ENGINEERING ANALYSIS
OF
EMISSIONS CONTROL TECHNOLOGY
FOR
SULFURIC ACID MANUFACTURING PROCESSES
VOLUME 2
LITERATURE SEARCH
FINAL REPORT UNDER CONTRACT CPA 22-69-81
FOR
DIVISION OF PROCESS CONTROL ENGINEERING
NATIONAL AIR POLLUTION CONTROL ADMINISTRATION
PUBLIC HEALTH SERVICE
U.S. DEPARTMENT OF HEALTH, EDUCATION & WELFARE
MARCH 1970
0064C
Consulting Division
Chemical Construction Corporation
320 Park Avenue
New York, New York 10022
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CONSULTING DIVISION
PART I
PAR T II
PART III
PAR T IV
CONTENTS
VOLUME 2 - LITERA TURE SEARCH
INTRODUCTION
REMOVAL AND RECOVERY OF SULFUR OXIDES
FROM SULFURIC ACID PLANT TAIL GASES
SULFURIC TRIOXIDE AND SULFURIC ACID
MIST EMISSIONS AND THEIR CONTROL
REMOVAL OF NITROGEN OXIDES FROM CHAMBER
AND MILLS - PACKARD SULFURIC ACID PLANT
TAIL GASES
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I
INTRODUCTION
This literature search forms a part of the final report under contract
CPA 22-69-81 entitled: "Engineering Analysis of Emissions Control
Technology for Sulfuric Acid Manufacturing Processes." The search
is divided into three bibliographies covering the areas and periods
described below.
Removal and Recovery of Sulfuric Oxides from Sulfuric Acid
Plant Tail Gases
This bibliography covers a search of Chemical Abstracts.
1955-1967. current technical journals and government
publications. Also included are references to waste gases
such as power plant stack gases and residual gases from
the Claus process. since these have similar compositions
to sulfuric acid plant tail gases. and may provide useful
information applicable as well to H2S04 plants.
Sulfur Trioxide and Sulfuric Acid Mist Emissions and
Their Control
This bibliography covers a search of Chemical Abstracts
1907 -1967. current technical journals and government
publications. .
I - 1
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A BIBLIOGRAPHY OF SULFUR
DIOXIDE REMOVAL AND RECOVERY
FROM WASTE GASES AND
SULFURIC ACID PLANT TAIL GASES,
EXCLUDING THE LIMESTONE AND DOLOMITE
INJECTION PROCESSES. 1953-1968, WITH ABSTRACTS
TABLE OF CONTENTS
(Subject Index)
Data on S02 emissions:
a) From stacks of coal-burning furnaces (2, 4, 6, 184)
b) From stacks of oil-burning furnaces (2, 4, 6)
c) From sulfuric acid plants (1, 2, 3, 4, 5, 7, 184)
1.
Toxicity and tolerance of S02 i~ atmosphere (8 to 11, 17)
Absorption of S02 in water (12 to 23, 93)
II.
III.
IV.
Absorption of S02 in inorganic aqueous salt solutions: .
a) Ammonia (24 to 29)
b)
c)
d)
e)
f)
g)
h)
i)
j)
k)
1)
m)
n)
0)
Ammonium sulfite (24, 29, 30 to 58, 93)
Ammonium phosphate (59)
Basic aluminum sulfate (93)
Beryllium sulfate (60)
Potassium carbonate (61)
Potassium sulfite (89)
Selenious acid (62, 63)
Sodium carbonate (64 to 71)
Sodium formate (71)
Sodium hydroxide (69, 73 to 78)
Sodium phosphate (79)
Sodium sulfite (80 to 88)
Sodium thiosulfate (90)
Others (91)
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Table of Contents - Page 3.
c)
d)
Oxidation on ion exchange resins (181, 181a)
Ca talytic oxidation followed by absorption (182 to 199)
X.
Removal of 802 by reduction
a) Reduction with H28 (200-202)
b) Other catalytic reduction of 802 (203)
Chromatographic separation (204 to 2(6)
XI.
XII.
General reviews and economic aspects (83, 89, 126, 138, 152,
155, 166, 185, 192,
207 to 220)
XIII.
Bibliographies (221 to 223)
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A BIBLIOGRAPHY OF SULFUR
DIOXIDE REMOVAL AND RECOVERY
FROM WASTE GASES AND
SULFURIC ACID PLANT TAIL
GASES. 1955-1967. WITH ABSTRACTS
1.
Anon. - 1967. New U.S. Cost Study on sulfur removal. Sulphur (London)
No. 68. Jan. -Feb. 1967. p. 34.
According to Garney. J. R.. pres-/Bituminous Coal Research. Inc., at
the Coal Convention of the Am. Min. Cobgress at Pittsburgh. Pa.. when
coal contains 3.4% S,the stack gas contains 802 3000 ppm., S03 30 ppm
by vol. With stacks 400-800 ft. high. the ground level S02 content in the
atmosphere would be about 0.3 ppm. S02. But the U. S. Public Health
Service has suggested a max. ground level concn. of S oxides to be O. 1
ppm. This requires a coal contg. no more than 1% S. At present. said
Mr. Garney, only 10% of U. S. coal can meet this requirement.
2.
Anon. -1955. Industrial air pollution. Chern. Age 73. 995-7 (Nov. 5. '55.)
A report of the Chief Inspector (in U. K. ) of industrial works for 1954 is
rev iewed. Emission in excess of statutory limits occurred in 24 cases.
Desulfurization by scrubbing was used in a number of power plants. The
chamber-process H2S04 plants showed an average of 1. 84 grains of S03
per cu. ft. of effluent gas. In 15 cases. the statutory limit of 4 grains r
cu. ft. was exceeded. No limits are yet laid down for the acidity of
emissions from contact acid plants. except the provision of the "best
possible means" of control.
3.
Ludwig. J. H.. & Spaite. P. W. (U. S. Public Health Service. Cincinnati. 0.)
Control of Sulfur dioxide pollution. Chern. Eng. Prog. 63, June 1967.
p. 82-86. (Chemico reprint 2764.>
It is estimated that air pollution by S~2 will continue to increase in the
near future and will reach a peak in 19130 at a level almost twice as high
as 1966. S02 discharged into the atmosphere in the U. S. in 1963 is
given in Table 1. (See page -4a- following. )
4.
National Society for Clean Air(London. England). Sulfur dioxide as an
atmospheric pollutant. Report by the Tech. Comm. of the Nat!. Soc.
for Clean Air J London. 1965(?). 32 pp.
A survey of the S02 emissions into the atmosphere in Britain has been
made. and possible means to minimize this emission are discussed.
Table 2 shows the source of S02 pollution in Britain. (See page -4b-
following. )
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TABLE 1
Sulfur Dioxide Emission to U. S. Atmoephere in 1963
Sulfur Dioxide*
Process ~ ~ of Totel
Combustion of coal
Power generation (211.189.000 ton) 9.580.000 41..0
Other combustion (112.630.000 ton) 4.449.000 !2:.Q
Subtotal 14,029.000 60.0
Combu8tion of petroloum products
Residual oil. power generation 650.600 2.8
Re8idual oil. other combustion 3.052.000 13.1
Other petroleum products 1. 115 .OOOH 4.8
Subtotal 4.827.000 20.7
lefinery operations 1.583.000 6.8
S..lting of ore8 1.735.000 7.4
Coke proceuing 462,000 2.0
Sulfuric acid manufacture 451.000 1.9
Coal refuse banks 183.000 0.8
Refuse incineration lOO.OOO -2:!
23.370.000 100.0
. A ..all ..ount of this tonnase i. converted to sulfur trioxide and
sulfuric acid mt8t before discharge to the ataosphere.
.. 10.000 tonsfro.a gas included.
Hote that the largest 8ingle 80urce is the generation of electric
power:
41.oj from coal combu8tion and 2.8~ from residual 011 combustion.
a total of about 4~~.
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Table 2
Estimates or Air Pollution by Sulphur Dioxide
from the Main Uses of Fuels in Great Britain in the Year 1963
FigurtS are ill millions of Ions /0 /he neam/ 0'1 millioll /OIlS for quanti/itS
of fuel and /0 /he neaml 0'0 I million Ions for slI/phllr dioxide
Quanli{y (blcnli{y of Sulphur
of Fuel Dio.tide discharged
Fuel and Class of Consllmer
COAL
Domestic (including miners' coal)
Electricity works" , ,
Railwa}"S , , , , , ,
Industrial and miscellaneous
Coke ovens
Gas works, ,
~'O 0,8:2
,8 2'0-1
4'9 0'14
41,8 1'20
23'S 0,08
2:2'1 0'16
191'1 4'44
COKE
Domestic coke and
smokeless fuels, ,
Blast furnaces
Industrial, ,
other manufactured solid
5'9
10'5
9'3
0'12
small
0'22
25'7
0'3-1
OIL
Domestic
Kerosene" and domestic fuel oils
Industrial
Kerosene, ga~idiesel oil, fuel oils and creosote-
pitch.. .. ..
Road and Rail Transport
Motor spirit, gas/diesel oil, and fuel oils
Marine Craft
Gas/diesel oil and fuel oils
2'1
0'01
30'8(a)
1'48
13'1
0,06
1'1
0'0"
47'1 (6)
1'59
6'37
O\'erall total quantity of sulphur dimtide
~~ "
(4) The "amount of 30.8 million tons of oil is equivalent in heating value to
about 5:2 million tons of coal, which if u;ed for the same purposes would
ha\'e produced about 1'5 million tons of sulphur dioxide, "
(6) The amount of -H.t million tons of oil is equi\'alent to about 80 million tons
or coal, so that the coal equi\"alent ofthc coal and oil consumed (excluding
air transport) in Greal nritain in 1963 w;u about 271 million ton~,
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5.
Rohrman, F.A., & Ludwig, J.H. (U.S. Public Health Service, Cincinnati, 0.)
Sources of sulfur dioxide pollution. Chern. Eng. Prog. !l, Sept. 1965,
p. 59- 63. (See table in reference 3. )
In 1963 more than 23 million tons of S02 were discharged into the atmosphere
of the U. S. The power plants are the cfiief culprits of this unfortunate
situation, accounting for over 40% of the total emission.
6.
Rohrman, F. A., Steigerwald. B. J. & Lud~g, J. H. (U. S. Public Health
Service, Cincinnati, 0.) Power plant and other sulfur dioxide emissions
1940-2000. Paper presented at ASME-IEEE National Power Conference,
Albany, N. Y. Sept. 19-22, 1965, 5 pp. (Chemico reprint 2925.)
S02 emissions in the United States in 1963 are presented. Emissions during
the period 1970-2000 are forecast. Under conditions of present control
practices the emissions during the next 30 year would be as shown in Table 3.
7.
U. S. Public Health Service. Atmospheric emissions from sulfuric acid
manufacturing processes. U. S. Public Health Service, Environmental
Health Services, Air Pollution. Publication No. 999-AP-13. 1965, 127 pp.
U. S. Govt. Printing Office, Washington, D. C., $0. 60. (Chemico reprint 2908.)
U. S. has about 163 contact H2S04 plants and about 60 chamber H SO plants.
The primary emissions from the chamber plants contain S02 OJ-B. 2%,N oxides
(mostly N02) 0.1-0. 2%,and H2S04 mist 5-30 mg. Iscf. 90% of the mist is
larger than 3 microns in diameter. Equipment for reducing the emissions
beyond the Gay Lussac tower is rearely employed. Emissions from the
contact plants contain S02 O. 1-0. 5%, S03 0.5 to 48 mg. Iscf.. and H2S04
mist 3-15 mg. Iscf. Electrostatic precipitators, glass-fiber mat or
stainles,s steel wire mesh pads eliminate 94-99. 9% of the mist, but do not
remove S02 or dry SO 3' Some plants use the Cominco process to reduce
the S02 content in the tail gas to about O. 03% in 2 stages of (NH4)2S03
scrubbmg. But Cominco process does not remove H2S04 mist.
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8.
Anon. -1969. Control of air pollution in the U.S. moved forward. Chern.
Eng. 1E., Feb. 24. 1969, p. 38.
The U. S. Dept.' of Health. Education and Welfare issued two air-quality
criteria covering sulfur dioxide and particulates, which states that O. 1 ppm
or more of S02 in the atmosphere over a 24-hour period, and 80 micrograms
or more of particulates per cubic meter of air "may produce adverse
health effects in particular segments of the population. "
9.
Patty, F. A. "Industrial hygiene and toxicology" Vol. II, Chap. 18,
Interscience Publishers, N. Y., 1949.
The tolerances,for man for prolonged exposure have been set at
S02 10 ppm., S03 1 ppm., H2S04 2-10 ppm., H2S 20 ppm.,
(But for vegetables and trees, especially in growing season, the S02 tolerance
is much smaller, about 0.20 ppm. (Katz, M., & Cole, R. J. Ind. Eng. Chern.
42, 2258-2269 (1950).
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Tabla 3
Istimated Potential tor Sultur Dlax:i.c1e Pollution
AMUal Em1ss1on ot Su1!ur Dioxide
SQ1rcos ot Pollu tion ~lIIillions of tons)
(10
196) 1970 1980 1990 2000
Paver Plant Operation (coal and. 10.1 1$.6 )0.3 $1.6 60.7
oil)
Other Combustion ot Coal 4.5 3.9 3.2 2.6 2.1
.
Combustion ot Petroleum Products 4.3 '4.9 5.~ 9.2 8.9.
(excluding pOlleT plant oil)
Smelting at Ores 1.7 1.8 2.1 2.3 2.5
Petro18\1111 RetilJ!lZ7 Opera t10n 1.6 1.6 1.6 1.6 1.6
Miscellaneous Sources. ..!:l ..Q.& M Jk2 0.2
TarAL 23.4 28.6 43.6 65.6 76~0
. Includes coke processing, sulfuric acid plants, coal retu.. banks,
and retuse incineration. .
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10.
11.
Squires~ A. M. (College of the City of N. Y.) Air pollution: the control of
S02 from power stacks~ I-II. Chem. Eng. 74, Nov. 6~ 1967, 260-8;
Nov. 20~ 1967~ p. 133-140.
The hazards of S02 to health and damages to vegetables and trees are
represented graphIcally as functions of S02 concentrations in atmosphere
and duration of exposure. The economics of removing sulfur from fuels
before burning and of removal of S02 from the stack gases of power stations
are discussed.
U. S. Bureau of Mines. Engineering evaluation of processes for sulfur
dioxide removal. Air Pollution Control Project report June 30, 1956,
p. 8-14.
Flue gases resulting from the combustion of coal contain about 0.06%
sulfur dioxide for each percent of sulfur in the coal. Sensitive plants may
be damaged by ID ncentrations exceeding 0.25 ppm. Sulfur dioxide is known
to be a respiratory irritant, and at a concentration of O. 001 % produces
coughing. Methods vb ich may serve- to reduce the sulfur dioxide content
of stack gases include coal preparation treatments and pretreatments.
The cost of sulfur dioxide removal by industrial processes ranges from
1 to 2 dollars /ton of coal consumed.
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12.
13.
14.
Anon. -1967. Further research into flue gas cleaning. Sulphur (London)
No. 1!, Sept-Oct. 1967, p. 29' Chem. Eng. 74, Mar. 27, 1967, p. 43.
In Kangana, Japan, S02 removal by absorption in plain water and sea
water is being tried in a pilot plant. It is reported that with water at pH
= 7, S02 in flue gas was reduced from 13001P> m. down to 80 ppm. But
if water has a pH of 12, the S02 content was decreased to 20 ppm.
Andrian6v, A. P., & Chertkov~ B. A. Ammonia recycle method for the
sulfur dioxide absorption from flue gases. Khim. Prom. 1954, 394-401;
C. A. 49~ 4971 b (1955).
Preliminary information is reported on a process of flue gas purification
from S02 by cooling it with water spray and neutralizing with NH3'
Among tfie problems yet to be solved are the corrosion of equipment and
the efficiency of absorption.
Germerdonk~ R. (Farbenfabriken Bayer AG, Leverkusen, Germany).
Scrubbing out of sulfur dioxide froM flue gases. Chem.-Ing.-Tech. 37,
1136-1139: (Nov. 1965) (Chemico transl. TR-382.) -
(Continued next page)
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Cont'd
14.
15.
16.
17.
18.
19.
An economical method of removing S02- from power plant stack gas is to
scrub the gas with cold water at pH of 1.0 and to drive the S02. out of the
water by red1 cing its pH to 3. 5 by adding H2S0 andblowing WI. th a
steam-air mixture. The desorbed S02 may be ~oncentrated and utilized
in the manufacture of H2S04 or some other product. The water is
neutralized with NaOH and recycled. A process flow diagram is shown.
Jackson, A.. & Solbett, J. M. Sulfuric acid plant tail gas treatment.
Chem~ & Ind. 1955. 1304-1311 (Oct. 15)
(1) Water scrubbing (with S02 stripping from the pregnant water by
using it as a coolant for the Durner gas), (2) NH3 soIn. scrubbing.
and (3) Na2S03 scrubbing are described. Data are given in 8 tables.
25 references.
Johnstone. H. F. and Singh. A. D. Recovery of sulfur dioxide. Industrial
and Engineering Chemistry. Vol. 29, No.3. 1937, pp. 286-297.
The absorption of S02 in water and o~ 5 N NaOH in packed columns was
investigated with respect to packing design. operating conditions, mass
transfer. and heat transfer.
Katz, M.. & Cole. R. J. Recovery of sulfur compounds from. atmospheric
contaminants. Ind. Eng. Chern. 42. 2258-2269 (1950).
Methods of recovering S values from stack gases are briefly described.
The tolerance of S02 in atmosphere for humans and for plants and
vegetables are discussed. At the Battersea power station in London.
England. the flue gas contains 0.02-0.05% S02' Scrubbing with water
from Thames River followed by a scrubbing WIth a slurry of chalk
reduced the S02 content to 20-50 ppm in the gas discharged into the
atmosphere.
Kelly. F. H. C. (Electrolytic Zinc Co.. Risdon, Tasmania). Design and
operation of a counter current gas-scrubbing system. Proc. Australian
Inst. Min. & Met. 152-153 17-39 (1949); C.A. 46. 4281 g (1952).
Roaster gases contg. up to 5% S02 has been treated in a scrubbing tower
through which sea water was circulated. Effluent gas contained only
0.05% S02. The operating variables of the scrubber have been studied.
If unlimited amount of sea water is available, S02 in the gases can be
completely removed.
Kettner. H. (Inst. for Water-Ground & Air-Hygiene, Dusseldorf. Germany).
The removal of sulfur dioxide from flue gases. Bul. of the World Health
Organization (N. Y.)~, 421-429 (1965). (Chemico reprint 2818).
(Continued next page)
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Cont'd
20.
21.
22.
23.
19.
Water scrubbing of flue gas is used by the Battersea power station in
London to remove 70% of the 80 in the flue gas. The scrubbing water is
discharged into Thames River d8wnstream of the power station. 802 in
the scrubbing water is not recovered.
Mirev, D., Elenkov, D., & Balarev, K. Rate of absorption of pure gases.
Compt. rend. acado bulgare scL 14, 263-6 (1961); C. A. 55, 24135 a (1961).
Absorption rates of pure 80 in water were determined in wetted-wall
column and in horizontal com.mn at relative water rate of 30-100 cc/min.
and gas rate of 1300 cc/min. 802 gas pressure was 215 mm. Hg.
Results showed that change in gas velocity do not affect the rate of
absorption of 802 in either the wetted-wall column or the horizontal
column.
Parkison, R. V. Absorption of 802 from gases of low concentrations.
Tappi 39, 522-7 (July 1956); C.A. 50, 13440 e (1956).
The absorption of 80 in water has been studied with 80 concn. in the
gas varied from 0.5 to 1.5%. Results are given in a tab1e and several
graphs.
Potop, 1. P. Reclaiming sulfur dioxide from waste gases. Rev-Chim
(Bucharest) .!l,705-17 (1962); C. A. 58, 13485 h (1953).
Gases containing 0.76-1. 4% 802 resp., were scrubbed with water at
250 -450, resp. and atm. pressure. The pregnant water contained
1. 625-2. 3 g. 802 per 1. The 802 is desorbed by raising the water
temperature.
Whitney, R. P. .& Vivian, J. E. (M.1. T.) Absorption of sulfur dioxide
in water. Chem. Eng. Progress 45, 323-337 (1949); C. A. 43, 4905
a (1949).
Exptl. results on the absorption of 80 in H 0, in a packed tower, are
presented. Over-all coeffs. for 802- a~sorp~ion show all the characteris-
tics of a system where both gas and~iquid film resistances exert an
appreciable effect. They increase markedly with increasing liquor rate,
gas rate, and temp. With the aid of certain assumptions based upon
previous absorption studies, the over-all coeffs. have been broken down
(Continued next page)
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Cont'd
23.
to yield values for the 2 film coeffs. The liquid film coeffs. of this study
are significantly lower than those predicted for the system. As with the
Cl -H20 system. the explanation for this difference appears to lie in the
re!ative rates of diffusion and hydrolysis of the S02 within the liquid film.
Pseudoliquid film coeffs.. calcd. by assuming no nydrolysis within the
film. are in agreement with the predicted values.
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24.
25.
Anon. -1969. S02-_recovery from sulfuric acid plant off-gases.
Sulphur (London)~o. 80. Jan. -Feb. 1969. p. 36-38. 40.
Two processes for the recovery of S02 from the tail gas of H2se 4 plants
are described: I. The Czech process uses aq. NH3 to absorb the S02
followed by a water scrubbing reducing the SO content from 0.25% crown
to 0.01%. The absorbed S02 is liberated by aading RN03. The final liquid
product is concentrated to glve a NH4N03 solution contg. some (NH4)2S04'
The NO content in the recovered SO gas is of the order of 0.05%,
(Cf. Czech Pat. 100 295.) II. The ~omanian process uses a solution of
NH4HS03 to absorb S02 from H2SO4-plant tail gas. The S02 in the
absorbent is liberated oy adding H3P04_and the resultant liquid is
concentrated to give a solution of NH4 H2P03.
Europ. Chern. News l.!.,
Anon. -1967, German systems reclaim S02'
Mar. 10. 1967. p. 34.
Air pollution can be minimized and sulphur dioxide conserved by incorporat-
ing into the design of sulphuric acid plants a double absorption system or a
scrubbing system each developed by Chemiebau Dr. A. Zieren GmbH,
The double absorption system, which is already being used in sulphuric acid
plants in Lenzing (Austria). Antwerp and Magdeburg. is claimed to reduce
sulphur dioxide losses of a 330,000 ton/year plant from 4, 300 ton to
1.000 ton annually,
It is equally suited to recovering sulphur dioxide from off gases having a
high or low concentration of sulphur dioxide.
Water and ammonia are used for scurbbing the sulphur dioxide from the
off gases in the second process. which has been incorporated in sulphuric
acid plants at Rravancore. Geleen, Wesseling. Worms and Zwickau.
One virtue of the latter technique is that it can be used for recovering
sulphur dioxide in the event of a failure in the steam supply putting the
absorption system out of action.
Proportion of sulphur dioxide lost to the atmosphere when off gases from
a 330,000 ton/year plant are purified by scrubbing is said to be reduced
to 130 ton/year,
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26.
27.
28.
29.
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CONSULTING DIVISION
Bergwerksverband zur Verwertung von Schutzrechter der Kohlentechnik
G. m. b. H. (Grosskinsky, 0., Klempt, W., & Adelberger, A., inventors).
Ammonium sulfate from gases with a low S02 content. Ger. Pat. 801,837,
Jan. 25, 1951 (Cl. l2k. 7); C. A. 45, 8728 d (1951).
Gases contg. less than 1 vol. % S02 may be scrubbed with NH40H som. to
recover S02 as (NH4)2S,?4.." The scrubbing som. is maintainecf at pH 4-5.5
in the presence of 50-~2(H:"01d 0 excess based on S02' The flow ratio should
be 120-200 vol. of gas per vol. scrubbing som. which is kept at 60-650. The
S02 loss and NH3 loss are, respl, 0.17% and O. 11% based on total charge.
The effluent gas contains 0.001% SO 2., and 0.002% NH3' The efficiency
obtained in treating a gas contg. O. lUfa S02 is about one-half as high as for
1 % SO 2 .
Furkert, H. & Muehlenbein, H. (to Chemiebau Dr. A. Zieren G. m. b. H.
Cologne-Braunsfeld, Germany). Process for recovering sulfur dioxide and
ammonia from aqueous scrubbing solution obtained from ammonia scr-ubbing
of gases containing sulfur oxides. D.-S. Pat. 3 321 275 (Cl. 23-178) May 23,
1967. (Germ. appl. Dec. 3, 1963).
S_~ in gases is removed by scrubbing with a solution of NH3. The
(NH4)HS04 and {NH4)2S04 formed during the process is separated and
decomposed at 2000F. to recover NH3 which is recycled.
Klimecek, R., Kana, B., Mikulsky, R., & Jara, V. Removal of sulfur
oxides from industrial gases. Czech. Pat. 111 472 (Cl. C 02c) July 15,
1964 (appl. Dec. 8, 1962); C. A. 62, 4948 b (1965).
S02 is absorbed in aq NH3' The resulting NH4H S03 is oxidized to
{NH4)2S04' The latter is treated ZnO Zn{OH'2 or z-nC03 to expel the
NH3' The expelled NH3 is absorbed in water and recycleo to the gas
scrubber.
Slack, A. V. (TVA) Air pollution: The control of S02 from power stacks.
III. Processes for recovering S02' Chem. Eng. 74, Dec. 4, 1967, p.
188-196.
The recovery of S02 in gases by absorption and desorption wi th an aq.
som. of NH was applied by Cominco in Canada to the smelter gases. Its
application (0 flue gases on large scale was first realized in Japan with a
25Mw oil-burning power station. The system was put in operation since
Oct. 1966 by Showa Denko KK. But the Show a Denko system does not
involve desorption of S02' it converts all S02 to {NH4)2S04 which is
recovered as a solid proouct. This simplifies the process and
materially cuts down costs.
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CONSULTING DIVISION
30. Anon. -1967. Czechoslovakia; desulfurization of flue gases using
ammo'nia. Sulphur (London) No. 72, Sept-'Oct, 1967, p. 24-26.
A SO recovery system is in operation in Northern Bohemia,
Czecfioslovakia, based on absorp. with (NH4)2S0 soln. the
installation is at the 100,000 kw power station 50tl, 000 m flue gas per
o 0 0
h. (0 C and 1 atm. ) contg. 0.1 to 0.3 mole % S02 at 140 -180 C. The
absorbers (2 in series) are operated at 500_600. In the case of single
absorbe~ the S02 content of the flue is usually reduczd to 0.01 mole %.
The reduction is more with 2 absorbers in series and the NH3 recovery
is better with 2 absorbers in series.
The pregnant soln. is acidified with H SO to liberate in S02 which is
sent to a H2S0 plant to make the aci~ 1he acidified soln contains
(NH4)2S0 4 whi~h is concentrated and recovered by crystallization, as
a by-product.
The lire cycle" version of the process involves the recycling of an
acidified soln. containing a higher acid~ty in order to drive out SO 2
at less expenditure of steam. Thus recycle is confined to the S02
desorption 'portion of the process. Plastics are used in making part
, of the equipment to circumvent corrosion.
31. Anon. -1955. S0.2 scrubber, two scrubs better than one. Chern. Eng. 62,
Feb. 1955, p. 132, 134; Chern. Eng. News~, 2.148-9 (May 16, 1955).
Olin Matheison Chern. Corp's plant on the Houston Ship Channel, Tex., uses
Cominco process and their own modifications. The H2S04 plant (estimated
capacity 600 tons/day) discharges 2,160,000 SCF gas perno contg. 0.3%
S02' By using (NH4) S03 soIn. in a 2-stage gas scrubbing system the exit
gas contains 0.03% s62' The absorbed gas is desorbed by adding 660 H2S04
to the pregnant soIn. and blowing dried air through it. The effluent gas
contg. a high concn. of desorbed S0.2 is combined with the feed S02 gas just
before the drying tower. By installmg this system the plant production was
pushed up 20%. The cost of the equipment was $340,000 (about 17% of the
total H2S04 plant investment, but it is automatically operated requiring no
added personnel).
32. Atsukawa, M., Nishimoto, Y., & Matsumoto, K. (Hiroshima Tech. Inst.
Japan). Removal of S02 gas from waste gases. Mitsubishi Heavy Inds.
Ltd., Tech. Rev. ~, No.2, 51-57 (May 1965).
Four processes of removing SO from waste gases which are being
developed by Mitsubishi Heavy Jtds. Ltd. are described with flow diagrams:
(1) NH4HS03 liquor process, (2) MnO(OH) slurry process, (3) milk of lime
process, (4) red mud slurry process. For all these processes, an inlet gas
contg. S02 O. 1-0.2%, for the pilot plant tests was used. For processes (1)
and (2) the removal efficiency was of the order of 97% and for processes (3)
and (4) it was about 90%. Processes (2) and (4) requi red higher liquid/ gas
ratios. '
- 11-
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34.
35.
36.
~~~~~
CONSULTING DIVISION
33.
Bergwerksverband zur Verwertung von Schutzrechter der Kohlentechnick
G. m. b. H. (Grosskinsky, 0., Klempt, W., & Adelberger, A., inventors).
Ammonium dioxide content. Ger. Pat. 801,837, Jan. 25, 1951 (Cl. 12k. 7);
C.A. 45, 8728 d (1951).
Gases contg. less than 1 vol. % S02 may be scrubbed with NH 4 OH soln. to
recover S02 as (NH4)2S04' The scrubbing soln. is maintained at pH 4-5. 5
in the presence of 50-l.20-fold OJ excess based on SO. The flow ratio
should be 120-200 vol. of gas per vol. scrubbing sofn. which is kept at
60-650. The S02 loss and NH3 loss are both low, i. e., 0.17% and
0.11%, resp.; for an original gas contg. 0.1% S02' the loses are 2.2%
and O. 69%, resp.
Bettelheim, J., Frantisak, F., Derka, J., & Klimecek, R. Sulfur
dioxide from industrial waste gases by ammonium cyclic method.
Czech. Pat. 114 564 (Cl. C -016) May 15, 1965 (appl. Sept. 4, 1962);
C. A. 64, 15440 a (1966)
In the process of recovering S02 from waste gases using (NH4)2S03
as the absorbent. It is specifiea that the waste gas is first cooled to
below 450 C. The condensate separated at this temp. is used to scrub the
gas to remove dust. The (NH4)2S03 solution is allowed to build up its
(NH 4 )2S0 4 content until the lafter compoun~ crystallizes upon cooling.
P- shp -stream of this solution is then processed to recover (NH4)2S04'
Bettelheim, J., & Klimecek, R. Absorption of sulfur dioxide in an
unpacked column with jets. Chem. Prumysl (Prague) ~ (6). 281-4
(1960); C. A. g, 10338 n (1964).
The absorption kinetics of S02 in aq. (NH4)2S03 in an unpacked column
with jets of the absorbent was studied. It is concluded that although there
is no liquid film such as on the surface of packing elements, the
diffusion resistance of the liquid to the absorption of S02 cannot be
neglected since there is still a film of more c onc. soln. of S02 around
each liquid drop of the absorbent. .
Burgess, W. D. (The Consolidated Min. & Smel. Co. of Can. Trail, 1
B. C.) S02 recovery process. Chern. in Can. ~, No.6, 116-120 (1956);
d. U. S. Pat. 2 862 789 (1958).
At T~ail at different times there was the necessity of .recovering S02 from
gases contg. about 1 % S02' The process which has been developed and.
used for many years uses an aq. soln. of (NH4) S03 + (NH4)H SO to
absorb S02. Aq. NH3 is continuously added to fuat soln. to mainrain its
absorptive power. A portion of this soln. is acidified to recover S02 in
the pure form. The S02 is either fed to the gas in the H2S04 plant or .
(Continued next page)
~ 12 -
-------
Con t' d
~~ <;!'~ ~~
CONSULTING DIVISION
36.
liquified and sold. The acidified soln. eventually builds up in (NH 4)2 SO 4'
which is crystalli zed and separated 'as a by-product. The mother 11quor
is recycled after correction of pH value by adding aq. NH3' Material
balance and heat balance are tabulated.
37.
Chertkov, B. A. p-PheJ?yldiamine as an inhibitor of oxidation of
ammonium sulfite-bisulfite solution. Zhur-Prikl. Khim. ~~, 952 -960
(1952); C. A. 53, 15499 c (1959).
Oxidation of dust-free (NH4)2S03 / NH4HS03 solns.with air was reduced,
several-fold by the presence of O. 5-3. 0 g./I. of p-phenyldiamine. The
effect of the latter compd. is not diminished in the presence of O. 25M
thiosulfate. However the effectiveness of p-phenyldiamine as an
oxidation inhibitor is impaired by a deficiency of NH OH. There is an
optimum S02/NH3 rat io for the circulating soln., w~ich is about 0.75.
When this ra~io is larger than 1. 0, oxi~ation of S02 became rapid after
200 h. of operation. The presence of fly-ash in the flue gas also
impairs the effectiveness of p-phenyldiamine. '
38. Craxford, S. R., Poll, A., & Walker, J. S. Recovery of sulfur 'from flue gas
by the use of ammonia. J. Inst. Fuel 25, 13-14 (1952); C. A. 46, 2267 d (1952);
cf. Trans. Inst. Chern. Engrs. (London)~, 43-51 (1945).
b. the Simon-Carves process of scrubbing flue gas with NH3 soln., the
chief difficulty was the proper control of the concn. of the scrubbing
soln. It was found later that the presence of MnS04 or Fe oxide
stabilizes the compn. of the soln. The introduction of the electrical-
conductivity vapor-pressure recorder (Brit. Pat. 633,627, Mar. 18,
1950) also helped in ma intaining the proper composition so that the
NH3 loss as vapor was at the min. and S02 remova! was 99%. The
scrubbed flue gases contained only O. 005% S~. The spent liquor was
treated in an autoclave at 1900 with H2S04' ElemeIftal Sand (NH4)2S04
were produced. On the basis of results from the 1000 cu. ft. per nr.
plant, a 25,000 cu. ft. per hr. plant was built and is now in operation at
the Fuel Research Station (in England).
39. Edge, H. A. (to Imp. Chern. Inds., Ltd., England) Recovery of S02'
U. S. Pat. 2 589 684, Mar. 18, 1952.
The gas contg. SO is scrubbed with an aq. sOln., of (NH4) S03 and
NH:1HS03 in whichqhe S02 is absorbed. The S02 may be l1berated by
addmg HN03 in excess.
- 13 -
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~~ ~~~~
CONSULTING DIVISION
40. Ganz, S. N. Kuznetsov, 1. E., & Podgaiko, V. V. Sulfur dioxide removal
from gases to obtain ammonium sulfate. Khim. Teckhnol. Resp.
Mezhvedomstv. Nauchn. -Tekhn. Sb. 1965 (2), 47-52 (in Russian); C. A.
65, 14896 c (1966).
The gas contained less than O. 25% S02' and the scrubbing soln. was a
strong (NH4.)2SO~1 soln.containing less than 1% free NH3. This soln.
had a capacIty 01 absorbing 580 g. SO?Jer liter of soln. This is about
800 times better than plain water at 25. In the presence of air or ° ,
the turbulence of circulation caused oxidation of (NH4)2S03 to (NH4)2~04
which was recovered as a fertilizer.
41. Gerrard, J. S. (to Simon-Carves Ltd., England). Production of ammonium
sulfate. U. S. Pat. 3 186 792; 3 186 802 (Cl. 23-119; CL 23-260) June 1,
1965 (appl. Mar. 2, 1961.)
The (NH ) SO liquor from the scrubbing column for the removal of 80
from wa~t~ ga~es is acidified with H SO and heated under pressure in The
presence of air to convert the (NH ) ~6 4 to (NH4)2S04 which is subsequently
b 4 2 11,3 t'
concentrated and recovered y crysta lza IOn.
42. Hien, L. B., A. B. Phillips, and R. D. Young. Recovery of Sulfur
Dioxide from Coal Combustion Stack Gases. Chapter 15. In Problems
and Control of Air Pollln. New York, Reinhold, 1955, p. 155-169.
DLC (TD883. 15, 1955)
This report discusses data obtained in pilot plant studies of the recovery
of sulfur dioxide, in usable ,form, from coal combustion gases. The
sulfur dioxide was absorbed in ammonia solution. The major variables
studied were recirculation rate, pH, and concent:ra tion of the scrubbing
liquor and the depth of packing and gas velocity in the scrubber. These
st udies were made at the laboratories at Wilson Dam, Alqbama as a
part of work conducted by TVA'to evaluate the emissions of sulfur
dioxide from steam plants so as to identify any needed controls. "
43.
Jara, V., Klimecek, R., Kordik, E., & Bettelheim, J. Recovering
sulfur dioxide from combustion gases. Czech. Pat. 99 875, June 15,
1961 (appl. Sept. 3, 1959); C.A. 58, 2190 g (1963).
The hot flue gas is first cooled by contacting mineral oil. The cooled
gas is scrubbed with aq. (NH4 )28"03' The pregnant soln. is regenerated
by heat which comes from direct mixing of hot oil used in cooling the
gas. The oil may be filtered periodically to remove fly-ash.
- 14 -
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47.
~~ ~~9f~
CONSULTING DIVISION
44,"
Johnstone, H. F. (Univ. of Ill.) Recovery of sulfur dioxide from waste
gases. Ind. Eng. Chern. 29, 1396-8 (Dec. 1937).
Data is given on the effect of solvent concentration upon capaci ty and
steam requirements of ammonium sulfite-bisulfite system of S02
recovery fr.om dilute gases. The optimum concn. of (NH )2S03 lor
min. steam consumption has a value less than one-half o~tfie concn, of
the satd. sal t soln, This optimum value is a function of S02 concn. in
raw gas and of operating conditions.
4C5.
Johnstone, H. F. (to Texas Gulf Sulfur Co.) Recovery of sulfur dioxide
from waste gases. U. S. Pat. 2 676 090; Apr. 20, 1954; C. A. 48,
11018 b (1954). -
The gases contg. S02 is scrubbed with an aq. saln. of (NH4-) S03' A
portion of the pregnant scrubbing soln. is acidified with H2.S0 4 to liberate
S02 after which the liquor is concentrated to recover (NH4:hS04' The
remainder of the pregnant scrubbing solution is heated to Cirive" out S02' "
cooled again and returned to the scrubbing column.
46. Johnstone, M. F., & Singh, A. D. (to Commonwealth Edison Co., Chicago,
121). Process for recovering sulfur dioxide from waste gases." U.S. Pat.
2 161 055 (Cl. 23-178). June 6, 1939 (appl. Mar. 24, 1937); C. A. 33,
7500 (b) (1939).
An arrangement of app. is described, and a soln. of (NH4)2S03 and
NH4HS03 to absorb the S02 therein, preheating the soln. contg. ab sorbed
S02' introducing the heateCi soIn. into a regenerator in contact with steam,
condensing the water in the vapors issuing from the regenerator, brir:@ng
the vapors into contact with a portion of the condensate, combining the
portion of condensate with the remainder of the condensate, and returning
all of the condensate to the regenerator at a point below the level of the
regenerated soIn.
Johnstone, H. F. & West, Jr., W. E.(to Texas Gulf Sulfur Co. )
Recovery of sulfur dioxide from gases and production of ammonium
sulfate. U. S. Pat. 2,810,627, Oct. 22, 1957; (CCC Pat. Dept.)
A gas mixt-contg. S02 is scrubbed with an aq. solution of NH in a
3-stage counter-current system from which the scrubbing liqJor is
withdrawn and oxidized by blowing air through it in another 3 -stage
countercurrent system, where the (NH 4 )2S0 is converted into
(NH4)2S04 which is subsequently recovered 5y crystallization.
- 15 -
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48.
~~ ~~W~
CONSULTING DIVISION
Klimecek. R.. Kana. B.. Mikulsky. R.. & Jara. V. Removal of
sulfur oxides from industrial gases. Czech. Pat. 111 472 (Cl C 02c)
July 15. 1964 (appl. Dec. 8. 1962); C'-A. g. 4948 b (1965).
A~ter absorbing. the SO~ in ~q. (NH4)2S03 the pregnant soln, is treated
wIth H2S04 to hbe.rate ~02 In a conc. gas. The (NH 4 )2S0 4 left in the aq.
. saln. IS treated wIth ZnO. Zn(OH) or ZnCO to liberate NH which is
absorbed in H20. The NH3 soln. ~s recyclecr to the SO abs5rber. .
The ZnS04 is recovered as a by-product. 2
49.
Klimecek. R.. Skri-v'3.nek. J.. &. Battelheim. J. (Ustinad Labem.
Czech.) Desulfurizing flue gases. .Staub Reinhaltung Luft 26 (6),
235-8 (1966) (in German); C. A. 65~ 14897 d (1966). -
After comparing the various processes of removing so' from flue
gases. the sulfite process was considered the most adJantageous.
A packed column for this process was designed.
50.
Kohl, A. L., & Riesenfeld. F. C. (The Fluor Corp.) Gas purification.
Chern. Eng. 66, June 15. 1959, 125-178.
SO is absorbed. according to Comineo process, in a soIn. of.
(NI14) S03' The latter is treated with H2S04 to cause S02 to desorb
leavmi bellind (NH 4) 2S0 4 which is recovered by crystallization.
McCabe. L. C. Atmospheric pollution. Ind. Eng. Chern.. 43, No.8,
8 3A . ( 1 9 5 1 ) . .
51.
The success of the Simon-Carbes process (Bri. Pat. 525.883 (1940),
and 633.627. (1949) depends upon close control of the soln. compn.
which consists of (NH~2S04 28-34%. (NH4)2S030-6%. NH4HS03
0.75-5% and (NH4)28 03 4-11%. In order to keep (NH4)2803 within
limits the presence 01 an oxidizing catalyst is necessary; Mn804 or
Fe(OH)3 may be used fO,r this purpose.
52. Office National Industrial de l'Azote (Cluzel. J.. inventor). Fixation and
recovery (as ammonium sulfate) of waste sulfur dioxide in industrial
effluent gas. Fr. Pat. 1 388 690 (Cl. C 016, c. F 23j) Feb. 16. 1965.
(appl. Apr. 29. 1963); C.A. 63. 3930 c (1965).
In the recovery of 802 with aq. (NH4)2S03 as absorbent. the latter is
maintained at pH 5. 3-5. 7 by constantly aading NH3' The gas fed to the
absorber contains 0.2 -0. 6% 80~ and the gas commg out of the absorber
contains less than 0.020/0 802' ~he pregnant absorbent contains
(NH ) 804 134.5 g.. (NH4~03 52.9 g.. NH4H80,3141. 7 g. per liter. A
slip~s1ream of the pregnant absorbent is treated with H2804 to pH 1. 5 to
liberate 802 with the aid of, a strong current of air. The S0-2 free liquor,
is evaporated to a concentr,~tion at which (NH4)280 4 crystalIizes upon
cooling. The (NH4)2804 is then recovered as a solId product.
- 16 -
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~~ ~~~~
CONSULTING DIVISION
53.
54.
56.
Petersen, H. Removal of sulfur dioxide from industrial gases. Neth. Pat.
Appl. 6516 530 (Cl. C 01b) June 20, 1966 (Ger. Appl. Dec. 19, 1964;
Apr. 28, 1965); C.A. 66, 4549 y (1967).
S02 -contg. gases are mixed with NH3 and water vapor and sprayed with an
aq. soln. of (NH4)2S03 or NH4HS03 fo sep. the formed (NH4)2S03 fog from
the gas stream in a 2-step mech. separator of the Petersen type, having a
pressure drop of 80-350 mm. water column. The treated gases contain
<0.02 vol. % S02' In the 1st step of the separation" gases contg. 5-10 g.
S02 (and some S03)/rn.3 and having a temp. of 50-600 are together with
steam brought into contact with (NH4)2S0~ or NH4HS03 soln. at 30-400 and
a pH of 4. 6-5.4 to remove ~50% of the 5'02' The sulIite soln. is
recirculated after addn. of H2S04 in a degasifier to drive out the S02 while
elevating the temp. 30, and sepg. soUd (NH4)2S04 in a classifying
crystallizer while decreasing the temp. 3°.. By using a 2 -step degasifier
pure S02 gas can be obtained. In the 2nd step of the separation, the gases
together with NH3' air, and steam are sprayed with sulfite soln., which
is recirculated by a classifying crystallizer during cooling by 30. For
each m. 3 starting gas, 1-4 g. steam is used. Solid (NH )2S0 is obtained
without evapg. the sulfite soln., while comparatively litt1e NJi33 is used.
