RESEARCH REPORT
FEASIBILITY STUDY OF CENTRALIZED
AIR-POLLUTION ABATEMENT
to
NATIONAL AIR POLLUTION
CONTROL ADMINISTRATION
PUBLIC HEALTH SERVICE
DEPARTMENT OF HEALTH, EDUCATION,
AND WELFARE
November 17, 1969
BATTELLE MEMORIAL INSTITUTE
COLUMBUS LABORATORIES
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- - -- --
THE COLUMBUS LABORATORIES of Battelle Memodal Iostitute
research center of an international organization devoted to research.
comprise the original
The Institute is frequently described as a "bridge" between science and industry - a role it
has performed in more than 90 countries. As an independent research instirute, it conducts
research encompassing virtually all facets of science and its application. It also undertakes
programs in fundamental research and education.
Battelle.Columbus - with
contract research. It pursues:
its staff of 3.000 - serves industry and government through
.
research embracing the physical and life sciences, engineering, and selected social
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.
~esign and development of materials, products. processes, and systems
.
information analysis, socioeconomic and
ment planning research.
technical economic srudies, and manage-
505 KING AVENUE. COLUMBUS, OHIO 43201
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,
FINAL REPORT
on
FEASIBILITY STUDY OF CENTRALIZED
AIR-POLLUTION ABATEMENT
to
NA TIONAL AIR POLLUTION
CONTROL ADMINISTRATION
PUBLIC HEALTH SERVICE
DEPARTMENT OF HEALTH, EDUCATION,
AND WELFARE
November 17, 1969
by
M. Fels and H. L. Crawford
Contract No. PH-86-68-84, Task 12
BATTELLE MEMORIAL INSTITUTE
Columbus Laboratories
505 King Avenue
Columbus, Ohio 43201
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TABLE OF CONTENTS
INTRODUCTION.
Page
I
SUMMARY
I
APPROACH
2
CHARACTERISTICS OF INDUSTRIAL PLANTS CHOSEN
3
Cement Plant.
Lime Plant.
Sulfuric Acid Plant.
Power Plant
Fertilizer Plant.
Gray-Iron Foundry.
Electric-Arc Furnace.
3
5
6
8
9
II
13
ECONOMICS OF INDIVIDUAL AIR POLLUTION CONTROL.
14
Cement Plant.
Lime Plant.
Sulfuric Acid Plant.
Power Plant
Fe rtili ze r Plant.
Gray-Iron Foundry.
Electric-Arc Furnace.
Stack, Plant, and Labor
14
15
15
15
16
16
16
17
GAS TRANSPORTATION SYSTEM TO CENTRAL FACILITY
18
Piping Cost Estimates.
Fan Cost Estimates.
Motor Cost Estimates.
Damper Cost Estimates
Operating Costs.
Total Gas-Handling Cost Estimates
Summary of Major Assumptions and Specifications
21
24
24
25
25
26
26
EMISSION CONTROL FOR TOTAL GAS SYSTEM.
26
Control Device
Cost Considerations
26
28
DISCUSSION
29
CONCLUSIONS
32
REFERENCES
32
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Table 8.
Table 9.
Table 10.
Table 11.
Table 12.
Table 13.
Table 14.
Table C-1.
LIST OF TABLES
(Continued)
Summary of Individual Air-Pollution-Control Costs.
Page
17
Stack-Cost Data
17
Minimum Transport Velocity for Polluted Air
20
Pipe Costs for 20-Inch Water-Pressure Loss.
23
Pipe Costs for 3S-Inch Water-Pressure Loss.
24
Mixed Gas Composition.
28
Cost Summary.
29
Gas Flow Rates for Individual Processes
C-l
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TABLE OF CONTENTS
(Continued)
Page
APPENDIX A
GAS COMPOSITIONS
A-I
APPENDIX B
COST CALCULATIONS.
B-1
APPENDIX C
TOTAL GAS CALCULATIONS
C-l
Figure 1.
Figure 2.
Figure 3.
Figure 4.
Figure 5.
Figure B-1.
Table 1.
Table 2.
Table 3.
Table 4.
Table 5.
Table 6.
Table 7.
LIST OF FIGURES
Plot Plan of Gas Transport System.
19
Installed Cost of Carbon Steel Pipe.
22
Comparison of Installed Pipe Cost for Three Types of Steel
(Four-Inch Pipe Line)
22
Installed Cost of Gas Transport System
27
Effect of Distance on Cost Difference Between Centralized and
Individual Control Abatement.
31
Prices for Brink Demisters
B-9
LIST OF TABLES
Emission Data for Cement Plant Kiln
4
Emission Data for Lime Plant
5
Emission Data for Sulfuric Acid Plant.
7
Emission Data for Power Plant
.
8
Emission Data for Fertilizer Plant.
10
Emission Data for Gray-Iron Foundry.
12
Emission Data for Electric-Arc Furnace.
13
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FEASIBILITY STUDY OF CENTRALIZED
AIR-POLLUTION ABATEMENT
by
M. Fels and H. L. Crawford
INTRODUCTION
Industrial plant complexes discharge a variety of pollutants to the environment.
These discharges include both particulate and gaseous pollutants over a wide range of
concentration, volumetric flow rates, and temperatures. Recently, there has been in-
creasing concern regarding the esthetic and health aspects of these emissions to the at-
mosphere, and it has become necessary to limit the amount of pollutants discharged to
the atmosphere. Unfortunately, the devices to control pollution are expensive, and, in
many cases, the pollutants collected are of no economic value to the company. Thus,
any reduction in the economic burden of air-pollution control would be greatly welcomed
by both government and industry alike.
The concept investigated in this report stems from an attempt to develop less ex-
pensive means of air pollution control. This concept is the centralization of pollution
control by having the polluted effluents from individual plants come to a centralized
treatment facility. The reasoning behind this concept is that one large piece of control
equipment would cost less per unit amount of gas treated than would several small units.
For example, in the chemical-proces 5 industry, capital costs of equipment increase, in
general, by size ratio to the 0.6 power, thus favoring larger units.
If implemented, the centralized concept would provide a system whereby all pol-
luted gaseous effluents could be discharged, untreated, to a system of manifolds which
would permit the gases to be pumped to the centralized treatment facility. At the cen-
tralized facility, the total mixed polluted gases would be purified and discharged to the
atmosphere.
bility
The purpose of the present study is to present the results
study of the centralized air-pollution-abatement concept.
of a preliminary feasi-
SUMMARY
The technical and economic aspects of a centralized air-pollution-control plant
located at a distance from seven industrial plants were investigated. The plants chosen
were: (1) lime, 200 tons/day, (2) cement, 4500 barrels/day, (3) sulfuric acid, 400 tons/
day, (4) power, 25 Mw, (5) fertilizer, 570 tons/day, (6) gray iron, 1440 tons/day, and
(7) electric arc, 2600 tons/day. Gaseous- and particulate-emission levels were taken
from literature sources, and as far as possible, average values were used £01" each
industry.
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afte r
The total amount of gas from these plants was found to be
mixing. The study showed the following results:
627,000 cfm at 320 F,
Capital Cost,
million dollar s
Operating Cost,
millions of dollars /
year
Individual Treatment
5.4
1.7
Centralized Abatement
Pollution Control
Transportation ( 3 miles)
2.5
11. 5
0.9
2.8
It was concluded that, although the centralized control facility is less expensive than
individual control devices, the transportation cost is 80 high as to make the centralized
concept unattractive. The results also show that the economics would begin favoring
the centrali,!,ed concept if each of the seven plants were located at about 1/2 mile from
the central facility; this distance was considered to be unrealistically close from the
standpoint of individual plant's land requirements.
Othe r disadvantages of the centralized concept included: (1) emis sions from the
lime, cement, and sulfuric plants were rendered valueless, (2) a malfunction in the
centralized control equipment would create large problems by releasing large quantities
of pollutants over a relatively small area, (3) vegetation growth over the buried gas
pipes would be inhibited, leading to potential esthetic problems.
APPROACH
As originally conceived, the study was to utilize air-pollution-emission data in a
document entitled "The Kanawha Valley Report" to develop criteria for (n selection of a
model site for the feasibility study and (2) performance of the economic and technical
analyses necessary to provide a basis for judging the concept feasibility.
The Kanawha Valley Report was received in draft form and reviewed carefully.
It was found that the type of data obtained in the Kanawha Valley study and the method of
reporting these data rendered the results essentially useless for the research program.
Specifically, the individual company questionnaire requested data on plant emissions in
terms of pounds per day; but, for estimating clean-up costs, gaseous flow, and pollutant
concentrations are required. In addition, data from the individual company surveys are
not reported. Instead, total estimated emis sions are reported as tons of pollutants dis-
charged per year in the entire study area.
Therefore, it was decided to attempt to collect the necessary data from individual
companies. These data would take the form of composition of effluent gases, flow rates,
temperatures, and the means and economics of pollution control in present use. In the
course of discussions with industry representatives, a number of difficulties associated
with this approach were uncovered, which led to its abandonment.
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A decision was then made to work with a hypothetical industrial complex using
emission data which could be found in the literature. A brief preliminary study showed
that there were enough emission data for the purposes of this study from the following
industries:
( 1 ) Cement Plant
(2) Lime Plant
(3) Sulfuric Acid Plant
(4) Coal-Burning Power Plant
(5) Fertilizer Plant
(6) Gray-Iron Foundry
(7) Electric-Furnace Steel Plant
The discussion to follow deals with the emission characteristics and pollution-
control costs for each of the seven plants. Consideration of the total abatement concept
will be done by discussion of the system for transporting the effluent gases to the cen-
tralized treatment plant, and of the central plant itself.
CHARACTERISTICS OF INDUSTRIAL
PLANTS CHOSEN
Cement Plant
Prace 5 S De scription
Portland cement is made by mixing calcareous (calcium-containing) and argillace-
ous (clay-containing) materials in the proper ratios. Essentially, the unit operations
prepare the raw materials in the necessary proportions and in the proper physical state
of fineness and intimate contact so that the chemical reactions can take place at the tem-
perature in the kiln to form various silicates and aluminates. Four major steps in the
production of portland cement are quarrying and crushing, grinding and blending, pro-
duction, and finished grinding and packaging. A good description of these operations is
given in Kreichelt, et al. (1)
Cement is made by either the wet process or the dry process. In the dry process,
the raw materials are ground, mixed, and blended as dry powders; whereas, the wet
process involves a slurrying of the raw materials in the grinding, mixing, and blending
operation.
Emissions and Their Control
Emission Data. Particulate matter is the primary emission in the manufacture of
portland cement. There are also the normal combustion products of the fuel used to
supply heat for the kiln and drying operations, including oxides of nitrogen and small
amounts of oxides of sulfur. The three sources of dust emission are the crushing opera-
tion, grinding operation (in the dry process), and the kiln operation.
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The purpose of the crushing operation is to reduce the quarried material from
boulder- size down to convenient size, 3/4-inch rock for handling and transportation to
the cement plant. This ope ration is usually done at the quarry. The amount of dust
generated during this operation depends on factors such as moisture content of the rock,
methods of handling, and type of rock. Because of the remote location of the operation,
and because of the relatively large sizes of rock involved, the dust emissions are of
minor importance. Thus, for this study, these emissions were neglected.
The purpose of the grinding operation is to reduce the size of the cement rock to a
fineness suitable for effective reaction in the kiln. This operation is performed on the
dry material in the "dry processll, and a cons ide rable amount of dust is generated. In
the wet process, water is added to the grinding mill with the crushed feed to form a
slurry. No dust is generated in the grinding operation because of the slurry condition.
Kreichelt, et al., note that there are 110 wet-process plants and 69 dry-process
plants. (1) Therefore, emission calculations were made for the wet process, and dust
arising from the grinding operation was not taken into account.
The dust from the kiln is of major importance. Generated by the drying and
clinkering of the cement itself, this dust is entrained by the gaseous products in the
combustion of fuel at one end of the kiln. Kreichelt, et al., give emission data for
22 wet-process cement plants; from these data, averages were calculated for use in the
present study. Calculations for the gaseous composition are shown in the Appendix A.
