JP2926932B2 - Exhaust gas treatment method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Summary] Regarding an exhaust gas treatment method in a factory or the like that discharges a large amount of exhaust gas, even if the introduced exhaust gas has a low concentration, organic substances in the exhaust gas can be effectively adsorbed on activated carbon. Exhaust gas purifying exhaust gas by introducing an exhaust gas containing an organic substance component into an adsorption tower having activated carbon, and adsorbing the organic substance component on the activated carbon. Processing method,
A first step of supplying a gas in a first state having an organic matter concentration at the time of initial generation to an enrichment module, and separating an organic matter component from exhaust gas in a first state in the enrichment module. A second step of generating a second state exhaust gas containing a high concentration of the component, and a third step of supplying the second state exhaust gas to the chamber,
And a fourth step of detecting an organic substance concentration in the exhaust gas in the second state, wherein the organic substance concentration detected in the fourth step enables the adsorption tower to perform an effective purification treatment.
When the concentration does not reach a predetermined concentration set in advance, after mixing the exhaust gas in the second state with the newly supplied exhaust gas in the first state, the exhaust gas in the first state is concentrated in the concentration module. The second to fourth steps are performed again by supplying the organic substance concentration detected in the fourth step,
When the concentration reaches the predetermined concentration, the exhaust gas in the second state is supplied to the adsorption tower to perform a treatment so as to perform a purification treatment.

[Industrial applications]

The present invention relates to an exhaust gas treatment method in a factory or the like that discharges a large amount of exhaust gas.

In recent years, for example, a large amount of organic solvents are used in semiconductor factories and the like, and these organic solvents are constantly volatilized during use, and generate exhaust gas containing organic components. In order to maintain the stability of various processes and a favorable working environment in a factory, it is necessary to exhaust the exhaust gas containing the organic components.

[Conventional technology]

As a method of treating the exhaust gas, a “combustion method” in which the exhaust gas is decomposed by heat treatment and an “adsorption method” in which an organic component contained in the exhaust gas is removed by filtering the exhaust gas are known. For example, in a semiconductor factory or the like, an “adsorption method” that is excellent in running cost, processing stability, and the like is generally used.

At present, there are roughly two types of adsorption methods as described below.

i) Fluidized bed type recovery treatment method Exhaust gas purifying means: Organic substances in the exhaust gas are adsorbed on spherical activated carbon.

Features: The spherical activated carbon is circulated between an adsorption tower for performing a filtration treatment and a desorption tower for performing a treatment for separating (desorbing) organic components adsorbed on the spherical activated carbon by the filtration treatment from the spherical activated carbon.

ii) Fixed-bed recovery treatment method 1 Exhaust gas purifying means: Organic substances in the exhaust gas are adsorbed on spherical activated carbon or activated carbon fiber.

Features: Two treatment towers containing spherical activated carbon,
The adsorption and desorption of organic substances in the exhaust gas are performed alternately (several hours).

In both methods, organic components separated from activated carbon or activated carbon fibers in a desorption tower are recovered as waste liquid by liquefaction. In particular, unlike the fixed-bed recovery method, the fluidized-bed recovery method is different from the fixed-bed recovery method in that during the separation process performed in the desorption tower, the steam for heating the desorption tower is not mixed with the organic components separated from the spherical activated carbon or the activated carbon fiber. The water collected by the steam does not mix with the waste liquid recovered in the first step. For this reason, the present method can recover a high concentration and a small amount of waste liquid, and is widely and generally used.

FIG. 3 is an explanatory view showing a processing apparatus according to the fluidized bed type recovery processing method. In the figure, 21 is an adsorption tower for performing an exhaust gas filtration treatment, and 22 is an organic column for adsorbing organic components adsorbed on the filtered spherical activated carbon. A desorption tower for performing a process of separating (desorbing) from the activated carbon; 23, a condenser for liquefying the organic matter component; 24, an exhaust gas inlet; 25, a purified gas exhaust outlet for discharging exhaust gas after filtration; It is an outlet. Spherical activated carbon circulates between the adsorption tower 21 and the desorption tower 22.

Exhaust gas generated in various processes in the factory is introduced into the adsorption tower 21 through an exhaust gas inlet 24. While the exhaust gas passes through the adsorption tower 21, organic components in the exhaust gas are removed by being adsorbed on the spherical activated carbon. The exhaust gas from which the organic components have been removed is discharged from the purified gas exhaust port 25.

The activated carbon on which the organic components are adsorbed is heated by moving into the desorption tower 22 being heated by steam. Then, the organic component adsorbed on the activated carbon is vaporized to separate (desorb) the organic component. The activated carbon that has been subjected to the separation treatment of the adsorbed organic components is circulated again to the adsorption tower 21 and is used again for the adsorption of the organic components.

