EPA-600/2-76-281
October 1976
Environmental Protection Technology Series
DESULFURIZATION OF STEEL MILL
SINTER PLANT GASES
Industrial Environmental Research Laboratory
Office of Research and Development
U.S. Environmental Protection Agency
Research Triangle Park, North Carolina 27711
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RESEARCH REPORTING SERIES
Resear:h reports of the.Office of Research and Development,
U.S. Environmental Protection Agency, have been grouped into
five series. These five broad categories were established to
facilitate further development and application of environmental
technology. Elimination of traditional grouping was consciously
planned to foster technology transfer and a maximum interface in
related fields. The five series are:
1. Environmental Health Effects Research
2, Environmental Protection Technology
3. Ecological Research
4. Environmental Monitoring
5. Socioeconomic Environmental Studies
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.
EPA REVIEW NOTICE
This re port has been reviewed by the U. S. Environmental Protection
Agency, and approved for publication. Approval does not signify that
the contents necessarily reflect the views and policies of the Agency, nor
does mention of trade names or commercial products constitute endorse-
ment or recommendation for use.
This document is available to the public through the National
Technical Information Service, Springfield, Virginia 22161.
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EPA-600/2-76-281
October 1976
DESULFURIZATION
OF STEEL MILL
SINTER PLANT GASES
by
Gary D. Brown, Richard T. Coleman,
James C. Dickerman, and Philip S. Lowell
Radian Corporation
P.O. Box 9948
Austin, Texas 78766
Contract No. 68-02-1319, Task 58
ROAPNo. 21AQR-005
Program Element No. 1AB015
EPA Task Officer: Norman Plaks
Industrial Environmental Research Laboratory
Office of Energy, Minerals, and Industry
Research Triangle Park, NC 27711
Prepared for
U.S. ENVIRONMENTAL PROTECTION AGENCY
Office of Research and Development
Washington, DC 20460
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ABSTRACT
This report presents the results of a study to eval-
uate the technical and economic feasibility of using limestone
scrubbing technology to control sinter plant emissions. Data
from Soviet and Japanese sinter plants employing limestone
scrubbing technology were used to develop a realistic design
basis. A conceptual process design was developed and used
to prepare economic estimates.
Results of the process design indicate that control
of sinter plant emissions by limestone scrubbing is technically
feasible. Economic evaluations show that a retrofitted limestone
scrubbing system will increase the cost of producing sinter by
about $2.07 per metric ton of product sinter for a standard sin-
ter plant operation. For a sinter plant with a windbox:gas re-
circulation system the cost increase would be about $1.59 per
metric ton of product sinter.
111
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TABLE OF CONTENTS
Page
ABSTRACT iii
TABLE OF CONTENTS iv
LIST OF TABLES vi
LIST OF FIGURES ix
CONVERSION FACTORS x
GLOSSARY xi
1.0 SUMMARY 1
2.0 INTRODUCTION 3
3.0 TECHNICAL DISCUSSION 5
3.1 Description of Steel Mill Sinter Plants 5
3.1.1 Process Description 6
3.1.2 Process Developments 9
3.1.3 Sinter Plant Emissions 13
3.2 Description of the Lime/Limestone Wet Scrubbing
Process 18
3.2.1 Process Description 20
3.2.2 Design Considerations 25
3.2.3 Typical Operations Relating to Sinter Plants... 32
3.3 Evaluation of USSR and Japanese Data 33
3.3.1 Summary of Soviet Data 33
3.3.2 Summary of Japanese Data 35
iv
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TABLE OF CONTENTS (cont.) Page
4. 0 DESIGN APPROACH 37
4.1 Des ign Bas is and As sumptions 38
4.1.1 Sinter Plant Design Basis 39
4.1.2 Limestone Scrubbing Design Basis 44
4. 2 Economic Basis 55
4.2.1 Capital Investment Costs 55
4.2.2 Annual Operating Costs 58
5.0 RESULTS 60
5.1 Process Designs 60
5 . 2 Limestone Scrubbing System Layout 69
5 . 3 Economic Evaluation 74
5.3.1 Total Capital Investment 76
5.3.2 Annual Operating Costs 78
6 .0 CONCLUSIONS AND RECOMMENDATIONS 81
6.1 Conclusions 81
6. 2 Recommendations 82
7 . 0 REFERENCES 85
APPENDIX A - COMMENTS ON THE SOVIET DATA A-l
APPENDIX B - COMMENTS ON THE JAPANESE DATA B-l
v
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TABLE OF CONTENTS (cont.) Page
APPENDIX C - DESCRIPTION OF RADIAN'S
PROCESS SIMULATION MODEL C-l
APPENDIX D - PROCESS EQUIPMENT LIST AND COST
DATA D-l
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LIST OF TABLES
Page
TABLE 3-1 SINTER-MIX COMPOSITION 8
TABLE 3-2 MATERIALS USED IN THE PRODUCTION OF SINTER
AT STEEL PLANTS IN THE UNITED STATES 12
TABLE 3-3 COMPOSITION OF PARTICULATE EMISSIONS 15
TABLE 3-4 SIZE DISTRIBUTION OF PARTICULATE EMISSIONS... 16
TABLE 3-5 TYPICAL CONCENTRATIONS OF GASEOUS EMISSIONS
FROM STEEL MILL SINTER PLANTS 17
TABLE 3-6 SULFUR BALANCE FOR SINTER MACHINE OPERATION.. 19
TABLE 3-7 COMPARISON OF SCRUBBER TYPES FOR A LIMESTONE
WET SCRUBBING SYSTEM 28
TABLE 4-1 SINTER PLANT DESIGN BASIS 40
TABLE 4-2 COMPOSITION OF PARTICULATES IN SINTER PLANT
FLUE GAS 43
TABLE 4-3 LIMESTONE COMPOSITION 45
TABLE 4-4 MAKEUP WATER COMPOSITION 45
TABLE 4-5 LIMESTONE SCRUBBING DESIGN PARAMETERS 50
TABLE 4-6 MASS EMISSION RATES FROM THE RADIAN BASE CASE
STEEL MILL SINTER PLANT AFTER LIMESTONE SCRUB-
BING OF THE WINDBOX EXHAUST GAS 52
TABLE 4-7 ITEMS USED TO ESTIMATE THE TOTAL CAPITAL IN-
VESTMENT REQUIRED FOR A LIMESTONE SLURRY
PROCESS 57
TABLE 4-8 BREAKDOWN OF ANNUAL OPERATING COSTS FOR A
LIMESTONE SLURRY PROCESS 59
TABLE 5-1 MATERIAL BALANCE FOR A LIMESTONE SCRUBBING
PROCESS ON A STANDARD SINTER PLANT 63
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LIST OF TABLES (cont.)
Page
TABLE 5-2 MATERIAL BALANCE FOR A LIMESTONE SCRUBBING
PROCESS ON A SINTER PLANT WITH WINDBOX
RECYCLE 64
TABLE 5-3 DESCRIPTION AND DESIGN SPECIFICATIONS FOR
MAJOR PROCESS EQUIPMENT 65
TABLE 5-4 OPERATING PARAMETERS FOR PROCESS DESIGNS 68
TABLE 5-5 SPACE REQUIREMENTS FOR A LIMESTONE SCRUBBING
SYSTEM OH STEEL MILL SINTER PLANT APPLICATIONS 73
TABLE 5-6
TABLE 5-7
TABLE 5-8
TOTAL CAPITAL INVESTMENT SUMMARY FOR STEEL
MILL SINTER PLANT FLUE GAS DESULFURIZATION
USING LIMESTONE SLURRY SCRUBBING
LIMESTONE SLURRY PROCESS TOTAL ANNUAL OPERAT-
ING COSTS (STANDARD CASE).,
LIMESTONE SLURRY PROCESS TOTAL ANNUAL OPERAT-
ING COSTS (RECYCLE CASE)
77
79
80
VI11
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LIST OF FIGURES
Page
FIGURE 3-1 SCHEMATIC FLOW DIAGRAM FOR TYPICAL MODERN
SINTER PLANT 10
FIGURE 3-2 PROCESS FLOW DIAGRAM - LIME/LIMESTONE WET
SCRUBBING 21
FIGURE 5-1 PROCESS FLOW DIAGRAM - LIMESTONE SCRUBBING
PROCESS FOR STEEL MILL SINTER PLANT
APPLICATION 62
FIGURE 5-2 LAYOUT OF SCRUBBING SECTION OF A LIMESTONE
SCRUBBING PROCESS FOR A STANDARD STEEL MILL
SINTER PLANT OPERATION 70
FIGURE 5-3 LAYOUT OF SCRUBBING SECTION OF A LIMESTONE
SCRUBBING PROCESS FOR A RECYCLE STEEL MILL
SINTER PLANT OPERATION 71
FIGURE 5-4 LAYOUT OF FEED PREPARATION AND SLURRY PRO-
CESSING SECTION OF A LIMESTONE SCRUBBING
PROCESS FOR A STEEL MILL SINTER PLANT
APPLICATION : 72
IX
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CONVERSION FACTORS
The metric system is used in this report. Following
are jiome factors for conversion between metric and English
systems:
1 m (meter) ~ 3.281 feet
1 m3 (cubic meter) = 35.31.4 cubic feet
1 mt (metric ton) = 1.1023 short tons
1 kg (kilogram) = 2.2046 pounds
1 liter = 0.2642 gallon
The capacity of FGD systems is expressed in Nm3/hr (normal cubic
meters per hour)
1 Nm3/hr = 0.589 SCFM
L/G ratio (liquid/gas ratio) is expressed in liters/Mm3
1 liter/Nm3 = 7.481 gallons/1000 SCF
x
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GLOSSARY
Carbide Sludge - Calcium oxide (CaO) and impurities
formed as a byproduct of acetylene manufacture.
Coke Breeze - coke fines that are generated during
the crushing and sizing of the coke for blast furnace consump-
tion and which are used as a fuel in the sinter charge.
Flue Gas - sinter plant off-gas.
Fluxing - any process in which materials (Fluxes)
are added to the metal charge to aid in the removal of gases.
oxides, or other impurities.
Fluxstone - limestone or dolomite.
Fly Ash - particulates entrained in the sinter plant
off-gas.
Gangue - a waste rock or slag material remaining
after most of the metal values have been removed.
Relative Saturation - The relative saturation (RS)
is the product of the activities of the species which react to
produce the precipitating solid divided by the solubility
product constant, as shown in the following equations for calcium
sulfate.
Ca ' + S04 + 2H20 £ CaSO, -2H20
RS = LaCa-H- • aso; ' aH20(£)
For precipitation to occur, the relative saturation must be
greater than one, and the rate R positive (see equation 2-4,
Appendix C) . For dissolution to occur, the relative satura-
XI
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tion must be less than one, and the rate R negative. At
equilibrium, the relative saturation is equal to one, and the
rate is zero.
Slag - A residue that forms on the surface of
molten metal during fluxing.
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1.0 SUMMARY
Desulfurization of sinter plant windbox gases by lime-
stone scrubbing is commercially practiced in both the USSR and
Japan; it is not currently practiced in the United States. To
determine the costs of applying this technology domestically,
conceptual process designs were prepared for both standard sin-
ter plant operations and operations employing a windbox gas re-
circulation system. Results of the conceptual designs were used
to size process equipment. An economic basis was selected and
applied to the process designs to perform an evaluation of both
capital and operating costs for each system.
The services of two outside consultants were retained
in order to help in obtaining the data and information that was
necessary to perform this evaluation. Mr. Richard Jablin, a
consultant with over 35 years experience in steel mill engineer-
ing and environmental control, provided much assistance and in-
formation on steel mill sinter plant operations. Mr. Jablin
holds several patents in the area of steel making and has been
employed by various steel companies since 1950. He currently
directs a consulting engineering firm, Richard Jablin and As-
sociates, located in Winchester, Virginia. Dr. Jumpei Ando,
an international consultant and lecturer in the areas of SOX
and NOX control, provided data and descriptions of several lime
and limestone systems which are currently being used in Japan
to remove S02 from sinter plant gases. Dr. Ando has held pre-
vious positions with the Faculty of Engineering, University of
Tokyo and the Tennessee Valley Authority. He is currently a
Professor at Chuo University in the Faculty of Science and En-
gineering.
The process designs and cost estimates are based upon
data obtained from the following sources:
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1) information available from Radian
files, Mr. Richard Jablin, and the
open literature;
2) information on Soviet technology
obtained by the EPA as a result
of a technology interchange agree-
ment between the US and USSR;
3) information on Japanese technology
prepared for Radian by Dr. Jumpei
Ando;
4) cost data provided in a TVA report
prepared by McGlamery, et al. (MC-147).
The results of this evaluation indicate that the
capital costs of a limestone scrubbing system, applied to a
sinter plant having a capacity of 6312 mtpd of product, range
from $8-10 million, depending upon whether or not the sinter
plant: uses windbox gas recirculation. For the same sinter plants
the operating costs would be respectively, $1.59-2.07 per metric
ton of product sinter. The desulfurization system evaluated
here uses a venturi prescrubber which would effectively remove
parti.culates. Optimisation of the technology could be accomp-
lished by determining the effects of contaminants in the sinter
plant: windbox gases on limestone scrubbing process chemistry
and on corrosion in the prescrubber loop.
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2.0 INTRODUCTION
Sulfur dioxide (S02) emissions from steel mill
sinter plants are of concern to the U.S. Environmental Pro-
tection Agency. Past experience of both the U.S. electric
power industry and of USSR and Japanese steel manufacturers
indicates that limestone slurry scrubbing is a feasible tech-
nique for sinter plant emission control. Under contract to
EPA, Radian has completed this study to evaluate the applica-
bility of limestone slurry scrubbing to the sinter plant emis-
sion control problem.
The objectives of the study were twofold. First, the
evaluation was performed to determine the technical feasibility
of applying limestone wet scrubbing technology to control sinter
plant emissions. Potential process problems and land require-
ments for solid waste disposal were identified. Secondly, the
study was to provide EPA with process economics to aid them in
determining the economic feasibility of applying limestone tech-
nology to sinter plants.
To accomplish these objectives, the following approach
was taken. First, data on U.S. sinter plant operations were
collected and reviewed. Secondly, data from USSR and Japanese
sources were collected and evaluated to determine the applica-
bility of foreign experience to domestic applications. From
these evaluations, a design basis was formulated and used to
develop conceptual process designs for limestone scrubbing
systems to control sinter plant emissions. Both standard sinter
plant operations and windbox gas recirculation operations were
used as design cases. Finally, estimates were made of process
economics for both design cases.
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The following sections of this report describe the
evaluations performed as part of this study. Section 3.0 is
a technical discussion of sinter plant and limestone scrubbing
operations. A summary of the evaluations of Soviet and Japa-
nese experiences with limestone scrubbing of sinter plant emis-
sion.'; is also included. Section 4.0 provides details of the
design approach and basis. Section 5.0 reports the study results
and Section 6.0 presents conclusions and recommendations.
Supporting details are included in the appendices.
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3.0 TECHNICAL DISCUSSION
In order to evaluate the applicability of limestone
slurry scrubbing to steel mill sinter plants, information on both
the operations and emissions of U.S. sinter plants was collected
and reviewed. Information on limestone slurry scrubbing opera-
tions, obtained from previous Radian reports and in-house
files, was used as a basis for determining the process design
considerations that would be important as related to sinter
plant applications. Data were also collected from Japanese
and Russian sources on the operating characteristics of lime-
stone slurry scrubbing units which currently process steel mill
sinter plant flue gases.
i
Typical sinter plant operations and emissions are
described in Section 3.1. A description of limestone slurry
scrubbing is given in Section 3.2 and a summary of the data
collected from both Soviet and Japanese limestone scrubbing
experiences is presented in Section 3.3.
3.1 Description of Steel Mill Sinter Plants
The following sinter plant description has been taken
largely from a report prepared for EPA by National Steel Corpora-
tion entitled Sinter Plant Windbox Gas Recirculation System
Demonstration (PE-179).
The function of sintering, in the steel industry,
is to convert iron-bearing raw materials of a fine particle
size into coarse agglomerates by partial fusion. The sinter
product has a porous cellular structure resembling clinker
in physical appearance. Its composition may be substantially
different from that of the original iron-bearing fines.
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Blast furnace sinter is categorized as acidic or basic,
depending on the basicity ratio. The basicity ratio is defined
by the following equation:
Basicity Ratio - Wt Percent CaO + Wt Percent MgO
Wt Percent Si02 + Wt Percent A1203
Sinter with a basicity ratio of less than 1.0 is acid and
that with a ratio greater than 1.0 is basic. It has become
common to refer to sinter with a basicity ratio of approximate-
ly 1.0 as self-fluxing, while ratios in excess of 1.0 may be
called burden-fluxing or superfluxed sinter. Acid sinter of
basicity less than 0.5 was the predominant product used as blast
furnace feed until the early 1950's. It was then realized that
both economic and productive benefits to the blast furnace
could be realized by incorporating in the sinter a part or all
of the required furnace flux. This was achieved by the addi-
tion of limestone and/or dolomitic fines to the ore fines to
be sintered.
3.1.1 Process Description
In the sintering process, a shallow bed of fine par-
ticles is agglomerated by heat exchange and partial fusion of
the quiescent mass. Heat is generated by the combustion of a
solid fuel contained within the bed of fines being agglomerated.
The process is initiated by igniting the fuel at the top sur-
face of the bed, after which a thin, high temperature combustion
zone is drawn downward through the bed by an induced draft.
Within this zone, the surfaces of adjacent particles are at a
fusf.on temperature and the gangue constituents form a semi-
liquid slag. The flow of volatiles and incoming air creates a
frothy condition and freezes the trailing edge of the advancing
fusion zone. The product then consists of particles of ore
bonded in a slag matrix of cellular structure.
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In the ferrous industry, the material to be sintered
consists essentially of a mixture of iron-bearing fines and a
solid fuel. The iron-bearing constituents are chiefly iron
ore fines, recycled sinter fines and blast furnace flue dust,
but may also include mill scale, and other steel mill waste
products containing iron. Coke breeze is the most common solid
fuel, but other carbonaceous materials are used. It has become
common practice to add limestone or dolomitic fines to the
sinter mix and this material may now be considered as an essen-
tial constituent in a typical sinter mix. Sinter-mix composi-
tions for three different U.S. steel mill sinter plants are
shown in Table 3-1 (VA-126). This mixture of fine material is
placed on the sinter strand in a shallow bed, seldom less than
152 mm (6 inches) nor more than 508 mm (20 inches) in depth.
In the ignition zone, the surface of the bed is heated to about
1260 to 1371°C (2300-2500°F), combustion of the fuel is initia-
ted, and fusion of the fine particles at the surface begins.
As air is drawn through the bed, the high temperature zone of
combustion and fusion moves downward through the bed and pro-
duces the bonded, cellular structure.
Combustion of the solid fuel and propagation of the
fusion zone through the bed is dependent on the air flow. To
assure an adequate air flow, the sinter mix is generally pre-
conditioned to improve its permeability. This can be accom-
plished by eliminating excessively fine materials when economi-
cally possible, but is normally achieved by the addition of
coarse [12.7 mm by 3.2 mm (% inch by V8 inch)] sinter returns
and by fluffing and/or micropelletizing the fine particles in a
balling drum.
The design and physical arrangement of sintering
equipment and the flow pattern of raw materials and product
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TABLE 3-1
SINTER-MIX COMPOSITION
( weight percent)
Sinter-Mix Components
Plant 1
Plant 2
Plant 3
Iron Ore
Dry blast-furnance dust
Blast-furnance filter
cake
Melt-shop slag
Rolling-mill scale
Basic-oxygen-furnance
dust
Miscellaneous dust
Limestone or dolomite
Coke
Total
29.1
1.3
15.8
6.5
11.5
3.5
0.0
28.2
4.1
100.0
82.0
0.0
0.0
15.0
3.0
100.0
49.5
5.6
4.9
0.0
7.6
0.0
6.7
20.8
4.9
100.0
Source: VA-126
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differ considerably between various plants. The choice of
equipment and material flow is generally determined by the
desired capacity, space available, capital costs, and prevailing
technology. However, each plant can be divided into three
distinct phases of operation, namely, (1) raw materials
processing, (2) sinter production and (3) product processing.
A schematic flow diagram of a typical modern sinter plant is
shown in Figure 3-1.
This schematic flow diagram is typical of a modern
sinter plant. Many of the older plants lack certain features,
such as hot and/or cold screens, balling facilities, sinter
breakers, coolers, and flexibility in materials handling. Some
of the newest plants have special process control features to
reduce the variation in the sinter product. Examples of the
new control technology being applied to sinter plants are:
(1) automatic raw material proportioning systems, and (2) com-
puter control of the process.
^ A typical sinter plant strand normally operates
at full load except for start-up. The induced draft fan that
pulls air through the sinter bed maintains a uniform suction
pressure. This results in a fairly uniform gas flow through
the sinter bed. The frequency of shutdown depends on the con-
dition of the plant. in a well run sinter plant the operator
would plan on running all week without an unscheduled shutdown.
Scheduled shutdowns for a well run sinter plant are about one
eight-hour shift every week (JA-136).
3.1.2 Process Developments
Most sinter plants are operated in a .similar manner,
differing primarily in the characteristics of the raw materials
which must be processed and the basicity ratio chosen for the
sinter product. The general trend in materials used for sin-
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o
I
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i 11
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i ' i ' - -
~" ^ S — "N HOT RETURNS
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Figure 3-1 Schematic flow diagram for typical modern sinter plant
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tering has been toward less iron ore fines and more iron-bear-
ing waste materials such as mill scale, ironmaking dusts and
slags. Fluxstone additions have increased with the trend
toward higher sinter basicities. Table 3-2 shows the trend in
sinter feed materials between 1960 and 1968. The increased use
of mill scale, cinder and slag, other materials which are pri-
marily recyclable iron-bearing fines, and fluxstone is evident.
The reduction in the use of blast furnace flue dust and sludge
is due to improved blast furnace burdens.
A major factor influencing sinter plant operation
has been the trend toward higher sinter basicities. In 1962,
only about 40 percent of the sinter produced had a basicity
ratio in excess of 1.0. At the present time, available data
indicate that at least 85 percent of the sinter produced in
the United States and Canada has a basicity in excess of 1.0.
Moreover, at least six sinter plants regularly produce sinter
with a basicity ratio greater than 3.0 and one plant in excess
of 4.0. Increasing the sinter basicity generally reduces pro-
duction capacity but increases the strength of the sinter
product. Improved sinter quality reduces the quantity of fines
to be recycled in the sinter plant and decreases the flue dust
and sludge generated at the blast furnace. Higher basicity
sometimes improves sinter strand operation and reduces the
production and emission of fine dusts.
A new development in sinter plant operations is the
practice of recirculating a portion of the windbox flue gas.
Development work, including installation and operation of a
windbox recirculation system, has been performed by the National
Steel Corporation, Wierton Steel Division, and the Aliquippa
Works of Jones and Laughlin Steel Corporation. The recirculating
system at Wierton is designed with four duct valves which permit
a once-through operation of recirculation rates ranging from 0-50
percent. A recirculation rate of 39 percent was calculated
to be the maximum recycle amount because of the rapidly de-
creasing oxygen content in the recirculated gas, and the large
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TABLE 3-2
MATERIALS USED IN THE PRODUCTION OF SINTER AT STEEL PLANTS IN THE
UNITED STATES
MATERIAL
Iron Ore
Flue Dust &
Sluc.ge
Scale
Cinder and Slag
Other
Flux£;tone
Fuel
1960
a) 35,900
b) 36,500
c) 74
5,200
5,300
11
980
1,000
2
49
50
.01
490
500
1
3,740
3,800
7
2,360
2,400
5
Year
1964
39,370
40,000
69
4,530
4,600
8
2,170
2,200
4
394
400
1
1,080
1,100
2
5,800
5,900
10
3,250
3,300
6
1968
33,170
33,700
64
3,050
3,100
6
3,150
3,200
6
394
400
1
1,770
1,800
3
7,480
7,600
15
2,660
2,700
5
a) Thousands of metric tons
b) Thousands of gross tons
c) Percentage of mix
Source: PE-179
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rate of increase in fan horsepower with increasing recycle
percentage.
The windbox recirculation system offers the folloxvdng
potential advantages as reported by Wierton (PE-179):
(1) reduction in quantity of gases to be
cleaned,
(2) reduction in capital investment for gas
cleaning equipment,
(3) reduction in total emissions to the atmosphere
for a given dust concentration,
(4) reduction in hydrocarbon content of the
exhaust gases,due to more complete combustion, and
(5) conservation of energy from recirculating
hot gases.
Because of the potential advantages to be gained
from operating in a windbox recirculation mode, data from the
Wierton Steel Division operations have been used to prepare a
conceptual design of a limestone scrubbing system to treat
S02 emissions. Results of this conceptual design will be
compared against a design of a limestone system for treating
a sinter plant waste stream without windbox recirculation.
3.1.3 Sinter Plant Emissions
Before discussing sinter plant emissions it should
be mentioned that every sinter plant is a special case. They
are all different, having different feed compositions, making
it difficult to define a typical sinter plant.
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Emissions from sinter plants include particulates,
condensable aliphatic hydrocarbons, and gaseous components such
as sulfur dioxide, carbon monoxide, and chlorides. Table 3-3
shows the particulate compositions for the three steel mill
sinter plants whose sinter mix compositions were given in Table
3-1. The size distribution for particulates emitted from the
main exhaust system of several sinter plants is given in Table
3-4.
Gaseous emissions from sinter plants include
significant amounts of carbon monoxide and sulfur oxides.
Typical concentrations of gaseous emissions from steel mill
sinter plants are given in Table 3-5. Other gaseous components
that are present in smaller amounts include nitrogen oxides,
chlorides, and fluorides.
Emissions from a sinter plant with windbox recircula-
tion vary from those of a sinter plant without recirculation.
The major environmental effects of gas recirculation are an in-
crease in the concentration of SC>2 in the exhaust gas, and a
decrease in both hydrocarbon and particulate emissions. In
both modes of sinter plant operation, the same quantity of
sulfur is oxidized to produce S02. Therefore, although the
concentration of SOz will increase in the recirculation case,
the total quantity of 862 emitted for both cases will remain
the same. The advantage gained by using a gas recirculation
system is that the total gas volume to be processed is reduced
thereby reducing the size and capital and operating cost of
required emission control equipment.
Hydrocarbon emissions will be reduced as the hydro-
carbons in the recycle stream will pass back through the flame
zone to be combusted. The particulate concentration should be
the same for both cases, although the windbox recirculation case
will produce less total particulate emissions. The stream com-
positions used as a basis for the limestone scrubbing design are
presented and discussed in Section 4.1 - Design Basis and
Assumptions.
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TABLE 3-3
COMPOSITION OF P ARTICULATE
Particulate Component
Fe 0
CaO
MgO
K20
Si02
A1203
Na20
ZnO
MnO
Chlorides
Sulfates
Hydrocarbons
Other
Loss on Ignition
Total
(weight percent)
Plant 1
33.9
7.1
5.3
5.2
4.8
2.6
1.6
0.4
0.2
8.5
7.5
7.4
1.6
13.9
100.0
EMISSIONS
Plant 2
11.7
10.9
0.4
0.6
2.4
4.3
0.3
0.1
0.1
3.0
16.5
36.9
0.0
12.3
100.0
Source: VA-126
Plant 3
28.0
15.0
2.0
8.1
4.6
2.5
0.0
0.0
0.0
8.8
2.1
0.0
0.0
28.9
100.0
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TABLE 3-4
• SIZE DISTRIBUTION OF PARTICULATE EMISSIONS
Size gradin
Plant
A
B
C
D
K
g of dust from sinter plant main
Size, microns
295 211 152 104 76
84 71 54
95 90 79
96 88 73
75 64 53
96
89
63
78
37
58
52
40
88
51
65
25
33
38
29
76
exhaust
53 40
43
55
18
18
31
22
61
50
39
50
16
14
25
17
46
gases, %
30 20
41
34
44
14
8
21
13
35
33
26
33
10
6
13
8
25
undersize
10 5
19
14
17
6
2
5
3
13
7.5
5
7
2
--
--
--
6
Source: BA-449
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TABLE 3-5
TYPICAL CONCENTRATIONS OF GASEOUS EMISSIONS FROM
STEEL MILL SINTER PLANTS
Component
°2
CO
CO,
H2°
SO
Condensable Hydrocarbons
Mole Percent
72.4
14.5
0.7
6.3
6.1
25 - 1000*
693**
* ppm
mg/NnT
Source: PE-179
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A sulfur balance for a sinter-machine operation is
given in Table 3-6. The major sources of sulfur are the iron-
bearing materials and the coke. The fuel oil used for igniting
the sinter mix and the limestone used as a flux also contain
some sulfur. Sulfur is carried out of the system with the
product sinter and as S02 in the combustion gases. It was
estimated that aobut 36 percent of the sulfur entering with the
sinter feed left in the combustion gases (VA-003) . It should
be realized that the sulfur balance presented here was made
for a specific case. Sinter feeds with different compositions,
basicity ratio, and using a different type of fuel for igniting
the sinter bed can have a sulfur balance that is much different.
3. 2 Description of the Lime/Limestone Wet Scrubbing
Process
The lime/limestone flue gas desulfurization process
uses a slurry of calcium oxide or calcium carbonate to absorb
S02 in a wet scrubber. This process is commonly referred to
as a "throwaway" process because the calcium sulfite and sul-
fate formed in the system are disposed of as waste solids. The
overall reactions in the system are as follows.
For lime systems:
S02/ N + CaO,gx + %H20 + CaS03 -%H20(s) (3-1)
For limestone systems:
S02 ^ , + CaC03,. + %H20 •* CaS03-%H20,s) + C02 , .
