JPS63291625A - Treatment of exhaust gas and fluidized bed type adsorption tower used for treatment thereof - Google Patents

Abstract

PURPOSE:To prevent the clogging of a gas purification cylinder and a filter and to efficiently treat exhaust gas by passing exhaust gas discharged from a reaction furnace through a scrubber and thereafter passing it through a fluidized bed type adsorption tower in which a purifying agent is floated and removing adhesive substance included in the exhaust gas. CONSTITUTION:Exhaust gas contg. harmful gas such as dischlorosilane discharged from a reaction furnace 1 in a semiconductor manufacturing factory is sucked with a vacuum pump 3 and introduced into a trickle-type scrubber 2 and harmful gas is removed by acting an alkali soln. or the like. Then the exhaust gas incorporating both nonreactive gas incapable of treating in the scrubber and adhesive substance formed in the scrubber is introduced into a fluidized bed type adsorption tower 6 in which a purifying agent such as activated carbon is floated via a pipe 5 and the adhesive substance is adsorbed and removed. Then the exhaust gas is introduced into a gas purification cylinder 9 encapsulated with the purifying agent and the residual harmful substance is throughly made harmless and treated.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to an exhaust gas treatment method and a fluidized bed adsorption tower used in the treatment method.

[Problems to be solved by conventional technology and invention]

One method for treating exhaust gas emitted from reactors in semiconductor manufacturing plants is to use scrubbers. Scrubbers are used for exhaust gas that easily undergoes oxidation reactions, hydrolysis, neutralization reactions, etc. with oxidizing agents, water, acids, alkalis, etc., and scrubbers are used to clean exhaust gases by bringing them into contact with these oxidizing agents as efficiently as possible. It is used to remove harmful substances, and typical scrubbers include one-component scrubbers and pentier scrubbers.
Scrubbers etc. are used.

In exhaust gas treatment methods using these scrubbers, they are often used in combination with other treatment equipment other than the scrubber, for example, in combination with a combustor or a gas treatment tube containing a purifying agent. The combination of these is a measure because it is difficult to perform sufficient processing with a single processing device.
By combining these, it is possible to achieve better detoxification treatment of exhaust gas.

As an example of a typical exhaust gas treatment method, exhaust gas from a reactor is sent to a one-component scrubber using a vacuum pump, and harmful substances are removed in the scrubber, and then sent to a gas treatment cylinder filled with a purifying agent, where the gas is One method is to remove the remaining toxic substances and turn them into harmless gases.

Furthermore, when treating pyrophoric gases such as silane, a method using a combustor, a venturi scrubber, and a filter instead of the one-component type scrubber in the above method is also used.

In conventional methods like this, sticky substances may be mixed in the gas that has passed through the scrubber, and these sticky substances may adhere to the gas treatment cylinder or filter, clogging them, resulting in This caused problems such as a significant decrease in processing efficiency. Such sticky substances are generated, for example, when exhaust gases such as silicon tetra-silicon heptide, dichlorosilane, trichlorosilane, and silicon tetrachloride are brought into contact with water, etc. in a scrubber, and its actual nature is not clear. is thought to be siloxane, fluorosilicic acid, etc.

It is an object of the present invention to provide a treatment method and apparatus that eliminate such sticky substances and prevent clogging of gas treatment tubes and filters, and that can efficiently treat exhaust gas. It is.

[Means for solving problems]

In order to solve the above problems, the method of the present invention sucks exhaust gas containing toxic gas discharged from the reactor, sends the sucked exhaust gas to a scrubber, and in the scrubber, oxidizer solution, water, acid solution, or alkaline solution is used. In an exhaust gas treatment method in which a solution is applied to remove most of the harmful gases and then the gas is sent to a gas treatment cylinder filled with a purifying agent to be purified and made into harmless gas, the exhaust gas after passing through a scrubber is processed into a fluidized bed in which the purifying agent is suspended. The device of the present invention has a structure in which sticky substances are removed from the exhaust gas that is generated and entrained when passing through a scrubber in the adsorption tower. The main body has a cylindrical adsorption tower body with a space for suspending the gas, and the bottom of the main body is provided with an inlet for introducing exhaust gas that is connected to the exhaust gas outlet of the scrubber. An outlet is provided, and the inlet is covered with a cap having a diameter larger than the diameter of the liquid tube, covering the upper surface of the inlet tube protruding from the bottom surface of the adsorption tower main body, with a gap between the bottom surface of the main body and the side wall of the inlet tube. This is an inlet configured so that exhaust gas is introduced into the main body from the liquid hole through the gap between the introduction pipe and the cap, and from the gap between the cap and the bottom of the main body. It has a structure in which a collar is formed in which the purifying agent placed inside the main body floats by transferring it from the inlet through the adsorption tower main body to the outlet.

〔Example〕

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

What is shown in FIG. 1 is a flow sheet of an exhaust gas treatment apparatus for carrying out an example of the method of the present invention. 1st
In the figure, a reactor 1 and a one-component scrubber 2 are connected by a pipe 4 via a vacuum pump 3, and a pipe 5 protruding from the top of the one-component scrubber 2 is connected to the bottom of a fluidized bed adsorption tower 6. A pipe 7 protruding from the top of the adsorption tower 6 is connected to the top of a gas treatment cylinder 9 via a blower 8.

