JP2014147863A - Gas treatment system and gas treatment method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a gas treatment system capable of efficiently and continuously perform adsorption and desorption of a gas containing an organic solvent by using an adsorbent, and to provide a gas treatment method using the gas treatment system.SOLUTION: The gas treatment system includes: a treatment gas inlet line 32 which introduces a treatment gas; a pre-treatment adsorption tank 29 provided in the treatment gas inlet line 32 and accommodating a pre-treatment adsorbent 30; and a return gas line 28 which returns a return gas pushed out of a condenser and/or a separator by a desorption gas to an upstream side of the treatment gas inlet line 32 than the pre-treatment adsorption tank 29.

Description

  The present invention provides a gas processing apparatus and a gas processing capable of performing in parallel a process of adsorbing an organic solvent contained in an organic solvent-containing gas using an adsorbent and a process of desorbing the adsorbed organic solvent. It is about the method.

  In recent years, emission concentration regulations for harmful air pollutants have been strengthened, and it is desired to reduce the concentration of exhaust gas from a gas processing apparatus.

  2. Description of the Related Art Conventionally, gas processing apparatuses are provided with a pair of adsorption tanks that adsorb an organic solvent of a gas to be treated with an adsorbent, and a gas supply means and a desorption gas supply means for each adsorption tank, and the adsorption tank is treated. Means is provided for switching between an adsorption process for supplying gas and a desorption process for supplying desorption gas.

  An activated carbon fiber (ACF) (hereinafter referred to as ACF) is used as an example of an adsorbent for a gas processing apparatus. ACF has an excellent function of adsorbing a low-concentration organic solvent-containing gas, and has been used as an adsorbent for a long time. For example, a gas processing apparatus in which an ACF is fixed to a support or is formed in a cylindrical shape by self-supporting and arranged vertically in a core material is disclosed in Japanese Patent Laid-Open No. 51-38278 (Patent Document 1). Proposed.

  Also, a similar adsorption / desorption device is proposed in Japanese Utility Model Publication No. 7-2028 (Patent Document 2), Japanese Utility Model Publication No. 7-2029 (Patent Document 3), and Japanese Utility Model Publication No. 7-2030 (Patent Document 4). Has been. In any of these methods, vapor is jetted onto the core material storing the ACF, and the organic solvent adsorbed on the ACF is desorbed.

Japanese Patent Laid-Open No. 51-38278 No. 7-2028 No. 7-2029 No. 7-2030

  In the case of granular activated carbon, the pores involved in adsorption are macropores, whereas in ACF, micropores are used, so the adsorption / desorption rate of organic solvent is faster with ACF, and the desorption time is completed in a short time. Therefore, the quality of the recovered solvent is good.

  Further, once the adsorbent is desorbed with water vapor, the adsorbent is once moistened, so that it is necessary to dry the adsorbent before the next desorption in order to maintain the adsorption performance in a long-term operation. If this drying is insufficient, as the operation proceeds, the wet portion of the adsorbent spreads, and the adsorption performance is greatly reduced. Since ACF is dried much faster than granular activated carbon, the case where the adsorption process also serves as drying is generally used.

  However, as the concentration of the organic solvent in the gas to be treated increases, the weight of the adsorbent per treatment air volume increases, so that it is difficult to perform drying in the adsorption process, and the following various measures have been taken.

  (1) Providing a drying process alone: This measure requires the addition of one drying adsorption tank, which increases the size of the gas processing apparatus and complicates the processing system.

  (2) Increasing the pre-adsorption temperature of the gas to be treated: This measure decreases the adsorption efficiency as the adsorption temperature is increased.

  (3) Lowering the relative humidity before adsorption of the gas to be treated: This measure requires an auxiliary device for removing water.

  (4) Diluting the gas to be treated to increase the air volume: This measure lowers the adsorption efficiency because the adsorbed organic solvent concentration decreases.

  Even if the measures described above are performed, the adsorption process, particularly in the initial stage of the adsorption process, is not sufficiently dried, and the adsorbent is moist and high temperature, so the adsorption capacity of the adsorbent has not completely recovered, The organic solvent sometimes leaked into the treated gas.

  Further, since the gap between the adsorbent attachment portions and the gap due to filling is generated in a very small amount, the gas to be treated leaks from these gaps, and the removal performance in the adsorption step of only one stage is 98 to 99. % Was the limit, and in order to further improve the removal performance, it was necessary to perform a multi-stage adsorption system connected in series.