(3-2)
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CORIPORAV9QN
TABLE 3-6
SULFUR BALANCE FOR SINTER MACHINE OPERATION
Basis: The production of one metric ton of sinter
Sulfur Content Amount of Sulfur
Material Amount (kg) (wt. percent) (kg)
INPUT:
Iron-bearing 1,100 0.041 0.45
Material
Coke
Oil
Limestone
50
25
100
0.70
0.55
0.049
0.35
0.14
0.05
0.99
OUTPUT:
Sinter 1,000 0.055 0.55
Sinter Fines 144.5 0.055 0.03
Sulfur in 0.36
Combustion Gases
0.99
Source: VA-003
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Some oxygen will also be absorbed from the flue gas or
surrounding atmosphere and will cause oxidation of absorbed
S02 and formation of calcium sulfate.
For limestone systems:
Ca + S03 + %02 + 2H20 + CaS04•2H20(g)
(3-3)
The calcium sulfite and sulfate crystals are precipitated in a
hold tank and then sent to a solid/liquid separator where the
solids are removed. The waste solids are generally disposed
of by ponding or landfill.
3.2.1 Process Description
The basic design of a lime or limestone scrubbing
system can be divided into the following process areas:
(1) S02 Absorption,
(2) solid separation, and
(3) solids disposal.
Figure 3-2 shows a generalized process flow diagram for the
lime/limestone slurry scrubbing processes.
S02 Absorption
Absorption of S02 takes place in a wet scrubber using
lime or limestone in a circulating slurry. Carbide sludge
(impure slaked lime) has also been used successfully at two
installations. Particulates can be removed in the S02 absorber
or ahead of the absorber by an electrostatic precipitator or
particulate scrubber. The selection of a method for removal of
particulates is based on economics and operational reliability.
Removing particulates in the SOa absorber increases the solids
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REHEATER
FAN
S02 ABSORBER r
FLUE GAS
ISTR,
STEAM
•*- MAKE-UP WATER
LIME
OR
LIME-_
STONE"
SLURRY
I
htl
CRUSHING
AND
GRINDING
SLURRY
EFFLUENT HOLD TANK
TO STACK
>•
FIGURE 3-2. PROCESS FLOW DIAGRAM LIME/
LIMESTONE WET SCRUBBING
SECOND STAGE
SOLID-LIQUID
SEPARATOR
OR
SETTLING POND
SOLID-LIQUID
SEPARATOR
I
SOLID WASTE
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CORPORATION
load in the S02 scrubbing system. It is also believed that some
components of the fly ash catalyze the oxidation of sulfite to
sulffite which increases the potential for sulfate scaling.
The absorption of S02 from the flue gases by a lime
or limestone slurry constitutes a multiphase system involving
gas, liquid, and several solids. The overall reaction of gas-
eous SOj with the alkaline slurry yielding calcium sulfite and
sulfate has been shown in Equations 3-1, 3-2, and 3-3. The
solid sulfite is only very slightly soluble in the scrubbing
liquor and thus will precipitate to form an inert solid for
disposal. In the lime system some C02 may also be absorbed
from the flue gas and will react in a similar fashion to form
solid calcium carbonate.
In most cases some oxygen will also be absorbed from
the flue gas or surrounding atmosphere. This leads to oxidation
of absorbed S02 and precipitation of solid calcium sulfate as
was shown in reaction 3-3.
The extent of oxidation can vary considerably,
normally ranging anywhere from almost zero to 40 percent in the
electric utility industry. In some systems treating dilute S02
flue gas streams, sulfite oxidation rates as high as 90 percent
have been observed. In sintering operations, where the oxygen
content of the flue gas is as high as 16 volume percent, sul-
fite oxidation rates of 100 percent have been reported. The
actual mechanism for sulfite oxidation is not completely under-
stood. The rate appears to be a strong function of oxygen con-
centration in the flue gas and liquor pH. It may also be in-
creased by trace quantities of catalysts in fly ash entering
the system.
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Various types of gas-liquid contactors can be used as
the S02 absorber. These differ in S02 removal efficiency as
well as operating reliability. Four general types of contactors
are usually used for S02 removal:
(1) venturi scrubbers,
(2) spray towers (horizontal and vertical),
(3) grid towers, and
(4) mobile bed absorbers [such as marble bed
and turbulent contact absorber (TCA)].
The liquid to gas ratio (L/G) generally ranges between
4.7-14.7 liters/Nm3 (35-110 gal/1000 scf) depending upon the
type of contactor. Simple impingement devices are placed
downstream from the absorber to remove mist entrained in the
flue gas.
The effluent hold tank receives the lime or limestone
feed slurry and absorber effluent. In addition, settling pond
water and clarifier overflow can be sent to the hold tank. The
volume of the hold tank is sized to allow residence time for
adequate calcium sulfite and sulfate precipitation. Reaction
time outside the scrubber is needed to allow the supersaturation
caused by S02 sorption in the sorber to dissipate and to permit
dissolution of absorbent. Too little residence time in the
hold tank can cause calcium sulfite or sulfate scaling in the
system.
The feed material for a lime scrubbing process is
usually produced by calcining limestone. Feed for a limestone
process generally comes directly from the quarry, and is then
reduced in size by crushing and grinding. The lime or limestone
is mixed with water to make a 25-60 percent solids slurry.
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Solids Separation
A continuous stream of slurry of 10-15 percent solids
is recycled to the absorber from the effluent hold tank. In
addition, a bleed stream is taken off to be dewatered. The
dewat.ering step, which is needed to minimize the area needed
for sludge disposal, varies depending on the application and
type of disposal. The waste sludge contains some unutilized
lime or limestone. This depends upon system design (additive)
stoichiometry). Generally, more excess additive is required in
limestone systems than in lime systems.
For systems with on-site pond disposal, solids may
be pumped directly from the effluent hold tank to the pond
area. Clean overflow liquor from the pond would then be re-
turned to the system. Depending on the physical properties
of the solids produced in the system, a thickening device such
as a clarifier can be used to increase the solids content to a
maximum of about 40 weight percent. Additional dewatering to
60-70 percent solids can sometimes be achieved by vacuum
filtration.
Solids Disposal
Sludge disposal is one of the main disadvantages
of lime/limestone FGD systems in comparison to regenerable FGD
processes. The quantity of sludge produced is large in both
weight and volume, and requires a large waste pond or landfill
area for disposal.
On-site disposal is usually performed by sending the
waste* solids to a large pond. Settling of the solids occurs
and pond water is recycled back to the process hold tank for
reus<;. "Stabilization" methods are currently under development
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(CORPORATION
to convert the sludge to structurally-stable, leach-resistant,
landfill material. These methods could be used when on-site
disposal is not possible. The stabilized material can then be
trucked to an off-site area for landfill.
At least four companies are developing sludge fixation
processes. A fixation process is currently employed to dispose
of the sludge generated by a limestone wet scrubbing system
installed on a 163 Mw unit at Commonwealth Edison's Will County
Station. The annual cost for sludge fixation is likely to be
higher than the lime or limestone raw material cost. Conversion
of the sludge to a construction material is another disposal
method under consideration.
3.2.2 Design Considerations
The flow rate and sulfur content of the sinter plant
flue gas are the major parameters to be considered in the lime
or limestone scrubbing system design. The quantities of lime or
limestone consumed and waste solids produced are roughly propor-
tional to the amount of sulfur in the gas. The tendency for
scale formation in the system is also related to the amount of
S02 removed from the gas. Since all of the S02 removed must
precipitate from solution before leaving the system, increased
crystal seed must be provided in proportion to the amount of
S02 removed. The scrubber liquid to gas ratio would have to be
increased for removal of high S02 concentrations and to avoid •
exceeding the scaling limits in the scrubber effluent liquor.
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CORPORATBON
Gas-Liquid Contactors
The different types of gas-liquid contactors can be
separated into two categories; those having an open configura-
tion and those having a closed (packed) configuration. These
gas-liquid contactors differ in their gas velocity, L/G ratio,
gas-£iide pressure drop, and resistance to plugging. These
characteristics will be discussed for the different scrubber
types.
Depending on the scrubber type, SOz removal efficiency
may be increased by:
(1) increasing the number of scrubber stages,
(2) increasing the contacting area per stage
(usually increases gas-side pressure drop),
(3) increasing scrubber liquor to gas ratio,
and
(4) increasing lime or limestone utilization.
Some of these design measures not only affect S02 removal but
also affect the scaling tendency of the system.
The most frequently used contactors for S02 removal
are :
(1) venturi scrubbers,
(2) spray towers (horizontal and vertical),
(3) grid towers, and
(4) mobile bed absorbers (marble bed, TCA
packed column).
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The performance characteristics of each of these types of
scrubbers are listed in Table 3-7.
Any of these scrubbers could be applied for both gas
absorption and particulate removal, however packed columns
show a much greater tendency for solids plugging. Resistance
to plugging is an important parameter in scrubber selection.
The open configuration of the spray tower gives it a lower gas-
side pressure drop and makes it less susceptible to plugging
when compared to the closed configuration of the marble bed and
TCA scrubbers.
The volume of flue gas to be treated normally
determines the physical size of the scrubbing device. The
minimum and maximum velocities selected vary widely among the
scrubber types but generally fall in a range of 1.5-7.6 ra/sec
(5-25 ft/sec). The highest gas velocities occur when using a
venturi due to the small diameter of the venturi throat. These
high velocities, however, must be decreased before the gas enters
the process mist eliminators.
Absorber Operation
The amount of slurry circulated is critical. If the
liquid to gas ratio is too low, the slurry will absorb too much
S02 per volume and critical supersaturation will occur.
Crystallization will then take place in the scrubber rather than
in the reaction tank. The minimum L/G generally ranges between
4.7-14.7 liters/Nm3 (35 and 110 gal/1000 scf), depending on
inlet SOz concentration, type of scrubber, and lime or limestone
reactivity. The lowest L/G's are used for venturi scrubbers
and mobile bed absorbers such as marble beds. High L/G's are
common in spray columns while TCA's generally use mid-range
values. In general, L/G ratios are higher for limestone sys-
tems than they are for lime systems due to limestone's lower
reactivity.
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TABLE 3-7
oo
i
COMPARISON OF SCRUBBER TYPES FOR A LIMESTONE WET SCRUBBING SYSTEM
Scrubber Type
Parameter
SOj Removal Efficiency
Particulate Removal Efficiency
Typical L/G (gal/1000 scf)
for SOz Removal
Gas Side Pressure Drop (in H20)
for L/G Above
Gas Velocity (ft/sec)
Dissolution of Solids
Resistance to Solids Plugging
Marble Bed
Good
Good
40-70
8-12
3-8
Good
Fair
TCA
Good
Good
50-80
6-12
6-11
Fair
Good
Venturi
Fair
Excellent
20-50
8-20
125-300
Poor
Excellent
Grid Tower
Good
Good
50-100
1-7
6-11
Fair
Fair
Spray Tower
Good
Fair
70-110
1-3
5-25
Poor
Excellent
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Both calcium sulfite and calcium sulfate form scales.
Calcium sulfate can form supersaturated solutions in the
scrubber system. The rate of scaling is sensitive to the super-
saturation of calcium sulfate. Test results from the TVA
Shawnee test facility have shown that scrubber internals can
be kept relatively free of scale if the sulfate (gypsum) satu-
ration of the scrubber liquor is kept below about 135 percent
(at 50°C). If supersaturation is unchecked, calcium sulfate
dihydrate starts to crystallize on solid surfaces, forming a
scale. The supersaturation can be controlled by seeding
the liquid with calcium sulfate dihydrate crystals , xvhich pro-
vide a large surface area on which the dissolved salts preferen-
tially deposit.
Evidence has also been encountered that coprecipita-
tion of calcium sulfite and sulfate may occur. This phenomenon
may enable operation of the process in a mode where calcium
sulfate concentration will not reach its normal saturation level
and thus will not form sulfate scale. Operation in this mode
seems to depend on the. level of oxidation occurring in the system.
Changes in liquor pH can also cause scaling. The
solubility of calcium sulfite decreases with increasing pH.
If the pH is allowed to fall below 5, comparatively soluble
calcium bisulfite is formed. With a subsequent increase in
pH value, the bisulfite is converted to calcium sulfite which,
being less soluble, crystallizes out and forms scale.
The pH of a freshly prepared limestone slurry is
usually between eight and nine. On contact with the S02 in the
flue gas the pH rapidly falls below seven, but below pH six the
decrease in pH is slow until the slurry is exhausted. The effi-
ciency of S02 removal is not appreciably affected until the pH
drops below about 5.2. The effect appears to be independent
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of the type of limestone. Limestone scrubbers usually operate
with an inlet and outlet pH range between 5.2-6.4. The scrub-
ber pH can be changed by varying the limestone feed.
Mist Elimination
Mist eliminator operation has been a major trouble
spot in lime/limestone scrubbing. All wet scrubbers introduce
mist droplets into the gas, some more than others. The mist
must be collected and separated to prevent corrosion and solid
deposits on downstream equipment and to avoid high energy con-
sumption in evaporating the mist in the gas reheater. Since
the drops are relatively large, usually 40 microns and larger,
they can be removed effectively by simple impingement devices,
such as zig-zag baffles (chevrons) or cyclonic demisters.
Practically all designers have used chevrons with the major
exception being Detroit Edison, where a cyclonic vane-type
eliminator was installed.
Chevrons have had trouble with both inefficient
mist removal and with plugging by soft deposits and scale.
Almost complete mist elimination by chevrons has been achieved
by mounting them in a slanted or vertical position instead of
the usual horizontal position so that the liquor can drain off.
This prevents re-entrainment of the liquor in the gas. Plug-
ging and scaling of mist eliminators can be prevented by washing
with fresh water. Intermittent washing with a high pressure
soot-blower type spray has been more successful than a lower
pressure continuous wash. Wash trays and wet electrostatic
precipitators have also been used as part of the mist elimina-
tion system. A wash tray is placed under a horizontal chevron
to remove solids in the entrained mist and to collect wash liquor
flowing off the chevron. Wet electrostatic precipitators remove
both mist and residual dust in the flue gas.
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CORPORATION
Sludge Dewatering
The sludge dewatering step is used to concentrate the
solids for ease of handling and disposal and to lower transpor-
tation costs. The clear liquor is usually recycled back to the
process for reuse. Sludge dewatering methods consist of clari-
fication, bed drying, centrifugation, vacuum filtration, and
thermal drying. In addition to these methods, interim ponding
is sometimes used as a dewatering procedure. The settling
characteristics of the sludge determine the effectiveness of
this technique.
Clarifiers are presently used in S02 removal systems
as a primary dewatering device when the solids content of the
sludge is low. Limestone scrubber sludges containing unreacted
additive are reported to thicken well compared to lime sludges
because of the coarse limestone present. Limestone processes
sometimes produce a turbid supernatant liquor.
Because of the physical nature of sulfate crystals
as opposed to sulfite, dewatering is improved by a higher
sulfate/sulfite ratio. Therefore, good results (85-90 percent
solids) have been reported for a sample obtained from the
Chiyoda process, which produces in a sludge with an extremely
high sulfate to sulfite ratio.
One engineering company currently markets an S02/
fly ash control process using a sludge dehydration operation
after an alkali scrubbing system. Clarifier underflow at 30
percent solids concentration is raised to 90-95 percent solids
by passing the slurry through a dehydrator co-current with the
hot flue gases (300°F).
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CORPORATOON
3.2.3 Typical Operations Relating to Sinter Plants
Lime/limestone wet scrubbing should require no new
technical modifications for application to steel mill sinter
plants. Sulfur oxide levels in the sinter plant effluent gas
(25-1000 ppm) are in the same concentration range as effluent
gas from oil and coal-fired boilers where the majority of the
FGD systems have been installed. The oxygen content of the
gas (12-16 mole percent) is about two to three times higher
than that usually encountered from utility boilers. The higher
oxygen concentration in the effluent gas should result in a
high rate of calcium sulfite oxidation. This has proved to be
the case from Japanese experience (see Appendix B) where 30-
100 mole percent of the calcium sulfite was oxidized to calcium
sulfate in the different FGD units.
The significant amounts of carbon monoxide (about
0.5-1.0 mole percent) should have no effect on the FGD system
because of its relative stability. The water content of sinter
plant gas generally ranges between 5-10 mole percent. The gas
will evaporate large amounts of water from the initial liquid
contacting device as is the case where FGD scrubbing is applied
to utility boilers.
The particulate concentrations found in the gas are
no higher than those commonly found on coal-fired boilers. High
particulate removal efficiencies (over 95 percent) should be
easily achieved by a particulate prescrubber such as a venturi.
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The unburned hydrocarbons carried by the effluent
gases are not normally encountered on oil or coal-fired utility
boilers. A particulate scrubber will remove some of the hydro-
carbons but the hydrocarbon removal efficiency by wet scrubbing
has not been conclusively determined. Most of the hydrocarbons
are aliphatic and will act as an inert in a wet scrubbing system.
The addition of windbox gas recycle systems to sinter plants is
expected to help control hydrocarbon emissions. It has been es-
timated that the recycle system at Wierton will reduce the con-
centration of unburned hydrocarbons in the effluent gases by 50
percent (CU-055).
3.3 Evaluation of USSR and Japanese Data
Data concerning FGD systems being used to treat waste
gases from steel mill sinter plants in Russia and Japan xcere
received and evaluated. The Soviet data for one limestone
FGD system and the Japanese data for four FGD systems were
summarized and examined for consistency with previous U.S. lime/
limestone scrubbing experience. Technical notes describing
these evaluations in detail, along with the actual Russian and
Japanese data, are contained in Appendices A and B.
3.3.1 Summary of Russian Data
The Soviet data consisted of a description of the
process and a discussion of operating parameters for the lime-
stone scrubbing system applied to the Magnitogorsk sinter plant
The system removes 85 percent of the S02 and 50 weight percent
of the particulates. A computer simulation was performed by
using the given operating parameters and making several neces-
sary assumptions to fill voids where information was lacking.
Several results were found from the given data and the .computer
simulation.
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(1) Oxidation was only 25 percent with a flue
gas oxygen concentration of 15.9 percent.
(2) The SO 2 concentration in the flue gas was
1600 ppm. This is higher than the average
concentration of 200 ppm believed to be found
in U.S. sinter plant operations (ST-368, WO-092)
(3) The reported inlet and outlet particulate
concentrations were 200 g/Nm3 and 100 g/Nm3
j
respectively. This is much higher than con-
centrations normally found on coal-fired
boilers (4.6-16 g/m3) or reported values
for U.S. sinter plants (^ 1 g/Nm3). It was
concluded that the particulate concentrations
were probably incorrect due to misplaced
decimal points. The actual values were
probably 2 g/Nm3 and 1 g/Nm3 for the inlet
and outlet flue gas particulate concentra-
tions, respectively.
(4) The large particulate concentrations used in
the process simulation model caused calcium
sulfate to be subsaturated in the scrubbing
system. The Soviets reported that 10 weight
percent of the calcium value of the sludge
was calcium sulfate.
(5) It was not considered worthwhile to make
further calculations on the assumed error
listed in (3) above.
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3.3.2 Summary of Japanese Data
The Japanese data consist of process•descriptions and
discussions of operating variables for four FGD processes
applied to treating waste gases from steel mill sinter plants
in Japan. The processes are:
(1) Kawasaki Steel, Mitsubishi Heavy Industries
(MHI) Process;
(2) Sumitomo Metal, Moretana Process;
(3) Kobe Steel Calcium Chloride (Cal) Process;
(4) Nippon Steel Slag (SSD) Process.
Two of the processes, the MHI and Moretana Processes, use a
conventional lime or limestone absorbent. The Cal Process
uses a lime absorbent in a 30 percent calcium chloride solution.
The SSD Process uses a 40 weight percent CaO converter slag as
an absorbent. A summary table showing all of the FGD processes
that operate on Japanese steel mill sinter plants is included
in the Japanese data found in Appendix B.
Several important findings were obtained from the
Japanese data.
(1) The oxidation of calcium sulfite to sulfate
in the scrubber was reported to be between
50-100 percent for the conventional lime/
limestone absorbent processes.
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(2) The S02 concentration in the flue gas
fluctuated between 800-1200 ppm every 20
minutes. High and stable S02 removal was
still obtained under these conditions.
(3) An inlet HC1 concentration of 20-50 ppm in
the flue gas was reported. High chlorine
concentrations in wet scrubbing systems can
cause corrosion.
(4) The oily matter in the incoming flue gas
necessitated the use of oil resistant rubber
linings to prevent swelling.
(5) S02 removal efficiencies of over 90 percent
were reported for inlet S02 flue gas con-
centrations of 200-1200 ppm.
(6) Absorbent utilizations of 95 percent for
lime and 80-85 percent for limestone were
obtained.
Results from the evaluation of Russian and Japanese
data were used to establish criteria for designing a limestone
scrubbing system to treat waste gas from U.S. sinter plants.
Section 4.0 describes, in detail, the approach used to design
the limestone scrubbing system.
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CORPORA73ON
4.0 DESIGN APPROACH
Computer simulations were used to prepare conceptual
process designs of limestone scrubbing systems for sinter plant
applications. The Radian process model, a group of computer
programs for simulating aqueous inorganic chemical processes,
was used for these simulations. The process model performs
calculations based on (1) chemical reaction rate and equilibrium
calculations, and (2) process and equipment data which define
the process flow scheme and characterize each of the individual
process units. A thorough description of the Radian process
model is provided in Appendix C.
Several information sources were utilized during this
program to develop design data for input to the limestone pro-
cess model. The open literature was screened to assemble avail-
able information. Mr. Richard Jablin was retained as a consul-
tant and proved to be a valuable source of information. Data on
a Russian sinter plant limestone process was obtained as a
result of an EPA sponsored US/USSR technology interchange agree-
ment. These data were evaluated to determine how best to
incorporate the Soviet operating experience into a process
design for U.S. sinter plants. A report describing Japanese
technology for controlling sinter plant S02 emissions, prepared
for Radian by Dr. Jumpei Ando, also provided valuable information,
Data from the above sources were evaluated to
determine realistic design parameters for use as input to the
computer model. A design basis for both a sinter plant and
a limestone scrubbing system was determined. Section 4.1 des-
cribes in detail the design bases chosen for these systems.
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Results of the conceptual designs were then used to
size process equipment. An economic basis was selected and
applied to the process designs to perform an evaluation of both
capital investment and annual operating costs. A detailed de-
scription of the economic basis of this design is presented in
Section 4.2.
4.1 Design Basis and Assumptions
A conceptual design basis for a limestone scrubbing
system to remove S09 from steel mill sinter plant waste gases
was developed from several sources. These included:
(1) an evaluation of U.S. steel mill sinter
plant operations and typical emissions,
(2) a comprehensive technical data base
developed by Radian in the area of
lime/limestone wet scrubbing technology,
and
(3) an evaluation of operating lime/limestone
wet scrubbing systems in the USSR and
Japan.
Data describing both sinter plant emissions and limestone
scrubbing operations were evaluated to establish a realistic
basiis for the conceptual design. Sections 4.1.1 and 4.1.2
discuss the sinter plant and limestone scrubbing design param-
eter;; used as input to the computer model.
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CORPQS9A78QN
4.1.1 Sinter Plant Design Basis
The sinter plant design basis was developed from an
EPA report describing the engineering and design of a sinter
machine windbox gas recirculation system (PE-179). The No. 2
sinter machine of the Wierton Steel Division in Wierton, West
Virginia, was the subject of that report. Two conceptual designs
were developed from the Wierton report, one for standard sinter
plant operation and one for a sinter plant with windbox gas re-
circulation. The recirculation of windbox effluent gas has the
advantage of substantially reducing the volume of gas emitted
from the sinter plant, thus reducing the amount of gas to be
cleaned. In addition, recirculating a portion of the windbox
effluent gas to the sinter strand allows unburned hydrocarbons
in the gas to be combusted in the second pass through the sinter
bed. The concentration of particulates in the effluent gas
remains essentially unchanged but the amount of particulates
leaving the system is reduced due to the reduced gas volume.
These advantages make sinter machine windbox gas recirculation
an attractive method for meeting future emission regulations.
Therefore, a design of a scrubbing system for a plant with wind-
box gas recycle was performed in order to further identify the
advantage of a gas recirculation system over a standard sinter
plant operation.
The design basis chosen for the two plants is given
in Table 4-1. Both sinter machines produce 6312 mtpd (6958 tpd)
of sinter product. Sinter production in the U.S. ranges from
1350 to 9100 mtpd (1,500 to 10,000 tpd) for individual sinter
strands (JA-136). The parameters for Case 1 (standard operation)
are all taken from operating performance data for the Wierton
No. 2 sinter machine except for the sulfur dioxide concentration
in the gas. The actual S02 concentration in the gas from the
sinter machine was less than 100 ppm. Since this concentration
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TABLE 4-1
Parameter
Dry Gas "
Total Gas
Gas Moisture Content
Gas Composition (Dry)
S02 Concentration (Dry)
Particulates (Dry)
Ccndensible . .
Hydrocarbons (.Dry;
Gas Temperature
SINTER PLANT DESIGN BASIS*
Case 1
(Standard Operation)
633,600 Nm3/hr
674,784 Nm3/hr
6.1 vol. 7o
Vol. %
N2 77.1
02 15.4
CO 0.8
COz 6.7
750 ppm
923 mg/Nm3
738 mg/Nm3
139'C (282'F)
Case 2
(39% Windbox Gas Recycle)
386,640 Nm3/hr
422,640 Nm3/hr
8.5 vol. %
Vol. %
73.3
13.3
1.4
11.9
1200 ppm
923 mg/Nm3
369 mg/Nm3
219'C (426*F)
Based on 6312 mtpd sinter product.
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was already low, it was decided to assume an increased SC>2 con-
centration in the gas for design purposes.
Data from a U.S. sinter plant x^ith an S02 concentra-
tion of approximately 900 ppm (YO-042) were checked to insure
that the concentrations of other species in the gas such as N2,
02, and C02 would not be significantly changed by assuming a
higher SO2 concentration. No substantial change in concentra-
tion of the other species was found. Data from Soviet, Japanese,
and other U.S. steel mill sinter plants corroborated this con-
clusion.
An S02 concentration of 750 ppm was chosen as the
design basis for standard plant operations. Data from Soviet
and Japanese sources indicated that an S02 concentration of 750
ppm represented an average value from processing high sulfur
sinter mixes. Some sinter plants have concentrations that are
at least that level (YO-042).
The design parameters for the second case (39 percent
gas recycle on a dry basis) were taken from the design of a gas
recirculation system for the same Wierton No. 2 sinter strand.
The concentration of the unburned hydrocarbons was obtained from
conversations with Wierton personnel (CU-055), and is a rough
estimation.
The S02 concentration for the second case was calcu-
lated to be 1200 ppm (39 percent higher than for the standard
sinter plant case). It was assumed that' the amount of S02 evolv-
ed from the sinter strand would remain the same and that the S02
in the recycled gas would pass back through the sinter strand
without further reaction. Therefore, the total amount of S02
evolved for both cases would be equal, although the S02 concen-
tration of the gas evolved from the plant with windbox gas re-
circulation would be higher than for the standard operation case.
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An average of the three particulate compositions
presented in Table 3-3 was assumed for both cases. It was felt
that an average composition would be representative of the
wide variations in sinter plant particulate emissions. Emis-
sion:; variations are caused by differences in sinter plant
feed compositions. The particulate composition assumed for
this study is given in Table 4-2.
The effect of varying particulate compositions on the
operation and cost of a limestone scrubbing system should be in-
significant. The overall system change resulting from the CaO
and MgO content of the particulate material will be small since
limestone is added to the pre-scrubber liquor loop to insure the
desired S02 removal. The equipment in the pre-scrubbing section
of the system is all plastic-lined to prevent corrosion. There-
fore, differences in chloride content of the particulates will
not affect the corrosion rate.
Oxidation of calcium sulfite to calcium sulfate is be-
lieved to be increased by certain catalysts in the particulates
entering the system. Iron oxides are believed to be oxidation
catalysts. The change of iron oxide content in the different
particulate compositons could, therefore, change the amount of
oxidation in the pre-scrubber and SOa absorber. A system design-
ed for low oxidation could experience scaling problems if high
oxidation was actually encountered. Also, limestone sludge with
a hig;h sulfate concentration dewaters more easily than a sludge
with a low sulfate concentration. This would affect the size
of the clarifer.
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CORPORATBOM
TABLE 4-2
COMPOSITION OF PARTICULATES IN SINTER PLANT
FLUE GAS
Component Weight Percent
Fe203 24.5
CaO 11.0
MgO 2. 6
K20 4.6
Si02 3.9
A1203 3.1
Na20 0.6
ZnO 0.2
Chlorides 6.8
Sulfates 8.7
Hydrocarbons 14.8
Other ' 0.7
Loss on ignition 18.4
100.00
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The condensible hydrocarbon concentration used is
in the normal range for steel mill sinter plants. The hydro-
carbon concentration can vary to a large extent depending on the
amount of hydrocarbons in the sinter feed. No reported data was
found on the percentage of the hydrocarbons which are condensible
versus non-condensible. The hydrocarbons in the sinter feed come
primarily from oily turnings or from coke added as a fuel.
4.1.2 Limestone Scrubbing Design Basis
A limestone scrubbing system was selected instead of
a lime scrubbing system for two reasons.
(1) Limestone systems are generally less
expensive than lime systems, primarily
because limestone is much cheaper than
lime. Furthermore, lime prices are ex-
pected to escalate because of the cost
of calcining limestone.
(2) Most steel plants typically use limestone
in process operations and, as such, have
a readily available supply.
It was necessary to select both limestone and make-up
water compositions in order to simulate the limestone scrubbing
system. The limestone composition presented in Table 4-3 was
chosen based on previous pilot plant studies done by Radian.
