APTD-1066
January 1972
RECENT DEVELOPMENTS
IN
DESULFURIZATION
OF
FUEL OIL AND WASTE GAS
IN
JAPAN (1972)
PREPARED FOR
U.S. ENVIRONMENTAL PROTECTION AGENCY
National
Environmental
Research
Center • RTP
Control
Systems
Division
PREPARED BY
DR. JUMPEI AN DO
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Recent Developments in Desulturization of Fuel Oil
and Waste Gas in Japan (1972)
Jump.i Ando
Contract No. CPA-70-1 (Task 16)
Faculfy of Science and Engineering
Chuo University
Kasuga, Bunkyo-ku, Tokyo
-------
'oreword
Desu1furiza tion of fuel oil and staok gas is assuming growing
importance in Japan in parallel to the mounting imports of high-sulfur
crude oil.
Japan today may well be most advanced in the world in the
practice or desu1furization.
For 19 commercial plants for hydrodesu1-
furization of heavy oil and many commercial plants for stack-gas desu1-
fu~ization are a1rea~ in operation in Japan, where various new processes
including gasification desulfurization of fuel oil are being developed.
A salient feature of desu1furization efforts in Japan is that they
are oriented toward processes that yield salable by-products such as
sulfur, sulfuric acid, sodium sulfite and high-quality gypsum.
This is
because Japan is subject to limitations in domestic supply of sulfur and
its compounds as well as in land space available for disposal of useless
by-products.
As desulfurization is making rapid progress, however, it will
not be long before supply of the by-products runs far ahead of demand.
A flue-gas desulfurization plant using a wet-lime process is under construc-
tiun as the first large plant which does not produce salable by-products.
The present paper describes the reoent developments in desu1furi-
zation in Japan up to December 1971.
January 1972
Dr. Jumpei Ando, Professor
Faculty of Science and Engineering
Chuo University, -,
Kasuga, BUnkyo-ku, Tokyo
. -
-------
Recent Developments in Desulfurizat10n of Fuel Oil
and Waste Gas in Japan (1972)
Contents
1
Emission and regulation of S02 in Japan
1.1 Supply of energy
1.2 Oil and its sulfur content
1.3 Heavy oil and sulfur
1.4 Other fuels
1.5 Policy for sulfur abatement
1.6 Environmental standard
1. 7 Emissi on standard
2 Outline of recent developments in desulfurizatiun
2.1 ~drodesulfurization of heavy oil
2. 2 WA~tt:-gas rlesu1furizaticn
2.3 Government policy for development of desu1furization techno1ozy
3 Desulfurization of heavy 011
3.1 UOP-RCD IGomax process fer toppe'!-crude hydrodesulfurizaticn
3.2 Gulf process for topped-crude hydrodesu1furizaticn
3.3 MDS process for topped-crude hydrodesulfurization
3.4 Other tests on topped-crude hydrodesulfurizati~n
3.5 Vacuum ~Qs-oi1 hydrodesulfurizaticn
3.6 Production of fuel gas by gasification desulfurization of heavy
oi1 (Ube process)
3.7 Power generation by sasification desu1furization of heavy oil
(Japan Gasoline process)
4 WAste-cras desu1furization by wet process
4.1 Kureha process (sodium scrubbing)
4.2 Showa Denko process (ammonia or sodium scrubbing)
4.3 ~ahco-Tsukishima process (sodium scrubbing)
4.4 Kanacrawa PIL process (Jinkoshi process)
4.5 Oji process (sodium scrubbing)
-------
~.6 Wellman-Lord process (MAX)
4.7 Wellman-Lord pro~ess (SCE)
.1. 0 MHsl1bishi-J~C process (lime-8'Ypsum
4.9 Chlyoda 'rh0rl"w~hbred 101 prc1cess
4.10 Kawasaki maGnesium process
4.11 Grillo process
4.12 Chemico process (lime scrubbinc and magnesium scrubbinC)
4.13 Takahax process (il2~ recovery)
4.14 Other wet processes
process)
W ~st~c:as desu.lfllrizatio~! ~ry process
5.1 Mitsubishi DAP-~ID process
5.2 Hitachi activated carbon process
'j
(
).3
Surnitomo activated carbon process
NRlPR active s0dium carbonate process
Shell prc1cess (Cupric oxide process)
5.4
5.5
5.6
Other ~ry processes
&onomic aspec ts
6.1
~upply, ~emand, and priQe of sulfur and its compounds
Gost of hy~rodesulfurization
Cost of flue gas desulfurizatiC'n
lH>;;jj) :
v'-l:
1 :
LLwV:
Bioi:
~.2
r;.3
6.4
Cost comparison of oil desulfurization and flue-eas desulfurization
Abbrevia ti ,ms
Barrels per stream day Nm3/hr:
Kiloliters SCF:
Normal cubic mete"!"s per hour
Stand~rd cubic feet
Liters
Liquid hourly
velocity
Megawatts
Sec,.nds
'.
sec. :
t
or tons:
Netric tens
space
TG:
Topped cru1e
Vacuum gas oil
VGO:
¥I
Yen
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1 Emission and regulation of S02 in Japan
1.1 Supply of energy
Along with the rapid industrial advances in Japan demand for energy here
i8 mounting steadily. Supply of energy doubled in the past five years
(Table 1.1); most of the increase was accounted for by imported oil.
In 1970, 71% of the total energy supply depended upon petroleum while
in 1965 the dependence was 5~. atdraulic power and coal are not increas-
ing 80 rapidly. Even though atomic power may eventually supplant petroleum,
demand for petroleum is thought to keep growing for some time to come.
Per-capita energy consumption in Japan was one-fifth that in the United
States in 1965, one-fourth in 1968, and most likely close to one-third
in 1970. Japan's energy consumption is expected to continue a fairly
rapid growth(Tab1es 1.1, 1.2).
Table 1.1 Supply of primary energy (1010kca1)1, 2)
1960 1965 1970 1975
Electrio power
~draulic 14,328 18,722 19,620 21,200
Atomic 0 9 1,122 10.200
Coal
Domestic 32,229 31,637 25,209 22,600
Imported 6,702 13,580 39,224 62,700
Oil
Domestic 587 740 847 800
Imported 34,782 95,964 218,914 342,500
Natural gas
Domestic 927 2,008 2,676 2,900
Imported ,( LNG) 0 0 1,298 4, 500
Other energy sources 4,194 2,924 1,918 1, 700
Total 93,749 165,614 310,468 470,400
(/)
-------
Table 1.2 Total oapaoity of electric power plants (MW)l)
1960 1965 1910 1980
Hydraulic 12,618 16,215 20,405 32,900
Fossil fuel 10,946 24,102 46,931 91,200
Atomic 0 13 1,336 21,000
Total 2},634 40,990 68,312 151,100
1.2 Oil and its sulfur content
With very little domestic production of petroleum, Japan depends on
overseas supplies for more than 99% of its oil consumpti n. Petroleum
is imported here mostly in the form of crude oil and partly fuel oil.
About 8~ of the crude oil comes from the Middle East (Table I.}).
Middle East crude is rich in sulfur; Khafji crude, especially, contains
8S much as 2.6% sulfur, as against the average 1.6% for all imported
crudes. The total amount of sulfur present in imported crude and fuel
oil exceeded 3 million tons in 1910 (Table 1.4).
Table 1. 3 Crude oil imports and their s"urces )
(in millions of kiloliters)l
District
1222
71.4
6.2
2.9
1.1
81.6
Middle Ea st
Far East
u. S. S. R.
Other districts
Total
1961
114. 1
8.3
1.1
1.0
125.1
1969
152.5
19.5
0.6
2.0
114.6
1910
173.3
27.5
0.6
3.5
204.9
According to the Government's petroleum supply plan for 1911 through 1915,
demand for oil is expected to reach approximately 230 million kiloliters
in 1911 and 390 million kiloliters in 1915. Even though efforts have
been made to import low~su1fur oil, the amount of sulfur seems to grow
steadily (Table 1.4).
(2)
-------
Table 1.4 Estimated imports of oils and their sulfur content})
Import of Average Sulfur from Import of Sulfur from Total
orude oil sulfur content crude oil fuel oil fuel oil sulfur
~million kl1 (%) _(1,000t )- ~million kl)_(l,OOOt} (l,ooot)
1910 205 1.56 2,151 24 }24 3,081
1911 232 1.46 2,912 2} }02 3,214
1912 244 1. 36 2,853 39 5}2 3,385
1913 213 1. 36 3,194 44 599 3,193
(1. 26) (2,960) (3,559)
1914 302 1. 36 3,536 51 682 4,217
(1.16) (3,016) (3,698)
1975 332 1. 36 3,884 55 730 4,614
(1. 06) (3,027) (3,151)
I.} Heavy oil and sulfur
In Japan, most of crude oil is treated by topping (atmospheric distilla-
tion). The residual oil from topping is known as "heavy oil" and is used
for fuel. From 100 parts crude, 55 parts heavy oil is obtained on the
average. Approxima tely 9~ of the sulfur in crude remains in heavy oil.
Heavy oil from Khafji crude has a sulfur oontent as high as 4% (Figure 1.1).
Crude oil
Gasoline,etc. ~5
100 (5=2.5%)
Topping
Heavy oil 55
(5=4.0%)
Figure 1.1
Rough material balance in topping of
Khafji crude
(t)
-------
ConsUJDpti"n of heavy oil amounted to approximately 50 million kiloliters
in 1965 and to 110 million kiloliters in 1970 (Table 1.5). In 1970 about
one-fourth of the heavy oil was subjected to hydrodesu1furization giving
nearly 300,000 tons of sulfur as by-product. Still 2.5 million tons of
sulfur in heavy oil burned produced 5 million tons of S02' which con-
stituted the chief source of S02 emission. About a third of heavy oil
was burned in eleotric power stations and the rest in other plants and
buildings.
Table 1. 5 Consumption of heavy oil (in thousands of ki101iters)1)
Use 1965 1967 1969 1970
Electric power 11 , 862 18,963 29,809 34,745
Chemical industry 5,762 7,291 8,529 12,657
Steel industry 5,256 7,109 9 , 261 11 ,445
Ceramio industry 6,017 8,051 9,716 10,352
Other uses 20,933 28,632 39,794 44,615
Total 49,830 10,052 97, 115 113,814
1.4 Other fuels
Domestio production of coal is decreasing because coal is more expensive
than oil (Table 1.6). About a half of domestic coal has been burned in
power plants (Table 1.7). The coal mined in Japan contains about 1%
sulfur on the average. Imported coal, whioh has been increasing, is
used to produce coke for the iron industry. The S02 problem is much
less with coal than with heavy oil.
Table 1. 6 Production and import of coal of tons)l)
(in thousands
1965 1961 1969 1970
Production 55,642 51,512 46,389 40,851
Import 17,637 27,213 43,260 50,941
( 4>
-------
'- .
Table 1.7 Consumption of fuels for electric powerl)
1965 1967 1969 1970
Heavy oil (l,OOOkl) 11,862 18, 96 ~ 29,809 34,745
Crude 011 (l,OOOkl) 719 2,192 3,939 7,251
Coal (l,OOOt) 20,909 26,349 24, 363 18,826
Natural gBs(million Nm}) 39 5 4 60
Japan produces little natural gas (Table 1.8). Liquefied natural gas (LNG)
~s been imported since 1969 as a means of alleviating the S02 problem
(~ables 1.8, 1.7). Two LNG tankers, each with a capacity of 30,000 tons,
are in service between Alaska and Japan. Four more similar tankers are
under construction to bring LNG from Brunei. Several power plants in
biF, cities have started to use LNG, a1thol~h it is much more expensive
than oil (Table 6.4).
Table 1. 8
Production and import of natural gaSl)
Production(million Nm3)
Import (LNG, 1,000t)
1965
2,108
°
1967
2,328
°
1969
2,721
182
1970
2,808
976
1.5 Policy for sulfur abatement
A report published by the Comittee for Sulfur Dimishing Policy, Ministry
of International Trade and Industry, indicates that to decrease the S02
level to the environmental standard by 1978 sulfur in fuel has to be
diminished as shown in Table 1.9.
Table 1. 9
Fuel consumption and S02 level in 1967
and need for low-sulfur fuel to attain
envir- nmenta1 standard by 19784)
Overpopulated
area
Polluted
area
Precaution
area
Prevention
area
1967
Amount(10,000k1)
Average sulfur content
(%)
Po11ution(S02 ppm)
2,297
2.41
1,307
2.51
3,064
2.45
0.}8
0.24
l..t )
-------
1973
Aroount(10,Oook1) 4, 360 2,830 2,750
Average sulfur content 0.90 1.}0 1.45
(%)
Po11ution(S02 ppm) 0.27 0.20 0.20
1978
Amo1lI1 t (10, 000k1) 5,500 4 ,600 5,400
Average sulfur content 0.55 0.80 1.00
(%)
Po11ution(S02 ppm) 0.20 0.20 0.20
9,940
1.20
15,500
0.80
1.
The environmental standard requires that SOL concentration should
be below 0.2ppm for more than 99% of total !hours (1.6).
2.
Fuel includes crude oil for fuel, LNG, etc.
3.
Effect of desulfurizahon is included in the sulfur cnntent.
Judging from th0 crude oil import situation not much low-sulfur oil can
bo expected. To attain the 502 level indicated in the table, 43.4
million kiloliters (275 million barrels) of heavy oil has to be subjected
(.0 hydrodesu1furiza tion to decrease the sulfur content to 1. 35% on the
Average in addition to flue-gas desu1furization of 1. 7 million kiloliters
in 1973 (Table 1.10).
Table 1.10
1973 target sulfur content in fuel and means
of achieving target4)
fieri/. "7 ~ il
Low-sulflll'
Medium-sulfur
High-sulfur
Residual hydrodesulfurization
Flue-gas desu1furization
Import of heavy oil
Class 0, including
crude oil for fuel
Class A
Imported LNG
Total for fuel
Amount (1, OOOkl)
Average sulfur content(%)
27,500
51,800
19,800
43 , 400
1,700
30,200 1.00
2,000 1. 50
1,400
177,800 1.10
(i)
0.55
2.35
3.15
1. 35
0.75
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1.6 Environmental standard
The environmental standard for 502 has been set out as follows:
1) The hourly average 502 concentration should not exceed 0.2ppm in not
less than 9~~ of the total humber of hours in a given year.
2) The daily average 502 concentration should not exceed 0.05ppm in not
lesa than 10% of the total number of days in a given year.
j) The hourly average 502 concentration should not exceed 0.05ppm in
not less than 88% of the total number of hours in a given year.
4) The yearly average of hourly conoentrationsshould not exceed D.05ppm.
The yearly averages in the moat polluted districts in major cities are
shown in Table 1.11. In many of the districts, 502 concentration still
exceeds the standard although the concentration in 1910 is lower than
in 1969.
