EPA-R2-73-284
June 1973
Environmental Protection Technology Series
-------
EPA-R2-73-284
NITROGEN OXIDE
ABATEMENT TECHNOLOGY
IN JAPAN - 1973
by
Dr. Jumpei Ando and Mr. Heiichiro Tohata
Processes Research, Inc.
2900 Vernon Place
Cincinnati, Ohio 45219
Contract No. 68-02-0242, Task No. 11
Program Element No. 1A2013
EPA Task Officer: Frank T. Princiotta
Control Systems Laboratory
National Environmental Research Center
Research Triangle Park, North Carolina 27711
Prepared for
OFFICE OF RESEARCH AND MONITORING
U.S. ENVIRONMENTAL PROTECTION AGENCY
WASHINGTON, D.C. 20460
June 1973
V, Libre r-y
230 South Dearborn Street
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This report has been reviewed by the Environmental Protection Agency and
approved for publication. Approval does not signify that the contents
necessarily reflect the views and policies of the Agency, nor does
mention of trade names or commercial products constitute endorsement
or recommendation for use.
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NO Abatement Technology in Japan
(May 1973)
Jiunpei Ando
Heiichiro Tohata
Faculty of Science and. Engineering
Chuo University
, 3ruikyo-lai, Tolcjro
ill
-------
HO Abatement Technology in Japan
.X.
(May 1973)
Contents
General survey
1.1 Introduction
1.2 Environmental concentration
1.3 Environmental quality standard
1.4 Emission control
1.5 Development of control methods
1.6 Development of measurement methods
HO abatement by combustion control
X
2.1 Pilot plant tests on 110^ abatement
-jV.
2.2 Large-scale test on UO abatement (Kansp.i Electric Pover)
2.3 Low-ITO,, burner (iT-Tl)
Reduction t>rocesses for 110 abatement
x
3.1 Hitachi Shipbuilding process
3.? Other catalytic reduction processes
3.3 Reduction by sodium sulfite (CCIC-JECCO process)
Absorption processes
4.1 Sodium scrubbing (lujikasui process)
4.2 Alkali permanganate process (1101T process)
4.3 Sodium-potassium permanganate process (Nissan process)
4.4 Alkali scrubbing (Shinko process)
4.5 Sodium scrubbing (Sun Mec SV process)
4.6 Alkali scrubbing (Kyowa Kako process)
/1.7 Sodium scrubbing1 (iToe process)
/[.O Other alkali scrubbing processes
iv
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1 General survey
1.1 Introduction
Though the presence of nitrogen oxides (lIO ) in the atmosphere has "been
known for a good many years, it has assunea serious proportions in Japan
since July 1970> when many girl students at Itissho Senior Jligh School
(Tokyo) complained of eye irritabions, sore throats, coughs and other symptoms
suspected to "be due to photochemical saog. This was followed by similar
incidents in Tokyo and other cities, most of the incidents occurring between
late spring and autumn.
Table 1 shows the numbers of warnings issued for photochemical smog.
Warnings are issued when the hourly oxidants concentration becomes equal
to or greater than 0.15ppm. The Ministry of Health and Welfare and the
Tokyo Metropolitan Government formed their own special committees in 1970
to investigate these phenomena. The reports published by these committees
show that the phenomena vere caused by photochemical smog similar to that
experienced in Los Angeles, "u.G.A.
The detailed mechanism of oxidants formation has hitherto been unlmown,
but the consensus is that ITO . seems to play an important role.
.?•-
1.2 [Environmental concentration
The annual averages of environmental NO concentration are shown in Table 2.
The values listed in Table 2 were recalculated from previously published
data using the conversion coefficient 0.72 instead of 0.50 in the naphthyl-
ethylene diamine method, because JIS K 0104 (Measurement of NO ) is to be
revised to use a variable coefficient in accordance with the concentration.
The total amount of NO emitted in Japan is roughly estimated to be 2x10 t/year.
In December 1972, the Environment Agency presented the result of investigation
on the contribution of various sources to 1TO emission in the Tokyo Bay area,
i.e. Tokyo Metropolis, Kanagawa Prefecture, Chiba Prefecture, and Saitama
Prefecture (Fig. l). It is pointed out that the contribution of automobiles
would be more than 5Qffo in urban areas.
1.3 Environmental quality standard
In 1971» the Ministry of Health and Welfare organized a special committee
to prepare the scientific bases for air quality standards for NO,, and
oxidanis. Later, this work was taken over by the Central Council on Environ-
mental Pollution Control of the Environment Agency. On April 26, 1973»
-------
Council recommended to the Environment Agency the following standards.
