JP2009082797A - Organic solvent-containing gas treatment system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an organic solvent-containing gas treatment system which is free from the deterioration of elimination performance due to temperature deflection or the undermining of durability due to temperature increase through stabilizing the control temperature etc. of a combustion device by curbing the density fluctuation of a desorption gas obtained from a gas enriching device and which, therefore, can ensure the stabilized operation of the system. <P>SOLUTION: This organic solvent-containing gas treatment system comprises a gas enriching device which operates to allow an organic solvent included in a gas containing the low-density volatile organic solvent to be adsorbed with the use of an adsorbent during an adsorption cycle, and discharge the enriched desorption gas by blowing a heated fluid to the adsorbent adsorbing the organic solvent during a desorption cycle. Further, this system is characterized in that an adsorption element filled with the adsorbent is arranged in a flow path of the enriched desorption gas to be discharged from the gas enriching device. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an organic solvent-containing gas treatment system that performs adsorption concentration treatment of a gas containing a volatile organic solvent (so-called VOC-containing gas) using an adsorbent.

  In semiconductor factories, liquid crystal factories, painting factories, printing factories, film laminating factories, etc., volatile organic compounds such as toluene, isopropyl alcohol (hereinafter referred to as IPA), xylene, methyl ethyl ketone (hereinafter referred to as MEK), and ethyl acetate (hereinafter referred to as “ethyl acetate”) , VOC), and the evaporated VOC diffuses into the space in the factory, and if it floats, the human body is adversely affected. Moreover, if the VOC-containing gas is released into the atmosphere without being treated, the environment will be polluted.

  Therefore, from the viewpoint of preventing air pollution, VOC emission standards are set in regulated plants, and it is obliged to observe the emission standards.

  Examples of gas purification methods for decomposing or removing VOC-containing gas include, for example, a regenerative combustion method in which VOC-containing gas is directly preheated and burned with a burner, a catalytic combustion method in which oxidative decomposition is performed with a catalyst, and preheated with a heat storage material and burned. Thermal storage combustion systems are known, but especially when processing low-concentration VOC-containing gas, an adsorption concentrator that concentrates low-concentration gas in order to further reduce the amount of energy used during combustion. It is installed (for example, refer to Patent Document 1).

  FIG. 1 shows a general adsorption concentrator.

The preconcentration unit 60, for example 1000 Nm ³ / min of VOC-containing gas while discharging a cleaned air is adsorbed and removed by the adsorbent, and desorption at e.g. 200 Nm ³ / min at 180 ° C. of heated air, Shokazeryou This is a device for obtaining a concentrated gas with high concentration.

  FIG. 2 shows an organic solvent treatment system using a general adsorption concentrator.

  In this system, the desorption gas obtained by the adsorption concentrator 60 is oxidized and decomposed by the combustion device 61 and discharged as clean air. By performing the adsorption concentration process, the amount of fuel used at the time of combustion can be reduced, and the system can economically process the gas containing the organic solvent.

Japanese Patent Laid-Open No. 10-000330

  In the concentrator for concentrating and processing the low-concentration VOC-containing gas, when a fixed type or cylinder type concentrator is used, or when the desorption wind speed fluctuates due to reinforcement of a rib or the like even in a disk type concentrator. A variation as shown in FIG. 3 is observed in the concentration of the desorption gas.

  Due to this fluctuation in concentration, for example, in a post-treatment device such as a combustion device, the control of the combustion temperature necessary for oxidative decomposition of VOC is not stable, and if the temperature fluctuates low, the removal rate may decrease, In the case where the fluctuation is high, there is a problem that the temperature becomes higher than the endurance temperature of the combustion device and abnormal combustion temperature occurs.

  In order to solve the above-mentioned problems, the present invention finds that the cause of unstable control of the combustion temperature of the aftertreatment device is the concentration fluctuation of the desorption gas, and the installation of the adsorbent as a method for suppressing the concentration fluctuation. And intensively studied the type and physical properties of the adsorbent. As a result, by installing an adsorbent in the flow path of the concentrated desorption gas discharged from the concentrator, concentration fluctuations can be remarkably suppressed, and problems with post-treatment devices such as combustion devices can be solved. I found it.