Table I shows the data used in subsequent calculations for emission control costs.
TABLE 1.
EMISSION DATA FOR CEMENT PLANT KILN
4500 BarrelslDay
Variable
Value
Gas Volume, 1000 acfm
Gas Temperature, F
193
404
Particulate Loading, gr I ft3
Outlet Loading, gr/ft3
5.4
0.05
Gas Composition, volume percent
NZ
Oz
COZ
HZO
SOZ
48.Z
1.3
19.5
31
Trace
Mter clinkering, the cement is ground again to a fineness of about IO-micron
average particle size. Closed circuit grinding is the common practice; dust collectors
that are an integral part of the fine-grinding equipment keep atmospheric emissions
down to a negligible level.
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Emission Control. The emissions from the cement plant are in the form of rela-
tively fine particles; for example, from 20 to 40 percent of the dust has a diameter less
than 5 microns. Consequently, Kreichelt, et al. (1), report that only collectors such as
the electrostatic precipitator effectively collect fine dust. According to the data given
for several plants, 8 of 14 dry-process plants use electrostatic precipitation, and only
1 wet-proces s plant of 22 doe s not use electrostatic precipitation for pollution control.
Therefore, in this study it was as sumed that the cement plant will use electrostatic
precipitation as its primary means of pollutant dust control.
Lime Plant
Process Description
\
Lime is produced by heating limestone to decompose the limestone into carbon
dioxide and lime. Heat is produced by burning coal or natural gas. Both vertical and
rotary kilns are used in the production of lime, but rotary kilns have a higher capacity.
A good discussion of the lime industry is given by Lewis and Crocker. (2)
Emissions and Their Control
Emission Data. The major air contaminant from lime manufacturing is dust.
This dust arises from crushing, screening, and kiln discharge. The dust consists
mainly of CaC03 and CaO, which can be irritating to the eyes, respiratory membranes,
and moist skin. Although some dust is produced from the crushing and screening opera-
tions, the major emissions are generated in the kiln operation.
Typical dust loadings for both the vertical- and rotary-kiln operation are given
by Lewis and Crocker. (2) Also given are typical data for production rates, gas tem-
peratures and volumes, fuel-to-lime ratios, and C02 content of the effluent gases. On
the basis of these data, calculations for the composition of the exit gases can be made;
they are shown in Appendix A. Because rotary kilns are more com.mon and also create
more of an air-pollution problem, the rotary lime kiln was chosen as the basis for a
typical plant in the centralized air-pollution-abatement model. Table 2 gives the perti-
nent data necessary on emissions from the lime plant.
TABLE 2. EMISSION DATA FOR LIME PLANT
200 Tons/Day
Varia ble
Value
Gas Volume, 1000 acfm
Gas Temperature, F
Paniculate Loading gr/ft3
29
910
6
Gas Composition,
N2
~
C02
~O
S02
volume percent
56.5
1.4
31. B
10.2
0.1
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Emission Control. In general, four types of control equipment are used to clean
kiln gases. They are cyclone collectors, bag filte rs, electrostatic precipitators, and
water scrubbers. From data given in Lewis and Crocker, it appears that the bag filters
do a satisfactory job of particulate removal from effluent gases. (2) Also, they are
relatively inexpensive compared with other control equipment such as the electrostatic
precipitators and water scrubbers. Cyclone collectors can be used only as prim.ary
elements for the removal of the plus 10-micron-size dust. Thus, for this preliminary
study, costs were based on the use of bag filters in the lime plant. Other data on pollu-
tion control in the lime industry can be found in References (3) and (4).
Sulfuric Acid Plant
Process Description
Sulfuric acid is made generally by combustion of sulfur with air to yield S02;
oxidizing the S02 catalytically to S03; and reaction of 503 with water to yield the final
product, H2S04' Two processes by which H2S04 is produced are the chamber and the
contact prace ases.
In the chamber process, S02 is oxidized to 503 in the presence of various oxides
of nitrogen. The oxidation takes place in large chambers, and the nitrogen oxides are
then recovered in a I1Guy Lussac" tower. The chamber process currently produces
approximately 10 percent of the total sulfuric acid in the United States, but it is expected
to account for less in the future. This process yields relatively weak acid. Because
the acid is more dilute than acid from. the contact process, transportation costs per unit
of H2S04 are higher. Construction and operating costs are usually higher than those for
contact plants. For these reasons the chamber process is today a small factor in sul-
furic acid production.
In the contact process the gases leaving the combustion chamber (8 to 11 percent
S02) are cooled and passed over a solid catalyst which promotes the oxidation of S02 to
S03' The S03 is then absorbed in water in an absorption tower. Cuffe and Dean give a
detailed description of the processing operation involved. (5)
Emissions and Their Control
Emission Data. The major s'ource of air pollution in the sulfuric acid industry is
the discharge of S02 and acid mist in the effluent gas stream. S02 in the stack gas re-
sults from the incomplete conversion of S02 to S03 in the catalyst converter. Conver-
sion efficiencies of 98.0 to 98.5 percent are attainable with proper plant design. Higher
conversion efficiencies require a more expensive plant and result in higher production
costs. The unconverted 502 from the catalyst converter passes through the absorption
system and is discharged to the atmosphere. Data of Cuffe and Dean show that S02
concentrations in the absorber discharge stack ranged from O. 13 to 0.54 percent, with
a mean (based on 33 tests) of 0.26 percent. (5)
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Sulfuric acid mists in stack gases arise from two sources. The first is related
to the hydrocarbons present in sulfur (from O. 1 to 0.3 percent). When sulfur is burned,
the hydrocarbons present are converted to COZ and water. The water later reacts with
the S03 produced in the converter to form sulfuric acid. The reaction takes place in
the vapor phase with the resulting sulfuric acid condensing out as a fine aerosol or mist
as the gas cools down in equipment and/ or ducts between the conve rte r and absorbing
tower. Much of the mist formed in this manner passes through the absorber packing and
must be collected by mist-collection equipment, if objectionable mists are to be
eliminated.
The second source is sulfuric acid spray which generally results from the en-
trainment of acid by the gas on leaving the packing in the drying and absorbing towers.
The pertinent data for pollution control calculations were obtained from Cuffe and
Dean(5), and are shown in Table 3. Calculations for the amount of nitrogen and oxygen
content of the gas are shown in Appendix A.
TABLE 3.
EMISSION DATA FOR SULFURIC
ACID PLANT
400 Tons/Day
Variable
Value
Gas Volume, 1000 acfm
Gas Temperature, F
Z6.5
154
Acid Mist Loading, gr/ft3
O. 13
Gas Composition, volume percent
NZ
°z
SOZ
85.8
13.8
0.z6
Emission Control. Although the SOZ amounts to O. Z6 percent in the stack gases,
Cuffe and Dean report that little or no recovery is attempted in actual practice. (5) Pre-
sumably' one of the reasons for this is the relatively low flow (about Z6, 000 cfm) of
effluent gases from an average sulfuric acid plant. Thus, the SOZ discharge, in terms
of amount per hour, is quite low. However, in a few plants, scrubbers have been used
to reduce the SOZ level in the stack gases. As there are no reliable cost data for SOZ
removal for sulfuric acid plants, it will be assumed for the purposes of this study that
SOZ control will not be used. The exchange of the mist eliminator (discussed below)
for a wet scrubber would not change the economics substantially.
Much more work has gone into the investigation of acid-mist removal. Brink has
developed a fiber mist eliminator which can operate at efficiencies of about 99 per-
cent. (6, 7) In this design, the gas containing the mist is passed through a fiber packing.
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The mist particles are collected as a film on the surface of the fibers. The collected
liquid flows through the bed by gravity, drips into a seal pot, and is recycled to the
process. In this way, essentially all of the sulfuric acid mist can be collected.
Power Plant
Process Description
Basically, the power-plant concept as applied here is concerned with the combus-
tion of a fuel to produce steam; the steam then drives turbogenerators for the generation
of electricity. The majority of plants utilize coal as a fuel, but oil or gas are also
burned to some extent.
Emissions and Their Control
Emission Data. The major pollutants from fossil-fuel-burning plants are oxides
of sulfur and nitrogen. Sulfur dioxide, the major constituent, is the prime object of
current and future control activities.
The sulfur oxides in the combustion gases arise from combustion of the sulfur in
the fuel. For example, the sulfur content of coal in this country ranges from about
0.5 to about 6 percent by weight.
The gaseous emissions from a typical power-generating station are from 50 to
100 times that of the total of the other 6 processes considered in this study. Therefore,
for this study a small plant (Z5, 000 Kw) is used; one that would, for example, supply
the small industrial complex used in this study. Gas-flow rates and compositions were
obtained from Katell(8) and are shown in Table 4.
TABLE 4.
EMISSION DATA FOR POWER PLANT
Z5, 000 Kw
Variable
Value
Gas Volume, 1000 acfm
Gas Temperature, F
Particulate Loading, gr/ft3
70
300
1.5
Gas Composition, volume percent
NZ
°z
COZ
HZO
SOZ
S03
76. Z
3.4
14.Z
6.0
O.Z
Trace
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Emission Control. Many processes have been proposed to deal with the removal
of sulfur dioxide from stack gases. They are all in various stages of development from
bench scale to large pilot-plant operations. Two processes, the catalytic-oxidation and
the dolomite process, have been developed enough for reasonable cost estimation(9), and
they show some promise of commercial feasibility.
In the catalytic-oxidation process, the hot flue gases are cleaned of their particu-
late matter by electrostatic precipitation, and then are passed into equipment which is
essentially a contact sulfuric acid plant. In the dolomite process, the flue gases are
contacted with a mixture of carbonates, mainly calcium and magnesium (either dry or in
slurry form). Reaction of S02 with the dolomite occurs, producing the corresponding
sulfates, which are then disposed of.
The catalytic oxidation process requires a greater investment than does the dolo-
mite process, but it does not have the disposal problems of the dolomite process. Eco-
nomic aspects of both of these processes are discussed in the section on IIEconomics of
Individual Air Pollution Control". Because of the amount of effort in the area of S02
control devices, better systems probably will be evolved; as shown later, such improve-
ments would merely strengthen the conclusions of this study.
Fertilizer Plant
Process Description
Fertilizers, as defined here, are those containing phosphorus. Common to all
these fe rtilizers is the starting material, phosphate rock. Phosphate rock is mined in
open pits, then screened and washed to recover the larger size fraction. Subsequent
flotation recovers the smaller particles of additional value. The wet rock is then dried
and ground for shipment and further processing. The major fraction is shipped as
ground phosphate rock.
The fertilizer products to be considered here are run-of-pile triple superphos-
phate, diammonium phosphate, and granular triple superphosphate. Run-of-pile triple
superphosphate is produced by the continuous acidulation of dried and ground phosphate
rock with phosphoric acid in a reactor, such as a TVA mixing cone. The resulting
slurry is discharged directly to a slow moving settling belt where the reaction produce s
a solid material. This "green" triple is stored from 30 to 60 days in a curing building
where the reaction continues at a decreasing rate. When cured, the product will con-
tain about 46 percent soluble P20S' The final product is mined from the "pile" in the
curing shed. It is crushed, screened, and shipped in bulk.
Some 5 to 6 years ago, a new fertilizer product known as "diarnmonium phosphate II
was introduced to the market. It is produced by the ammoniation of phosphoric acid
with a subsequent granulation and drying. The acid is pre neutralized in a vertical reac-
tion tank with additional ammoniation and granulation taking place in rotating horizontal
drums. The product is dried in rotary-drum kilns, then sized and transferred to the
storage and shipping building.
Two different methods are used for the manufacture of granular triple superphos-
phate. One method continuously acidulates phosphate rock with phosphoric acid. The
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resulting slurry is fed to blungers where it is mixed with recycle materials to start
the granulation. From the blungers the material is passed through granulating drier
kilns at a controlled speed and temperature. The other method passes cured and
screened run-of-pile material through drum granulators in the presence of steam. It is
then dried in horizontal, rotary kilns.