The make-up water composition listed in Table 4-4 was decided
upon after conversations with Mr. R. Jablin (JA-137).
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CORPORATBON
TABLE 4-3
LIMESTONE COMPOSITION
Component Weight Percent
CaC03 97
MgC03 1
Inert 2
TABLE 4-4
MAKEUP WATER COMPOSITION
Parameter mg/1
Total Solids 261
Total Dissolved Solids 238
Total Suspended Solids 23
Alkalinity as CaCO., 76
SO^ . 80
Cl" 29
N03 2
HN3 0.7
pH 7.2
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Process Equipment
The following major equipment was included in the
design to insure efficient FGD system operations. The criteria
used for selecting each of these items is discussed below.
(1) Prescrubber
A venturi prescrubber was selected for sinter
plant applications for three -reasons.
(a) Flue Gas Cooling and Saturation - To
avoid evaporation of water from the
scrubber liquor and subsequent scale
formation at the inlet to the S02
absorber, the flue gas should be pre-
saturated.
(b) Chloride.Removal - The high chloride
concentrations in the flue gas would
cause corrosion problems in the S02
absorption system if not removed.
(c) Particulate Removal - An additional
benefit of using a venturi prescrub-
ber is removal of most of the parti-
culates entering the 862 scrubbing
system.
(2) Forced Draft Fan
A fan is needed to overcome the pressure drop
of the scrubbing system. The existing waste gas fan is designed
to handle sinter plant flue gas at high temperatures (up to
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175°C) and with a significant particulate
loading (^ 1 g/Nm3). No problems should be
incurred in installing an additional forced
draft fan to operate under these conditions.
Induced draft fans, which are installed
after the FGD system reheater have suffered
from corrosion due to scrubber mist carry-
over in the stack gas. Therefore, forced
draft fans were selected for this design.
(3) Spray.Tower S02 Absorber
A countercurrent vertical spray tower was
chosen as the gas/liquid contacting device
for S02 removal. This type of contactor
was chosen over other types of contactors
mentioned in Section 3.2. Spray towers have
an open configuration'which reduces the
possibility of scaling and solids plugging
in the scrubber.
(4) Ball Mill
A wet ball mill was placed in the FGD system
to grind large calcium sulfite and sulfate
crystals contained in a bleed stream of waste
sludge from the clarifier bottoms. The ground
crystals are recycled to the S02 absorber
hold tank to insure that an adequate number
of seed crystals are present to provide sites
for calcium sulfite and sulfate precipita-
tion. The formation of large sulfite and
sulfate crystals in the system can cause a
shortage of sites for precipitation. This can
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result in the relative saturation of calcium
sulfite and sulfate in the liquor to rise
above critical supersaturation values. The
addition of seed crystal sites reduces the
chances of scaling. Controlled seed crystal
recirculation is a Radian proprietary concept,
(5) Demister
A vertical chevron demister located in a
horizontal duct will be placed downstream
of the S02 absorber. This type of demister
has been shown to be effective in removing
entrained mist without experiencing plugging
problems. A high pressure mixture of fresh
water and clarifier overflow will be used
to intermittently wash the demister.
(6) Reheater
The reheater will be designed to heat the
stack gas to 79.4°C (175°F) for stack gas
buoyancy. A low pressure steam heat ex-
changer will be used to heat ambient air
which will be blended with the stack gas
stream to provide the necessary heat. This
type of design will prevent fouling and
corrosion problems experienced by reheaters
placed in the stack gas duct. Low pressure
steam needed for the reheater is available
from steel mill operations.
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CORPORAT8QN
Design Parameters
Design parameters used for the conceptual design
of the limestone scrubbing system are given in Table 4-5.
The limestone scrubbing basis is the same for both sinter
plant applications to permit accurate comparisons.
Most sinter plants in the U.S. today use a high
basicity sinter mix by adding limestone or dolomite to the
sinter feed. The addition of the alkali causes some of the
sulfur in the sinter bed to be fixed in the sinter as calcium
sulfite and sulfate. It also produces a basic fly ash that
contains 10-20 weight percent CaO plus MgO. These basic species
will probably be soluble to some extent after removal from the
gas stream in the prescrubber.
At one Soviet sinter plant facility, venturi scrubbers
were used to capture fly ash which contained 10-13 percent CaO.
They found that the CaO dissolved in the water to neutralize
the acids present. The aqueous medium leaving the scrubbers
was either weakly alkaline or neutral (SU-094). The venturi
scrubbers removed up to 98.5 percent of the particulate and
over 60 percent of the S02. (SU-093) .
The venturi prescrubber system was designed to remove
30 percent of the S02 in the flue gas. This was done because
the presence of basic fly ash components would already cause some
SO2 removal which would have to be considered in the overall
system design. Also, removing part of the S02 in the venturi
prescrubber would require less to be removed in the absorption
section and would lower the absorption section equipment costs.
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TABLE 4-5
LIMESTONE SCRUBBING DESIGN PARAMETERS
Design Area
Parameter
Venturi Pre-Scrubber
!30~ Countercurrent
Spray Scrubber
Total System
SO- Removal
Particulate Removal
SO- Removal
Particulate Removal
Calcium Sulfite Oxidation
Overall SO- Removal
Overall Particulate Removal
Overall Calcium Sulfite Oxidation
Solids in Scrubbing Slurry
Solids in Clarifier Underflow
Solids in Disposal Pond
Design Specification
fWeight-
30
98
90.4
70
70*
93.3
99.4
70*
12
40
60
*Mole Percent
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CORPORATION
Previous operating experience with venturi scrubbers.
reported in the literature, indicated that a particulate
removal efficiency of 98 percent can be easily obtained.
Removal efficiencies of over 99 percent are not uncommon with
venturi scrubbers. Therefore, the venturi prescrubber was
designed to remove 98 percent of the incoming fly ash. Radian
pilot plant experience indicated that an S02 spray scrubber can
remove about 70 percent of the remaining particulates in the gas
stream which had passed through an initial particulate collection
device. The removal of 98 percent of the particulates in the
prescrubber and 70 percent in the absorber results in an overall
removal of 99.4 percent. The Radian conceptual designs have
particulate concentations of 844-867 mg/Nm3 at the inlet and 4.59-
4.91 mg/Nm3 at the outlet of the FGD System. This degree of
particulate removal seems reasonable when compared to Japanese
experience. The Moretana Process used at the Kashima Plant achieved
greater than 90 percent removal with the use of two Moretana per-
forated plate scrubbers. The first scrubber is used to cool the
gas and remove particulates while the second scrubber is used as
an S02 absorber. The Radian design achieves a greater amount of
particulate removal because the venturi prescrubber is capable of
a much higher particulate removal efficiency than the perforated
plate scrubber used at the Kashima Plant.
The conceptual design of the two limestone scrubbing
systems was based on removing an equivalent percentage of SO2
from both systems while reducing the SOa level in the stack
gases below 100 ppm. Equal S02 removal rates were used for
both systems to achieve an equal basis for comparing the capital
investment and operating costs. An overall S02 removal efficiency
of 93.3 percent was chosen for both systems. This reduced the
outlet S02 level to 44 ppm for the standard sinter plant case and
67 ppm for the recycle case. The emission rate for both particu-
lates and S02 per unit of total strand feed is given in Table 4-6.
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TABLE 4-6
MASS EMISSION RATES FROM THE RADIAN BASE CASE
STEEL MILL SINTER PLANTS AFTER LIMESTONE SCRUBBING
OF THE WINDBOX EXHAUST GAS
Basis: Mass emissions per unit of total strand feed including
recycle fines and a hearth layer.
Strand feed rate = 336 mtph (370.4 tph)
Grams Pollutant Pounds Pollutant
Pollutant Kilogram StrafuT Feed 'ion strand
Partlculates
(a) Standard Case 0.011 0.021
(b) Recycle Case 0.006 0.013
S02
(a) Standard Case 0.27 0.54
(b) Recycle Case 0.41 0.82
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These S02 removal efficiencies are consistent with the S02 removal
efficiencies experienced in Japan where greater than 90 percent
SOa removal was achieved from scrubbing sinter plant gases with
similar S02 concentrations. (See Japanese data in Appendix B)
Calcium sulfite and sulfate relative saturation
levels in the scrubbing system are important parameters that
affect the limestone system performance. It has been shown
by testing at TVA's Shawnee pilot plant that sulfate relative
saturation levels should be kept below a maximum of 1.35 to
prevent scaling (EN-310). The maximum allowable relative
saturation level for sulfite in lime/limestone systems is not
as well defined. Relative saturation levels as high as six
have been reported in systems which operated without scaling
problems. It was decided to design the Radian scrubbing system
to operate well below the maximum alloxvable saturation levels .
Maximum sulfate and sulfite relative saturation levels of 1.16
and 2.25 in the scrubber bottoms were chosen to insure scale-
free operation.
Data obtained from the open literature describing
hydrocarbon removal from sinter plant operations is conflicting.
Condensible hydrocarbon removal efficiencies are reported to
vary from nil to almost 70 percent (ST-368, BA-444). The high
removal efficiencies were obtained when using a high energy
scrubber. From the available data, one cannot ascertain the
degree of hydrocarbon removal to be expected from the venturi
prescrubber included as part of the limestone system design.
The hydrocarbons included in the particulate composition were
treated as particulates and were the only hydrocarbons assumed
to be removed by the scrubbing system. All hydrocarbons not
collected in the scrubbers will exit the system with the stack
gas from the absorber.
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Limestone scrubbing systems noroially operate using
a limestone scrubbing slurry of 10-15 weight percent solids. A
value of 12 weight percent solids was chosen for this design.
The bleed stream from the SCL scrubbing system, which removes
fly ash and calcium sulfite and sulfate, is normally thickened
and sent to disposal. A clarifier was chosen as the thickening
device for this system. The solids content of the clarifier
underflow can range anywhere from 20 to 40 weight percent. An
underflow concentration of 40 weight percent solids was chosen
for this design because the solid waste is made up primarily
of cai'-cium sulfate dihydrate crystals which settle more easily
than i:he calcium sulfite hemihydrate crystals. Most scrubber
sludges contain more of the sulfite crystals than sulfate and
do not: settle as well.
The amount of oxidation of calcium sulfite to sulfate
has been reported to be anywhere from 25-100 percent from
Japanese and Soviet experience (see Appendix I and II). A
value of 70 percent was chosen for the conceptual designs.
The clarifier underflow is transferred to a waste
disposal site where the sludge settles to its final concentra-
tion. The high rate of sulfite oxidation in this system pro-
duces a sludge whose solids are composed predominantly of
calcium sulfate crystals (about 65 percent of the solids).
This relatively high concentration of sulfate crystals allows
the sludge to compact to a final solids concentration of about.
50 weight percent. Clear supernatant liquor from the disposal
pcnd will be rccirculated to the system.
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4 . 2 Economic Basis
An economic evaluation of a limestone slurry flue gas
desulfurization process requires that both total capital invest-
ment and annual operating costs be calculated. The basis for
the economic calculations performed for this study was the
January, 1975, report by McGlamery, et al. (MC-147) on detailed
cost estimates for advanced effluent desulfurization processes.
A direct comparison of the limestone scrubbing system design
basis presented in Section 4.1 with the basis used by McGlamery
allowed both equipment and operating cost estimates to be made.
Cost estimates for equipment not included in McGlamery's report
were based on work done by PEDCo (PE-146). The installed equip-
ment cost vss based on retrofitting the limestone slurry process
equipment to an existing sinter plant.
4.2.1 Capital Investment Costs
From the design basis presented in Section 4.1, cal-
culations were made to estimate the equipment sizes required to
prpcess flue gas from the two steel mill sinter plant operating
cases considered. Once the equipment sizes for both cases were
determined, size-cost scale factors presented by McGlamery, et
al. (MC-147) were used to obtain estimates of the delivered
equipment costs.
The criteria used to calculate the total capital
investment required to install a limestone slurry flue gas
desulfurizationjsystern on an existing steel mill sinter plant
Included the following.
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(1) A cost index factor of 1.20375 (CH-278)
was assumed in order to scale up the 1974
equipment costs presented by McGlamery
(MC-147) to mid-1977 costs. This factor
was calculated from the Chemical Engineer-
ing plant cost index based upon a September
1975 factor of 1.0514 (obtained by divid-
ing the September 1975 index by the Sep-
tember 1974 index). An annual inflation
rate of 7 percent was chosen for the years
of 1976 and 1977.
(2) Installation costs for retrofitting the
limestone slurry process equipment to
existing sinter plants were based on cost
estimate factors given by Wood (WO-078).
(3) The cost of spray tower SOz absorbers was
based on data reported by the Western Precipi-
tation Division of Joy Manufacturing
Company (JO-194).
(4) The cost of the S02 absorber effluent
clarifier was based on data presented
by PEDCo (PE-146).
The items used in calculating the total capital in-
vestment for the limestone slurry process include both direct
and indirect capital costs and are listed in Table 4-7.
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TABLE 4-7
ITEMS USED TO ESTIMATE THE TOTAL CAPITAL
INVESTMENT REQUIRED FOR A LIMESTONE SLURRY PROCESS
Direct Costs:
Equipment (Purchased)
Piping
Structural Steel
Concrete Foundations
Insulation and Painting
Electrical
Instruments
Buildings and Service
Excavation, Site Preparation
Auxiliaries
Sludge Ponds (installed)
Fixed Costs (includes labor):
Engineering Design and Supervision
Construction Field Expense
Contractor Fees
Contingency
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4.2.2 Annual Operating; Costs
Table 4-8 lists both the direct and fixed operating
costs which must be considered for an economic evaluation of a
limestone slurry process. The estimates made for annual operat-
ing costs assumed a 1978 start-up of the limestone system.
Operating cO'St data taken from several sources served as a
basis for estimating 1978 costs (OT-043, MC-147, PE-146).
The estimates presented here for both operating and
capital costs are much the same as those which might be calcu-
lated for comparable size power plant flue gas desulfurization
units. No spare equipment for increased reliability has been
included.
The results of the capital investment and annual
operating cost estimates for both sinter plant operating cases
are presented in Section 5.3.
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CORPORATION
TABLE 4-8
BREAKDOWN OF ANNUAL OPERATING COSTS
FOR A LIMESTONE SLURRY PROCESS
Direct Costs;
Raw Materials
Limestone
Conversion Costs
Operating Labor and Supervision
Utilities
Maintenance
Analyses
Fixed Costs:
Annual Capital Charges
(Includes depreciation, taxes, and insurance)
Overhead
Plant
Adminis trat ive
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5.0 RESULTS
The results presented in this section reflect study
efforts in two major areas:
(1) Preparation of conceptual process
designs for the two sinter plant
limestone scrubbing systems, and
(2) preparation of cost estimates,
including both capital and operating
costs, for the two limestone scrubbing
system process designs.
Detailed discussions of the results of this study are
report.ed in the following sections. Section 5.1 presents a de-
scription of the conceptual process designs for the two limestone
scrubbing systems along with a detailed process flow diagram,
material balances, and design specifications of the process com-
ponents. Section 5.2 presents a plot plan of a potential arrange-
ment for a limestone scrubbing system located in a sinter plant,
and Section 5.3 contains the results of the economic evaluations
of the two limestone scrubbing systems.
5.1 Process Designs
Design parameters presented in Section 4.1 were used
as the; basis for preparing conceptual process designs for limestone
scrubbing systems to remove SOo from sinter sinter plant flue gas.
Process designs were developed for both standard sinter plant and
windbox gas recirculation operations.
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A process flow diagram was prepared to depict the flow
of process streams through the various equipment. Only one flow
diagram was prepared since the limestone scrubbing system will
employ the same types of equipment for both design cases. Figure
5-1 is the flow diagram illustrating the process stream flows in
the limestone scrubbing system.
Two scrubber modules in parallel were used to treat
the flue gas from the sinter plant while the limestone feed pre-
paration, slurry processing, and calcium solids disposal sections
of the process use only one set of equipment. Hoxvever, for ease
of depiction the process flow diagram shows only one set of equip-
ment for the entire process.
Material balances were prepared for each design case
to determine the process raw material requirements. In addition,
material balance calculations were used to estimate the sizes of
the various process equipment. Tables 5-1 and 5-2 present the
results of the material balance calculations for the two design
cases. The tablcc present the total .nrocess flow rates for both
scrubbing modules.
The design specifications for the various process equip-
ment were determined from the results of the material balance cal-
culations. The function and operation of major equipment items
are described, and their design specifications given in Table 5-3.
Potential problem areas in the FGD system were investi-
gated. It was found that steel mill sinter plants normally operate
24 hours a day except for one eight-hour shift per week. The FGD
system, during this period, would continue to circulate the scrub-
bing slurry to prevent settling of solids and plugging of the lines
Another potential problem area is the small amounts of contaminants
contained in the flue gas. Species such as chlorides, fluorides,
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SPRAY
TOWER
SO, ABSORBERS
SO 2
ABSORBER
EFFLUENT
HOLD TANKS
HOPPERS. FEEDERS 6. CONVEYORS
ELEVATOR
MARK-UP
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TABLE 5*1. MATERIAL BALANCE FOR A LIMESTONE SCRUBBING PROCESS ON A STANDARD SINTER PLANT
T.TRKAH IIUTV.1KH *
HEMtHIi'TlUN
[o4<»l Stream flow ^*»'*
(g/5PC)
(« . f neJe /sec)
frr«p^*a|urr C°C)
eio
GAS l^i^SE
Gas PtiaST Flov^ Rale
(q-rviofe/S*e)
Cwm'/sec)
1 <<1/M9 ^ -,
Cc»n(>Oii(iao ( r»>olc Vt.,/
N2
0^
^•(-V,
*-*-'Z
M2O
SO2 (pP'^)
LIQUID Pimse •
Lulu 'd PliajP Flow BiW
(q/5C«.)
(o-f^Jc/5«)
frort.poilib" fmoJcjUy 'lO4i
SO3 =
MSO 3 ""
SO-l f
MCOj
H2C05 (o)
Co.*'
CO.HCO i *
Oi3O3(i)
Co SO^ < f )
AAq •'
AAq5O4 f«l
No*
Ci"
pH
CoSOi ftlal'V jtJura^'O^
O>5O^ O'lrji'vff S"''u*tl'(Or*
JiSX1!*^ 5tJ'di^uJ pp'*')
5c.l;d>Co.l~ foic
(^Q/ieel
(q.««>lr/W<)
C^,/M-»)
Corv\CV3lliOn C1"' ^o)
Cc.O
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122-
812073
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2U7OOO
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2304200
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0.435
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2.250
1.134
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12
313550
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4.075
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17.4
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..ZO
109
20.3
9.83
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4.19
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fo.51
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to l-IMxl
1719
foi.9
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1.20
109
20.3
965
113
2.ZZ
J.ZS
fe2.O
IO.O
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fo.SI
2efe4
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II. 61
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C,1?5
2 28
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M-tV.. ll|>
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7.II
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I7&
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0.229
O
I.2I
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0
0
6.08
7.I2
ihi
M»-
slurry .<•
I'llll-l.-.H
M46- '
3245
459.5
255
feo
4.69. a
fe.95
o 9/
O.OJ
i.faS
3fcO
221.4,
2 25
O.97
O.O3
l.foS
u>
i
NOTE: All stream values nrc for the combined f>as clcaninp, system.
-------
TABLE 5-2. MATERIAL BALANCE FOR A LIMESTONE SCRUBBING PROCESS ON A SINTER PLANT WITH WINDBOX RECYCLE
S1HKAM KUHilER -
DESCRIPTION
t
feWS^FI^SW.
{a-mcJv/Sff)
fernp. (°c)
Goi Pha^f Flow Pole
(<)/S«<)
Co-f>W*/Sct^
Nl
Ol
COl
HzO
SO jiff")
LIQUID PHftSE
Liq^iJ rv,o«. Flow fole
~.o»v»posil icnTmolaf ily • Id"'
S03-
HSO3"
UCOj-
Mp CO aft)
Co **
Cc, MCOj •
CaSOJfo)
CaSOrfd)
AAq«
AAcJ 5Of (0)
lil -t
ci°-
pW
^iSOj SVlaliv* Sn^mlion
CaSO« fifelolive ^^urolion
->!3iolvcJ Solicfj (i^( ppm)
Sol.*!)
(Xifl to
IS5Z3J
5242.
2i9
4Zfc
IS5IS4
5241
117.4
t.7.1
12.2
12. Z
8.5
IO98
9».I3
I.J7
844
II.O
8.7
2 fo
O^>
fe.8
'0.3
3 '5
<$>
to SO,
Abnorber
Ifo5000
578O
57
135
IW99O
5780
129. Sfa
to. 7
II.O
ll-l
17.1
tab
1.98
.O273
is.ze
II.O
G.I
Z.fo
O.
Cat
to Stock
IM690
5780
57
135
ife>489O
578O
129-54
foo.7
II.O
H.2
n.i
%£e
4.59
II.O
87
2 fa
o.fa
t».8
70.3
315
Preacmbber
Recycle
583429
28919
513410
28438
12
7Ooll
Pte»c rubber
Bottonfl
57 3fe^2.
28370
503554
27889
12 .Z
7O IO8
481
Absorber
Recycle
945800
9(/4£>9
0.390
2.4&>
IO9.O
18.49
13-38
'SMB
3.15
70.55
(j.tty
2.fe4
'8 Z5
2509
fe 34
l-3£>l
1.088
2932
12
it>oz
11.8
Zl 0
t.5-0
2 2
? 42.
Absorber
Dot torn
.94tooo
9MW
I1I290O
0.4 Zfo
0.17
M4.8
753
(fo.bb
I2O 4
O.S09
-3.19
75 Zl
2.11
25.IO
5. 65
1.508
Mb
.3059
23J050
Ifooo
in
2I.O
W.I
2.2
711
<£>
Pr*sc rubber
Bleed
to Pond
3490.8
173-1
3071.4
170.2
12.
418.9
2. 88
<£>
Prcac rubber
PotKt
Recycle
279Z.b
154.7
2192 .t»
XX
Abnorher
filers! to
CUrlftei
5fa40
269. fc
4963
2.4&
109.0
18.49
13.38
2fo|0
J.I5
70.55
fe.lfo
?.fe>4
18.25
2509
fo.»
2932
IZ
4-faS
n. a
21.0
feS.O
?.i
Z.4Z
XX
Clorlflrr
tverflou
3948
218.7
3948
O.Z94.
l.fafl
102.4
19.98
13.0
IIO.O
2.26
7 31
fe.4.90
&.ZI
2-59
I0.7b
fa.39
2757
O
Abnorbcr
243.6
155
?43.«>
13.5
0
O
7.il
IO.7
l.7fo
tblo
0.7.29
O
I.ZI
O
O
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8.08
•t.iz
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O
Rtcaa
1829. 3
IOI.5
IZI
250
1829.3
IOI.S
IOO
O
IMortfler
IW>I luwi
to
ifo.9
O.fo'
10. 1
O.Sfc
0.294
I.C»B
102.4
19.96
130
IIO.O
2-2t>
2.JI
t>4 -9O
G- 21
2.59
Z508
fo.39
2757
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t, a
0.05
11.8
21.0
foS.O
2-Z
a.
Wat,.,
448.3
21.9
448.3
24.9
O
O
7.11
IO.7
l.7fo
Ka.fe
0229
O
I.ZI
O
O
O
19-00
7.12
2£>(
•&
r.lurry t.i
Proi-.:n(i
H20.7
31.60
448.3
24.9
foo
f'e
-J^
PM-rtcr>ihb«>r
H-tko-ttp
U.,t..r
10049
SG7.7
10049
557.7
O
0
i.n
IO.7
l.7fe>
tty.tt
0 229
O
<-2(
O
O
O
0-08
7.12
Zbi
<$>
I.ln.-Hlonr
3tO.S
IO Z
144.2
8-0
fcO
2-lfl
^?i>
Ahsi>it>.-r
5SS.3
30 9
558.?!
50.9
NOTE: All stream values are for the combined p,as cleaning system.
-------
TABLE 5.3
Ln
I
Item
1 . Blower
No.
2
2. Prescrubbcr 2
3. Prescrubber 2
Hold Tank
4. Absorber
5. Absorber Hold 2
6. Dcmlstcr
7. Reheater
8. Clarlfier
DESCRIPTION AND DESIGN SPECIFICATIONS TOR MAJOR PROCESS EQUIPMENT
Description
The blower is a forced draft fan that is
installed prior to the FGD system. It Is
provided to overcome the FGD system pressure
drop.
The prescrubber is a venturi scrubber used
to:
i. Cool and saturate the gas.
2. Remove pnrticulates . hydrocarbons,
chlorides, S02 and other undersirable
emissions .
The prescrubber hold tank provides a loca-
tion for -limestone slurry addition to neu-
tral ixe and react with absorbed compounds.
Residence time is provided for calcium sul-
fite and sulfate precipitation.
The absorber is a countercurrent spray tower
that is designed to remove a high percentage
of the S02 and some of the remaining particu-
lates.
The absorber hold tank is an agitated Hank
that provides a location for limestone
addition to reach a constant slurry den-
sity. Residence time for sul f ite and
sulfate precipitation is provided.
The demister is a vertical chevron demister
installed in a horizontal duct after the
spray tower. The demister removes entrained
mist and solids in the stack gas.
The reheater is a low pressure steam heat
exchange that is placed outside of the
stack duct. Air is forced through the
Equipment
Parameter
Power rating
Gas flow rate
Pressure drop
Gas flow rate
Gas velocity
Volume
Gas flow rate
Gas velocity
Vo 1 ume
Liquid residence time
Gas flow rate
Power rating
Steam requirement
Surface area
Design Parameters
Standard
System
1530kw.,
1.41 .4m /s
609mniH20
141 .m3/s
38.1m/sec.
174.1. m"1
118.6m3/s
3. 05m/ sec.
531m3
7.2 minutes
118.5m3/s
4000 kw
1.83 !--S/sec
146.3m'
Recycle
System
Il45kw..
1.05.8m /s
609mmH20
I0r>.8m3/s
38. Im/sec.
"
199.4m3
78.4ni3/s
3. 05m/ sec.
708m3
12.8 minutes
78.3m3/s
2000 kw
0.92 kg/sec
73.4 my
exchange where it is heated and then
mixed in with the stack,, gas. The stack
gas is reheated to 79.4 for bouyancy
The clarifier is a sol id-liquid separator
that concentrates the solid waste to 40
weight percent solids. The clarifier over-
flow is low In suspended solids and is re-
cycled back to the process.
Feed slurry flow rate
311 Liters/min.
303 l.iters/min.
-------
TABLE 5-3
DESCRIPTION AND DES1CN SPECIFICATIONS FOR MAJOK PROCESS
(Continued)
Equipment Design Parameters
I
CTv
Item
9. Ball Mill
No.
10. Prescrubber
Settling Pond
11. Absorber
Settling Pond
12. Limestone
Preparation
System
Description
The ball mill is a continous wet ball mill
that grinds a small slip-stream of the solid
waste from the clarifier underflow. The
outlet stream is sent back to the hold tank.
The ball mill grinds the solid particles to
provide additional surface area for calcium
sulfite and sulfate precipitation in the
hold tank. The ball mill will generally
operate intermittently to control the quantity
and size of sulfite and sulfate crystals.
The prescrubber settling pond is a disposal
site for the participates, calcium sulfite
and sulfate sludge, and other component
captured In the prescrubber. The waste
sludge settles to a concentration of fO weight
percent solids. The pond is clay-lined and
designed for a 40 foot depth.
The absorber settling pond is a disposal
site for the particulatcs and calcium sul-
fite and sulfate sludge from the absorber.
The waste sludge settles to a concentrated
of 60 weight percent solids. The pond is
clay-lined and designed for a 40 foot
depth.
The limestone preparation system crushes
and grinds the limestone from 0x4 cm
into 70 percent - 200 mesh. The limestone
is slurried to a 60 weight percent solid
slurry before being sent to the process.
Parameter
Feed slurry flow rate
Volume
Solid waste feed rate
Acres (@ 40 fooC depth)
Volume
Solid waste feed rate
Acres (@ 40 foot depth)
Limestone feed rate
Standard
System
18.9 I.iters/mtn.
403,050m
32 Liters/rain.
8.2
566,600m-1
45 Liters/min.
11.5
4l.4kg/mln.
Recycle
System
18.9 Liters/ruin.
348,200m
27.6 l.iters/min.
7. I
554,700mJ
44 l.iters/roin.
11.2
40.3kg/min.
-------
and arsenic have been reported to be present in sinter plant flue
gas (VA-126, BA-449). These species can cause corrosion problems
if allowed to build-up in the scrubbing system. These species will,
however, be contained in the prescrubber loop where they will build
up to some steady-state level. All corrosion problems can then be
handled in the prescrubber loop and not affect absorber operations.
The FGD system designed for sinter plant applications
includes an initial particulate collection system which is
separate from.the S02 absorption system. The systems are
separated to prevent potential oxidation catalysts, chlorides,
and other corrosion causing agents from entering the S02 absorp-
tion system.
Some important operating parameters for the two systems
are given in Table 5^4. The major differences in the parameters
for the standard and recycle cases are the liquid to gas ratio
(L/G) and the liquid residence time in the hold tank. The recycle
case has an L/G ratio that is 15.5 percent higher than for the
standard case and the gas volume treated is about 35 percent less
on a wet basis, thus the absorbed pumping requirements for the
recycle case are about 25 percent less. Although the hold tank
residence time is 78 percent higher for the recycle case, the
actual required hold tank volume is only 33 percent larger because
of the smaller liquid flow rate. Another difference in the two
systems is an increased steam reheat requirement of 100 percent
for the standard case due to both the increased volume of gas to
be heated and the lower initial stack gas temperature.
