Pilot Plant Experiment on the Treatment of Exhaust Gas from a Sintering Machine by Electron Beam Irradiation Keita Kawamura* I,Shinji Aoki', Hitoshi Kimura, and Kyojiro Adachi Central Research Institute, Ebara Corporation, 4720, Fujisawa, Fujisawa-shi, Kanagawa, Japan
Kazuo Kawamura and Tsutomu Katayama Environmental Technology Center, Process Technology, R&D Laboratories, Nippon Steel Corporation, 1-1, I-chome, Edamitsu, Yawata-Higashi, Kitakyushu, Fukuoka, Japan
Katsumi Kengaku and Yasuhiro Sawada Plant Engineering and Technology Center, Nippon Steel Corporation, 2-6-3, Ote-machi, Chiyoda-ku, Tokyo, Japan
In order to verify the performance of the process for exhaust gas treatment by electron beam irradiation on an expanded scale and t o study experimentally the applicability of this process to the treatment of exhaust gas from a sintering machine in a steel plant, a pilot plant with a capacity of 3000 Nm3/h (maximum gas flow rate, 10 000 Nm3/h) was set up, and experiments over a period of 1 year including 1-month continuous operation were performed. The results showed that this method qualified as a dry process capable of removing NO, and SO, simultaneously from exhaust gas of a sintering machine. The 1-month continuous operation a t a dose of 1.5 Mrad was successfully performed without any breakdowns. NO, removal of about 80% and SO, removal of more than 95% were both steadily obtained during the entire period of the test run, with emissions to the atmosphere staying within the range of 10-50 ppm "3.
+
In the field of current NO, ( = NO Nos) removal technology, dry processes are more advanced than wet processes. Among the dry processes, selective catalytic reduction using NH3 as a reducing agent is most common, and more than 20 practical-scale plants of this type are reported to be under operation in Japan (1). Many of these plants are, however, intended to treat so-called clean exhaust gases alone, which are almost free from sulfur oxides (SO,) and dust components, and have already undergone 1-2 years of operation (1). Therefore, technical problems with the treatment of such gases may be considered to have been virtually solved. On the other hand, the treatment of exhaust gases containing certain amounts of SO, and dust, which are, for instance, emitted by combustion of heavy oil, still involves problems such as catalyst plugging and deterioration and heat exchanger corrosion due t o acid ammonium sulfate (NH4HS04). Exhaust gas from a sintering machine in a steel plant is more difficult to treat than heavy oil combustion gas because it contains a variety of dust components, in particular potassium salts that are reported to seriously deteriorate catalyst activities (2). Thus, the application of any denitrification process to exhaust gas from a sintering machine has not yet been promising without the aid of a SO, -removal process, which will remove these salts as well as SO,. In recent years, the energy crisis has brought about the reevaluation of coal as a n energy source, and coal-fired power stations are expected t o increase rapidly over the years t o come. However, exhaust-gases from the combustion of coal contain exceedingly large amounts of SO,, NO,, and dust. Therefore, the development of a technique to remove all these pollutants is essential for public acceptance of coal-fired power stations. From the standpoint of simultaneous removal of NO, and SO,, wet processes for SO, removal, which are popular Present address, Plant Engineering Department, Ebara Corporation, 11-1, Haneda Asahicho, Ota-ku, Tokyo 144, Japan. 288
Environmental Science & Technology
now in the world, have a disadvantage in that they cause the gas temperature to fall lower than the range the dry denitrification process requires for satisfactory operation. The process for exhaust gas treatment using an electron beam, developed through joint research between Ebara Corporation and the Japan Atomic Energy Research Institute ( 3 4 ) ,is a dry method capable of simultaneous removal of NO, and SO,. In addition, this process works well in spite of the presence of various substances in the exhaust gas, because the process uses no catalysts subject to deterioration. However, in relation to exhaust gas treatment from the sintering machine, NO, and SO, removal cannot be easily predicted, because the influence of other coexisting components such as CO and 0 2 on the oxidation of NO, and SO, in this process is still unknown. If this process could also remove both NO, and SO, in exhaust gas from the sintering machine, as in the case of heavy oil combustion gas, it may be regarded as a technological breakthrough in the field of gas treatment. It was the aim of the research reported here (which was performed as joint research between Ebara Corporation and the Research Association for Abatement and Removal of NO, in the Steel Industry; managing company, Nippon Steel Corporation) to experimentally study the applicability of this process to the simultaneous treatment of NO, and SO, in exhaust gas from a sintering machine in a steel plant with a pilot plant of an expanded capacity 3000 Nm3/h (maximum gas flow rate, 10 000 Nm3/h) ( N = normal) and to further investigate its overall performance in continuous operations.