Popovici, N., Potop, P., Brindus, L., & Anghel, P. Design of an
installation for retaining of 802 -containing residual gases in a plant of
complex fertilizers, under economically advantageous conditions. Rev.
Chim. (Bucharest) g, (1), 40-41 (1967) (in Roma:lilian); C. A. 66, 115
001 f (1967).
The tail gas from H2S04 plants are scrubbed wi th a solution of (NH4)2S03
which absorbs S02' The pregnant solution is treated with dil. H3P0...4 ana
by blowing air through the acidified solution, a gas containing 10-15u/o S02
is recovered. The acid solution is sent to the H3P04 plant or to the
phosphate fertilizer plant. A high rate of tail gas flow through the
scrubber favors absorption coeff. The mist of the (NH4)2S03 solution
created by this high flow rate is recovered by adding a prain -water
scrubbing column.
55.
Simon-Carves Ltd. Recovering (~4)2S0 4' Brit. Pat. 1 031 724
Europ-Chem. News g, July 22, 1966, P 4~. d. Belg. Pat. 632 077,
Sept. 2, 1963 (Brit, Appl. June 18, 1962); (C. A. 60, 12920 d (1964).
An apparatus is specified for the oxidation of ammoniacal soIns. contg.
xoides of S washed out of combustion gases to yield (NH4)2S04'
Vasilenko, N. A. Ammoniacal-acid methods for enriching weak sulfur
dioxide gases with nitric and phosphoric acids or their manufacture.
Bolshoi Dzhezkazgan Dobycha; Pererabotka Rud. Sb. 1963, 434 -443;
C. A. g, 3958 g (1964). -
!he S02 in g.ases is absorbed in aq: (NH4)2S03' The pregnant soln..
IS treafed WIth HNO 4 or H3PO 4 to lIberate the 80 , thus avoiding the
use of H2S04' A byproduct oINH4 N03 or (NH4 )21fPO 4 is produced.
- 17 -
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58.
59.
~~ ~~~~
CONSULTING DIVISION
57.
Volgin. B. P.. & Maron. F. S. Absorption of carbon dioxide and sulfur
dioxide in Venturi scrubber. Soobshcheniya 0 Nauch-Tekh. Rabot..
Nauch. Inst. Udorbren. & Insektofungisidov 1958 No. 6-7. 118-137;
C.A. 55. 10995 c (1961).
The results of expts. on the absorption of C02 by a Na2C03 soln. and
S02 by solns of (NH4}2S03-NH4HS03 and Cr203 are cifed. The Venturi
scrubber can be useCl successfully for absorption of easily soL gases at
high concn. in a gaseous mixt. Of practical'interest are the absorption
of S02 by a soln. of (NH4)2S03 -NH4HS03 and of S03 by H2S04.:- A high
percent recovery is attamed by absorption in several steps. With
absorption of difficultly sol. gases. an increase of the gas velocity into
the throat has ,more effect than an increase of the sp. consumption of
liquid. but with absorption of easily sol. gases an increase of sp.
consumption has more effect. During the process of absorption. the
sp. consumption of :!quid must be several times greater than for dust
collecting. The concn. of the absorbable component m the gaseous
mixt. influences the degree and coeff. of absorption considerably.
'Woollam, J. P. V.. & Jackson, A. Removal of oxides of sulfur.from
exit gases. J. Soc. Chern. Ind. 27, 43-51 (1949); Trans. Inst. Chern.
Eng. 23, 43-51 (1945);C. A. 43, 1882 e (1949).
- -
Gases contg. S vapor and 8 oxides are scrubbed with an aq. soln. of
(NH.4 )r:SO , (N~ )280 and (N~ 4 )SO at pH 5 -7. The solution is
perlOdlcal1y rem1orce~ by addmg Nit OH. A portion of the pregnant
soln. is autoclaved to convert 803 into SO 4' .
Some elemental 8 is also formed in the autoclave. The latter and
(NH4)2S04 are removed and the mother liquor is reused as scrubbing
soln.
-
-------------------------------------------------------------------------------
Averbukh, .T. D., Bakina, N. P., & Te.lepneua, A. E. Ammonia-
phosphate method of sulfur dioxide enrichment. Trudy Ural. Nauch.-
Issledovatel.' Khim, Inst. 1958. No.7. 150-170; C. A. 55, 7772 a (1961).
The recovery of ~92 by absorption and desorption in aq. solns. may be
carried out with ~4H2P04 solns. as well as with NH4HS03 solns.
The NH4H2P04 may be more expensive and the process may consume
more steam, Dut there is less oxidation of 802 to S03 in the NH4 H2PO 4
soln. . .
-------------------------------------------------------------------------------
- 18 -
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60.
rc~ w~ CC~
CONSULTING DIVISION
S. A. des manufs. des glaces et prod. chim. de Saint-Gobab, Chauny et
'Cirey. Recovery of sulfur dioxide. French Pat. 974 179, Feb. 19, 1951;
C. A. 46, 11608 c (1952).
S02 is absorbed in an aq. soln. of basic Be sulfate from which SO is
recovered by heating in vacuo. ~ soln. contg. BeS04 4H20 435:g. 71. ,
and BeO 109 g. /1. will absorb 186 g. S02 per 1. of soln. at 200 from a
gas contg. 4% S02' or 196 g. S02 from a gas contg. 7% SO. The BeO
used in this soln. is less than that required to saturate the 2soln. To
eliminate the small amount of H2S04 formed in the process, CaO, BaO
or similar oxides may be added. Basic Al sulfate may be added to the
Be soln.
---------~-_.-._----------------------------------------------------------------
61;'
Bodoni, D.. (to Bodoni & Co. C. m. b. H.) Recovery of carbon dioxide
and sulfur dioxide from combustion gases. Austrian Pat. 174, 896
May 11, 1953; C.A. 47, 7780 f (1953).
Gases contg. C02. and S02._are scrubbed with an aq. soln. contg.
N (0 Et)3' NH2 (OEt) and1<2C03 in the ratio 2:2: 1 in which th~ CO
and S02 aissolves. The pregnant soln. is regenerated by heat ing ~o
liberate C02 and S02. Recoveries of 95-98% of the C02 and S02 in
the gases can be maae.
------------------------------------------------------------------------------
62.
Badische Anilin-& Soda-Fabrik A. G. (Wolf, H., Goesele, W., &
Schachemeier, G., inventors). Removal of sulfur dioxide from exhaust.
gases. Ger. Pat. 1 204 770 (Cl. F 23j) July 3, 1963 (appl. Nov. 11,
. 1963); C. A. 64, 5671 b (1966).
The removal of S02. by the H2Se03 process is specified. An example is
given: 360 liters 01 waste gas contg. 0.2% S.02 was s.crubbed with 1. 31
liters of 30% H2SO4- contg. 2. 5% Se02 by wt.lI1.-Ventun scrubber at a
liquid velocity of 2'56 liters/h. In 211. the Se (3.25 g. ) ppt. was filtered
off. The H2S04' increased in concentration. A slip stream corresponding
to 5.75 q H2S04 was removed and replaced with water. The Se is oxidized
with air to se02 and returned to the scrubbing soln.
Norddeutsche Affinerie (Emicke K., inventor). Removal of sulfur dioxide
from flue gas. Belg. Pat. 665 484 Oct. 1, 1965 (Ger. Appl. June 18,
1965 (Ger. Appl. June 18, 1964); C. A. 64, 19041 a (1966).
63.
Flue gas is first cleaned of dust with an electrostatic precipitator. It is
then scrubbed with an aq. soln. contg. H2Se03 42 g/l and H2S04 77 g/l.
The reaction: 2S02 + Se02 -- 2S03 + Se taKes place. The Se is filtered off
and processed to regenerate H2Se03' A slip stream of aq. soln. is
concentrated to recover H2S04'
------------------------------------------------------------------------------
- 19 -
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65.
'G~ ~~ C;f~
CONSULTING DIVISION
64.
Blasinski, H., & Ignaczak, W. (Politech. Lodz. Poland). Absorption of
sulfur dioxide by sodium carbonate aq.soln. from a gas mi.xture (air-
sulfur dioxide). Przemysl Chern. 45 (7), 374-8 (1966) (in Polish);
C. A. 6~. 14876 a (1966). - .
Air contg. 0.1775-0.7880% S02 was scrubbed in a packed column with a
spray of aq. Na2C03 at the top. The removal of S02 was 90.5-99. 9%
complete. .
Fleming, E. P. & Fitt, T. C. (to Am. Sme!. & Ref. Co.) Sulfur
dioxide recovery. U. S. Pat. 2 399 013 Apr 23, 1946; Brit. Pat.
598 283 Feb. 13, 1948; C. A. 40, 7538 (5) (1946); d. U. S. Pat.
2 295 587 Sept. 15, 1943; C.A. 12, 1234 (3) (1943).
The S~ in a gas is absorbed by anhy. dimethylaniline (DMA) so that
the effruent gas still contains a small.amount of S02; the effluent gas
is next scrubbed with an aq. soln. cf Na2 C03 to remove the remaining
SO. The residual gas containing DMA vapor is scrubbed with aq.
H2?S0 4. The 3 scrubbing solns. are separately regenerated so as to
recover pure SOd' and the solvent. The latter is separated from the
H2S04 soln. b!. .~sti~l~tion. - . .._-
6'6. Jara, V., Bettelheim, J., & Skrivanek, J. Regenerating absorption
solution used for trapping sulfur dioxide from industrial refuse ex-
.halations. Czech. Pat. 106 240 Jan 15, 1963 (appl. Nov. 12, 1961);
C.A. 60, 6524 f (1964).
The SO contg, gas is scrubbed with aq. Na2C03 which is trans-
formed2to NaHS03 by the S02' The S02 is liberated from NaHSO
by adding H2S04' The soln. is neutrahzed with Na2COg' and Na2~04
is recoverea in solid form. The N':2S0..A is reduced wIth coal or cOKe
at 6000_11000 forming amolten Na2S-: The Na2S is dissolved in
water. The water soln. is contacted with C02 to liberate H2S, The
H2S and recovered S02 are put through the Claus process to recover
elemental S. The Na2-c0g soln. i~ recycled.
67. Johnstone, H. F., et al. (Univ. of Ill.) Recovery of sulfur dioxide from
waste gases. Ind. Eng. Chern: 30, pp. 101-9 (1938).
Fig. 2 shows the capacity of Na2S03 -NaHS03 solutions for recovery of
S02 from gases contg. O. 3% S02 at absor8tion temps6 of 350, 450 and 550
resp., and desorption temps. of 700, 80 , 900, 100 and 1200. The
capacity is defined as the difference between SO concn. in solution
leaving absorber and that from the regenerator 10r a constant concn. of
a. base, in this case, Na2C03. Max. efficiency and min. steam require-
ments with the same temp. parameters are given. .Similar data for
methylamine sulfite solutions are given in Fig. 3. The use of Na or
methylamine sulfite soln. for recovery of S02 requires larger quantity
of steam for regeneration than the use. of ammonium sulfite soln.
but the Na or methylamine sulfite soln. permits the use of high
temperatures for regeneration, thereby obtaining a more complete
desorption of S02.
- 20 -
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CONSULTING DIVISION
68.
69.
70.
Kopita, R., & Gleason, T.G. (Peabody Eng. Gorp. N.Y., N.Y.) Wet
scrubbing of boiler flue gas. Chern. Eng-Prog. 64, Jan. 1968, p. 74-78.
A wet scrubbing system can be designed to remove 99+% of the fly ash
from the stack gas and also 70-99. 5% of the S02 in the same gas (70%
by using'plain water and 99.5% by using aq. Na2C03). Such a system
would be economical to use, compared to the alternative of using
extra -ldw -S fuel.
Sakol, S. L. & Shah, 1. S. (Chemical Construction Corp. ) Removal of
sulfur dioxide from clay kiln exhaust gases. Chemico Brochure, 1968,
10 pp.
In the ceramic industry, the waste gases from the kilns contain an
appreciable amount of S02. To eliminate air pollution due to this S02'
Chemico has developed a scrubbing system using as absorbent an aq.
solution of NaOH or Na2C03 or a slurry of quick lime (5%) in a Venturi
scrubber. For a capacIty of 10, 000 SCF / min., waste gas, the
equipment cost is estimated at $47,000, and operating cost $14,250 per yr.
Skrivanek, J., & Cada, V. Absorption of sulfur dioxide in a Venturi
tube. Chem-Prumysll, 340-3 (1957); C. A. g, 14993 i (1958).
Absorption of sulfur. dioxide in a Venturi tube. Expts. with absorption
of a gas contg. 0.2% S02 in Na2C03 solu. in a Venturi tube were
arranged in a factorial manner 15asea on statistical methods, and the
degree ,of absorption and the pressure drop were followed. An equiation
is presented correlating the processing conditions. The efficiency of
absorption incrp.ased with the velocity of the gas. At the optimum
conditions an absorption of 68% at a pressure drop 610 mm. H20 is
reported.
& Zapryanova, A. Extraction of
Khim. Ind. (Sofia)~(1), 3-5
q 1. TrendafeIov, D., Ponyankov, B.,
sulfur dioxide from smoke gases.
(1963); C. A. . 59, 6892 e (1963).
Absorption of ~02 byaq. Na2C03 in a recovery system can be
complete at 50 .
---------------------------------------------.----------------------------------
.-
72. Nakazono, T. (to Furukawa Kogyo K. K.) ;Recovering sulfur dioxide.
Jap. Pat. 172,814, May 31, 1946; C.A. 43, 7201 f (1949).
An aq. soin. of an alkaline earth or alkali salt of HCOOH is used as
the absorbent for SO. The SO is recovered by heating the aq. soin.
The latter is then re~ycled to t~e absorber.
- 21 -
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CONSULTING DIVISION
73.
74.
---.- -
Anon. -1969~ Chemico looks at sulfur recovery. Europ. Chern. News
lit Feb. 28. 1969. p. 26.
The various processes for the removal and recovery of S02 from waste
gases are briefly described and their economics are discussed. Among
several proprietory processes mentioned is the one used by Stone and
Webster Co. which uses caustic soda to absorb S02 resulting ~aHSO~ in
the pregnant solution. The S02 is then stripped from the solutlOn an
recovered.
Anon. -1969. Kureha Chemical create desulfurization technique. Japan
Chern. Wk. .!.Q~ Jan. 23~ 1969. p. 1: Chern. Eng. 76. Feb. 10. 1969. p. 38.
Under construction is a desulfurization unit at Kureha's power generating
plant at Nishki~ Fukushima Prof. capable of treating 330.000 cu. m. gas
~r h. producing 18.000 tons Na2S03 per yr. consuming 680 Kg NaOH
per ton of Na SO reocvered. Removal efficiency is 950/0.
2 3
75. Franz. M.. & Klimecek. R.
gases. Czech. Pat. 110 995
C.A. g. 14233 d (1964).
The S02- is absorbed in aq. NaOH. The pregnant soln. is acidified
with H2"s04 to pH of about 1. 0 to liberate S02' The resulting
Na2S0 4 soln. is partly electrolyzed to recover NaOH and H2S04
separately. The NaOH and H2S04 are rec~led, resp.
Processing sulfur di:}xide from combustion
May 15, 1964 (Appl. July 22. 1961);
76. Germerdonk. R. (Farbenfabriken Bayer AG. Lieverkusen. Germany).
Scrubbing sulfur dioxide from the gases. Chem. -Inq. -Tech. 37.
1136-9 (Nov. 1965). -
Data on scrubbing with NaOH solution are given.
71. Spalding. C. W.. & Han, S. T. (Inst. of Paper Chem.. Appleton. Wis.)
Absorption with chemical reaction from a dilute gas in packed towers.
Tappi 45 (3) 192-9 (1962); C.A. 60. 12906 h (1964).
The design procedure and operating characteristics of packed columns
are discussed using water and NaOH soln.. resp.. as absorbents.
78. Takeuchi. N.. & NambaJ Y. (Univ. Hiroshima, Japan). Absorption
of sulfur dioxide. Hiroshima Daigaku Kogokubu Kenkyu Hokoku 12 (2),
241-250 (1964); C.A. g. 15395 e (1964). -
The rate of absorption of S02 in aq. NaOH was measured. The data were
in agreement with the theoretical valued corresponding to the instantaneous.
2nd-order irreversible chem. reaction.
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- 22 -
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CONSULTING DIVISION
79.
Rozie~ M. and Desire~ P. (to Societe Progil, Paris, France). Process for
recovery and use of sulfur dioxide. U.S. Pat. 3431 072 (Cl. 23-165) March
4, 1969 (appl. March 27, 1961).
A scrubbing solution is prepared by neutralizing H3PO A- with Na carbonate.
The tail gas from the H2S0.4 plant containing residual 802 (about 0.2%) is
scrubbed with the Na phospfiate solution which reduces the S02 content to
about 40 ppm. NaHS03 and NaH2PO are formed in the solution which is
withdrawn from the bottom of the sc'I-ubbing column and pumped to the top
of the stripping column where 92% H2S04 is sprayed and mixed with the
S02 -rich solution. Air is blown into the stripping column at its bottom.
The air carries the S02 liberated by H2S04 out of the column at its top.
This air then contains a controlled amount of S02 suitable for use as feed
gas to the II2S04 plant. The liquid effluent from the stripping column
containing ~2S0 4' NaH2P04 and some Na2S04 is sent to the H3P04 plant
as part of the aCIdulating agent for the purverlzed phosphate ore.
-------------------------------------------------------------------------------
81.
80; CederquestJ K. N., Ahlborg, N. K. C., Lunden, B., & Wentworth, T. 0.
Stora sodium-base chemical recovery p.rocess. Tappi 43, 702 -6 (Aug. 1960).
The chemicals recovery system of Stora Kopparbergs Bergslags, A. B. ,
Sweden is described with flow diagram. Briefly the sulfite plup mill and
the sulfate craft mill are integrated. The Na2S0 4 in the waste liquor is
smelted to give C02 and H2S, The H2S is converted to S by the Claus
process. The S together with make-up S is burnt to give S02' The burner
gas is water-scrubbed to give a 2% aq. S02 soln.; the latter is heated to
give a 90% S02 J 10% H20 gas. . The residual S02 in the tail gas from the
water scrubber is absorbed in aq. Na2S03- soln. The latter soln. leaving
the S02 absorption tower contains 70 g/l Na20 and S02' This solution is
used to convert Na2C03 and NaHC03 obtainea from tne smelting step into
Na SO. The latter is adjusted to the proper pH value and sent to the
wo~d-~hip digester. A part of this Na2S03 soln. is recycled to the S02
absorber.
Johnstone~ H. F., Read, H.J., & Blankmeyer, H. C. (Univ. of Ill., Urbana).
Recovery of sulfur dioxide. from waste gases. Equilibrium vapor pressures
over sulfite-bisulfite solutions. Ind. Eng. Chern. 30, 101-109, (1938).
Figure 2 shows the capacity of Na2S03 -NaHSO~ solutions for recovery of
S02 from gases contg. O. 3% S02. at absorption temps. of 350, 450 and 550,
resp., and desorption temps. 01 700, 800~ 900, 1000, and 1200. .The
capacity is defined as the difference between S02 cOllcn. in solution leaving
absorber and that leaving the regenerator for a constant concn. ci a base, in
this case, Na. Max. efficiency and min. steam requirement with the same
temp. parijmeters are given. Similar data for methylamine sulfite solutions
are given in Fig. 3. The use of Na or methylamine sulfite soIn. for recovery
of S02 requires larger quantity of steam for regBneration than the use of
ammonium sulfite soIn. but the Na or methylamine sulfite soIn. permits the
use of high temps. for regeneration, thereby obtaining a more complete
.desorption of S02'
- 23 -
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'Gknued ~~ ~
CONSULTING DIVISION
82.
83.
84.
Johnstone, H. F. & Singh, A. D. (to Commonwealth Edison Co., Chicago,
Ill.) Process for recovering sulfur dioxide from waste gases. U. S. Pat.
2 161 056 (Cl. 23-178) JUne 6, 1939 (appll Mar. 24, 1937). C.A. 33,
7500 (6) (1939).
Apparatus apd process for recovering S02 from dil. gases which
consists in absorbing the S02 in an aq. soln. of Na2S03 and NaHSO ,
treating the enriched soln. with ZnO, removing ppta. ~nS03 from ffie soln. ,
returning the soln. to contact with the gases in a cyclic manner, drying the
Zn sulfite and heating it _to decompn. into ZnO and S02' collecting the S02'
and returning the ZnO for further treatment of the enriched soln.
Johnstone, H. F., & Singh, A. D. (Univ. of Illinois, Urbana). The recovery
of sulfur dioxide from dilute waste gases by chemical regeneration of the
absorbent. Univ. of Illinois Eng. Expt. Station Bul. Ser. No. 324; Univ.
of Illinois Bul 38, No. 19, Dec. 31, 1940, 137 pp; C. A. ~, 2301 (9) (1941);
cf U. S. Pat 2 161 056 (1939).
A commercially workable process for the recovery of S02 from waste
gases is described. The waste gases are scrubbed with an aq. soln. of
Na2S0.1 and NaH2S0..3' The fouled soln. is regenerated by the addn. of
ZnO wnich ppts. ZnSO 2. 5H20 in a well-defined cryst. form which
settles rapidly. The ZnS03 IS dewatered and calcined to liberate the S02-'
When dealing with gases contg. 0.3% S02' the oxidation is approx. 10% 01
the SO absorbed. The SO 4 formed is removed by means of lime. The
cost otthe equipment for a plant treating 100,000 cu. ft. of gas per min.
at 3000F. contg. 0.3% S02 and recovering 21. 7 tons of S02 per day would
be approx. $140,000. ThIS includes mam inery for the liquefaction of the
S02' The fixed charges and operating costs are approx. $15.40 per ton of
S02' The advantages of this process are - (1) The clear, neutral liquid
gives a high rate of absorption and freedom from severe corrosion
difficulties.. (2) The pptn. of the scale-forming salts outside of the scrubber
permits the use of cycline spray scrub bers without danger of clogging of
the nozzles. (3) There is no danger of loss of chemical by volatilization.
(4) Pure S02 is produced. A detailed study of each step in the process
and a flow sheet is given. .
Johnstone, H. F:., and Singh, A. D. . Recovery of sulfur dioxide from
waste gases.. Ind. Eng. Chem. ~, 1037-1049 (1940).
A new process for the regeneration of sulfite-bisulfite solutions used for
absorbing sulfur dioxide from waste gases is described. It is based on the
precipitation of zinc sulfite, followed by decomposition of the dried solid
in a flash calciner to give pure sulfur dioxide and zinc oxide, the latter
being recycled. A thorough study in the laboratory and pilot plant has given
important information on several of the unit operations. The paper includes
a discussion of the design of flash calciners based on the transfer of heat to
particles suspended in gas streams. Data are presented on the rate of oxi-
dation of sulfite-bisulfite solutions in the recovery process from actual plant
operation, and a new flow sheet for desulfation is described.
- 24 -
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~~~~~
CONSU L TI NG DIVISION
85. Lynn. S.. Straatemeier. J. R.. & Kramers. H. (Tech. Hogeschool,
Delft. Netherlands). Absorption studies in the light of the penetra-
tion theory. 1. Long wetted -wall column.. Chem. Eng. Sci. i.
49-57 (Apr. 1955); C.A. 49. 10671 f (1955).
The absorption of S02 by aq. NaHS0;:tsoln. of concns. of O. 196
and 1. 087 N. resp.. was invest igatea. The diffusivity ~ SO:;!! in
the soln. at 200 was found to be 1. 40 and 1. 25 times 10- cm /sec.
resp. The presence of surface-active agent in the ~oln. was found
to have no effect upon the rate of absorption (g. / cm . / sec. ) into
the liquid film. which is a function of diffusivity. Under similar
conditions the diffusivity of S02 into pure water and found as 1. 46 x
10. -5 indicating the mass effect of HS03 upon absorption of S02 in
water. '
8'6. Monev. G.. Tartarski. A.. & Kircheva. N. Purification of flue
gases from sulfur dioxide. Godishnik Nauchnoizsled. Inst.
Khim Prom. ~. 5-20 (1963) (in Gulgarian); C. A. 62 7407 f (1965).
The S02 contg. gas is scrubbed with aq. Na2S03 soln. The pregnant
solution contg. NaHS03 is treated with MgO according to the equation
2NaHS03 + MgO + 5H20-:> Na2S03 + MgS03' 6H20. The MgS03' 6H20
is separated by crystallization ana centrifuging. The mother lIquor
contg. Na2S03 is recycled to the scrubber. The MgS03.: 6H20 is dired
and calcined to liberate S02 and regenerate MgO.. The-S02.1s
suitable for making H2S04' .
87. Wang. J. C.. & Himmelblau. D. M. (Univ. of Texas, Austin). A
kinetic study of sulfur dioxide iri aqueous solution with radio-active
tracers. A.!. Ch. E. Journal1..Q. (4). 574-580 (1964); C. A. g.
8939 g (1964).
In an aq.. soln. of Na2S0a the reaction rate con~tants for forward and
b~ckward .directio~s m S,02 + H2 ° <=""~ H ++ SH03 were deter ~ine8
'wIth the aId of radlO-actlve tracer S-35. Data cover temps 0 -20 ,
and pH 1. 25-4.3.
88. Whitney, R. P.. et al.On the mechanism of sulphur dioxide absorp-
tion in aqueous media. Tappi 36. No.4. April 1953. pp. 172 -175;
C.A. 47. 11727 b (1953). - .
'S02 absorption by aq. Na2S03 soln. was studies using a 4 inch diam. .
24-inch high column of 1-mcn Rasching rings. . The rate of absorption.
was measured at 1000F. and a liquid rate of 3130 lb/ (h) (sq. ft. of
column cross-section). The liquor contained 1. OM Na2S03.. Various
values of S02partial pressures were used. A curve was plotted with
KGa vs. G. (KGa = overall coefficient in lb. males of S02 per (h. )
{cu. ft. ) (atm. ); and G = average overall total gas rate at top and
bott om of column. ) .
----------------------------------------------------------------------------------.
- 25 -
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CONSULTING DIVISION
89.
Anon. -1968. Some det::i Is of the Beckwell process for removing sulfur
dioxide. Chem. Week 103, July 27, 1968, p. 57; cf Belg. Pat. 706-449
(1968).
The Beckwell process is jointly developed by Bechtel Corp. and
Wellman-Lord Eng., Inc. and is based on the absorption of S02 from
flue gases and H2S04 plant tail gases by hot K S03 solution. The
pregnant solution containing KHS03 and very nttle K2SO . A portion of
the pregnant solution is cooled to crystallize K pyrosulfife. The crystals
are separated and heated to convert them to K2S03 with liberation of S02
which is recovered as a pure gas. The K2S03 is recycled.
-------------------------------------------------------------------------------
90.
Keller, J. L. (to Union Oil Co.) Removal of sulfur dioxide from gases
containing the same. U. S. Pat 2 729 543, Jan. 3, 1956.
T.he S02 in a gas is absorbed in a 'solution of Na thiosulfate, buffed to
gIve a pH value of 4-6. The solution after use is regenerated by
contacting H S gas at 400 -1000 so that elemental S is formed. After
removal of Efby filtration the thiosulfate solution is recycled. In the
regenerating step, the solution is taken out of contact with H S gas as
soon as the stoichiometric amount of H2S has dissolved in th~ solution.
-------------------------------------------------------------------------------
91.
Bevans, R.S., Renzi, P.N., and Loonkar, Y.R. (to American Standard
Inc.) Method of removing sulfur compounds. and recovering heat from
combustion gases. U. S. Pat. 3 386 798 (Cl. 23-2) June 4, 1968 (appl.
Nov. 30, 1964).
The scrubbing solution is essentially a soln. of CaC12 and Ca(OH)2'
In order to use it to remove S02 from the hot flue gas from thermal
power plants a concent:6ated (e. g. 35-45%) CaC12 soln. has the advantage
of lower vapor pressure and therefore it can be operated at a higher
temp. The CaS03 thus formed has low solubility; therefore it may be
removed as a solId precipitate by settling or filtration. After circulating
through the hot S02 scrubber, some of the heat c~ntent in the scnubbing
soln. may be recovered by heat exchange with the air going irito the
combustion chamber.
-------------------------------------------------------------------------------
-------------------------------------------------------------------------------
92.
Furufugi, 1. (to Toa Gosei K. K.) Treatment of sulfur dioxide in flue
gas. Jpa. Pat. 174 880 June 6, 1948; C. A. 43, 7201 g (1949).
S02 in flue gas is adsorbed Q1 C particles suspended in water. Example:
a gas contg. O. 7% S02 was scrubbed with a liquid contg. 600 liters of
c dust in 135 cu. m. of water; the effluent gas contained 0.04% S02'
-------------------------------------------------------------------------------
- 26 -
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~~~~~
CONSULTING DIVISION
93.
, Barwasser, J., & Roesner, G. (Lurgi -Gesellschaft, Chemie
Huttenqesen m. b. H.) Obtaining sulfur dioxide from industrial gases.
Reichsamt Wirtschaftsausbau. Chern. Ber. Pruff-Nr. 93, (PB 52008),
1,35-48 (1940) (Pub. 1941); C.A. g, 6374' i (1947).
Processes using H20, basic Al')(S04)3 soln., (NH4.)2S03 soln. as
absorbent are discussed. The "'Sulfidin" process IS specially mentioned.
It uses a 1: 1 or 1: 2 mixt. of xylene and H20 as the absorbent, economy
of this process is claimed. Absorption isotherms are given for S02 in
H20, . basic A12 (SO 4)3 soln and xylene. "
-------------------------------------------------------------------------------
94. Bergars, D. J'. (to Imp. Chern. Inds. Ltd.) Treatment of gases with
liquids. Brit. Pat. 680868 Oct. 15, 1953; C.A. 47, 4664 f (1953).
Flue gases from coal or oil-fired furnaces have been treated with a
slurry of Ca(OH)2 in a tower packed with layers of bars. ' The
efficiency of S02 removal was 960/0. . . ,', . '
. ,
, . .
95. Lessing, R. (to Imp" Chem~ Inds. Ltd.) Purifying combustion gases
containing oxides of sulfur; U. S. Pat 2 080 779 May 18, 1937; C. A.
~, 5138 (9) (1937). .
Aq. CaC03 slurry is used as S02 absorbent.
96. Nakagawa, S. Removal and utilization of sulfur dioxide in stack gas
by the JECCO process. Ryuson~, 211-8 (1963); C. A. 60, 10251 c
(1964). (cf. ref. 213).
The JECC.o process uses either (NH4)2S03 or milk of lime as the
absorbent for S02' and recovers (NH 4 '2S0 4 or gypsum, resp., as
product. .
.9{7. Nonhebel, G. et al. (to Imp. Chern. Inds. Ltd.) Purifying gases from
the combustion of sulfur contg. fuels. U. S. Pat 2 090 142 Aug. 17,
1937; C.A. ~, 7231 (5) (1937). '
The gases contg. S oxides is scrubbed with an aq. soln. contg. milk
of lime. The operation yield CaS03 and CaSO 4 which ppt. from the.
scrubbing soln. The pptd. CaSO and CaSO ppts. are removed from
the scrubbing sol11. fresh milk or lime is a~ded and the reinforced soln.
is recycled.
98. Shneerson, B. L. et al. Removal of sulfur dioxide from flue gases.
Russ. Pat. 50 446 Feb. 28, 1937; C. A. ~, 8894 (7) (1937).
About 50% of the S02 is oxidized to S03' the rest is absorbed in aq.
Ca(OH)2' The CaSu3 soln. thus formed is treated with H2S04 formed
by oxidation to separate S02 from CaS04'
!'
- 27 -
i
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~~ <;f"~ ~
CONSULTING DIVISION
99.
Tennessee Valley Authority. Sulfur dioxide removal from power plant
stack gas: use of limestone in wet scrubbing. National Air Pollution
Control Admin. Report, 1969, 104 pp. ; PB 183 908, clearinghouse,
Springfield, Va., $3.00
powgered limestone (or dolomite) may be injected into the fire box of
a power plant boiler, or may be fed into the water in a scrubbing
system. Each of these methods has advantages and disadvantages;
but the most important considerations are that the injection method is
simpler and less costly to operate, and that the slurry scrubbing
method removes S02 more completely (> 900/0 vs. 50- 600/0). ,:The lime-
stone injection with no subsequent scrubbing but with a dry dust removal
system does not appreciably lower the stack gas temp. On the other
hand, any wet scrubbing would reduce stack gas temp. to the saturation
temp. (about 1250F) and would require reheating of the flue gas to
prevent visible vapor trail from the stack and to prevent great
reduction of plume rise for good dispersion. Neither dry limestone
injection method nor limestone slurry scrubbing method recovers the
S values in the stack gases, and both methods have a solid waste
disposal problem. The scrubbing water can be recycled after settling
out the solids which are mostly CaS04 and CaSO~. Lime m,ay be used
instead of limestone in the slurry scrubbing metfiod. The use of lime
would require a lower liquid rate in the scrubber, but lime is more
expensive and the overall cost of operation is in favor of' limestone.
Capital and operating costs for an installation of a limestone slurry
scrubbing unit attached a 200 Mw power plant are estimated in detail.
Plant layout and equipment specifications are given.
- 27 a -
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CONSULTING DIVISION
100. Wilton, T.O., Wilton, N., Green, H.E.J., & Mann, H.C. Washing
and purifying flue gases. U.S. Pat 2 073039 Mar. 9,1937; C.A.~,
3244 (7) (1937).
SO and 80 in the flue gas are removed in 2 stages. In the 1st stage
th~ gases Jre scrubbed with milk of lime of such concn. as to form
only Ca bisulfate and bisulfite. In the 2nd stage, the liquor from the
first stage is treated with more milk of lime to ppt. the normal Ca
sulfite and Ca sulfate which are removed by settling and filtration. .
------------------------------------------------------------------------------
101.
Babushkina, M. D., Babaev, E. V., & Molchanova, N.1. Preparation of
magnesium -base cooking liq~ors. Bumazhn. Prom. 38, (5), 7-10 (1963);
C. A. 59, 7746 f (1963).
Considering the increasing use of the Mg-base sulfite pulping process, a
study was made of the mechanism of 802 absorption by aq. suspens ions of
MgO, and specifically, of the effect of suspension concn. and of reaction
time on the formation of sulfite-bisulfite soIns. The concn. of the gaseous
802 to be absorbed was kept const. at 11-12%. The MgO suspensions
were prepd. in concns. of 1, 3, and 10% from caustic magnesite (a waste
product of the conversion of magnesite into metallurgical powders), contg.
83-86% MgO and an amt. of impurities within the limits of the standard
specifications. The reaction was carried out to a total concn. of 802 in
the system of 2. 5-5%. The total 802 concn. was detd. only by the reaction
time and did not depend on the COncn. of the MgO suspension. The distribu-
tion of bound 80.2 between the liquid and the solid phase, and the concn. of
bound 802 in som. depended on the con en. of the suspension. In 1%
suspensions, absorption of 802- resulted in the accumulationof bound 80.2
mainly in the liquid phase and the 802 accumulated at a uniform rate. m
10% suspensions, the bulk of the bound 802 was found in the solid phase,
and its accumulation curve showed a max. The reactions in the 3% MgO
suspension had a character intermediary between those occurring in the
1% and the 10% suspensions. At first, only Mg803 was found in soIn.,
then, with crystn. of MgSO , and hence with accumulation of 80 in the
solid phase, Mg803 and Mg1H803)2 were both found in soIn. At the same
time, the COllen. of bound 802 in tfie solid phase began to decrease. In
the 1st phase, up to the crysm. of sulfite, the reaction was similar to
that in 10% suspension, and the 2nd phase co~responded to the reaction
occurring in the 1% suspension. Evidently, in dill. MgO suspensions,
the decompn. of Mg(H803-)2 by excess MgO is insignificant and no super-
aatn. with Mg803 takes place, while this reaction predominates in
coned. suspensions. .
- 28 -
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~~~~~
CONSULTING DIVISION
102. Chertkov, B. A. Mass-transfer coefficients in the absorption of
sulfur dioxide from gases by magnesium sulfite-bisulfite solutio'ns.
Khim. Prom. 1963 (7), 537 -541; C. A. 60 2558 f (1964).
The absorption of S02 from industrial waste gases, contg. 0.25-0.35%
S02 by wt., at 150-700 was studied with an absorber irrigated with a
Mg sulfite-bisulfite soln. contg. suspended MgS03' 6H20 crystals and
some impurities, at pH 5. 1-6.2. The resistance to mass transfer in
the liquid phase was insignificant, and the overall mass -transfer coeff.
was practically equal to the gas-p hase mass -transfer coeef. The
relation between theJ.'T2isselt and Reynolds nos. obeyed the equation
NUg = 0.0035 RegRel . (subscripts g and I designate the gas and
liquid phases. ,resp.) The resistance to mass transfer in the liquid
phase increased with decreasing pH, probably because of the
increased relative concn. of Mg bisulfite..
103. LaBerge, J. C. (Weyerhaeuer Co., Longview, Wash.) Sulfite
MgO system-S02 absorption efficiency improvement. Tappi 46, (9)
538-41 (1963); C. A. 59, 11 005 h (1963).
S02 -contg. boiler flue gases and vent gases enter cooling towers,
the S02 burner gas is mixed with the digester gas, and both pass into
a tower used for fortification of the product acid from the absorption
trains. The overhead gas from this tower is mixed with cooled flue
gas. S02 is absorbed in spray towers with conc~rrent flaw and the
remaining S02 passed into 3 towers with counter current flow. Thesp.
are packed wIth partition rings. The gases are force-drawn through
the towers by draft fans.
104. Lowenstein-Lorn, W. G. (to Standard Oil Dev. Co.) Removal of sulfur
oxides from flue gases and their conversion to ammonium sulfate.
Brit. Pat. 708 09::>, Apr. 28, 1954; C.A. 48, 11033 c (1954).
Gases contg. S02 and S03 are scrubbed .with an aq. suspension of
Mg(OH)2' The spent scrubbing soln. now contg. MgS03 and MgS04
is aerafed and oxidize MgS03 into MgS04' After this operation the
solution is treated with NH3 gas to convert MgS04 into Mg(OH)2 and
(NH4 )2S0 4' The Mg(OH)2 separat ed and used to make a fresh
suspension for scrubbing. T,he (NH4 )2S0 4 soln. is concentrated to
crystallize the (NH4)2S04' . '
105.. Pinaev, V. A. Removal of sulfur dioxide from gases from agglomerat-
ing plants by a method using crystalline magne'site. Vestn. Tekhn. i
Ekon. Inform. Nauchn. -IssI~d. Gas. Kom. Sov. Min. SSR po Khim
1962 (5) 51-56; C.A. 59, 13621 d (1963).
S02 in the waste gases from the sintering plant may be recovered by
,scrubbing the gas with slurry of MgO. The MgO is thereby converted
to ~gS03 which ppts. out as MgS03.6H20. The latter is calcined at
850 -9000 to drive out S02 and regenerate MgO. .
. .
- 29 -
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CONSULTING DIVISION
106.
107.
108.
Potop, P., Creanga, L., & Theodorescu, C. Recovery of sulfur dioxide
from residual gases by wet absorption in two purification steps. Rev.
Chim. (Bucharest) 1:1 (6), 331-6 (1966); C. A. 65, 14896 e (1966).
The gas to be treated contained O. 1 ,to 0.70/0 S02. The 802 was recovered
in 2 steps. The first step was scrubbing the gas with a spray of MgO or
MnO slurry in water. The resulting gas contained 0.01% S02' The MgO
or MnO became MgS04 or MnS04' resp. ~ which was calcinecf to give
MgO and M~03' resp., and a gas contg. 5-8% S02 which could be used
to make H2SU 4. The second step was to take the effluent gas from the
1st-step scruboer contg. 0.010/0 S02 and pass it through a column packed
with active C and sprayed with a soln. of (NH4)2S0~ contg. free NH3 '
(the NH3 fed into the system is approx. equivalent 10 the 802 in the gas).
The effluent of the 2nd-step scrubber contained 0.001-0. OOZ% SO .
(NH4)2S04 was recovered from the scrubbing liquor by concentra~ion
(evaporation) and crystallization. The mother liquor separated from the
" crystals ~as reinforced with NH 3 and recycled to the scrubber.
Ruhrchemie AG. Eliminating sulfur dioxide in gases. Belg. Pat.
628 092, Aug. 6, 1963 (Ger. AppI. March 13, 1962); C. A. 60,
11656 b (1964).
Gases contg. a low concn. of S02. are scrubbed with an aq. slurry of
MgO, Mg(OH)2' MgCO or Mg(HC03)2. , The S02 is oxidized to SO
during absorption so t~at MgSO 4 is formed. Mg(OH) is,regenera1ed by
adding NP3 to ppt. Mg(OH)2. After filtering off Mg(tlH)2 the (NH4)2S04
is recovered from the motfier liquor.
Zalogin, N. H SO from the smoke of electric power stat ions.
Novosti Tekhni~i 11J40, No. 21-22, p. 46-48; C. A. 37, 6413 (6) (1943).
The flue gas contg. O. 350/0 S02 is scrubbed with a water slurry of MgO.
The SO combines with MgO to form solublO MgSO 4 and solid lVIgSO . 6H 0
The lat~er is collected and calcined at 900 to ~ecover S02 and Mg1). ;rhe
MgO is recycled. The MgSO 4 is also recovered as a by-product.
------------------------------------------------------------------------------
109. Anon. -1966. H S04 and Cl2 from waste gas. Europ. Chem. News
..!.Q, Oct. 2 8, 19~6, p. 46; cf. Brit. Pat. 1 041 822 (to Mitsubishi
Shipbuilding and Engineering Co., Ltd., japan.)
Gases contg. S02 is scrubbed with a 300/0 slurry of Mn oxide to absorb
S02 forming MnS-9A. The slurry containing MnSO is treated with HCl to
fO,rm MnCl2._and H2S04. The MnCl is crystalliz~d out of the aqueous soln.
as l};1nCl2. ffi2 O. It is dried, dehy&ated and 2000 and calcined at 5000-
900 to convert it to MnO and Cl gas. The MnO is reused. The H SO
produced earlier in the process ~s used with NaCl to produce HCI. 2 4
- 30 -
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~~~~
CONSULTING DIVISION
,111.
112.
113.
110. Andrianov, A. P.
oxides of sulfur.
3666 (9) (1937").
Combined method of purification of flue gases from
Novost: Tekhniki 1936, No. 58-59 14-16; C. A. 31
~-. . ., -'
The gases contg. . SO is first treated with an aq. slurry of MnO and
F~SO 4 ~o that. 50% of the ~02 is removed. The gases are then erc:i.~ubbed
wIth mIlk of hme. The fIrst treatment yields H SO and the 2nd treat-
ment yields CaS0;i' 2H2 O. Combining the two an~ h~ating to 900 yields
a gas contg. 90-91>% S02'
Atsukawa, M., Matsumoto, K., & Murokawa, H. (to Mitsubishi Ship-
building & Engineering Co., Ltd., Tokyo). Process of treating waste
gas containing sulfur oxide. U.S. Pat 3 226 192 (Cl. 23-167). Dec. 28,
1965. (Japan;appl. Feb. 28, 1962).; Brit. Pat. 1 041 822, Sept. 7, 1966.
Waste gases containing S02 is scrubbed with a thick Mn -oxides slurry.
Thus the spent slurry contains Mn sulfate. The spent slurry is regenerated
in the liquid form with HCI so as to form MnCl2 and H2S04' The MnCl2
is crystallized and separated. It is then treatea with not combustion gas
with excess 02 to convert the MnCl2 into Cl2 gas and Mn oxides which
are re-slurried 'and reused. .
Mitsubishi Shipbuilding & Eng. Co. Ltd. Sulfur oxides removal from
stack gases and sulfuric acid manufacture. Fr. Pat. 1 348 923-4
(Cl. C lOb, 10k, F 23j) Jan. 10, 1964 (Japan. ppl. Feb. 28, 1962);
C. A. ~, 6657 e, f (1964).
S tack gas contg. O. 17~ S02 and 2. 8% 02 is scrubbed with a slurry.of
8% MnO in water at 45-50~. The gas is thus freed from S02' The
pregnant soln., aside from the suspended soli<;is, contains MnS04
24.3% MnS206 O. 9% and H2S04 O. 8%. The MnSO 4 is crystallized as
MnS04.4H2lJ. The latter IS converted to MnCI2' 4~0 with HCl or
NaCl. The MnCI2' 4H20 is oxidized at 3500 - 0000 to regenerate MnO
and H Cl.
