EPA-600/2-76-199
July 1976
Environmental Protection Technology Series
,
OPERATION OF A
SULFURIC ACID PLANT USING
BLENDED COPPER SMELTER GASES
Industrial Environmental Research Laboratory
Office of Research and Development
U.S. Environmental Protection Agency
Research Triangle Park, North Carolina 27711
-------
RESEARCH REPORTING SERIES
Research reports of the Office of Research and Development, U.S. Environmental
Protection Agency, have been grouped into five series. These five broad
categories were established to facilitate further development and application of
environmental technology. Elimination of traditional grouping was consciously
planned to foster technology transfer and a maximum interface in related fields.
The five series are:
1. Environmental Health Effects Research
2. Environmental Protection Technology
3. Ecological Research
4. Environmental Monitoring
5. Socioeconomic Environmental Studies
This report has been assigned to the ENVIRONMENTAL PROTECTION
TECHNOLOGY series. This series describes research performed to develop and
demonstrate instrumentation, equipment, and methodology to repair or prevent
environmental degradation from point and non-point sources of pollution. This
work provides the new or improved technology required for the control and
treatment of pollution sources to meet environmental quality standards.
EPA REVIEW NOTICE
This report has been reviewed by the U.S. Environmental
Protection Agency, and approved for publication. Approval
does not signify that the contents necessarily reflect the
views and policy of the Agency, nor does mention of trade
names or commercial products constitute endorsement or
recommendation for use.
This document is available to the public through the National Technical Informa-
tion Service, Springfield, Virginia 22161.
-------
EPA-600/2-76-199
July 1976
OPERATION
OF A SULFURIC ACID PLANT
USING BLENDED COPPER SMELTER GASES
by
Ben H. Carpenter
Research Triangle Institute
P.O. Box 12194
Research Triangle Park, NC 27709
Contract No. 68-02-1325, Task 33
ROAPNo. 21AUY-057
Program Element No. 1AB015
EPA Task Officer: R.V. Hendriks
Industrial Environmental Research Laboratory
Office of Energy, Minerals, and Industry
Research Triangle Park, NC 27711
Prepared for
U.S. ENVIRONMENTAL PROTECTION AGENCY
Office of Research and Development
Washington, DC 20460
-------
TABLE OF CONTENTS
LIST OF FIGURES iv
LIST OF TABLES v
ACKNOWLEDGMENTS vi
1. Conclusions 1
2. Recommendations 4
3. Introduction 5
4. Gas Blending at Bor 7
4.1 The Smelter Gas-Handling System ........ 7
4.2 The Gas-Blending Trials 9
4.3 The Performance of the Acid Plant 10
4.3.1 Operating Conditions 10
4.3.2 Results 22
5. Examination of theFactors Relating to the Plume For-
mation 24
5.1 Survey of Experience with C02-Containing Feed Gas 24
5.2 Appraisal of Conditions Prevailing During Trial
Runs 24
5.3 Design Features that Control Plumes 27
6. Literature Review 33
6.1 Emissions from Contact Sulfuric Acid Plants . . 33
6.2 Sulfuric Acid Mist Formation 33
6.3 Control of Mists 34
BIBLIOGRAPHY 38
APPENDIX : , 41
ABSTRACT 45
iii
-------
LIST OF FIGURES
Figure Page
1 Gas handling system, Bor Plant 8
2 Contact sulfuric acid plant at Bor, Yugoslavia .... 11
3 Gas flow sheet for sulfuric acid converter system,
Bor, Yugoslavia 16
4 Gas flow sheet for sulfuric acid plant at the Collier
Carbon and Chemical Corporation 28
5 Typical collection efficiencies of particulate collection 35
iv
-------
LIST OF TABLES
Table
1
2
3
4
5
6
7
8
9
10
Al
A2
Sulfuric Acid Plant Operating Data. Gas Purification
Cooling Tower
Sulfuric Acid Plant Operating Data. Gas Purification
Washing Tower
Sulfuric Acid Plant Operating Data. Gas Purification
Wet Electrostatic Precipitator
Sulfuric Acid Plant Operating Data. Gas Drying Towers
Sulfuric Acid Plant Operating Data. Auxiliary Air
Drying Tower
Sulfuric Acid Plant Operating Data. Converters . . . .
Sulfuric Acid Plant Operating Data. Converters ....
Sulfuric Acid Plant Operating Data. Absorber
Experience of Acid Plant Designers and Builders ....
Ammonia Scrubber and Mist Eliminator. Compliance Test
Results
Emission and Operating Data for Contact Sulfuric Acid
Plants with Mist Eliminators
Acid-Mist Collection in Absorber Stacks of Contact Sul-
furic Acid Plants
Page
12
13
14
17
18
19
21
23
25
31
42
43
-------
ACKNOWLEDGMENTS
This report describes an investigation by the Research Triangle
Institute, Research Triangle Park, N.C, of the operation of a contact
sulfuric acid plant at a copper smelter being fed with blended exit gases
from roasters, reverberatory furnaces, and converters. The investi-
gation focuses on the problem of a visible plume from the acid plant
stack.
The investigation was carried out under Contract No. 68-02-1325.
Mr. R. V. Hendriks of the Environmental Protection Agency's (EPA)
Industrial Environmental Research Laboratory, Research Triangle Park,
served as Project Officer.
The investigation was conducted in the Process Engineering Department
with Mr. Ben H. Carpenter as Project Leader. Several individuals
contributed to specific aspects of the study. Mr. Raj Swarup interpreted
much of the technical literature. Mr. J. P. Dempsey was engineer in
residence at the Bor Copper Smelter, where the gas blending trials were
made, during its expansion in 1970 and 1971. He provided an appraisal
of the circumstances that prevailed during the blending of gas streams
fed to the acid plants. Mr. Tim J. Browder, a specialist in the design
and operation of sulfuric acid plants, appraised the information available
on the Bor plants relative to the problem of plume formation and sug-
gested design features necessary for elimination of plumes. Mr. J. H.
Buddenberg, of the Collier Carbon and Chemical Corporation, permitted
their sulfuric acid plant to be observed in operation. Mr. J. R. Donovan
of Monsanto's Enviro-Chem Systems, Inc., provided technical information
on mist control features of this plant. Performance data for the mist
controls used at Collier were supplied by the Los Angeles Air Pollution
Control District.
'Mr. Norman Plaks, Chief, EPA's Metallurgical Processes Branch, Indus-
trial Environmental Research Laboratory, provided additional guidance to
the investigation. Messrs. Doug Bell, Charles Darvin, and Fred Porter of
EPA's Office of Air Quality Planning and Standards, provided helpful suggestion.
vi
-------
SECTION 1
CONCLUSIONS
A high degree of control of SOV emissions at copper smelters can be
A
obtained by blending reverberatory furnace gases with gases from roasters
and converters and using the combined stream as feed to a sulfuric
acid plant. The Bor Copper Smelter in Bor, Yugoslavia, experimented with
this technique for a short time and reported that visible plumes of
acid mist were emitted from their acid plant stack. This was attributed
to the carbon dioxide present in the reverb gases, which was presumed
to decrease the absorption of SOg with the unabsorbed SO, emitted as a
mist.
The results of this study indicate that the visible plume produced
at the acid plant at Bor, Yugoslavia, when reverberatory furnace gases
were added to its feed stream were caused by factors other than the .pre-
sence of C02- The visible plume could most likely have resulted from
additional sulfuric acid mist loads imposed upon the wet electrostatic
precipitator (ESP) that receives cooled smelter gases from the acid
plant cooling system. This would increase the concentration of mist
in the gas leaving the ESP, and hence increase the quantity of mist carried
through the dryers to the converter. Any of the mist disassociated to
SOg and water in the converter would recombine as very fine mist as the
gas cooled, and be carried through the S03 absorber to the stack.
Several factors could have increased the mist content of the blended
gases when the reverberatory furnace gases were included:
- The reverberatory furnace was operated on pulverized
coal, had manual controls and instrumentation, and sub-
stantial in-leakage of air. The resulting excess oxygen
at high temperatures is conducive to the oxidation of
nitrogen to NOX, which could promote the formation of
SOo in the exit gases. The reaction of SOo with water
would yield acid mist.
-------
In the gas blending trials, the reverberatory furnace
gas was fed to the mixing tower for the acid plant
feed gases without treatment for removal of fine
particulates. Any particulate matter not removed in
the waste heat boiler was evidently carried some
distance through the ducts, in which it may have
promoted the formation of SOo from the SC>2 present,
contributing to increased mist.
The furnace gas was usually fed to the acid plant feed
gas tower only when gas from an iron pyrites roaster
was also available. Since this roaster was operated
intermittently, the reverberatory furnace gas was
flowing through its duct intermittently, with time
for cooling, reaction, and condensation therein bet-
ween successive runs. Mist formed in the duct while
its flow was shut off could have been carried into
the acid plant when gas flow was resumed.
Representative samples of the Bor reverberatory furnace gases
showed the following composition ranges over an eight-hour period: SC^,
0.4 to 3.1 percent by volume; CC^, 1.4 to 12.4 percent by volume; 02,
5 to 18.8 percent by volume. The estimated range of C02 concentration
in the mixed gases fed to the sulfuric acid is 0.4 to 4.7 percent.
Sulfuric acid plants processing refinery alkylation acids, waste
hydrogen sulfide and sulfur also process (^-containing feed gases
frequently in greater concentration than that found in the Bor reverber-
atory gas. The danger exists that traces of impurities in these feed
materials, not the (X^, might cause a highly visible stack plume. Data
was obtained on one of these plants which continues to operate without
excessive S02 or ^504 mist emissions. The plant has the following units
not present in the Bor plant: a Brink mist eliminator after the absorber,
designed for an efficiency of 90 percent on 0.3 to 3 micron particles;
an ammonia scrubber to reduce S02 emissions to below 300 ppm; and a Brink
demister which reduces particulates to 20 mg per normal cubic meter.
The system operates without a plume most of the time. Opacity of the
stack gases exceeded the California standard (< 40%) only once during a
-------
full day's compliance testing. For the rest of the test period, opacity
readings were less than this standard; the haze was blue or white and not
the black color for which the measurement method was designed. The high
efficiency mist eliminators appear to be necessary to eliminate sulfuric
acid mist.
-------
SECTION 2
RECOMMENDATIONS
At this point, the study seems to have established the causes of
plume formation in the acid plant during gas blending trials at Bor.
The available operating data do not, however, provide sufficient information
about the conditions of operation of the absorber which is a very important
factor. Further study of the design of the Bor acid plant, to quantify
the performance expected of the mist-control equipment is recommended.