The high-concentration organic component gas generated by vaporization in the separation process is cooled and liquefied by moving into the condenser 23 cooled by cold water, and is collected as waste liquid by the waste liquid outlet 26.

The processing capacity of this processing device is determined by the circulation speed of spherical activated carbon,
The flow rate of the exhaust gas is a major factor. This is 1
This is because there is a limit in the adsorption capacity of each spherical activated carbon.

[Problems to be solved by the invention]

For example, when an exhaust gas containing a high concentration of an organic component that exceeds the adsorption capacity of activated carbon circulating in the adsorption tower is introduced into the adsorption tower, the exhaust gas is discharged without being sufficiently purified.

However, it is difficult to completely purify the exhaust gas even when the exhaust gas having an organic substance concentration within the adsorption capacity of the activated carbon circulating in the adsorption tower is introduced into the adsorption tower. This is because the molecules of the organic components contained in the exhaust gas are very small, so that the molecules of the organic components that pass through the gaps of the activated carbon circulating in the adsorption tower always occur. Therefore, the purified gas exhausted from the adsorption tower after the filtration treatment necessarily has an organic matter concentration (residual concentration) of a certain level or more.

Therefore, the organic matter concentration of the exhaust gas introduced into the adsorption tower is
If the residual concentration is close to the above, there is a problem that the effect of the filtration treatment cannot be obtained much.

On the other hand, for example, in a semiconductor factory, various organic solvents used are not used in all steps. That is, the organic component volatilized from the organic solvent or the like is not always generated, and the concentration of the organic component in the exhaust gas is constantly changing. In clean rooms, etc., provided in semiconductor factories,
A large amount of air in the clean room is exhausted to maintain the cleanliness inside. For this reason, the organic components in the exhaust gas in these factories were generally low in concentration.

Therefore, the above problem becomes remarkable in these semiconductor factories and the like, and the conventional exhaust gas treatment method cannot perform a sufficient adsorption treatment.

SUMMARY OF THE INVENTION An object of the present invention is to provide an exhaust gas treatment method capable of effectively adsorbing organic components in activated carbon in the exhaust gas even when the introduced exhaust gas has a low concentration.

[Means for solving the problem]

FIG. 1 is a basic principle diagram of the present invention, and FIG. 1A shows the basic configuration. 1 is a concentration module for concentrating organic components contained in exhaust gas to a predetermined concentration,
2 is an adsorption tower, 3 is a chamber for measuring the concentration of organic substances in the exhaust gas and judging whether or not to supply the exhaust gas to adsorption or the like, and 4a and 4b are fans for blowing air. FIG. 2B is a model diagram of the enrichment module.

The enrichment module is comprised of microscopic tubes made of a membrane that is permeable to low molecular gases, ie, components normally present in air, such as oxygen and nitrogen. When the exhaust gas is supplied to the concentration module, the polymer gas, that is, the organic component volatilized from the organic solvent and the like passes through the inside of the tube, but the low molecular gas passes through the side wall of the tube, so that the low molecular gas and Polymer gas can be separated.

The present invention introduces an exhaust gas containing an organic component into an adsorption tower having activated carbon in order to solve the aforementioned problems,
An exhaust gas treatment method for purifying the exhaust gas by adsorbing the organic substance on the activated carbon, wherein the exhaust gas in a first state having an organic substance concentration at the time of initial generation is supplied to a concentration module. A second step of generating an exhaust gas in a second state containing a high concentration of an organic substance component by separating an organic substance component from the exhaust gas in the first state in the concentration module; Exhaust gas in the state, the third step of supplying the chamber, the fourth step of detecting the organic substance concentration in the exhaust gas of the second state, the organic substance concentration detected in the fourth step, The adsorption tower can perform an effective purification process, when the concentration has not reached a preset predetermined concentration, the second state exhaust gas was mixed with the newly supplied first state exhaust gas. Later, the first The second to fourth steps are performed again by supplying the exhaust gas in the state to the concentration module, and when the organic substance concentration detected in the fourth step has reached the predetermined concentration, the second The exhaust gas in the state described above is supplied to the adsorption tower to perform the treatment so as to perform the purification treatment.

[Action]

In the present invention, the low-molecular gas is separated and exhausted by introducing the exhaust gas into the concentration module, and the exhaust gas is circulated between the concentration module and the chamber until the organic matter concentration in the exhaust gas reaches a preset concentration. . Further, in order to concentrate the circulating exhaust gas, newly generated exhaust gas is constantly supplied to the enrichment module. Then, exhaust gas having a predetermined organic substance concentration is always supplied to the adsorption tower.