Emissions and- Their Control
Engdahl and Sachse 1 describe the sources of pollution arising from fertilizer-plant
operation. (10) Two sources of pollutant exist in fertilizer manufacture: rock dust from
grinding, and fluoride -bearing fumes and gases from acidulation.
If the air- swept mill and the dust collector for rock grinding are properly
designed, over grinding is the most likely source of dust that can usually be traced to
improper operation of the mill.
Acidulation fumes and gases cannot be avoided. In the dried and ground state,
phosphate rock contains 3.5 to 4.0 percent fluoride, of which 1/3 to 1/2 is evolved from
subsequent chemical or thermal processing. The evolved fluorides are probably present
as silicon tetrafluoride and hydrogen fluoride.
Huffstutler reports emission levels for the various fertilizer plants in pounds per
hour of fluorides and ammonia in the case of diammonium phosphate. (II) These data
are summarized as averages in Table 5. This source does not give quantitative data
on total exhaust gas rate. It was assumed that the exhaust from the buildings would be
approximately 100,000 cfm at ambient temperatures.
TABLE 5. EMISSION DATA FOR FERTILIZER PLANT
Ernis sians Emissions
Average Before Afte r Scrubber
Production, Scrubbing, Scrubbing, Efficiency,
Fertilizer Product ton/ day Ib/ ton Ib/ ton percent
Run-of-Pile Triple 860 5.8 O. 16 97.2
Superphosphate
Diammonium Phosphate 644 6.2 0.38 92. 7
Granular Triple 214 3.8 0.15 96.0
Superphosphate
Averages 573 5.3 0.23 95.3
Emission Control. As mentioned before, the major source of pollution is in
fluoride emissions. Fortunately, SiF4 and HF are quite soluble in water. Therefore,
a wet-contact device can be used to remove these fluorides. Huffstetler reports the use
of wet scrubbers in the fertilizer industry. Recent information suggests that the
scrubber design called a "crossed flow packed tower" is more suitable for fluoride
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removal than a venturi scrubber. However, as there are no cost or efficiency
data on this type of device, it is assumed that a wet scrubber of the venturi type will
be adequate for pollution control of fluorides.
Gray-Iron Foundry
Process Description
The principal device used in iron foundries to obtain molten metal for production
of castings is the cupola furnace. A cupola can be defined simply as a refractory-lined
cavity with necessary openings at the top for the escape of gases and for the charging
Of the stock, and openings at the bottom for entry of the air blast and for drawing off
the iron and slag.
Cupolas are used for almost all gray-iron melting, and as the primary melting
unit for much malleable-iron production. They are used commercially in heats lasting
from Z hours a day to several successive days, with hourly outputs from Z to 50 tons.
Additional information on cupola operation can be obtained from Reference (13).
Emissions and Their Control
Emission Data.
various metals, their
sulfur compounds are
0.6 percent or less.
Emissions from the cupola consist of coke and flux particles,
oxides, and some condensible oils and greases. Emissions of
usually small because the sulfur content of cokes is generally
Because of the variations of infiltrated air, grain loadings also show wide varia-
tions. For example, data on three cupolas published in Reference (13) show variations
in grain loadings from 0.0014 to 1. 6 gr/ft3. For the present study, the highest grain
loading was taken, and grain loadings assumed to be about Z gr/ft3.
Calculations for the gaseous emission compositions are shown in Appendix A, and
the data are tabulated in Table 6. Cupolas are operated as either "hot-blast" or "cold-
blast". In the hot-blast operation, the air for combustion of the coke is preheated by
the exiting stack gases. The system also incorporates an afterburner to burn off the
CO and HZ emissions; the heat of combustion of these two emissions is used to help
heat the blast. The afterburner probably also oxidizes the small amount «0.001 gr/ft3)
of condensible oils and greases that are released during the cupola operation.
Most large, modern cupolas are hot-blast operations; however, a relatively large
number of small cold-blast units are still in operation. In these units, ambient air is
used for the blast, and the stack gases are discharged without heat recovery.
If a cold-blast operation were in use, an afterburner would be necessary for the
removal of the CO and oils, whether the emissions are treated at the cupola site or are
treated in the centralized facility. However, for the centralized concept, a cooler would
be necessary to cool the stack gases before they are transmitted to the centralized
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lZ
facility. The cost of the cooler would have to be added to the cost of the centralized
treatment plant. It does not seem feasible to discharge the cupola emissions from a
cold-blast operation directly into the centralized facility. The condensibles would prob-
ably make frequent cleaning of equipment necessary, and the removal of the relatively
large amount of CO from the mixed gases would be difficult and expensive. Therefore,
for this study, a hot-blast operation was assumed to avoid undue penalizing of the central
facility concept.
TABLE 6.
EMISSION DATA FOR GRAY-IRON FOUNDRY
60 Tons/ Hour
Variable
Value
Gas Volume, 1000 acfm
49.6
500
Gas Temperature, F
Particulate Loading, gr/ft3
Z
Gas Composition, volume percent
NZ
COZ
°z
HZO
SOZ
78.Z
19.7
0.4
1.7
Trace
Emission Control. Bloomfield has noted that collection equipment being purchased
for cupolas is of five types: (1) wet caps, (Z) fabric filters, (3) low-pressure-drop wet
scrubbers, (4) high-pres sure-drop wet scrubbers, and (5) multitube cyclones. (14)
Wet emission-control systems are generally used for cupolas
temperatures of cupola effluents restrict uses of other methods.
because the high
Wet-cap systems operate with natural draft. Pressure drop is about 1 inch of
water. They are made of stainless steel with rubber liners and can become part of a
wet-scrubber system in a future improvement. They remove only large, heavy
particle s.
The use of fabric filters requires cooling of cupola gases before contact with the
filter. Electrostatic precipitators used with cupolas have failed to maintain high collec-
tion efficiencies because of wide variations of gas-feed conditions, i. e., temperature,
humidity, volume and particulate chemical composition. Life and dependability of these
precipitators has been low and no attempts have been made in recent years to employ
them.
Sterling states that installation of wet scrubbers can accomplish a very high degree
of control. (15) For this study, therefore, it was assumed that a wet-scrubber installa-
tion would be chosen.
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Electric-Arc Furnace
Process Description
The electric-arc furnace consists of a refractory-lined shell to hold the material
to be melted, electrode s that can move vertically, and the means to tilt the pot. The
electric arc is characterized by its high temperature and concentration of heat energy.
The electrodes are either graphite or amorphous carbon. The heat is provided by an
arc to the charge or melt. Because the source of heat is nonchemical, electric furnaces
are especially desirable in melting alloys of controlled composition.
In 1967, electric arc furnaces produced about 11 percent of the total raw carbon
steel made in the United States and 36 percent of the alloy and stainless steels. About
59 percent of all electric furnace heats were carbon steels. Electric-arc furnaces have
capacities up to 200 tons.
Em.issions and Their Control
Emission Data. Emissions from the electric-arc furnace originate from light
scrap that oxidizes readily, from dirty scrap (a major source), and from oxygen lancing.
The main emis sians are fumes from scrap preheating, iron oxide dust from. the melting
operations, and furnace off-gases.
The amount of dust released per net ton of electric-furnace steel depends upon the
condition of the scrap and whether or not oxygen lancing is used. Dirty scrap can raise
the dust emissions from a normal level of 8 to 15 pounds to as high as 40 pounds per net
ton of steel. It has been estimated that oxygen lancing produce s 20 percent of the total
emissions. The composition of the off-gas from the electric furnace varies with prac-
tice. The chief constituents are carbon monoxide, carbon dioxide, nitrogen, and oxy-
gen. A more detailed description of emissions from the electric-arc furnace can be
found in Barnes and Lownie. (16) Table 7 lists the emissions from the electric-arc
furnace, calculated from data in Barne sand Lownie (Appendix A).
TABLE 7.
EMISSION DATA FOR ELECTRIC-
ARC FURNACE
2600 Tons/Day
Variable
Value
Gas Volume, 1000 acfm
Gas Temperature, F
Particulate Loading, gr/ft3
116.0
500
2. 5
Gas Composition, volume percent
N2
02
C02
CO
78.5
13.5
1. 35
6.75
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Emission Control. The types of air-pollution-control devices that can be used in
the electric-arc furnace are; high-energy venturi scrubbers, electrostatic precipita-
tors, and fabric filters. Of these, the fabric filter is most often used, probably because
it is relatively inexpensive compared to the first two. Therefore, for this study, a
fabric-filter installation was chosen to control the air-pollution problems from the
electric -arc furnace.
ECONOMICS OF INDIVIDUAL AIR-POLLUTION CONTROL
In the ensuing discussions of the costs of air-pollution-control equipment, it must
be emphasized that accurate estimates both of the capital and operating costs involved
are virtually impossible. There are several basic reasons for this:
(1) Each installation of a control device is different and depends on many
factors, such as actual plant geometry, labor, etc. Thus, cost
information from seemingly similar installations in many cases shows
discrepancies of up to 50 to 100 percent.
(2)
The cost of operating the control installation is dependent on a great
many factors. Even the cost of the device in the plant itself varies from
time to time. Some of these factors include age of installation, changes
in production rate or in feed materials, etc.
(3) It is often very difficult to
using these devices.
obtain cost information from the industries
The following section details the cost estimates for each of the seven plants.
When there were several sources of cost data for a particular type of installation, the
cost figures were averaged. Also where a range was quoted, the mid-point of the range
was taken.
One general assumption which was made was that the annual cost could be esti-
mated by taking the operating costs and adding 20 percent of the capital expendi-
tures. (16) Again, it must be kept in mind that these costs can be in error by 50 to
100 percent. However, as will be seen later, errors of this magnitude do not affect
the final conclusion of this study. Costs quoted here have been scaled to 1969 prices.
Table 8, which appears at the end of this section, summarizes the data on the costs.
Cement Plant
As mentioned previously, the pollution-control device of choice is the electro-
static precipitator. The cost of an electrostatic precipitator is a function of many
parameters, the major ones being the gas load and efficiency. The efficiency is in turn
related to the particle size distribution. Sargent gives data on electrostatic precipita-
tor costs for a 60,000 cfm (68 F) unit. (17) He also lists the efficiencies of this precipi-
tator with a "standard dust". With his data it is possible to calculate that the efficiency
of the electrostatic precipitator whose costs are given would be about 92 percent when
BATTELLE MEMORIAL INSTITUTE - COLUMBUS LABORATORIES
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handling the dust emissions from the cement plant. As the efficiency required is
(5.4-0.05)/5.4= 99 percent, the electrostatic-precipitator costs reported by Sargent
would be too low; and, if this precipitator were used, the outlet loading would be about
0.4 gr/ft3. Data taken from Barnes and Lownie (page C-80) indicate that reducing the
dust loading 2-1/2 times requires a 10 percent increase in capital and operating expen-
ditures. From this information, it can be calculated that the capital and operating costs
reported by Sargent should be increased by about 24 pe rcent. Pertinent calculations
are detailed in Appendix B.
The cost data of Sargent yield a capital expenditure of $490,000 and a yearly
operating cost of $106,000. Barnes and Lownie report a capital cost of $905,000 and an
annual operating expense of $277,000 for an electric-arc furnace handling 185,000 cfm
at 500 F. It was assumed that a reasonable estimate of the costs involved could be ob-
tained by averaging the costs reported by both Sargent and by Barnes and Lownie.
Lime Plant
Lewis and Crocker report a capital expense of $1. 80 per cfm and annual operating
expenses of $.20 per cfm. (2) Bergstrom et al., report these costs to be $1. 55 and $.08
(maintenance only). (4)
Data of Sargent(l7) indicate capital and annual operating expense s (includinr,
20 percent of capital) of $1. 50 and $.47 per cfm (at 910 F). Barnes and Lownie( 6) give
costs of $2. 13 and $.78 per cfm for capital and annual operating expenses for a fabric
filter to control particulate matter from electric furn~ces.
When the 20 percent of capital expense is added to the operating costs reported by
Lewis and Crocker and by Bergstrom, an average of all the costs yields $1. 75 per cubic
foot capital and $.55 per cubic foot annual operating expense.