It is recognized that the gas blending trials were not entirely pre-
planned experiments; therefore, no systematic data collection could be
expected. However, the analysis presented herein indicates that gas
blending can proceed without a visible acid plant plume if the reverbera-
tory furnace gases are produced with controlled burning, properly cleaned,
and if the acid plant is equipped with high efficiency mist eliminators.
Reverberatory furnace gases at Bor are now being cleaned with an ESP.
The possibility of conducting a planned trial of gas blending involving
planned sampling should be explored for its mutual possible advantages.
-------
SECTION 3
INTRODUCTION
At domestic copper smelters, reverberatory furnaces present a
difficult problem in control of sulfur dioxide (809) emissions. Typically,
S0« concentrations in the exit gases are too low for autogeneous conversion
to sulfuric acid in a vanadium-catalyzed process. Neither is an alter-
native approach to control completely acceptable at this time. New
source performance standards currently exempt these furnaces from con-
trol. Their total emissions, however, include dusts high in arsenic and
other toxic substances. Reverberatory furnaces thus present an overall
problem requiring the development of new technology.
The Environmental Protection Agency is investigating the possibility
that a high degree of control of sulfur oxides (S02 and SO.,) emissions
from copper reverberatory furnace off-gases can be achieved by blending
these gases with those from roasters and converters and using the combined
streams as a feed to a sulfuric acid plant. The Bor copper smelter in
Bor, Yugoslavia, experimented with this technique for a short time. They
reported, however, that when reverheratory gases were introduced into the
total gas mix, the absorption of SO, in the acid plant was apparently
decreased, and a visible acid mist plume was observed. Federal standards
for emissions from U. S. acid plants exclude those attached to smelters,
but smelter standards limit the opacity of acid plant stack gases to 20 per-
cent. Thus, a visible plume would be poor operation in this Country. The
Bor experts attributed this poor acid plant operation to the high carbon
dioxide (C02) content of the reverberatory furnace gases. This conclusion
is contrary to other known situations where acid plants operate well with
C02 containing feed gas.
This study provides an investigation of the possible effect of C09 in
the feed gases to a sulfuric acid plant on its performance and its emissions
levels. Available data on the gas blending experience at Bor have been
compiled and examined to determine the extent of knowledge concerning acid
plant design, operating procedures, and gas stream conditions.
-------
The information thus developed has been compared with the experience
of American acid plant builders to determine whether CO- has generally an
adverse effect or whether other factors are the likely cause of the acid
plume formation experienced at Bor.
-------
SECTION 4
GAS BLENDING AT BOR
4.1 THE SMELTER GAS-HANDLING SYSTEM
Figure 1 shows the gas-handling system at the Bor smelter at the
time the first gas blending trials were made, in 1969. There were five
Maguin multihearth roasters. Concentrates processes in the roasters
contained about 0.8 percent arsenic. Roasting removed 45 to 50 percent
of the sulfur. The resulting calcine was 17-18 percent sulfur. Gases
left the roasters containing 8.8 to 10.6 percent S02 and 3.8 to 5.9
o
percent oxygen (02). The total volume averaged 50,000 Nm /hr. No
external fuel was used. After dust removal and about 100 percent dilution,
these gases typically contained about 5.7 percent S02 when combined with
the converter gases.
Two of the plant's three "Pierce Smith" converters were operated at
a time, and the gases were combined with the roaster gases after passing
through electrostatic precipitators and blowers.
Gases just off the converters contained about 12 percent S02- The
O
flow-rate from a single converter was about 33,000 Nm /hr at this point.
After cleaning, with attendent dilutions, the gases averaged 2-6 percent
so2.
The coal fired reverberatory furnace produced 50,000 kkg/yr of
copper. Furnace gases were usually sent ot a stack but could be sent,
via the duct which connected with the duct from a fluo-solids roaster,
to a mixing tower for blending with gases from the roasters and conver-
ters. The composition of the reverberatory furnace gases at the time
is not known, but the data for furnace operation in 1972 show a gas rate
3
of 60,000 to 72,000 Nm /hr; with S02 content ranging from 0.4 to 3.1 per-
cent, by volume; C02, from 1.4 to 12,4; 02 from 5 to 18.8.
Figure 1 shows a (Dorr-Oliver) fluo-solids roaster, which is mounted
on top of the reverberatory furnace, with its exit gases passing through
\
cyclones and,an ESP, then through a duct to blending tower MT. This
-------
oo
TO
CONTACT
ACIO PLANT
BALLOON FLUE
id
•Jj
ir^
M
•
•IW* •"•"
—
MT-,
£V
M
o
REACTOR
NO. I
CYCLONES
CONVERTERS
I LBOILER
W^H.
Gfcz
REVERB
NO. I
BOILER MULTIHEARTH ROASTERS
MT
!!
V\ ' J>AMPERS7
T0/^x\ I I X /
STACK \\J L£ ^_.
F = FANS
MT = MIXING TOWER
TO
CHAMBER
ACID PLANT
NEW STACK
Figure 1. Gas handling system, Bor Plant.
-------
roaster was operated half time, processing iron pyrites at a rate of 345
3
kkg/day. It produced some 48,000 Nm /hr* of gases containing 12-13
percent S0_.
4.2 THE GAS-BLENDING TRIALS
In October 1969, the reverberatory furnace gases were mixed for a
trial period with those of the multihearth roasters and converters, and
fed to the acid plants, including the contact acid plant. During the
trials, the mixture's S0« content was strengthened intermittently by
addition of gases from the pyrites roaster. The gases were blended
using the duct system shown in Figure 1, and were fed from mixing point
MT1 - to the sulfuric acid plant-which at this time consisted of two chamber
process units of Petersen design and one Chemiebau contact process unit.
This study is concerned only with the contact unit. Gas rates there,
3
after drying, ranged on a typical day from 81,000 to 83,500. Nm /hr. Since
the total gas rate exceeded the capacity of the acid plants, excess gases
were sent to a stack. By 1971, the Bor plant had added a second contact
acid plant, similar to the first. Each of the contact acid plants had
a sulfuric acid capacity of 430 kkg/day. A fluo-solids concentrate roas-
ter was also in operation. In a second trial of gas blending, conducted
in October, 1971, the feed to the acid plants included gases from two
converters (3rd idle), the fluo-solids roaster and the multihearth roasters,
the iron pyrites roaster, and one reverberatory furnace. Provision was
made, as before, to heat the gases going into the contact plants, since
the iron pyrites roaster was operated intermittently, and the SOr, concen-
tration of the feed gases was occasionally low when it.was not operating.
Feed rates to Contact Plant No. 1 ranged from 80,000 to 82,000 Nm3/hr;
those to Contact Plant No. 2, 88,000 to 90,000 Nm3/hr.
The symbol N indicates standard conditions: 760 mmHg, and 273 K.
-------
4.3 THE PERFORMANCE OF THE ACID PLANT
4.3.1 Operating Conditions
One contact plant was available for the trials in 1969; two, in
1971. Both plants were technically identical Chemibau units. The
single absorption converters had four stages of vanadium oxide catalyst.
The plant was comprised of four basic processes: gas purification, gas
drying, oxidation of S02, and absorption of SO, (Figure 2). Operating
data for two selected days for the first gas-blending trial and two days
of the second trial are shown in Tables 1 to 8. The data in all these
tables are given in the order: October 21, 1969; October 22, 1969;
October 5, 1971: October 6, 1971, as indicated at the start of Table 1.
The gas purification process employed a steel gas cooling tower
lined with acid resistant brick (1) , Gas.es entering the plant with 12
to 17 percent oxygen (wet basis) were sprayed with 19 percent sulfuric
acid, for cooling and removal of some dust. (The cooling operation is
reported to produce sulfuric acid mist which absorbs catalyst-poisoning
quantities of As^Oo and Se02 carried in the dusts). The gas pressures
and temperatures in and out of the cooling tower are shown for every
second hour of daily operation in Table 1. During the four days shown,
gas temperatures of the exit gases ranged from 28 to 55°C. The average
o
specific heat of gases entering the cooler is estimated to be 0.323 kcal/Nm .
Cooled gas passed to a Raschig-ring packed washing tower also con-
structed of brick-lined steel (2), Here it was sprayed with, acid, part of
which was recovered from the following ESP. Operating data for the wash-
ing tower are shown in Table 2. Exit gas temperatures ranged from 25 to
36°C.
Washed gas passed to a two-stage wet Electrostatic Precipitator (8).
Operating data recorded for the ESP (Table 3) were gas pressure in and
out, and data believed (pending receipt of further design information) to
be concerned with control of the rectifier: the voltage on the high-vol-
tage transformer (V), the current through power thyristors in series with
10
-------
CONDENSED PHASE
GAS, PHASE
UNITS: 1. Gas Cooling Tower 6.
2. Gas Washing Tower 7.
3. Settling Tanks 8.
4. Cooling Coils 9.
5. Collecting Tank 10.
Collecting Tank
Heat Exchanger
ESP
Pre-drying Tower
Drying Tower
PROCESS STREAMS:
A. Smelter gases
B. Liquid feed to cooling tower
C. Liquid feed to washing tower
D. Effluent from Cooling tower
E. Slurry of solids and weak acid
F. Condensed mist from ESP
11.
12.
13.
14.
15.
Spray
Spray
Main
Heat
Heat
Coolers
Cooler
Blower
Exchanger
Exchanger
16.
17.
18.
19.
20.
Converter
Air Blower
Air Drying
Tower
Spray Cooler
Absorption
Tower
21.
22.
23.
24.
25.
26.
Spray Cooler
Stack
Storage Tanks
Cisterns
Oil-fired
preheater
(startup)
Air Blower
G. 75% H2S04
H. Effluent from converter
I. 98% H2S04
J. Make—up water
K. Absorption tower effluent
L. Transfer of acid from 12 to 18
M. Preheater exhaust to stack
Figure 2. Contact sulfuric acid plant, Bor, Yugoslavia
-------
Table 1
Sulfuric Acid Plant Operating Data
Gas Purification Cooling Tower
Hour Day
6 10/21/69
10/22/69
10/ 5/71
10/ 6/71
8
10
12
14
16
18
20
22
24
•
2
4
.
Pressure,
In
110
115 ,
o-1-7
5
112
40
10
15
110
75
5
5
125
70
0
15
85
55
4
10
95
65
2
25
100
75
20
0
120
80
5
10
90
70
10
"~
100
65
5
—
130
80
15
""
115
80
15
-
Gas
ranH.,0
Out~
215
180
-
162
180
90
-
72
185
145
-
30
200
150
-
57
175
130
-
95
175
140
-
110
230
175
-
135
210
170
-
160
175
150
-
155
185
195
-
155
185
190
-
165
185
170
180
75
Temp .
