates were about 12% larger than indicated.
Recalibration of the gas flow rate instruments and
the discovery of several air leaks into the marble bed contactor
accounted for the remaining sulfur material balance error.
These first two sodium carbonate tests were rerun
using the recalibrated instrumentation.
5.1.4 Sampling and Analytical Procedures
The sLurry sampling points utilized in each phase
of the SO 2 scrubbing tests are indicated on the scrubbing flow
schemes presented in Figures 5-1, 5-2a, 5-2b, 5-3a, and 5-3b. By
use of a small laboratory pump, slurry samples were pumped from
the sampLing points to a central sampling bench. Representative
temperature and pH measurements were taken by continuously pumping
the slurry over the pH electrodes and the mercury thermometer.
SLurry samples were taken for percent solids measurements. The
slurry samples were also pumped through a 0.8 micron Millipore
filter for the purpose of collecting solid samples and clear
liquid samples.
-ill-
-------
Slurry sampling lines, sampling probes, and the
sampling pump were sized and designed for collecting slurry
samples as rapidLy as feasible, minimizing changes due to
chemical reactions. Because the marble bed liquor was not
uniform over the scrubber cross section due to non-uniform
gas distribution, downcomer slurry samples were taken from
both sides of the marble bed and averaged.
The solids and liquor samples were chemicaLly
analyzed in Radian Corporation’s laboratories using the
procedures documented in Radian Final Report on EPA Contract
CPA-70-143.
5.2 Test Program and Objectives
Radian Corporation designed the original test program
for the Windsor lime/limestone wet scrubbing tests under EPA
Contract CPA 70-45. The primary objectives of the test pro-
gram were to:
(1) determine the rate limiting steps and their
values in the lime/limestone wet scrubbing
system. These rate steps include vapor-liquid
mass transfer rates, solid-Liquid mass transfer
rates, and oxidation rates. The adequate
determination of these rates is required to
predict SO 2 removal as a function of process
conditions and thus properly design Lime/lime-
stone wet scrubbing processes for the broad
spectrum of control appLications.
(2) assess the scaling problems created by handling
supersaturated slurries.
-112-
-------
(3) evaluate the sampling and analytical techniques
developed by Radian for dealing with super-
saturated slurries.
5.2.1 Phase I - Soluble Sodium Carbonate Tests
In order to efficiently attain the three primary
objectives mentioned above, the Radian test program was divided
into three phases. Phase I consisted of once-through flue gas
scrubbing with a clear sodium carbonate scrubbing liquor.
Since sodium carbonate is a highly soluble alkali scrubbing
agent and its reaction products are soluble, the effects of
slurries, crystallization, dissolution, and supersaturation
were eliminated from the Phase I scrubbing tests. This allowed
the Phase I scrubbing tests to concentrate on the following
three points:
(1) What is the effect of major contacting
variables on vapor-liquid mass transfer
rates in a pilot scale marble bed?
(2) What is the approach to vapor-liquid
equilibrium in a pilot scale marble bed?
(3) Is the vapor or liquid film resistance
controlling?
The operating conditions of the 16 sodium carbonate
scrubbing tests which comprised Phase I are listed in Table
5-1. In these Phase I tests the following contacting variables
were manipulated to assess their relationship to the above
three questions:
-113-.
-------
TABLE 5-1
SCRuBBER OPEMTINC CONDITIONS
Ltauor Flow Rate. (amw ) Outlet SOS CO
flcefltr atton
Feed C . Flow Ret. Drwpotnt (‘fl Ge. T .( ’F) ( ppw )
*bavs Below wncowsr Bottow ( c at j3Q7 ) In Out In Out In
h-a
1k:
Test
No.
Set 1
Set 2
Date
10/29/71
Peed Coeposttlon
(owole/i NaCO.)
10.30
10.55
Liquor Towp. C’ F)
54 107
54 107
149
149
19.3
20.0
10,960
10,960
fl
111
111
120
120
111
112
232
231
123
123
2,020
2.020
880
880
2k:
Set 1
Set 2
10/27/71
11.90
11.55
112
111
129
129
-— 165
—— 165
88
85
77
80
10,750
10,800
118
123
294
292
129
129
2,050
2,030
750
760
3k:
Set 1
Set 2
10/14/71
11.45
11.10
52
52
105
105
-— 170
-— 170
160
160
13
15
11,200
318
102
2,095
860
4k:
Set 1
Set 2
10/28/71
10.70
114
117
127
129
—— 170.5
- — 170
153
150
15.3
15.3
10,775
10,800
118
121
306
309
130
130
2,030
2.030
800
790
58:
Set 1
Set 2
11/02/71
12.05
12.50
102
102
120
120
53 106
53 107
150
145
14
14
12,980
12,980
117
120
298
298
122
122
2,273
1.020
68:
Set 1
Set 2
11/02/71
13.15
13.20
115
115
125
123
55 110
55 110
135
136
29
24
9,180
9,180
122
121
304
304
127
127
2,050
480
iRa
Set 1
Set 2
11/03/71
12.85
13.00
112
112
122
123
69 152
69 152
185
185
34.5
34.5
11,240
11,240
116
123.5
291
299
122
122
2,000
2,000
450
460
8k:
Set 1
Set 2
11/03/71
15.55
13.75
109
116
121
125
36 73
36 73
93
90
15.0
15.5
11,200
11,190
116
123.5
312
300
125
125
1,780
830
9k:
Set 1
Set 2
10/29/71
12.65
13.05
110
110
121
121
54.5 116
54.0 116
15%
155
14.5
14.3
11.000
10,910
115
119
292
295
126
126
2,050
2,010
700
730
10k:
Set 1
Set 2
11/09/71
12.90
12.80
110
111
120
121
53 112
53 112
153.6
152.8
9.9
10.7
10,680
10.690
114
120
302
304
120
121
1,980
1.960
540
520
118:
Set 1
Set 2
10/14/71
55.70
59.25
52
52
84
84
- - 165
— — 165
155
160
14.0
13.0
11,500
11,400
288
108
1.980
120
128:
S.t 1
Set 2
11/09/71
66.90
67.70
110
110
121
121
53.5 110
53.0 110
150
150
17
17
11,210
11,200
114
118
295
295
122
122
2,020
1.980
110
110
13k:
Set 1
Set 2
11/06/71
17.40
18.05
111
111
119
119
54 110
56 110
153
153
16.3
16.5
11,330
11,400
116
123.5
298
298
122
122
2.050
2.040
380
280
148:
Set 1
Set 2
11/05/71
16.40
16.25
113
115
122
122
36 75
36 75
95
95
15
14
11 .300
11,360
113
122
300
299
129
128
2,070
2,040
780
780
15R:
Set 1
Set 2
11/05/71
17.10
17.40
111
111
120
120
55 110
53 110
143
146.3
16.5
16.5
12,980
12,980
115
118
302
299
120
121
2,040
2,040
500
500
168:
Set 1
Set 2
11/05/71
17.60
18.85
110
109
116
114
35.5 110
35.5 110
143
145
20
20
11,500
11,300
111
118
223
222
116
113
2,010
2,020
330
330
-------
• gas flow rate
• liquor spray rate above bed
• Liquor spray rate below bed
• Na 2 CO 3 concentration in the scrubbing liquor
• inlet flue gas temperature
Figure 5-1 is a diagram of the scrubbing flow scheme utilized
in the Phase I tests. The results and conclusions obtained
from these tests are discussed in Section 5.4 of this report.
5.2.2 Phase II - Limestone Injection Wet Scrubbing Tests
Phase II of the Radian test program was composed of
six limestone injection/wet scrubbing tests with either slurry
or clear liquid recycle. In the limestone injection/wet scrub-
bing process, finely ground limestone is injected into the
boiler where it is calcined to CaO and partially reacts with SO 2
to form CaSO 4 . The unreacted GaO, along with the CaSO 4 , is
entrained in the flue gas and hydrated down stream in the
scrubber where it forms an alkali scrubbing medium.
The primary objectives chosen for the Phase II tests
program were to:
(1) observe the rates at which the gaseous
species (SO 2 , C0 2 , 02) are transferred
to or from the scrubber luquor,
(2) observe the rate at which a boiler-calcined
limestone additive hydrates and dissolves
in the scrubber liquor and in the hoLd tank
liquor,
-115-
-------
(3) observe the rates at which the solid waste
products precipitate from the liquor,
(4) observe the rates and types of chemical
reactions in the aqueous phase which determine
the driving forces for the above three rate
steps,
(5) determine the applicability of laboratory
determined precipitation and dissolution rate
expressions,
(6) confirm the vapor-liquid mass transfer
correlations derived from the sodium
carbonate scrubbing test data,
(7) establish the supersaturation limits for
the scale-free operation of large scrubbing
units.
(8) demonstrate the ability of Radian sampling
and analytical techniques to characterize a
supersaturated slurry stream.
Table 5-2 presents the pilot scrubbing unit operating
conditions for the Phase II test series. The operating
parameters which were varied in order to assess their relation-
ship to the limestone injection/wet scrubbing system’s perfor-
mance include:
additive stoichiometry (from 65% to 80%),
percent solids in the scrubber spray (from
o to 8.5),
-116-
-------
TABLE 5-2
OPERATING CONDITIONS - LIMESTONE INJECTION/WET SCRUBBING TESTS
21R 22R
Test Number 17R l8R 19R 20R ( CE 24R) ( CE 23R )
Stoichiometry (7.) 65 65 75 75 80 80
Outlet Gas Flow Rate 11,000 11,000 10,000 10,000 9,700-10,000 9,900
(acfm at 130° F)
Approximate Percent 3.5 1.4 0.7 7.5 8.5
Solids in Scrubber
Spray
Liquid to Gas Ratio 10 18.5 20 20.5 20 36
(gal/l000 acf)
Gas Temperature (°F):
In 236 290 290 300 340 300
Out 125 125 112 115 120 120
Gas Dewpoint (°F):
In 132 110 108 108 108
Out 123 105 110 115 115
SO 2 Concentration
(ppm):
In 1,500 1,500 1,880 1,950 2,000 2,020
Out 750 390 1,060 1,250 780-845 520-590
Liquor Flow Rates
(gpm):
Spray 110 205 200 205 200 355
Downcomer 90 180 175 180 180 260
Bottoms 25 30 20 20 20 95
Clarifier Feed 145 25 35 80 10 10
Clarifier Liquid 110 25 --- 40 10 10
Returned
Clarifier Bottoms 4 3 3 4 3
Make-Up Water 55 3 40 45
Blowdowrt 55 - - - 35 40 - --
Hold Tank Volume 6,000 6,000 6,000 6,000 3,000 5,300
(gal)
—117—
-------
• liquid to gas ratio (from 10 to 36 gal/103 acf),
inlet flue gas temperature (from 236° F to 340°F),
• SO 2 concentration in the inlet flue gas (from
1500 to 2020 ppm),
• system blowdown (from 0 to 55 gpm),
• hold tank volume (from 3000 to 6000 gaL)
Figures 5-2a and 5-2b show the flow schemes used for
these tests. The results and conclusions derived from the six
limestone injection - wet scrubbing tests comprising Phase II
are presented in Section 5.5 of this final report.
5.2.3 Phase III - Limestone Tail-End Addition Tests
Phase III of the lime/limestone wet scrubbing test
program was composed of six limestone tail-end addition tests.
Three tests used a single marble bed scrubber and three tests
used a double marble bed scrubber. One objective of these
tests was to permit extrapolation of single-bed data which
had to be taken at Shawnee to predict double-bed operation.
The limestone tail-end addition/wet scrubbing flow scheme
(Figures 5-3a and 5-3b) was chosen for investigation because
it too has proven to be one of the most promising SO 2 control
systems currently being developed. In the limestone tail-end
addition/wet scrubbing system, limestone provides the alkali
scrubbing agent and is added to the scrubbing system in the
hold tank. Part of the limestone not reacting in the hold
tank is slurried to the marble bed scrubber where it dissolves
and provides increased alkalinity for SO 2 removal.
-118-
-------
The basic objectives in the Phase III limestone
tail-end addition/wet scrubbing tests were to:
(1) observe the rates at which the limestone
additive dissolves in the marble bed scrubber
and in the hold tank,
(2) observe the rates at which the gaseous species
(S0 , C0 , 02) are transferred to or from a
limestone based scrubbing liquor,
(3) observe the rates at which the solid waste
products precipitate from a Limestone based
scrubbing liquor,
(4) observe the rates and types of chemical reactions
in the aqueous phase of limestone scrubbing
systems which determine the driving forces for
the above rate steps,
(5) determine the applicability of laboratory
determined precipitation and dissolution rate
expressions,
(6) confirm the vapor-Liquid mass transfer correlations
derived from the sodium carbonate and limestone
injection scrubbing test data,
(7) establish the supersaturation limits for the
scale-free operation of large limestone scrubbing
units.
-119-
-------
Table 5-3 lists the operating conditions for the
six limestone tail-end addition/wet scrubbing tests. The “B”
series of scrubbing tests were double marble bed tests with
the L/G per bed equivalent to the L/G per bed of their counter-
part in the single marble bed “A” series tests. The additive
stoichiometries of the “A” and “B” tests were varied in a similar
fashion. For aLl six of the Phase III limestone tail-end addition
tests, the flue gas rate was held at approximately 10,000 ACFM,
the percent solids at approximately 7.57 , the inlet flue gas
temperature at approximately 200°F, the inlet SO 2 concentration
at approximately 2400 ppm, and the hold tank voLume at approxi-
mately 6000 gal. The clarifier feed rate was varied from 10 to
15 gpm in the “A” tests and was held at 15 gpm for the “B” tests.
The results and conclusions obtained by Radian
Corporation in the limestone tail-end addition tests are discussed
in Section 5.6 of this final report.
5.3 SolubLe Sodium Carbonate Test Results
This section of the final report presents the results
and conclusions obtained by Radian Corporation in the Phase I
soluble sodium carbonate wet scrubbing tests. The flow scheme
and operating conditions utilized in these tests were presented
in Figure 5-1 and Table 5-I.
5.3.1 Analytical Results
Results of the chemical analyses performed on liquor
samples taken from each of the wet scrubbing process streams are
presented in Table 5-4. The electroneutrality imbalances
-120-
-------
TABLE 5-3
OPERATING CONDITIONS - LIMESTONE TAIL-END
ADDITION TESTS
Test Number 1A . 2A 3A . lB 2B 33
Stoichiometry (mole per- 157 145 98 152 147 94
cent based on inlet So 2 )
Outlet Gas Flow Rate
(acfm at 130° F) 10220 10080 9930 10090 10300 10280
Approximate Percent Solids Sample
Lu Scrubber Spray 7.5 6.6 7.6 6.6 8.6 1.ost
Liquid to Gas Ratio
(gal/1000 acf) 15 24 24 31 46 47
Gas Temperature (°F)
In 220 183 212 194 217 212
Out 122 124 149 134 131 124
Gas Dew Point (°F):
1n 105 113 106 114 113 115
Out 118 120 122 127 126 122
S0 Concentration (ppm):
In .2310 2505 2345 2410 2435 2375
Out 1110 1010 980 545 290 365
Liquor Flow Rates (gpm):
Upper Bed
Spray ——— --— 150 225 235
Downcomer ——— ——— —-— 110 175 180
Lower Bed
Spray 150 240 243 160 245 250
Downcomer 135 180 185 170 205 215
Bottoms 15 60 58 30 90 90
Clarifier Feed 12 15 10 15 15 15
Clarifier Weir 12 14 10 15 15 15
Clarifier Bottoms 0 1 0 0 0 0
Makeup Water O
Blowdown 0 0 0 0 0 0
Bold Tank Volume (gal) 6000 6000 6000 6000 6000 6000
Upper Bed p11 -—— —-— --- 5.8 5.7 5.5
Lower Bed pH 5.4 5.1 5.3 5.7 5.5 5.2
-121-
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TABLE 5 t’ 4
CUD IICAL ANALYSES OF CE SOLUBLE TEST SAXPLES
Concentrations in Millimole/Liter
Experiment * + pH Temperature t Ion
Number Date Sample Location Ca H z Na K Total S S0 • C0 Cl Total N low/hizh ( °C) Imbalance
1K: Set 1 Feed 0.2 0.64 10.30 43.8 +6.6
Downcomer 16.35 2.95 5.20/5.50 49.4 +0.6/+0 . 6
Pump Discharge 0.92 0.31 20.6 19.35 0.12
Bottom 0.91 0.38 21.1 17.5 15.8 5.64 0.52 5.65 48.8 +1.8
Set 2 Feed 0.11 0.37 21.1 0.2 11.6 10.30 43.8 +2.0
Downcomer 14.95 3.03 5.10/5.28 49.4 +0.l/-0.3
Pump Discharge 21.7 19.5
Bottom 21.5 18.1 15.8 6.11 5.92/6.00 48.8 +1.71-2.3
2K: Set 1 Peed 0.98 0.38 23.8 0.2 14.4 0.47 0.38 10.38 44.4 +2.5
Downcomer 17.3 4.36 5.90/6.05 53.9 -5 . 61- 4.7
Pump Discharge 1.01 0.39 24.0 0.013 20.5 0.49 0.25
‘ S . ) Bottom 0.88 0.38 24.2 20.6 14.6 0.49 0.26 5.95/6.05 53.9 -5 .6 1 -4.9
Set 2 Feed 23.1 0.2 13.8 10.36 43.8 -1.5
Downcomer 16.55 3.87 5.95/6.05 53.9 -4.2/-2.4
Pump Discharge 23.7 20.
Bottom 23.4 20.7 15.5 3.45 5.9 /6.05 53.9 -5 .5 1-4 .6
3K: Set 1 Feed 0.03 0.37 23.9 0.3 0.3 12.74 0.60 10.93 1.5.0 -2.5
Downcomer 1.02 0.40 24.5 23.9 20.3 3.81 0.56 4.40/4.65 34.0 -2 .0 1-1 .8
Pump Discharge
Bottom 0.84 0.39 23.1 19.65 16.8 7.02 0.67 5.15/6.00 39.0 -3.2 1- 1.3
Set 2 Feed 0.32 0.37 22.2 0.4 0.4 11.16 0.63 10.90 16.0 +0.6
Downcomer 1.35 0.41 23.9 23.5 23.5 3.82 0.59 3.68/4.0 34.0 +3.4/ 43.7
Pump Discharge
Bottom 1.05 0.41 22.4 19.8 19.8 6.59 0.60 5.62/5.9 39.0 +2.8
* Values given for the downccwer location are an average of two downcemer samples.
+ SO analyses done by CE except for ina 3 K and ilK.
-------
TABLE 5-4-CH 2lICAL ANALYSES OF CE SOLUBLE TEST S PLES (coat.) Page 2
Concentrations in Millitnole/Liter
Experiment * + pH Temperature 7. Ion
Number ) ate Sample Location Ca Mg Na K Total S $02 ‘ CO 2 Cl Total N low/high ( °C) Imbalance
4R: Set 1 Feed 0.2 10.3 64.6 46.6
Downcomer 18.15 2.12 3.75/5.29 53.3
Pump Discharge .91 .36 20.2 19.3
Bottom .91 .37 20.5 0.013 17.2 15.1 5.31 5.9 52.2 -0.2
Set 2 Feed .91 .37 21.4 0.2 10.9 10.30 46.2 +5.5
Downconier 17.9 2.17 3.93/5.36 53.9 +2.71+2.8
Pump Discharge 20.9 19.6
Bottom 21.6 16.8 14.8 5.64 6.02 52.2 +1.3
5R; Set I Feed 0.94 0.38 24.1 0.2 15.0 0.50 10.37 38.9 -3.0
Downco mer 20.0 3.04 0.54 5.32/5.57 48.9 -2.0/-2.7
Pump Discharge 0.98 0.39 24.5 23.6
Bottom 1.00 0.40 25.1 0.013 22.6 21.4 5.31 0.54 5.84 51.7 +0.1
Set 2 Feed 25.0 0.2 14.7 10.38 38.6 -0.7
Downcomer 20.2 6.54 5.3 /5.58 48.9 -1.31-2.4
Pump Discharge 24.5 23.3
Bottom 25.5 22.2 21.4 5.72 5.85 51.7 -1.3
6R: Set 1 Feed 0.83 0.39 26.3 0.2 15.9 0.51 10.35 46.1 -3.1
Downconier 20.7 4.73 5.92/6.12 51.1 +0.71-0.7
Pump Discharge 0.98 0.39 26.5 22.6 0.50
Bottom 0.93 0.40 26.6 18.0 14.9 9.12 0.51 6.32/6.44 51.1 -1.91-0.5
Set 2 Feed 26.4 0.2 15.6 10.35 46.1 -2.1
Downcomer 20.5 4.67 5.88/6.12 51.1 -0.91-2.6
Pump Discharge 26.2 23.1
Bottom 27.3 18.6 16.7 3.94 6.38/6.43 51.1 -3.51.4.0
* Values given for the dovncomer location are an average of t downcemer ssples.
+ SO, analyse, dons by cg except for tans 3R and ha.
-------
TABLE 5-4 - CHDIICAL ANAJ.YS 0 CE S .UBLE TEST SA1 LES (cant.) Page 3
Concentrations in Ilillimole/Liter
Experiment * + p11 T erature 7. Ion
Number Date Sample Location Ca ? t Na K Total S SO. ‘ C0 Cl Total N low/high ( °C) Imbalance
7R: Set 1 Feed 0.82 0.37 25.7 0.2 14.7 0.64 10.7 44.4 .5.5
Downcomer 19.8 5.26 6.05/6.4 48.9 +5.0/+1.6
Pump Discharge 0.95 0.38 26.6 20.0 0.51
Bottom 0.99 0.38 26.7 21.0 18.5 7.56 0.52 6.15/6.2 50.0 -1.41-0.9
Set 2 Feed 26.0 0.2 13.92 0.53 10.68 46.7 -2.2
Downcoiner 17.7 5.32 6.06/6.35 49.4 -3.21+0.5
Pump Discharge 25.2 19.1
Bottom 25.5 20.7 18.6 6.36 6.06/6.18 50.5 -1.1/0
8R: Set 1 Feed 0.74 0.36 31.1 0.2 16.9 10.46 44.7 -0.1
Downcomer 22.9 3.62 5.78/6.00 49.4 48.11+6.8
Pump Discharge 0.92 0.37 33.5 24.1
Bottom 0.83 0.37 31.5 19.7 17.6 11.3 6.5 51.1 -0.2
Set 2 Feed 27.5 0.2 15.9 10.38 46.6 -2.0
Downcomer 21.8 3.57 5.56/5.65 51.6 -1.9/2.2
Pump Discharge 27.7 25.6
Bottom 29.6 19.7 18.5 9.69 6.38 51.6 +1.2
9R: Set 1 Feed 0.75 0.36 25.3 0.25 13.7 0.56 10.38 43.3 +1.5
Downcomer 18.3 3.55 5.65/5.9 49.4 -0.6/-0.9
Pump Discharge 0.92 0.37 25.2 22.1 0.51
Bottom 0.91 0.37 25.0 0.013 20.1 18.2 7.33 0.55 6.01 48.8 +0.2
Set 2 Feed 26.1 0.25 13.7 10.38 43.3 +2.8
Downcower 18.1 5.45/5.84 49.4 +3.41+3.2
Pump Discharge 24.3 21.5 3.55
Bottom 25.0 19.4 18.7 6.23 5.98 48.8 +3.2
* Values given for the doiinconer location s an average of t dovnc er awple..
+ SO analyses done by CE except for sins 3R and lift.
-------
TABLE 5- - CH IICAL ANALYSES OF CE SOLUBLE TESf SAMPLES (cont.) Page 4
Concentrations in MillimolefLiter
Experiment * + pH Temperature Ion
Number Date Sample Location Ca Mg Na K Total S SO. CO Cl Total N low/high ( °C) Imbalance
10k: Set 1 Feed 0.96 0.39 25.8 0.2 15.8 10.35 43.3 -2.9
Downcomer 20.1 5.37 5.62/5.8 48.9 +0.61-0.4
Pump Discharge 2.88 0.43 26.2 24.4
Bottom 1.81 0.39 26.3 22.2 20.4 5.19 +1.31+2.5
Set 2 Feed 25.6 0.2 15.2 10.32 49.2 -2.1
Downcomer 19.6 3.59 5.65/5.85 47.6 -1.91-2.8
Pump Discharge 26.4 23.8
Bottom 26.2 22.6 19.9 4.69 5.95/6.08 49.44 -1.8/-0.9
11R: Set 1 Feed 0.18 0.35 111.4 0.43 59.27 0.63 0.44 11.45 14.5 3.4
Downcomer 0.41 0.36 109.5 36.9 33.9 46.26 0.65 0.36 7.2 / 7.4 34.0 +0.11+1.8
Pump Discharge
Bottom 0.53 0.38 110.6 37.5 32.0 43.34 0.67 0.39 7.55/7.8 37.0 -1.11+0.1
Set 2 Feed .04 0.30 118.5 0.3 57.59 0.63 11.44 15.0 +1.5
Downcomer .49 0.36 114.7 37.55 36.0 53.96 0.66 7.28/7.5 34.5 1.4/+0.3
Pump Discharge
Bottom .48 0.36 117.1 39.9 34.6 52.80 0.63 7.25/7.5 37.0 -2.0/-0.2
12k: Set 1 Feed 1.30 0.37 133.8 0.013 0.2 66.5 0.44 10.77 43.6 +1.5
Downcomer 28.7 65.9 7.78/8.02 49.4 -3.0/+2.1
Pump Discharge 0.18 0.36 133.1 0.012 30.8 0.32
Bottom 0.21 0.36 135.4 0.013 34.6 34.1 64.8 0.47 7.62/7.75 50.0 +2.0/+2.7
Set 2 Feed 135.4 0.2 67.8 10.75 63.3 +1.2
Douncomer 28.1 68.3 7.97/8.15 49.4 +1.5/+0.9
Pump Discharge 133.2 30.8
Bottom 133.6 34.1 32.9 65.1 7.82/7.95 50.5 +0.9/+1.4
* Values given for the downcooer location are an averag, of t downcemer .emipi.s.
+ SO analyaee done by CE except for ne 3k and lift.
-------
TABLE .4 - CH 4ICAL ANALYSES CE LUBLE TEST M) LES . (emit.) Page 5
Concentrations in Millimole/Liter _______________
k cperiment * + pH Tanperature Z Ion
Number 1 te Smi ,ie Location Ca P Na K Total S SO ‘ CO. ci Total N low/high ( °C) Imbalance
13R: Set 1 Feed 0.86 0.35 34.8 0.2 19.1 10.48 42.6 -0.3
Downcomer 24.2 5.04 5.95/6.22 48.6 -0.1/-2.1
Pump Discharge 0.85 0.36 33.6 27.8
Bottom 0.70 0.37 34.8 25.3 22.0 9.96 6.4 48.9 -2.6
Set 2 Feed 38.1 0.2 19.9 10.52 42.6 +1.4
Downcomer 25.0 6.73 6.08/6.35 48.3 -1.61-4.2
Pump Discharge 32.8 27.6
Bottom 40.4 26.3 23.1 11.9 6.43 48.9 0.0
14R: Set I Feed 1.11 0.39 32.8 0.2 19.4 10.37 46.1 -2.0
Downcomer 26.6 3.80 5.63/5.87 50.0 -0.61-1.7
Pump Discharge 1.02 0.40 33.6 30.4
Bottom 0.61 0.40 34.6 22.8 21.2 12.5 6.48/6.55 50.0 -2.3/-1.3
I- .
N.)
Set 2 Feed 32,5 0.2 18.5 10.37 46.1 - -0.2
Downcomer 25.6 4.71 5.72/5.81 50.0 -2.8/-3.3
Pump Discharge 33.9 30.6
Bottom 33.6 22.0 20.2 12.7 6.5 50.0 -1.9
15R: Set 1. Feed 0.87 0.39 34.2 0.2 20.0 10.38 43.6 -1.8
Downcomer 26.1 5.03 5.42/6.18 48.9 +2.1/+2.0
Pump Discharge 0.97 0.40 35.2 29.7
Bottom 0.91 0.40 35.0 28.2 25.7 8.54 6.33 48.9 -3.0
Set 2 Feed 34.8 0.2 20.1. 10.38 43.6 -1.2
Downcomer 25.8 5.58 5.96/6.25 48.9 -0.6/-2.9
Pump Discharge 35.1 29.5
Bottom 35.1 27.8 25.4 8.90 6.23 49.2 -1.5
* Values given for the downcceer location are an averag. of t do mco..r . les.
+ SO analyses done by CE except for I ns 3K and 11K.
-------
TABLE 5-4 - CH 1ICAL ANALYSES OF CE SOLUBLE TEST SAMPLES (cent.) Page 6
Concentrations in Millimole/Liter
Experiment * + pH Temperature ZIon
Number Date Sample Location Ca Na K Total S SO CO 2 Cl Total N low/high ( °C) Imbalance
16R: Set 1 Feed 0.84 0.39 35.2 0.2 19.8 10.38 41.8 -1.3
Downcomer 24.9 5.72 6.03/6.42 46.3 +0 .4 1-3.3
Pump Discharge 1.15 0.40 34.9 0.014 28.3
Bottom 0.91 0.40 35.4 25.6 18.8 11.3 6.37/6.45 46.5 -6.01-5.1
Set 2 Feed 37.7 0.2 19.6 10.38 41.8 +3.4
Downconier 24.1 6.73 6.02/6.35 45.5 -0.1/-3.1
Pump Discharge 36.2 28.5
Bottom 36.0 25.3 22.5 12.2 6.44/6.55 46.13 -4.1/-2.6
* Values given for the doimcomer location are an average of two do mcoe*r samples.
+ SO analyses don. by CE except for Runs 3R and hR.
-------
calculated for each chemical analysis are included in this table.
The percentage values shown are a ratio of the charge imbalance
to the total equivalents of charged species analyzed for a given
sample. This percentage is a measure of the accuracy of the
liquid phase chemical analyses. In general the percentage
imbalance has been less than 57 in previous work of this type.
All of the data sets for the sodium carbonate tests except
Runs 2R1 and 8R1 have resulted in a reasonable charge balance.
Further discussion of this subject is given in Radian Technical
Note 200-014-05.
As a further check on the accuracy of the sampling
and analytical techniques total sulfur material balances were
performed around the scrubbing system. The results are
presented in Table 5-5. The gas and liquid phase t, sulfur terms
were calcuLated from the relationship:
= flow x concentration)
- ut flow x concentration) (5- 1)
The results were well within expected experimental
error (<47 ) for all runs except 3R. Further discussion of
this subject is given in Radian Technical Note 200-014-05.
5.3.2 Vapor-Liquid Mass Transfer Rates
From the chemical analysis of the downcomer stream,
vapor-Liquid equilibrium caLculations were made for the marble
bed scrubber in each test using an updated version of the Radian-
developed chemical equilibrium program. Comparison of actuaL
S0 concentrations in the gas leaving the scrubber with
-128-
-------
TABLE 5-5
TOTAL SULFUR MATERIAL BALANCE
Liquid Out Total S Liquid Out Total S
Gas Out SO Out Gas In SO In S Gas Liquid In Total S In Bottom Bottom Downconier Down t S Li 9 uid
Run No. ( gniole/min) ( ppm) ( mole/min) ( ppm) ( gmole/min) ( gpm) ( nunole/L) ( gpir) ( amiolefL) ( gpm) ( mmole/L) ( gmoleimin )
1R: Set 1 11,550 880 10,930 2,020 11.9 161 0.2 19.5 17.5 149 19.35 12.1
Set 2 11,550 880 10,930 2,020 11.9 161 0.2 20.0 18.1 149 19.50 12.2
2R: Set 1 11,340 750 10,390 2,050 12.8 165 0.2 77.0 20.6 88 20.50 12.7
Set 2 11,390 760 10,440 2,030 12.5 165 0.2 80.0 20.7 85 20.00 12.6
3R: Set 1 11,820 860 10,820 2,095 12.5 170 0.3 15.0 19.65 160 23.9 15.4
Set 2 11,820 860 10,820 2,095 12.5 170 0.4 15.0 19.8 160 23.5 15.1
4k: Set 1 11,370 800 10,485 2,030 12.2 170.5 0.2 15.3 17.2 153 19.3 12.0
Set 2 11,390 790 10,510 2,030 12.3 170 0.2 15.5 16.8 150 19.6 12.0
5k: Set 1 13,690 1,020 12,630 2,275 14.8 161 0.2 14.0 22.6 150 23.6 14.5
Set 2 13,690 1,020 12,630 2,275 14.8 162 0.2 14.0 22.2 145 23.3 13.8
6k: Set 1 9,685 480 9,070 2,050 13.9 165 0.2 29.0 18.0 135 22.6 13.4
Set 2 9,685 480 9,070 2,050 13.9 165 0.2 24.0 18.6 136 23.1 13.4
7k: Set 1 11,860 450 10,760 2,000 16.2 221 0.2 34.5 21.0 185 20.0 16.6
Set 2 11,860 460 10,760 2,000 16.1 221 0.2 34.5 20.7 185 19.1 15.9
BR: Set 1 11,820 830 10,720 1,780 9.3 109 0.2 15.0 19.7 93 24.1 9.5
Set 2 11,805 830 10,710 1,780 9.3 109 0.2 15.5 19.7 90 25.6 9.8
9k: Set 1 11,605 700 10,670 2,050 13.8 170.5 0.25 14.5 20.1 155 22.1 13.9
Set 2 11,510 730 10,590 2,010 12.9 170.5 0.25 14.5 19.4 155 21.5 13.5
1OR: Set 1 11,270 540 10,290 1,980 14.3 165 0.2 9.9 22.2 153.6 24.4 14.9
Set 2 11,280 520 10,300 1,960 14.3 165 0.2 10.7 22.6 152.8 23.8 14.5
11R: Set 1 12,130 120 11,620 1,980 21.5 165 0.43 14.0 37.5 155 36.9 23.3
Set 2 12,030 120 11,530 1,980 21.4 169 0.30 13.0 39.9 160 37.55 24.5
12R: Set 1 11,830 110 10,890 2,020 20.6 163.5 0.2 17.0 34.6 150 30.8 19.6
Set 2 11,820 110 10,880 1,980 20.2 163.5 0.2 17.0 34.1 150 30.8 19.5
13k: Set 1 11,950 380 10,850 2,050 17.7 164 0.2 16.5 25.3 153 27.8 17.5
Set 2 12,030 280 10,910 2,040 18.9 164 0.2 16.5 26.3 153 27.6 17.5
14k: Set 1 11,920 780 10,780 2,070 13.0 111 0.2 15.0 22.8 95 30.4 12.1
Set 2 11,985 780 10,840 2,040 12.8 111 0.2 14.0 22.0 95 30.6 12.1
15R: Set 1 13,690 500 12,640 2,040 18.9 165 0.2 16.5 28.2 145 29.7 17.9
Set 2 13,690 500 12,640 2,040 18.9 165 0.2 16.5 27.8 146.5 29.5 18.0
16R: Set 1 12,130 350 11,090 2,010 18.0 165.5 0.2 20.0 25.6 145 28.3 17.3
Set 2 12,130 350 11,090 2,020 18.1 165.5 0.2 20.0 25.3 145 28.5 17.4
-------
equilibrium SO 2 concentrations for the liquor gives a measure
of the vapor-liquid mass transfer capability of the scrubber.
In these calculations the marble bed scrubber was
assumed to be a well mixed contactor with respect to the liquid
phase. Because the bed composition is known to vary from side
to side, two cases were considered for each data set. These
used the highest and lowest measured pH values as inputs,
giving a range of the highest and lowest equilibrium SO 2 partial
pressures for each data set.
Results are presented in Table 5-6. The “relative
overall mass transfer coefficients” listed in the right hand
column are based upon the following reLationship:
*
-y
Ka= Cg, ( 2 in (5-2)
g V yQfl
‘ 2 out
where G is the gas flow rate and y is the partial pressure
of SO 2 in equilibrium with the marble bed calculated from
the chemical analysis of the liquor. Normally V is the volume
of the agitated layer in the marble bed, but because of the
difficulties encountered in determining this volume, a V was
arbitrarily chosen based uion the Kga of Test 9R being set
equal to 1.0. Therefore, reported Kga’s are all relative to
the Kga of Test 9R (Set 1).
The percent approach to equilibrium shown in Table
5-6 was determined by:
-130-
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TABLE 5.6
VAPOR LIQUID E JILIBRIU1 J CALCULATIONS FOR Na .CO . TE
Ex mental SO ( Relative Overall
per 2 Equilibritun SOa (ppm) Liquor pH % Approach to Haag Transfer Coefficient
Pun No. Out In low/high low/high Equilibrium low/hLgh
1R: Set 1 880 2,020 9/20 5.2 /5.5 55 0.8/0.8
Set 2 880 2,020 15/24 5.1 /5.28 55 0.8/0.8
2R: Set 1 750 2,050 3/5 5.9 /6.05 65 0.9/0.9*
Set 2 160 2,030 3/4 5.95/6.05 65 0.9/0.9
3R: Set 1 860 2,095 40/71 4.4 /4.65 60 O.9/0.9
Set 2 860 2,095 210/430 3.68/4.0 65/75 l.O/l.3**
4R: Set 1 800 2,030 20/750 3.75/5.29 60/95 0.9/3.0*
Set 2 790 2,030 20/510 3.93/5.36 60/80 0.9/1.5
5R: Set 1 1,020 2,275 10/18 5.32/5.57 55 0.9/0.9
Set 2 1,020 2,275 10/19 5.30/5.58 55 0.9/0.9
6R: Set 1 480 2 050 3/5 5.92/6.12 75 1.1/1.1
Set 2 480 2,050 3/5 5.88/6.12 75 1.1/1.1
7R: Set 1 450 2,000 1/3 6.05/6.4 75 1.4/1.4
Set 2 460 2,000 113 6.06/6.35 75 1.4/1.4
8R: Set 1 830 1 78O 4/7 5.78/6.0 55 0.7/0.7*
Set 2 830 1,780 10/12 5.56/5.65 55 0.7/0.7
9R: Set 1 700 2,050 4/8 5.65/5.9 65 1.0/1.0
Set 2 730 2,010 4/12 5.45/5.84 65 0.9/0.9
1OR: Set 1 540 1,980 5/8 5.62/5.8 75 1.2/1.2
Set 2 520 1,960 4/7 5.65/5.85 75 1.2/1.2
I1R: Set 1 120 1,980 0 7.2 /7.4 95 2.7/2.7
Set 2 120 1,980 0 7.28/7.5 95 2.7/2.7
12R: Set 1 110 2,020 0 7.78/8.02 95 2.7/2.7
Set 2 110 1.980 0 7.97/8.15 95 2.7/2.7
13R: Set 1 380 2,050 2/5 5.95/6.22 80 1.6/1.6
Set 2 280 2,040 2/3 6.08/6.35 85 1.9/1.9
14R: Set 1 780 2,070 6/12 5.63/5.87 65 0.9/0.9
Set 2 780 2,040 7/9 5.72/5.81 60 0.9/0.9
15R: Set 1 500 2,040 3/18 5.42/6.18 75 1.5/1.6
Set 2 500 2,040 2/5 5.96/6.25 75 1.5/1.5
16R: Set 1 350 2,010 1/3 6.03/6.42 85 1.7/1.7
Set 2 350 2,020 1/3 6.02/6.35 85 1.7/1.7
* The electroneutrality imbalance for these cages s unacceptable.
** The material balance for these case. was unacceptable.
-------
yso 2 in - So 2 t
7 = CU xlOO (5-3)
•SO 2 - SO 2
The data given in Table 5-6 indicate that the mass
transfer capability of the marble bed scrubber is most strongly
dependent on the liquor pH. The operating variables of flue
gas temperature, liquor temperature, and gas velocity do not
appear to have as significant an effect on relative mass transfer
as do liquor flow rate and sodium carbonate concentration. The
effect of liquor flow rate appears to be more consistent with
changes in liquid film resistance rather than interfacial area
for mass transfer.