Peisakhov, 1. L. Catalytic purification of flue gases from sulfur
c;iioxide. Novosti Tekhniki 1936, No. 58-59, 13-14; C. A. ~,
3666 (7) (1937).
S02 in gases is removed by washing the gases with a soin. contg.
dissolved or suspended Mn02 or a mixt. of MnO and FeSO 4' The
reaction between S02 and the said soln. yields I!2S0 4' The mixture
of Mn02 and FeSO 4 as catalyst for the oxidation of S02 is very stable
and gives a 14-15Ujo H2S04' .
- 31 -
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~~ ~~1f~
CONSUL TlNG DIVISION
114.
115.
116.
117.
Tarbutton, G., Jones, T. M., & Driskell, J. C., & Smith, C. M. (to TV A)
(Muscle Shoals, Ala.) Manganese oxide process for the re,covery of sulfur
dioxide from waste gases. U. S. Pat. 2 984 545 (Cl. 23-178) May 16, 1961
(Appl. Feb. 27, 1958).
Waste gases containing S02 is scrubbed with a water slurry of Mn oxides.
The SO combines with the Mn oxide to form a sulfite in the form of a
precipitate. The Mn sulfate is filtered out and dried and calcined to
drive SO out and thus regenerating the Mn oxides. The hot Mn oxide is
exposed to air to alter its state of oxidation so that the absorptive power
of the slurry made from it is improved.
Tarbutton, G., Driskell, J.C., Jones, T.M., Gray, F.J., & Smith, C.M.
(TVA, Wilson Dam, Ala.) Recovery of sulfur dioxide from flue gases.
Ind. Eng. Chem. 49, 392-5 (1957).
Four processes for recovering S02 from flue gas have been invetigated,
all using Mn oxides, suspended in an aq. soIn., as catalyst: (1) direct
absorption of S02 in the presence of 02.; (2) absorption of S02 in aq. soIn.
followed by aerafion of the soIn. with aIr contg. 03; (3) absorption of S02
from gas contg. 03 in a slurry of Mn02 contg. NH3; and (4) scrubbing the
SO -contg. gas with a 10% siurry'of Mn oxides obtained from calcining
Mn~O 4 at 10000-11000 without added ozone. The last mentioned process
appears most promising. In a pilot plant test a gas contg. S02 0.26; 02
2.4; C02 15.6; and N2 81. 7%is scrubbed with a 10% Mn oxide slurry at
600 for a contact time of 7.5 sec. ; essentially all of ,the S02 was absorbed.
At the end of 72 hours of continuous operation the slurry was filtered and
the filtrate contained an equivalent of 29% anhy. MnS04' About 10.5% of
the Mn in soIn. was in the form of dithionate only a trace of H2S04 was
present. 28 references.
Vasil'ev. S. S., Kashtanov, L. I., Kastorskaya, T. L. & Nemkova, 0. G.
Application of catalysts and ozone in the water purification of flue gases
from sulfur dioxide. Novosti Tekhniki 1936, No.58-59, p. 12-13;
C. A. 1!, 3666 (5) (1937).' ,
A soIn. of Mn salts (0.1%) used for the absorption of S?2 r.esults in a 25%
H SO soIn. The action of 03 in the process of SO oXHfahon depends on
th2e rfUb of ° concn. At equal concn. one mole orH2So4 is formed per.
mole of ° ; if there is a high excess of SO , then 15-20 moles of H2S04 1S
formed pe~ mole of 03' This is explained1;y the c~ain reaction between
03 and S03' There is probably a catalyst formed m the soIn.
Zimmerley, S. R. (to Kennecott Copper Corp.) Use of deep-sea nodules
for removing sulfur compounds from gases. U. S. Pat. 3 330 096 (Cl.
55-73) July 11, 1967 (Appl. Feb. 19, 1965).
Deep-sea Mn nodules are found to absorb S02 to the extent of 25% of
their own weight. They are specified to be used in a loose packed bed to
remove S02 from waste gases.
-------------------------------------------------------------------------------
- 32 -
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~ c;f'~ 1f~
CONSULTING DIVISION
118.
119.
Atsukawa~ M., Nishimoto, Y., ~ Matsumoto, K. (Hiroshima Tech. Inst.
Japan). Removal of S02 gas from waste gases. Mitsubishi Heavy Inds.
Ltd., Tech. Rev. ~, No.2, 51-57 (May 1965).
The processes for the removal of S02 from flue gas are reviewed. Tests
are being completed by Mitsubishi Heavy Inds. Ltd. on a new process
using a slurry of red mud from the bauxite processing, as the S02
absorbent.
Fukuma, S., Atsukawa, M., & Inoue, .Y. (To Mitsubishi Shipbuilding &
Engineering Co. Ltd., Tokyo). Production of sulfites from red mud.
U.S. Pat. 32987.81 (Cl. 23-121) Jan. 17, 1967. (Japan, appl. Feb. 9,
1962). '
S02 in waste gases is removed scrubbing with a slurry contg. up to 40%
red mud (the residue of treating bauxite with an alkaline som. in the
Bayer process). The slurry may be used at 200-70oC. until its pH value
drops to 4. 3. Upon filtration an aq. som. of Na2S03 and NaHS03 may be
recovered.
-------------------------------------------------------------------------------
120.
Hrdlicka, K. Absorbing sulfur dioxide and trioxide from industrial
fumes by the zinc method. Czech Pat. 90 701, Jline 15, 1959; cf.
Tech. Chern. (Prague) l£ (5), 236-241 (1962); C.A. 54 9230 d (1960);
g, 3608 e (1964).
The S02 contg. gas is scrubbed with a slurry of ZnO producing
ZnS03' z. 5H20 crystal. Two methods of liberation of SO and
regeneration of Zn oxide are available: one is thermal Jecomposition,
and the other is treating the ZnS03 in soln. with H2S04. However the
second method does not regenerate ZnO, but gives a byproduct of
ZnSO 4' which is not always economical unless suitable ZnO in large
supply is available. .
121.
Klimecek, R., & Jara, V. Absorbing sulfur dioxide from industrail
waste gases. Czech. Pat. 106 829, Mar. 15, 1963 (appl. Nov. 26,
1961)' C. A. 60, 3915 b (1964).
, -
The presence of O. 5-50 g. 11. of NaOH, KOH, or NH40H in the ZnO
slurry increases the efficiency of scrubbing from 70-80% to 80-90%
at the same liquid rate.
, - 33 -
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~knuad <;$'~ ~
CONSULTING DIVISION
122.
123.
124.
Metallgese Ischaft AG. (Bakay. T.. inventor). The decomposition
of ZnS0.3 obtained from the purification of fume gas which contains
sulfur dioxide. Fr.' Pat. 1 370 520 (cl. C 016) Aug 21. 1964
(Ger. appl. Dec. 12. 1962); C.A. 62. 10109 h (1965).
An aq. slurry of ZnO is used to absorb SO from a gas contg. S02'
The ZnS0.3 formed in the slurry is alloweJ to settle to the bottom.
separated~ dried at 1900. and calcined at 4000 -50Qo to liberate S02
and regenerate the ZnO.
Peisakhov. 1. L. Zinc method of concentration of sulfur dioxide.
Sbornik 1953. 20-33; C. A. 52. 1564 i (1958). .
The S02 in smelter gas is absorbed in a slurry of ZnO. forming insoluble
ZnSO~. The latter is filtered off and heated to 300-3500 to decompose
back 10 802 and ZnO. This method has the advantages of operating
without necessity of cooling the gas and without interfe!,ence by the
presence of Se. in the gas. There is some ZnS'O 4 fornled which c.an
be recovered from the ZnO before it is reused.
Srbek. J.. Klimecek. R.. & Jaeger. L. Scrubbing sulfur dioxide
from waste gases. Czech. Pat. 108 093~ Aug. 15. 1963 (appl.
Apr. 13. 1956); C. A. 60. 6524 h (1964).
The S02 -contg. gas is scrubbed with a slurry of ZnO which is
thereby converted to 2nS03' The ZnS03 is treated with H2S04 to
liberate SO. The ZnSO 4 thus formed is calcined to give ZnO and
S02' The :lno is recycled as a slurry in the absorption step.
===============================================================================
125.
126.
Anon. -1968. Developments in desu1ff.urization of waste gas. Sulphur
(London) No. 78. Sept. -Oct. 1968. p. 33-34. .
Two pilot plants are being built to test the active-carbon adsorption
proce~s and the Mn02 adsorption process. Each pilot plant has a
capacIty of 150.000 cu. m. /h. of flue gas. One at Goi. Japan. using
Hitachi Mfg. Co. 's active-carbon adsorption process; the other at
Yakkaichi. Japan. using Mitsubishi Heavy Inds. Ltd. 's dry Mn oxide
adsorption pro cess.
Anon. -1967. Coke cleans flue gas in German process. Chep..1. Eng.
24. Oct. 23. 1967. p. 94. 96. 98. (cf. ref. Frankenberg).
The Reinluft process for SO removal from waste gases is described
with a flow diagram. CapitiI costs and operating costs are estimated.
- 34 -
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~~
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~~ ~~ 1f~
CONSULTING DIVISION
127.
128.
129.
130.
131.
Anon. -1967. Japanese rushing to cut S02 pollution. Oil & Gas J. 65, .
June 26, 1967, p. 53-54.
Hitachi Mfg. Co. Ltd. is operating a 5 million SCF flue gas per day
based on adsorption of S02 on active carbon. In the regenerating step,
the pregnant carbon is washed with water recovering a H2S04 solution.
Brauer, L. W. (to Auergresellschaft Gmbh, Berlin, Germany). Sulfur
dioxide absorbent. U. S. Pat. 3 396 122 (Cl. 252-428). Aug. 6, 1968,
(appl. Nov. 17, 1964).
A S02 absorbent is specified consisting essentially of granular
activated carbon impregnated with an alkaline material and 3-.100/0
glycol or O. 5-3. 00/0 polyvinyl alcohol operated at about 280C.
Frankenberg, T. T. (Am. Elec. Power Service Corp., N. Y.) Removal
of sulfur from products of combustion. Proc. Am. Petro Inst. Vol. 45,
Sec. III p. 365-370 (1965). (Chemico reprint 2955, p. 367.)
The Reinluft process was invented in the late 1950's by Dr. F. Johswich
of West Germany. The Wolkswagen Co. and two other companies are
installing it with government subsidy. The process involves adsorption
of S02 on the char made from peat, size, 10-12 mm. The reactor has 3
zones, vertically disposed and in countercurrent relationship with the
reacting gases. In the reactor the char descends slowly at about 1-2
mm. per min. The upper zone operates at 2030-212oF., the middle
zone at 320oF., and the lower zone is the desorption zone. The 3
zones are sealed from each other automatically by the char. The waste
gases contg. S02 enter at the bottom of the midcD. e zone and go upward.
The stripping gases, N2 or C02 or a mixt. of the two, at 750oF., enter
at the bottom of the lower zone. S02 is driven out through the outlet
at top of the lower zone in a concn. approx: 50% S02. The regenerated
char is recycled to the top of the reactor.
Juntgen, H. (Berzbau-Forschung GmbH, Germany). The dry process
for separating sulfur dioxide from waste gases. Chern. -Ing. -Tech. l!!.,
734-6 (July 1966).
A simple method to remove S02 from waste gases is to use a dry
adsorption method with a carbanaceous adsorbent. The latter may be
regenerated by washing with water or by applying heat.
Kurel, M., Juentgen, H., & Dratwa, H. (to Bergwerksverband Gmbh. ,
Essen, Germany). Method of purifying gases. U. S. Pat 3 345 125
(Cl. 23-2) Oct.. 3, 1967, (Ger appl. Nov. 13, 1965).
S02 in the flue gas is removed by adsorption on active carbon impregnated
with 1-100/0 Cu, Cr, Fe, Mn, or Ce sulfate or CoNO at 100o-160oC. The
adsorbent may be regenerated by heating to 3000-50~o or higher temp. in
a current of inert gas contg. less than 1 % 02'
- 35 -
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CONSULTING DIVISION
132.
133.
Peters" W.J. and Juntgen, H. (to Firma Bergvierksverband GmbH. ,
Essen, Germany). Method and apparatus for purifying gases. U. S. Pat.
3 405 508 (Cl. 55-73) Oct. 15,. 1968 (German Appl. Oct. 8, 1965).
S02 in flue gas is adsorbed on activated carbon or char. The pregnant
carbon is next washed with aq. NH3 and the carbon reused.
Tamura" Z., and Hishinuma, Y. (to Hitachi, Ltd.,
Japan). Method of and Apparatus for Desulfurizing Industrial Waste
Gases. U. S. Pat. 3 398 509 (Cl. 55-73) Aug. 27, 1968 (Japanese appl.
Aug. 15, 1966).
Waste gases containing small amounts of S oxides are passed through a
moving bed of active carbon which adsorbs the S oxides. The pregnant
carbon granules are then washed with water to remove the S oxides.
From the wash water the S oxides are recovered as dilute H2S04'
-------------------------------------------------------------------------------
134.
Ste.Nationale des Petroles d 'Aquitaine (Mathieu" P., inventor). Catalyst
regeneration. Fr. Pat. 1 448 829 (Cl. B 01; C 01b) Aug. 12, 1966
(Appl. Apr. 27, 1965); C.A. 66, 59305 n (1967)..
An Al203 (97%) catalyst used in desulfurizing a gas contg. S02 and H2S
was regenerated by heating at 5000 for 1 hr. After 18 cycles tfie catalyst
lost only 15% of its initial activity. An identical catalyst regenerated by
passing air over the catalyst at 4500 rapidly lost activity.
-------------------------------------------------------------------------------
135.
136.
Anon. -1967. Pollution cost gap. Chern. Week 101, July 22" 1967, p. 73-6.
A process flow diagram for the Alltalized Alumina process of the U. S.
Bur. of Mines is shown.
Bienstock, D., Field" J. H., & Myers, J. G. p'rocess development in
removing sulfur dioxide from hot flue gases. (In four parts.) Parts
1 and 3 U. S. Bureau of Mines, RI-5735, 1961. 29 pp; RI-7021, July
1967, 52 pp.
Results are reported of laboratory investigations of absorption of S02 at
concentrations less than 0.5% in waste gases by metal oxides, expeclally
Mn oxides and alkalized alumina. (See also abstract under ref. 137.)
- 36 -
-------
~~ 1#'~
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~~ ~~ 9f~
CONSULTING DIVISION
140.
Pijpers, F. W. and Starmans, M. M. J. J. (to Shell Oil Co. , New York,
N. Y.) Alkali on a support promoted by iron or iron and antimony
ill sulfur dioxide removal. U.S. Pat. 3428 575 (Cl. 252-464)
Feb. 18, 1969 (Dutch appl. Oct. 3, 1965). (See abstract of ref.
139).
------------------------------------------------------------------------------
140a.
Pigache, P. Recovery of sulfur and sulfur compounds from gases.
Brit. Pat. 743 172, Jan. 11, 1956; U. S. Pat. 2 747 968, May 29,
1956; C. A. 50, 13388 a, 16082 b (1956).
S compds. are removed from gases by passing the mixt. through
a fixing agent maintained at 100-3000. The fixing agent, which
consists of finely divided Cu or oxide on a carrier of Al203 free
of Si, is regenerated by heating to 350-8500 and oxidizing with air,
followed by reduction with H2 or. CO. The S may be recovered as
elemental S, liquid S02' or H2S04'
- 37a -
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~~~~~
CONSULTING DIVISION
140b.
Shell Internationale Research Maatschappij NV. Removal of sulfur
dioxide from gaseous mixtures and acceptors for use in the process.
Fr. Pat. 1 448 396, June 27, 1966 (appl. Sept. 3, 1965).
A process for S02 removal from flue gases is specified, in vb ich the
SO , together with S03' is chemisorbed by a Cu oxide-based
"a~ceptor" supported on silica-alumina. The acceptor is prepared by
impregnating silica-alumina with an aq. Cu(N03)2 soln. which also
contains Cr as a promoter and Ba as a stabilizer. A typical acceptor
contains, by weight, Cu 18, Cr 5, Ba O. 5 and silica -alumina 100 parts.
The silica-alumina contains silica 87 and alumina 13 wt. % with a
specific area not less than 100 sq. m. / g. The gas to be treated must
contain sufficient free 02' so that the chemisorbed S02 on the acceptor
is completely oxidized to form CuS04' The absorption is carried out
at 325-4250C. in a continuous process by a known technique, such as
the fluidized bed system. The pregnant acceptor is then transferred
to a regenerator where a reducing gas containing CO and/or H2 or
CH4' passes over the acceptor at 350-4500C., when the CuS~4 is
converted back to CuO and the sulfur values emerge as S02' ff2S
and S vapor. These are recovered by known methods. After tne
regeneration, there is a supplementary step whereby a gas containing
free 02 is passed over the acceptor at about the same temperature as
in regeneration, so that any over-reduced Cu, and possibly some
Cu S are reoxidized to CuO. It is claimed that the activity of the
spJcified acceptor improves after the first several cycles of S02
absorption and regeneration, and tin t since the regeneration
temperature is only a little higher than the absorption temperature,
the stress developed in the acceptor granules is very small, therefore,
the life of the acceptor is long (e. g. several hundred cycles without
appreciable decrease in activity).
-----------------------------------------------------------------------------
- 38 -
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~~~ ~~ CC~
CONSULTING DIVISION
141.
142.
143.
144.
Anon. -1968. Waste gas desulfurization to become practical. Japan
Chern. Wk. ~, June 27, 1968, p. 3; Sulphur (London) No. 78, 33-34
(Sept. -Oct. 1968).
The S02 removal process develbped by Mitsubishi Heavy lnds. is
being tested in a pilot plant at Chubu Elec. Co's Yokkaichi power
station at a gas rate of 150,000 cu. m. /h. The process involves
absorption of S02 by solid Mn oxide. The S02 removal efficiency
was about 90%.
Anon. -1967. Manganese nodules can provide a cheap way to clean stack
gases. Chern. Eng. 24, July 31, 1967, p. 33; d. Zimmerley, S. R.
U. S. Pat 3 330 096 (1967),
After 6 years of development work at Kennecott Copper Corp. Mn
nodules gathered from ocean bottom in their natural state was found
to react rapidly with SO forming Mn sulfate. The Mn nodules are
regenerated by flushing 1hem with water which removes the Mn sulfate.
The nodules can be thus used in 10 or more cycles' of absorption and
regeneration.
Anon. -1967. Japanese rushing to cut S02 pollution. Oil Gas J. 65,
June 26, 1967, p. 53-54.
M itsubishi Heavy lnds. Ltd. has completed a pilot plant based on
absorption of S02 by active Mn oxide powder. It has a capacity of
2. 5 million SCF Ilue gas per day.
Aktiengesellschaft fur Zinkindustrie vorm. Wilhelm Grillo. Removal
of sulfur compounds from flue gases. Neth. pa( Appl. 6 601 639
(Cl. B Old) Aug. 11, 1966 (Austrian appl. Feb. 10, Nov. 25, 1965);
C. A. ~, 12305 d (1967)
(Continued next page)
- 38a -
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~~ ~~~~
CONSULTING DIVISION
Con t 'd
144.
145.
The method described uses a moist, powd., or granulated absorbent const'g
of a mixt. of an alkali metal or alk. -earth metal hydroxide and an oxide of
Mn, Fe, AI, or Zn deposited on a porous carrier. The amphoteric metal
oxides are the active components of the absorbent; the other metal is only
present to protect the active ingredients during regeneration by the forma-
tion of manganates, aluminates~ etc. Example: 124 kg. 70% Mn ore is
treated with 500 kg. 50% H2S04. S02-contg. flue gases are blown through
the mixt. To the almost crear soln. IS added 136 kg. of a burned magnesite
(90% MgO). Air is blown into the mixt. to oxidize any dissolved Fe. Acid
is added to a pH 2-3. A MgO dispersion is then added to pH 4.5-5 and the
ppt. (Si02 and Fe(OH)3) is filtered. The soln. is vacuum concd. and cooled.
The crysfals obtained by centrifugation have the compn. 3MgS04' 7H20 +
1MnS04_.7H20. Regeneration is as follows. 500 kg. of the pregnant absor-
bant ana 12:) kg. finely ground coal is fed to a rotary furnace held at 9000.
Desulfurization begins at once. Steam and just enough air are introduced to
maintain a hot reducing atm. in the furnace. All S compds. are reduced to
S, H S, or COS. These products are then burned to form S02 and the gas
(12-f5% S02) is sent to a H2S04 plant. In the oxidizing section of the furnace,
more air is introduced; Mn20 IS oxidized to Mn02' and any remaining S is
removed during this stage. 1:-6 ensure completion of the manganite formation,
the hot manganite (~7000) is quenched with water and hyeroxides of Mg and
Mn are formed.in this process. The hydroxides are filtered and used as
absorbent.
Bienstock, D., & Field, J. H. (to U. S. Dept. of Interior). Removal of
sulfur dioxide from gases. U. S. Pat. 3 150 923 (Cl. 23-2) Sept. 29,
1964 (Appl. Jan. 18, 1962; C. A. g~ 16694 d (1964).
S02 from waste gases was adsorbed on MnO and the SO then released
from the spent absorbent MnS04- to regenera1e Mn02 for2recycling in the
process. Thus to a 30% soln. 01 MnS04 a 25% soln. of NaOH was added
in an amt. equal to 20% excess of NaOK. Both solns. were heated to
700 before mixing. The ppt. obtained was washed with cold H ° dried
at 1080 for 47 hrs., heated with air for 2 hrs. at 3000 and thefi in vaccuo
at 300-400 for 20 hrs. The absorbent thus prepd. contained (wt. %);
Mn203 99, Na20 O. 4~ S03 O. 5. This was treated as a fixed bed with a
simulated flue gas of the following compn,; (wt. %) S02 0.3, C02 13.0,
02 6. O. H20 6.7, N 2 74. O. The following absorptions were obtained
(temperature, g. S02/ 100 g. absorbent, vol. 802/vcH. absorbent)
130, 33, 75; 330, 43, 100.
- 39 -
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Y/~ ~~ 1f~
CONSULTING DIVISION
150.
Ehrenberg, W.. Filter-mass for the SO removal from waste
gases. Chem. Ing. Tech. 38, (July, 1966). (6hemico transl. TR390).
S02 in waste gases contg. C02 such as the flue gas from power plants
may be removed by contacting the waste gases with porous solid
NaHC03 slightly moistened with water.
-------------------------------------------------------------------------------
151.
Martin, D. A., & Brantley, F. E. Selective adsorption and recovery of
sulfur dioxide from industrial gases by using synthetic zeolites. U. S.
Bur. Mines Report of Invest. 6321, 1963, 15 pp.
Synthetic zeolite of types 4A and AW 500 may be used to adsorb S02
from gases provided the gases have been cooled and dried before
contacting with the zeolite. The desorption may be carried out at
3750 in a current of N2.
-------------------------------------------------------------------------------
-------------------------------------------------------------------------------
152.
153.
154.
Anon. -1968. Two processes offer economic recovery of S02 from stack
gas. Chem. Eng. News 46, July 8, 1968, p. 13.
(1) Southwest Research Inst., Houston, Texas uses U. S. Bur. Mines
alkalized alumina process, but substitutes Na aluminate for alkalized
alumina. (2) North Am. Rockwell Co. uses the molten carbonate
process (d. Ibid. 45, Aug. 14, 1967, p. 11). Operating costs of the
two processes are estimated based on pilot plant data.
Anon. - 1967. Atomic International process of removing S02 from
. flue gases. J. Commerce(New York) Aug 9, 1967, p. 9; Chern.
Eng. News 45~ Aug. 14, 1967, p. 11-12.
The hot flue gas is scrubbed with a molten salt which absorbs SO .
The pregnant molten salt is regenerated when it gives off H2S. .the
H2S is subsequently converted to elemental S by known metfiods.
Heredy, L. A., McKenzie, D. E. & Yosim, S. J. (to N. A. Rockwell
Corp.) Removal of sulfur oxides from flue gas. U. S. Pat 3 438 722
(Cl. 23-2) April 15, 1969 (appl. May 15, 1967).
S02 in the flue gas is removed by passing the gas in contact with a
miXture of alkali metal carbonates at a temp. above 3500C. Metal
sulfites are formed in the molten mixture. The pregnant melt is
treated with a mixed gas containing H and C02 at 5000. The metal
sulfites are thus reacted to form metcft carbonates and H2S. The H2S
is recovered and the metal carbonates reused as S02 absorbents. An
example of the mixture of metal carbonates is given consisting of
LiCL-KCl entectic (LiCl 58 mole % KCl 42 mole % m. p. 3480C.) 40 g.
Li2C03 10 g. and KCl 5. 34 g.
===============================================================================
- 41 -
-------
~~~
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~~ ~~~~
CONSULTING DIVISION
158.
159.
Marks~ G. W., & Ambrose, P. M. Diethylenetriamine and other amines
as agents for the recovery of sulfur dioxide. U. S. Bur. Mines, Rept.
Invest. 3339, 41-46 (May 1937); C.A.~, 6422 (1) (1937).
Aq. soIns. of diethylenetriamine and triethylenetetramine are
excellent absorbers for 802 up to 950, provided that the difference in
pressure of this gas over tile amine soIn. is high enough.
Losses of amine during runs over several days were small. On boiling
a.mine soIns. that have been satd. with S02' a large par~ of .the g~s is
lIberated. Anal. procedures for detn. 01S0.1 - and amme m amme
soIns. contg. S02 are given.
Stout, J. W. III. Sulfur dioxide-ethanolamine-water equilibriums.
Dissertation, Lehigh Univ., Bethlehem, Pa., 1965, 175 pp. ;
Dissertation Abs. ~ (10) 5817 (1965); C. A. 63 3673 g (1965).
Data on vapor-liquid equilibrium of the systems S02 -ethanolamine-
water are presented.
-------------------------------------------------------------------------------
160.
Italy). Sulfur dioxide
Ind. (Milan) 44,
Giona, A. R. & Pfeifer, G. (Univ. Rome,
absorption in dimethylformamide. Chim.
1354-1361 (1962); C.A. 58 7422 a (1963).
The soly of 802 in anhy. and aq. DlVIF was ir.vE'stigated. The isotherms
show that soly. decreases with increase in I-I20 cont.ent in the solvent.
The soly. of 802 at 200 and 760 mm. partial pressure was found to be
470 ml. / g. DM!. The data on heat of solution are given.
-------------------------------------------------------------------------------
161. 8medslunc1, T. H. Dimethyl sulfoxide as solvent for sulfur dioxide.
Finska Kemistsamtundets Medd. 59, 40-43 (1950); C. A. 46, 4329 a
(1952); cf U. S. Pat. 2 539 871 (1951). -
o
At 18 a soln. of 60. 13% S02 in (CH3)2S0 was obtained at atm. pressure.
lV10derate heat is evolved during absorption of 80 in (CH ) SO and the
volume of the solvent increased from 1 to 2.03. 2At 10003a2saturated
soln. contains 17. 90/0 S02' at 1610 3.2%.
-------------------------------------------------------------------------------
162.
Badische AnHin-& Soda Fabrik AG. (Giesler, E., inventor).
Separation and recovery of sulfur dioxide from waste gases. Ger.
Pat. 1 191 793 (Cl. C 01b) Apr. 29, 1965 (appl. Dec. 17, 1963);
C.A. 63, 6712 g (1965).
The absorbent for the recovery of 802 from waste gases is specified
as an organic polyhydroxy compound, such as glycol, glycerol, or
pentaerythritol, either p1..
-------
~~ ~~CC~
CONSULTING DIVISION
1-63. Nobel-Bozel (lVIarchequet, H. G. L. & Gandon, L., inventors).
Extraction of S02 from gases. Fr. Pat 1 224 892 June 28, 1960;
C. A. 55, 20357 a (1961); d. U. S. Pat 2994 585 Aug. 1, 1961.
A 0 0
glyoxal soln. at 15 -30 was used for the solvent. Desorption was
carried out by raising the temp. of the solution to 650_750.
----------------------------------------------------------------------------
1:64.' Nobel-Bozel. (Marcheguet, H. G. L., & Gandon, L., inventors). Sulfur
dioxide separation. Fr. Pat. 1 353 646 (Cl. C 01b) Feb. 28, 1964 (appl,.
Jan. 18, 1963); C. A. g, 336 e (1964).
802 in the stack gas is absorbed in aq. glyoxylic acid, OEC COOH, to
form HOOCCH(OH)S03H. The latter gives up 802 when heated. No
H2804 is formed.
-----------------------------------------------------------------------------
165.
Kohl, A. L. & Riesenfeld, F. C. Gas purification:' S02 removal by
liquid absorption. Chern. Eng. ~, June 15, 1959, p. ~47-151.
The following processes are briefly described with flow diagrams.
(1) Sulfuridiene process (using aq. 500/0 xylidine). (2) Asarco
process (using dimethylaniline). (3) Coromco process (using
(NH4)2S03' (4) Battersea process (using CaC03 and MnS04)'
, (5) Zinc oxide process (using Na,2 CO , ZnO and Ca(OH)2)' In the
last process the pregnant soln. 1S a ~aHS03 soln. because S03 is
capable of displace CO in aq. soln. ZnO is added to convert
NaHS03 into ZnS03 anJby calcining ZnS03 in closed system, a gas
contg. 30% S 02 and 70% H20 is obtained.
16,£).
Lurgi Gesellschaft fur Chemie und Huttenwesen m. b. II. The
8ulphidine process. Brochure issued by Lurgi, no date, Chemico
reprint No. 732.
An 1:1 aq. soln. of xylidine, (CH3)2C6H31\TH2' is used as the absgrbent
for low-concn. 80 in gases. WorRing with a 0.5% S02 gas at 20 -250 C.
and atmospheric Jressure, the S02 capacity of the absorbent is shown in
a graph to be about .90 g. 11. as vs. about 55 g. 11. for basic _A12(S04)3
soln. contg. com. bined A 1,2 03 53.2 cP' 11. and free Al203 .45. ;) g. ~l.
80 desorption 1S conducted at 100 -1020 C. Photos of 1l1stallahons
ar~ shown. (Xylidines as 4 isomers boil in the range 2160_2260 C.
Mixed xylidine is currently quoted at 44c; lIb., in tanks delivered.)
- 44 -
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~km«d ~~ ~~
CONSU L TI NG DIVISION
167~
168.
Roberson, A. H., & Marks, G. W. Partial pressures of sulfur
dioxide over solutions of sulfur dioxide in mixtures of water and
various aliphatic amines. U. S. Bur. Mines Rept. Invest. 3415,
45 pp. (Oct. 1938); C. A. ~, 949 (9) (1939). -
A comprehensive study of the solvents for SO recovery by absorp-
tion and desorption is reported. These solve~1ts include: (1)
xyl~dine, (2) ?asic aluminum. sulfate, (3) (NH4) S03' (4) diethylenetri-
amme, (5) tnethylenetetramme, and (6) monoe1hano1amine. The
data on monoethanalamine include the compositions (wt. % of MEA,
S02 and H20) of the solns. before and after absorbing SO at various
temps. ana degree of saturation. 2
Weidmann, H., (Metallgesellschaft A. -G. Germany). The "Sulphidine"
process for recovering sulfur dioxide. Ind. Eng. Chern. News Ed. li,
105 (1936); d. Dean, R. S., et al., U. S. Bur. Mines, Rept. Invest.
3339, 1937, 51 pp.
SO and S03 in a gaseous mixt. is absorbed in a 1:1 mixt. of xylidine
ana water, adding Na2C03 or Na2S03 to convert any xvlidine sulfate
into Na2S0 - The pregnant liquor is then heated to 80° -1000 to drive
off S02 m tte pure form. To remove Na2S03 whenever an accumulation
occurs in the aq. phase, it is a simple matter of replacing a part or all
of the aq. phase with fresh water. The xylidine is only s 1i'ghtly soluble
in the aq. phase. The initial mixt. of xylidine (a reduction product of
nitroxy1ene) and water is a two-phase liquid mixt. When xylidine
absorbs enough S02' it becomes xylidine sulfite which is soluble in
water. After desorption of S02 the mixt. again separates into two
liquid phases which settle into~iquid layers. Toluidine may be si-
milarly used. When this process was cp erated at 15-300 on a gas
contg. about 7% 802' the residual S02 in the effluent gas was as 10\'.'
as 0.10/0. The efficiency of desorption is better than 99%. Xylidine
vapors in the efi1uent gas amount s to 2. 5g per cu. m. at 20-250, and is
recovered by an alkaline bisulfite wash. The desorbed S02 gas also
contains a small amount of xylidine which is r'emoved by an aq.
H2S04 wash.
-------------------------------------------------------------------------------
169.
Robinson Bros. Ltd., F arkes, D. W., & Evans, R. B. RecoverillO'
acidic gases from gas mixtures. Brit. Pat. 468 972, July 15, 1937;
C. A. ~, 755 (2) (1938).
C02' S0?t;. and ~T2S, etc. are removed and recovered from gas mixtures
by scru6 ~ng wltfi an aq.. soln. of 1 or more dipiperidyls and subsequently
regenerat~ng the s~rubbmg soln. The dipiperidyls may be made by
electrolytic reductlOn of the corresponding pyridine bases or by reduction
of corresponding dipyridy1s.
- 45 -
-------
YI.km«d
-------
~A~ 600 which is also in excess of the dew point of the gas being
cleaned. The H2S0:4 formed is continuously removed and the used I is
regenerated by anodIc oxidn. The gas may be subjected to previous
mech. cleaning and/or be cooled to room temp. and reheated for clean-
ing. Thus, to clean at 800 a gas having a dew point of 700, a 5-15 sec.
contact with 37% aq. H2S04 contg. the equiv. free 02 of 20 g. H20 /1.
is satisfactory. . 2
Simon-Carves Ltd., Parker W. C., & Gillham, E. W. F. Improvements
relating to the removal of sulfur dioxide from gases. Brit. Pat.
633 627, Mar. 18, 1950; C. A. 44, 4656 g (1950).
A process is described for the removal of S02 from gases in which it
occurs in low conens. NHi neutralizes the aDsorbed S02' the absorbent
used being an acid H202 soIn. and NH3 causes a reduction and S02 an
increase in the condo of the absorbent, so that the result of the condo
measurement indicates whether NH 3 or S02 is present in excess in the
effluent gases from the washer, or whether the wash liquor is liberating
NH3 or S02.
------------------------------------------------------------------------------
------------------------------------------------------------------------------L
175.
Acs, M., Takacs, P., & Szucs, Z. Utilization of high-voltage electric
fields for the desulfurization of fumes. I-II Magy. Kern. Lapja
(Budapest)~, 28-31, 96-100 (1966) (in Hungarian); C. A. 64, 10787 a,
17305 h (1966).
Air contg. 0.3% S02 is mixed with NH3 gas in the molar ratio of NH03/S02
of 2: 1, and the mixt. is passed througli a dielec. -heated tube at 130 and
5-10,000 volts, The S02 combines with NH3 forming (NH4)2S03 which is
oxidized by 03 which is generated in situ by the high voltage. The
resulting (NH4)2S04 drops out of the gas stream.
- 47 -
-------
~~mn«:d ns. J. Chern. Inc. (USSR).!i, 365-9 (1937); C. A. I!., 6114 (b)
(1937).
The oxidiation of SO by ° in the presence of MnSO , studied by K. and
Ruizhov (C. A. 12., 71>19 (sr (1936)) can be applied to 1he removal of S02
from industrial gases. The apparatus is described.
Kuesters, W. Treatment of flue gas. Neth. Pat. Appl. 6 607. 238
(Cl. B old) Jan. 101 1967 (German Appl. July 9, 1965); C. A. 66,
118592 k (1967).
The flue gas rotates in a purification chamber contg. 2 concentric
electrods. The external electrode can be a grid., on which the charged
particles lose their elec. charge. The elec. field between external and
central electrode is chosen so high that corona discharge is obtained.
The corona discharge leads to the following chern. reactions. ° is
converted into 03; this 03 converts S02 to S03. The complete installa-
tion is built in corrosion-free material.
Nechaeva, N. Removing S02 from fuel gas. Novosti Tekhniki,
Sere Gorno-Rudnaya Prom. 1935, No. 41-42, 13; C.A. I!., 2783 (8) (1937).
Fuel gas was completely freed from S02 by oxidation in high frequency
elec. discharges.
Tarbutton, G., Driskell, J. C., Jones, T. M., & Smith, C. M. (to TV A).
Recovery of sulfur dioxide from waste gases. U. S. Pat. 2 926 999,
Mar. 1, 1960; Ind. Eng. Chern. 49, 392-5 (1957).
The gaseous mixture containing S02 is treated with 03 to the extent of
20-80 ppm. based on gas mixture. Enough 02 is present in the mixture
to satisfy the formation of S03 from S02. The resulting gas is scrubbed
with an aq. solution of H2S04 or (NH4)2S04 containing Mn ion at a temp.
below the b. p. of the solution but above the dew point of the gas mixture.
The S02 in the gas mixture appears in the scrubbing effluent as sulfate ion.
Vasilev, S. S., et al. Application of catalysts and ozone in water
purification of flue gases from sulfur dioxide. Novosti Tekhnici 1936,
No. 58-59, 12-13; C. A. I!., 3666 (s) (1937).
A soln. of Mn salts (0. 1 %) used for the absorption of S02 results in a
2 5% H2S04 soIn. The action of 03 in the process of S02 oxidation
depends on the ratio of 03 concn. to S02 concn. At equal concn. one
mole of H2S04 is formed per mole of 03; if there is a high excess of
S02' then 15-20 moles of H2S04 is formed per mole of 03. This is
explained by the chain reactIOn between 03 and S03. MIll LS probably
a catalyst in this case.
=========================================================================:===~
- 48 -
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~~~ ~~ <6'~
181.
181a.
CONSULTING DIVISION
Empresa Auxiliar de la lt1dustria S. A. Removal of sulfur oxides.
Brit. Pat. 1 037 554. July 27. 1966.
S02 in the flue gas is absorbed in a bed of a pyridine polymer resin. which
is formed by copolymerizing 2-methyl-5-vinyl pyridine and p-divinyl
benzene. During adsorption of S02' the resin is in contact with water at
250-600. After adsorption. air isolown through the resin bed to oxidize
S02 to SO:!, Then aq. NH3 is passed through the resin to produce (NH4)2-
SO 4' FinaIly, the resin bed is eluted with water to recover (NH 4) 2S0 4'
Layton. L. & Youngquist, G. R. (Clarkson College of Technol.. Potsdam.
N. Y.) Sorption of sulfur dioxide by ion -exchange resins. I&EC Process
Design & Dev. .!!' 317-324 (July 1969).
The ion -exchanger resin used was a polymer derived from the reaction of
a secondary amine with a chloromethylated styrene-divinylbenzene
copolymer. It is used in the dry state. Some permanent absorption of
S02 occurred, but that did not interfere with the adsorption capacity of
the resin for S02 at 250C. Desorption was carried out at 900C. At a
S02 partial pressure of 50 mm Hg, the adsorptive capacity of the resin
is comparable to those of active charcoal and zeolite.
-------------------------------------------------------------------------------.
-------------------------------------------------------------------------------.
182.
183.
Anon. -1968. Monsanto's process to recover sulfur dioxide from power
plant stack gases went commercial. Chern. Eng. News 46, Oct. 7, 1968,
p. 27; Oct. 14, 1968. p. 53. Chern. Eng. ~, Oct. 21, 1968, p. 47-48.
Chern. Week 103, Oct. 5. 1968. p. 120; Oct. 21, 1968, p. 47-48; Europ.
Chern. News.!i. Oct. 18, 1968. p. 46; Sulfur (London) No. ~, Nov.-
Dec., 1968. p. 46; cf. Chern. Eng. News 45, July 10. 1967, p. 28-29.
After operating the S02 recovery unit for more than a year at the
Metropolitan Edison Co's 800 Mw coal burning power plant. Portland,
Pa.. Monsanto Co. decided to offer the catalytic oxidiation process
(see ref. 198) for licensing. The capital cost for the S02 recovery unit
is estimated at $20-$30 per Kw power-plant capacity.
Anon. -1967. Sulfur limits throw utilities in turmoil.
News 45. July 10, 1967. p. 28-29.
The new power station of Metropolitan Edi son Co. has been completed
at Portland. Pa.. incorporating the Monsanto unit of S02 recovery
system. The Monsanto process oxidzes S02 in the flue gas to S03 in
the presence of a V catalyst. The S03 is then scrubbed with water to
give a 70% H2S04'
Chern. Eng.
- 49 -
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CONSULTING DIVISION
184.
185.
186.
187.
188.
Anon. -1966. Sulfur that gets away. Chem. Week 98, May 21, 1966,
p. 26-28; Chem. Marketing (N. Y.) 189, Apr. 25, 1966, p. 5, 34.
S02 escaped from stacks in the U. S. is estimated at 21,000,000 tons/yr.
If this amount is recovered and made into H2S04' it would be 32,000,000
tons of H SO , 100% basis. The total consumptiOn of H2S04 in the U.S.
is about :t4, o'bo, 000 tons/yr. Monsanto Co. has developed a process of
recovering S02 from stack gas. A prototype unit will be installed soon
at Metropolitan Edison CO IS power station at Portland, Pa. The process
uses V 205 catalyst to oxidized S02 in the stack gas to S03 and the latter
is converted to 70% H2S04. .
Anon. -1966. Saleable ammonium sulfate from SO -containing stack
gases. Sulphur (London) No. 65, p. 32 (Aug. -Sepr. 1966). (cf. ref. 196).
The process developed by Dr. R. Kiyoura of Tokyo Inst. of Techno!.
comprises catalytic oxidation of SO~ after which NH3 is injected into
the gas stream to form solid (NH,J2-S04 which is recovered by dust
collector. Costs of equipment ana. operating costs are estimated for
a 600 Mw. power plant burning fuel oil. At 90% load capital cost is
$ 6,670, 000 and operating cost 0.009<; per Kwh with credit to the by-
product (NH4)2S04. S02 in flue gas is reduced from 0.2% to 0.020/0.
Anon. -1966. New pilot plants tackle S02 pollution. Chem. Eng. News
44, July 4, 1966, p. 36-38; Sulphur (London) No. 64, 32 (June-July
1966); d. Brit. Chem. Eng. Q, 641-2 (July 1966).
Six pilot plants are planned or under construction in the U. S. to test
different processes of S02 removal and recovery from flue gases. A
flow diagram is shown, which is similar to the Mons an to process and
the Kiyoura-T. I. T. process. The end product of this process is
(NH4)2S04 and the residual S02 in tail gas is 0.02%.
Anon. -1967. Japanese rushing to cut S02 pollution. Oil & Gas J. ~,
June 26, 1967, p. 53-54.
A pilot plant based on the Kiyoura-TIT process of SO removal is
described. It treats power-plant flue gas at a rate 01'424 million
SCF flue gas per day. It is expected that the data obtained from this
pilot plant will enable Dr. R. Kiyoura to design a full-scale unit for
standard-size thermal electric power plants. (cf. ref. 196).
Anon. -1966. SNPA H2S04 process utilizes sour gas. Europ. Chem.
News .!.Q, Aug. 19, 1966, p. 38; Sulphur (London) No. 66, Oct-Nov.
1966, p. 39.
A joint development of Ste. Nat. de Petroles d IAquitaine (SNP A) and
Haldor Topsoe. Feed gas has less than 1% S02' product 93% H2S04'
recovery 95%, and tail gas contg. O. 0025% (25 ppm) S03. A plant
with a c~pacity of 140,000 tons H2S04/yr. is now in operation at ANPA's
plant ~n Lacq.
- 50 -
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CONSULTING DIVISION
189.
190.
191.
192.
193.
Anon. -1966. New pilot plants tackle S02 pollution. Chem. Eng. News
44, July 4, 1966, pp. 36-38.
The Monsanto and Kiyoura -T. 1. T. (Tokyo Inst. of Technol. ) processes
are described with flow diagrams.
Anon. -1966. S02 removal from flue gases. Brit. Chem. Eng. Q.
641-2 (July 1966). .
A flow diagram is shown representing the process developed at Pa.
Electric Co. at Seward, Pa.. since 1961. This process is similar to
the Monsanto process. and the end product is H2S04. The residual
S02 in the end gas is 0.02% along with 0.002% S03' which are
acceptable under air-pollution control. The flue gas from the boiler
contains 0.20% S02 and 0.002% S03. The full-scale plant based on
this process will1:5e built at Portland. Ore.. by Metropolitan Edison
Co. (cf. ref. 193.)