Table 1.11 Yearly average concentration of 502
1961 1968 1969 1910
Sapporo 0.040 0.040 0.049 0.049
Tokyo 0.014 0.080 0.085 0.065
Yokohama 0.064 0.060 0.060 0.058
Kawasaki 0.10 0.084 0.015. 0.062
Nagoya 0.051 0.054 0.056 0.052
Yokkalchi 0.081 0.052 0.051 0.045
~oto 0.053 0.051 . 0.053 0.052
Osaka 0.091 0.082 0.095 0.090
Kobp. 0.038 0.051 0.049 0.048
Omuta 0.052 0.055 0.051 0.052
1.1 Emission standard
The emission standard is given by the following equation:
q = k x 10-3He2
q:
amount of sulfur oxide, Nm3/hr
the value shown in Table 1.12
effective height of stack (meters)
k:
He:
(7 )
-------
Table 1.12 The values of k
~
1
2
k
11. 7
12.8
14.0
15.8
17.5
20.4
23.3
26.3
3
4
5
6
7
8
Districts
Tokyo, Osaka, Yokkaichi, etc.
Kashima, Chiba, Kurashiki, etc.
Muroran, Nagoya, Himeji, etc.
Sapporo, ~oto, Hatogaya, etc.
Hitachi, Ni1hama, Omuta, etc.
Niigata, Onoda, Ube, etc.
Xure, Tokuyama, Nanyo, etc.
Hachinoe, Kamaishi, Nobeoka, etc.
A special k value 5.26 has been applied recently to areas which are
already heavily polluted such as the city areas of Tokyo and Osaka, and
industrial areas such as Yokkaichi and Kawasaki. Electric power plants
have built tall stacks as high as 200 meters in an effort to meet the
emission standard.
In additirn to these national standards, there are regulaticns on
sulfur oontent of oil enforced in speoific areas. For example, an
ordinanoe issued by the Governor of Tokyo is shown in Table 1.1'.
Table 1.13 Ordinance on sulfur content of fuel oil (Tokyo)
Plants Buildings
Consumption of 011 Maximum S Consumption of Maximum S
(l:iter/day) (%) oil (li'ter!day) (%)
C1 ty area 1,000 to 4,000 1.3 (1. 5)* 300 to 10,000 1.0 (1. 3)*
4,000 to 10,000 1.0 (1.3) over 10,000 0.5(1.0)
over 10,000 0.5 (1.3)
Other areas 1,000 to 10,000 1.3 (1.7) 300 to 10,000 1.0 (1.3)
over 10,000 1.0 (1.3) over 10,000 0.5 (1.0)
* Parenthesized figures are for existing plants and buildings.
Other figures are for those to. be newly built.
on
-------
As public opinion on air pollution is becoming more and more critical,
both the k values and the 502 concentration in the environmental standard
are to be reduced by about 4~. By this change the sulfUr abatement
policy would be revised to require larger amounts of imported low-sulfur
fuels, more desulfUrization, and higher stacks.
{7J
-------
2 Outline of recent developments in desu1furization
2.1 HYdrodesu1furization of heavy oil
Many hydrodesulfurization plants have been built since 1961 in various
districts of Japan (Table 2.1). Three of them use the topped-crude
desulfurization process (or the atmospheric residual desulfurization
process which is often referred to as the direct process) and others the
vacuum gas-oil desulfurization process (indirect process). By the direct
process,up to about 15% of sulfur in oil can be removed (Figure 2.1) but
the life of catalyst is a big problem.
Heavy oil 100
Sulfur, naphtha, etc. 10
( S = 4.0%)
Desulfurized oil 90
( S = 1.0%)
Desulfurization
Figure 2.1 Rough material balance in topped-crude
hydrodesulfurization (direct process)
By the indirect process, heavy oil is first distilled under vacuum. The
distillate is desulfurized down to O.~ sulfur without any significant
technical tr.: uble (Figure 2.2). The desulfurized oil is normally mixed
with the residue of the vacuum distillation to be used as fuel oil. The
product contains 2.4% sulfur when heavy oil with 4.0.% sulfur is treated.
Therefore, the removal is not satisfactory to meet the severe require-
ments for 502 control.
Vo)
-------
Deeulfurization
Sulfur, naphtha, etc. 6
Heavy oil 100
( 5 = 4.0%)
Vacuum gas oil
62 (5 = 2.~)
Desulfurized oil
56 ( s = 0.2%)
Residual oil 38
Vacuum
distillation
94(5=2.4%)
Figure 2.2
Hough material balance in vacuum gas-oil hydrodesulfuri-
zation ( indirect process)
Table 2.1
Refiner Plant site Process Completed
IdomitAu Chiba UOP (T)* 1961 40,000 240
Koean
fuj1 Oil Sodegaura CRC(V)** 1968 23,000 90
Toa Nenryo Wnkayama ERE(V} 1968 25,000 162
Dsikyo Oil Umaokoshi Gulf (V) 1969 11,500 100
Nippon Negishi CRC (V) 1969 40,000 113
011
Shows Oil Kawasaki Shell (V) 1969 16,000 60
Kyushu Oil Oita Shell (V) 1969 14,000 50
Mitsubishi Mizushima UOP (V) 1969 30,000 90
Oil
Maruzen Chiba Union(V} 1969 35,000 150
Oil
Seibu Oil Yamaguchi Shell (V) 1969 4,000 25
Nippon Mizushima Gulf (V) 1970 27,160 150
Mining
Koa Oil Marifu CRC (V) 1910 8,000 35
(II )
-------
General Sakai ERE (V) 1910 '1,000 66
Oil
Ka shima Kashima UOP (T) 1910 45,000 240
Oil
Idemitsu Himeji UOP (T) 1970 40,000 200
Kosan
Daikyo Oil Umaokoshi Gulf (V) 1970 17,500 70
Kansai Oil Sakai ERE (V) 1971 20,000 80
Koa Oil Osaka CRC (V) 1971 12,000 50
Toa Nenryo Kawasaki ERE (V) 1971 51,000 200
Subtotal 496,260 2,231
Nippon Negishi CRC (V) 1972 28,000
Oil
Idemiteu Rime j i Gulf (T) 1972 40,000
Kosan
Kyokuto Chiba UOP (V) 1972 60,000
Petroleum
Ka shima Kashima (V) 1972 11,000
Oil
Asia Oil Sakaide (V) 1972 50,000
Nippon Muroran C RC (V) 1973 40,000
011'
Toa Oil Nagoya (V) 1973 30,000
Subtotal 259,000
Total 755,260
* Topped-crude desulfurization (direct process)
** Vacuum gas-oil desulfurization (indirect process)
2. 2 \V~te.-gas desulfurization
Large-scale desulfurization plants are listed in Table 2.2. The plants
No.1 through No.6 are commercial plants designed to produce sodium
sulfite solutions for paper industry. Others produce sulfuric acid, gypsum,
(/ 2)
-------
Table 2.;:' Major plants for afA.~gas desulfur:ization
~ Developer User Plant site Absorbent Product Gas treated 1.OOOBm3 k Comp1e1r:iOn
1 Kureha Chemical Kureba Chemi,,~ 1 Nishiki HaOH Na2503 600a 1968
2 Oji Paper Oji Paper Ka S1J88i HaOK Na2503 8ooa,b 1969-1971
, Show Denko Show Denko Kawasaki BaOH Na2S0, 150a 1970
4 Showa Danko Ajinomoto Kawasaki HaOH Na2SO, 270a 1971
5 Showa Danko Nippon PhosPhoric Sodegaura NaOH Na2S03 80c 1971
6 Bahc o-Tsuki shima DB i shows Yoshinaga BaOH Na2503 335b 1971
7 Wellman-Lord Nihon Synthetlo Chiba Ba2SO, S02(H2SO 4) 2fX)a 1971
Rubber
8 Wellman-Lord Toa Nenryo Kawasaki Na2S0, S02 60d 1971
9 Mi tsubishi Nippon Kobo Koys su Ca(0i1)2 gypsum 60c 1968
H.I.
10 Mi tsubishi Kansai Eleo trio !mags saki Ca(OH)2 gypsum looa 1972
H. I.
11 Japan Eng. Co. Tomakomai Chem. Tomakomai Ca (OH)2 gypsum 528 1912
12 Sumitomo Kansai Electric Sakai Carbon S02(H2S04) 175a 1911
13 Hi tsubishi Chubu Electric Yokkaichi Mn0x (NH4)2S04 326a 1912
H.I.
14 Hi tachi Ltd. Tokyo Elec tric Ka shima Carbon H2SO 4 (gypsum) 420a 1912
15 Jinkoshi Nippon Kokan Keihin NH40H (NH4)S04 l50e 1912
16 Chiyoda C. E. Nippon Minil1P.; Mizushima dil. H2SO 4 gypsum 70d 1912
17 Chemic 0 Hi tsui Aluminum Omuta Ca(OH)2 CaS03 5l2f 1912
18 Shell Showa Yokkaiohi Yokkaichi CuO S02 120a 1913
Sekiyu
-::- as Oil-burning boiler b: Kraft recovery boiler c: Sulfuric acid plant
<-
- d: Claus furnace es Sintering plant f: Coal-burning boiler
-------
ammonium sulfate, etc. In Japan, it is necessary to obtain usable by-
produots by desulfurization because there 1s not enough land for waste dis-
posal. Several othor processes are being tested on a smaller scale
BS will be deeoribed later.
2.3 Government polioy for development of desulfurization technology
National research projects for desulfurization
The £gency of Industrial Science and Technology, MITI, has set forth the
followinr, guideline for desulfurizati n: Large electric power ~lants
should perform flue-gas desulfurization by which more than ~ of 502
can be removed. Other consumers of heavy oil, such as various plants
and building!.'!, should use low-sulfur oil obtained by direct hydrodesulfuri-
zation. Based on this guideline, the Agency has awarded contracts to
several groups for the development of processes for flue-gas desulfuri-
zation and heavy-oil desulfurization (Topped-crude hydrodesulfurization)
as shown in Tables 2.3 and 2.4.
Table 2.}
Year
-
1966
1967
1968
1969
1970
1971
Development of desulfurization processes under
contract of Agenoy of Industrial Science and Technology
Flue-gas desulfurization
Topped-crude
hydrodesu1furization
Mltsubishi
-'manganese)
Pilot
plant
Pl'ototn8
lant
Hitachi
(carbon)-
Pilot
plant
Research
on
Prototype
plant
catalyst
Pilot
plant
Table 2.4
I!!.!
1966
1967
1968
1969
1970
1971
Expenditures of the Agency of Industrial Science and
Technology for the contracts(millions of yen)
Flue-gas desulfurization Topped-crude hydrodesulfurization Total
325
455
547
45
o
o
o
100
240
428
305
163
325
555
787
473
305
163
(i if- )
-------
(1)
Contraots for flue-gas desulfUrization
Contraots were awarded to Mitsubishi Heavy Industries (active manganese
prooess, DAP-Mn process) for the period 1966 through 1968 and also to
Hitaohi Ltd. (activated carbon process) for 1966 through 1969 to build
pilot plants followed by prototype plants. Each prototype plant was .
capable of treating l50,OOONm3/hr gas from oil-fired power plants(50MW
equivalent).
(2)
Contraots for topped-crude hydrodesulfurization
A contraot was awarded to a research group of ten oil refiners for the
1961-1969 period to develop a catalist for deaulfurization. Under another
contract for 1969 through 1911 a new suspended-bed reactor with a capacity
of 500BPSD has been built and tested by Nippon Oil.
Researches on desulfurization have been made also by institutes which
belong to the Agency. Government Research Institute, Tokyo, is working
on hydrodesulfurization. National Research Institute of Pollution and
Resources (former Resources Research Institute) has been working on flue-
gas desulfurization by the sodium carbonate process and also on catalysts
for hydrodesulfurization.
Under the oontracts, all expenses for development are supplied by the
Government. After completion of the tests under contract, each organi-
zation makes further development at their own expense.
Projected new system for the development of pollution control technology
MITI plans to set up a new program for the development of "closed systems"
which cause no emission of pollutants, and is trying to get budget allo-
cations for the program. Under this program MITI has tentatively selected
three projects for important closed systems deemed worth developing.
The three are 88 follows.
(1) Gasification desulfurization (Ube process, which will be described
in 3.6). (2) Production of caustic soda by electrolysis without using
mercury. (3) Production of pulp and paper without giving any trouble-
some muddy material.
Each of the projects is expected to require 1 to 2 billion yen to build
prototype test plants. MITI is to supply 1~ of the total expense subject
to budget appropriations.
(j.t )
-------
3
Desulfurization of heavy oil
3.1
UOP-RCD Iso,max process for topped-crude hydrodesulfurization
Description Two commercial-scale plants using the UOP-RCD process are
in operation--one at Chiba and the other at Kashima (Table 2.1) The
Chiba plant, owned by Idemitsu Kosan, was completed in 1967 as the first
commercial plant in the world for topped-orude desulfurization. The
Kashima plant was completed in 1970.
The flow sheet of the process is shown in Figure 3.1. Heavy oil is
preheated, mixed with hydrogen, reheated, and charged into the two
reactors in series. The reactors contain molybdenum-cobalt catalyst in
fixed beds. The reaction is carried out at 380 to 430°C temperature under
140 to 160kg/om2 pressure. The liquid hourly space velocity (LHSV) is
maintained at about 1. The discharge from the reactors is sent to the hot
separator where hydrogen-rich gas is separated from liquid. The liquid
is sent to the flash drum and then to the stripper. Desulfurized oil
ia discharged from the bottom of the stripper while naphtha and hydrogen
sulfide are discharged from the top.
The gas from the hot separator is sent to the cold separator
gen is separated and recycled to the reactor. The remainder
separator is sent to the cold flash drum where some hydrogen
released. HYdrogen sulfide from both the flash drum and the
is sent to a Claus furnaoe to be conve~ted into sulfur.
where hydro-
from the
sulfide is
stripper
Operation data The fir'st plan. at Chiba had mechanical troubles for
over a year since operation was started in 1967. The troubles have been
overcome, and satisfactory operati(:n has been carried out recently. The
plant Rt Kashima has been working well since operation was started in 1970.
. Typical operation data for the Chiba plant are shown in Table 3.1. The
averae~ consumption of hydrogen is 500 to 600 SCF per barrel cf heavy
oil c~:.arged.
(/6)
-------
Hydrogen
A
A
Water
Naphtha
Heater
Waste-
vater
Stripper
Heavy oil
Desu1furized oil
A, A' : Reactors
D : Cold flash drum
C : Hot f'lash drum
B : Hot separator
E : Cold separator
F : Compressor
Flow sheet of UOP (RCD) Isomax process
Figure 3.1
"""'"'
-.
..:f
'-
-------
Table '.1 Typical operaticn data
BPSD Ratio to charge Sulfur (% in oil)
Charge h~avy oil 40,075 100 3.94
gasoline 362 0.9
Product gas oil 2,460 6.1 0.04
desulfurized oil 31,500 96.3 1.01
Life of catalyst The catalyst is poisoned by heavy metals contained in
heavy oil--by nickel and particularly by vanadium (Table 3.2).
Table ;.2 Viscosity and ingredients of heavy oil
obtained by t;pping of various crudes
Iranian Iranian
Kuwait Khafji Light Heavy California
Viscosity (cat, 50°C) 250 500 . 250 350
Su1fw:' (%) 3.8 4.1 2.5 2.6 1.9
Vanadium (ppm) 45 55 63 165 80
Nickel (ppm) 15 25 29 55 125
The heavy oil from Iranian ileavy (Gaoh Saran) crude contains the larbest
amolmt of vanadium and is most unfavorable for the catalyst. Catalyst
life ia about 25bbl/lb for Iranian Heavy and '5 to .45bbl/lb for other
heavy oils.