Sulfuric Acid Plant
To control mists, a fiber mist eliminator will be used. In order to obtain the cost
of these units, Dr. Brink(l8) was contacted, and he provided the cost curves for the mist
eliminators (see Figure B-1 in Appendix B). A conservative estimate was made by
choosing the most costly unit. The price of this unit for the gas-flow rate of
26,500 cfm, is about $55,000. Brink suggests that the installation costs would be about
100 percent of the unit costs. Direct operating expenses would be low and, thus, the
operating cost per year was assumed to be 20 percent of the capital cost.
Powe r Plant
As mentioned before, the two processes to be considered for S02 control are the
catalytic oxidation and the dolomite process. Capital and operating costs for the cata-
lytic oxidation process have been detailed by Lemmon et al., based on the work of
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Katell. (8) For a 25 Mw unit, capital investments would be $1. 9 million, with annual
operating expenses of $630,000. This operating expense assumes the saleability of
sulfuric acid at $14 per ton. However, in the present case, sulfuric acid production
would amount to only about 15 tons/day, and the price obtainable per ton at this small
production level would probably be lower, resulting in a higher operating expense.
For the dolomite process, the slurry, or wet process was chosen because it has
a higher efficiency and can remove 90 percent of the S02. Schuler, et aI., have given
data on both capital and annual operating costs of the wet dolomite process. (19) These
costs for the 25 Mw power plant are $645,000 and $250,000, respectively. Thus, it can
. be seen, that, for the relatively small power plant used in the present study, the dolo-
mite process would be the preferred means of S02 control.
Fertilizer Plant
Costs for a high-energy, venturi-type scrubber having an efficiency of over 99 per-
cent as reported by Sargent(17) are $180,000 capital, and $90,000 annual operating.
Barnes and Lownie(16) report costs for a high-energy, wet scrubber which handles
100,000 cfm at 100 F to be $357,000 and $168,000 for capital and annual operating,
respectively. For the fertilizer plant, a low-energy scrubber installation would prob-
ably be adequate. Thus, cost data reported by Barnes and Lownie were lowered by the
ratio of the cost of high-energy wet scrubbing to low-energy wet scrubbing as computed
from the data of Sargent. (17) Again, the average of the two sets of data was taken to
give an estimate of the costs involved. Calculations are shown in Appendix B.
Gray-Iron Foundry
For the gray-iron foundry, costs of venturi scrubbers were estimated from the
data of Barnes and Lownie. (16) The gaseous emissions from the electric-arc furnace,
open-hearth furnace, and basic oxygen furnace have similar characteristics as those
from the cupola. Barnes and Lownie report capital costs for wet scrubbers on the three
furnaces ranging from $7.20 to $9.30 per cfm, and annual operating expenses ranging
from $3.00 to $3.72 per cfm. Average values were $8.03 and $3.39 per cfm,
respectively.
Electric-Arc Furnace
Costs for the electric-arc furnace control are well documented by Barnes and
Lownie. (16) From their data for fabric filters (pages C-43 and V-20), capital costs
were estimated to be $343,900, and operating costs to be $195,000 per year.
BATTELLE MEMORIAL INSTITUTE - COLUMBUS LABORATORIES
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TABLE 8.
SUMMARY OF INDIVIDUAL AIR-POLLUTION-CONTROL COSTS
Gas Equipment Equipment
Flow Capital Operating
Rate, Temp, Pollution - Investment, Expense,
Industry acfm F Control Device dollars dollars/ year
Cement Plant 193,000 404 Electrostatic 745,000 206,000
Precipitator
Lime Plant 29,000 910 Fabric Filter 50,800 16,000
Sulfuric Acid 26, 500 154 Mist Eliminator 55,000 11,000
Power Plant 70,000 300 Wet Limestone 645,000 250,000
Fe rtilizer Plant 100,000 90 Wet Scrubber 210,000 99,800
Gray-Iron Foundry 49,600 500 Wet Scrubber 400,000 168,000
Electric-Arc 116,000 500 Fabric Filter 343,000 195,000
Furnace
Totals 583,000 2,449,000 946,000
Stack, Plant, and Labor
Stack Costs
Cost data for the stacks, which includes the column itself, the supports, and lin-
ings were taken from data given by Stankiewicz. (20) Installation was estimated to be
100 percent of the equipment cost; and as before, maintenance, depreciation, etc.,
expenses were taken to be 20 percent of the capital cost on a yearly basis.
As the discharges from the stacks should be relatively clean, it was felt that
200-foot stacks should suffice. Table 9 summarizes the data on stack costs.
TABLE 9. STACK-COST DATA
Operating
Stack Stack Capital Expense,
Diamete r, Velocity, Cost, dollars/
Plant ft ft/ se c dollar s year
Cement 10 41 121,800 24,400
Lime 5 25 77,800 14,600
Sulfuric acid 5 23 77,800 14,600
Powe r 5 60 77,800 14,600
Fertilizer 7.5 38 100,000 20,000
Gray il"on 5 43 77,800 14,600
Electric arc 7.5 44 100,000 20,000
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Plant Costs
Not included in the cost calculations, 50 far, are costs for plant, buildings,
services, etc. Lang has published average values by which the capital-cost estimate
should be increased to include buildings, piping, services, etc. (21) For solids- and
fluid-processing plants under $1 million (Table 8), an additional 75 percent is to be
added to the capital cost. These costs are detailed in the Summary Table (Table 14,
page 29).
Labor
Labor involved to run the individual pollution-control devices was estimated to re-
quire about 1/2 man, and to run the centralized facility, 2 men. Hourly rates were
assumed to be $4.50, which includes management charges. The labor costs appear in
the Summary Table (page 29).
At this point, the major capital and operating costs for pollution control of the
seven plants have been detailed. The following two sections are concerned with the
costs of the gas -transport system and the plant necessary to remove the pollutants from
the total mixed effluent gases from the seven plants.
GAS TRANSPORTATION SYSTEM TO
CENTRAL FACILITY
The detailed cost discussion that follows is divided into three sections - piping
costs, fan costs, and motor costs - to facilitate later use of the information in studies
of many different pipe/fan/prime mover combinations. A summary of assumptions used
appears at the end of this section.
In the study, it was assumed that all of the seven different types of industrial
plants considered were located at various equal distances from the central processing
plant. Costs involved for different distances over a range from I to 5 miles were esti-
mated. It was assumed that the central plant would eliminate polluting dirt and chemi"
cals, before expelling the collected air into the atmosphere.
A single pipe line from each industrial plant to the processing plant with no
branches was analyzed, for convenience; however, pipe networks might be used, if the
pollutants transported were compatible when mixed. Figure I is a schematic diagram
of the transportation system.
Three arrangements of fan locations relative to the processing plant were con-
sidered for analysis, but only one was selected. Two fan pressure levels were consid-
ered, the lower pressure level being for the shortest pipes.
The three arrangements of fan locations were as follows:
(I)
One fan located in each pipe at each industrial plant for blowing polluted
air through the pipe to the processing plant
BATTELLE MEMORIAL INSTITUTE - COLUMBUS LABORATORIES
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In
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r
In
3:
In
3:
o
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PRe - Pressure recorder
and controller
FP - From plant
~?
\
f:'p
I
Control device
plus fans
PRC
t
FP
FIGURE 1.
PLOT PLAN OF GAS TRANSPORT SYSTEM
--FP
~
'"
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(2) One fan located in each pipe just ahead of the
inducing polluted air through the pipe and for
through the processing plant
processing plant for
blowing polluted air
(3) Several large fans located after the processing
polluted air through the entire system.
plant for inducing
The last arrangement listed is recommended and is the only one analyzed herein.
The major advantage of placing the fans downstream of the processing plant is the re-
duction of fan costs realized by handling clean, low-temperature air. Erosion and
corrosion are reduced substantially by removing dirt particles and chemicals from the
polluted air before passing it through the fans; therefore, carbon steel rather than ex-
pensive alloys can be used for fan construction. The handling of low-temperature air
also eliminates the need for high-temperature-resistant alloys. The capacity require-
ment of each fan is reduced significantly at low temperature, since the air density is
relatively high. This reduces the size and, hence, the initial cost of the fans required
as well as the cost of power for operating the fans.
Another advantage of this arrangement is that the pressure in the piping is below
atmospheric; therefore, any small holes that might develop in the pipes would leak air
into them. If such leaks occurred in the positive-pressure system of the first arrange-
ment listed above, pollution of the atmosphere would result from the outflowing gases.
Minimum transport velocities were calculated for the particle loading of each
industrial plant. The minimum transport velocity, which occurs when particles no
longe r slide along the bottom of the pipe but are transported by saltation, has been
recommended by Thomas, et al. (22), as the optimum design velocity for suspension
transport. The particle size, particle specific gravity, and the minimum transport
velocity of the particle for each industrial plant are shown in Table 10. The air veloci-
ties of only two of the six plants having particle-laden air are sufficiently high to sus-
pend the particles. Since the air velocity was limited to 100 feet per second by erosion
considerations, particles of the sizes and weights assumed for the electric-steel fur-
nace, gray-iron foundry, lime plant, and cement plant will settle to the bottom of the
pipe. Whether these particles will slide along the bottom of the pipe or collect to block
the air flow is not known, but the problem does not appear to be insurmountable.
TABLE 10. MINIMUM TRANSPORT VELOCITY FOR POLLUTED AIR
Industrial Plant
Maximum
Expected
Panicle
Diameter,
microns
Particle
Specific
Gravity(a)
(Water = 1. 0)
Minimum
Transport
Velocity,
ft/see
Electric Power
Electric Steel Furnace
Gray-Iron Foundry
Lime
Sulfuric Acid
Cement
Fertilizer
150
100
100
150
50
60
L6 79.1
7.72 166.1
7.12 25L8
2.5 155.2
1.0 69.5
2.5 130.4
No Panicle Loading Assumed
(a) Mechanical Engineer's Handbook, edited by T. Baurnister, Sixth
Edition, McGraw-Hill, New York (1958).
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A periodic cleaning with a rotating plug, such as that used in the pipe-laying
industry, might be a workable solution to the problem. Another alternative might be
the installation of simple, low-efficiency dust collectors at each industrial plant. These
would be relatively inexpensive and would operate on less than 2 inches of water-gage
pressure loss.
Piping Cost Estimates
Cost estimates were made for piping for a range of distances from 1 to 5 miles
between the centralized processing plant and the circle containing the industrial
plants. (23 through 28) Piping costs for a given length are determined approximately by
the diameter and material. Figure 2 sho~s the variation of cost for several diameters
of carbon steel pipe. Costs vary linearly with distance and diameter. For example,
the cost of a 2 -mile -long pipe is twice that of a 1 -mile -long pipe and the cost of an
8-inch-diameter pipe is twice that of a 4-inch-diameter pipe of the same length and
material. Therefore, the cost of a 4-inch-diameter pipe 1 mile long was chosen as
the base value for computing all piping costs. The basic value, $30,000 per mile for
carbon steel pipe, for example, includes the cost of material, installation, and ease-
ment rights for land. Material costs include the cost of seamless pipe, coating material
around the pipe (no thermal insulation), cathodic protection, and one damper in each
line for flow control. Installation costs include surveying, mapping, field welds of
pipe, freight, sales taxe s, field-labor fringe benefits and statutory burdens, field
supervision, temporary facilities, equipment, tools, and contractor fees. Additional
details can be found in Appendix B.
It was assumed that the pipe would be buried underground. Methods of installing
the piping other than burying underground were considered, but a detaile~ economic
study was not carried out. These methods were to install the piping above streets or
buildings, install it in cradles just above ground, and laying it on the ground partially
exposed. These methods were rejected on the basis of thermal pollution, safety hazards
of hot exposed piping to personnel, appearance reasons, and vulnerability to sabotage
by pranksters. The degree of undesirability would depend considerably on location of
the installation, local codes, and community standard, habits, and acceptance.