The overall differences in stream flow rates and raw
material requirements for the standard and recycle cases are small.
This is due mainly to the fact that the same amount of S02 is being
removed by both FGD systems. Major differences are evident, however,
in the sizes of the gas handling equipment. These differences are
reflected in the capital investment costs of the systems which are
reported in Section 5.3.
-67-
-------
TABLE 5-4
OPERATING PARAMETERS FOR PROCESS DESIGNS
Parameter
Design Gas Velocity (m/sec.)
Venturi Prescrubber
Spray Tow<»r S02 Absorber
L/G (Liters/Nm3)
Venturi Prescrubber
Spray Tower $©2 Absorber
Design Pressure Drop (mm^O)
Venturi Prescrubber
Spray Tower $©2 Absorber
Ducting and Demisters
TOTAL
Liquid Residence Time (minutes)
Prescrubber Effluent Hold Tank
S02 Scrubber Effluent Hold Tank
Solid Residence Time (days)
Prescrubber Effluent Hold Tank
S02 Scrubber Effluent Hold Tank
Standard Operation
38.1
3.05
4.7
11.6(87.0)*
7.6
7.2
1.1
9.3
39% Recycle
38.1
3.05
4.7
13.4(100.1)*
254
76
279
609
12.0
12.8
1.4
12.6
*gallons/MSCF
-68-
-------
CORPORATION
5.2 Limestone Scrubbing System Layout
The conceptual process designs contained in Section
5.1 were used to prepare layouts of the limestone scrubbing
systems. The layout, which is divided into two processing areas,
was prepared to show the utilization of space for the process.
The first area is the scrubbing section between the sinter plant.
and the stack which includes the scrubbers and hold tanks. This
area is the most important in relation to space requirements in
a retrofit situation because the area between the existing sin-
ter plant and the stack is usually limited. Figures 5-2 and
5-3 show the layouts for the scrubbing sections of a limestone
scrubbing system applied to standard and recycle steel mill
sinter plant operations.
The second area is the limestone feed preparation and
slurry processing section of the system. The layout for this
section, shown in Figure 5-4, is the same for both sinter plant
applications. This is because equal amounts of SOa are removed
in both cases and, therefore, about the same amount of limestone
is required and about the same amount of sludge is produced.
The equipment sizes were estimated from the process
design data. A report by TVA was used as an aid in positioning
some of the equipment on the layout.
The total space requirements for the two process de-
signs are shown in Table 5-5. The recycle operation requires
more land area for the scrubbing section because of the larger
absorber hold tanks. The hold tanks are placed beneath the
scrubbers in both designs. A length of 4.6m (15 feet) was chosen
as a reasonable spacing between equipment in the scrubbing section
-69-
-------
PRESCRUBBER HOLD TANK
'DIA.=5.5M
SO2 ABSORBER HOLD TANK
DIA.= 8.0 M
/ VENTURI
(PRESCRUBBER
». DIA. = 7.7M
37.3M-
FIGURE 5-2. LAYOUT OF SCRUBBING SECTION OF A LIMESTONE SCRUBBING PROCESS
FOR A STANDARD STEEL MILL SINTER PLANT OPERATION
-------
PRESCHUBBER HOLD TANK
DIA.= 6.0M
SO2 ABSORBER HOLD TANK
DIA. = O.OM
/ VENTURI
/ /PRESCRUBBER
SO2 ABSORBER
STACK
DIA.r BM
f VENTURI
IPRESCRUBBER
v DIA. = 6.6M
SO2 ABSORBER
DIA. =. 5.7M
37.2M
FIGURE 5-3. LAYOUT OF SCRUBBING SECTION OF A LIMESTONE SCRUBBING
PROCESS FOR A RECYCLE STEEL MILL SINTER PLANT OPERATION
-------
SLURRY FEED TANK
20M
o
o
(L_)
WET BALL MILL
DEMISTEH WASH PARTICLE
HOLD TANK RECIBCULATION
SURGE TANK
0 - D
WET BALL MILL
CRUSHER
FEED BIN
CONVEYOR
ELEVATOR NO. 1
WEIQH DELT
( OYnATOnY CRUSHER
])ELEVATOR NO. 2
-1 r— -,
I ' i 1
_J L___J
PER HOPPER
/
CONVCYOn
R
1
Zl
ECEIVIN
^OPPER
LIMESTONE PILE
OIA. • 16M
FIGURE 5-4. LAYOUT OF FEED PREPARATION AND SLURRY PROCESSING SECTION OF A
LIMESTONE SCRUBBING PROCESS FOR A STEEL MILL SINTER PLANT APPLICATION
-------
CORPORATION
TABLE 5-5.
SPACE REQUIREMENTS FOR A LIMESTONE SCRUBBING SYSTEM
ON STEEL MILL SINTER PLANT APPLICATIONS
Processing Area
Scrubbing
length (r.)
width (m)
area (m2)
Standard
Operation
37.3
20.6
768
Recycle
Oneration
37.2
22.6
841
Feed Preparation and
Slurry Processing
length (m)
width (m)
area (m2)
66
20
1320
66
20
1320
Total Area
(excluding waste disposal)(m2) 2088
(acres) *0.52
2161
0.53
Prescrubber Sludge Settling (m2) 33059
Pond " (acres) 8.2
28560
7.1
Absorber Sludge Settling (m2) 46473
Pond (acres) 11.5
45497
11.2
Total Area
(including waste disposal)(m2) 81620
(acres) 20.2
76218
18.8
-73-
-------
RADIAN
CORPORATION
For the prescrubbers, the hold tanks are smaller in
diameter than the scrubbers so that the equipment spacing is
measured from the outside diameter of the prescrubber. For the
absorbers, the hold tanks are larger in diameter than the scrub-
bers so that the equipment spacing is measured from the outside
diameter of the hold tanks. Since the absorber hold tanks for
the recycle operation are larger than for the standard operation,
the scrubbing area becomes larger.
As can be seen, most of the space required is
for disposal of the fly ash and calcium solids. The
FGD process itself requires only about 2270m2 (24,400 ft2).
About, 42 percent of this area or 950m2 (10,200 ft2) is needed
for the scrubbing section between the sinter plant and the stack.
The most significant difference in land requirements
between the standard and recycle sinter plant operations occurs
in the waste disposal area. The recycle operation requires
5475 m2 (59000 ft2) less for particulate and calcium solids
waste-, disposal. This difference is mainly due to the smaller
prescrubber settling pond because of the lower particulate load-
ing for the recycle case.
5.3 Economic Evaluation
The results of the economic evaluation performed for
this study indicate that a reduction in both capital investment
and annual operating costs of a limestone scrubbing system can
be realized by employing windbox gas recirculation. For the
cases considered here, a 21.3 percent and 23.2 percent reduction
is indicated in capital investment and annual operating costs
respectively. The cost of modifying the sinter plant for wind-
box recirculation was not considered in this evaluation.
-74-
-------
CQRPQRAiraON
The reduced gas volume and quantity of particulates
to be removed were the major reasons for the lower required
capital investment cost for the recirculation case. The 35 per-
cent reduction in gas volume did not reduce the plant cost pro-
portionately. This is typical for small-scale units where the
initial fixed costs of the manufactured equipment represent a
larger portion of the total investment than do the costs for
larger equipment.
Annual operating costs for the gas recirculation case
were lower because of both the reduced gas volume to be processed
and the lower capital investment required. The reduced gas volume
required less electricity for handling and less steam usage for
reheating. The reduction in these two direct costs also resulted
in a lower cost being assigned to plant overhead. The reduced
capital investment resulted in both lower maintenance and annual
capital charges.
The estimated total annual operating cost of the lime-
stone scrubbing systems is $2.07 per metric ton of product sinter
for the standard operation case and $1.59 per metric ton of pro-
duct sinter for the windbox recirculation case. This results in
a price increase of about 2 percent or $5.00 per ton of product
steel when 80 percent of the blast furnace charge is sinter
(JA-145).
The detailed results of both the capital investment
and annual operating cost estimates are presented in the follow-
ing section.
-75-
-------
RAPIAN
CORPORATION
5.3.1 Total Capital Investment
A comparison of the total capital investment costs re-
quired for limestone slurry scrubbing of the two sinter plant
design cases considered is presented in Table 5-6. The major
cost savings for Case B, the windbox recirculation system, are
in the particulate scrubbing, SOn scrubbing, gas reheating, and
gas handling areas. Capital cost reductions of 19.9, 34.5, 27.4,
and 28.2 percent respectively occured in each of these areas be-
cause of both the reduced gas volume and quantity of particulates
processed in the recirculation case. The lower values for in-
stallation and associated construction costs for the gas recircu-
lation case reflect the lower cost for the process equipment in
these four areas.
The reduction of the quantity of particulates to be
scrubbed, due to gas recirculation, reduced the cost of particu-
late disposal by 13.3 percent. Both modes of operation require
that the same quantity of S02 be removed from the gas stream. Thus,
the cost of calcium solids removal is nearly identical in both cases
As stated in Section 5.3, this evaluation indicates
that the total capital investment required for flue gas desul-
furization can be reduced by 21.3 percent if windbox gas recir-
culation is employed in the sinter plant. The capital costs
associated with installing a windbox gas recirculation system
were not evaluated for this study. However, these costs are
discussed in the Wierton Report (PE-179). Additional work is
being done under this program and definitive costs will be deve-
loped.
A detailed breakdown of the equipment costs for each
of the limestone slurry scrubbing areas is given in Tables D-l
and D-2 of Appendix D.
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TABLE 5-6
TOTAL CAPITAL INVESTMENT SUMMARY FOR STEEL MILL SINTER
PLANT FLUE CAS DESULFURIZATION USING LIMESTONE SLURRY
SCRUBBING
Case A - Standard
Operation
Case B - 397. Gas
Rcclrculafl.on
Direct Costs:
Process Equipment
Materials Handling
Feed Preparation
Participate Scrubbing
S02 Scrubbing
Gas Reheating
Gas Handling
Solids Disposal
Services
Particle Rcclrculntion
Subtotal.
Equipment Installation
Piping
Structural Steel
Foundations
Insulation and painting
Electrical
Instruments
BI, Building and Service*
Excavation and Fill Site
Preparation
Aux Lliaries
Sludge Ponds (installed)
Participate Disposal
Calcium Solids Disposal
Subtotal Direct Costs
Indirect Costs:
Engineering Design and
Supervision
Construction Field Expense
Contractor Fees
Contingency
Subtotal Indirect Costs
TOTAL CAPITAL INVESTMENT
5 32,850
9/1,040
673,170
1,026,800
210,470
143,300
178,200
128,570
31.950
$2,519,350
978,000
750,000
125,000
1,511,000
50,000
176,000
100,000
126,000
250,000
25,000
120,000
170.000
6,900,350
899,000
955,000
506,000
1.011.. OOP
3,371,000
10.271.350
36,210
97,230
539,190
672,600
152,900
102,860
191,800
128,570
31.950
$1,953,310
762,000
586,000
100,000
1,172,000
40,000
137,000
78,000
98,000
195,000
20,000
104,000
166.000
$5,411,310
712,000
756,000
400,000
800.000
$2,668,000
$8.079.310
*Battery Limit
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5.3.2 Annual Operating Costs
The estimated annual operating costs for both design
case;; are summarized in Tables 5-7 and 5-8. Both the operating
costs and capital charges are included in these tables. As can
be seen from the values in these tables, the total operating
cost for the limestone slurry scrubbing process can be expected
to b<> reduced approximately 23.2 percent by windbox gas re-
circulation. This is due to the reduced utility requirements
for gas handling and gas reheating and to the lower capital
charges required when gas recirculation is used.
This cost reduction would be affected if capital charges
and operating costs of the windbox gas recirculation system were
included in the analysis. However, these costs were not avail-
able for inclusion in this study.
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VO
I
TABLE 5-7
LIMESTONE SLURRY 1'ROCESS
TOTAL. ANNUAL OPERATING COSTS
(Existing steel mill sinter plant - standard operation)
Annual Quantity
Direct Costs
Delivered raw material
Limestone
Subtotal
Conversion costs
Operating labor and supervision
Utilities
Steam
Process water
Electricity
Maintenance
Labor and material, .09 x 6,900,350
Analyses
Subtotal conversion costs
Subtotal direct costs
Indirect Costs
Average capital charges at 1.4.9%
of total capital investment
Overhead
Plant, 207. of conversion costs
Administrative, 10% of operating labor
Subtotal indirect costs
Total annual operating cost
17. A M nitons
18,000 man-hr
89,500 M kg
290.000 M liters
23,270.000 UWh
Unit Cost. $
6. 60/tnton
10,00/man-hr
3.31/M kg
0.029/M liter
0.028/kWh
2. 07/niton product
sinter
Total Annual
Cost. $
11/..600
1 U , 600
180,000
296,000
8,400
651 ,600
621,000
29./i 00
1,786,400
1,901.000
I ,530,400
357,300
18.000
I. ,905,700
3.806,700
Percent of
Total Annual
Operating Cost
3.0 \
3.01
4.73
7.78
.22
17.12
16.31
.77
46.93
49.94
9.39
._47
50.06
100.00
Basis:
Remaining life of sinter plant, 30 yr.
Stack gas reheat to 79.4°C.
Sinter unit on-stream time, 7,000 hr/yr.
Midwest plant location, 1978 operating costs.
Total capital investment, $10,312,550; subtotal direct investment, $6,898,550.
Sinter plant capacity of 631? nit pd
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TAOLF, 5-8
LIMESTONE SLURRY PROCESS
TOTAL ANNUAL OPERATING COSTS
(Existing steel mill sinter plant - 39% gas recycle)
Annual Quantity
I
00
o
Direct Costs
Delivered raw material
Limestone
Subtotal
Conversion costs
Operating labor and supervision
Utilities
Steam
Process water
Electricity
Maintenance
l.abor and material, .09 x 5,All,310
Analyses
Subtotal conversion costs
Subtotal direct costs
17.0 M mtons
18,000 man-hr
44,900 M kg
267,200 M liters
16,800,000 kWh
Unit Cost. $
6.60/mton
10.00/man-hr
3.31/M kg
0.029 liters
0.028/kWh
Total Annual
Cost. $
112.200
112,200
180,000
148,500
7,800
470,400
487,000
29.400
1.323.100
1,435.300
Percent of
Total Annual
Operating Cost
3.84
3.84
6.16
5.08
.27
16.10
16.67
1.01
45.23
49.12
Indirect Costs
Average capital charges at 14.9%
of total capital Investment
Overhead
Plant, 20% of conversion costs
Administrative, 10% of operating labor
Subtotal indirect costs
Total annual operating cost
1.59/tnton product
sinter
1,204,000
264.600
18.000
1.486.600
2.921.900
41.21.
9.06
.62
50.88
100.00
Basis:
Remaining life 06 sinter plant, 30 yr.
Stack gas reheat to 79.4°C.
Sinter unit on-stream time, 7,000 hr/yr.
Midwest plant location, 1978 operating costs.
Total capital investment, $10,312,550; subtotal direct investment $6,898,550.
Sinter plant capacity of 6312 mtpd.
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CORPORATION
6.0 CONCLUSIONS AND RECOMMENDATIONS
Conceptual process designs and cost estimates were
performed for limestone scrubbing systems to control sinter
plant emissions. The following conclusions and recommendations
are presented to summarize the results of this effort.
6.1 Conclusions
1) Lime/limestone scrubbing technology has
been demonstrated in Japan and the USSR
to be an acceptable method for removing
SOa from sinter plant effluent gases.
Based upon foreign experience and the
conceptual process design performed for
this study, there is no apparent reason
that lime/limestone scrubbing technology
cannot be applied to controlling emissions
from sinter plants in the United States.
This study is, therefore, an initial as-
sessment of the economic impact of lime/
limestone scrubbing on domestic iron and
steel plants.
2) The cost of sinter plant flue gas desul-
furization was determined to be $2.07 per
metric ton of product sinter for the stan-
dard operation case and $1.59 per metric
ton of product sinter for the windbox gas
recirculation case. This may increase the
price of the steel product by about $5/ton.
The effect of this price increase on the
profitability of steel production needs
to be evaluated for each specific installation.
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3) Cost estimates indicate that windbox gas
recirculation can reduce both capital in-
vestment and annual operating cost re-
quirements for sinter plant limestone
scrubbing units by approximately 20 per-
cent. Estimates made during this study
include only the costs associated with
the limestone units and do not account
for the additional cost of installing
the windbox gas recirculation system.
4) Nearly all existing sinter plants have
some type of particulate control follow-
ing the cyclones which are the primary
particulate collection device. The Radian
conceptual design includes a venturi pre-
scrubber to saturate and cool the hot sinter
plant gas and to remove chlorides and parti-
culates. This design would be applicable
to an existing plant when the presently
used particulate collection device follow-
ing the cyclones was removed. To retrofit
the SOz scrubbing system on a plant with
an existing particulate scrubber, the pre-
scrubber section would be excluded from the
system design. It is estimated that exclud-
ing the pre-scrubber section of the design
would decrease the overall cost by about
20 percent.
6.2 Recommendations
1) The results presented in Section 5.0 indicate
that limestone slurry scrubbing is a technically
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feasible method of flue gas desulfurization
for steel mill sinter plants. The results
also indicate that a complete limestone
system for a sinter plant as described in
Section 3.0 would cost about 8-10 million
dollars. A recommendation of this study
is that S02 removal in particulate scrubbers
be investigated as an alternate S02 control
technique for sinter plants. The purpose
of such a demonstration would be to provide
an acceptable technique for meeting S02
emission regulations while reducing the
economic impact of flue gas desulfurization
on sinter plant operation.
Two S02 scrubbing mediums that are recom-
mended for consideration in this evaluation
are: (1) limestone slurry and (2) a sinter
fly ash slurry mixture.
Sinter fly ash usually contains between 10-15
percent CaO and MgO, two basic species capable
of removing S02 in a wet scrubber. The basic
species come from the limestone or dolomite
that is mixed in with the sinter charge in
order to produce a basic sinter. The largest
consituents of the fly ash are usually iron
oxides. Sinter fly ash entering the scrubber
would be supplemented with fly ash removed in
the initial particulate collection device as
needed.
2) Theoretical, laboratory, and pilot plant investi-
gations should be conducted to determine the
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specific influences of sinter plant exit
gas components on process operations, and
to obtain data for process optimization.
Of particular concern are the effects on
sulfite oxidation and the potential cor-
rosion effects in the prescrubber liquor
loop.
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7.0 REFERENCES
BA-444 Bayr, Robert B. and Richard J. Wachowiak, "Elimination
of Hydrocarbon Emissions from the Sinter Plant", TMS-
AIME Ironmaking Proc. 31, 55-58 (1972).
BA-449 Ball, D. F0, A. F. Bradley, and A. Grieve, "Environ-
mental Control in Iron Ore Sintering", Presented at
the Minerals and the Environment Symposium, London,
June 1974.
BA-450 Ban, Thomas Eugene, "Sintering Process", U.S_. Patent
3,849, 115 (November 1974).
\
BA-451 Ban, Thomas E., "Process for Conditioning Sinter Draft
for Electrostatic Precipitation of Particulate Material
Therefrom", U.S. Patent 3,909, 189 (September 1975).
BA-452 Ban, Thomas E., "An Improved Sintering Process to Over-
come Environmental Problems in the Sinter Plant", Pre-
print No. 75-B-6, Presented at the AIME Annual Meeting,
New York, February 1975.
CH-278 "CE Plant Cost Index", Chem. Eng_r. 2_6 September 1975.
CU-055 Current, G. P., "Private Communication", National
Steel Corporation, Weirton Steel Div., Weirton, West
Virginia, April 1976.
EN-310 Environmental Protection Agency, Technology Transfer,
Lime/limestone Wet-Scrubbing Test Results at the EPA
Alkali Scrubbing Test Facility, 2nd Progress Report.
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JA-136 Jablin, Richard, Private Communication, Richard
Jab1in and Associates, Blue Bell, Pa., 15 April 1976.
JA-137 Jablin, Richard, Private Communication, Richard Jablin
and Associates, Blue Bell, Pa., 5 May 1976.
JA-145 Jablin, Richard, Private Communication, Richard Jablin
and Associates Consulting Engineers, 25 August 1976.
JO-194 Joy Manufacturing Company, Western Precipitation
Div., Basic Handbook of Air Pollution Control Equip-
ment, Los Angeles, 1975.
MA-544 Manning, G. E. and F. E. Rower, "A Characterization
of Air Pollutants from Sintering Plant Induced Draft
Stacks", TMS-AIME Ironmaking Proc. 30, 452-460 (1971).
MC-147 McGlamery, G. G., et al., Detailed Cost Estimates
for Advanced Effluent Desulfurization Processes, Final
Report, EPA-600/2-75-006, Muscle Shoals, Alabama,
TVA, January 1975.
MC-205 McGlamery, G. G., et al., "Flue Gas Desulfurization
Economics", Presented at the 6th Flue Gas Desulfuriza-
tion Symposium, New Orleans, La., March 1976.
OT-R-043 Ottmers, D. M., et al., Evaluation of Advanced Re-
generable Flue Gas Desulfurization Processes. Draft
Report, Radian Project No. 200-116, EPRI Contract
No. RP 535-1, Austin, Tx., Radian Corporation, March
1975.
PE-146 PEDCo-Environmental Specialists, Inc., Flue Gas
Desulfurization Process Cost Estimate, Preliminary
Draft, Contract No. 68-01-3150, Task 2, Cincinnati,
Ohio, May 1975.
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CQRPQRAT8ON
PE-179 Pengidore, D. A., Sinter Plant Windbox Gas Recircula-
tion System Demonstration, Phase !_, Engineering and
Design, EPA 600/2-75-014, Weirton, W. Va., Nat'1
Steel Corp., August 1975.
PE-193 Petrov, Yu A., et al., "Cleanup of Flue Gases at a
Sintering Plant", Metallurgist 15 (7), 420 (1970).
RO-219 Rowen, Harold E., "Protecting the Environment During
Agglomeration", Presented at the Institute for Briquetting
and Agglomeration, Hyannis, Massachusetts, August 1975.
RO-256 Rowen, Harold E., "Agglomeration - an Environmental
Tool", in Proc. In s t. for Briquetting and Agglomera-
tion, 13th Biennial Confernece, Colorado Springs,
Colorado, August 1973, pp. 13 ff.
SC-328 Schmitt, R. J., "Corrosion Problems in a Sinter Plant
Exhaust Gas System", Corrosion II, 425t - 29t (1961).
ST-368 Steiner, B. A.-, "Pilot Plant Testing of High-Energy
Scrubbers for Sinter Plant Gas Cleaning", TMS-AIME
Ironmaking Conf. Proc. 31., 59-69 (1972).
ST-398 Steiner, Bruce, Private Communication, Armco-Environ-
mental, 27 April 1976.
SU-092 Suitlas, John R., "Emission Characteristics and Pilot
Plant Studies on a Sintering Plant Windbox Discharge",
TMS-AIME Ironmaking Proc. 30., 461-68 (1971).
SU-093 Suprunenko, R. S., et al., "Industrial Use of Venturi
Pipes for Wet Cleaning of Sinter Gas", Metallurgist
12 (7), 358 (1967)..
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SU-094 Suprenko, R. S., et al., "Removal of Sulfur Dioxide
from Sinter Gas", Metallurgist 1.4 (9), 542 (1969).
SU-095 Suprenko, R. S., et al., "Wet Cleaning of Sintering
Gas", Metallurgist 9 (10), 539-41 (1964).
VA-003 Varga, John, Jr., et al., A Systems Analysis Study
of. the Integrated Iron and Steel Industry, PB 184 577,
May 1969.
VA-126 Varga, John, Jr., Control of Reclamation (Sinter)
Plant Emissions Using Electrostatic Precipitators,
Final Report, EPA 600/2-76-002, Contract No. 68-02-
1323, Task 32, Columbus, Ohio, Battelle-Columbus
Labs., January 1976.
WO-078 Woods, Donald R. , "Technique for the Estimation of
Capital Costs for the Process Industry", Presented
at the Symposium on Cost Estimation, Permian Basin
Section of the AIchE, Odessa, Texas, April 1975.
WO-092 Woodward, Kenneth, Private Communication, EPA Emission
Standards and Engineering Div., Durham, N.C., 26 May
1976.
YO-042 York Research Corporation, Test Report of_ Sinter
Plant Emissions at Bethlehem Steel Corp. , Bethlehem
Plant, Bethlehem, Pennsy1vania, Final Report, 3
volumes, Y-8479-18, Stamford, Connecticut, December
1975.
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APPENDIX A
COMMENTS ON THE SOVIET DATA
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1.0 INTRODUCTION
As a result of a technology interchange agreement between
the U.S. and the USSR which encourages cooperation between the two
countries in common areas of environmental concern, information
describing the operation of a full scale Soviet limestone wet
scrubbing facility was recently disclosed to the EPA. Since the
scrubbing facility in question has been used to control S02 and
participate emissions from a USSR iron ore sintering unit, it
was hoped that the Soviet data might provide a meaningful basis
for the application of lime/limestone wet scrubbing technology to
sintering operations in this country. Unfortunately, the Soviet
data was not of sufficient quality to be of any real use in this
area.
The comments which are presented in this report are
based upon an engineering review of process data obtained from
two sources (KH-027, LO-149). The specific objectives of the
work which was performed as part of this assessment were:
1) to identify unique mechanical features of
the Soviet sintering plant scrubbing
process,
2) to determine normal operating ranges of
important process variables, and
3) to identify potentially significant pro-
cess problem areas.
The approach which was taken in order to accomplish these objec-
tives involved both:
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1) a thorough analysis of the available
information to identify key process
features and performance characteristics,
and
2) a computer simulation of the system
to check the reasonableness and con-
sistency of the Russian data.
As a result of these activities, it was concluded that
the Soviet data were lacking substantially in the areas of both
completeness and accuracy. For this reason it does not appear
that this information will lend any support to the limestone wet
scrubbing process development efforts which are currently underway
in this country. Justification for Radian's position in this
regard is described in the next four sections of this report.
In Section 2, a general conceptual description of the
Soviet scrubbing system and several important pieces of process
performance data are presented. The data quality question is
discussed in Section 3. Radian's approach to the development of
a computer simulation of the Soviet system is described in
Section 4. Simulation results are discussed in Section 5.
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2.0 DESCRIPTION OF SCRUBBING FACILITY
The Magnitogorsk limestone scrubbing system consists
of 21 scrubbers separated into 3 scrubber banks. Normally 16-17
scrubbers are operating with the remained down for cleaning.
Figure 2-1 shows the process flow diagram for one scrubber system.
Table 2-1 gives the operating parameters for one scrubber. Scrub-
bert inlet and outlet flue gas compositions are presented in
Table 2-2.
The gas is first sent to a spray scrubber through a
forced draft fan. Slurry recirculated from the hold tank scrubs
the waste gases, removing 85 percent of the S02 and 50 wt percent
of the particulates . The following equations give the overall
S02 absorption reactions:
CaC03 + S02 -> CaS03 + C02 (2-1)
CaS03 + %02 -»• CaSCH (2-2)
Spent scrubbing liquor is processed in a cyclone filter. The
underflow from the filter is sent to a sludge tank prior to dis-
posal. The overflow; from the filter is sent to a hold tank
where fresh limestone slurry (prepared in a limestone slurry
tank) is added. The sludge tank and limestone slurry tank are
common to 4-5 scrubbers.
A unique feature of this system is the location of the
cyclone filter prior to the hold tank. Most lime /lime stone
scrubbing systems utilize a clarifier or filter after the hold
tank to process a bleed stream from the recirculating slurry.
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INLET FAN
XXX
XXX
SPRAY SCRUBBER
HYDROSTATIC
SEAL FROM SCRUBBER
SCRUBBER FEED
CONSTANT HEAD
TANK
CYCLONE FILTER
FIGURE 2-1
PROCESS FLOW DIAGRAM
OF THE RUSSIAN MAGNITOGORSK
LIMESTONE SCRUBBING FACILITY
~fc>-TO STACK
V 1 '
SLUDGE TANK
WATER LIMESTONE
Q
LIMESTONE
SLURRY TANK
TO DISPOSAL
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TABLE 2-1
OPERATING CONDITIONS FOR ONE SCRUBBER SYSTEM AT THE MAGNITOGORSK
SCRUBBING INSTALLATION
Parameter
Gas Flow Rate
Liquid Flow
L/G
Value
200,000 NmVhr
1,350,000 liters/hr
6.75 liters/Nm3
Gas Velocity
SO2 Removal Efficiency
Particulate Removal Efficiency
2.5 m/sec
85%
50%
Scrubber Inlet Slurry Density
Limestone Utilization
5 wt %
40%
Limestone Composition
87% CaC03
2% MgC03
Balance - Si02
Waste Sludge Calcium
Distribution
60% CaC03
30% CaS03
10%
Hold Tank Volume
Hold Tank Residence Time
180 m3
8 minutes
A-6
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TABLE 2-2
THE AVERAGE CHEMICAL COMPOSITION OF WASTE GAS BEFORE AND AFTER PURIFICATION
MAGNITOGORSK SCRUBBING FACILITY
System
Location
Scrubber
Inlet
Scrubber
Outlet
Volume 70 (dry basis)*
CO 2
4.0
4.1
CO
0.6
0.6
02
17.0
17.0
N2
77.71
77.71
CHq
0.5
0.5
NOV
0.012
0.010
S03
0.011
none
S02
0.16
0.016
Dust
g/Nm3
200
100
Average Gas
Temperature (°C)
125
50
* Moisture content of gases (wet basis): inlet - 7.1 volume percent
outlet - 12.2 volume percent
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3.0 DATA QUALITY
The data obtained for the Russian Magnitogorsk limestone
scrubbing system would have to be characterized as incomplete.
