JPS58115216A - Disposal of waste gas - Google Patents

Abstract

PURPOSE:To dispose waste gas in high thermal efficiency, by feeding the waste gas containing combustible organic compound into a catalyst oxidizing reactor to burn it completely, after the waste gas is heated by discharged gas from the reactor which is provided on the after-flow side of the gas. CONSTITUTION:When waste gas fed through a pipe 31 is disposed, first, the waste gas is led into a catalyst oxidizing reactor 36 by a booster fan 32, after it is heated while it passes through a heat exchanger 33 and a pipe 34 in turn, and is mixed with a part of gas which is fed into a catalyst oxidizing reactor 36 through a pipe 46 and is discharged from the outlet of the reactor. A part of waste gas, completely burnt in the reactor 36, is branched off into a pipe 40 and is led into a heat exchanger 44, heating the waste gas which is led through the pipe 34. On the other hand, the remaining part of waste gas flowing out of the reactor 36 is released to the open air, passing through a stack 39 via a heat recovering unit 38 and the heat exchanger 33. All or a part of waste gas flowing out of the above-mentioned heat exchanger 44, passing through the pipe 46, is mixed which the waste gas flowing out of the heat exchanger 14.

Description

[Detailed description of the invention]

Unexploded 8F+ relates to a method for processing gaseous gas. Specifically, this is a waste gas treatment method for the complete solubilization of hydrocarbons, carbonized carbons, and other combustible organic compounds in waste gases emitted from chemical manufacturing processes, etc. It is related to. Waste gases generated in chemical manufacturing factories, etc. - methane, ethane, ethylene, propane, propylene, etc.
Contains flammable compounds such as 6 hydrocarbons, organic compounds, aldehydes, esters, and alcohols, and contains many foul-smelling substances. . It is desirable that these flammable compounds be released into the atmosphere;
It is obvious that there is a strong need to remove bad odors, and various processes have been proposed to eliminate them. As for the conventional waste gas treatment process adopted to remove this foul odor and other harmful substances, Example 2 is shown in the flow sheet in Figures 1 and 2. There is a power method as shown in . In the method shown in Figure 1, the waste gas containing combustible compounds supplied from the conduit is
After being heated in a heat exchanger 3 via a booster fan 2 provided as necessary, the heat exchanger 5 passes through a conduit 4 and is heated by heat from an external heating source. Next, a catalytic oxidation reactor 6 ((
It is sent to a heat recovery device 8 through a conduit 7 for complete combustion.
After the combustion gases are supplied to the exhaust gas and the heat is recovered, the combustion gases themselves are supplied to the heat exchanger 3 to heat the waste gas supplied from the conduit J, and are then discharged from the stack 9 into the atmosphere. Furthermore, if the temperature of the harsh gas supplied to the pre-distribution medium oxidation reactor 6 is too high, air is supplied from the air supply fan 0 to dilute it. The heat exchanger 1 passes through the booster fan 12 installed.
After being heated in step 3, it is sent through a conduit 14 to a catalytic oxidation reactor 16 consisting of activated alumina filled with a catalyst containing a fraction of a noble metal such as platinum, where it is completely combusted, and further through a conduit 7. The combustion gas itself is supplied to the heat exchanger 13 to heat the waste gas supplied from the conduit 11, and then released into the atmosphere from the stack] 9. be done. In this case, a portion of the fully combusted gas from the catalytic oxidation reactor 6 is branched off by line 20 and circulated by fan 2 into the heated waste gas supplied from line 14 to further remove said waste. It raises the temperature and increases thermal efficiency. Further, a part of the branched complete combustion gas is transferred to the conduit 22V (
It may be further branched and supplied to the heat exchanger]3. Furthermore, if the temperature of the gas supplied to the catalytic oxidation reactor 6 is too high, the gas after passing through the heat recovery device 18 may be transferred to the conduit 2.
3 may be branched and circulated. However, it generally contains two gases containing flammable compounds, including paraffinic hydrocarbons. When adopting the process of completely converting the open gas using a catalyst, the prerequisites are:
It is as follows. (1) The quality of the log gas output from the catalyst should be approximately constant. The allowable temperature limit of the catalyst is said to be 700 to 720 DEG C. It is not preferable to operate at a catalyst bed outlet gas temperature of 650 DEG C. or lower, since combustion of carbon, paraffin hydrocarbons, especially propane, etc. will be insufficient. Therefore, the average 4
- It is desired that the target be operated at a level of approximately 680°C. (2) The gas temperature at the inlet of the catalyst layer should be 250° C. or higher in relation to contactor activity. (3) The calorific value of the gas at the inlet of the catalytic oxidation reactor is such that the self-rise temperature in the catalyst layer is 430°C or less (680 to 250°C)
However, the process should be controlled within the temperature range of Very powerful. As a result of studying a waste gas treatment method based on the above premise, the present inventors have come to realize that the following points are necessary. (A) Maximum recovery of heat If the temperature of the treated exhaust gas released into the atmosphere is kept as low as possible, 7 degrees will be generated in terms of durability.
Increases in the amount of supplied waste gas (by introducing fresh air, etc.) should be avoided as much as possible. In order to achieve maximum heat recovery, it is necessary to make the process so that the gas demand 1# released is kept as constant as possible even when the supply gas fluctuates before it heats up. (B) 4. Re-extraction of the emitted gas for the first use In the exhaust gas thus released, there is almost no smoke or combustible matter (e.g., alcohol). Since the concentration is low, it can be used for various purposes as a non-resident gas.
For example, it is desirable to use it for the seal shell of a hazardous material tank. However, in the method shown in FIG. 1, in order to maintain the above-mentioned preconditions and satisfy the conditions (A)2 and (B'l), it is inconvenient to operate the heating heat exchanger 5. The 11th problem is the increase in gas consumption due to air replenishment.
It's hard to avoid profit. The outlet gas of the catalytic converting reactor 6 is heat recovered in a heat recovery device 8, for example by generating steam, and is further used for heating the feed plant waste gas before being discharged. When the calorific value of the supplied waste gas is low, the temperature of the reaction log gas rises even if the temperature changes, so in order to control it, it is necessary to mix the air from the outside ship, which causes an increase in the gas flow rate. ° It is impossible to avoid an increase in the amount of heat carried away by the gas. O, since the oxygen temperature in the outlet gas does not reach a certain level, there is a problem in terms of reuse of the exhaust gas. On the contrary, When the calorific value of the supplied waste gas is low, the tactile aL
In order to maintain the temperature of the log gas exiting the solubilization reactor at the rated value, it is necessary to increase the gas temperature at the inlet of the catalytic oxidation reactor, and the heating heat exchanger 5 must be operated. In order to carry out complete acetylation, it is necessary to maintain the temperature of the log gas exiting the catalytic butcherization reactor at approximately 680"C, and therefore the temperature of the log gas entering the catalytic butcherization reactor must be increased. For example, the calorific value of gas is the target.If the temperature is 370℃ as 121-Fuchi degree, the temperature at the entrance of the reaction reaction, [w If the temperature is set to 31.0℃, the outlet temperature