Carbon deposits on the catalyst surface pose another problem.
deposi tg can be reduced by using a higher hydrogen pressure.
remarta~ly v~e~ t~e r~cti0n temperature exceeds 430°C.
The
They occur
The catalyst used to be regenerated after several months' operation.
The regeneration requires much sodium hydroxide. Recent~ a new type of
cheaper RCD catalyst has been introduced which is abandoned without
regeneration. Better econo~ is achieved in this way.
Investment and operation costs According to a recent estimation5)investment
cost for a plant to treat 50,OOOBPSD Khafji heavy oil and requirements
for operation are as follows:
(Tables ;.4 and ;.5).
(J ,>
-------
Table 3.4 Investment cost for desulfurization plant (millions
of yen)
Isomax HYdrogen production Sulfur recovery
J SO. ()()()BPSD). il.1S x 106Nm3/daY) (225t/day) Total
Equipment 4,800 1,300 491 6,591
Patent 1,065 206 1,271
Oa ta1yst 830 155 20 1,005
Chemicals 14 10 24
'l'ech8ical 25 1 5 31
gni noe
Total 6,720 1,682 526 8,928
Tab10 3.5
Requiremen's for operation of 50,000BPSD
plant
Isomax
plant
Elee tr io power (k\rl) 2,370
Steam 'tons/hr) 2.5
Water for bOilero(tnna/hr) 4.0
Process water (tons/h~) 30
OoolinR water (toDs/hr)4,030
Fuel (106kcul/hr) 88
Catalyst (Iaomax) (kg/day)650
CAtalyst (hydrogen)(Il03/day) -
C"~~'.~:' ~r.emicah (kgjday)
H,ydroeen
plant
1,600
-1.1
13
33
100
92
165
61
Sulfur
-plant
510
26.6
-26.6
1,300
2.0
310
Tota 1
4,480
28
50.4
63
S,430
100.4
6S0
165
371
Op~r~tion cost, accordi~ to Idemitsu, is about '2,100 to treat one
kiloliter of KhafJi heavy oil to decrease sulfur c;ntent from 4 to 1%.
Another estimate5)gives a nearly equal t(ost (6.2). One report places
Lhe operation cost at as low as Yl,1556). This estimation seems too low.
It, lA possible, however, for the cost to be reduced to a little less
than ¥?,OOO through future improvement of catalyst if the by-product
sulfur can be sold at a reasonable price.
(I' J
-------
'.2 Gult J1'OO... tor top~4-orwt. b.Ydr04.nltu~)
State of development! ooaDeroial plant oapable of treating 25,OOOBPSD
heavr 011 has been 1n operation sinoe 1970 at the Millushia vorks of Nippon
Kinin« Co. Another plant, ,with a 40,OOOBPSD oapaoit)P, i8 to be built in
1972 at the Himeji works, I4a1teu Xo..n.
De80ripiion The flow sheet of the proce.s i8 given in figure 3.2. The
prooes. i8 similar to the UOP-RCD process (3.1), but differs from the
latter in that.
(1) Two reaotors are provided in parallel, either one or both of them
oan be used.
(2) o.s from the separator is vashed in a sorubber by aaine to r..ove
~drogen sulfide, thus, ~drogen gas without ~drogen sulfide is
recycled reUl ting in better deeulturiu tion.
(3) ! portion of the oold ~drogen gas frea the scrubber is introduced
into the reaotors for oooling to mainiain an optt8wD reactiOD
temperature--300 to 350.C--vhereas in the ear17 UOP-RCD process cold
oil was reoycled for cooling.
(4) ! l1ol1bdermm-Diokel-oobal t oa talyst i. u.ed vhioh is fair17 oheap
and is abandoned after about 6 110nth.' use without being regenerated.
Operation data The Mizushilla plant bas been in satisfaotory operation
sinoe it vas started in 1970. Typioal operation data u81ag Kuwait heavy
011 (sulfur ,. 9~, vanadiUl1 52ppm, niokel 15ppm) are abOft iD Table 3.6.
Table '.6 Produots frol1 deeulfurizatioD ot Imwait heavy oil
(130 to l40kg/c.2 pre.8Ure, 320 to 3,o.C t..perature,
LBSV near 17 1)
Produc te (~bY volUl1e~
C- C4
0.6
Deeulturi.ed
aS --- 343.C heaU' oil
4.8 96.3
Sultur oontent of desul-
turi.ed heav.v oil
-------
Hydrogen
plant
Heavy
oil
r-
Iv
--
..
...
Reactor
A
Heator
Reactor
B
Heator
Figure 3.2
Flow sheet of Gulf process
Scrubber
Separator
A
Separato
B
Gas
Naphtha
Recti-
fier
Furnace
oil
Desulfurized oil
-------
To l18intain a hiBh de8UltUrisation rate, the reaotion t_perature i.
gradual17 1'8i.e4 8. the oa-17.' ao'i.iv i. lowered 4uri- operation
<'iI'11"8 ,. ,). The oata):7.' i. ruin8d at t_perature. above 400.0. The
plant vas de.igned for a oata17.t ohallp 8.817 6 8cmth..
Kbafji heavy oil al.o oan be desulfurized b1 the plant although treat-
lDent .- a little harder than vi th Xuvai t heaY1 oil. To desulfurize
Iranian g,avy < Gaoh Saran) oil vhioh i- rioh in VSDadiua, it i- required
to ohaQge the plant de8ign.
Boonomios Total inveBtlle~t oost tor a dellUlfurizaUon plant oapable
ot treatiDB 40,OOOBPSD ot Xuvait heavy oil to reduce sulfur to as lov
as l~ 1s estimated at about Y8 billion inoludiag the ~drogen plant and
sulfur recoveZ7 plant. The operatio. oOlt vould be 12,200 to 2,100 per
kilo11ter ot oil neglecting bT"product oredit trcm selling the recovered
sultUr .
50
40
......
u
0
....." 30
.
p.,
E
Q) 20
~
'+-4
0
Q) 10
10
'P'4
P:4 0
0 1 2 3 4 5 6
Time ( month)
Figure 3.3
Rise ot temperature during operation
(;22)
-------
. .
3.3 !JDS prooell for topped-orude b.Tdr...9J8nllvl..tion8)
Developer Governaent Chemioal Besearoh luti tute, ToJqo
1-1-5, Honmachi, Shibuya-ku, Tokyo
State of DeveloJ88nt A pilot plant ueiQg & reaotor 20Qaa in d1a8eter
ls In 8UOoes.tul operation. A. IIW)h larBer pilot plant 18 planned.
De80ription Thi8 proce88 18 oharaoterlsed by the use of & aoviag-bed
reaotor. A. devioe enables the oataq8t to be renewed oontinuousq
without having to 8top plant operation. A .00el or the reaotor ia shown
in '1BVe '.4.
Advantage8 The oata178t i8 renewed
oonti.uou817 duriDB plant operation,
wherea8 in the UOP and Gulf prooe8se8,
. whioh U8e a tixed-bed reactor, plant
operatioft has to be stopped to ohaDBe
the oatalyst. Reaotlon effioiency 18 better wlth
an ebullated bed.
The oata17.t,obarBed froa the
top, trBdua11y de80end8 tkrough the
reaotor without beins fluidized.
A mixture or h_..,. oil and }qdrQBeJl
18 oharSed from the bottC8 aad 00118.
in oontaot with the old oata178t
fir.t. Imparlty In oil i8 fl1tered
&wa1 by the old 08t8118t; this' obv1&~.8
the U8e of a filter whioh is needed
with other t~1 ot reaotors. Cata17lt
in the upper 187er i8 alway8 kept
olean and -intaln8 hiBh l'88oU.,1 ty.
A flow sheet ot the 818tem 18 shovn in
'iBUre '.5. T;rp1oal operation data are
Biven ift Table8 '.7 and '.8.
Catalyst
Gas
Heavy oi
Hydrogen
Desulfurized
heavy oil
Catalyst
Figure 3.4
Model of moving bed
reactor
the mo.,ll1g bed than wi th
(23)
-------
Air heater
IiV
~
Fluidized
heater
Reactor
00
Catalyst
pot
Pump
Heavy oil
Heater
A
00
eater
B
C
Flash drum
Figure 3.5
A : Hot separator B: Cold separator C: Scrubber
Flow sheet of MDS process with a pilot reactor 200 mm in diameter
Hydrogen
Pump
Buffer
Buffer
Deeu1furized.
heavy oil
-------
Table 5.7 'mical operation data (lbatji heavy oil)
0-2 1'-2 G-3
Pres8ure (k8IcI12) 200 200 200
Tempera ture or ca tal;yst
Maxillua (. C) 40' '92 40'
MinilllUl1 (. C) ,67 '81 '9'
ATera,e (.C) '85 '87 '98
LBSV (hr-l) 1.01 1.27 0.62
Oil recycle ratio 1.,6 1.68 6.47
Sulfur in heav,y 011 (~) 4.11 4.~ 4.~0
Sultur rem0'l81 (~) 81.9 76.4 90.6
~drcsen COll8Ulapti ODe Chem. .;kl) 177 149 186
Sulfur 111 desultur1zed c11 (~) 0.76 1.07 0.67
V18cosity or desulfur1zed 011
(Cst at 50.C) 9,.6 148.2 58.7
D18tillation test
I. B. P. (.c) 204 163 1'8
~ (.c) 28' '07 225
1~ (.c) ,06 '28 280
300.C + (vol.~) 91.5 96.1 8'.5
Table '.8 Material balaDCe 1n Kbafj1 heavy oil tests (kg/hr)
Heav,y oil charged
~drcgen oharged
Total
De8Ulturized heavy c11
Btdrcgen released
Iqdrcgen sulfide
C ,",- C
1 4
Total
C-2 1'-2 G-,
86.50 104.20 51.21
1.81 "1.7' 1.01
88.'1 105.9' 52.22
84.91 101.40 44.99
0.46 0.40 0.14
'.09 '.40 1.99
0.26 0.27 0.42
88.75 105.47 47.54
(HI
-------
~.4 Other tests o~ tODDed-crude hY4rodesulfurlzation
(1)
Suspending-bed ~drodesulfurizatlon
Developer The Agenoy of Industrial Science and Teohno1ogy with Nippon
Oil Co., partly with Chiyoda Chemioa1 Bngineering Co. and Nligata
Engineering Co. .
Desoription Pilot plant tests on suspending-bed ~drodesulfurization
have been oarried out since 1969 using a ceba1t-mo1ybdenum oatalyst.
In prellminar,y tests with a reaotor 200mm in diameter, sulfur removal
reaohed ~5 to 80% with Khafji heavy oil by reaotion at 380 to 39O.C under
195k81om pressure at LHSV 1;0 to 1. 5.
Testa with a larger reaotor to treat 250BPSD have been oarried out since
1910. A .-.odified reaotor with the same oapaoity was oompleted recently.
Details ot these tests have not 7eiT:b8elLlIBde known.
(2) Tests on oatalyst
The National Researoh Institute of Pollution and Resouroes has worked on
improvement ot a oobalt-molybdenum oatalyst using alumina and silioa-
alumina as oarriers. After soreening tests, 1,000 to 2,000 hours' tests
were made on the seleoted catalyst. Over ~ sulfur removal was attained
with the oatalyst.
A research group of ten oil refiners has worked on niokel-molybden~
alumina catalysts. A good catalyst was obtained after 1,000 to 1,500
hours' tests. By oooperation with the National Institute of Pollution
and Resouroes, 2,000 to 3,000 hours' lite tests have been made.
Details of these tests have not been. publiRed yet exoept a tundamental
study of the oatalytio reaotions involved.9)
3.5 Vaouum gas-oil hydrodesu1furization
Desoription Sixteen commercial plants for vaouum gas-oil hydrodesulru-
rization are in operation and several others are under oonstruotion
(Table 2.1). Typical examples of material balance and flow Sheet of the
prooess are shown in Figure 3.6 and Figure 3.1.
(2'J
-------
Gas 011 57.5 ( s = 3.1%)
Desulfurization
-
eavy oil 100 (B. P. 315 to 560°C)
haJji, 5 = 4.15%) 56.2
. -
, (5 =0.2)
Vacuum ~
distillation
Residual 011 42.5 ( s :: 5.4%)
~If
H
( K
Figure 3.6 Material balance in VGO process
Heavy oil
98.7 (s = 2.6%)
Vacuum gas oil (gas oil) obtained by vacuum distillation ot heav,y oil,
with a boiling point between 300 and 560.c and with essentially no
vanadium or niokel is subjected to h1'drodesulfuriza tion under the con-
ditions indicated in Table 3.9.
Table ;.9
Condition ot VGOdesulturization as compared with
TC deBUlfurization
Vaouum gas-oil Topped-orude
desulfurization deBUlfurization
Oil charged
Reaction temperature (.C)
Reaction pressure (kg/cm2)
LHSV
Catalyst lite (years)
B3drogen consumption (sCFID"l)
Vacuum gas oil
Below 450
90 to 110
2.0 to ;.0
; to 5
;00 to 400
(2V>
Heavy oil
Below 450
1;0 to 160
0.5 to 1.0
0.5 to 1
500 to 800
-------
Heater
Water
A
Vacuum gas oil
r;;
.'"
'-
C
Hydrogen
Compressor
Waste-
water
BtS
Stripper
Naphtha
Naphtha
A : Reactor
B : High pressure separator
C : Low pressure separator
Figure 3.7
Flow sheet of vao hydrodesulfurization process
-------
The desulfurization is oarried out far more easily than with the topped-
o~de process. The oata1yst life is as long as 5 years. Sulfur content
of oil can be lowered to O.~. A typical example at the yield and pro-
perties of products is illustrated in Table }.10.
Table '.10 Yield and properties of products of VGO desul-
furization
Vol. % Wt. %
Charge
IChafji VGO 100.0 100,0
~drogen 419 0.79
Products
H2S '.21
C1 -. Cs 1.07
C6 ,-- 3S0oF 1.84 1.50
350....6oo.F 6.S3 6.00
6oo.F '" 92.07 89.01
~fur~
Viscosity(Cst~ 5O°C~
3.2
33.0
0.005
0.05
0.20
1.1
}3.0
Advantages Operation is eas,y and veIl-established. Vacuum gas oil can
be desulfurized to a very low sulfur content ~t ,a fairly low cost (6.2).
Desadvantages Utilization of the residual oil from vacuum distillation
is a diffioult problem. The oil, oontaining much sulfur, heavy metals
Rnd asphalt, is quite diffioult to desulfurize. It is usually mixed
with the desulfurized oil to be used as fuel oil (Figure 3.6). Overall
desulturizstion is poor in this case.
Modified procesl To obtain fuel oil with a lover sulfur content, a
modified process as illustrated in Figure 3.8 is also used. In this pro-
cess, the residual oil from yaouum distillation is extracted with a sol-
vent such as propane, buthane or pentane. The extract is desulfurized
togsther with the vacuum gas oil. More than a half of the sulfur in heavy
oil oan be removed in this way.