Anon. -1966. Promise seen in stack-gas S02 removal. Oil Gas J.
64. May 2. 1966, p. 53.
Babcock & Wilcox, Inc.. and Monsanto Co's processes of S02
removal systems are briefly described. Other schemes are'
mentioned.
Chem.
Anon. -1964. Flue-gas purification unit makes byproduct acid.
Eng. 1!.. June 8. 1964. p. 92, 94.
The process developed by Tigges of Jackson & Moreland Inc. is
described. The process is based on the following steps: (1) removal
of dust from hot flue gas by electrostatic pptn. ; (2) oxidizing the S02
to S03 using V catalyst; (3) condensing the H2S04 to form a 70%
H2S04' and collecting the H2S04 mist by a second electrostatic
pptor. The cost of plant attached to a 1,000.000 Kw power plant
burning coal contg. 3% S is estimated at $14.500,000.
Bovier. R. F. (Pa. Elec. Co., Johnstown. Pa.) Sulfur-smoke removal
system. Paper read at 26th Annual Am. Power Con£., Apr. 16. 1964.
Chicago, Ill.
The gas from burning coal contg. 3% S is first treated to remove fly
ash. It passes through a V ~()5 catalyst bed where S02 is oxidized to
SO by preheated air. The H SO 4 mixt. is collected oy an electro-
sta~ic precipitator. The gas feavmg the precipitator contains S02
200 ppm and S03 20 ppm. 90% of the S in the coal is recovered as
70% H2S04 at a cost of $7. OO/ton.
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CONSULTING DIVISION
194.
195.
196.
197.
198.
Furkert~ H. (to Chemiebau Dr. A. Zieren GmbH.) Recovery of products
from waste gas. U. S. Pat. 3 129 663, (Cl. 23-175) Jan. 28, 1964 (appl.
Jan. 2 1 ~ 1958); C. A. g, 333 f (1964).
S02- in wastes gas is catalytically oxidized to SO~. The gas is then
cocHed to a temp. above its dew point~ and the S03 is absorbed in
98% H2S04.
Guyot~ G. (SNPA, France) SNPA process for the treatment of residual
gases with low concentration in S02. Chim et Ind. Genie Chim. 101,
31-34, 813-6 (Jan., Mar. 1969).
The process is designed to treat the tail gas of the Claus process
containing S02' H2S and S valD r, a total of 1. 5 vol. %. This gas has
also a moisture content up to 30%. The gas is passed over a V 205
catalyst at 5400C to convert the S values into H2S04 without formation
of acid mist. The reaction products are scruboed with 80-85% HaS04.
The concn. of the scrubbing acid rises in the process to about 9411/0.
The scrubbing is carried out at 2500-2750C. A process flow diagram
is shown. Data from pilot plant tests show: the feed gas contained
S02 1 %, H S 1%, moisture 11%; conversion of S compounds to S03
was 90-95%; product acid was 94% H2S04; emission of S03in the tail gas
was 75 mg/cu. m. .
Kiyoura, R. (Inst. Technol., Tokyo, Japan). Removal of SO from hot
flue gases to prevent air pollution. J. Air Pollution Control Assoc. ~
(9), 4688-9 (1966); C. A. 65, 20739 c (1966).
S02 in flue gas is catalytically (V 205) oxidized to S03.. The small
amount of moisture in the gas converts the S03 to H2S0. Then NH3
gas is injected into the hot gas stream to form solid (NIi4)2S04 which
is collected with the fly ash in a cyclone.
Pauling~ E. (to Metallgesellschaft AG., Frankfurt am Main, Germany).
Sulfur dioxide separation. U.S. Pat. 3 318 662 (Cl. 23-168) May 9,
1967 (Germ. appl. Oct. 17, 1960).
Small amounts of SO in gases are removed from gases containing it by
a catalytic process a1 a temp. between 200 and 1000C. The catalyst is
either V 205 or similar material supported on active carbon~ or an
active carbon containing O. 1 to 5% I2. The gases to be treated would
contain water vapor and excess 02' so that H2S04 is formed and
subsequently removed from the catalyst.
Remirez, R. (ed) Catalytic route is ready for flue-gas cleanup jobs.
Chern. Eng. lE., Apr. 21, 1969, p. 86-88.
(Continued next page)
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CONSULTING DIVISION
Con t 'd
198.
199.
The Monsanto process of S02- removal by catalytic oxidation as installed
at Metropolitan Edison Co's Portland, Pa., 250 Mw power plant is
described with a flow diagram. The catalyst works with hot flue gas and
removes about 90% of the S02 in the gas. Even if temp. of the gas should
drop to 1750F., as when the power plant is operating at 50% boiler load,
the S02 removal is still as much as 80%. A byproduct of H2S04 with a
strengtn of about 80% is obtained.
Terminet, R. (to Societe Nationale des Petroles d'Aquitaine, France).
Catalyst composition and process for the
recovery of sulfur compounds from gas mixtures. U. S. Pat. 3 300 280
(Cl. 23-175) Jan. 24, 1967 (France appl. Feb. 11, 1963).
The catalyst is alumina-based containing about 6% V 205 and 7 -8% K20.
Operating temp. is 4300 and contact time 0.25-0.35 sec. In the
presence of 02S02 at low concn. is oxidized to S03 which is
subsequently removed by absorption in water or ronc. H2S04'
-------------------------------------------------------------------------------
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200.
201.
202.
Anon. -1968. S02 removal: Cheaper process piloted. Chern. Eng. News
46, Sept. 9, 1968, p. 22. .
The Princeton Chemical Research, Inc. has developed a process, called
PCR process, to remove S02 from waste gases by a series of catalytic
reactions: (1) Elemental S is reacted with natural gas and steam to
produce H S and C02' (2) the H S is reacted with S02 to produce
elemental%, and a part of this Efis reacted with natural gas and steam
to produce H2S (as in step (1). The main part of elemental S is a
saleable byproduct.
Spence, P. & Sons Ltd. Sulfur dioxide removal. Belg. Pat. 661 381
July 16, 1965 (Brit. appl. Feb. 5, 1964); C. A. 65, 6792 a (1966).
With ahout 90% of the stoichemetric amount of H2S supplied, the
Claus process: S02 + 2H2S --... 3S + 2H20 may be used to eliminate
S02 from flue gases. Example: In the presence of activated Al203
as catalyst, operating at 500-3000, elemental S deposits on the
catalyst, and the gas coming out of the reactor contained no S02"
Starting from a gas contg. 0.24% S02' all of the S02 was eliminated
in about 1. 65 sec. Presence of C02 (1%), 02 (20%), and H20 vapor
(6%) did not interfere with the process. .
Sulfur-Chemie A. -G. Purifying gases.
1936; C. A. ~, 3671 (7) (1937).
Gases contg. S02 is passed together with an equivalent amount of H S
into an aq. soln. contg. oxygenated compounds of thiosulfate. This2
promotes the reaction between S02 and H2S with pptn. of elemental S.
French Pat. 804 487, Oct. 24,
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214.
215.
216.
Frankenberg, T. T. (Am. Elec. Power Service Corp., N. Y., N. Y.).'
Removal of sulfur from products of combustion. Proc. Am. Petro.
Inst. Sect. III. 45 (3), 365-370 (1965); C.A. 65, 15972 d (1966).
- -
A va'ilable processes for ~emoval of 802 from stack gases are reviewed.
In none of the processes IS the recovery of byproduct S compounds
ec onorni cal.
Johswich, F. The present position of flue-gas dcsulfurization.
BreuD.stott-Waerme-Kraft.!1 (5), 238-245 (1965) (in German); C. A.
El, 8071 c (1965).
The following processes are reviewed and the costs of 8 recovery
compared: Reinluft process (adsorption on C), Penelec process
(catalytlc oxidation), Wickert process (injection of powdered
dolomite), Bayer-Lcverkusen process (a 2 -step process involving
catalytic oxidation), the alkalized Al2 03 pro~ess. Processes.
involving scrubbing with aq. soln. and slurnes such as ZnO slurry
are considered "impractical on a large scale. "
Katell, 8. (U. S. Bur. Mines) Removing sulfur dioxide from flue gas.
Chern. Eng. Prog. 62, Oct. 1966, pp. 67-73
Three dry processes for 80...2.. removal from flue gases are compared
based on a power plant of 8UD Mw capacity burning coal contai"fling 3% S.
These processes are (1) Alkalized alumina (U. S. Bur. Mines); (2)
Reinluft (German), and (3) Catalytic oxidation (Monsanto Co.) The
capital cost is lowest for (1) and highest for (3). The 0IE rating cost
at 90% load is lowest for (3) provided the byproduct of 70% H2S04 ~can
be utilized locally. A summary of cost estimates is shown in Ta1:E 4.
T;lb:c 4. CJpit.1/ requIrements end opcratm[: co:;ts.
QpEH.\ TIXG COS,'"
(90% or'Elt.\TING LOAD)
C.\i'ITAL HEQUJIn::,lS~T.
MILLS/
KW.-liIl.
S/TO;';
OF ~In.J.s/
COAL 10' BTU
PRO,ESS DOLL\[':~ $/KW.
--
Rcb!uft 14,~17.000 17.77
Alk~Ez(.j
ah.l~1:~:: 5,510,000 10.6,1
$/YR.
5,431,000
0.557
~.45
95.8
3,402,000
0.537
1.54
60.0
C:l:::~~'\ :~
oxici:nivn . .16,999,000 21.25 3,881,000 0.613 1.75 68.4
.I:1C!II(h's pIant cost, -inlcr~st during construction, end U'orl;ing eanita!.
"Ill<,;ud~s ~e:l' 7Il~/crials, utilities, labor, maintenance, ot'crhead, ~lId capital charges
oj 14 'I~ (J lotcl11ll'cs/mcnt /;ut excludes /;?J-pfoduet credit.
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CONSULTING DIVISION
221.
222.
223.
Bienstock, D., & Murphy, E. M. The Chemistry of sulfur dioxide.
U. S. Bur. Mines, Div. of Solid Fuel Techno!., Interim Report 1956, 58 pp.
The problem of air pollution by S02 emissions from burning coal contain-
ing S, from smelters and from H2S'04 plants is discussed. Plans for
finding a solution to this problem are under way at U. S. Bur. of Mines
in cooperation with U. S. Public Health Service. A survey of literature
has been made for information useful in this project. An annotated
bibliography of 84 references is presented.
Bienstock, D., Brunn, L. W., Murphy, E.M., & Benson, H. E.
Sulfur dioxide, its chemistry and removal from industrial waste gases.
U. S. Bur. Mines, Inf. Circ. 7836, 1958, 96 pp.
Phys. and chern. properties of S02 are reviewed. Methods of removal
of S02 from waste gases have been investigated. Their advantages
and dIsadvantages are discussed. 253 references.
Cooper, A. G. (U. S. Public Health Service Div. of Air Pollution,
Washington, D. C.) Sulfur oxides and other sulfur compounds.
U. S. Publication No. 1093, Bibliography Ser. No. 56, 1965, 383 pp.
A bibliography with abstracts of 994 references, 1893-1964 with
subject headings and author index.
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CONSULTING DIVISION
I.
II.
III.
IV.
V.
a)
b)
e)
f)
g)
h)
i)
j)
A BIBLIOGRAPHY OF SULFUR
TRIOXIDE AND SULFU RIC ACID
MIST EMISSIONS AND THEIR
CONTROL, 1907 -1968,
WITH ABSTRACTS
TABLE OF CONTENTS
(Subject Index)
Sulfuric acid mist formation (1 to 5)
Physical behavior of H2S04 mists (1, 6 to 16)
Sulfuric acid mist emissions and their control (17 to 20, 61)
Mist removal in general:
a)
b)
Filter mats (21, 22)
Filter cartridges (23)
c)
d)
Glass fiber mats (24, 25, 26)
Sieve tray columns (27)
Venturi scrubbers (28)
e)
f)
Wire me sh filters (29 to 33)
Sulfuric acid mist removal:
Review of processes (34, 35, 36)
Scrubbing with alkaline solutions (37)
c)
d)
Scrubbing with water foam (38)
Ceramic filters (36, 39 to 44)
Coke-bed filters (45, 46)
Electrostatic precipitators (45, 47 to 50)
Glass fiber mats (36, 51 to 57)
Metal granules (58)
Packed columns (36, 59, 60)
Sonic vibrations (61, 62, 63)
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CONSULTING DIVISION
Table of Contents - Page 2.
k)
1)
m)
n)
0)
p)
q)
VI.
Steam injection and condensation (64, 65, 66)
Sulfuric acid solutions (67)
Synthetic fiber mats (68 to 75, 83)
Vane-type baffles (36)
Venturi scrubbers (76 to 79)
Water spray (80, 81)
Wire mesh filters (36, 82, 83)
Sulfur trioxide removal:
a)
b)
c)
d)
e)
f)
g)
h)
i)
j)
VII.
Absorption in concentrated sulfuric acid (84, 85, 86)
Ammonia injection (87, 88)
Limestone injection (89)
Magnesia slurry (90)
Peroxysulfuric acid (91, 92)
Reaction with iron oxides (93, 94, 95)
Reduction with carbon (93, 94, 96 to 99)
Reduction with H2S and CH4 (100)
Steam injection and condensation (101)
Zinc oxide slurry (102)
Analytical methods (103, 104, 105)
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CONSULTING DIVISION
A BIBLIOGRAPHY OF SULFUR
TRIOXIDE AND SULFURIC ACID
MIST EMISSIONS AND THEIR
CONTROL, 1907-1968,
WITH ABSTRACTS
1.
Dooley, A., & Goodeve~ C. F. (Univ. College, London~ England), on sulfuric
acid mist. Trans. Faraday Soc. E, 1209-1218 (1936); C. A. 30, 7244 (3)
(1936).
When S03 in a dry air stream is passed through water, it is not appreciably
absorbed, but is converted into a H2S04 mist which is stable to acids and
alkalis. On the other hand when dry S03 vapor is passed thro ugh a 98%
H2S04' it is practically completely absorbed. Exptl. results indicated that
good absorption of S03 vapor in an aq. H SO 4 requires an extremely low
water vapor pressure. But removal of ;SSO 4 mist by absorption requires
a saturated or supersaturated water pressure. Therefore, if the scrubbing
liq uid in a column changes continuously from 98% H2S04 to pure water, the
H2S04 mist will pass through a maximum.
2.
Gillespie. G. R.. & Johnstone. H. F. (Univ. of Ill.) Particle-size
distribution in some hygroscopic aerosols. Chem. Eng. Prog. ~. No.2.
74F-80F (1955).
The formation of mist and the particle size distribution in the mist have
been studied in the case of H2S04' H3PO 4' HCl, HBr and ClS03H. It was
demonstrated that for a given concn. of Hie vapor, the substance with lowest
equilibrium pressure has its critical supersaturation exceeded most. and
therefore a greater number of smaller particles in the mist. It is also
shown that particle size of the hygroscopic aerosols depends primarily on
the manner of formation. If the hygroscopic vapor reacts with water vapor
with release of considerable energy. the particle size of the aerosol is
small. i. e.. less than 2 microns. Examples are S03 in humid air forming
H2S04 aerosols and P 205 vapor in humid air forming H3PO 4' On the other
hand. if the vapor simply condenses and then absorbs moisture without
releasing a large amount of energy. the particle size will be large~ i. e. ,
2-6 microns. Examples of the latter case are the condensation of H2S04
vapor, HCl, and HBr. The problem of nucleation in the formation of
aerosol has been studied. Exptl. results indicated that the addition of
foreign nuclei to the air stream generally decreases particle size and
increases particle number with two exceptions: (1) In the case of H2804
mist formed from 803 and water vapor. the introduction of additional nuclei
did not affect the particle size. (2) In the case of HCl mists selfnucleation
did not take place nor did the introduction of foreign nuclei have any effect
until sufficient water vapor was present to dissolve the salt used as a source
of nuclei. This indicates that. in this case. solid foreign particles do not
act as nuclei, but when dissolved in water, the droplets absorb HCl to form
an aerosol.
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CONSULTING DIVISION
3.
Goodeve, C. F., Eastman, A. S., & Dooley, A. The reaction between sulfur
trioxide and water vapors and a new periodic phenomenon. Trans. Faraday
Soc. 30, 1127-1133 (1934); C. A. ~, 2428 (6) (1935)
The reaction between SO and H ° is very fast. Under certain conditions
the H SO mist forms pe~iodicany. Trimolecular collisions are apparently
2 4 ' t' th' d b d'
necessary. The molecules of the inert carrymg gas ac mg as lr 0 les.
4.
Petryanov, 1. V., & Tunitskii, N. N. Formation of aerosols during the
condensations of supersaturated vapors. Zh. Fiz. Khim. g, 1131-1140
(1939); C.A. 34, 4636 (1) (1940).
Sulfuric acid fogs were produced by mixing streams of S03 and H20 vapors
in capillary tubes, and their properties were detd. by means of an electro-
metric method. Data are given on the size and concn. of the fog droplets
obtained as a function of the concn. and rate of flow of the S02 and H20
streams, the temp., and the size and length of the capillary tubes. For
stearic acid fogs produced by diln. with a cold gas, a diam. of about
7 x 10-6 em. is obtained at temps. up to 1870, above 2000 the diam. in-
creases.
5.
Walker, W.H., Lewis, W.K., & McAdams, W.H. Principles of chemical
engineering, 3rd ed., McGraw-Hill Book Co., New York, 1937, p. 39.
The explanation of the difficulty of absorbing sulphur trioxide made in the
contact process: "If one attempts to dissolve the trioxide in water or dilute
sulphuric acid, the trioxide vapor first comes in contact not with the liquid
but with the water vapor which has evaporated from the liquid into the gas.
It reacts with this vapor, producing minute droplets of sulphuric acid in the
form of a fog, and these droplets are effectively insulated from the absorbing
liquid by the gas film. One must therefore use as an absorbent a liquid, the
water-vapor pressure of which is negligible, i. e., strong sulphuric acid.
This is the reason why for absorption one must use acid between 97 and 98
per cent. If more dilute, the pressure of water vapor is sufficient to
produce a fog, if more concentrated the partial pressure of S03 over it is
great enough to prevent complete absorption. "
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6.
Amerlin, A. G., & Yashke, E. V. Dispersity of mist formed during vapor
condensation on a surface. Kolloidn. Zh. 25, 3-8 (1963); C. A. 59, 51 e
(1963).
Wt.~oncn. and dispersity of H SO 4 mist droplets condensed at the inner
surface of an outside-cooled tute carrying H2S04 vapor-air mixt. was detd.
as function of condensation temp. and flow rate, oy the ultramicroscopic
method. On increase in temp. and decrease in flow rate, the size of droplets
increases. Exptl. results agree quant. with previously (ibid. 24, 374(1962»
given calcns.
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9.
10.
~~ «;t'~ CC~
CONSULTING DIVISION
7.
Gillespie~ G. R. Particle-size distribution in hygroscopic aerosols. VI. Test
on industrial sulfuric acid mist. Northwestern Univ. ~ Doctor's dissertation,
1953~ 103 pp; Diss. Abst. 11, 1125-6 (1953).
p. 39. The particle size of the H SO mist from the tail gas of a contact plant
of Am. Cyanamid Co. in HamiltoJ~ O~ was measured. Tnp. mist particles
ranged from 0.6 to 3.3 microns with a mean diam. of 2.4 microns. These
particles due to their relatively large size are readily recovered by a
venturi-type scrubber using water as the absorbent.
8.
Remy~ H. Absorption of fogs appearing in chemical reactions.
28, 467-9 (1922); C. A. .!.I, 661 (2) (1923).
Chemical fogs such as S03 and NH4Cl may be differentiated as dry fogs and
wet fogs. The dry fogs consist of colloidal particles about 10-5 cm. in diam.,
and may be absorbed in conc. salt soIns. When the dry fog is contacted with
moisture, it forms wet fog. Wet fogs consist of particles about 10-4 cm. in
diam., and best absorbed by water.
Z. Elektrochem.
Remy ~ H. The absorption of chemical mist.
(1926); C.A. 20~ 1289 (1) (1926).
Z. anorg. Chem. 39, 147-150
Chemical mist consists of either dry or wet particles. The dry particles are
of the order of size of colloidal particles, while the wet particles are larger.
These particles do not behave like gas molecules but are more stagnant in
the gas stream so that when the gas stream is contacted with a liquid
absorber or a scrubbing fluid, the chances of absorption or wetting are much
less than the molecules of a true gas~ and the less the larger the particle.
Expts. confirmed this hypothesis. On the other hand, if a filter made of
paper ~ asbestos~ or cotton is used, the larger the particles the easier they
are removed from the gas stream. Electrostatic pptn. is most efficient in
removing the chemical mists.
Remy, H. The chemistry of colloids and dusts. I-II.
677-9, 698-9 (1928); C. A. ~, 4304 (8) (1928).
Expts. showed that conc. H2S04 removes H2S04 mist but not all S03 from
a gas stream contg. the two. H2S04 mist is nof absorbed when the gas
contg. it passes through an aq. soIn. of KOH. In the gas stream from a
contact HzS04 plant there is cloud of dry S03 dust which is distinct in
Chem. -Ztg. 52,
properties from the wet H2S04 mist. Results of measurements indicate that
the wet particles are larger than the upper limit of colloided particles while
the dry particles are smaller. Viscosity of the absorbing liquid has adverse
effect upon the percentage of S03 absorbed. Example: aq. soIns. contg. 0.0,
O. 1, O. 5 and 1. 0% gelatin showea absorptive power for S03 of 37.4, 29. 5~
22.3 and 5. 1%~ resp. However, wetting by water spray or steam makes the
dry S03 particles much larger and above the colloidal-partical range. These
enlarged particles form a mist. Although the mist is not absorbed upon
passing through pure water, it can be absorbed by passing it through strong
solutions of NH4Cl or CaCl2' or absorbed on gas-mask carbon on filter
paper, because the particles in the mist are sufficiently large.
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11.
12.
13.
14.
15..
~~ ~~~~
CONSULTING DIVISION
Remy. H. & Behre. C. The absorption of fogs blown out of fuming sulfuric
acid. Kolloid-Z. 71,129-145 (1935); C.A. 29.7741 (9) (1935).
The absorption of fogs satd. with moisture bears no simple relation to the
concn. of free S03 in the acid used. being nearly const. in the range 25-35%
SO . passing through a very sharp min. at about 40% SO . and increasing
wiih further increase in S03 content. The absorption of 10gs fro,m acid contg.
less than 35% S03 is higher them that of fogs with the same S03 content prepd.
from acid contg. more than 35% S03' Expts. in,which the fogs were dildo
with air show that absorption is independent of the S03 concn. of the fog. but
decreases linearly with increasing rate of flow. LiqUIds of low viscosity and
low surface tension appear to be the best absorbents.
Remy. H.. & Koch. C. The fogs occurring in chemical reactions. III.
Examination of chemical fogs for electrical charges. Z. anorg. allg.
Chern. 139. 69-80 (1924); C. A. ..!Q. 595 (8) (1925).
Carefully dried S03 and NH4CI fogs were examd. by lead and quadrant
electrometers but no charged particles could be detected. On passage
through a strong elec. field no deflection of the illuminated fogs could be
seen. After bubbling through H2?' such charges could be demonstrated. as
was found also to be the case wfth H and air. '
Remy. H.. & Seemann. W. The effect of bubble size on the absorption of
fogs by liquids. Kolloid-Z. 72, 5-12. 279-291 (1935); C. A. 29, 7742 (23)
(1935).
The absorption of H2S04 mist by a liquid is decreased as the size of the
bubble of the gas contg. the mist is increased.
Remy. H. & Vick, E. Absorption of chemical fogs in gas wash bottles.
Kolloid-Z. 68. 22-29 (1934); C. A. ~. 6358 (a) (1934). '
The absorption of damp NH Cl and S0-3 fogs, hav.ing opposite heats .of som. .
was tested with H 0. 96% EttOH and 1~o aq. gelatm some covered With ether.
in Drechsel. Volh~rd.. Winkler and Jena 83G1 fritted glass filter gas wash
bottles. The tests were at room temp.. 14. 5-22. 30. with gas flow of 0.2
1. Imin.. data were taken in each expt. for 6 mins. The best results. 98%
or better absorption. were in the bottles with the fritted glass filter. There
was little difference in the efficiency of the absorbing liquids.
Schytil. F. Absorption of sulfuric acid fumes. Ang. Chern. E!. 459 (1950);
Absd. by Ind. Chemist (London)~.. 229 (May 1951).
Absorption of H SO fumes (droplets of O. 5-3 micron diam. ) 'depends on the
water vapor pre~su~es of both the fume droplets and the absorbent liq.'
which is usually a H2S04 of certain concentration. The temp of the fume
and that of the absorbenf liq. is also an important factor.
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.cont'd 18.
19.
20.
~A~ ~~~~
CONSULTING DIVISION
removed. In an example where the acid is concentrated in the 2nd-stage drum
from 68 to 93% H2.S04' the mist content in the combustion gases entering the
electrostatic precIpitator is in the range of 240-340 mg/ cu. ft. (approx. O. 6-
1. 16% by wt. ).
Gillespie, G. R. & Johnstone, H. F. Particle-size distribution in some
hygroscopic aerosols. Chem. Eng. Prog. ~, 74-80 (Feb. 1955).
Samples of tail gases from a commercial contact H2S0A plant were taken at a
point about 3 feet above the absorption column. The S03 mist loading was
found to be 0.62-0.73 mg. /1., resp. (corresponding to 495 and 583 ppm. ;
resp., by wt.). The sizes of the particles of the H2S04 mist ranged from
0.2 to 1. 5 microns, and the size distribution was of the same pattern as
that of mists made in the laboratory made of SO 3 and humid air. The
particles of the mist grow in size with time.
U. S. Public Health Service. Atmospheric emissions from sulfuric acid
manufacturing processes. U. S. Public Health Service, Environmental
Health Services, Air Pollution. Publivation No. 999-AP-13, 1965, 127 pp.
U. S. Govt. Printing Office, Washington D. C., $0.60; Chemico reprint 2908.
U. S. has about 163 contact H2S04 plants and about 60 chamber H2S0..4...plants.
The primary emissions from the chamber plants contain S02 0.1-0. 'l.Ujo, N
oxides (mostly N02) 0.1-0.2%, and H2S04 mist 5-30 mg./scf. 90% of the
mist is larger than 3 microns in diameter. Equipment for reducing the
emissions beyond the Gay Lussac tower is rarely employed. Emissions from
the contact plants contain S02 0.1-0.5%, S03 0.5 to 48 mg. /scf., and H2S04
mist 3-15 mg. /scf. Electrostatic precipitators, glass-fiber mat or stainless
steel wire mesh pads eliminate 94-99.9% of the mist, but do not remove S02
or dry S03. Some plants use the Cominco process to reduce the S02 content
in the tail gas to about 0.03% in 2-stages of NH4HS03 scrubbing. But,
Cominco process does not remove H2S04 mist.
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21.
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Carmichael, Jr., L. and Reese, A. Apparatus for Removing Liquid Particles
in a Gas Stream. U. S. Pat. 3 339 351 (C1. 55-350), Sept. 5, 1967, (app1.
March 12, 1965).
Mists with particle size in the range 0.25 to 10 microns are removed from
gas streams by a 2 -stage "agglomeration filter" made of mats of fine
fibers (0.0003-0. 15 inch diam.). The first-stage mat is O. 1-0.5 inch
thick with 50-80% void. The second-stage mat is 4-6 inches thick with
97 -99% void.
22.
Plaut, W., & Fairs, G. L. (to Imp. Chem. Inds. Ltd.). Fiber filters for
the removal of fine mists. U. S. Pat 3 107 986 (C1. 55-97) Oct. 22, 1963
(app1. in Britain Nov. 28, 1956).
- 8 -
-------
~ont 'd 22.
~~~ ~~ ~~
CONSULTING DIVISION
Mists comprising aq. particles less than 5 microns in diam. are removed by a
mat of non-wettable fibers which range in diam. from 5 microns to 50 microns
and which are neither woven nor felted. The mats contain 80 to 98%
voids. The mist would collect on the fibers in the form of discreet droplets.
23.
----------------------------------------------------------------------------------
Fulford, E. H., & Searcy, J. E., Jr. (to Fram Corporation, Providence, R.1.)
Gas separator Ifilter apparatus. U. S. Pat. 3 201 924 (Cl. 55-324) Aug. 24,
1965 (appl. July 24, 1962).
The mist remover is made in cartridges of fibrous material, Gases carrying
mists pass from the outside to the inside of the cartridge and out through its
top. Liquid drops follow down from the inner surface into a sump.
24.
----------------------------------------------------------------------------------
25.
26.
Anon. -1956.
(1956).
Remove liquid entrainment better. Chem. Eng. 63, No.2, 230
The wire-mesh mist remover is manufactured by Metal Textile Corp. ,
Roselle, N. J. For liquid particles mostly 5 microns or larger a single mat
of multilayered knitted metal wire mesh will do. For liquid particles in the
submicron range, an extra mat is necessary to serve as a preliminary step.
This extra mat is made of layers of glass fibers and metal wire knitted
together in parallel. The glass fibers seem to cause the fog to coalesce.
After that the droplets of increased size are caught by the second stage mat
of all-metal wire mesh. These mats give high efficiency at low pressure
drop.
Baker, C.O., & Scauzillo, F.R. (to Socony Mobile Oil Co.) Mist extractor.
U. S. Pat. 3 010 537, Nov. 28, 1961.
A glass-wool mat is used to remove mists from gases.
Blasewitz, A. G., & Judson, B. F.. Filtration of radio active aerosols by
glass fibers. Chem. Eng. Prog. ~, 6-11 (Jan. 1955).
Satisfactory performance over periods of 1-3 years have been recorded with
air filters made of glass fiber mats at the Hanford Atomic Products Operation.
The filter units range in sizes from 200 to 20,000 cu. ft./min. The collection
efficiency of these units is about 99.99% when operated with gases contg. vary-
ing amounts of submicron particles and acid vapors; the lat ter often as high
as 50% by volume. (The glass fibers can be operated at a temp. as high as
5000F.) The pressure drop of the glass fiber filters was studied at super-
ficial velocity of 5-100 ft. Imin. The pressure drop is generally low (2.2-
4.0 inches water). Data are presented in terms of x, y, z, the exponents of
the equation b.. p = KLx py yz, and u. Where K = a constant; L = bed depth;
p = packing density; Y Y superficial velocity; and u = fiber diam. The glass
f16er air filters installed at Hanford are expected to last for at least 15
years without developing excessive back pressures.
----------------------------------------------------------------------------------
- 9 -
-------
27.
~~ ~~~~
CONSULTING DIVISION
Sze. M. C. (to Hydrocarbon Research Inc.) Mist removal from gases. U. S.
Pat. 2 801 709. Aug. 6. 1957.
A mist collector is specified in which the gas velocity increased progressively
as the gas passes from one stage to the next. each stage having a sieve plate
with holes facing an impact surface while the liquid resulting from coalescence
flowing by gravity to the collecting channels.
-----------------------------------------------------------------------------------
28.
Harris. L. S. (Schutte and Koerting Co.. Comwells Heights. Pa.) Fume
scrubbing with the ejector Venturi system. Chern. Eng. Prog. g. Apr.
1966. p. 55-59; C. A. ~. 341 d (1966).
Mist and dust particles smaller than 2 microns in diameter are effectively
removed from gas streams by scrubbing with an ejector Venturi scrubber.
The scrubber also acts as a suction pump so the gas under treatment may
flow at a desired rate without using a blower. For submicron particles in
the gas the ejector Venturi scrubber could be made with two-stages. The
collection efficiency increases with the liquid (water or alkaline solution) to
gas volume ratio. L/G; and for a constant L/G. it increases with the
motive pressure of the liquid supply.
-----------------------------------------------------------------------------------
29.
30.
Campbell. J. A.
1950.
Gas & Liquid Separator. U. S. Pat. 2 511 967. June 20.
The apparatus comprises a vertical cylindrical tank with a gas inlet tube
attached tangentially about the middle of the tank. Inside of the tank the
. cylindrical baffle plate and the gas outlet tube are arranged in a coaxial
manner attached at the top of the tank with the outlet tube protruding. There
is a liquid outlet at the bottom of the tank. Under operating conditions a
certain amount of liquid is retained at the bottom of the tank with the liquid
level high enough to seal off the bottom opening of the baffle plate but not
high enough to reach the outlet tube. The flow of ~as is directed along the
inner surface of the tank; at a point more than 180 away from the inlet tube.
the gas passes through a vertical slot at the top of the baffle plate into an
inner chamber wh ich is formed by the baffle plate and the outlet tube. The
bottom of the outlet tube is closed by a plate. but ti}ere are vertical slots
in that part of the outlet tube surrounded by the baffle plate. The same
part is wrapped around by multiple layer of wire -cloth. A layer of wire-
cloth is also provided along the inner surface set about 1/4" away from it.
Fisher. J. P.. & Downs. G. F. (to Empire Oil & Ref. Co.) Apparatus for
cleaning gas. U. S. Pat 1 824 713. Sept. 22. 1931.
A cylindrical vessel is specified into which the gas carrying entrainment is
passed through a ring of nozzles located around the lower part of the vessel
so as to impart a whirling movement to the gas as it passes up the cylindrical
vessel. In the upper part of the vessel hanging down from the centrally
- 10 -
-------
cont'cEO.
31.
32.
33.
CC~em«d ~~ CC~
CONSULTING DIVISION
located outlet tube is a cartridge of filtering screen through which the gas
finally passes on its way to the outlet. By using this apparatus the larger
droplets in the gas stream "W) uld be thrown against the inner surface of the
vessel and then fall down into a liquid reservoir below; and the smaller
droplets would adhere to the filtering screen and coalesce and then drop
off into the liquid reservoir which is maintained at a constant level by a
drain pipe with a trap.
Neeson~ C. R. (to Chrysler Corp.) Gas and liquid separator. U. S. Pat.
2 510 049, May 30, 1950.
The apparatus comprises a vertical cylindrical shell with a cartridge of
wire gauze fixed against the upper end of the shell where the gas outlet is
located. The inlet tube is located a little way from the top; said tube
protrudes inside the shell with the inside opening sealed off but a slot is cut
to permit gas to enter the apparatus horizontally and tengential to the
inside surface of the shell. There is a diaphragm which seals off the
annular space at the lower end of the said cartridge, so 'that all gas passes
through the gauze to the outlet nozzle. The lower part of the shell, that is,
below the diaphragm contains a reservoir for the liquid and a constant
level device connected with the discharge valve for the liquid.
Reynolds, S. C. (Metal Textile Corp. Roselle~ N. J.) Entrainment
eliminators save money. Petro Ref. ~, No.7, 138-140 (1953).
The device that removes liquid entrainment from vapors and gases is
knitted wire -mesh mat 4-8 inch thick that permits one to see light through
it and yet stops better than 99% of the entrainment of a particle size down
to 1 micron. The mat made of steel, Monel, or 18-8 stainless steel wire
(e. g., 0.011 inch in diam.) has free volume of 98%, and a surface area of
125 sq. ft. per cu ft. The mat in 18-8 stainless steel costs $9. -$10 per
sq. ft., 4 inches thick. That in plain steel costs 1/4 as much. In operation
there is a range of optimum vapor or gas velocity to be used which is high
enough to cause impingement of the droplets and prevent them from drifting
through the mat~ and yet not too high as to sweep the coalesced drops from
the mat into the down-stream vapor or gas. With air-water system at
atmospheric pressure~ the optimum velocity range was found to be 2-12 ft. /
sec. In vacuum the upper limit would be increased, while under pressure
it would be reduced. Due to its open structure, the resistance to gas flow
is very low, e. g., not over 1 inch of water.
York, O. H. Performance of wire-mesh demisters.
421-4 (Aug. 1954); C. A. 48, 11122 h (1954).
Chern. Eng. Prog. 50,
The wire-mesh type of entrainment remover as applied to distillation
columns is described. The wire-mesh most commonly used is a knitted
mat made of O. Oll-inch wire of Monel or other metal with a bulk density
- 11 -
-------
~:ont'd 33.
~~~ 1t'~ ~~
CONSULTING DIVISION
of approx. 12 lbl cu. ft. and a surface area of 110 sq. ft. I cu. ft. The
efficiency of entrainment re moval for a 4-inch thick mat is 99. 9 wt. % over
a wide range of vapor or gas velocities, e. g., 3-13 ft. per sec. The
pressure drop is rarely more than 1 inch of water. By suitable arrangement
an effluent may contain as low as one part of liquid per 1~ billion parts of
gas or vapor by weight. The cost of wire -mesh mats including the support-
ing grids is estimated for a typical installation: total capacity 50, 000 cu.
ft. Imin.} wire mesh made of 18-8 stainless steel or Monel metal; approx.
$24.00/(100 cu. ft.) (min.).
----------------------------------------------------------------------------------.
-----------------------------------------------------------------------------------
34.
35.
36.
Fair, G. L. Removal of acid mist. J. Soc. Chem. Ind. 60, 141-6 (1941);
C.A. ~, 7661 (8) (1941).
H2S0 4 mist produced during the manufacture of the acid is commonly
removed from the tail gas by 3 methods: (1) The packed scrubber, eg.,
the coke filter; the removal is satisfactory, but its bulkiness makes it un-
popular. (2) The centrifugal separator; it removes particles down to 2
microns in diam. ; scrubbing efficiency is about 970/0. (3) The electrostatic
precipitator; it removes particles all sizes, and gives a scrubbing
efficiency of 99. 9%.
Kerrigan, J. V., Snajberk, K., & Anderson, E.S. (Univ. of California,
Richmond). Collection of sulfuric acid mist in the presence of a higher
sulfur dioxide background. Anal. Chem. ~, 1168-1171 (1960); C. A. 54,
23449 b (1960).
. The electrostatic precipitator, the Greenburg-Smith impinger, and the
sintered-glass filter are evaluated as to their efficiency in collecting H2S04
mist when a higher S02 background is present. The results show that these
instruments yield reproducible results over the concn. range of O. 5-150
mg. H2S04 mistl cu. m., and are efficient at low and high concns. This
study esta15lishes the ability of these instruments to collect H2S04 mist
accurately at concns. found in the atm. under field conditions.
Massey, O. D. (Stauffer Chem. Co., Houston, Tex.) Demister for sulfuric
acid plant stacks. Paper presented at Air and Wat.er Pollution Abatement
Conference, M. C. A., Cincinnati, 0., March 1959; abst. in Chem. Eng.
66, July 13, 1959, p. 143-6; Chem. Eng. Prog. 55, May 1959, p. 114-8;
Sulphur (London) Sp. issue 1959, p. 16-19; C. A. El, 14608 h (1959).
Using a 2 -stage wire-mesh demister unit on the tail gas of a 98% H2S04
plant, a tenfold reduction of acid mist was obtained at pressure drop of
1. 5-2.0 inches of water. This corresponds to a H2S04 content of 1-2
mg. I cu. ft. in the stack gas, and the stack plumes were practically
invisible. However the wire-mesh demister unit, even with a 3rd stage,
was found ineffective when used on the tail gas of an oleum plant.
- 12 -
-------
~Aenuad ~~ rc~
CONSULTING DIVISION
cont'd 36.
Other mist removers, which were less efficient than the knitted wire mesh,
were also tested. They were (1) packed beds of Berl saddles, (2) vane-type
baffles, and (3) Lurgi filters (porous ceramic thimbles). Performance data
of these and the knitted wire mesh demister are given as follows:
Comparative Filter Performance Data
Pressure Drop, Mg. H,SO./Cu. Fl. Mg. H2SO./Cu. Fl.
In. H20 Inlel Outlel
Packed Bed; 12-10. Lay':!r of 1-10. Ber! Saddles--Table I
(Velocity: 7, 10, 12 and 20 fl./sec.) .
% 16.5 14.5
* 18.3 6.4
1 V
-------
37.
~~ ~~~~
CONSULTING DIVISION
Alekseeval M. V. 1 & Andronov1 B. E. Absorption of sulfuric acid.fog. Lab.
Prakt. (U. S. S. R.).!!, No.1, 8-21(1941); C. A. ~I 4921 (7) (1941).
H2S04 and HN03 fogs completely absorbed by an aq. soIn. of 0.02 N alkali
praced in a train of 5 wash-bottles in series with gas velocity 0.25-0. 5
1. Imin. and pressure drop of 130 mm. Hg. The gas stream passes a
fritted glass filter in the 3rd-stage wash bottle.
-----------------------------------------------------------------------------------
38.
BtanskYI D. W. 1 & DiworYI D. J. Removal of sulfuric acid fog by bubble
phase absorption. Nat '. Petr. News 32, No. 22, R -200-1; Refiner
Natural Gasoline Mfr. .!.Q, 191-5 (1940); C.A. 341 6054 (2) (1940); Proc.
Am. Petro Inst. 10th mid-yr. meeting. !!.I 39-45 (1940).
The gas contg. H2S04 fog is scrubbed with a soIn. of a petroleum sulfonic
acidl which forms a loam and catches 93-95% of the H2S04 fog in 10-11
sec.
-----------------------------------------------------------------------------------
39.
40.
41.
42.
Anon. -1960. Ceramic filter for acid mist. Brit. Chern. Eng. ~, June
19601 p. 400.
The Lurgi ceramic filter for H2S04 is a bundle of tubes through which the
pores are of a specially designed Size and number. In operation gas
enters the tubes placed at the base of the stack before an induced draft fan.
The H2S04 mist coalesces in the pores and flows down as a liquid stream
on the outside of the tubes where it is collected and recovered. The clean
gas passes through the tube wall and out into the stack.
Edeleanu G. m. b. H. Removing sulfur trioxide mist from gases.
Pat. 549 3421 Feb. 41 1928; C. A. ~I 3860 (4) (1932).
The gas contg. S03 mist is passed through a filter made of mineral material
which is kept moist.
German
Fletcherl A. W. (Fuel Research Station, London, England.) Determination
of sulfur trioxide in gases. The efficiency of a sintered-glass filter in
recovering sulfuric acid mist. Chern. & Ind. 19541 777-8; C. A. 481
11244 d (1954).
Gaseous mixt. contg. 0.0002-0.004% SO as H SO mist were analyzed
for S03 by the Corbett method (J. Inst. ffuel 2:t1 2~7-251 (1951); C. A. 46,
237 i (1952). The results showed a high efficiency of collection of
H2S04 mixt. on the "Grade 4" sintered-glass filter.
Leonard, C. L., Schneider, C. R., & Sheppard, J. K. (to Union Carbide
Corp.) Sulfuric acid mist removal. U. S. Pat. 2 906 372, Sept. 29, 1959;
C. A. 541 988 b (1960).
Gas streams contg. H2S04 mist are passed through a plate of porous Si02.
which is continuously wetted by 60-72% H2S04 at 1100-1300 to remove the
H2S04 mist from the gas stream. .
- 14 -
-------
43.
44.
~~mnU:d <;t'~ CC~
CONSULTING DIVISION
The removal of sulfuric acid mist. Ind. Chemist~. 220-2
Markward. H. G.
(May 1960).
The operating data of the Lurgi ceramic filter tubes for the removal of H2S04
mist are given. When the pressure drop across the filter is properly adjusted
the amount of mist in the gas stream is decreased from 0.34-0.589 to 0.002-
0.20 gr. S03/SCF. resp. The pressure drop across the filter is 9 inches
water at start and 12 -13 inches towards the end of the 3rd month of operation.
Schytil. F.. & Krollmann. H. (to Metallgesellschaft A. G.) Collecting the
liquid contained in mist. U. S. Pat. 2 947 382. Aug. 2. 1960.
The H2S04 mist is filtered out by a ceramic plate with pores in the range
0.2-3 microns.
----------------------------------------------------------------------------------
45.
46.
Anon. -1959. New installation for pollution control. Chem. Eng. Prog. 55.
Mar. 1959. p. 41.
At Allied Chem. Corp's H2S04 plant two batteries of electrostatic pptor.
have been installed to reprace a row of coke-boxes for the removal of
H2S04 mist. Another row of coke boxes is retained for the time being.
Ruibnikov. G. Effect of steam on the degree of precipitation of sulfuric
acid mist. Khimstroi 2. 45-46 (1935); C. A. £Q. 3200 (b) (1935).
The H2S04 mist is more effectively removed by introducing steam into the
gas ana pass the gas through a coke filter. The amount of S03 removed is
nearly doubled by this improvemm t.
----------------------------------------------------------------------------------
47.
48.
Perevezentsev. 1. G.. & Tarasova. A. A. Separating S03 from S02 during
the determination of the degree of contacting in the production of contact
sulfuric acid. Trudy Ural. Nauk. -Issledovatel. Khim. Inst. 1957 No.4.