Figure 5-4 is a plot of relative mass transfer
coefficients vs. pH for the soluble sodium carbonate tests.
The trends exhibited in this graph seem to indicate a direct
relationship between downcomer liquor pH and the relative mass
transfer rate.
5 .3.3 Conclusions
From the results obtained in the soluble sodium
carbonate tests the following conclusions were drawn:
(1) The Liquor sampling and analytical techniques
applied were adequate to investigate chemical
processes occurring in soluble sodium carbonate!
wet scrubbing systems.
(2) A vapor-liquid equilibrium approach of 95%
can be obtained in single marble bed with a
high pH sodium carbonate scrubbing liquor.
-132-
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‘Run 7 - High L/C
Run 14 - Low L/G
Run 8 - Low L/G
I I I
3 4 5 6 7 8 9
Marble Bed, pH
FIGURE 5-4 - RELATIVE MASS TRANSFER RATE VS. pH FOR SOLUBLE TEST
3.0
Interinedia te
Liquor
Dilute
00
00
00
0
-c
0
00
cQ O
0
-133-
-------
(3) Operating variables such as gas velocity
and temperature do not appear to have a strong
effect on the overall vapor-liquid mass
transfer rate. This may indicate that the
gas film mass transfer rate does not limit
the overall vapor-liquid mass transfer rate.
(4) The correlation between overall mass transfer
rate and liquor pH exhibited in Figure 5-4
indicates that a Liquid phase resistance is
a substantial portion of the overall vapor-
liquid mass transfer resistance.
5.4 Limestone Injection Wet Scrubbin g Tests
This section of the final report presents the resuLts
and conclusions obtained by Radian Corporation in the Phase II
limestone injection/wet scrubbing tests. The flow sheets and
operating conditions for these tests have been presented in
Figures 5-2a and 5-2b. Because the Combustion Engineering
boiler was not designed to aLlow limestone injection, lime-
stone which had been injected and calcined in a Union Electric
Company boiler was metered into the flue gas stream above the
pilot scrubbing unit.
5.4.1 AnalyticaL Results
The results of the chemical analysis performed by
Radian Corporation’s laboratories on the slurry samples taken
during the limestone injection/wet scrubbing tests are presented
in Appendix D of this report.
-134-
-------
These analytical results again include the electroneutraLity
imbalances calculated by the Radian equilibrium computer program
for each slurry sample analysis. Most of the analyses for the
Limestone injection tests have reasonable charge imbalances,
i.e. less than 57g. There were consistently higher electro-
neutrality imbalances in the marble bed and scrubber bottom
analyses which were due to sampling problems.
As a further check on the accuracy of both the
sampling and the analytical- techniques employed in the Limestone
injection tests, total sulfur material balances were performed
around the scrubbing system. The results of these calculations
are summarized in Table 5-7. The material balance errors were
within 1070 for the marble bed and within 57 for the hold tank.
The marble bed errors were attributed to local variations in bed
composition and to sampling problems. A brief discussion of the
sampling technique employed at Windsor and their impact upon
the accuracy of the analytical results is given below.
Successful characterization of a slurry scrubbing
process depends upon the representativeness of samples taken
from unstable process streams. A previously developed proce-
dure was used to obtain rapid separation of solid and liquid
phases during slurry sampling (see Radian Final Report on
EPA Contract CPA-70-143). A sample was pumped directly from
each process stream into a Millipore filter holder with a
one micron oore size membrane. The sampling rate was such
that the residence time of the slurry in the sample train was
small compared to that of the vessel from which the sample
was drawn. A possible exception to this criteria was the marble
bed itself. The liquid residence time in the marble bed is on
-135—
-------
TABLE 5-7
TOTAL SULFUR MATERIAL BALANCE SUMMARY -
CE PROTOTYPE TESTS 17R-20R
(AlL values in gmoles/min Total S)
Marble Bed Hold Tank
Run Set In Out In Out
17R 1 21.8 19.3 24.4 24.1*
2 21.5 19.1 10.2 8.6
18R 1 119 135 137 142
2 114 129 126 116
19R 1 66.8 70.95 58.2 60.5
2 70.5 71.05 60.8 59.4
20R 1. 57.35 59.0 47.4 51.0
2 58.55 56.9 48.2 53.9
*17R Set 1 hold tank samples taken independently of scrubber
samples.
- 136 -
-------
the order of 30 seconds while the sampling time is about 5-10
seconds.
Care was taken to obtain slurry samples from vertical
lines where possible. This was done to avoid errors due to
vertical gradients in slurry solids concentration. The sever-
ity of possible sampling errors due to radial gradients and
non-isokinetic sampling was checked experimentally. The
solids concentrations in samples drawn through a non-isokinetic
side tap were compared to those obtained using an approximately
isokinetic center probe. This was done in two- and three-inch
vertical lines having markedly different slurry velocities
and particle size distributions. The side tap produced results
only 2-37. lower than the isokinetic center probe. The solids
concentrations were measured by quantitative filtration and
weighing of solids from a known weight of slurry.
Calculation of solid-liquid reaction rates for
this system requires very accurate material balances. For
this reason, it was essential to sample process streams around
a given vessel in a proper and rapid sequence. The composi-
tions of the downcomer and scrubber bottoms streams can vary
considerably due to fluctuations in oxidation rate, SO 2 re-
moval rate, and additive rate. These streams were sampled
three times consecutively as they entered the hold tank over
a period of about one residence time. The hold tank effluent
itself was then sampled. This procedure results in an accurate
time average of reactant concentration entering the tank. Rate
calculations are thus not affected by short term fluctuations
in stream compositions.
The composition of the scrubber spray should not
change significantly during sampling around the marble bed.
-137-
-------
Previous experiments showed that the marble bed itself is
non-uniform, however. Two samples of the marble bed liquor
were taken; one at the back and one at the front of the
scrubber. These results were averaged for use in rate and mate-
rial balance calculations. It was assumed that the marble bed
samples were representative of streams leaving the scrubber
through the downcomers.
The scrubberbottoms sample is probably the least
representative of the actual process stream. This is due to
sampling from a large short section of pipe that is not full or
in turbulent flow. The contribution to the scrubber material
balance from this stream is fortunately small.
Analytical methods used have been described in
(Radian Final Report for EPA Contract CPA-70-143). Aqueous
SO 2 analyses and percent solids determinations were completed
on site. The remainder of the analyses was performed at
Radian after shipping the samples to Austin. The pH measurements
were made with a Beckman laboratory pH meter carefully
standardized and temperature compensated. This instrument was
located so that the slurry could be continuously directed
from the pump into a beaker containing the electrodes. The
error due to additive dissolution was kept at a minimum in
this manner.
5.4.2 Precipitation and Dissolution Rates
The precipitation rates of CaSO 3 J H 2 O, CaSO .2H 2 O,
and CaCO 3 , the dissolution rate of Ca(OH) 2 , and the oxidation
rate of SO 2 were calculated for the hold tank and the marble
bed. Sample calculations of precipitation, dissolution, and
oxidation rates are presented in Appendix E of this report.
A summary of these precipitation, dissolution, and oxidation rates
is presented here in Table 5-8.
-138-
-------
TABLE 5-8
LIMESTONE INJECTION WET SCRUBBING TESTS - RATE CALCULATION SUMMARY
(All values in gmoles/min.)
17R 18R 19R 20R 21R 22R
Solid Balance Liquid Balance Liquid Balance Solid Balance Liquid Balance Solid Balance Liquid Balance Liquid Balance Liquid Balance
Sell Se12 Sell St2 setI Set2 Sell SeeB Seti Set2 Sell Set2 Seti Set2 Set 1 Set2 Set I Se12
Marble Bed
SO Oxidation 3.8 4.2 3.5 3.3 3.4 3.4 —.4 —.7 3.4 3.4 .9 1.8 3.7 3.7 3.7 3.7 4.5 4.5
CaSOa Precipitation 1.3 .8 1.6 1.75 5.7 4.6 1.6 1.0 —3.0 2.6 L.2 .3 -.7 —1.5. 2.5 -.45 4.0 4.5
CaSO 4 Precipitation —.8 -.4 1.0 .7 1.2 .4 -.6 -1.8 —.7 .8 —1.1 2.6 .8 1.9 2.0 1.65 .3 2
CaCO 3 Precipitation .5 0 ** ** ** ** -.8 .4 ** ** -.6 .7 ** ** — -- — - 1* **
Ca(OH) 3 Dissolution 5.2 3.3 6.9 5.3 7.7 6.9 4.5 3.4 1.6 9.4 4.8 5.9 5.5 4.1 9.1 4.9 7.8 8.7
503 Removal 7.8 7.6 7.8 7.6 12.1 12.1 7.5 7.5 7 3 7.5 6.73 6.75 6.75 6.75 10.2 10.2 13.0 13 0
System Additive Rate 10.9 10.9 10.9 10.9 10.9 10.9 14.8 14.8 14.8 14.8 14.8 14.8 14.8 14.8 15.7 15.7 15 7 IS 7
Hold Tank *
SO3 Oxidation -.2 .7 ** ** ** ** -.5 -.2 ** ** -.6 .1 ** *4 ** ** 4* *4
CaSO 3 Precipitation 7.2 1.5 7.0 2.3 1.8 2.4 6.0 3.2 5.3 5.0 4.1 2.8 2.7 27 1.3 3.9 12.4 8.3
CaSO Precipitation 1.1 -.1 1.7 .7 .6 1.3 2.3 1.4 0 .6 1.2 1.6 —1.1 -1.9 —.1 3.4 8.4 2.9
CaCO, Precipitation 1.0 .5 .5 .2 .2 0 ** ** .1 .2 4 .4 4* 4* ** *4 *4
Ca(OH) 3 5.0 2.0 3.0 1.6 3.4 3.7 5.2 4.4 7.8 3.3 3.3 4.7 .6 .9 -3 8 5.0 12.4 5.5
SO 3 Removal 7 7.6 7.6 12.1 12.1 6.2 6.2 .2 6.2 8.0 8.0 8.0 8.0 10.2 10.2 130 130
System Additive Rate 7 10.9 10.9 10.9 10.9 14.8 14.8 14.8 14.8 14.8 14.8 14.8 14.8 13.7 13.7 15.7 13.7
Total Rates
SO 3 Oxidation 4.9 3.5 3.3 3.4 3.4 -.9 —.9 3.4 3.4 0.3 1.9 3.7 3.7 3.7 3.7 4.5 4.5
CaSO , Precipitation 2.3 8.6 4.1 7.5 7.0 7.6 6.2 2.5 7.6 5.3 3.1 2.0 1.2 3.8 3.5 16.4 12.8
Ca50 4 Precipitation -0.5 2.7 1.4 1.8 1.7 1.7 0.4 -0.7 1.4 0.1 4.2 -0.3 0.0 1.9 5.3 6.7 3.1
CaCO, Precipitation 0.5 0.5 0.2 -0.6 0.4 -0.5 0.9
CaOH, Diasolution 5.3 11.9 6.9 11.1 10.6 9.7 9.8 9.4 12.7 8.1 10.6 6.1 3.0 5.3 9.9 20.2 14.2
1n Run 17 Set L Hold Tank raId Vera .ea.ured under different operating conditions than the scrubber ratas.
These rate. vers assuned to be negligible.
-------
Two methods for checking the plausibility of these
rates are:
(1) the sum of Ca(OH) 2 dissolution in the hold
tank and the scrubber should not exceed the
additive rate,
(2) the sum of CaSO 3 and CaSO 4 precipitation rates
in the hold tank and the scrubber should not
exceed the SO 2 removal rate.
The most consistent rate data presented in Table 5-8
are enclosed by brackets. In general the marble bed rates were
less reasonable than the hold tank rates. This can be attributed
to the instability of the marble bed and to marble bed sampling
problems. However, for each limestone injection test, at
least one good set of rates was obtained.
One objective of the limestone injection/wet scrubbing
test series was to confirm the precipitation rate correlations
derived through laboratory research on precipitation kinetics
(Section 4.0 of this report). The observed precipitation rate
correlations can be expressed by an equation of the form:
R = kn(r-1) (54)
where R is the precipitation rate ing-moles/gram-min., k is
the precipitation rate constant (g-mole/min-active site), n is
the number of active sites for precipitation per gram of seed,
and r is the relative saturation of the precipitating species.
This is equal to the activity product of precipitating ions
divided by the solubility product.
-140-
-------
To compare the precipitation rates observed in the
Limestone injection/wet scrubbing tests with the precipitation
rates observed in Radian laboratory studies, the hold tank
precipitation rates enclosed by brackets in Table 5-8 were
adjusted to the same temperature (45°C) using the Arrhenius
rate constant equation with an activation energy of 15 kcal/g-mole.
The amount of seed crystals in the slurry was calculated from
the slurry analyses. The total amount of seed in the hoLd tank
could then be calculated using the volume of the tank. Results
of these calculations are presented in Table 5-9.
The relative saturations of the precipitating species
were caLculated using an equilibrium computer program and are
also presented in Table 5-9.
Using the data presented in Table 5-9, plots were
made of the precipitation rates in millimole/gram minute (at
45°C) versus relative saturation. These plots are shown in
Figure 5-5 for CaSO 3 precipitation in the hold tank and in Figure
5-6 for CaSO 4 precipitation in the hold tank. Precipitation
rates for the marble bed were not correlated due to rate errors
resulting from marble bed sampling problems.
Referring to Figure 5-5, the sulfite precipitation
rates calculated from hold tank balances are in general agreement
with Equation 5-4. The data are quite scattered, however. A
curve representing laboratory rate data for sulfite precipitation
at 45°C is also shown in Figure 5-5. With the exception of Run
17, the pilot data lie far below this curve. Apparently, the
crystals circulating in the pilot unit were less reactive than
those used in the laboratory study.
Figure 5-6 shows sulfate precipitation rates for the
injection scrubbing tests. These data agree quite well with
-141-
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TAIiLE 5-9
HOLD TANK PREC1PITA1 ION RATE CORRELATION
INJECTION-WET SCRUBBING TESTS
Hold Slurry Seed Normalized
Calculated Rate Tank Relative Concentration I late
( gmoies/min ) Volume Supersaturation Temp ( glitter) ( inmoles/min-gram seed )
Run Set CaSO 3 CaSO 4 ( gal) CaSO 3 CaSO 4 °C CaSO 3 CaSO 4 CaSO 3 CaSO 4
17R 1* 7.0 1.7 6000 2.8 1.13 51 1.91 0.71 0.090 0.048
2 2.3 0.7 6000 4.6 0.5 37.5 0.60 0.10 0.277
18R 1 1.8 0.6 6000 2.7 1.16 46 5.24 10.99 0.014 0.002
2 2.4 1.3 6000 6.4 1.18 46 4.26 8.3 0.024 0 007
19R I. 5.5 2.3 6000 9.9 1.28 39 2.94 1.62 0.144 0.057
2 5.0 1.4 6000 11.4 1 24 39 2.84 1.52 0 145 0 052
20R 1 4.1 1.2 6000 7.8 1.39 40 1.41 0.81 0.212 0.106
2 2.8 1.6 6000 10.4 1.51 40 1.11 0.70 0.179 0.167
21R 1 1.3 -0.1 3000 3.0 1.25 65 25.55 18.48 0.009
2 3.9 3.4 3000 3.8 1.17 45 21.43 10.50 0.014
22R 1 12.4 8.4 6000 4.0 0.96 46 28.44 19.69 0.017
2 8.3 2.9 6000 3.7 1.11 45
*These data were taken before the use of blowdown and are not comparable to other data in the table.
-------
Labora tory
Rate
0 17,1
18,10 i,i
2.0 3.0
017,2
18 ,2
022,1
4.0
5.0
6.0 7.0
Relative Saturation
0 20,1
19,1 0
0 20,2
19,20
8.0 9.0 10.0 11.0 12.0
2
2
2
2
2.
1
1
1.
a)
4- i
Cu
0 )
a)
0
,-
. - --1
a)
4- i
0
- .-1
4- i
4 I
- ‘-I
—I
( I
a.’
I -i
p - I
1.2
1.
0.8
0.6
0.4
0.2
0.0
1 .0
FIGURE 5-5 - CaSO 3 PRECIPITATION RATE IN HOLD TANKS FOR LIMESTONE INJECTION TESTS
-------
2.2
2.0
a)
1 .8
1.6
1.4
1.0
0
:;i 0.8
06
U
1.2
0.4
0.2
0
1.0
Laboratory
Ra t e
20,2
020,1
19,2
0
19,1 0
1.1 1.2 1.3 1.4 1.5 1.6
Relative Saturation
1.7
FIGURE 5-6 - Ca SO 4 PRECIPITATION RATE IN HOLD TAN1 FOR LIMESTONE INJECTION TESTS
-------
Equation 5-4. They are also in good agreement with laboratory
results.
5.4.3 Vapor-Liquid Mass Transfer Rates
In the same manner as the soluble tests, vapor-liquid
equilibrium calculations were made for the marble bed scrubber
in each limestone injection/wet scrubbing tests. Relative
mass transfer coefficients were again calculated using Test 9R
as a reference point.
The data given in Tables 5-10 and 5-11 indicate that the
mass transfer capability of the marble bed scrubber is strongly
dependent on the liquor pH in the same manner as in the soluble
sodium carbonate test series. This trend is exhibited in Figure
5-7 which plots Kga . pH for both the soluble sodium carbonate
tests and for the limestone injection tests.
The operating variables of flue gas flow rate, liquid
to gas ratio, flue gas temperature, and liquor flow rate do not
appear to have as significant an effect on relative mass transfer
as do percent solids in the scrubber spray. This effect of the
percent solids in the scrubber spray is probably due to its
effect on the scrubber operating pH through dissolution of lime
in the bed.
5 .4.4 Prediction of Scaling Conditions
Another objective of these tests was to determine the
ability to predict scaling conditions in the scrubber based upon
calculated supersaturations. Laboratory studies have related
scaling to rapid nucleation of calcium sulfite and calcium
-145-
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TABLE 5-10
MARBLE BED VAPOR-LIQUID EQUILIBRIUM
CALCULATIONS
Run
17R
18R
19R
20R
2 IR
22R
pH Range
4.5-5.5
5.8-6.2
4.5-4.9
4.5-4.7
5.4-5.7
5.4-6.1
SOa
( ppm )
10-50
0
10—35
10-20
0
0
y*CO
( a tm )
.05- .06
.07- .18
.03
.025
.025-.03
.01- .025
Experiment Liquor pH
17R 4.5—5.5
18R 5.8-6.2
19R 4.5-4.9
20R 4.5-4.7
21R 5.4-5.7
22R 5.4-6.1
y (ppm)
Inlet Outlet
1,500 750
1,500 390
1,880 1,060
1,950 1,250
2,000 810
2,020 555
2 N.T.U.
50
0
35
20
0
0
yin-y*
Relative
= out3 Kga
.7 .7
1.35 1.35
.6 .55
.45 .4
.9 .8
1.3 1.2
TABLE 5-11
RELATIVE MASS TRANSFER COEFFICIENTS
(Based on Kga for Experiment 9R of the soluble test
series set equal to 1.0)
-146-
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3.0
W
W
‘4 .1
U,
a)
I i
a)
a)
a)
...4
U
a)
‘-I
l 0
Marble Bed, pH
FIGURE 5 -7 - RELATIVE MP SS TRANSFER RATE VS. pH FOR SOLUBLE
TEST AND LIMESTONE INJECTION TESTS
0
Run 7 - High L/G
Run 14 - Low L/G
Run 8 - Low L/G
I I i I i I
3 4 5 6 7 8 9
2.0 —: Intermediate
Liquor
Dilut
Liqi
0
0
00
-147-
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sulfate at supersaturations exceeding the “metastable limit”.
Experimentally determined values for the metastable limit of
calcium sulfate are 1.3 - 1.4 and of calcium sulfite are
3.0 - 4.0. Observations of scaling during the limestone
injection/wet scrubbing tests are compared with predicted
scaling behavior in Table 5-12.
In general the results are excellent. Taking into
consideration the possible errors in measurements and calcula-
tions, the sulfate metastable limit of 1.3 - 1.4 appears to be
an adequate criterion for predicting scaling. The sulfite limit
of 3 - 4, on the other hand, may be somewhat conservative. No
sulfite scale was observed in Test 2LR where the marble bed
sulfite supersaturation ranged as high as 6.8 and in Test 22R
where 5.0 was reached.
5.4.5 Conclusions
From the results obtained in the limestone injection!
wet scrubbing tests the following conclusions were drawn.
(1) The slurry sampling and analytical techniques
applied in these tests adequately revealed
the chemical processes occurring in limestone
injection/wet scrubbing systems. Difficulty was
encountered in characterizing the marble bed
due to its non-uniform composition, however.
(2) Operating variables such as additive rate, flue
gas flow rate, Liquid to gas ratio, and liquor
fLow rate appear to affect the overall vapor-
liquid mass transfer rate only through their
-148-
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TABLE 5-12
PREDICTION OF SCALING USING CALCULATED RELATIVE SUPERSATURATIONS
Sulfite Sulfate
Run Supersaturation Supersaturation Predicted Scaling Observed Scaling
17R 2.1-5.2 .85-1.08 Possible sulfite. Minor scaling. Compo-
No sulfate. sition not reported.
L8R 4.8-11.4 1.16-1.28 Definite sulfite. Scale observed:
Possible sulfate. 55-65% sulfite
25-45% sulfate
19R 31-7.4 1.8-2.6 Possible sulfite. Scale observed, sul-
Definite sulfate. fate (preliminary
analysis).
20R 1.7-2.9 2.0-2.2 No sulfite. Scale observed, sul-
fate (preliminary
analysis).
211 3.9-6.8 1.2-1.6 Possible sulfite. No scale observed.
Possible suLfate.
22R 3.4-5.0 1.2-1.4 Possible sulfite. No scale observed.
Possible sulfate.
-------
effect on the operating pH of the marble bed. This
correlation between vapor-liquid mass transfer and
pH indicates that a liquid phase resistance is a
significant portion of the overall vapor-liquid
mass transfer rate.
(3) The precipitation rates observed in the limestone
injection/wet scrubbing tests could be described
by the same general form as the rate correlation
observed in Radian laboratory research.
R = kn(r-l) (5_4)
Therefore, circulation of large amounts of
solids in the slurry increases th precipitation
of and decreases the supersaturation of CaSO 3
and CaSO 4 in the scrubbing system. The magnitude
of sulfite precipitation rates was considerably
lower in the piLot unit than in the Laboratory
study, however. Sulfate precipitation rates were
comparable.
(4) Over half of the system additive dissoLution occurs
in the scrubber in spite of Low liquid residence
times. The additive dissolution rate is apparently
a strong function of liquor pH.
(5) Safe supersaturation limits for scale-free
operation agree with those established in the
laboratory for calcium sulfate (1.3-1.4) , but
appear to be higher for calcium sulfite. The
limestone injection/wet scrubbing system operated
in a scale-free condition with calcium sulfite
supersaturation levels up to 6-8.
-150-
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5.5 Limestone Tail-End Addition Tests
This portion of the final report outlines the results
and conclusions obtained by Radian Corporation from the Phase III
limestone tail-end addition/wet scrubbing tests. The objectives
of these tests were presented in Section 5.3.1 of this report.
The flow scheme and operating conditions of these tests were
presented in Figures S-3a and 5-3b, and in Table 5-3 of this
report.
5.5.1 Analytical Results
The results from Radian laboratory analysis of the
liquid and solid phases of the slurry samples taken in the
limestone tail-end addition/wet scrubbing tests are presented in
Appendix D of this report. Electroneutrality imbalances were
determined for each of the liquid phase chemical analyses. For the
slurry sample analysis from the limestone tail-end addition tests
the electroneutrality imbalances were below 47 except for Test 3A
where four of the slurry sample analyses had electroneutrality
imbalances of 57 - 77g. Errors up to 5% are to be expected in
the chemical analysis of slurries of this nature.
Total sulfur material balances were performed around
the marble bed scrubber and the hold tank as a check on the
accuracy of both the sampling techniques and the analytical
techniques employed. The results of these material balance
calculations are presented in Table 5-13.
-151-
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TABLE 5-13
TOTAL SULFUR MATERIAL BALANCE SUMMARY CE LIMESTONE TESTS
(All values in gmoles/min total S)
Marble Beds Hold Tank
Deviation from Mean Deviation from Mean
Run Set In Out ( 7 ) In Out ( 7 )
IA 1 193 212 9.4 185 191 3.1
2 202 233 14.3 192 187 2.6
2A I
2 292 275 5.6 312 299 4.3
3A 1 375 386 2.9
lB 1 359 429 17.7 363 354 2.5
2 406 420 3.4 381 376 1.3
2B 1 809 953 16.3 720 968 20.4
2 919 1,124 20.1 827 865 4.5
3B I
2
-------
Excluding Test 2B the average deviation in the sulfur
material balances was lO% for the marble bed and 4°h for the
hold tank. The 29°h materiaL balance deviation for the hold
tank in Test 2B was probably due to an error in the weight
percent solids determination. The marble bed sulfur material
balances consistently have greater deviations due to problems
in obtaining slurry samples representative of the marble bed.
It should be noted here that for slurries with high
solids content, the total sulfur material balance is not a good
indication of the accuracy of the liquid phase analyses since
most of the sulfur is in the solid phase.
5.5.2 Precipitation and Dissolution Rates
As in the injection/scrubbing test series, the
precipitation rates of CaSO 3 were calculated for the hold tank
and for the marble bed. These rate calculations were performed
using the ch mical analyses of the slurry samples taken during
the limestone tail-end addition tests sample calculations of
these rates are given in Appendix E of this report. The
results of these calculations are summarized in Table 5-14.
No attempt was made to perform separate material
balances or rate calcuLations around the lower and upper marble
beds during the double bed runs. Possible transfer of liquor
between beds and lack of an intermediate gas sampling point
precluded this calculation.
Of the rates presented in Table 5-14, the marble bed
rates contained the largest errors. These errors were due to
-153-
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TABLE 3 i4
RATE CALCULATION SUMMARY FOR LIMES1DNE TAIL-END ADDITION TESTS
Liquid Balances (mmoles/min)
Run 1A Run 2A Run 3A Run lB Run 28 Run 38
Set 1 Set 2 Set 1 Set 2 Set 1 Set 2 Set 1 Set 2 - Set I Set 2 Set 1 Set 2
M.irb [ e Beds
SO, Oxidation 2,540 2,540 3,400 3,400 2,930 4,250 4,350 5,940 5,870 5,750 5,990
CaSO 3 Precipitation -3,160 —270 —2,990 —3,150 210 520 90 2,710 3,010 —3,600 -5,330
CaSO 4 Precipitation 2,690 260 2,510 1,900 4,870 1,030 1,440 -790 —380 40 890
CaCO 3 Dissolution 4,360 5,690 7,460 5,530 6,010 8,130 9,690 12,360 12,020 9,420 8,900
Hold Tank
SO 2 Oxidation * * * * * * * * * * * *
CaSO 3 Precipitation 3,980 -1,890 7,390 8,910 10,250 9,000 8,330 7,860 8,140 9,890 12,080 14,590
CaSO, Precipitation 920 4,580 560 580 -2,710 —570 1,270 1,520 4,000 2,430 3,510 3,870
CaCO 3 Dissolution 2,350 3,360 3,765 4,773 3,810 4,780 5,310 4,720 5,690 5,940 6,580 9,060
u Surge Tanks
SO Oxidation * * * * * * * * * * * *
2
p- CaSO 3 Precipitation 7,386 4,364 6,104 5,357 500 4,410 4,740 3,460 1,800 4,380 4,990
CoS0 Precipitation -1,620 863 976 1,430 2,840 2,160 1,778 2,910 3,970 2,630 550
CaCO 3 Dissolution 3,744 2,028 1,836 3,042 620 2,270 2,800 2,080 2,220 2,248 2,230
SO 2 Removal Rate 10,600 10,600 11,600 11,600 12,200 12,200 17,000 17,400 21,200 20,980 19,160 19,950
System Additive Rate 34,440 34,440 35,336 35,336 21,440 21,440 36,940 36,940 36,940 36,940 22,910 22,910
Total S Precipitation 10,200 7,910 14,550 15,030 15,960 --- 17,700 17,400 20,400 20,700 19,000 19,600
Total CaCO 3 Dissolution 10,450 11,080 13,060 13,350 10,440 15,700 17,200 20,100 20,200 18,200 20,200
Total S Removed from
Flue Gas 10,600 10,600 11,600 11,600 12,200 --- 17,000 17,400 21,200 21,000 19,200 20,000
Total SO Oxidation 2,540 2,540 3,400 3,400 2,930 4,250 4,350 5,940 5,870 5,750 5,990
Total Ca50 4 Precipitation 1,990 5,703 4,050 3,910 5,000 4.460 4,740 6.120 6,020 6,180 5,310
-------
sampling probe and sampling line problems which limited
ability to collect representative slurry samples.
The CaSO 4 2H 2 O precipitation rate in the hold tank
for Test 3A is negative indicating dissolution of CaSO 4 2H 2 O.
This is also substantiated by sub-saturation levels of CaSO 4
in the hold tank. Since Test 3A was the first test in the
series, this condition may indicate that steady state operation
had not been reached.
Because the rate calculations around the hold tank
and the marble bed did not appear to account for all of the
precipitation and dissolution occurring in the system, rate
calculations were performed around the surge tanks. The
results of the surge tank rate calculations are included in
the rate calculation summary presented in Table 5-14. Agreement
of the precipitation, dissolution, and SO 2 removal rates
presented in Table 5-14 is good and indicates good overall
accuracy for the results.
The precipitation rates observed in the limestone
tail-end addition tests were compared with those observed in
previous tests. Rates were again normalized to the common
temperature of 45°C using the Arrhenius rate constant equation
with an activation energy of 15 kcal/g-mole.
The normalized precipitation rates, the seed crystal
density, and the relative supersaturations for both CaSO 3 and
CaSO 4 are presented in Thble 5-15. From the data presented
in Table 5-15, plots were made of precipitation rates versus
relative saturation for the data collected in the limestone tail-
end addition tests. These plots are shown in Figure 5-8 for
CaSO 3 precipitation in the hold tank and in Figure 5-9 for
-155-
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TABLE 5-IS
HOLD TANK PRECIPITATION RATE CORRELATION
TAIL-END ADDITION TESTS
Slurry Seed
Calculated Rate Relative Concentration Normalized Rate
( gmoles/min ) Volume Supersaturation Tern ( a/liter) ( rrmioles/min-gram sea4l
Run Set CaSO , , CaSO ( gal) CaS0 CaSO °C CaS O 1 Ca50 4 Ca !Q , Ca&L
IA 1 3.98 0.92 6 ,000 3.5 1.09 48.0 2.14 1.30 0.041 0.023
2 -1.89 4.58 6 ,000 2.0 0.87 47.4 2.68 1.18 -0.024 0.132
2A 1 7.39 0.56 6,000 4.1 1.09 48.0 - - - -
2 8.91 0.58 6,000 4.8 1.12 47.0 2.77 1.15 0.114 0.018
3A 1 10.25 -2.71 6,000 8.4 0.80 49.0 3.50 1.55 0.086 -0.041
1 2 9.00 -0.57 6,000 11.9 0.64 48.0 3.27 1.33 0.084 -0.013
lB 1 8.33 1.27 6,000 5.9 1.07 50.3 2.57 [ .10 0.083 0.030
2 7.86 1.52 6,000 1.6 1.12 50.8 2.68 1.25 0.072 0.030
2B 1 8.14 4.00 6,000 4.9 1.05 51.2 4.68 2.42 0.041 0.039
2 9.89 2.43 6,000 4.2 1.05 50.4 4.13 2.18 0.061 0.029
38 1 12.08 3.51 6,000 4.3 1.03 50.0
2 14.59 3.87 6,000 4.2 1.03 50.0
-------
Relative Saturation
FIGURE 5-8 - Ca SO 3 PRECIPITATION RATE IN HOLD TANK FOR LIMESTONE
TAIL-END TESTS
Laboratory Rate
.26
.24
.22
• .20
.l8
.16
0
i-i .12
FE
.O4
.02
0
1
02A, 2
e1B, 1
o 2E, 2
0
1A, 1
2B, 1
o 3A, 1 3A, 0 2
•1
-------
.22
.20
.18
C
.16
C u
1 - i
.14
U )
a)
.02
Relative Saturation
FIGURE 5-9 - CaSOk PRECIPITATION RATE IN HOLD TANK
FOR LIMESTONE TAIL-END TESTS
Labora tory
Ra t e
2B,1
,2G1tè13 1
1.5
-158-
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CaSO 4 precipitation in the hold tank. Due to the unrealiability
of the marble bed rate data, these precipitation kinetics
comparisons were not made.
Figures 5-8 and 5-9 indicate that the precipitation
rate data obtained from the limestone tail-end addition tests
do not correlate well using the precipitation rate expression
given by Equation 5-4. This scattering of data may be due to
errors in the precipitation rates, or to the fact that the
number of active sites for precipitation is only proportional
to the mass of seed crystals when the crystal size distribution
is constant for all tests.
Limestone dissolution rates measured in these pilot
studies have been re-calculated on a per gram of limestone basis
for comparison with laboratory results. Information pertinent
to these calculations is summarized in Table 5-16. Figure
5-10 compares the laboratory and pilot scale results on a
consistent basis. Considering the possibility of variations
in particle size between the pilot scale and the laboratory
tests, the agreement is excellent.
5.5.3 Vapor-Liquid Mass Transfer Rates
From the chemical analysis of the downcomer stream,
vapor-liquid equilibrium calculations were again made for the
marble bed scrubber in each limestone tail-end addition/wet
scrubbing test. For the double bed runs the equilibrium SO 2
partial pressures for each bed were averaged due to the
unavailability of data on the flue gas composition between
the marble beds. The “relative Kga” for the marble bed in each
Limestone tail-end addition test was calculated from the
equilibrium SO 2 data presented in Table 5-17. These Kga vaLues
are presented in Table 5-L7 and are again relative to Test 9R.
-159-
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1. BLE 5-16
HOLD TANK LIMESTONE DISSOLUTION RATE CORRELATION
Limestone Limestone Hold
DissoLution Solids Tank a + Limestone
Rate Concentration Density Volume - 1 Dissolution Rate
Run Set ( mo lesImin l ( wt 7. ) _.jgj ...4L ( liters) ( 10 P mo e/ 1 ) ( mmole/gram mm )
LA 1 2.4 3.2 1,080 22,700 8.9 .0031
2 3.4 3.4 1,080 22,700 7.6 .0042
2A 1 3.8 - . ** 22,700 10.0 **
2 4.8 2.3 1,070 22.700 8.5 .0086
3A l 3.8 2.5 1,080 22.700 8.9 .0062
2 4 8 2.1 1,080 22,700 9.6 .0093
L 1 5.3 2.3 1,070 22,700 4.9 +
2 4.7 2.5 1,070 22,700 35.5 .0077
2B 1 5.7 2.9 1,110 22,700 9.1 .0078
2 5.9 2.6 1,100 22,700 9.3 .0091
3B 1 6.6 ** *t 22,700 12.3 **
2 9.1 ** 22,700 15.9 **
7. solid samples were lost for these runs.
+TIis value ignored because SCOT
-------
TABLE 3-17
RELATIVE MASS TRANSFER COEFFICIENTS
(Based on K 1 a for Experiment 911 of the soluble test series set equal to 1.0)
Outlet Cas Total Scrubber (ppm) *
Flow Rate Liquid Rate Liquor 150 5 Relative
Experiment ( gmoles/mip) ( gpm) p H Inlet Outlet ( ppm )
LA 10,800 150 5.3-5.6 2,310 1,110 4.4 0.73 0.68
2A 10,600 240 5.0-5.2 2,505 1,010 7.8 0.91 0.83
3A 10,480 243 5.3 2,345 980 9.9 0.87 0.79
18 10,700 310 5.6-6.0 2,410 545 1.1 1.49 1.37
28 10,900 470 5.4-5.8 2,435 290 1.5 2.13 2.00
38 10,800 485 5.0-5.6 2,375 365 5.2 1.87 1.74
frd
-------
.05 —
.04 0 - Lab Result
- Pilot Unit Result
I .03
0
4J
.02
v - I
N .) 0
. 0
0
U
F 0 ’
0 11 tiil I
.3 .4 .5 .6 .7 .8 .9 1.0 2 3 4 5
Hydrogen Ion Activity x 106
FIGURE 5-10 - COMPARISON OF LAB AND PILOT UNIT LINESTONE
DISSOLUTION RATES
-------
In agreement with previous tests, there appears to be
a proportional relationship between the relative mass transfer
coefficient and the scrubber pH for the Limestone tail-end
addition experiments. This trend is exhibited in Figure 5-11
and indicates that the SO 2 removal is partially limited by a
liquid-film diffusion rate.
Figure 5-11 also indicates that the limestone
stoichiometry influences the overall mass transfer coefficient
by its influence on the pH. The only difference in operating
conditions between Tests 2A and 3A, and between Tests 2B and
3B is the limestone stoichiometry. In both cases the tests
with the limestone stoichiometry of 967 had a lower Kga than
the tests with the limestone stoichiometry of l457 . The lime-
stone stoichiometry, by its infLuence on the Limes tone dissolution
rate,. may have an influence on the liquid film resistances and
the Liquid film diffusion rates.
5.5.4 Prediction of Scaling Conditions
Laboratory studies have shown that scaling is related
to rapid nucleation of calcium sulfite and sulfate at super-
saturations exceeding the so-called “metastable limit’. Predicted
scaling behavior for the tail-end addition tests based on the
metastable limits of 3.0 - 4.0 for CaSO 3 .½H 2 0 and of 1.3 - 1.4
for CaSO 4 2H 2 O is presented in Table 5-18. Regardless of the
several high supersaturations, there was no scaling observed
during any of the limestone tail-end addition tests. No
explanation is available for this phenomenon.
-163-
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3.0
c i i
.-I
c i
‘4- I
(4 (
c i )
0
0
a)
4 -I
C’,
c c i
C’,
C)
J-.
c c i
a,
0
2.0
Downcomer Liquor, pH
FIGURE 5-11 - RELATIVE MASS TRANSFER COEFFICIENT VS. pH
Strong
Liquo:
A - Single Bed Runs
• - Double Bed Runs
Run 2B
oc
0
7 - ugh L/G
00
Run 2AA
Run 3AA
Is
14 - Low L/G
in 8 - Low L/ C
6
7
8
9
-164-
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TABLE 5-18
PREDICTION OF SCALING USING CALCULATED R ..ATIVE SUPERSATURATIONS
Temperature
Run Vessel _pjj.. ( °C) CaSO 3 H O CaSO 4 2H ,O Predicted Scaling
IA Marble Bed 1 5.28 47.4 10.6 1.22 Definite Sulfite, Possible Sulfate
2 5.59 47.2 14.0 1.41
2A Marble Bed 1 4.97 48.0 5.9 1.45 Possible Sulfite, Possible Sulfate
2 5.19 46.0 8.6 1.57
3A Marble Bed 1 5.29 49.0 9.6 0.87 Definite Sulfite, No Sulfate
lB Upper Marble Bed 1 5.76 46.6 11.6 1.43 Definite Sulfite, Possible Sulfate
2 5.95 47.5 14.2 1.45
Lower Marble Bed 1 5.64 47.1 13.6 1.40 Definite Sulfite, Possible Sulfate
2 5.90 47.5 17.9 1.28
2B Upper Marble Bed 1 5.81 45.5 6.0 1.40 Possible Sulfite, Possible Sulfate
2 5.68 46.0 5.5 1.39
Lower Marble Bed 1 5.38 47.3 6.6 1.42 Possible Sulfite, Possible Sulfate
2 5.52 44.4 7.9 1.38
3B Upper Marble Bed 1 5.60 47.0 5.8 1.38 Possible Sulfite, Possible Sulfate
2 5.49 47.0 5.9 1.35
Lower Marble Bed 1 5.30 46.2 8.2 1.40 Possible Sulfite, Possible Sulfate
2 5.05 48.9 5.2 1.33
-------
5.5.5 Conclusions
The data and calculations obtained for the six
limestone tail-end addition/wet scrubbing tests support the
following conclusions.