HO 0.02ppm (daily average of one-hour values)
jC
Oxidants 0.06ppm (hourly average)
The standard for NO is to fee attained within 5 years. In Tokyo, Kawasaki
and other cities where environmental concentration is very high, however,
it is to be achieved within 8 years, and by 1978, the 110 r concentration
in 6(yfo of the total number of days in a year must be reduced to this
limit. The standard for oxidants is to be attained as soon as possible.
The standard proposed for NO _ is very severe compared with those in other
countries (e.g. 0.05 annual average in the U.S.A. and 0.04 daily average
in the U.S.S.K.), but considering the serious situation in Japan, it is
likely to meet with public approval. These standards are expected to be
set forth by the Cabinet in near future.
1.4 Emission control
In order to keep the levels of NO pollution under 0.02ppm, emissions both
from motor vehicles and stationary sources must be controlled.
1.4.1 Motor vehicle exhaust gas
In June 1970, the Ministry of Transportation published a 5 Year Plan for
a Basic Program for Automobile Exhaust (Table 3). Tha figures in Table 3»
except those for carbon monoxide, are not those set by law, but are
guidelines for future control. An automobile exhaust control act, analogous
to the Muskie Act in the U.S.A., is expected to be set forth in near future.
1.4.2 Waste gases from stationary sources
According to the Air Pollution Control Law (amended in 1970), an emission
standard for S09 is given by the following formula.
-3 °
q rr :: * 10 Ee~
where q - ruantity of S0_ in m'/hr at 0°C and 1 r.fc:a.
II - constants ranging from 2.92 to 22.2 according to the area
He - effective height of discharge in mebers
-------
K values are scheduled to be reduced to about 1/3 of the present values
within this year. We commonly call this type of control "K-value control".
Since HO and SO,, are similar pollutants in that both are emitted from
the combustion or fossil fuels and originate from a wide variety of
sources, control of R0^r from stationary sources would possibly follow the
same pattern as in theJ"case of S0_, i.e. "K-value control".
1.5 Development of control methods
There are two approaches to control; one is to reduce emission by
combustion modification, the other is to extract NO by some means from
the exhaust gases before allowing them to enter the" atmosphere.
1.5-1 Control methods for automobiles
Automobile engines that produce a minimum of pollutants Lave been developed
by such national research institutes as the Mechanical Engineering Laboratory
(Ministry of International Trade and Industry) and the Traffic Safety and
Nuisance Research Institute (Ministry of Transportation), as well as by
automobile manufacturers and universities. The most remarkable outcome
of these development efforts is the CVCC (combined vortex controlled
combustion) engine of Honda Motor Co. As for NO, emission, although the
engine does not satisfy the Muskie standard for 1^76, it is said to
be a matter of time that it will be reduced to that level, \fliile some
problems must be resolved before it can be put to practical use, this
contrivance should be highly evaluated.
Conversion catalysts for automobile exhaust gas have been developed by
the National Research Institute for Pollution and Resources, the Government
Chemical Research Institute, Tokyo (Mil), and by some engineering and
chemical companies. Some catalysts are already in practical use, but
the development of highly durable catalysts, especially those for red^^ction
of 5TQr, is yet to be accomplished.
1.5.2 Control methods for stationary sources
(l) Control by combustion modification
As shown in Chapter 2,electric power companies, national research institutes,
boiler makers, and some universities have developed combustion methods
designed to reduce HO, emission from boiler furnaces and other combustion
facilities. Use of a new type of burner, low-oxygen combustion, two-stage
combustion, recycling of flue gas etc. have been tried. Among these methods,
-------
the use of a new type of "burner, as shown in 2.3, seems to "be the most
promising for oil and gas burning, because considerable HO abatement
can be achieved at the lowest cost. Reduction ratio by this method,
however, is reported to be 50/° a"t "the highest, and for further abatement
it would be necessary to develop other methods. In cases where there is
extreme need for NO abatement, the use of pure oxygen for combustion would
have to be considered.
(2) Removal of HO from flue gases
JC
Countermeasures for large-scale boilers irould be along the line reviewed
in the preceding section, but there are many other stationary sources where
HO cannot be reduced in that way. Attempts to remove HOT from waste gases
have been directed chiefly toward purifying tail gas from nitric acid
plants and waste gas from pickling plants. The problem is how to apply these
techniques to flue gases from combustion facilities*,. Table 4 shows the
denitration processes under development in Japan. »^/
The denitration processes are classified into two groups; in one, HO is
absorbed by means of solutions, and in the other H0v is reduced to H£ by
means of a reducing gas under the presence of catalyst.