223-6; C.A. 54. 6054 b (1960).
A mixt. contg. 6-7% SO and 0.2-0.4% SO in air corresponding to gas
mixts. at the exit of con~act app. in the H2~0 4 production is bubbled
through 3-4 mm. of H20 or dU. H2S0 A to form a fog of H2S04' The fog
is removed in a high-voltage electro-filter. This simplifIes the analysis
of the residual S02' since the gas leaving the electrofilter is entirely
. free of S03' but its S02 content does not change.
Stastny. E.P.
precipitation.
(Koppers Co. Inc.. Baltimore. Md.) Electrostatic
Chem. Eng. Prog. g. Apr. 1966. p. 47-50.
- 15 -
-------
[ont'd 48.
49.
50.
~A~ ~~ ~~
CONSULTING DIVISION
Between 85 and 95% of the H SO 4 mists from the oleum tower are particles
smaller than 2 microns, whi1e only about 30% of the particles from the 98%
acid absorber are smaller than 2 microns. To remove H2S04 mists of less
than 2 microns, the ordinary wire -mesh type mist collector is not effective,
but an electrostatic precipitator serves the purpose with high efficiency. At
a low, but practical, gas rate through the electrostatic precipitator, the
exit gas contains as low as 0.03 mg H2S0 4 per SCF when treating gas from
a 98% H~O 4 absorber. In one installation attached to a combination of 2
white 9tlu/o acid, 1 black 99% acid, and 1 black 104. 5% oleum tower, the
mist loading was 9 mg. H2S0 4/SCF. and the stack gas had a residual mist
content of 0.08 mg. H2S0 4/SCF. The H2S04 plant stack usually shows a
visible plume when the residual mist is more than O. 12 mg. H SO /SCF.
The N oxides, if present in the H SO 4 tail gas, is also eliminated ty the
electrostatic precipitator. The Sb2 present in the H2S04 plant tail gas is
mostly eliminated in the precipitator by the action of ozone produced by
the corona effect on the electrodes. The ozone oxidizes SO to form SO
and the moisture (after purposely added) converts it to H2Sd 4 mist whic~ is
removed along with the mist originally present.
Stopperka. K. (Tech. Univ., Dresden, Germany) Electrostatic deposition
of sulfuric acid mists from waste gases of sulfuric acid manufacture.
Staub (Dusseldorf)~, 508-512 (1965) (in German); C.A. 64, 12202 c (1966).
Pilot plant in vestigation, using different sized plates, various humidities,
and different shaped discharge electrodes are discussed. The system that gave
the best results used Korobon tube electrodes (Korobon is graphite within
a phenolformaldehyde matrix which proved corrosion -free after 4 months
of continuous use) and the addn. of water at the rate of 15 g. /m~ (which
gave a clear condensate with 25 to 55% H2S04). Detailed dimensions of
the lead-barbed discharge electrodes anaother operating data are
presented.
Stopperka, K., Neumann, V., & Hose, W. (Univ. Dresden, East Germany).
Electrostatic separation of sulfuric acid clouds. Chem. Tech. (Berlin) g,
321-7 (1966); Brit. Chem. Eng. II, 807 (Aug. 1966); C. A. 65, 18203 e
(1966).
The electrostatic precipitator was studied in connection with the removal of
SO~ from exhaust gases of the Gips process. The S03 content was approx.
62U mg. per cu. m. Water was sprayed into the gas stream sothat the
liquid collected from the electrostatic precipitator is an approx. 50%
. H2S04. Tests of various designs of the component showed that the tubes
are better than plates as acid collectors and a twisted ribbon with up-
pointing spikes is preferred as the corona electrode. The tubes are made
of impregnated carbon (Korobon). Gas velocity is 1. 96 m. /sec. corres-
ponding to a residence time of 2.04 sec. At a voltage of 70 kv. the
removal of S03 was complete.
----------------------------------------------------------------------------------
- 16 -
-------
51.
52.
53.
~~ ~~~~
CONSULTING DIVISION
Brink~ J. A. (Monsanto Chem. Co.) Blocks air pollution~ snares 1700 lb. of
H2S0 4 per day. Chem. Processing ~~ Feb. 1962, p. 40-41.
H2S0 4 mist is removed by filters made of glass fibers made in the form of
bags nanging from a tube-sheet. The unit consists of 22 bags or tubes 18"
diam. and 8' long reinforced by resistant wire mesh. The gas volume
handled was 22,000 SCF Imin. at 180oF. contg. 0.3-3. 0 micron H SO
particles. The pressure drop across filter' was 7.25 inches of wafer. 4
Removal was 99.98%. Quantity recovered was 1,700 lbs. H2S04 per day.
Chapman, F. F. (to Canadian Inds. Lt d.) Separation of chemical mists from
gases. Can. Pat. 442~ 210, June 17~ 1956; C. A. !!, 6446 f (1947).
H2S0 4 mixt. is removed from gases by passing them through a fabric woven
from glass fibers.
Fairs~ G. L. (Imp. -Chem. Inds. Ltd.) High efficiency fiber filters for the
treatment of fine mists. Trans. Instn. Chem. Engrs. 36, 476-485 (1958).
H SO 4 mist of less than 2 microns diam. has been effectively collected by
a 1ilter pad made of silicone coated glass wool. The silicone coating renders
the glass fibers water repellent and causes coalescense of the H2S04 droplets,
and an improvement of mist collection of 12 times. (The exit gas from un-
coated glass wool contained O. 2% H2S04.) Garnetted terelyne polyester fiber
gave similar results as coated glass fiber, with a scrubbing efficiency of
99. 6%.
54. . Gille, H. The absorption of chemical clouds. Z. angew. Chem. 39, 401-2
(1926); C.A. 20~ 2712 (4) (1926).
55.
Gas from pyrite burners~ if moist, may be freed from S03 by passing the
gas through a plug of wadding. The S03 thus retained may be recovered by
washing the wadding. If the gas is dry the wadding retain5 little or no S03.
Hennig~ R. R. (to Allied Chem. Corp.) Filter for removal of droplets from
gas streams. U. S. Pat. 2, 771~ 153, Nov. 20, 1956; C. A. 53, 20953 b (1959).
Droplets of liquid~ e. g. H2S04' entrained in a gas stream are removed
by passing the mixture through an app. contg. filter material, e. g. glass
wool~ permeable to gas but not to liquid. Liquid draining from the filter
forms a seal at the bottom, preventing the mixt. from by-passing the filter.
56.
Vashke~ E. V.. Amerlin~ A. G.. Petrovskii, V. A. ~ & Osmulkevich, V. A.
Glass wool filters for trapping sulfuric acid mist. Khim~ Prom. 1965 (3)
196-200 (in Russian); C. A. ~, 1499 f (1965).
- 17 -
-------
[;ont'd 56.
YJ~ ~~ CC~
CONSULTING DIVISION
Two types of filters packed with glass wool (compn. Si02 70.5-72.5. CaO 6.7-
6. 9. MgO 3.9 -4. O. Na20 14. 6-17. 1. and trivalent metaT oxides 1. 7 -2. 1 %) with
a fiber diam. of 25 microns are described; lab. expts. showed that the glass
wool resisted prolonged effect (400-600 hrs.) of 75-98% H SO . but was
destroyed by more dil. acid. The hydraulic resistance ('6,m o!filters packed
to a height of 100-300 mm. with glass wool increased with increasing content
of H2S04 mist in the gases passing through the filter and with increasing gas
velocity; the degree of trapping of the mist increased with increasing.6.H and
with increasing diam. (d) of the H SO 4 droplets in the mist. within the d
range between O. 3 microns and 1.1) mIcrons. Large -scale expts. showed
that when the initial mist content in the gas was 38-60 g. 1m. 3, a degree of
purification of 99. 7% (i. e.. a final mist content of O. 12 g. 1m. 3) was
obtained by using a filter with a ~H of 160-390 mm. Hg. Although the
expenditure of elec. energy needed to transport the gas thJ:>ugh a glass-wool-
packed filter is larger than that needed for an electrostatic precipitator, the
glass -wool filter is preferred because of its much lower cost and lower
maintenance.
57.
Wong. J. B.. Ranz. W. E.. & Johnstone, H. F. (Univ. of Ill.) Collection
efficiency of aerosol particles and resistance to flow through fiber mats.
J. Appl. Phys. ~, 161-9 (1956); C. A. 50. 11725 a (1956).
The collection efficiencies for H2S04 aerosols of 0.4-1. 3 microns particle
diam.. and the resistance to flow through glass fiber mats composed of
3. 5. 6.2. and 9. 6 micron fibers. were investigated. The results agree
with the theory that particle collection in this range is a function of the
. inertia of the particles. the interception by the fibers. and the nature of the
flow around the fibers. as characterized by the inertial parameter ~ ratio
of the diam. of the aerosol particles to the diam. of the fiber (interception
parameter). and that the pressure drop is a function of the flow character-
istics and the fiber interfering effect. Theoretical equations for collection
efficiency and pressure drop of the fiber mats were analyzed in terms of
the impaction efficiency and drag coefficient of single fibers. These
equations were evaluated by comparing the apparent fiber efficiency and
drag with theoretical values. (~= SiDe; S = stopping distance of a particle
in still gas when given initial velocity, Vo; and Dc = diam. of glass fiber. )
----------------------------------------------------------------------------------
58.
St~.des Forges et Chantier de la Mediterranee. Purification of combustion
gases. Fr. Pat. 1 399 747 (Cl. C 01b) May 21, 1965 (appl. 10,1964);
. C. A. 64. 487 c (1966).
An app. and process for the purification of gas produced by the combustion
of fuel oil or coal in boilers are described. in which a heat exchanger contg.
porous metal granules cools the gas below its dew point, and the granules
entrain the mist of H2S04 produced by the combination of S02 and S03 with
condensed H20. .
----------------------------------------------------------------------------------
- 18 -
-------
59.
60.
~km«J ~~ ~~
CONSULTING DIVISION
Chemiebau Dr. A. Zieren GmbH. (Zieren, A., & Schuett, H., inventors).
Se~ration of fine sulfuric acid mists. Ger. Pat. Appl. 1,217,347 (Cl. C
01b) May 26, 1966 (appl. Sept. 15. 1952); C. A. ~, 10183 e (1966).
H2S04.-contg. gas is passed through a thin layer of granular Pb or glass
matenal (2- 5 mm. ) in spherical or other form at a rate of 1750-3700
m. 3/hr. m2. to sep. the H2S04 mixt. The sepn. unit can consist of 3 or more
layers of granules or spheres. The tail gas of a H2S04 chamber
process was passed through a bed of the above-described S102 spheres
at 3150 m3. Ihr. m2. The mist content of 300 mg. was reduced to 10
mg. 1m3. The Reynolds no. was 199. The process is useful for the sepn.
of all finely divided H2S04 mists which consist of liquid droplets, as they
occur, for instance in the production of H2S04' in the purification of 802-
contg. gases prior to catalyst treatment, ill tfie conversion of H2S to
H2S04' etc.
Hartig, R. G.. & Archer, J. R. (to Int'!.
Recovery of chemical mists from gases.
1959; C.A. ~, 22794 d (1959).
Mists of S03' halides, and P 205 are removed from gases by passing the
latter through beds of 10-80 mesh inert material while passing a liquid
countercurrent to it, but in an amt. insufficient to flood the voids,' and thus
maintain a back pressure on the gas stream o'f 10-30 in. H20.
Min. & Chern. Corp.)
U. S. Pat. 2,901,061, Aug. 25,
--------------------------------------------------------------------------------
61.
62.
Danser. Jr., H. W. Eliminate stack dusts and mists. Chern. Eng. El,
May 1950, p. 158-160.
A siren -type sonic generator creating a sound pressure of over 150 decibels,
operates in the passage of a gas contg. H2S04 mist amtg. to 300 mg of
H2S04 per cu. ft. The sound agglomerates tlie fine liq. particles which
are then collected by a number of small-diam., high velocity, cyclone
dust collectors operating in parallel. A normal contact H2S04 plant gives
a tail gas containing generally less than 60 mg. H2804 mist per cu. ft.,
while the tail gas leaving a drum concentrator may contain as high as 300
mg. H2S04 mist per cu. ft. A sonic precipitator would reduce the mist
contenf down to less than 5 mg. I cu. ft., which would be low enough to meet
the air pollution control requirements in a majority of localities.
Jahn, R. A new method for the separation of sulfur trioxide mist from
gases containing sulfur dioxide. Papier (Darmstadt, Germany)~, 433-
. 4 (1962); C. A. ~, 655 h (1963).
A simpler method has been devised for the sepn. of S03 microparticles
than that requiring electrofilters. The new technique resorts to sound
waves transmitted through appropriately placed pipes. In this way, the
very finely divided 803 particles are coagulated so that they can be re-
moved to the extent of 99% of the S03 present in the mist. The new tech-
nique is also considerably cheaper tlian the on e requiring electro filters .
- 19 -
-------
63.
~~~ 't#'~ ~~
CONSULTING DIVISION
Nord. M. (Wayne Univ.. Detroit. Mich.)
and dust particles. Chern. Eng. ~, Oct.
1950. p. 158-160.
Sonic precipitation of smoke fumes
1950. p. 116-9; cf. ibid.. 57. May
The theory of sonic precipitation of aerosols from a gas stream is discussed.
High-intensity sound waves (on the order of 160 decibels equivalent to 2 watts/
sq. cm.) produce vibrations of the aerosol particles at velocities correspond-
ing to their respective sizes. This results in collisions of the aerosol
particles. Collisions produce coagulation in the case of solid particles and
coalescence in the case of liquid particles. The resulting larger particles
may then be collected by small-diam. multiple cyclones. An installation of
a sonic precipitator unit built by Ultrasonic Corp., Cambridge, Mass., is
shown (photo. and schematic drawing) attached to a contact H2S04 plant.
-----------------------------------------------------------------------------------
64.
65.
66.
Adadurov. 1. E.. & Gernet. D. V. The absorption of sulfuric anhydride by
water vapor. Zh. Khim. Prom. ~, (18) 12-16 (1931); C.A. ~. 2279 (a)
(1932).
From 6 to 8% of the S03 formed in the contact process is lost as an
undissolved fog. If this fog is passed through water and then into a Cottrell
app., the loss is reduced to 2.3-2.7%. However, the method is costly and
complex. Between 338-4500 S03 reacts with water vapor to form H2S04
directly. If the fog is allowed to remain in contact with steam for 3-6 sec. ,
reaction takes place, and 99% of the S03 is recovered in the condensed
H2S04.
Kraus. R. Method and apparatus for the analytical determination of
sulfuric acid fogs applied to the roasting and contact gases of the sulfuric
acid industry. Angew-Chem. 48, 227 -8 (1935); C. A. ~, 4903 (3) (1935).
The gas contg. O. 35 vol. % SO and other gases including SO was
saturated with water vapor at fooo and passed through a conJenser at a
velocity sufficiently slow to condense most of the water vapor. The
product gas contained 0.06 vol. % S03 but retained all of the S02.
Remy. H.. & Finnern. H. Fogs resulting from chemical reactions. IV.
Adsorption of a chemical fog by a liquid and by solid materials. Z. anorg.
allgem. Chern. 159. 241-255 (1926); C.A. ~. 1388 (1955).
The H2S04 fog in a gas stream is effectively removed by injecting steam
. into the gas and then condensing the steam. whereby 98% of the HfO 4 in
the gas stream is removed from the gas stream.
-----------------------------------------------------------------------------------
- 20 -
-------
67.
~km«:d ~~ ~~
CONSU L TI NG DIVISION
The
Remy, H., & Ruhland. The fogs occurring in chemical reactions. II.
absorption of chemical fogs. Z. anorg. allg. Chem. 139, 51-68 (1924);
C. A. .!.Q, 595 (7) (1925).
The rate of absorption of dry 803 and NH 4 Cl fogs by aq. H2804. and NH 4 Cl
soms., resp., was found to depend on the concn. of the absortimg som.
The absorption rate-concn. curves are parallel to the corresponding b.
p. -compn.. curves. The rate of absorption of moist 803 or NH4Cl decreases
with increasing concn. of the absorbent.
----------------------------------------------------------------------------------
68.
69.
70.
Anon. -1965. A "fog broom" utilizing nylon thread.
Dec. 4, 1965. p. 79.
Laboratory experiments showed that a "tunnel visibility" could be made
through heavy atmospheric fog in about 6 min. by a network of fine nylon
threads wrapped around a revolving frame mounted on a truck travelling
through the fog.
Chem. Week 97,
Fiber filters for fine acid mist.
Brit. Chem. Eng. ,i, 137
Anon. -1959.
(Mar. 1959).
The filter is made of Terylene fiber or silicone (1. C. 1. Silicone M441)
coated glass fiber compressed to 2" thick pads either circular and made
into tubes. (Forming temp~ Terylene 1400 -16001 Silicone-glass 4000-
5500). H2S0.3 mist >2 microns is completely removed (e. g. inlet gas contg.
O. 1 g. H2S04 gave a outlet gas contg. O. 0005-0. 000 7 g. H2804. per cubic
meter. Due 1:0 the hydrophobic nature of Terylene fiber, tlie mlst collects
on the filter in drops and falls off so that the filter is selfdraining. The
fiber is 5-50 micron in diam. The unit is manufd. by Mancima Eng, Ltd.
and by Nordac Ltd. of England.
Brink, J. A., Jr. (Monsanto Chem. Co.) Monsanto solves air pollution
problems with new fiber mist eliminator. Chem. Eng. 66, Nov. 16, 1959,
p. 183-186.
A cartridge-type mist eliminator comprising a vertical sleeve of double-
layer wire screen filled with a synthetic fiber packing has been developed
for H2.S0 4 and H3PO 4 mists and showed an efficiency of 99.95% on 0.3 to
3.0 mlcron particles under high gas velocity and low pressure drops, e. g.
400-500 ft/min. at 6-8 inches of water, Several full-scale installations
(up to 20,000 SCFM) have been put into service to replace the electrostatic
precipitators which were incurring excessive operating and maintenance
costs. The capital cost of these mist eliminators (on the order of $50,000
for a 20,000 SCFM installation) is only a fraction of that for the electro-
static precipitator of the same capacity.
- 21 -
-------
71.
CCknuad ~~ ~~
CONSULTING DIVISION
Brink, J.A.. Jr., Burggrabe, W.F.. & Rouscher, J.A. (Monsanto Co.. St.
Louis, Mo.) Fiber mist eliminators for higher velocities. Chem. Eng. Prog.
60, Nov. 1964, p. 68-73, d. Chem. Eng. 66, Nov. 1959, p. 183-6; Phos. &
Potas. (London) N~, 28-29 (Apr. -May 1966).
A "high velocity" type of mist eliminator has been developed and improved.
The performance characteristics of this mist eliminator as installed on top
of H PO 4 and 99% H2S04 absorption towers are given in 3 tables and 3
grap~s. Examples: For H3PO 4' gas velocity 600 ft/min., mist loading
28.2 mg. P 205/SCF, removal efficiency 94.6%, pressure drop 9 inches
water. For 1I9U;O H2S04' gas volocity 600 ft. Imin., mist loading 18.6 mg.
H2S0 4/SCF., removal efficiency 97. 3%, pressure drop 8 inches water.
72.
Brink, J. A., Jr., Burggrabe, W. F., & Greenwell, L. E. . (Mbii'santo Co. ,
St. Louis, Mo.) Mist eliminators for sulfuric acid plants. Chem. Eng.
Prog. 64, Nov. 1968, p. 82-86; cf. ibid., 60 Nov. 1964, p. 68-73; Chem.
Eng. ~, Nov. 16, 1959, p. 183-6.
Knitted wire mesh made from 316 stainless steel (wire diam. 0.011 inch)
has been extensively used to eliminate H2S04 mists in the tail gas of
contact H2S04 plants, but stainless steer-is subjected to excessive
corrosion by B8-99% H2S0 at 180-200oF. The latest innovation in H2S04
mist elimination is to use ~enon fiber mats supported by special alloy
grids. This type of demister collects H2S0 1: mists of particle size less than
3 microns and for that purpose it is as eIficlent as the electrostatic
precipitator. It costs more than the stainless steel wire mesh mist eliminator
but much less than the electrostatic precipitator both in capital cost and in
operating cost. Three types of H2S04 mist eliminators are discussed: (1)
The "spray catcher" comprising generally a 2-stage horizontal mat of
knitted stainless steel wire mesh, glass fibers or synthetic fibers, supported
by metal grids. (2) The "high velocity" mist eliminator comprising a Teflon
fiber mat supported between alloy grids vertically disposed above the
absorption tower, generally operated at gas velocities of 400-500 ft. Imin.
(3) The "high efficiency" mist eliminater similar in principle as the high
-velocity mist eliminator but operated at a much lower gas velocity, i. e. ,
15-40 ft. Imin. It is generally built in a multiple-cartridge form. The
individual cartridges are constructed with two concentric alloy wire
screens with fine Teflon fibers packed in the annular space between the two
screens. The gas flows from the outside through tre fiber packing and the
collected H2S04 drains down the inside surface of the cartridge to its
. closed bottom and is returned to the absorber through a liquid seal. The
"high efficiency" mist eliminator works satisfactorily on 99% H2S04
absorbers and on oleum towers. It is claimed that the removal efficiency
on less than 3 micron H2S04 mists is as high as 99. 98%. Some operating
characteristics of the three types of mist eliminators are given as follows:
(See next page for Table)
- 22-
-------
~~t'd 72.
73.
74.
75.
~~ ~~~~
CONSULTING DIVISION
Table 1.
Operating characteristics of various types of fiber mist
eliminators as used on sulfuric acid plants.
High Efficiency High Velocity Spray Catcher
Brownian Impaction Impaction
. Movement
Controlling mechanism for
mist collection
Superficial velocity (ft./min.) 15 to 40 400 to 500 400 to 500
Efficiency on particles Essentially Essentially Essentially
greater than 3 microns 100% 100% 100%
Efficiency on particles 95 to 99+% 90 to 98% 15 to 30%
3 microns and smaller
Pressure drop ("W.C.) 5 to 15 6 to 8 112 to 1
Meinhol~, T. F. (ed.) Three-way payout for H2S04-gas cleaner. Chem.
Processmg 29, Mar. 1966, p. 63-64; cf. YorK, 0. H., & Poppelle, E. W.,
Chem. Eng. Prog. 59, June 1963, p. 45-50.
The H2S04 mist removal system at Chemicals, Inc., Bartow, Fla. was
developed "by York Separators, Inc. It is made of Teflbn fiber materials
supported by stainless steel grid. The mist remover was installed over
the 20 ft. diam. S03 absorbers (2 used for the 900 tons/day plant). 56-87%
of the H2S04c mist particles measure less than 3 microns. The cleaned gas
leaving a 200 ft. high stack contains about O. 6 mg. S03 /SCF, which is well
within the limit set by the State of Florida. The acid thus recovered
amounts to 2. 5 tons / day.
Morash, N., Krouse, M., & Vosseller, W. P. (National Lead Co., South
Amboy, N. J.) Removing solid and mist particles from exhaust gases.
Chem. Eng. Prog. 63, Mar. 1967, p. 70-74; C. A. 66, 118554 Z (1967).
An irrigated, thin, felted, fiber filter is described with a pilot-plant technique
for the removal of sub micron-size Ti02 dust and H2S04.. acid mist particles
from laden exhaust gases. Feeds contg. 0.44 g. T102/ft.3 and 1. 56 g. acid
mist/ft. 3 are exhausted with zero Ti02 and O. 02-0. Og g. acid mist/ft. 3.
Pressure drops of 5. 5 to 10 in. water at gas flow rates of 1 to 5 ft. /sec.
are experienced. A min. flow rate of 8 gal. spray liquor /1000 ft. 3 gas is
required for high mist removal efficiencies. Both polyester and polypropy-
lene fibers are evaluated.
York, 0. H., & Poppele, E. W. (Otto H. York Co. Inc.) New acid gas
cleaner for sulfuric acid plant. Paper presented at Air Pollution Control
. Association meeting, Jacksonville, Fla., Nov. 3, 1965; abst. Sulphur
(London) No. g, 30, (Dec. 1965).
In the new acid gas cleaner, a matrix of Teflon FEP fluorocarbon fibre is
used to remove minute particles of sulphuric acid and oleum that appear
in absorber effluent. Teflon was selected as the base material, partly for
- 23 -
-------
cont'd 75.
Yt~
-------
78.
Source of
'2504 Mist
,ontact Acid
lant
,oaster Gas
Chloro
IUlfonic acid
lant
79.
~~ ~~~~
CONSULTING DIVISION
Ekman, F. 0., & Jolmstone, H. F. (Univ. of Illinois, Urbana). Collection of
aerosols in a Venturi scrubber. Ind. Eng. Chern. 43, 1358-1363 (1951).
For the removal of H2S04 mist from gas streams using the Venturi scrubber,
the following data are given:
Water Rate
Gal. 11,000
cu. ft. gas
Gas Velocity at
Throat-ft. I sec.
Mist Loading
gall cu. ft.
In Out
Removal
Efficienq
0/0
Pressure DroI=
Inches Water
171
190
0.6
99 7
4.3
9.7
171
309
1.7
99 4
7.2
14.5
756
7.8
98.9
Kristal, E., Dennis, R., & Silverman, L. (Harvard Univ. Cambridge, Mass.)
Evaluation of an experimental French wet scrubber "Solivore". U. S. Atomic
Energy Comm. Report NYO-461?', 1957, 50 pp.; C. A. ~, 7 f (1958).
An exptl. French wet scrubber, the Solivore, was tested for efficiency in
removing air-suspended matter such as fly ash, coarse and fine H2S04 mists,
and Fe oxide fumes. This 600 cu. ft. Imin. unit has 4 collection stages in
series, each contg. 2 1. 5-horsepower, 9-gal. Imin., 7-lb. Isq. in. spray
generators, and a Venturi tube in which the gas attains a 12,000 cu. ft. Imin.
. max. velocity. The spray gener ators use a rotating mech. interrupter to
disintegrate small liquid jets. Wt. collection efficiencies were detd. with
inlet dust loadings of 0.2-2.0 grains/cu.ft. and water rates of 6-12 gal. Imin. I
spray generator for 1-2-, and 3-stage operation. Single-stage efficiencies were
fly ash 99, coarse H2S04 mist 95, Fe oxide fume 22, and fine H2S04 mist 5%.
Efficiency varied directly with the no. of collection stages and water rate, and
inversely with the gas flow. Total pressure loss for one-stage operation
(including droplet elimina tor) was 4.5 in. of water at rated capacity. An
addnl. pressure loss of 2-3 in. of water per stage was observed for multi-
stage operation.
----------------------------------------------------------------------------------
80.
Anon. -1967. Mahon's fog smog scrubber. Sulphur (London) No. 68, 35
(Jan. -Feb. 1967>.
To clean particle-laden fumes from a 100 ton p. d. sulphuric acid concentrator,
R. C. Mahon designed and built an air cleaner. The polluted air is sucked into
three giant silo-shaped chambers and scrubbed with fog created jet-force
streams of water broken up by 800 special nozzles. The resulting water-
soaked whirlwind spins gases and contaminants at high angular velocity. The
accumulated centrifugal force hurls the contaminants to the chamber's bottom,
- 25 -
-------
~ont'd 80.
81.
f(l~ ~~ CC~
CONSULTING DIVISION
where they are washed away. The fog-scrubbed air is discharged into the open.
The unit is operated by Atlas Chemical Industries for the Volunteer Army
Ammunition plant near Chattanooga, Tenn.
Richter, F. (Virginia-Carolina Chern. Corp., Richmond, Va.) Pollution
control equipment pays off in two years. Air Eng. ~, 27-29, 53 (1960);
C. A. 54,20030 a (1960).
Air pollution by H28iF £' 802' or 803 mists, and flakes of solid fluorides
from the acidulation oIphosphate rocK dust with H2804 was controlled by
low-velocity (490 ft. Imin.) cell-type, water scrubbers. The effluent
passed through a series of five 24-ft. towers with water sprays discharging
counter to the air flow.
---------------------------------------------------------------------------------.
82.
83.
Wong, J.B., Ranz, W.E., & Johnstone, H.F. (Univ. of Ill.) Inertial
impaction of aerosol particles on cylinders. J. Appl. Phys. 26, 244-9
(1955); C. A. 49, 5038 f (1955).
The impaction of H2S04 aerosols of nearly uniform size ranging from O. 6
to 1. 4 micron in diam. on 2 Pt. wires, 29 and 83 microns in diam.., and 2
Wwires, 53 and 106 microns in diam. was measured at several velocities of
flow past the wires. Reynolds numbers ranging from 13 to 330 were used.
For values of the square root of the inertial parameter 'f below 1. 4, the exptl.
efficiencies of impaction agree with those predicted by Langmuir and
Blodgett for potention flow and by Anandahl and Herrmann for a Reynolds
number of 10. The exptl. values are higher than the calcd. valu es for If 1 12
greater than 1. 4. The theoretical predication that a critical value of If 1 I 2
exists at approx. 1 14, below which inertial impaction does not occur was
verified.
York, 0. H., & Poppele, E. W. (Otto H. York Co. Inc.) Wire mesh mist
eliminators. Chern. Eng. Prog. 59, June 1963, p. 45-50.
The operating characteristics of knitted wire-mesh and synthetic fiber mat
mist eliminators are discussed. Examples of practical applications are
gi ven among wh ich are the dem isters us ed in con tact H2804 plants.
Certain design data are also given. When synthetic fibers are used
instead of knitted stainless steel wire mesh, the fiber mats are supported
on stainless steel, Monel, Carpenter 20, titanium, or Hastelloy grids.
A typical mist eliminator is composed of a Teflon fiber mat sandwiched
. between Hastelloy C grids.
----------------------------------------------------------------------------------
----------------------------------------------------------------------------------
- 26 -
-------
84.
85.
86.
~~~ ~~ ~~
CONSULTING DIVISION
Lamm, C., Schumann, H., & Klauss, J. Removal of nitrogen-oxide-contain-
ing sulfuric acid fumes. East Ger. Pat. 50 584 (Cl. C 01b) Oct. 5, 1966
(appl. Apr. 17, 1965); C. A. 66, 96985 m (1967).
3
Off-gases from a H2S04 plant, contg. NO and S03 0.925 g. Istandard m.
are passed at a velocity of 3.5 m. Isec. through a 80-mm. high Joam layer
of 980/0 Iii'04' The resulting off-gases contain S03 O. 04 g. 1m. and are
free of NO.
Rosenbloom, W. J. (CheTI. Construction Corp.) Recovery of oxides of
sulfur and fluorides from gas mixtures. U.S. Pat 3 031 262 Apr. 24, 1962
(appl. Feb. 27, 1959); C.A. 57, 10781 e (1962).
Off-gases from the calcining of phosphate rock are (1) scrubbed with H2S04
in a spray chamber to cool the gases and to remove S03 and particulate
material, (2) scrubbed with NH 4 sulfite-bisulfite soIn. m an absorption
tower to remove S02 and HF, (3) discharged to the atm. The liquid stream
from the absorption tower is (1) autoclaved with air to oxidize (NH4)2S03;
(2) treated with a metal sulfate (e. g. MgS04) to ppt. metal fluoride; (3)
filtered to remove solids, including Si02; and (4) crystd. to recover
(NH4)2S04'
Tigges, A. V. (to Air Preheater Corp.) Recovering heat and sulfur
compounds from hot gaseous products of combustion. U. S. Pat. 2 863 723
Dec. 9, 1958; C. A. 53, 5645 c (1959).
The gases may be cooled below their dew point if the heat-exchange surfaces,
.e. g. rotary regenerative air preheaters, and sprayed with noncorrosive 700/0
H2S04' The acid is reclaimed with the recovery of absorbed S02 or S03'
-----------------------------------------------------------------------------------
87.
88.
Chem. Construction (G. B.) Ltd. (Syers, R., inventor) Removal of sulfur
oxides from flue gases and stack gases. Brit. Pat. 826 221, Dec. 21, 1959;
C. A. 54, 10289 h (1960).
NH3 is added to flue gas or H2S04 plant stack gas at a temp. higher than the
dew point of the flue gas or the stack gas. The S02 and S03 present in the
flue gas or the stack gas are converted to solid (NH4)2S03' (NH4)2S ° 4' and
NH4HS04 which is removed from the flue gas or the stacK gas by passage
through an electrostatic precipitator or a cyclone. The process reduces the
air pollution caused by the flue gas or the stack gas.
Momose, S. (Chubu Elec. Power Co., Nagoya, Japan) The prevention of
corrosion by sulfuric acid of heavy oil burners. Netsu Kanri.!.Q, No. 10
20-22 (1958); C. A. ~, 19349 a (1959).
- 27 -
-------
cont'd 88.
~~ ~~CC~
CONSULTING DIVISION
The stack gas of an elec. generating boiler system which burns heavy oil
contg. 2.8-3.0% S is reacted with NH3 gas to reduce the amt. of S0;i. The
dew point dropped sharply (from 140 to 450) by blowing 0.01-0.02% NH3
with respect to the oil. The dew point of the flue gases with addn. of
0.02-0.12% NH3 (based on wt. of oil) was almost const. at 450.
---------------------------------------------------------------------------------
89.
90.
Hohmann. H. Removal of sulfur dioxide and S03 from exhaust gases. East
Ger. Pat. 55 743 (cl. B Old) May 5. 1967 (appI. Aug. 25. 1966); C.A. El.
76124 x (1967).
The process is to pass the exhaust gas through a mill contg. CaCO~1 before
being sent to the chimney. The CaCO is granulated and dried in tfie mill
and as a result the mill contains 50-1&0%. relative water vapor. and the
adsorbent has a large surface area. S02 is removed from the gas by
adsorption on CaC03 and the formation of CaS03. 1/2H20.
Lowenstein-Lorn. W. G. (to Standard Oil Dev. Co.) Removal of sulfur
oxides from flue gases and their conversion to ammonium sulfate.
Brit. Pat. 708 095. Apr. 28. 1954; C.A. 48. 11033 c (1954).
Gases contg. S02 and S03 are scrubbed.with ~n aq. suspension of
~g(OH). The sp.e~t scrubbin? soin. now contg. MgS03.and MgS04
IS aera~ed and oXIdIze MgS03 Into MgSO 4. After this operation the
solution is treated with NH3 gas to convert MgSO 4 into Mg(OH)2 and
.(NH4 )2S0 4. The Mg(OH)2 separat ed and used to make a fresh
suspension for scrubbing. The (NH 4 )2S0 4 seln. is concentrated to
crystallize the (NH4 )2S0 4. .
---------------------------------------------------------------------------------
91.
Dr. C. Otto & Co. GmbH. (Struck. C. H.. inventor.) Removal of sulfur
oxides from industrial gases. Ger. Pat. 1 234 912 (cl. F 23j) Feb. 23,
1967 (appl. Dec. 2, 1961); C.A. 66. 97014 f (1967).
S02 and S03 are removed from gases by washing with a 35-80% H2S04
sorn. contg. peroxysulfuric acid (1) equiv. to 5 -60 g. H202/1. at a temp.
> 600 which is also in excess of the dew point of the gas being cleaned.
The H2S04 formed is continuously removed and the used I is regenerated
. by anoQic oxidn. The gas may be subjected to previous mech. cleaning
and (or) be cooled to room temp. and reheated for cleaning. Thus. to
clean at 800 a gas having a dew point of 700. a 5-15 sec. contact with 37%
aq. H2S04 contg. the equiv. free 02 of 20 g. H202/1. is satisfactory.
- 28 -
-------
92.
~~ ~~~~
CONSULTING DIVISION
Simon-Carves Ltd. Sulfur oxides elimination in residual gases. Belg. Pat.
613 590. Feb. 28. 1962 (Brit. appl. Feb. 25. 1961); C.A. El. 9460 c (1962).
S02 and S03 were extd. from fumes and chimney gases by passing the
ascending gases through a 40-80% aq. H2S04 spray contg. peroxydisulfuric
acid (1) and H20. Part of the wash som. was recycled, part withdrawn and
a nd treated for rI2S04 recuperation and an equiv. amt. of H ° added, and
part cooled and regenerated by an electrolytic cell to strenJhen I and H202'
this being facilitated by halide ion addn. To recuperate HC1-free H2S04'
either the gases were first H20 washed, or the recuperated H2S04 distd.
-----------------------------------------------------------------------------------
93.
94.
Crossley. H. E. (Fuel Research Station. D. S. 1. R.. Greenwich, England.)
The reduction of sulfur trioxide by constituents of boiler-flue dust. J. Inst.
Fuel~. 207-9. 213 (1948); C. A. 42. 4326 g (1948).
Boiler plants fired by pulverized fuel are relatively immune from the
corrosion and deposit difficulties sometimes encountered on the external
heating surfaces when mech. stokers are used. An investigation of the
reduction of S03 to S02 indicates that this immunity may be partly due to
the presence of fly-asl1 particles rich in magnetite, Fe304. Magnetite
reduces S 03' the action being most pronounced at temps. above 5000.
Coke. also present in flue dust. reduces S03 at temps. below the ignition
point of the coke. The remaining fraction of the flue dust from powd. -fuel-
fired boilers had little. if any, reducing action on S03. It seems possible
the the max. possible reduction of S03 in a boiler might be secured by
introducing the coarser part of the magnetic fraction of powd. -coal fly-
ash into the gas in the combustion chamber, with a view to the deposition
of some Fe 04 on the heating surfaces where the reduction takes place. The
best metho~ of reducing the S03 by C would probably be the introduction of a
C smoke near the boiler outlet. or the arrangement of a bed of suitably
sized carbon or coke across the gas stream in the duct between the boiler
and the economizer. In this position the temp. of the flue gas is usually
3000. and there should be little loss of C by burning. In the lab. expts.
the efficiency of reduction of S03 by coke was 100% at 3500.
Hansen. W. The reduction of sulfur trioxide by solid particles in flue gases.
Oelfeuerung (Stuttgard. Germany) E.. 90-94 (1961); C. A. 56, 7619 b (1962).
S03 in a stream of N is reduced to S02 when passed through a reaction tube
contg. black fly ash or Fe304 at 300-7000 or fly coke at 200-7000. White
fly ash and Si02 are less effective. S03 in a stream of N. 0, and H20 is
reduced to S02 when passed over fly coke. gas coke. or smelting COKe at
3500 or Fe304 at 500- 6500. Essentially no S03 remained in the reaction
tubes contg. coke or Si02.: A layer of Fe203 retained 97% of the entering
S03 as SO 4-- at 350-50OV. Fe304 retained 37 and 34% resp.. at these
temps.
- 29 -
-------
95.
~~ ~~~~
CONSULTING DIVISION
Siemes-Schuckertwerke AG. Separating a constituent from a gas stream.
Brit. Pat. 1 003 419 (Cl. B 04 b. c) Sept. 2. 1965. (appl. June 21. 1963);
C.A. 63. 14405 g (1965).
Finely divided « 6 micron) Fe2-03 is sprayed into a flue-gas stream at 2500
to remove SO and SO : ~FeO + 6S0 + 30 -+ 2Fe2(SO ) and Fe203 +
3s03-.Fe2(st> 4)3. T~e speJ Pe2(S0413 is Jecompd. at ~O:Oo to recover
Fe203 and 803 for conversion to H2S04.
--------------~-------------------------------------------------------------------
96.
97.
98.
Feustel. K.. Johswich. F.. & Stratmann. H. (to Reinluft GmbH. Germany).
Removal of sulfur oxides from fuel gases. U. S. Pat. 2 992 065 July 11.
19 61; C. A. ~. 2 6390 b (19 61) .
A hot gas stream contg. S02 and SO is passed over a carbonaceous
absorbent. e. g. charcoal. at 150-251>0 to absorb S03. The gas is then
cooled to 100- 500 and passed over the absorbent to rerm ve S02. The
absorbent is then heated to reduce S03 to S02' and then the S02 is purged
from it.
Oesterreichische Stickstoffwerke AG. (Huber. F.. inventor.) Portland
cement. Austrian Pat. 195.830. Feb. 25. 1958; C. A. 52. 6756 g, (1958).
In a process of the manuf. of portland cement from cement raw material.
e. g. clay and lime contg. small amts. of sulfatic impurities. the powd.
raw material is mixed with small amts. of solid fuels. approx. sufficient
to reduce its 803 contents. and the mixt. is calcined in an inert gas atm.
before formation of the clinker. Preferably N or the gas from the end zone
of the calcination furnace is used as inert gas. and the reduction treatment
is conducted in the same furnace as the formation of the clinker.
The use of reducing agents
Zh. Prikl. Khim. ~.
Vitukhnovskaya. M. S.. & Belyanskaya. E. A.
for the regeneration of the spent sulfuric acid.
2427-2434 (1960); C.A. 55. 7769 d (1961).
The kinetics of reduction of S03 to S02 was studied by passing mixts. of
803 and N with and without CO througn an empty reactor. retention 0.2
min.. and through a reactor filled with activated C. retention O. 09 min.
The amt. of S02 formed. x. at 8000 under all conditions increased as the
concn. of S03 in the initial gas increased from 1 to 17%. The presence of
CO increased x very little. x increased with the temp. in the 500-8000
range. but at all temps. it was much higher over activated C than with CO.
despite the lower retention time. The difference increased at higher temps.
Even at 5000 x was higher over C (86%) than at 7000 with CO. At 7000 over
C. x = 96%. Reducing with C at 8000 resulted in the formation of S. The
rate of reaction 2S03 + C -"'2S02 + C02 passed through a max. at 5000; that
of S03 + C ~ 802 +CO decreasea as the temp. increased from 400 to 7000.
and iliat of 2803=42802 +02 increased at first slowly below 6000 and very
rapidly above BUOo.
- 30 -
-------
99.
Y5~ ~~ CC~
CONSULTING DIVISION
Wahnschaffe, E. Desulfurization of smoke gases by the clear-air method.
Mitt. Ver. Grosskesselbesitzer No. ~, 72-74 (1963); C. A. 59, 3254 b (1963).
From 1000 to 2000 cu. m. /hr. fuel oil combustion gas, emanating at a temp.
of 2000 is passed through a precooler, a cooler, a reusable semicoke
absorber to remove 802 and 803' a desorber, and a heater (to 4000) for
desorbed gases to remove the 8-content in the form of pptd. 8. The app.
operated satisfactorily under a wide range of industrial conditions.
-----------------------------------------------------------------------------------
100.
Mandelik, B. G. (to Chem. Construction Corp., New York, N. Y.) Complete
recovery of sulfur dioxide. U. 8. Pat. 3 059 995 (Cl. 23-177), Oct. 23,
1962 (appl. May 11, 1960); C.A. 58, 2190 e (1963).
The off-gas derived from sulfating roast of sulfide ores at 400-8000 contg.
0.5-3% 80 , 6-9% 802' and entrained dust was heated to 900-14000 by
burning H2~' refinery sludge acid, natural gas within the gas stream with
air addn. 1f required, thus decompg. the 80 to 802 and ° and recovering
all 8 values; 803 remaining is < 0.05%. The ~ot gas stream partially cooled
by a waste heat boiler to approx. 3500 was then H20-scrubbed, further
cooling it and eliminatmg the dust. .
-----------------------------------------------------------------------------------
101.
Cerny, F. Recovermg sulfur oxides from combustion products. Czech.
Pat. 100 363, July 15, 1961 (appl. Aug. 5. 1958); C.A. 58, 2190 f (1963).
. When the combustion gases are cooled below the dew point prior to escaptmg
mto the atm., the resulting condensate absorbs entire 803 and a part of 802'
another part of which is bound by the wet volatile ashes. Addn. of steam to
the combustion gases aids the effect by coolmg the gases and increasing the
dew point of the products.
-----------------------------------------------------------------------------------
102.
Hrdlicka, K. Absorbing sulfur dioxide and trioxide from industrial fumes
by the zinc method. Czech. Pat. 90 701, June 15, 1959; cf. Tech. Chem.
(Prague) Q (5), 236-241 (1962); C.A. 54, 9230 d (1960); g, 3608 c (1964).
The 802 - and 803 -containing gas is scrubbed with an aqueous slurry of
Zn(OH)2. The liq. effluent from the scrubber contains Zn(H2803)2'
Zn804 and crystalline Zn803 -2. 5 H20. This effluent is treated ill either
of the followmg two ways: (1) thermal decomposition of Zn(H803)2 and
Zn803. 2. 5 H20 to give 80~ gas and regenerate ZnO; (2) adding H280 to
drive off 802 and recover "Zn804 as a byproduct. 4
-----------------------------------------------------------------------------------
-----------------------------------------------------------------------------------
- 31 -
-------
103.