[If you keep it at 680℃, you will be lucky, so you need a heating source of 350℃. However, in the method shown in Figure 2, the above preconditions are maintained and ( In order to satisfy the conditions A'l and (Bl), the waste gas treatment equipment is designed based on the maximum heat release time of the supplied gas. That is, the exhaust gas temperature at the catalytic oxidation reactor outlet is In order to reach 680℃, the outlet temperature of [heat exchanger] 3 is 680℃ minus (self-rising temperature when the most door generates heat)
If the temperature is below 250° C., a part of the catalytic reaction supplementary gas can be recycled and used to raise the inlet temperature of the catalytic reactor. However, the effect of the circulating gas is only to increase the temperature of the log gas entering the catalytic butcherization reactor, but is not useful for increasing the temperature of the log gas exiting the catalytic butcherization reactor. Therefore, when the calorific value of acid gas becomes low, depending on the increase or decrease in the amount of circulating gas,
It is not possible to maintain the log gas temperature fi 680° C. at the exit of the drunkenization reactor, and it is necessary to increase the exit efficiency of the heat exchanger 13. Therefore, it is necessary to bypass the VC heat recovery system [8] and supply a part of the outlet gas of the catalytic oxidation reactor 16 to the heat exchanger 13 to elevate and filter the feed gas.
9. If the temperature of the exhaust gas flowing into the room rises, the heat recovery rate will decrease significantly.Thus, an object of the present invention is to provide a method for treating exhaust gas that can be recovered as efficiently as possible. be. Another objective of Honba Momei is to provide a method for treating acid gas that can be used for immobilization of the gas extracted from the processing vessel. The power of the present invention is as follows. (11(a) Calorific value from complete combustion, including carbonized compounds, -19 carbonized carbon substitutes, and other stimulant compounds)
00 to 300 Kcal/Nm" is heated with the exhaust gas after heat recovery from the log gas exiting the atomization reactor, (b) The acid gas heated in this way is heated in the atomization reactor = h
(e) supplying the heated acid gas obtained in step (b) to a catalytic oxidation reactor until complete oxidation is achieved; (d) A portion of the catalytic butcherization reactor outlet gas used to heat the acid gas in operation (b) is combined with the TJU-heated waste gas and the catalyst itself and the catalytic butcherization reactor. (e') The remainder of the part of the gas at the outlet of the reactor used for heating the folding gas + IC in operation (d) is:
(f) A part of the exhaust gas after heat recovery is subjected to heat recovery together with the remainder of the log gas output from the catalytic conversion reactor (b + Ig
The catalyst that heated the waste gas is mixed with a part of the log gas from the conversion reactor. I + T gas processing method in which the gas flow is reduced by a spool at the 7th mouth of the gas flow (maximize the gas flow rate of fi, and when it is a calorific value handle, it is set by reversing it.Hereinafter, 12/4 In other words, the waste gas treatment method of the present invention is shown in FIG.
A booster fan 32 is provided as necessary to remove the gas that is generated when the liquor, carbon dioxide, and other combustible materials are placed on the table.
After being heated in the first heat exchanger 33 through the conduit 34, it is further heated in the second heat exchanger 44, and the catalyst portion is supplied from the conduit 46 to the reactor 36. It is mixed with a part of the outlet gas and then touched.
It is supplied to the oxidation reactor 36 and completely combusted. The reactor 3
The outlet (exhaust) gas that has been completely combusted and heated in step 6 is branched from the conduit 37 through the conduit W4 ovc and is supplied to the second heat exchanger 44 to heat the open gas supplied from the conduit 34. After that, all or a part of the outlet gas supplied to the second heat exchanger 44 passes through the conduit 46 to the second heat exchanger 44.
It is mixed into the folding gas heated by the heat exchanger 44. If there is a remainder of the outlet gas supplied to the second heat exchanger 44, it is circulated through the conduit 47 to the conduit 37 and sent to the catalyst chamber 7.
After being mixed with the hot outlet gas from the reactor 36 and then recovering maximum heat in the heat recovery device 38, it is transferred to the conduit 4.
8 to the first heat exchanger 33 to heat the folding gas supplied from the conduit 31, and further discharge into the atmosphere from the stack 39 or to accommodate the chemical process or slender material of Tsukuda, It is used as an inert gas for sealing containers. On the other hand, when the calorific value of the supplied waste gas is high, a part of the log gas from the catalytic sootification reactor that has passed through the second heat exchanger 44 is returned to the total amount or to the catalytic sootification reactor 36, and further A portion of the log gas output from the heat recovery device 38 is also transferred to the catalytic oxidation reactor 36.