Since the main component of 1TO in flue ga,ses is HO which cannot be easily
absorbed or reacted with water or alkaline solutions, it is desirable that,
in the absorption process, HO be oxidized into H0_ with some oxidizing agent,
such as ClOp, HaClO^, or KMnO,, either in the gaseous or liquid phase.
Many processes described in Chapter 4 use oxidizing agents. The disadvantages
of the absorption processes are that they involve high cost for chemicals,
require disposal of waste solutions, and they seen unsuitable for large-scale
installations. Absorption processes have been developed by many engineering
and chenica.1 companies and some universities (including our laboratories).
The catalytic reduction of 1\0^ i" more promising for flue gas treatment
because the products, N2,H20, etc. ,are free from secondary pollution.
Problems, however, remain as to the durability and cost of catalysts, the
presence of oxygen, sulfur dioxide and steam, initial cost of processing
plant and so forth. Most of the processes treat nitric acid plant tail gas
using platinum catalyst developed in the U.S.A. by UOP, Oxy Catalyst and
Sngelhard. The Hitachi Shipbuilding process aims at the treatment of flue
gas (see J.l).
1.6 Development of measurement methods
Hitrogen oxides are usually measured colorimetrically with the reagents
naphthyl-ethylene diamine or phenol-disulfonic acid. Instruments for
analysis, such as those based on chemical luminescence of HO, infrared
-------
absorption, ultraviolet absorption and constant voltage electrolysis,
have been developed in recent years to meet the needs of the market.
Among them, the chemical luminescence analyzer (vacuum and normal pressure
type) is widely used because of precision and rapid response in measuring
HO concentrations. HO analyzers are manufactured by several makers,
representatives of which are Hitachi-Horiba, Shimazu, and Yanagimoto.
-------
Table 1 Numbers of warnings issued
1)
Prefecture
Saitama
Chiba
Tokyo
Kanagawa
Aichi
Osaka
i Hyogo
Total
Year
1971
1972
1971
1972
1970
1971
1972
1971
1972
1971
1972
1971
1972
1971
1972
1971
! 1972
Jan.-
March
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
April
0
1
0
1
0
0
2
0
1
0
0
; o
0
0
0
o
! 5
May
2
2
0
1
0
3
6
1
3
0
0
0
1
0
i i
6
i *4
June
3
5
7
6
0
9
5
5
8
0
1
0
4
i
! 3
26
| 32
July
8
1
4
4
5
8
5
3
6
1
2
0
3
2
4
26
25
Aug.
8
4
1
9
10
•»
1
0
1
2
3
2
5
27
Sept.
2
2
^_
3
•i
0
2
2
12
i
Oct.-
Dec.
0
2
0
6
0
0
0
0
8
Total
23
19
•"-«'
7
38
11
1
4
7
/
113
-------
Table 2 Annual average of environmental
concentration (ppm) '
City Monitoring station
National Air
Monitoring St.
Tokyo In front of Metropolitan
Government Office
Setagaya
Itabashi
Kasumigaseki
Osaka national Air
Monitoring St.
Nagoya National Air
Monitoring St.
Kawasaki national Air
Monitoring St.
Sapporo National Air
Monitoring St.
Matsue National Air
Monitoring St.
1969
0.040
0.040
0.042
0.014
0.012
0.035
0.022
1970
0.041
0.034
0.028
0.042
0.044
0.029
0.016
0.037
0.030
0.003
1971
0.046
0.044
0.033
0.040
0.040
0.027
0.014
0.031
0.028
0.003
-------
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Table A
Major denitration plants in Japan
2, 3)
Process developer
Catalytic reduction
Hitachi Shipbuilding
Japan Engelhard
Japan Gasoline-TJOP
Kobe Steel-Oxy Catalyst
Sumitomo Chemical
Mitsubishi Heavy Industries
Absorption(alkali scrubbing)
Fujikasui Engineering
Mitsubishi Metal, et al.
Nissan Engineering
Kobe Steel
Kyowa Kako
Sun-Oh Reinetsu-Matsushita
ITbe Industries
Mitsubishi Heavy Industries
Hishinaka Industries
Plants in operation
A pilot plant for flue gas ( 5,900scfia)
A test plant for flue gas from diesel engine
Two planes for nitric acid plant tail gas
Several plants for nitric acid plant tail
gas, etc.