104.
105.
~A~ ~~ rc~
CONSULTING DIVISION
Anon. -1969. Controlling the S03 content of industrial flue gases. Sulphur
(London) No. g, 30-31 (May-June 1969).
The Siemens "Sulfotherm" continuous analyzer is briefly described. It
takes a gas sample at 450oC, filters it and mixes it with watervapor at
200oC. The S03 in the sample reacts with water vapor to from H2S04
which is condensed. The condensed H2S04 is reheated to 1000C to
drive out any S02 and C02. The H2S04 -contg. liquid is again cooled and
its electric conductivity is measured and recorded in terms of S03 content
in the gas. Four scales are provided on the instrument, the lowest CD vers
the S03 range 0-100 mg. Icu. m., and the highest scale 600-3500 mg. Icu. m.
Central Electricity Generating Board (Jackson, P. J., & Laxton, J. W.,
inventors.) Measurem ent of gas concentration in gas mixtures. Brit.
Pat. 1 030 541 (CI. G 08c) May 25, 1966 (appl. Jan. 2, 1964); C. A. 65,
3006 a (1966.>.
The gas mixt. is passed at a known rate into an extractor to dissolve a
particular gas. The subject some is passed thro ugh a reactor bed which
contains a reagent capable of giving a colorimetric response to the
particular gas. An optical cell is filled with the colored some for photo-
elec. detn. of the absorbance. Thus, S03 is removed from flue gas by
aq. (preferably 4:1 vol. IvoI.) iso-PrOH prior to reaction with Ba
chloroanilate which liberates reddish acid chloroanilate ions with max.
absorption at 535 m micron. The me thod is good to 0.2 ppm. and is
particularly suitable for flue gases from oil-fired boilers.
Corbett, P. F. (Brit. Coal Utilization Research Assoc.) The determination
of sulfur dioxide and sulfur trioxide in flue gases. J. Inst. Fuel 24,
247-251 (1951); C. A. 46, 237 i (1952).
A method is described for the determination of small traces of S03 in
the presence of a large excess of S02 by using 80% ,iso-propanol both
as the oxidation inhibitor and absorbent.
----------------------------------------------------------------------------------
----------------------------------------------------------------------------------
----------------------------------------------------------------------------------
- 32 -
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~
==
<:
-------
~~ cc~ ~~
CONSULTING DIVISION
I
II
III
IV
V
VI
VII
VIII
A BIBLIOGRAPHY OF REMOVAL OF
NITROGEN OXIDES FROM WASTE
GASES, EXCEPT METHODS BASED
ON REDUCTION A T HIGH TEMPERA TURE
AND CA TALYTIC DECOMPOSITION
1907-1968
WITH ABSTRACTS
TABLE OF CONTENTS
(Subject Index)
PART ONE
Removal of Nitrogen Oxides From
Chamber-and Mills- Packard Sulfuric
Acid Plant Tail Gases
Absorption in concentrated sulfuric acid
Absorption in ammoniacal solutions
Ref. No.
1 to 8
Reaction with ammonia in the vapor phase
Absorption in sodium hydroxide solutions
9, 1 0, 39
11,12,13
14
Addition of fine water spray before electrostatic
precipitation
Adsorption on active carbon
15
16, 17
18
Adsorption on phosphates
Adsorption on fluidized peat
19
PART TWO
Removal of Low Concentrations of
Nitrogen Oxides From Waste Gases
-------
~~ ~~~~
CONSULTING DIVISION
Ref. No.
I Nitrogen oxides (NO + N02) removal by absorption
a. Absorption in water 20 to 29, 149
b. Absorption in sulfuric acid and H2S04 - HN03
mixtures 30 to 3 7
c. Absorption in ammoniacal solutions 38 to 44
d. Absorption by ammonia in the vapor phase 45 to 49
e. Absorption in alkaline solutions 27, 50 to 56,
61, 121
f. Absorption in carbonate solutions 57 to 74
g. Oxidation - scrubbing 7 5 to 82
h. Absorption in ferrous salt solutions 83 to 89
i. Absorption in sulfite solutions 90 to 92
J. Absorption in calcium and/or magnesium
oxide and hydroxide slurries 93 to 101
k. Absorption in limestone slurries or with wet
limestone 102, 103
1. Absorption by moist iron on manganese oxides 104 to 106
m. A bsorption by iron sulfide 107 to 109
n. Absorption by dry oxides and hydroxides 11 0 to 115,
140
o. Absorption in aqueous organic solutions 116 to 12 1
p. Absorption in anhydrous organic liquids 122
II Nitric oxide, NO, removal by adsorption
a. Adsorption on active carbon 123 to 125
b. Adsorption on alumina 126
c. A dso rption on clay 127
d. Adsorption on graphite 128
e. Adsorption on silica gel 129 to 132
f. Adsorption on zeolite 133, 134
III Nitrogen oxides (NO + N02) removal by adsorption
a. Adsorption on active carbon 135 to 140
b. Adsorption on aluminum silicate 141 to 143
c. Adsorption on silica gel 26, 144 to
151, 153,
ii 154
-------
~~~ ~~ ~~
CONSULTING DIVISION
d.
Adsorption on zeolite
Ref. No.
150, 152 to
155
e.
Adsorption on ion -exchange resins
Adsorption on peat
156, 157
158
f.
Hi
-------
~~ ~~~~
CONSULTING DIVISION
A BIBLIOGRAPHY OF REMOVAL OF
NITROGEN OXIDES FROM WASTE
GASES, EXCEPT METHODS BASED
ON REDUCTION AT HIGH TEMPERATURE
AND CA TA LYTIC DECOMPOSITION
1907-1968
WITH ABSTRACTS
PART ONE
Removal of Nitrogen Oxides From
Chamber-and Mills-Packard Sulfuric
Acid Plant Tail Gases
1.
Beavers, G. E. Absorption of nitrogen oxides in the chamber acid
process. Chem. Met. Eng. ~, 280-2 (1925); C~ A. .!.Q, 1328 (1) (1925).
At Copper Hill, Tenn., the tail gases from the chamber H2 SO 4 plant
was scrubbed with H2S04 as the absorbent. The efficiency of N oxides
absorption was investigated with respect to the sp. g., purity and
temperature of H2S04' It was found that the amount of N oxides
absorbed increases dIrectly with the sp. g. and the purity, and
inversely with the temperature.
2.
Bylov, V. D., Znamenskii, Yu. D., Kapitonova, L. P., & Shchedrov,
M. S. Scrubbing nitrogen oxides from partially oxidized gases with
sulfuric acid. Zh. Prikl. Khim. ~, 1503-5 (1962); C.A. 57, 12098
i (1962). .
The efficiency of absorption of nitrogen oxides in 93% H SO is
materially increased if the nitorgen oxides are first oxiaize~, for
example, by passing them through a 93% H2S04- containing 3-4% HN03'
This increase was shown to be from 41. 5% to 79%, In a laboratory
set-up> a column 2 m. high having 8 bubble plates was used. The lower
2 plates were irrigated with the HNO 3 - H2S0 4 mixture and the upper 6
plates by 93% H2S04'
3.
Fairlie, A. M. Recovering nitrogen oxides in sulfuric acid manufacture.
U. S. Pat 1 420 477, June 20, 1922; C. A. ~, 2969 (2) (1922).
S02 is removed from exit gas of a H2S04 plant by oxidation, and lower
N oxides are then oxidized to higher oxides and absorbed.
- 1 -
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rJ~
-------
10.
~~~
-------
12.
13.
~~ ~~~~
CONSULTING DIVISION
Varlamov, M. L., Manakin, G. A., Staroselskii, Ya. 1., & Zbrozhek, L. S.
Investigation of the ammonia method for the purification of gases from low
concentrations of nitrogen oxides. Zh. Prikl. Khim. ~, 8105 (1963);
C. A. 59, 239 b (1963).
Lab. scale investigations were carried out on the NH3 Ire thod of purification
of gases from low concns. of N oxides, by using gaseous NH3. In using
acoustic coagulation of the NH4N02 and NH4N03 aerosols, tHe degree of
removal of the N oxides is """'85% and does not depend on excess NH3 in the
gas mixt. Completeness of the reaction of N02 and equimol. mixts. of
NO and N02 with gaseous NH3 averages 81-91. 4% and increases little with
increase in the reaction vol. The NH3 method of gas purification was
investigated in a H2S04 tower system on lab. equipment by using gas -lifting
app. and electrofilfers for the removal of NH3 compds. from the exhaust
gases. The lower degree of purification of prow ction -scale gases com-
pared to that obtained under lab. conditions is primarily due to the lower
degree of NO oxidn. in the inflowing gases. However, with a recalcn. of
the compn. of the oxides to an equimol. mixt. of NO and N02' the degree
of purification of production gases reasonably approaches that obtained
in the lab. expts.
Ya. 1.
Varlamov, M. L., Manakin, G. A., Zabrozhek, L. S., & Starosel'skii,
Purification of gases of tower nitrose sulfuric acid systems. Sb. Tr.
Odessk Med. Inst. 1961, No. 15, 44-51; C. A. 57, 14703 i (1962).
The re moval of N oxides from waste gases of H2S production by the tower
process by means of a reaction with NH3 gas was studied; an aerosol of
NH -nitrite-nitrate is thus formed. The size of the reaction space has
littte effect on this process; 93% reaction is achieved. The effect of the
concn. of N oxides and NH3' the degree of NO oxidn., and the time of
sound treatment on the acoustical coagulation of the above aerosol were
studied. The degree of purification reached 87%. Trapping of the aerosol
(produced by the reaction of waste gases in NH3 water in a gas-lift app. ) in
an elec. filter was studied. At 30.7 and 44% oxidn. of NO, the degree of
purification was 51. 2 and 80.4%, resp. The content of N oxides in the
gases as a result of such purification can be increased by increasing the
degree of NO oxidn. and by using optimum conditions. In an alk.
medium at <700, decompn. of NH4 -N02 is negligible.
-------------------------------------------------------------------------------
14.
Varlamov, M. L., Manakin, G. A., Zbrozhek, L. S., & Starosel'skii, Ya. 1.
Purification of exhaust gases of a nitrose-sulfuric acid system in a foam
apparatus at a pilot plant installation by using water and caustic soda.
Izv. Vyssh. Ucheb. Zaved. Khim. i Khim. Tekhnol. .!.Q (8), 948-9 (1967);
C. A. 68, 14557 c (1968).
- 4 -
-------
14.
Con t 'd
~~
-------
~.kmiad
-------
~~ ~~~~
CONSULTING DIVISION
A BIBLIOGRAPHY OF REMOVAL OF
NITROGEN OXIDES FROM WASTE
GASES, EXCEPT ME THODS BASED
ON REDUCTION AT HIGH TEMPERATURE
AND CATALYTIC DECOMPOSITION
1907-1968
WITH ABSTRACTS
PART TWO
Removal of Low Concentrations of
Nitrogen Oxides From Waste Gases
20.
Andersen, L. B., & Johnstone, H. F. (Univ. of Ill.) Gas absorption
and oxidation in dispersed media. J. Am. Inst. Chern. Engrs. 1.,
135-141 (June. 1955).
The absorption and subsequent liquid-phase reaction of oxygen was
studied with two types of dispersion apparatus, the Venturi atomizer
and the fritter-glass disperser. The systems st!-1died in both devices
included the absorption of atmospheric oxygen by ca talyzed sodium
sulfite solutions and the simultaneous absorption of atmospheric
oxygen with nitrogen dioxide and with sulfur dioxide by water. Very
large values of the liquid-film mass transfer coefficient for oxygen
absorption were observed in the atomization zone of the Ventrui
atomizer. Over-al~ recovery efficiencies were less than 2.3% for
nitrogen dioxide but reached as much as 22% for sulfur dioxide.
Oxidation efficiencies for sodium sulfite solutions ranged up to 80%;
depending on the operating conditions. The fritted-glass disperser
gave recovery efficiencies of nitrogen dioxide as high as 90% from
air containing 10% of the gas. The recovery efficiency decreased at
low concentrations of nitrogen dioxide for both the Venturi atomizer
and the fritted-glass disperser.
- 6 -
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21.
22.
23.
24.
~knud 'lf~ ~~
CONSULTING DIVISION
Critchley, T. (to Johnson & Sons' Smelting Works, Ltd., England).
Oxidation of nitrogen oxide fumes. U. S. Pat. 2 581 518 (Cl. 23-102)
Jan. 8, 1952 (appl. in England Feb. 17, 1948).
Pure 02 is added to the waste gas contg. NO and the whole is
scrubbed with water to remove all oxides of nitrogen. The NO is thus
first oxidized to N02 and the latter absorbed in the scrubbing water.
Farbwerke Hoechst Ag. Removal of nitric oxide from cracked gas.
Belg. Pat. 613 976, Aug. 16, 1962 (Ger. appl. Feb. 15, 1961);
C. A. 59, 4950 e (1963).
Hydrocarbon gases contg. 0.001-0.2 vol. % NO, 10% min. alkanes,
and O. 5 min % 0, preferably 0.8-1. 2%, are purified by compression
to 7 -16 atm. at 10-400 and immediate washing with H20 or an alk.
aq. soIn. of pH > 7. Thus, 31. 5 m. 3 /hr. (at normal "temp. and
pressure) of a cracked gas contg. H 28.7, CO 15.5, C02 11. 6, CH4
11.7, C2H6 O. 8, C2H4 16.5, C2H2 6.2, other unsatd. compds. 2. 6,
N 6.0, 0 0.45, anaNO 0.015 vol. % was compressed to 7.5 atm.
abs. at 300 and washed with 2000 1. /hr. of H20 with a residence time
of 50 sec. in the column. The NO content was reduced to 0.0135%.
When the ° content was increased to 1.15 vol. %, the NO content after
washing was 0.0001% max. When the H20 was replaced by a 2% aq.
KHC03 soIn., no NO could be detd.
Ganz, S. N., & Kuznetsov, I. E. Rate of absorption of nitrogen oxides
in hollow columns provided with a centrifugal sprayer. Zh. Prikl.
Khim. ~, 1686-1692 (1963); C. A. 60, 3414 f (1964).
The absorption column used for this investigation was a hollow
cylinder, with a centrifugal sprayer at top. Grates at top and at
bottom of the cylinder rendered uniform gas distribution throughout
the column.
Kopita,' R.,. & Gleason, T. G. (Peabody Eng. Corp., New York, N. Y. )
Wet scrubbing for boiler flue gas. Chem. Eng. Prog. 64, Jan. 1968,
p. 74-78; C. A. 68, 53005 r (1968).
A discussion and review of scrubbers which can remove S02' N
oxides, and particulate matter in a single unit was presentea and
included comments on air pollution code requirements, efficiencies
of actual installation, construction materials, flow cycles, and
savings effected with a 300,000 lb. /hr. steam generator. Flow
sheets are shown for removal of solids, S02' and N oxides with and
without provision for water reuse. A wet scrubbing system can be
designed to remove 99% of the fly ash from pulverized coal and
stoker-fired boilers and 70-99.5% of the S02 in the flue gas.
- 7 -
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YJ~ ~~ CC~
CONSULTING DIVISION
25.
26.
27. .
Kramers, H., Blind, M. P. P., & Snoeck, E. (Tech. Hoges chool,
Delft, Netherlands). Absorption of nitrogen tetroxide by water jets.
Chern. Eng. Sci. li, 115-125 (Jan. 1961); C. A. 55, 19372 a (1961).
Laminar water jets of different lengths were exposed to a pure N02/
N ° mixt. at pressures between O. 06 and O. 3 atm. The amounts
ojH~02 and HN03 found by chemical analysis in the liquid leaving
this absorption system were interpreted in terms of absorption of
N204 and its subsequent reaction. The manner in which these N204
aosorption rates depend on the partial pressure of ~2~.4 and the Jet
length strongly support the working hypothesis that N2CJ" is
preferentially absorbed under simultaneous reaction witt water
according to fairly rapid first order rate formula.
Peters, M. S. (Univ. of Ill.) Stop pollution by nitrogen oxides.
Chern. Eng. g, No.5, 197 -200 (1955).
Data on removal efficiency of N oxides in gases by water and by
silica gel are given. When water was used as absorbent, data are
obtained from spray tower, one-tray bubble-cap column, packed
column, and one-stage fritter-glass-plate diffuser. The N o.xide
content in the gas range from O. 2 to 1. 9 vol. % calcd. on a mixt. of
N02 + 2N204' High efficiency (48% removal with a gas contg. 1. 9%
N oxides) is obtained with the fritted glass diffuser. Removal
efficiency is below 32% in all other cases within the range of N
oxide concens. tested. The adsorption efficiency of nitrogen
oxides on silica gel is comparable to absorption efficiency of the
bubble-cap column.
Peters, M. S., Holman, J. L. (Univ. of Ill.) Vapor- and liquid-
phase reactions between nitrogen dioxide and water. Ind. Eng.
Chern. 47, 2536-9 (Dec. 1955).
The results of exptl. work have indicated that both gas-phase and
liquid-phase reactions occur in the remOi al of N02 from gases by
contact with aq. solns. The major part of these reactions does
not occur in the bulk phases, but takes place in the gas film and the
liquid film at the boundaries between the t\\O phases. The presence
of NO in the exit gas, and the increase in temp. in the absorption
column indicate the existence of the gas -phase reaction. The
occurrence of liquid -phase reaction is indicated by the fact the
rate of removal of N oxides from a dilute gaseous mixt. is not
directly proportional to the partial pressure of tbe water vapor
at constant conditions of temp., gas rate, and gas composition.
The rate of absorption of N oxides by aq. NaOH solns. decreases
significantly as the temp. is raised.
- 8 -
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~~
-------
30.
31.
~~ ~~CC~
CONSULTING DIVISION
Apakhov, I. A., Bulycheva, L. I., Shchelkunova, N. V., & Ershova, K. N.
Effect of sulfuric acid mist on the absorption of nitrogen oxides. Khim.
Prom. 42, 684-5 (1966); C. A. 65) 19735 E (1966).
This effect was examined by passing the flue gas) after the absorber
with H2S0 4 -H20~ successively through 2 lab. electrostatic filters at a
rate 011 1. Imin. using 500-1000 1. lexpt. Usually 95-99% of the mist
was captured in the 1st filter. In other expts., the stream was passed
through a centrifugal separator at a rate of 8 1. Imin. and 900-1800 1. lexpt.
In the filter process, the sepn. of the mist permits the formation of N
oxides in the filter, while in the 2nd this is not possible. Two samples
of the condensate from the 1st filter were analyzed; to one, coned.
H2S04 and free N oxides were added and the N2-03 was detd. colori-
metrically. The 2nd sample was dildo with H2D and its H2S04 content
detd. It was assumed that during the dUn., tlie N oxides are completely
expelled. The condensate from the centrifuge was also analyzed. The
amount of N:¥0:L in the mi. st corresponds to its content in the gas, approx.
10 mg. 1m. . The majority of the N203 from the gas passes into the
mist and is not absorbed by the sprayed acid. Probably the N oxides
cause the mist formation.
Ioshpa, I. E., & Belkin, A. A. Kinetics of nitrogen absorption by
sulfuric acid-nitric acid mixtures. Zh. Prikl. Khim. 40 187 -9 (1967);
C.A. 66, 96884 c (1967).
The conditions Dr satn. of nitrose by nitrosylsulfuric acid and HN03 and
for the degree of N02 absorption for a sirg Ie scrubbing of gas contg. N02
by nitrose were studIed. Expts. were made on a lab. column) internal
diam. 4.5/6.5 mm., length 10-16 mm., and total height of packing 2.55 m.
Measurements were made at 30, 40, and 450 and for a gas -liquid vol.
ratio 700-750 1. 11. The absorption -rate coeffs. calcd. from measure-
ments at 300 (mean value approx. 5 g. 1m. 2 hr. torr.) agree with the
mean value of the absorption -rate coeffs. obtained in the study of the
absorption process in a flow system. Temp. rise from 30 to
400 has Ii ttle influence on the value a the absorption -ra te coeff. and on
the degree of satn. of the soIn. with nitrosyl-sulfuric acid and HN03.
The increase of temp. has, however, a significant effect on the COllen.
of N02 in the outlet gas. (Temp. rise from 30 to 400 approx. doubles
the concen. of N02 in the outlet gas.) Concn. of N02 in the inlet gas
affects considerab1y the compn. of nitrose. For a doubled scrubbing
rate at 400, the concn. of N02 in the outlet gas is diminished approx.
to 1 I 3 and the absorption -rate coeff. is increased approx. 1. 6 times.
At the same time the percentage of N203 and of HN03 in the outflowing
nitrose is decreased.
- 10 -
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~~ ~~~~
CONSULTING DIVISION
32.
33.
34.
Ioshpa. I. E.. & Krivonogov. V. P. Determination of scale-up factor
from laboratory to industrial packing in absorption of nitrogen
dioxide by sulfuric acid-nitric acid mixtures. Zh. Prikl. Khim. 40.
189-190 (1967); C.A. 66. 96885 d (1967).
The kinetics of absorption of NH 3 by H20 was studied on the same lab.
equipment and under the same hydrodynamic conditionsas the absorption
of N02 by nitrose (cf. preceding abstr.) The column was packed with
glass rings. 4.5/6.5 mm. diams.. avo length 13 mm.. and sp. packing
surface 829 m. 2/m3. The measured absorption-rate coeff. of NH3 by
H20 was 93. 3 kg. moles /m. 3 hr. atm. The value of the absorpt ion
rate coef£. of NH3' by H20 on industrial Raschig rings 25x25x3 mm. ,
is 81. 8 kg. mOles/m.3 hr. atm. is calcd. from the formula K = 0.076
W O. 57W 0.41 h W d f" 1 1 " f
J . were an Wl are super lQ a mass ve oCltLes 0 gas
an%. liqui . resp. From ~bsorptlOn-rate coeffs. of NH3 by H20 on lab.
and industrial packing it follows that. in the case of absorption of N02
by nitrose. the lab. absorption-rate coef£. must be reduced by a factor
of 1. 14 when applied to industrial Raschig rings 25x25x3 mm packing.
Kuz'minykh. LN., & Surkov, E.L Bubble tower for removing
nitrogen oxides from gases with sulfuric acid. Khim. Nauka: Prom.
~, 523-4 (1957); C. A. 52 4939 d (1958).
Absorption of nitrogen oxides (0. 5-0. 6%) at the end of a production line
with H2S04 in a bubble tower (1300 mm. high) was investigated. Steel
plates (5) 5 mm. thick with 3 mm. perforations 5.5 mm. apart were
placed 200 mm. above each other. With 40-mm. depth the degree of
absorption 0(, on 1 plate was 50% with a liquor rate of 4 cu.m. /m.hr.
and a gas rate 1. 2 m. /sec. with 89-91% H SO at 500. On 5 plates ex.
was 95%. To reduce a tail gas of 0.2-0.3% nitrogen oxides to the
tolerance concn. of 0.05-0.06% 3 plates were sufficeint (c;(,= 80-5%);
the back pressure was 150 mm. H20. In the range of 75-8% H2S04
the effect of the acid concn. on the coef£. of mass transfer K was Hie
highest, i 20%; increasing the concn. from 78 to 89% did not affect~:
the nitroso concn. of the acid did not affect K.
Lentia GmbH. (Schmidt, A., Weinrotter, F., & Mueller, W.,
inventors). Separation of nitrogen oxides from gases. Ger. Pat.
1 204 640 (Cl C 01b) Nov. 11. 1965 (appl. Feb. 12, 1964);
C. A. 64, 4661 f (1966).
The sepn. of N oxides from gases where the mol. NO concn. exceeds
the N02 concn. is described. An absorption system with 2 Raschig-
ring packed columns. each of 100-mm. diam. and a height of 800 mm. ,
was used. In the 1st step, the gas is treated with 96% H2S04 and 45%
HN03 sufficient for the conversion of NO to N203' In a 2nd step, the
- 11 -
-------
34.
Cont'd.
35.
36.
37.
YJ~ ~~ CC~
CONSULTING DIVISION
N203 is converted to rgS05N by coned. H2S04' Thus, e. g. 10 m?/hr. of
a gas contg. 6 g. N 1m., 1. 2 g. as N02' was entered at the bottom of the
1st column, passed through the column, and was then fed to the 2nd
column. The H SO 4 (2 kg. Ihr. ) entered the top of the 2nd column and
was recycled, $.e excess being fed to the top of the 1st column. The
excess acid from the 2nd column was mixed with 200 g. 45% HN03/hr.
and fed to the top of the 1st column. In the 1st column, t~e N concn.
was decreased to 2.4 g. 1m. 3 and in the 2nd to O. 6 g. 1m. The excess
acid from the bottom of the 1st column was recovered as HSO 5N, the
remainder being recycled.
Safiullin, N. Sh., & Tseitlin, A. N. Absorption of nitrogen oxides in
sulfuric acid. Zh. Priki. Khim. 36, 490-5 (Mar. 1963); C. A. 59,
1308 b (1963).
Absorption of N oxides from a gas contg. 0.15-0.20% NO by 76-98%
H2S04 was studied in a packed column at 18-200. The rate of
aDsorption const., K, increased rapidly with the concn. of H2S04 in
the 76-85% range. Above this concn. K approached constancy. As a
function of the gas velocity, w, log K = bwfl, for w = 0.4-0. 8 m. I sec. ,
n = 0.17. As a function of the liquid rate, V, K = bVc. In the V
ranges of 2.9-5.8 and 5.8-11. 6 cu. m. Isq. m., c = 0.45 and 0.085,
resp. Increasing the HN03~oncn. in H2S04 from 0 to 4.4% lowered
K by 8%. As a function of the temp., K = fit- N; up to 400, N = O. 915
and at 40-600, N = 0.545.
Stopperka, K., & Kitz, F. (Tech. Univ., Dresden, East Germany).
System H20-S03-N2.o3' 1. System H2S04-H20-N203' Z. Anorg. Allg.
Chem. ~, 58-10 (1966); C. A. 66, 41121 w (1967).
The system H2S04-H20-N203 was investigated. The amt. of N203
absorbed in 5U-100% H2S04 at 19, 60, and 950 is directly proportional
to the acid concn. and mversely proportional to the temp. The NO+
formation according to the equating 2H~0+ + N203" ... 2NO+ + 3H20
occurs only at H2S04 concns. < 52%. AbsorptiOn in highly conca.
H2S04 results in the formation of cryst. NOHS04' The ir spectra
are gIven for N 20 in H2S04' Data on x-ray interferences of
NOHS04 are ta15ul~ted.
Tseitlin, A. N., & Romanenko, K. E. Nitrogen oxide absorption by
sulfuric acid. Izv. Vysshikh Uchebn. Zavedenii, Khim. i Khim.
Teklnol ~ (1) 85-88 (1966); C. A. 65, 6770 c (1966).
The absorption of N oxides from air contg. about 10% N oxides (50%
oxidized) by 78-95% H2S04 contg. 0.78% N203 was studied in a 2-cm.
diam. wetted-wall column having a surface area of 0.0138 m. 2. With
an absorbent flow of 50 mil min. at 300, the coeff. of absorption K,
g. Im~ hr. mm. Hg, increased from 20 at O. 2m. Isec. gas flow to
70-110 at 1. 0 m.,/sec. and increased only a little more as gas flow
was increased to 2. 0 m. I sec. In tests at 500, liquid flow van ations
from 50-150 mI.'/min. had little effect on K. At 500 with 75 mi. Imin.
- 12 -
-------
37.
Con td.
~Ammad
-------
~~ ~~~~
CONSULTING DIVISION
40.
Cont'd.
41.
42.
43.
concn. The 24-hr. capacity of the app. was 1 ton of NH4 salts, calcd. as
NH4N02' with an inlet concn. of N oxides of 9.0% and nominal absorption
efficeincyof 65%. An increase in N02 concn. from 0.31 to 7.93% in the
inlet gas caused the following: a decrease in absorption capacity of the
reactor from 100 to 78.0%, in N efficiency of the process from 70. 5 to
54.0% and an increase in 24-hr. capacity from 22.8 to 508 kg. NH4N02'
in temp. from 4 to 43. 50, in the vol. abs orption coeff. from O. 33 fo
7. 38 kg. N / cu. m. hr. The absorption efficiency of N oxides in the app.
was very low.
Streight, H. R. L. (du Pont Co. Canada Ltd., Kingston). Reduction of
oxides of nitrogen in vent gases. Can. J. Chem. Eng. ~, 3-11 (1958);
C.A. g 6731 h (1958).
NO and N02 in the effluent gases from HN03 and nylon intermediate
manuf. were reduced by absorption in a waste caustic NH3 liquor.
Finely dispersed NH3 salts were removed by a venturi scrubber.
Pilot-plant and full-scale operating data are given.
Varlamov, M. L., & Kordon, 1. V. Optimization of the process of
trapping low concentrations of nitrogen oxides by the ammollia
method in a foam column. Zavodsk, Lab. ~ (3), 324-6 (1966);
C.A. 64, 18979 d (1966).
For obtaining a math. model of tre process taking place in the absorp-
tion column, the method of multifactor planning of the expt. was used.
The independent variables were: xl consumption of NH3 (in 1.) in the
form of HN40H with respect to the entering N oxides (in 1.), NH3/
(NO + N02); x2 consumption of liquors for irrigation of the app., 1 /hr. ;
x3 concn. of N oxides (NO and N02) in the gas, vol. %; x4 pH of the
irrigating soln, ; x5 volumetric gas rate, m. 3/hr. ; and x6 concn. of
salts in the circulating liquors, wt. %. The output parameter y
characterized the degree of absorption of N oxides in the app., in %.
The degree of oxidn. of NO was taken as const. and equal to O. 6, and
the temp. was held at 20 t 30 during the expts. The following
regression equation was obtained: y = 47.01 + 2. 78xl - 1. 29x2 + 3. 23x3
+ 1. 55x4 + 1. 35x5 - 4. 9x6. The method of steepest ascent with
respect to a nominal gradient was used for detg. the optimum
condi tions of absorption. From the results of the above Ire thod, a
planning matrix was constructed and the regression coeffs. were
calcd.
Varlamov, M. L., Manakin, G. A., & Zbrozhek, L. S. The use of
sieve plate apparatus for the removal of the oxides of nitrogen
from waste gases of the tower sulfuric acid system. Nauchn. Zap.,
Odessk. Politekhn. Inst. ~, 57,..67 (1961); C.A. E.Q., 7171 h (1963).
- 14 -
-------
~knuUd 'lC'~ W~
CONSULTING DIVISION
43.
Cont'd.
44.
Using a sieve-plate absorption column and an NH3 solution as scrubbing
liquor, about 90% of the nitrogen oxides in the waste gas was removed.
The effluent from the scrubber contained 0.03% nitrogen.
Varlamov, M. L., Manakin, G. A., Zbrozhek, L. S., & Starosel'skii,
Ya. 1. Study of ammonia method for the removal of nitrogen oxides
from waste gases from towers of the nitroso-sulfuric acid system.
Zh. Prikl. Shim. 36, 2335-2343 (1963); C. A. 60, 6513 f (1964);
The scrubbing of N oxides from the stacks of the chamber acid process
with aq. NH40H was studied in a pilot plant with packed columns. With
a liquor rate of 11-20 cu. m. leu. m. hr. of 0.74-1. 97% NH40H the
degree of purification, tX., from a gas contg. O. 379% acid gases was
74.3-77.4%. The exit gases contained 0.0764% (NO + N02 + 2S02)'
Increasing NH40H from 1 to 1. 67% did not affect ciJ. In a foam ~app.
with a capacity of 20 cu. m./hr. gas, IN = 90%, reducing the content ci
N oxides to 0.03% which is below the max. amt. according to sanitary
requirements. .
-------------------------------------------------------------------------------
45.
Badische Anilin-& Soda-Fabrik Ag. (Nonnenmacher, H., &.
Kartte, K., inventors.) Selective elimination of nitrogen oxides in
oxygenated gaseous mistures. Belg Pat. 655 115, Apr. 30, 1965
(Ger. appl. Oct. 31, 1963); C.A. 64, 19033 d (1966).
When HN03 is manufd., it is necessary to eliminate the NO and N02
produced by the reaction. An improved method using V, Mo, and W
oxides as catalysts, eliminates the high consumption of combustibles
and the loss of catalyst activity. These oxides are used in combination
with A1203 or H2SiO in a proportion of 2 -50 wt. % oxides. By this
procedure, a very se1.ective elimination of N .oxides is effected, without
extg. 02 at the same time; moreover, the fraction of N02 in the gas
mixt. has no deleterious effect on the catalysts and hence, does not
shorten their lives. The V oxide catalysts are not senstivie to S. The
residual gases, which are formed during the prepn. of HN03 from NH3
or generated during nitration procedures, usually contain 0-15 02' 0-2
NO, and 0-2 vol. % N02' the rest being inert gases such as N 2; the
mixts. may also contain up to 5% H20 vapor. The quantity of NH
desirable for a selective elimination (>.90%) of N oxides is 1-1 1 /~ times
the N oxide content. The gas mixt. contg. NH3 is passed over the
catalyst at a rate of 10,000-30,000 vols. /catalyst vol. /hr. The gas is
in troduced at 200-3500 and the pressure varies between 1-20 atm.
For example, a gas mixt. contg. 96.1 N, 3.50, and 0.43% NO, mixed
with O. 86% NH (3 times the equiv. of NO) is passed at 2000 over a
catalyst of 8. 9~o V 205 with H2SiOa at a rate of 10, 000 vols. / catalyst
vol. /hr. The gas leaving the ca ta:lyst contains O. 09% N oxides (79%
of the oxides eliminated.) When the temp. is raised to 2700, this is
raised to 91. 4%. If H2Si03 only is used, only 16.5% is eliminated.
- 15 -
-------
~~ 1$"~ rc~
CONSULTING DIVISION
46.
47.
48.
49.
Cohn, J. G. E., Steele, D. R., & Anderson, H. C. (to Erigelhard Inds. ,
Inc.) Removing oxides of nitrogen. U. S. Pat. 2 975 025, Mar. 14, 1961.
NO and/or N02 in gases may be eliminated by adding NH3 and passing
the mixt. through a Pt or Pd catalyst bed at 2000-3000 and 1-4 atm.,
at a space velocity of 17,000-86,000 per h. The reaction: 2NH3 + 3NO
= 2. 5N2 + 3H20.
Engelhard, Inds. Inc. (Keith, C. D., & Kenah, P. M., inventors.)
Catalytic purification of gases containing nitrogen oxides and catalyst
therefor. Fr. Pat. 1 365 787 (Cl. C 01b) July 3, 1964, (U. S. Appl.
Aug. 14, 1962); C. A. 62. 10111 e (1965).
N oxides are removed from gases by treating a mixt. of these gases
with NH3 on an appropriate catalyst at 150-4000 and spatial speed
3,000-100,000 vol. of mixed gases per catalyst vol. per hr. The
catalyst is a Pt-group metal deposited on partially fritter A1203'
The Al203 has a specific surface of 10-100 m. 2/ g., is mainly k
phase, wm ch crystd. at 500-9000 C. In an example, 0.3% NH3 by vol.
is added to gases contg. ,..J 0.2% NO + N02' 3-14% 0, 5-6% N20, 2-3%
CO + C02' the remainder, including N, being inert. This mixt. is
passed over the catalyst at 220-3000 and at ",,22,000 vols. /hr. More
than 90% of the NO + N02 is eliminated. The catalyst is prepd. by
fritting or calcining classical activated 3. 2-mm. Al 03 rods with
0.5% pt at 9000 for 3 hrs. This catalyst can be use5 with satisfactory
results for about 61/2 months.
Hibernia-Chemie GmbH, & Pauling, H. Complete removal of nitrogen
oxides. Neth. Pat. Appl. 6 606 577 (Cl. C 01c) Nov. 21, 1966 (Ger.
appl. May 18, 1965); C. A. 66, 67453 f (1967).
N oxides were removed from waste gases by treatment with NH3'
NH4N03 is formed and can be recovered. The degree of oxidn. of
the N oxides was 1st increased by mixing with NO or N02' or gases
contg. them, or by further oxidn. of the oxides to a N02: NO ratio
of 1: 1. This gas mixt. was then treated with aJ1. ammoniacal
NHAN03 soln. The ratio of H20: NH3 in the vapor phase was limited
to Z:1 for the upper range, ana 100:1 for the lower range.
Varlamov, M. L., & Kordon, 1. V. Study of the ammonia method for
purifying exhaust gases of nitrogen oxides by using multifacotrial
experiment planning. Dokl. Vses. Soveshch. Plan. Eksp., 1st,
Moskow, 1964, 251-260; C.A. 66, 96889 h (1967h cf. ref. 42 above.
Multifactorial planning was used to obtain a math. model of this process.
The main factors in the 1st foam absorption app. are the flow rates of
NH3 and of the alk. spray liquid, the concn. of NO + N02 in the gas, the
gas rate, and the salt concn. in the recirculated spray lLquid. A series
of random factorial expts. was carried out to derive the yield equation
as a function of these factors.
-------------------------------------------------------------------------------
- 16 -
-------
50.
51.
52.
53.
54.
YJ~ ~~~~
CONSULTING DIVISION
Ammoniaque Synthetique et Derives, S. A. Absorption of nitrogen
oxides from the tail gases in the manufacture of nitric acid. Belg. Pat.
412 314, Dec. 31, 1935; C. A. ~, 5735 (5) (1936).
The N oxides are absorbed by an alk. som. or by an alk. earth
suspension which is atomized by the impact of the gases contg. the
oxides to be recovered.
Ganz, S. N. Increased removal of nitrogen oxides from exit gases by
alkaline absorption. Izv. Vysshikh Uchebn. Zvedenii Khim. i Khim.
Teknol. ,i, 998-1002 (1961); C. A. 56, 15322 b (1962).
Exptl. work indicated that a better absorption of N oxides from exhaust
gases by alkaline soms. may be achieved by feeding a small amount of
conc. N02 gas into the exhaust gas before the latter is passed through
the absorption column, which then absorbs 80-85% of the total N oxides
in the exhaus t gas.
Grosspietsch, H., & Kalfenhauser, H., & Heuse, 0. (to Farbwerke Hoechst
AG). Removing nitric oxide from gases containing unsaturated hydrocar.bons.
U. S. Pat. 3 192 009 (Cl. 23-3) June 29, 1965 (appl. Jan. 31, 1962).
Gases contg. 0.001-0.2% NO and more than 10% unsaturated "hydrocarbons
are mixed with enough air to give an 02 content of at least O. 5%. If that
much 02 is already present in the gases, no air needs to be added. The
gases are then compressed to 2-50 atm. Under these conditions all of
the NO is converted to N02 and N204. The compressed gases are then
scrubbed with an aqueous alkaline or neutral solution at 00_300 and under
2-50 atm. pressure to remove N02 and N204.
Kuz'minykh, LN., Aigina, E.P., & Babushkina, M.C. Absorption of
nitrogen oxides by soda and lime solutions. Khim. Prom. 1953, No.8,
p. 26-27; C. A. g, 5094 g (1958).
The absorption of NO and N02 (by soda soms. arid lime water) when
bubbled through a single orifice was studied. The greatest degree of
absorption occurs at a ratio N02:NO = 1:1, at a high concn. of N
oxides in the gas and low temp. ThE' lime water is a better absorbent
than is the soda som. Increase in the soda som. concn. improves the
absorption of the N oxides; its neutralization decreases absorption. The
lime som. concn. has relatively little effect on the absorption. With the
increase of the sam. with Ca(N02)2 the degree of absorption is lowered.
Increase in the bubbling depth over 30 mm. causes very slight increase
of the absorption.
Mirev, D., Balarev, K., Boyadzhiev, L., & Lambiev, D. Absorption
of nitrogen oxides by vibrating layers of NaOH solutions. Compt. Rend.
Acad. Bulgare ScL 14, 259-262 (1961) (in German); C. A. 56, 66 a (1962).
- 1 7 -
-------
54.
Cont'd.
55.
56.
~~ ~~~~
CONSULTING DIVISION
The effect of the following variables on the completeness of the
absorption was studied: NO:N02ratio, 02 concn., (NO + N02) concn. ,
and flow rate. The completeness of the reaction reaches a max. at a
1: 1 mole ratio. At this ratio the 02 and ~ 0+ N02) concns. have no
effect. At a higher ratio, an increase of the 02 concn. favors the
absorption.
Radhakrishna, G. N. The removal of nitrogen oxides from air-polluting
exhausts. Ductorate dissertation 1965, Purdue Univ., Lafayette, Inc.,
207 pp. ; Dissertation Abs. ~ (2), 943-4 (1965); C. A. ~, 17025 e (1965).
The hydroxides selected for investigations ind uded potassium, sodium
and calcium hydroxides. The experiments performed on these hydroxides
in dilute solutions (2 to 5% by weight) were devoted not only to an under-
standing of the mechanisms involved in the process of absorption of
nitrogen peroxide diluted with nitrogen, but also to making a comparative
study of the use of the hydroxides as absorbing agents for the gas and
neutralizing agents for the acids formed in the process of absorption.
The results indicated that when the alkali was in excess in solution,
almost equimolar quantities of nitrite and nitrate were formed. But,
after all the alkalinity was utilized for neutralizing the acids formed,
the nitrites decreased and the nitrates increased in concentration
considerably. For a comparative study of the use of hydroxides in
dilute solutions for absorbing N02' it was concluded that on the basis
of weight, sodium hydroxide was more efficient than calcium or
potassium hydroxides. However, the ability to neutralize the acids
formed, decreased in the order: caclium, sodium and potassium
hydroxides. The solids selected for investigation included Ascarite,
(8-20 mesh), silica gel (20-60 mesh), calcium oxide and barium oxide
(20-60 mesh). The results indicated that Ascarite has a better capacity
than silica gel for the removal of nitrogen peroxide at flow rates of
about 36 liters per hour and in the range of concentrations of O. 79 to
1. 5 mole per cent N02' but at lower concentrations silica gel appeared
to be a better removal agent. The weights of N02 removed by Ascarite
increased with concentrations of the gas and decreased with increasing
rates of flow within the range c:f. concentrations used (0. 70 to 1. 36 mole
per cent), and the range of flow rates adopted 30.0 to 45.0 liters per
hour). For the silica gel, the weight of NO removed by adsorption
increased with the partial pressures, as we11 as with the concentrations
of N02 in N2' within the range of partial pressures (0.051 to 0.496 mm.
Hg. ) and concentrations (0.510 to 1. 503 mole per cent). The results
of absorption of N02 by calcium and barium oxides were poor,
possibly due to dry gases being used. The pre sence of moisture in
the gases was expected to improve the removal.
Shelud'ko, M. K. Removal of nitrogen oxides from industrial waste
gases. Khim, Teknol., Resp. Mezhvedomstyv. Nauchn. -Tekhn. Sb.
1965, (3) 76-85; C. A. 65, 20739 e (1966).
- 18 -
-------
~knuad
-------
58.
Cont'd.
59.
60.
61.
62.
~~ ~~~~
CONSULTING DIVISION
50-53% HN03' Oxidn. of NO in the spray column was 15-18% higher than
in a packed tower. With CX-o= 38-40%, ex. and K increased as the concn.
of NO + N02 in the gas, C 1\101 increased from & 6 to 1. 2%. The increase
in oc.with CND was pronounced only at CNo< O. 6%.CXand K decreased as
the temp. increased from 10 to 400. At 100, ~ = 90%. g
Koninklijke Nederlandsche Hoogovens en Staalfabrieken NV. (van
Ommeren, B. G. H. J., inventor). Low nitric oxide-content fuel gas.
Brit. Pat. 937 364 (Cl. C 106) Sept. 18, 1963 (appl. May 19, 1960);
C. A. 60, 336 b (1964).
The fuel gas contg. small amounts of NO is treated with ozone under a
pressure of 6 atm. to oxidized NO to N02' After that, the gas is
scrubbed with aq. soln. of Na2C03 or NarfC03 to remove N02'
Kuz'minykh, I. N., Rodionov, A. I., & Mishchenko, Yu. S.
Absorption of nitric oxide from nitrogenous exhaust gases in large-
scale plate columns. Tr. Mosk. Khim. -Tekhnol. Inst. 1961, No. 33,
p. 43-47; C.A. 57, 2022 h (1962).
A 12 tray, 150 mm. diam. column was used to det. optimum operating
conditions and the effect of the NO-N02 ratio in the inlet gas on atm.
pressure scrubbing of 0.3% gas at room temp. with 10% Na2C03 soln.