In
260
289
198
182
252
182
180
200
240
194
175
193
239
205
180
200
220
138
198
205
218
208
190
210
235
210
178
205
232
206
185
202
240
215
190
—
239
222
200
-
218
225
200
-
210
220
180
-
"C
Out
52
41.
40
29
53
38
39
30
55
44
41
29
58
45
36
29
47
44
40
33
50
45
42
30
50
45
41
29
52
48
42
28
50 ...
49
39
31 ,«
48
53
39
31
45
47
40
31
45
48
40
31
Acid
Temp . c
In
28
27
35
34
; 28
' '• 29 ""
35
35
1 -
29
30
31
34
29
30
31
35
28
38
37
40
26
37
39
33
30
28
39
29
28
27-
39
28
28
24
32
30
26 ""
30
31
32
28
« . 30
31
31
29
28
31
31
«^J^iS
"c
Out
49
41
48
35
50
41
47
35
50
43
47
34
53
47
44
36
46
46
46
40
47
46
47
33
51
47
46
33
50
44
46
31
48
48
44
33
46
50
44
35
47
48
46
34
45
40
46
34
—Change in reading reflected in logs for 1971
12
-------
Table 2
Sulfuric Acid Plant Operating Data
Gas Purification, Washing Tower
Hour
6
8
10
12
14
16
18
20
22
24
2
4
Gas Exit
Temp. °C
30
29
25
27
35
••' •,-.•- 23
:' :.: 25
30
36
23
«. 25
30
36
26
26
. 28
29
26
26
31
27
26
27
29
34
31
26
20
33
32
26
25
30
32
24
32
29
35
26
26
30
32
30
29
34
30
, 25
25
___Acj
Temp .
In
29
22
19
20
23
22
19
20
21
25
20
24
21
21
21
18
21
23
21
18
19
22
22
20
21
25
22
16
20
26
22
15
18
30
20
21
17
24
! 22
20
19
20
26
18
20
20
20
15
d
°C
Out
43
38
35
34
43
34
33
33
41
33
32
34
43
36
31
35
39
37
32
38
37
37
33
35
45
39
32
36
45
39
32
34
43
43
28
35
42
44
29
36
41
41
36
35
40
40
35
38
13
-------
Table 3
Sulfuric Acid Plant Operating Data
Gas Purification
Wet Electrostatic Precipitator
Hour
6
8
10
12
14
16
18
20
22
24
2
4
Gas Pressure
mm H^O
In Out
275 365
260 342
215
225
275 370
110 205
185
260
265 370
180 298
187
200
280 385
188 307
200
265
245 340
170 285
210
270
240 330
195 310
190
218
340 430
225 355
320
210
280 375
225 355
205
210
255 330
210 325
240
260
255 330
250 385
250
270
265 340
235 355
235
300
253 335
225 340
235
230
First Stage
Filters 1-4
V A mA
260
260
292
290
220
240
280
280
260
255
290
300
280
250
290
300
278
265
287
295
265
258
285
200
266
268
290
280
263
262
282
280
265
270
290
290
285
264
285
280
265
270
275
295
260
265
280
30.0
30
38
32
33
35
32
32
26
30
30
33
40
45
30
32
40
45
40
33
42
33
30
32
40
33
40
34
30
35
26
32
34
30
35
33
35
45
25
33
44
35
35
34
42
24
35
33
40
95
122
110
110
105
100
110
130
95
98
110
140
120
100
110
145
130
125
110
150
105
98
105
140
105
120
110
100
115
40
105
100
100
120
110
120
140
105
110
155
100
100
115
150
100
100
110
150
Second Stage
Filters
V A
260
275
310
325
260
230
320
325
260
250
325
330
265
220
320
330
278
270
330
320
268
280
325
320
240
275
325
312
265
260
320
300
260
280
328
305
270
270
325
310
270
280
315
215
268
280
320
315
0
25
34
30
5
15
32
29
10
15
32
33
20
25
30
33
25
30
30
35
5
30
30
34
15
30
30
28
28
15
29
40
5
30
30
25
35
18
30
42
20
35
30
41
18
34
29
20
1-2
mA
40
82
110
60
40
20
60
60
40
40
60
70
80
80
60
65
100
80
60
70
60
100
60
65
50
80
60
65
82
60
60
70
40
100
60
55
105
100
60
90
80
100
60
90
80
110
60
85
Filters
V A
240
280
275
280
220
250
225
290
220
268
280
300
270
270
280
295
272
275
280
280
266
280
218
283
265
270
290
275
265
270
275
270
280
280
280
265
265
270
280
270
275
280
270
275
274
280
275
275
5
30
32
32
5
10
31
36
10
20
31
40
20
30
32
42
30
30
32
43
15
30
32
42
15
20
30
35
28
10
31
35
25
30
32
30
30
20
32
44
25
30
32
42
20
30
32
42
3-4
mA
20
100
100
110
20
55
100
125
50
80
100
150
80
100
105
150
100
100
105
150
80
100
100
142
58
80
100
120
85
60
100
120
80
100
105
100
100
100
110
160
95
100
110
150
100
100
110
150
Optical
Visibility
good
good
good
—
good
good
good
—
good
good
good
—
good
good
good
—
good
good
good
good
good
good
good
good
good
good
good
good
good
fair
good
good
good
good
good
good
good
good
good
good
good
good
good
good
good
good
good
good
14
-------
the high voltage transformer primary (A), and the value of high tension
current supplying the electrical field (mA). Optical visibility at
the ESP sight glass was classed as either good, bad, or fair, no bad
readings were noted, but the observation was occasionally omitted.
The gas drying process employed a predrying tower and a drying tower.
In the predrying tower (9), the gases were sprayed with strong sulfuric
acid. Operating records for this tower (Table 4) indicate that the gases
were washed with 82-76 percent acid at inlet temperatures from 30 to 36°C.
The drying tower (10) to which the gases then passed was packed with
Raschig rings. Here the gases were contacted with 93-97.8 percent acid
at inlet temperatures of 28 to 39°G (Table 4).
Auxiliary air which was blown into sections of the converter as
required for oxidation of S0_ to SO-j, was also dried using a separate
Rashig-ring packed tower (18), The data (Table 5) show a range of auxiliary
3
air from 78-82 m /hr. This is about one percent of the S02~containing
gas processed. Acid used ranged in concentration from 92 to 97.8 percent.
Acid exit temperatures are given for three points, the relative positions
of which are not yet defined. The range shown is 30-66°C, with the high
values at exit 2.
From the drying tower, the_gas was transferred by turbo-blowers into
the converter system. A flow sheet for this system, derived from available
information, is shown in Figure 3. Gases from the drying tower are heated
by exchange with converter gases from the converter exit and from stage 2.
Gas temperature in the converter is controlled by heat exchange and by
auxiliary air blown into stages two and four. The auxiliary air also
provides additional oxygen for conversion of S02 to SO.,. Operating data
in Table 6 provides the performance of the first contacter during the 1969
gas blending trials, and the performance of the second converter in 1971.
Table 7 shows the gas pressure drops through the converter stages
and the heat exchangers.
The SO, containing gases from the converter, after heat exchange
(heat exchanger 1, Figure 3) were, passed into the brick-lined steel absorp-
tion tower. The tower was packed with Raschig rings. Acid accumulated in
15
-------
FROM DRYING TOWER
TO
STACK•
ABSORPTION
TOWER
HEAT EXCHANGERS
DRIED
"AIR
DRIED
AIR
CONVERTER
HEATER
Figure 3- Gas flow sheet for sulfurlc acid converter system, Bor, Yugoslavia.
-------
Table 4
Sulfuric Acid Plant Operating Data
Gas Drying Towers
Acid
Predrying Tower
Hour
6
8
10
12
14
16
18
20
22
24
2
4
Temp. *C
In Out
30
30
30
33
30
30
30
35
29
33
30
34
30
31
30
30
30
30
30
33
33
30
31
32
32
30
32
30
30
31
33
36
34
30
30
32
29
35
33
35
29
32
32
35
31
31
30
33
35
34
45
-
35
33
45
-
35
36
45
-
36
35
45
-
34
35
44
-
33
35
46
-
40
37
47
48
38
36
50
44
40
37
45
52
34
40
48
61
32
39
54
55
36
35
50
52
Density
Em/ cm
1.660
1.652
1.680
1.5456
1.660
1.660
1.680
1.5568
1.655
1.658
1.660
1.5866
1.660
1.660
1.660
1.4876
1.660
1.660
1.660
1.5446
1.660
1.660
1.652
1.662
1.660
1.650
1.660
1.660
1.660
1.656
1.664
1.662
1.654
1.652
1.644
1.662
1.660
1.655
1.650
1.660
1.666
1.650
1.652
1.660
1.650
1.658
1.650
Tank
level
610
630
560
740
700
690
700
740
600
700
710
840
680
700
760
1000
680
660
700
930
630
670
830
760
690
650
900
1000
600
600
820
900
690
680
870
810
580
640
720
800
560
660
680
700
680
700
780
600
Temp.
In
32
34
28
30
34
30
32
32
35
31
33
30
35
32
32
31
34
34
33
33
32
34
35
33
35
35
37
30
33
35
38
29
34
33
35
30
34
34
35
39
32
33
32
33
31
32
30
31
Drying Tower
"C
Out
44
42
36
46
50
42
46
48
50
44
46
44
50
42
45
44
44
44
48
48
42
45
50
46
52
48
52
70
49
50
55
38
46
48
50
43
46
48
50
52
40
46
56
46
48
43
43
42
m3 Cone.
"Hr %
- 97.53
- 97.91
- 93.00
- 93.00
- 97.18
- 97.67
- 93.00
- 93.00
- 97.10
- 97.59
- 94.90
- 93.00
- 97.19
- 97.60
- 95.95
- 93.00
- 97.50
- 97.60
- 96.02
- 93.00
- 97.77
- 97.69
- 96.20
- 93.00
- 97.50
- 97.50
- 95.34
- 93.00
- 97.37
- 97.36
- 95.10
- 93.00
- 97.36
- 97.80
- 95.39
- 93.00
- 97.37
- 97.16
- 95.81
- 93.00
- 97.65
- 97.39
- 93.00
- 93.00
- 97.79
- 97.45
- 93.00
- 93.00
level
810
840
1130
1280
805
920
1320
1320
840
810
1420
1270
850
800
1240
1070
770
790
960
1260
880
800
1370
1250
860
840
1070
1270
800
800
1070
1120
820
740
1190
1200
830
790
1160
1280
650
780
1080
1180
750
760
1240
1130
Gas
Pressure
mm HjO
In
345
320
35
25
350
188
20
25
355
275
20
23
365
286
23
23
325
265
25
23
300
230
23
21
405
325
23
22
360
325
22
21
315
319
28
27
310
350
30
23
320
330
25
27
320
320
27
22
Out
460
430
200
205
465
270
210
205
465
388
215
208
485
390
208
210
435
370
208
210
410
395
208
207
530
450
205
210
465
455
205
207
420
425
205
210
415
475
200
200
430
455
205
210
420
435
210
205
17
-------
Table 5
Sulfuric Acid Plant Operating Data
Auxiliary Air Drying Tower
Hour
6
8
10
12
14
16
18
20
22
24
,
2
4
Acid
Exit
1
30
31
36
34
29
30
28
38
32
31
29
38
34
30
28
38
30
30
28
41
31
30
29
37
32
30
31
35
30
30
32
30
28
29
29
34
34
30
31
41
32
30
31
38
30
29
32
37
Temp.