Several plants for nitric acid plant tail
gas
Three plants for nitric acid plant tail gas
A pilot plant for flue gas(37,000scfm,
under construction)
A pilot plant for flue gas (lyOscfm)
A plant for nitric acid plant tail gas
(l,200scfni, under construction)
A plant for pickling waste gas(9,200scfm)
A pilot plant for pickling waste gas
Several plants for pickling waste gas
A commercial plant for nitric acid plant tail
gas (being designed)
Three plants for pickling waste gas
Several plants for pickling waste gas
-------
Refuse disposal
0.
Commercial & 2.
domestic
Petroleum industry
( including marketing)
Motor vehicles
Electricity
generation
Figure 1 Contribution of sources in Tokyo Bay
area ( 1970 )
10
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2 NO abatement by combustion control
IX!
2.1 Pilot plant tests on NO abatement '
Developer
Research organization Technical Laboratory, Central Research
Institute of Electric Power Industry
1229, Iwato, Komaemachi, Kitatama-Gun, Tokyo
Description Tests on NO abatement by mixing flue gas with air for
combustion were made witn a test furnace (heavy oil O.Jlbl/hr). Some of
the results are shown in Figures 2.1.1 and 2.1.2. Mixing the flue gas with
secondary air was found more effective for NO abatement than with whole air
for combustion (Figure 2.1.1). By mixing flue gas with secondary air in
an amount equal to 15$ of whole air, flame temperature was reduced by about
50°F, dust (fly ash) by about 35$, and NO by about 13$, when the oxygen
content of the combustion gas was 1$ (Figure 2.1.2).
11
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2.2 Large-scale test on NO abatement (Kansai Electric Power)
5)
Developer Kansai Electric Power Co.
3-51 Nakanoshima, Kita-ku, Osaka
Description Kansai Electric Power has improved a 450MW oil-fired boiler
at Himeji Power Station to abate NO in flue gas and has made tests
since July 1972. The boiler was originally manufactured by Combustion
Engineering Co., U.S.A. to produce l,450t/hr of steam at 1,0060F with
a pressure of J>,B1Q lb/square inch (superheater outlet). At an additional
cost of about ¥230 million ($880,000) improvements were made on the
boiler for the following purposes:
(l) Two-stage combustion by feeding a portion (maximum 10$) of air for
combustion through "NO ports" which have been newly provided above
the burners, so that tne air charged to the burners has been reduced
in order to lower the flame temperature.
(2) Eecycling of combustion gas. A portion of flue gas (maximum 10$)
is recycled and mixed with air for combustion in order to lower the
combustion rate.
The following results have been obtained with the improved boiler:
NO was abated with increasing amounts of air to "NO ports" and of flue
gas recycled, but excessive increase in the amounts resulted in unstable
combustion and overheating of superheater tubes. Acceptable amounts were
3$ for the air to the NO ports and 5$ for flue gas recycled. Optimum
operation data are shownbelow in comparison with those obtained with
the boiler before the improvement. NO was reduced from 370 to 190ppm by
the improvement. In consideration of the frequent variation of the operation
load of the boiler, the average NO concentration with the improved boiler
would be 220-230ppm. x
Capacity (MW)
NO in flue gas (ppm)
X
0- in flue gas ($)
Furnace temperature (°F)
Fuel consumption (bbl/hr)
Temperature of tube wall
of primary superheater (°F)
Before
improvement
450
370
1.7
2,840
660
980
After
improvement
450
190
2.0
2,640
672
986
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2.3 Low-NO burner (mi)5'
Developer Ishikawajima-Harima Heavy Industries Ltd. (iHl)
2-2-1, Otemachi, Chiyoda-ku, Tokyo
Description Various types of "burners which are effective in reducing NO
have been developed by IHI. Two examples are shown in Figure 2.J.I.
The basic principle of the burners is that the flame is divided to lower
the flame temperature. The results of tests on the burners with a furnace
(23ft in diameter, 46ft in length, 4-4t heavy oil/hr, excess air coefficient
1.2) are illustrated in Figure 2.3-2. NO concentrations were reduced to
30-50?o of those by the conventional burners.
State of development The type N-l burner has been recently applied to
a commercial oil-fired boiler of a power plant (84MW, with nine burners)
and has helped reduce NO concentration by about 50/£.
Jv.
Applicability For oil and gas burners.
Advantage NO can be reduced substantially by a slight modification of
the top part of burners.
Disadvantage No disadvantage. The method, however, may not be very
effective for coal burners.