To maintain the outlet gas temperature at the rated value, the gas is mixed into the conduit 45 from the conduit 49, and then passed through the conduit 46 to the catalytic oxidation reactor 36.
returned to the entrance. As the calorific value of the supplied waste gas decreases, the flow rate of the circulating gas supplied to the catalytic conversion reactor 36 after passing through the heat recovery device 38 decreases, and the calorific value of the waste gas becomes equal to the design calorific value branch. point (18 in Figure 4)
0Kca1/m”), the flow rate may be set to zero.
This circulating gas may be used as indicated by '-):m49 in FIG. Furthermore, the heat generation of waste gas
When the pressure is lowered, a portion of the catalyst reaction log gas that has passed through the second heat exchanger 44 will be returned to the heat recovery device 38. This is equivalent to heat exchange between the outlet gas of the oxidation reactor 36 and the waste gas heated in the heat exchanger 33 of the oxidation reactor 36, and the amount of heat exchanged is It can be controlled by the flow rate of exhaust gas that flows directly to 38. That is, the effect is substantially the same as that of increasing the exhaust gas output from the heat exchanger 13 in FIG. 2 IC. Furthermore, if the method shown in Fig. 3 is followed, the bottom fat of the exhaust gas flowing into the stack 39 is almost constant regardless of the amount of gas, and there is no increase or decrease in the exhaust gas, so a tremendous heat recovery rate can be achieved over a wide range of calorific value (11 K). I'm interested in maintaining it. Also, the method r in Figure 3
(Accordingly, if it is desired to raise the inlet temperature of the exhaust gas recovery reactor 36 to 250°C or higher due to deterioration of the catalyst, the second heat exchanger 44
The inlet temperature of the catalytic oxidation reactor 36 can be easily raised by increasing the flow rate of the exit gas of the catalytic oxidation reactor 36 passing through the catalyst. In order to make the above explanation more concrete, FIG. 4 shows the rate of heat recovery for each of FIGS. 1 to 3. Operational neutrality and design condition settings are as follows. Heat generation of one supply gas-ji 300Kcal/W? ~
]0OKcal/m' (self-rise temperature IW penalty 93
0℃～31f1℃r (equivalent) supply is waste gas temperature
50℃ IIl! l! Medium layer log gas temperature
250℃ Temperature of gas coming out of the tactile layer 680℃ Temperature of air supplied from outside 20℃ Standard design waste gas calorific value 180Kcal, outside standard design exhaust gas temperature 100℃ In the case of Figures 1 and 3, the heat Gas temperature blooms when discharged from the exchanger to the outside, Habo 10
However, in the process shown in Figure 2, the calorific value is small; the exhaust gas temperature has to be raised to 270 to 290 degrees Celsius. Kari, I understand that it would be very convenient in case of disaster. In the above meter, the calorific value of the gas is expressed as the self-rising temperature (
680 minus the supply exhaust gas temperature) 100°C or less. Even in cases where the calorific value exceeds this value, the superiority of the present invention is clearly recognized. In the process shown in Figure 1, the addition of external air is increased to I'
・It is clear from the trend in Figure 4 that a decrease in the heat recovery rate is unavoidable, although it is possible to cope with this problem. In the processes shown in Figures 2 and 3, tJ1 can be achieved by mixing the heat recovery equipment outlet gas with a portion of the log gas from the Cape glue reactor that is recycled (the broken line in Figure 2). (Illustrated.) In this case, in the process shown in FIG. 3, gas flows completely through the line from the second exchanger 44 to the heat recovery 'fk 38, so the process shown in FIG. 2 can be seen as essentially the same process. Therefore, the heat (b) yield will be the same. In other words, in Figure 4, it is shifted to the Takamoto Netsudo side, and the heat exchange rate is the same as that of the processes in Figures 2 and 3 (the processes in Figure 1 show the same concavity, and only the process in Figure 1 The results show that the process shown in Figure 3 is capable of dealing with fluctuations in calorific value over a wide range, and it is clear that it meets the standards of an excellent heat recovery agent. Therefore, the method and apparatus of the present invention can be applied to a process for producing acrylic acid by distillation of propylene, a process for producing acrylonitrile by ammophilation of propylene, and a process for producing epithermal maleic acid by distillation of benzene. Waste gas emitted from e.g.
~300Kcal/Nm3, %K 100~250K
It is particularly effective for the disposal of waste gases with a calorific value of "cal/Nm".