Exit
2
32
35
55
54
32
34
49
58
35
33
48
56
35
30
48
58
34
33
40
66
34
35
41
56
35
34
43
52
34
36
44
47
34
34
41
58
38
35
41
62
30
37
43
56
35
34
48
56
°C
Exit
3
30
34
31
33
32
32
35
35
35
32
37
33
35
30
36
34
34
32
37
35
33
34
38
36
35
35
40
30
33
35
42
30
32
32
39
31
35
33
37
40
30
30
39
38
30
30
33
33
Feed Rate
m /hr
82
82
-
-
80
80
-
-
80
80
-
-
80
80
-
-
80
80
_
-
81
78
-
-
80
80
-
-
79
79
-
-
78
80
-
-
79
80
-
-
80
78
-
-
80
80
-
-
Cone.
%
97.54
97.75
92.56
96.42
97.26
97.68
94.90
96.45
97.15
97.67
96.29
96.15
97.20
97.65
96.86
95.72
97.42
97.61
96.94
96.52
97.15
97.67
97.07
96.12
97.52
97.59
96.38
97.18
97.41
97.36
96.18
94.70
97.35
97.05
96.71
95.69
97.56
97.16
96.68
95.50
97.65
97.28
95.17
95.12
97.74
97.45
96.12
95.10
18
-------
Table 6
Sulfuric Acid Plant Operating Data
Converters
Gas '
Rate
1000
Hour Hn3/hr
6 82
82i/
90^
90
8 82
70
92
90
10 82.7
81.0
92.5
90
12 82
80
91
90
14 83.5
80
90
90
16 82
80
81
90
so2
4.0
3.3
2.8
3.8
3.9
0.7
3.2
4.0
4.1
4.0
4.9
4.4
5.4
2.9
5.3
3.4
2.5(P)
2.4
3.9
6.5
4.9(P)
5.2
3.9
8.3
Added Air^'
1000
Nm3/hr
8.5
3.0,.
- I/
-
9.
0.
-
-
7.2
0.
_
-
9.
0.
-
-
1.
0.
-
-
2.7
9.2
-
-
5.
1.5
-
5.3
0.
_
-
4.9
0.
_
-
4.6
0.
-
-
4.9
0.
-
-
4.7
1.1
-
-
Outer Heat
Exchanger
In Out
71
70
75
68
70
61
75
80
71
71
78
75
75
67
75
75
72
68
72
75
67
70
75
73
365
339
335
350
350
322
322
354
340
311
322
360
340
310
315
345
340
328
347
373
332
330
344
387
T
Exit
B'twn
Exc's.
505
479
422
448
490
418
412
440
483
445
420
440
480
465
423
440
480
468
446
452
480
482
438
447
E M P
E R A T
Stage 1
In Out
468
441
440
455
452
427
421
460
449
412
431
455
450
429
434
445
448
432
455
467
444
442
450
463
572
541
520
560
560
473
505
590
556
508
538
560
565
519
535
547
549
512
510
598
550
560
572
593
U R
Stage 2
In Out
532
527
520
542
522
472
505
580
520
496
530
530
525
511
532
545
523
508
569
572
524
520
577
547
543
526l/
520
542
525
490
506
570
526
48li'
525
530
530
518
530
542
528
518
560
572
530
532
597
548
E, °
C
Stage 3
In Out
482
435
430
457
450
422
419
460
445
409
422
455
445
422
428
442
438
425
447
470
434
438
472
477
470
445
438
460
455
447
424
473
450
412
440
458
450
425
440
460
449
428
460
470
444
440
452
488
Stage 4
In Out
458
435
438
450
438
428
421
457
435
412
440
450
438
425
441
460
431
428
460
467
428
432
452
488
458
435
430
445
438
429
423
495
435
417
435
450
438
425
440
447
431
428
452
453
432
435
450
478
Exit
Outer
Heat
Exc.
195
178
160
182
185
157
160
185
182
155
160
185
185
155
162
162
171
155
167
198
170
170
167
210
-------
Table 6 (Cont.)
NJ
O
Gas
Hour
18
20
22
24
2
4
Rate
1000
Nn>3/hr
88
86
90
90
83
88
91
90
82
85
90
90
81
85
90
88
81
85
88
90
82
85
91
90
so2
%
6.2(P)
4.2
4.2
3.7
4.2(P)
4.KP)
4.8
5.4
3.2(P)
4.8(P)
6.0
5.2
3.6(P)
4.5(P)
3.2
5.2
3.9
5.0
3.3
8.0
2.2
3.4
4.9
4.9
Added Alr^
1000
Nm3/hr
S1/S22/S3/SA
10.
3.9
-
-
9.6
8.0
-
-
4.8
9.2
-
-
7.5
10.2
-
-
4.8
3.5
-
-
0.
3.7
_
—
5.0
3.8
_
-
5.0
5.5
-
-
4.8
5.0
-
-
4.5
5.0
-
-
3.9
5.0
-
-
5.8
7.0
-
•~
:~ss :
Outer Heat
Exchanger
In Out
71
70
78
70
67
70
80
70
68
70
79
72
69
70
82
78
68
70
85
78
65
68
75
79
360
332
373
372
358
346
353
363
348
350
358
362
341
352
362
385
342
360
375
380
340
355
350
332
T
Exit
B'twn
Exc ' s .
498
482
442
429
480
488
452
445
482
491
450
445
438
492
462
441
482
490
459
445
479
487
438
448
E M
P E
Stage 1
In Out
457
448
448
422
448
452
463
460
430
457
461
469
450
455
470
460
447
450
470
460
441
450
450
465
586
552
560
540
560
562
572
580
550
569
580
570
560
571
588
582
560
570
572
595
525
550
562
590
R A
T U
Stage 2
In Out
545
522
560
527
516
520
572
545
525
522
580
545
525
531
586
530
522
525
555
555
521
525
538
560
552
530
558
525
525
530
567
548
527
532
563
545
530
540
579
540
530
531
555
558
521
522
532
560
R E,
°C
Stage 3
In Out
445
440
448
458
436
450
456
460
440
450
458
466
440
445
465
470
433
444
465
422
430
440
445
428
462
448
460
462
449
458
471
470
448
458
472
472
450
459
484
482
448
450
478
435
444
458
458
490
Stage 4
In Out
440
432
760
460
428
440
471
470
428
438
472
472
430
436
484
482
430
439
458
424
428
430
458
479
442
435
755
460
432
435
465
460
430
439
462
468
432
440
473
475
432
443
452
465
430
440
439
472
Exit
Outer
Heat
Exc.
191
175
170
192
190
180
172
182
185
185
170
192
180
190
175
215
178
190
198
210
175
188
178
215
— First two days shown are for the first contact acid plant; the last two, for the second
(newer) acid plant.
(P)Indicates that the feed gas contained iron pyrites roaster gases.
o /
— S1/S2 denotes air added between the first and second catalyst beds of the converter.
S3/S4 denotes air added between the third and fourth bed.
3/.. . . .
— no data recorded.
-------
Table 7
Sulfuric Plant Operating Data
Converters
Outermost
Beat Exc.
Hour
6
8
10
12
14
16
18
20
22
24
2
4
1
1900
1610
2400
2700
1880
1250
2420
2690
1820
1500
2430
2730
1850
1590
2430
2500
1790
1580
2410
2700
1790
1780
2400
2800
2030
1800
2400
2600
1850
2020
2400
2700
1750
1990
2420
2700
1780
1970
' 2480
2680
1710
1930
2600
2760
1650
1890
2600
2780
Points
2
1420
1168
-
-
1394
883
-
—
1360
1078
-
—
1380
1112
-
-
1270
1130
-
-
1280
1364
-
-
1570
1373
-
-
1398
1522
_
-
1256
1486
-
-
1306
1478
_
-
1252
1470
-
-
1184
1394 '
—
_
Pressure,
Stage 1
11
80
60
-
-
79
40
-
-
73
55
-
-
75
63
-
-
70
60
-
-
68
69
-
-
82
70
-
-
79
52
_
-
70
80
_
-
67
75
-
-
65
85
-
•-
60
65
_
-
In
1260
1041
1820
2270
1244
770
1610
1910
1208
944
1630
1820
1214
992
1630
1680
1122
990
1630
1910
1189
1100
1624
2020
1374
1200
1720
1790
1250
1380
1620
1875
1104
1306
1630
1880
1076
1310
1660
1910
1110
1310
1870
2005
1048
1294
1770
2005
Out
1155
933
1440
1710
1140
690
1440
1740
1108
862
1460
1760
1108
888
1444
1570
1012
884
1456
1736
1070
994
1460
1844
1260
1095
1390
1624
1152
1254
1460
1700
1000
1202
1450
1720
1004
1204
1500
1760
1008
1200
1630
1820
948
1132
1600
1835
mm H20
Stage 2
In
1080
868
1390
1610
1066
638
1382
1080
1039
776
1382
1690
1040
820
1384
1420
950
820
1396
1673
912
910
1390
1790
1170
1002
1330
1556
1080
1152
1390
1630
934
1118
1380
1640
996
1194
1410
1690
992
1120
1610
1760
880
1050
1530
1760
Out
975
776
1260
1440
962
572
1256
1540
928
692
1254
1660
922
730
1250
1300
860
734
1269
1530
818
822
1260
1627
1064
910
1200
1424
962
1050
1260
1480
832
1010
1260
1500
906
1000
1275
1550
942
1020
1490
1610
708
842
1410
1620
Stage 3
In
780
625
1050
1220
786
450
1034
1290
746
494
1020
1300
746
584
1022
1170
702
672
1090
1280
752
710
1034
1374
860
730
990
1190
780
844
1030
1230
672
816
1030
1230
730
808
1040
1300
679
830
1250
1350
632
773
1150
1350
Out
645
522
846
1000
660
377
871
1060
635
438
832
1040
632
780
830
890
600
485
838
1040
624
652
837
1077
735
620
800
985
668
718
815
1000
563
692
810
1015
618
682
825
1045
576
700
1020
1115
533
650
950
1115
Stage 4
In
615
489
790
960
613
340
790
1000
586
419
780
1010
583
448
774
810
544
440
792
1005
525
505
794
1025
684
570
750
819
517
665
750
945
515
643
775
950
568
630
780
1000
528
645
985
1045
490
616
870
1045
Out
428
278
432
620
423
220
505
945
408
287
495
660
408
300
495
510'
375
303
499
640
363
348
495
960
475
397
470
596
398
465
488
600
352
450
490
605
324
431
490
645
353
440
640
695
340
428
560
680
21
-------
the reservoir at the tower base at 98-99 percent concentration after
o
being sprayed into the tower at about 500 m /hr (Table 8). The desorbed
gases left the absorber at 60 to 83°C. The circulated acid was cooled
by passing it through trough coolers sprayed with water. The gases were
passed through a "drip separator" (not fully described), and then to a
stack.