16
-------
N-l
Pressure
atomizing
(Divided flame)
N-2
Steam
atomizing
(Divided flame)
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Figure 2.3.1 Shapes of divided flame
200
150
ft
ft
100
Pressure atomizing
(Ordinary burner)
Steam atomizing
(Ordinary burner)
N-l
50 L V ^ -^ N-2
25
02^6
Dust (Bacharach smoke number )
Figure 2.3.2 Effect of flame dividing on NO
and dust concentrations
-------
3 Reduction processes for NO abatement
JC
3.1 Hitachi Shipbuilding process '
Developer Hitachi Shipbuilding & Engineering Co.
1-47, Edobori, Nishi-ku, Osaka
Description Flue gas is divided into two portions and the larger portion is
heated to 1,560°F. The hot gas is used to heat manganese-iron sulfite
formed in the S0_ absorption step. By the heating, manganese ferrite,
absorbent for SO-, is regenerated and S0? is expelled which is used for
sulfuric acid production. The hot gas is then mixed with the rest of the
flue gas and led into a CO generator, where the gas is reacted with coke
to form CO and C0_. The gas containing CO is led into a dust eliminator
and then into a S0? absorber, where S0? is absorbed by granular manganese
ferrite to form the sulfite mentioned above. The desulfurized gas is then
led into a NO reducer, where WO is entirely reduced to K_ reacting with
CO in the presence of a cupric oxide catalyst. The treated gas is led
into a stack after passing through a heat exchanger. CO present in excess
in the gas reacts with water vapor to form C0_ and therefore is not contained
in the outlet gas. Neither NO nor NH, is detected in the outlet gas; SOp
concentration is less than lOppm.
Applicability Flue gas and other waste gases containing NO and SO
jC J\.
State of development The process was originally developed by Chevron Chemical,
U.S.A. and has been much improved by Hitachi. A pilot plant (5,900scfm)
at Sakai refinery, Kansai Oil Co. has started operation recently.
Advantages A very high removal ratio is attained for both NO and SO-.
No waste material other than the purified waste gas.
Pisadvantage High temperature is required.
10
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3.2 Other catalytic reduction processes
Japan Gasoline Co. has constructed two units to treat nitric acid plant
tail gas (NO l,000-6,000ppm, 0_ 2-4$) using HOP catalyst. Methane is _x
used as the reducing agent; reaction temperature ranges from 1,200 to 1,500°F. '
Kobe Steel Co. has built seven units to treat waste gases from nitric acid
and pickling plants. Catalyst developed by Oxy-Catalyst Inc. is used.
NO in inlet gas can be reduced from l,800ppm to GOppm by reduction with
methane at 900°^ under lOOpsig pressure.?)
Sumitomo Chemical Industries has built a unit to treat nitric acid plant tail
gas to reduce NO from 2,000-3,000ppm to lOOppm.2) A conventional catalytic,v
reduction process is used with some improvement on the heat recovery system. '
Mitsubishi Heavy Industries has constructed three units, each to treat
about 10,000scfm tail gas from nitric acid plants. NO can be reduced from
2,000ppm to 100-200ppm by reaction with H2, CH. or LPGXat about 930°F.2'
A test plant is in operation at Naoetsu Works, Mitsubishi Chemical Industries,
to treat diesel engine flue gas using a catalyst developed by Engelhard,
U.S.A.3)
Detailed information on these processes is not available yet.
Bench-scale tests have been carried out by Aichiken Kogyoshidojo (institute
for Industrial Development, Aichi Prefecture) on catalytic reduction as
well as on catalytic oxidation of NO .2/
Jx
20
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J.5 Reduction by sodium sulfite (CCIC-JECCO process)*'
Developer Catalyst and Chemical Industrial Co. Ltd. (CCIC)
2-6-2, Otemachi, Chiyoda-ku, Tokyo
Japan Engineering and Consulting Co. Ltd. (JECCO)
1-4, Ogawamachi, Kanda, Chiyoda-ku, Tokyo
Description Waste gas containing NO is treated with a sodium sulfite
solution to reduce NO to 1SL.
A. £-
O, + 2ND =
05 + 2N02 =
As the above reactions occur slowly with conventional scrubbers, the
rotary atomizer "Topca" invented by JECCO is used (Figure 3«3)«
The atomizer divides the waste gas into numerous small bubbles l-5mm
(1/25 - l/5in.) in diameter so that the reactions are promoted markedly.
Bench-scale tests have shown that NO concentration could be reduced from
3,000 to 50ppm« Sodium sulfite can oe obtained by waste-gas desulfurization
with a sodium hydroxide solution. It might be possible to remove SO- and
NO in waste gas simultaneously with a sodium hydroxide solution using the
rotary atomizer. A large rotary atomizer can treat up to about 3»000scfm gas.