That is, the present invention is as follows.
1. Desorption concentrated by adsorbing an organic solvent in a gas containing a low-concentration volatile organic solvent during an adsorption operation and spraying a heated fluid on the adsorbent that has adsorbed the organic solvent during the desorption operation. An organic solvent-containing gas processing system comprising a concentrating device for discharging a gas, wherein an adsorbent is disposed in a flow path of the concentrated desorption gas discharged from the concentrating device.
2. 2. The organic solvent-containing gas treatment system according to 1 above, wherein the adsorbent used in the concentrator is filled in a cylindrical adsorbent.
3. 2. The organic solvent-containing gas treatment system according to 1 above, wherein the heating fluid sprayed onto the adsorbent that has adsorbed the organic solvent during the desorption operation is heated air at 80 to 230 ° C.
4). 2. The organic solvent-containing gas treatment system according to 1 above, wherein the adsorbent filled in the adsorbent disposed in the flow path of the desorption gas is an inorganic adsorbent.
5). 5. The organic solvent-containing gas treatment system as described in 4 above, wherein the inorganic adsorbent filled in the adsorbent disposed in the flow path of the desorption gas is zeolite.
6). 6. The organic solvent-containing gas treatment system according to 5 above, wherein the zeolite charged in the adsorbent disposed in the desorption gas flow path is a hydrophobic zeolite.
7). 7. The organic solvent-containing gas treatment system as described in 6 above, wherein the hydrophobic zeolite filled in the adsorbent disposed in the desorption gas flow path is a zeolite having a Si / Al ratio of 10 to 2000 and a pore diameter of 5 to 9 mm. .
8). A desorption gas concentrated by adsorbing an organic solvent in a gas containing a low-concentration volatile organic solvent during an adsorption operation and blowing a heated fluid onto the adsorbent that adsorbed the organic solvent during the desorption operation. A concentrating device for discharging
A combustion apparatus for burning the desorption gas;
An organic solvent-containing gas treatment system in which an adsorbent is disposed between a concentrator outlet of a concentrated desorbed gas discharged from the concentrator and a combustion device.

  Since the organic solvent-containing gas processing system of the present invention can significantly suppress concentration fluctuations by installing an adsorbent in the flow path of the concentrated desorption gas discharged from the concentrator, the control temperature of the combustion apparatus, etc. This is an organic solvent-containing gas treatment system that can be stably operated without lowering the removal performance due to temperature fluctuations or lowering the durability due to higher temperatures.

  The principle of the concentrator in the present invention is shown in FIG. A concentrator 1 for adsorbing an organic solvent in a gas containing a large amount of air and a low concentration of VOC has a cylindrical case 3 that can rotate around a central axis 2, and adsorbs VOC in the case 3. The adsorbent 4 having a honeycomb structure (with the communication path oriented in the central axis direction) is accommodated to constitute a tubular adsorbent as a whole.

  An adsorbing portion 1a and a desorbing portion 1b are partitioned on a moving path along which the cylindrical adsorbing member rotates, and an adsorbent (adsorbing member) 4 passes through the adsorbing portion 1a and the desorbing portion 1b alternately. ing.

  In the adsorbing portion 1a, for example, a VOC-containing gas supply pipe 5 for introducing a VOC-containing gas generated in the factory and a purified air for sending purified air purified by the adsorbent 4 of the concentrating device 1 to the factory. A delivery tube 6 is provided.

  Moreover, the desorption part 1b is provided with a desorption air supply pipe 7 for blowing high-temperature dry air, for example, 180 ° C., that is, desorption heating air, onto the adsorbent 4 that has adsorbed VOC. Is set to be about 1/2 to 1/30 of the volume of the VOC-containing gas, so that the desorbed gas is concentrated.

  Examples of the concentrator include a disc rotor type concentrator shown in FIG. 5 and a cylinder type concentrator shown in FIG. This will be described below.

<Disc rotor type concentrator>
A disk rotor type concentrator 10 shown in FIG. 5 is configured to rotate a honeycomb-structured columnar adsorbent 11 around a rotation shaft 12, and a VOC-containing gas is introduced from one of the cylindrical adsorbents 11, Purified clean air is taken out from the other side.

  Ducts 13 and 14 are arranged on both sides of the cylindrical adsorbent body 11 so as to face each other. Desorption heated air is blown from the duct 13 to the cylindrical adsorbent body 11, and desorption gas flows from the other duct 14. It is supposed to be discharged.