Reactor Design The reactor was designed to be a vertical, hollow cylinder with a pair of foil windows (30 p m thick) oppositely located nearly a t its mid-height portion, through which electron beams were to be taken into the reactor. The windows were made of a titanium-palladium alloy so as to resist corrosion by acids, and they were designed to be replaced by remotely controlled hydraulic drive if broken during irradiation. The windows were provided with a cooling system by means of an air jet so as to remove heat caused by electron incidence. A reactor diameter of 2.6 m was adopted so that electrons entering the reactor and being diffused by gas molecules would not hit the reactor inner wall. Such contact with the wall was considered undesirable because one of the essential economic factors being evaluated was the proportion of electron power that can actually be absorbed by the gases in the reactor. At the reactor inlet, a n impeller was installed to rotate the gases, since the measurement of electron distribution in the atmosphere suggested a considerably heterogeneous distribution of electron dose in the reactor. In order t o prevent the occurrence of condensed water a t lower temperatures in the reactor and t o prevent a decrease in efficiency of NO, and SO, removal at higher temperatures, the reactor wall temperature must be kept within a proper range, The reactor was, therefore, equipped with a jacket to 0013-936X/80/0914-0288$01.00/0
@ 1980 American Chemical Society
Table I. Gas Analyzing Methods method instrumental item
chemical
Zn-NEDA method ( 7 ) arsenazo-Ill method (8) Nessler method (9)
nitrogen oxides (NO,) sulfur oxides (SO,) ammonia (NH3) nitrous oxide (N20)
UV meter UV meter CLD meter
CLD meter NDlR meter CLD meter
magnetic oxygen meter NDlR meter NDlR meter
magnetic oxygen meter
gas chromatography
oxygen ( 0 2 ) carbon monoxide (CO) carbon dioxide (C02) products moisture a
EP8 outlet
reactor inlet
gravimetric method
EP, electrostatic precipitator.
UV, ultraviolet rays absorption. CLD, chemiluminescence detection. NDIR, nondiffractive infrared rays absorption.
Mom M
Drain V c c m tonk
M
P
Figure 1. Flow diagram of the pilot plant (gas flow rate, 3000-10 000 Nm3/h)
control its wall temperature by air flow, and several probes were put on the wall €or monitoring the temperature.