Pipe costs for three materials are shown in Figure 3, for a given pipe size. Car-
bon steel (ASTM-A-53, Grade A) is recommended where temperatures are below 800 F
and where excessive corrosion is not a problem. Chrome-molybdenum steel
(ASTM A-335, Grade P12) is recommended at 800 F to 1000 F(29) which exceeds the
highest expected temperature of this study. Stainless steel (ASTM A-312, Type 316) is
recommended where special protection against corrosion is needed. (29, 30, 31, 32)
Other pipe materials such as plastics and concrete, were considered, but, generally,
temperatures were above the range of application of these materials.
The most economical pipe size is generally the smallest in diameter; however, as
the diameter is decreased, the air velocity in the pipe approaches certain limits. Two
limits on velocity were used herein. The upper velocity limit of 100 ft/sec(30) was
selected so that erosion, caused by dirt particles suspended in the air, will not be
"excessive". * A second limit is that the frictional pressure loss in the pipe must not
.Reference 30, Table 4, pp 18.8, shows the" Maximum Allowable Gas Velocity... to prevent flue dust erosion" for pulverized
coal of 100 ft/sec and cement dust of 45 ft/sec. This illustrates that more information concerning erosion is needed before a
final decision is made on the maximum velocity in an actual installation.
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1000 1000
24
800 20 800
600 16
en
0 4 .c
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c - . N
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III en N
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0 100
0 ... ...
r a. a.
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0 40
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en
2 3
Pipe Length, mi les
4
5
2 3 4
Pipe Length, miles
5
FIGURE 2. INSTALLED COST OF CARBON
STEEL PIPE
FIGURE 3.
COMPARISON OF INSTALLED PIPE COST
FOR THREE TYPES OF STEEL (FOUR-
INCH PIPE LINE)
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23
exceed the fan pressure rise. Two values for the maximum allowable pipe friction loss
were selected and these were 20 and 35 inches of water gage. The higher value is about
the highest practical value for centrifugal fans, considering that an additional 15 inches
of water was assumed to be dissipated across the treatment equipment. The lower
value of 20 inches of water was assumed for pipes about I mile long. U the higher value
were used for the shortest pipes, a costly pressure loss would occur across the dampers
in the pipes. For certain cases in relatively long pipes the air velocity exceeded
100 ft/sec for a certain pipe size; therefore, the next larger standard pipes were se-
lected. Since the flow areas of the next larger standard pipes increase considerably for
large pipes, the resulting pressure losses were below 20 inches of water, and these
pipes were listed in the lower pressure-loss system. It is acknowledged that, once a
system is selected, the pressure losses in all parts of the system must be compatible;
but, it is also acknowledged that in an actual system all industrial plants might not be
located the same distance from the centralized abatement plant as was assumed herein.
Tables II and 12 show the pipe material selected and the size and cost for a range
of lengths with pressure losses of 20 and 35 inches of water gage, respectively. Only
standard sizes of pipes were used. In Table 12 for the lime plant for the 4-mile
length, for example, if 36-inch-diameter pipe were used, the pressure loss would have
exceeded 35 inches of water gage. The next larger standard size of pipe is 42-inch
diameter. The calculated pressure loss for this size was below 20 inches of water
gage. If this pipe were installed in a system having 35 inches of water gage fan pres-
sure, the 15 inches of water gage difference must be dissipated across a damper.
Another alternative is to obtain specially manufactured pipe of the calculated diameter.
Whether this would offset the operating costs of using a damper is beyond the scope of
this report.
Finally, some consideration should be given to cooling of hot gas at the source
before it enters the pipe line. There may be problems involved in sending 500 F gas
through a buried pipeline because the ground temperature might eventually become
excessively high above the line. On the other hand, if gases containing 502 and water
are cooled below the dew point, 'which can be higher than 250 F depending on concen-
,tratian, sulfurous and sulfuric acid may be formed. This might require a change in
pipe material to stainless steel for corrosion resistance, and this would increase costs
substantially. Final deliberations on the maximum allowable pipe temperature must
take into consideration local codes, population density, and pipe location.
TABLE 11. PIPE COSTS FOR 20-INCH WATER-PRESSURE LOSS
Pipe Length
1 Mile 2 Mile 4 Mile 5 Mile
Cost, Cost, Cost, Cost,
Pipe Diameter, million D iamerer I million Diameter, million Diameter, million
Industrial Plant Material inches dollars inches dollars inches dollars inches dollars
Electric Power Carbon Steel 48 0.360 48 0.720
Electric Steel Furnace Carbon Steel 60 0.450
Gray-Iron Foundry Carbon Steel 42 0.315
Lime Carbon Steel 36 1.002 42 2.340
Sulfuric Acid 316 Stainless 36 0.671 48 4.470
Cement Carbon Steel 78 0.585 84 1.260
Fertilizer Carbon Steel 54 0.450
Totals 2.831 2.982 2.340 4.470
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TABLE 12. PIPE COSTS FOR 35-INCH WATER-PRESSURE LOSS
Pipe Length
1 Mile 2 Mile 3 Mile 4 Mile 5 Mile
Cost, Cost, Cost, Cost, Cost,
Ind usuia! Pipe Diameter, million Diameter, million Diameter, million Diameter, million Diameter, million
Plant Material inches dollars inches doHars inches dollars inches dollars inches dollars
Electric Carbon Steel 54 1. 215 60 1. 800 60 2.250
Power
Electric Carbon Steel 60 0.900 66 1. 485 66 1.980 72 2.700
Steel
Furnace
Gray-Iron Carbon Steel 42 0.630 48 1. 080 48 1.440 48 1.800
Foundry
Lime Carbon Steel 30 0.419 36 1. 503 42 2.925
Sulfuric 316 Stainless 36 1. 342 42 2.346 42 3.128
Acid
Cement Carbon Steel 78 1. 755 84 2.520 90 3.375
Fertilizer Carbon Steel 60 0.900 66 1. 485 72 2.160 72 2.700
Totals 0.419 3.772 10.869 13.028 15.750
Fan Cost Estimates
Centrifugal fans (33) are recommended for transporting the polluted air to the
processing plant. In sizing the fans, an additional pressure loss of 15 inches of water
gage was added to that of the piping to account for the loss within the centralized pro-
cessing plant. Therefore, the fan pressure rise was assumed to be either 35 or
50 inches of water gage. Fifty inches of water gage is near the limit of a simple, one-
stage centrifugal fan. The total quantity of air handled from the seven industrial plants
is 394,000 scfm (as calculated in Appendix C). Four fans of 110, OOO-scfm capacity each
were considered in the estimates, but this does not provide standby capacity, if one of
the blowers were shut down for maintenance.
The cost of four fans for 50 inches of water gage pressure is $252,000, and for
35 inches of water gage, $168,000. Each fan is a radial-blade, double-inlet centrifugal
design. These ~stimates include cost of fans, inlet ducting, and installation costs.
Costs of motors are shown separately below, since alternative prime movers might be
substituted.
Motor Cost Estimates
Motors for the fans having 50 inches of water gage are each 2,000 hp, 1,200-rpm,
2,300-volt, 3-phase, 60-cycle units of open-type construction. Open motors were
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25
selected, with a substantial cost reduction, on the assumption that the motors would be
protected from the weather. Transformers for reducing line voltage of 13,200 volts
to 2,300 volts are 2, OOO-kva capacity. Motor starters are included in the estimate.
The
$238,000.
estimated cost of four motors, frames, starters, and transformers is
This estimate includes costs of material and installation.
On-site power generation should be considered. With electric power one is paying
for transmission lines, power-generation apparatus, transformers, switchgear, and
electric motors. The motors are fixed-speed units and require either throttling for
flow control or variable-speed (fluidic) fan couplings. Use of on-site gas-turbine or
gas-engine fan drives would reduce considerably both the investment cost and the opera-
ting cost of the system. With direct drive from engines or turbines, fan speed could be
adjusted to match loads. In this regard, the fan power for the illustrative system, at
8,000-hp, would absorb about 1/4 of the power output of the 25, OOO-kw power plant in
the system.
Damper Cost Estimates
Dampers in each of the pipelines are necessary to maintain a constant pressure
drop in each of the pipes of the transportation system. As the effluent-gas rates are not
constant at all times, pressure controllers are included.
An estimate of the costs of the damper system was. made based on quotations by
Hayes who cited a cost of $4500 plus 500 installation for a 48-inch butterfly gas valve
made of carbon steel. (34) The following assumptions were made in calculating the re-
quired costs:
(1) Valve costs were proportional to the area of the pipe
(2) Installation costs were proportional to the diameter of pipe
(3) Valves made from alloy steels would be five times the cost of those
from carbon steel
(4) The pressure controller for each damper would cost $10,000.
Calculations for damper costs are shown in Appendix B. Capital costs were
estimated to be $141,000. Operating cost would consist only of maintenance, which is
usually relatively high for control devices. It was estimated at 5 percent of the capital
cost per year, that is $7,050 per year.
Operating Costs
Electricity and maintenance are the major operating costs, along with the 20 per-
cent financial charge. Using a value of $0.01 per kwhr for electric power, the cost of
running the four 2000-hp motors would be $523,000 per year.
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26
The cost of pipeline maintenance, i. e., service to cathodic protectors, occasional
cleaning, etc., and of motor service was roughly estimated at 1 percent of the capital
expenditures over a 10-year period, or $11,000 per year. Thus total operating expense
for a 3-mile distance was $523,000 + $11,000 + $7,000 + 20 percent of $11,500,000 =
$2,841,000.
Total Gas-Handling Cost Estimates
To obtain a total cost estimate for the gas-handling system, the pipe costs of
Tables II and 12 were added to the fan and motor cost, and the damper cost. These
costs have been plotted in Figure 4. The cost of the pipelines is about 90 percent of the
total cost of the gas-transportation system. Calculations are shown in Appendix B.
Summary of Major Assumptions
and Specifications
(I) All plants
facility.
are located equidistant from the centralized treatment
(2)
The treatment plant reduces particulate matter and corrosive gases
below a limit which would be harmful to the fans.
(3) The fans are located after the pollution-control device.
(4) The fans can develop 50 inches of water suction; 35 inches
the pipelines, and 15 inches across the control equipment.
through
(5)
Pipes are to be buried 4 to 5 feet underground in industrial locations .
(6)
The material of construction for the pipelines is carbon steel, except
for the lime plant and sulfuric acid plant which utilize molychrome
and 316 stainless, respectively.
EMISSION CONTROL FOR TOTAL GAS STREAM
This section deals with the central treatment plant, whose function is to treat the
mixed effluents from the seven individual plants in one large control device.
Control Device
The compositions of the mixture of gas streams from the seven plants is shown
in Table 13. Calculations for this table are shown in Appendix C. It can be seen that
the gas stream contains various compounds which will react with each other, mainly
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4
2
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2B
acidic compounds such as 502, sulfuric acid, and C02, and basic constituents from the
cement and lime plants. Bya consideration of the free energy changes accompanying
the various reactions (shown in Appendix C), it was shown that the most favored reaction
would be the reaction of lime and SOZ. However, the level of various reactive acidic
components in the gas after mixing would depend on factors such as (I) the amount of
lime present for reaction, (2) temperature of the gas, (3) reactivity with cement, and
(4) residence time of the reactants.
Thus, it is impossible to give concentration levels of 502, sulfuric acid, and the
fluorides after the gases are mixed. In the present case, there would not be enough
CaD in the emissions to remove the acidic pollutants entirely, necessitating their re-
moval by the control device. It is felt that since sulfuric acid, the fluorides, and S02
are relatively soluble in water, and react easily in an aqueous system, a wet-scrubbing
device would give reasonable control. The water used in the wet scrubber should have
lime dissolved in it in order to form CaS04 and CaF2' These two compounds, because
of their low solubility in water, could be removed by precipitation and filtration, along
with the dust emissions.
TABLE 13.
MIXED GAS COMPOSITION
Variable
Before Afte r
Scrubbing Scrubbing
627 530
320 240
2.7 <.01
Gas Flow, 1000 acfm
Gas Tempe rature, F
Particulate Loading, gr/ft3
Gas Composition, volume percent
Fluorides
69.3 67.0
9.2 B.B
10.4 10.0
10.7 13.2
.04
I. 1 1.0
Trace
Trace
N2
°2
C02
H20
S02
CO
H2S04
Cnst Considerations
Chemical Construction Corporation supplied necessary information on types of
wet scrubbers that would be suitable for handling the emissions encountered. (12) They
felt that a high-energy venturi scrubber would accomplish the desired degree of control,
and they had recent data on a scrubber installation for a power plant.