4.3.2 Results
The S0? content of the exit gases was estimated at 1500 ppm. When
reverberatory furnace gases were added to the feed gas for treatment in the
acid plant, the exit gases developed a plume of acid mist. This disappeared
when these gases were taken out of the feed stream. The formation of the
plume was attributed by the Yugoslav operators to the C0? content of the
reverb gases. This was presumed to have decreased the absorption of SO,.
Unabsorbed SOo was then emitted to form a sulfuric acid mist.
22
-------
Table 8
Sulfuric Acid Plant Operating Data
Absorber
Hour
6
8
10
12
14
16
18
20
22
24
,2
4
Gas
Exit
Temp. °C
69
66
75
80
65
62
77
83
68
68
65
83
72
63
68
70
61
62
78
80
64
71
76
80
70
65
78
70
64
62
81
70
61
68
79
79
70
70
80
80
62
65
79
80
60
60
72
78
mm
H00
16
8
-
-
15
4
-
-
16
7
_
-
14
10
-
-
15
10
-
-
16
11
-
-
21
15
-
-
16
17
-
-
12
16
_
-
13
12
-
-
14
15
-
-
13
13
-
_
Temp
In
60
60
60
64
60
60
63
68
60
68
56
68
62
60
52
64
59
58
62
70
60
62
62
64
62
60
68
60
60
60
67
58
58
62
63
61
62
62
62
64
60
59
63
62
58
58
59
62
. °C
Out
78
74
78
84
74
68
78
92
73
70
77
90
78
68
73
80
72
68
84
94
76
78
80
90
80
74
85
82
76
78
85
80
71
78
83
83
76
76
83
88
72
74
85
90
70
72
80
90
Acid
*3
mj/hr
500
490
_
-
510
510
-
-
500
500
-
-
500
515
-
-
505
510
-
-
510
505
-
-
500
500
-
-
520
515
-
-
500
510
-
-
490
500
-
—
495
540
-
-
500
520
-
-
•
Cone.
%
98.54
98.49
98.35
98.48
98.60
98.80
97.83
98.48
98.56
98.50
98.20
98.42
98.59
98.52
98.98
97.90
98.53
98.58
99.00
98.50
98.64
98.58
98.68
98.48
98.65
98.56
98.25
98.61
98.51
98.54
98.12
98.27
98.54
98.83
98.67
98.54
98.60
98.60
98.63
98.26
98.62
98.58
98.41
98.44
98.57
98.54
98.48
98.41
23
-------
SECTION 5
EXAMINATION OF THE FACTORS RELATING
TO THE PLUME/FORMATION
5.1 SURVEY OF EXPERIENCE WITH O^-CONTAINING FEED GAS
Several sulfuric acid plant designers and builders have indicated
that some of their plants handle C02~containing feed gases without a
plume in the exit gases. While very high C02 concentrations were felt
to be adverse to over all operation, there was no valid scientific or
experimental support for this thinking. The estimated range of C02
concentration in the mixed gases fed to the acid plant at Bor is 0.4 to
4.7 percent. This is lower than the 5 to 6 percent C02 in the feed
to sludge burning plants.
Many firms had experienced plume problems or operation upsets due
to 1) nitrogen oxide in the feed gases, 2) CO from incompletely burned
organic matter, 3) excessive moisture in the gases entering the conver-
ter, 4) insufficient rate of acid circulation and lack of uniform distri-
bution in the SO- absorption tower, 5) unclean packing in the SO-
absorption tower, 6) improper concentration and temperature of the
absorbing acid, and 7) shock cooling of the gases leaving the converter
below their dew point.
Table 9 summarizes the experiences and opinions of the several firms
with whom the Bor gas-blending trial was discussed.
5.2 APPRAISAL OF CONDITIONS PREVAILING DURING TRIAL RUNS*
The conditions prevailing at the Bor plant during the two tests of
gas blending offered several opportunities for generation of a plume: an
intermittently used underground flue; excess combustion air; and excess
particulate matter in the uncleaned reverberatory furnace gases.
*
Based on personal observations of Mr. J.P. Dempsey who was resident
engineer during the Bor plant expansion in 1970 and 1971, and on analysis
of the information by Mr. Tim J. Browder, specialist in sulfuric acid
plant design.
24
-------
Table 9
Experiences of Acid Plant Designers and Builders
Firm
M. W. Kellogg
Ralph M. Parsons
Stauffer Chemicals Co.
Smelter Control Research Assoc.
Chemical Process Plants
Division of Chemico
Fluor, Utah
Leonard Construction Co.
Enviro-Chem
Picatinny Arsenal
Sludge burning plants with 5-6% C(>2 in
the feed gas have had no plume problems.
NOX in converter exit gas seems to
promote formation of 1*2804 mist from
803 and H20 before the gas reaches the
absorber. Low flame temperatures
suppress the plume, possibly because
they supress NOX.
CC*2 has not been known to cause a plume.
One satisfactory elemental sulfur
conversion plant feeds a gas that tests
5-8% CC-2 and 0.9% 02 at the stack.
C02 cannot cause a plume. Their
alkylation acid plants process feed gases
with greater than 4% C02 without plume
problems.
The cause of plume formation is most
likely H2S04 mist.
C02 has had no effect.
Brink mist eliminators are normally used
to remove any mists that might be present
from whatever cause, and that might
otherwise form a plume.
C02 cannot cause a plume. NOX probably
promotes the formation of E^SO^ mists in
the presence of moisture, and the mist
causes the plume.
CC>2 has not been a problem.
C02 has not been a problem. Absorber
acid concentration, temperature, and
inadequate distribution can contribute
to plume formation.
Wire mesh types of mist eliminators do
not control the plume from TNT plant acid
recovery systems.
25
-------
At the time of the 1969 tests, a flue conveyed gas from the No. 1
Reverberatory Furnace underground to the old stack. There was a
connection to the flue from the pyrites roaster just prior to the point
where the reverberatory flue went underground. Accordingly, the furnace
gas was mixed with the pyrites roaster gas downstream from the roaster
ESP. This means that the furnace exit gas still contained all particulate
matter not removed in the waste-heat boiler. These particulates could have
promoted the conversion of S02 in the gas mix to SOo, which would then
form excessive mists as the gas traveled on through the duct system.
The reverberatory furnace was a fairly old furnace, built in 1958-
1959. It was fired with pulverized coal in 1969 and 1971, and had
minimal process controls and instrumentation. The side wall brick had
been replaced many times. In 1970 and 1971, these side walls looked like
a sieve, and substantial air inleakage was unavoidable. Excess air
during combustion in the furnace would have caused oxidation of nitrogen
to NO which would catalyze the formation of SO- in the exit gases. The
X j
cooling and drying systems of the acid plant would not be expected to
remove fine mist particles (< 3 microns) formed from SO- and water. These
would then overload the ESP sufficiently to allow excessive mist to reach
the converter, dissociate there, and reform in the absorber, overload
the "drip separator", and exit to generate a plume.
The intermittant operation of the pyrites roaster would have provided
an opportunity for acid mist to accumulate in that part of the duct system
which was thus intermittently idle. This mist would have been swept
into the acid plant when the roaster operation was resumed.
The cause of the plume is judged to have been the use of excessive
air in burning the coal in the reverberatory furnace, leading to formation
of N0x which, with excessive particulate dust passed into the gas handling
system. Here excessive sulfuric acid mists were formed which passed
through the acid plant to the atmosphere.
26
-------
5.3 DESIGN FEATURES THAT CONTROL PLUMES
Figure 4 shows the gas flow through an acid plant operated by the
Collier Carbon and Chemical Corporation to produce sulfuric acid from
refinery hydrogen sulfide, alkylation acid, and sulfur. The system
feeds gases produced by burning the three sulfur bearing materials, and
the feed is usually a composite form of all three. This plant was observed
to operate without any pliume formation. Its performance had been
confirmed by tests carried out by the Los Angeles Air Pollution Control
District. While limited data are available on the composition of the
feed gases to this plant, the feed gas may be presumed to contain C02 at
a somewhat higher concentration than the reverberatory furnace gases at
Bor. Resen (37) gives the following composition of gases from a comparable
sludge acid furnace: 30.7 percent H?0, 8.6 percent 809, 9.7 percent C0«,
1.5 percent 02, 49.4 percent N7. The Collier plant controls the excess
02 in the burner exit gases at 3 percent, which would reduce their S02
and C0~ concentrations somewhat below those given for this sludge acid
furnace described by Resen. The gas feed rate to the stack at the Collier
o
plant was about 35,000 Nm /hr. (The converter feed gas showed 10 to 11.2
percent 802)•
In the humidifying tower, the gas is washed with a 0 to 5 percent
H-SO, spray. It is then cooled in "Carbate" coolers, to 27-30°C, and
some water and acid condense. The cooled gas is treated in an ESP which
was fabricated using 15 cm diameter lead tubes. This unit has an estimated
particle elimination efficiency of 95 - 99 percent (weight basis).
After further cooling, the gas is dried with 96 -97 percent H-SO,. A
98 percent acid would be too high; acid and SO, vapor pressures would be
high enough to add mist to the gases.*
The plant has a gas-fired startup pre-heater which can be bypassed.
Heat exchangers can also be bypassed but usually adjust to changes in
i
flow by the changes in heat transfer coefficient thereby induced.
Discussion with Mr. J. R. Donovan of Monsanto Enviro Chem, the designer
of the mist control system.