  In the figure, an arrow A indicates the rotation direction of the columnar adsorbent 11.

<Cylinder type concentrator>
The cylinder type concentrator 20 shown in FIG. A VOC-containing gas is introduced from the outer peripheral side of the adsorbent 21 toward the center thereof, and the purified clean air is taken out from the space inside the adsorbent 21. .

  With respect to the adsorbent 21 that has adsorbed the VOC, the desorption heated air is blown to the adsorbent 21 from one duct arranged so as to sandwich the adsorbent 21, that is, the desorption air supply pipe 22, and contains VOC. The desorption gas is discharged from the other duct, that is, the desorption outlet 23.

  Although it does not specifically limit in the said concentration apparatus, More preferably, it is a cylindrical adsorption body. The cylindrical disk rotor type concentrator can suppress desorption gas concentration fluctuations due to its structure, but the cylindrical cylinder type concentrator, in particular, changes the number of adsorbents when it is sent to the desorption zone. This is because desorption gas concentration fluctuations are always observed at regular intervals.

  The heating fluid sprayed onto the adsorbent that has adsorbed the organic solvent during the desorption operation is preferably heated air at 80 to 230 ° C. Below 80 ° C, the desorption efficiency is remarkably reduced and the performance of the concentrator cannot be fully exhibited. When it is above 230 ° C, when the adsorbent is deformed by the heat of the adsorbent or activated carbon is used. This is because there is a risk of combustion.

  The adsorbent filled in the adsorbent disposed in the flow path of the concentrated desorption gas discharged from the concentrator is preferably an inorganic adsorbent. This is because the desorption operation is performed at a high temperature of 80 to 230 ° C., and the organic adsorbent has a risk of thermal deterioration and combustion.

  The inorganic adsorbent filled in the adsorbent disposed in the flow path of the concentrated desorption gas discharged from the concentrator is preferably zeolite. Inorganic adsorbents include activated alumina, silica gel, and the like, since zeolite is the most excellent for VOC adsorption. More preferably, the zeolite is a hydrophobic zeolite. This is because the desorption gas is remarkably high in moisture by concentrating the moisture of the raw gas simultaneously with the VOC gas. Therefore, a hydrophobic zeolite that does not more adsorb moisture that inhibits VOC adsorption is effective. Hydrophobic zeolite is effective in that it has a low catalytic activity and can suppress deterioration due to oxidative polymerization reaction, which is observed in, for example, ketone solvent treatment, as compared with activated carbon.

  The hydrophobic zeolite filled in the adsorbent disposed in the flow path of the concentrated desorption gas discharged from the concentrator is a zeolite having a Si / Al molar ratio of 10 to 2000 and a pore diameter of 5 to 9 mm. Is preferred. This is because when the Si / Al molar ratio is too low, the hydrophobicity decreases and water is preferentially adsorbed over VOC, and if the Si / Al molar ratio is 2000 or more, the hydrophobicity is This is because it is not improved, and only the manufacturing cost is increased. Further, if the pore diameter is 5 mm or less, a gas having a large molecular diameter cannot be adsorbed, and if the pore diameter is too large, the VOC adsorption rate decreases as supported by Kelvin's capillary condensation theory.

  The apparatus for treating the desorbed gas desorbed by the concentrating apparatus of the present invention is not particularly limited, but it is particularly effective in the case of a combustion apparatus in which concentration fluctuation affects the control and performance of the apparatus.

  The organic solvent-containing gas treatment system of the present invention will be described based on the following examples.