BATTELLE MEMORIAL INSTITUTE - COLUMBUS LABORATORIES
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29
The scrubber for that power plant cost $750,000, including installation, and it
handled 420,000 cfm at 420 F. Since this was one of the largest they manufactured,
costs for this study were scaled up on a cfm basis, making the capital cost of the
scrubber for the emissions in the present case equal to
627,000 880
420 000 x 780 x $750,000 =
,
$1. 27 million.
Unfortunately, no operating cost data were available. To estimate these costs,
the results of Sargent( 17) were scaled up to the present case, the cost of lime necessary
to remove 50 percent of the acid gas pollutants (the rest assumed to react with the lime-
plant emissions) was added. Lime cost used was $15.50 per ton (Oil, Paint and Drug
Reporter, December, 1969). Detailed cost calculations can be found in Appendix B.
DISCUSSION
A detailed cost summary is shown in Table 14. Total cost of pollution control on
an individual basis is about $5.4 million capital, and $1. 7 million annual operating. In
comparison, the costs for centralized control (3-mile radius) would be $14.0 million
capital and $3.6 million annual operating.
TABLE 14. COST SUMMARY
Equipment Stack Buildings. etc. Total
Operating, Operating. Operating. Labor, Total Operating,
Capital, dollars/ Capital, dOllars/ Capital, dollars/ dollars/ Capital, dOllars/
Plant dollars year dollars year dollars year year dollars year
Cement 745, 000 206,000 121.800 24.400 651,000 130,200 19,700 1,517,800 380,300
Lime 50,800 16,000 77,800 14,600 97,000 19,400 19,700 225,600 69,700
Sulfuric 55,000 11,000 77,800 14,600 101,000 20,200 19,700 233,800 65, 500
Acid
Power 645,000 250,000 77,800 14,600 542,000 108,400 19,700 1,264,800 392,700
Fen ilizer 210,000 99,800 100,000 20,000 233,000 46,600 19,700 543,000 186, 100
Gray~rron 400, 000 168,000 77,800 14,600 358,000 71,600 19, 700 835,800 273,900
Electric 343,000 195,000 100,000 20,000 332,000 66,400 19,700 775,000 301, 100
Arc
Total 2,448,800 945,800 633,000 122,800 2,314,000 462,800 137, 900 5, 395, 800 1,669,300
Centralized 1,270,000 539,000 177,000 35,400 1,083,000 216,600 78,800 2,530,000 869,800
Control
Gas 11,500,000 2,841,000 11,500,000 2,841,000
Transport
(3 miles)
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30
It is noteworthy that the premise of one large treatment plant being m.ore econom.i-
cal than several smaller treatment plants is verified; the central pollution-control plant
costs $2.5 million in comparison to a $5.4 million cost for individual control facilities.
However, the cost of transporting the effluents to the centralized plant is very high;
being $11. 5 million for the 3-mile radius. As the transportation cost is a function of
distance, the difference between the cost of centralized and individual pollution control
can be plotted versus distance of the plants from the treatment facility to determine a
"break-even" point. Figure 5 shows that if the individual plants were located about
1/2 mile from the centralized treatment facility, it would appear more economical to
treat the gase s in the central plant.
Before drawing definite conclusions, however, it is important to consider
factors that have a bearing on the feasibility of the centralized concept.
several
(1)
The cost of waste disposal was not estimated as part of the economics
because the disposal cost is a function of many variables, most of which
can only be guessed. However, valid observations about the effect of
waste disposal on the economics of the centralized concept can be made
if one assumes that the disposal cost per ton of material is the same for
both the centralized plant and the individual plants. This assumption is
not unreasonable because the major variables affecting this cost, such
as location, labor costs, proximity of disposal facilities and type of
waste, should be the same in both cases.
If none of the effluents have any value to the individual plants, that is,
the effluents cannot be recycled or sold as product, then the disposal
costs should not influence the economics significantly because approxi-
mately the same amount will have to be disposed of in both the central-
ized facility and in the individual plants. However, in general, this is
not the case. The sulfuric acid mist can be collected as a saleable
product if individual control we re used. For the case of centralized
control, mixing of the effluents from the seven plants would render the
sulfuric acid valueless because of its reaction with the lime either from
the lime plant emissions or in the scrubber. For the sulfuric acid
plant used in this study, H2S04 emissions amount to about $25,000 per
year (H2S04 at $25/ton).
The only other emissions which may be of value are those from the
lime and cement plants. For the value of these emissions to be
realized, however, they must be returned to the kiln, a practice which
is not in general use at the present time because of the complexities
involved.
(2)
Burial of the hot plpes would result in localized heating of the ground
above the pipe s. This would probably eliminate any vegetation in this
area. This may be undesirable from an esthetic viewpoint and would
increase run-off somewhat.
(3)
A malfunction in the centralized pollution-control facility could cause
serious problems. If the operation of the scrubber were to be discon-
tinued for repair, a relatively large amount of pollutants would be
BATTELLE MEMORIAL INSTITUTE - COLUMBUS LABORATORIES
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31
10 /
VI 8
~
0
0 ~ 0
-0 ' -0
,
- " -
o " 0
VI 6 Capital cost ,," VI
C " c
o d i f ference " 0
E ~"".,,, E
C1> " C1>
U ..." U
c 4 Operating cost c
C1> .!! 1.0 C1>
~ difference ~
C1> C1>
- -
- -
o 0
c;; -
VI
o 0
u 2 u
o '"
- c
a. -
o 0
U ~
C1>
a.
o
o 0
o
0.5
2
3
Distance of Plants From Centralized Facility, miles
FIGURE 5. EFFECT OF DISTANCE ON COST DIFFERENCE BETWEEN
CENTRALIZED AND INDIVIDUAL CONTROL ABATEMENT
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32
released over a small area. This situation could possibly cause
serious temporary problems; whereas, in the case of individual
control, the chance of all seven pollution devices malfunctioning
at the same time is very remote. Problems of this nature could be
alleviated somewhat by utilizing two scrubbers in parallel, each
handling one-half of the effluents, at an increase in cost.
(4)
If a malfunction occurred in the transportation system, i. e., failure
of the pipeline or fans, it would be necessary to vent the emissions
elsewhere. This situation might be impossible for a given plant.
Therefore, some extra capacity in the transportation system would
probably have to be provided; for example, an extra line and extra
fans. To provide for this contingency, additional expense would be
involved.
Some information pertinent to this study was obtained from Brink( 18) during dis-
cussion of the demister control units. He stated that Monsanto had done a centralized
air-pollution study for one of their own plant complexes similar to the one presented in
this report. On the basis of results of their study, Monsanto rejected the centralized
concept as being both too expensive and presenting too many technical difficulties. It
is interesting to note that the major factor that determined the cost of centralized treat-
ment in the Monsanto study was also the cost of gas transportation.
CONCLUSIONS
On the basis of this study of a centralized-air-pollution-abatement concept, it is
concluded that the centralized concept is not economically feasible, mainly because the
cost of transporting the gas to the centralized facility is so high that the individual
plants would have to be less than about 1/2 mile from the central treatment plant for any
economic gain over individual treatment to be realized. From a practical standpoint,
it would be difficult to envision seven plants so close together because of their individual
land requirements.
Considerations of waste disposal, natural esthetics, and potential emergency prob-
lems associated with the failure of the centralized equipment all tend to reduce the
attractiveness of the concept further.
REFERENCES
(I) Kreichelt, T. E., Kemnitz, D. A., and Cuffe, S. T., Atmospheric Emissions
From the Manufacture of Portland Cement, Environmental Health Series, PHS
Publication No. 999 -AP-I 7, Cincinnati, Ohio (1967).
(2)
Lewis,
Dust",
C. J., and Crocker, B. B., "The Lime Industry's
J. Air Pollution Control Assoc., .!1 (1), 31 (1969).
Problem of Airborne
BATTELLE MEMORIAL INSTITUTE - COLUMBUS LABORATORIES
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33
(3) Stuart, H. H., and Bailey, R.
Scrubber Installation", Tappi,
E., TlPerformance Study
48 (5), 104A (1965).
of a Lime Kiln and
(4)
Bergstrom, J., et al., "Panel Probes
ucts", p 76 (January, 1965).
Dust Collection Problems", "Rock Prod-
(5)
Cuffe, S. T., and Dean, C. N., Atmospheric Emissions From Sulfuric Acid Manu-
facturing Processes, Environmental Health Series, PHS Publication No. 999-AP-
13, Cincinnati, Ohio (1965).
(6) Brink, J. A., Jr., Burggrabe, W. F., and Greenwell,
for Sulfuric Acid Plants", CEP, 64 (ll), 8Z (1968).
L. E., "Mist Eliminators
(7)
Brink, J.
J. Chem.
A., Jr., "Air Pollution
Eng., ~, 134 (1963).
Control With Fibre Mist Eliminators", Can.
(8) Katell, S., "Removing
(10), 67 (1966).
Sulfur Dioxide From Flue Gases", Chem Eng. Prog., 6Z
(9)
Lemmon, A. W., Jr., Fletcher, B. L., Schuler, R. E., and Carlton, H. E.,
"A Cost-Utilization Model for SOZ-Control Processes Applied to New, Large
Power-Generation Facilities", Summary Report from Battelle Memorial Institute
to National Air Pollution Control Administration (January 17, 1969).
(10) Engdahl, R. B., and Sachsel, G. F., "Solving Air Pollution Problems in
lizer Production", Farm Chemicals (January, 1960).
Ferti-
(II) Huffstutler, K. K., "Sources and Quantities of Fluorides Evolved From the Manu-
facture of Fertilizer and Related Products", paper presented at the Air Pollution
Control Association Annual Meeting, San Francisco, California (June ZO, 1966).
(lZ)
( 13)
(14)
Chemical Construction Corp., Private Communication with Mr.
Industry Sales Manager, Pollution Control Division, New York.
W. Ellison,
The Cupola and Its Operation, American Foundrymen's Society (1965).
Bloomfield, B. D.,
Modern Casting, 67
"The Foundry - And Air
(October, 1967).
Pollution Control Legislation",
(IS) Sterling, M., "Current Status and Future
Control", paper presented at the National
(December lZ, 1966).
(16)
Prospects - Foundry Air Pollution
Conference on Air Pollution
Barnes, T, M., and Lownie, H. W., Jr., "A Cost Analysis of Air-Pollution Con-
trols in the Integrated Iron and Steel Industry", Final Technological Report to
Division of Economic Effects Research, National Air Pollution Control Adminis-
tration, Department of Health, Education, and Welfare from Battelle Memorial
Institute (May IS, 19'69).
(17) Sargent, G. D., "Dust Collection Equipment", Chern. Eng., 76 (Z), 130 (1969).
( 18)
Brink, J. A., Jr., Private Communication, Monsanto Co.
BATTELLE MEMORIAL INSTITUTE - COLUMBUS LABORATORIES
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34
(19) Schuler, R. E., Cherry, R. H., Jr., Testin, R. F., and Lemmon, A. W., Jr.,
"Estimated Cost Impact of Sulfur Dioxide Air-Pollution Regulations as Related to
The Ohio Electric Utility Industry", Research Report to Ohio Electric Companies
from Battelle Memorial Institute (May 15, 1969).
(20) Cost Engineering in the Process Industries, Edited by C. H. Chilton and the Sta££
of Chemical Engineering, McGraw-Hill Book Company, Inc., New York (1960),
"How to Estimate Stack Costs" (E. J. Stankiewicz), pp 253-58.
(21) Ibid, "Cost Relationships in Preliminary Cost Estimation" (H. J. Lang), pp 7-11.
(22) Thomas, D. G., "Transport Characteristics
J., ~ (3), pp 303-308 (1964).
of Suspensions: Part IX", A.!. Ch. E.