27
-------
STEAM DRUM
BLOW DOWN
A A
STACK
FURNACE
ESP
BRINK MIST
ELIMINATOR NO. 2
BRINK MIST ELIMINATOR
NO. I
WATER
AND
ACID
ro
oo
AMMONIA ABSORPTION
SCRUBBER
HEAT EXCHANGERS
-K
DRYING
TOWER
i rU
ru TCAF
CARBATE EXCHANGERS
WATER
CONVERTER
Figure 4. Gas flow sheet for sulfuric acid plant at
the Collier Carbon and Chemical Corporation.
-------
The Collier plant presents some of the same conditions—gases exposed
to combustion temperatures in the presence of excess air, organic materials
present in the added fuel, limited clean up of the gases prior to the
cooling and humidifying tower—that existed at Bor. The dust content
of the Collier gases should be lower than that of the Bor reverberatory
furnace gases. While the Collier system affords less cooling of the feed
gases prior to the humidifying tower, it accordingly provides a greater
degree of "shock" cooling at the humidifier. Beyond the converter,
however, the Collier gases are subjected to mist eliminators of high
efficiency, an important factor in the control and elimination of a plume.
The ammonia scrubber and Brink mist eliminator No. 2 were recently
added to the plant, primarily to control S02 emissions from this single
absorption system. The Brink mist eliminator No. 1 was a part of the
original system (36). It was designed to handle 35,000 Nm /hr of gas
at 85°C with an efficiency of 90 percent on 0.3 to 3 micron particles,
with a pressure drop of 184 mm E^O. Installed in the top of the absorber,
the mist eliminator consisted of 22 packed fiber elements. Each was a
hollow core cylinder measuring 46 cm in diameter by 2.5 m high. The fibers
were packed within corrosion-resistant, wire mesh enclosures. These ele-
ments were mounted vertically in the corrosion-resistant metal tube sheet
installed in the absorption tower. Liquid trapped by the fibers drained
from the elements at the rate it collected, permitting continuous operation.
When the plant was started in 1960, the stack met the requirements
and was approved by the Los Angeles Air Pollution Control District. Visi-
bility measurements revealed results better than the No. 2 Ringelmann chart.
Since tests of the gases leaving the mist eliminator inside the
absorber showed that the gases were completely invisible, any slight
opaqueness of the stack gases was attributed to mist formation in the stack
or chemical reaction of the gaseous components with water vapor in the
atmosphere. The unit tested 100 percent recovery efficiency on particles
greater than 3 microns in diameter and 94 percent on 0.3 to 3 micron particles.
Pressure drop across the unit varied between 50 and 152 mm water. The unit
recovered about 770 kg of H2S04 per day.
29
-------
The ammonia scrubber and second mist eliminator were added to bring
the plant into compliance with new S02 regulations. In May 1974, the
Los Angeles Air Pollution Control District tested these units, sampling
gases at the ammonia scrubber inlet and the Brink mist eliminator No. 2
outlet. The test results are tabulated in Table 10.
The equipment operated at steady conditions from 9:00 am until
5:00 pm on the day of the tests, May 29, 1974. Materials charged to the
process were:
H2S 12.6 metric tons per day
Alky Acid 32.6 metric tons per day
Sulfur 106.7 metric tons per day
Water 0.2 liters per second
The total rate of input materials was 685 kg/hour. The sulfuric acid
production rate was 422 metric tons/day.
The mist eliminator outlet tested well under the required standards
for total particulates and SC^-
The opacity standard is less than 40 percent opacity (No. 2 on the
Ringelmann Chart) except that a value as dark or darker than 40 may
occur not more than three minutes per hour. Accordingly, the first
reading of 40 for seven minutes is a violation. However, the haze was
noted as light blue, not black as required for the Ringelmann test. The
last six haze readings (Table 10) were noted as white in color. The
haze thus does not quite fully conform with the color requirements for
use of the Ringelmann Charts. The violation was minor, since the rating
equaled 40 but did not exceed it.
The standards discussed in the previous paragraph are California
standards. New Source Performance Standards, EPA Reg. 40 CFR 60.80,
60.81, 60.82, and 60.83, apply to sulfuric acid plants which produce sul-
furic acid by burning sulfur, alkylation acid, etc. This plant meets
two of the three Federal Standards: S02 emissions were less than 2 kg/ton
of acid produced, and acid mist emissions were nil. The opacity standard
could be considered violated. However, these standards do not apply to
facilities where conversion to sulfuric acid is utilized primarily as a
30
-------
Table 10
Ammonia Scrubber and Mist Eliminator
Compliance Test Results^
u>
Scrubber Inlet
Gas flowrate, Nm3/hr, wet 31772
dry 31432
Gas velocity, m/sec 14.8
Gas temperature, °C 60
Total particulates, kg/hr 2.09
mg/Nm^
Solid particulates? kg/hr 0.50
S02, kg/hr 540
ppm by vol
kg/ ton acid produced
NH3, kg/hr
Acid mist, kg/hr 0.72
kg/ton of acid produced
% Opacity at 46-meter stack
11:16 to 11:23 am
11:23 to 11:24 am
11:24
11:31 to 11:36
11:36 to 11:38
11:38 to 11:41
16:14 to 16:15
16:15 to 16:17
16:17 to 16:20
Allowable Emissions Fff, . £
_ Eiir.LCi.ency or
Demister Outlet California Federal Controls, %
34660
33131
15.5
33
0.68 67
19.9 147
0.68 0
242 90 96
270 2000
1.37 2.0
0.05
0.0
0.0 0.075
40 <40 <20
30
25
30
20
30
30
20
25
1. Air Pollution Control District, County of Los Angeles, Test No. C-2127, May 29, 1974,
2. Solid particulates = Total particulates - sulfuric acid
3. New Source Performance Standards
-------
means of preventing emissions of sulfur compounds. At a copper smelter,
the appropriate standard for opacity is < 20 percent opacity, given in
Standards of Performance of Copper Smelters, Federal Register, January
15, 1976 (p. 2339).
32
-------
SECTION 6
LITERATURE REVIEW
General information relevant to the causes and control of emissions,
and plumes, from sulfuric acid plants has been compiled from the technical
literature; articles reviewed are listed in the Bibliography.
6.1 EMISSIONS FJROM CONTACT SULFURI.C ACID PLANTS
The Manufacturing Chemists Association and the Public Health Service
conducted a study of atmospheric emissions from sulfuric acid manufacturing
processes.(25) Emissions and operating data were compiled for about 12
percent of the total number of establishments. These data help to assess
the general performance of an acid plant. Two tables from this study are
appended to this report: Table Al, Emissions and Operating Data for Contact
Sulfuric Acid Plants with Mist Eliminators; Table A2, Acid-Mist Collection
in Absorber Stacks of Contact Sulfuric Acid Plants. Several types of plants
are included in the tables. The data indicate that plants at that time
(1965) were achieving 96.9 to 98.5 percent conversion of S02 to S0_.
Typically, S02 concentrations in the stack gases ranged from 0.14 to 0.35
percent. Plume opacity ranged from none to light. Acid mist leaving the
mist eliminator ranged from 6.3 to 826 mg/m (0.18 to 23.4 mg/scf). Mist
3
leaving the absorber ranged from 35 to 1723 mg/m (1 to 48.8 mg/sef) except
that one plant that used no water removal facility for the discharge com-
bustion gases showed a mist level of 89,450 mg/m3 (2533 mg/scf). The
mist particles leaving the absorber ranged from 7 to 70 percent less than
3 microns in diameter. By comparison, the Collier Plant (Section 4)
o
showed only 20 mg/m of total particulates.
Existing plants, at the time of this study, were achieving lower
conversion and less emissions control than could have been attained had
the plants been using the best processing techniques then available. A
German double absorption contact plant offered in 1963 claimed 99-7 percent
conversion at approximately the same investment as the single adsorption
plants then in operation.(38) (The Bor plant uses a single absorption process.)
6.2 SULFURIC ACID MIST FORMATION
In most contact plants, dryers reduce the moisture content of gases
entering the converter to 106 mg/m3. As these gases leave the converter,
33
-------
acid mist will form if the temperature falls below the dew point.(25)
The mist tends to be of very fine particle size and is not absorbed in
the SO. absorber. Theoretically, moisture in the dried gas at this level
3
could generate 530 mg/m of mist.
Traces of NO in the inlet gas to the absorber are reported to hinder
x
the adsorption of SO,. (25) NO is also believed to promote the formation
j X
of SO., prematurely in the feed gases before they enter the humidifying
tower. Upon cooling, the SO, forms mist by reacting with the water present.
NO is formed by combustion of fuels at high temperature with excess oxygen.
X
Brink found that the acid mist collected on the fiber mist eliminator of
a typical hydrogen sulfide-spent acid fed plant contained two percent
nitrogen as nitric acid. (27) ESP's may produce NO if arcing occurs.
X
Plants which produce oleum face problems of mist formation; generally
the amount of mist varies directly with the proportion of plant output in
the form of oleum and the strength of the oleum produced. The extent of
cooling of the converter gas before it passes to the oleum tower influences
the particle size and hence the visibility of the mist in the exit gases.
The visibility of an acid mist depends more on particle size than on
concentration. High proportions of mist particles less than 3 microns
in diameter could cause a heavy plume if present in concentration greater
3
than 35 mg/m . (28) Mists containing particles up to 10 microns in diameter
have been observed, since there is visible light scattering. Conversely,
if the particle size exceeds 10 microns, then the plume may not be visible
2
at concentrations of up to 176 mg/m .
Unabsorbed SO, can be hydrated to mist when exposed to moist air. A
detached plume is an indication that this is taking place.
6.3 CONTROL OF MISTS
Numerous types of entrainment separators are available to collect mists:
cyclones, wire mesh impingers, ESP's, fiber mist eliminators, and venturi
scrubbers. Currently designed acid plants now employ any of these that
are considered appropriate. Figure 4 shows their typical collection
efficiencies.
Fiber mist eliminators effect the elimination of submicron particles
of mist by providing a surface with which the particles can collide under
Brownian movement. A particle of 0.1 micron dimeter will have about five
34
-------
u>
Ui
100
X1
95-1
O 90-
u
2
Q 80
u
III
O
O
70
Typical Brink H-E
Mist Eliminate
Electrostatic
Precipitator (3)
Wire Mesh /High Efficiency
(2) I Cyclone (1)
Reference*:
1) Strauss, W. Industrial Gas Cleaning. Pergamon
Press, 1966. p. 193.
2) Perry, John H. Chemical Engineers' Handbook.
Fourth edition McGraw-Hill, 1963. p. 18-88.
3) White. P. A. F., & Smith, S. E., High Efficiency Air
Filtration. Butterworths, 1964. p. 192.