(1) The analytical and hoLd tank sampLing methods
employed were adequate for investigating
important vapor-liquid and solid-liquid reac-
tion rates in the process vessels. Poor
results caused by marble bed sampLing probe
problems indicate the importance of very short
sampling times.
(2) The amount of CaSO 4 •2H 2 0 precipitation in the
scrubber is always a substantial fraction of
the total CaSO 4 2H 2 O precipitation for the
system ( 5O7 ) in spite of the low Liquid resi-
dence time in the marble bed. This is presumably
due to high supersaturations and high nucleation
rates in the marble beds. CaSO 3 .i H 2 O precipita-
tion in the marble bed is low, but significant
( lO7 ).
(3) Over 5O7 of the CaCO 3 dissolution in the wet
scrubbing system occurs in the scrubber in spite
of its relatively small liquid hold up. This is
due to the high driving force for dissolution
occurring in the marble beds. This is consistent
with laboratory results showing a strong rela-
tionship between limestone dissolution rate and
pH. Limestone dissolution rates in the hold
tank agree well with laboratory results.
-166-
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(4) Significant amounts of precipitation and
dissolution occurred in the surge tanks.
This reaction should be taken into account
in pilot plant studies and process design.
(5) Vapor-Liquid mass transfer rates were similar
to those experienced in the lime and Na 2 CO 3
test series. Their correlation with marble
bed pH was again significant. It was
also evident that there is a direct relation-
ship between the vapor-Liquid mass transfer
rates and the number of marble beds. These
facts indicate that SO 2 removal is limited
by liquid phase mass transfer resistance
and by interfacial area, not by the equilibrium
partial pressure of s 2
(6) Increasing the total scrubber liquid-to-gas
ratio decreases the suLfite supersaturation
significantly but does not appear to affect
the sulfate supersaturation.
5.6 Application of CE/Windsor Test Experience to EPA’s
Shawnee Program
One goal of the SO 2 scrubbing tests at Windsor was to
gain experience in the characterization of processes that may
be helpful during EPA’s on-going prototype program at Shawnee.
Several aspects of the sampling and data interpretation proce-
dures used at Windsor can be related directly to the Shawnee
tests. Others, particularly those dependent on relative flow
rates, vessel configurations, and modes of operation, may require
-167-
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some modification. The single major difficulty in relating the
two programs is probably the difference in test goals and pro-
posed data interpretation procedures.
5.6.1 Sampling Procedures
The sampling procedures employed in any test must
satisfy two main criteria.
The slurry sampLe drawn from a vesseL or
process stream must be representative of
the actual stream composition.
The sampling time from when the slurry
leaves the process stream to when solid-
liquid separation and liquid species
fixation are achieved must be smalL with
respect to the residence time of the
vessel being sampled.
Experimental results at Windsor have indicated that
although sampling should be done from verticaL lines to eliminate
slurry stratifying effects it need not be isokinetic sampling.
Non-isokinetic sampling of a 5°h slurry stream induced only a
27 - 37€ , error. This error will vary with the percent solids
and should be investigated at Shawnee before non-isokinetic
sampling is employed.
Due to poor flue gas distribution the slurry
composition was found to vary 2O% across the bed. This sampling
problem was solved by taking slurry samples from the bed front
and the bed back and averaging the analysis.
-168-
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To eliminate sampling errors due to reactions in
the sampling lines, the sampling Lines should be kept short
and should be of smaLl diameter. Care should be taken to
purge the sampling lines well before samples are obtained.
Accurate pH and temperature measurements are required
and should be obtained by pumping slurry directly through a
small container or fLow cell in which the pH electrode and thermo-
meter are suspended. Since accurate temperature compensation
is important, the pH meter should be calibrated frequently with
a buffer at the same temperature as the stream to be sampled.
5.6.2 Steady State Criteria
The factors involved in determining the length of
time a system must be run in a given operating mode before
meaningful data can be obtained vary with the process vessel
from which samples are being taken. The following steady state
criteria can be established for material balance and rate
calculations about the hold tank.
A minimum period of three to four hold
tank residence times must elapse before
sampling (based on the total flow through
the tank).
For high solids runs where the bleed-off to
the clarifier is small with respect to the
total tank throughput, liquid species balances
are valid after this minimum time period.
-169-
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• For runs where the amount of sulfur in the
liquid and solid phases is approximately equal
and for solids species balances in high solids
runs, at least two characteristic times based
on the tank (+ scrubber) volume and clarifier
bleed-off rate must elapse before sampling.
To account for short-term composition fluctuations in
streams entering the hold tank at Windsor, these inlet streams
were sampled three times in succession over a period of approxi-
mateLy one tank residence time. This allowed an average inlet
composition to be calculated.
Steady state criteria for the scrubber are not as
stringent since the liquid hold-up is at least an order of
magnitude smaller than that of the hold tank. There should not
be any significant short term fluctuation in the scrubber feed
composition, but the scrubber effluent and bed should be sampled
several times in succession for accurate material balances and
rate calculations. For vapor-liquid equilibrium calculations
in the scrubber where the liquor is sampled to calculate SO 2
partial pressures, no steady state criteria need be applied
if the gas is continuously analyzed with a small Lag time.
Although the entire wet scrubbing system (including
clarifiers or ponds) has a very long response time, this presents
no problems to material baLances and rate calculations about
process vessels if the system is regarded as being at quasi-
steady state” over the time period required for sampling. How-
ever the ultimate Long-term performance of the system with
respect to SO 2 removal and operability is a function of the
eventual soluble species concentrations reached when the system
reaches steady state.
-170-
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5.6.3 Material Balance Data Interpretation
Total sulfur material balances were used as a check
on data consistency for the Windsor wet scrubbing test series.
The results of these balances are indicative of the process
and analytical measurement errors that can be anticipated at
Shawnee assuming similar sampling techniques are used.
The average deviation of the inlet and outlet sulfur
rates for the scrubber is 77 while the majority of the
deviations are within lO7 . The average deviation of the inlet
and outlet sulfur rates for the hold tank is 47 and the majority
of the deviations are within 57g. It should be noted that the
most important criterion for material balance accuracy is related
to the rate calculations to be made. The absolute difference
between inlet and outlet total sulfur rates should be much
smaller than the amount of SO 2 removed in the scrubber if
reliable precipitation rates are to be calculated.
5.6.4 Precipitation and Dissolution Rate Calculations
From observation of the rate calculations presented in
Appendix E of this report, it is evident that the rates of
precipitation and dissolution cannot be rigorously determined
by liquid species balances alone. A combination of solid and
liquid balances must be used. However, in practice it was
found that rigorous calculation of precipitation and dissolution
rates via solid species balances is not feasible for slurries
having a solids content of greater than 27g. Even small amplitude
errors in solids analyses would mask changes due to precipita-
tion because of the high circulation rate of solids in the system.
-171-
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The need for employing solid phase material balances
in the rate calculations of high solids slurries (over 2%)
can be eliminated by making two assumptions. For the lime-
stone injection tests these assumptions are:
all oxidation of aqueous SO 2 occurs in the
scrubber(none in the hoLd tank),
precipitation and dissoLution rates of
CaCO 3 are negligible compared to other
rates of interest.
For Limestone tail-end addition tests only the first assumption
applies. These assumptions have been verified from experiments
with low soLids concentrations. It should be emphasized that
these assumptions must be checked for the particular system
and equipment being tested.
One objective of the Windsor test series was to
relate precipitation and dissolution rates to the amounts of
seed circulated in the slurry and the resulting levels of
supersaturation observed. As discussed in Sections 5.4 and
5.5 of this report, for the limestone injection and the lime-
stone tail-end addition systems the precipitation and dissoLu-
tion rates were roughly proportional to the amounts of seed
circulated in the slurry. Maintaining Low levels of super-
saturation by circulation of large amounts of seed is one
approach to scale prevention.
5.6.5 SO 2 Removal in the Marble Bed Scrubber
One of the most consistent correlations developed
from the Windsor test series was that relating the overalL gas
-172-
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phase vapor-liquid mass transfer coefficient for the marble
bed to the bed liquor pH. This relationship was shown in Figures
5-4, 5-7, and 5-10. Although this correlation cannot be applied
directly to units other than the marble bed, similar behavior
may be anticipated.
5.6.6 Prediction of Scaling Conditions
Laboratory studies have shown that scaling is related
to rapid nucleation of calcium sulfite and sulfate at super-
saturations exceeding the so-called t1 metastable limit”. Experi-
mentalLy determined values of relative supersaturations at which
nucleation becomes significant are 1.3 - 1.4 for CaS0 4 2H 2 O
and 3.0 - 4.0 for CaS0 3 H 2 0. In general, observations of scaling
during the wet scrubbing tests correlated well with experimentally
determined values for the metastable limits. The sulfite Limit
of 3.0 - 4.0, however, did appear conservative and additional
pilot data wiLl be needed to firm up these numbers.
. . .173_
-------
.6.0 ANALYTICAL SUPPORT FOR SHAWNEE
Under EPA Contract CPA 70-143, Radian designed a
laboratory data analysis system for EPA’s demonstration of
the lime/limestone wet scrubbing system at TVA’s Shawnee
Plant. Modifications and system improvements were conducted
under this contract.
The Shawnee Laboratory Analysis System was designed
to perform data storage, laboratory computations, and report
generation tasks associated with the laboratory operations.
The system is basically a card oriented system using marked-
sense card input to ease the problem of converting data toa
machine readable format. In addition, the system is designed
to provide automatic operation of an X-ray fluorescence spectro-
meter with automatic calibration and matrix corrections per-
formed upon the results. The X-ray analysis results are
entered automatically without operator intervention.
For each set of analyses defined by a time, sampling
point, sample type (i.e., line out, steady-state, or exception),
and run number, a data packet is created on disk to store
all raw data and computed results associated with that set of
analyses. After all data for that particular set of analyses
has been entered into the data processing system and all
calculations performed, the completed data packet is trans-
ferred by the operator from the disk to magnetic tape and by
means of the line printer a hard copy is prepared. The data
analysis system may be commanded to prepare sample taking
schedules and sample analysis schedules.
Analytical support for Shawnee Plant included
several trips to Paducah to aid in solving hardware problems and
-174-
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to incorporate requested changes in the Laboratory Analysis
System. The major changes to the Laboratory Analysis System
were the allowance of several more default values on the card
inputs to speed up the input of data to the system and the
addition of several new commands implementing new analyses and
allowing the input of data via CRT or teletype. In addition,
Radian assisted Bechtel personnel in data tape transfer and
interpretation. System capabilities were expanded to permit:
(1) dust and wet SO 2 analysis calculations, and
(2) ion imbalance calculations for the solid
species.
The work done and changes made to the system are detailed in
the form of trip reports in the Appendix C (see Section 10).
-175-
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7.0 SOLUBILITY PRODUCT OF CaSO 4 .½i 2 O
Precipitation of calcium sulfate salts is an important
aspect of lime/limestone wet scrubbing processes. Knowledge of
the solubility characteristics of the various hydrated forms is
necessary for an accurate description of such processes. Data
for the less soluble hydration states, CaSO 4 (anhydrite) and
CaSO 4 2H 2 O (gypsum), were originally included in the Radian
equilibrium model. The more soluble hemihydrate (CaSO 4 .½H 2 0)
was omitted at that time since it was not the equilibrium
species in the temperature range of interest. Kinetics studies
have shown, however, that the rate of hemihydrate precipitation
is great compared to the rates for anhydrite and gypsum. Thus,
in highly concentrated sections of the scrubber system, the solu-
tions could become greatly supersaturated with respect to anhydrite
and dihydrate and the solubility limit of the hemihydrate might
be reached. Conversion to a more stable hydration state would
later take place in the clarifier.
A survey was conducted to collect solubility data for
calcium sulfate hemihydrate reported in the literature. These
data were evaluated on the basis of experimental method and
starting material employed. After selection of the best values,
solubility product constants were calcuLated with the aid of the
Radian equilibrium program and correlated in the general form
shown in Equation 7-1.
-RLnK, = k 1 + k 2 LnT + k 3 T + k 4 T 1 + k ,T + k T ’
(7—I)
Where R is the gas constant; KT is the thermodynamic solubility
product constant at infinite dilution; k 1 , k: , k , k.; , k , and
ke are correlation coefficients; and T is the absolute temperature.
-176-
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An investigation was made to determine the optimum number of
constants so as to result in a correlation form having the
least number of terms but an error still in accordance with
the accuracy of the experimental data. A similar procedure was
performed using all available solubility data.
7.1 Data CoLlection and Evaluation
Experimental solubility values for calcium sulfate
hemihydrate were collected from the literature. Several solu-
bility compilations incLuding Cmelin (GM-00l) and Linke (LI-005,
LI-020) were used to obtain the data from 1950 and earlier. To
Locate more recent experimental evidence Chemical Abstracts was
searched from 1950 through June 1971, and Chemical Titles from
January to June 1971. Work relating to this subject funded by
the Department of Interior’s Office of Saline Water was reviewed
by means of the OSW Conversion Report for the years 1969-1970
and 1971.
The selection of soLubility data for CaSO 4 • H 2 0 to
be included in the Radian equilibrium program was based on the
medium in which the solubility was measured, whether the meta-
stability of the hemihydrate was taken into account in the
experimental method employed, the nature of the starting material,
and the care taken in the handling of the substance. The data
in the temperature range 25-90°C reported by Zdanovskii and co-
workers (ZD-001, ZD-002, ZD-003), Sborgi (SB-OOL), Riddell
(RI-0 19), and Power et al. (P0-004, P0-022) were chosen. A
second correlation was also made employing all solubility
measurements reported in the literature for a-CaSO 4 ½H 2 0 determined
in pure water. It should be noted that two forms of CaSO , ,.½H 2 0,
the and forms, are possible. The c form is the most
probable form encountered in Lime/limestone wet scrubbing
processes.
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7.2 Data Correlation
Solubility data for CaS0 4 H 2 0 were correlated as a
function of temperature (°K) in the form of Equation 7-1. A
least squares technique was employed in the correlation. This
technique minimizes the difference between LnK calculated and
observed. The choice of LnK results in minimization of the
percentage error of the correlation. The derivation of the
correlation form is described in detail in Radian Technical
Note 200-014-04 (see Appendix A of this report).
Solubility data for CaSO 4 H 2 0 collected from the
literature were converted, if necessary, to weight percent
CaSO 4 in solution. The moles of calcium, sulfate, and H 2 0 per
100 grams solution were then calcuLated for each data point and
input to the Radian equilibrium program. It was then possible
to determine the activities of Ca , S0 , and H 2 0 which appear
in the expression for the solubility product constant for
CaSO 4 ½H 2 0 as shown in Equation 7-2.
KT = (aCa )(aSO=)(aHO)½ (7-2)
This procedure was used to calculate observed solubility product
constants, Kobs, for 18 carefuLly selected data points in the
temperature range 25-90°C. A second run using all available
data involved 59 data points in the temperature range 0-200°C.
An investigation was made to determine the optimum
number of constants so as to result in a correlation having the
least number of terms but an error still in accordance with the
experimental data. More constants than this is a correlation
of experimental error. This was accomplished by dropping k 8 ,
and k 2 in succession from the correLation. This corresponds
-178-
-------
to elimination of the heat capacity coefficients A, B, C, and D,
respectively, from Equation 7-3.
C (T) = A ÷ BT + CT 2 - D/T (7-3)
k 1 and k 4 are related to the standard entropy and enthalpy for
the reaction of interest, the dissolution of calcium sulfate
hemihydrate.
The relationships between the heat capacity coefficients,
the standard state entropy and enthalpy, and the correlation
coefficients are fully described in Radian Technical Note 200-014-04.
Basically, integration of Equation 7-3, substitution of temperature
Limits, substitution of AH 298 and AS 298 for thermodynamically
equivalent terms, and collection of like terms result in an
equation having the same general form as Equation 7-1. The forms
of the coefficients k 1 are shown below.
= -L S 298 + 298.16 + 1) + L B(298.L6) (7-4a)
+ ( )(298.l6) 2 C + (½) (298.16)2
k 2 = M (7-4b)
I c 3 = (½)t D (7-4c)
k 4 = AHR 298 - 298.16 M - ( 298.16)2 L B (7-4d)
( 298.16) C ( 1 L D
- A - 298 .16
-179-
-------
= (- )i B (7-4e)
= (-‘/a)1 C (7-4f)
The results of this investigation using the selected
data from 25-90°C are given in Table 7-1. The root mean square
(RNS) error for the correlation is also given for each case.
This number was also used to compare the accuracy of the correla-
tion with the experimental error. A second correlation was also
made for 59 data points which included solubility data for
CaSO 4 •½H 2 0 in the range 0-200°C.
7.3 Results
The k’s calculated in Case 3 have been seLected as
the set of coefficients to be used in the calcuLation of soLu-
bility product constants in the Radian equiLibrium program.
This choice was made on the basis of constancy of the RNS error
and enthalpy and entropy terms in Cases 1, 2, and 3 as the
coefficients none, C, and C and D, respectively, were eLiminated
from the correlation. The correlation error of —57 is reason-
abLe with respect to the solubility data seLected from the
literature. Table 7-2 gives the tabulated resuLts of Case 3,
including the raw solubility data in weight percent CaSO 4 in
soLution at each temperature, observed and calculated solubility
product constants, the error fraction (KObs - Kca1c)/Kbs and
the literature reference for each data point.
In summary, the solubility product constant for
a - CaS0 1 .½H,0 may be expressed the relationshin:
_RthKT = -81.826056 + 12.707705 QnT + 3429.0616 T’+ 0.054204619 T
(7-5)
-180-
-------
TABLE 7-1
RESULTS OF INVESTIGATION TO DETERMINE
OPTIMUM NUMBER OF CONSTANTS FOR CORRELATION
Case
1
2
3
Heat Capacity
Coefficients
Included
A, B, C, D,
A, B, D
A,B
AU 0
298
RMS Error
0.05024
0.05028
0.05030
0.05090
0.7742
4 A
5 None
-5. 169x10 3
-5.094x10 3
-5. 178x10 3
-5.355x10 3
-2. 530x10 5
AS
298
-35.58
-35.33
-35.60
—36.17
-19.74
M.
+ 1.457
AB
AC
AD
-6.754x10
-3.163x10 4
-4.O17x10 5
+ 1.312
-1.089x10’
+L.70OxlO
-12.71
-1.084x10 1
-39.95
0
0
0
0
0
0
0
0
0
0
-------
TABLE 7-2
RESULTS OF CORRELATION OF 25-90°C DATA
RMS Error For This Case — .5030-01
— -81 .826056
• 1.2.107705
— 3429.061.6
— .542046L9-01
1.1
Degrees
Centigrade
Degrees
Kelvin
CaSO 4 -1/2 H 0
Solubility
Gram/tOO C Soin
Solubtlity Product Constant
(g-molesfkg H,O) 2
Observed Calculated
Error
rracuon
Reference
1
25.0
298.2
.6940
.10072867-03
.10320439-03
-.246-01
ZD-003
2
25.0
298.2
.7100
.10340530-03
.10320439-03
.194-02
SB-O01
3
25.0
298.2
.6620
.95)96033-04
.10320439-03
-.819-01
ZD-OOL
4
25.0
298.2
.7850
.11603980-03
.10320439-03
.111
ZD-002
5
31.0
304.2
.5980
.81248368-04
.86470887-04
- .643-01
R1-019
6
35.0
308.2
.6030
.79536831-04
.16768214-04
.348-01
SB-0Ql
7
40.0
313.2
.5500
.68685806-04
.66081333-04
.379—01
SO-Wit
8
45.0
318.2
.4552
.52893859-04
.56815099-04
- .741-01
P0-004
9
50.0
323.2
.4560
.50668615-04
.48794536-04
.370-01
ZD-003
50.0
323.2
.4270
.46963430-04
.48794536-04
- .390-01
R1-019
50.0
323.2
.4700
.52465375-04
.48794536-04
.700-01
SB-00l
12
50.0
323.2
.4360
.48110833-04
.48794536-04
- .142-01
ZD- OOL
[ 3
65.0
338.2
.3280
.29847979-04
.30728143-04
- .295-01
P0-004
14
75.0
348.2
.2900
.23210667-04
.22479702-04
.315-01
ZD-003
15
75.0
348.2
.2710
.21451469-04
.22479702-04
- .479-01
RI-019
16
75.0
348.2
.2900
.23210667-04
.22479702-04
.315-01
SB-0O1
17
75.0
384.2
.2860
.22839388-04
.22419102-04
.1.57—01
ZD-00l
18
84.0
357.2
.2380
.1661761.2-04
.16925249-04
- .185—01
P0-004
-------
8.0 NOMENCLATURE AND UNITS CONVERSION
8. 1 Nomenclature
a interfacial area
a chemical activity of i species
A temperature independent constant in
Arrhenius relationship
A 0 initial value of surface area
A,B,C,D heat capacity coefficients
C concentration
L C change in concentration
initial concentration
C heat capacity
E* activation energy
F flow rate
G gas flow rate
AHR 298 standard state enthalpy
k rate constant
k coefficients in solubility product correlation
K 0 overall gas phase mass transfer coefficient
solubility product constant
Kr themodynaniic solubility product constant
M mass of seeds
M 0 initial mass of seeds
n number of seed crystals; also n+ +
n÷,n number of cations and anions
NTU number of transfer units
P pressure
r relative saturation
-183-
-------
R reaction rate; also gas constant
L S difference in amounts of sulfur
standard state entropy
t time
T absolute temperature
V volume
y mole fraction of SO in the gas phase
y* mole fraction of SO 2 in the gas phase in
equilibrium with liquid phase
crystalline form of CaSO 1 . H 2 O
undetermined coefficients
. activity coefficient
some function of actual and equilibrium con-
centrations or activities of the reacting species
-184-
-------
8.2
Units Conversion
Engineering quantities presented in this report
are expressed in English units, i.e., inches, feet, gallons,
SCFH, °F, psia, etc. Conversion factors for determining
the metric equivalent of each of these quantities are listed
below:
IACFM =
ifoot =
lft 2 =
lft 3 =
1 gallon =
linch =
1 lb-mole =
ipsia =
1SCFH =
28. 316 liters/minute
0.30480 meters
0.092903 square meters
28.316 liters
3.7853 liters
2. 5400 centimeters
453.59 g-moles
5.1715 cm Hg
28.316
standard liters/minutes
-185-
-------
9.0 BIBLIOGRAPHY
DR-004 Drehmel, Dennis C., “Limestone Types for Flue Gas
Scrubbing”, presented at 2nd International Lime!
Limestone Symposium, Nov. 8-12, 1971, New Orleans.
EP-002 Epstein, M. et al., “Test Program for the EPA Alkali
Scrubbing Test Facility at the Shawnee Power Plant”,
presented at the 2nd International Lime/Limestone
Wet Scrubbing Symp., New Orleans, Nov. 8-12, L971.
GM-O01 Gmelin, Gmelin’s Handbuch der Anorg. Chemie , 8.
Auflage, Calcium, Teil B Lieferung 3, (1961).
LI-005 Linke, William F., Solubilities--Inorganic and Metal
Organic Compounds , Vol. I, 4th ed., Princeton, New
Jersey, D. Van Nostrand, 1958.
LI-0 12 Liu, Sung-Tsuen, “Kinetics of Crystal Growth of
Calcium Sulfate Dihydrate”, (Univ. of N. Y.) J. Cryst.
Growth 6(3), 281-9 (1970).
LI-020 Linke, William F., Solubilities--Inorganic and Metal
Organic Compounds , Vol. II, 4th ed., Washington, D.C.,
American Chemical Society, 1965.
L0-027 Lowell, P. S. et al. , A Studjr of the Limestone In-
jection Wet Scrubbing Process , Final Report, Vol. I,
APCO Contract 70-45, Austin, Radian Corporation (1971).
NA-033 Nancollas, George H. and N. Purdie, “The Kinetics
of Crystal Growth”, Chem. Soc. Quarterly Rev . 18,
1-20 (1964)
-186-
-------
P0-004 Power, Wilson H., Bela N. Fabuss, and CharLes N.
Satterfield, “Transient Solubilities in the Calcium
Sulfate-Water System”, J. Chem. Eng. Data 9, 437-42
(1964).
P0-022 Power, W. H. et al., Thermodynamic Properties of
Saline Water , RD-104, Everett, Mass., Monsanto
Research Corp., July 1964; PB 181 685.
RI-019 Riddell, W. C., as cited by K. K. KeLley 3
J. C. Southard, and C. T. Anderson in “Thermodynamic
Properties of Gypsum and Its Dehydration Products”,
U. S. Bureau of Mines Tech. Paper 625 , 1941, p. 56.
SB-OOl Sborgi, U. and C. Bianchi, “Solubilita’ Conducibi1it
e R 5ntgenana1isi del Solfato di Calcio Anidro e
Semiidrato”, Gazz. Chim. Ital . 70, 823-35 (1940).
ZD-001 Zdanovskii, A. B. and F. P. Spiridonov, “Solubility
of the and R Modifications of CaSO 4 0.5H,0 and
CaS0 4 2H 2 0”, Russ . .1. Inorg. Chem . 11(1), 11-13 (1966).
ZD-002 Zdanovskii, A. B. and C. A. Vlasov, “Solubility of the
Various Modifications of Calcium Sulfate in H 2 S0 4
Solutions at 25 Degrees C”, Russ . J. Inorganic Chem .
13(10), 1415—17 (1968)
ZD-003 Zdanovskii, A. B. and F. P. Spiridonov, “Polytherm
for the Solubilities of Various Forms of CaSO 4 . cJj O
in Water Between 0 and 100 Degrees”, J. Appi. Chem.
U.S.S.R . 40(5), 1109-11 (1967).
-187-
-------
10.0 APPENDICES
-188-
-------
10.1 APPENDIX A
RADIAN TECHNICAL NOTE 200-014-04
CALCIUM SULFATE HEMIHYDRATE SOLUBILITY
-189-
-------
TECHNICAL NOTE 200-014-04
CALCIUM SULFATE HEMIHYDRATE SOLUBILITY
12 November 1971
Prepared by:
Nancy P. Phillips
Philip S. Lowell
-190-
-------
1.0 INTRODUCTION
Precipitation of calcium sulfate salts is an important
aspect of lime/limestone wet scrubbing processes. Knowledge of
the solubility characteristics of the various hydrated forms is
necessary or an accurate description of such processes. Data
for the less soluble hydration states, CaSO 4 (anhydrite) and
CaSO 4 2H 2 0 (gypsum), were originally included in the Radian
equilibrium model. The more soluble hemihydrate (CaSO 4 . ½H 2 0)
was omitted at that time since it was not the equilibrium species
in the temperature range of interest. Kinetics studies have
shown, however, that the rate of hemihydrate precipitation is
great compared to the rates for anhydrite and gypsum. Thus, in
highly concentrated sections of the scrubber system, the solu-
tions could become greatly supersaturated with respect to zero
and dihydrate, and the solubility limit of the hemihydrate might
be reached. Conversion to a more stable hydration state would
later take place in the clarifier.
A survey was conducted to collect solubility data for
calcium sulfate hemihydrate reported in the literature. These
data were evaluated on the basis of experimental method and
starting material employed. After selection of the best values,
solubility product constants were calculated with the aid of
the Radian equilibrium program and correlated in the general
form shown in Equation 1-1.
-RLnK = k 1 + kLnT + k 3 T 2 + k 4 T + k 5 T + k 6 T 2 (11)
An investigation was made to determine the optimum number of
constants so as to result in a correlation form having the
least number of terms but an error still in accordance with
-19 1-
-------
the experimental data. A similar procedure was carried out
using all available solubility data.
The following sections of this technical note describe
the collection, evaluation, and correlation of data which have
been carried out.
2.0 DATA COLLECTION
Experimental solubility values for calcium sulfate
hemihydrate were collected from the literature. Several
solubility compilations including Gmelin (GM-OO1) and Linke
(LI-O05,.LI-020) were used to obtain the data from 1950 and
earlier. To locate more recent experimental evidence Chemical
Abstracts was searched from 1950 through June, 1971, and Chem-
ical Titles from January to June 1971. Work relating to this
subject funded by the Office of Saline Water was reviewed by
means of the OSW Conversion Report for the years 1969-1970 and
1971. Copies of approximately 20 articles and 40 abstracts
were added to the Radian literature system.
3.0 DATA EVALUATION
3.1 Controversy Concerning Number of Crystalline
Phases
The exact number of distinct crystalline forms of
CaSO 4 • H 2 O was found to be in dispute in the literature;
opinions varied from zero to two. Ridge and Beretka (RI-003)
and Rabinowitz. et al. , (RA-028) have summarized much of the
evidence presented thus far.
-192-
-------
Early investigators regarded the hemihydrate as a
zeolitic hydrate of y-CaSO 4 and not as a distinct crystalline
species. Some crystallographic data were cited which supported
this viewpoint. Improved experimental techniques later proved
that the hemihydrate and y-CaSO 4 did have distinguishable
powder patterns.
The different properties of the two postulated forms
of hemihydrate are due chiefly to their methods of preparation.
The s-form is prepared by a wet method, usually autoclaving
the dihydrate for five to six hours at a pressure of 20 lb/in 2 .
Other techniques are also practiced. This type of procedure
results in well-formed crysta].s of low porosity. The dry method
of preparation involves dry-calcining gypsum in an oven at 150°C.
The hemihydrate produced, commonly referred to as -CaSO 4 ½H 2 0,
is characterized by relatively small crystallite size, large
surface area, and a high degree of porosity. Ridge points out
that the smaller crystal size could be responsible for the greater
solubility of this form, as reported by Zdanovskii and co-worker
(ZD-OO1, ZD-002, ZD_003)*. Table 3-1 gives a comparison of the
solubilities of these two forms as reported by these workers.
If this were the case, then solubility differences could not be
used as evidence for the existence of two crystalline species.
Other characteristics often used as criteria for distinctiveness
such as X-ray and electron diffraction, infrared absorption, and
proton magnetic resonance absorption, have failed to show con-
clusively that two structural forms exist.
In this investigation, solubility data were collected
for both postulated forms when available. However, since the
* In one publication by Zdanovskii (ZD-0O1), the labeling of the
graphs and tables showing and -CaS0 4 ’ H 2 O solubility has
apparently been reversed.
-193-
-------
TABLE 3-i
SOLUBILITIES OF - AND B—CaSO 4 . ½H O
IN WATER AT VARIOUS TEMPERATURES
Solubility in Weight Percent CaSO
T°C x-CaSO H O -CaSO 4 ’ H O
‘0 0.986 1.060
25 0.694 0.762
50 0.456 0.494
75 0.290 0.306
100 0.200 0.208
Reference: ZD-003
dry-calcined form ( ) is more soluble and upon contact with
water hydrates more rapidly than the a-form, it was necessary
to make a choice of which data to use in our correlation.
The s-form was selected on the basis that it would be the
form most probably encountered in a wet scrubbing process.
Also, the data reported for this form was in close agreement
with values given for unclassified hemihydrate.
3.2 Experimental Method
Several different methods have been applied to the
determination of calcium sulfate hemihydrate sol.ubility as
reported in the literature. The metastability of this com-
pound in the CaSO -H 2 O system causes some doubt as to the
accuracy of measuremen’ts obtained from standard procedures for
solubility determinations. A description of the various methods
which have been applied is given below.
-194-
-------
1. Kinetic Method
The kinetic method of solubility determination was
used by Zdanovskii and co-workers (ZD-00l, ZD-002, ZD-003) to
measure the solubilities of powdered materials. Several sam-
ples of equal weights were dissolved in succession in the same
volume of water or solution containing from 0.1 to 0.5°!. CaSO 4 .
Uniform conditions of stirring and temperature were maintained.
A specified amount of time was allowed for dissolution, followed
by immediate withdrawal, filtration, and analysis of solution
specimens, which yielded the increase in concentration of CaSO
in solution.
Increase in CaSO 4 concentration was plotted versus
initial CaSO 4 concentration in the solution for a given tempera-
ture. Intersection of the isochrone with the abscissa (the
point at which the increase in concentration of dissolved CaSO 4
is zero) axis yielded the solubility of the hemihydrate at that
temperature. A second and, in some cases, a third isochrone
acted as a check on the result obtained from the first.
Different variants were used in the studies described,
and are summarized in Table 3-2.
2. Conductometric Method
As a salt dissolves, the electrical conductivity
of the solution increases in proportion to the amount of ions
present. This is the principle of the method used by Sborgi
and Bianchi (SB-OOl) and Smith (as reported by Player, PL-007).
At each temperature the conductance of the solution is measured
as a function of time. The point of maximum conductance is taken
as the solubility at that temperature. The composition of the
solution at that point is determined by chemical analysis of a
filtered sample.
-195-
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TABLE 3-2
EXPERIMENTAL CONDITIONS OF SOLUBILITY STUDIES CONDUCTED BY KINETIC METHOD
Initial
Amount Concentration Dissolutic
Temperature Sample Weight of of Solvent Time
Reference Salt Medium Range ( in grams) Solvent, with CaSO 4 ( minutes )
ZD-001 a- and s-heniihy- water 0 l00vC 1-2 200 ml 0.1 - 0.57. 5, 10, 15
drates
ZD-002 a- and -hemihy- 0-407. R SO 4 25 4 100 ml 0.2 - 0.67. 3, 5
drates; dehydrated
a- and -hemihy-
drates; soluble
a- and -anhydrite;
insoluble anhy-
drite
ZD-003 a- and -hernihy- water 0-100°C 4 100 g 0.1 - 0.57. 3, 5
drates; dehydrated
a- and B-hemihy-
drates; soluble
a- and a-anhydrite;
insoluble anhy-
drite
-------
3. Isothermal Method
The standard isothermal method for determining
solubilities has been applied to calcium sulfate hemihydrate
by some investigators (P0-004). The temperatureof a specified
volume of distilled water or, in some cases, a filtered satu-
rated CaSO 4 solution is held constant throughout the run. A
weighed saniple of hemihydrate is added to the stirred solvent.
Samples of solid and liquid phases are taken regularly for analy-
sis. The hydrate water content of the solid phase is analyzed by
gravimetry (loss-on-ignition method). The calcium sulfate content
of the solution is determined by an EDTA titration of Ca . Power
and co-workers (P0-004) simultaneously carried out conductometric
measurements during the run to locate solubility maxima, which
were taken as the solubility of the substance.
3.3 Nature of the Starting Material
Another criterion in the selection of our data was
the nature of the starting material. This was important for
several reasons. As described in Section 3.1, the method of
preparation of the hemihydrate has a great effect on the
physical properties of the product. Therefore if the investi-
gator failed to describe how the starting material was prepared,
his results became questionable. Also the handling of the
starting material could influence the reliability of the data.
In some earlier investigations data incorrectly assigned to
“soluble anhydrite” prepared by complete dehydration of gypsum
were in error because of the rapid rehydration to hemihydrate
on exposure to the atmosphere.
The selection of solubility data for CaSO 4 ’ ½H 2 0 to
be included in the Radian equilibrium program was thus based on
-197-
-------
whether the metastability of the hemihydrate was taken into
ccOuflt in the experimental method employed, the nature of the
starting material, and the care taken in the handling of the
substance. The data in the temperature range 25-90°C reported
by Zdanovskii and co-workers (ZD-0Ol, ZD-002, ZD-003), Sborgi
(SB-001), Riddell (RI-019), and Power, et al., (P0-004, P0-022)
were chosen. The results of the selected 25-90°C data correla-
tion, which is described in the following section, give an
approximate error of 570 compared to an ll°h error when all avail-
able data in the range 0-200°C for hemihydrate prepared by a
wet method were used.
4.0 DATA CORRELATION
Solubility data for CaSO 4 ½H 2 0 were correlated as
a function of temperature (°K) in the form of Equation 4-1
using a least squares technique.
-RLnKT = k 1 + k 2 LnT + k 3 T + k 4 T 1 + k 5 T + k 8 T 2 (41)
The observed solubility product constants, Kobs, were calculated
from reported solubility data using the Radian equilibrium
program. The least squares technique minimized the difference
between LnK calculated and observed. The choice of LnK results
in minimization of the percentage error of the correlation.
An investigation was made to determine the optimum number of
constants so as to result in a correlation having the least
number of terms but an error still in accordance with the experi-
mental data, Section’4.3 describes this aspect of the study,
and Sections 4.1 and 4.2 give a description of the calculation
of Kobs and the derivation of the general correlation form
respectively.
-198-
-------
4.1 Calculation of Observed Solubility Product Constant
Solubility data for CaSO 4 ½H 2 0 collected from the
literature were converted, if necessary, to weight percent
CaSO 4 in solution. The moles of CaO, SO 3 , and H 2 0 per 100 grams
solution were then calculated for each data point and input to
the Radian equilibrium program. It was then possible to determine
the activities of Ca , SOT, and H O which appear in the expres-
sion for the solubility product constant for CaSO 4 ½H 2 0 as shown
in Equation 4-2.
= (aCa )(aSO=)(aHO) (4-2)
This procedure was used to calculate observed solubility product
constants, Kobs, for 18 carefully selected data points in the
range 25-90°C. A second run using all available data involved
59 data points.
4.2 Derivation of Correlation Form
This section describes how the equilibrium constant
for a reaction can be calculated. The reaction of interest is
the dissolution of calcium sulfate heinthydrate as shown in
Equation 4-3.
CaSO 4 H 2 0( 5 ) ± Ca + S0 + ½H20(L) (4-3)
This general reaction can be described by Equation 4-4, with
i reactants and products where and are the stoichio-
metric coefficients.
-199-
-------
Reactants Products (4-4)
i
Note that when i is a reactant, = 0 and when i is a product,
= 0. At equilibrium and at temperature T, Equation 4-5 holds.
= - T S (4-5a)
= -RTLnK (4-5b)
— l(1 H
LnKT — \ T - S 11 (4-5c)
Thus, the equilibrium constant for a reaction at temperature T
may be calculated by evaluating the right hand side of Equation
4-Sc. The enthalpy term is evaluated from Equation 4-6 and
likewise, the entropy term from Equation 4-7.
T T
= + $ Cp(T) dT] - + $ Cp(T) dT]}
298 298 298 298
T
= + ,f Cp(T) dT] (4-6)
1 2g8 298
T T Cp(T).
Cp(T) .
= + 1 dT] - [ s 98 + J 1 dT]}
T
i ‘ 298 298 T
T Cp(T).
= V ( - a. . S 298 + $ T 1 dT] (4-7)
L \ ij ij,
298
-200-
-------
The form of Cp(T) for both products and reactants is given in
Equation 4-8.