(23) White, J. E., "Economics of Large Diameter Liquid Pipelines", Pipe Line News,
pp 14-18 (June, 1969).
(24) "Pipeline Industry World-Wide Construction Scoreboard", Pipe Line Industry,
pp 69-74 (June, 1969).
(25) Guthrie, K., "Costs", Chemical Engineering, Deskbook Issue, pp 201-216
(April 14, 1969).
(26) Stark, V., and Wastie, A., "LNG for
Industry, pp 57-60 (January, 1969).
Peak vs Base Load Applications", Pipe Line
(27) O'Connor, L. J., "What O££shore Pipe Lines Cost", Pipe Line Industry, pp 35-37
(August, 1969).
(28) Meckler, M., "Air Handling Equipment for Contamination Control",
tioning, Heating, and Ventilating, pp 37-40 (July, 1968).
Air Condi-
(29) Steam, The Babcock and Wilcox Company, 37th Edition, New York (1955), Chap-
ter 22, p 35.
(30) Steam, ibid, Chapter 8, pp II and 24 and Chapter 18, pp 6-8.
(31) Pray, H. A., et aI., "Literature Review on Corrosion of Metals and Materials
by Flue Gas Condensate", Report No. I from Battelle Memorial Institute to
A. G. A. (February, 1947).
(32) Archer, R. A., et aI., Molybdenum Steels, Irons, Alloys, 2nd Printing, Climax
Molybdenum Co., New York (1953), p 135.
(33) Pare, Paul and Wilson, American Standard, private communications September 9,
1969, and October 14, 1969.
(34) Hayes, D. N., Private Communication, Chemical Plant Equipment, Inc.,
Columbus, Ohio.
(35) Shreve, R. N.,
Book Company,
The Chemical Process Industries, Second Edition, McGraw-Hill
Inc., New York (1956), Chapter 11.
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APPENDIX A
GAS COMPOSITIONS
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A-I
APPENDIX A
GAS COMPOSITIONS
Cement Plant Calculations
Gas Composition
Usual ratio of CaC03 to coal is 4 to 1. (35) Reactions are
C + 0z - COZ
(1 )
CaC03 - COZ + CaO
(Z)
Assume 10 percent excess air:
oxygen required per Ib of C [Equation (1)]
3Z
= 12 x 1. 1 = Z. 94 lb 0z = 0.0918 moles 0z
0.0918
Therefore, nitrogen = O. Zl x 0.79 = 0.345 moles NZ
oxygen in stack
= O. 1 x 0.0918 = 0.00918 moles 0z
and carbon dioxide:
44
From Equation (1): = 12 = 3.67 Ib
44
From Equation (Z): = 80 x 4 = Z. ZO Ib
Total COZ
= 5.87 lb or 0.133 moles COZ
On a dry basis:
COZ O. 133 = 28 percent
=
0.478
0z 0.00918 1. 9 percent
= =
0.478
N2 0.345 = 70 percent
=
0.478
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A-Z
On a wet basis:
From Kreichelt(l), water content = 31 percent
COZ = 0.69 x Z8 = 19.5 percent
NZ = 0.69 x 70 = 48. Z percent
Lime Plant Calculations
Gas Composition
From Lewis and Crocker(Z), COZ = 31.8 percent for a 4: I lime-to-fuel ratio.
C + Oz - COZ
(3)
CaC03 - COZ + CaO
(4)
On a basis of I Ib of C and 4 Ib of CaO:
moles of COZ from Equation (3) = 0.0833
moles of COZ from Equation (4) = O. IIII
Total = O. 1943
0.1943
Thus, other constituents = 0.318 x O. 68Z = 0.416 moles
Asswne 10 percent excess air, then
Oz = O. 0833 x I. I
= 0.0916 moles
Oz in stack
= 0.0083 moles
0.0916
NZ = O. ZI x 0.79 = 0.345 moles
moles of water and 80Z = 0.416 - 0.353 = 0.063 moles
assume 80Z = O. I percent = 0.001 x (0.416 + o. 194)
= O. 0006 moles.
Thus, water = o. 06Z moles
NZ = 0.345/0.610 = 56.5
COZ
0z = 0.008/.610 =
= 31.8
1.4
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A-3
H20 = 0.062/.610 = 10.3
S02
= 0.1
Sulfuric Acid Plant Calculations
Exit-Gas Composition
is
From Cuffe and Dean(5), the average S02 concentration entering the converter
8.3 percent, and S02 in stack is 0.26 percent.
S + 02 - S02
To calculate gases input (basis 1 mole of S): Let x = moles of excess 02 input.
input 02
= 1 + x
input N2
= (1 + x) 0.79/0.21
output 02
=x
output S02 = 1
Total moles entering converter = (1 + x) 0.79/0.21 + 1 + x
=4.76+4.76x
1
Solving: 4. ,76 + 4. 76x = 0.083
x = 1. 52 moles of 02 excess
To calculate S02 in stack; the moles of gases for the stack are as follows:
N2 = 9.45
°2 =
1. 52
x
S02 = 10.97 + x .
Know that x/(lO. 97 + x) = 0.0026.
Thus, x = 0.0029.
N2 = 9.45/11 = 85.8 percent
02 = 1. 52/11 = 13. 8 percent
S02 =
0.26 percent
S03 =
0.03 percent
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A-4
Gray-Iron Foundry Calculations
The calculated example in Reference (13), pages Z9Z-Z96, was used as a basis for
gaseous compositions. This reference gives weight of emissions for a melting rate of
Z1. 91 tons of iron changed per hour. The gas rates are given in lb/hr at 850 F.
COZ = 6,780 lb/hr = 154 moles/hr
CO
= 4,370 lb/hr = 153 moles/hr
NZ = Z4, 500 lb/hr = 875 moles/hr
HZ = Z6. 3 lb/hr
=
13. Z moles/hr
To recover some of the sensible heat from the stack gases, a widely used and
successful method is the Griffin system. Also in this system, provision is made for
introducing air, which burns the CO to COZ' and the HZ to HZO, and recovers the heat
of combustion. It will be assumed that this system will be used. The reactions are:
CO + l/Z 0z = COZ
HZ + l/Z 0z =HZO
Moles of 0z required = l/Z (153 + 13. Z) = 83.1 moles/hr.
Assuming 10 percent excess air, oxygen leaving stack = 8. 31 moles/hr.
NZ = 875 + 79/Z1 (91.4) = lZ19 moles/hr.
COZ = 154 + 153 = 307 moles/hr.
The temperature leaving the heating chamber in the Griffin system is about 500 F.
359 960
Therefore, to convert from moles/hr to acfm, the factor 49Z x "(;0 = 11. 65 is used.
NZ = lZ19
moles/hr = 14, ZOO acfm
COZ =
307
mole s /hr =
3,580 acfm
°z =
8.3 moles/hr =
100 acfm
HZO =
Z6.3 moles/hr =
300 acfm
Total = 18,180 acfm
From these numbers, stack-gas composition is easily calculated.
An average cupola operation appears to utilize three cupolas, melting 60 tons of
iron per hour. Therefore, emissions would be
18,180 x 60/Z1. 91 = 49,600 acfm
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A-5 and A-6
Electric Furnace
For the electric furnace, both CO and COZ are produced in the reaction of the
carbon electrodes with air. Information necessary for the calculation of the composi-
tion of the stack gases was obtained ftom Barnes and Lownie(16).
The two reactions occurring are:
C + l/Z 0z - CO
CO + l/Z 0z -COZ
(5)
(6)
The following assumptions were made: (I) Equation (5) takes place with
stoichiometric amount of 0Z' (Z) Equation (6) takes place with 500 percent
excess air, (3) the final COZ/CO ratio is 5.
Basis:
I mole of C
Let x = number of moles of CO reacted in Equation (6).
Then, since 1 mole of CO is produced by Equation (I), there will be (I-x) moles of
CO in the exit gas stream.
Thus.,
x/.( I-x)
= 5 and x
= 5/6.
Oz inlet
=
0.5+ I/Z (5/6) x 5 = Z. 58 moles
0z used up = 0.5 + (1/Z) (5/6)
= o. 9Z moles
0z in stack = Z. 58 - 0.9Z
= 1.66
NZ in stack = (Z. 58 x 79)/ZI
= 9.7
COZ in stack
= 0.833
CO in stack
= o. 166
From these results, the gas composition follows readily.
BATTELLE MEMORIAL INSTITUTE - COLUMBUS LABORATORIES
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APPENDIX B
COST CALCULATIONS
BATTELLE MEMORIAL INSTITUTE - COLUMBUS LABORATORIES
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B-1
APPENDIX B
COST CALCULATIONS
Cement Plant
Electrostatic precipitator efficiencies for various particLe sizes are given by
Sargent(17) (Table V), and approximate screen analysis of the cement dust by Krelchelt,
et al. (1). Total efficiency calculations are tabulated below:
Particle Size,
microns
Amount
Present,
weight percent
Precipitator
Efficiency,
percent
Dust
Collected,
percent of total
2.5
5
10
20
30
40
50-60
22.5
7.5
12.5
17.5
20.0
10.0
10.0
77.0
90.5
95.0
96.0
96.5
96.8
97.7
17.3
6.8
11. 9
16.8
19.8
9.7
9.8
91. 6
Total
Data from Barnes and Lownie(16) indicate that about a 10 percent increase in
capital and operating costs is necessary to decrease the outlet dust loading by 2.5 times.
The amount of decrease necessary for the present case would be
(l - 0.916) x 5.4 = 9.14
0.05
Thus, since (2.5)2.4
2.4 x 10 = 24 percent.
=
9.14, the percentage increase in cost required would be
Size Considerations
The data in Sargent show a cost of the electrostatic precipitator to be $233,000 for
a gas flow rate of 60,000 cfm at 68 F. At this temperature, the flow rate of cement-
plant emissions would be 193,000 x 528/864 = 118,000 cfm.
To scale up the cost data of Sargent, use the relationship
Costl = [ flowl ]m
Cost2 flow2
The index "m" was calculated to be 0.7 from data of Barnes and Lownie (page C-42).
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B-2
The cost of a
118, OOO-dm unit would be
[118 000]0.7
233,000 x 60; 000 = $375,000
Addition of the 24 percent for the required efficiency increase, and adjustment of cost to
1969 levels would result in a capital investment of $490, 000.
Yearly operating costs would corne to about
1.24 x
[118, 000]' ,
($2,000 + $1,300) x 60, OOOJ+ 20% of $490, 000
= $8,000 + $98,000 = $106,000
Costs for electrostatic precipitation have been reported by Barnes and Lownie and can
be calculated for this case:
Capital
[193000960]0.7
Cost = $905,000 x 185',000 x 864
= $1,000,000
Similarily, yearly operation costs = $306,000
Averaging the two costs from Sargent and Barnes and Lownie gives
Capital cost = $745,000
Operating cost = $206, OOO/year
Fertilizer Plant
Barnes and Lownie(16) report costs of a low-energy venturi-type wet scrubber,
handling 55,000 dm at 70 F, to be $179,000 and operating costs to be about $75, 000
yearly (Page C-26). To scale these prices to the fertilizer flow rates (100,000 dm at
90 F), it was assumed that the cost index was 0.7.
Thus, control cost for the fertilizer plant would be
[100, 000 530] O. 7
$179,000 x 55,000 x 550 = $265,000
The operating costs were assumed to be proportional to the volum~- of gases
treated, with the exception of the 20 percent capital charges. Therefore, operating cost
per year for the fertilizer -plant control would be
100,000 x 530 ($22,000 + $7,000 + $10,000) + 20% of $265, 000
55,000 550
= $63,000 + 52,400 = $115, 400/year
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B-3
In a similar manner, costs for the treatment of fertilizer-plant gas
lated from the data of Sargent( 17) (Table VI),
[ 100 000 528] O. 7
Capital cost = 107,000 xl, 05 x 60,000 x 550
can be calcu-
= $155,000
100, 000 528
Operating cost = 60,000 x 550 x ($12, 100 + $1,000 + $18,000) x 1. 05
+ 20% of $155,000
= $53,200 + $31,000 = $84, 200/year
The estimate of costs was obtained by averaging the costs from both sources,
Capital cost = ($265,000 + $155,000)/2 = $210,000
Operating cost = ($115,400 + $84, 200)/2 = $99, 800/year
Dampers
The table below details the cost calculations for the dampers required. This table
is based on a cost of $4500 for a carbon steel valve of 48-inch diameter, plus $500 in-
stallation charge.