Procedure The flow diagram of the pilot plant is shown in Figure 1. The temperature of the exhaust gas that branched from the main flow was first regulated either by the cooling tower or by the heat exchanger. Then the gas was introduced, through the mixing chamber, into the gas-analyzing room, where the contents of NO,, SO,, and other components were measured with both instrumental and chemical methods-all methods (7-9) used are listed in Table I, and typical gas compositions are shown in Table 11. Thereafter, NH3 was added to the gas before entering the reactor in the irradiation room; the amount of NH3 was automatically controlled by the flow rate regulator connected with the NO,-Sop meter. The gas flow was rotated a t the reactor inlet, and then irradiated by electron beam. During the irradiation, NO, and SO, along with NH:I were converted into an aerosol containing sulfur and nitrogen, which turned into a white powder on the Table II. Typical Composition of Tested Gases dust, NO,, ppm
NO, ppm
NO2, ppm
183
181
2
so,,
ppm
190
02,
%
COP, %
H20,
%
Nm3
15.5
16.2
10.3
40
rngl
way to the electrostatic precipitator (EP) installed outside the irradiation room. The powder was separated from the gas by the EP, and the cleaned gas was returned to the main gas flow after determination of the decreased contents of NO,, SO,, "3, and dust. The following denotation was used in the description of the results. Efficiency of NO, removal ( 7 ~ 0 ~ ) :
where c = (21.0% - [ o p ] ~ . ~ ~ ) / ( 2 1-. 0[ 0%p ] ~ p - ~ ~[NOxIR-in t), is NO, concentration a t the reactor inlet (ppm), [ N O , ] E P - ~ ~ ~ is NO, concentration a t the E P outlet (ppm),C is the compensation coefficient for air leak a t the EP, [ 0 2 ] R . l n is 0 2 concentration at the reactor inlet (%I, and [O&p.out is 0 2 concentration a t the E P outlet (To). Efficiency of SO, removal ( 1 7 ~ 0 , ) :
where [So,]~.i, is SO, concentration at the reactor inlet is SO, concentration at the E P outlet (ppm) and [SOx]~p.out (ppm). Exhaust NH3 =
c ["~IEP-~~~
Volume 14, Number 3, March 1980
289
(Verticol cross-section) (Horizontal cross-section 1 F k t r o n beam
W
Figure 2. Dose rate distribution in the reactor (accelerating voltage = 600 kV)
where [ N H ~ ] E Pis. ~NH3 ~ ~ concentration a t the E P outlet (ppm). Ratio of added NH3 to stoichiometric quantity
R N H =~
LN
p-8-* ' ' * sox ' '
.o
1
H ~
I[NoxI~-in+ ~ [ S O ~ I R - ~ ~ I G ~ O - ~ where L N His~the amount of added NH3 (NL/h) and G is the gas flow rate (Nm3/h). Operational Performance
Dose Rate Distribution. The dose rate distribution in the reactor irradiated by 600-kV electron beams from a pair of accelerators was measured with a cellulose triacetate film dose meter ( I O ) . The results are shown in Figure 2, where it is seen that the distribution is exceedingly heterogeneous, as suggested, both in vertical and horizontal directions. The average dose rate in the irradiated zone was determined to be 0.26 Mrad/s for the maximum beam current (60 mA X 2) by three-dimensional integration of the entire distribution; the proportion of the electron power absorbed by the gases in the reactor to the total electron power generated in the accelerated tubes was calculated to be 75% for the accelerated voltage (600 kV) and estimated to be 79% for 750 kV. Optimum Gas Rotation Ratio. Preliminary irradiation of the gas was first carried out to determine the optimum gas rotation ratio. Efficiencies of NO, and SO, removal are plotted against the gas rotation ratio in Figure 3. The ratio is a measure of the gas rotation in the reactor and is defined as: gas rotation ratio - revolutions of impeller (rpm) gas flow rate (Nm3/h) circular component of gas velocity a axial component of gas velocity or tan 0 (0 = gas helix angle) Both efficiencies were considerably influenced by the gas rotation ratio, and the optimum ratio was determined to be 1/60 (rpm-h/Nm3).I t is surmised that the gas rotation was effective in improving the removal efficiencies in region I in Figure 3 because it makes the dose absorbed by the gases thoroughly uniform despite the heterogeneous dose distribution in the reactor. In region 11, excessive rotation caused inverse flow, which had been experimentally verified in ad290
100
-
Environmental Science & Technology
v
6
YY
y
I,
NO,
so,.
: 180ppm : 200ppm
Flow rate ( N W h )
0.. 9000
-
6000
-
c
Dose : 1.8 Mrad
A , A
0.. 3000
.