The primary areas where the data quality was questionable or
non-existent were: 1) inlet and outlet particulate loadings, and
2) make-up water composition. A discussion of the problems asso-
ciated with the inlet and outlet particulate loading data is in-
cluded in Section 5.0 of this technical note. In summary, it
appeared that the dust loading figures presented were two orders
of magnitude too high.
The water make-up composition was not given in either of
the sources which were reviewed. The composition of this stream
is important because it determines to a great extent the concen-
tration of the noncalcium dissolved salts in the system. Both
the recirculating slurry and filter bottoms dissolved salt con-
centrations are affected by this parameter.
The other data that was given in the literature appeared
to be reasonable for a limestone scrubbing system although some-
what incomplete. It would have been very helpful in verifying
the results of the process simulation program to have had a total
solids and liquid composition of one of the streams in the scrub-
bing system. The scrubber bottoms or hold tank slurry composition
would have been preferred.
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4.0 SYSTEM EVALUATION
The computer simulation of the Soviet scrubbing process
was attempted in order to calculate important stream flow rates
and compositions. The following assumptions for the system were
made:
• The CO, N2, CEk, and NOX species were
assumed to be inert and to pass through
the scrubber system.
Vapor liquid equilibrium of C02 and H20 occurs.
The particulates collected in the
scrubber were treated as insoluble
inerts.
The MgC03 and Si02 constituents of
the limestone were treated as inerts.
The make-up water dissolved salts
composition was taken to be 1000 ppm NaC&.
The cyclone filter underflow was
taken to be 10 wt percent solids.
The feed stream to the filter was
5 wt percent solids.
The cyclone filter was assumed to
operate at 75 wt percent overflow
and 25 wt percent underflow for the
total stream.
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The computer model which was used to estimate steady-
state operating conditions for the Soviet limestone scrubbing
process was developed by Radian to simulate aqueous inorganic
chemical processes. In addition to simulating the reactions in
the system and the operation of each piece of equipment, a mat-
erial balance around the entire system was generated by the com-
puter. A discussion of additional assumptions that are incorporated
in the computer model will be included in an appendix to the final
report for this task. Since other subt.asks will utilize the pro-
cess simulation model, it was decided to present the discussion
of the model in an appendix to avoid repetition in other sections
of the final report.
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5.0 DISCUSSION OF RESULTS
The pertinent results of the computer simulation are
shown in Table 5-1. Two important results of the calculations
can be seen. First, there is a high percentage of inerts
(84-88 wt percent) in the solids in the system streams. Secondly,
calcium sulfate was predicted to be at sub-saturated levels in
all parts of the system.
The high percentage of inerts which were computed to be
found in the process streams is explained by the high flue-gas
particulate loading data (pickup = 100 g/Nm3). This particulate
loading is tremendously high as compared to other combustion
operations such as coal-fired utility boilers which generate flue
gases containing from 4.6-16 g/m3 of particulate matter (prior to
any particulate control device). Three possible reasons exist
for the large number of particulates.
1) Cyclones or other particulate control
devices were either not used prior to
the S02 scrubber or the particulate
control equipment was not adequately
maintained.
2) The dust loading could include con-
densible and non-condensible hydro-
carbons. These hydrocarbons are
usually contained in the sinter mix
feed due to borings, turnings, and
other hydrocarbon laden materials
from other parts of the steel mill.
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N>
TABLE 5-1
System Location
Hold Tank
Scrubber Bottoms
Waste Sludge
Stream
RESULTS OF THE
Solids
CaC03
12,
8,
8.
.3
.9
.9
SCRUBBER SYSTEM SIMULATION PROGRAM
Composition (wt %)
CaSO
3
3
3
3-%H20 Inerts
.2
.3
.3
84.
87.
87.
5
8
8
Relative
Saturation
CaSOsro
6
0
1,
.39
.98
.0
CaS04 (K)
0.
0.
0.
68
81
79
Partial
Pressures (atm)
CO 2
(xlO~2)
8
7
11
.29
.97
.01
S02
(xlO-6) pH
0
10
0
.419
.57
.01.41
6.04
4.91
6.36
-------
3) The dust loading could be an incorrect
figure. Experience in U.S. sinter plants
using well maintained cyclones show
particulate loadings in the waste gases
on the order of 1-2 g/Nm3. The loading
reported by the Soviets would then be
off by 2 orders of magnitude if their
operation is consistent with U.S.
experience. The fault in the data
could then be attributed to misplaced
decimal points.
It is concluded that this third possibility is the most reasonable
explanation for the apparent inaccuracy of the Soviet data.
Further evidence that helps to support this conclusion is the sub-
saturation levels of the calcium sulfate in the computer simulation
of the system. The sulfate saturation is low because of the high
percentage of inerts in the system. The reported data shows that
there is 10 wt percent CaSOi, among the calcium species in the
waste sludge. Calcium sulfate normally has to reach the saturation
level to precipitate and be present in the waste sludge. The com-
puter simulation for the process, therefore, did not agree with
the reported behavior of calcium sulfate in the waste sludge.
More information on the composition of the process streams is
needed before the results of this process simulation case can be
used to draw reliable conclusions.
If the inlet and outlet particulate loadings were reduced
by two orders of magnitude to 2.0 g/Nm3 and 1.0 g/Nm3, respectively,
then the calcium sulfate saturation level in the waste sludge
would probably be reached and solid calcium sulfate would be
precipitated. Further computer simulation using this assumption
was not performed. Before further evaluation of the system is
performed, it is recommended that more information be obtained from
A-13
-------
the USSR. The data already supplied should first be verified
as to whether it is accurate. Secondly, more data on the operating
parameters of the system should be obtained so that the process
can be better characterized.
A-14
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CORPORATION
6.0 REFERENCES
<*
KH-027 Kharkov, "Information on the development of a method of
purifying agglomeration gases of sulfur dioxide". Point
AM-1-2 of Appendix 3, First Working Meeting of the
Soviet-American Branch Group for Ferrous Metallurgy on
Methods of Preventing Atmospheric (Air) Pollution,
pp. 1-5. Translated by E. Fitzback, SCI IRAN, Santa
Barbara, Ca., 1975.
LO-149 Lowell, P.S., Trip Notes. Gaseous Emissions Abatement
Project Visit to the USSR,. 12-24, Oct., 1975. EPA
Contract No. 68-02-1319, Task 38. Austin, Tx., Radian
Corporation.
A-15
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TR 76-261
INFORMATION ON THE DEVELOPMENT OF A METHOD OF PURIFYING
AGGLOMERATION GASES OF SULFUR DIOXIDE
[Informatsiya o razrabotke sposoba ochistke aglomeratsionnydk gazov ot
serniystogo angidrida]
Khar'kov
Point AM-.!.-?, of Apnprirb'x 3, First Working Meeting of the Soviet-American
Branch Group for Ferrous Metallurgy on Methods of Preventing Atmospheric
(Air) Pollution, pp. 1-5.
Translated for EPA by
SCITRAN (SCIENTIFIC TRANSLATION SERVICE)
SANTA BARBARA, CALIFORNIA
A-16
-------
INFORMATION ON THE DEVELOPMENT OF A METHOD OF PURIFYING
AGGLOMERATION GASES OF SULFUR DIOXIDE
Khar'kov
A Brief Description of the Technological Process for Trapping S00 from Agglo-
meration Gases.
In order to purify agglomeration gases of sulfur dioxide in the Soviet
Union, a lime method has been widely used in fields of irrigated scrubbers,
as the most effective and economical method. A line diagram of the device
is shown in Figure 1. The flue gas extractor forces the agglomeration gases
into the scrubber, where they are irrigated with a lime suspension by means
of nozzles. The process of absorption and neutralization of S0~ aay be given
in the form of a reaction:
CaC03 + S02 -v CaS03 + C02
2CaS03 + 02 + ZCaSOi,
The purified gas is discharged into the atmosphere through the smokestack. '
The constantly renewed lime suspension circulates in a closed system: part
of the spent suspension is discharged into the slurry gutter and the required
amount of fresh suspension enters the circulation collector.
Basic Technological Indices of the Industrial Device (for one system)
3
Amount of run-through gas 200,000 nm /hr
Flowrate of gas in scrubber 2.5 m/sec
3
Amount of irrigation in scrubber 1350 in /hr
Degree of purification of gas of SO^ 85%
Coefficient of efficiency
Lime 45% - 50%
A-17
-------
Ifean intake concentration of SCL in the agglo- .,
raeration gases 5-10 g/nm
BasicZquipmsnt of Sulfur Purification Devices
The supply of agglomeration gas to the scrubber is carried out by the aid
3
of a flue gas extractor with a productivity rating of 200,000 nm /hr,
head — 340 mm water column,
power of electric motor — 630 kw,
rpm — 735 rpm,
along a gas duct made of sheet steel. The gas duct is heat insulated with slag
and coated with tin plate. The scrubber is hollow with a conical bottom and
top; scrubber diameter - 6300 mm, scrubber height 24,000 mm. The scrubber
walls are made of sheet steel and on the outside are heat insulated with slag
and coated with sheet tin. They are faced on the inside with a diabase and
acid resistant plate. The top of the scrubber is made of ordinary steel chemi-
cally protected with epoxide resin. Within the scrubber are mounted 3 round
collectors vi t-h 2-n'nch involute nozzles. The collectors are made of stainless
steel pipes 219 nun in diameter. The lime suspension is fed into the collector
by a pump:
3
productivity — 1350 m /hr,
with a head of — 56 m water column,
power of electric motor — 500 kw, and
rpra — 735 rpra.
The impeller of the pump is made of a special alloy and the plate* is
corundized. The pipes which supply the lime suspension are made of stainless
steel. The operating lime suspension is fed to a cyclone filter from the
scrubber via the hydraulic valve. The characteristics of the cyclone filter
are: diameter - 2020 mm, height - 880 mm, width of the filter ( J^ ) aperture
- 10 Era. (The remainder of this page is unreadable.)
* Translator's note: due to poor quality of foreign text, precise translation
of this term is not possible.
A-18
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The circulation collector is made of sheet steel and is faced on the in-
side with an acid resistant plate. From the circulating collector, the suspension
proceeds through a pipe 500 mn in diameter to the intake pump. The spent
suspension is drawn off through a rubberized slurry gutter into the slurry col-
lector.
Diameter — 4,250 mm
Height — 3,670 mm
3
Volume — 40 m .
Transfer pumping of the spent suspension into the slurry removal system
3
is carried out by means of pumps with a productivity rating of 600 m /hr,
a head of 36 mm water column,
electric motor power of 125 kw, and
rpm - 985 rpm.
Purified gas from the scrubber proceeds along a "pure" gas duct 4,000 nun
in diameter faced on the inside with an acid resistant plate and proceeds to
the smokestack, where it is discharged into the atmosphere. The smokestack
110 meters high is made of sheet steel covered on the inside with epoxide
resin. Compensators in the "pure" gas ducts are made of rubberized fabric.
The Physico-Chcmical Parameters of the Smoke-Gas Streams Before and After Puri-
fication.
The quantitative and qualitative composition of the agglomeration plant
exhaust gases basically depends on the initial raw material and the conditions
of agglomeration. Table 1 gives the average chemical composition of agglomer-
ation gases before and after purification.
It is seen from the table that the agglomeration gases contain other com-
ponents in addition to sulfur dioxide, for example, sulfur trioxide, carbon
monoxide, and nitrous oxide. Of the components of the agglomeration gases
listed in the table, sulfur dioxide and sulfur trioxide as well as dust are
primarily trapped. All of the other components are not practically absorbed
by the lime suspension and are discharged into the atmosphere.
A-19
-------
TABLE 1
Point of
removing
gas
Before
scrubber
After
scrubber
CO,
vol.
4.0
4.1
C0(
vol.
0,6
0,€
—-
* /.
vol .
17.0
17,0
••
'%*• ~'.fi
vol. vol.
77.71 0,5
'77.7I, 0.5
t/0f
vol.
0 0^i<^
oeoio
^ r ' r
• f \ i f~ r.. i "«s 7
^7 S^V, U'^S^
o Z i / . ^
/. if/1ffl
vol. vol. |
i !
i ;
| !
' i •' M 1 i H / -''i 9 r- iH
>^ ^ ^ i JU ^/ O 4 W ' X- ^ *-'
! i
none i !
Q»Gl& 100
, I
^ "5s" ,
^X
O
-------
Figure 1.
1- scrubber; 2- flue gas extractor; 3- dirty gas duct; A- collectors with noz-
zles; 5- circulation pump; 6- supply pipe; 7- hydraulic valve; 8- filter- 9-
circulation collector; 10- slurry gutter; 11- slurry collector; 12- slurrv
pump; 13- pure gas duct; 14- smokestack.
A-21
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APPENDIX B
COMMENTS ON THE JAPANESE DATA
B-l
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CORPORATION
1.0 INTRODUCTION
The Environmental Protection Agency is interested in
determining the technical and economic feasibility of applying
lime/limestone scrubbing technology to control S02 emissions
from steel mill sinter plants. Radian Corporation has been
contracted by the EPA to investigate the feasibility of using
lime/limestone scrubbing for this application. Since there has
been no work in this area performed in the US, it was decided
to examine the operating experiences of lime/limestone scrubbing
units treating gases from steel mill sinter plants in other
countries.
As part of a first step in the study, data from
Dr. Jumpei Ando was obtained describing the operation of FGD
scrubbing systems applied to Japanese steel mill sinter plants
(AN-1.39). A copy of this information is included at the end of
this Appendix. It was hoped that the Japanese data might pro-
vide meaningful information that would be helpful in the
successful application of lime/limestone wet scrubbing systems
to sinter operations in this country. Although some important
process design information was lacking, the data provided infor-
mation on the Japanese operating experience which should prove
to be. of considerable value.
The comments presented in this report are based upon
a review of process data from Dr. Ando's report and four
additional sources (AN-138, AN-141, PE-182, HI-149). The
objectives of this assessment were-.
(1) to identify unique mechanical features of
Japanese sinter plant scrubbing processes.
(2) to summarize normal operating ranges of
important process variables,
B-2
-------
(3) to summarize Japanese operating experience,
and
(4) to identify potentially significant process
problem areas.
The approach taken to accomplish these objectives was to
examine data for four wet scrubbing processes treating flue
gas from Japanese steel mill sinter plants. The four pro-
cesses investigated were:
(1) Mitsubishi Heavy Industries (MHI) Process
installed at Kawasaki Steel plants (Lime
is used as the absorbent);
(2) Moretana Process installed at Sumitomo
Metal plants (Limestone is used as the
absorbent);
(3) Kobe Steel Calcium Chloride Process (Cal
Process) (A lime absorbent is used in a
30 percent calcium chloride solution);
(4) Nippon Steel Slag Process (SSD Process).
(Converter slag containing 40 percent CaO
is used as the absorbent).
In Section 2.0, a summary of the operating parameters
and experience for each process is presented. A discussion of
key process information is contained in Section 3.0.
B-3
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CORPORATION
2.0 PROCESS OPERATING EXPERIENCE
A description, including flow sheets, of the four
processes investigated is contained in Dr. Ando's attached
report. It was decided to summarize the operating parameters
and experience in tabular form in order to be able to effectively
determine important information. Table 2-1 contains a summary
of the operating parameters for the MHI and Moretana process.
The summary of operating parameters for the Kobe Steel calcium
chloride process is given in Table 2-2. Insufficient data were
presented to prepare a summary table for the SSD process.
It was hoped that enough information would be
available for a computer simulation of the MHI and Moretana
processes. Although a substantial amount of information was
obtained from the different sources, key operating parameters
for the processes which are necessary for a computer simulation
were missing.
The Radian process simulation model requires the
identification of process input streams and important operating
variables. Information which was lacking in order to simulate
the two Japanese processes were:
(1) limestone composition for both processes,
(2) water make-up composition for both processes,
(3) fly ash composition for both processes,
(4) the percent oxidation of calcium sulfite in
the scrubber for the Mizushima plant (MHI
process),
B-4
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TABLE 2-1
SYSTEM DESCRIPTION OF THE MHI AND MORETANA PROCESSES
MHI Process
01
System Parameter
Absorbent
Absorbent Characteristics
Absorbent Utilization
Gas Treated
(1000 Nm-Vhr)
Type of Pre-Cooler
Pre-Cooler Dimensions
(meters)
Inlet Gas Temperature
CO
Outlet Gas Temperature
From Cooler (*C)
Pre-Cooler Inlet Gas
Composition (Vol. %)
02
CO
co
Inlet S02
(ppm by Vol.)
Outlet S02
From Absorber
(ppm by vol . )
General For All
Sintering Plants
CaO
95 - 99
120 - 900
Spray Tower
12 - 17
4-8
6-12
600 - 1,200
Mizushima Plant
(No. 4 Sinter Machine)
CaO
Lime has less than
1% MgO
95
350 - 850
Designed for 750
Spray Tower
14 x 8, 26 high
57
150
13.5
5-13
400 - 1,100
20 - 50
Moretana Process
Kashima Plant
CaC03
Limestone is less than 170
MgO and is ground to pass
325 mesh
79 - 86
350 - 880
Designed for 880
Moretana Scrubber
6.5 Diameter, 24.5 high
(2 coolers used)
150
14 - 15
1 - 1.5
6-8
4-10
200 - 450
3-15
-------
TABLE 2-1 (Continued)
MHI Process
to
i
System Parameter
S02 Removal (70)
Inlet Dust
(g/Nm3)
Outlet Dust
(g/NmJ)
Dust Removal
Dust Components
Inlet Cl
(ppm as HC ')
Inlet Oily Matter
(g/Nm3)
Type of S02 Absorber
Absorber Dimensions
(meters)o
(1000 NmJ/hr)
Gas Velocity
In Absorber (m/sec)
Circulating Liquor
(m3/hr)
i ir
L/G
Slurry Cone, (wt
Inlet Liauor
pH
Sintering Plants (No. 4 Sinter Machine)
90 - 97 91 - 98
0.04 - 0.092
(ESP outlet)
Fe, Mn, Si, Pb, K,
Na, Ca, Mg, Al, Zn,
Cu, etc.
20 -50
0.057 g/Nm3
Spray Tower
Spray Tower
14 x 6.5, 30 high
2.5
10 - 14
6.5 - 7.5
6.4 - 7.5
Kashima Plant
>95
0.15 - 0.23
0.008 - 0.010
>,90
Ferric oxide
Moretana Scrubber
(perforated plate)
6.5 Diameter, 20.5 high
(2 absorbers used)
3-5
2,500
5-6
6 - 6.5
-------
TABLE 2-1 (Continued)
MH1 Process
System Parameter
Oxidation In Scrubber
(7o)
Mist Eliminator Type
Pressure Drop
(miT>H20)
Reheat Temperature ("C)
References
General For All
Sintering Plants
70 - 100
HI-149
Mizushima Plant
(No. 4 Sinter Machine)
Considerable Extent
Cooler, Absorber, and
Mist Eliminator-120
140
AN-139
Moretana Process
Kashima Plant
50
Vertical Chevrons In
Horizontal Duct
Cooler - 220-250
Absorber - 120-140
Eliminator - 20-25
Total System - 700-800
AN-138, AN-139, AN-141
td
i
-------
TABLE 2-2
oo
System Parameter
Absorbent
Absorbent
Stoichiometry
Gas Treated
(1000 NnrVhr)
Inlet Gas Temperature
Cc)
Outlet Gas Temperature
Cc)
Inlet 02 Cone.
(Vol. 7o)
Inlet S02 Cone.
(ppm)
Outlet S02 Cone. From
Absorber (ppm)
S02 Removal (%)
Inlet Dust (g/Nm3)
Dust Removal (%)
SYSTEM DESCRIPTION OF THE KOBE STEEL
CALCIUM CHLORIDE PROCESS
General For
All Sinter Plants
Ca(OH)2 in a 30%
CaCl2 solution
50 - 375
70
Pilot Plant:
15 - 16
Pilot Plant:
200 - 400
>90
Most
V
Amagasaki Plant
Ca(OH)2 in a 30% CaCl2
solution
1.05
350
120
70
14 - 16
240 - 400
20
91 - 94
0.05 - 0.2
50
/,
Slurry Cone.
(wt 7o)
Type of Absorber
In Pre-Cooler
Spray Tower
Spray Tower
-------
_ System Parameter
Absorber Capacity
(1000 Nm3/hr)
Absorber L/G
Slurry Cone. In Absorber
(wt %)
Absorber Inlet Liquor pH
Absorber Outlet Liquor pH
Oxidation in Scrubber (%)
Pressure Drop
(mm H20)
TABLE 2-2 (Continued)
General For
All Sinter Plants
2
30
7
5.5
Pilot Plant - 30
AmagasakiP1ant
175 (2 absorbers used)
3
30
6-8
750
Cooler, Absorber and
Mist Eliminator - 190
MD
References
AN-139, PE-182
AN-138, AN-139
-------
CORPORATION
(5) the scrubber effluent hold tank volume
or residence time for both processes.
The last two pieces of information are most important, and
are needed to adequately characterize any lime/limestone wet
scrubbing system.
The operating experience of the four processes is
given in Table 2-3. In general, the availability of the
Mizushima plant (MHI process) and the two plants using the
Moretana process was high.
B-10
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TAIil K 2-3
OPERATINC liXPIjlUKNCE 01'' 1.IHI5/1.7HESTONK SCKIIIili I Nli
UNITS ON STKIil. Mil.I. S'lMTKK PLANTS IN JAPAN
Mill Process
Pa ramcter
FCD System
Oeneral For All
Sintering Plants
Absorbent=CaO
Gas Treated3 .,
120,000-900,000 NMJ
hi:
Mi.xushi.mil Plant
(Si.iU-ei: Machine /M)
Absorbent=CaO
Cas Treateil=
750,000 NM£
hr
Moretana Process
Ahsorbent=CaCO.j
Cas Treated^
Kashiina Pl;mt=
880,000 NM-*
hr
Wakayama l'lant=
370,000 NM3
hr
Kobo Steel
Col Process
Nippon Stoul
SSIJ Process
Absorbont=Ca (Oil) v Absorbent=Converter
in a 30 percent Slag
Cul'.l... solution
Cas Treated=
Pilot P!aiit =
50,000 NM2.
lir
Aiuaj-'asaki Planl:=
350,000 NM£
(ias 'l'reati;cl=Tol)at:a
Prototype Pl;iiiU =
200,000 NMJ
Start-Up Date
First plant completed
in L973
November, 1974
KM si lima PI ant-September
1975
Wakayama Pliint-May,
1975
Pilot Plant-
June to Decem-
ber, I 9 Ti
197-'.
Monthly
Avai.labi.l i.ty (7.)
90 - 95+
Kashlma - 100
Wakayama - 98
Opera t i nj^ Ex per Lei ire
J) The incoming j'iis
laden with oily matter
caused swelling of
rubber linings of a
pre-cooler on one
ins till'I at ion. This
problem was solved
by using oil resis-
tant rubber linings.
2) Using the pll of
the reci.rculat ing
slurry as a control
factor, all of the
scrubbers are rnnn-
i ng with exceI lent
stabi 1 i.ty. The S09
concentration of
fh.ie g.'ises I'rom sin-
tering plants changes
Several minor problems
occurred in the first
three months result-
ing in about 907- sys-
tem avail ahll i ty :
I) Corrosion of the
impeller of the
cooler circulation
pump.
2) Stop-up of the
lime-slurry pump.
3) Breakage of a
firebrick in the
furnace(reheater).
These problems were
solved and nearly
lOO"/. availability
Wakayama Plant: Tiie FCD
system has been in
smooth operation except
for ;i defect in the plas-
tic lining in a cooler
which was found at the
beginning of the opera-
tion and was repaired.
Kashiina Plant: Slight
corrosion has been ob-
served in the gas coolers
of the FCJI) system which
are constructed with 316
stainless steel anil
partially with a high
Ni-Cr alloy.
Pilot Plant:
1) A soft de-
posit formed on
the wal1 of the
absorber when
the I./C ratio
was smaller than
I but the de-
posit could he
washed off by
using an L/C
larger than 2.
2) Corrosion has
been the main pro-
blem. Stainless
steoI, plastic,
and rubber linings
are used for the
mater ia I . Hecaiisc
There lias been some
seal ing problem to
be solved lo ensure
a long-term con-
t i nuous opera L i on.
-------
TABLE 2-3 (Continued)
Milt 1'rr.ccss
Paramter
SinterLng Plants (Sinter Machine
Moretuma Process
Operating Experience:
(Continued)
I
I—1
to
References
from 800 - 1,200 ppm
every 20 minutes. Kven
at this kind of: fluctua-
tion, the FGI) system
operated with high and
stable SO, removal.
3) The sulflte oxida-
tion in the scrubber
reaches as high as
1007.. Scaling was
prevented by:
a) Addition of
gypsum "seed"
crystals to pro-
vide seed sites
for calcium sul-
fate crystal Iiza-
t ion.
b) liigh L/C. was
used. A scrubber
with a simple
structure was used
to maintain uniform
chemical conditions
of the scrubbing
slurry and to keep
all the internals
wet and clean.
4) Combustible flue
gases from steel mills
were burned to reheat
the scrubber gas.
was obtained in the
next three months.
111-149
AN-139
AN-138, AN-139
AN-141
f\uuc: o ice I
C'a I Process
die lower part
of tlie cooler,
where the hot
gas is intro-
duced was
corroded sever-
ly, the part
was replaced by
titanium, which
is durable.
iii ppoii .^Lee i
SSIJ Process
3) Concentra-
tions of magnes-
ium and other Im-
purities increased
in the absorber liquor
but caused no problem.
4) The plant
operated without
scaling and waute-
w;iter problems.
AinJKflsak i Plant:
'I'ho Tallowing pro-
hlems were en-
countered during
the two month test
run:'
I) Unusual vibration
of a centrifuge.
2) Wearing of: a con-
trol valve.
3) Scaling of a pll
mefer electrode.
4) Breakage of rubber
lining in a reducer.
These problems were
solved and the plant
went into commercial
operation in April,
1976.
l'E-1.82, AN-139 AN-I 39
-------
CORPORATION
3.0 DISCUSSION OF THE SYSTEM DATA
The operating parameters for the two lime/limestone
processes (MHI and Moretana processes) are, of course, more
important for this study since these systems are very
similar to the type of FGD system considered in this project.
But, the information obtained for the Cal and Slag processes
should not be neglected since CaCOo and CaO are the absorbents
in these systems respectively.
Several important pieces of information were obtained
from the data on the MHI and Moretana processes.
(1) An inlet Cl concentration of 20-50 ppm in
the flue gas was reported. High chlorine
concentrations in wet scrubbing systems can
cause corrosion.
(2) The oxidation in the scrubber was reported
to be between 70-100 percent. Scaling was
prevented by recycling gypsum as seed crystals,
using a high liquid to gas ratio (L/G), and
by using a scrubber with a simple structure.
(3) The oily matter in the incoming gas
necessitated the use of oil resistant rubber
linings to prevent swelling.
(4) The S02 concentration in the flue gas
fluctuated between 800-1200 ppm every
20 minutes. High and stable S02 removal
was still obtained under these conditions.
B-13
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CORPORATION
These four points need to be considered when designing a lime/
limestone wet scrubbing system for a sinter plant facility.
It was reported for the Kobe Steel calcium chloride
process that concentrations of magnesium and other impurities
increased in the absorber liquor but caused no operating
problems. The magnesium and other impurities mentioned did not
cause a problem in this facility, but these species can affect
process chemistry and should be considered in any FGD system
design.
The Nippon Steel slag process experienced complete
oxidation of the lime absorbent to calcium sulfate. It was
reported that the prototype plant encountered some scaling
problem that remains to be solved to insure a long-term con-
tinuous operation.
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CORPORATION
4.0 SUMMARY
Lime/limestone wet scrubbing has been successfully
applied to steel mill sinter operations in Japan. About nine
commercial lime/limestone scrubbing installations (excluding
the Cal and SSD processes) will be operating on sinter plants
by the end of 1976. Operating data from existing facilities
have shown high system availabilities with minor operating
problems. The S02 removal efficiency has been consistently
over 90 percent with very high lime or limestone utilizations,
B-15
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CORPORATION
5.0 REFERENCES
AN-138 Ando, Jumped., "Status of Flue Gas Desulfurization and
Simultaneous Removal of S02 and NOX in Japan",
Presented at the Flue Gas Desulfurization Symposium,
New Orleans, March 1976.
AN-139 Ando, Jumpei, "Desulfurization of Flue Gas from Iron-
Ore Sintering Plants in Japan", Tokoyo, Chuo Univer-
sity, May 1976.
AN-141 Ando, Jumpei, Private communications, Chou University,
29 May 1976.
HI-149 Hirai, M., et al., "MHI Flue Gas Desulfurization
Systems Applied to Several Emission Sources",
Presented at the 6th Flue Gas Desulfurization Sympo-
sium, New Orleans, March 1976.
PE-182 Pedco Environmental, Inc., Untitled Preliminary
Draft, regarding recent developments in desulfuriza-
tion technology in Japan up to January 1975.
B-16
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DESULFURIZATION OF FLUE GAS FROM
IRON-ORE SINTERING PLANTS
IN JAPAN
(May, 1976)
Jumpei Ando
Faculty of Science and Engineering
Chuo University
Tokyo
B-17
-------
CONTENTS
1. INTRODUCTION
2. MIZUSHIMA PLANT, KAWASAKI STEEL (MHI PROCESS)
3. KASHIMA PLANT, SUMITOMO METAL (MORETANA PROCESS)
4. KOBE STEEL CALCIUM CHLORIDE PROCESS (CAL PROCESS)
5. NIPPON STEEL SLAG PROCESS (SSD PROCESS)
ADDRESSES OF STEEL PRODUCERS AND PROCESS DEVELOPERS
REMARKS
The metric system is used in this report. Some of the conversion
figures between the metric and American systems are shown below:
1m (meter) =3.3 feet
lin (cubic meter) = 35.3 cubic feet
It (metric ton) =1.1 short tons
1kg (kilogram) = 2.2 pounds
1 liter =0.26 gallon
Ikl (kiloliter) =6.29 barrels
The capacity of flue gas desulfurization plants is expressed in
Nm"'/hr (normal cubic meters per hour),
INm /hr = 0.59 standard cubic foot per minute
L/C-- ratio (liquid/gas ratio) is expressed in liters/Nm .