In the organic solvent-containing gas treatment system shown in FIG. 7, the gas is adsorbed by a cylinder-type concentrator 60 using hydrophobic zeolite as an adsorbent with an air volume of 400 m ³ / min containing isopropyl alcohol at a concentration of 300 ppm. Then, it was desorbed with 180 ° C. heated air and concentrated to obtain a concentrated gas having an average temperature of 65 ° C. with an air flow rate of 20 m ³ / min and an average of 6500 ppm CH ₄ and a concentration fluctuation of 3000 to 8700 ppm CH ₄ . Next, the adsorbent 62 installed between the desorption gas outlet line 63 of the cylinder type concentrator and the direct combustion unit 61 is 100 kg of Y-type zeolite pellets having a Si / Al molar ratio of 100 and a pore diameter of 7 kg ( 1.5φ × 5 mm pellets) was put and passed at a passing linear velocity of 30 cm / s. By installing this adsorbent, the concentration of the concentrated gas was 6500 ppm CH ₄ on average, and the concentration fluctuation could be remarkably suppressed to 6300 to 6700 ppm CH ₄ (concentration fluctuation suppressing effect is shown in FIG. 3). As a result, the combustion outlet temperature of the combustion apparatus averaged 750 ° C. and the temperature fluctuation was 700 to 800 ° C., but the average fluctuation was 750 ° C., the concentration fluctuation was suppressed to 745 to 755 ° C., and the removal rate was 99.9%. Further, the heat resistant temperature of 800 ° C. or lower can be stably maintained, and the direct combustion apparatus can be stably subjected to oxidative decomposition.

  According to the present invention, since the concentration fluctuation can be remarkably suppressed by installing the adsorbent in the flow path of the concentrated desorption gas discharged from the concentrator, the control temperature of the combustion apparatus is stabilized. Thus, it is possible to provide an organic solvent-containing gas treatment system that can be stably operated without a decrease in removal performance due to temperature fluctuations or a decrease in durability due to a high temperature.

It is explanatory drawing which showed the general adsorption concentration apparatus. It is explanatory drawing which showed the general adsorption | suction concentration system. An example of the concentration fluctuation of the desorption gas is shown, and at the same time, the effect of suppressing the concentration fluctuation of the example is shown. The principle of a concentrator is shown. The structure of a disk type concentrator is shown. The structure of a cylinder type concentration apparatus is shown. It is explanatory drawing of the VOC containing gas processing system shown in an Example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Concentrator 1a Adsorption part 1b Desorption part 2 Central axis 3 Case 4 Adsorbent 5 VOC containing gas supply pipe 6 Purified air delivery pipe 7 Desorption air supply pipe 10 Disc rotor type concentrator 11 Cylindrical adsorber 12 Rotating shaft 13 Duct DESCRIPTION OF SYMBOLS 14 Duct 20 Cylinder type concentrator 21 Adsorbent 22 Desorption air supply pipe 23 Desorption outlet part 40 VOC containing gas processing system 60 Concentrator 61 Combustion device 62 Adsorbent 63 Desorption outlet gas line

Claims (8)

  Desorption concentrated by adsorbing an organic solvent in a gas containing a low-concentration volatile organic solvent during an adsorption operation and spraying a heated fluid on the adsorbent that has adsorbed the organic solvent during the desorption operation. An organic solvent-containing gas processing system comprising a concentrating device for discharging a gas, wherein an adsorbent is disposed in a flow path of the concentrated desorption gas discharged from the concentrating device.   The organic solvent-containing gas treatment system according to claim 1, wherein the adsorbent used in the concentrator is filled in a cylindrical adsorbent.   The organic solvent-containing gas processing system according to claim 1, wherein the heating fluid sprayed onto the adsorbent that has adsorbed the organic solvent during the desorption operation is heated air at 80 to 230 ° C.   2. The organic solvent-containing gas processing system according to claim 1, wherein the adsorbent filled in the adsorbent disposed in the desorption gas flow path is an inorganic adsorbent.   5. The organic solvent-containing gas treatment system according to claim 4, wherein the inorganic adsorbent filled in the adsorbent disposed in the desorption gas flow path is zeolite.   6. The organic solvent-containing gas treatment system according to claim 5, wherein the zeolite filled in the adsorbent disposed in the desorption gas flow path is a hydrophobic zeolite.   The organic solvent-containing gas treatment according to claim 6, wherein the hydrophobic zeolite packed in the adsorbent disposed in the desorption gas flow path is a zeolite having a Si / Al ratio of 10 to 2000 and a pore diameter of 5 to 9 mm. system. A desorption gas concentrated by adsorbing an organic solvent in a gas containing a low-concentration volatile organic solvent during an adsorption operation and blowing a heated fluid onto the adsorbent that adsorbed the organic solvent during the desorption operation. A concentrating device for discharging
A combustion apparatus for burning the desorption gas;
An organic solvent-containing gas treatment system in which an adsorbent is disposed between a concentrator outlet of a concentrated desorbed gas discharged from the concentrator and a combustion device.