Another way to use the residual oil is to burn it as tue1 and remove
SO from the flue gas. This process seems promising if it is used on a
B~tab1e Beale and in favorable locations 'for flue-gas desulfurization.
l2V
-------
Case 1
Deaulfurization
Va
di
.
..
73.2 73.7(S=0.3%)
Extract 100.5
I Residual oil ..
21.9 -
cuum - ( S = 2
stillation 48.7
VGO ( 315 to 510°C) 51 3
Heavy oil
100 ~
."'>
Solvent
extraction
Asphalt 26.8(s:6.7%)
Case 2
Desulfurization
VGO(315 to 510°C) 51.3
85.4
85.9(S=O.37~)
Heavy oi
.
100
Vacuum
distillation
48.7
Extract
34.1
100.5
(S = 1.6%)
Residual oil
Asphalt 14.6 (S=7.4%)
Solvent
extraction
Figure 3.8 Modified VGO desulfurization processes
( Charge: Khafji heavy oil, S=4.15%. Hydrogen consumption: 450
SCF in case 1 and 550 SCF/bbl in case 2.>
(0)
-------
sifioation desulfurization of hea
oil
2-1, Nagatacho, Chiyoda-ku, Tokyo)
State of development A pilot plant to treat 5 tons heavy oil per day
1s in operation. Construction of a prototype plant to supply the gas to
a 40MW power plant has been decided recently. The total investment is
estimated to be nearly ¥2 billion. The construction is scheduled to be
oompleted by early 1973.
Outline Heavy oil is converted into fuel gas by partial oxidation with
oxygen and steam. Sulfur is converted into hydrogen sulfide which is
removed from the gas by the wet process. The flow sheet of the process
is shown in Figure 3.9.
Description Heavy oil is charged into a fluidized reactor with oxysen
and a jet stream ot water vspor and undergoes partial oxidation at 800
to 9OO.C.under atmospheric pressure. In the reactor, silica-alumina
partioles are fluidized to promote the gasification of heavy oil. The
gas leaving the reactor is cooled to 450.C in a quencher by spraying
residual 011 from a distillator. The silica-alumina particles are flui-
dized also in the quencher and are gradually coated with tar. The tar-
ooated partioles are continuously sent to a regenerator, where the tar
1s burned oft by air.
The product gas from the quencher contains hydrogen, hydrocarbons, carbon
oxides, hydrogen sulfide, and carbon. Carbon i8 removed by a cyclone.
The gas then is cooled, condensed, and treated in a distillator. The
distillate is cooled to separate gas oil and the gas i6 sent to an absorber,
where hydrogen sulfide is removed to produce sulfur-free fuel gas. Part
of the residual oil from the disti11ator is sent to the qUenche~ and regene-
rator. The rest of the resudual oil is decomposed in a high-temperature
reactor together with the carbon from the cyolone. The gas from the
high-temperature reactor is also sent to the absorber.
The removal of hydrogen sulfide from the gas is carried out by the wet
process, preferably by absorption with potassium carbonate. HYdrogen
sulfide is regenerated from the solution in a discharger and sent to a
Claus furnace to be converted into sulfur. The refined product gas con-
tains about 19% H2' 16% 0H.4, 15% 02H4' ~ O~, 6% 03116, l~ OO,and l~
002 with essentially no sulfur. The heat ot oombustion of the product
gas reaches about 8,OOOkcal/Nm3.
The material balance is il1ustrateg in Table '.11. The production cost
is estimated to be about ¥1,OOO/lO kcal (Table 3.12) and thus the product
(31)
-------
may be able to oompete with imported LNG or 10v-sulfUr oil (Figure 3.10).
Better 8oono~ may be expeoted by using residual oil from v~cuum distil-
lation as illustrated in Figure 3.11.
Table 3.11 Material balance
Feedstock Products
Heavy 011 1,000 Refined dry gas 1,289
Oxygen 472 Steam 417
Steam 497 Gas oil 75
Total 1,969 Sulfur 35
Advantages
High-sulfur heavy oil and residual oil can be utilized.
Higher sulfur recovery than in ~drodeBUlfUriz8t1on.
Far smaller desulfur1zation facilities than in flue-gas desulfUrization
beoause of the smaller amount of gas and higher concentration of sulfur
compounds.
Disadvantages
Oxygen is required.
Separation of hydrogen sulfide from the gas containing olefins and carbon
dioxide is not quite easy.
The whole system is not simple.
Table 3.12
Cost estimation
(Production of fuel gas to supply 500MW power plant.
Total capital cost is 16,840 million.)
(J'l )
-------
Case 1 Case 2
,",Operation 6.100 hours a year) ",Operation 1.~OO hours a year).
ADnua1 cost Cost Annual cost Cost
..(!yJ.1ions of yen11YerV106koal) -'Millions of yen) ,",YerVI06kcal)
4,0~8 61~ 5,2~ 61~
825 125 1,069 125
62 9 81 9
-462 -10 -599 -70
684 104 684 80
80 12 80 9
205 ~l 205 24
~58 55 358 42
181 28 181 22
650 99 650 16
6,627 1,006 7,945 930
Heavy oi1
Eleotrioity
Cooling vater
Reduction*
Depreciation**
Labor
Maintenanoe
Other fixed oosts
Management
Interest
Total
* By sulfur and gas oil
** 10% of total investment cost
(11)
-------
QU;llcher
(4S00C)
Reactor
(800 to
900°C)
'Q
-e
Heavy
oil
Jet stream
of vater
vapor
Figure 3.9
Cyclone
Air
Carboll
Nesidual oil
ox,ygen
Flow sheet of Ube
gassitication desulfurization
process
Gas
oil
Com..
pressor
Distil-
lator
Carbon
Residual oil
Cooler
Absor-
ber
Product
gas
Discharger
Heat exchanger
Sulfur
High-temperature
reactor
Oxygen
Tail-gas
treatment
-+
Waste
gas
-------
-
,..,
as
u
.!4
........
s:: 1.
C)
>4
't;;
~
-
~
co
o
o
1.
LNG, under future contracts ( S = 0% )
-
-----
------
----
- - ------ ---
Class C heavy oil for power plants ( S = 1.}%)
o.
o
200
400
600
800
Capacity of power plant (MW)
I Naphtha
!(S(o.O,.)
1,000
Figure 3.10 Cost and sulfur content of fuels for power plants
-------
Residual
oil
( S.4%)
16
Heavy oil
32 (8=5%)
Reactor
Carbon
High temp.
reactor
Sulfur
recov817
Fuel
gas 26
Crude oil 100 ( 8 = 2.5%)
55
Topping
45
VGO
23 (8=3%)
Hydrodesu1fu-
rization
39
Vacuum
distillation
Residue
( 8=5.5%)
16
Low-sulfur
fuel oil
24
Gasoline,
etc. 45
I SU1~ I
Figure 3.11
Combination of oil refinery and gasification desulfurization
(3l>
-------
Heavy oil
Air
Power eneration bait ation desulturization ot hea
Japan Gasoline prooes8
. Developer Japan Gasoline Co. ( .2-4, Otemachi, Chiyoda-ku, Tokyo)
State of development Feasibility study has been made reoently by Japan
Gasoline Co. A pilot plant may be built in 1912 jointly with Kansai
Electrio Power Co. or Tokyo ileotrio Power Co.
oil
Desoription The process is similar to the Bulzer prooess of West Germany
and consists of the following three steps:
(1) Partial ~xidation and heat recovery--Heavy oil or asphalt is s~b-
mitted to partial oxidation with air at 1,5OO°C under 10 to 30kg/cm
pressure to be converted into a gas mixtue:o~ hydrogen and water vapor
(l~), carbon monoxide (2~), hydrogen sulfide (O.~), nitrogen (6~)
and other minor oomponents. The gas is cooled to l60.c by generating
high-pressure steam.
(2) Recovery of sulfur--More than 90% of the hydrogen sulfide is removed
from the cooled gas and converted into elemental sulfur by a conventional
proces8.
,--- - - ->High
I
,
,
~
pressure steam
-----
Partial
oxidatio
Gas
turbine
Heat
recovery
Waste
gas
1.5000C
. 60.c
850°C
,
,
- - - --,
I
,
,
,
, .
, ,
, ,
I
- - ---+ E~ctricH'
Air
Recovery
of sulfur
Partial
combustion
Steam
turbine
o C
Air
Figure 3.12 Simplified flow sheet of Japan Gasoline process
(3?1
-------
(}) Power generation--The desulfurized gas is partially burned by air
to raise the temperature to 850°C, then sent to a gas turbine for power
generation. The gas is then oompletely burned in a boilor to heat the
high-pressure steam from the heat recovery section. The super-heated
steam is used for a steam turbine ~o generate power. For partial oxida-
tion, a Shell-type or Texaco-type reactor may be used. The total invest-
ment oost for a commercial-scale plant to generate 200MW electric power
i8 estimated to be about 110 billion. The overall effioiency (power at
terminal)/(LSV consumption) would be about }7. "ffi.
Advantages
AsphaJt, a cheap fuel containing much sulfur, can be also used. 1 small
amount of carbon formed by the partial oxidation can be completely re-
covered and recycled to obtain a clean fuel gas.
Sulfur in the fuel can be converted into hydrogen sulfide, which is readily
removed.
More than 90% of sulfur can be removed.
The whole system is a combination of several well-established processes.
Emission of NOx is less due to the low combustion temperature.
The amount of gas formed by the partial oxidation is about half that by
oomplete combustion (Table 3.13). The actual volume of the gas for
gasifioation desulfurization is only one-twentieth to one-sixtieth
that for flue-gas desulfurization because the desulfurization is carried
out under pressure. Plant size can be substantially reduced.
Table 3.13 Comparison of desulturization processes (2OOMW plant)
Volume of gas (Nm3/hr)
Sulfur compounds (% in gas)
Temperature (OC)
Pressure
Gasifioation
300,000
H2S 0.32
40
10 to }0k8/cm2
Flue gas
600,000
S02 0.15 to 0.17
40 or higher
atmospheric
Disadvantages
Equipment that withstands high pressures is needed.
The generated gas, containing much nitrogen, has a low calorific value.
C~8)
-------
4
Stack-gas desulfurization by wet process
4,1 Kureha process (sodium sorubbing)ll, 12)
Developer Xureha Chemical Industry Co.
l-B, Roridomeoho, Nihonbashi, Chuo-ku, Tokyo
State of development A commercial plant to desulfurize 200,000 to 300,OOONm3/hr
flue gas from an oil-fired power plant has been in operation since Februar,y
1969. Another plant of nearly equal size has been in operation since
Septem~er 1910. Two more plants will be built in 1912.
Description Stack gas is first washed with water in a conventional
scrubber for dust removal and cooling, then desulfurized with a sodium
sulfite solution in a rubber-lined packed tower to remove about 95% of 502.
'../a ter
( 25t/hr)
Haste gas( 60°C, s~ 0.007%)
321,500 Nm'/hr)
NaHSo,
50% NaOR
1.. 995Kg/hr
Flue gas
300,OOONm'/hr
A
B
S~ O.14~.6
165°C
Separator
rystal-
l1zer
Na, So,
2,330kg/hr
Dryer
A : Dust removal and cooling
B : Absorber
Figure 4.1 Flow sheet of Kureha process
P~)
-------
The sodium bisulfite solution leaving the packed tower is treated with
a sodi\uo hydroxide solution to give a sodium sulfite solution, which is
concentrated in a crystallizer to produce sodium sulfite crystals. The
crystalline sodium sulfite is separated, dried, and supplied to paper
mills. The purity of the sulfi te ranges from 90 to 91%. The mother.
liquor (sodium sulfite solution) is sent to the packed tower.
The packed tower absorber was designed to evaporate as much water as the
water in the sodium hydroxide solution charged, to maintain water-balance.
Pressure drop in the absorber is 65mm H20. An oxidation inhibitor is
used when it is necessary to reduce the sodium sulfate content of the
product.
. - ------ -..---
Table 4.1
Operation data
Amount of gas
Temperature in absorber
SO~ concentration
Amount of liquid
~ Charge Discharge
Gas(oC) Liquid( °C 1 Inlet(%) 0ut1et(7~) Jm3/hr ). ~
233,000 61. 5 62.0 0.135 0.007 31. 5 30.6
218,000 59.5 59.5 0.134 0.009 32.0 31.0
227,000 60.0 60.0 0.125 0~010 31.1 29.6
---
Cost, advantages and disadvantages 3The total investment cost of the
plant to treat 200,000 to 300,OOONm /hr gas was 1420 million. The desul-
furization cost including reheating of gas is 1500 per kiloliter of
heavy oil containing 2. ~ sulfur (Table 6.7)
The process is simple and operation is easy.
The market for sodium sulfite, however, is limited.
(6.1).
Modified processll) Tests have been made to treat a sodium bisulfite
Boluti'-,n with milk of lime or limestone to produce sodium sulfite and
calcium sulfite. The sodium sulfite solution is recycled to the absorber.
The oalcium sulfite is oxidized into gypsum, whioh has a fairly large.
market in Japan.
2NaHS03 + CaCO, 8 Na2S03 + CaS03 + H20 + C02
Cas03 + 1/2 02 + 2H20 = Cas04.2H20
(~o)
-------
Using this modified process, a demonstration plant capable of treating
5,OOONm3 flue gas is under construction jointly vi th Kavasaki Heavy
Industries at a cost of !50 million.
Showa Denko process (ammonia or sodium scrubbing)ll, 13)
4.2
Developer
Showa Denko K. K~
34, Shiba Miyamotocho, Minat~lq.1, Tokyo
State of development Commercial plants designed to recover S02 from tail
gas from sulfuric acid plants, and therefrom produce an ammonium sulfite
solution for papermaking were operated for a few years. These plants
vere closed recently as the superannuated sulfuric acid plants were shut
down.
A similar type commercial plant to treat l50,OOONm3/hr flue gas from an
oil-fired boiler using a sodium hydroxide solution in place of ammonia
has been in operation since October 1910. Anothe3 plant of similar type
to treat, with sodium hydroxide,tail gas (eo,OOONm!hr) from a new sulfuric
acid plant has been in operation since May 1911.
Description Vertical-cone type
sorubbers are used. The liquid
19 charged from the bottom and
blown up by gas to ab90rb s02.
The liquid is recycled without
the use of a pump. The liquid
gas ratio is about 1 1iter/m3;
gas pressure drop is less than
250mm H20. The desulfurized
gas is discharged through a gas-
liquid separator.
r
Gae
Gas liquid
separator
Two absorbers are used to treat
l50,OOONm3/hr of the gae from
an oil-fired boiler, as is
illustrated in Figure 4.3. The
gas contains about 0.15% S02
and 0.12gfNm3 dust. About 95%
of the S02 and 6~ of the duet
are removed.
Liquid
Gae
The sodium sulfite solution is
filtered to remove duet, after
Figure 4.2
Type of
scrubber
(~I)
-------
whioh it is sold to paper mills. The solution contains 20% sodium sul-
fite, less than ~% sodium sulfate, .le88 than 0.05% sodium chloride, and
less than 100g/m heavy metals.