Cp(T) = A + BT + CT 2 - D/T 2 (4-8)
Integrating the heat capacity terms, substituting the temperature
limits, substituting and AS in Equation 4-5c, and collect-
ing like ternis result in an equation of the following form:
-RLnK 1 = k,+ k LnT + k 3 T + k f 1 + k 5 T + k 8 T 2 (4-9)
The form of the constants k 1 through k 6 is given below.
k 1 = (-1) a. )s 98 .- - AA(Ln 298.16 + 1)
+ B(298.l6) + (½)(298.16) 2 AC + 298.16)2 (4-lOa)
k 2 = - A (4-lob)
k 3 = ( )t, D (4-lOc)
k 4 = [ ( J - 1.]) f] - 298.16 _(298.l6) 2 B
- ( 298.16) - ( 29 116 ) D (4-lOd)
k 5 = (- )t B (4-lOe)
k 6 = (-V 6 )AC (4-lOf)
-201-
-------
where:
= (a..- a. i)Aj (4-ha)
= ( - )13 (4-lib)
Ac = (an- (4-lie)
AD = ( - (4-lid)
4.3 Determination of Optimum Number of Constants to
be Used in Correlation
An investigation was carried out to determine the
optimum number of constants so as to result in a correlation
having the fewest constants but an error still in accordance
with the experimental data. This was accomplished by dropping
k 6 , k 3 , k 5 , and k in succession from the correlation. As
shown in Equations 4-lOa through 4-lOf this corresponds to
elimination of C, D, B, and A respectively from the heat capa-
city equation. Substituting the values calculated for the
remaining k’s in Equations 4-lOa - 4-iOf yielded L A, AB, AC, AD,
and the enthalpy and entropy changes for the reaction of interest
(Equation 4-3) at 298° K. The enthalpy change for this reaction
is the standard heat of solution for calcium sulfate hemihydrate,
i.e., from solid to infinite dilution. This number should be
constant and was used as a criterion for the accuracy of the
correlation. If too many constants had been dropped from the
correlation then the value of AH for that case would be
S29B
-202-
-------
noticeably different from values resulting from cases
which included a greater number of constants. The entropy
change for the reaction as it appears in Fquation 4-ba, the
expression for k 1 , was similarly used.
The results of this investigation using the selected
data from 25-90°C are given in Table 4-1. The root mean square
(RNS)error for the correlation is also given for each case.
This number was also used to compare the accuracy of the corre-
lation with the experimental error.
A second correlation was made which included
solubility data for calcium sulfate hemihydrate in the range
0-200°C. Only data measured clearly using the -hemihydrate
(dry-calcined gypsum) were excluded; this screening was done
because of the noticeably greater solubility of this form
compared to the hemihydrate prepared by a wet method. As
mentioned in Section 3.]. this property is not necessarily
evidence of its existence as a distinct crystalline species
but rather may be due to its smaller crystallite size and
greater porosity. If the identity of the starting material
was not clear, but the results seemed consistent with other
reported values for the a-form, the data were included. As
shown in Table 4-2, omission of correlation constants produced
results corresponding to the previously described study, but
with much larger RIIS errors ( -a 117.) and greater deviations in
the other calculated values.
-203-
-------
TABLE 4-1
Heat Capacity
Coefficients t SD
Case Included RNS Error L 98 ______ A __________ __________ __________
1 A, B, C, D 0.05024 -5.169x10 3 -35.58 + 1.457 -6.754x10 2 -3.163x10’ -4.017x10 5
2 A, B, D 0.05028 -5.094x10 3 -35.33 + 1.312 -1.O89x1O - 0 +1.7OOx10
3 A, B 0.05030 -5.178x10 3 -35.60 -12.71 -1.084x10’ -o o
4 A 0.05090 -5.355x10 3 -36.17 -39.95 0 0 0
5 None 0.7742 -2.530x10 3 -19.74 0 0 0 0
TABLE 4-2
Heat Capacity
Coefficients
Case Included RNS Error __________ eB _______ t B ___________ ___________
1 A, B, C, D 0.1108 -4.278x10 3 -32.65 -11.50 +8.831x10 2 -6.499x10’ +3.068x10B
2 A, B, D 0.1103 -4.301x10 3 -32.74 +13.79 -2.800x10 1 0 +2.849x10 5
3 A, B 0.1104 -4.325x10 3 -32.83 +14.29 -2.875x10’ 0 0
4 A 0.1158 -4.238x10 3 -32.43 -85.66 0 0 0
5 None 14.80 -5.308x10 4 -22.95 0 0 0 0
-------
5.0 RESULTS
The k’s calculated in Case 3 in the first series of
correlations have been selected as the set of coefficients to
be used in the calculation of solubility product.. constants in
the Radian e ui1ibrium program. This choice was made on the
basis of consistency of the RNS error and enthalpy and entropy
terms in Cases 1, 2, and 3 as the coefficients none, C, and
C and D, respectively, were eliminated from the correlation.
The correlation error of 57 is reasonable with respect to
the solubility data selected from the literature. Table 5-1
gives the tabulated results of Case 3, including the raw solu-
bility data in weight percent CaSO 4 in solution at each temperature,
observed and calculated solubility product constants, the error
fraction (Robs- Ka1)/kobs and the literature reference for
each data point.
Table 5-2 is the tabulation of results from the
correlation using the data in the 0-200°C range. Again, Case
3 is shown in which the A and B coefficients in the heat capa-
city equation were used.
-205-
-------
1 25.0
2 25.0
3 25.0
14 2’.
5 3i.(
6 35.0
7 40.C
8 45.0
9 ‘0.0
10 50.C
11 50.0
12 50.0
13 65.0
114 75.0
15 75.0
16 75.0
17 75.0
18 R •fl
298.2
2 8 • 2
2q8.
eq ‘ • 2
304 • 2
30L3.2
3i3.
315.2
325.2
325.
325.2
325.2
338.2
345.2
3” 5.2
548.2
548.
357.2
• 6940
.7100
.6620
.7 Ii 0
• 598Q
.6050
.5500
.4552
• ‘4560
.4210
• 14700
.4360
.3280
.2900
.2710
.2900
.2860
.2380
. ER IC U
.10” 12t 7—U5
.95 3)I U 5 - U 4
.11 h ) —05
.8124 56 P — 0.4
.79536 35 —04
• 1.86 P ., U f — U ‘i
• b 2 d 93 c S ) -
.50668615-04
. 4 696345 0—04
.S2’)6 5 1 —U4
.4’J l lu8 Si—U’+
.298’;7’J79—tJ4
.23210667—04
.21451469 — 0 ’ ,
.23210667—04
.228393 8-U ’+
.16617612—U 4
CALCULATED
• 10.520 ’4 9—05
.10420459—05
.10320459—05
. 1fl5204 9—Oi
.8647U 3R7—04
. 7676b214—04
.6608135 3—04
•b68 15099—0’4
.4879’4 55 (.—D4
.4879 14536 0 I;
.48794536—04
.q879453 —0 ’4
• 30 72b 14 3—04
.22479702—04
.22479702—04
.22479702—04
•2247 .I70?—0’e
.1 (.9252(49—04
q o r
FRAC rio;i
—.246—01
.194—02
— .819—Ui
.111
— .644—01
. 54 8—01
.379—Ui
—.74 1—01
.370—Ui
_. So)0_01
.7c0—01
— .1’42—01
—.795—0 1
.315—01
—.479—01
.515—Ui
.157—Ui
—.185—01
Pt FEKL’.CL
z C — CtIS
p-C01
.r _(Jlfl
I 1-0l9
—001
pcj— U Oq
z - ii us
I• I-U 19
7 1 )-J01
I • C — U U’e
l u-U I ’ S
I C 1-1)19
S - U Ji
0—001
P0-0 4
RMS ERROR FCR
k
k 4
CASE = .5030-Ui
-8l.8260 6
12. 707705
31429 • 0518
S 4 204619—01
TE PER TUP t
r E(pEES
cr TI!,P oF KtLJ1N
CASOI4-j/2 H2fl
S(jLLfl3ILI TY
GRAW/100 6 SDLr
TABLE 5-1
DLLJ3ILtTY PRODUCT CONSTANT
( ‘0LCS/KG H20)*e2
T’IIS
-------
a .
2 3.0
3 5.0
‘e i1.C
5 ir.0
6 21.
7 23.5
8 25.0
9 25.C
tO p5 .0
1.1 25.r
12 3j.C
i3 35 .fl
1 40.(’,
15 45.0
16 cO.0
17 0.O
lB SCeO
1? cC.C
20 6 S.
273.2
2Th • 2
27tS.c
.2
29112
• 7
2c6. 7
293.2
20 t • 2
304.2
306.2
333.2
338.2
423•
323.2
373.2
525.2
3 .
CASt, ’ .-1/2 1120
SOLURILI T Y
CRAM/lou C, SOLN
•9F360
.U2 tJ
1 - 10
.7490
• 02 U U
.6620
.b55C)
.6940
• 7100
•66 0
• 71’ 0
.5960
.6050
. S SUO
• 45 2
• ‘.560
.4270
.‘47U 0
.4360
.3280
• 1735U1 ’ —05
•1333•j 222—U 3
• 1’ . ’ bf2—U5
.119c 9+5fl_0i
.1 7’l3bA—U3
.97662481—04
.9 ’ ; b 6 b 765—04
.lnu 12867—03
• i 5”O550—0i
.95596U53—U4
.11603980—C3
.b12 ’ItS56R U ’3
.7’) 36851—0’e
.r, r. M 5606—U 4
.52 1 958 9—U4
.5’ 6 86l5—C4
.46565450—04
• 2q b 3 5 014
.43110853—04
.29 4 r979—0 4
16912467—03
• 16014683—03
• 15 ’419988—03
.13671171—03
.11733672—03
.10818923—03
• in 314459—03
99452379-04
.99452379—04
.99452379—04
.99452379—04
• 8550 180 8-0
• 76952948—04
.67126500-04
. 8247074—U4
• 50 287 395- 04
.50287395-04
.50287395—04
50287395-04
• 31’456427—04
ERR OH
FRACTION
.252-01
—.149
•199
—.140
,R20—01
—.108
—.873—01
.127—01
•582-0i
— ‘425—Ui
.143
—.524—01
.325—UI
•227—0 I,
—.101
.752—02
—.708—01
.415—01
—.452—01
—.539—01
RfF(t(Cf1CE
20-U 03
14 I—U 19
p—U L ii
t’ I —019
SA-UDi
1 1—019
2 1:—U 03
SBU 1
LO-CC2
KI—0 19
Ij—o01
.O—on1
P0—U 04
D- fl5
p 1—019
S 13-UU1
10 001
F 0—U O L e
T PEP4Tt”C
rE tEs
cr’,TI r r ‘< .LvTN
TABLE 5-2
S0L’. ILItY PRODUCT CONSTANT
(1. L LLS/KG 1 120)**2
CALCULATED
0
-------
1’.)
0
C..)
TABLE 5-2
(cont.)
21
.0
348.
.2900
.23210667—04
. 25l1437—U4
.501—01
20—005
2
75.fl
3 8.2
.2710
.2l451L46 _(P4
.22511tI37 0
—.494—01
ftL-019
23
75.
i’ .2
.2900
.23210 67—04
•225L1’ i7—
.3fl1—01
j-&O1
2 4
75.0
3di9
.2660
.25955R—U’
.225t1 437_P1
.144—01
2f —U01
5
3 7.2
.2300
.166176 12_114
•j6432 74 04
.112—01
I•, —004
3.0
3 6.2
.i9 0
.11b5+9b7 ’4
.1185u 1 .—C
—.L —01
P 1—0 19
27
q .C
36 3.2
.19 2
.1172355fl—O’e
,11003046—t’4
.615—0].
P0—022
29
1fl0.’
373.
.2000
.111fl4169—0’4
.91185IJ J.i—0
.179
L—U(I3
79
i 0,0
373.
.1764
•95937 i6U
.91185093—U ’,
,496..Uj
p’ -U
30
lOn.Y
373.2
.1645
•Pq3944U1—u
.9118 5 693—05
—.315—01
pA _U214
1
75.2
. 1 9C
.1fl397931—04
.911’. 09 . —05
.123
S —U0i
32
1 0.0
373.2
.1980
• 1 QJ7 5 48 —04
.911B5095—05
.169
2G— Jfl1
33
100.5
373 7
.j600
•8 00535fl—U5
. ‘ ‘4&9310—05
—.52c—o l
Pfl— J 6
34
i05.
379.2
•i 99
.742l857 -05
.7 315 th9—D5
—.148—01
Pn—U’ ) 4
35
106.c
379.2
.1’480
.72147189—05
.724 9491—D5
—.433—02
r .—012
36
110.0
38 .2
.1510
.6997 473—05
.L200b517—05
.114
5 —U01
37
110.0
3P3.2
.1290
.5q15o781—us
.L20fl6 17—05
—.663—01
PA—024
38
114.0
3Pf . .
.12 0
,53Uq8455—L
.9 G? 7—05
•174— 02
Sv U12
39
i 5.E’
3’1 .2
.1120
.4595 11 4 —U5
, 0t’92674—05
—.105
F4A—U62
40
126.0
395.2
.10 50
,3 59 ’-t)5
. 1645Afl4 05
—.731—01
PA—024
41
127.0
395.2
.1010
.36 62U7 — . . :i
.5’ 04’69—05
—.416—01
IA—U62
-------
RI4S EHROI FOR
k 2
THIS CASE = .1104
C e . 7 9 14 14 p
= —14.2 P249
= e194.2512
.14315275
0
TABLE 5-2
(cont.)
142
125.
395.2
.u955
.3 C4 ’e59—O5
.35980.i52—05
—.282—01
?A—U72
‘ .3
131.r
4”5.2
.0590
.2’ 3 2 7 j ’I—OS
.27640152—05
.220—01
S?’—012
‘ .4
130.0
4 ’3.2
.0830
.260?t JA -O5
.2761413152 05
—.625—01
PA—024
45
134.0
‘107.2
.u703
,2013d315—L’S
.23597262—05
—.162
FO—022
6
1 6.r
409.2
.0773
•2i6f’:2 205
.23.5Q9R 6—0b
,1750i
I ’ 0022
47
1”t.
4 5.2
.0779
.20789U5 —05
.18156806—05
.127
TX—Oil
‘.5
jq .0
‘.15.2
.0665
.17250Uf —U5
.18 56806—U5
— . 3S—O1
PI —U2 ’ I
149
J’.2.0
‘+ 5.2
.1 )650
.1627612 1—OS
. 6671146i—05
—.243—01
PP —062
0
146.(1
l421.
•O ’ 451
.90736181-06
.1287’4642—35
—.419
10—022
‘1
1cO.(
425.2
.0550
.3.125U93 —05
.2.1B0272 —05
—.455—01
1A—U2’+
i o.fl
‘435.2
.u4 ls
.72D’ ?1q’I—u6
.75990602—06
—.546—01
—U24
53
165.C
435.2
.0560
.9’4556511—Ub
.60766446—06
.557
TI—Oil
511
170.0
‘i 5.2
.0325
.41iR6l—0c
.48485957—06
—.583—01
. I ’A— 024
55
130.0
4 3.2
.0225
.25009817—06
.30674267—06
—.226
PA—U2 ’ 1
56
160.0
4 5.Z
.02(0
.51151j9140—06
.5067 ’e2bI—O6
.155—01
1 1—011
57
1a6.C
459.2
.0760
.2F,953283 —06
.23215628—06
.138
CA —062
58
190.fl
1465.2
.0205
,i8 5 ’+3’i?-Vb
.1925U427—U6
—.156—Ui
FA-U ?4
59
200.fl
1473.2
.0165
. 7 53 2 ouq -o6
.11959593—06
.78—01
PA—024
-------
REF ERENC ES
GM-OO1 Gmelin, Cmelin’s Handbuch der Anorg. Chemie ,
8. Auflage, Calcium, Teil B Lieferung 3, (1961).
HA-062 Hall, R. E., J. A. Rbbb, and C. E. Coleman,
“The Solubility of Calcium Sulfate at Boiler-
Water Temperatures”, J. Am. Chem . Soc.., 48
927-38, (1926).
KE-039 Kelley, K. K., J. C. Southard, and C. T. Anderson,
“Thermodynamic Properties of Gypsum and its Dehydra-
tion Products”, U.S. Bur. Mines Tech. Paper 625 (1941).
LI-005 Linke, William F., Solubilities--Inorganic and Metal
Organic Compounds , Vol. 1, 4th. ed., Princeton, New
Jersey, D. Van Nostrand, 1958.
MA-072 Marshall, William L., Ruth Slusher, and Ernest V. Jones,
“Aqueous Systems at High Temperature. XIV. Solubility
and Thermodynamic Relationships for CaSO 4 in NaC1-H 2 0
Solutions from 400 to 200°C, 0 to 4 Molal NaC1”,
J. Cheni. Eng. Data , 9(2), 187-91 (1964).
PA-024 Partridge, Everett P., and Alfred H. White, “The
Solubility of Calcium Sulfate from 0 to 2000h1,
3. Amer. Chem . Soc., 51, 360-370 (1929).
PL-007 Player, Murray Richard, “Heterogeneous Nucleation
of Calcium Sulfate Hemihydrate on Heated Surfaces”,
Univ. of Michigan (1969).
-210-
-------
P0-004 Power, Wilson H., Bela M. Fabuss, and Charles N.
Satterfield, “Transient Solubilities in the Calcium
Sulfate-Water System!i, J. Chem. Eng. Data , 9, 437-42
(1964).
P0-022 Power, W. Ii., etal., Thermodynamic Properties of
Saline Water , Monsanto Research Corp., Everett, Mass.,
(1964).
P0-026 Posnjak, E., “The System, CaSO -H 0”, Amer . J. Sci.,
235A , 247-72 (1938).
RA-028 Rabinowitz, Morton N., etal., Final Report on Office
of Saline Water Graduate Research Fellowship Grant No.
14-01-0001-1298 for the period from 1 July 1968 to
30 Sept. 1969, Dept. of Chemical and Metallurgical
Eng. Univ., Michigan.
RI-003 Ridge, 11. 3., and J. Beretka, “Calcium Sulphate
Hemihydrate and its Hydration”, Rev. Pure and Appi .
Chem., 19, 17-44 (March, 1969).
RI-0l9 Riddell, W. C., as cited by K. K. Kelley, et al.,
(KE—039).
SB-O01 Sborgi, U., and C. Bianchi, “Solubilità conducibi1it
e r8ntgenanalisi del solfato di calcio anidro e semiidrato”,
Cazz. Chim . Ital., 70, 823-35 (1940).
SM-012 Smith, Glen Charles, “Heterogeneous Nucleation of
Calcium Sulfate”, Univ. of Michigan (1965).
-211-
-------
TI-Oil Tilden, W. A., and W. A. Shenstone, Phil. Trans.
Royal Soc. , 175, 23-36 (1884), as cited by R. E. Hall,
et al., (HA-062).
ZD-OO1 Zdanoviskii, A. B., and F. P. Spiridonov, “Solubility
of the and Modifications of CaSO 4 O.5H O and
CaSO 4 2H O”, Russ . J. Inorg . Chem., 11(1), 11-13 (1966).
ZD-002 Zdanovskii, A. B., and C. A. Vlasov, “Solubility of
the Various Modifications of Calcium Sulfate in H 2 SO 4
Solutions at 25°C”, Russ . J. Inorganic Chem.,13(1O),
1415-17 (1968).
ZD-003 Zdanovskii, A. B., and F. P. Spiridonov, ‘ t Polytherm
for the Solubilities of Various forms of CaSO 4 xH 2 O
in Water Between 0 and 100°”, J. Appi. Chem. USSR ,
40(5), 1109-11 (1967).
-212-
-------
10.2 APPENDIX B
RADIAN TECHNICAL NOTE 200-014-07
DISSOLUTION KINETICS
LITERATURE REVIEW AND SCREENING EXPERIMENTS
-213-
-------
TECHNICAL NOTE 200-014-07
DISSOLUTION KINETICS
LITERATURE REVIE 1 AND SCREENING EXPERIMENTS
30 May 1972
Prepared by:
James L. Phillips
-214-
-------
1.0 INTRODUCTION
This technical note reviews previous work in the area
of dissolution kinetics. An initial series of experiments to
screen for rate-limiting regimes governing dissolution of
CaCO 3 in aqueous solutions is then formulated.
In Section 2.0, a general approach to correlating
dissolution kinetics data is discussed and several experimental
techniques described. Section 3.0 introduces the concept of
rate-limiting steps or regimes. Detailed results of previous
investigations are presented within this framework. The fourth
and final section outlines a series of screening experiments
for the present study of CaCO 3 dissolution kinetics.
2.0 GENERAL ASPECTS OF DISSOLUTION KINETICS
As in the previously described precipitation kinetics
study (Radian Technical Note 200-014-06) it is convenient to
formulate a rate expression for dissolution in forms of measur-
able process design variables. This is normally written as in
Equation 2-1.
-l —l
R = k . M . 0 mole liter mm (2-1)
R is the dissolution rate of a given substance, k is a rate
“constant” which may vary with liquor temperatures, composition,
and transport parameters, M is a term dependent on the amount
of solid phase present, and 0 is some function of the actual
and equilibrium concentration of the dissolving species. The
typical experimental approach involves measurement of R at
known or constant values of M, and/or 0. The rate “constant”
-215-
-------
k is then calculated. Applicable parameters are varied over
ranges expected to prevail in a typical process and the measured
rates or rate constant correlated for use in large scale design.
The dissolution rate, R, is most comonly determined
by chemical analysis of the liquid phase to detect an increase
in concentration of the dissolving species. Alternately, the
decrease in weight of the solid phase may be measured. The “M”
term is usually assumed to correspond to the exposed surface
area of the solid phase. This obviously may be difficult to
quantify in experiments with suspensions of many fine particles.
0 is nearly always taken to be the difference between the actual
and equilibrium concentration of the dissolving species, perhaps
raised to some power. In more complex solutions, the driving
force needs obviously to be written as a function of ion acti-
vation if it is to vanish explicitly at saturation (see Radian
Technical Notes 200-403-09 and 200-014-06).
In order to quantify R, M, and 0, a means of contact-
ing the two phases must be selected. Three categories generally
considered are fixed-solid/moving liquid, moving solid/ t ’fixed”
liquid (agitated only by the solid itself), and agitated liquid/
suspended solid. The first two techniques are generally used
in more fundamental studies where it is desirable to have quanti-
tative descriptions of liquid velocity profiles and well defined
surfaces for dissolution. Since the present study is intended
for direct application to limestone scrubbing process design
where agitated tanks will be used, only the third technique
will be considered here. Quantitative application of data from
flow situations other than an agitated suspension does not appear
to be practical, given the present knowledge of phenomena in-
vo ived.
-216-
-------
As in the precipitation study there are at least
three choices regarding experimental operation of an agitated
vessel. These are as follows:
a. batch liquid-batch solid
b. continuous liquid-batch solid
c. continuous liquid-continuous solid
The first of these is simplest from the operational standpoint
but the most complex in terms of data analysis. A characterized
batch of seed crystal is introduced to a subsaturated solution
and the concentration of the liquor monitored with time. For
slow dissolution, grab samples give adequate results. For
faster rates, in-situ measurement using ion electrodes or con-
ductivity is required. Calculation of the dissolution rate in-
volves differentiation of the concentration versus time data
as well as correction for any significant changes in area of
the seed crystals during an experiment. An additional compli-
cation can arise if the rate is both particle size and area de-
pendent as happens in some cases (see Section 3.0).
The continuous liquid-batch solid method is very con-
venient for systems in which the change in the amount, area, and
size of seed crystals is negligible during an experiment. Under
these conditions, a “steady state” material balance for the liquid
phase gives the rate directly without differentiation of a con-
centration curve.
The third method is the most difficult to achieve ex-
perimentally since continuous addition of solids is necessary.
It does, however, offer a true steady-state rate regardless of
-217-
-------
changes in the solid mass, area, and size. The rate is cal-.
culated directly from a steady state liquid or solid species
balance.
For the present study, method b can be employed for
dissolution of CaCO 3 in neutral solutions. For higher dissolu-
tion rates in acid solution, continuous solids feed may be
necessary.
3.0 PREVIOUS WORK
For purposes of discussion, previous studies of dis-
solution kinetics have been organized according to the rate-
limiting step for mass transfer. Possible rate-limiting mech-
anisms are discussed in Section 3.1. Sections 3.2-3.6 describe
the results of previous investigations.
3.1 RATE LIMITING REGIMES FOR DISSOLUTION KINETICS
Qualitatively, the following physical phenomena are
involved in dissolution of an electrolyte. First, an ion pair
of the dissolving substance must detach from the crystal lattice.
Dissociation and hydration may also be involved in this step.
The combination of removal of an ion pair and dissociation and
hydration of the ions will be termed “surface reaction” in this
discussion.
The ions next must diffuse through the liquid boundary
layer or film into the bulk solution. This step will be termed
diffusion. In addition to these steps, the diffusing ions may
react with other ions in solution. For example:
C0 + ± HCO (3-1)
)1 Q...
— L
-------
Such a reaction would change the concentration gradient and
thus, the diffusion rate of the diffusing ions. This type of
reaction will be termed 1T bulk reaction”.
Since the steps set forth above are in series, any or
all of them may contribute significantly to the overall rate.
In some cases, if the rate of one step is much less than that
of the others, the slow step is said to be rate-limiting.
That is,the overall rate cannot proceed faster than the slowest
step. More commonly, two or more steps may be of equal magnitude
and furthermore, will interact through their individual contribu-
tion to the species concentration profile near the solid particle.
Table 3-1. summarizes five major rate-limiting regimes
considered in this study. Identifying features of each regime
in terms of observable experimental effects are noted.
3.2 SURFACE REACTION LIMITED DISSOLUTION
Referring to Table 3-1, surface reaction limited dis-
solution is characterized by high activation energies (temperature
dependence), little or no effect of particle size and agitation,
and significant dependence on crystal type and structure. Several
investigators have noted such behavior in previous experimental
determinations of dissolution kinetics. Important details of
these studies are summarized in Table 3-2.
Nestass and Terjesen, in a study of CaCO 3 dissolution
in C0,-saturated water, showed that the dissolution rate was in-
dependent of agitation and was sensitive to adsorbed ions (Sc
in this case). They also estimated a purely diffusion-limited
dissolution rate to be considerably higher than the observed rate.
-219-
-------
TABLE 3-i - D1SSOLUTIQN RATE REGIMES
,,rcn—n Doartlnn
Surface Reaction
+ Diffusion
Diffusion
Diffusion + Liquid
Phase Reaction
Linuid Phase Reaction
(Slow surface reaction,
fast oiffusion)
(Diffusion and surface re- (Fast surface reaction,
action rates of equal mag— slow diffusion of ions
nitude) away from surface)
(Fast surface reaction, slow
diffusion affected by reac-
tion of diffusing species in
the iic sU film)
(Fast surface reaction, fast dif-
fusion)
Xaior Variable Effects
Race corstant is inoepen—
dc t of agitation and
particle s:ze Activa-
ti m erergy ray be nigh
(stgnftcant temperature
ceperdence of rate).
:e —ay be proportional
to nroer of active sites
rntrr tnan surface area.
Lt—esco-e t oe and cry-
stal structure can have a
najor effect on rate.
Drnjnz Force Porn
Driving force based on
S.jlk species activities
and solubility product
(K )
sp
Rate constant sensitive to
agitation and particle size
at hi.gh tenperature. Less
sensitive at Lower tempera-
ture. Rate constant more
sensitive to temperature at
high agitation and small
particle size. Intermediate
activation energy. Rate may
be influenced by surface
area and nuriber of active
sites. Limestone type
could be important.
Driving force based on un-
known intermediate value
of species activities in
liquid fun. IrRasist cesu
are additive only if a
linear driving force appli
to the reaction step as well
as the diffusion step.
Race constant sensitive
to azitation and particLe
site. tow activation
energy. Limestone type
should not be an impor-
tant variable.
Driving force is linear
with the difference of
actual and equilibrium
species activities in
the bulk solution.
Rate constant sensitive to
agitation, particle size, and
concentration of reactants in
bulk liquid. Low activation
energy. Limestone type not im-
portant. Possible reacting
speci s affecting tbe rate
are H , S0, and SO (also
usa ;, uca;3.
Driving force is linear with
species activities.
Rate constant independent of agi-
tation, particle size, and crystal
structure.
Driving force involves activities
of reacting species in the bulk
solution in addition to dissolv-
ing species.
Correlation + Scale-up TechniAues
Correlation and scale-
t.p not difficult for a
s ir. le crystal ty je . A
ell-defineo Biiving fore
function and temperature
dependence may be deter—
irined in lab.
Correlation and scale-up Good correlation and
extremely difficult even scale—up possible over
for a single limestone reasonable particle size
type. Laboratory rate con- ranges and for gearetri-
stants and driving force cally similar vessels and
functions may not be applied agitators. Conventional
in large vessel unless stric- dimensionless groups used
test attention is given to to calculate mass trans-
system geometry. Data are fer coefficient.
needed over entire range of
all variables.
Correlation end scale-up more
difficult than simple diffus-
ion regime. Rate constant
must be correlated with bulk
concentration of reactants in
addition to other parameters
in diffusion regime.
Correlation and scale-up not diffi-
cult if only a limited number of
reacting species is involved.
NJ
NJ
C
-------
TABLE 3-2 - SURFACE REACTION LIMITED DISSOLUTION
Re ference
Nestass and
Terj esen
NE- 032
Other Conclusions
Agitation had no effect.
Estimated diffusion-
limited mass transfer
rate was sIgnificantly
higher than observed
rate.
Drehmel
Lime and Limestone
in water and 115503
Trickle funnel and
small magnetically
stirred beaker. Batch
solids dissolution
at constant pH
12 solid types. p11 4
to pR 1 solutions
10-110°F temperatures
lOO-l000u particles
None given
Interpretation of re-
sults must be qualita-
tive since driving force
functions were not cal-
culated.
5-6 kcal/mole activation
energy for CaCO 3 dissolu-
tion.
Armstrong and
Prosser
AR-014
Bovington and BaSO, in 11 O
Jones
30-048
Canpbell and Sr50 4 in 11 O
:;ar.co i Las
CA- 065
Fixed plate in stirred
solution. Batch soLid
and liquid
Agitated 250 ml flask
Surface area effect less
than 1.0 power.
Factor of 30 difference
in apparent dissolution
rate of marl and calcite.
Dissolution proportional
to BET surface area which
was —lOx external area.
Crinding, polishing, and/
or cleaning alters the
dissolution rate markedly
(in addition to surface
area effects).
Particle size effects due
to increase in ratio of
deformed surface thick-
ness to total crystal
thickness.
No effect of 507. increase
in agitation.
High activation energy
—25 kcal/mole.
Surface active substances
inhibit dissolution rate
markedly.
Little and
Nancollas
PbSO 4 in 1150
Not specified
4% seed crystals
Rate—k A(C*_C)°
Rate inhibited by
tetrametaphosphate.
Chemical System
CaCO 3 in 11 ,0 under
CO pressure (In-
hi ited by Sc ’ions)
Mechanical System
Not specified. Agita-
ted suspension with
CO 5 gas bubbled
through
Range of Variables
Not specified
Rate Correlation
Rate —
N i
1 . -i
I-
Pure ?%0 crystals
in 1.38 t I HCI.
Agitated suspension.
Batch solid and
liquid
1°C, 40°C None given
Large single crystals
Also ground crystals
with mean particle
sizes of 5 16, 55,
156, and 3 0 microns
10.5°C, B5°C Rate.kCC*_C)°
1 5 u seed crystals Rate—k A(C*_C)’
LI-033
-------
Drehmel studied dissolution rates of 12 naturally occur-
ring limestones and dolomites using a constant pH titration
technique. Although the measured activation energy for lime-
stone dissolution was comparable to that expected for a dif-
fusion limited mechanism (5-6 kcal/mole), dissolution rates
varied by as much as thirty times with different limestone
types. This behavior indicates a strong dependence on a sur-
face reaction step.
Dependence of dissolution rate on surface effects
was also demonstrated by Armstrong and Prosser. In work with
MgO crystals dissolved in l.38N HC1, grinding, polishing and/or
cleaving altered dissolution rates of single crystals markedly
in excess of effects accounted for by surface area changes.
They postulate that dissolution is related to lattice disloca-
tions on the crystal surface in a manner similar to precipita-
tion processes. Studies with different particle sizes produced
a threefold increase in dissolution rate per unit area as cry-
stals were ground from 35Oi. to 5 1.L mean particle size fractions.
This rate increase in excess of the area increase was attributed
to an increase in the number of dislocations or active sites for
dissolution.
These three studies have in common alkaline solids
dissolving in acid solutions. Under these circumstances, the
liquid film diffusion resistance could be unusually low due to
liquid phase reaction of diffusing species. The observation
that dissolution rates are surface reaction limited for this
situation is quite r asonab1e. This behavior cannot be gener-
alized to neutral or alkaline solutions, however, since dif-
fusion and surface reaction resistances may then be of similar
magnitudes.
-222—
-------
Naricollas and several coworkers have studied the dis-
solution rates in water of slightly soluble sulfates including
BaSO 4 , SrSO 4 , and PbSO 4 . All of these investigations led to a
driving force term of the form
0 = (a* — a) 2 (3-2)
where a* is the equilibrium activity of the dissolving species
and a is the activity in the bulk solution. This form is
probably not representative of a diffusion limited rate mecha-
nism. The dissolution rates were also found to be significantly
inhibited by trace amounts of surface active additives such as
tetramataphosphate. In the BaSO ,, investigation, a 50% increase
in stirring rate had no effect. Also, an activation energy of
25 kcal/mola was observed. This work shows that a surface re-
action can limit dissolution even when diffusion is not aided
by reaction in the liquid film.
In general, it is quite possible that the rate limit-
ing mechanism for limestone dissolution may change as the acid-
ity of the solvent solution increases or decreases. This will
be a consequence of reaction of H+ with the diffusing C0 or
0H ions in the liquid film (see Section 3.5).
3.3 SURFACE REACTION AND DIFFUSION LIMITED DISSOLUTION
The postulated mechanism for dissolution includes a
number of steps in series which all depend on concentration
profiles of the dissolving species. These conditions can result
in intermediate regii nes where both diffusion and reaction rates
contribute significantly to the observed overall rate. Experi-
mental effects characteristic of intermediate rate-limiting
regimes have been noted in several previous studies of dissolu-
tion kinetics. These are summarized in Table 3-3.
—223-
-------
TABLE 3 3 - SURFACE REACTION AND DIFFUSION-LIMITED DISSOLUTiON
______________________ Rate Correlation Ocher Conclusions
None given explicitly Dissolud.on is first +
order with respect to }
(Inversely proportional
to 0H).
Rate constant is a func-
tion gf speed of rotating
disc. Race constant ver-
sus speed of rotation
plot is assynptocic at
high level. The race
dependence on rotation
is greater at 25°C than
at 4°C.
Fast hydration followed
by slow dissolution is
postulated.
Rate—k (C*_C) Rate inhibited by Cu
where C* and C are ions. k a(9PN)
bicarbonate concen-
trations
Rate—k A(C*_C)
with k a(RPN) 5
and k a. exp(lO ,000/RT]
Chemical. System
Re ference ___________________
MacDonald and MgO in }l SO
Owen
MA- 142
Erga and CaCO 3 in C0 3 -saturated
Ter esen water
ER- 007
Lin and Nancollas CaSO 4 2N O in H 0
1 1-031
Mechanical System
Pellets imbedded in
rotating disc
10 liter agitated
vessel. Batch solid and
liquid
250 ml stirred flask.
Batch solid and liquid.
Range of Variables
4°C, 25°C 100-1000RPM
(laminar flow regime)
300-400u particles,
.95, .66, .39, .135
atm CO 5 partial
pressure, 280-555 RPM
150, 300, 600 RPM
The dissolution rate of
CaSO is considerably
faster than other sulfate
studied (see 3.2).
An activation energy of
10 kcalfmole was observed.
-------
The paper by MacDonald and Owen presents an excellent
discussion of series rate steps and experimental observations
indicating both surface reaction and diffusion resistances.
The temperature/agitation interaction observed in this study
of NgO dissolution is typical of the combined rate limiting
mechanism. The experimental dissolution rates were influenced
by speed of rotation of the MgO pellets, but less so than pre-
dicted by mass transfer theory. Furthermore, the effect of
rotation was less at a lower temperature as the reaction step
became more significant. These investigators also note that
the rate of increase of dissolution with agitation becomes
small at high levels of rotation as the diffusion resistance
becomes negligible with respect to the reaction resistance.
The rate increase with temperature corresponded to an activation
energy ranging from 4.5 kcal/mole at low rotation speeds to 6
kcal/mole at high speeds.
Erga and Terjesen studied CaCO 3 dissolution rates in CO,-
saturated water. They found the rate was inhibited by trace qual-.
ities of copper ions, indicating significant surface reaction
effects. The rate was dependent on agitation, but to a lesser
extent than expected for a diffusion-limited mechanism.
Liu and Nancollas observed similar behavior in dis-
solution experiments with CaSO 4 2H 2 O in water. Their experi-
mental dissolution rates were proportional to the agitator
speed to the .5 power. The observed activation energy was 10
kcal/rnole indicating.some contribution from a resistance other
than diffusion.
-225-
-------
3.4 DIFFUSION-LIMITED DISSOLUTION
The bulk of reported investigations of dissolution
rates in agitated vessels fall into the diffusion limited cate-
gory. Many attempts have been made to develop general correla-
tions of diffusion-limited dissolution rate constants with
vessel and agitator design parameters. Historically, most dis-
solution processes have been assumed to be diffusion rate limited.
Consequently, the absence of contributions from surface or bulk
reaction has not been experimentally verified in most cases.
This point must be kept in mind when reviewing available infor-
mation. Details of several studies appear in Table 3-4 in
chronological order.
The types of correlations proposed for prediction of
diffusion-limited solid-liquid mass transfer can be categorized
as follows:
a. Fr issling correlations based on particle
Reynolds number
kD ID = 2 + A N;e ( /D)
where D is the particle diameter and
NRe = D U 1 /v. Here, 13 ? is the so-called
slip velocity or terminal velocity of
the particle in the fluid.
b. Gilliand-Sherwood correlations of the
form
B
k d/D = A NRe (v/D) (3-4)
-226-
-------
TABLE 3-4 - DIFFUSION-LIMITED DISSOLUTION
Chemical System
BeI CCLC acid, rock
salt, and Bad in
water. Naphtha!ene
in methanol
Rate Correlation
Above Ng — 6.7x 10
Kd/D —
( 1 jpD) ‘
Below N • 6:7x10
Itd/D — 2.7x 10’
•5
(n f p/u) (u/pD)
Other Conclusione
Two different rete re-
gimes probably due to
incomplete particle
suspension at low
Tamperature effects not
Checked.
Mack and
lOarr inar
W.- 146
)hzsphrey and
VanNe g
HU-006
9.7”and ].ô’ diameter
x 24” high baffled
tanks
Batch Liquid and •olid
6—gallon baffled tank
12 diameter x 12’ high
Propeller and turbine
type agitators.
Steady etate continuous
flow of eolida and li-
quids
57°F—82’F
2, 4, 6-blade agA-
tacors with 3 to 1.1”
blades
25O fold range of
particle surface
area 92-1530 RPM
.OO6 -. .82 H.P.
Large particle re—
gune (7nm+)
200-600 RPM with
turbine
400-1300 RPM with
propeller
l.arga particle re-
gime (.73-1,5 me)
where K-mass transfer
roe! ftc Lent
d—tank diameter
Ddtffusivity of dis-
solving species
n—stirrer RP
D - f1uLd density
uflutd viscosity
d/B — (H/d) P
C I ..I U
((Pg/n L p) nL )
where
Il-i (quid height
0—neutralization
time
P—power
L—isipeller diameter
ltdlD — a(u/pD)
(nd p/u
a—. 13 for propeller
—.0032 for turbine
b—.58 for propeller
—.67 for turbine
Rate - It A(C*.C)
No correlation for
K given
No particle size effect.
Baffle size and type
not significant. (Only
presence or absence
had effect.)
Tenoerature effects not
checked.
No particle size effect.
Teeperature effects not
considered.
lODu or smaller particle.
were nearly perfectly
mixed,
No effect of impeller
epand for 1000 R.PN and
above.
No particle site effect
for large particles.
Equations given for
various CSIR configura-
tions.
Temperature effects not
considered.
Reference
Hixon end
B a a
HI-Oil
4-blade, 45’ pitch
agitators
13, 21, 26, 36, 46,
61 cm. ves e1a
similar geometry main-
tained
height • diameter
Range of Variables
100-500 RPM
Room temperature.
Large particle regime.
N.)