4) Lund, H. F. Industrial Pollution Control Handbook.
McGraw-Hill, 1971. p. 11-11.
5) Nonhebel, G. Gas Purification Process. Newnes
1964. p. 15.9.
80" Venturi (S)
.025
.3 .5 1
PARTICLE SIZE—MICRONS
10
20
Figure 5. Typical collection efficiencies of particulate collectors.
-------
times the Brownian displacement (caused by collision with gas molecules)
of a 1 micron particle. This increases the probability that the particle
will collide with a fiber and be collected. Larger particles are collected
by impaction and interception. Mist particles collected on the fibers
unite and form a film which moves horizontally through the fiber bed,
propelled by the gases. Once on the inside surface, the liquid moves down-
ward to a collection seal (or directly into an absorber if the eliminator
is installed directly above it) and are returned to the process. (32, 34)
Mineral wool filters show improved acid mist collection efficiency if
moisture is present on the surface.(31) This material is characterized
by small fiber diameter (4 microns), and resistance to high temperature
(540°C).
ESP's show good efficiency as mist collectors in acid plants; the
wire and tube design is the most frequently used. Usually, two ESP's in
series are prescribed because the first tends to overload, and when this
occurs, process adjustments can be made with the second ESP as effective
backup. For acid plants, tests have shown (29) particle migration velocities
of 0.21 to 0.18 m/sec, with attendant efficiencies of about 99.7 percent.
For known migration velocities, the probable efficiency can be calculated
using the Duetch equation.(35) Stopperka(35) has investigated the effect
of design and gas moisture content on the collection of acid mist with ESP's.
A relatively new method, fog filtration:, is being used to remove con-
taminants such as H2SO, mists in TNT plant streams. This is essentially
a high pressure scrubber in which vaporized water cleans the gas in silo-
shaped chambers spaced about 15 meters apart.(30) This gas cleaning system
applies as follows: partially clean gas from ESP's is fed to one of three
fog filters where it is washed under high pressure, pulled downward in a
swirling motion, drawn through a pipe and expelled. The effluent water
flows from the bottom of the filter to a collecting basin. The fog particles
from the high pressure nozzle provide an induced draft; all gas thus
entrained moves with the velocity of the fog particles. These particles
wet the mist particles and carry them out of the air by simulated cyclone
action.
36
-------
If for any reason, NO in the gases cannot be reduced by control of
A
combustion, and adequate mist elimination cannot be elected, a method for
NO removal from the gas has been investigated (33) in which the gas is
A
passed over coal particles which absorb the NO . The chief application
X
of this method appears to be in nitric acid plants, where the absorbed NO
J
contributes to higher process efficiencies.
37
-------
BIBLIOGRAPHY
1. Semrau, Konrad T. "Control of Sulfur Oxide Emissions from Primary
Copper, Lead and Zinc Smelters-A Critical Review," Jour. Air Poll.
Control Assoc.. 21(4), April 1971, pp. 185-194.
2. Donovan, J. R. and Stuber, P. J. "Sulfuric Acid Production from Ore
Roaster Gases," Jour, of Metals, Nov. 1967, pp. 45-50.
3. Tarbutton, G., Driskell, J. C., Jones, J. M., Gray, F. J. and Smith,
C. M. "Recovery of Sulfur Dioxides from Flue Gases," Ind. and
Engr. Chem., 49(3), March 1957, pp. 392-395.
4. Fleming, E. P., et al. "High. Purity Sulfur from Smelter Gases,"
Ind. and Engr. Chem., 42(11), Nov. 1950, pp. 2249-2269.
5. Applebey, M. P. "The Recovery of Sulphur from Smelter Gases," Jour, of
the Society of Chem. Industry. 139, May 1937, pp. 139-146.
6. Johnstone, H. F., et al. "The Recovery of Sulfur Dioxide from Waste
Gases," Ind. and Engr. Chem.. 30(1), May 1938, pp. 101-109.
7. Sawyer, F. G. and Hader, R. N. "Sulfur from Sour Gases," Ind. and
Engr. Chero.. 42(10), Oct. 1950, pp. 1938-1950.
8. Valdes, A. R. "New Look at Sulfur Plants," Hydrocarbon Processing and
Petroleum Refinery, 43(3), March 1964, pp. 104-108.
9. Goar, B. G. "Today's Sulfur Recovery Processes," Hydrocarbon Processing.
47(9), Sept. 1968, pp. 248-252.
10. Thompson, R., et al. "History of ^SO^ Production from Converter Gas
at the Kennecott Copper Corporation's Utah Smelter," J. of Metals,
July 1968, pp. 82-84.
11. Doerr, Karl H.; Grimm, Hugo; Winkler, Egon; "Removal of S0_ from Waste
Gas in Contact Plants," Germ Offen, pp. 13, 22 May 1975.
12. Sasaki, Kazud. "Manufacturing H-SO, by Contact Process Free from Tail
Gas Formation," Japan Kokai, 3 pp. 18 Sept. 1973.
13. Amerlin, A. G.; Yashkee, E. V.; Valiev, B. T.; Kaupoya, R. P. Kim.
Prom. (Moscow), 49(6), 1973, pp. 435-438.
14. Doerr, Karl H.; Frimm, Hugo; Taoke, Michaels; Peichl, Robert. "Removal
of Sulfur Trioxide and Sulfuric Acid Mist from Waste Gases," Germ
Offen. 12 pp, 22 March 1973.
15. Salas, Francisco Nunez. "Incidence of Sulfuric Acid and Products which
• Appear in the Working Environment of a Sulfuric Acid Factory Using
the Contact Method for Production of Acid," Ion (Madrid), 32(369),
April 1972, pp. 214-217.
16. Minzi, E. "Determination of Sulfuric Acid Spray, Sulfuric Acid Mist,
and Unabsorbed Sulfur Trioxide in Exhaust Gases from Sulfuric Acid
Contact Plants," Chem. Engr. Tech. 44(13), 1972, pp. 858-60.
17. Sasaki, Kazud. "Oxidation of Sulfur Dioxide with Pure Oxygen for Itnprove-
Improvement of Catalytic Production of H0SO.," Koatsu Gasu. 8(6), 1971,
pp. 335-338. 2 4
38
-------
18. Mande, S. S.; Venkataraman, K.; and Raman, S. K. "Selection and
Adaptation of a Process for SO. Removal from Gases in Contact
H2S04 Plant," Indian Chem. J.. 61. I-VIII, 1971.
19. Danielson, John A., Editor. Air Pollution Engineering Manual. Edition
II, "Chemical Processing Equipment," Environmental Protection
Agency, Research Triangle Park, N.C., May 1973, pp. 719.
20. Heuter, F. G., et al. Air Quality Criteria for Nitrogen Oxide.
A report prepared by the Expert Panel on Air Quality Criteria,
NATO Report N-15, June 1973.
21. Technical Report on the Conference on Low Pollution Power System
Development. A report prepared by the Expert Panel for the
Committee on Challenges of Modern Society, NATO Report No. 4,
Feb. 1971.
22. Burchard, John K., et al. Control Techniques for Nitrogen Oxide
Emissions from Stationary Sources. A report prepared by the
Expert Panel for the Committee on Challenges of Modern Society,
NATO, Oct. 1973.
23. Calderbank, P. H. "Contact-Process Converter Design," Chem.'Engr.
Progr., 49(11), Nov. 1953, pp. 585-590.
24. Weiger, Dipl. Ing. Horst. "Can SO, in Reverb Off Gases be Cut,"
World Mining. March 1975, pp. 56-60.
25. Cooperative Study Project by the Manufacturing Chemists' Assoc., Inc.
and Public Health Service, Atmospheric Emissions from Sulfuric
Acid Manufacturing Processes. U.S. Department of Health and
Welfare, 1965.
26. "Sulfuric Acid Process Reduces Pollution," Chem. Engr. News. Vol. 42,
December 21, 1964, pp. 42-43.
27. Brink, Jr., J. A. "Air Pollution with Fiber Mist Eliminators,"
Can. J. Chem. Engr., 41, June 1963, pp. 134-138.
28. Duecker, W. W. and West, J. J. Manufacture of Sulfuric Acid. ACS
Mono. 144., Reinhold Publishing Co., New York, 1959.
29. Gotham, R. L. "Electrostatic Precipitation of Sulfuric Acid Mist,"
Proc. Clean Air Conf., Univ. New South Wales, 1962, Paper 20,
Vol. 2, 16 p.
30. "Sulfuric Acid Mist is Cleaned from Air by Fog Filter System,"
• ((Air Eng.)), 9(3), March 1967, pp. 24-25.
31. Billing, Charles E.; Kurker, Jr., Charles and Silverman, Leslie.
"Simultaneous Removal of Acid Gases, Mist, and Fumes with Mineral
Wash Filter." J. Air Pollution Control Assoc., 8(3), Nov. 1958,
pp. 195-202. (Presented at 51st Annual Meeting, Air Pollution
Control Assoc., Philadelphia, Pa., May 26-29, 1958.)
39
-------
32. Brink, Jr., J. A.; Burggrabe, W. F. and Greenwell, L. E. "Fiber
Mist Eliminators for Sulfuric Acid Plants," Preprint, Monsanto
Co., St. Louis, Mo. (Presented at the Symposium on Sulfur, Sul-
furic Acid and the Future, Part II, 61st Annual Meeting, AIChE,
Los Angeles, Calif., Dec. 1-5, 1968, Paper 6-F.)
33. "A Method for the Recovery of Nitrogen Oxides," (Werkwijze voor
het winnen van stikstofoxyden.) Text in Dutch. (Universal
Oil Products Co., Des Plaines, 111. Dutch Pat. 6,607,036.
13 p., Nov. 25, 1966.
34. Brink, Jr., J. A.; Burggrabe, W. F. and Greenwell, L. E. "Mist
Removal from Compressed Gases," Chem. Engr. Progr., 62(4),
April 1966, pp. 60-66.
35. Stopperka, K. "Electroprecipitation of Sulfuric Acid Mists from
the Waste Gas of a Sulfuric Acid Production Plant," Staub (English
Transl.) 25(11), Nov. 1965, pp. 70-74.
36. "Blocks Air Pollution, Snares 1700 Ib of H SO, per Day," Chemical
Processing, Feb. 1962, Monsanto Enviro Chem Systems, St. Louis, Mo.
37. Resen, F. L. "Acid Sludges Regenerated to Make 98 Per Cent H-SO,,"
The Oil and Gas Journal. Jan. 18, 1954, pp. 101-104.
38. "New Acid from Refinery Sludge," Chemical Engr., Jan. 1954, pp. 114-116.