In the old plants which used ammonia, a small amount of white fume was
generated which was not easy to remove by additional water scrubbing.
This is the reason why sodium is used in the new plants which treat larger
amounts of gas.
150,000
Economics The total investment for the plant to treat ~Nm3/hr tail gas
was 1200 million. The operation cost is 1680 per kiloliter of oil con-
taining 2.7% sulfur.
Gas
To stack
Scrubber
Scrubber
Heater
Doiler
Fuel
Gas
Air
NaOH
Water
N~ 80, solution
Figure 4.3
Flow sheet of 8howa Danko process
(lf1)
-------
4.3 Behoo-Tsuktahl&a
process (sodium 8crubbi~)11, 12)
Develo~er Behco (Sweden) and Tsukishima Kikai Co. (17-15, 2-chome,
Tsukuda, Chuo-ku, Tokyo)
Description Desulturization is carried out with a sodium hydroxide
solution using the Behco so rubber. About 95% of S02 is recovered as a
sodium sulfite solution. More than 9~ of dust is also removed. The
solution is filtered to give a clear solution to be used for papermaking
(Figure 4.4). Pilot plant tests have been made to produce solid sodium
sult! te or sulfate. Tests also have been made to recover 502 with lime,
to produce gypsum.
NaOH
~'/a ter
Flue gas
Filter
Absorber
Product
(N~ So, solution'
Neutralizer
Setting tank
Figure 4.4
Flow sheet of Bahco-Tsukishima process
State of development Three commercial plants are in operation at
Daishowa Paper Co. (Table 4.2).
(4-.1)
-------
Table 4.2
Commeroial plants using Bahco-Tsukishima process
(Temperature of gas oharged, 150 to 190°C
Temperature of gas disoharged, 55 to 58°C
Pressure drop in sorubber, 360 to 380mm H20.)
Plant site
Yoshinaga* Suzukawa* Suzukawa**
Flue gas (Nm'/hr) 220,000 24,500 110,000
502 in gas (ppm) 1,000 1,200 250 to 300
Dust (g/Nm3) 0.01 0.01 0.15
S02 recovery (%) 95 95 90
Dust removal (%) 90 90 80
Number of scrubbers 3 1 1
* Oil-firing boiler ** Combustion gas of sludge
A plant is under construction at Central Glass Co. to treat 100,OOONm3/hr
oombustion gas from its glass furnaces. Another plant i8 under~on6truction
at Daio Paper Co. to treat 300,OOONm'/hr gas. In add! tion, several plants
will be built to treat combustion gas of sludge from wastewater treatment
in big cities such as Tokyo and Osaka. A lime scrubbing plant will be
built at Yahagi Iron Co. Ltd.
~ Kanagawa PIL prooess (Jinkoshi process)ll, 12, 13)
Developer
Industrial Research Institute of Kanagawa Prefecture
3173, Showam&chi, Kanagawa-ku, Yokohama
Description A new type of absorber using screens has been developed by
Kanagawa PIL (Jinkoshi). Sea water, industrial water, dilute aqueous
ammonia, or sodium hydroxide solution flows down on the surface of stain-
less steel screens (about 10 mesh) placed vertically or with inclination
to form stable thin liquid films which are highly effective for removal of
S02 and dust.
Pilot plant tests A pilot plant with a capacity of 3,OOONm'/hr of gas
from an iron-ore sintering plant was built in 1967 at the Keihin works
of Nippon Kokan (KKK). The gas was first treated by a conventional type
of sorubber with water for cooling and then led into a scrubber with
screens. More than 85% of S02 was removed by absorption with industrial
(44J
-------
water at 33 to 35°0 and pH 7.2 to 7.4. More than 95% of 502 vas removed
with very dilute aqueous ammonia (reoovered from ~ot. oYen gas) at 36 to
41°0 and pH 8.4 to 8.6 (Figure 4.5).
400
t.4
QI
~
ft.4
I1S
,....
d'i
tlJp,
-
ft.4
o g 200
s:t....
o~
~~
11S....
~ ~
~~
s:tft.4
Qlr"4
U ::s
s:t II)
o Qj
U"d
Industrial
water
2,000
Dilute aqueous ammonia
K X K X
4,000 6,000
Amount of gas ( Nm' /hr )
°
Figure 4.5
Desulfurization in pilot tests by Jinkoshi process
( S~ in gas 1,400 to 2,000ppm )
Larp:er pilot plant test A. larger pilot plant des...gned to treat 30,OOONm3/hr
gas from an iron-ore sintering plant has been in operation since 1969
at the Keihin works of Nippon Kokan. The absorber, measuring 4.6 x 4.6 x
l2.0m in size, consists of three sectionsl (1) a dust removal zone where
most of dust is removed by sea water, (2) an 502 removal zone where 502
is absorbed by dilute aqueous ammonia (about 0.2% concentration) obtained
from coke oven gas, and (3) an ammonia-gas recovering section where ammonia
released in a small amount from the 502 removal zone is caught by sea water.
(~t" )
-------
The water disoharged from this section is sent to the dust removal
seotion (Figure 4.6). The 802 ooncentration of the oharged gas, 600 to
I,OOOppm, was lowered to 50 to 80ppm when ~O,OOONm~/hr gas was treated
with dilute aqueous ammonia at about pH 8. The investment oost for the
plant was 180 million.
Sea water
Aqueous ammonia
from coke oven
Gae
"" "
" ',' '\
" , "
" '" "
" , "
" " "
" " "
\
Gal!!
to s?ac
>
Tank
Tank
Wastewater
Ammonium sulfate
recovery
Figure 4.6
Flow sheet of pilot plant by Jinkosbi... NKK process
(30,000 Nm' /br)
Prototype test (sodium scrubbi~l A prototype plant to treat 45,OOONm~/br
flue gas from an oil-fired boiler was built at Oji Paper's Tomakomai
works in 1969 (Figure 4.7). The gas is first treated by a presorubber
in which soreens (about 10 mesh) are placed nearly vertically to remove
dust with water. The screens are set in frames about 1 meter wide and
2 to 3 meters long. The gas is then led into an absorber where screens
are plaoed with inolination. A sodium hydroxide solution is fed onto
the soreen to absorb more than ~ 802 to form a solution of sodium
sulfite and bisulfite.
(t4J
-------
Pre-scrubber
l'lue galS
~
NaOH
tank
N~ So,
tank
Figure 4.7
Prototype plant by Jinkoshi - Oji process (45.000Nm'/hr)
Commercial plants The screen-type absorbers have been used commercially
in the following plants:
(1) Tomakomai Plant, Oji Paper Co. (see 4.5).
(2) Kawasaki Plant, Nichimo Oil Co. Tail gas (3,OOONm3/hr) from a Olaus
('t7)
-------
furnace is treated with industrial water (60tons!hr). 502 concentration
in the gas is reduced from 3,300ppm to 500ppm by an absorber with a
pressure drop of 350mm H20. The wastewater containing 502 is mixed with
other wastewater from the plant and disoharged into the sea after pH ad-
justment.
(3) To~ma Plant, Tokuynma 50da Co. Waste gas (23,OOONm3/hr) from a
rotary kiln for cement production is desulfUrized with sea water in order
to utilize C02 in the gas for soda ash production.
(4) Keihin Works, Nippon Kokan (KKK). A plant designed to treat l50,OOONm3/hr
gas from an iron-ore sintering plant is under construction at an expense
of ¥160 million as a joint venture of Nippon Kokan K.(KKK) and eight
steel producers. An ammonium sulfite solution is used for the recovery
of 502 to produce an ammonium bisulfite solution. The bisulfite solution
is used to recover ammonia from coke oven gas (30,OOONm3/hr) to produce
an ammonium sulfite solution. A part of the sulfite solution is oxidized
with air to produce ammonium sulfate; the rest is used to absorb 502.
(5) In addition, more than twenty smaller commercial plants are in
operation or under construction at chemical, food and other manufacturers.
Advantages and disadvantages
slight pressure drop.
High recovery of 502 is attained with a
The degree of desulfurization can be varied easily by changing the number
of the screens.
Uniform distribution of gas is required in order to ensure high recovery
of 502 and low corrosion of screen.
4.5 Oji process (sodium scrubbing~' 13)
Developer
Oji Paper Co.
4-1-5, Ginza, Chuo-ku, Tokyo
Description Wet-scrubbing of flue gas with a sodium hydroxide solution
has been carried out by Oji Paper Co. cOlIDDercially in several plants.
A sodium sulfite solution is produced and is used for paper production.
Two types of scrubbers, OK (cyclonic, over 85% recovery of 502) and
Jinkoshi (screen type, over 90% recovery, see 4.4) are used.
Application The OK scrubber was originally designed for treatment of
flue gas from a Kraft recovery boiler to reoover sodium sulfate dust and 502.
The. Jinkoshi scrubber is designed to remove dust and 502 in gas from
various plants. .
(.;.f)
-------
State of development
OK sorubber Sixteen scrubbers of this type are in commercial use. A
sodium sulfite solution is sprayed in a oyclonic scrubber to remove dust
and S02. For example, a scrubber made of fiber-reinforced plastic, 4
me tors in diameter and l' meters high, can treat as much as 115,000Nm3/hr
of flue gas from a Kraft recovery boiler to absorb more than 85% S02
(Figure 4.8). Stainless-steel sorubbers are used for flue gas from oil-
fired boilers.
Jinkoshi sorubber A pilot-soale scrubber has been in operation since
1910. A oommeroial-soale sorubber (220,OOONm3/hr) has been completed
very reoently. Two more of the same capacity are under construction.
In the pilot plant two Jinkoshi sorubbers are used in series; the first
one for removal of dust and S03 mist. The first sorubber was omitted
in the oommeroia1 plants. One scrubber removes more than 95% of S02 and
moat of dust. The dust is separated from the sodium sulfite solution.
Table 4.3 Commercial plants by Oji process
Type of Plant Number of Gas lAi te of
scrubber User site scrubbers Nm'/hr Temp.c::£I completion
OK Oji KasU88i 8 1,068,000 .150 1966 to 69
OK Tokai 3 314,000 150 1910
OK Oji Kasugai 1 183,000* 170 1970
OK Chuetsu Sendai 1 116,000 150 1971
OK Honshu Kushiro 2 260,000 140 1971
OK Oji Ebetsu 1 184,000* 198 1971
Jinkoshi Oji Tomakomai 1 45,000* 1970
Jinkoshi Oji Tomakomai 3 660,000* 1971 to 73
* For oil-burning boilers. Others are for Kraft recovery boilers.
Advantages The OK scrubber is simple and cheap.
pressure drop (40 to 60mm H20).
It features a small
The Jinkoshi scrubber is quite effeotive for 502 reoovery, with a very
small pressure drop and power oonsumption.
1.1)
-------
Kraft recovery boiler
Electrostatic
precipitator.
!to
Water
--,.....
Warm
water
Evaporator
OK scrubber
NaOH
Nlit so,
Figure 4.8
Flow sheet of Oji process
4.6 Wellman-Lord process (MKK)14, 15)
Constructor Mitsubishi Chemical Machinery (KKK)
6-2, 2-chome, Marunouchi, Chiyoda-ku, Tokyo
Users
Japan Synthetic Rubber, Chiba Plant
Description A commercial plant designed to treat 200,OOONm3;hr flue gas
from an oil-fired boiler has been in operation sinoe June 1971. The
flow sheet of the process is shown in Figure 4.7. Flue gas containing
about 2,lOOppm S02 is first washed in a scrubber--placed in a lower part'
of an absorber--to remove most of dust and S03. The gas is then washed
with sodium sulfite eolution to remove more than 90% of S02 and then led
into a demister at the top of the absorber. The waste gas at 60°C con-
taining about 200ppm S02 is reheated to 100 to 130°C by means of an
after-burner.
Two absorbers are used in parallel. The sodium bisulfite solution formed
in them is led into a double-effect evaporator-crystallizer and heated
l~-OJ
-------
To stack
Steam
-r
Water
Flue gas
.
-----
----
---
.
Cooling
vater
Separator
Naz So,
Crystal
NaHSo, solution
Wastewater treat~ent
Figure 4.9
Na, so, 8olution
Flow sheet of Wellman - ~~ process
Condenser
s~
NaOH
.
-------
Sulfur
'" 6%
'" 4.2%
" " '" 3%
/ '"
/ "
/ '"
/ _......:::._--------
/ " .
,," ,,(
'" "1
" "
,; / I
//,," I
". // I
".'" t
I
I
,
I
I
,
,
,
l5d MW ~
t
250'HW
,
,
I
I
I
..... I
...., I
....
.... .... I
.... I
......... I
....,.....
_"-::L~---------
....
.... .... 6%
4.2%
3%
Investment cost
( Desulturizer and
sulfuric acid. plant)
100,000 Nm' /hr
t
1,000,000 Nm' /hr
I 1
450 HW
.....
.....
....
....
,
....
....
Desulturization .....,
....
cost(per kiloliter.... ,
oil) .... ....
.....
,
Su1tur
i 2 billion
i 1 billion
i 0.5 billion
J 2,000
¥ 1,000
" 500
Figure 4.10 Relationship of plant size and sulfur content of
oil to investment and desulfurizatioD costs
({1)
-------
to 100°0 with steam, to be decomposed into a gas mixture of 502 and
water vapor, and orystals of sodiUJD sulri tee
2NaHSO, :(----? Na280, + 802 + H20
The gas mixture is cooled in a condenser to separate S02 from water.
The product 502 is sent to a sulfurio acid plant to produce 40 tons sul-
furio acid per day.
The sodium sulfite crystals are centrifuged from the mother liquOr,
dissolved into the condensate from the condenser, and recycled to the
absorbers. The mother liquor is returned to the crystallizer. Sodium
sulfate formed by oxidation is removed from the liquor.
Economics The total investment cost including the cost for the sulfuric
acid planl was ¥800 million. The relationship of plant size and sulfur
content of oil to investment and operation costs are illustrated in
Figure 4.10 (see also Tables 6.1 and 6.8).
11)
4.1 Wellman-Lord process (SOE)
Oonstructor
Sumitomo Chemical Engineering
33-5, 3-chome, Hongo, Bunkyo-ku, Tokyo
User Toa Nenryo, Negishi Plant
-
Description
from a Claus
sheet of the
A commercial plant designed to treat tail gas (10,OOONm3/hr)
furnace has been in operation since July 1911. The flow
process is shown in Figure 4.11.
The tail gas at 500°C containing about 1,000ppm S02 is cooled to 350°0
in a waste-heat boiler, then cooled to 100°C in a cooling tower with
water spray. This cooling method was used because gas containing much
S02 at 100 to 350°0 is quite corrosive. The gas at 100°C is then cooled
to 10°0 in a heat exchanger and introduced into an absorber with a three-
stage sieve tray to which a sodium sulfite solution at pH 6.2 to 6.4 is
charged. About 93% of 802 is recovered in the absorber.
Sodium bisulfite solution at pH 5.1 to 6.0 is discharged from the absorber,
led to an evaporating crystallizer, and heated to 100°0 to separate a
gas (50% S02 and 50% water vapor) and crystalline sodium sulfite from
the solution. The gas is cooled in a condenser to remove water. The
product gas which contains more than 99% 502 is sent to a Claus fUrnace.