  Further, the desorption gas desorbed in the desorption step is cooled by a condenser, and further separated and recovered as a recovery solvent by a separator. In order to prevent pressurization of the capacitor and / or separator, it is necessary to open the gas phase portion of the capacitor and / or separator.

  However, since the gas staying in the condenser and / or separator pushed out by the desorption gas is an unconcentrated high-concentration organic solvent-containing gas close to the saturated vapor pressure, an oxidative decomposition facility that processes the high-concentration organic solvent-containing gas It was necessary to attach a recovery facility. Hereinafter, the high-concentration organic solvent-containing gas staying in the capacitor and / or separator pushed out by the desorption gas is referred to as “return gas”. In particular, in the serial multistage adsorption system, which requires high removal performance, complete treatment of “return gas” was an absolute condition.

  In the initial stage of the desorption process, the gas to be treated that remains in the adsorption tank is pushed out to the condenser and / or the separator with desorption steam. However, since most of the gas to be treated is not cooled and concentrated, “return gas” corresponding to the volume of the adsorption tank is discharged in a short time. After that, the organic solvent-containing vapor that is almost cooled and condensed is sent to the condenser and / or the separator, so that the flow rate of the “return gas” is significantly reduced.

  That is, the air volume of the “return gas” becomes the largest at the initial stage of the desorption process and then significantly decreases, so that it has been difficult to recover the organic solvent in the “return gas” with high efficiency.

  In addition, the separated and recovered organic solvent is often reused from the viewpoint of environmental considerations and manufacturing cost reduction. Therefore, in order to improve the recovery rate, "return gas" that contains a high concentration of organic solvent. Must be recovered efficiently.

  Therefore, the present invention provides a gas processing apparatus and a gas processing method using this gas processing apparatus, which can perform adsorption and desorption of an organic solvent-containing gas with high efficiency and continuously using an adsorbent. With the goal.

  With the recent improvement in environmental awareness, regulations on the content of organic solvents in exhaust gas have been strengthened, and the reduction of organic solvent content has become active. When the concentration of the organic solvent in the gas to be treated is high, the removal performance is required to be 99% or more, and therefore the number of cases in which the series multistage adsorption method is performed is increasing.

  As the order of the serial multi-stage adsorption system, the first stage process for first subjecting the gas to be treated to adsorption is the first adsorption process, and thereafter the adsorption process connected in series to the treatment path as the treatment efficiency is increased to two stages. The number will increase with the second stage (second adsorption process) and the third stage (third adsorption process).

  In order to avoid degrading the desorption efficiency, it is best to perform the desorption process after the first adsorption process, which is the first stage of the adsorption process, is completed. The treatment cycle in the tank may be repeated from the desorption process → the second adsorption process → the first adsorption process → the desorption process.

  In the serial multistage adsorption system, the present invention provides a pretreatment adsorption tank filled with a pretreatment adsorbent in the preceding stage of the gas supply unit to be treated, and the return gas pushed out by the desorption gas is disposed upstream of the pretreatment adsorption tank. , And after mixing with the gas to be processed, by providing a means for passing through the pretreatment adsorption tank and processing in the first stage adsorption tank, the fluctuation of the adsorption process inlet gas concentration due to the return gas is greatly reduced. Therefore, it is possible to prevent deterioration of the adsorbent and deterioration of performance due to heat of adsorption. It is another object of the present invention to provide a gas processing apparatus capable of recovering an organic solvent in a higher yield than when the return gas is separately processed by a processing facility, and is more compact and lower in running cost.

  The gas treatment apparatus according to the present invention has an adsorbent capable of adsorbing an organic solvent, and a gas to be treated containing the organic solvent and heated steam for desorbing the organic solvent from the adsorbent are alternately supplied. Having at least three treatment tanks, a heating steam supply unit for introducing the heating steam into one of the treatment tanks selected from a plurality of the treatment tanks, and a plurality of the treatment tanks in series are connected in series. A gas supply unit for introducing the gas to be processed into a plurality of the processing tanks connected in series in multiple stages, and a gas phase unit communicating with the heating steam supply unit, and the processing is performed when the heating steam is supplied. A recovery mechanism including a capacitor and / or a separator for recovering the organic solvent from the desorption gas discharged from the tank.

  The process gas supply unit includes a process gas inlet line for introducing the process gas, and a pretreatment adsorption tank provided in the process gas inlet line and containing a pretreatment adsorbent.