[Brief explanation of the drawing]

1 and 2 are flow sheets of a known waste gas treatment process, and FIG. 3 is an example of a flow sheet according to the present invention. FIG. 4 is a graph showing the trend of the heat recovery rate of the valley process shown in FIGS. 1 to 3. In Fig. 4, the horizontal @ indicates the heat generation mr'(Kcal/Nm'') and the vertical axis indicates the heat recovery rate (correspondence). Applicant: Nippon Shokubai Kagaku Kogyo Co., Ltd. −
115216 (6) 41st blade foot η'°7 sympathy amount (this %

Claims (1)

[Scope of Claims] (11(a) Hydrocarbons, including white carbon and other flammable cold compounds, heat generation i due to complete combustion)
F10 to 300 Kcal/Nm" of hot gas is heated with the exhaust gas after heat recovery from the catalytic oxidation reactor outlet gas, and (b) the thus heated waste gas is heated in the catalytic oxidation reactor outlet gas. (e) The heated waste gas obtained in step (b) is further heated for three additional times to be completely oxidized and rendered harmless by supplying the heated waste gas obtained in step (b) to a catalytic oxidation reactor, and (d) the waste gas obtained in step (b+) Part or all of the catalytic reaction product log gas heated by the heated VC is supplied as a catalyst hr. The remainder of the part of the catalytic oxidation reactor outlet gas used to heat the gas is used for heat recovery together with the remainder of the catalytic oxidation reactor outlet gas. In the exhaust gas treatment process, which is mixed with a part of the output gas from the catalytic oxidation reaction that heated the exhaust gas in step (b), the gas flow rate in operation (e') when the calorific value of the IK gas is at its maximum. The gas flow rate of operation (r') is maximized by decreasing it to zero 7,
This waste gas treatment method is characterized by the fact that when the calorific value is at its minimum, the reverse rotation occurs.