Advantages Sodium sulfite, by-product from waste-gas desulfurization, is
used for NO removal. Simultaneous removal of S0? and NO may be possible
under certain conditions. NO is utilized for oxidation of sodium sulfite
which has been oxidized with air in many plants.
Disadvantage The process may not be suitable for treating a very large
amount of waste gas particularly when it contains much oxygen.
21
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4 Absorption processes
4-1 Sodium scrubbing (Pujikasui process) '
Developer Fujikasui Engineering Co. Ltd.
1-4-3, Higashigotanda, Shinagawa-ku, Tokyo
Description Gaseous C10_ is added to waste gas containing NO to oxidize
110 into NOp. The gas is then washed in a scrubber with a NaCfOp solution.
This treatment removes more than JCffo of NO in flue gas or more than 95$
of that in waste gas from pickling plants and tail gas from nitric acid
plants. The wastewater contains NaNO, and Nad. NaCl is recovered from
the solution, and subjected to electrolytic oxidation to produce CIO,,
and NaClOp. In order to treat the flue gas containing a considerable
amount of SOp, it is preferable to remove SOp prior to the above treatment.
SOp gas recovered from flue gas can be used for the production of ClOp gas.
Applicability Flue gas and other gases containing NO .
X
State of development Commercial plants are on stream to treat waste gas
(7,000-14,OOOscfm) from pickling plants and flue gas from a glass melting
furnace. A prototype plant designed for the treatment of boiler flue gas
(37,OOOscfm) is under construction to start operation in August 1973*
Advantage Operation is easy. Low running cost. SOp recovered from flue gas
can be used for the production of C10? gas.
Disadvantage Wastewater treatment is required.
Economics Investment cost ¥3-4 million($13,000) for 1,OOOscfm
Running cost about ¥4 (l-50) for l,000scf gas containing
260ppm N0_.
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4.2 Alkali permanganate process (MOW process) '
Developer Mitsubishi Metal Co.
1-5-2, Otemachi, Chiyoda-ku, Tokyo
Mitsubishi Chemical Machinery Mfg. (MKK)
2-6-2, Marunouchi, Chiyoda-ku, Tokyo
Nippon Chemical Industrial Co.
9-15-1, Kameido, Koto-ku, Tokyo
Description NO (and also S0_) in waste gas are absorbed in an alkaline
solution containing alkali permanganate or manganate, for example, a KOH
solution containing KMnO.. NO (and S0?) are absorbed and oxidized to
form alkali nitrate and sulfate while permanganate or manganate is reduced
to precipitate manganese dioxide which is filtered off.
KMnO. + NO = KNO, + Mn02
KMnO. + 2KOH + 3N02 = 3KNO, + Mn02 +
2KMnO . + 4KOH 2 2
Manganese dioxide is converted to alkali permanganate or manganate by a
conventional process. The alkali nitrate (and sulfate) solution obtained
is concentrated to produce a solid product which can be used for fertilizer
and other purposes.
State of development Under the leadership of Professor T. Okabe, Tohoku
University, the above-mentioned three companies have jointly developed the
process. A pilot plant (lyOscfm) has been under continuous operation since
November 1972 removing more than 90$ of NO and virtually all of S0_.
The 1TO concentration is kept below lOOppm. A larger pilot plant ( 3,000-6,000scfm)
is being designed.
Applicability For flue gas, waste gas from chemical plants, etc. To treat
a large amount of flue gas from high- sulfur fuel, SOp in the gas should be
subjected to desulfurization prior to the NO removal.
X
Advantages High removal ratio of NO and S0? is attained. No waste
material is produced.
Disadvantage Potassium hydroxide is not cheap. Production of potassium
permanganate from manganese dioxide is fairly expensive.
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4«3 Sodium-potassium permanganate process (Nissan process)
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Developer Nissan Engineering, Ltd.
5-2-8, Toshima, Kita-lcu, Tokyo
Description Waste gas containing HO is first washed in a scrubber with
a solution containing sodium hydroxide and the discharge from a second
scrubber to remove 70-80$ of NO . The gas is then treated in the second
scrubber with sodium hydroxide-potassium permanganate solution to oxidize
NO into NO,, which is aborbed by the alkaline solution. NO concentration
of the outlet gas is kept below lOOppm. A portion of the second scrubber
discharge which contains potassium manganate is subjected to electrolytic
oxidation to regenerate potassium permanganate. The discharge from the first
scrubber is sent to a wastewater treatment sj stem.
Applicability Tail gas from nitric acid plants and other gases containing
N0x.