Bensoic acid
.00191( NaOli
in
Mattern, et.al. HaCl in brIne 1.3
4 ”
x -iao hi h
1½
liter vessel
diameter x 5½”
(fully baffle
marine propeller
20—50 mesh MaCi
(3 fractions)
1000-1500 RPM
-------
TABLE 3-4 - DIFFUSION-LIMITED DISSOUJrION (coot.)
Page 2
Re ference
Chemical System
Mechanical System
Range of Variables
Rate Correlation
Other Conclusions
Barker and
Treybal
BA-125
Large particle regime
(.5—1.5 nan)
500-1400 RPM for small
turbine
200-700 for medium
140 for large
Density difference .06—
.99 g/cc
N, ,“1140-62000 for
benzoic acid
—735-55000 for boric
acid
No particle size effect.
No effect of density
dtfference. D ffusivity
not signtficant. o
effect of turbLne/tank
diameter ratto. Baffles
increase k sLgnificantly.
No effect of wet&ht per-
cent SOILdS in reactor.
Temperature effects not
considered.
Power/unit volume not
adequate to correlate
data.
Ni
Ni
Dispersed bubbles in
agitated vessel
Wide range of diffusivi—
ties and viscosities,
lOOu to 8 ,mn bubbles.
Other variable ranges
not specified
kN .l3(PIvu/o’) ’
(with —66l. atd. de-
viat ion)
Power required to
suspend particles r—
related by
P/V. ’const(gAp )tal
u’ D, I’ (wt7.)’’/p’ ’
Baff Led agitated vessel. SxlO’ — 10’
6’ diameter x Il’ high, a
Continuous liquid, batch 25.O’C
solid (fixed in vessel
bottom). 3” diameter
6-blade turbine.
Wide range of variables
.07 — 122 HP/bOO gal,
130 — 1500 RPM for
small vessel 85 — 1500
for intermedIate 200
RPM for large tank,
15 to 1000 u particle
size.
kd/D — .4O2(N ) (NR c) 4 ’ Tenperature not con-
sidered.
(turbine Reynolds no.)
Transition effect
noted at Ng — 60,000
Temperature not considered.
Large deviations from
corrclat on.
Unbaffled dissolution
rates 2.5 times baffled
rate.
Effect of baffles on rate
depends on degree of par-
ticle suspension. Tem-
perature not considered.
No particle sire effect
for Dp > 200 i.
Use of power/volume or
turbine NR c is net mean-
ingful in general.
(cent.)
Boric acid, benroic
acid, and rock salt
in water and sucrose
solutions
6, 12 18, 30” baffled
vesseis
2, 3, 4, 6, 9, 12” dia-
meter 6-blade turbines.
Batch liquid and solids.
Turbine NRO adequate
to correlate k for a
single vessel, but
not generally
N OS 2 NRe ’USNSc ’l
where NRe flLl p/u
Power/unit volume
not adequate to
correlate data
Calderbsnk CO , in H 0 and glycol,
and Moo-young ‘0, in H l and brine,
N, in wax,
CA-066 Resin beads in HO
Marangozia
and Johnson
MA-l69
Benzoic acid in IlgO,
0-salicylic acid in
14,0, benroic acid in
glycerol solutions
Impeller N type cor-
relations § e consistant
with this developrent,
but require sii ILlar geo-
metry for extrapolation.
After particles are sus-
pended, little is gained
from additional power.
Plarangozis Review of previous data
and Johnson
)lA-l47
Marriott
W i—Ui
Benzoic acid, PbSO 4 , ion 4” flask, 8 and 21”
exchange beads, and boric tanks. ilj, 2, 3, 4,
acid in water and polymer and 7” 6-bladed tur—
solutions. bin . ,.
bc
kd/D — ScNRe
where NRa — nL’p/iI
Mo aatisfactory cor-
relation for all data.
For Dp > 100 j, kcn”.
For Dp — 15 ii, san’,
For Dp<200 u,
ktDp .S
For AP .4
(coet.)
-------
TABLE 3-4 - DITYUSION-LIMrrED DISS I7TION (cone.)
Page 3
Review of previous
work
Rate Correlations
Best general correlation
uses slip velocity theory
followed by corrections for
Dp, n, and L/d.
No satisfactory general
correlation has been fot—
nulated.
Other Conclusions
Power/volume nay be adequate
if similar geometry is rain—
tamed. No effect of wt.
solids for large particles.
Suggests the use of an
effective turbulent diffusi—
vity rather than the usual
molecular value would improve
results.
Middleman Discussion of
) x-O66 Marriott’s data,
1, 10, 100 gallon baffled
agitated vessels with
fixed pellets of BzOli.
4, 8, 18” 4-blade paddles
in 6, 12, and 27” veasela.
Batch solid, continuous
liquid. Geometric similar-
ity maintained.
3-fold density range,
5-fold diffusivity,
200 - 10 nen particle
aize. Several differ-
ant impeller positions.
100-2000 RPM.
Suggests use of Kolniogoroff
theory of isotropic turbu-
lence to establish slip
velocity for use in Frdss—
ling-type correlation.
Nsh 2 +.6 4 0 N
This techniaue relates the
particle Reynolds number to
the impeller Reynolds num-
ber.
VrSssling equation used.
N 2 1 IN” “
Sh Re’Sc
Large standard deviation
in data fit to thia cor-
relation.
Frtissling equation used
with slip velocity calcu-
lation modified for parti-
cle size effects.
ken’ 5 for low impeller
position
kcn ° for high impeller
position
km PowerS” after particles
are suspended
Actual k’s will be 10-SOZ
greater than predicted k ’i.
No couneents on estimation
of slip velocity for sus-
pended particles.
If particle size remains the
same with scale-up, fixed
impeller tip speed is good
criterion.
bnpetler position has little
effect at high enough RPM to
auspend all particles.
Suall particles yield pre-
dicted coefficients close
to actual values.
power/volume is net an ecortom-
ical method to increase k
after particles are suspended.
Chemical System Mechanical System
Reference
Marriott
•IiAlll (cent.)
Killer
MI-0 59
Ran.. af Va,lahl ..
Bensoic acid in
H ,O
Miller
MI-058
Nienov
Nl-OlZ
Impeller NRe
27,270 — 631,830
P/v .04 — l6.6MP/lO00 l.
170-450 RPM in small
vessel. 110-300 in
intermediate. 20-170
in large vessel. 1/8,
1/4, 172, lv.” pelleta.
X,SO , NH 4 C1, 4 and 6-blade turbines.
alum, MaCi, 1 1 12 and 14 cm-baffled
all in water vessels. Batch solid
solution and liquid.
-------
TABLE 3-4 - DIFFUSION-LIIIITED DISSOLUTION (cont.)
Page 4
Reference Chemical System Mechanical System
Brian, et al. Pivalic acid in 11,0 Stirred flask 12 cm di-
aineter x 11. cm high.
BR- 083 Fully baffled 6 cm 3-bla
marine propeller, 5 cm
4-blade turbine agitator.
Batch liquid and solid.
Range of Variables
100-400 RPM
Pover/n ’L ’p — .42 for
maxine
propeller
— 11.1 for
turbine
Large particles 1.5-
3 mm.
Rate Correl tLons
44
f(PIVDDO ii)
I A 4
Other Conclusions
Data are very scattered.
Negligible effect of Ap for
< 251.
No particle •iza effect for
large particles.
Large particles (also
uses Marriott’s small.
particle data):
0.5 — 19 HP/bOO gal.
170-490 small tank RPM
100—290 intermediate
25-170 large
For large particle flow
regime, the Fr8saling
equation is used to get
kmjn. Then
k/kmin .027(RPIIY ’
For small particle regime
— 2
and
D(SffectLV) - D x 3.O8(
Miller
Benmoic acid in 1, 10,
100 gallon tanks,
Ml- 020
11,0
4-blade
metric
tained.
and eobid.
turbines. Geo-
similarity main-
Batch liquid
For Op < 200 u, radial
diffusion is dominant sech-
anise. Power input/volume
is not adequate for scale-up.
-------
where k is the mass transfer coefficient,
d a characteristic length for the system,
D the diffusivity of the dissolving species,
v the kinematic viscosity of the liquid,
and NRe a system Reynolds number. NRC may
be based on tank dimensions: NRe =
(n = RPM, d = tank diameter), or impeller
dimension: NRe = nL 2 /v (L = impeller diameter).
c. Power input correlations of the form
k = f (Power/Volume x
Early investigators generally used the Gilliand-
Sherwood form. The studies of Hixon and coworkers, Humphrey
and Van Ness, and Barker and Treybal are typical of this
approach. Characteristic observations of variable responses
include no effects due to particle size, Reynolds number ex-
ponents ranging from .5 to .9, Schmidt number exponents of .3
to .5, and significant differences between baffled and unbaffled
vessels, but no effect of baffle type or size.
Harriott and other proponents of the slip velocity!
Fr ssling equation approach have pointed out the fundamental
difficulty of the Gilliand-Sherwood correlation in that it com-
pletely ignores the fact that qualitatively, the mass transfer
rate must depend on the velocity profile near the particle it-
self. The use of a Reynolds number based on propeller speed
and tank or propeller diameter is obviously not theoretically
justified and consequently cannot be safely extrapolated. This
has been demonstrated experimentally. Correlations based on
impeller Reynolds number are not valid over varying tank dimen-
-231-
-------
sions and those based on tank dimensions and tank Reynolds
number vary with impeller dimensions.
The apparent particle size independence of the
Gilliand-Sherwood correlation has also proved incorrect. For
sufficiently small particles, (D < 200 microns), the mass
transfer rate is a strong function of particle size.
The slip velocity approach based on the Fr ssling
equation is more satisfying theoretically, but also suffers
several practical limitations. This correlation is given by
kD /D = 2 ÷ A (DPUTp/ L) 5 (‘ /D) 3 (3-6)
The first term on the right hand side represents the contribution
to the rate from molecular diffusion and the second from forced
convection. In the large particle regime, the second term dom-
mates. In the small particle regime, the slip velocity U 1
approaches zero and the first term dominates.
The terminal or slip velocity of the particle must be
estimated in order to use Equation 3-6. Normally, this may
be done using conventional drag coefficients for spheres, but
the resulting values are usually low and yield a conservative
value for k. The discrepancies arise from the fact that the
turbulent eddy size in agitated vessels may be of the same
order of magnitude as the particle diameters.
For small or very light particles, the slip velocity
approaches zero and the molecular diffusion term determines the
rate. Again, difficulty is encountered in this case. The
actual or effective diffusivity generally is greater than the
stagnant molecular diffusi’vity because of transport by turbulent
-232-
-------
eddies. Predicted mass transfer coefficients fall lower than
actual values as a result.
}iariott and Miller have both proposed empirical
corrections to the basic slip velocity theory to account for
these discrepancies. The generality of these schemes is
questionable, of course.
The third major approach to prediction of diffusion
limited mass transfer is based on the Kolniogoroff theory of
isotropic turbulence. Qualitative reasoning regarding the
mechanism of energy dissipation in agitated vessels leads to the
conclusion that the velocity field “seen” by suspended particles
should be primarily a function of power input per unit volume.
A dimensionless group involving the agitator power input and the
viscosity and density of the solution is used to correlate k.
The power/unit volume for a given agitator and speed of rota-
tion is a function of system geometry. Thus, this approach
requires geometric similarity to be maintained.
Papers by Barker and Treybal, Calderbank and Moo-Young,
Harriott, Middleman, and Nienow (see Table 3-4) discuss the power
input approach to vessel scale-up. In general, this correlation
technique appears to be less successf l than the slip velocity
approach.
Summarizing previous work on diffusion limited dis-
solution, important variables that must be considered in this
rate limiting regime are as follows:
Agitator design, speed of rotation, and
location.
-233-
-------
Tank geometry and baffling.
Fluid transport properties.
Particle size and density.
Minimum agitation necessary to suspend
particles.
Some important generalizations that appear throughout the
literature are as follows:
Particle size effects are important for
small particles only (1D c 200 microns).
Power input increases the mass transfer
rate significantly only in the region
where full particle suspension has not
been achieved. Above this level, the
rate varies with power to the .2 or less
exponent.
Particle-liquid density differences are
significant at levels higher than 257O.
The presence or absence of baffles affects
the rate, but the type of baffling does
not.
The mass transfer rate is independent
of slurry density for large particles.
-23 1k-
-------
Maintenance of geometric similarity
is necessary for reliable design and
scale-up.
3.5 DIFFUSION 1ITH CHEMICAL REACTION IN THE LIQUID PHASE
In a diffusion—limited mass transfer situation, any
variable that changes the activity gradient of the diffusing
species will change the overall rate. Thus, removal of diffus-
ing ions from solution by chemical reaction will increase the
rate by increasing the activity gradient. This mechanism may
prove to be very important in lime or limestone dissolution in
scrubbing liquors.
Since diffusion processes are greatly complicated by
chemical reaction, relatively few experimental studies have
characterized this rate limiting regime. Applicable studies are
summarized in Table 3-5.
The usual approach to correlation of mass transfer
coefficients when liquid phase chemical reaction is significant
is to examine the ratio of k with diffusion and reaction to k
with diffusion only as a function of the concentration of
reactant (s) in the liquid phase. For the simplest case of a
rapid irreversible reaction between a single dissolving sub-
stance A and a liquid phase reactant B, the film theory of dis-
solution leads to
k/k 0 1 + DBCB/Q CA 3 (3-7)
Other more complex functional relationships result with re-
versible reactions and reactions involving several species.
Ionic reactions make the problem more difficult because of
charge interaction between the diffusing species.
-235-
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TABLE 3-5 - DISSOLUtION LIMITED BY DIFFUSION AND LIQUID PHASE REACTION
Reference
Sherwood and
Ryan
SH-073
Range of Variables
17°C, 25°C, 33°C
N R a — 136 -. 103,400
Rate Correlations
NaOH concentration in
“° bulk solution.
Film Theory: A+B Pass
— _ _ _
Corrected for ion Diffusion:
h - l+ !$t.x{.Jl+gs.a_.Q.L
where:
— ionic conductance
F — Faraday’s constant
C 0 — concentration in bulk
solution
C 1 — concentration at parti-
cal surface.
Benroic acid and
0-salicylic acid
in NaCH and 1(0K
solutions.
6” diameter c 12” high
a itated vessel with
3 6-blade turbine. Or-
ganic acid cast in ring
on bottom.
MgO, Mg(OH). l.a Not specified.
KC1 and KCIO 4
solutions.
Boundary layer theory with
ion diffusion effects.
k N 5 1/3 N 5 c
- + (N a)
Ion diffusivities used in
Nsc (see Sherwood and Wei).
10-30 i i particles, slow Rate mechanism apparently
agitation, pH 3 to pH 10. changes in different pH
ranges.
Chemical System Mechanical System
Bonzoic acid in
water and NaOH so
solution (2 order
fast irreversible
reaction).
Rotating cylinder 30 em
diameter in a 10 cm diam-
eter 1 1.5 liter vessel.
Other Conclusions
Ni
Marangozis
and Johnson
MA-l49
Vermilyea
VE-0 13
1) + 1)
Very poor reproducibility
of results.
-------
Sherwood and Ryan conducted dissolution experiments
with benzoic acid in water and dilute NaOH solutions. After
establishing a correlation for the mass transfer coefficient,
k 0 , without reaction, NaOH solutions were used to establish a
correlation for mass transfer with reaction. Results could
be adequately correlated using the film theory corrected for
ion diffusion effects. Boundary layer theory predicted a
slightly lower enhancement factor (k/k 0 ). The experimental
range of k/k 0 varied from 1.6 to more than 30 as the ratio of
NaOH to the saturated benzoic acid concentration increased
from .3 to 20. Use of the film theory with molecular diffusivit-
ies rather than individual ion values leads to errors greater
than 50 percent. The actual value of the enhancement factor is
considerably greater than that predicted using molecular diffusiv-
ides especially where the reacting ions diffuse faster than the
dissolving ions.
Marangozis and Johnson studied dissolution of benzoic
acid in NaOH and KOH and 0-salicylic acid in NaOH. Their re-
suits agreed well with enhancement factors predicted by boundary
layer theory corrected for ion diffusion effects. Experimental
k/k 0 ratios ranged from 2 to 15 as the ratio of NaOH to dissolv-
ing species concentration was increased from .4 to about 4.
Considering the magnitude of these effects, if the re-
action of and C0 3 affects the rate of CaCO 3 dissolution, it
would do so even at relatively neutral levels of pH. This is a
consequence of very low equilibrium levels of C0 3 in limestone
scrubbing solutions. That is, the concentration of H+ is of the
same order of magnitude as that of C0 even at a pH of about 7.
—237-
-------
An investigation by Vermilyea with MgO and Mg(OH) 2
showed an apparent change of mechanism from simple diffusion
to diffusion plus reaction limited regimes as the pH was varied.
The experimental results of this study were not very reproducible,
but serve to illustrate the possibility of a change in rate limit-
ing mechanism over a range of experimental conditions.
3.6 LIQUID PHASE REACTION LINITED D1SSOLUTION
Although no previous experimental studies of dissolution
limited by liquid phase reactions were found, this rate limiting
regime could be encountered in limestone scrubbing processes.
Conceptually, if limestone dissolution rates were much faster
than CaS0 3 H 2 O and CaSO 4 2H 2 O precipitation rates, the rate of
dissolution of limestone could be limited by the rate of pre-
cipitation. The possibility of this situa ion can perhaps be
estimated given adequate rate data for limestone dissolution.
4.0 SCREENING EXPERIMENTS
Because of the possible complexity of the limestone
dissolution rate form and the fact that it may change with pro-
cessing conditions, it is desirable from an experimental stand-
point to establish ranges of rate limiting regimes before attempt-
ing rate correlations. A set of screening experiments for this
purpose has been devised based on major variable effects noted
in previous studies.
Table 4-1 summarizes conditions for these initial
experiments. The sequence starts with dissolution in water at
high temperature. Under these experimental conditions, surface
reaction is favored over diffusion. If no agitation effect is
LJ0
-------
TABLE 4-1 - LI11E 0NE DISSOLUTiON SCREENING EXPERIMENTS
High Temperature (50°C) Low Temperature (25°C )
Water (CO 2 free) 1. High Agitation 3. High Agitation
2. Low Agitation (If significant, 4. Low Agitation
check 25°C level.)
Acid (pH 5) 5. High Agitation 7. High Agitation
6. Low Agitation (If significant, 8. Low Agitation
check 25°C level.)
)
‘A,
NOTE: A set of eight experiments will be performed with each of two limestone
types.
-------
noted at this level, the dissolution rate will probably be
surface reaction limited for most process conditions. If agita-
tion is significant, two more runs in water at 25° will be made.
At this lower temperature, the surface reaction will be slower.
A similar agitation effect at this temperature would indicate
little or no contribution from the surface reaction rate. A
decreased agitation effect would point to a combined surface
reaction/diffusion rate limiting mechanism for the neutral liquor
environment.
Diffusion rates should be greatly increased for
dissolution of CaCO 3 in acid solution. Experiments 5 and 6
are expected to show a decreased dependence on agitation and
an increased surface reaction contribution to the overall rate.
Experiments 7 and 8 represent conditions where the ratio of
diffusion rate to surface reaction rate should reach an upper
bound for normal process conditions.
This series of eight experiments should be conducted
with at least two limestone types so that possible differences
in surface reaction rates between crystal types can be detected.
Particle size effects on rate limiting regimes may also be
important.
The results of these screening experiments will
provide a basis for additional runs to correlate the dissolu-
tion rate with important parameters.
-240-
-------
REFERENCES
AR-014 Armstrong, J. T., and A. P. Prosser, Inst. Mining
Met. Trans., Sect . C, 79, pp 66-68 (1970).
BA-125 Barker, J. J., and R. E. Treybal, A.I.Ch.E. Journal ,
6, pp 289-295 (1960).
B0-048 Bovington, C. H., and A. L. Jones, Trans. Farad . Soc.,
66, pp 764-8 (1970).
BR-083 Brian, P. L. T., H. B. Hales, and T. K. Sherwood,
A.I.Ch.E. Journal , 15, pp 727-33 (1969).
CA-066 Calderbank, P. H., and M. B. Moo-Young, Chem. Eng .
Sci., 16, pp 39-54 (196]).
CA-065 Campbell, J. R., and C. H. Nancollas, J. Phys . Chem.,
73, pp 1735-40 (1969).
DR-004 Drehmel, D. C., “Limestone Types for Flue Gas Scrubbing”,
Presented at Second International Lime/Limestone Wet
Scrubbing Symposium, New Orleans, Nov., 1971.
ER-007 Erga, 0., and S. G. Terjesen, Acta Chem. Scand. , 10,
pp 872-874 (1956).
HA-ill Harriott, P., A.I.Ch.E. , 8, pp 93-102 (1962).
HI-Oil Hixon, A. W., and S. J. Baum, md . & Eng. Chem. , 33,
pp 478-485 (1941).
HU-006 Humphrey, D. W., and H. C. VanNess, A.I.Ch.E. Journal ,
3, pp 283-286 (1956).
-241-
-------
LI-033 Little, D. M. S., and G. H. Nancollas, Trans. Farad .
Soc., 66, pp 3103-12 (1970).
LI-031 Liu, S., and C. H. Nancollas, J. tnorg. Nuci . Chem.,
33, pp 2311-16 (1971).
MA-142 Macdonald, D. D., and D. Owen, Can . J. Chem., 49,
pp 3375-80 (1971).
MA-146 Mack, D. E., and R. A. Marriner, Chem. Eng . Prog.,
45, pp 545-552 (1949).
MA-147 Marangozis, J., and A. I. Johnson, Can . J. Chem . Eng.,
40, pp 231-237 (1962).
MA-149 Marangozis, J., and A. I. Johnson, Can . J. Chem . Eng.,
39, pp 152-158 (1961).
MA-180 Mattern, R. V., 0, Bilons, and E. L. Piret, A.I.Ch.E.
Journal , 3, pp 497-505 (1957).
111-066 Middleman, S., A.I.Ch.E. Journal , 11, pp 750-61 (1965).
111-059 Miller, D. N., md . & Eng . Chem., 56, pp 18-27 (1964).
111-061 Miller, D. N., Chem. Eng . Sci., 22, pp 1617-1626
(1967).
111-020 Miller, D. N., Chem. Proc. Des. Develop. , 10, pp 365-
75 (1971)
-242-
-------
NE-032 Nestaas, I., and S. G. Terjesen, Acta Chem. Scand. ,
23, pp 2519-31 (1969).
NI-012 Nienow, A. W., Can . J. Chem . Eng., 47, pp 248-58
(1969).
SH-073 Sherwood, T. K., and J. N. Ryan, Chem. Eng . Sci., 11,
pp 81-91 (1959).
VE-013 Verniilyea, D. A., J. Electrochem . Soc., 116 , pp 1179-
83 (1969).
-243-
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10.3 APPENDIX C
TRIP REPORTS OF SHAWNEE
ANALYTICAL SUPPORT
-244-
-------
5 January 1973 (Revised for Final Report)
MEMORANDUM
TO: F. S. LaGrone
FROM: C. T. Shelton
RE: Trip Report
From December 27 through December 29, I visited the
Shawnee Steam Plant at Paducah, Kentucky at the request of
Joe Barkley of TVA. He wanted the following changes made to the
Laboratory Analysis System software:
I) The total suLfate calculation needed to
be recorrected. Shawnee personnel thought
it was wrong at first and Mike McAnally changed
it, but now they decided it was ok originally.
2) Bechtel personnel feel that the weight percent
solids in the slurry data is not getting
onto the data tape.
3) Shawnee personnel wanted the ability to print
out multiple copies of the final report using
only one command.
-245-
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MEMORANDUM - Trip Report
5 January 1973
Page 2
4) Shawnee personnel wanted about 20 default
values put into the programs for values that
were never changed on the card inputs. This
would cut down greatly the number of
variables input via cards on some analyses.
When I got to Paducah, Mickey Martin, one of the lab
technician shift supervisors, had two more changes:
I) They wanted the sample point number printed
in addition to the sample ID and run number
in the LISTS system command.
2) The system indicated that not all analyses
had been done when they had been.
I made the foLlowing changes to the system:
1) I recorrected the sulfate calculation to
its original form in FRPRT.
2) I checked to ensure that data from cards
for weight 7 solids actuaLly got onto
the disk in the correct locations in the
data packet. I then dumped a data packet
to mag tape, deleted it from disk, and
read it back in. The data for weight °h
solids were still in the right places.
-246-
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MEMORANDUM - Trip Report
5 January 1973
Page 3
Evidently, Bechtel personnel are
looking in the wrong places on the
data tape. I will have Linda Parker
(who wrote the tape dump program) call
Bechtel to get this straightened out.
3) I changed the final report program,
FMAIN, to print up to 99 copies of the
final report.
4) I put in all the default values they had
requested, still leaving the option of
putting values on the cards instead of
using the default values.
5) I changed the LISTS system command to
print sample point numbers.
6) The message that all analyses were not
complete came from the fact that an extra
X-ray analysis was done that hadn’t been
scheduled. I corrected FRPRT and DPSTS to
check to see that the analyses scheduled
had been done.
-247-
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MEMORANDUM - Trip Report
5 January 1973
Page 4
7) I changed the DIJMPT command to dump data
packets to mag tape so that all the data
packets could be dumped using one command.
8) I cleaned up the NXSAN command. It was
overflowing a format and printing S1**X
for sample ID’s for ID’s greater than 100.
9) I cleaned up the LSTDP command. In creating
a data packet, the operator ID section of
the data packet was being used to store
some other data. This caused a format
overflow in LSTDP when operator ID’s were
printed (*1).
10) I added a new system command, READK to
read sample analysis data card images
from the keyboard of the teletype or CRT.
I emphasized that this was only to be
used in case the card reader was broken
or for corrections.
I explained all these changes to Joe Barkley, Mickey
Martin, and Bob Bell, another shift supervisor. They all seemed
to be pleased and said that these changes would help greatly
in using the system.
-248-
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MEMORANDUM - TRIP REPORT
5 January 1973
Page 5
A Data General field service man came by the plant
one day to check on the equipment. He was impressed that it
was as clean as it was. I noted that the card reader and
Beehive CRT were occasionally giving problems.
Distribution: DMC, PSL, MAN, LMP, KS, DM0
-249-
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15 February 1973 (Revised for Final Relort)
MEMORANDUM
TO: F. Scott LaGrone
FROM: C. T. Shelton
SUBJECT: Trip Report, Shawnee Steam Plant, 15 January 1973
Joe Barkley requested that I come to Paducah again.
They were having trouble with the X-ray calibration, the aqueous
CO 2 calculations, and the line printer. They also wanted several
default values put into the program. I suggested a way to take
care of the calibration problem, but they could not seem to get
it to work. I also suggested that since the aqueous CO 2 program
had been working and just quit working, the wrong tape with an
old version had been loaded, but Joe felt sure it hadn’t been.
From Joe’s description of the line printer problem, I was fairly
certain that there was a hardware problem either in the interface
or in the printer itself.
I arrived in Paducah Monday afternoon, January 15, and
by that evening had fixed the X-ray problem, determined that the
aqueous CO 2 was correct, isolated the line printer problem to
the printer itself, and put in all the default values requested.
The graveyard shift then set about to try out the changes. All
of the changes worked.
Joe Barkley wanted two new computation schemes added
to the system. I added a new command to the system, DUSTA,
-250-
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MEMORANDUM - Trip report
15 February 1973
Page 2
to implement dust analysis calculations. I also added a system
command, WETSO, to make wet SO 2 analysis calculations that Joe
requested. Shawnee personnel tried out the new commands and
seemed pleased that the dust analysis and wet SO 2 calculations
process would be greatly speeded up.
The Data General service man came Wednesday to fix
the line printer. When that is fixed, the whole system will
be in good shape, including the CRT. Apparently, there are
still a few problems with the card reader so I asked Gerald
Wood to get Nathan Burns, the instrument mechanic, to tune it
up.
The additions to the system included putting the
results into the data packet so they would be dumped to mag
tape with the rest of the data for Bechtel. I will contact
John Jacobs at Bechtel to tell him what and where these data
are.
Linda Parker and I finally determined that the data
for weight °L solids that Bechtel could not find on the tape
actually had been there all the time, but that Bechtel had been
having difficulty interpreting them. Linda and I interpreted it
for them so that Bechtel can now process these data.
Distribution: PSL, KS, MAM, LMP, JLP, DM0
-251-
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New dc’fault values have been added for the following
station codes and variables:
Sta. Code
11-15 Ui instrument readings Average of U can be
put in for U - commas
for U 2 & U 3
16 Cs cone of standard soin 4.0
16 Ui instrument readings Average of Ui’s for U 1 ,
commas for U 2 & U 3
17 Cs conc of standard soin 0.4
17 Ui instrument readings Average of Ui’s for U 1 ,
commas for U 2 & U 3
18-22 Ui instrument readings Average of Ui’s for U 1 ,
commas for U 2 & U 3
25 F wt of fixing soin 0.0
26 Wi wt of container 0.0
V 2 wt of container + sample 0.05
28 Wi wt of container 0.0
W 2 wt of sample + container 0.1
-252-
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DUSTA
This system command implements the dust analysis com-
putations. The system responds to the command by typing “TYPE
IN SANPLE ID”. To terminate the command, type in an up-arrow
(‘T’) in response to this question, otherwise, type the sample
identification, for example, SO12X. If the sample ID is in-
correct, a question mark is typed out and the question is
repeated. “TCA(l), HF(2), OR VENT(3)?” A 1, 2, or 3 followed
by a carriage return should be typed in. “INLET (1) OR OUTLET(2)?”
is asked next. A 1 or 2 should be typed in. The next question
is “NO. OF SANPLES=”. A carriage return may be typed in so
that the default value of 12 will be used. Otherwise, the
number of samples followed by a decimal point should be typed
in followed by a carriage return, e.g., NO. OF SANPLES = 6.
Next the system asks for the barometric pressure at the orifice
meter. “PBAR”. The pressure in inches of mercury should be
typed in followed by a carriage return. The system asks for the
total amount of particulate matter collected: “MN”. This
amount in milligrams should be typed in followed by a carriage
return. The volume of ga s sample through the meter will be
asked for: “VM(l)”. The number in parentheses is the sample
number. The volume in cubic feet should be typed in followed
by a carriage return. Next the average dry gas temperature is
requested: “TM(l)=”. The temperature in degrees Farenheit
should be typed in followed by a carriage return. Next the
pressure drop across the orifice meter is asked for: “DH(l)”.
The i H in inches of water should be typed in followed by a
carriage return. VM(2) is asked for next and so on until VM,
TM, and DH are typed in for all samples. The grain loading in
grains/scf is then typed out: “Cs = 10.5678 GR/SCF”.
-253-
-------
This data is put into the data packet in location XDTA
(474) and is printed on the final report.
NOTE: All input numbers must contain a decimal point. No
checking is done on the ranges of the input or calculated
variables.
-254-
-------
WETSO
This system command implements the wet SO 2 calculations.
The system responds to the command by typing: “TYPE IN SAMPLE
ID”. To terminate the command, type in an up-arrow (1), other-
wise, type in a sample identification. If the sample ID is
incorrect, a question mark is typed out. The system asks for
the scrubber type: “TCA(l), HF(2), or VENT(3)?” A 1, 2, or 3
should be typed in. Then the system asks “INLET(l) OR OUTLET(2)?”
A I or 2 should be typed in. The control room reading is asked
for: “CONTROL ROOM S0 2 =”. The control room reading in ppm
with a decimal point should be typed in followed by a carriage
return. Next the time is requested: “TIME=”. The time followed
by a decimal point should be typed in. The volume should be
typed in followed by a carriage return after the volume is asked
for: “V=”. Next the temperature is requested: “T”. The
temperature in degrees Centigrade should be typed followed by
a carriage return. The system then asks for the number of milli-
liters of basic solution used: “NL=”. This amount followed by
a carriage return should be typed in. Then the normality of
the basic solution is asked for: “N”. The normality should
be typed in followed by a carriage return. The system then
prints out the SO 2 in ppm. “SO 2 = 1234. PPM”. The system then
asks for another sample ID.
NOTE: All input data should contain a decimal point. No checks
are made of the ranges of the input variables. The SO 2 ppm is
stored in the data packet in XDTA(475) and is printed on the
final report.
-255-
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Operational Changes 1/17/73
1. Default values were added for station codes 11-15,16,17,
18-22,25,26, and 26.
2. System commands were added to implement dust analysis (DUSTA)
and wet SO 2 calculations (WETSO).
-256-
-------
NEW VALUES ADDED TO DATA PACKET AND MAC TAPE
Value Type_Variable Data Packet Word
1. Time SO 2 reading Integer 56
was made
2. Dust-scrubber, Integer 57
inlet lout let
flags
3. S0 2 -scrubber, Integer 58 225-228
inlet/outlet
f lags
4. Dust grain loading SPFP 947-948
5. SO 2 lab concen-
tration SPFP 949-950
6. SO 2 control room Integer 951
concentration
SPFP = Single Precision Floating Point
1. Time SO 2 reading was made in an integer from 0000 hours to
2359 hours.
2. Dust Analysis flags - integer formed in the following way:
Scrubber flag *10 + inlet/outlet flag
where
Scrubber flag Scrubber
1 TCA
2 HF
3 VENT
Inlet/Outlet flag Meaning
1 INLET
2 OUTLET
Mag Tape Byte
217-220
221-224
2189-2 192
2193-2 196
2197-2198
-257-
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15 March 1973 Radian Project No. 200-014
(Revised for Final Report)
MEMORANDUM
TO: F. S. LaGrone
FROM: C. T. Shelton
SUBJECT: Trip Report, Shawnee Steam Plant, 1 March 1973
Joe Barkley and Julian Jones requested that I go to
Shawnee Steam Plant to make some additions to the Laboratory
analysis system and to aid in determining the problems with
the X-ray unit. I went to Paducah on March 1 to be there at
the same time that the Siemens man was there in order to help
in determining where the X-ray problems were. The Siemens man
was there working on the X-ray unit when I arrived. The computer
system was down when I got there.
The Disk Operating System would not boot from disk,
only from mag tape, and not always from tape. The DEPOSIT
NEXT switch sometimes caused the computer to start running
when it was halted. The PROGRAM LOAD did not function
properly with the disk. I ran several of the hardware
tests to localize the problems to the above mentioned. I tried
to make the ion imbalance additions requested, but the system
always bombed out before I could get it done. Friday, I talked
to the Data General man and explained the problems. He said
he would be there Monday to work on the system. I arranged for
Mike McAnally or myself to come back the week of March 5-9 when
the computer was fixed in order to make the requested ion im-
balance additions.
Distribution: PSL, KS, MAN, LMP, JLP, DM0
-258-
-------
15 March 1973 Radian Project No. 200-014
(Revised for Final Ret,ort)
MEMORANDUM
TO: F. S. LaGrone
FROM: C. T. Shelton
SUBJECT: Trip Report, Shawnee Steam Plant, 9 March 1973
I returned to Paducah March 9 to make the changes
requested the week before. I implemented the ion imbalance
equations given on the attached sheet. The computer system
had been repaired and was working properly. I was there for
a short time and didn’t see Joe Barkley, so I left him a
No changes in the operating procedure were required.
The calculation is automatically done when a final report is
requested with the FRPRT command.
Distribution: PSL, KS, MAN, LMP, JLP, DM0
-259-
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PROCEDURE FOR SOLIDS IONIC IMBALANCE CALCULATION
Let the weight percentage of (1) CaO, (2) MgO, (3) CC 2 ,
and (4) total S expressed as SO 3 be stored as W , i CaO, NgO,
CO 2 and SO 3 . Let the molecular (formula) weights of these same
species be stored in the same order in MW 1 . From this, the
relative sums of positive and negative charges may be calculated
as Equations 1 and 2, respectively.
C = WCaO/MWCaO + WMgO/MWMg0 (1)
CN = W 0 /NW + W 0 /NW (2)
2 2 3 3
Any of a number of methods may be used to express the
relative charge imbalance, I. An arithmetic average may be
taken either with respect to the relative po.sitive charge or
with respect to the sum of the positive and negative charges,
as in Equations 3 and 4.