With perforated trays with downcomers, between 43 and 75u/o of the N
oxides were removed, with overall gas velocities of 1. 3 m. /sec., and
4.3 cu. m. /sq. m. hr. liquid loading. The max. absorption (75%) was
obtained for equal mole rates of NO and N02' and the column perfor-
mance depended more on the degree of oxidii. of NO than on gas or
liquid loadings, with NO to N02 ratios of 0.41-0.60.
Mirev, D., Balerev, K., Boyadzhiev, L., & Lambiev, D. Absorption
in a vibrating layer. II. Absorption of nitrogen oxides in solutions of
NaOH and Na2C03' Izv. Inst. Obshcha Neorg. Khim., Org. Khim.
Bulgar Akad. NaUK j!, 83-101 (1961); C. A. ~, 5752 h (1962).
Gases contg. small amounts of N oxides are passed through a layer
of vibrating soln. of 2N KOH and/or K2C03' The N oxides are
absorbed completely if the oxidation oINO to N02 is greater than 50%.
There should be enough free 02 in the gas to insure this oxidation.
Within the range of N oxides O. 55-1. 8% as NO, and a space velocity
up to 800 per h. The residual N oxides concn. in the exit gas is
independent of initial N oxide concn.
Mirev, D., Balerev, K., Boyadzhiev, L., & Lambiev, D.
Absorption of nitrogen oxides in a vibrating layer of sodium carbonate
solutions. III. Compt. Rend. Acad. Bulgare Sci. .!.i, 345-8 (1961);
C. A. ~, 5795 3 (1962).
- 20 -
-------
62.
Cont'd.
63.
64.
~km«:d <;#'~ ~~
CONSULTING DIVISION
The absorption of N oxides by Na2C03 soIns. in a vibrating layer was
studied under various conditions. The expts. were made with mixts.
of gases contg. 0.55-1. 8% N oxides (NO and N02)' The degree of oxidn.
of NO to N02 (oc) varied from 20 to 60%. The effect of ct., ° content,
velocity of gas flow, absorbent concn., and temp. on the efficiency of
absorption ('1) was detd. from the presence of N oxides in gases after
absorption. The amt. of N oxides in exit gases was considerably
smaller during absorption in the vibrating layer than that obta ined by
~he bubbling. rrethod. T~e efficiency of absorption by Na2C03 soIn.
mcreases wIth decreasmg temp. from'- = 72% at 730 to 11 = 98.5%
at 00. The rate of gas flow and concn. of NO in gases affect the
absorption: at a rate of 800 cu. m. / cu. m. hr. the 't was 87 at NO
0.55, 91. 5 at NO 0.7, and 94 at NO 1. 0%; at 200 cu. m. leu. m. hr.,
">! was 96.97, and 98%, resp. The concn. of Na2C03 in soIn. was
2N in all expts.
Pawlikowski, S., Aniol, S., & Bistron, S. Experiments of NH3
absorption of N oxides in the nozzle systems on semitechnical scale.
II. Absorption by a mixture of ammonium carbonate and bicarbonate
solutions. Przemysl Chern. (Warsaw) 43, 80-83 (1964); C.A. 60,
14150 b (1964).
Production of NH4N02 by absorption of NO+ N02 in the mixt. of (NH4)2-
C03 and NH4HC03 was studied in a semitech. installation of 1/10th of
the size of tIle proposed industrial system. In the course of investigation
the effect of the following parameters were examd: (1) the concn. of
N oxides, (2) the excess of absorbing medium in the mixt., (3) the
pressure in the absorber, (4) gas flow rate; the safety aspects were
also investigated. Optimum absorption was adl ieved with an absorbing
soIn. in which the mole ratio of NH3 to C02 is as low as possible,
because at these conditions the heat effect IS small and the temp.
increases is not high enough to cause NH4N02. decompn., hence high N
efficiency (90-9%) and the total efficiency (70u/o)., The increase of
pressure in the reactor by O. 8 atm., higher concn. of oxides, and
higher gas flow rate have a little effect on the absorption efficiency.
The aspect of safety was examd. by maintaining a steady excess of N
oxides in relation to alk. component of absorbing medium. The temp.
in the absorber never exceeded 500 and the rate of NH 4NO decompn.
never attained violent proportion. The final product was :15% NH4N02
soIn. which solidifies at -160 and can thus be transported by pipes
even at avo winter conditions.
Pietrek, lV1. Aerosol to remove nitrous gases in the atmosphere.
Czech. Pat. 105 998, Dec. 15, 1962 (appl. June 8, 1961); C. A. 60,
2250 b (1964).
An aerosol prepared from 6% Na2C03 and 6% KMn04 in H20 removes
noxious gases from air which may be caused by dynamite clasts.
- 21 -
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~~ ~~~~
CONSULTING DIVISION
65.
66.
67.
Potasse et Engrais Chimiques (Quanquin B., & Trimbach, H., inventors).
Purification of waste gases from complex fertilizer manufacture. Fr. Pat.
1 408 302 (Cl. C 05b) Aug. 13, 1965 (appl. July I, 1964); C. A. 65, 5076 f
(1966).
The waste gases from the fertilizer plant are first scrubbed with 15-30%
H2SiF 6 soIn. at 400-750 which removes 90-95% of the F compds. The
gases are next scrubbed with aq. Na2C03 or K2C03 at a concn. of 3-5
g. /1., or with aq. HaHC03' KHC03 of Ca(OH)2' Iii either case the
NO- and/or N03 in the scrubbing soIn. is marntained at a total of
50-~0 g. /1. The scrubbed gases contain F 3-10 mg. /cu. m., and
N oxides 0.02-0.05 vol. %.
Potasse et Engrais Chimique (Quanquin, B., inventor). Nitrogen oxides
recovery from gaseous effluents. Fr. Pat. 1 387 207 (C1. C 01b) Jan.
29, 1965 (appl. Dec. 16, 1963); C.A. g, 14210 a (1965).
The waste gas from the HN03 plant is scrubbed in 2 stages by aq.
KHCO soIns. In the 1st stage the KHCO is 10 g. /1. and in the 2nd
stage fue KHC03 is 80 g. /1. The 2 scru~bing columns are maintained
at 400-450. When the KN03 and KN02 have been built up toa sufficient
concn. the scrubbing soIns. are witharawn and treated with HN03 to
oxidize all KN02 t~ KN03' liberating NO gas which is collected and
sent back to theffN03 plant. The KN03 soIn. is then cooled to 300 to
crystallize KN03 -which is recovered as a by-product.
Pozin, M. E., Kopylev, B.A., & Bel'chenko, G. V. The absorption of
nitrogen oxides in soda solutions in the Penn apparatus fo r the production
of sodium nitrate. . Trudy Leningrad. Tekno1. Inst. im. Lensoveta 36,
120-132 (1956); C.A. 52, 14106 e (1958).
In the Penn app. a mixt. of NO + N02 can be absorbed by a Na2C03
soIn. so as to form NaN03 + NaN02 with very small losses of the
oxides, but the efficiency coefficient (equiv. N oxides absorbed/equiv.
Na2C03 used) will drop from 30 to 16% if the linear rate of gas flow is
increased from O. 5 to 3 m. / sec. over the total cross section of the
app. The absorption coeff. increases with the linear rate of gas flow;
it reaches a value of 1860 kg. /sq. m. -hr. -kg. /cu. m., a value which
is 6-7 times as great as the value obtained in bubble-cap columns and
20-5 times the value obtained with industrial scrubbers. The coeff. of
efficiency increases slightly with lq uid flow rate. If the concn. of
Na2C03 is raised from 5 to 20%, at a linear gas flow of 1 m. /sec.,
the efficiency coeff. drops from 26 to 16% and the absorption coeff. drops
correspondingly. If the starting concn. of the N oxides in the gas is
raised from 0.05 to 1. 4%, then, at a linear gas flow of 1 m. / sec., the
efficiency coeff. is increased from 8 to 25%.
- 22 -
-------
68.
69.
70.
Yf~ ~~ CC~
CONSULTING DIVISION
Pozin, M. E., Kopylev, B. A., Bel'chenko, G. V., & Tereshchenko, L. Ya.
Absorption of nitrogen oxides by soda solutions under foaming conditions.
Izvest. Vysshikh Ucheb. Zavedenii, Khim. i Khim. Tekhno1. ~, 803-9
(1959); C.A. 54, 7990 i (1960).
The absorption of N oxides by soda solns. under foaming conditions takes
place a few times more intensively than in towers with pack ings. With
an increase in the linear speed of the gas, W, in the whole section of the
app. from 0.5 to 2.5 ,m. /sec., the absorption of an equimo1. mixt. of N
oxides (with an initial concn. of about 1%) by a soda soln. on one shelf
of the foam app., decreases from 36 to 18%. The absorption coef£.
under these conditions increases from 800 to 1800 kg. / sq. m. -hr. -kg.!
cu. m. With a decrease in the concn. of N oxides in the gas below 0.5-
o. 6%, the absorption rate is sma Her, the lower the content of N oxides
in the gas. The degree of absorption of an equimo1. mixt. of N oxides
on one shelf of the app., for a content of about 0.2%, for W from O. 5 to
1. 5 m. / sec., is 10-18%. An increase in the content of nitrite-nitrate salts
up to 150 g. /1. in the soln. for W = 0.75 m. /sec., flow rate of the liquid
= 3 cu. m. /m. -hr., and a Na2C03 content of about 5%, has practically no
influence on the absorption; for a further increase in CDncn., i. e., up to
500 g. /1., the degree of absorption decreases from 24 to 16% for an
initial nitrous content of the gas of about O. 5% NO + N02 and' 0= 50%.
The absorption of N oxides by Na2C03 soln. is most eflective when a
preliminary 50% oxidn. of N oxide is carried out, when about 5% Na2C03
is used, and when heat is removed by circulating lye. The degree 01
absorption on one shelf of the app. of N oxide, without a preliminary
oxidn., for an initial concn. of 1%, is 5-10% and depends relatively
slightly on its concn. in the gas. This indicates a partial oxidn. of
NO under foaming conditions in the liquid state.
Rabson, S. R. Development of an extraction plant for the elimination
of blasting fumes. Trans. Commonwealth Min. Met. Cong.l., 757-774
(1961); C. A. ~, 619 i (1962).
N oxides, such as NO, N02' N204 and N203 are removed from air by
passing the air through a contact mass made of 1/8-3/8 inch
vermiculite, 2 ft. deep, impregnated with a 5% soln. of Na2C03
KnMn04 .
Skrivanek, J. Absorption of ni trogen oxide gases by soda solution.
Chem. prHmysl2, 404-9 (1956); C. A. ~, 9104 d (1957).
Absorption kinetics of residual gases by soda soln. was studied for
the purpose of producing nitrite from the mother liquor after
absorption. The expt1. results indicate that for the production of
nitrate a continuous system of packed columns seems suitable. The
recycled soln.in the last column should contain 3% soda, which
corresponds to the highest value of the absorption coef£. For nitrite
- 23 -
-------
~~ 18 Wg. For desorption KL = L O. 2, for a liquor velocity
in the thorat wL = 64.9 m. Isec. , where L is the liquor rate, cu. m./sq.
m. hr. The gas-phase mass trmsfer coeff., K a, detd. by desorption
of S02from an aq. soIn. is correlated ~ K a ~2820w or Nu = O. 36 X
1O-4Re~. 81prgO. 666 and Kg = 4. 8wgO. . For absorpflon wi& chemical
reaction, Kga was detd. for absorption of N oxides from air by Na2CO
soIns. 3
- 24 -
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~~ ~~ 1f~
CONSULTING DIVISION
73.
Varlamov, M. L., Manakin, G. A., & Starosel'skii, Ya. 1.
Absorption of nitrogen oxides by soda solutions in efficient
atsorption apparatus of the gas lift type. Nauch. Zapiski Odessk.
Politekh. lnst. 1957, .!2, 37-52 (publ. 1958); C. A. 55, 10997 c
(1961).
New gas-lift type app. were developed which permit, within wide limits,
a change in the relation of consumption of gas and liquid, and operation
with greater linear gas velocity at comparatively low hydraulic
resistances in compari son with conventional equipment. The hydro-
dynamics and the absorption of N oxides in low ooncn. by solns. of
Na2C03 in 6 gas-lift app. were studied in relation to concn. of N
oxiaes, consumption of gas and liquid, diam. and height of lift pipes,
their cross section, and the no. of operating cycles. For optimum
gas consumption with minimum hydraulic resistance, the absorption
coef£. was 100 times greater than the same coef£. for packed towers.
From test lab. models it was possible to design plane parallel app. of
great capacity if the same equiv. diam. was used. Exptl. data were
obtained of practical interest in removing N oxides from tail gases,
esp. at pressures which can be used for operation of gas lift app.
74.
Varlamov, M. L., & Starosel'skii, Ya. 1. Absorption of nitrogen oxides
by sodium carbonate solutions in a gas-lift apparatus. Zhur. Priklad.
Khim. ~, 1716-1723 (Aug. 1959); C. A. ~, 20940 d (1959);
Absorption on No and N02 from dil. gases by Na2C03 solns. in a gas-
lift type of absorber was studied. The results were expressed by the
following empirical relations. At a const. gas rate, V , the vol.
coeff. of absorption Ka = C~'J1 With V from 5 to 30 f./min. and
the concn. of NO + N02' CNO = 0.35 - f. 2% and the concn. of Na2C03.
in the soln., Cs = 50.5 g./l., Ka = VO. 57C~'J1. With Cs = 87.5" g.!!.
the rate of absorption U = VO. 5C 1. 36 ~g. I cu. m. -hr. The degree of
absorption D decreased as ~ an~ge gas :liquor ratio increased. Ka
decreased lineraly as the temp. increased from 20 to 500. In the liquor
rate, L, range from 0.15 to 1. 51. Imin., Ka = 180Ll. 25h-1. 94, where
h is the depth of submersion.
-------------------------------------------------------------------------------
75.
The Gas Light & Coke Co., et al. Removing or converting constituents
of gas mixture. Brit. Pat. 496 721, Dec. 1, 1938; C. A. ~, 4004 (2)
(1939).
The gas to be treated is passed in contact with the anode of an electro-
lytic 02 cell to oxidize all of the N oxides S02 and H2S in the gas. The
electr01yte may be a soln. of NaOH.
- 25 -
-------
76.
77.
78.
79.
~~ ~~ 1f~
CONSULTING DIVISION
Gattys, F. J. Absorption column for nitrous gases. Ger. Pat. 1 229 502
(cl. c 01b) Dec. 1, 1966 (appl. June 30, 1961); C. A. ~ 47691 d (1967).
Nitrogen oxides in waste gases are recovered by oxidation followed by
absorption in dilute HN03 in a column designed to have an oxidation
chamber on each plate. .
Gesellschaft fur Lindes Eismaschinen AG. (Karwat, E., inventor).
Removal of nitric oxide from gas mixtures. Ger. Pat. 1 085 640
(Cl. 26 d) appl. Sept. 3, 1957; C. A. 56, 5638 c (1962).
HCIO? or CI02 is added to the water or gas mixt. to be purified at pH
of 7-f2. After the reaction between CI02 and NO, the gas mixt. is
washed with NaOH, or Na2S203' or Na2s03 solns. Thus, 50 cu. m.
N contg. 0.01% CI was passed through a saturator filled with 50 1. of a
10% aq. NaCI02 soln. at 12 atm. Then this N leaving the saturator was
charged with 1U 1. CI02 and added to a stream of 10, 000 cu. m. coke-
oven gas with 2% C02 and 1 p. p. m. NO. After 2- 6 sec., C02 was
removed, and the gas was washed with Na2S203; about 40 g. NaCI02
was consumed.
Karwat, E. (to Gesellschaft fur Linde's Eismaschinen AG., Germany).
Removal of nitric oxide from gas mixtures containing the same. U. S.
Pat. 3 023 076 (Cl. 23-2) Feb. 27, 1962 (appl, in Germany Sept. 3,
1957).
Small amounts of NO in gases are eliminated by oxidizing it with CI02
freshly prepared from reacting NaCI02 with C~ (2NaC102 + Cl2 ~
2CI02 + 2NaCI). The NO is thus oxidized to NG2' and the N02 1S
removed by scrubbing the gas with an alkali som.
Karwat, E. (to Gesellschaft fur Linde's Eismaschinen AG, Germany).
Removal of nitric oxide from gas mixtures containing same. U. S. Pat.
3 149 907 (Cl. 23-2) Sept. 22, 1964 (Ger. appl. Sept. 3, 1957); Ger.
Pat. 1 085 640 (1960); Chem. -lng. -Tech. 35, 863 (1963). C. A. 56,
5638 e (1962).
HCIO or CIO is added to the water or gas mixt. to be purified at
pH of~-12. After the reaction between CI02 and NO, the gas mixt. is
washed with NaOH, or Na2S20 , or Na2S0 solns. Thus, 50 cu. m.
N contg. O. 01 % CI was passed 1hrough a sa1urator filled with 50 1. of
a 10% aq. NaCI02 soln. at 12 atm. Then this N leaving the satura tor
was charged with 10 1. CI02 and added to a stream of 10,000 cu. m.
coke-oven gas with 2% C02 and 1 p. p. m. NO. After 2-6 sec., C02
was removed, and the gas was washed with Na2S20 . The gas thus
treated contained 0.025 p. p. m. NO + N02' A150ut 40 g. NaCI02
was consumed.
- 26 -
-------
~knuad ~~ ~~
CONSULTING DIVISION
80,
81.
82.
Koninklijke Nederlandsche Hoogovens en Staalfabrieken NV.
(Guillaume, B., & van Ommeren, H. J., inventors). Low nitric oxide-
content fuel gas. Brit. Pat. 937 364 (Cl. c lOb) Sept. 18, 1963 (appl.
May 19, 1960); addition: Brit. Pat. 1 080 240, Aug. 23, 1967; C. A. 60,
336 b (1964);~, 4769 j (1968).
After scrubbing with an aq. Na2C03 soln., hot flue gas obtained by
combustion of hydrocarbons ana contg. 5-10 ppm. of S02 and 40-50
ppm. NO was treated with a 20% excess of the stoichiometric amt. of
03 required for reaction with NO and S02' After 5 min., the NO
content was 2 -3 ppm. The gas contg. the N02 formed was scrubbed
with an aq. Na2C03 soln. In the manuf. of coal gas, the soln. is
added to the coal gas stream prior to the scrubbing steps.
Morrison, M. E., Rinker, R. G., & Corcoran, W. H. (Calif. Inst. of
Technol., Pasadena). Rate and mechanism of gas-phase oxidation of
parts-per-million concentrations of nitric oxide. Ind. Eng. -Chern.
Fundamentals~, 175-181(1966); C.A. 65, 80 a (1966).
Rates of the air oxidn. of ppm. concns. of HN03 were studied homo-
geneously at atm. pre ssure and ambient temps. in a const. -vol. batch
reactor. The initial concn. of nitric oxide was varied from '2 to 75
ppm., while the ° concn. ranged from 3 to 25 vol. %. The initial
order of the oxidn. reaction in the absence of N dioxide is 2.00 ':t 0.09
for nitric oxide and 0.97 t O. 11 for 0. From initial rate data at 26.50,
a 3rd-order rate const. of (1. 297 t 0.051) X 104 (1. )2/ (g. -mole)2-sec.
was obtained. The addn. of N dioxide increased the initial oxidn. rate,
and that compd. showed an autocatalytic effect throughout the course of
the reaction. A nonlinear least-sqs. analysis was used to develop a
mechanism involving 6 reactions, with N03' N203' and N205 as
intermediates. Use of that mechanism gave a min. standard deviation
of 1. 6 ppm. for the predicted concns. of nitric oxide relative to the
exptl. data.
Peters, M. S., Ross, C. P., & Anderson, L. B. (Univ. of Illinois,
Urbana). Removal of nitrogen oxides from gaseous mixtures. U. S.
Atomic Energy Comm. report COO-lOll, Sept. 30, 1953, 99 pp.
p. 23-24. Nitrogen oxides, such as NO, N02' N204' and N203'
may be removed quantitatively from gas mixfures by oxidizing agents
in aqueous media, of the chemical reactions involved are the following:
(1) 2NO + 3 H202 = 2HN03 + 2H20
(2) 2N02 (or N204) + H202 = 2HN03
(3) 10NO + 6KMn04 + 9H2S04 = 10HN03 + 3K2S04 + 6MnS04 + 8H20
(4) 10N02 + 2KMn04 + 3H2S04 + 2H20 = 10HN03 + K2S04 + 2MnS04
------------------------------------------------------------------------------
- 27 -
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~~ ~~~~
CONSULTING DIVISION
83.
84. .
85.
Ganz, S.N., Luk1yanitsa, A.I., & Bel'china, L.A. (Khim, -Tekhnol. Inst.
Dnepropetrovsk). Production of nitrogen-iron fertilizers from waste
pickling solutions II. Zh. Prikl. Khim. 12, 1609-1611 (1964); C. A. g,
9193 a (1964).
Spent pickling liquor contg. 25% FeS04 and 4-5% free H2S04 was used
to scrub a gas contg. small amounts of NO and NO . Tfie apparatus was a
packed column which was maintained at 200-220. ~he scrubbing solution
was then withdrawn and heated to 90-1000 to liberate the NO which is sent
back to the HN03 plant. The soIn. is finally treated with NH3 to produce
a N - Fe-contg. fertilizer.
Ganz, S. N., & Mamon, L.1. Kinetics of absorption of nitric oxide by
solutions of ferrous sulfate in a mechanical absorber with a high number
of revolutions. Zh. Prikl. Khim. 30, 553-561 (1957); C. A.~, 13534 h
(1957);~, 4873 e (1959).
The rate of absorption q of NO by aq. soIns. of FeSO 4 in a revolving app.
was studied. The over-all coeff. of absorption Kv was a function of the
r. p. m., n, or the peripheral velocity vd of the disks up to a crit.
value of n = 3000 r. p. m. or vd = 6.5 m. Isec. at which point Kv passed
through a max. and then decreased (max. Kv == 1050 kg. I cu. m. hr. atm.)
The decrease was attributed to the centrifugal force or to the destruction
of the structure of the foam at high velocities. Up to the crit. value of
vd, log Kv vs. vd was a linear function expressed by Kv = 276vdO. 82,
and Kv was independent of the partial pressure P of NO and the concn.
of FeSO 4. q was proportional to P, so that q = KvAPav. Log Kw was
a linear function of the vol. velocity of the gas up to w ,-1000 cu. m. I cu.
m. hr. In the range of linerairty Kw = AwO. 86; the values of A for vd
2.05, 6.28, and 10.25 m. Isec. were 2.57, 5.3, and 3.89, resp.
Pozin, M. E., Tarate, E. Ya., Zubov, V. V., & Tereshchenko, L. Ya.
(Technol. Inst., Leningrad). Velocity and mechanism of adsorption of
nitric oxide by aqueous salt solutions. Izv. Vysshikh Uchebn.
Zavedenii, Khim. i Khim. Tekhnol. E. 974-981 (1963); C. A. 60, 1529 e
(1964).
The process of absorption of NO by Na2S03' (NH4)2S03' FeSO 4' and
FeCL2 soIns. was studied under conditiOns not complicated by turbulent
mass transfer, using an essentially static gas phase in contact with a
mildly agitated liquid phase. Two regions of absorption of NO by
sulfite soIns. were observed. With low NO concn. «0.1 bar), the
absorption rate is wholly controlled by the gas phase and is described
by V = KlP, kg. 1m. 2 hr., where P = partial pressure of NO and K1
is the mass ""transfer coeff. With NO concn. > O. 1 bar, driving force is
detd. by both gas and liquid phases and absorption velocity is described
by V = Kl (P - Pi), where Pi == equil. pressure of NO at the boundary
- 28 -
-------
85.
Cont'd.
86.
87.
88.
~~ 1f'~ ~~
CONSULTING DIVISION
layer of the liquid. Analogously there are 3 regions of absorption of NO
by soIns. of bivalent Fe salts. but drivirg force is also modified by the
equil.: k = (FeNO++] I (Fe++] [NO), If the degree of satn. of the initial
soIn., x = [FeNO++] I CFe++J. then a cor. partial pressure is defined
by: p* = x/k. H(l - x), where H = Henry's Law const., V = k(P - p>,1: - Pi).
Pozin, M. E., Zubov, V. V., Tereshchenko, L. Ya., Tarat, E. Ya., &
Ponomarev, Yu. L. Solubility of nitric oxide in aqueous solutions of
some salts. Khim. i Khim. Tekhnol. b, 608-616 (1963); C. A. 60, 4870 d
(1964); English transl. Chemico TR -377.
Thesoly. of NO in aq. soIns. ofCuS04' CuC12, MnS04' H3P04' CoS04'
NiS04' CU2(NH3)nCI , Na2S0 , FeS04' and FeC12 was deta. Solns. of
NaSO , FeSO , FeC~2' and ~2(NH3) Cl2 proved to be the most efficient
absor~ing me~ia. Equil. conditlOns w~re investigated for NO-FeS04 and
NO- FeC12 at 10-900 and equil. consts. for salt concns. (:;, .7M) were
detd. by the equation 10 g K :;: 2550/T - 8.8. The equil. pressures of
NO above soIns. of FeC12 and FeS04 are given.
Pozin, M. E., Tarat, E. Ya., Tereshchenko, L. Ya., Zubov, V. V., &
Treushchenko, N. N. Kinetics of absorption of nitric oxide by aqueous
salt solutions. Izv. Vysshikh Uchebn. Zavedenii, Khim. i Khim.
Tekhnol. ~ (4), 628-632 (1965); C. A. 64, 6126 a (1966).
N2S03 and FeS04 soIns. are practical absorbents for NO in N or Ar
streams. Studies were conducted at 200 in a 5-cm. diam. x 75-cm.
high tower packed with 6 x 10 x 1. 3-mm. ceramic rings, and in a 4-
cm. diam. foam chamber with 3-mm. orifices providing 23% free area.
Dat a was correlated by the following equations: for the J(acked scrubber
with Na2S0 soIn.: Ksd/D~ = 1. 34 x 10-6 (4w IfgUg)O. 6(4wl Ifgul)O. 6
(ug/PgDg)0.3:33(u/p1D1)0. 19-n/d)-O. 33; for the roam chamber with Na2S03
soIn.: Kvwg/g = 2.1 x 10-5(Wg3/vgg)0. 5(i/vl)0. 33(H/h)0. 3(vg/Dg)0. 33;
for the foam chamber with FeSD4 soIn.: Kvwg/g = 2.54 x 10-5(wg3/vgg)0. 55
(i/v1 )0. 35(v g/Dg)O. 33, in which Ks = ab sorptlOn coef£., m. I sec., d and 1
= equiv. diam. and height of packing; w and wI = mass flow rates of gas
and liquid, kg. 1m. 2-sec. ; Ug and ul = J5ynamic viscosity of gas and liquid,
kg. I sec. -m. 2; Pg and PI = d. of gas and liquid, kg. -sec. -g. -m. 4; Dg and
DI = diffusion coeffs. of NO in gas and liquid, m.2. Isec. ; f = sp. surface
of the packing, m. 21m. 3; Kv = vol. coef£. of absorption, (kg. 1m. 3)/(sec.)
(kg. 1m. 3); Wg = surface gas velocity, m. Isec. ; i = intensity of liquid
flow, m. 3/sec. -sec. ; Vg and vI = kinematic viscosity of gas and liquid,
m. 2 I sec. ; H = foam heIght, m,; h = orifice height, m.
Pozin, M. E., Tarat, E. Ya., Tereshchenko, L. Ya., Zuboc, V. V., &
Morariu, 1. (Lensovet Inst. Technol., Leningrad). Method of expressing
the driving force of absorption processes. Protsessy Khim. Tekhnol.,
Gidrodinam., Teplo- i Massoperedacha, Akad. Nauk SSSR, Otd. Obshch.
i Tekhn. Khim., Sb. S. 1965, 218-223; C. A. 65, 17734 c (1966).
- 29 -
-------
88.
Cont'd.
89.
~~ ~~ CC~
CONSULTING DIVISION
The local driving force, D, of absorption is represented by the basic
equation D = Pi - Pei where Pi is the partial pressure of component i
which is being absorbed and Pei is the equilibrium pressure of i at the
phase boundary. This basic equation was tested by the absorption of
NO in aq. soln. of FeSO. The mass transfer coef£. is a practically
const. quantity that is inlIependent of the conen. of the absorbent and
the substance being absorbed.
Shelud 'ko, M.K. Some characteristics of green vitriol solutions as
an absorbent for nitrogen oxides from industrial waste produ:: ts of
nitric acid apparatus. Khim. Tekhnol. Resp. Mezhvedomstv.
Nauchn. -Tekhn. Sb. 1965 (2), 68-71; C. A. ~, 14877 b (1966).
The use of aq. solns. of FeSO 4 as absorbents for N oxides in the
waste gases from the HN03 plant was investigated. It was found
that the equilibrium concn. of NO in the FeSO 4 soln. decreases with
the partial pressure of NO in the gas phase; that working with 1% NO
in the waste gas, it took about 63 cu. m. of FeSO 4 soln. to treat
1,000 cu. m. of waste gas. (0.16 cu. m. NO per cu. m. of FeSO 4
soln.) Therefore FeSO 4 solns. are not recommended for use with NO
removal.
-------------------------------------------------------------------------------
90.
91.
92.
Ges. Fur Linde's Eisenmaschinen AG. Removing nitric oxide from
gases. Ger. Pat. 521 031, Oct. 15, 1929; C.A. ~, 2838 (7) (1931).
Traces of NO are removed from gases by washing them with solns.
contg. lower oxides of S or the alkali salts of the corresponding acids.
Since the presence of free OH ions promotes the absorption, an alk.
washing liquor is preferred, and the gases should be preliminarily freed
from acid constituents other than C02' The method is particularly
useful in purifying coke-oven gases prior to sepg. constituents thereof
by liquefaction, and may be put into effect in this case by adding an
alkali sulfite to the alk. washing liquor used to remove C02'
Office National Industriel de l'Azote (Garlet, R., inventor). Removal
of nitrogen oxides from waste gases. Fr. Pat. 1 336 212 (Cl. C 01b, C 01k)
Aug. 30, 1963; U. S. Pat. 3 329 478 (Cl. 23-2) July 4, 1967 (Fr. appl.
July 11, 1962); C.A. ~, 298 b (1964).
Nitrogen oxides in waste gases are removed by scrubbing the gases
with an aq. solution of NH4HS03-and (NH4)2S03 with or without
free NH3' in which the HS03/S03 molar ratio 1S in the range 0.1
to 0.4.
SINCA T Soc. Ind. Catanese Soc. Per. Azioni. Abatement of nitrogen
oxides emission. Fr. Pat. 1 454 723 (Cl. C 01c) Oct. 7, 1966
(appl. Nov. 11, 1964); C. A. 66, 97011 c (1967).
- 30 -
-------
92.
Cont'd.
YJknud «;f'~ CC~
CONSULTING DIVISION
Emission of N oxides from chem. plants was reduced by treating these
with a soln. contg. sulfite or bisulfite according to the following
reactions: 2NO + 48032- ~ N + 48042- and 2NO + 28032- " .
N2 + 280 2-. ?he gas was scrubfied at room temp. with a soln. contng.
either 3. a% Na2803' 4.5 K2803' 0.25 MgS0:l'- or 3.5 NaH803' resp.
The N oxide-contg. gas (0.3-0.4% by vol. of~O and NO ) was bubbled
through the sulfite soln. at the rate of 150 l/hr. through4250 cc. of the
latter. In another example, a 1. 15% by vol. of N oxides equiv. to
N02 was charged through a Venturi tube at the rate of 18,000 m. 3/hr.
ana treated with a soln. contg. 19.5% by wt. of 802 as an NH4 + salt.
In both cases, the exit gas contained 0.01% N oxides by vol. and the
final soln. had a pH 6.4-6.9. The (HN 4)280 4 was concd. and
recovered.
-------------------------------------------------------------------------------
93.
94.
Berquin, Y. F. (Potasse & Engraise Chimiques, France). The PEC
company and the problem of nitrophosphates. Proc. 15th Annual Meeting,
Fertilizer Industry Round Table, Nov. 10-12, 1965, p. 88-92.
The PEC company has developed a process of absorbing nitrogen oxides
from the tail gas of a HN03 plant in a milk of lime followed by treating
the pregnant milk of lime, after filtration, with 2.0-2.5 moles of H2804
per 3 moles of calcium nitrite. Thus all the Ca(N02)2 is oxidized by
H2804 to Ca(N03)2' If more H2804 is used, e. g. 1 mole H2804 per
mole of Ca(N03}2' then HN0..3 is formed. Under this conditiOn, after
filtering off CaBO 4' a 10-20Ujo HN03 can be obtained.
Ganz, 8. N. (Khim. -Tekhnol. Inst. Dnepropetrovsk). Effect of
hydrodynamic condition on the rate of absorption of nitrogen oxides
by solutions of calcium hydroxide in a mechanical absorber on a .
semi-plant scale. Zh. Prikl. Khim. 30, 1311-1320 (1957); C. A. g,
2472 i (1958).
The study made previously with a lab. unit was extended to a unit O. 88 m.
diam., 1. 54 m. long, and 1 cu. m. capacity with 4 perforated disks with
14 spadelike bends in each. With a gas velocity w of 400 cu. m. / cu. m. of
absorber/hr. through a soln. contg. nitrites + nitrates 10-20, Ca070-80
g. /1., the degree of absorptioncL at 60-700 increased with the peripheral
velocity v g rather rapidly at first but at decreasing rates so t hat at Vg
= 22-23 m. /sec. d ':1.1 dVg was small and at v = 27-28m. /sec. approached
zero. In the range of initial gas concn. xl tom O. 14 to 4% (NO-N02)'
cc increased with xl; even with a dil. gas, O. 14-0. 3%, cC = 70-75%, which
was higher than could be obtained in a packed tower. By means of the
method described previously (C. A. 50, 3857b), equations were found
for the coeff. of absorption K = f(x1, v g) in the v ~ range of 14-30 m. / sec.
The generalized form of the equation was K = m ~ + n. From a series
of simultaneous equations of 2 points on each curve of the functions m(n)
= f(x:H' the following empirical relation was obtained Kg = (1490 - 241x-1)
v~. 3 + (590X1 -1 - 2080). K = f(w) was empirically expressed by
- 31 -
-------
94.
Cont'd.
95.
96.
~km«d
-------
96.
Cont'd.
97.
98.
~kmiad ~~ 1f~
CONSULTING DIVISION
G/Vt/jP, where G is the wt. of the gas absorbed (N basis), V the vol.
of the absorber, t time, and.dP is the logarithmic mean driving
force (atm.), is independent of the temp. up to 400 and slightly
decreases above that up to 550. Kg decreases slightly with the concn.
of Ca(OH)2 (up to 13 g. /1. ) and increases with the concn. of I so that
the Kg vs. Ca(OH)2 concn. is a family of parallel straight lines sepd.
by decreasing distances as the gas concn. increases from 0.56 to 1,
3, and 4% 1. From the similarity to the bubble tower the no. of
disks n required is calcd. by [100/(100 - w1gn = C1/C2, where W1
is the degree of absorption by 1 disk and C 1 and C2 are the concns.
of I entering and leaving the plate. Exptl. values of w1 are 80.6,
82.3, 84.8, 87.3, and 90.3%: for C1 0.55, 1. 02, 2.85, 4.4 and
6.2%. The max. n required is 4. It is estd. that construction cost
and operating energy of a revolving absorber are 10 and 38.4% of an
equiv. packed tower. The rate of absorption of N203 is higher than
that of N02 in a revolving absorber.
Ganz, S. N., & Lokshin, M. A. Effect of basic physiochemical factors
on the rate of absorption of nitrogen oxides by solutions of Ca(OH~ in
a rapidly revolving absorber. II. Zh. Prikl. Khim. 30, 1525-153fJ
(1957 ); C. A. ~, 5103 i (1958).
The degree of absorptioncx, of NO + N02 by soIns. of Ca (OH) in a
revolving absorber (loc. cit.) decreased as the concn. C of d(N03)2
+ Ca(N02)2 increased. Empirically, the coef£. to absorption Kg =
mCn, kg. (cu. m. hr. atm. For initial concns. x of NO + N02 (60%
of NO oxidized) from 0.475 to 2. 125%, CaO concns. from 3 to 5 g. /1. ,
peripheral velocity V g of 23 m. / sec., ga's volocity w of 400 cu. m. / cu.
m. hr. at 60-700, m = 4400x + 400 and n = -(0. 13x + 0.24). The calcd.
Kg agreed with the exptl. values within ~2-3%. The effect of the degree
of oxidiation of NO to N02, q, on c<.. was detd. at 30-450 with soIns.
contg. CaO 4-6 g. /1., C = 200-50 g. /1., at V g = 23, and w = 300-20.
With x = 2.2%, iX, increased from 69.8 to 82.1% as q increased from
30 to 70%; the N oxide content in the exit gases decreased from O. 371
to 0.258%. With x = o. 6% c:<.t increased from 62 to 73.2% as q increased
from 32 to 68% and the concn. of N oxides in the exit gases decreased
from O. 228 to o. 172%. The kinetics of the reaction was studied by the
change in C of the partially recirculated soIn. The results indicated
that in a revolving absorber the rate of absorption of N20 and N02
were practically equal; this is attributed to the reactions ~ 20 3 +
Ca(OH)2 = Ca(N02)2 + H20 and Ca(N02)2 + 2N02 = Ca(N03'2 + 2NO.
Potasse et Engrais Chimiques (Quanquin, B., & Trimbach, H.
inventors). Recovery of nitrogen oxides. Fr. Pat. 1 391 087 (Cl.
C 01b) Mar. 5, 1965 (appl. Jan. 21, 1964); C. A. 63, 9510 h (1965).
A gas contg. NO + N02 0.25% was scrubbed with lime water of 110 g.
CaO/1. The effluent gas contained less than 0.023% NO + N02' The
scrubbing soIn. was treated with H2S04 to ppt. CaS04 and recover
the N oxides as 10% HN03'
- 33 -
-------
99.
100.
101.
~~ 1ff'~ ~~
CONSULTING DIVISION
Pozin, M. E., Kopylev, B. A., & Bel'chenko, G. V. Absorption of
nitrogen oxides by milk of lime during bubbling and foaming conditions.
Izvet. Vysshikh Ucheb. Zavedenii, Khim. i Khim. Tekhno1. i, No.1,
102-7 (1961); C. A. 55, 20344 g (1961).
N oxides were absorbed by milk of lime under foaming condi tions at an
extent of 5 times as great as during bubbling, and 10 times as great as
in a packed column. For a content of 30-110 g. CaO/1. in the milk of
lime, the degree of absorption practically did not change during the
accumulation of the nitrite-nitrate salts (up to 200 g. /1. ) in the soln.
The degree of absorption during bubbling increased insignificantly on
increasing the height of the column of liquid to 40-50 mm. : under
foaming conditions, and increase in the rate of the liquid flow from 1
to 5 cu. m. /m. hr. resulted in an increase of the absorption degree
on one shelf of the app. by 15-30% (relative). With an increase in the
flow of the gas, the degree of absorption on one shelf decreased more
during bubbling than under foaming conditions: this was due to the
lower abs. values of the gas rate and a greater contact time of the
phases. In the interval of linear gas rate from 0.5 to 2 m. /sec., the
values of the absorption coeff. of an equimo1. mixt. of N oxides at an
initial concn. in the gas equal to 1%, was equal to 2000-3350 kg. N/cu.
m. hr. atm. The insignificant variation in the degree of absorption
depending on the concn. of milk of lime and on the accumulation of the
nitrite-nitrate salts in soln. permitted realizing the absorption process
with. a rather high degree of absorption of the N oxides and obtaining
relatively coned. nitrite-nitrate solns., when the initial concn. of the
N oxides was not very low. For low initial concns. of N oxides
(<:: 0.5%), the regularities in their absorption changed sharply.
Schmidt, A., & Weinrotter, F. (to Osterreichische Stickstoffwerke
AG). Removal of lower oxides of nitrogen from gaseous mixtures
containing them. U. S. Pat. 3 034 853 (Cl. 23-2) May 15, 1962
(app1. Aug. 4, 1959).
Aq. suspensions of Mg(OH)2 or MgC03 absorb NO and N02 to form
Mg(N02~2_and Mg(N03)2' Upon heating, these compds. give up the
NO anaNU2' thus regnerating the absorbent suspension. The
regeneration is carried out at 1400-2000 under pressure.
Vetrocoke Societa per azioni. Absorption of nitrogen oxides from the
vent gas from nitric zcid-plant absorption systems. Ital. Pat. 513 953,
Feb. 8, 1955: C. A. g, 5764 f (1958).
The vent gas is passed through a packed tower where it is brought into
contact with a suspension of lime in an aq. soln. of Ca(N03)2 and
Ca(N02)2' Clear soln. obtained from a portion of the slurry leaving
this tower is acidified with HN03 to convert the nitrite to nitrate. The
N oxiCles formed are fed back to the front end of the main absorption
system. The Ca(N03)2 soln. from the acidifier is pumped either to
- 34 -
-------
10l.
Cont'd.
~~ ~~~~
CONSULTING DIVISION
the appropriate t ower in the main absorption system, in which case all
the HN03 produced contains Ca(N03)2; or is fed to a smaller
absorption system fed with a portion of the gases from the NH 3-
oxidation converter, in which case only a portion of the HN03 produced
is contaminated with Ca(NO )2.' All the water required for tile main
absorption system is initialry mtroduced with the lime suspens ion.
--------------------------------------------------------------------------------
102.
103.
Rodionov, A. I., Mishchenok, Yu. S., Klimov, A. P., & Bogdanov, E. A.
Absorption of nitrogen oxides with a suspension of limestone. Tr. Mosk.
Khim. -Tekhnol. Inst. 1963 (40) 74-77; C. A. g, 6463 a (1964).
A gas contg. NO and N02 is scrubged with a slurry of finely ground
CaC03 in an absorption column with 15 sieve trays. A foam layer is
maintained over each tray. It was found that the percentage of
absorption is increased by the increase in the concn. of nitrogen
oxides in the gas and also by the increase in the oxidation of NO during
absorption. The degree of this oxidation increases with the height of
the foam layer over the seive tray. Within the range 160 - 580 the degree
of absorption of NO + N02 remained constant, other conditions being the
same.
Zaklady Azotowe im. Pawla Findlera (Blasiak, E., & Jamiczek, W.,
inventors). Absorption of nitrogen oxides from dilute mixtures.
Pol. Pat. 43 284, Aug. 30, 1960 (appl. Feb. 26, 1958); C. A. 57,
7075f (1962).
Gases contg. small amounts of N oxides are passed through a bed of
granular CaCO (3-5 mm. ) which is wetted by a spray of water which
washes off the ta(N03)2 and Ca(N02)2 formed on the surface of the
granules.
-------------------------------------------------------------------------------
104.
105.
Bollinger, K. (to Colasit AG., Switzerland). Purifying air contaminated
by acid or nitrous impurities. U. S. Pat 2 856 259 (Cl. 23-4) Oct. 14,
1958 (appl. Dec. 2, 1950).
The gas contg. N oxides is contacted with a mass of Fe203 supported
on sawdust, arranged in two separate layers, one of Whldi is
irrigated with water. The gas first passes through the dry mass,
then through the irrigated mass, so that the effluent gas contains no
oxides of N.
Kainz, G., & Mayer, J. (Univ. Vienna). Absorption of nitrogen
dioxide on manganese dioxide in C-H determinations. II.
Mikrochim. Acta 1962, 241-8 (in German); C.A. 57, 50 b (1962).
The absorption of N02 by moist Mn02 granules was found to improve
with decreasing grain size. The water adsorbed on the Mn02 granules
served as additional absorbent. The efficiency of absorption decreases
with temp. rise; as the temp. rises above 500 the absorption product
Mn(N03)2 begins to decompose.
- 35 -
-------
'tf~ ~~ ~~
CONSULTING DIVISION
106.
Purtseladze, Kh. G., Dzhikiya, S. I., Karumidze, Z. A., & Chkoniya,
T. K. Absorption of nitrogen oxides by manganese hydroxide. Trudy
Inst. Metal. i Gorn. Dela, Akad. Nauk Gruzin. S. S. S. R. I, 239-247
(1956); C.A. g, 8555 g (1959). .
The results of lab. expts. on the absorption of N oxides at concns. of
....,0.3% and room temp. by Mn ores (Mn sponge, Mn carbonate, and
pyrolusite) and paste-like Mn(OH)2' contg. up to 65% water (with the
addn. of wood shavings to reduce the resistance), showed that Mn ores
quickly become deactivated; Mn(OH)2 was the only compound tested
which proved suitable for the absorp1ion of N oxides. Mn (OH)2 can be
regenerated from the absorption product Mn (N03)2 by the action of
NH40H; as an alternate method, activated Mn02. or Mn concentrates
can be obtained by the thermal dissocn. of the mtrate.