State of development Tests with a pilot plant (90scfm) have led to the
construction of a commercial plant to treat l,200scfm tail gas from a nitric
acid plant.
Advantages A high removal rate of NO is attained. Operation is easy and is
flexible enough to deal with the changing amount and concentration of gases.
Disadvantage Wastewater treatment is required.
Cost The running cost is about ¥0.5(3.20/1,OOOscf gas containing 2,500ppm
NO which consists of nearly equal volume.s of NO and N09.
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4.4 Alkali scrubbing (Shinko process) '
Developer Kobe Steel Co. Ltd.
1-3-18 Wakihainacho, Fukiai-ku, Kobe
Description Waste gas containing NO is first washed in a scrubber with
a NaOH solution to remove about JOffo of NO . The gas is then led into a
reactor (a packed tower) containing granular alumina which has been sprayed
with a solution containing NaOH and NaC10,j and dried. In the reactor more
than 95^ of NO is removed forming NaNO,, ItfaCl and gaseous C10_. The 010^
gas is removed in another tower with a solution containing NaOH and Na_Sp6,
forming NaCl and Na_SO. which are discarded. The reacted absorbent in
the reactor is treated intermittently to remove Nad and NaNO, and to replace
NaOH and NaC102. 5
Applicability Waste gas from pickling plants.
State of development A commercial plant with a capacity for treating
9,200scfm gas from a pickling plant is on stream at Chofu North Works,
Kobe Steel Co.
Cost ¥22-34(8.50-13?!)/l,OOOscf gas containing NO l,200ppm at a maximum
and 230ppm on the average.
Advantage A high removal ratio is attained.
Disadvantage NaCIO,, is expensive.
29
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4-5 Sodium scrubbing (Sun Mec SV process)
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Developer Sun-Oh Reinetsu Co. Ltd.
18, Hatagocho, Kita-ku, Osaka
Matsushita Electronic Co.
1006, Oazakadoma, Kadomashi, Osaka
Description Waste gas with a high concentration of NO such as that from
pickling plants is first washed with water or a sodiumnydroxide solution to
reduce the 110 concentration to l,000-3,000ppm and then led into a reactor.
In the reactor, NO is converted to N0_ and to HNO, while passing through
a catalyst layer to which steam is fea. The gas containing HMO, is then
washed with a sodium hydroxide solution. The treatments reduce NO to
100-200ppm. X
Applicability Waste gas from metal dissolving and pickling plants and from
chemical plants.
State of development A total of 12-13 commercial plants with capacities
ranging from 350 to 3»500scfm are on stream.
Advantages Operation and maintenance are easy. Wastewater contains NaNO,
but virtually no NaNO_.
Disadvantage The process does not suit flue-gas treatment.
Economics Investment cost ¥25 million ($96,000) for 3,500scfm
Running cost ¥23(8.80)/l,OOOscf
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4.6 Alkali scrubbing (Kyowa, Kako process)
Developer Kyowa Kako Co. Ltd.
2-3, Maenooho, Itabashi-ku, Tokyo
Description Vaste gas from a pickling plant containing ITOv is first
washed in a scrubber with an alkaline solution (for example, sodium
hydroxide solution) to remove acidic components of the gas such as HC1
and HP, and also a portion of NO^ . The gas is then led into a second
scrubber and treated with an alkaline solution containing an oxidizing
agent such as hydrogen peroxide to remove most of 1TO . The gas is
finally washed in a third scrubber with alkali hydrogen sulfide or alkali
sulf ide .
10N02 + 4Na2S = 4NaNO + 4NaN02 + 43 + Ng
4N02 + 4NO + 51Ta2S = 6NaN02 + 3S + Eg
NO present in inlet gas to an extent of 3,000 to 4»000ppm is reduced to
below 50ppni by "the treatments when NO- concentration is nearly equal to
that of NO. When N0_ is more than NO, it is not necessary to use an
oxidizing agent in the second scrubber. When N0? is much less than NO,
it is not easy to reduce NO to below 50ppm even with an oxidizing agent.
X
The liquors from the first and the second scrubbers are sent to a
wastewater treatment system. That from the third scrubber is treated with
ferrous sulf ate to precipitate sulfide ion in the form of ferrous sulfide,
and then with calcium hydroxide to precipitate sulfate ion in the form of
gypsum. The slurry thus formed is filtered and the filtrate is sent to
a wastewater treatment system along with the liquors from the other
scrubbers.
Applicability V7aste gas from pickling and chemical plants.
State of development A unit to treat waste gas from a pickling plant at
300-400scfm is being designed.