I = (Cp_CN)/Cp (3)
I = 2 (Cp_CN)/(Cp+CN) (4)
-260-
-------
10.4 APPENDIX D
TEST DATA FROM WINDSOR PILOT STUDIES
-26 1-
-------
10.4.1 TEST DATA FROM LINE SLURRY SCRUBBING RUNS
10.4.1.1 CHEMICAL ANALYSES
TABLE 10.4-1 LIQUID PHASE ANALYTICAL RESULTS
CE RUN 17R
TABLE 10.4-2 SOLID PHASE ANALYTICAL RESULTS
CE TEST NO. 17R
TABLE 10.4-3 LIQUID PHASE ANALYTICAL RESULTS
CE RUN 18R
TABLE 10.4-4 SOLID PHASE ANALYTICAL RESULTS
CE EXPERIMENT 18R
TABLE 10.4-5 RESULTS OF LIQUID PHASE ANALYSES
CE EXPERIMENT 19R
TABLE 10.4-6 RESULTS OF SOLID PHASE ANALYSES
CE EXPERIMENT 19R
TABLE 10.4-7 RESULTS OF LIQUID PHASE ANALYSES
CE EXPERIMENT 2OR
TABLE 10.4-8 RESULTS OF SOLID PHASE ANALYSES
CE EXPERIMENT 20R
TABLE 10.4-9 RESULTS OF LIQUID PHASE ANALYSES
CE EXPERIMENT 21R
TABLE 10.4-10 RESULTS OF SOLID PHASE ANALYSES
CE EXPERIMENT 21R
-262-
-------
RESULTS OF LIQUID PHASE ANALYSES
EXPERIMENT LA, 7 July 1972
RESULTS OF LIQUID PHASE ANALYSES
EXPERIMENT 2A, 10 July 1972
RESULTS OF LIQUID PHASE ANALYSES
7 July 1972 - RUN 3A
RESULTS OF LIQUID PHASE LANALYSES
11 July 1972 - RUN lB
RESULTS OF LIQUID PHASE ANALYSES
13 July 1972 - RUN 2B
TABLE 10.4-11 RESULTS OF LIQUID PHASE ANALYSES
CE EXPERIMENT 22R
TABLE 10.4-12 RESULTS OF SOLID PHASE ANALYSES
CE EXPERIMENT 22R
10.4.1.2 RELATIVE SUPERSATURATIONS
TABLE 10.4-13 RELATIVE SUPERSATURATIONS
CE SLURRY TESTS SERIES
TABLE 10.4-14 AMOUNT OF SEED IN SLURRY
10.4.2 TEST DATA FROM LIMESTONE SLURRY SCRUBBING RUNS
10.4.2.1 CHEMICAL ANALYSES
TABLE 10.4-15
TABLE 10.4-16
TABLE 10.4-17
TABLE 10.4-18
TABLE 10.4-19
-263-
-------
TABLE 10.4-20 RESULTS OF LIQUID PHASE ANALYSES
14 July 1972 - RUN 3B
TABLE 10.4-21 RESULTS OF SOLID PHASE ANALYSES
EXPERIMENT 1A, 7 July 1972
TABLE 10.4-22 RESULTS OF SOLID PHASE ANALYSES
EXPERIMENT 2A, 10 July 1972
TABLE 10.4-23 RESULTS OF SOLID PHASE ANALYSES
7 July 1972 - RUN 3A
TABLE 10.4-24 RESULTS OF SOLID PHASE ANALYSES
11 July 1972 - RUN lB
TABLE 10.4-25 RESULTS OF SOLID PHASE ANALYSES
13 July 1972 - RUN 2B
TABLE 10.4.26 RESULTS OF SOLID PHASE ANALYSES
14 July 1972 - RUN 3B
10.4.2.2 RELATIVE SUPERSATURATIONS
TABLE 10.4-27 RELATIVE SUPERSATURATIONS
CE SLURRY TEST SERIES
-264-
-------
TABLE 10.4-1
- LIQUID PHASE ANALYTICAL RESULTS, CE RUN hR
Concentrations in Millimoles/Liter
Total p 1 1
S0 C l N low/high
Temp. 7. Ion
.C&1 Imbalance
Water Make Up
Scn.b er Liquid “Dr 1
Scx-.ibber Liquid “T” 2
ScruQber Liquid “T” 3
Scrubber Bottom “T” 1
Scrubber Barton “T” 2
Scnibner Sott a ‘“1” 3
held Tank Effluent
12/15/71
12/15/71
12/15/71
12/15/71
12/15/71
12/15/71
12/15/71
12/15/71
14.25
13.9
13.6
1.62
1.42
1.47
0.88
0.78 0.87
3.78 0.77 5.75
5.75
5.75
4.48 11.65
11.60
11.60
3.88 0.80 10.85
e ___I —
Set I a
Total
Date Ca Mg Na S
1.08 0.33 0.49
29.7 0.32 1.14 1.04 35.5
29.9 1.12 34.7
29.6 34.5
27.8 0.003 1.08 0.18 18.0
18.6
17.5
22.85 0.03 1.09 0.04 18.5
C . ’
U,
0.20 0.76 1.10 22.2
25.5
0.27 12.9
0.01 0.74 0.13 10.3
S c I
:‘arble Bed Front
‘aroie Bed Back
SertD.3e” Bottos “5”
Spra;
Set 2
Scrubber Liquid “T” 1
Scr.bber Liquid “T” 2
Scru”ber Liquid “12” 3
Scr baer Botton “12” 1
Scnsbner Bottom “t’ 2
bald Tank Effluent
Yarblo Bed Front
Maroie 3ed Back
Ecn...aer Bottca s “5”
C1.r ..i er Bottom
F.lter Liquid
a:er Make Up
12/28/71
12/28/7 1
12/28/71
12/28/71
12/28/71
12/28/7 1
12/28/7 1
12/28/71
12/28/7 1
12/28/7 1
12/28/71
12/28/7 1
12/28/71
12/28/7 1
12/28/7 1
12/28/71
12/28/71
18.6
22.0
16.8
12.6
20.0
19.7
19.6
17.4
17.5
12.6
19.0
21.95
16.0
13.5
16.2
5.26
1.08
51.5
52.0
52.0
52.5
52.0
52.0
51.0
49.5
48.5
67.0
37.5
50. S
50.0
50.0
48.0
48.1
37.5
47.5
46.5
46.5
37.0
25.0
16.5
-3.5
-2.4
-2.6
-26.8
-22.2
-20.5
-1.0
—0.7/- 2.5
—1.2/-2 1
+3.01+0 .8
—5.3
—1 .9/— 2. 3
-0.7
—1 .4/— 1.9
+ 1 .41— 1 .2
.e.52/+29
+1.5
-+0.4/-0. 2
+0.8 1+0. 5
+5 .5/+3 .2
+3.9
+12.4
8.95
8.57
1.26
0.84
8.96
8.13
9.10
0.97
1.03
1.30
7.57
9.23
1.30
0.89
0.58
0.18
0.35 0.77
0.75
0.83
0.0]. 0.77
0.75
0.07 0.68
0.27 0.68
0.75
0.74
0.02 0.68
0.66
0.55
0.45
2.65 0.73
2.81 0.73
2.13
2.63
2.81
2.06
2.29
2.39
0.73
1.07
0.96 22.9
21.7
• 22.4
0.06 10.7
10.6
0.26 10.0
0.87 21.6
25.2
0.20 12.6
0.10 9.6
0.12 8.5
0.62 2.4
4.55/ 5.5
5.0 / 5.4
10.6 / 10.8
11.18
5.78/ 5.86
5.75
5.751 5.85
11.15/11.22
11.04/11.12
10. 75
4.52/ 5.08
4.45/ 4.75
9.9 /10.5
11.02
11.85
11.58
-------
TABLE 10.4-2 - SOLID PHASE ANALYTICAL RESULTS, CE TEST NO. 17R
Chemical Composition in Millizeole/Cram Solid
7. undissolved
Sa —p le Date Wt7. Solids Ca Mg Total S .jQt _cQa ( in .O4MMCI)
Set Ia
Scrubber Liquid “7” 1 12114/71 0.367 3.76 .493 0.907 0.49 0.323 53.4
Scrubber Liquid “7” 2 12/14/71 0.415 3.96 .491 0.938 0.69 0.316 53.0
Scrubber Liquid “T” 3 12/14/71 0.399 3.94 .504 0.923 0.45 0.399 53.2
Scrubber Bottom “1” 1 12/16/71 1.64 5.30 .443 1.12 0.82 0.430 43.9
Scrubber Bottom “T” 2 12/14/71 1.78 5.44 .419 0.907 0.65 0.398 43.6
Scrubber Bottom “T” 3 12/14/71 1.66 5.06 .432 1.02 0.71 0.401 45.6
Hold Tank Effluent 12/14/71 0.775 4.71 .412 2.445 1.92 0.513 38.7
Sct 1
Marble Bed Front 12/28/11 0.211 3.22 .522 0.869 0.80 0.220 51.3
Marble Bed Back 12/28/71 0.316
Scrubber Bottom “S” 12/28/11 1.02 5.68 .402 0.677 0.59 0.362 35.5
Spray 12/28/11 .0078
Set 2
Scrubber Liquid “7” 1 12/28/11 0.274 3.40 .448 0.939 0.52 0.227 49.6
Scrubber Liquid “T” 2 12/28/11 0.251 3.68 .488 1.002 0.55 0.236 53.7
Scrubber Liquid “7” 3 12/28/71 0.269 3.57 .506 0.914 0.49 0.224 51.7
Scrubber Bottom “7” 1 12/28/11 0.850 5.52 .430 1.012 0.88 0.566 41.9
Scrubber Bottom “T” 2 12/28/11 0.904 5 .59 .435 1.012 0.78 0.554 41.5
Hold Tank Effluent 12/28/11 0.327 4.57 .479 1.74 1.51 0.650 41.4
Marble Red Front 12/28171 0.163 3.28 .498 0.765 0.30 0.296 55.7
Marble Red Back 12/28/11 0.293
Scrubber Bottom “S’ 12/28/11 1.11 5.80 .416 0.692 0.50 0.511 61.2
Spray 12/28/11 0.0103
Clarifier Bpttom 12/28/11 11.1 3.87 .516 2.10 1.76 0.755 40.5
Filter Liquid 12/28/71 0.0139
filter Solid 12/28111 79.6 4.15 .868 0.538 0.65 0.595 40.5 ‘
-------
TABLE 10.4-3 - LIQUID PHASE ANALYTICAL RESULTS, CE RUN IBR
Concentrations in killimoles/Liter Temperature
&rrple Time Ca jg_ Total S pH 1°C )
Set 1
Scrubber Liquid: TI 5.57 20.5 3.34 1.08 21.7 3.07 6.33 6.15 46.5
2 6:09 21.1 3.54 1.08 23.3 4.69 6.20 47.8
3 6:21 20.3 3.34 1.12 21.6 3.16 6.60 48.0
Scrubber Bottonis: TI 6:05 33.4 1.12 18.4 1.08 6.91 11.5 48.0
2 6:15 33.5 1.10 18.1 1.04 11.4 48.0
6:27 32.6 1.11 18.4 1.17 11.4 47.8
Clarifier Liquid 6:33 20.9 0.93 16.95 0.57 3.91 11.05 37.5
Hold Tank Effluent 6:38 23.3 1.06 18.3 0.80 6.17 10.75 46.0
Marble Bed; Front 6:54 22.8 3.70 1.05 23.8 2.55 6.44 6,23 43.0
Back 1:05 24.4 3.60 1.10 26.9 7.43 5.75 45.0
Scrubber Bottoc s 5 7:13 25.7 1.14 18.15 0.74 6.89 10.6 47.0
Scrubber Spray 7:23 23.5 1.10 16.2 0.64 6.11 10.75 46.0
I ’ . )
0’ Set2
Scrubber Liquid: Ti 7:33 21.2 3.41 1.14 24.5 4.85 6.45 5.90 47.5
2 7:47 21.5 3 ,39 1.12 24.3 4.62 5.95
3 7:56 22.65 3.40 1.11 25.4 5.29 5.80 48.0
Scrubber Bottoms: Ti 7:39 34.3 1.13 18.5 0.97 7,15 11.45 47.5
2 7:51 35.55 1.16 18.55 0.86 11.50
3 8:01 32.7 1.13 18.9 5 34* 11.45
Clarifier Liquid 8:07 22.0 0.94 17.1 0.73 4.40 11.2 37.5
Mold Tank Effluent 8:11 23.9 1.11 19.0 1.31 6.28 10.6 46.0
Marble BedS Front 8:30 26.0 3.42 1.13 30.2 7.67 6.49 6.05 45.0
Back 8:22 24.7 3.40 1.11 27.4 5.14 6.0 45.0
Scrubber Bottoms S 8:40 25.5 1.17 19.5 0.92 10.45 47.0
Scrubber Spray 8:50 23.2 1.09 19.3 0.68 10.4 47.0
Water )akc-Up 0.40 0,69
* Probably an error.
-------
TABLE 10.4-4 - SOLID PHASE ANALYTICAL RESULTS, CE EXPERIMENT 18R
3 February 1912
Wt.7. Solids Composition in Millimoles/Gram weight 7.
Sample in Slurry Ca %_ Qa_ fl _ £9a_ Undissolved
Set 1
Scrubber Liquid: TI 4.45 4.50 0.34 2.26 0.87 0.58 34.6
2 4.46 4.57 0.34 2.27 0.83 0.55 32.1
3 5.28 4.60 0.34 2.18 0.86 0.50 34.8
Scrubber Bottoms: Ti 5.83 4.81 0.41 1.57 0.93 0.52 35.1
2 6.00 4.62 0.41 1.63 0.99 0.61 35.9
3 6.15 4.69 0.40 1.73 0.87 0.73 36.0
Clarifier Liquid .0 17
Hold Tank Effluent 4.50 4.47 0.40 2.22 0.86 0.63 34.1
Marble Bed: Front 4.17 4.56 0.31 2.31 1.02 0.59 33.3
Back 4.10 4.52 0.32 2.34 1.00 0.60 34.2
Scrubber Bottoms S 5.39 4.85 0.41 1.73 0.785 0.49 36.0
00
Scrubber Spray 3.67 4.59 0.41 2.11 0.84 0.58 34.9
Additive 5.97 0.50 0.06 0.45 0.39 46.3
Set 2
Scrubber Liquid: Tl 4.07 4.59 0.33 2.26 1.02 0.51 34.0
2 4.12 4.54 0.33 2.32 0.84 0.54 34.5
3 3.93 4.49 0.33 2.36 0.84 0.58 34.6
Scrubber Bottoms: Tl 5.26 4.80 0.41 1.68 0.73 0.62 36.3
2 5.61 4.85 0.41 1.67 0.75 0.63 36.5
3 5.79 4.64 0.41 1.89 0.17 0.63 36.3
Hold Tank Effluent 3.66 4.57 0.41 2.12 0.865 0.64 34.0
Marble Bed: Front 4.10 4.50 0.32 2.32 0.86 0.49 33.2
Back 3.91 4.54 0.32 2.36 0.83 0.52 34.6
Scrubber Bottoms 5 4.99 4.93 0.40 1.69 0.745 0.59 35.1
Scrubber Spray 3.35 4.47 0.40 2.20 0.88 0.54 34.6
Clarifier Bottoms 4.33 0.43 2.i3 0.85 0.54 35.3
-------
TABLE 10.4-5 - RESULTS OF LIQUID PHASE ANALYSES, CE EXPERIMENT 19R
Total Concentrations. mm dc per liter
Code T ern Total Charge
No. Sc—plc Des.g.ia iom. Date & Timne* °C pH Ce Mg N0 S Suri te Sulfame Carhonate Chloride Nitrote 1 lmbalencr
SET 1
79
80 Scrubber Liquid TIc 1 11:25 43.5 4.95 35.2 4.43 54.5 16.35 38.15 1.33 2.33 -97.
81
83 Scrubber Liquid TIc 2 11:37 43.0 5.00 35.3 4.56 53.8 28.6 25.2 -22
85 Scrubber Liquid TIc 3 11:45 43.6 5.00 35.3 4.53 54.6 28.55 25.05 -22
81
88 Scrubber Bottoms TIc 1 11:30 43.5 5.83 23.6 4.42 30.3 7.65 22.65 0.75 3.36 -37.
89
91 Scrubber Bottoms TIc 2 11:40 43.5 5.93 23.7 4.36 29.8 7.8 22.0 -22
93 Scrubber Bottoms TIc 3 11:52 44.0 5.90 24.2 4.37 31.1 8.35 22.75 -37.
95
96 Clarifier Liquid 11:57 23.5 5.30 22.5 3.41 29.1 6.0 23.1 0.24 2.00 —32
a
‘0
98
99 Hold Tank Effluent 12:00 39.0 5.43 24.5 4.30 36.3 15.7 20.6 1.10 2.10 -37.
1 CO
102
103 Marble Bed: Front 12:08 41.0 4.70 34.4 4.49 53.2 27.1 26.1. 1.86 2.32 -37.
104
Marble Bed: Back 12:15 41.5 4.50 34.4 4.52 53.4 26.6 26.8 1.83 -37.
109
110 Scrubber Bottoms 5 12:25 44.0 5.60 27.7 4.20 37.2 14.75 24.45 0.83 3.24 -57.
ill
113
114 Scrubber Spray 12:30 39.0 5.50 25.7 4.67 35.9 15.55 20.35 1.12 2.13 2 1
1 15
* Samples were taken on 20 April 1972
** Spot check showed Na concentration to be .w.40 txsnoles/s
Spot check showed NO 3 concentration to be es.25 ttmmolea/L
-------
TABLE 10.4-5 - RESULTS OF LIQUID PHASE ANALYSES, CE EXPERIMENT 19R (cant. ) Page 2
Total Concenirai,ons . in mole pet Irter
Code Temo. Total Chorge
S:— n Desçnct, Dote 6 Tune * ‘ ph Ca Mg Na S Suhfte Sulfate Carbonate Chloride NItrat* Imbalance
SET 2
117
115 Scrubber Liquid Tk 1 12:43 44.0 5.00 35.6 4.43 55.2 26.2 29.0 1.36 2.26 -47.
I L9
121 Scrubber Liquid Tk 2 12:50 44.0 5.05 35.5 4.46 53.3 28.0 25.3 -27.
123 Scrubber Liquid Tk 3 1:05 44.0 5.00 34.9 4.35 52.9 27.75 25.15 -27.
125
26 Scrubber Bottoms Tk 1 12:48 44.0 6.25 21.6 4.06 25.0 4.095 20.905 0.17 3.17
127
129 Scrubber Bottoms Tk 2 12:55 44.0 6.25 22.1 3.99 25.9 2.865 22.995 —17.
131 Scrubber Bottoms TIc 3 1:10 44.0 6.00 22.8 4.13 28.7 6.65 22.05 -27.
133
134 Clarifier. Liquid 1:15 23.5 5.60 22.6 3.45 28.8 5.95 22.85 0.22 2.03 -32.
135
136
137 Hold Tank Effluent 1:20 39.0 5.50 25.5 4.23 35.9 15.05 20.85 0.97 2.03 —27.
138
1L O
141 Marble Bed: Front 1:30 41.5 4.9 34.5 4.40 51.9 26.35 25.55 1.83 2.30
142
Marble Bed: Back 1:40 42.0 4.65 34.8 4.37 52.9 25.45 27.45 1.97 -37.
147
168 Scrubber Bottoms 5 1:45 44.0 5.6 27.6 4.24 37.3 13.65 23.65 0.83 3.25 -37.
149
151
152 Scrubber Spray 1:25 37.0 5.5 25.2 4.23 36.6 15.15 21.45 1.00 2.08 -37.
153
* Samples were taken on 20 April 1972
** Spot check showed Na concentration to be .40 olee/L
*** Spot check showed NO 3 concentration to be .25 aissolesll
-------
TABLE 10.4-6 - RESULTS OF SOLID PHASE ANALYSES, CE EXPERIMENT 19R
Total Concentrations, mmole per gram
Code Mt. % Solids Total 7. Undissolved
Sample Designation Date & Time * n Slurry s Calcium Magnesium Sulfite Sulfate Carbonate in 0.04 N HC1
SET 1
82 Scrubber Liquid Tk 1 11:25 1.22 1.96 3.30 0.224 1.32 0.64 0.175 53.07.
84 Scrubber Liquid Tk 2 11:37 1.22 1.90 3.31 0.222 1.29 0.61 0.166 50.27.
86 Scrubber Liquid Tk 3 11 45 1.23 1.95 3.45 0.228 1.34 0.61 0.177 50.57.
90 Scrubber Bottome Tk 1 11:30 2.61 2.06 4.10 0.329 1.57 0.49 0.271 44.57.
92 Scrubber Bottoms TIc 2 11:40 2.73 1.64 4.93 0.321 1.28 0.36 0.260 42.37.
96 Scrubber Bottoms Tk 3 11:52 3.28 1.88 4.53 0.330 1.52 0.36 0.237 45.1
101 Mold Tank Effluent 12:00 1.39 2.26 3.85 0.200 1.60 0.66 0.172 47.77.
105 Marble Bed: Front 12:08 1.50 1.83 3.68 0.244 1.24 0.59 0.171 51.17.
108 Marble Bed: Back 12:15 1.38 1.90 3.47 0.221 1.28 0.62 0.171 51.77.
117. Scrubber Bottoms S 12:25 3.21 1.53 4.88 0.341 1.47 0.06 0.280 45.17.
116 Scrubber Spray 12:30 1.14 2.21 3.73 0.197 1.62 0.59 0.215 45.67.
* Samples were taken on 20 April 1972
-------
TABLE 10.4-6 - RESULTS OF SOLID PHASE ANALYSES, CE EXPERIMENT 19R (cont. ) Page 2
Tetol Concentrotians, mmele per gram
Code Wt.%Sok,h Total 7. Undissolved
Sample Designation Dale & Time * in Slurr , s Calcium Magnesium Sulfite Sulfate Carbonate in 0.04 N HC1
SET 2
120 Scrubber Liquid Tk 1 12:43 1.2]. 1.85 3.39 0.240 1.22 0.63 0.161 51.17.
122 Scrubber Liquid Tk 2 12:50 1.35 1.84 3.52 0.243 1.23 0.61 0.209 51.97.
124 Scrubber Liquid Tk 3 1:05 1.34 1.77 3.50 0.235 1.15 0.62 0.201 50.57.
128 Scrubber Bo:toms Tk 1. 12:48 3.27 2.13 4.19 0.336 1.56 0.55 0.333 44.07.
130 Scrubber Bottoms Tk 2 12:55 3.54 1.85 4.72 0.334 1.37 0.48 0.349 42.07.
132 Scrubber Bottoms Tk 3 1:10 3.10 1.90 4.16 0.334 1.45 0.45 0.335 43.47.
1’) 139 Hold Tank Effluent 1:20 1.49 2.05 3.84 0.215 1.45 0.60 0.189 45.57.
143 Marble Bed: Front 1:30 1.67 1.66 3.98 0.265 1.18 0.48 0.198 48.67.
146 Marble Bed: Back 1:40 1.52 1.79 3.80 0.255 1.15 0.64 0.243 48.97.
150 Scrubber Bottoms S 1:45 4.19 1.42 5.01 0.350 1.33 0.09 0.402 42.47.
154 Scrubber Spray 1:25 1.46 2.01 4.01 0.224 1.41 0.60 0.180 45.47.
155 Fly Ash and Lime 0.45 5.81 0.500 0.455 45.87.
156 Fly Ash and Lime 0.54 5.78 0.498 47.67.
* Samples were taken on 20 April 1972
-------
TABLE 10.4-7 - RESULTS OF LIQUID PHASE ANALYSES. CE EXPERIMENT 20R
Tot tl Concentrations. mmole per liter
Code Tern . . Total Charge
Sample Designation Date & Time * C ’ pH Ca Mg Na** S Sulfite Sulfate Carbonate Chloride Nitrat * Imbalance
SET 1
I
2 Scrubber Liquid Tk 1 10:36 44.5 5.20 31.6 3.37 44.9 17.85 27.05 1.36 2.13 47.
3
5 Scrubbe: Liquid Tk 2 10:55 43.5 5.23 31.7 2.90 44.3 14.55 29.75
7 Scrubber Liquid Tk 3 11:05 44.0 5.20 31.4 3.31 0.38 44.7 14.6 30.1 -67.
9
10 Scrubber Bottoms 7k 1 10:48 45.0 11.23 21.1 3.30 19.7 1.08 18.6 0.06 3.11
11
13 Scrubber Bottoms Tk 2 11:00 45.3 10.82 24.3 21.3 1.03 20.3 47.
15 Scrubber Bottoms 7k 3 11:10 46.0 10.85 22.2 20.0 .93 19.1 27.
17
18 Clarifier Liquid 11:17 39.0 5.85 22.1 3.01 28.4 5.05 23.35 0.51 1.78 -47.
19
N .)
21
22 Hold Tank Effluent 11:25 40.0 5.75 23.6 3.24 0.38 31.9 7.45 24.45 0.95 2.03 -67.
23
25
26 Marble Bed: Front 11:40 42.5 4.7 32.0 3.44 0.40 44.9 14.75 30.15 1.49 2.23 -47.
27
Marble Bed: Back 11:50 42.0 4.53 32.5 3.59 46.5 15.25 31.25 1.69 -57.
32
33 Scrubber Bottoms S 12:00 44.0 5.93 26.1 3.32 33.4 8.1 25.3 1.38 3.01 -57.
34
37
38 Scrubber Spray 12:08 39.0 5.72 23.4 3.18 32.6 7.9 24.7 0.93 1.89 -77.
40
* Samples were taken on 21 April 1972
** Spot check showed Na concentration to be m.40 a o1es/L
Spot check showed NO 3 concentration to be m.25 amioles/1
-------
TABLE 10.4-7 - RESULTS OF LIQUID PHASE ANALYSES, CE EXPERIMENT 20R (cont. ) Page 2
Total Concentrationi. ‘a male per liter
Code Temp. • Total Cha ,ge
Somple Designation Date & Time * °C pH Ca Mg Na** S SulIit Sulfate Carbonate Chloride NutrotC***lmbalance
SET 2
43
44 Scrubber Liquid Tk 1 12:32 43.5 5.10 32.9 3.58 46.2 18.15 28.05 1.42 2.04 - 7.
45
47 Scrubber Liquid Tk 2 12:45 44.0 5.05 32.6 3.54 47.8 -87.
69 Scrubber Liquid Tk 3 1:00 44.5 5.05 34.0 3.78 48.5 18.4 30.1 -67.
50
51 Scrubber Bottons TIc 1 12:40 44.5 6.80 22.3 3.32 24.7 2.1 22.6 0.48 3.12 -1 2.
52
54 Scrubber Bottoms TIc 2 12:52 44.5 6.40 24.0 3.49 27.6 3.58 24.0 -27.
56 Scrubber Bottoms TIc 3 1:07 44.5 6.20 25.3 3.67 29.2 -17.
59
59 Clarifier. Liquid 1:20 39.0 5.80 22.9 3.28 28.7 7.4 20.9 0.57 1.95 -27.
60
61
62 Hold Tank Effluent 1:23 40.0 5.70 25.9 3.57 34.9 10.25 24.65 0.87 2.13
63
65
66 Marble Bed: Front 1:50 40.0 4.70 33.1 3.80 - 46.9 16.65 30.25 1.74 2.38 -47.
67
Marble Bed: Back 1:40 42.5 4.55 33.8 3.73 46.2 17.05 29.15 1.27 -27.
72
73 Scrubber Bottoms S 1:57 42.5 5.70 30.0 3.62 38.6 12.0 26.6 0.70 3.13 -37.
34
75
39 Scrubber Spray 1:30 44.5 5.87 26.6 35.7 10.2 25.5 0.98 2.03 47.
76
* Saples were taken on 21 April 1972
- - Spot check shoved Na concentration to be m.40 aeioles/L
*fr* Spot check shoved NO, concentration to be ‘e.25 uznole./1
-------
TABLE 10.4-8 - RESULTS OF SOLID PHASE ANALYSES, CE EXPERIMENT 20R
Total Concentrations. eimole per gram
Code Wt.% Solids Total 7. Undissolved
No. Sample Designation Datet Time * in Slurry s Calcium Magnesium Sullite Sulfate Carbonate In 0.06 N HCI
SET 1
4 Scrubber Liquid Tk 1 10:36 0.735 1.67 3.18 0.300 0.98 0.69 0.205 50.37.
6 Scrubber Liquid TIc 2 10:55 0.743 1.57 3.34 0.307 0.98 0.59 0.209 51.27.
8 Scrubber Liquid TIc 3 11:05 0.691 1.58 3.79 0.370 1.03 0.55 0.172 52.27.
12 Scrubber Bottoms TIc 1 10:48 2.67 1.72 4.61 0.483 1.37 0.35 0.384 40.87.
14 Scrubber Bottoms TIc 2 11:00 1.87 1.98 4.73 0.578 1.53 0.45 0.199 42.27.
16 Scrubber Bottoms TIc 3 11:10 2.27 1.83 4.61 0.482 1.51 0.32 0.327 44.17.
20 Clarifier Liquid 11:17 0.013 0.93
—4
24 Hold Tank Effluent 11:25 0.738 2.05 3.73 0.241 1.44 0.61 0.201 41.97.
28 Marble Bed: Front 11:40 0.983 1.53 3.67 0.315 1.05 0.48 0.210 51.4
31 Marble Bed: Back 11:50 0.868 1.47 3.40 0.290 0.97 0.50 0.150 54.1 %
36 Scrubber Bottoms S 12:00 2.53 1.36 4.87 0.364 1.20 0.16 0.249 44.37.
41 Scrubber Spray 12:08 0.694 2.00 3.77 0.251 1.42 0.58 0.181 48.8 %
• Samples were taken on 21 April 1972
-------
TABLE 10.4-8 - RESULTS OF SOLID PHASE ANALYSES, CE EXPERIMENT 20R (cont. ) Page 2
Totiti Concentr.tione .nmole per gram
Code Wt.%Sofld Total 7. Undissol .ved
Sar.ple Designation Dale & Time * its Slurry S Calcium Magnesium Sulfite Sulfate Carbonate in 0.04 N HC1
SET 2
46 Scrubber Liquid Tk 1 12:32 0.72 1.46 2.73 0.251 0.93 0.53 0.163 55.47.
48 Scrubber Liquid Tk 2 12:45 0.703 1.42 3.08 0.290 0.95 0.47 0.204 58.37.
49A Scrubber Liquid Th 3 1:00 0.697 1.41 4.46 0.366 0.94 0.47 0.138 58.87.
53 Scrubber Bottoms Tic 1 12:40 2.03 1.79 3.05 0.287 1.26 0.33 0.278 45.27.
55 Scrubber Bottoms Tic 2 12:50 2.06 1.73 4.53 0.367 1.44 0.29 0.310 45.27.
57 Scrubber Bottoms Tic 3 1:07 2.06 1.59 4.28 0.362 1.24 0.35 0.346 44.07.
64 Hold Tank Effluent 1:23 0.665 1.93 3.61 0.249 1.30 0.63 0.217 47.97.
—4
68 Marble Bed: Front 1:50 0.843 1.26 3.70 0.318 1.03 0.23 0.223 54.2
71 Marble Bed: Back 1:40 0.756 1.21 3.21 0.320 0.88 0.33 0.192 55.77.
74 Scrubber Bottoms S 1:57 2.26 1. .1 4.86 3.84 1.16 0.05 0.299 49.17.
77 Scrubber Spray 1:30 0.699 1.79 3.70 0.230 1.28 0.51 0.192 49.17.
* Saszples were taken on 21 April 1972
-------
TABLE 10.4-9 - RESULTS OF LIQUID PHASE ANALYSES, CE EXPERIMENT 21R
Total Concentrations ,rniole per liter
Co .le * Tema. Total Charge
Sompe Des,gneion Date & Tune C pH Ca Mg No S Sulfite Sulfate Carbonate Chloride Nitrate Imbalairc.
SET 1
157
158 Scrubber Liquid Tk 1 1:20 47.5 6.42 33.1 0.00 27.35 0.94 26.4 .18 9.19 1.47.
159
160 Scrubber Liquid Tk 2 1:32 46.0 5.92 17.5 15.6 1.11 32.40 5.05 27.4 -3.27.
161 Scrubber Liquid Tk 3 1:50 47.0 5.68 23.5 16.5 31.4 3.25 28.1 6.77.
l(’2
163 Scrubber Bottoms Tk 1 1:27 45.0 9.77 26.5 0.19 23.26 0.75 22.3 .23 10.7 -3.57.
164
165 Scrubber Bottoms Tk 2 1:38 45.9 9.82 24.3 0.43 21.56 0.80 20.8 -4.47.
166 Scrubber Bottoms Tk 3 1:55 66.0 9.70 22.2 3.23 22.90 1.15 21.7 -5.27.
167
N.) 168 Clarifier Liquid 2:00 29.0 9.85 19.4 4.30 23.16 0.85 21.3 .30 3.94 -0.67.
168A
169
170 Hold Tank Effluent 2:05 45.0 8.52 18.1 11.7 1.06 27.76 1.10 26.7 .28 8.84 0.3 3.37.
171
173
174 Marble Bed: Front 2:22 44.0 5.69 23.6 16.8 34.46 6.70 27.8 1.98 9.22 4.17.
175
Marble Bed: Back 2:30 46.0 5.48 22.6 16.0 41.16 7.60 33.6 1.94 -6.67.
180
181 Scrubber Bottoms S 2:40 47.5 8.18 20.0 10.5 27.17 1.28 25.9 .34 10.3 -2.57.
182
183
164 Scrubber Spray 3:00 45.5 8.30 16.8 13.9 29.34 1.28 28.1 .23 8.70 -4.17.
185
* Samples taken on 4/26/72.
-------
TABLE 10.4-9 - RESULTS OF LIQUID PHASE ANALYSES, CE EXPERIMENT 21R (cont. ) Page 2
Tote! Cancert,ot,on , nimole per liter
Code Temp. • Total Charge
: o. Senrple Deuigna lion Dote & T,m O pH C. Mg Na S Sulfite Sulfate Carbonate Chloride N,t,ate Imbalance
SET 2
183
1S Scrubber Liquid Tk 1 3:28 47.3 5.37 19.2 17.2 38.92 6.98 31.9 1.42 9.00 -4.57.
150
191 Scrubber Liquid Tk 2 3:45 47.2 5.37 19.8 16.5 46.89 10.4 36.5 —11.57.
192 Scrubber Liquid Tk 3 4:05 47.5 5.34 20.5 18.2 40.20 5.45 34.7 -3.97.
193
194 Scrubber Bottows Tk 1 3:35 46.0 9.48 22.3 7.76 27.68 1.52 26.2 .19 10.3 -4.47.
195
196 Scrubber Boctons Tk 2 4:00 46.0 9.47 20.2 10.5 29.26 0.8 28.5 -3.77.
197 Scrubber Botcons Tk 3 4:10 47.0 9.35 20.8 11.1 29.60 1.3 28.3 -4.27.
198
199 Clarifier Liquid 4:18 29.9 9.9 17.6 4.72 21.76 0.98 20.8 .29 4.60 3.57.
2G0
201
202 Hold Tank Effluent 4:23 45.0 7.03 16.9 15.1 1.09 30.50 1.73 28.8 .30 8.73 .3 -3.67.
203
205
206 Marble Bed: Front 4:33 44.0 5.5 20.5 16.8 39.71 12.9 26.8 1.89 9.13 -2.17.
207
Marble Bed: Back 4:42 46.5 5.38 23.6 16.6 46.35 12.0 34.4 2.04
212
213 Scrubber 8otto s S 4:52 47.8 6.42 19.4 12.0 29.05 1.12 27.9 .52 10.0 .3.37.
214
215
216 Scrubber Spray 5:00 46.0 8.90 16.9 13.9 29.11 1.32 27.8 .15 8.56 3.67.
217
* Saples taken on 4/26/72.
-------
TABLE 10.4-10 -
RESULTS OF
Sample De gnat.on
Date & Time
Code
No -
SET 1
172 Hold Tank Effluent
176 Marble Bed: Front
179 Marble Bed: Back
186 Clarifier Botto ns
‘.0
SET 2
204
2C8
211
SOLID PHASE ANALYSES, CE EXPERIMENT 21R
Total Concentrations mmole per gram
Wt. % Sol,di Total
in Slurfy S Calcium Magnesium Sulfite Sulfate Carbonat.
8.02 3.53 4.37 .245 2.27 1.26 0.250
8.09 3.66 4.46 .216 2.26 1.20 0.235
9.10 3.65 4.50 .200 2.40 1.25 0.227
2.65 4.21 .295 1.66 0.99 0.394
6.67 3.20 4.11 .186 2.35 0.85 0.200
7.65 3.38 4.11 .184 2.28 1.10 0.241
7.83 3.35 4.51 .194 2.22 1.13 0.211
Hold Tank Effluent
Marble Bed: Front
Marble Bed: Back
7. Urtdissolved
in 0.04 S MCI
36.27.
36.77.
34. 77.
32.97.
35.97.
36.57.
36.07.
-------
TABLE 10.4-11 - RESULTS OF LIQUID PHASE ANALYSES, CE EXPERIMENT 22R
latal Conceniratlons mmole p., lii, ,
Code Temp. Total Charge
Sample De.ignatron Date & Trme* C pH Ca Mg Na S Sulfrte S lfo,e Carbana . Cl,lo,,de Nutiat, Imbalance
SET 1
219
220 Scrubber Liquid Tk 1 1:10 45.0 4.99 24.7 18.2 1.16 55.0 18.6 36.4 8.84 -7.27.
221
222 Scrubber Liquid Tk 2 1:25 45.0 4.94 23.6 17.9 50.93 20.4 30.53 -4.07.
723 Scrubber Liquid Tk 3 1:40 45.5 4.86 24.4 17.8 52.81 21.75 31.06 -4.37.
224
225 Scrubber Bottoms Tk 1 1:15 46.0 5.87 16.6 17.4 32.00 7.75 24.25 9.20 -0.47.
226
227 Scrt .bber Bottoms Th 2 1:35 45.5 5.62 17.0 17.4 32.68 8.4 24.28 - 1.07.
228 Scrubber Bottoms Tk 3 1:47 46.0 5.63 18.5 18.0 37.0 8.6 28.6 -2.07.
229
230 Clarifier Liquid 2:00 27.0 9.11 18.9 4.18 20.7 0.77 19.93 5.09 0.27.
231
232
233 Hold Tank Effluent 2:06 46.0 5.60 16.2 18.3 1.14 31.97 7.55 24.42 8.93 .3 1.97.
234
236
237 Marble Bed: Front 2:45 45.0 6.10 18.4 17.7 37.3 4.26 29.92 9.24
238
Marble Bed: Back 2:50 45.0 5.82 20.3 18.0 41.33 6.05 35.28
243
244 Scrubber Bottoms 5 2:25 44.0 8.60 17.9 17.6 33.04 1.36 31.68 8.89
245
246
247 Scrubber Spray 3:00 45.5 7.70 16.5 16.9 31.00 1.51 29.49 9.15
248
* S plea taken on 4/28/72.
-------
TABLE 10.4-11 - RESULTS OF LIQUID PHASE ANALYSES, CE EXPERIMENT 22R (cant. ) Page 2
Total Concentrat,ons mmole per liter
Code Temp. Total Charge
! o . Sample Designation Date S. Time C pH Ca Mg Na Sulfite Sulfate Carbonate Chloride Nitrate Imbalance
SET 2
249
250 Scrubber Liquid 7k 1 3:06 46.0 5.27 20.9 18.4 44.34 11.5 32.84 .79 9.30 -4.87.
251
252 Scrubber Liquid 7k 2 3:22 46.5 5.49 20.1 18.6 39.0 8.55 30.45 -1.57.
253 Scrubber Liquid 7k 3 3:35 46.0 5.25 22.2 18.6 45.85 11.2 34.65 -4.87.
254
255 Scrubber Bottoms 7k 1 3:16 46.5 6.50 19.7 13.6 31.27 1.62 29.63 1.38 9.92 -3.47.
256
257 Scrubber Bottoms 7k 2 3:30 46.5 6.55 18.9 15.4 32.84 1.89 30.95 -4.07.
258 Scrubber Bottoms 7k 3 3:40 46.5 6.35 18.0 17.5 33.0 2.55 30.45 -2.27.
2)9
260 Clarifier Liquid 3:52 28.0 8.88 18.6 5.20 23.30 0.75 22.55 .23. 5.58 -4.07.
261
262
623 Hold Tank Effluent 3:45 45.5 6.81 16.4 17.9 1.15 31.70 1.93 29.77 .65 9.56 .3 -2.37.
264
266
267 Marble Bed: Front 3:58 44.0 5.35 21.0 19.9 43.68 8.8 34.88 1.44 9.81 -4.17.
268
270
271 Scrubber Bottoms S 4:05 45.5 5.67 16.9 19.0 32.67 3.76 28.91 2.09 10.4 -0.37.
272
Marble Bed: Back 4:22 42.5 5.44 19.9 19.9 43.79 10.5 33.29 .90 4.97.
276 -
277 Scrubber Spray 4:15 45.0 6.05 16.8 19.8 34.0 4.88 29.12 .62 9.75 -0.77.
278
* S. p1es taken on 4/28/72.
-------
TABLE 10.4-12 - RESULTS OF SOLID PHASE ANALYSES, CE EXPERIMENT 22R
Total Concentrations. mmol, per gram
Code Wt.%Soiids Total 7. Undtssolved
No. Sample Desupiation Date & Turns us Slurry s Calcium Magnesium Sullute Sulfate Carbonat, in 0.04 N MC I
SET 1
235 Hold Tank Effluent 8.58 3.55 4.37 .190 2.32 1.23 0.205 35.37.
239 Marble Bed: Front 7.84 3.61 4.44 .200 2.35 1.26 0.196 35.77.
242 Marble Bed: Back 8.51 3.83 4.52 .188 2.52 1.31 0.243 35.17.
SET 2
269 Marble Bed: Front 9.18 3.75 4.44 .172 2.40 1.35 0.146 34.97.
N.)
275 Marble Bed: Back 9.82 3.85 4.53 .155 2.51 1.34 0.133 34.67.
279 Additive 0.50 6.09 .483 0.08 0.42 0.469 47.47.
-------
TABLE 10.4-13
RELATIVE SUPERSATURATIONS - CE SLURRY TEST SERIES
Temp. a . ‘K 2
Run Vessel pH Range ( °C) Ca S0 H 0’ sp aCa4 aSO=aHO/Ksp aCa aOH _ /Ks
17R Marble Bed: 1 4.5-5.5 49 2.1-5.2 .85-1.08 6.3x10’ 5 - 4.5x10’ 3
2 4.5—5.1 47 .7-2.1 .9 —1.07 2.9x10 15 - 5.4xl0 ’
Hold Tank: la 10.85 51 2.8 1.13 3.2x10 2
2 10.75 37.5 4.6 .5 1.9x10 3
18R Marble Bed: 1 5.75-6.2 44 4.8-7.8 1.16-1.20 8.9x10’ 3 - 5.6x10 12
2 6.0 45 7.4-11.4 1.28 2.7-3.4x10 2
Hold Tank: 1 10.75 46 2.7 1.16 1x10 2
2 10.6 46 4.4 1.18 5.3x10 3
19R Marble Bed: 1 4.5-4.7 41 3.1-5.0 1.85-1.9 2.3-5.3xl0’ 5
2 4.7-4.9 42 3.5-7.4 1.8 -2.6 4x10’ 5 - 1.4x10 4
Hold Tank: 1 5.43 39 9.9 1.28 7.8x10 14
2 5.5 39 11.4 1.24 1.1x10 3
20R Marble Bed: 1 4.5-4.7 42 1.7-2.4 2.13-2.17 2 .5-5.9x10 15
2 4.5-4.7 41 2.1-2.9 2.05-2.13 3.2-4.3xl0
Hold Tank: 1 5.75 40 7.8 1.39 3.8x10’ 3
2 5.7 40 10.4 1.51 3.3x10 13
-------
TABLE 10.4-13 - RELATIVE SUPERSATURATIONS - CE SLURRY TEST SERIES (cont.)