Also, in Fig. 1, 15 is a pressure gauge, 16 is a pressure gauge with contacts, and 17 is a pressure gauge.
indicates an exhaust fan.

The fluidized bed adsorption tower 6 in the present invention is as shown in FIG.
It has a cylindrical adsorption tower main body 20 having a space 19 for suspending the purifying agent 18 therein, and an exhaust gas inlet 22 connected to the exhaust gas outlet of the scrubber is provided on the bottom surface 21 of the main body 20. Further, an exhaust port 24 for exhaust gas is provided on the upper surface 23 of the adsorption tower main body 20. In the exhaust gas inlet 22, the upper surface of an inlet pipe 25 protruding from the bottom surface 21 of the adsorption tower main body is covered with a cap 26 having a diameter larger than the diameter of the liquid pipe 25, with a gap 27 provided between the bottom surface 21 of the main body and a gap 27. Also, holes 28 for exhaust gas outflow are provided on the front, rear, left and right sides of the side wall of the introduction pipe 25.

The purifying agent suspended in the fluidized bed adsorption tower of the present invention is a particulate agent that adsorbs sticky substances mixed in the exhaust gas discharged from the scrubber. Specific examples thereof include activated carbon, activated alumina, silica gel, Examples include synthetic zeolite. Further, the particle size of the purifying agent varies somewhat depending on the flow rate of gas such as exhaust gas flowing in the adsorption tower, but it is preferably about 0.5 to 3 fi. Furthermore, the amount of purifying agent inserted into the adsorption tower main body is appropriately selected depending on the size of the adsorption tower, etc. For example, if the volume of the space inside the adsorption tower is about 151, approximately 2 to 3 kg of purifying agent is inserted into the adsorption tower main body. Preferably, a cleaning agent is used.

The operation of the method of the present invention shown in FIG. 1 using the fluidized adsorption column 6 of the present invention constructed as described above will be described below with reference to the treatment of exhaust gas containing dichlorosilane.

The exhaust gas containing silicon tetrachloride in the reactor 1 is sucked by the vacuum pump 3, and the sucked exhaust gas is introduced into the clear liquid type scrubber 2, where an alkaline aqueous solution is applied to the exhaust gas to remove tetrachloride from the exhaust gas. Decomposes and removes silicon. At this time, sticky substances are generated in the exhaust gas.

Next, unreacted gas that cannot be treated by the scrubber and exhaust gas containing sticky substances generated by the scrubber pass through the vibrator 5 from the exhaust port of the scrubber 2 and enter the adsorption tower from the inlet 22 of the fluidized bed adsorption tower 6. be introduced.

The exhaust gas from the four people passes through the inlet pipe 25 protruding from the bottom surface 21 of the adsorption tower body, passes through the exhaust gas outflow hole 28 of the liquid pipe 25, passes through the gap between the inlet pipe 25 and the cap 26, and passes through the gap between the inlet pipe 25 and the cap 26.
6 and the bottom surface 21 of the main body from the space 19 inside the main body.
(arrow A in Figure 3).

A purifying agent 18 is placed in a space 19 inside the main body,
Due to the flow of the exhaust gas, they are in a floating state, and the sticky substances in the exhaust gas are adsorbed by the purifying agent 18 here.

Further, when a vacuum pump is used for suction from the reactor, oil may be mixed in the exhaust gas, but such oil can also be adsorbed by the purifying agent 18.

Next, the exhaust gas from which the sticky substances have been removed is introduced from the outlet 24 of the fluidized bed adsorption tower 6 through the pipe 7 into the treatment tower 9, where all harmful substances remaining in the exhaust gas are removed and treated.

What is shown in FIG. 2 is a flow sheet of an exhaust gas treatment apparatus for carrying out another example of the method of the present invention. In Fig. 2, a Hentury scrubber 29 is used instead of a clear liquid type scrubber, and a combustor 30 is connected between the reactor 1 and the Pentieri scrubber 29, and a fluidized bed type adsorption, etc. It has a configuration in which a filter 31 is connected between the blower 6 and the blower 8.

The venturi scrubber 29 is used to treat exhaust gas containing fine powder, and the combustor 30 burns combustible gas to convert it into thermally stable oxides. The exhaust gas combusted in this combustor 30 contains fine powder of solid combustion products, and in order to remove this powder, a venturi scrubber 29 is used in combination. Further, a filter 31 is provided to remove fine powder that cannot be excluded in the Hentury scrubber 29.

The operation of the apparatus constructed in this way will be explained with respect to the treatment of exhaust gas containing silicon tetrafluoride and silane.

The exhaust gas containing silicon tetrafluoride and silane discharged from the reactor 1 is introduced into the combustor 30, where the silicon tetrafluoride and silane are burned to form silicon oxide, and then the exhaust gas is sent to the venturi scrubber 29. It will be done.