Advantage A high NO removal ratio is attained.
X
Di sadvant age s Wastewater treatment is not simple. Sludge disposal is
required.
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4.7 Sodium scrubbing (Dbe process)
Developer Ube Industries Ltd.
2-1, Nagatacho, Chiyoda-ku, Tokyo
Description A small portion of nitric acid plant process gas containing
much HOp is added to tail gas which contains l,000-3,000ppm NO and has
a low NO .-/NO ratio in order to adjust the ratio to about 1. Tne mixed gas
is treated with a NaOH solution in an absorption tower equipped with special
dispersion elements. The treatments reduce WOr in the gas to below 200ppm.
NaNOp and NaUO, are recovered as by-products.
Applicability Uitric acid plant tail gas
State of development A commercial unit is to be built shortly.
Economics Investment cost for a 190t/day nitric acid plant is $280,000.
The operating cost varies with the type of the acid plant.
Advantage The process is simple. Low investment and running costs.
Disadvantage Produces considerable amounts of NaNOp and NaNO,, the demand
for which is limited.
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4.8 Other alkali scrubbing processes '
4.8.1 Mitsubishi Heavy Industries process
Waste gas from pickling plants is first washed with water to recover
nitric acid. The unreacted NO with some NO,, is then absorbed by an
alkaline solution to form nitrite solution. Three units ranging in
capacity from 14,000-24,OOOscfm have been built. NO concentration in
outlet gas ranges from 280 to 490pPm when the inlet concentration ranges
from 700-2,100ppm.
4.8.2 Hishinaka Industries process
NO in waste gas is oxidized to NO,, by passing through an activated
carbon layer and then treated witn a sodium hydroxide solution to
produce sodium nitrite and nitrate. Several units to treat pickling
waste gas are on stream.
References
l) Report of Air Quality Bureau, Environment Agency (1973)
2) Report of the Technical Comittee for NO , Public Utilities Bureau,
Ministry of International Trade and Industry (March 1973)
3) Private Communication
4) Report 72026, Technical Laboratory, Central Research Institute of
Electric Power Industry (Sept. 1972)
5) Report of Kansai Electric Power Co.
37
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BIBLIOGRAPHIC DATA
SHEET
1. Report No.
EPA-R2-73-284
3. Recipient's Accession No.
4. Title and Subtitle
Nitrogen Oxide Abatement Technology in Japan — 1973
5. Report Date
June 1973 •
6.
7. Author(s)
Dr. Jumoei Ando and Mr.
Heii chiro Tohata
8. Performing Organization Kept.
No.
9. Performing Organization Name and Address
Processes Research, Inc.
2900 Vernon Place
Cincinnati, Ohio 45219
10. Project/Task/Work Unit No.
Task No. 11
11. Contract/Grant No.
68-02-0242
12. Sponsoring Organization Name and Address
EPA, Office of Research and Development
NERC-RTP, Control Systems Laboratory
Research Triangle Park, North Carolina 27711
13. Type of Report & Period
Covered
Final
14.
15. Supplementary Notes
16. Abstracts The report documents development, demonstration, and control now in
progress in Japan on Japanese processes pertaining to NOx abatement from flue
gases. It includes Japanese environmental emission and control standards, and
measurement methods. It presents process descriptions, states of development,
advantages, disadvantages, economics, and flow sheets for 13 processes (including
combustion control, reduction, and absorption) for NOx abatement f rom waste
gases. A new type of burner seems most promising for combustion modification;
catalytic reduction seems most promising for NOx removal from flue gases. NOx
source contributions in the Tokyo Bay area are: 39% motor vehicles, 22% electricity
generation, 31% industry, and 8 % other sources.
17. Key Words and Document Analysis. 17o. Descriptors
Air Pollution
Nitrogen Oxides
Combustion
Abatement
Development
Control
Flue Gases
Standards
Measurement
17b. Identifiers/Open-Ended Terms
Air Pollution Control
Stationary Sources
Japan
Japanese Processes
Emission Standards
Reviews
Economics
Reduction (Chemistry)
Burners
Catalysis
Motor Vehicles
Electric Generators
Control Standards
Measurement Methods
Process Descriptions
Tokyo Bay Area
17c. COSATI Field/Group 13B, 14A , 21B
18. Availability Statement
Unlimited
19. Security Class (This
Report)
UNCLASSIFIED
20. Security Class (This
Page
UNCLASSIFIED
21. No. of Pages
37
22. Price
FORM NTIS-35 (REV. 3-72)
USCOMM-DC MB52-P73
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Rapier: V, Ml..-.' -•
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