5 LITGas Rotation Ratio
(rpm,h m)
Figure 3. NO, and SO, removal vs. gas rotation ratio relation
vance with a scale-down model reactor; therefore, the removal efficiencies were lowered. I t is also observed in Figure 3 that the efficiencies are independent of the gas flow rate and dose rate, being determined solely by the total absorbed dose, as they were in the previous work using the exhaust gases from the heavy oil-fired boiler (11). Efficiencies of NO, and SO, Removal. The efficiencies of NO, and SO, removal at the reaction temperatures 70 and 90 "C are plotted as a function of the total dose in Figure 4. NO, removal increased with increasing dose, reached a peak a t a dose of 1.5-2.0 Mrad, and thereafter decreased gradually with dose. The SO, removal was ca. 12% without irradiation, and increased with dose more rapidly than the NO, removal, approaching 100%. The exhaust NH3 decreased with increasing dose over an entire range of 0-4.0 Mrad, regardless of the decrease of NO, removal a t the larger doses. Both removals were considerably affected by reaction temperature; they were ca. 15%higher at 70 "C than at 90 "C when the dose was 1.5 Mrad. I t should be noted that the removal rates shown in Figure 4 were obtained in the operation with a gas rotation ratio of 1:33 rpm.h/Nm3. By referring to the curves of NO, and SO, removal in Figure 3, it may be observed that the removals increase ca. 5 1 5 % a t a gas rotation ratio of 1:60, compared with those a t a ratio of 1:33 rpm.h/Nm3. Figure 5 shows NO, and SO, removal vs. dose relation at a ratio of 1:60 rpm.h/Nm3 for the flow rate of 10000 Nm3/h. The NO, and SO, removals increased with increasing dose, as shown also in Figure 4,
100
-890
Table 111. Experimental Conditions in Continuous Operation (Term, One Month)
'80 70
60
6 50 2 L
E
40
200
_" 30
150
$20
100
d 10
50
-I"s
2
gas flow rate total dose input NO, input SO, ratio of NHs addition reaction temp ratio of gas rotation irradiation
3000 Nm3/h 1.5 Mrad 190 ppm 200 ppm 1.o 80 OC rpm.h/Nm3 600 kV X 17 mA X 2
0 Figure 4. NO, and SO, removal and exhaust NH3 vs. dose relation
0
05
10 15 20 Dose ( Mrod)
25
Figure 5. NO, and SO, removal vs. dose relation
reaching ca. 80 and 100%a t 1.8 Mrad, respectively; these are ea. 10%higher than the removal rates at the same temperature in Figure 4. The NO, removal of 80%at 90 "C was equal to the removal obtained under the same conditions in the previous work with the pilot plant, a t 1000 Nm3/h ( I I ) ,while the SO, removal of nearly 100%was ca. 20% higher. By-products. X-ray diffraction analysis indicated that the powder collected with the E P was largely composed of a and ammonium mixture of ammonium sulfate (("&Sod) nitrate sulfate ( (NHl)&304.2NH4N03), which are the same as those obtained in the previous work (11).The chemical analysis indicated that the molar ratio (NH4)2S04: ( N H ~ ) ~ S O ~ . ~ N Hwas ~ Nabout O S 2:3 with the products obtained under typical experimental conditions (see Table 111). Continuous Operational Performance. The performance of continuous operations was tested over a period of 1month. Operational conditions, shown in Table 111, were determined based on a series of experiments that had been performed systematically to investigate the influences of factors on the removal efficiencies. The flow rate was lowered to 3000 Nm3/h because the designed capacity of the E P fell on this value. Figure 6 shows the NO, and SO, removal and exhaust NH3 along with the input NO, and SO, during the entire running period. NO, removal of about 80%and SO, removal of more than 95% were simultaneously steadily accomplished. The exhaust NH3 was maintained between 10 and 50 ppm, although it temporarily exceeded 50 ppm because of the trouble with the flow meter for the "3. It might be noted here as well that the operation was carried out a t a gas rotation ratio of 1:33 rpm-h/Nm3, which was the lower limit of the ratio available for 3000 Nm3/h with the present plant; according to Figure 3, an increase of 5-15% in both removals and the corresponding decrease of 20-30 ppm in the exhaust NH3 are expected a t the optimum gas rotation ratio 1:60 rpm.h/Nrn:j. During the continuous run no repairs were required with any part of the plant. The foil windows (Ti-Pd alloy) of the
reactor remained new or undamaged in appearance even after a 1300-h continuous run involving the preliminary continuous operation of 1 month. The deposition of the powder was observed especially in the duct between the reactor and the E P and a t the E P bottom.