Pipe Diameter, Valve Cost, Installation,
Plant inches dollars dollars
Cement 78 11,600 800
Lime 36 12,700 370
Sulfuric Acid 42 17,200 430
Power 54 5,700 560
Fertilizer 60 7,000 625
Gray-Iron 48 4,500 500
Electric Furnace 66 8, 500 690
Totals 67,200 3,985
Assuming $10, 000 for pressure controllers for each pipeline, total capital cost
would be
$ 67,200 + $3985 + 7 x $10, 000 = $141,000
Operating cost = 5 percent of $141, 000 + 20 percent of $141, 000 = $35, 300/year
BATTEL.L.E MEMORIAL. INSTITUTE - COL.UMBUS LABORATORIES
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B-4
Scrubber Operating Costs
Data of Sargent(17) can be scaled up as follows:
Cost =
627, 000 x 528 ($18 820 + $12 100 + $1 000)
60 000 780 x, , . ,
,
= $225, OOO/year
The cos t of the lime required is:
.527 56 x 60 x 24 x 365
2 x 2000 x$15.50=$60,000/year
Operating cost of high-energy wet scrubber =
$225, 000 + $60,000 + .20 x $1, 270, 000 = $539, OOO/year
Total Gas Handling
3 -Mile Dis tance
Capital cost = pipeline cost + fan cost +
motor cost + damper cost
= $10, 869, 000 + $252, 000 + $238, 000
+ $141, 000
= $11,500, 000
Operating cost consisted of electricity,
the 20 percent of capital investment.
pipeline and damper maintenance plus
Operating
cost = $523, 000 + $11, 000 + $7, 000 + 200/0 of $11,500, 000
= $2, 841, DaD/year
2-Mile Distance
It was assumed that the same size pipes, fans, motor, and dampers would be used
in this case as for the 3 -mile case.
Thus,
Capital cos t =
2/3 x $10, 869, 000 + $252, 000
+ $238, 000 + $141, 000
= $7,881, 000
BATTEL.L.E MEMORIAL. INSTITUTE - COL.UMBUS L.ABORATORIES
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B-5
Operating
cost = $523,000 + $11, 000 + $7,000
+ 200;. of $7, 881, 000
= $2, 114, OOO/year
I-Mile Dis tance
Pipeline cost (Table II) = $2, 831, 000 + $1,002,000/2
= $3, 332, 000
Fan Cost = $168, 000
Motor Cost = $119,000
Damper Cost = $100,000
Total Capital Cost = $3,700,000
Operating costs:
Electricity = $523,000 x 35/50 = $367,000
Pipeline maintenance = O. I percent of $3, 833, 000
= $3, 800
Damper maintenance = $5,000
Total operating costs = $376,000 + 20 percent of $3.7 million
= $1, 116, OOO/year
1/2-Mile Distance
Again, it was assumed that the same size pipes, etc., would be used in this case,
as for the I-mile case.
Capital cost = 1/2 x $3, 833, 000 + $168,000
+ $119,000 + 100,000
= $2,293,000
Operating cost = $376,000 + 20 percent of $2, 293, 000
= $834, 600/year
Figure 5 shows the difference between the costs of centralized pollution control
and individual control. For example, for a 3 -mile distance, centralized control
would cost
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B-6
$11,500 + $2, 530,000 = $14,030,000 capital
and
$2,841,000 + $869,000 = $3,710, OOO/year operating
The difference would be
$14,030,000 - $5,396,000 = $8, 634, 000 capital
and
$3,710,000 - $1, 669,000 = $2,041,000 operating.
Pipe Line
O'Connor(27) shows the cost per mile of a 26-inch-diameter pipe is $195,000 for
laying pipe in U. S. Gulf Coast marsh land where costs can be expected to be higher than
normal. This is about $30, 000 per mile for 4-inch-diameter pi&e assuming a linear
relationship between cost and pipe diameter. Pipeline Industry 4) shows an extensive
amount of pipe cost data. Reducing these data on the same basis, using only pipe costs
with no substations, the cost per mile of 4-inch-diameter pipe is about $26, 000 to
$30,000 and the relationship between pipe cost and diameter up to 42 inches in diameter
is nearly linear. Stark(26) shows curves for 4, 6, and 8-inch diameter pipe. The
4-inch-diameter pipe cost is $26,400 per mile and a nearly linear relationship between
cost and diameter is shown. These references do not break the pipe costs into separate
items, but they do discuss a few variables which can vary the cost.
Guthrie(25) shows a detailed cost breakdown, but costs are nearly double those
shown above and were not used directly. These costs were high for several reasons.
One reason is that they are estimates rather than actual costs, and Guthrie admits that
these cost estimates can decrease by as much as 40 percent under competitive bidding.
Another reason is that these estimates were for short lengths of line such as those run
in an industrial plant rather than cross country.
Based on these data it was believed that the installed cost of $30, 000 per mile
represents a reasonable estimate for laying several miles of pipe.
White(23) shows a somewhat detailed cost breakdown for laying eight sizes of pipe.
Costs per foot of 32-inch-diameter pipe shown by White were divided by eight to obtain
costs on the basis of a 4-inch-diameter pipe and multiplied by 5280 ft/mile to obtain the
costs shown below:
Estimated Cost of Installed 4-Inch-Diameter Pipe
Cost per Mile
Item -
Pipe, Grade X-52, 0.312-inchwall
Coa ting mate rial
Cathodic protection ($0. 02/ft, regardless
- of pipe size)
$7,410
376
106
Total pipe material cost
$ 7, 892
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B-7
Total construction and closely
allied services
$ 264
2,400
340
4, 650
Surveying, mapping, pipe X-ray (0. 05/ft)
Damages
Freight
Construction
$ 7, 654
Total material and construction
$15,546
Subtracting this cost from the assumed $30, 000 per mile cost, the remaining cost of
$14,454 includes land easement rights, overhead, etc., not included in the above
tabulation. .
Another estimate was made using formulas shown by Guthrie and on the basis of
costs by White, since it is believed that material costs by Guthrie might be excessively
high for the air pollution abatement application. This estimate is as follows:
Item
Cost per Mile, dollars
Total pipe material costs, including X-ray
Indirect costs - 1.34 x material cost
Breakdown of 1.34 factor:
8, 156
10,920
Item
Percent of Material Costs
Material
Engineering(a)
Direct labor
Construction Overhead(b)
Sales tax
Freight
Total material and O. H.
100.0
14.8
78.0
38.4
3.0
5.0
239.2
Total material + Overhead
Material + Direct Labor
=
239.2 = 1.34
178.0
Contingency (10 percent of 19,076)
19,076
1, 908
$20,984
(a)
This cost includes direct engineering costs - pipe-circuit analysis, analytical
engineering, plot plans - and indirect office costs, burden and overhead,
and contractor fees.
(b)
This cost is 49.2 percent of direct labor which equals 38.4 percent
of material and includes field labor benefits and statutory burdens,
field supervision, some average rigging, equipment rental, small
tools, etc.
A detailed cost of land and associated costs were not available, but approximately
$9,000 per mile for the basic 4-inch-diameter pipe was used in the estimate reported.
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B-8
Obviously, if land need not be purchased or leased, the installed pipe
crease by about one -third of the former estimate of $30, 000 per mile
diameter pipe.
cas t might de-
for 4-inch-
Sulfuric Acid
Figure B-1 shows cost versus cubic feet per minute for demisters of two
efficiencies.
BATTELLE MEMORIAL INSTITUTE - COLUMBUS LABORATORIES
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APPENDIX C
TOTAL GAS STREAM CALCULATIONS
BATTELLE MEMORIAL INSTITUTE - COLUMBUS LABORATORIES
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C-l
APPENDIX C
TOTAL GAS STREAM CALCULATIONS
Gaseous Composition
The amounts of various constituents for the mixed streams of gases are shown in
Table C-l. From the totals, gas compositions of the mixed stream can be calculated.
TABLE C-1. GAS FLOW RATES FOR INDIVIDUAL PROCESSES
Gas flow. Temp, Component, moles/minute Panicle,
Process 1000 acfm F N2 02 CO2 H20 S02 Ib/min Other
Cement 193.0 404 148 4.0 59.8 95.0 149
Lime 29.0 910 17.1 0.4 9.7 3.1 0.0303 24.9
Sulfuric Acid 26.5 154 50.6 8.2 0.1535 Acid, 0.491b/min
Pow~r 70.0 300 96.4 4.4 18.0 7.6 0.253 15.0
Fenilizer 100 90 196 52 SiF4 and HF
2.11b/min
Gray Iron 496 500 55.3 0.3 13.9 1.2 14.2
Electric Arc 116.0 500 130.0 22.3 2.2 41.4 CO, 11.1 mole/min
Totals 693.4 91.6 103.6 106.9 0.437 244.5 CO, 11.1
Reaction Calculations
The gaseous emissions from the seven plants contain various acid gases and basic
solids which can react together. Some reactions that may occur (along with the standard
free energy change, £IF") are as follows:
CaO + SOZ + l/Z 0z - CaS04'
£IF"
= -96 kcal/mole
CaO + COZ
.. CaC03' £IF"
= -33 kcal/mole
SiF4 + ZCaO
. ZCaFz + SiOZ' £I F" = -70 kcal/ mole
HZS04 + CaO
... CaS04 + HZO, £I F" = -Z9 kcal/ mole
ZHF + CaO
.. CaFZ + HZO, £IF"
= -27 kcal/mole
All the reactions have negative free energies, and thus are energetically feasible.
The amount of CaO present is 24.9/56.0 = 0.445 moles.
BATTELLE MEMORIAL INSTITUTE - COLUMBUS LABORATORIES
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C-2
Amount of CaO required for 502
= 0.437 moles
Amount of CaO required for H2S04 = 0.05 moles
Amount of CaO required for SiF4
= 0.04 moles
Amount of CaO required for HF, unknown
Total = 0.527 moles
Therefore, there would not be enough CaO to react with all pollutants of the acid
gas form. Probably the reaction with 502 would take place preferably, as it has the
most negative free-energy change. Another possibility is that some of the gases would
combine with the emissions from the cement plant.
Exit-Gas Composition
The schematic diagram below, shows the path of the flue gases.
o
~0
-0
P = 1 atm
Pi = -35 in. H20
P2 = -50 in. H20
T = 336 F
Tl
T2
v = 583,000 dm
Vi
V2
A = 7 Process Plants
B = Venturi Scrubber
C = Fan
To calculate Tl and Vi, the temperature and pressure of the gas before entering
the scrubber, adiabat-ic conditions are assumed
PVi. 3 = PVi. 3
Using the relationships for adiabatic flow,
Vi = 627,000 adm, Tl = 320 F
The next step is to calculate the quantity of water picked up in the scrubber by the
flue gases.
Assume water is available at 75 F, and that the specific heat of the gas approxi-
mates that of air (7 Btu/mole F).
BATTELLE MEMORIAL INSTITUTE - COLUMBUS LABORATORIES
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C-3 and C-4
Vapor pressure of water
= 2.22 cm Hg
Latent heat of vaporization = 1050 Btu/lb.
p - 405-50 = 0.875 atm
2 - 405
Let w = weight of water evaporated into the gas stream.
A heat balance then gives:
1050 w = 1010 moles of gas x 7 x (780 -T2)
Also
2.22 X 2118 X V2 - w X 1544 X T2
76 - T8
And
V2 = Vgas + Vwater
= 1010 x
359 x T2
492
w
+-x
18
359 x T2
492
There are 3 equations and 3 unknowns, T2' V2' and w.
Solving, one obtains T2 = 240 F
w = 540 Ib/min (30 moles/min)
V2 = 530,000 cfm (394,000 scfm)
The composition of the exit gases are then easily calculated.
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