Therefore, even if the concentration of organic substances in the exhaust gas introduced into the adsorption tower is low, the exhaust gas is concentrated to a predetermined concentration and then sent to the adsorption tower, so that the adsorption tower can perform a sufficient adsorption treatment. You can.

〔Example〕

FIG. 2 is an explanatory view showing one embodiment of the present invention,
12 is a concentration module, 31, 32 are chambers, 41a, 41b, 42
a and 42b are fans, 50 is an exhaust duct leading to the adsorption tower,
51 is a general exhaust duct. A to F are photographic devices used in, for example, a lithography process. A to C constitute a photographic device group, and DF to a photographic device group.

In this embodiment, the photographic apparatus group or the exhaust gas in the first state generated from the photographic apparatus group is sent to the concentration modules 11 and 12, respectively. This concentration module 11, 12
Is composed of, for example, a fine tube using a polysulfine-based membrane, and the concentration module 1
Normal air components in the exhaust gas are separated by 1 and 12,
It is exhausted from the general exhaust duct 51.

The exhaust gas in the second state after the separation of the normal components in the air is sent to the chambers 31 and 32 to detect the concentration of the organic components contained therein.

At this time, if the concentration reaches a preset concentration at which the adsorption or the like can perform an effective operation, the fans 41a and 42a operate to discharge the exhaust gas in the second state into the exhaust duct. Sent to 50.

If the concentration has not reached the set value, the fans 41b and 42b operate, and the exhaust gas in the second state is
It is mixed with the photographic device group and the exhaust gas in the first state which is always generated from the photographic device group. Then, the exhaust gas in the first state is supplied to the concentration modules 11 and 12 again.

As a result, the concentration of organic substances contained in the photographic apparatus group and the exhaust gas generated from the photographic apparatus group gradually increases while circulating between the concentration modules 11 and 12 and the chambers 31 and 32. Then, the exhaust gas is sent to the exhaust duct 50 after being concentrated to a predetermined concentration. The exhaust duct 50 is connected to adsorption or the like, and exhaust gas of a constant concentration is always supplied to the adsorption tower.

Therefore, in the exhaust gas treatment method according to the present embodiment, the adsorption tower can perform the purification treatment efficiently and effectively. After the concentrated exhaust gas is sent to the adsorption tower, the treatment may be performed by the same process as in the related art.

〔The invention's effect〕

As explained above, according to the present invention, there is an effect that the concentration of the organic component in the exhaust gas sent to the adsorption tower is always constant.

Therefore, even if the generated exhaust gas has a low concentration, efficient and effective adsorption becomes possible, which greatly contributes to the improvement of the reliability and performance of the related exhaust gas treatment.

[Brief description of the drawings]

 FIG. 1 is a basic principle diagram of the present invention, FIG. 2 is an explanatory diagram showing an embodiment of the present invention, and FIG. 3 is an explanatory diagram showing a conventional exhaust gas treatment device. In the figure, 1, 11, 12 ... concentration module, 2, 21 ... adsorption tower, 3, 31, 32 ... chamber, 4a, 4b, 41a, 41b, 42a, 42b ... fan, 50 ... exhaust duct , 51 ... General exhaust duct, A to F ... Photo equipment, 22 ... Desorption tower, 23 ... Condenser, 24 ... Exhaust gas inlet, 25 ... Purified gas exhaust, 26 ... Waste liquid outlet.

Continuation of the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) B01D 53/02-53/12 B01D 53/22 B01D 53/34-53/96

Claims (1)

(57) [Claims] An exhaust gas treatment method for purifying exhaust gas by introducing an exhaust gas containing an organic substance component into an adsorption tower having activated carbon, and adsorbing the organic substance component on the activated carbon, comprising the steps of: A first step of supplying an exhaust gas in a first state having an organic substance concentration to a concentration module (1), and separating an organic substance component from the exhaust gas in the first state in the concentration module (1). A second step of generating an exhaust gas in a second state containing an organic substance component at a high concentration; a third step of supplying the exhaust gas in the second state to a chamber (3); A fourth step of detecting an organic substance concentration in the exhaust gas in the second state, wherein the organic substance concentration detected in the fourth step is a predetermined predetermined level at which the adsorption tower can perform an effective purification process. Concentration reached If the second state exhaust gas is mixed with the newly supplied first state exhaust gas, the first state exhaust gas is supplied to the enrichment module (1). The second to fourth steps are performed again.If the organic substance concentration detected in the fourth step has reached the predetermined concentration, the exhaust gas in the second state is supplied to the adsorption tower. An exhaust gas treatment method comprising performing a purification treatment.