Nitrogen and Sulfur Balance The nitrogen and sulfur balance of the exhaust gas between, before, and after irradiation was investigated under typical experimental conditions. The total amount of each element after irradiation was derived from the sum of its contents in the E P captures, in the exhaust to the atmosphere, and in the products deposited between the reactor and the E P in the duct, of which the upper one-third length was washed out to collect the products. In referring to nitrogen, each of NO, ( = N O + NOL),"3, (NO, + 2N,O), and total nitrogen was separately examined. The results shown in Figure 'iindicate that the contents of NH3 nitrogen and sulfur recovered downstream of the reactor or after irradiation are nearly equal to their input contents. But the total recovered NO, nitrogen and (NO, 2N20) nitrogen considerably exceeded the input. The composition of products deposited in the duct was compared with those of the products attached to the reactor wall and collected with the EP. The contents of NH4+. NO,?-, and S042- along with the molar ratio of NOS- to S O A ~in - the products are plotted against the residence time in Figure 8. The S042-content occupied a larger fraction in the upper half of the reactor, decreased with increasing NOS- content in the lower half of the reactor, and reached a certain level in the duct downstream of the reactor where the molar ratio of N03- to Sod2- became approximately unity. X-ray diffraction analysis also indicated that (NH4)2S04 and (NH4)+304.2NH4N03 were respectively predominant in the products deposited on the reactor wall and in the products downstream of the reactor.
+
Discussion Formation of (NH&S04 and (NH4)2S04*2NH4N03 Powder. As described before, the products collected with the E P were a mixture of (NH4)2S04 and (NH4)2S04*2NH4N03 under the typical experimental conditions. The NO, and SO, in the gas are considered to be oxidized into "03 and H2S04, respectively, by the oxidizing species OH, 0, and HO2 formed via radiolysis of the exhaust gas in the absence of NH3 ( I 1 , 1 3 ) . Some parts of the H2S04 will react with N 2 0 3 to form NOHS04 as described previously (12). Since HNO3 and HzS04 are both hygroscopic, they are readily converted into a mist state in the presence of moisture:
nHzO(gas, droplet)
HPSO4(gas)
H2S04 (mist)
(1)
HN03(mist)
(2)
mHzO(gas, droplet)
HNOs(gas)
Volume 14, Number 3, March 1980
291
Gas flow rote
Adjustment
Y
3coO
NmVh
1.5 Mrod
Dose Temp.
80°C
RNHS
1.o
-
G O 0
lo0
20
300
500
400
600
Irradiation-hour ( h ) Figure 6.