The solid sodium sulfite is dissolved in water from the condenser and
(5j)
-------
~
-:!:
Flue
gas
Naz So, solution
Absorber
Crystallizer
NaHSo, solution
Figure 4.11
Flow sheet of Wellman - SCE process
Centrifuge
s~
NaOB
i
\
-------
returned to the absorber. The remaining solution is recycled to the
orystallizer. A portion of the solution is taken out of the system to
remove impurity and the sodium sulfate formed b;y oxidation.
An oxidation inhibitor developed by Sumitomo Chemical Co. has been used
in the process. Without the inhibitor 3 to ~ of total sodium compounds
in the plant is converted into sulfate in a day. By the use of the
inhibitor, oxidation is reduced to about one-third resulting in a sub-
stantial decrease in the consumption of sodium hydroxide.
The waste gas from the absorber 18 emitted at 60°C without reheating.
Although there has been no problem involving the waste gas, it is planned
to heat the gas by some means for safety.
Acid-resisti~~ materials such as stainless steel, fiber-reinforced
plastics and plastic coatings are used in the plant. Tests have been
made to seek cheaper aCid-resisting materials. Tests also have been
made to recover sodium hydroxide from by-product sodium sulfate.
Economics The total investment cost forthe recovery plant was 1600 million.
In addition, 1200 million was required for the cooling system for the
tail gas including a waste-heat boiler, cooling tower, and heat exchanger.
It is estimated by Sumitomo Chemical Engineering that when this type of
desulfurization plant is used fora 25OMWoil-fired power plant to treat
750,000Nm3/hr flue gas, the operatiun cost to remove 9~ of 502 would
ba about ¥1,5oo per kiloliter of oil. Reheating of the waste gas by an
after-burner would require ¥2oo to 300 more.
j.B Mitsubishi-JEC process (lime-gypsum process)ll, 12, 13)
Developer Mitsubishi Heavy Industries (5-1, 2-chome, Marunouchi,
Chiyoda-ku, Tokyo) and Japan Engineering Consulting Co.
(1-4, Ogawamachi, Kanda, Chiyoda-ku, Tokyo)
Description The gas is first washed with water in a spray tower for
dust removal and cooling to 50 to 60°C, then treated with milk of lime.
In a commercial plant completed in 1961, a large spray tower was used
for desulfurization to minimize the scaling problem. Extensive tests
have been made by Mitsubishi to prevent scaling and to improve the scrubber,
resulting in the establishment of many items of know-how for scale preven-
tion. In new commercial plants which are under construction, plastic-
grid packed towers are used. Two packed towers are used in series (Figure
4.12). Milk of lime is charged to the No.2 absorber. The reaction
(i".tJ
-------
Cooler
No.1
Absorber
--- ~---
I I
A\ I
I I
I I
I
Water
Flue
gas
c;;
....
-
r---,
I
I
I
I
I
I
I
I
I
I
I
L
t-!ilk of
lime
To stack
~
I
I
Figure 4.12
Mitsubishi-JEC lime-gypsum process
To No.2 absorber
l'
I
I
I
I
I
I
Oxidation
tower
Centrifuge
Gypsum
-------
product, a mixture of oaloium sulfite and lime with a small amount of
gypsum, is led to the No.1 absorber. Gas is first introduoed into the
No.1 absorber and then to No; 2 absorber to attain more than ~ de sul-
furization. Calcium sulfite slurry at pH 4.0 to 4.5 is discharged from
the No. 1 absorber and sent to an oxidation tower. In the tower the
sulfite is converted into ~psum by oxidation with fine bubbles of air
at 50 to ao°c under 5kg/cm pressure. Very fine bubbles are produced
by meanA of a rotary atomizer invented by Japan EnBineering Consulting
Co. Gypsum is centrifuged from liquor, the liquor is recycled to the
No.2 absorber. Gypsum thus obtained has more than 9&}b purity and good
quality, whibh make it suitable for use in cement and gypsum board.
State of development
(1) A commercial plant (Koyasu plant, Nippon Kokan K.) to treat tail
Bas from a sulfuric aoid plant 60,OOONm3/hr containing 0.2 to O.Y'/> 502
has been in operation since 1967. A spray tower absorber (5m x 7m
rectangular prism 15.5m high) is used to remove about 9~ 502' Most
of the units are provided with PVC lining. Pumps are made of hard rubber.
(2) A commeroial plant to treat flue gas from an oil-fired boiler at
the rate of lOO,OOONm~/hr is being built by Mi tsubishi at the Amagasaki
plant, Xansai Electric Power. A spray tower is used for cooling and
dust removal; two grid packed towers are used for desulfurization. The
plant, designed to reduce 502 concentration in the gas from l,500ppm to
lOOppm, is scheduled to come on-stream in March 1972.
(~) Another commercial plant to treat 52,OOONm~/hr gas from a sintering
plant of Tomakomai Chemical, Tomakomai, containing l,800ppm 502 is under
construotion by Japan Engineering Consulting Co. The types of absorbers
are the same as in (2) above. The plant is designed to reduce 502 to
50ppm (97% recovery). Liquid gas ratio of about 10 liter/Nm3 will be
used to attain the high recovery rate.
(4)
Two other commercial plants are being planned.
Advantages The process is fairly simple. Good quality gypsum is obtained
which can be sold for Y2,OOO/ton. Rotary atomizer is quite effective
for oxidation, involving no operational problem.
Disadvanta~es Oversupply of gypsum might occur within several years
if too many gypsum-producing desulfurization plants are built.
(5?)
-------
Economics Investment cost for the Amagasaki plant to treat loo,OOONmX' hr
gas is 1450 million. That for the Tomakomai Plant to treat 52,OooNm3 r
gas is 1100 million. The latter is unusually cheap.
Materials and utilities needed for a 250MW power plant (750,OOONm3/hr gas)
sre shown in Table 4.4
Table 4.4 Materials and utilities for desulfurization
of flue gas from 250MW power plant
(Sulfur in oil 3%, 90% recovery of S02)
Slaked lime
Industrial water
BOt/day.
1,OOOt/day
3 , Ooot/ day
70,OOOkWh/day
3t/day
2 persons/shift
lBOt/day
Sea water
Electricity
Sulfuric acid
Labor
By-produc t gypsum
The operation cost for a plant to treat 150,000 to 200,000Nm3/hr gas
from an oil-fired boiler is estimated by Mitsubishi at 11,400 to 1,800
per kiloliter of oi1 containing 2.5 to 3% sulfur, including revenue by
selling the gypsum at ¥2,000/ton.
11)
--4.9 Chiyoda Thoroughbred 101 process
Developer
Chiyoda Chemical Engineering & Construction
1580 Tsurumi-cho, Tsurumi-ku, Yokohama
Outline of the ~rocess Flue gas is washed with dilute sulfuric acid
which contains a catalyst and is saturated with oxygen. S02 is absorbed
and converted into sulfuric acid. Part of the acid is reacted with
limestone to produce gypsum. The rest is diluted with gypsum wash water
and returned to the absorber.
Description The flow sheet is shown in F.igure .4.13. Flue gas is first
treated by a wet scrubber to eliminate dust and to cool the gas to 60°C.
The cooled gas is led into a packed tower absorber containing 1 inch
Telleretts. Dilute sulfuric acid (2 to 10% H2S04) which contains a
soluble catalyst and is nearly saturated with oxygen is fed to the packed
tower. About 90% of S02 is absorbed, and partly oxidized into sulfuric acid.
t.t8)
-------
Oxidation
Absorption
Crystallization
Vent
Fuel i
Reheater
>0
Water
Centrifuge
Oxidizer
Absor-
ber
I-jake-up
water
Scrubber
Catalyst
Lim -
eto e
/
?
Conveyor
Sulfuric
acid tank
bl,
Blower
Gas
r.jother
liquor
tank
Gypsum
.~ ~ Air bJ b--J
Blower Pump Pump
Pump
Pump
Pump
--
~
Figure 4.13
Chiyoda Thoroughbred 101 process
-------
The produot aoid is led to the oxidizing tower into which air is bubbled
from the bottom for oxidation. Most of the acid nearly saturated with
oxygen is returned to the absorber. Part of the acid is treated with
powdered limestone (minus 200 mesh) at 50 to 55°C to produce gypsum.
A special type of crystallizer has been developed to obtain good crystals
of gypsum 100 to ,00 microns in size. The gypsum is centrifuged from
the mother 1iqucr and washed with water. The product gypsum has good
quality and is salable.
The mother liquor and wash water ~re sent to the absorber. The amount
of the wash water is equal to the amount of water evaporated and lost
from the absorber.
O~eration data of pilot plant Chiyoda has operated a pilot plant with
a I,OOONm'/hr capacity for several months continuously without trouble.
The absorber is 700mm in diameter and 6 meters high. Oil-burning gas
with 1,300ppm S02 and I.Omg(Nm3 dust is treated to decrease the S02
content to lOOppm and the dust content to 0.01g/Nm3. The waste gas tem-
perature is about 55°C. The gas is heated and released through a stack.
The by-product gypsum contains about 97% dihydrate and about 0.6% lime-
stone with no sulfite.
A fiber-reinforced plastic is used for the towers and pipings. Loss of
catalyst is virtually zero. The catalyst is kept a secret, but is said
to be an inexpensive material.
State of development A commercial plant will be built in Mizushima,
Nippon Mining Co. by September 1972 to treat tail gas (0.8% S02) from a
Claus furnace at the rate of 35,OOONm3/hr. In the plant 50 tons of
gypsum will be produced daily. Another plan is afoot to build a plant
to treat 400,OOONm3/hr flue gas from oil-burning boilers. In the commer-
oial plant the towers will be provided with rubber or FRP linings.
Advantages The process is simple and the plant is easy to operate.
Even in the event that the gypsum-producing system has to be stopped for
a day or two for repairs, the absorbing system can be operated continu-
ously. The concentration of sulfuric acid increases by 1 or 2.% in this
case but S02 recovery is not decreased. Catalyst is cheap and is not
poisoned bJ impurities in the gas.
Disadvantages A fairly large absorber is required as shown in the
following table. Large pumps are also required.
(~O)
-------
Table 4.5 Size of towers
(meters)
Absorber Oxidizer
Amount of ~as(Nm3/hrl Diameter Height Diameter Height
200,000 9 15 4.6 19
500,000 15 15 6.4 19
Table 4.6 Investment and desulfurization costs
(S02 content of gas 1,5OOppm,
Investment cost (millions of yen)
Annual cost (millions of yen)
Fixed costl)
Operation cost2)
Revenue from gypsum sale3)
Desu1fUrization cost (yeq/ton of oil)
9~ recovery)
Amount of gas (Nm3/hr >.
200.000 500.000
540 980
9.9
9.8
3.5
1,200
18.6
19.9
8.9
880
1) Including depreciation (14.3% of investment) and interest.
2) Limestone ¥2,OOO/ton. Electricity ¥3/kWh. Water ¥5/ton.
Costs for catalyst. labor, repairs, and managing included.
3) Sale price of gypsum 12.000/ton.
4.10 Kawasaki magnesium processll, 13)
Developer
Kawasaki Heavy Industries Ltd.
16-1, 2-chome, Nakamachidori, Ike~ku,Kobe
Description The process resembles the Chemico process. Magnesium
hydroxide from sea water is used for absorption of S02' Two absorbers
arranged in aeries iive large crystals of magnesium sulfite (Figure 4.14).
The su1f'te formed in the second absorber is further reacted with S02
in the first absorber to form magnesium ti.1sulfi tee The sulfite is then
(J,u
-------
!-- -
,.----.,
I I
, I
I
I
,
I
I
I
L
1
Magnesium oxide
Wa ter
7
,.------,
3
8
Gas to
t
I
I
I
,
, I
-_J
stack
1 : Cooler 2 : First absorber 3 : Second absorber
4 : Crystallizer 5 : Precipitator 6 : Centrifuge
7 : Magnesium hydroxide tank 8: Mother liquor tank
Figure 4. 14
Flow sheet of Kawasaki magnesium process
('2)
-------
treated with magnesium hydroxide in a crystallizer and a precipitator
to produce large crystals (300 to 500 microns) of sulfite which is readily
separated from the mother liquor and also from small crystals of magne-
sium hydroxide. The sulfite separated is calcined to regenerate the
ma~eBium oxide and to release S02. The oxide is recycled to the absorber;
S02 is used for sulfuric acid production.
State of develo ment This process was invented by Mr. S. !kimoto, Osaka
Kobai K. K. Japanese Patent 577,195 July 6, 1970. Patent application
was made in July 1966). Kawasaki bought the patent and, since September
1971, has operated a pilot plant of the absorbing step which is capable
of treating 5,000Nm3/hr flue gas. Pilot plant tests for the regeneration
step will start in January 1912.
-4.11
. 11 12 13)
Grlllo process: '
Developer
Grillo Werke, West Germany
Mitsui Shipbuilding Co.
5-6-4, Tsukiji, Chuo-ku, Tokyo
State of development Mitsui has bought the 502 absorption process from
Grillo and now operates a pilot plant to treat 1,200Nm3/hr gas from oil-
fired boilers.
Description The process consists of an absorption step and regeneration
step. Flue gas is desulfurized by a spray of slurry containing magnesium
and manganese oxides to form sulfides and sulfates of both magnesium and
manganese. The reRction product is dried in a spray dryer. The dried
solid is charged into a furnace for heating at 950°C tu release S02 and
to regenerate magnesium and manganese oxides. The released S02 is used
for sulfuric acid production. The presence of manganese promotes the
decomposition of magnesium sulfate.
Mitsui has developed a special oil-fired furnace for the regeneration.
The details are not published yet.
Cost estimation12) The investment cost for a commercial plant to treat
1,200,OOONm'/hr flue gas from a boiler burping heavy oil (5.5% sulfur)
is estimated at ¥3.3 billion including the cost for a sulfuric acid
plant. The desulfurization cost to remove 92% of 502 is estimated at
¥970/kiloliter oil, including depreciation over a 1-year period.
(IJ)
-------
Flue
".
~
'-
Water
Waste
gas
Figure 4.15
Furnace
Spray
dryer
Grillo-Mitsui process
Cyclone
Electrostatic
precipitator
SOt
Magnesium and
manganese oxides
Chemical treatment
( Dust removal)
-------
4.12
Chemico process (lime scrubbing and magnesium sCrubbing)ll)
Constructor Mitsui Miike Machinery Co.
2-1-1, Muromachi, Nihonbashi, Chiyoda-ku, Tokyo
Lime process A desulfurization plant designed to treat 5l2,OOONm3/hr
flue gas from a coal-fired boiler (165MW) is under construction at Omuta
Works, Mitsui Aluminum Co. Operation will start in March 1912. .The
coal contains 2.5 to 3% sulfur. The power plant, equipped with 8n
electrostatic precipitator, has been in operation for some time.