1 liter/Nm = 7.4 gallons/1,000 standard cubic feet
For monetary conversion, the exchange rate of 1 dollar = 300 yen is used,
B-18
-------
1. INTRODUCTION
In 1974 the Japanese steel industry produced 114 million tons
(metric tons) of crude steel and spent $563 million for pollution
control, which was equivalent to 18.5% of the total investment made
by the industry in that year. Many desulfurization units have been
installed since 1971 to treat flue gas from iron-ore sintering plants,
the major source of SO- emission from the steel industry (Table 1).
As the absorbent, a lime slurry is used by Kawasaki Steel (MHI process),
a limestone slurry by Sumitomo Metal (Sumitomo-Fujikasui Moretana
process), a slurry of pulverized converter slag by Nippon Steel (SSD
process) and a calcium chloride solution dissolving lime by Kobe Steel
(Cal process). All of those plants by-produce gypsum. On the other
hand, Nippon Kokan uses ammonia scrubbing to by-produce ammonium
sulfate or gypsum by reacting lime with the sulfate.
By 1977, 22 FGD plants will be in operation with a total capacity
of treating 13,800,OOONm3/hr (8,120,000scfm) flue gas, which is about
one-half the total gas from all sintering plants in Japan.
Flue gas from sintering plants is characterized by a high 02
concentration (12-16%), relatively low SO- concentration (200-1,OOOppm),
and a dust content rich in ferric oxide. Oxidation of sulfite into
sulfate occurs in the scrubbers much more readily than with flue gas
from a boiler, because the oxidation is promoted by the high O^/SO™
ratio and also by the catalytic action of the ferric oxide.
The present report will describe mainly the lime and limestone
processes and the dimensions and performance of the plants.
B-19
-------
Table 1.
S02 REMOVAL INSTALLATIONS FOR WASTE GAS FROM IRON-ORE SINTERING MACHINES
Steelmaker
Kawasaki Steel
n
n
"
ii
"
Sumitomo Metal
t;
D3 "
g
n
Kobe Steel
- "
ii
Nakayama Steel
Nippon Steel
"
Nippon Kokan
n
Plant site
Chiba
11
n
Mizushima
"
"
Kashima
Wakayama
Kokura
Amagasaki
Kobe
Kakogawa
Osaka
Tobata
Wakamatsu
Keihin
Fukuyama
Ogishima
Gas treated
(l.OOONm /hr) Process
120 M1-1I
320 "
650
750
900
750
880 Moretana
1,000 "
1,000
370
720
175 x 2 Cal
375 "
1,000 x 2 "
375
200 SSD
1,000 "
150 NKK
760
1,230 "
Absorbent
CaO
n
n
n
11
n
CaCO_
n
n
n
Ca (OH)
11
n
"
Slag
"
NH~, CaO
NH *
Year of completion
1973
1975
1976
1974
1975
1977
1975
1976
1977
1975
1976
1976
1976
1977
1976
1974
1976
1971
1976
1977
Gypsum (t/year)
3,600
13,200
26,500
27,600
32,400
27,600
32,400
40,500
40,500
14,400
26,500
12,600
12,600
72,000
13,500
7,200
32,400
7,200
12,000**
20,000**
* Ammonia in coke oven gas
** Ammonium sulfate
-------
2. MIZUSHIMA PLANT, KAWASAKI STEEL (MHI PROCESS)
Layout of Sintering Machines and FGD Plants
Kawasaki Steel installed FGD plants first at its Chiba works
using the lime-gypsum process developed by Mitsubishi Heavy Industries,
Satisfied with their operation, Kawasaki Steel introduced larger FGD
plants at its Mizushima Works, where four iron-ore sintering machines
with a unit capacity of 8,000-15,OOOtons/dayhad been installed. The
FGD plants were erected in an iron ore storing yard adjacent to the
sintering plants (Figure 1). FGD plants for No. 3 and No. 4 sinter-
ing machines are in operation and a plant for No. 1 and No. 2 machines
is under construction.
No. 4 Sintering Machine
Specifications of the No. 4 machine are shown in Table 2. The
machine has 22 wind boxes. The amount, temperature and composition
of gas from the wind boxes are shown in Figure 2. The total amount of
3
the gas reaches l,100,OOONra /hr. The S02~rich gas, about a half of
the total, is selected by means of dampers as is shown in Figure 3
and sent to the FGD plant. The S02 concentration in the selected gas
ranges from 400 to l,100ppm while that in the rest of the gas ranges
from 40 to 90ppm.
Table 2. SPECIFICATIONS OF No. 4 SINTERING MACHINE
Equipment
Sintering machine
Main blower
Dust collector
Cooler
Type
Dwight-Lloyd
Induced fan
Electrostatic
precipitator
Lurgi
Specifications
Capacity 15,000t/day
2
Fire grate 410m
Capacity 21,000m /min x 2
Motor 7,800kW x 2
Capacity 21,000m /min x 2
Dust(Inlet 1'°8/Nm
(outlet 0.06g/Nm
2
Cooling area 550m
Cooling fan 15,000m /min x 2
B-2I
-------
Cd
i
ro
FGD plant under construction
for No.l and No.2 sintering machines
i"Fv-T--^< "^Li!
Sintering machines
(No.3 and No.
100m
A: Scrubber, etc.
B: Lime preparation
C; Dust treatment
D: Wastewater treatment
E; Control room
I Gas from No.l and No.2
sintering machines
Figure 1 Layout of FGD plants (Mizushima plant, Kawasaki Steel)
-------
0) .S
B \
r-i "a
O 2
> O
O
to o
rt
80
60
40
20
0
1,000
0
O.
3 'hO
w ts
07 B
0) S
fc -^
a,
B o
-------
Cd
i •
ro
Duct to FGD plant
22-20
18
19
T
i
17 - 10
9,8
7-1
Duct to stack(without FGD)
Fan
E.P. Fan
Stack
Figure 3 Gas flow from No.k sintering machine
( Figures show wind box numbers)
-------
FGD Plant for No. 4 Machine
The plant uses the MHI process with one absorber and has a
capacity of treating 750,OOONm /hr flue gas (Figure 4). The gas at
about 150°C containing 500-1,OOOppm S02 and about 13.5% 02 is first
cooled to 57°C in a cooler with water sprays and led into a plastic
grid packed absorber, where it is treated with a lime slurry at pH
o
6.4-7.5 at an L/G ratio of 7 liters/Nm (about 50 gallons/1,OOOscf)
and has more than 90% of S02 removed. The treated gas passes through
a mist eliminator, is heated to about 140°C by after-burning, and
sent to a stack. A calcium sulfite slurry discharged from the
absorber is acidified to pH 4 by adding sulfuric acid, led into an
oxidizer, and oxidized into gypsum by air bubbles generated by a
rotary atomizer. The gypsum slurry is sent to a thickener and then
centrifuged to less than 10% moisture. The by-product gypsum is sold
as a retarder of cement setting. The liquor from the centrifuge is
returned to the thickener; the thickener overflow is returned to the
absorber after lime is added.
A portion of the circulating liquor of the cooler is neutralized
with lime to recover low-grs.de gypsum. The liquor from the centrifuge
is sent to a wastewater treatment system and reused.
The specifications of the FGD unit are shown in Table 3. As the
calcium sulfite is oxidized to a considerable extent in the absorber
due to the high concentration of oxygen in the gas, the gypsum is
recycled to the absorber as crystal seed in order to prevent scaling.
To ensure high operability of the plant, spare units have been provided
for major pumps and the centrifuge. Ah automatic system has been
installed to shut down and restart the plant with the sintering machine.
B-25
-------
Mist eliminator
-H2SO<,. Oxidizer
Centrifuge
To . wastewater treatra^ifC
Low-grade
gypsum
Liquor tank
Gypsum
Figure ^. Flowsheet of MHI lime-gypsum process ( one-absorber system)
-------
Table 3. SPECIFICATIONS OF FGD UNIT FOR No. 4 SINTERING MACHINE
(Capacity 750,QOONm /hr)
Cooler 14m x 8m, 26m high
Absorber 14m >: 6.5in, 30m high
Blower 750,OOONm3/hr, 2,400kW
Total pressure 380mmH20
Mist eliminator 14m x 13m, 9.5m high
Oxidizer 3.2m diameter,!5. 6m high
Performance
The FGD plant for the No. 4 machine went into operation in
November 1974. The performance is shown in Figure 5. The gas volume
o
fluctuated from 350,000 to 850,OOONm /hr and inlet SO, concentration
from 400 to l,100ppm. The S02 removal efficiency was 91-98% and the
SO. concentration at scrubber outlet ranged from 20 to SOppm.
Availability (FGD operation hours per cent of total hours) was about
90% for the first three months because of several minor troubles such
as corrosion of the impeller of the cooler circulation pump, stop-up
of the lime-slurry pump, and breakage of a fire-brick in the furnace.
Those problems were solved and nearly 100% availability was obtained
in the next three months. The low availability in May 1975 (about
90%) was due to a shut-down of the sintering machine.
On the average, the gas velocity in the scrubber is about
2.5m/sec and the total pressure drop in the cooler, absorber and mist
eliminator is about ^OmmHoO. Lime with less than 1% MgO has been
used. The by-product gypsum contains about 7% moisture after being
centrifuged and has an average crystal size of about 40 microns. The
requirements for the operation are shox
-------
-P x-^
a> ^
-P N
3 0
O t/5
T3 <"v
«x
t, a
>
U O
td H
^
OJ X
rH -P
•H -H
«J H
> -H
^^
.
tC >>
> 0
o c
B d)
(D iH
f-i W
•H
- — — — o^ ^
*• • V
XK^ N>
^ • • .
. cf
_
9^^*—^^t ^^.
-
-
^ft °- 'a**'*^^ ^--"°"
X . ^^
^^
m
1 1 1 i l 1 1
Nov. Dec. .Jan. Feb. Mar. Apr. May
197^ 1975
Figure 5 Performance of FGD plant for
No.k sintering machine
B-28
-------
slightly less than 1 mole lime to 1 mole inlet S0? has been vised to
obtain about 95% removal and thus the consumption of sulfuric acid
has been reduced.
Table 4. REQUIREMENTS OF FGD PLANT FOR No. 4 SINTERING MACHINE
Power (103kWhr)
Fuel* (106kcal)
Air** (103Nm3)
CaO (t)
H2S04 (t)
Water (10 3m3)
1974
Dec.
2,000
7,000
2,500
500
24
37
1975
Jan.
2,300
7,000
1,800
600
18
11
Feb.
2,100
6,300
1,900
460
19
24
Mar.
2,500
7,000
1,800
530
13
24
Apr.
2,600
10,000
1,900
470
8
29
Mav
2,100
2,900
2,300
360
7
19
!
* For reheating
** For oxidation
B-29
-------
3. KASHIMA PLANT, SUMITOMO METAL (MORETAMA PROCESS)
Moretana Process
Sumitomo Metal is operating two plants and constructing three
more (Table 1), all using the Moretana process developed by Sumitomo
jointly with Fujikasui Engineering Co. The process is characterized
by the use of the Moretana scrubber fitted with four perforated plates
made of stainless steel. The holes range from 6 to 12mm in diameter
and the plate thickness from 6 to 20mm. Both dimensions are varied
depending on the specific scrubbing conditions. The free space in
the cross section ranges from 25 to 50%. The bottom tray serves
mainly as a gas distributor and the upper three serve as absorbers.
The gas and liquid flows are so adjusted as to maintain a liquor head
of 10 to 15mm on each plate. The gas velocity is higher than in
usual scrubbers. The design gives extreme turbulence, producing foam
layers 400 to 500mm thick, and thus ensures a high SO^ and dust removal
ra'zio. The mist eliminator is a set of vertical chevron sections
mounted in a horizontal duct after the scrubber.
A flowsheet of the process is shown in Figure 6. Gas from a
sintering machine is first treated with water in a Moretana scrubber
for cooling and to remove more than 90% of dust. Removal of ferric
oxide dust is useful in reducing the oxidation in the absorber to
ease scale-free operation. The gas is then treated with a limestone
slurry (or a mixed slurry of lime and limestone) 10-20% in excess of
stoichiometric amount in a second Moretana scrubber to remove more
them 95% of S02> The limestone contains less than 1% MgO and is ground
to pass 325 mesh. The calcium sulfite slurry discharged from the
scrubber is sent to a clarifier, and then to a pH adjusting tank where
the pH is adjusted to about 4.0 by adding a small amount of tLSO, .
B-30
-------
td
i
CO
Sintering
machine
After-
burner
From No.2 train
pH adjusting
tank
H2SO
Oxidizer Tank
Figure 6 Flowsheet of Moretana process
-------
Tae slurry is then sent to an oxidizer developed by Fujikasui to
convert calcium sulfite to gypsum. The gypsum slurry is centrifuged,
and the filtrate is returned to the absorber.
The discharge from the cooler is sent to a thickener. The
overflow is returned to the cooler; the underflow is filtered. The
filter cake is returned to the sintering machine and the filtrate is
sent to a wastewater treatment system.
Kashima Plant, Sumitomo Metal
3
The Kashima plant with a capacity of treating S80,OOONm /hr gas
was started up in September 1975 and has since been in stable
operation. All the gas from a sintering machine ranging in flow rate
3
from 350,000 to 880,OOONm /hr is treated. The gas contains 200-450ppm
S02, 14-15% 02, 6-8% C02, 1-1.5% CO, 4-10% H20, and 0.15-0.23g/Nm3
dust at about 150°C. The scrubbing units consist of two trains each
o
with a capacity of treating 440,OOONm /hr gas. The Moretana scrubber
works normally with a gas velocity between 3 and 5m/sec. When the
gas flow rate is low one train only is used. The size of the equip-
ment and operation parameters are shown in Tables 5 and 6.
Table 5. SIZE OF EQUIPMENT
Facility Number
Cooler 2
Absorber 2
MLst eliminator 2
Oxidizer 2
Centrifuge 4
Size (Specification)
6.5m (dia.) 24.5m (height)
6.5m (dia.) 20.5m (height)
6 x 6m, 2.4m (length)
2.8m (dia.) 5.4m (height)
550kg/hr each
B-32
-------
Table 6. OPERATION PARAMETERS
Cooler:
Space velocity
Circulated liquor
Dust content
Absorber:
Space velocity
Circulated liquor
pH of the liquor
S0« content
Mist eliminator:
Gas flow
Washing liquor
Pressure drop:
Cooler
Absorber
Eliminator
Total
By-product gypsum;
Moisture
Crystal size
4.4 to 5.0mm/sec
•3
5,000m /hr in two towers
0.15-0.23g/Nm3(inlet), 0.008-0.010g/Nm3(outlet)
4.4 to 5.0m/sec
3
5,500m /hr in two towers
6 to 6.5
250-400ppm (inlet), 3-10ppm (outlet)
5.5-6.0m/sec
40m /hr in two units
220-250mmH20
120-140mmH20
20-25mmH20
700-800mmH20
6.0-9.5% (after centrifuge)
Larger than 50 microns
Operating hours of the sintering and desulfurization plants are
listed in Table 7. Operability of the desulfurization plant has been
maintained at 100%.
B-33
-------
Table 7. OPERATION OF KASHIMA PLANT
1975 1976
Sept. Oct. Nov. Dec. Jan. Feb. Mar.
Operating hours
Sintering plant 705 729 683 725 729 654 716
Desulfurization plant (501)* 729 683 725 729 654 716
Availability of
sintering plant
Operability of
desulfurization plant (100) 100 100 100 100 100 100
* Started operation in September
Performance of the No. 1 train is shown in Figure 7. Inlet and
outlet SO™ concentrations have been 300-450 and 3-15pptn respectively.
The L/G ratio in the absorber is about 5 liters/Nm3 (36 gallons/1,OOOscf).
Construction and operation costs for the Kashima plant are shown
in Table 8.
Table 8. COSTS FOR KASHIMA PLANT
Plant cost ($1,000) 15,000
Running cost ($l,000/month)
Power 121
Fuel 121
Limestone, chemicals 47
Other 38
Fixed cost ($l,000/month) 286
Total 613
Sintered product (t/month) 283,384
Desulfurization cost ($/t) 2.16
B-34
-------
Cd
i
LO
en
Sept. 10
o
B
300 _
200
Q)
tn
2
to
S
0
Oct. 1
Oct. 25
Cooler
Absorber
Mist eliminator
500
ifOO
300
200
30
o
05 20
10
0
B
a,
Inlet
Outlet
Failure of
S02 meter
-«—•—•—•—•—* »—«—e—•—v—e—*-—•—»-
Figure 7 Operation data of No.l train, Kashima plant
-------
Wakayama Plant, Sumitomo Metal
3
An FGD plant at Wakayama with a capacity of treating 375,OOONm /hr
waste gas from a sintering machine started operation in May 1975 and
has since been in smooth operation except for a defect in the plastic
lining in a cooler which was found at the beginning of the operation
and was repaired. Operability of the plant is 98% except for the
(scheduled shutdown of the sintering plant that normally occurs about
avery two months. The mist eliminator is washed intermittently
(once in 30 minutes) with the circulating liquor and fresh water
alternately. The pressure drop in the mist eliminator which is 30mm
H~0 at the beginning gradually increases while it is washed with the
circulating liquor. When the pressure drop reaches 50mm, fresh water
±s used in place of the liquor until the pressure drop returns to 30mm.
'Che ratio of liquor to fresh water is about 80 to 20.
B-36
-------
4. KOBE STEEL CALCIUM CHLORIDE PROCESS (CAL PROCESS)
Process Description
Kobe Steel has developed a new process using a 30% calcium
chloride solution dissolving lime as the absorbent. A pilot plant
2
(50,OOONm /hr) has been operated and two commercial plants (Table 1)
have just come on-stream to treat waste gas from iron ore sintering
plants.
Calcium chloride solution dissolves 6-7 times as much lime as
does water. High S0? recovery is attained at a low L/C of 3 liters/
3
Nm . The flowsheet is shown in Figure 8.
Waste gas is first cooled in a cooler to which a calcium chloride
solution (about 5%, from a gypsum centrifuge) is fed to cool the gas
to about 70°C and to remove most of the dust. The solution is con-
centrated here to about 30% and is sent to a scrubber system after
dust removal by filtration. The gas is then led into an absorber in
which a calcium chloride solution (about 30%, at pH 7 dissolving lime)
is sprayed to remove more than 90% SO-. The gas is then passed
through a mist eliminator and sent to a stack. The liquor discharged
from the absorber at pH 5.5 containing calcium sulfite is sent through
a thickener to a centrifuge to separate most of the solution, which
is sent to a tank where calcium hydroxide is dissolved to raise the
pH to 7. The calcium sulfite sludge from the centrifuge is repulped
with water and some sulfuric acid to produce a slurry at pH 4. The
slurry is oxidized by air bubbles into gypsum, which is then centri-
fuged. The liquor from the centrifuge containing about 5% calcium
chloride is returned to the cooler giving no wastewater at all.
Since vapor pressure of the liquor is low, the temperature of
the gas after the scrubbing reaches 70°C as compared with the 55-60°C
for the usual wet process and thus less energy for reheating is required.
The mist eliminator is washed with the circulating liquor. The
solubility of gypsum in the liquor is very low (nearly 1/100 of that
in water) and the evaporation of the liquor does not cause scaling.
B-37
-------
i
u>
oa
Cnnler
After-
burner
-, . Centrifuge
eliminator _ °
Figure 8 Flowsheet of Cal process
-------
Continuous operation of the pilot plant for about 6 months showed
that a soft deposit formed on the wall of the absorber when the L/G
ratio was smaller than 1 but the deposit could be washed off by using
an L/G larger than 2. A highly corrosion-resistant material is
required for the cooler; the lower part where the hot gas comes in
is made of titanium.
Amagasaki Plant
The Amagasaki plant has two trains, each with a capacity of
treating 175,OOONm /hr flue gas at 120°C containing 240-400ppm SO-,
3 " ^
0.05-0.2g/Nm dust and 14-16% 02> The plant went into test operation
in February 1976. The following problems were encountered during the
two months' test run:
Unusual vibration of a centrifuge
Wearing.of a control valve
Scaling of pH meter electrode
Breakage of rubber lining in a reducer
Those problems have been solved and the plant went into commercial
operation in April 1976. The S02 removal efficiency ranges from
91-94%. The dust removal efficiency runs to about 50%. Gas velocity
in the absorber is 3m/sec. Total pressure drop in the cooler,
absorber and mist eliminator is 190mmH«0. The L/G ratio is 4.0 in
the cooler and 3.0 in the absorber. More than 50% of calcium sulfite
is oxidized in the absorber. The by-product gypsum has an average
crystal size of about 40 microns and contains about 8% moisture and 0.1%
chlorine after being centrifuged. The designed and actual require-
ments are listed in Table 9.
B-39
-------
Table 9. REQUIREMENTS AT AMAGASAKI PLANT
Designed value Actual value
Power (kWhr/hr) 1,830 1,372
Water (t/hr) 20 6.2
Steam (t/hr) 2 1.8
Sulfuric acid (kg/hr) 106 50
Slaked lime (kg/hr) 328 150
Calcium chloride
(35% solution, kg/hr) 60 50
B-40
-------
5. NIPPON STEEL SLAG PROCESS (SSD PROCESS)
Nippon Steel has developed a process which uses converter slag
as the absorbent (Figure 9). The slag contains about 40% CaO, 16%
SiO , 3% MgO, 3% Al 0 , and 35% FeO and Fe 0 and has no current uses.
Nippon Steel has operated a prototype plant with a capacity of treating
200,OOONm /hr waste gas from a sintering plant since 1974. A commercial
o
plant (l,000,OOONm /hr) has just started operation.
The process is similar to other lime/limestone-gypsum processes
except that it uses no oxidizer. The gas is cooled and led into two
absorbers in series to remove 95% of SO,.,. The slag is fed to the
second absorber to produce a calcium sulfite slurry which is led to
the first scrubber and entirely oxidized into gypsum in the scrubber
due to a low pH and the presence of much iron compounds which act as
a catalyst. The by-product gypsum contains about 40% impurities and
has been discarded. The prototype plant has encountered some scaling
problem to be solved to ensure a long-term continuous operation. The
process may be useful for steel producers who normally have large
amounts of useless slag.
B-41
-------
Absorber(l) Absorber(2) [ 1 Mist eliminator Reheater
CO
i
-p-
r-o
Wastewater
pit
Compressor
V
Gypsum /'K
FIGURE 9 - FLOWSHEET OF SSD PROCESS
-------
ADDRESSES OF STEEL PRODUCERS AND PROCESS DEVELOPERS
The addresses of the steel producers and process developers
described in this report are listed below:
Kawasaki Steel Co.
1-12-1, Yurakucho, Chiyoda-ku, Tokyo
Sumitomo Metal Co.
5-15, Kitahama, Higashi-ku, Osaka
Kobe Steel Co.
1-36-1, Wakihamacho, Fukiai-ku, Kobe
Nippon Steel Corp.
6-17-2, Ginza, Chuo-ku, Tokyo
Mitsubishi Heavy Industries (MHI)
2-5-1, Marunouchi, Chiyoda-ku, Tokyo
Fujikasui Engineering Co.
1-4-3, Higashigotanda, Shinagawa-ku, Tokyo
B-43
-------
RADIAN
CORPORATION
APPENDIX C
DESCRIPTION OF RADIAN'S PROCESS
SIMULATION MODEL
C-l
-------
RADIAN
CORPORATION
1.0 INTRODUCTION
Radian has developed a computerized process simulation
model, for lime/limestone wet scrubbing systems. The program
utilizes equipment modules to represent the wet scrubbing system
so that different process arrangements can be simulated. The
following discussion is a rather brief description of Radian's
process simulator as applied to limestone wet scrubbing systems.
C-2
-------
RADIAN
CORPORATION
2.0 PROCESS DESCRIPTION
A simplified flow diagram of the conceptual limestone
scrubbing system is given in Figure 2-1. In this system the
incoming flue gas is scrubbed with a limestone slurry in the
spray tower. The scrubber bottoms are combined with fresh lime-
stone and recycled slurry from the clarifier in a stirred hold
tank where dissolution of limestone and precipitation of calcium
sulfate and sulfite occur. The major portion of the tank efflu-
ent is returned to the scrubber. The minor portion of the tank
effluent is fed to the clarifier, where some additional lime-
stone dissolution and precipitation of calcium sulfate and
sulfite may take place. The clarifier underflow is solid waste
which exits the process.
The following sections describe the operation of
various process components in more detail. Important design
relationships are introduced which must be dealt with in some
fashion in the process calculation scheme described in Section
3.0.
2.1 Scrubber
The primary purpose of the spray tower is to provide
interfacial area for transfer of SOa from the flue gas to the
alkaline slurry. Gas passing upward through the scrubber is
contacted with fine droplets of slurry introduced at the top
of the tower via spray nozzles. SOa is absorbed by these drop-
lets as they fall through the tower. Limestone present in the
slurry droplets may dissolve and the absorbed SOa may precipi-
tate as CaS03-%H20, or if it be oxidized, as
C-3
-------
STACK GAS
o
I
FLUE
GAS >
LIMESTONI
MAKE-UP
WATER
4
\
i
A
A
\
„
i
/
/
\
' ^
C\
S
\ /
^ /
^
r \
/
^
\
\
^
r
/
/
^
^•
f
/
i
\
*
^\^J
SOLID
WASTE
FIGURE 2-1 FLOW DIAGRAM OF SIMULATED LIMESTONE SCRUBBING PROCESS
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CORPORATION
A sophisticated mathematical treatment of a spray tower
would probably be formulated in terms of mass transfer rate to
an individual slurry droplet of a given size. The overall mass
transfer performance would then be calculated by considering the
number and size distribution of droplets in the total spray. In
the absence of such a detailed description of physical phenomena
in the spray tower, its overall performance may be discussed using
conventional mass transfer terminology derived for packed-tower
design. The following discussion is based upon the performance of
a spray tower and should not be used to describe other types of gas-
liquid contactors.
The usual design problem in application of an absorber
is to select a scrubber size and liquid rate to attain a specified
absorption efficiency for a given throughput of gas. The design
relationship for these parameters may be written (normally for a
packed tower) as in Equation 2-1).
K aV
-£— = N.T.U. (2-1)
nG
Here, K (Ib mole/hr-ft2) is the overall gas phase mass transfer
coefficient, a (ft2/ft3) the interfacial area per unit volume of
contactor, nG (Ib mole/hr) the gas flow rate, and N.T.U. the number
of overall gas phase mass transfer units. The overall packed
height of the tower is calculated as follows:
HT - (N.T.U) (H.T.U) (2-2)
Here, H.T.U. is the height of an overall gas phase mass transfer
unit.
C-5
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N.T.U. may also be defined in terms of the amount of
absorption and the actual and equilibrium mole fractions of the
gas being absorbed (S02 in this case).
out
N.T.U. = - f dy
in ^ '
When y is very small, as in S02 scrubbing where the S02 concen-
tration is in the ppm range, then the (1-y) term is approximately
equal to 1.
Y
out
N
. T. U. = - f dy
•/ V —V~
For systems near atmospheric pressures and with small pressure
differentials, the N.T.U. m£y be expressed in terms of partial
pressures.
Pout d
N'T'U;"" L p-p*
s ^in " Pout ^ £n ll^l^in_ (2-5)
^P~P 'in ~ ^P~P 'out ^P~P -'out
Thus, for a specified S02 removal, the required
number of transfer units depends on p* which is a function of
the scrubber liquor composition. If enough available alkalin-
ity is provided in the scrubber slurry, p* will remain small
compared to p and sorption will proceed. As the available
alkalinity decreases, p* increases and N.T.U. grows large.
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RADIAN
CORPORATION
Equation 2-1 shows that either Kg, a, or V must be increased
to achieve such an increase in N.T.U. A calculated N.T.U. may
be used, then as an index of difficulty of achieving specified
sorption efficiency for a given set of operating conditions.
Calculation of p* and N.T.U. is one of the primary objectives
of the present analysis of scrubber performance. The variables
which enter into this calculation are the specified S02 removal,
the amount and composition of scrubber liquor, and the degree
of limestone dissolution in the scrubber. The fraction of
absorbed S02 which is oxidized also affects the equilibrium
partial pressure and N.T.U. A more complete design calculation
would adjust scrubber design parameters such as gas velocity,
height, diameter, to satisfy Equation 2-1. The exact relation-
ship of K a to these design variables is not yet known. The results
cS
ot present calculations may be compared with previous pilot
scale data, however, to insure that calculated values of N.T.U.
and K aV are realistic.
g
Estimation of mass transfer requirements (N.T.U.)
for the scrubber is one goal of an engineering anslysis based
on process chemistry. A second important aspect of scrubber
performance is the level of supersaturation in the scrubber
liquor with respect to CaS03-%H20 and CaSOu-2H20.