Result of continuous operation
suggests that (NH4)2S04 and ( N H ~ ) ~ S O C ~ N Hformation ~NO~ may be completed in the reactor. Formation of NO, and NzO. During the investigation of SNHs(gas) the nitrogen balance it was found that the amount of nitrogen HzS04(rnist) (NH4)2SOd(solid) (3) oxides after irradiation exceeded that before irradiation and that a certain amount of nitrous oxide (NzO) was detected in ru"s(gas) the irradiated gases as mentioned before. This suggests the HNO,(mist) NH4N03(solid) (4) formation of NO, and N20 by irradiation. The formation of ZNHs(gas) + 2HhT03(gas) NO, could explain the finding that the efficiency of NO, re+ lHpO(gas, droplet) (NH~)ZSO~~NH~NO ~ decreased a t doses above ca. 1.8 Mrad, despite the moval consumption of NH3 as shown in Figures 4 and 5. (solid) (5) But the formation of NO, is not consistent with the results 2NH3(gas) + of the previous work (11) that the amounts of NO, before and after irradiation balanced each other and the NO, removal (NH4)2S04*2NH4N03 ("4)2S04 increased with dose up to 3.5 Mrad. Koda et al. reported re(solid) (solid) (6) cently that NO, is produced through Reaction 8 in the radi2NH4N03(solid) olysis of the N2-NO-02 mixture ( 1 4 ) . + (NH4)2S04*2NH4N03 (solid) (7) 0 2 N(*D),N3+ +NO, be produced through the reaction of these mists with NH3 as follows:
-
Reaction 5 is considered to be much faster than reactions 6 and 7 for the following reasons: (a) As is well known, the formation of H2S04 mist by Reaction 1 is much faster than the formation of "03 mist by Reaction 2. (b) Since the diffusion velocity of HNOs(gas) is much greater than that of HNOs(rnist) and NH4N03 (solid), the HN03(gas) has a larger probability of reaching the suspended (NH4)2S04(solid) and forms the (NH4)2SO4.2NH4N03 with the NH3(gas) and H20(gas, droplet). Thus, the formation of ("&SO4 and (NH&S042NH4N03 may be attributed mainly to Reactions 1 , 3 , and 5, Le., the H2S04 mists are first'produced, reacting with the NH3 then about half of the (NH4)2S04 gas to form the ("&Sod; is converted into the (NH4)2S04a2NH4N03.The mechanism mentioned above is consistent with the following experimental results: (a) The products collected with the E P were composed largely of (NH4)2S04 and (NH4)2S04*2NH4N03;they were free of NH4N03. (b) (NH4)zSOh was predominant in the products deposited on the reactor wall, whereas (NH4)2S04. 2NH4N03 was rich in the products deposited between the reactor and E P and the products collected in the EP. The fact that both Nos- and Sod2- contents were nearly constant downstream of the reactor as shown in Figure 8 292
Environmental Science & Technology
The 0 2 content of exhaust gas from the sintering machine was ca. 15.5%as shown in Table 11, whereas that of the heavy oil combustion gas used in the previous work (11) was ca. 3-4%. The formation of NO, may be attributed to the larger 0 2 content in exhaust gas from the sintering machine. Decrease of SO,. The decrease of SO, is mainly attributable to the reaction of H2S04 mists (produced under irradiation) with NH3 gas to form ("&SO4 as mentioned above (Reaction 3). However, 12% SO, removal was attained even without irradiation, as shown in Figure 4. It is commonly known that several percent of SO, exists as SO3 in the exhaust gases from combustion. The SO3 must react with the NH3 through Reaction 3, but this cannot explain entirely the 12% SO, removal. If H2O droplets are suspended in the gas, the formation of (NH&S03 by Reaction 9 will take place because of the high solubility of SO2 for water. SO2 (gas)
nHzO(drop1et)
H2S03(mist) ?KHi(gas)
---+
(NH4)2S03(solid) (9)
The (NH4)2S03 might be collected with the EP, where it
1
? u n ~~~~~~i~~~ ,
IF
Proportion of Recovered to Input _.__
~
[%)
_
_
A
_
1.2
~
150
-:5
total N*') NOX-N
1109 (NOxt2N20)-N "3N
sox- s
total N NOx- N 11 1 1 (NOx+2NzO)-N "3N
sox- s
0
1114 (NOX t2N20).-N "3N
24
30
36
As the result of experiments over a period of 1 year using the pilot plant with a maximum gas flow rate of 10 000 Nm3/h, this process was proven to be promising as a dry process capable of simultaneously removing NO, and SO, contained in exhaust gas from a sintering machine in a steel plant.