Temp.
Run Vessel pH Range ( °C) a ++a 0 ajj5 0 /K p aCa++aSOa O/KSp aCa++aOH _ /Ksp
21R Marble Bed: 1 5.5-5,7 45 3.9-5.6 1.39-1.61 2 .4-5.3x10 13
2 5.4-5.5 45 5.1-6.8 1.17-1.66 1.6-l.9xlO 3
Hold Tank: 1 8.52 45 2.95 1.25 2.1x10 7
2 7.03 45 3.8 1.17 2.0xl0’
22R Marble Bed: 1 5.8-6.1 45 5.0 1.21-1.45 8.5x10 3 - 3xl0 2
2 5.35-5.45 45 3.44.7 1.26-1.43 9.0-9.7x 10 14
Hold Tank: 1 5.6 46 4.0 .96 3.3x1O 3
2 6.81 45 3.7 1.11 7.0x10”
-------
TABLE 10.4-14
AMOUNT OF SEED IN SLURRY
(All values in weight percent)
Run Vessel Total Solids CaSO ½H 2 O CaSO 4 2H 2 0 Ca(OH) 2
17R Marble Bed: 1 .26 .03 .003 .04
2 .23 .009 .02 .04
Hold Tank: la .77 .19 .07 .10
2 .33 .06 .01 .05
18R Marble Bed: 1 4.13 .54 .93 .50
2 4.00 .44 1.0 .50
Hold Tank: 1 4.50 .50 1.05 .54
2 3.66 .41 .80 - .49
19R Marble Bed: 1 1.44 .23 .15 .16
2 1.59 .25 .15 .23
Hold Tank: 1 1.39 .29 .16 .15
2 1.49 .28 .15 .18
20R Marble Bed: 1 .93 .12 .08 .13
2 .80 .10 .04 .12
Hold Tank: 1 .74 .14 .08 .08
2 .66 .11 .07 .07
21R Marble Bed: 1 8.60 2.6 1.8 .45
2 7.74 2.25 1.5 .41
Hold Tank: 1 8.02 2.35 1.7 .35
2 6.67 2.0 .98 .35
22R Marble Bed: 1 8.17 2.6 1.8 .31
-2 9.50 3.0 2.2 .39
Hold Tank: 1 8.58 2.6 1.8 .39
-------
TABLE 10.4-15 - RESULTS OF LIQUID PHASE ANALYSES, EXPERIMENT 1A, 7 July 1972
Total Cartcentrat,ons. mmole per liter 7
Code Temo. Total Chcrge
S:—ple Designation Dote & Tune ‘C pH Ca Mg Na S Sulfite Sulfate Carbonate Chloride Nitrate l,,bclance
szT 1
SLT1 9:25 49.2 5.39 23.1 3.92 0.86 31.0 8.65 22.4 7.02 1.28 0.5 -2.1
SLT2 9:32 49.4 5.40 24.2 3.9]. 0.86 34.4 11.4 22.9 7.20 1.32 0.5 -3.6
SLT3 9:40 49.0 5.48 25.7 4.00 0.86 35.3 8.13 1.35 0.5
SBT1 9:27 48.0 5.71 22.6 3.93 0.89 29.1 7.51 21.6 6.55 1.40 0.5 -2.0
S3T2 9:37 L8.1 5.70 21.8 3.82 0.88 28.6 6.62 21.9 6.83 1.47 0.5 -3.2
SBT3 9:45 48.9 5.64 21.8 4.00 0.88 29.1 7.41 21.7 6.43 1.42 0.5 -2.8
CLT 9:50 32.6 6.86 17.9 2.43 0.92 19.8 1.08 18.7 4.33 1.22 0.5 -3.3
HTE 9:53 48.0 6.05 19.4 3.86 0.86 23.5 2.65 20.8 6.63 1.33 0.5 2.6
333 XBB 10:07 47.4 5.28 27.7 4. e 0.88 42.6 22.6 20.0 3.0]. 1.30 --- -2.5
SB 10:15 48.2 5.27 26.9 3.92 0.89 40.4 23.8 16.6 3.49 1.34 0.5 -0.1
SS 10:20 47.7 6.10 19.1 3.80 0.88 23.0 3.04 20.0 7.77 1.29 0.5 -2.0
-------
TABLE 10.4-15 - RESULTS OF LIQUID PHASE ANALYSES, EXPERIMENT 1A, 7 July 1972 (cont. ) Page 2
Total Concentrations, mmole per liter 7
Code Temp. Total Charge
Scriple Designation Date & Time °C pH Ca Mg Na S Sulfite Sulfate Carbonate Chloride Nitrate Imbalance
SET 2
SLT1 10:30 49.5 5.51 23.8 3.98 0.86 33.4 10.7 22.7 7.12 1.50 0.5 —3.7
SLT2 10:38 50.0 5.51 25.3 4.00 0.86 33.9 10.7 23.3 7.97 1.41 0.5 —2.5
SLT3 10:50 49.8 5.54 24.3 4.33 0.85 32.8 9.92 22.9 7.85 1.29 0.5 . .2.6
SBT1 10:33 49.0 5.65 21.8 3.98 0.90 29.1 8.28 20.8 7.45 1.32 0.5 —2.5
S BT2 10:43 49.1 5.68 21.7 3.98 0.9 e 28.6 7.63 21.0 6.86 1.30 0.5 -2.4
S3T3 10:53 49.3 5.68 21.5 3.95 0.91 28.8 8.07 20.7 7.31 1.27 0.5 —2.8
CLT 10:56 33.9 6.81 17.6 2.45 0.95 19.5 1.12 18.4 5.34 1.24 0.5 -4.1
RTE 11:00 47.4 6.12 24.8 3.84 0.88 27.1 12.5 14.9 6.85 1.38 0.5 -3.2
11:15 48.5 5.31 30.2 3.97 0.91 44.3 18.9 25.4 3.98 1.22 0.5 -4.8
NBB 11:10 47.2 5.59 29.8 3.86 0.90 40.0 16.9 23.1 2.79 1.25 0.5 —1.0
SB 11:22 47.7 5.49 28.5 3.92 0.92 40.5 16.2 24.3 3.20 1.26 0.5 —3.1
SS 11:28 48.1 6.22 19.6 3.89 0.89 23.2 7.51 1.4]. 0.5
-------
TABLE 10.4-16 - RESULTS OF LIQUID PHASE ANALYSES, EXPERIMENT 2A, 10 July 1972
Total Concentrations, mmole per liter 7
Code Temp. To ta l Chcrge
Scmple Designction Date & Time ‘C pH Ca Mg Mo S Sul 4 ite Sulfate Carbonate Chloride Nitrate Irbolerce
s:T I
SLT I 13:45 49.0 5.29 24.5 3.55 0.87 33.4 12.4 21.0 5.79 1.39 0.5 -1.4
SLT Z 14:00 49.0 5.32 24.8 3.59 0.87 33.1 12.8 20.4 7.25 1.33 -0.5
SLT3 14:12 49.0 5.30 25.2 3.56 0.87 33.7 11.7 22.1 6.25 1.3]. -1.3
SBT1 13:55 48.5 5.33 23.2 3.59 0.88 30.7 9.42 21.3 5.98 1.34 —1.3
SBT Z 14:07 48.5 5.32 24.0 3.58 0.88 31.2 9.83 21.4 5.65 1.39 0.5 -0.4
4 :3 ssT3 14:15 49.0 5.32 25.4 4.03 0.89 37.0 5.45 1.38
CLT 14:25 31.0 7.19 17.5 1.84 0.98 18.7 0.74 18.0 3.39 1.14 0.5 -2.9
ICE 14:20 48.0 6.00 19.7 3.35 0.87 23.7 3.31 20.4 6.52 1.35 0.5 -2.9
21SF 14:35 48.0 4.97 30.7 3.56 0.89 44.3 21.8 22.5 3.80 1.35 -0.8
2188 14:45 48.0 5.13 28.5 3.52 0.88 39.9 15.8 24.1 3.09 1.30 0.5 -1.8
SS 14:55 47.0 5.97 21.5 3.45 0.87 25.1 3.73 21.4 5.67 1.37 -1.9
SB 14:50 48.5 5.32 27.5 3.54 0.88 36.3 17.0 19.3 3.41 1.33 1.5
-------
TABLE 10.4-16 - RESULTS OF LIQUID PHASE ANALYSES, EXPERIMENT 2A, 10 July 1972 (cont. ) Page 2
Total Concentrations, mmolo per liter 7
Code Temp. Total Charge
Sair.ple Designation Dote & Time °C pN Co Mg Na S Sulfite Sulfate Carbonate Clrlor.dc Nitrate lmbclønc.
SET 2
SLT1 15:05 49.0 5.35 24.8 3.50 . 0.85 33.8 13.0 20.8 6.78 1.32 —1.4
SLT2 15:15 49.0 5.33 25.3 3.53 0.87 34.2 12.3 21.9 6.76 1.30 0.5 -1.5
SLT3 15:25 49.0 5.49 25.9 3.58 0.87 35.4 12.6 22.9 5.90 1.27 -2.8
SBT I 15:10 48.5 5.34 31.4 3.56 0.88 38.5 10.5 28.1 5.40 1.25 -0.1
SBT2 15:20 48.5 5.37 24.9 3.56 O.88 33.7 10.9 22.7 5.32 1.22 0.5 —2.2
N.)
¼ SBT3 15:35 48.5 5.52 25.8 3.58 0.88 34.0 11.7 22.3 5.07 1.20 -1.4
CLT 15:42 31.5 7.15 17.7 1.95 0.97 19.0 0.76 18.2 4.26 1.12 0.5 —3.4
If E 15:47 47.0 6.07 20.5 3.38 0.85 24.0 3.36 20.6 5.65 1.19 0.5 -1.6
MBF 15:55 46.0 5.19 32.1 3.60 0.87 43.8 19.5 24.3 3.59 1.28 -0.4
16:02 47.0 5.24 29.4 3.52 0.88 42.4 18.6 23.8 3.93 1.18 -2.6
SS 16:10 47.0 5.29 22.5 3.56 0.87 24.6 6.16 1.21
SB 16:15 47.0 6.05 27.9 3.54 0.87 39.2 15.5 23.8 3.68 1.22 0.5 -6.4
-------
TABLE 10.4-17 - RESULTS OF LIQUID PHASE ANALYSES, 7 July 1972, RUN 3A
Total Concentrations mmole per liter
Code Temp. Total Chcrge
Scm?le.Deslgnation Dote & Time C pH Co Mg Na S Sulfite Sulfate Carbonate Chloride Nitrate lmbcI: ce 7.
S T I.
301
302 SLT1 10:45 50.5 5.44 22.31 3.21 0.69 30.49 18.17 12.82 6.62 1.39 0.3 1.3
304
305 SLT2 10:55 50.5 5.51 24.07 3.22 0.68 30.78 23.9 6.88 6.65 1.42 0.3 7.0
307
308 SLT3 11:06 — 5.56 21.28 3.25 0.69 28.53 22.6 5.93 6.30 1.50 0.3 - 5.7
310
311 SBT I 10:50 49.5 5.62 20.13 3.18 0.66 26.58 18.3 8.28 5.73 1.51 0.3 4.3
313
314 SBT2 11:02 50.0 5.54 21.36 3.22 0.69 28.81 20.7 8.1 6.67 1.46 0.3 4.3
316
317 S8T3 11:12 — 5.62 20.26 3.21 0.69 27.14 16.7 10.44 5.85 1.35 0.3 2.4
319
320 CLT 11:15 27.5 6.99 15.83 0.90 0.90 16.82 4.02 12.8 2.01 1.36 0.3 -3.0
321
322 HTE 11:20 49.0 6.05 17.94 3.11 0.69 21.67 6.57 15.1 6.56 1.39 0.3 1.4
324
325 1 . F1 11:30 - 5.31 25.85 3.29 0.70 37.60 45.6 - 1.48 1.43 0.3 2.4
327
328 11:42 — 5.29 24.67 3.32 0.72 34.82 21.0 13.82 2.14 1.38 0.3 2.3
330
331 SB 11:55 49.0 5.23 24.35 3.26 0.71 34.62 9.95 24.67 3.15 1.32 0.3 -5.0
334 SS 12:03 — 6.02 24.03 3.14 0.83 27.03 8.51 18.52 5.35 1.31 0.3 1.5
-------
TABLE 10.4-17 - RESULTS OF LIQUID PHASE ANALYSES, 7 July 1972, RUN 3A (cont. ) Page 2
Total Concentrationa, mmole per liter
Code Temp. Total Charge
P Sample Designation Date & Time ‘C pH Ca Mg Pla S Sulfite Sulfate Carbcnate Chloride Nitrate lr-bcio rce 7.
SET 2
336
SLT1 12:25 49.5 5.46 21.61 3.16 0.71 30.50 22.2 8.3 4.44 1.34 0.3 3.9
339
340 SLT2 12:35 49.2 5.44 21.82 3.26 0.70 30.41 21.0 9.41 5.83 1.29 0.3 3.7
342
SLT3 12:45 — 5.44 22.58 3.30 0.71. 31.97 19.7 12.27 5.18 1.30 0.3 1.6
345
S3T 1 12:30 49.0 5.59 22.11 3.20 0.71 28.82 17.8 11.02 5.28 1.26 0.3 3.7
348
SBT2 12:40 - 5.51 21.57 3.21 0.70 29.73 23.0 6.73 4.48 1.31 0.3 5.2
-‘ —9
351
SBT3 12:50 - 5.59 20.29 3.23 0.69 28.00 18.9 9.10 6.12 1.34 0.3 2.6
35.
CLT 12:55 28.0 6.96 15.98 0.96 0.91 17.00 6.98 10.02 2.12 1.15 0.3 -1.9
356
HTE 1:00 48.5 6.02 17.80 3.18 0.69 21.67 9.62 12.05 6.36 1.32 0.3 0.6
-------
TABLE 10.4-18 - RESULTS OF LIQUID PHASE ANALYSES, 11 July 1972, RUN lB
Total Concentrations. mmole per liter
Temj i. Total CFiar;e
Sample Designation Time pH Cc Mg Na S Sulfite Sulfate Carbonate Chloride Nitrate Imbalance
SET 1 SLTIA 2:45 PM 51.3 5.68 24.66 4.54 0.70 34.80 12.68 22.12 7.50 1.19 0.5 -3.4
SLT1B 2:50 PM 51.5 5.95 22.59 4.36 0.70 30.05 8.29 21.76 7.20 1.13 0.5 -3.8
SLT2A 2:58 PM 51.5 5.70 24.63 4.46 0.70 34.99 12.52 22.47 5.92 1.12 0.5 -3.7
SLT2B 3:02 PM 50.8 5.97 22.50 4.32 0.70 29.58 8.09 21.49 6.61 1.10 0.5 -3.3
SBTL 2:55 PM 50.0 5.92 23.11 4.48 0.68 31.60 8.85 22.75 5.79 1.16 0.5 -4.3
SBT2 3:04 PM 50.6 5.90 23.08 4.53 0.68 30.93 8.61 22.12 5.86 1.16 0.5 -3.2
CLT 3:09 PM 37.0 7.02 19.68 3.19 0.90 21.73 2.12 19.61 4.59 1.19 0.5 -2.3
HTE 3:12 PM 50.3 6.31 20.06 4.33 0.68 24.40 3.48 20.92 6.63 1.21 0.5 -3.2
MBF 1 3:45 PM 44.2 5.66 28.86 4.72 0.64 41.63 16.14 25.49 3.86 1.22 0.5 -4.2
MBF2 3:25 PM 46.6 5.76 27.22 4.53 0.65 36.55 11.40 25.15 2.85 1.24 0.5 -2.7
NBB1 3:55 PM 50.0 5.61 26.41 4.48 0.65 37.50 16.12 21.38 2.75 1.17 0.5 -2.0
SB 3:30 PM 50.5 5.67 26.95 4.55 0. 64 38.36 16.14 22.22 4.16 1.26 0.5 -2.8
SS 3:37 PM 50.0 6.42 21.80 4.51 0.62 25.16 3.98 21.18 7.66 1.20 0.5 -2.0
SET 2 SLT1A 4:00 PM 52.0 5.82 24.19 4.73 0.68 34.31 12.35 21.96 6.39 1.23 0.5 -4.0
SLT IB 4:06 PM 51.0 6.09 23.05 4.61 0.68 30.31 7.16 23.15 4.34 1.18 0.5 -2.8
SLT2A 4:15 PM 51.0 6.15 22.86 4.63 0.65 30.48 7.76 22.72 4.27 1.15 0.5 -4.2
SLT2B 4:20 PM 51.8 5.84 25.45 4.84 0.66 36.27 13.67 22.60 6.42 1.23 0.5 -4.2
SBT I 4:10PM 50.7 6.00 24.73 4.76 0.68 32.40 8.58 23.82 -- 1.26 0.5 --
SBT2 4:30 PM 51.0 6.00 23.14 4.74 0.64 32.33 9.53. 22.82 5.58 1.29 0.5 -5.1
CLT 4:36 PM 38.0 7.10 18.85 3.37 0.88 21.25 1.21. 20.04 4.57 1.22 0.5 -3.0
HTE 4:40 PM 50.8 5.45 19.80 4.63 0.72 24.54 3.27 21.27 6.07 1.25 0.5 0.4
MBF1 4:47 PM 46.0 5.89 28.23 4.82 0.70 40.29 18.88 21.41 2.91 1.28 -- -3.3
MBF2 5:12 PM 47.5 5.95 26.90 4.84 0.70 37.32 11.25 26.07 3.79 1.22 0.5 -4.8
NaB]. 4:55 PM 49.0 5.80 26.35 4.83 0.68 31.58 12.68 24.90 3.32 1.25 0.5 -4.4
SB 5:05 PM 50.8 5.79 25.73 4.90 0.64 38.21 15.68 22.53 3.68 1.29 0.5 -4.7
SS 5:20 PM 50.8 6.49 20.03 4.75 0.65 24.71 3.06 21.65 6.87 1.27 0.5 -4.1
-------
TABLE 10.4-19 - RESULTS OF LIQUID PHASE ANALYSES, 13 July 1972, RUN 2B
Total Cancentrations mmole per liter
Temp. Total Charge
Sample Designaton Time ph Ca Mg No Sulfite Sulfcte Carbonate Chloride Nitrate Imbelance
SET 1 SLTIA 10:55 AM 51.5 5.49 23.54 5.58 0.65 34.01 11.04 22.97 -- 1.36 0.5 --
SLT IB 11:00 AN 51.4 5.79 21.84 5.45 0.68 29.96 6.01 23.95 3.76 1.34 0.5 -2.9
SLT2A 11:09 AM 51.5 5.52 24.20 5.72 0.65 33.86 10.11 23.75 6.54 1.36 0.5 -1.7
SLT2B 11:15 .\N 51.6 5.79 22.14 5.57 0.65 30.17 6.07 24.10 3.72 1.31 0.5 -2.4
S STL 11:04 AN 51.3 5.49 22.84 5.76 0.65 33.46 9.20 24.26 4.77 1.35 0.5 -3.2
S T2 11:20 AM 51.4 5.49 23.68 5.84 0.65 33.06 9.88 23.18 4.97 1.36 0.5 -0.9
CLT 11:25 AM 35.5 6.80 18.28 3.67 0.82 21.52 0.88 20.64 3.69 1.20 0.5 -3.0
HTE 11:30 AM 51.2 6.04 19.40 5.67 0.66 25.44 4.03 21.41 4.91 1.36 0.5 -1.6
BF1 11:41 AN 46.0 5.36 26.66 5.84 0.66 39.06 15.32 23.74 3.65 1.36 0.5 -1.4
3F2 12:03 PM 45.5 5.81 23.97 5.84 0.68 32.43 5.81 26.62 4.34 1.34 0.5 -3.4
1l 55 AX 48.5 5.40 25.80 5.94 0,66 37.34 9.91 27.43 4.05 1.35 0.5 -3.2
SS 12:10 PM 50.5 6.02 19.60 5.89 0.66 25.11 3.58 21.53 5.80 1.36 0.5 -0.8
SB 11:45 AM 50.5 5.29 26.63 5.83 0.66 37.64 15.51 22.13 3.09 1.37 0.5 0.8
SET 2 SLTI.A 12:17 PM 51.0 5.50 22.90 6.04 0.67 33.21 10.48 22.73 6.01 1.36 0.5 -1.8
SLTLB 12:21 PM 50.8 5.68 22.26 6.01 0.68 32.07 7.52 24.55 4.26 1.35 0.5 -3.3
SLT2A 12:35 PM 50.8 5.49 23.13 6.16 0.67 33.84 10.36 23.48 6.42 1.36 0.5 -2.2
SLT2B 12.40 PM 51.0 5.71 21.94 6.11 0.67 30.32 9.35 20.97 4.13 1.37 0.5 -0.1
SBT I 12:30 PM 50.8 5.59 20.89 6.22 0.67 29.76 8.52 21.24 6.97 L36 0.5 -1.1
SBT2 12:47 PM 50.5 5.49 23.31 6.29 0.66 34.23 6.49 27.74 -- 1.41 0.5 --
CLT 12:52 PM 35.5 7.00 18.45 3.79 0.82 21.75 0.90 20. 3.81 1.21 0.5 -3.2
hTE 12:56 PM 50.4 6.03 18.91 6.13 0.70 25.35 3.5 21.85 5.38 1.36 0_s -1.9
XBF I 1:10 PM 43.0 5.59 25.85 6.25 0.70 37.35 12.87 24.48 3.75 1.33 0.5 -1.9
3F2 1:35 PM 46.0 5.68 23.85 6.13 0.70 32.98 6.50 26.48 3.34 1.35 0.5 -2.5
M381 1:18 PM 45.8 5.45 24.57 6.07 0.68 36.75 9.96 26.79 3.28 1.36 0.5 -4.1
SS 1:40 PM 50.0 6.10 19.22 6.23 0.66 25.30 3.34 21.96 5.40 1.37 0.5 -1.5
SB 1:30 PM 50.7 5.31 24.13 6.28 0.70 37.43 14.29 23.14 3.59 1.37 0.5 -2.4
-------
TABLE 10.4-20 - RESULTS OF LIQUID PHASE ANALYSES, 14 July 1972, RUN 3B
Total Concentrations, mmdc per liter 7
Temno. Total Chrçe
Scmnple Desmgnetion Time °C pH Cc Mg No S Sulfite Sulfate Carbonate C,lormde Nitrate hrbc’cnce
SET 1 SLTIA 9:55 AM 50.8 5.32 23.52 6.77 0.56 36.13 12.63 23.50 5.52 1.32 0.5 -2.0
SLTL3 9:58 AM 50.6 5.58 22.58 6.50 0.58 32.64 9.05 23.S9 3.84 1.33 0.5 -1.7
SLT2A 10:06 AM 50.6 5.40 23.62 6.57 0.60 36.09 12.37 23.72 5.37 1.35 0.5 -2.4
SLUR 10:10 AM 50.4 5.58 22.21 6.43 0.56 33.21 8.99 24.22 3.85 1.30 0.5 -3.2
SM !. 10:03 AM 50.0 5.31 24.27 6.72 0.60 36.98 11.74 25.24 3.58 1.37 0.5 -2.5
S BT2 10:22 AM 50.0 5.30 26.16 6.71 0.56 39.70 Lost -- 3.31. 1.31 0.5 --
CLT 10:23 AM 36.0 6.68 18.57 4.60 0.85 22.20 1.73 20.47 4.09 1.27 0.5 -1.7
f iTS 10:31 AM 50.0 5.91 18.53 6.45 0.56 26.46 4.40 22.06 4.77 1.33 0.5 -2.7
MEF I 10:38 AM 43.0 5.50 27.18 6.53 0.60 41.52 17.28 24.24 2.89 1.36 0.5 -2.5
M BF2 10:52 AM 47.0 5.60 24.09 6.62 0.55 34.48 8.04 26.44 2.52 1.31 0.5 -2.4
10:45 AM 49.3 5.09 26.59 6.92 0.tO 40.93 14.66 26.27 2.81 1.37 0.5 -2.0
55 11:05AM 50.0 5.90 18.78 6.86 0.55 26.52 4.18 22.34 5.91 1.37 0.5 -2.1
SB 10:58 AM 49.6 5.11. 26.92 6.89 0.52 42.21 18.26 23.95 2.92 1.34 0.5 -1.3
SET 2 SLT IA 11:20 AM 51.0 5.29 25.49 6.79 0.49 39.14 12.82 26.32 4.01 1.35 0.5 -3.0
SLT1 B 11:25 AM 50.5 5.48 23.48 6.70 0.45 34.73 10.69 24.04 3.94 1.35 0.5 -1.9
SLT2A 11:33 AM 50.8 5.30 24.02 6.99 0.45 37.46 15.23 22.23 5.70 1.35 0.5 -1.3
SLT2 R 11:36 AM 50.5 5.50 21.88 6.85 0.45 33.60 10.32 23.28 5.47 1.34 0.5 -2.5
SBT I 11:30AM 50.3 5.30 24.87 6.79 0.44 39.07 15.42 23.65 4.15 1.36 0.5 -2.3
SST2 11:40 AM 50.4 5.21 25.37 6.88 0.47 39.97 14.84 25.13 4.51 1.36 0.5 -2.7
CLT 11:45 AM 37.0 6.60 18.26 4.70 0.90 22.54 2.16 20.38 4.75 1.25 0.5 -2.9
fiTS 11:50 AM 50.0 5.80 18.91 6.92 0.47 26.80 4.89 21.91 5.28 1.36 0.5 -1.4
MBF1 12:00 PM 47.8 5.08 25.53 6.95 0.48 41.62 20.48 21.14 2.36 1.34 0.5 -0.9
N EP2 12:10 PM 47.0 5.49 24.43 6.78 0.50 35.06 9.70 25.36 3.08 1.34 0.5 -1.3
M 331 12:05 PM 49.9 5.02 27.63 7.03 0.48 43.70 17.09 26.61 3.10 1.34 0.5 -2.4
SB 12:18 PM 50.0 5.09 26.98 7.09 0.45 43.58 20.03 23.55 2.90 1.35 0.5 -6.2
55 12:27 PM 50.0 5.84 18.59 6.97 0.42 26.72 5.13 21.59 6.34 1.35 0.5 —2.0
-------
TABLE 10.4-21 - RESULTS OF SOLID PHASE ANALYSES, EXPERIMENT 1A, 7 July 1972
Total Concetitrotions, mmole per grcni
Code Wt.% Solids Total 7. Insoluble
Sample Dos.çnaton Date & Time n Slurt)’ S Calcium Magnesium Sulfite Sulfate Carbonate in 0.04 HCI
SET 1
361 SLT1 9:25 6.57 3.66 8.13 0.05 2.76 0.90 4.32 2.91
364 SLT2 9:32 6.75 4.22 7.88 0.05 3.24 0.98 3.43 2.04
367 SLT3 9:40 6.79 4.19 8.11 0.05 3.16 1.03 3.70 2.18
370 SBT I 9:27 4.94 5.10 7.94 0.04 4.07 1.03 2.72 1.60
373 SBT2 9:37 5.42 4.72 7.88 0.05 3.68 1.04 3.03 1.39
376 SBT3 9:45 7.46 3.76 8.02 0.06 2.83 0.93 3.92 2.40
3S1 hTE 9:53 7.43 3.60 8.13 0.06 2.65 0.95 4.36 2.70
3 54 3F 10 00 6.46 4.22 7.84 0.06 3.26 0.96 3.81 2.24
3S7 MBB 10:07 7.52 3.98 7.95 0.06 3.04 0.94 4.02 2.91
390 53 10:15 6.92 4.07 7.93 0.06 3.17 0.90 3.79 1.64
393 SS 10:20 7.18 3.57 8.08 0.07 2.70 0.87 4.54 3.16
SET 2
3 6 SLT1 10:30 6.84 3.98 7.96 0.06 3.02 0.96 3.93 2.1.0
399 5LT2 10:38 6.81 3.85 8.03 0.06 2.84 1.01 3.99 2.13
402 SLT3 10:50 6.77 3.90 8.00 0.06 2.96 0.94 4.09 1.85
405 SBT1 10:33 7.62 3.76 8.08 0.07 2.78 0.98 4.38 1.93
4 3 S3T2 10:43 7.38 3.59 8.09 0.07 2.75 0.84 4.29 2.2].
-.11 S3T3 10:53 7.43 3.80 8.00 0.06 2.83 0.97 4.19 2.22
416 lifE 11:00 7.38 3.49 8.07 0.06 2.62 0.87 4.65 2.28
413 3F 11:10 7.08 4.24 8.01 0.06 3.23 1.01 3.79 1.96
421 11:15 7.97 4.44 7.96 0.06 3.45 0.99 3.55 1.83
423 SB 11:22 7.49 3.69 8.12 0.06 2.76 0.93 4.50 2.72
426 SS 11:28 7.69 3.53 8.08 0.06 2.74 0.79 4.45 2.58
-------
TABLE 10.4-22 - RESULTS OF SOLID PHASE ANALYSES, EXPERIMENT 2A, 10 July 1972
Total Coecenivotians. mmols pr gram
Code Wt. % Solids Total 7. Insoluble
4:
Sample Designation Date & Time in Slurry S Calcium Maçnesium Sulfite Sulfate Corboncte in 0.04 HCI
SET 1
429 SLT]. 13:45 5.02 7.62 0.03 3.78 1.24 2.74 1.59
432 SLT2 14:00 5.01 7.82 0.04 3.74 1.27 2.91 1:55
435 SLT3 14:12 4.79 7.74 0.04 3.54 1.25 2.97 1.64
438 SBT1 13:55 5.07 7.64 0.04 3.85 1.22 2.81 1.47
441 SBT2 14:07 5.05 7.64 0.03 3.91 1.14 2.60 1.21
444 SBT3 14:15 4.64 7.80 0.04 3.52 1.12 3.17 1.60
449 HTE 14:20 4.59 7.83 0.04 3.39 1.20 3.23 1.80
452 14:35 5.02 7.72 0.04 3.76 1.26 2.75 1.53
455 MBB 14:45 5.26 7.67 0.03 4.02 1.24 2.57 1.43
458 SS 14:55 3.94 8.05 0.05 2.90 1.04 4.37 2.89
461 SB 14:50 4.53 7.92 0.04 3.40 1.03 3.40 2.08
SET 2
464 SLT1 15:05 4.52 7.64 0.05 3.34 1.18 3.26 1.95
457 SLT2 15:15 4.48 7.63 0.05 3.37 1.11 3.32 1.84
470 SLT3 15:25 6.24 4.61 7.75 0.05 3.45 1.16 3.33 1.72
473 SBT I 15:10 6.67 4.71 7.8]. 0.05 3.53 1.18 2.82 1.51
476 58T2 15:20 6.91 4.31 7.84 0.05 3.28 1.03 3.51 2.07
479 SBT3 15:35 5.44 4.12 7.86 0.06 3.08 1.04 3.82 2.35
484 HTE 15:47 6.43 4.12 7.71 0.06 3.14 0.98 3.61 1.93
487 15:55 7.54 4.31 7.69 0.06 3.29 1.02 3.40 1.97
490 B 16:02 6.65 4.45 7.60 0.05 3.38 1.07 3.38 1.95
493 SS 16:10 6.57 3.82 7.90 0.06 2.94 0.88 4.03 2.44
496 53 16:15 4.43 7.68 0.06 3.37 1.06 3.40 1.73
-------
TABLE 10.4-23 - RESULTS OF SOLID PHASE ANALYSES, 7 July 1972, RUN 3A
Total Concerflrat,ons, mmole per gram
Code Wt. % Solids Total 7. Insoluble
Sample Des,çnatioo Date & Time in Slurry S Calcium Magnesium Sulfite Sulfate Carbonate in 0.04 NHC1
SET 1
303 SLI1 10:45 7.18 4.60 7.18 0.034 3.50 1.10 2.73 1.97
306 SLT2 10:55 7.09 4.83 7.33 0.027 3.64 1.19 2.68 1.26
309 SLT3 11:06 7.10 4.78 7.35 0.028 3.57 1.21 2.70 1.70
312 SE n 10:50 7.77 4.37 7.46 0.032 3.14 1.23 3.02 2.27
315 SBT2 11:02 7.63 4.44 7.33 0.031 3.33 1.11 3.24 2.01
315 S3T3 11:12 7.83 4.46 7.36 0.031 3.33 1.13 3.00 2.27
323 HTE 11:20 7.79 4.28 7.46 0.032 3.21 1.07 3.24 2.18
326 Fl 11:30 7.32 4.64 7.22 0.029 3.50 1.14 2.73 1.90
329 > 1331 11:42 6.32 5.39 7.32 0.023 4.02 1.37 2.08 2.05
332 SB 11:55 7.90 4.61 7.40 0.030 3.42 1.19 2.94 2.07
335 SS 12:03 7.55 4.36 7.39 0.032 3.32 1.04 3.05 2.50
-------
TABLE 10.4-23 - RESULTS OF SOLID PHASE ANALYSES, 7 July 1972, RUN 3A (cont. ) Page 2
Total Concentrations. mmole per gram
Code W,. % Solids Total 7 Insoluble
Sample Designation Date & Time in Slurry S Calcium Magnesium Sulfite Sulfate Carbonate in 0.04 NHC1
SET 2
338 SLT I 12:25 6.96 4.78 7.23 0.028 3.70 1.08 2.75 1.85
341 SLT2 12:35 7.06 4.92 7.31 0.026 3.68 1.24 2.65 1.63
3A4 SLT3 12:45 7.09 4.86 7.39 0.027 3.71 1.15 2.66 1.71
347 SBT1 12:30 7.59 4.96 7.30 0.026 3.74 1.22 2.46 1.70
350 SBT2 12:40 7.58 4.44 7.55 0.030 3.33 1.11 2.99 2.28
353 SBT3 - 3A 12:50 6.71 4.61 7.58 0.028 3.46 1.15 2.99 2.10
CO 358 HTE — 3A 1:00 7.14 4.31 7.31 0.029 3.30 1.01 2.94 2.04
Additive I Run 2A 100 0.002 9.50 0.11 0 0.002 9.24 2.6
Additive 2 Run 2B 100 0.015 9.42 0.13 0 0.015 9.46 2.34
Additive 3 Run 3B 100 0.002 9.45 0.13 0 0.002 9.40 2.26
-------
TABLE 10.4-24 - RESULTS OF SOLID PHASE ANALYSES, 11 July 1972, RUN lB
Total Concentrations, mmole per gram 7
Wt. % Solids Insoluble
Sample Desugnasior. Tine in Slurry Total S Calcium Magnesium Sulfite Sulfate Carbonate in .04 HC1
SET 1 SLTIA 2:45 PM 6.00 4.19 7.84 0.06 3.16 1.03 3.63 2.32
SLT1B 2:50 PM 5.96 4.30 7.93 0.06 3.26 1.04 3.72 2.02
SLT2A 2:58 PM 6.07 6.28 7.79 0.06 3.22 1.06 3.66 1.90
SLT2B 3:02 PM 6.18 4.33 7.82 0.06 3.26 1.07 3.67 1.83
SIST1 2:55 PM 6.82 4.06 7.85 0.07 3.04 1.02 3.59 2.20
S3T2 3:04 PM 6.38 4.12 8.03 0.07 3.10 1.02 3.82 1.66
HTZ 3:12 PM 6.17 4.02 7.88 0.07 3.04 0.98 3.74 2.12
MRF ]. 3:45 PM 8.45 4.07 7.95 0.07 3.00 1.07 3.79 2.12
M SF2 3:25 PM 6.61 4.30 7.86 0.06 3.21 1.09 3.40 1.81
M613 1 3:55 PM 4.72 5.49 7.52 0.04 4.26 1.23 2.16 1.20
SB 3:30 PM 6.93 4.16 7.90 0.07 3.14 1.02 3.67 2.02
SS 3:37 PM 6.40 3.84 8.01 0.07 2.86 0.98 3.91 1.99
SET 2 SLTIA 4:00 PM 6.08 4.73 7.84 0.04 3.59 1.14 2.89 1.68
SLT IB 4:06 PM 6.05 4.45 7.81 0.05 3.29 1.16 3.25 1.88
SLT2A 4:15 PM 6.03 4.20 7.80 0.05 3.10 1.10 3.71 2.31
SLT2B 4:20 P]I 6.30 4.60 7.84 0.05 3.44 1.16 3.1’e 1.73
SoT ] . 4:10 PM 6.86 4.11 7.8]. 0.06 3.06 1.05 3.57 2.13
S3T2 4:30 PM 6.35 4.33 7.89 0.06 3.24 1.09 3.41 1.84
HIt 4:40 PM 6.47 4.06 7.77 0.06 3.01 1.05 3.90 1.97
MEFI 4:47 PM 6.61 4.18 7.76 0.06 3.11 1.07 3.53 1.96
MBF2 5:12 PM 6.13 5.07 7.67 0.04 3.90 1.17 2.88 1.02
XBB]. 4:55 PM 4.46 5.90 7.45 0.03 4.71 1.19 1.87 0.83
S3 5:05 PM 7.67 4.50 7.84 0.05 3.39 1.11 3.00 2.04
SS 5:20 PM 6.7]. 4.2]. 7.92 0.06 3.13 1.08 3.48 1.64
-------
TABLE 10.4-25 - RESULTS OF SOLID PHASE ANALYSES, 13 July 1972, RUN 2B
Total Concentrations. mmola per gram
Wt. % Solids Insolub le
Sample DesgaatFon Ti me in Slurry Total S Calcium Magnesium Sulfite Sulfate Carbonate in .04 11C1
SET 1 SLT1A 10:55 AN 6.82 4.70 7.75 0.05 3.40 1.30 3.04 1.67
SLT1B 11:00 AM 7.41 4.75 7.81 0.05 3.49 1.26 2.88 1.48
SLT2A 11:09 AN 7.60 4.80 7.70 0.05 3.45 1.35 2.96 1.54
SLT2B 11:15 AN 7.23 4.62 7.88 0.05 3.32 1.30 3.03 1.39
5571 11:04 AN 7.51 4.52 7.87 0.06 3.24 1.28 3.04 1.81
5 8T2 11:20 AN 7.68 4.61 7.74 0.06 3.33 1.28 3.04 1.70
HTE 11:30 AN 10.05 4.51 7.62 0.08 3.25 1.26 2.93 1.76
MBF1 11:41 AN 7.86 4.55 7.57 0.08 3.37 1.18 2.92 1.77
2$F2 12:03 PM 11.31 5.32 7.36 0.06 3.88 1.44 2.13 1.14
11:55 AN 6.18 6.09 7.19 0.05 4.54 1.55 1.32 0.66
SS 12:10 PM 8.41 4.53 7.55 0.07 3.27 1.26 2.90 1.83
SB 11:45 AM 7.09 4.80 7 54 0.06 3.45 1.35 2.73 1.49
0
SET 2 SLT1A 12:17 PM 7.55 5.20 7.46 0.07 3.66 1.54 2.43 1.34
SLT1 S 12:21 PM 8.63 4.68 7.63 0.07 3.32 1.36 2.77 1.66
SLT2A 12:35 PM 6.87 4.89 7.43 0.06 3.52 1.37 2.76 1.60
SLT2B 12:40 PM 7.75 4.83 7.52 0.07 3.41 1.42 2.73 1.65
5311 12:30 PM 9.15 4.68 7.57 0.07 3.33 1.35 2.93 1.82
5372 12:47 PM 11.40 4.63 7.50 0.07 3.33 1.30 2.78 1.68
ICE 12:56 PM 8.85 4.61 7.47 0.07 3.30 1.31 2.95 1.68
l 3F1 1:10 PM 8.99 4.68 7.46 0.06 3.32 1.36 2.97 1.79
I’BP2 1:35 PM 12.34 5.60 7.30 0.04 4.10 1.50 2.00 0.98
1:18 PM 6.87 6.05 7.22 0.03 4.50 1.55 1.34 0.76
55 1:40 PM 8.72 5.00 7.46 0.05 3.63 1.37 2.67 1.62
53 1:30 PM 9.17 5.07 7.43 0.05 3.58 1.49 2.40 1.42
ADDITIVE 2 RUN 2B 100 0.015 9.42 0.13 0 0.015 9.46 2.34
-------
TABLE 10.4-26 - RESULTS OF SOLID PHASE ANALYSES, 14 July 1972, RUN 3B
Total Concentrations, mmole per gram 7
Wt. % Solids Insoluble
Sample Designation Titue in Slurry Total S Calcium Magnesium Sulfite Sulfate Carbonate i i .04 HC1
s r 1 SLTI.A 9:55 AN 5.83 7.08 0.04 4.13 1.70 1.40 0.96
SLT IS 9:58 AN 5.58 7.10 0.06 3.93 1.65 1.6]. 1.45
SLT2A 10:06 AM 5.75 7.13 0.05 4.02 1.73 1.50 1.25
SLT2B 10:10 AM 5.76 7.08 0.05 4.06 1.70 1.57 1.25
SBT I 10:03 AN 5.55 7.15 0.05 3.88 1.67 1.77 1.51
S T2 10:22 AN 5.50 7.09 0.05 3.86 1.64 1.88 1.53
ti lL 1031 AN 5.63 7.16 0.05 3.94 1.69 1.82 1.46
10:38 AN 5.81 7.01 0.05 4.04 1.77 1.49 1.21
:1:2 10:52 AN 6.10 7.10 0.04 4.30 1.80 1.19 1.00
3B 10:45 AN 6.46 7.04 0.03 4.62 1.84 0.87 0.64
SS 11:05 AN 5.70 7.15 0.05 3.87 1.83 1.67 1.40
SB 10:58 AN 5.66 7.17 0.05 3.89 1.77 1.82 1.34
0
sET 2 SLT1A 11:20 AN 5.76 7.12 0.05 4.01 1.75 1.50 1.1.0
SLT13 11:25 AN 5.76 7.13 0.04 4.07 1.69 1.66 1.36
SLT2A 11:33 AN 5.86 7.06 0.04 4.03 1.83 1.43 1.28
SLT2B 11:36 AN 5.89 7.17 0.05 3.98 1.91 1.38 1.35-
sri:i. 11:30 AN 5.57 7.17 0.05 3.83 1.74 1.70 1.72
SBT2 11:40 AN 5.71 7 3 0.05 3.95 1.76 1.49 1.45
} iTE 11:50 AN 5.67 7.14 0.05 3.94 1.73 1.64 1.51
NM’ l 12:00 PM 5.88 7.10 0.05 4.06 1.82 1.27 1.26
MBF2 12:10 PM 6.12 7.03 0.05 4.25 1.87 1.33 0.99
12:05 PM 6.39 7.00 0.04 4.56 1.83 0.86 0.71
SB 12:18 PM 5.95 7.09 0.04 4.17 1.78 1.27 1.22
SS 12:27 PM 5.63 7.13 0.06 3.91 1.72 1.68 1.85
ADDITIVE 3 RUN 3B 100 0.002 9.45 0.13 0 0.002 9.40 2.26
-------
TABLE 10.4-27
RELATIVE SUPERSATURATIONS - CE SLURRY
TEST SERIES
Temp
!; pll ( °C )
CaSO 3 H 2 O CaS0 .2H Q
Run Vessel
IA Marb].e Bed
Ho].d Tank
2A MarbLe Bed
Hold Tank
3A Marble Bed
Hold Tank
lB Upper Marble Bed
Lower Marble Bed
Hold Tank
2B Upper Marble Bed
Lower Marble Bed
Hold Tank
3B Upper Marbl.e Bed
Lower Marble Bed
hold T.ink
2
5.59
47.2
14.0
1.41
0.039
1
6.05
48.0
3.5
1.09
0.41
2
6.12
47.4
2.0
0.87
0.62
1
4.97
48.0
5.9
1.45
0.043
2
5.19
46.0
8.6
1.57
0.010
1.