Chemico scrubbers (two-stage venturi) are adopted. A calcium hydroxide
sludr,o from a plant prcducing acetylene from calcium carbide will be
usca as the absorbent for S02. The by-produced calcium sulfite will
tentatively be used for land filling at the sea shore. Should any water-
pollution problem occur, Mitsui Aluminum plans to install a facility for
o~ictation. This desulfurization plant will be the first large-scale
one in Japan that does not produce salable by-products.
Mae;nesium process Mi teui Miike Machinery Co. ha s been opera ting a pilot
plant designed to treat 2,500Nm3/hr flue gas with magnesium hydroxide
alurry. The details have not been published yet.
4.1)
( 11 16)
Takahax prt'cess H2S recovery) ,
Developer
Kinon Chemicals
3-3, l-chome, Ginza, Chuo-ku, Tokyo
Description Hydrogen sulfide is recovered by an alkaline solution at
pH 8 to 8.5 containi~ a newly developed catalyst 1,4-naphthoquinone-
2-sulfonic acid, which precipitates elemental sulfur rapidly. The
catalyst is readily regenerated by introducing air into the solution.
(~ ~')
-------
Ha 5 + Nal Co, . NaHS + NaHCo,
+ NaHS + NaHCo,
>
..OR
,
CO~ .....50, Na
~I # +
I
OR
Na2 Co, + 5
so, Na
/'
o
OR
00, jo,Na
I + 1/2 Ot
~ h
dH
>
o
00" So, Na
o:?' '
, 1 + HaO
~.
"
o
Air
Cleaned gas
Make-up chemicals
Oxidizing
tower
Absorber
Air
Gas
Filter press
Figure 4.16
Two-tower system, Takahax process
More than 99.8% of hydrogen sulfide in coke oven gas, petroleum gas,
etc. is recovered. 1,4-naphthoquinone is recovered easily from the sludge
by-produced when phthalic anhydride is produced from naphthalene. It
can also be directly synthesized at a high yield. It can be easily con-
verted to l,4-naphthoquinone-2-sulfonic acid, which is soluble in water.
Two towers--absorber and oxidizing tower--are used for the cleaning of
fuel gas, etc. For the desulfurization of waste gas, one tower is used
into which both air and the gas containing hydrogen sulfide are introduced.
fJ,6)
-------
11)
Oper.ati0n data The followine values have been adopted recently as
opor~tine conditions.
Power requirement
40kg/kl as Na2C03
8 to 8.5
1.5 to 2 mOles/kl
22 gas/licruid
0.55 liquid/air
Catalyst:O.02 mole/kg of
recovered sulfur
Alkali: 0.15kgJkg of recovered
sulfur
0.05kWh/m3 gas
Alkali concentration
pH
Catalyst concentration
Liquid-cas ratic
Liquid-air ratiu
Make.up chemicals
State of development The process haa been adopted recently in about 60
plants in Japan including Mitsubishi Chemical's Sakaide plant, where it
treats 85,OOONm3/hr coke oven ~as and Sumitomo Metal's Wakayama plant, for
treatment of 200,OOONm3/hr coke oven gas.
The process has undergone improvement recently. The imprcved process
will be used for Nippon Steel's Nagoya plant, where a unit is being built
to treat 400,000Nm3/hr coke oven gas.
Economics The Takahax process and the Thylox process are compared below
with regard to investment and operation costs. The investment cost for
treating 10,00Qm3/hr for 5e/m3 H2S by the Takahax process is as follows&
Remote-control system
¥70,930,OOO
¥62,890,OOO
Field operation system
On the other hand, the Thylox process costs ¥94,370,OOO, or about 4cr~
more. The operation cost per cubic meter of raw gas calculated from
fixed and variable costs is:
Takahax process
about ¥0.23
about ¥0.46
Thylox process
The Thylox process requires an additional expenditure of ¥0.2l or so for
arsenic removal.
r"J
-------
Advantages.
Both investment and operation costs are low.
Very high recovery of H2S--more than 99.~-is attained.
Operation is so easy that unattended operation is possible.
The catalyst is not poisonous, so that the by-product sulfur is useful.
Possible application The Takahax process has so far been utilized chiefly
in the town gas industry and iron industry, especially for the desulfuri-
zation of coke oven gas. Since the catalyst is highly stable and active,
the process is thought to be applicable to various gases regardless of
th~ concentration of hydrogen sulfide, for example for the recovery of
hydrogen sulfide from hydrodesulfurization of heavy oil as well as the
sulfide in tail gas of Claus furnace. Also in treating waste fermenta-
tion ~ae, the process is utilized to give methane gas which may be used
as a heat source for boilers.
The Takahax process may be helpful in removing heavy metals in wastewater
by usinp, hydrogen sulfide which is quite effective in precipitating heavy
metals but has not been used for that purpose because of the difficulty
in treating the gas released to the air.
ll)
4.14 Other wet processes
Sodium hypochlorite process Hitachi Shipbuilding & Engineering Co. has
operated recently a pilot plant (500Nm3/hr gas) to absorb S02 with a
sodium hypochlorite solution which oxidizes S02 and converts it to sul-
furic acid. Limestone is added to precipitate gypsum. The remaining
sodium chloride solution is subjected to electrolysis to regenerate the
hypochlori tee .
MaRneaium hydroxide process Tsukishima Machinery Co. has developed. a
wet process using magnesium hydroxide slurry. The details have not been
published yet.
w')
-------
5 Waste-gas desUlfuriZatiO~
5.1 Mitsubishi DAP-Mn processll, 17)
process
Developer Mitsubishi Heavy Industries
5-1, 2-chome, Marunouchi, Chiyoda-ku, Tokyo
Description Activated manganese oxide MnO .nH20 in powder form (5 to
150 microns in size) is charged into an ab~orber, and is dispersed and
oarried by flue gas. The powder i9 caught by a mult1clone and electro-
static precipitator with an efficiency of 99.99%. The total pressure
drop of the gas is 100 to l50mm H20. About 90% of S02 in the gas is
removed forming magnesium sulfate. The powder oaught is a mixture of
the oxide and sulfate. Most of the powder is returned to the absorber.
The rest is treated with water to dissolve the sulfate; the unreacted
oxide which is insoluble in water is centrifuged and returned to the
absorber. The manganese sulfate solution is treated with ammonia and
air to precipitate activated manganese oxide. The mother liquor is
concentrated to obtain solid ammonium sulfate which has more than 99%
purity.
State of development A prototype plant to treat l50,OOONm3/hr flue gas
from an oil-fired boiler was completed at Yokkaichi, Chubu Electric
Power, in 1967 under contract with the Agency of Industrial Science and
Technology. A semicommercial plant to treat 330,OOONm~/hr gas (llOMW
equivalent) has been completed recently at Yokkaichi.
Economics The investment cost for the semicommercial plant (llOMW) is
11.4 billion. The desulfurization cost would i-rl,a 12,000 per kiloliter
oil. be abollt
Advantages
The absorbent, which is highly reactive and in powder form, enables S02
to be recovered at a high rate.
Pressure drop through the absorber is only 10 to 20mm H20.
pressure drop does not exceed 150mm H20.
The total
Temperature drop in the gas is also small.
desulfurlzation is kept above 110°C.
The gas temperature after
Di sa dvantages
The desulfurization cost ~8 relatively high.
Demand for ammonium sulfate is decreaeing.
( 6'f)
-------
~
I Vent
Water
Scrubber
Waste gas
to stack
Absorber
M.C.and
Regenerater
Flue gas
Crystallizer
Filter
~
Filter
.t~
I
I
.
, Dissolver
.
I
,
I
I
,
: £Sir i
L- - ,
.
- - - - - -- - --'
,
--~
Ammonium
sulfate
Disintegrator
r-
-a
.....
Aqueous
ammonia
I
------ -- -- -..
Figure 5.1
Flow sheet of activated manganese oxide process
-------
11 l~)
5.2 Hitaohi activated oarbon prooess 0"
Developer Hitaohi Ltd.
2-8, Otemaohi, Chiyoda-ku, Tokyo
Description S02 in flue gas is absorbed by aotivated carbon. The carbon
is then washed with water to release dilute sulfuric acid (about 20% H2S04)'
1511,000 3
State of development A prototype plant to treat }::5eNm /hr flue' 68S from
an oil-fired boiler was built in 1968 at Goi works. Tokyo E1eot~io Power.
Five towers packed with activated oarbon were used alternatively for
absorption, water washing, and drying. Tests on ooncentration of the
product acid to 65% H2S04 were also oarried out using submerged combus-
tion (Figure 5.2).
4f-20, 000
A semicommercial plant to treat ~Nm3/hr flue gas from an oil-fired
boiler (150MW equivalent) is under construction at Kashima works, Tokyo
Electric Power at a cost of 11.7 billion. The plant will be put into
operation by September 1912. Six towers with three compartments each
are used in two trains. (Three towers with nine compartments form one
train). The gas from electroataticpreoipitators containing eOOppm S02
and less than 3Omg/Nm3 of dust at a temperature of 135°C will be
introduced in the absorbers to remove 80% of 502 while maintaining the
outlet gas temperature above IOD°C. Dilute sulfuric acid (2~~ H2S04)
will be produced at a rate of 5.9 tonsjbr which will be treated with
powdered limestone to produce salable gypsum at a rate of 2.3 tons/hr.
The plant will consume 3,9ODkW power. 1.2 to~hr of limestone and 25 tons/hr
of wa ter.
Advantages
The temperature of the desulfurized gas is kept above lODoC.
The process is simple and operation is easy.
The dust in the gas adhered to the carbon is washed away with water to
maintatn the aotivity of the carbon.
By-prQduct'gypaum is of good qualit~and'salable.
Disadvantages
Investment cost is relatively high.
Oversupply of gypsum is like~ several years from now.
(71 )
-------
Fl ue gas
Drying and washing steps
Stack
Blower
--,
I
I
I
I
JJ :
I
I I
I I
I I
I I
: Water I
-----~
Tank Pump
Dust
collector
Dampe
Concentrater
I~ - - - -
I Filter
Q
-- U -, II
Q ~ Cake coolerd
Tank
Figure 5.2
Flow sheet of Hitachi process ( 150,OOO~/hr)
5.3
12 13)
Sumitomo aotivated oarbon process'
Developer
Sumi tomo Shipbuilding and Machinery Co. Ltd.
2-1, 2-ohome, Otemachi, Chiyoda-ku, Tokyo
Desoription Moving beds of activated carbon are used for S02 recovery.
The flow sheet is shown in Figure 5.3. Granular activated carbon descends
slowly through an absorber into which flue gas is introduced perpendicularly
to the oarbon stream. The oarbon which absorbed 502 is discharged from
the bottom of the absorber and is led into a desorber through which the
(72)
-------
oarbon again descends slowly. A recyling gas heated in a heat exchanger
is introduced into the desorber perpendicularly to the oarbon stream
for desorption. An inert gas or reduoing gas is introduced to purge the
502 gas. S02 concentration in the purged gas is controlled between 10
and 20%. A porticn of the purged gas is led to a sulfuric acid plant;
the rest is recycled to the desorber after being heated in the heat
exchanger. Tail gas from the sulfurio aoid plant which contains S02 is
introduced into the absorber.
State of development A pilot plant to treat lO.OOONm'/hr flue gas was
built in 1968. A prototype plant to treat l15.000Nm'/hr gas was built
recently at Amagasaki works, Kansai Electric Power Co.
Advantages
The process is fairly simple and is operated safely.
The continuous cross-flow of gas and carbon ensures a high efficiency
of absorption and desorption.
Disadvantages
Carbon consumption is considerably high.
The desulfurization cost may be high as well.
( VJ)
-------
Flue gas
r-
I
I
Activated I
__c~bo~~
F
) Gas
r,~,
,
,
,
,
,
,
,
,
To stack
/
/
/
/
/
/
/
/
D
I
I
I
I
'¥
A ,
I
I
..v
/
, /
, /
:-
/ ,
/ ,
,
~,
,
,
/
/
7/
/
/
/
/
/
/
/
--/
E
,
,
,
, I
, I
'"
M
Oil
- - -- ~ Activated carbon
A : Absorber C : Converter
D : Desorber E : Heat exchanger
H : Hot-air furnace M: Multiclone
CW : Cooling water
F : Fan
S : Vibrating screen
l'igure 5.3
Flow sheet of Sumitomo Shipbuilding -
Kansai Electric process
(7tJ
-------
5.4
11 13)
NRIPR active sodium oarbonate prooess '
JJeveloDer
National Research Institute of Pollution and Resouroes
188, Kotobukioho', Kawaguohi-shi, Saitama l'refoc brc
ent Pilot plant, tests were carried out, desulfurizing
flue gas. Tests on regeneration are in prOgr~ss.
DescriDtion An absorber in the form of an inverted U l5.5cm in diameter
and 25 meters in length is used in the pilot plant. Light-weight soda
ash (or sodium bicarbonate) in powder form is charged into the absorber
and carried by the flue gas at a temperature between 500 and 350°C and
a velooity of 5 meters/sec. About 110 to 120 grams of sodium carbonate
is charged per Nm3 gas. Nearly 90% of 802 is removed by reaction with
the carbonate. The reacted powder which is a mixture of sodium sulfate
and carbonate is caught by sedimentary and electrostatic precipitators.
Most of the powder is returned to the absorber; the rest is subjected
to regeneration.
3
-GJ--,~
I
1: Absorbent tank
2: Feeder
3: Absorber
4: Cyclone
H,S
co
II,
5: Electrostatic
precipitator
6: Air heater
7: Absorbent tank
8: Regenerator
Nal Co,
9: Carbonation tank
10: Filter
10
Figure 5.4 Flow sheet of NRlPR sodium carbonate process
(,W)
-------
The regeneration teats have been carried out by using a melt reduction
process. The powder is charged into a hot reducing gas obtained by
partial combustion of oil. Sodium sulfate is reduced rapidly to form
molten sodium sulfide. The sulfide is then treated with steam and carbon
dioxide at about 400°C to recover soda ash.
Na2S + H20 + C02 = Na2C03 + H2S
It is a1ao possible to carry out this reaction in an aqueous solution.
Sodium carbonate thus regenerated is returned to the absorber. Hydrogen.
sulfide can be converted into sulfur by a conventional process.
Advantage and disadvantage High recovery of S02 can be attained due to
the high reactivity of the light-weight soda ash. The regeneration
process is not simple and seems to be fairly expensive.
5.5
Shell process (Cupric oxide process)11,13)
Constructor
Japan Shell Technology Co.
~ Showa Yokkaichi Sekiyu, Yokkaichi Plant
Description S02 in flue gas at 400°C is absorbed by cupric oxide held
by an alumina carrier. The cupric sulfate thus formed is then reduced
with hydrogen to release 502 and regenerate the cupric oxide.
CuO + S02 + 1/2 02 = CuS04
CuS04 + H2 = CuO + S02 + H20
Two towers packed with the cupric oxide-alumina absorbent are provided,
the two alternating between absorption and regeneration every hour.
State of development A plant with a capacity to treat l20,OOONm)/hr flue
gas from an oil-fired boiler will be built by March 1973 at the Yokkaichi
refinery, Showa Yokkaichi 5ekiyu Co. The 502 gas recovered will be led
into a Claus furnace to react with hydrogen sulfide gas from the refinery
to produce elemental sulfur. This plant will be the world's first com-
mercial plant to use the Shell proc~ss; Shell has made pilot plant tests
in the Netherlands to treat I,OOONm /hr gas.