: EP Capture : Exhaust to Atmosphere ;I(3) : Deposited in Duct
L i t e r a t u r e Cited a21
Total N =(NOX-N)+(NH~-N)+~(N~O-N)
M2) N20-N
18
Residence Time Is)
Conclusion
sox- s
3 1)
12
Figure 8. Variation of product composition with residence time
total N NOX- N
1I 1-
6
vas doubled, since it has two nitrogen atoms.
*3) '13 was actually samplkd and * I 3 was estimated proportionally to the duct length. Figure 7. Results of nitrogen and sulfur balance examination: NO,, 190 ppm; SO,, 215 ppm; RNH3,1.0; gas rotation ratio, 1:20 rpm-h/Nm3; dose, 1.8 Mrad; reaction temp, 90 O C ; gas flow rate, 3000 Nm3/h
would be readily oxidized to ("&SO4 by the 0 2 in the gas. In the cooling tower upstream of the reactor, water is atomized to droplets, which may be suspended in the flowing gas. In the heat exchanger a number of water droplets would be formed in the gas, because the supersaturation of water vapor is caused by the cooling water, the temperatures of which are -20-30 "C a t the inlet and -30-40 "C at the outlet. Although the temperature of cooled gas is raised to ca. 90 "C by mixing with the hypassed gas, most of the water droplets may still remain in the gas, since the dew point of the exhaust gas is -120 "C. Thus, 12% SO, removal obtained without irradiation may be responsible for the formation of (NH4)zSOa via H # 0 3 mists formed by the absorption of SO2 into the water droplets that are produced either in the cooling tower or in the heat exchanger.
(1) Tomoda, M., N e t s u Kanri To Kogai, 30,21 (1978). ( 2 ) Nishijima, A., Kurita, M., Sato, T., Kiyozumi, Y., Hagiwara, H.,
JJeno, A., Toda, N., Nippon Kagaku Kaishi, 893 (1978). (3) Kawamura, K., Aoki. S., J . A t . Energy Soc. J p n . , 14, 597 (1972). (4) Kawamura, K., Aoki, S., Kawakami, W., Hashimoto, S., Machi, S., Radiat. Clean Enuiron., Proc. Int. Symp., 621 (1975). (5) Washino, M., Tokunaga, O., Hashimoto, S., Kawakami, W., Machi, S., Kawamura, K., Aoki, S., Radiat. Clean Enuiron., Proc. I n t . S y n p . , 633 (1975). ( 6 ) Machi, S.,Tokunaga, O., Nishimura, K., Hashimoto, S., Kawakami. W., Washino, M., Kawamura, K., Aoki, S., Adachi, K., Radiat. Phys. Chem., 9,371 (1977). (7) Japanese Industrial Standard, "Methods for Determination of Oxides of Nitrogen in Exhaust Gases", J I S K-0104. (8) Japanese Industrial Standard, "Analytical Methods for Determining Total Sulphur Oxides in Flue Gases", J I S K-0103. (9) Japanese Industrial Standard, "Method for Determination of Ammonia in Exhaust Gas", J I S K-0099. (10) Lakier, J., Hashimoto, S., Yotumoto, K., Tanaka, R., Kageyama, E., Matuzaki, K., Danno, A., JAERI-memo 5136, 1973. (11) Kawamura, K., Hirasawa, A,, Aoki, S., Kimura, H., Fujii, T., Mizutani, S., Higo, T., Ishikawa, R., Adachi, K., Hosoki, S., Radiat. Phys. Chem., 1 3 , s (1979). (12) Kawamura, K., Hirasawa, A., Aoki, S., Kimura, H., Fujii, T., Mizutani, S., Higo, T., Ishikawa. R., Adachi, K., J . At. Energy Soc. J p n . , 20,359 (1978). (13) Tokunaga. O., Nishimura, K., Suzuki, N., Washino, M., Radiat. Phys. Chenl., 11, 117 (1978). (14) Koda, S., Tsuchiya, S.,Nippon Kagaku Kaishi, 164 (1979). Recpiued for reuieu?June 28,1979. Accepted December 3, 1979
Volume 14, Number 3, March 1980
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