  The recovery mechanism section has a return line that returns the return gas pushed out of the capacitor and / or the separator by the desorption gas to the upstream side of the pretreatment adsorption tank of the process gas inlet line.

In one embodiment, the adsorbent is activated carbon fiber or granular activated carbon.
In one embodiment, the pretreatment adsorbent is a material selected from at least one of the group of granular activated carbon, activated carbon fiber, zeolite, silica gel, ion exchange resin, and activated alumina.

  A gas treatment method according to the present invention is a gas treatment method for recovering an organic solvent from a gas to be treated containing an organic solvent, wherein the capacitor and / or the Alternatively, the return gas extruded from the separator is mixed with the gas to be processed, and the desorption gas after passing through the pretreatment adsorption tank is supplied from the gas to be processed supply unit to the plurality of remaining gases connected in series. It introduce | transduces into the said processing tank and collect | recovers organic solvents from the to-be-processed gas containing an organic solvent.

  According to the gas processing apparatus and the gas processing method using this gas processing apparatus based on this invention, it is possible to perform adsorption and desorption of the organic solvent-containing gas with high efficiency and continuously using the adsorbent.

It is a figure which shows the 1st process of the structure of the gas processing apparatus in this Embodiment, and the gas processing method using this gas processing apparatus. It is a figure which shows the 2nd process of the gas processing method using the gas processing apparatus in this Embodiment. It is a figure which shows the 3rd process of the gas processing method using the gas processing apparatus in this Embodiment. It is a figure which shows the result of the Example of a gas processing method using the gas processing apparatus in this Embodiment, and a comparative example.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the following embodiments, the same or corresponding parts are denoted by the same reference numerals in the drawings, and the description thereof may not be repeated. In the embodiments described below, when referring to the number, amount, and the like, the scope of the present invention is not necessarily limited to the number, amount, and the like unless otherwise specified.

  The organic solvent used in the present specification is methylene chloride, chloroform, carbon tetrachloride, ethylene chloride, trichloroethylene, tetrachloroethylene, O-dichlorobenzene, m-dichlorobenzene, Freon-112, Freon-113, HCFC, HFC, bromide. Propyl, butyl iodide, methyl acetate, ethyl acetate, propyl acetate, butyl acetate, vinyl acetate, methyl propionate, methyl acrylate, ethyl acrylate, butyl acrylate, methyl methacrylate, diethyl carbonate, ethyl formate, diethyl ether, Dipropyl ether, tetrahydrofuran, dibutyl ether, anisole, methanol, ethanol, isopropanol, n-butanol, 2-butanol, isobutanol, t-butanol, allyl alcohol, pentanol, hep Nord, ethylene glycol, diethylene glycol, phenol, O-cresol, m-cresol, p-cresol, xylenol, acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, phorone, acrylonitrile, n-hexane, isohexane, cyclohexane, methylcyclohexane, n- Heptane, n-octane, n-nonane, isononane, decane, dodecane, undecane, tetradecane, decalin, benzene, toluene, m-xylene, p-xylene, o-xylene, ethylbenzene, 1,3,5-trimethylbenzene, N -Refers to methylpyrrolidone, dimethylformamide, dimethylacetamide, dimethylsulfoxide, and the like.

(Gas treatment apparatus 100)
With reference to FIG. 1, the structure of the gas processing apparatus 100 in this Embodiment is demonstrated. FIG. 1 is a diagram illustrating a configuration of a gas processing apparatus 100 according to the present embodiment. The gas processing apparatus 100 is configured to realize a serial multistage adsorption method, and includes a first processing tank 2, a second processing tank 3, and a third processing tank 4.

  The first treatment tank 2 includes a cylindrical first adsorbent 5A, the second treatment tank 3 includes a cylindrical second adsorbent 5B, and the third treatment tank 4 includes a cylindrical third adsorbent. Includes 5C. In the first adsorbent 5A, the second adsorbent 5B, and the third adsorbent 5C, the gas to be processed passes from the outside to the inside, the adsorption process is performed, and the heating steam passes from the inside to the outside. Thus, the desorption process is performed. ACF is used for the first adsorbent 5A, the second adsorbent 5B, and the third adsorbent 5C.

  The first processing tank 2, the second processing tank 3, and the third processing tank 4 are communicated with the processing gas introduction line 31 and the desorption gas line 24. In order to open / close the communication to the processing gas introduction line 31 and open / close the communication to the desorption gas line 24, the first processing tank 2, the second processing tank 3, and the third processing tank 4 are respectively A first automatic lower damper 9, a second automatic lower damper 10, and a third automatic lower damper 11 are provided.