Slurry entering the scrubber will be slightly
supersaturated, with respect to the solid waste components
being precipitated in the hold tank. These are CaSOn-2H20 and
CaS03-%H20. Previous laboratory and pilot scale investigations
have shown that a major process problem, scaling, is related
to critical levels of supersaturation that should not be ex-
ceeded for successful process operation. Under normal opera-
ting conditions, the highest level of supersaturation in the
process will be reached in the scrubber effluent. Whether or
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not the critical scaling point is reached will depend on the
scrubber liquid-to-gas ratio, the specified 862 removal, the
composition of the inlet slurry and the degree of oxidation and
limestone dissolution in the scrubber. Calculated levels of
scrubber effluent supersaturation reached under various oper-
ating conditions can be compared with experimentally established
limits to determine the susceptibility of the scrubber to
scaling. Since scaling is primarily a chemical problem and
does not depend on assumptions regarding mechanical character-
istics of the scrubber, this aspect of the present process
analysis will be an important contribution to any preliminary
process design. The utility of the simulation model as a design
tool and as a method of predicting scaling conditions was demonstra-
ted at a 3 MW limestone scrubbing pilot plant located at Pennsylvania
Power and Light's Sunbury Station. The simulation model was used
to set process operating parameters. To verify the model's accuracy,
the system was operated at conditions in which the model predicted
scaling to occur. At those conditions the system scaled. The reli-
ability of the model was shown .by the fact that the pilot plant
operated throughout its life in an GQ.ggaled moae.
2.2 Hold Tank
The function of the process hold tank is to provide
adequate reaction time in a well mixed environment for suffi-
cient: dissolution of limestone and precipitation of calcium
sulfate and sulfite to occur. Since the hold tank is a well
mixed vessel, the composition of the output stream will be
essentially the same as the composition of the material in the
tank.
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RADIAN
CORPORATION
The performance of a hold tank may be calculated by
simultaneous solution of the chemical reaction and mass transfer
rate equations describing the phenomena taking place in the
vessel. Laboratory and pilot scale investigations have provided
quantitative descriptions of precipitation and dissolution
reactions important to a limestone scrubbing process.
The rate expression which is used for the hold tank
is given in Equation 2-4.
R = k A n V Ksp (RS - 1) (2-6)
Here, R is the precipitation rate, k is the rate constant,
A is a proportionality constant, n is the flow rate of the
solid into the tank, V is the hold tank volume, Kor. is the
»F
solubility product constant, and RS is the relative saturation.
The relative saturation is the product of the activities of
the species which react to produce the precipitating solid
divided by the solubility product constant, as shown in Equa-
tions 2-5 and 2-6 for calcium sulfate.
Ca44" + SOV + 2H20 t CaSO,-2H20 4- (2-7)
RS = [aCa++ ' aSOV ' aH20(o]/KsPCaSOl)-2H20 (2-8)
For precipitation to occur, the relative saturation is greater
than one, and the rate R is positive. For dissolution to occur
the relative saturation is less than one and the Rate R is
negative. At equilibrium, the relative, saturation is equal to
one, and the rate is zero.
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Several factors influence these solid-liquid mass
transfer rates. One factor of major importance is the hold
tank volume. If the volume is increased for a given relative
saturation and flow rate, the precipitation and dissolution
rates will increase. If the volume is increased and the rates
are to remain the same, the relative saturations must move
closer to one, indicating a closer approach to equilibrium.
Another factor which will affect the rates is the
flow rate of the solid into the tank (i.e., slurry concentra-
tion) . This flow rate controls the area on which precipitation
and dissolution may occur. Increasing the area for a given
relative saturation will increase the rate.
Variation of the proportionality constant A and the.
rate constant k is known to occur with the particle size of
precipitating or dissolving solids. The exact functionality
of this change is unknown. For purposes of investigating the
effect of such changes, the rate constant k can be changed in
process calculations.
The principle criteria for hold tank design in
limestone scrubbing processes is that the hold tank effluent
supersaturation be low enough to prevent scaling conditions
from developing as the slurry is recycled through the scrubber.
A secondary requirement is that the tank be large enough to
dissolve limestone for reasonable concentrations of limestone
in the slurry. A larger hold tank will improve limestone
utilization.
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RAPIAN
CORPORATION
The design and function of the hold tank interact
with the scrubber operating parameters. Up to a point, increas-
ing the hold tank size will decrease the required scrubber
liquor rate at least from the standpoint of supplying sufficient
alkalinity and keeping the scrubber effluent supersaturation at
a safe level.
2.3 Clarifier
The clarifier is intended primarily as a solid-liquid
separation device; however, some additional solid-liquid mass
transfer may take place here. One reaction of possible signifi-
cance that could occur in the clarifier is sulfite oxidation
due to the large surface area available for transfer of oxygen
from the atmosphere. This oxidation could affect the levels
of sulfite and sulfate supersaturation in the scrubbing system.
The clarifier removes waste solids and some liquid
from the process. A major process variable associated with
the clarifier is the amount of liquid leaving the process with
the waste solids. Soluble species such as chloride, sodium,
and magnesium are introduced to the system as trace components
in the flue gas, fly ash, and limestone. Since the liquid
carried with waste solids is the only route by which soluble
species can leave the system, the concentration of these soluble
salts in the process liquor will be inversely proportional to
the liquor content of the waste solids. These soluble species
cause significant changes in process chemistry through their
interaction with ions that actually participate in .the absorp-
tion, dissolution, and precipitation steps.
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CORPORATION
3.0 PROCESS MODEL
This section describes the computational scheme or
model used to estimate steady-state operating conditions for a
limestone scrubbing process.
The important physical phenomena and process rate
steps introduced in Section 2 are formulated mathematically.
Certain simplifying assumptions are made which lead to practi-
cal yet meaningful solutions describing the performance of the
process.
The Radian process model is a gorup of computer
programs for simulating aqueous inorganic chemical processes.
The foundation of the model is the ability to predict vapor-
liquid-solid mass transfer rates and chemical equilibrium for
the CaO-MgO-NaaO-SOa-COa-SOa-NaOs-HCl-HaO system. The process
model performs unit operation calculations and other engineer-
ing manipulations based upon (1) rate and equilibrium calcula-
tions and (2) process and equipment data which define the
process flow scheme and characterize each of the individual
process units.
The programs which make up the process model may be
grouped into five major subdivisions: (1) rate and equilibrium
calculation programs, (2) equipment subroutines which model
each process unit and process input stream, (3) an executive
syst€m which interconnects the equipment subroutines to form
an analog of the process flow diagram and controls the sequence
of computer operations, (4) convergence routines which force
convergence of the model iterative parameters, and (5) print
routines which print out stream and process data.
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CORPORATION
3.1 Process Model Flow Sheet
The main flow scheme used in this group of simulations
is given in the symbology of the Radian process model as
Figure 3-1. Subroutines FLUGS1, ALKINP, and WTRMKP simulate
process inputs of flue gas, limestone, and make-up water,
respectively. Subroutine SCRUBS models the spray tower and
RATHD1 simulates a stirred holding tank. Subroutines DIVDER
and DIVDR2 simulate stream splitters, and FILTER models a
clarifier-filter system. Subroutine SYSTB1 is an ancillary
routine which performs material balance calculations around the
entire system.
Several assumptions have been incorporated into this
simulation system.
(1) The spray tower behaves as an adiabatic
countercurrent contacting device and the
equilibrium partial pressure of SOa above
the scrubber feed is negligible.
(2) The partial pressures of COz and HaO in
the gas leaving the scrubber are in equi-
librium with the scrubber liquid at the
scrubber temperature.
(3) No precipitation occurs in the scrubber.
(4) The temperature of the recirculating
process liquor streams is fixed at the
adiabatic saturation temperature of the
scrubber effluent liquor.
C-13
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o
h-1
4>
PLUGS 1
FLUE GAS
2
ALKINP
LIMESTONE
1
WTRMKP
WATER
MAKE-UP
3
SYSTB1
OVERALL SYSTEM
BALANCE
4
SCRUBS
SPRAY TOWER
7
>
v^.
i r
RATHD1
HOLD TANK
8
- XnS
DIVDER
TEE
6
FILTER
CLARIFIER-FILTER
5
DIVDR2
TEE
9
ORDER OF PROCESS CALCULATIONS: 1. 2. 3, 4, 5, 6.(7, 8, 9 ) *
FIGURE 3-1 CONCEPTUAL DESIGN FLOW PLAN
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RADIAN
CORPORATBON
(5) The temperature of the water make-up
has no effect upon the circulating
liquor temperature.
(6) Ionic reactions taking place in the liquid
phase are rapid and thus are at equilibrium.
(7) The holding time of the clarifier (modeled
by the FILTER subroutine) is sufficiently
long that solid-liquid equilibrium is achieved.
(8) The hold tank closely approaches an idealized
backmixed vessel.
(9) Neither chemical change nor phase separation
occurs to a process stream except in a
process unit.
The two assumptions involving the temperature of the
process liquor streams should be good approximations. Previous
pilot unit work indicates that the scrubber effluent liquor
streams closely approach the adiabatic saturation temperature.
In simulation cases previously conducted, the water make-up
stream was on the order of 0.5 percent of the scrubber feed
stream and thus would have a negligible effect upon changing
the process liquor temperature. Heat loss to the surroundings
should be small in most instances. Assumptions one and three
are good approximations for a short-residence-time contactor
with a high liquid-to-gas ratio such as a spray tower. Assump-
tion seven listed above is probably not a good assumption in
that it does not reflect the true situation in a clarifier.
This modeling assumption may be justified from the standpoint
that solid-liquid equilibrium represents the maximum chemical
change that can occur across the clarifier. Thus, the actual
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CORPORATION
composition of the clarifier effluent streams will lie
between the composition of the clarifier feed and the effluent
composition as determined by solid-liquid equilibrium. In
general, this chemical change will be small.
3.2 Equipment Subroutines
This section gives a brief description of the major
routines used in the process simulations. The routines may be
grouped into four sections: (1) input routines (FLUGS1, ALKINP,
and WTRMKP), (2) unit operation routines (SCRUB5, RATHD1),
(3) material balance routines (SYSTB1), and (4) minor process
unit routines (DIVDER, DIVDR2, and FILTER).
FLUGS1 - This routine simulates a flue gas input
stream with entrained fly ash. It reads data cards for the
temperature, pressure, and flow rate of the gas stream and the
weight rate of the fly ash, all in English units , as well as
the mole fraction composition of the gas and the weight frac-
tion composition of the solid. The calculations performed are
to convert these data to program units and assign it to the
specified output stream.
ALKINP - This routine simulates an alkali input
stream, which was limestone for all cases run. It reads data
cards for the weight rate and weight fraction composition of
the limestone. The calculations performed are to convert these
data t:o program units and assign it to the specified output
strean.
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RADIAN
CORPORATION
WTRMKP - This routine simulates a water input stream.
It reads data cards for the weight composition of the water
stream and converts these data to molality in the specified
output stream. This routine does not assign the flow rate of
the output stream.
SCRUB5 - This routine simulates a vapor-liquid
contactor. It is assumed that (1) the scrutber is adiabatic,
(2) C02 and H20 are in vapor-liquid equilibrium, and (3) no
precipitation occurs. The flue gas flow rate, composition,
and amount of S02 removal required is input to this routine
as is the composition and flow rate of the scrubber slurry
feed stream. Since quantitative prediction of the amount of
limestone that will dissolve in a spray tower is not yet feasi-
ble, a fraction of incoming limestone (and fly ash, if desired)
is assumed to dissolve. The type of contactor (co-current,
countercurrent, and back-mixed liquor) may also be specified.
The mass transfer coefficients reported here are for counter-
current spray tower operation.
The routine calculates the number of transfer units
(and thus KgaV) required to achieve the specified S02 removal
using the specified feed rate and composition. The composition
of the outlet slurry is also calculated. As noted in Section
2.0, the supersaturation of this stream is of major interest.
RATHDl - This routine simulates a well-mixed holding
tank. All input streams must be completely known along with
the tank volume and the rate constants for the solid-liquid
mass transfer of limestone, CaS04-2H20, and CaS03-%H20. The
output stream is calculated by simulataneous solution of rate,
material balance, and equilibrium relationships.
C-17
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CORPORATION
Hold tank performance can be modified by adjusting
the tank volume, the slurry solids concentration, or by chang-
ing the precipitation and dissolution rate constants.
SYSTB1 - This routine performs a mass and energy
balance about the process based on complete knowledge of the
flue gas and limestone streams, the composition of the make-up
water stream, and the following system parameters: (1) the
fraction of the SOa in the flue gas which is absorbed, (2) the
fraction of the absorbed SOz which is oxidized to SOs, (3) the
pressure drop across the scrubber, (4) the particulate removal
efficiency of the scrubber, and (5) the desired filter bottoms
pH. Additional information is taken from other routines as
need be.
Based on total removal of SOa and HG1, the specified
fractional removal of SOz, and a guess at the loss of COz,
the non-aqueous portion of the scrubber exit gas is calculated.
An adiabatic heat and material balance is then performed to
find the water in the scrubber exit gas, assuming that the
liquid circulating through the scrubber and the exit gas are
at the adiabatic saturation temperature.
Based on (1) the weight fraction solids in the filter
bottoms; (2) complete information for the flue gas, scrubber
exit gas, and limestone•streams; and (3) the composition of the
make-up water streams, the filter bottoms flow rate and compo-
sition, and the make-up water flow rate can be calculated.
DIVDER - This routine simulates a stream splitter.
Based on the flow rate for the first output stream and com-
plete information about the second output stream, complete
information for the input stream and the first output stream
are calculated.
C-18
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CORPORATION
DIVDR2 - This routine also simulates a stream splitter,
The difference from DIVDER is that in DIVDR2 the feed stream is
completely known and the flow rate of the first output stream
is known. Based on these data, complete information for both
output streams is calculated.
FILTER - This routine models a solid-liquid separator.
Input data are the weight fraction solids in the feed and
bottoms streams and the separation efficiency, i.e., the frac-
tion of the feed solids which are transferred to the bottoms.
3.3 Calculation Sequence
In the execution of a simulation computer run, the
executive system makes three passes through each of the equip-
ment subroutines which is used in the simulation. In the first
pass the data cards are read, the input data are printed, and
any necessary initialization (such as assigning the weight
fraction solids in the filter bottoms in the FILTER routine)
is performed. In the second pass the simulation calculations
are performed as follows.
(1) The input routines FLUGS1, ALKINP, and
WTRMKP are called. These routines perform
all of their operations on the first pass
and do not play an active part on the second
pass.
(2) Subroutine SYSTB1 calculates the scrubber
exit gas and the filter bottoms stream.
(3) Subroutine FILTER calculates the filter
feed and filter overhead.
C-19
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CORPOSLATBON
(4) Subroutine DIVDER calculates a first
guess at the scrubber slurry feed stream
and the hold tank effluent as having
equilibrium compositions.
(5) Subroutine SCRUBS calculates the scrubber
bottoms stream.
(6) Subroutine RATHD1 calculates the tank
effluent based on rate calculations.
(7) Subroutine DIVDR2 recalculates the scrubber
feed and filter feed streams based on the
hold tank effluent.
(8) Steps 5, 6, and 7 (subroutines SCRUBS,
RATHD1, and DIVDR2) are iterated until the
compositions and flow rates of the streams
involved approach their steady-state values.
This completes the second pass. At this point, the
executive system prints complete stream data for all process
streams. After the stream print, a final pass is made through
the equipment subroutines, and any ancillary output which was
not printed in the. stream print, such as KeaV and N.T.U. in
O
the scrubber is printed.
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R&D1AN
CORPORATION
4.0 PROCESS SIMULATION CASE
The following pages represent a typical process
simulation of a limestone wet scrubbing system. The computer
output 'for the conceptual design of the limestone scrubbing
system on the sinter plant with 39 percent windbox gas recycle
was chosen. The stream values shown were those used to prepare
the material balance which was presented in Section 5.1 of this
report. The flow plan used for the simulation case was pre-
viously given in Figure 3-1 of this Appendix.
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RADIAN
CORPORATION
22
! 1 121:57.151
INPUT SPECIES (-JI.ES)
TEHPEHATUSi
57,473 OES, C,
PH i
H20 e
CAO »
VA20 •
COMPONENT
M2Q
H2C03
HC03-
HN03
M2503
HSfU-
XS04-
CA«t
CAOH*
CA"Ct'3»
CAC03
CA-JG3*
CASU3
CAS04
MOOh*
.1GHC03*
"or.03
1GS04
Minn
MAC03-
NAN03
•US04-
OH-.
CL-
C03--
>J03-
S03»
COMPONENT
CA(OH)3(S)
CACU3CS)
CAS03(S)
MCC03CS)
PSfiZ i 3.^47,11-
Prl"0i « 1.76722
1 I b 7 1 .•> ,1 » J 3
i , 5 2 s m « .1 a
AOUEO'JS SOLUTION EO
."OUAUITY
5,412-07
1 ,338-WJ
1,849-^3
1 .323-12
2!<:5S-fl4
1,154-^2
3,323-fS
2,173-iU
2.711-^5
j!l49-34
7.',1S5-H3
6, 153-1*4
3.S83-.1"
21413-fl?
7.178-11
2,193-OS
4.335-.18
s:;;j:s;
2.216-37
3.S97-il5
J.B93-U2
1CLALITY ACT
21224-2!
i. 152-01
8 ',1',!! i
*,M*
ft ATI,
-17 4T»,,
10LECUIA3 'H»T£R i 1
6.3397 IONIC STSEv&Ti > 4.97
HCL 4.29699*d!)
C02 2,it23J««2
w;n3 a.^.i^^tt
N205 3,a7535-.a2
SQ2 3,81311*32
533 9,1359S*ii2
UIlIoSIA
ACTIVITY ACTIVITY COEFFICIENT
4.574-B7 B.451-B1
9,994-.'!
1 , 3 i ^ • 8 3 1 , ^ ii 9 • il 3
t!?'J3-24 8,11)9.^1
5,103-?.3 4,4J4-,11
2.SJ5.03 B,HS-?.l
2,735-26 1 ,tV9*Q?, '
3,i/s-«4 i,?ee»?^
7, 1 16-«3 1 , ?rffl»ijiJ
2.355-.14 4,536-'^l
2,^i4-37 1,7'JO'fH
5 , b3 t -Pi 1 ,?09 !,l&?-il4
,71?t.l»il3 t « » 1 1 , 7 9 M t ;i H
C-22
-------
J
2
3
4
S
6
7
0
9
AL«INP
FL'JGSl
MTRMXP
STST31
FILTER
OIVOER
SCRUBS
RATH01
OIVOR2
2
7
9
2
1
»
CORPORATION
SINTER PLANT ( 3ux RZCYCLE J LIMESTONE SCRUBBING SYSTEH
PROCESS DESCRIPTION
EOUI", NO, EQUIP, NAME INP'JT STREAMS OUTPUT STREAMS
1
2
3
1 4 S
10 9
6 7
4 8
IB 3 9
6 7
QROER OF PROCESS CALCULATIONS
1,2,3,4,3,6(7,5,9).
RtCiCLE. LOOP FROM 7 TO 9 '
SYSTEM AMO EJUIP«ENT PARAMETERS
SYSTJl, C.OU1PMENT NUMfitR 4
Su? 4-)SURdED i Sf>,43 X NO ABSORBED • ,30 X
S'T2 OXIOtZEO • ' P. 03 X NQ2 ABSORBED • ,00 X
Ll^E 50L1CS MYOR/HNG IN SYSTEM* CAO « 130.39 X M50 • 106,00 X
PKCSSuRE DROP CONSTANTS* GAM-itl * a,038 GAH14 2 > 9,003 GAM«» 3 • a.;
PARTICIPATE REMOVAL CONSTANTS* BETA l • l,204*0<) BETA 2 » a,a»0 BETA 3 »
I"ITI»L VALUE OF XA(C3?) « 9,*W9
SOLIO itSTE PH LIMITED TO 6,80 i 0,S
FILTE*, ETUIPWENT NUMBER 5
FEEO i«T FR SOLIDS « 12,32 X UNDERFLOW »T FR SOL13S » 48,33 X
SEPARATION EFFICIENCY « IJ0.00 X
S rLO" " i
SCSUJS, iS
•)»C*MIx£r) O^ESATnx PRECIPITATION NOT ALLO«EO
Ll*E SOLIDS HYOHAU'iG IN SCRUBBF.H* CAO > iad,i»M X .MGO « 188,38 X
FRACTIONS OF SOLIOS AvUL'S'.E fJR REACTION*
CACUHJ2 *G(OH)2 CAC03 flGC.Ii MGS04 NA20 I.ACL LIMESTONE
SLURRY* .33 X ,?) X
FLUE GAS* loa.aa x u^.??« x ,90 x ,?)8tf WT x HGS03 0,0000 »r x
T,n K,P^M«I WT x CAS04 K,0e0M -aiua n,?<<)«ai MRLE x NACL 6,8i«a MT x
so3 3,ai>cM MOLE x INERT 7a,3na WT x
Ni 8,37j*i»
-------
22
STREAM
T n T 4 I 0
2
,16500+06
5/80.2
330,38
1 ,0003
r -.11635+09
, 12004^02
12,644
,16499+06
5780,2
, 15666+06
,12956+06
-,11634+09
1,0532
4,0230
641 ,60
,00000
,010080
635.82
,00000
3510,3
,0)0000
96H,41
,00000
,69600-01
11,100
,00000
,00000
1 1 ,000
,00000
60,730
,00000
17,100
,00000
3 4
1114,6 ,16489+06
61,857 b779,5
204.27 330,24
,00000 1,0003
*•, 42386+07 ^,11647+09
,00000 ,36015*03
,W?l000 3,7930
,035500 ,16489 + 06
,00000 5779,5
,030110 ,15657 + 06
, 000HM ,12954+06
S0?.0t30 !•>, 11647 + 09
,030190 1,0532
,0f)0W0 ,38621
,00P)W0 645,23
,00000 ,00000
,0MB M0 ,00000
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22 JUN 7b 11:25:00.283
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22 JIJN 7t> ii:25:wi
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278.33
330.24
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FLO*
n
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COMP
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22 ,JUN 7t> 11:25102.
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SO 2
CO 2
5)03
SINTER PLANT ( 39X RECYCLE 3 LIMESTONE SCRUBBING SYSTEM
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LIQUID PHASE
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KEY COHP I
502
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(G-MOLES/SEC)
(CAL/SEC)
(G/ML AT T)
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CONIC (G-MOLKS/KG
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5614,1
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1.0987
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-------
22 JUN 76 11 t25}02,25iO
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(G-MOUE3/KG
SINTER PLANT ( 39X RECYCLE ) LIMESTONE SCRUBBING SYSTEM
8910
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N A S 0 4 -
CL-
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4,9270
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,13135-07
,13379-02
,11644-01
,33246-07
,31487-03
,27108-05
,21776-03
,70547-02
,90536-0b
,61581-03
,35879-07
,66232-05
,57258-05
.26425-03
,24131-06
,18251-02
,71775-10
,43355-07
,21933-05
,.50796-04
,1601 1-07
,25H9v)-02
,49771-01
2932,2
1707.7
1728,9
,16604-05
,72498-07
,81661-03
,42577-04
,11485-01
,75341-03
,72386-07
,34979-04
,20372-05
,13332-06
,16656-02
,12039-01
,11143-07
,34879-03
,36832-06
,90888-04
,75211-02
,92566-06
,61251-03
,11581-07
,70655-05
.23014-05
,27130-03
,31575-07
,18256-02
,23376-10
,57547-08
,H8954-06
,52905-04
,15907-07
,25100-02
,51404-01
3058,8
1712,6
1734,1
, 54123-06
,22158-06
,24580-03
,38968-04
,10901-01
,18489-02
,54013-06
,34997-04
,63723-06
,13135-07
,13379-02
,11844-01
,33246-07
,31487-03
,27108-05
,21776-03
,70547-02
,90536-06
,61581-03
,35879-07
,66232-05
,57258-05
,26425-03
,24131*06
,lb2bl-02
,71775-10
,43355-07
,219.53-MS
,50796-04
,16011-07
,25090-02
,49771-01
2932,2
3,8977
3.9473
,48348-06
,24654-06
.16783-03
,29356-04
,10245-01
,19976-02
,64386-06
,35039-04
,54464-06
,80658-08
,13000-02
,110143-01
,35488-07
,23144-03
,31530-05
,22576-03
,64898-02
,87159-06
,62131-03
,40824-07
,51892-05
,63275*05
,25912-03
.29918-06
,18265-02
,80559-1 0
,52560-07
,23909-05
,48706-04
,16207-07
.25083-02
.47208-01
2737,3
-------
22 JUN 7b 11125102,475
STREAM NUMBER
SOLID PHASE
FLOW RATE (G/SED
(G^MOLE/SEC)
ENTHALPY (CAL/SEC)
SPECIFIC GWAVITY
KEY COUP KATE(GMOLES/SEC)
so a
COi?
SO 3
M2U5
CAO
MGU
MA20
HCU
H20
_ COUP RATE (G MOLES/SEC)
i CAO
£ CACOH12
CACfM
CASOJ
CASOJ*1/2H20
CAS04
CAS04*2H20
MGU
NG COtO 2
MGCQA
•1GUfM*3H20
MGC()3*bH20
MGSCM
MCii>03*.JH20
fl(;SOii*6H2n
MGS04
MGCL2
MA 20
NACL
IMERT5
LINES TUNE
XLS
7
072,60
4.6207
,18412+07
2,4228
1,4)957
.79225
2,5383
,00000
4,4263
,000^0
,00000
,00000
5,6245
,00000
,00000
,79225
,03000
1,0957
,29114-05
2,5383
,00000
,00000
,0(4000
, 300U0
,045000
,fl00U0
,v}W0fc)0
a 0 tl ' W W
• "i ^1 V) fe) B
,<5y000
,021000
,Mr10^H
,19443
,00000
.MM 00
SINTER PL
8
,23305+06
1600,3
-,63794+09
2,4225
379,83
272.50
080,52
,00000
1532,9
,00000
,00000
,00000
1951,0
,00000
,00000
272,50
,00000
379.83
,10120*02
880,52
,000a0 '
,0ti0fc)0
,00000
,000^0
,00000
,00040
,00000
,0.0000
,00000
.00000
,00000
,0001*0
67,403
,000190
,000140
ANT ( 39X RECYCLE )
9
,23379+06
1606.1
v, 647)00 + 09
2,4228
380,87
275,38
882,31
,00000
1538,6
,00000
, 03000
,00000
1955,1
,00000
,02000
275,38
, 030ldft
38(3,87
,iui2a*a2
882,31
,0001-10
,00000
,0210(40
,001500
,00000
,00000
,00003
,000k}ft
.000U0
,00000
,00000
,00000
67,5d4
, W0W00
,003^0
10
,00000
,00000
,00000
,00000
,00000
,00000
,00000
,00000
,00000
, PI0000
,00000
, 00000
,00000
,00000
,00000
,00000
,00000
,00000
,00000
,00000
,00000
,00000
,00000
,00900
,00000
,110000
,00000
,0000(9
,00000
,00000
,00000
,00000
,00000
,00000
,00000
LIMESTONE SCRUBBING SYSTEM
HI
o1
z
-------
22 JUN 76 11I25J02.665
STREAM NUMHb^
ELEMENT su;-ATOMS/SEC
TOTAL STKEAM
H
C
M
0
MG
S
CL
CA
GAS PHASE
H
C
SINTER PLANT ( 39X RECYCLE ) LIMESTONE SCRUBBING SYSTEM
8 9 10
n
o
3D
o
w
0
S
CL
LIQUID PHASE
H
C
N
0
NA
MG
S
CL
CA
SOLID PHASE
H
C
N
0
MA
MG
S
CL
CA
558.23
,80908
,17697-03
295,34
,92536-02
,43983-02
3,7271
,12362-01
4.5211
,00000
,05*000
,00000
.021000
,00000
,00000
546,98
,16831-01
.17697-03
273,90
,92536-02
.43983-02
.93008-01
,12362-01
.94773-01
11.249
.79225
,00000
21,442
,80000
.40000
3.6341
.H3PI30
4,4263
.19348+06
276,80
,61341-01
,10237+06
3,2093
1,5253
1295,4
4,2863
1567,0
,00000
,00000
.000019
,00000
,00000
,90000
,18958+06
4,2923
,61 341-01
94937,
3.2093
1.5253
35,088
4,2863
34,156
3901,9
272,50
,00000
7430,0
,00000
,00000
1260,4
,00030
1532,9
,19404+06
281,23
,61514-01
,10266+06
3,2165
1.5288
1295,5
4.2970
1571,5
,00000
,00000
,00000
,00000
,00000
,00000
,19313+06
5,8504
,61514^01
95206.
3,2165
1,5288
32,329
4,2970
32,943
3910,1
275,38
,00000
7453,0
,00000
.00000
1263.2
,00000
1538,6
432,71
,13783*01
,14003*03
216.66
,73184-02
,34778-02
,68120-01
,97767-02
, 69980-01
,00000
.00000
,00000
,00000
,00000
,00000
432,71
,13783-01
,14003*03
216,66
,74184-02
,34778«02
,68120*01
,97767*02
,69980*01
,00000
,00000
,00000
,00000
,00000
,00000
,00000
,00000
,00000
-------
22 JUN 76 11:24:59,710 SINTER PLANT ( 39% RECYCLE ) LIMESTONE SCRUBBING SYSTEM 0
39
5CRIBI5, rJRUIPMENT NUMBER 7 §
L/G = 8,15413^01 KAL/100a ACF |
PhESSUHE DROP » ,fe)0 PSI §
P*RTICULATE REMOVAL s 70.02 X |
KGAV(S02) s l(M7ti62 + 05 LBMOLE/HR ATM 1
MTUCS02) * 2,347
5TOICHIOMETRY s 1M9*9 HOLE X LIMESTONE PER S02
o
i
OJ
-------
RADIAN
CORPORATION
APPENDIX D
COST DATA
D-l
-------
CORPORATION
1.0
EQUIPMENT LIST
The items listed in Tables D-l and D-2 are the equip-
ment required to process the flue gas from the two sinter plant
cases considered in this study. The equipment arrangement was
shown, in Figure 5-1. The limestone process was divided into
ten areas to allow comparisons of the two cases to be made
easily.