6.00
48.0
4.1
1.09
0.34
2
6.07
47.0
4.8
1.12
0.37
1
5.29
49.0
9.6
0.87
0.010
1
6.05
49.0
8.4
0.80
0.40
2
6.02
48.5
11.9
0.64
0.35
1
5.76
46.6
11.6
1.43
0.068
2
5.95
47.5
14.2
1.45
0.181
1
5.64
47.1
13.6
1.40
0.050
2
5.90
47.5
17.9
1.28
0.103
1
6.31
50.3
5.9
1.07
1.080
2
5.45
50.8
1.6
1.12
0.042
1
5.81
45.5
6.0
1.40
0.011
2
5.68
46.0
5.5
1.39
0.052
1
5.38
47.3
6.6
1.42
0.021.
2
5.52
44.4
7.9
1.38
0.029
1
6.04
51.2
4.9
1.05
0.33
2
6.03
50.4
4.2
1.05
0.33
1
5.60
47.0
5.8
1. 8
0.030
2
5.49
47.0
5.9
1.35
0.024
1
5.30
46.2
8.2
1.40
0.013
2
5.05
48.9
5.2
1.33
0.004
1
5.91
5’LO
4.3
1.03
0.178
2
5.80
50.0
4.2
1.03
0.133
-3 02-
-------
10.5 APPENDIX E
SAMPLE CALCULATIONS ON WINDSOR TEST DATA
-303-
-------
10.5.1 SAMPLE CALCULATIONS FOR LIME SLURRY SCRUBBING TESTS
TABLE 10.5-1 TOTAL SULFUR MATERIAL BALANCES
EXPERIMENT 17R
TABLE 10.5-2 RATE CALCULATIONS USING SOLID BALANCE
EXPERIMENT 17R
10.5.2 SAMPLE CALCULATIONS FOR LIMESTONE SLURRY SCRUBBING
TESTS
TABLE 10.5-3 TOTAL SULFUR MATERIAL BALANCE
EXPERIMENTS IA and 2A
TABLE 10.5-4 RATE CALCULATIONS USING LIQUID
SPECIES BALANCES - EXPERIMENT 1A
-304-
-------
TABLE 10.5-1 - TOTAL SULFUR MATERIAL BALANCES, EXPERIMENT 17R
Total S in Gas Total S in Solids Total S in Liquid Total S
Scrubber Strewn Name Flow Rate ( ppm) Solids Content ( inmole/g) ( mvnole/z) ( gr.ole/intn)
Set 1
f Inlet Gas 11.000 gniolefeiin 1500 16.5
Scrubber Spray 416 L/min 10.3 4.3
Additive 2,010 glrnin - --- 1007. .51 1.0
Outlet Gas 11,600 gmole/min 750 ---— 8.7
outgoing Downcomor 329 i/m m 2.11 g/i .87 22.2 8.6(avg.)
Strew’s ( Carb1e Bed Samples) 3.16 gI L 25.5
Bottoms l02’ L/min 10.3 g/j .68 12.9 2.0
t Total S In — 21.8 Total S Out — 19.3
Set2
Inlet Gee 11,000 gniolelmin 1500 16.5
I .jJ1 Incoring Scrubber Spray 416 s I m m 9.6 4.0
I Additive 2,010 glmmn 1002 .51 1.0
Outlet Gas 11,600 gmnle/win 750 ---- 8.7
Outgoing Dovncomer 329 sImm - —-- 1.63 g/z .765 21.6 8.3(avg.)
Streas 2.93 gI l 25.2
Bottoms 102 5/mm 11.7 g/ L .69 12.6 2. 1
S Total S In — 21.5 5 Total S Out — 19.1
-------
TABLE 10.5-1 - TOTAL SULFUR MATERIAL BALANCES, EXPERIMENT 17R (cont. ) Page 2
Flow Rate Solids Content Total S in Solids Total S in Liquid Total S
Hold Taflk Strewn Name ( L/rnin) ( g I L) ( nnnolefg) ( nmiole/L) ( ginole/nin)
Set la*
Scrubber Liquid 529 3.68 .91 35.5 2 0. 4 (avg.)
1nco ng (Downcoxner) 4.16 .94 34.7
Streaz s 4.00 .92 34.5
Scrubber Bottoms 113.5 16.5 1.12 4.O(avg.)
18.0 .91
16.7 1.02
Outgoing Hold Tank Effluent 643 7.78 2.45 18.5 24.1
Strewn
E Total S In — 24.4 t Total S Out — 24.1
Set 2
Scrubber Liquid 329 2.74 .94 22.9 8.2(avg.)
2.51 1.00 21.7
Incoming 2.69 .91 22.4
Streams Scrubber Bottoms 102 8.50 1.01 10.7 2.O(avg.)
9.08 1.01 10.6
Make-Up Water 117
(By Difference)
Outgoing Hold Tank Effluent 548 3.27 1.74 10.0 8.6
Stream
E Total S In — 10.2 E Total S Out — 8.6
* Set la Hnld tank samples were taken independently of all other samples for ibm 17R.
-------
TABLE 10.5-2 - RATE CALCULATIONS USING SOLID BALANCE, EXPERIMENT 17R
Total
Total Species Total Species Species Total Species
Method of Solid iii Solid in Liquid in Ges Flow Rate
Vessel Reaction Calculation Str om Name StreSm Flow Rate Content ( meolcS/R) ( a moles/t) ( ppr ’) ( ci-. ,1csfrt- )
17R, arb1e CaSO , H ,O Solid SO, Incoming fNosulfitesolidsin
Set I Bed Precipi- Balance Streams Incoming Streams
tation
I Downconier* 329 L/n,in 2.11 g/L 0.80 SO, 693 SO,
Outgoing 3.16 gIL
Streams I. Bottoms 102 LImin 10.3 g/z 0.59 SO, 620 S0
CaS0 , H ,O Precipitation Rate — E SO, (solid)Out - t S0 ,(solid)In
— 693 + 620 1310 meole/min
SO, Oxida— Gas/Liquid Incoming r Inlet Flue Gas 11,000 ginoles/nin 1500 SO, 16,500 50,
tion SO ,Ba a?ce Streams ‘1 Scrubber Spray 406 f/mitt 0.84 SO, 340 SO,
tation Rate
Outlet Flue Gas 11,600 gmcles/min 750 SO, 6,700 SO,
Outgoing Downconier 329 z/rnLn 8.95 SO, 2,880 SO,
Streams 8.57 SO,
Bottoms 102 i/mitt 1.26 SO, 130 SO.
SO, Oxidation Rate — E S0 ,(gas + liquid)In - E S0 ,(gas + liquid)Out - Precipitation Raie of CaS0 , %1i ,O
— 16,840 - 11,710 - 1,310 — 3820 mmole/tnin
CaS0 2l ,0 Solid SO 4 Incoming f Additive 2,010 g/min 0.5 SO 4 1,005 so,
Precipi- Bala:ice Streams
tation
Downcomer 329 i/mitt 2.11 g/L 0.07 SO 4 6L SO,
Outgoing 3.16 gIL
Streams ( Bottoms 102 f/mitt 1.0.3 g/L 0.09 SO 4 95 SO 4
CaSO, 2H ,O Precipitation Rate — 5O ,(solid)Out - Z S0 4 (solid)In
— 156 asnole/min - 1005 nixnole/min — -850 usnole/min
CaCO 3 Pre- Solid CO , Incoming f Additive 245 g/mitt 0.39 CC, 95 CO ,
cipitation Balance Streams
* All Downcoer values are art average of two marble bed aantplee.
-------
TABLE 10.5-2 - RATE CALCULATIONS USING SOLID BALANCE, EXPERIMENT 17R (cont. ) Page 2
Total
Total Species Total Species SpecLes Total S 1 ’ecies
Method of Solid in Solid in Liquid in Cas Flo Rare
Vesse1 Reaction Calculation Stream Name Stream Flow Rate Content ( iemoles/g) ( rnmoles/L) ( ppm) ( 2rcles,’- kr. )
17R , Marble CaCO, Pre- Solid CO 2 1DO comer 329 L/min 2.12. g/a 0.22 CO 3 191 CO 2
Set 1 Bed cipitation Balance Outgoing 3.16 g/i
(coa t.) Streams Bott S 102 £/min 10.3 g/L 0.36 CO 378 CO 2
CaCO 3 Precipitation Rate — Z CO 2 (solid)Out - E CO 3 (solid)In
— 569 - 95 — 474 mmole/min
Ca(OH) 3 Liquid Ca Incoming Scrubber Spray 406 Llrnin 12.6 Ca 5,110 Ca
Dissolu- Balance + Streams
tion Precipi-
tation Downcomer 329 i/mm 18.6 Ca 6,660 Ca
Outgoing 22.0 Ca
Streams Bottoms 102 1/rein 16.8 Ca 1,710 Ca
Ca(OH) 3 Dissolution Rate — Ca(liquid)Out - Ca(liquid)In + E Ca Precipitation Reactions
— 9390 - 5110 + 930 — 5210 esnole Ca(OR) 3 /min
Co
*Rold CaSO 3 •¾H 3 0 Solid SO,, Scrubber Liquid 329 i/rein 3.68 glt 0.49 SO 3 996 SO 2
Tank Precipi- Balance Incoming 4.16 g/i 0.49 SO 2
tation Streams 4.00 gli 0.45 SO,,
Scrubber Botton 114 i/rein 16.5 gIL 0.82 SO,, 1,415 50,,
18.0 gIL 0.65 SO 2
16.7 gli 0.71 SO 3
Outgoing f Hold Tank Efflu- 643 i/rein 7.78 g/i 1.92 SO,, 9,390 SO,,
Streams ‘ ent
CasO 3 ½H 3 O Precipitation Rate — y SO 3 (so lid)Out - E SO,, (solid)In
9590 - 2410 — 7180 imeole CaSO,, H 5 O/min
SO,, Oxida- Liquid SO3 Scrubber Liquid 529 i/rein 14.25 So 2 7,370 So 2
tion Balance - 13.9 SO
Precipi- ncom ng 13.6 SO 1
, ,treans
tatLon Scrubber Bottoms 114 i/rein 1.62 SO 1 170 30,,
1.42 SO 3
1.47 50,,
Outgoing f Hold Tank Efflu- 643 i/rein 0.88 SO,, 565 503
Screams ) ent
SO, Oxidation Rate — E SO,, (liquid)In - SO,, (liquid)Out - CaSO 3 .1 H O Precipitation Rate
— 7540 - 565 - 7180 — -205 omo le/min
* The hold tank samples for Set 1 were taken independently of the remaining sample sets before the use of blowdown was iqitiated.
-------
TABLE 10.5-2 - RATE CALCULATIONS USING SOLID BALANCE, EXPERIMENT 17R (cont. ) Page 3
Total
Total Species Total Species Species Total Species
in Solid in Liquid in Gas F1o. gate
______ ___________ ____________ _____________________________ __________________ _____ ( mmole /g) ( tmi oles/L) ( ppm) ( a ro1es/—Lr. )
0.42 SO 4 933 SO
0.45 SO 4
0.47 504
0.30 504 564 S0
0.26 SO 4
0.31 SO 4
0.525 SO 4 2,625 SO 4
SO 4 (solid) In
nmole CaSO 4 2H ,0/min
0.32 CO 3
0.32 CO 3
0.40 CO 3
0.43 CO 3
0.40 CO 3
0.41 CO
0.51 CO 3
Scrubber Liquid 529 Llmin
Incoming
Streams
Scrubber Bottoms 114 £/min
Outgoing f Hold Tank Efflu- 643 L/min
Streams 1 ent
Ca(OH) 4 Dissolution — Ca(liquid)Out - Z Ca(liquid)In + Precipitation Rates
— 14690 - 18870 + 9330 — 5050 ussole Ca(OH) 2 /min
Method of
Veisei Reaction Calculation
17R, Hold CaSO 4 2HaO Solid SO 4
S. t 1 Tank Precipi- Balance
(coat.) tation
Stream Name
Scrubber Liquid
Incoming
Streams Scrubber Bottoms
Outgoing ( Hold Tank Efflu-
Streams I. ent
CaSO 4 2H ,O Precipitation
CaCO 3 Pre- Solid CO 3
cipitation Balance
Solid
Stream Flow Rate Content _____________
529 L/niin 3.68 5/a
4.16 g/t
4.00 g/L
114 Llmin 16.5 gf
18.0 g/a
16.7 gIL
643 Llrnin 7.78 gIL
Rate — Z SO 4 (solid)Out - E
— 2625 - 1500 1125
329 L/min 3.68 g/a
4.16 g/L
4.00 g/L
114 a/mm 16.5 g/L
18.0 gIL
16.7 g/a
643 i/mm 7.78 g/L
— T CO (solid)Out - t CO (solid)In
— 2550 - 1526 — 1024 mnole CaCO 3 /min
Scrubber Liquid
Incoming
Streams Scrubber Bottoms
Outgoing f Hold Tank 5ff lu-
Streams ent
CaCO 3 Precipitation Rate
Ca(OH) 3 Liquid Ca
D ssolu- Balance +
tion E Precipi-
tation
723 CO 3
803 CO 2
2,350 CO 2
29.7 Ca
29.9 Ca
29.6 Ca
27.8 Ca
22.8 Ca
15,700 Ca
3,170 Ca
14,690 Ca
-------
TABLE 10.5-2 - RATE CALCULATIONS USING SOLID BALANCE, EXPERIMENT 17R (cont. ) Page 4
Total
Total Species Total Species Species Total Species
Method of Solid in Solid in Liquid in Gas Flow Rite
Vessel Reaction CalcuJation Stream Name Stream Flow Rate Content _Jmmoles/g) ( n oles/L) ( ppm) ( cLe 5/ ’ )
hR. irble CaSO 3 •¾H ,O Solid SO, Incoming No Sulfite solids
ec 2 cd Balance Streams in entering
streams.
IDowncomer 329 1/rein 1.63 g/l 0.30 so, 225 So,
Outgoing 2.93 gli
Streams Isottoms 106 1/rein 11.7 gIL 0.50 sO, 620 SO,
CaS0, H ,0 Precipitation Rate — z SO ,(eolid)Out - t S0 ,(solid)In
— 845 usnole CaSO 3 R ,0/min
SO, Oxida- Gas/Liquid Incoming Inlet Flue Gas 11,000 greole/min 1500 SO, 16,500 SO:
tion c; ; Streams C Scrubber Spray 406 f/rein 0.89 SO, 361 SO,
cipitation Outlot Flue Gas 11,600 gmole/min 770 SO, 8,930 SO
Outgoing flounconier 329 1/rein 7.57 SO. 2,765 Si),
Streams 9.23 so,
Bottoms 106 zlmin 1.30 so, 138 53,
SO, Oxidation Rate — z SO ,(liquid)In - SO ,(liquid)Out - Precipitation Rate of CaSO ,½H ,O
— 16860 — 11830 - 845 4185 nusole SO,/tntn
CaS0 4 2H ,O Solid SO 4 Incoming f Additive 2,010 g/min 0.5 SO 4 1,005 SO.
Precipi- Balance Streams
tat ion
I Downcomer 329 1/rein 1.63 g/L 0.465 5O 349 SO
Outgoing 2.93 g/L
Streams Bottoms 102 1./rein 11.7 gli 0.192 5O 229 SO
CaSO 2H,O Precipitation Rate — t S0 4 (solid)Out - S0 4 (solid)In
— 578 - 1005 -430 remole/min
CaCO, Pre- Solid CO, Incoming f Additive 2,010 g/min 0.39 CO, 783 CO ,
cipitation Balance Streams I
I Downcomer 329 /min 1.63 glz 0.296 CO , 222 GO,
Outgoing 2.93 gIL
Streams I Bottoms 102 1/rein 11.7 gIL 0.511 CO , 608 CO.
CaCO , Precipitation Rate — t CO ,,(solid)Out - Z C0 ,(solid)In
— 830 - 783 — Essentially Zero
-------
TABLE 10.5-2 - RATE CALCULATIONS USING SOLID BALANCE, EXPERIMENT 17R (cont. ) Page 5
Total
Total Species Total Species Species Total Species
Method of So lid an Solid i i ’ LiquLd in (as Fir. Rfle
Vessel Reaction Calculation Stream Name Stream Plow Rate Content ( mmolcs/g) ( mo les / i) ( rles/mu ) _
lift, Marble Ca(OH) Liquid Ca Incoming Scrubber Spray 406 i/m m 13.5 Ca 5,680 Ca
5 ’: 2 Bed Diasolu- Balance + Streams
(cor.t.) tion Precipi-
tation Downc 9 mer 329 i/win 19.0 Ca 6,730 Ca
outgoing [ 21.95 Ca
Streams
Bottoms 102 i/win 16.0 Ca 1,632 Ca
Ca(OH) 3 Dissolution — z Ca(liquid)Out - S Ca(liquid)In + t Ca Precipitation Rates
— 8362 - 5480 + 415 3300 irmole/min
Hold CaS0 3 HO SO 2 Solids Scrubber Liquid 329 i/mm 2.74 gI l 0.52 SO Avg. 453 50,
tat ion
Streams 2.69 g/e 0.49 S0
Tank Precipi- Balance Incoming f 2.51 g/ i 0.55 SO 2
Scrubber Bottoms 102 i/win 8.50 gI L 0.88 SO, Avg. 744 SO,
9.08 g/L 0.78 SO 3
Outgoing Hold rank Efflu- 548 i/win 3.27 g/z 1.51 SO 2 2,710 SO,
Streams tnt
CaSO , ¾H,0 Precipitation Rate — SO, (aolid)Out — S SO1(solid)In
— 2710 - 1200 — 1510 trots CaSO,¾H,O/mmn
SO, Cxi- Liquid SO , Scrubber Liquid 329 a/win 6.96 50, Avg. 2,870 50,
dation Balance - Incoming 8.13 50,
Precipita- Streams 9.10 50,
tion Rate Scrubber Bottoms 102 i/win 0.97 50, Avg. 102 50,
1.03 SO,
Outgoing r Hold Tank Efflu- 548 i/win 1.30 SO, 713 50,
Streams ent
50, Oxidation Rate — E SO, (Iiquid)In - S 50, (liquid)Out - CaS0, jH,0 Precipitation Rate
— 2970 -_710 - 1510 — 750 cniiole 50,/win
CaS0, 2H,0 Solid SO Scrubber Liquid 329 i/win 2.74 g/ L 0.42 SO Avg. 375 SO ,
tkon Rate Incoming 2.69 gI L 0.42 50,
Precipita- Balance f 2.51 g/ L 0.45 SO
Streams
Scrubber Bottoms 102 i/win 8.50 g I L 0.13 SO, Avg. 162 50,
9.08 gI L 0.23 SO,
Outgoing mold Tank Efflu- 548 s/win 3.27 gI L 0.23 SO, 41250,
Streams ‘j. ent
CaSO,2H,O Precipitation Rate : SO ,(eolid)Out - S SO,(solid)In
4 12 - 537 — -125 asnole CaSOe2X,0/min
-------
TABLE 10.5-2 - RATE CALCULATIONS USING SOLID BALANCE, EXPERIMENT 17R (cont. ) Page 6
Tots I
Total Species Total Species Species Total Species
Method of Solid in Solid in Liquid in Gas Flo. Rate
Vessel Reaction Calculation Stream Name Stream Flow Rate Content ( trmolcs/g) ( ssnoles/L) ( ppm) 1r oIesI-ii )
17R, Mold CaCO 3 Pre- Solid CO 3 Scrubber Liquid 329 L/min 2.74 gli 0.23 Co 3 Avg. 200 C0
Se : 2 Tank cipitation Balance i 2.51 g/L 0.24 CO 3
(cc t.) Rate 2.69 g/L 0.22 CO
Scrubber Bottoms 102 L/uiin 8.50 gIL 0.57 CO 3 Avg. 502 CO 2
9.08 gIL 0.55 CO 3
Outgoing f Hold Tank Efflu- 548 L/min 3.27 g/.& 0.65 Co 3 1,165 CO;
Strc’nmR I. ont
CaCO 3 Precipitation Rate — t CO 3 (solid)Out - CO3(solid)In
— 1165 - 700 — 465 ussole CaCO 3 /uiin
Ca(Ofl) 3 Liquid Ca Scrubbor Liquid 329 L/rnin 20.0 Ce Avg. 6,500 Cs
Dissolu- Balance + 19.7 Ca
tion Precipi- Incomin 19.6 Ca
tation Rate Screams Scrubber Bottoms 102 ham 17.4 Ca Avg. 1,780 Ca
17.5 Ca
Make-Up Water 117 ham 1.08 Ca 126.5 Ca
Outgoing I Hold Tank Efflu— 548 h/mm 12.6 Ca 6,900 Ca
Streams 1_ ent
Ca(OH) 3 Dissolution Rate — t Ca(liquid)Out — Ca(liquid)In + 2 Ca Precipitation Rate
— 6900 - 8410 + 1850 — 340 muole Ca(OH) /min
Ca(OH) 5 Solid Ca Scrubber Liquid 329 i/mm 2.74 g/L 3.40 Ca Avg. 3,095 Ca
Dissolu- Balance + 2.51 gIL 3.68 Ca
tion 2 Precipi- 2.69 g/L 3.57 Ca
tation Rate Scrubber Bottoms 102 i/aim 8.50 gI l 5.52 Ca Avg. 6,980 Ca
9.08 gIL 5.59 Ca
Outgoing f Hold Tank Efflu- 548 i/aim 3.27 gIL 4.57 Ca 8,190 Ca
Streams 1. ent
Ca(OH) 3 Dissolution Rate — 2 Ca(solid)In - 2 Ca(solid)Out + 2 Ca Precipitation Rates
— 8075 - 8190 + 1850 — 1965 ussole Ca(OH) 3 /ain
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TABLE 10.5-3 - TOTAL SULFUR MATERIAL BALANCE, EXPERIMENTS 1A AND 2A
Total S Solids Total S Total $
in Gas Content in Solids in Liquid Total S
Vessel Streaz, Name Strewn Flow Rate ( ppn) ( z/L ) jnrolesig) ( rnoles/L) ( gnoles/nin )
RUN 1
Set 1 Scrubber Incoming j Inlet Gas 9,770 gmoles/ciin 2,310 ---a ---- 22.6
Streams 1. Scrubber Spray 568 1/ mm 77.5 3.57 23.01 170.
f Outlet Gas 10,800 grnoles/mirt 1,110 ---- ---- 12.0
Outgoing Downcon,er 511 2/ mm 75.5 4.10 42.66 180.
(. Scrubber Bottoms 57 1/mm 74.7 4.07 40.37 19.6
Z Total S In — 192.6 S Total S Out a 211.6
Hold Tank p71.0 3l.02
Scrubber Liquid 511 2/nm 72.9 4.22 34.39 166.
(A ) 1 .733 L 41 9 1353 1
Incoimir.g
Strean r 53 • 3 5.10 29.14
Scrubber Bottoms 57 2/mm t 5 85 (4.72 (28.56 18.2
80.6 2.76 29.07
Clarifier Wéir 45 i/mm 0.1 19.78 .9
Outgoing f Hold Tank Effluent 613 i/nm 80.2 3.60 23.45 191.4
Streams
S Total S In a 185.1 S Total S Out a 191.4
Set 2 Scrubber Incom.ng r Inlet Gas 9,770 gmnoles/min 2,310 22.6
Streams . Scrubber Spray 568 1/mm 83.0 3.53 23.21 179.
r Outlet Gas 10,800 gmnoles/min 1,110 12.0
Outgoing Downcomer S1L 1/mm 81.3 4.34 42.13 201.5
Scrubber Bottoms 57 i/nm 80.9 3.69 40.52 19.3
S Total S In a 201.6 5 Total S Out — 232.8
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TABLE 10.5-3 - TOTAL SULFUR MATERIAL BALANCE, EXPERIMENTS 1A AND 2A (cont. ) Page 2
Total S Solids Total S Total S
in Gas Content in Solids in L .qu3.d Total S
Vessel Stream Name Stream Flow Rate ( ppm) ( g iL) ( mr olcs/g) ( rrmoles/L) ( grrolesf Ln )
RUN 1
Set 2 Hold Tank r 73 • 9 r 3 • 98
Scrubber Liquid 511 L/niin 73.5 3.85 1 33.93 164.
¼cont., L73.l 13.90 L 3 2. 77
Incoming
Streams Scrubber Bottoms 57 1/mm (79.7 (3.59 (28.64 16.7
180.2 -3.80 L28 79
Clarifier Weir 45 i/rain 0.3 19.47 8.8
Outgoing Hold Tank Effluent 613 i/rain 79.7 3.49 27.37 186.8
Streams
E Total S In — 191.5 Total S Out 186.8
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TABLE 10.5-4 - RATE CALCULATIONS USING LIQUID SPECIES BALANCES, EXPERIMENT 1A
Total Species Total Species Total Spec es
Method of in Liquid xn Gas Flow Race
Vessel Reaction Calculation Stream Name - Scream Flow Rate ( mmoles/z) ( opr) ( rrztles/r n )
RUN IA
Sec 1 Marble Bed CaS0 J .%0 Gas/Liquid SO Incoming f lnlet Flue Cas 9,770 noles/min 2,310 22,600
Precipitation Balance Streams ‘IScrubber Spray 568 Z/min 3.04 1,730
10k1t1et Flue Gas 10,800 giroles/min 1,110 12,000
Downcomer 511 tfmin 22.6 l1,6C O
(.Scrubber Bottoms 57 ifmtn 23.8 1,350
CaSO ’½H 2 O Precipitation Rate — S SO (Liquid + Cas) In — S S0 2 (Liquid + Gas) Out - Oxidation Rate (assumed)
— 24,330 - 24,950 - .24 (22,600 — 12,000) — -3,160 moles/mitt
CaSO 4 2H 2 0 Liquid 504 Incoming fScrubber Spray 568 L/min 20.0 11,3
Precipitation Balance + Streams
Oxidation Rate
Outgoing Downcomer 511 2/ mm 20.0 10,200
Streams I Scrubber Bottoms 57 2/m m 16.6 946
CaSQ 2H 9 0 Precipitation Rate — S S0 (Liquid) In — E S0 (Liquid) Out + Oxidation Rate
— 11,300 - 11,146 + .24 (10,600) - — 2,694 nnoles/min
CaCO 3 Liquid Ca Incoming f Scrubber Spray 568 .e/min 19.1 10,800
Dissolution Balance and Ca Stroaits
Precipitation
Rates
Outgoing fDowncomaer 511 2/mm 27.7 14,100
Streams l.Scrttbber Bottoms 57 2/mm 26.9 1,530
CaCO 3 Dissolution Rate — S Ca (Liquid) Out - S Ca (Liquid) In + S Ca Precipitation Rates
— 15,630 - 10,800 (-466) 4,364 nimoles/min
Hold Tank CaSO 3 H 2 0 Liquid SO Scrubber Liuqid 511 .t/min 10,0 5,140
Precipitation Balance coming I5cfl er Bottoms 57 2/m m 7.18 409
Clarifier Weir 45 i/mm 1.08 49
Outgoing fRold Tank Effluent 613 1/mm 2.65 1,620
Streams
CaSO 3 R 2 O Precipitation Rate — £ S0 2 (Liquid) In - £ S0 3 (Liquid) Out
— 5,598 — 1,620 — 3,978 muioles/mmn
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TABLE 10.5-4 - RATE CALCULATIONS USING LIQUID SPECIES BALANCES, EXPERINENT 1A (cont. ) Page 2
Total Species Total Species Total S e os
Method of in Liquid in Gas Flo ’ . .c:e
Vessel Reaction Calculation Strewn Name Strewn Flow Rate ( rrmoles/L) ( opm) ( -o les!—: )
lA
S : 1 liold Taik CaSO 4 2H 5 0 Liquid SO 4 rScrubber Liquid 511 i/mm 22.6 11,600
(ac—c) (cont.) Precipitation Balance Incoming ‘Scrubbcr Bottoms 57 i/mm 21.7 l,2 .0
Streams IClarifler Weir 45 i/mm 18.7 E4 .
Outgoing Rold Tank Effluent 613 i/nun 20.8 12,700
Streams
CaSO 4 2H 3 O Precipitation Rate E SO 4 (Liquid) In - E SO 4 (Liquid) Out
— 13,681 - 12,700 981 n noles/min
CaCO 3 Disso- Liquid Ca IScrubber Liquid 511 i/mm 24.3 12,400
lut .on Balance and Cu Inconing Scrubber Bottoms 57 .L/min 22.9 1,300
Prccipitation Strcwis
Rates IClarifier Weir 45 i/tnin 17.9 807
Outgoing Ho1d Tank Effluent 613 i/mm 19.4 11.900
Streams
0’
CaCO 3 Dissolution Rate E Ca (Liquid) Out — E Ca (Liquid) In + Z Ca Precipitation Rate.
— 11,900 — 14,507 + 4,959 — 2,352 nmoles/nuin
Set 2 Marble Bed CaSO 3 ½H 2 O Gas/Liquid SO 3 Incoming rlnlet Flue Gas 9,770 gmoles/min 2,310 22,600
Precipitation Balance Streams (Scrubber Spray 568 L/nuin 3.04* 1,730
lOutlet Flue Gas 10,800 gmoles/min 1,110 12,000
Downcomer 511 i/mm 17.9 9,140
LScrubber Bottoms 57 i/nun 16.2 924
CaSO 3 R 3 O Precipitation Rate E SO 3 (Liquid + Gas) In - Z SO3 (Liquid + Gas) Cut - Oxidation Rate (ass .mzed)
— 24,330 — 22,064 — .24 (22,600 - 12,000) — -274 numoles/min
CaSO 4 2H 5 O Liquid S0 Incoming Scrubber Spray 568 i/mm 20.2 11,500
Precipitation Balance + Streams
Oxidation Rate
Outgoing rDownccmer 511 i/mm 24.2 12,400
Streams tScrubber Bottoms 57 i/mm 24.3 1,380
CaSO 4 2H 3 0 Precipitation Rate — t SO 4 (Liquid) In - E SO 4 (Liquid) Out + Oxidation Rate
— 11,500 - 13,780 + .24 (10,600) — 260 e o1es/nin
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TABLE 10.5-4 - RATE CALCULATIONS USING LIQUID SPECIES BALANCES, EXPERIMENT lÀ (cont. ) Page 3
Total Species Total Species Total Species
Method of in Liquid in Gas Flow Rate
Vessel Reaction Calculation Stream Name Stream Flow Rate ( nrr.olesIL) ( pp m) ( rro les,’rir )
RUN lÀ
Set 2 > arble Bed CaCO 3 Disso- Liquid Ca Sal- Incoming f Scrubber Spray 568 S/mm 19.6 11,200
(cent.) (coat.) lution ance and Cu Streams
PrccipitatLon
Rate
Outgoing fDowncomer 511 5/mm 30.0 15 ,300
Streams tScrubber Bottoms 57 5/mm 28.5 1,600
CaCO 3 Dissolution Rate — S Ca (Liquid) Out - S Ca (Liquid) In + S Ca Precipitation Rate
— 16,900 - 11,200 + (-14) — 5,686 caoles/min
Hold Tank CaSO 3 1-1O Liquid £02 f Scrubber Liquid 511 5/n un 10.3 5,260
Precipitation Balance Scrubber Bottoms 57 s/mm 7.77 443
t.Clarifier t4ejr 45 s/tnin 1.12 53.4
Outgoing [ Hold Tank Effluent 613 5/mm 12.47 7,640
Strea. ss
CaSO 1 jH 5 O Precipitation Rate a 5 5% (Liquid) In - 5 5% (Liquid) Out
a 5 753 — 7,640 a —1887 intoles/min
CaSO 2M O Liquid S0 f Scrubber Liquid 511 5/mm 22.9 11,700
Prectpitation Balance Incoming Bottoms 57 s/nan 20.8 1,190
Clarifier Weir 47 5/mm 18.3 623
Outgoing f Hold Tank Effluent 613 5/mm 14.9 9,130
Streams
Ca SO 2It O Precipitation Rate 5 SQ (Liquid) In - S SQ (Liquid) Out
— 13 ,713 - 9,130 — 4,583 mnoles/min
CaC% Disso- Liquid Ca Bal- I Scrubber LLquid 5 11 s/n un 24.5 12,500
lution i a on t5c 1 t. Bottoms 57 5/mm 21.7 1,240
Rates Clarifier Weir 45 5/mm 17.6 792
Outgoing f Hold Tank Effluent 615 5/mm 24.8 15,200
Streams
CaCO 3 Dissolution Rate a 5 Ca (Liquid) Out — t Ca (Liquid) In + S Ca Precipitation Rate
a 15,200 - 14,530 + 2,690 — 3,360 numoles/min
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TECHNICAL REPORT DATA
(Please read Jncjpjct,ons on the rewcrse before completing)
1 REPORT NO.
EPA- 650/2 - 75-006 12.
3. RECIPIENT’S ACCESSIO NO.
4 TITLE AND SUBTITLE
A Theoretical and Experimental Study of the
Lime/Limestone Wet Scrubbing Process
5. REPORT DATE
December 1974
6. PERFORMING ORGANIZATION CODE
7 AUTHOR(S) M.Ottmers Jr. , J. L. Phillips, C. E. Burklin
W. E. Corbett, N. P. Phillips, and C. T. Shelton
8. PERFORMING ORGANIZATION REPORT NO.
9 PERFORMING ORGANIZATION NAME AND ADDRESS
Radian Corporation
8500 Shoal Creek Boulevard
Austin, Texas 78766
10. PROGRAM ELEMENT NO.
1ABO13(’ROAP 2IACY-03l —
11.-CONTRACT/GRANT NO.
68-02-0023 -
12 SPONSORING AGENCY NAME AND ADDRESS
EPA, Office of Research and Development
NERC -RTP, Control Systems Laboratory
Research Triangle Park, NC 27711
13. TYPE OF REPORT AND PERIOD COVERED
Final; 5/71-5/73
14. SPONSORING-AGENCY CODE-
15. SUPPLEMENTARY NOTES
16. ABSTRACT
The report describes results of technical efforts in several areas relating to the
development of the lime/limestone wet scrubbing process. It reviews a portion of
the test plan for EPA ’s prototype test facility. It describes laboratory studies of
key reaction steps, including lime and limestone dissolution rates and calcium
sulfite and sulfate precipitation rates. It describes engineering and chemistry sup-
port for EPA-contracted pilot unit studies, including test program design, on-site
sampling and chemical analysis of test samples, as well as engineering analysis of
test results. It reports on chemical analysis support, including assistance with the
analytical data, system at EPA’s prototype test facility.
17. KEY WORDS AND DOCUMENT ANALYSIS
a DESCRIPTORS
b. IDENTIFIERS/OPEN ENDED TERMS
C. COSATI Field/Group
Air Pollution Calcium Sulfates
Des ulfurization Analyzing
Scrubbers
Calcium Oxides
Limestone
Experimental Data
Air Pollution Control
Stationary Sources
Calcium Sulfite
Lime/Limestone Scrub-
bing
l3B
07A, O7D
O7B
08G
14B
18 DISTRIBUTION STATEMENT
Unlimited
19 SECURITY CLASS (ThasReport)
Unclassified
21 NO. OF PAGES
330
20 SECURITY CLASS (This page)
Unclassified
22 PRICE
EPA Form 2220-1 (9.73)
-318-
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