39. "This Acid Plant is Different," Chem. Engr.. Sept. 1955, pp. 128-130.
40. Labine^ R. A. "Converting Waste Sludge Acid to H SO,," Chem. Engr.
Jan. 11, 1960, pp. 80-83.
41. Harris, T. R. "Disposal of Refinery Waste Sulfuric Acid," Ind. Engr.
Chem., 50, Dec. 1958, pp. 81-82.
42. Graham, W. A. "Alkylation Integrates Acid Plant," Hydrocarbon
Processing, Aug. 1972, pp. 87-90.
40
-------
APPENDIX
Table Al. Emission and Operating Data for Contact Sulfuric Acid
Plants with Mist Eliminators
Table A2. Acid-Mist Collection in Absorber Stacks of Contact
Sulfuric Acid Plants
41
-------
TABLE Al. EMISSION AND OPERATING DATA FOR CONTACT
SULFURIC ACID PLANTS WITH MIST ELIMINATORS"
-P-
ro
Plant type
Raw material
Plant number
H.,SO4 production,
tons/day
Percent 'of
maximum capacity
Oleum made, % of output
Oleum made,
% of free SO3
Stack gas tem-
perature, °Fd
Stack gas rate, Mscfm
SO2 entering
converter, vol %
SO., in stack gas, vol %
Conversion of SO., to
S03, %
SO., emitted, tons/day
Type of mist eliminator
Acid mist leaving absorber,
% less than 3 microns
Acid mist leaving absorb-
er, mg/scf
Acid mist leaving mist
eliminator, mg/scf
H2SO4 collection
efficiency, %
H.>SO4 emitted, tons /day
SO, concentration leaving
absorber mg/scf
SO3 concentration leaving
mist eliminator, mg/scf
Plume opacity
Sulfur
Air dil. No air dil.
Molten dark
1
961
96
0
0
186
58
8.0
0.14
98.5
10.4
2A»
150
68
0 i
0
165
7.4
8.0
0.19
97.6
1.8
Wire me
70
6.5
0.60
light
7.5
48.8
3.6
92.6
0.04
2.1
1.1
none
2BK
150
68
13
30
166
7.4
8.0
0.20
97.5
1.9
sh
62.0
37.3
23.4
37.2
0.27
1.0
med.
Combination
Spent acid, H..S, and
supplemental sulfur
3A
240
100
0
180
0.34
3B
240
100
0
180
0.35
3C
219
91
0
76
12
8.2
0.26
97.2
4.0
4
133
60
56
40
76
7
8.4
0.17
98.2
1.5
Electrical precipitator
5.9
0.33
94.5
light
4.9
0.38
92.2
light
7.1
0.18
97.5
0.003
light
29.0
0.31
99.9
0.003
light
"Sampling points:
Plant 6A and 6B: in horizontal duct between absorber top and exit stacK.
All other olants: in duct or exit stack near top of absorber.
»Test data for Plant 2A and 2B were obtained by joint MCA-PHS field testing.
The results are averages of several tests.
Plant type
Raw material
Plant number
H.,SO4 production,
tons /day
Percent of
maximum capacity
Oleum made, % of output
Oleum made,
% of free SO3
Stack gas tem-
perature, "F"1
Stack gas rate, Mscfm
SO., entering
converter, vol %
SO., in stack gas, vol %
Conversion of SO., to
SO.,, %
SO., emitted, tons/day
Type of mist eliminator
Acid mist leaving absorber,
% less than 3 microns
Acid mist leaving absorb-
er, mg/scf
Acid mist leaving mist
eliminator, mg/scf
H.,SO4 collection
efficiency, %
H.,SO4 emitted, tons/day
SO3 concentration leaving
absorber mg/scf
SO3 concentration leaving
mist eliminator, mg/scf
Plume opacity
Combination
Spent acid, H..S, and
supplemental sulfur
5A
300
76
0
175
17
9.0
0.32
96.9
7.0
1-40
0.5-2
50.0
0.01-.05
1-2
1-2
5B
300
76
2
25
6AC
265
88
0
160
14
7.2
0.16
98.0
2.8
6Bc
300
100
0
180
21
7.4
0.19
97.8
5.1
Glass fiber
10-30"
7-9
60.0
20.6
0.23
98.9
0.005
none
32
1.9
94.1
0.06
faint
Wet
gas
HL,S
sulfur
7
100
67
0
130
11
Sulfur
Molten
dark
8
429
13
21.5
176
28.0
8.0
0.19
98.0
6.8
Combi-
nation
Spent
acid,
sulfur
9
272
0
150
19.3
7.4
0.20
96.7
5.0
| Teflon® mesh
38
2533'
1
2.3 1-2
99.9
0.04
t
light faint
1-4
faint
cRaw material included 48.4% spent acid, 32.8% H2S, and 18.89$- sulfur.
dSome of the temperatures are of acid entering the tower; however, inlet gas
and acid temperatures are usually close together.
'•High-velocity type glass-fiber mist eliminator designed for only medium
performance.
'This "wet gas" unit utilized no water-removal facilities for the discharge
combustion chamber gases.
-------
TABLE A2. ACID-MIST COLLECTION IN ABSORBER STACKS
OF CONTACT SULFUR1C ACID PLANTS*
Raw material
Plant number
H..SO. production, tons/day
Oleum, % of output
Oleum, % of free SO,
Stack gas temperature, *F
Stack gas* rate, Mscfm
SO, entering converter, vol %
Conversion of SO2 to SO,, %
SO« in stack gas, vol %
Ambient temperature ( avg ) , . *F
Ambient temperature (range), *F
Wind direction
Wind velocity (avg) , mph
Stack plume opacity
Stack gas velocity, ft/min
H..SO4 concentration
"leaving absorber, mg/ft-1"1
H2SO4 concentration
leaving Teflon demister, mg/ft3*
Acid drip from base of stack, Ib/day
Strength of acid drip, % H,SO4
Total acid mist from absorber
collected in stack, wt %«
Molten sulfur
1
429
13
21.5
176
28.0
8.0
98.0
0.19
25
8-37
NW.W.SW
10.1
faint
1990
^•W^HWflh^H^HHm*
1-2
22
70.4
11.0
2
422
51
30.8
123
25.1
8.8
97.5
0.25
29
25-36
N.NW.W
6.4
light
1620
2-4
no
demister
9
99.5
3.6
Molten sulfur
and spent acid
3
272
0
0
150
19.3
7.4
97.6
0.20
42
S-SE
12
faint '
1080
•I^PVI-V^^PIIIB—B^tfllW
1-4
0
0
4
302
71.5
20.0
163
19.7
8.0
97.8
0.20
35
S-SW
3
medium
775
••••••••••••••••••••••••••v
10-12
no
demister
0
0
•All plants incorporate internal, packed bed "spray" eliminators as part of the
standard absorber design.
"Acid mist concentrations are normal loadings, but were not obtained during
acid drip measurements.
The amounts of acid mist collected were averages from several tests con-
ducted at each plant.
43
-------
CONVERSION TO SI UNITS OF MEASURE
(°F + 459.67)71.8
M scfm x .4179474
mph x .44704
ft/min x .00508
mg/f3 x 35.3
Ig/day x .45359
tons/day x .907.185
°K
N km3/s
m/s
m/s
ukg/m
kg/day
metric tons/day
44
-------
TECHNICAL REPORT DATA .
(Please -JEEriZ* on the reverse before completing)
I— —""' ~ la. REC
ll. REPORT NO;
EPA- 600/2-76-199
[4. TITLE AND SUBTITLE -
Operation of a Sulfuric Acid Plant Using Blended
Copper Smelter Gases
7. AUTHOR(S)
Ben H. Carpenter
9. PERFORMING ORGANIZATION NAME AND ADDRESS
Research Triangle Institute
P.O. Box 12194
Research Triangle Park, NC 27709
'•"••••^ -- —
3. RECIPIENT'S ACCESSION NO.
5. REPORT DATE
July 1976
6. PERFORMING ORGANIZATION CODE
8. PERFORMING ORGANIZATION HbHUBT NOT
10. PROGRAM ELEMENT NO.
1AB015; ROAP 21AUY-057_
1. CONTRACT/GRANT NO.
68-02-1325, Task 33
12. SPONSORING AGENCY NAME AND ADDRESS
EPA, Office of Research and Development
Industrial Environmental Research Laboratory
Research Triangle Park, NC 27711
3. TYPE OF REPORT AND PER
Task Final; 3-12/75
ERIODCOVI
4. SPONSORING AGENCY CODE
EPA-ORD
llS. SUPPLEMENTARY NOTES EPA
82, Ext 2557.
officer for this report is R. V. Hendriks, Mail Drop
is. ABSTRACT gQX (gQ2 and so3) emissions from copper reverberatory furnace off-gases
can possibly be controlled to a high degree by blending the off-gases with those from
roasters and converters and using the combined streams as a feed to a sulfuric acid
plant. The Bor (Yugoslavia) copper smelter experimented briefly with the technique.
Bor reported that when reverberatory gases were introduced into the total gas mix,
absorption of SO3 in the acid plant.apparently decreased, and a visible acid mist
plume was observed. Bor attributed this poor acid plant operation to the high CO2
content of the reverberatory furnace gases, a conclusion contrary to other known
situations where acid plants operate well with CO2-containing feed gas. The report
gives results of an investigation of the effect of CO2 in the feed gases to a sulfuric
acid plant on plant performance and emission levels. Available data on gas blending
experience in Bor was compared with the experience of U.S. acid plant builders to
determine if CO2 generally has an adverse effect or if other factors probably cause
the acid plume formation experienced at Bor. The report indicates that the plume
during gas stream blending at the Bor smelter is probably caused by an excessive
load of sulfuric acid mist imposed upon the wet electrostatic precipitator that re-
ceives gases from the acid plant cooling system
17.
KEY WORDS AND DOCUMENT ANALYSIS
Ja- DESCRIPTORS
Air Pollution
Carbon Dioxide
Industrial Processes
Sulfuric Acid
Copper
1 Smelters
Smelting
Reverberatory
Furnaces
Sulfur Oxides
Electrostatic
Precipitators
18. DISTRIBUTION STATEMENT
Unlimited
b. IDENTIFIERS/OPEN ENDED TERMS
Air Pollution Control
Stationary Sources
Off -Gases
Gas Blending
19. SECURITY CLASS (This Report)
Unclassified
20, SECURITY CLASS (This page)
Unclassified
c. COS AT I Field/Group I
13B
07B
13H 13A
.11F
21. NO. OF PAGES I
51 1
22. PRICE ]
EPA Form 2220-1 (9-73)
45
------- |