The silicon oxide powder produced in the combustor 30 and the unreacted silicon tetrafluoride are cleaned in a venturi scrubber 29 by the action of water, but at this time a sticky substance is produced in the exhaust gas. The combustor 30 in the scrubber 29
The silicon oxide sent from the
29 is discharged to the outside.

On the other hand, the exhaust gas passes through the pipe 5 from the exhaust port of the scrubber 29 and is introduced into the adsorption tower 6 from the inlet 22 of the fluidized bed adsorption tower 6. This exhaust gas also contains sticky substances as in the embodiment shown in FIG. 1, but this sticky substance can be removed in the adsorption tower 6. Therefore, the adsorption tower 6
There is no sticky substance in the exhaust gas sent from the filter 31 to the filter 31, which will not clog the filter 31.The exhaust gas that has passed through the filter 31 is treated in the same manner as in the embodiment shown in FIG. 1 above.

FIG. 4 shows a test example to see how much clogging of a filter can be eliminated when the adsorption method of the present invention is used.

The graph shown in Fig. 4 shows the change in the differential pressure of the bag filter, and A in Fig. 4 indicates that the exhaust gas containing 500 p of silicon tetrachloride from the reactor is removed using a pentier scrubber, the adsorption method of the present invention, etc. It shows the change in the differential pressure of the filter when exhaust gas is introduced into the bag filter through the filter.
B shows the change in differential pressure across the filter when a similar gas is directly introduced into the bag filter from the reactor via the Pentier scrubber.

In this way, when the fluidized bed adsorption tower of the present invention is used, the differential pressure across the filter does not change, but when it is not used, the differential pressure increases monotonically over time, which clearly indicates that the filter is severely clogged. be.

The exhaust gas treated by the method of the present invention contains at least one gas that generates sticky substances when passed through the scrubber, such as silicon tetrafluoride, dichlorosilane, trichlorosilane, silicon tetrachloride, etc. Examples include gases containing at least one type of.

As explained above, the treatment method of the present invention and the fluidized adsorption tower used therein can be used in various embodiments.

The method and apparatus of the present invention are not limited to the above-described embodiments, and any changes in structure, material, and shape may be made without departing from the gist of the present invention.

〔Effect of the invention〕

As explained above, according to the method for treating exhaust gas of the present invention using the device of the present invention, sticky substances mixed in the exhaust gas after passing through the scrubber can be removed, and as a result, the sticky substances follow the filter. As a result, the frequency of replacing filters or cleaning agents can be minimized, and exhaust gas can be treated efficiently.

[Brief explanation of the drawing]

The drawings show embodiments of the present invention, and FIG. 1 is a flow sheet of a treatment apparatus for implementing one example of the method of the present invention, and FIG. 2 is a flow sheet of an exhaust gas treatment for implementing another example of the method of the present invention. A flow sheet of the apparatus, FIG. 3 is a vertical cross-sectional view showing an embodiment of the fluidized bed adsorption method of the present invention, and FIG. 4 is a graph showing changes in differential pressure of a bag filter. 1... Reactor, 2... Reservoir type scrubber. 6... Fluidized bed adsorption tower, 8... Blower. 9... Gas processing cylinder, 18... Purification agent. 19...Space, 20...Adsorption tower body. 21...Bottom surface of adsorption tower main body, 22...Exhaust gas inlet. 23...Top surface of adsorption tower main body, 24...Discharge port. 25...Introduction pipe, 26...Camping. 27... Gap, 28... Hole. 29...Pencherry Scrubber Figure 1 Figure 2 Figure 3 '1 ('I i Figure 4 time te'l (min,) Procedural dispute official seal) 3. Address of the person making the amendment Tokyo. 2-10-2 and above Iwamotocho, Chiyoda-ku

Claims (2)

[Claims] (1) The exhaust gas containing toxic gas discharged from the reactor is sucked, the sucked exhaust gas is sent to a scrubber, and the scrubber is treated with an oxidizer solution, water, acid solution, or alkaline solution to remove most of the harmful gases. In an exhaust gas treatment method in which after gas is removed, the gas is sent to a gas processing cylinder filled with a purifying agent to be purified and made into harmless gas. An exhaust gas treatment method characterized by removing sticky substances from exhaust gas generated and entrained when passing through a scrubber in an adsorption tower. (2) Equipped with a cylindrical adsorption tower body having a space for suspending the purifying agent inside, the bottom of the body is provided with an inlet for introducing exhaust gas connected to the exhaust gas outlet of the scrubber, and the upper is provided with an exhaust port for discharging exhaust gas, and the above-mentioned inlet is covered with a cap having a diameter larger than that of the main body, with a gap formed between the top surface of the inlet pipe formed protruding from the bottom surface of the adsorption tower main body and the bottom surface of the main body. At the same time, a hole for exhaust gas outflow is provided in the side wall of the introduction pipe, and the exhaust gas is introduced from the hole through the gap between the introduction pipe and the cap into the main body through the gap between the cap and the bottom of the main body. is the mouth;
A fluidized bed used in an exhaust gas treatment method, characterized in that the exhaust gas is transferred by a blower from the inlet, through the adsorption tower body, and to the outlet, so that a purifying agent placed inside the body is suspended. type adsorption tower.