(76)
-------
Heat recovery
) Stack
400.C
r--"------~1
I
-------
6 Economic aspects
6.1 Supply, demand, and price of sulfur and.its compounds
Supply and demand In 1970 supply of sulfur and its compounds totaled
nearly 2.9 million tons as sulfur (Table 6.1). Pyrite vas the major
source of sulfur. Production of sulfuric acid registered nearly 7 million
tons (nearly 2.3 million tons as sUlfur). About 60% of the acid was
produced from pyrite and about 4~~ from smelter gas. The supply of pyrite
will decrease year by year with the increase of smelter gas.
Table 6.1 ~timated supply of and demand for su~fur and
its compounds (1,000 tons as sUlfur)3)
1970 1971 1972 1973 1914 1975
Supply
Pyrite 1,475 1,465 1,427 1,376 1,515 1,245
Smelter cras 1,042 1,233 1,338 1,508 1,693 1, 890
Mined sulfur 109 56 36 0 0 0
Recovered su1fur* 270 375 570 608 '" 942 763 "-1,282 795'~ 1,625
Total 2,896 3,151 3,277 3,513"- 3,847 3,766,,-, 4, 285 3,930.", 4,187
Demand
Sulfuric acid 2,289 2,428 2,525 2, 626 2,731 2,840
}!;lemental sulfur 326 335 342 348 357 365
S02 (1i.quid) 150 155 160 160 160 160
Other* 108 138 169 211 255 305
Total 2,873 3,056 3 , 1 96 3,345 3,503 3,670
Surplus 23 73 79 137"~481 263"" 782 260"- 1,117
* Including by-products of waste-gas desu1furization
Mined sulfur is scanty and decreasing. Recovered sulfur and its compounds
by-produced from hydrodesu1furization of oil and waste-gas desulfurization
will increase remarkably and reach about 1 million tons BS sulfur by 1915.
(70
-------
The consumption of sulfur and its compounds is expected to increase by
about 5% yearly. Considerable amounts of by-products from vaste-gas
desulfurization will be utilLed. For example, in 1915 nearly 1 million
tons of gypsum (about 180,000 tons as sulfur) obtained from waste-gas
deeulfurization is expected to be used for cement and wall board. The
deman~ for sodium sulfite is estimated to increase from 310,000 tons in
1910 to 590,000 tons in 1915. Still a considerable oversupply of sulfur
and its compounds is expected in th~ near future due to the increase of
desulfurization plants. Sodium sulfite is already reported to be in
overproduction.
Price of sulfur and its compounds
DemCln~ fOI" und price of sulfur and its compounds in Japan in 1969 are
shown in Table b.2. The prices of sulfuric acid and elemental sulfur
were slightly higher in 1910 but was considerably lowered in 1911 due to
an oversupply. It seems that the prices of sulfur and its compounds
would continue to decrease in future.
Table 6.2 Demand ~nd price of sulfur and its compounds in 196918)
Demand
(1,000 tons
6, 800
}80
},510
400
180
1, 200
10 to 20
of materiall Price (¥/ton).
8,000
21,500
3,000 to 5,000
16,500 to 11,000
10,000 to 30,000
14,000
30,000
Sulfuric acid
Elemental sulfur
Gypsum
Sodium sulfate
Sodium sulfite
Ammonium Bulfate
Liquid 502
6.2
Cost of ~~drodesu1furization
Topped-crude hydrodesulfurization The investment and operation costs
for a topped-crude ~drodesul~izatiDn plant with a capacity of 50,000-
BPSD was reported as fo11ows.5)
l7~)
-------
Heavy 011
)
7,949k1/day
(8=4.1%)
Sulfur
recovery
Sulfur 238t/day
Fuel gas l18k1/day
Naphtha )
387k1/day
Naphtha l06kl/day
Desu1furized heavy 011(8=1.0%)
7,909kl/day
F1gure 6.1
Mater1al balance in topped-crude hydrodesu1furization
(Khafj1 heavy 011 50.000BPSD)
Table 6.3
Investment cost for topped-crude hydrodesulturiza tion
plant (50,000 BPSD) (millions of yen)
~drogen Sulfur
Desu1furization production recover.y
1,600 490
169 17
151 22
6,350
1,020
781
140
8,291
1,920
529
Total
8,440
1, 206
954
140
10,740
Equipment
Patent fee
Catalyst,
Land
Tots 1
chemicals
((1))
-------
Table 6.4
Operation cost for topped-crude hydrodesu1furization
piant (50,000 8PSD) (fl,OOOjday)
Hydrogen Sulfur
Desulfuri za tit'n producti,-n recovery Total
l"ixed cost* 1,220 1, 110 410 9,460
Variable coat 6,540 4,650 -220 10,910
~ubtota1 13, 1hO 6,420 250 20,430
By-product credi t** -1 , 710 -2,620 -4,390
'rotal 11 , 990 6,420 -2,310 16,040
* Operation 1~~ of total hours (about 6,100 hours a year)
** Naphtha ¥G,~OO/kl; Sulfur Yll,OOO/ton
Vesu1furization cost is calculated as ¥2,020/kiloliter Khafji heavy 011
when the plant is operated for 70% of total hours (about 6,100 hours a
yp.ar) and about ¥l,870 when operated for 8~ (about 1,000 hours a year).
The price of high-sulfur heavy oil (sulfur 3 to 4%) is about ¥5,000/kiloli ter
an~ that of desu1furizAd heavy oil (~fur 1 to 1.5%) is about '6,500.
The difference by the desu1furization is less than the desulfurization
~ost. To encourflge oil refiners to practice desu1furization, the Japanese
Government subsidizes the refiners at a rate of 1500 per kiloliter 011
subjected to desu1furization.
Vacuum gas-oil desu1furization The investment and operati~n custs for
a vacuum gas-oil hydrodesulrurization p1~nt with a capacity of 50,000-
BPSD of Khafji heavy oil are as fol1ow~
Sulfur
Sulfur
120t/day
)
Fuel gas
kJ../day
Heavy
oil
;)
Vacuum
distil-
lation
Vacuum gas 011
Deau1fu-
r1zation
recovery
7,949
kl/day
(5=4.1%)
4, 57Ok1/day
(8=3.1%)
Residual oi1
},397k1/day
Naphtha 92kl/day)
Desul!urized 011
4,4?Okl/day(5=0.2%)
Hydrogen
production
Heavy oil
?,849kl/day
(5=2.6%)
Hydrogen
0.43 x 1d Nm'/day
Figure 6.2
Material balance in vacuum gas-oil hydrodesul!ur1zat10n
(Khafj1 heavy 011 50,OOOBPSD)
(ro
-------
Table 6.5
EqIJipmcnt
Patent fee
Cutalyst, ohemicals
Land
Totfll
Table 6.6
~'ixeil cost*
\/I.tr.iable cost
Subtotal
By-product qr.edit**
'rotal
Inve3tment Ci..~st for vacuum p,as-oil hydrodeslllf'urization
plant (50,000 BPSD) (millions ~f' yen)
Vac~um Desu1furi- ijydrogen Sulfur
distillation zation ~roduction recovery Total
1,170 2,700 816
o 300 55
o 108 49
140
3,248
322
6
11
1,170
920
339
5,008
361
168
140
5 , 677
Operation cost of VGO hydrodesulfnrizatiC'!'I (n,ooo/day)
Vacuum
distillation
900
950
1,850
o
Desulfuri- d3drobe~
zation production
Su1f'ur
recovery
260
2,480
930
3,410
-1,000
2,410
740
1,520
2,260
o
-80
180
-1,320
2,260
1,850
-1,140
* Operation OQ1~ of total h~urs (ab0ut 1,000 hours. a year)
** Naphtha Y6,OOO/k1j Sulfur fll,COO/ton
Total
4,380
3,320
7,700
-2,320
5,380
The desulf'urization cost is calculated as '680 per kiloli ter cf ~eavy C'11
or ¥1,180 per kiloliter of' vacuum gas oil to be subjected tc des~lfuriza-
ti7~. The Japane3e Government offers subsidies of 1500 per kilcliter
:: vacuum gas oil ~lbjectad to desu1furizati~n. Although desulfurization
~~3t is much lower for VGO dOBUl~lr.ization than for TC desulfurizativn,
the use of residual oil from vacuum distillation poses a big problem as
has been mentioned already (3.5).
6.3
Cost of flue-Ras desulfUrization
Deeulfllrization costs for six flue-gas desu1furization processes are
comparltd in Table 6.7. Among them, only the Wellman-Lord process lind
Ku~eha process are now in commercial operation. Therefore, the ~" ta in
the table may not be quite accurate. The table indicates that
deaulfurization cost is less for wet processes than for dry processes.
(f2)
~
\
-------
Table 6.7 Comparison or de8U1~riz8tion costs12)
,Wet Drace.8 Dry process
Wellman- Hitachi Mitsubishi Sumitomo
Kure~ Lord Chemic 0 carbon manganese carbon
pnwe1" plant (MW) 100 250 1,200 250 250 58
Amnunt nr eas }OO 750 ',600 750 750 174
(l,OOONm3/hr)
~ulrur in oil(~) 2.8 '.0 ,., '.0 '.0 2.0
Zul f'ur removel'($G) 95 90 80-90 80 80 90
, ' Investment cost 0.42 1.14 4.0 2.4 1.9 0.85
(billions or yen)
ily-product Na2S0, H2S04 H2S04 H SO ** (NH4)2S04 Q2504
2 4
Dc:m1 rl1rization
f1nst(f/kl oil)* 500 070 780 1,300 1,100 2,560
. Includinc depreciation tor 7 lears.
** Glpsum 1s produced with the acid.
J)oolllf'l1rization cnst is the lowest tcr the ~eha prOCeS8, which by-produces
t1ndium sHltite. 3uppl1 c,t sodium Gultite, however, 1s alread¥ in excess
of demand ilt Japan. Al thoueh QP8U8 and concentra te
-------
Brdih hydrndesulfurizution and flue-cas desulfurizatioll are likely to continue
thoi.J~ present rapid ljrowth in Japan for a few more years; in tho meantime
~a~irication desulfurization of oil is expected to be comme~cifilized.
'l'he ai tua tion may take a turn several years from now t when oversupply of
oulfur and its compounds assumes serious proportions.
(It)
-------
I'able
6.9 ;;ost c: f'.1e1 3.:-_~. ~e"nl~'.1=:za::.::;:-- (:,'):)01'~,,, ;/':",;:::'
~
? ..,~O _1'11; ~.,.., 1 ~... ':>"'s ~.. ....;, ,..,...) :)"'" ..,~ 11;"'''' . --;
-,I"" -- --"'.--~"'-. v- ""'-- -- -" .1_' ---. _....1......
plar::. ?la1 ~cns'.1::?ti~:-: is
... -.-. 1 '19)
:: ~~.; year Y I
rC'ppe~=-..de
~y~~des~lf~izatic~
Sulfur in fuel ({o)
Sulfur removal (;~)
SC2 in flue gas (ppm)
Cost of fuel (Ye~k1 or Nm3)
Cost of fuel (Billion ye~year) (D)
rnvest~ent cost (Di11iora of yen)
Desu1furization cost (Billion ye~year)(C)
Total cost (3 + C) (Billion yen/year)(~)
~y-products credit (Billion yen/year)(E)
ilet cost (D - E) (Billion yeq/year)
~'..\'....ai t
~eavy IJil
3.1
7 I,
600
5,000
13.65
9.97
5.34
18.99
1. 24
11.75
A1:afji
~ea vy "il
4.1
7{.
,~
600
5,000
13.65
10.74
6.16
19.81
1.46
18.35
(A) By Wellman-Lord process
(~) rnc1u1in~ 23~ of investm~n~ ~ost
-
01)
:z
i'1'..l~s
1e3~lf'.l:.:'izat:cn(A)
ca:ji
~ea'!y :>il
4.2
?~
250
5,000
13.55
10.10
4.73
19.43
1. 52
16.91
~4:ji
asphalt
5.5
93
250
4,000
10.92
11.23
5.72
16.54
2.08
14.56
'ii t~o:.;. t
iesulf'..u-iza tLn
Zieavy oil
(Standard)
2.0
o
1,200
5,000
16.38
°
o
15. 38
o
15.38
Hi~.as
cr'.lde oil ~
0.1
o
60
7,000
19.11
°
o
13.11
o
19.11
o
o
o
3.5
24.65
6.0
1.88
26.53
o
26.53
-------
Herercnoes
1)
~'O~J~ii Tokei (Ene~GY Statistics), Ministry of Intern~tional Trade
:!n~ Industry (l>UTI) (1971)
2)
IHppon No Enerur.;ii Mondai (Ji:nergy Problems in Japan), l'sushf'sCHlGYo
Kenkyu, No. 160, IvlIT.l (1971)
3)
A. Matsumoto, Aacaku Keizai, pa~e 27, Oct. 1971
4)
'l'eiyuo Bnnkakni H.okoku (Report of Subcomi ttee fer 03ulfur iJiminishinc
Pnlicy, Advisory Comittee for Enerr,y) l>UTI, Dec. 1969, revise~ i~
June 1970.
~)
¥. Oi,atn et. a1., Juyu Haien Datsur~~ ~ijutsu (T~chnr10~y ~~
Do:mlfurizaticn 0f lienvy Oil and Stack lias), Nikkan A,("'If'.yc .3'hinDLL'1, 1971
(;)
7)
H. ¥csni1n ani ::). S11zuki., har;aku Koljt1ku, j!, 1,:'51, 1?70
'i. 1{n sahara, Kar,'aku Kot';aku, 2!, 1,257, 1970
.", )
,)
~. ~lt0, Tokoshi N~lSU (~ews 0f Government Che~ical Researc~ institute,
Tokyo) 2' 130, 1971
9)
K. lik':i an~ h.. l~tsumoto, Chemical EconoII\Y a:ld ~1t!il"'.eerinc Review, Nov.
1970 (in ~lish)
10)
11)
G. Nawata, Encrut;ii .Nov. 1971
P~ivat~ commnnication
1'2)
lil.licndatzuryu l~o Ji::::sai (Pract.ice of Stack \iu.J .Desn1t'nrbati::n) C~:lC'
~~<.:t::m.k;mri 4'~ikai, Oct. 1971
1~)
H:liendatsuryu \iijutsu (Technoloc.Y of 3tack lias liesu1furizaticn)
Mc:akukoG'ynsha, 1970
14)
15)
Y. Tsushima, Byrum \iijutsu, ~, No.6, 1971
T. Aki, Technical Conference Report, Byusan ~0kai, Oct. 1971
1.(; )
N. ilasebe, Chemical Econom.Y and Engineering Review (pa~e 27), Nar. 1970
(in EnGlish)
{ f"
-------
17) ~. Yoshimochi and K. Kamel, ibid. paGe 22, Mar. 1970
(in English)
10) K. ~lrosawa, KoCaiboshi San6Yo, Sept. 1971
19) K. KurosQwa, Kacukukojo, Nov. 1971
(17'
------- |