-------------------------------------------------------------------------------,
107.
108.
109.
Fulweiler, W. H. (to United Gas Improvement Co.) Purification of
gas from oxides of nitrogen. U. S. Pat. 2 031 410 (Cl. 23-3) Feb.
18, 1936 (appl. Sept. 16, 1933); C. A. 30, 2354 (4)(1936).
In the removal of N oxides by Fe sulfide, the efficiency is maintained
by removing substantially all of the 02 in the gas (suitably by the
action of Cu at about 2000c. ) before tHe gas is brought into oontact
with the Fe sulfide.
Ovcharenko, A. P., & Kovpakova, R. F. Purifying a gas of nitrogen
oxides. U. S. S. R. Pat. 191 033 (Cl. C 10k) Jan. 14, 1967 (appl.
Apr. 13, 1964); C.A. 68, 23238 b (1968).
The gas is purified by passing it throughapacking of plane parallel
steel plates. To increase the degree and rate of purification,
freshly-deposited FeS is applied to the plates. .
Ward, A. L., &; Jordan, C. W. (to United Gas Improvement Co.)
Gas purification. U. S. Pat. 1 976 704 (Cl. 23-3) Oct. 9, 1934 (appl.
July 16, 1922); C.A. 28, 7441 (7) (1922); cf. U.S. Pat. 2073083
(1937); C. A. l!, 3244 (5) (1937).
The gas contg. about 35-52 g. NO per million cu. ft. and O. 5-0. 6%
02 is passed through a bed of spent "Lux" iron oxide contg. H2S,
TIle NO is entirely removed.
-------------------------------------------------------------------------------
110.
Dita Orvam di Borgatti Tersilla. Removal of nitric oxides from the
ozonized air emitted by ozonizers. Ital. Pat. 650 226 (Cl. C 01b)
Dec. 10, 1962 (appl. Apr. 17, 1961); C.A. 67,46966 f (1967).
Nitrogen oxides in the ozonized air are removed by filtering
through a porous mass of alkaline material.
- 36 -
-------
~~
-------
114.
115.
~~ ~~1f~
CONSU L TING DIVISION
Ogg, Jr., R.A., & Ray, J.D. Method of recovering dilute nitrogen
oxides from gaseous mixtures. U. S. Pat. 2 684 283, (Cl. 23-2)
July 20, 1954 (appl. Sept. 21, 1950).
A gas contg. N oxides is mixed with 02 and passed through a mass
of Fe20? and NaJo, the latter two being in 1:1 molar ratio, at a temp.
in the rahge 300 -5000 to form NaN03'
Perov, E. V. Absorption of nitrogen oxides by magnesium, strontium,
and barium hydroxides. Tr. Novocherk. Politekhn. Inst. 121, 57-60
(1961); C. A. g, 12696 g (1964).
N oxides weo-e absorbed by solid Mg(OH)2' Ba(OH)2.8H20, and
Sr(OH)2.8H2)' Expts. with absorptionfrom mixts. contg. 0.25-1. 0%
of N oXides at 25-350 (Mg(OH)2) and 150 (Sr and Ba hydroxides) showed
that the process results in formation of nitrates and nitrites of these
metals. Oxides adsorbed by the solid phase are easily swept out with
air. From Mg(OH)2 the salts may be sepd. by leaching with H 0. In
case of Mg(OH)2 the rate of reaction is approx. the same at 253 and
350. At a flow rate of the gas mixt. of 0.5 1. Imino the satn. of the
absorbent is achieved within 60-70 min. The absorbent utilization
factor is then ~O. 45. Reaction with Sr and Ba hydroxides (0. 1 g. of
absorbent at flow rate of the gas mixt. O. 5 1. Imino ) was completed
within 30-40 min. The utilization of the solid mass is then 900/0 for
Sr(OH)2' 8H20 and 480/0 for Ba(OH)2' 8H20.
-------------------------------------------------------------------------------
116.
117.
Borok, M. T. Absorption of trace cQlcentration of N02 by aqueous
solutions of salts of aromatic amines. Zh. Prikl. Khim. E, 2035-2042
(1960); C. A. 55, 24136 f (1961).
The rate of absorption (Q) and the degree of absorption (c(), fI. = (initial
concn. - final ccncn. )/initial concn., of N02 from a gas with initial
concn. (Ci) 10-3_10-2 mg. /1. by benzidine in aq. AcOH (n and by m-
phenylenediamine in aq. HCI (II) were detd. in absorbers of 4 different
geometric forms. In all absorbers, C decreased continuously as the gas
rate (V) increased, but the relative rate of absorption, q = dQ/dCi = (V~
passed through a max. % at Vo and decreased at V > Yo. The values of
the consts. n, a, and b in the theoretical equation" = a (1 - bVn) were
calcd. from the exptl. c:t vs. V curves; n was practically independent of
the structural parameters of the absorbers and of the concn. of I and II;
n = 0.32. Apparently n was a function of the soly. of NO in the liquid
phasO' [or values of Ci from 0.002 to 0.012 mg. /1. C( ~f(V)(1 + 0.001/
Ci)C i. . 1 ,where the function fey) was similar to the function < =
a [(b/vn) - 1].
Ganz, S.N., & Kuznetsov, 1. E. Purifying gases by removal of nitrogen
oxides. U. S. S. R. Pat. 186 985 (Cl. C 01b) ext. 11, 1966 (app1. Mar.
19, 1965); C. A. 67, 13335 w (1967).
- 38 -
-------
rc~ ~~ W~
CONSULTING DIVISION
117.
Cont'd.
118.
119.
120.
121.
Nitrogen oxides are removed from gases by scrubbing the gases with
an aq. solution of urea.
Maury, L. G., & Nahill, G. F. (to Hercules Powder Co.) Separation of
solvated fixed nitrogen. U.S. Pat. 3044853 July 17, 1962 (appl. May
29, 1958); C.A. ~, 10776 e (1962).
An electron donor compound is separated from N compounds by con-
tacting the donor compound with an oxidizing agent in the presence of
a Lewis acid under conditions for converting N compounds to HN03'
When N02 is present, a sufficient amount of H20 in the contacting
zone reacts with the N02 to form HN03 which 1S then separated from
the solvent.
Maury, L. G., & Nahill, G. F. (to Hercules Powder Co.) Removing
nitrogen oxides from fluids and nitrous acid. U. S. Pat 3 044 844,
July 17, 1962 (appl. May 29, 1958>. C.A. 57, 10780 b (1962).
The gases contg. small amounts of N oxides are passed through, or
contacted in counter-current flow with a partially water-miscible
liquid electron donor compound contg. 2-25% water. The temp.
limits are 0-200oF. 80-100% of N oxides in the gases treated are
thus removed. Examples of the electron donor compounds are:
glycol ethers, alkyl phosphate, aryl phosphate, alkyl amines, alkyl
sulfoxides, and alkyl phosphoramines.
Prokopovich, A. A., Balitskii, A. S., & Agafonov, E. T. Absorption
of nitrogen oxides. U. S. S. R. Pat. 197 512 (Cl. B Old b) June 9,
1967 (appl. June 29, 1966); C. A. 68, 88604 n (1968).
BU3P04 is specified as absorbent for nitrogen oxides.
Union Rheinische Braunkohlen Kraftstoff AG. (Hubenett, F.,
Dorffurt, H., & Nettesheim, G., inventors). Removal of nitrogen
oxides from gases. Ger. Pat. 1 038 014 (Cl. 12 i) Sept. 4, 1958;
C.A. 54, 17853 d (1960); cf. Ger. Pat. 1 104494 (1961).
NO in gases is removed by first oxidizing it to N02' The latter is
absorbed in an aq. soln. of a dialkyl sulfoxide and a dialkyl sulfone.
The absorbent soln. is periodically regenerated.
-------------------------------------------------------------------------------
122.
Giammarco, G. (to S. p. A. "Vetrocoke"). Removing nitrogen oxides
from gaseous mixtures: U. S. Pat. 3 031 258, Apr. 24, 1962
(Ital. appl. Feb. 15, 1955); C. A. ~, 2520 f (1962).
The entire gas stream and contained tota gums are heated to 90-1500
for the release of all combined and occluded N oxides before passing
the gaseous mixt. through equipment operated at superatm. pressure
- 39 -
-------
122.
Cont'd.
rc~ ~~ ~~
CONSULTING DIVISION
and at sufficiently low temps. to maintain diene-class materials either in
a liquid state or in a strongly coned. some in a liquid petrleum-derived
solvent. The diene should boil at 35-450. Cyclopentadiene is the most
active diene. In the 2nd stage of the pressurized, low-temp. app.,
volatilized dienes are obtained from the gas stream for return to the
1st stage for addnl. removal of N oxides. Thus, 24,000 cu. m. Ihr.
gas contg. 0.5 p. p. m. N oxides, compressed to 12 atm. was scrubbed
at -400 bu 20 cu. m./hr. of kerosine contg. dienes, b. 35-400. Approx.
2-4 cu. m./hr. was distd. by using hydroquinone to prevent polymerization
of reaction products in the so lvent.
-------------------------------------------------------------------------------.
---------..---------------------------------------------------------------------.
123.
124.
125.
Szepesy, L., & Giona, A. R. (Univ. Rome, Italy). Elimination of
nitrogen oxide in low concentrations by means of adsorption. Chim. Ind.
(Milan) 47 (6), 588-92 (1965) (in Italian); Magy. Kern. Folyoirat 1..! (9),
399-403 (1965) (in Hungarian); C. A. ~, 10725 g (1965); 64, 52 d (1966).
For the adsorption of NO from gas contg. NO in ppm. several adsorbents
were investigated. They were ion-exchange resins, silica gel, molecular
sieves and active C. Of these, active C showed best results. It was
found that the displacement velocity of the adsorption zone is. independent
of concn. of NO and the distribution isotherm was linear in the range
studied (0-16 ppm.) Isotherms at 200, 500, and 800 are shown.
Riese, W. Removal of nitric oxide from coke-oven gas transformed
by thermal cracking. Brennstoff-Chem. 20, 301-8 (1939); C. A. 34,
6023 (4) (1940).
Expts. using chemical absorbents for the removal of 1-3 ppm. NO
found in the coke-oven gas were unsuccessful. Adsorption of NO on
activated C was found satisfactory. The C may be reactivated by
heating at 3000 in presence of steam. Silica gel was found not
satisfactory as a NO adsorbent.
Smith, R. N., Lesnini, D., & Mooi, J. (Pomona College, Claremont,
Calif.) The anomalous adsorptive properties of nitric oxide.
J. Phys. Chern. 60, 1063-6 (1956); C. A. g, 39 f (1957).
NO reacts readily with C surfaces at 0 and -780 to form gaseous N
and C{) surface complexes. Thus, adsorption isotherms detd. at
these temps. with C are fictitious; likewise, previous calorimetric
measurements are heats of reactions, not heats of adsorption, for
unknown amts. of NO. NO does not react with a C surface at -1540,
and adsorption appears to be normal, although the adsorbed state is
probably N 20 . NO also adsorbs normally on both porous and non-
porous Si02 a1 0 and -780, but there is some revers ible chemisorption
in each case. NO may interact to some extent at -780 with the water
bound in the Si02 gel. .
-------------------------------------------------------------------------------
- 40 -
-------
Y/.knuad ~~ ~~
CONSULTING DIVISION
126.
Solbakken, A., & Reyerson, L. H. (Univ. of Minnesota, Minneapolis).
The chemisorption of nitric oxide by alumina gel at 00. J. Phys.
Chern. ~, 365-6 (1962); C. A. 56, 13573 i (1962).
The final equilibrium of the chemisorbed NO on Al203 gel was
determined at the end of a 128-day period. The 221J mg. Al203
gel had adsorbed 2.56 mg. NO. The low transmission coeff.
accounting for the slow chemisorption was confirmed by magnetic
studies of the system.
-------------------------------------------------------------------------------
127.
Mortland, M. M. (Michigan Agr. Expt. Sta., East Lansing). Nitric
oxide adsorption by clay minerals. Soil Sci. Soc. Am. Proc. 29 (5),
514-19 (1965); C.A. 64, 7402 b (1966).
NO was chern. adsorbed on montmorillonite and nontronite when the
exchange complex was satd. with certain transition metal ions. The
ir data showed a no. of reactions depending on the nature of the satg.
ion, including (1) coordination of NO as the mono or dinitrosyl
complex, (2) formation of N 0, and (3) formation of (NO)+: The NO
mol. was able' to penetrate tte interlamellar regions of Co montmoril-
lonite or Co nontronite. On all other systems apparently only surface
adsorption occurred. When air was admitted, a 11 surface-adsorbed
NO was immediately oxidized but interlamellar NO decreased at a
rate dependent upon the diffusion of NO to the clay mineral surface.
A product of oxidn. was found to be coordinated nitrile.
-------------------------------------------------------------------------------
128.
Zarif'yants, Yu. A. (State Univ. Moscow). Properties of the
surfaces of freshly cleaved graphite. IV. Adsorption and
differential heat of adsorption of nitric oxide. Zh. Fiz. Khim. 38,
2655-8 (1964) (in Russian); C. A. 62, 3438 e (19.65).
The mechanism of the reaction of NO with finely dispersed graphite,
sp. surface 380 sq. m. / g., was studied by adsorption and by
magnetic susceptibility, x. At 100-600 mm. H& sorption was phys.
At 5-100 mm. Hg)most NO adsorbed was irreversible. Sorption at
600 mm. followed by desorption 16 hrs. at 5 X 10-5 mm. left 4.8
micromoles / sq. m. as irreversibly adsorbed. The 2nd cycle was
completely reversible. This was confirmed by x. The differential
heat of adsorption during the initial period was 50-3 kcal. /mole,
whereas the heat of adsorption of the 2nd cycle was only 4 kcal. / mole.
Apparently the bond of NO was of the C-NO type. The presence of this
bond was confirmed by the ir spectrum. The amt. of irreversibly ad-
sorbed NO on a completely oxidized graphite surface was 2.2 mi-
cromoles / sq. m. suggesting a covalent bond of the -O-NO type.
-------------------------------------------------------------------------------
- 41 -
-------
~~ ~~~~
CONSULTING DIVISION
129.
130.
131.
132.
Briner, E., & Sguaitamatti, B. The recovery of nitrogenous gases by
adsorption. 1. Adsorption of nitric oxide by silica gel. Helv. Chim.
Acta~, 1216-1231 (1940); C. A. 35, 2051 a (1941).
Adsorption of NO on silica gel was studied at -780, 00, and 500. The
data were compared with those for 02 and C02'
Briner, E., & Sguatamatti, B. The recovery of nitrogenous gases by
adsorption. III. Recovery of nitric oxide from silica gel. Helv. Chim.
Acta 24, 421-434 (1941); C. A. ~, 7788 (3) (1941).
The adsorption of NO from air by silica gel increased with decrease
in temp. and with increase in moisture content of the air. A
mechanism is proposed leading ultimately to the formation of HN03
on silica gel. Upon h'eating, the desorbed gas mixt. contains both
NO and N204' Recovery is nearly 100%.
Kazakova, E. A., Khiterer, R. Z., & Bomshtein, V. E. Apparatus for
purifying nitrose waste gases with fluidized silica gel circulating in an
adsorber-desorber system. Khim, Prom. 44 517-520 (1968); Brit.
CherI).. Eng. H, 667-8 (May 1969); C. A. 69, 79960 u (1968).
Waste gases from HN03 manuf. contg. O. 2~0. 3 vol. % of NO + N02'
were cooled to 00, the condensed HN03 was sepd., and the gases were
brought in contact with a countercurrent stream of silica gel particles
(0.2 -3. 0 mm. in diam. ) fluidized bya ir. As a result, the concn. of N
oxides in the waste gases was reduced to 0.04-0.05 vol. % and the gases
were released to the atm. After satn. of the silica gel with N oxides
(to 50-60% of its capacity), it was moved to a desorber where it was
regenerated by contact with dry steam at 180-900, and then returned to
the absorption tower. Gradual decrease in the particle size of the
silica gel occurred with time. Pilot-plant equipmen t for continuous
fluidized -bed adsorption -desorption of the N oxides is described.
Kuznetsov -Fetisov, L.1., & Krasnyi, E. B. Adsorption of nitric
oxide. Trudy Kazan. Khim. -Tekhnol. Inst. im. S. M. Kirova 1958,
No. 22, 106-116, C.A. 53, 21029 e (1959).
Static activity of local adsorbents towards NO is investigated
gravimetrically at 10, 25, and 400 and equil. pressures of 100-760
mm. Five to 6 cycles of detns. are made for each adsorbent at const.
conditions by noting the elongation of a quartz or Mo-glass spiral at
sorption equil. (the error is 1-5%). Si02 gel, Al203 gel, Fe203- gel,
Si02 gel copptd. with Ni(OH)2 gel and Cu(OH)2' carooalumino gel,
and carbosilica gel, all having 2. 5-4 mm. particle size, were made
in the lab. Com. adsorbent Si02 gels, KSM, MSM, KSK, and a silica
gel contg. Al203 ShGSG; and bauxite from south Ural of 2. 5-4 mm.
particle size are used as adsorbents. Carboalumogel, Si02 gel
copptd. with Ni()H)2 gel and Cu(OH)2 andSi02 gel KSM possess the max.
- 42 -
-------
Y5~ <;f'~ ~~
CONSULTING DIVISION
132.
Cont'd.
static activity, each at different temps. in the order listed (carboalumogel
and Si02 gel copptd. with Ni(OH).2 gel have the max. activity at all temps. )
At increased temps. the adsorptton value of all adsorbents decreases in 2
intervals of 10-250 and 25-400 by 1. 4-2 times in each. The isotherms of
adsorption are S-shaped indicating the possibility of multimol adsorption.
The best conditions of desorption are 3000 and evacuation to 10-5 mm. and
give 98-9% desorption. Incompleteness of desorption and formation of
color on the surface of the adsorbents reveals the possibility of chem.
reactions wi th H20 of constitution to give higher oxides, HN03' and
chemisorbed complexes. The Freundlich adsorption isotherm equation
can be used as an interpolation formula for the exptl. results with all
adsorbents. This was checked graphically. The Langmuir equation is
inapplicable for this purpose. The calcd. apparent activation energy
E 10-250 of NO adsorption on Si02 copptd. with Ni(OH)2. gel is 1940 cal. /
mole, bauxite 2356, ferrogel 30f13, carboalumogel 45l7! and Si02 gel
KSM 7100; and E25-400, 2244, 2204, 2604, 3669, and 9533, resp., at
760 mm. pressure and 10, 25, and 400. Energy of activation
influences the adsorption of gaseous substances.
-------------------------------------------------------------------------------.
133.
134.
Brenman, J. A. (to Socony Mobile Oil Co.) Removal of nitrogen oxides
from combustion gases. U. S. Pat. 3 015 369, Jan. 2, 1962 (appl. May
23, 1960); C. A. 56, 9715 f (1962).
NO in exhaust gases is removed by passing the gases through a hot bed
of 13X molecular sieve. 2 examples are given. (1) At 4200 and space
velocity 31,200 per h., the NO content of a N2 gas was reduced from
0.55 down to 0.13 mg. /1. (97 ppm. by vol. ) aIter 3 h. (2) At 4000 and
space velocity of 3000 per h., the NO content was reduced from O. 88
down to 0.02 mg. /1. (15 ppm. by vol. ) after 1 h. of opera tion. .
Chachulski, J., Kornblit, L., Kruszka, F., Koczorowica, B., &
Woszek, B. (Sodium plant Inowroclaw, Poland). Type 5A molecular
sieves of Polish production. Chemik (Gliwice).!.!!, 252-5 (1965)
(in Polish).
A synthetic zeolite was prepared having an approximate formula 0.7
CaO. 0.3 Na20. A1203. 2 Si02' It was found to absorb readily
at room temp. 28 different gases and vapors including CO2' cas,
CS2' Cl2' CH4' C2H2' and NO.
-------------------------------------------------------------------------------.
-------------------------------------------------------------------------------.
- 43 -
-------
~~ ~~ CC~
CONSULTING DIVISION
135.
136.
137.
Baranov, A. V. Okhramovich, A. E., & Pashchenko, P. A. Adsorption
of nitrogen oxides by activated carbon. Trudy Dnepropetrovsk Khim. -
Tekhnol. Inst. 1958, No.6, p. 35-65; C. A. 55, 7982 e (1961).
Factors affecting the dynamic capacity of activated C (brand Bay) and
the time before N oxides passed through the adsorbent that were
studied were temp., concn. of N oxides in the gas mixt., linear and
total velocity of the gas mixt., depth of the layer, avo size of grm ules,
and moisture content of the absorbent. Activated C adsorbed N oxides
well. When it was used for collecting N oxides from tail gases from
the production of HN03' the vol. of the tower for acid absorption
could be decreased, and the concn. of N oxides in the gas entering
the first tower increased.
Baranov, A. V., & Okhramovich, A. E. The desorption of nitrogen
oxides from activated carbon. Nauchn. Tr. Dnepropetr. Khim.
Tekhnol. Inst. 1961, No. 12, Pt. 2, p. 185-8, C. A. ~, 15861 e (1962).
The kinetics of desorption of N oxides from activated carbon were
studied at 100-2000, both in. vacuo and in a flow of air. The total
desorption was measured by absorbing the gas in O. 5N NaOH, and the
reaction was followed by weighing the tube contg. the carbon at 5-min.
intervals. In an air flow of 10 ml. Imin. the rate of desorption at
~1000 was very low. Thus, in 2 hrs. at 1000, 80% desorption was
observed. The rate of desorption increases with increasing temp.
At 1250 desorption was 90% in 1 hr. ; at 1500 95% in 1 hr. ; at 1750
100% in 30 min. ; at 2000 100% in 10-15 min. The activity of the
carbon was not lost after repeated sorption and desorption. C02
appeared in the desorbed gases as a result of the action of the N
oxides on the carbon. The rate of attack depended on temp.' The
kinetics of desorption in vacuo were studied at 100 and 1250. The
rate of desorption in vacuo is much greater than in a low rate of air
flow at the same temp. Thus, at 1000, 93% was desorbed in 30 min.
in vacuo, and only 78% in 2 hrs. in an air flow. Most of the desorp-
tion occurred in the first 15 min. The degree of desorption in vacuo
at 1250 was equiv. to that in a flow of air at 1750.
Ganz, S. N. (Chem. -Techno!. Inst., Dnepropetrovsk). Adsorption
of nitrogen oxides by solid adsorbents. 1. Zh. Prikl. Khim. ~,
138-140 (1958); C. A. g, 9534 a (1958); English transl, available
at Chemico Library.
The absorption of NO + NO by solid absorbents at 18-200 was
investigated. A O. 3% gas ~O 60 + N02 40%) was passed at 1000-
2000 cu. m. I cu. m. hr. at linear velocities from O. 024 to O. 048
m. /sec. through a packed tower. The rate of absorption and the
- 44 -
-------
137.
Cont'd.
138.
139.
140.
~~ ~~ rc~
CONSULTING DIVISION
capacity decreased in the following order: activated C > Al silicate> Si02
gel> Mn02 > CuO :> Mn02 60 + CuO 40%. Because of the catalytic
oxidation and the formation of HN03' desorption was possible only above
3000. The most stable absorbent was Al silicate.
Kurita Kogyo KK. Adsorption of nitrogen oxides. Japan Pat. 23 925
(1963); d. Chemiker-Ztg. /Chem. Apparatur.!!Q, 632-635 (1965).
A gas contg. 0.2% nitrogen oxides was passed over active C made from
coconut shell to remove 95-98% of the N oxides. The active C was
regenerated by washing with water followed by drying.
Lozhkin, A. F., & Subochev, N. L. Recovery of nitrogen oxides from
lean gases by activated carbon in a moving bed. Sb. Nauch. Tr.,
Perm. Politekh. Inst. No. .!.!!' 61-74 (1965); C. A. ~, 20533 s (1967).
The adsorption of N oxides from gases contg. low concns. of the N
oxides by granulated activated carbons of grade KAD and AG in a fixed
bed and in a moving bed was studied. The adsorption capacities of the
KAD and AG carbons were equal and depended on the degree of oxidn.
of the N oxides in the gas; the higher the degree of oxidn., the higher
the adsorption capacity, all other conditions being equal. The possi-
bility of detg. the linear transporting velocity of the carbon in a hyper-
sorber by using data on the movement of points of equal concn. in a
fixed bed was studied. During the thermal regeneration of the spent
carbons, dissocn. of N02 into NO and ° takes place on the surface of
the adsorbent. As a result, some of the carbon is lost by the formation
of C02' For each adsorption-desorption cycle, the combustion losses
of KAD and AG were -'0. 5 and 0.4% of the inital wt., resp.
Ruhrchemie AG (Rottig, W., inventor). Separation of nitrogen oxides
from residual gases from nitric acid production. Ger. Pat. 1 040 003
(Cl. 12 i) Oct. 11, 1958; C. A. 54, 25645 b (1960).
The gases are treated at 50-400 with activated C and passed over
alkaline earth oxides and/or hydroxides or carbonates after
saturating with water. The coefficient of absorption is 80-90%.
-------------------------------------------------------------------------------
141.
Ganz, S. N. (Chem. -Technol. Inst., Dnepropetrovsk). Adsorption
of nitrogen oxides by solid adsorbers. II. Adsorption by aluminum
silicate sorbents. Zh. Prikl. Khim. l.!., 360-8 (1958); C.A. 52,
13204 a (1958),
The degree of adsorption K' of dry NO + N02 and the degree of oxida-
tion K' I of NO by Al silicate at 18-200 decreased with the gas rate w and
incre
-------
Y/~ 1ff'~ ~~
CONSULTING DIVISION
141.
Cont'd.
142.
143.
rate of adsorption, kg./cu. m. hr., and the coeff. of adsorption, kg./cu.
m. hr. atm., increased with w and passed through a max. at w = 600-900
cu. m./cu. m. hr. Apparently Al silicate acted as a catalyst of NO
oxidation. With moist gases K' decreased as the H20 vapor in the gas
increased. In the temp. range from 12 to 420 with w = 500, H20 in the
gas 3.1%, 'and NO + N02 = 1. 38%,K" was 96-8% and K' decreased
from 97% (in dry gas) to 78%. K' decreased as the temp. increased
from 45 to 600. Desorption with N at 160-5000 yielded HNO .
Complete desorption was obtained with NO + N02 gases at 3JOo.
Kulcsar, G. J., & Vodnar, 1. (Univ. Babes-Bolyai, Cluj, Romania).
Adsorption of nitrogen dioxide on aluminum silicate. 1. Adsorption
capacity of activated kaolin. Studia Univ. Babe-Bolyai, Ser. Chemia
~ (1), 47-53 (1964); C.A. g, 15386 d (1964).
The kaolin used contained 98% A1203' 2Si02' 2H20. It was activated by
the Kopylov method, resulting in asp. surIace of 48.5 sq. m. I g. The
gas used to measure the adsorption capacity contained 4. 64% N02 .
The "degree of adsorption" was found to be 20.59% at 20. 80. Repeated
adsorption and desorption caused the activity of kaolin to decrease (to
75.33% of its initial value after 5 cycles).
Kulcsar, G. J., Vodnar, 1., Lengyel-Szabo, Gy., Boejthe, P., &
Zete, Z. (Univ. Bables-Bolyai, Cluj, Romania). Adsorption of
nitrogen dioxide on aluminum silicates. II. Studia Univ. Babes-Bolyia,
Ser. Chern. .!l. (1), 79-84 (1966) (in Romanian); C. A. ~, 17734 (1966).
The adsorption of N02 on these kaolins was studied by a previous method
(CA 61, 15386 d). TEe N02 was generated by bubbling S02 through a
68% soln. of HNO at 800. The apparent adsorbent vol. was 35 cc. and
the air was passe~ at a const. rate of 4450 cc. Ihr. The initial N02
concn. in the air was --'12%. The degree of adsorption of the NO 1S
given as a function of the initial NO content of the kaolin at 25-1~00.
The degree of adsorption decreased2with increasing temp. and increasing
N02 content of the kaolin. The amt. of NO.2 retained on fresh adsorbers
at 2"50 was I 0.27 and II 0.42 millimoles NU2 / g. adsorber. In the two
cases, the amt. of N02 adsorbed from the gas was I 95 and II 99%, but
only ~50% for kaolins already contg. I O. 18 and II 0.30 millimoles,
NO,) g. adsorber. The degree of adsorption decreased sharply from
200'"to 400. This was attributed in part to the displacement of the
equil. 2N02 ~~ N 20 4' Despite this sharp decrease of adsorption with
temp., the retention of N02 by fresh kaolins at 1200 was still I 55.4
and II 66.4% of the amt. present in the gases. The total adsorption
capacity of the kaolins decreased from I O. 12 and II O. 35 millimoles
N02/g at 250 to I 0.05 and II 0.055 millimoles N02/g. at 1200.
Regenerated kaolins lost 34% of the total adsorption capacity after
the first regeneration and 11% in addn. after the 2nd.
-------------------------------------------------------------------------------
- 46 -
-------
~~ ~~~~
CONSULTING DIVISION
144.
145.
146.
Gordunkel, V. E., Kazakova, E.A., & Chernyavskaya, M. K.
Purification of exhaust gases. U.S.S.R. Pat. 129 193, June 15, 1960;
C. A. 55, 3039 f (1961).
Exhaust gases contg. approx. 0.3% N oxides are cooled to about OOC.
and passed through miltistage fluidized beds of silica gel. The
adsorbed N oxides are then desorbed from the silica gel by heating
the gel and blowing air through the beds.
Kazakova, E. A., Chernyavskaya, M. K., & Nizhegorodova, N. V.
Enrichment of dilute nitrous gases by adsorption in a fluidized bed.
Khim, Prom. 1962, 506-512; C. A. 58, 3114 f (1963).
The enrichment of dil. nitrous gases by a modified Wisconsin process
(Ermence, CA~, 1557 a) was studied in the lab. The modifications
introduced were: N02 was adsorbed on finer silica gel particles than
in the original process. The catalytic oxidn. of the NO to N02 was
carried out in a fluidized bed at - 100 instead of at - 500, the
adsorption of N02 on the lower trays was non-adiabatic, and the
desorption process was also carried out in a fluidized bed. The
N02 content in the enriched gas was 30-40% as compared with 2. 5%
NO + N02 in the raw material. Among the silica gels studied brand
ASM had the highest adsorption capacity, 45 g. N02/ 100 g. adsorbent
at -110 and 150 mm. The equil. concn. of H20 on the adsorbent was
close to the equil. H20 concn. in the gas at ilie exit of the fluidized
bed; equil, adsorption of the H ° was obtained with bed thicknesses
below 50 mm. The capacity of the silica gel increased with increasing
H20 content in the raw gas showing that pi rt of the N02 was absorbed
on water on the silica gel. The effect of gas velocity (within the range
0.13-0.30 m. /sec.) on the degree of adsorption of the N02 was
insignificant, i. e., there exists a rate-controlling interal diffusion
process. Complete desorption of the N02 was obtained byblowing
air for 15-20 min. at 180-2000. Expts. on a pilot-plant column
showed that the amt. of silica gel needed to adsorb 1 g. N02 varied
from 7 to 40 g. within the temp. range 0-200. The presence of NO
reduces the degree of adsorption of the N02; this redn. is, however,
slight and by using the combined N02 adsorption-NO oxidn' method,
the overall energy consumption is practically equal to that in the
adsorption of N02 from NO-free gases.
Krasnyi, E. B., Kuznetsov-Fetisov, L.!., & Rozenberg, G.!.
(Khim. -Tekhnol. Inst., Kazan). The adsorption of low concentrations
of nitrogen dioxide-nitrogen tetroxide under dynamic conditions. Izv.
Vysshikh Uchebn. Zavedenii, Khim. i Khim. Tekhnol. ~, 802-5
(1963); C. A. 60, 8669 e (1964).
- 47 -
-------
~km«:d ~~ ~~
CONSULTING DIVISION
146.
Cont'd.
147.
The sorption characteristics of a com. Si02 gel (1) designated as KSM
were compared with those of a synthetic NiO-Si02. gel (II) for removal
of low CDncns. (0.5-1%) of N02+N204 from air. Apparent d. of I was
1. 388, that of II was 1,236; sp. surface of I was 654 sq. m. I g., that
of II was 448. Grain size of I was 2.7-7 mm. Adsorptions were
carried out at 250 in a 14 mm. diam. U-tube with a bed depth of 40
em. and a gas velocity of 1 m. Imin. Desorption was conducted by
passing air through the U -tube at 3500. For each gel, adsorption-
desorption cycle was repeated several times with similar results.
Time to break-through (indicated by coloration of KI-starch soln.
through which effluent air was bubbled) was 51-73 min. for I and
531-737 min. for II. At break-through I and II had adsorbed 0.43
and 5.7 g. N oxides I 100 g. gel, re sp., fr9m air contg. 1% N oxides.
Adsorption isotherm of II was S -shaped, whereas that of I was a
smooth curve.
Krasnyi, E. B., & Kuznetsov-Fetisov, L. I. Investigation of the
adsorption and desorption of N02~~ 20 4 on technical silica gels
ASM and No.6. Tr. Kazansk. Khlm. -Tekhnol. Inst. No. 30, p.
223-239 (1962); C.A. 60, 3515 b (1964). .
Two tech. Si02 gels, ASM and No.6, were structurally characterized
according to 9 phys. properties: apparent d., true d., total porosity,
total pore vol., max. adsorbed vol., sp. surface, effective radius of
pores at max. of distribution curve, pore radius, and particle diam.
The amt. of structure H20 for ASM and No.6 is, resp., 5. 66 and
4. 53%. These SiO gels belong to the 3rd structural type (uniform,
fine pore adsorbent> according to the classifica tion made by Kiselev
(CA,il, 6033 0. Adsorption and desorption isotherms of N02+N 204
on Si02 gel ASM and No.6 were obtained at -1, 0, 10, 20, 41), and
1000 and relative pressures from 0 to 1. The activity of the gels is
independent of temp. in this pressure range. At const. e quil. satn.
pressures, the activity increases with temp. decrease. The dependence
of activity on a change of equil. and relative pressure at const. temp.
is the same for both gels. The adsorption isotherms are of the
Langmuir type and can be described by the B. E. T. equation in the
relative pressure range from O. 07 to O. 32. The NO 2+ N 20 4 was
proved to be monomol.} adsorbed and for complete adsorption of low
concns. of N02+N204 it is necessary to use adsorbents of the 3rd
structural type wlth pore diam. of 20-22 A. Indirectly a partial
chemisorption arises from interaction of the N oxides with the OH
groups of the silicic acid to form stable chemisorbed complexes.
The adsorptive properties of. Si02 gels depend on 2 factors: structural
(pore size) and chern. (degree ofnydration of the gel surface).
- 48 -
-------
CONSULTING DIVISION
148. Mizukami, S. Carbon and hydrogen determination. Hydroxyl-amine
sulfate as an adsorption agent for oxides of nitrogen. J. Pharm. Soc.
Japan 7.6, 1216 (1956); C. A. H, 945 l (1957).
Adsorption of NO (in the case of NO. it is first oxidized to MX) is
effected by usingEiO gel contg. 30% NH OHH SO . A satisfactory
result was obtained in the analysis of C and H in picric acid, MeNO-,
and dicyandiamide, etc.
149. Peters, M.S. (Univ. of 111. ) Stop pollution by nitrogen oxides.
Chem. Eng. j>2, May 1955, p. 197-200.
Efficiencies of removal of NO- and NO from air by absorption by
water and adsorption on silica gel were compared exptly. Results
indicated that the highest efficiency may be obtained from water
absorption using porous glass as gas-bubble producer. This system
requires a higher pressure drop and a lower gas rate than correspond-
ing systems of water spray tower, packed column, bubble-cap tower,
and dry silica gel. The removal efficiencies of the last two systems
were found next highest. Data are agiven.
150. Sundaresan, B.B., Harding, C.I., May, F.P., & Hendrickson, E.R.
(Univ. of Florida, Gainesville). Adsorption of nitrogen oxides from
waste gas. Environ. Sci. & Technol. J^, 151-6 (Feb. 1967);
Nitrogen (London) No. 48, July/Aug. 1967, p. 38; C.A. J56, 88456 z (1967).
A systematic study was carried out of the adsorption of N oxides on
silica gel and commercial zeolite. It was found that the zeolite is
more efficient than silica gel. A simulated HNO- plant tail gas was
used in the experiments. The input gas contained 1800 ppm. N oxides
calcd. as NO and the exit gas contained less than 10 ppm. of N
oxides with a given cycle which has a continuous adsorption period of
up to 3 h., although it is considered that a N oxides concn. of 200 ppm.
in the HNO« plant exit gas is permissible. The N oxides were
desorbed from zeolite by action of hot air or steam. A treatment for
30 min. gave an 80-85% recovery of N oxides, of which 1/4 was in
the form of enriched N oxides and 3/4 in the form of a weak acid
contg. about 20% HNXX. The scheme of removal and recovery of N
oxides by adsorption was considered feasible for full-scale HNO~
plants.
151. Veal, D. J. (to Phillips Petr. Co.) Removal of nitric oxide from gas
streams. U.S. Pat 3 050 363 (Cl. 23-157) Aug. 21, 1962 (appl. July
28, 1958).
Silica gel with additions of IpO- or CrO« was found to be effective to
adsorb NO and NO0. The NO is oxidized to NO0 in the adsorbed state.
- 49 -
-------
~.kmud ~~ 'C~
CONSULTING DIVISION
152.
153.
154.
Anon. -1966. Process cleans up nitric tail gas.
July 4. 1966. p. 13.
Dr. C.1. Harding. Gainsville. Florida. and associates propose to
recover N oxides in 0.1-0.4% range in the tail gas of HN03 plants
by adsorption by zeolite.
Chem. Eng. News 44.
Anon. -1967. Removal of nitrogen oxides in tail gases by silica or
zeolites. Nitrogen No. 47. May-June 1967. p. 36.
Removal of nitrogen oxides (NO and NO ) from nitric acid plant exit-
gases has been investigated by Dr. Haraing and co-workers at the
University of Florida. Volumetric composition of the tail gases
studied was:
% Content
Nitrogen oxides (NO + N02) 0.1-0.4
Oxygen 3-4
Water 1
Nitrogen 95
It has not proved economic to recover these oxides of nitrogen and
to recycle them using absorption equipment. Nevertheless.' the NO +
N02 content is such that it constitutes a pollution problem. Dr.
Harding and his co-workers have been investigating--and the results
are reported to be successful-- an adsorption -desorption cycle of
these nitrogen oxides on silica or zeolites. In operation at one nitric
acid installation at 40oC. passage through a molecular sieve (in
preference to silica gel) reduced the tail gas content to 0.001% oxides
of nitrogen after 3 h. and then to O. 02% after 5h 20 min and to O. 8%
after 7 h. The zeolite is regenerated by injection of steam or air at
160oC. The nitrogen 0 xides are removed in a concentrated state and
are recycled. It is estimated that the zeolites will be able to be
employed for 2.000 cycles. but this is not yet definitely determined.
Application of the technique and process on a large scale is expected
to perm it an increase in production of 4 to 5 tons in a 300 tons p. d.
nitric acid unit.
Krasnyi. E. B.. Musin. T. G.. Piguzova. L.1., & Nikolina, V. Ya.
Adsorption and desorption of NO 2+ N 20 4 on synthetic acid resistant
zeolites. Khim. Prom. 42 (7). 523-4 (1966) (in Russian); C. A. 65.
16091 g (1966).
The isotherms of adsorption and desorption of mixed N02 and N 20 4
on 5 kinds of synthetic zeolite and technical silica gel were
determined. The adsorption capacity of the 4 of the 5 zeolites tested
was 3.7-9.0 times as great as that of silica gel.
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CONSULTING DIVISION
155.
Piguzova, L.r., Nikolina, V. Ya., Dubinin, M.M., & Shishakova, T.N.
Acid resistance of the synthetic zeolite erionite. Khim. Tekhnol.
Topliv i Masel.!Q (10), 32-34 (1965) (in Russian); C. A. 64, 6126 f (1966).
Synthetic erionite, (0. 5K2.0. O. 4Na2-0. AI20~. 6. 6Si02' 5. 5H20) was
treated with O. 006-3N HL! soIns. at 96-9"80"for 1 hr. The zeolite was
washed, and its capacity for H20 and N02 +N 04 was detd. At pH
~2. 1-.24, the zeolite structure is preserveJ. After treatment with
O. 1 N HCI, the capacity for H20 and the crystal lattice are essentially
unchanged. The substitution of Na+ and K+ with H+ does not destroy
the crystal lattice. The zeolite was studied in the H -form in the batch
adsorption-desorption ofN02+N2?4' At small concns., the adsorption
capacity of the zeolite is higIier than that of silica gel. After 8 cycles
of adsorption -desorption of N02 +N 204' no changes in the adsorption
properties and structure of the zeolite were found.
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156.
157.
Rizaev, N. U., Nabieva, Z. M., Saldadze, K. M., & Merenkov, K. V.
Adsorption of nitrogen oxides from exhaust gases by anion-exchange
agents. Uzb. Khim. Zh. .!Q (5) 70-72 (1966); C. A. 66, 49045 v (1967).
Ahion-exchange agents were used for the elimination of N oxides. With
the anion-exchange agents AN-23 and AN-25 in the 1st period, 60% of the N
oxides was adsorbed from the exhaust. The adsorption of N02 requires
its transformation to HN03 using moisture from the exchange agent. Of
3 moles N02' 2 moles are transformed to HNO~ and 1 to NO. The exhaust
gases studied contained 0.2 -0.4% N oxides. TIle level after passing tre
exchange agent was 0.08-0.16%. The desorption of the anion by 0.2-0.5 N
NaOH completely restores the adsorption capacity of the exchange agent.
AN-23 and AN-25 have a capacity of NO- adsorption which is 5-6 times
that of silica gel. The exchange agents ~ave no catalytic effects on the
oxidn. of NO to N02. The industrial samples of AN-23 and AN-25 were
washed free of Fe ions by 50/0 HC!. The excess CI- was removed with
H 0. The agents in the OH form were obtained by the equation
RCI + NaOH ~ ROH + NaCI. For expts. under dynamic conditions
batches of 10-15 g. were prepd. and allowed to stand with H20 for 3-4
hrs. for swelling. After that the exchange agents were poured into the
column together with H 0. The exchange agent AN-25 is the best
sorbent for sorption ana desorption of N oxides from exhaust gases.
Tuerkoelmez, S. Synthetic resin ion-exchanger for eliminating
obnoxious odors through exchange adsorption. Wasser Luft Betrieb
.!!. (11), 737-743; (12), 912-6 (1965) (in German); C. A. Ei, 12768 e
(1966).
For the purification of industrial waste gases, polymer resins can be
used as ion exchangers vb ich will adsorb nitrous gases, such as NO,
N02' N204 and N 03' This adsorption may be coupled with splitting
of certam molecutes by saponification, hydrolysis, or other reaction
mechanisms.
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CONSULTING DIVISION
158.
Pozin, M.E., Kopylev, B.A., Bel'chenko, G.V., &Obruba, P.
Cleaning gases of nitrogen oxides with the production of a fertilizer-
nitrated peat. Izv. Vysshikh Uchebn. Zavedenii, Khim. i Khim.
Tekhnol. ~ (2), 276-9 (1966); C. A. 65, 11287 f (1966).
In tests conducted in a 38 mm. diam. column, at 18-200, peat from
the Leningrad region (52% moisture) absorbed 60% of the N02
contained in air with 0.2% N02 over a 6-hr. period. The air was
passed through at O. 1 m. I sec. (2255 m~ I ton -hr. ). At O. 2 m. I sec. ,
(13550 m. 3 Iton-hr. ), N02 removal efficiency dropped from 45%
initially to 20% after 3 hrs. Removal efficiency was little affected by
vari.ation in initial NO concn. from O. 1 to 0.3%. Removal of N02
from air varied from g2% for an initial concn. of O. 1 %, to 20% for an
initial concn. of O. 3%, at a linear velocity of O. 1 m. I sec. (2255 m. 3 I
ton-hr.). Other samples of peat showed somewhat better sorption
characteristics. It is proposed that following sorption of N oxides,
the peat be treated with NR OR. It cppears possible thereby to
produce a pea t contg. 11 % ~ in this manner for use as a fertilizer.
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