The size cost scale factors listed in Tables D-l
and D-2 were used to obtain order-of-magnitude cost estimates
for the process equipment. Capital investment costs for com-
plete plants can be correlated to within + 30% with these fac-
tors using some plant parameter as a basis for equipment sizing,
The correlation used in this study was of the form:
Capital
Cost
'Capital cost ~
for reference
size
x
size parameter
reference size
parameter
x I
where: I = inflation index factor
n = size-cost scale factor
This technique allows a reasonably accurate estimate of plant
cost to be made from data on different size plants without
obtaining price quotations from equipment vendors.
The inflation indices used for cost estimates of this sort
introduce some error into the estimate, but this is unavoid-
able. Several publications, most notably Marshall and Stevens,
Chemical Engineering Magazine, and Nelson Refinery Construction
D-2
-------
RADIAN
CORPORATION
and Equipment Inflation Indices, list inflation indices based
on a year in the late 1950's (e.g., 1957 = 100.). Using these
indices, costs of equipment can be scaled up to the present
with reasonable accuracy. However, projecting costs into the
future (1977 in this case) introduces a possible error. Nor-
mally, some inflation rate in the 7-9 percent per year range
is used to estimate future equipment prices. The inflation
rate assumed can be based on past performance as indicated by
the published inflation indices but projecting past inflation
rates into the future can introduce error.
The Chemical Engineering plant cost index was used for
this study. The 1974 costs were scaled up to 1975 costs using
indices from this index. To project costs from 1975 to 1977
a yearly inflation rate of 7 percent was used based upon inflation
rates of previous years. The high inflation rates experienced since
1973 were considered abnormally high so they were not used.
D-3
-------
TABLE D-l
CASE 1: STANDARD OPERATION
WORK SHEET FOR PROCESS EQ'JIP>ENT COSTS
AREA 1 - MATERIALS HANDLING
1.
2 _
3.
4.
5 .
6.
7.
S.
9.
10.
11.
12.
13.
11.
I cam
Unloading
hopper i!o. 1
Line scone
feeder iio. 1
(vibrat:,ng)
Convevoi..'
(belt) !!o. 1
Convevoi.'
(belt) iio. 2
Hoppers
under p:.Le
Limestone
feeder iio. 2
(vibrating)
Conveyo::
(belt) !!o. 3
Tunnel
surap puitp
Elevator.'
No . 1
Bin
Car shaker
Dust
collecting
system :.'o. 1
Dust
collecting
system iio. 2
Bag filrer
system
Xo. DescriDtion
1 Capacity ,31m , carbon
steel
1 5.8 kg/s
1 5.3 kg/s
1 5.3 kg/s
3 Capacity 0.21m3, car-
bon steel
3 2.8 kg/s
1 2.3 kg/s
2 3.2 x 10~4m3/s, carbon
steel, neoprene lining,
186.5 watt motor
1 2.8 kg/s
1 Capacity 15.6m3, car-
bon steel
1 Railroad trackside
vibrator
1 0.12 n3/s inertial
separator, cyclone,
hoppers, fan", and
drive
1 0.33 ra3/s inertial
separator, cyclone,
hoppers, fan, and
drive
1 0.87 n /s, automatic
fabric dust collectors.
Size-Cost
Scale
Factor
0.68
0.58
0.81
0.65
0.81
0.65
0.68
0.58
0.65
0.81
Factor
Source
Chen. Engr. 3-24-69
Guchrie
Chem. Engr. 3-24-69
Guthrie
Fund, of Cost Enzr.
1964
Chem. Engr. 3-24-69
Guthrie
Fund, of Cost Engr.
1964
Chem. Engr. 3-24-69
Guthrie
Chem. Engr. 3-24-69
Guthrie
Chem. Engr. 3-24-69
Guthrie
Chem. Engr. 3-24-69
Guthrie
Fund, of Cost Engr.
1964
Depends on gpra and head re- .
quirements resulting in
changes of motor and impeller
size
0.83
0.68
0.80
0.80
0.68
Chem. Ensr. 3-24-69
Chem. Engr. 3-2^-69
Chesn. Engr. 3-24-69
Guthrie
Chem. Engr. 3-24-69
Chem. Engr. 3-24-69
Base
Cost
Each
(1977)
560
1,100
580
2,750
470
570
4,240
720
2,560
4,280
7,950
590
1,100
2,580
Total
Mid-1977
Cost
560
1,100
580
2,750
1,410
1,710
4,240
1,440
2,560
4,280
7,950
590
1,100
2,580
bag support, shaker sys-
tem, isolation damper,
motor, drive, dust hopper,
fan and motor
SUBTOTAL
D-4
-------
TABLE D-I (Continued)
AREA 2 - FE
ED PREPARATION
Size-Cost
Scale
i
2 .
3.
4.
5 .
6.
7 .
3.
9.
10.
11.
I cera
Bin discharge
feeder
Weigh feeder
Gyratory
crusher
Elevator
No. 2
Wet ball
r.ill
Slurry feed
tank
Lining
Agitator,
slurry
feed
tank
Pumps, slurry
feed rank
Dust
collecting
system
Hoist
Bag filter
system
N'o.
1
1
1
1
1
1
1
1
!
7
1
1
1
Description
0.8 kg/s, 'carbon
steel
0.8 kg/s, carbon
steel
0.8 kg/s
0.8 kg/s
7.4 kg/s
78330 W motor
Capacity 20. 8m ,
carbon steel
6.35 x 10" m neoprene
1492 W, neoprene coated
6.9 x 10~4m3/s,
carbon steel, neoprene
lined
0.42 m3/s, inertial
separator, cyclone,
hoppers, fan and drive
1800 kg electric
0.87 m /s, automatic
fabric dust collectors,
Factor
0.58
0.65
1.20
0.65
0.65
1.07
0.68
0.50
0.46
Depends
Factor
Base
Cost
Each
Source (
Chem. Engr.
Guthrie
Chem. Engr.
Guthrie
Chem. Engr.
Guthrie
Chem. Engr.
Guthrie
Chen. Engr.
Guthrie
3-24-69
3-24-69
3-24-69
3-24-69
3-24-69
Fund, of Cost Ener.
1964
Chem. Engr.
Guthrie
Chem. Engr.
Guthrie
3-24-69
3-24-69
3
2
1
50
3
5
4
3
1977)
320
,900
,450
,140
,550
,600
,450
,820
,020
Total
Mid- 1977
Cost
3
2
1
50
3
5
4
3
320
,900
,450
,140
,550
,600
,450
,820
,020
Fund, of Cost Engr.
1964
on gpra and h
quirements resulting
changes
size
0.80
0.81
0.68
of motor and
Chem. Ener.
Guthrie
Popper, H.
Chem. Engr.
ead re-
in
impeller
3-24-69
3-24-69
1
1
10
2
,990
,340
,890
,580
3
1
10
2
,980
,340
,890
,580
bag support, shaker sys-
tem, isolation damper,
motor, drive, dust hopper,
fan and motor
SUBTOTAL
D-5
-------
TABLE D-I (Continued)
AREA 3 - PARTICULATE SCRUBBING
1.
2.
3.
4
5.
6 .
7.
Item
Tank ,
particulate
scrubber,
effluent
hold
Lining
Agitator,
effluent
hold ca'.ilc
Pumps ,
recyc le
slurry
Venturi
scrubber
Venturi
sump
Soot
blowers
Bleed
pump
Size-Cost
Scale Factor
Mo. Description Factor Source
2 Capacity 174. 1 a ,
carbon steel
2 6.35 x 10 m neoprene
2 7460 W, neoprene
coated
3 .4 m /s, carbon
steel, neoprene lined
2 93.7 m /s, carbon steel,
neoprene lined
2 Carbon steel, neoprene
lining
10
3 1.9 x 10"3 tn3/s, carbon
steel, neoprene lined
0.68 Chem. Engr. 3-24-69
Guthrie
0.26 Fund, of Cost Engr.
1964
0.50 Chem. Engr. 3-24-69
Guthrie
Depends on gpm and head re-
quirements resulting in
changes of motor and impeller
size
0.60 Universal Oil
Products
0.63 Cheta. Engr. 3-24-69
Guthrie
1.00 TVA
Depends on gpm and head re-
quirements resulting in
changes of motor and impeller
size
Base
Cost
Each
(1977)
29,150
21,460
5,770
20,950
160,250
51,430
4,820
2,000
Total
Mid-1977
Cost
58,300
42,920
11,450
62,350
320,500
122,860
48,200
6,000
SUBTOTAL
D-6
-------
TABLE D-l (Continued)
AREA 4 -
S02 SCRU33I.NG
Size-Cose
Scale Factor
I eera
1. Spray cower
scrubber
2 . Spray tower
sump
3. Tank
absorber
ef f luenc
hold
Lining
4. Asitator,
S02
absorber
hold tank
5. P-or.ps, S02
absorber
recycle
slurry
6 . Pur.p s ,
makeup
water
7. Sooc
blowers
S. Derrdster
9 , PUI7.D ,
bleed
10. Tank
Denis Cer
Wash
11. Pump,
Demister
Wash
SraiOTAL
No. DescriDtion Factor Source
2 Gas flow 93.7 m3/s,
carbon steel, neoprene
2 Carbon steel, neoprene
lined
2 Capacity 530.9 m3, car-
bon steel, field erected
2 6.35 x 10 m neoprene
2 22380 W, neoprene
coated
5 .62 m /s, carbon steel,
neoprene lined
2 1.1 x 10"3 m3/s, carbon
steel, neoprene lined
10
2 Carbon steel, neoprene
lined
4 6.7 x 10"" m /s, carbon
steel, neoprene lined
2 Capacity 1.89m , carbon
steel, neoprene lined
4 1.3 x 10 m /s, carbon
steel, neoprene lined
Western Precipitation
Div. Joy Mfr. Co.a
0.68 Chem. Engr. 3-24-69
Guthrie
0.68 Chem. Engr. 3-24-69
Guthrie
...
0.50 Chem. Engr. 3-24-69
Guthrie
Depends on gpn and head re-
quirements resulting in
changes of motor and impeller
size
Depends on gpm and head re-
quirements resulting in
changes of motor and imoeller
size
1.00 TVA
Depends on gpm and head re-
quirements resulting in
changes of ir.otor and impeller
size
0.68 Chem. Engr. 3-24-69
Guthrie
Depends on gpm and head re-
quirements resulting in
chanaes of motor and impeller
size"
Base
Cost Total
Each Mid-1977
(1977) Cost
232,000 464,000
60,460 120,920
37,680 75,360
32,250 64,500
12,360 24,720
32,620 163,100
1,500 3,000
4,820 48,200
23,200 46,200
2,000 3,000
1,400 2,800
1,500 6,000
1,026,300
Indicateds source of spray tower cost
D-7
-------
TABLE D-l (Continued)
1.
2.
Item
Steam
reheaneT
Sooc
blowers
No.
2
10
AREA 5 - REHEAT
Size-Cost
Scale
Description Factor
4.0 x 106 K racing 0.30
146.3 m2 surface area
1.00
Factor
Source
Chem. Engr. 3-24-69
Guthrie
TVA
SUBTOTA1
Base
Cost Total
Each Mid-1977
(1977) Cost
81,130 162,270
4,820 48,200
210,470
AREA 6 - GAS HANDLING
1. Fan
1.53 x 10 W motor drive 0.68
Chem. Engr. 3-24-69 71,650 143,300
Guthrie
AREA 7 - SOLIDS DISPOSAL
1.
2.
Item
Clarifer:
Pumos,
feed
pond
No.
1
2
5.5
1.3
bon
Description
x 10~3 m3/s
x 10"3 m3/s, car-
steel, neoprene
Size-Cost
Scale
Factor
...
Depends
Base
Cost
PEDCO
on gpm
Factor
Source
(PE-146)
and head re-
quirements resulting in
Each
tl 9
161,
1,
77)
000
500
Total
Mid-1977
Cost
161,000
3,000
lined
3. Pump, cT.arifer 2
water rocvcle
4. Pumps, yiarticu- 2
late pond water
recycle
5. Pumps, S02
pond wacer
recycle
SUBTOTAL
,-3
4.1 x 10 J m3/s, car-
bon steel, neoprer.e
lined
3.2 x 10"3 3i3/s, carbon
steel, -eoprene lined
5.8 x 10" m /s, carbon
steel, neoprene lined
changes of motor and impeller
size
Depends on gprn and head re- 3,500
quirenents resulting in
changes of motor and impeller
Depends on gpm and head re- 2,500
quirements resulting in
changes of motor and impeller
size
Depends on gpm and head re- 1,100
quirements resulting in
changes of motor and impeller
size
7,000
5,000
2,200
178,200
D-8
-------
TABLE D-l (Continued)
AREA 8 - UTILITIES
Note: There is no process equipment in :his area.
AREA 9 - SERVICES
leer.
1. Payloader
2. Plane
vehicles
3. Maine. &
instrument
shop-
equipraenc
i. Service
building-
equipmenc
5. Stores-
equipmenc
SUBTOTAL
N'O.
Descripcion
Size-Cose
Scale
Faccor
Faccor
Source
Base
Cose Tocal
Each Mid-1977
(1977)
Cose
29,350 29,850
12,050
31,780 31,780
42,130 i2,130
12,760 12,760
128,5/0
AREA 10 - PARTICLE RECIRCULATIOS
Item
1. Wee ball
mill
No.
1
Descrioeion
3.2 x 10"4 m3/s
Size-Cose
Scale
Faccor
.65
Factor
Source
McGlanery
2. Pump,
particle
recirculacion
3. Tank,
particle
recirculaeion
surge
3.2 x 10*6 m3/s,
molded polypropylene
Capacity l.lm , carbon
steel, neoprene lined
Depends on gpm and head re-
quirements resulting in
changes of mocor and irr.peller
sizes
.68
Me Glemery
Base
Cose Tocal
Each Mid-1977
(1977) Cose
29,950 29,950
500
1,000
1,000
1,000
SUBTOTAL
31,950
D-9
-------
TABLE D-2
CASE 2: 397, SINTER GAS RECYCLE
WORK SHEET FOR PROCESS EQUIPMENT COSTS
1.
i
3.
4 .
5 .
6.
7.
3.
9.
10.
11.
12.
13.
14.
Item
Unloading
hopper Mo. 1
Limescoae
feeder Mo . 1
(vi.braci.ng)
Conveyor
(belt) No. 1
Conveyor
(belt) N'o. 2
Hoppers
under pile
Limestone
feeder Mo. 2
(vibrating)
Convevor
(belt) N'o. 3
Tunnel
sump pusp
Elevator
No. 1
3in
Car shaker
Dust
collecting
system No. 1
Dusc
collecting
system N'o. 2
Bag filter
system
AREA 1 -
No. Descriotion
1 Capacity .34 m3,
carbon sceel
1 6.3 kg/s
1 6.3 kg/s
1 6.3 kg/s
3 Capacity 0.23 m3,
carbon steel
3 3.0 kg/s
1 3.0 kg/s
2 3.2 x 10'4 m3/s,
carbon steel, neoprene
lining, 186.5 watt
motor
1 3.0 kg/s
1 Capacity 17 m", carbon
steel
1 Railroad crackside
vibrator
1 0.12 m3/s, inertial
separators, cyclone,
hoppers, fan, and drive
1 0,35 m3/s, inertial
separators, cyclone,
hoppers, fan, 'and drive
1 0.94 m /s, automatic
fabric dust collectors.
MATERIALS
Size-Cost
Scale
Factor
0.68
0.58
O.S1
0.65
0.81
0.65
0.68
0.58
0.65
0.81
HANDLING
Factor
Source
Cham. Engr. 3-24-69
Guthrie
Chem. Engr. 3-24-69
Guthrie
Fund, of Cose Engr.
1964
Chem. Engr. 3-24-69
Guchrie
Fund, of Cost Engr.
1964
Chem. Engr. 3-24-69
Guthrie
Chem. Engr. 3-24-69
Guthrie
Chen. Engr. 3-24-69
Chem. Engr. 3-24-69
Guthrie
Fund, of Cost Engr,
1964
Depends on gpm and head re-
quirements resulting in
changes of motor and impeller
sizes
0.33
0.68
..i.
0.80
0.80
0.63
Chem. Engr. 3-24-69
Chem. Engr. 3-24-69
Chem. Engr. 3-24-69
Guthrie
Chem. Engr. 3-24-69
Chem. Engr. 3-24-69
Base
Cost
Each
(1977)
600
1,160
620
2,940
490
600
4,490
720
2,760
5,470
6,600
590
1,160
2,730
Total
Mid-1977
Cose
600
1,160
620
2,940
1,470
1,300
13,470
1,440
2,760
5,470
6,600
590
1,160
2,730
bag support, shaker sys-
tem, isolation damper',
motor, drive, dust hoppe:
fan and motor
SUBTOTAL
36,210
D-10
-------
TABLE D-2 (Continued)
AREA 2 - FEED PREPARATION
Size-Cost
Scale
Item
1. Bin discharge
feeder
2. Weigh feeder
3. Gyratory
crusher
4. Elevator
.No. 2
5. Wet bail
nill
6. Slurry feed
tank
Lining
7. Agitator,
slurrv
feed
tank
8. Pumps, slurry
feed tank
9. Dust
collecting
system
10. Hoist
11. Bag filter
system
NO.
1
1
1
1
1
1
1
1
1
2
1
1
1
Descriotion
0.8 kg/s, carbon steel
0.8 kg/s, carbon steel
0.8 kg/s
0.8 kg/s
7.9 kg/s
85790 W motor
Capacity 20.9 ai ,
carbon "steel
6.35 x 10 in neoprene
1492 W, neoprene
coated
7.6 x 10" m /s, carbon
steel, neoprene lined
0.47 m /s, inertial
separator, cyclone,
hoppers, fan, and
drive
1800 kg electric
0.94 ni /s, automatic
fabric dust collectors,
Factor
0.58
0.65
1.20
0.65
0.65
1.07
0.68
0.50
0.46
Depends
Factor
Source
Chem. Engr.
Guthrie
Chem. Engr.
Guthrie
Chem. Engr.
Guthrie
Chem. Engr.
Guchrie
Chem. insr.
Guthrie
3-24-69
3-24-69
3-24-69
3-24-69
3-24-69
Fund, of Cost Engr.
1964
Chem. Er.gr.
Guthrie
Chem. Engr.
Guthrie
3-24-69
3-24-69
Base
Cost
Each
(1977)
3,
2,
I,
52,
3,
5,
4,
3,
320
900
450
140
870
970
570
930
020
Total
Mid-1977
Cost
3
2
1
52
3
5
4
3
320
,900
,450
,140
,370
,970
,570
,930
,020
Fund, of Cost Engr.
1964
on gpm and head re-
quirements resulting
changes
size
0.80
0.81
0.68
of motor and
Chem. Engr.
Guthrie
Popper, H.
Chem. Engr.
in
impeller
3-24-69
3-24-69
1.
I,
10,
2,
990
460
890
730
3
1
10
2
,980
,460
,890
,730
bag support, shaker sys-
tem, isolation damper,
motor, drive, dust" hopper,
fan and motor
SUBTOTAL
97,230
D-ll
-------
TABLE D-2 (Cor.tinued)
AREA 3 - PARTICULATE SCRUBS ISC
Base
Size-Cost Cose
Scale Factor Each
1.
2.
3.
4.
5 .
6.
7.
Item No.
Tank 2
particulars
scrubber,
effluent.
hold
Lining 2
Agitator, 2
effluent.
hold tar.k
Pump s , 3
recycle
slurry
Vencuri 2
scrubber'
VB.nturi 2
sump
Soot blowers 10
Bleed pimp 3
Description . Factor Source (1977)
Capacity 199.4 m3,
carbon steel
6.35 x 10 m neoprane
7450 W, neoprene
coated
.26 m /s, carbon
steel, neoprene
lined
53.7 m /s, carbon steel,
neoprene lined
Carbon steel, neoprene
lining
1.6 x 10 m /s, carbon
steel, neoprene lined
0.68 Chen. Engr. 3-24-69 31,970
Guthrie
23,540
0.26 Fund, or Cost Engr. 5,770
1964
0.50 Chem. Engr. 3-24-69
Guthrie
Depends on gpm and head re- 17,450
quiretnenta resulting in
changes of motor and impeller
size
0.60 Universal Oil 121,040
Products
0.68 Cheni. Engr. 3-24-69 44,000
Guthrie
1.00 TVA 4,820
Depends on gpm and head re- 2,000
quirements resulting in
changes of motor and impeller
size
Total
Mid-1977
Cost
63,940
27,080
11,450
52,350
242,080
88,000
48,200
6,000
SUBTOTAL
D-12
-------
TABLE D-2 (Continued)
AREA 4 - SOi SCRUBBING
Size-Cost
Scale Factor
1.
2.
3.
/.
5 .
6.
7.
3.
a _
10.
11.
Item
Spray cower
scrubber
Spray tower
sump
Tank,
absorber
effluent
hold
Lining
Agitator, S07
absorber
hold tank
Pumps, S02
absorber
recycle
Pump s ,
makeup
water
Soot
blowers
Demister
Pump, bleed
Tank,
demister
wash
PlLT.p ,
deir.ister
wash
SUBTOTAL
No.
2
2
2
2
2
3
2
10
2
4
2
4
Description Factor Source
Gas Flow 117.4 m3/s,
carbon steel, neoprene
Carbon steel, neoprene
lined
Capacity 707.9 m ,
carbon steel, field
erected
6.35 x 10 m neoprene
29840 W, neoprene
coated
.46 m /5, carbon steel,
neoprene lined
1.2 x 10 m /s, carbon
steel, neoprene lined
Carbon steel, neoprene
lined
6.7 x 10 "* n /s, carbon
steel, neoprene lined
Capacity 1.89 m , carbon
steel, neoprene lined
1.3 x 10 m /s, carbon
steel, neoprene lined
Wester Precipitator
Div., Joy Mfg. Co.a
0.68 Chem. Engr. 3-24-69
Guthrie
0.68 Chem. Engr. 3-24-69
Guthrie
0.50 Chem. Engr. 3-24-69
Guthrie
Depends on gpm and head re-
quirements resulting in
changes of motor and impeller
size
Depends on gpm and head re-
quirements resulting in
changes of motor and impeller
size
1 . 00 TVA
Depends on gpm and head re-
quirements resulting in
changes of motor and impeller
size
0.68 Chem. Engr. 3-24-69
Guthrie
Depends on gpm and head re-
quirements resulting in
changes of motor and impeller
size
Base
Cost Total
Each Mid-1977
(1977) Cost
145,260 290,520
44,000 88,000
45,820 91,640
39,220 78,440
13,250
27,000 27,000
1,500 3,000
4,820 48,200
14,500 29,000
2,000 8,000
1,400 2,800
1,500 6,000
672,600
Indicates source of spray tower cost
D-13
-------
TABLE D-2 (Continued)
AREA 5 - REHEAT
Icera
Item
1. Steam
reheater
2. Sooc
SUBTOTAL
No.
2
10
Description
Size-Cost
Scale
Factor
ractor
Source
Base
Cost Total
Each Mid-1977
(1977) Cost
2.0 x 10° W rating
73.4 m<- Jin-far
73.4
surface area
0.80 Chem. Engr. 3-24-69 52,350 104,700
1.00
TVA
4,820 48,200
132,900'
AREA 6 - GAS HANDLING
Item
1. Fan
Base
Size-Cost Cost Total
Scale Factor Each Mid-1977
No. Descriotion Factor Source (1977) Cost
2 1.14 x 106 W drive 0.68 Chem. Ener. 3-24-69 51,430 102,860
Guthrie
AREA 7 - SOLIDS DISPOSAL
1. Clarifier
2. Puir.ps, pond
feed
3. Pump, clarlfier 2
water recycle
4. Pump s,
particuJace
pond wat-er
recycle
5. Pumps, H02
pond wat;er
recycle
5.8 x 103 m3/s
1.4 x 10~3 m3/s, car-
bon steel, neoprene lined
4.4 x 10 m /s, carbon
steel, neoprene lined
3.7 x 10"3 m3/s,
carbon sceel, necprene
lined
5.8 x 10 m'Vs, carbon
steel, neoprene lined
0.68
PEDCO (PE-146)
Depends on gpn and head re-
quirements resulting in
changes of niocor and impeller
size
Depends on gpn; and head re-
quirements resulting in
changes of motor and impeller
size
Depends on gpm and head re-
quiremencs resulting in
changes of motor and impeller
size
171,600
1,500
3,500
4,000
1,100
171,600
3,000
7,000
3,000
2,200
SUBTOTAL
D-U
-------
TABLE D-2 (Continued)
AREA S - UTILITIES
Note: There is no process equipment in this area.
AREA 9 - SERVICES
Item
1. Payloader
2. Plant
vehicles
3. Maine. &
instrument
shop-
equipment
i. Service
building-
equipment
5. Stores-
equipment
SUBTOTAL
No.
Description
Size-Cost
Scale
Factor
Factor
Source
Base
Cost Total
Each Mid-1977
C1977) Cost
29,850 29,850
12,050
31,780 31,780
42,130 42,130
12,760 12,760
128,370
AREA 10 - PARTICLE RECIRCULATION
1.
Item
Wet ball
mill
Size-Cost
Scale
No. Description Factor
1 3.2 x 10~4 m3/s .65
Factor
Source
McGlamery
2. Pump,
particle
recirculation
3. Tank,
particle
recirculation
surge
SUBTOTAL
3.2 x 10~4 m3/s,
molded polypropylene
Capacity 1.1 o , carbon
steel, heoprene lined
Base
Cost Total
Each Mid-1977
(1977) Cost
29,950 29,950
Depends on gpm and head re-
quirements resulting in
changes of motor and impeller
size
.68
McGlamery
500
1,000
1,000
1,000
31,950
D-15
-------
RADIAN
CORPORATION
2.0
COST FOR SLUDGE PONDS
The cost for the sludge ponds was not included in the
previous section because they were not considered to be equip-
ment items. The cost of the ponds, unlike the equipment items,
includes installation, and the cost for pumps and piping to and
from the pond (~1 mile) are included. The ponds are clay-lined,
and they are sized for a 30-year operation at 7000 hr/yr operat-
ing time. A midwestern plant location is assumed. The total
cost is expected to vary for each specific plant location due
to differing land costs. Table D-3 contains the cost informa-
tion for the sludge ponds.
TABLE D-3
Item
Prescrubber settling
pond, Standard System
COST DATA FOR SLUDGE PONDS
Area @ 40 foot Source
Depth (acres)
8. 2 TVA
Total Cost
Mid-1977
Dollars
120,000
Absorber settling
pond, Standard System
Prescrubber settling
pond, Recycle System
11.5
7.1
TVA
TVA
170,000
104,000
Absorber settling
pond, Recycle System
11.2
TVA
166,000
D-16
-------
TECHNICAL REPORT DATA
(Please read limnictions on the reverse before completing)
1. REPORT NO.
EPA-600/2-76-281
3. RECIPIENT'S ACCESSION-NO.
4. TITLE AND SUBTITLE
Desulfurization of Steel Mill Sinter Plant Gases
5. REPORT DATE
October 1976
6. PERFORMING ORGANIZATION CODE
7.AUTHOR(S)Gary D Brown> Richard T. Coleman, James
C. Dickerman, and Philip S. Lowell
8. PERFORMING ORGANIZATION REPORT NO.
9. PERFORMING ORGANIZATION NAME AND ADDRESS
10. PROGRAM ELEMENT NO.
Radian Corporation
P.O. Box 9948
Austin, Texas 78766
1AB015; ROAP 21AQR-005
11. CONTRACT/GRANT NO.
68-02-1319, Task 58
12. SPONSORING AGENCY NAME AND ADDRESS
EPA, Office of Research and Development
Industrial Environmental Research Laboratory
Research Triangle Park, NC 27711
13. TYPE OF REPORT AND PERIOD COVERED
Task Final; 3-9/76
14. SPONSORING AGENCY CODE
EPA-ORD
15. SUPPLEMENTARY NOTES IERL_RTp task officer for this report is Norman Plaks, 919/549-
8411 Ext 2557, Mail Drop 62.
is. ABSTRACT
rep0r|- gives results of an evaluation of the technical and economic
feasibility of using limestone scrubbing technology to control sinter plant emissions.
Data from Soviet and Japanese sinter plants employing limestone scrubbing technol-
ogy were used to develop a realistic design basis. A conceptual process design was
developed and used to prepare economic estimates. Results of the process .design
indicate that control of sinter plant emissions by limestone scrubbing is technically
feasible. Economic evaluations show that limestone scrubbing will increase the cost
of producing sinter by about $1. 82 per metric ton of product sinter for a standard
sinter plant operation. For a sinter plant with a windbox gas recirculation system,
the cost increase would be about $1. 44 per metric ton of product sinter.
17.
KEY WORDS AND DOCUMENT ANALYSIS
DESCRIPTORS
b.IDENTIFIERS/OPEN ENDED TERMS
c. COSATI Field/Group
Air Pollution
Sintering Furnaces
Iron and Steel Industry
Sulfur Oxides
Dust
Cost Analysis
Desulfurization
Scrubbers
Calcium Oxides
Limestone
Air Pollution Control
Stationary Sources
Windbox
Gas Recirculation
Particulate
Lime/Limestone Scrub-
bing
13B
13A
11F
07B
11G
14A
07A
08G
13. DISTRIBUTION STATEMENT
Unlimited
19. SECURITY CLASS (This Report)
Unclassified
21. NO. OF PAGES
215
20. SECURITY CLASS (Thispage)
Unclassified
22. PRICE
EPA Form 2220-1 (9-73)
D-17
------- |