  The first branch line 31A that branches into the first treatment tank 2 of the process gas introduction line 31 is provided with a first introduction on-off valve 21, and the first branch line 31A is connected to the first process gas introduction line 31B. Furthermore, the first dilution gas introduction line 31C is connected to the first processing gas introduction line 31B. A second introduction opening / closing valve 18 is provided in the first processing gas introduction line 31B.

  The second branch line 31D that branches into the second treatment tank 3 of the process gas introduction line 31 is provided with a third introduction on-off valve 22, and the second branch line 31D is connected to the second process gas introduction line 31E. Furthermore, a second dilution gas introduction line 31F is connected to the second processing gas introduction line 31E. A fourth introduction opening / closing valve 19 is provided in the second processing gas introduction line 31E.

  The third branch line 31G that branches into the third treatment tank 4 of the process gas introduction line 31 is provided with a fifth introduction opening / closing valve 23, and the third branch line 31G is connected to the third process gas introduction line 31H. Furthermore, a third dilution gas introduction line 31I is connected to the third processing gas introduction line 31H. A sixth introduction opening / closing valve 20 is provided in the third processing gas introduction line 31H.

  Above the first treatment tank 2, a first automatic upper damper 6, a first derivation line 31J, and a second derivation line 31K that control the flow of the gas to be treated are provided. The first derivation opening / closing valve 12 is provided in the first derivation line 31J, and the second derivation opening / closing valve 15 is provided in the second derivation line 31K.

  Above the second treatment tank 3, a second automatic upper damper 7, a third derivation line 31L, and a fourth derivation line 31M that control the flow of the gas to be treated are provided. The third lead-out opening / closing valve 13 is provided in the third lead-out line 31L, and the fourth lead-off opening / closing valve 16 is provided in the fourth lead-out line 31M.

  Above the third treatment tank 4, a third automatic upper damper 8, a fifth derivation line 31N, and a sixth derivation line 31P that control the flow of the gas to be treated are provided. A fifth derivation opening / closing valve 14 is provided in the fifth derivation line 31N, and a sixth derivation opening / closing valve 17 is provided in the sixth derivation line 31P.

  A condenser 25 is connected to the desorption gas line 24, and a separator 27 is connected to a recovery liquid line 26 connected to the condenser 25. The separator 27 has a liquid phase region 27A and a gas phase region 27B. From the liquid phase region 27A of the separator 27, the recovery solvent K is recovered by the recovery line 27C.

  A return gas line 28 is connected to the gas phase region of the capacitor 25 and the separator 27. The return gas line 28 is introduced into the process gas inlet line 32. The processing gas inlet line 32 is connected to the processing gas introduction line 31, and the pretreatment adsorption tank 29 and the blower 1 are provided in the processing gas inlet line 32. The pretreatment adsorption tank 29 has a pretreatment adsorbent 30.

  The gas processing apparatus 100 has a heating steam supply device 34, and the heating steam sent out from the heating steam supply device 34 passes through the heating steam line 35, the first processing tank 2, the second processing tank 3, and the third processing tank. 4 is supplied.

  A first heating steam branch line 35A branched from the heating steam line 35 communicates with the first processing tank 2, and a first steam opening / closing valve 36 is provided in the first heating steam branch line 35A. A second heating steam branch line 35B branched from the heating steam line 35 communicates with the second treatment tank 3, and a second steam opening / closing valve 37 is provided in the second heating steam branch line 35B. A third heating steam branch line 35C branched from the heating steam line 35 communicates with the third treatment tank 4, and a third steam opening / closing valve 38 is provided in the third heating steam branch line 35C.

  In the gas processing apparatus 100, the first automatic upper damper 6, the second automatic upper damper 7, the third automatic upper damper 8, the first automatic lower damper 9, the second automatic lower damper 10, the third automatic lower damper 11 , First introduction on-off valve 21, second introduction on-off valve 18, third introduction on-off valve 22, fourth introduction on-off valve 19, fifth introduction on-off valve 23, sixth introduction on-off valve 20, first derivation on-off valve 12, Second derivation on-off valve 15, third derivation on-off valve 13, fourth derivation on-off valve 16, fifth derivation on-off valve 14, sixth derivation on-off valve 17, heating steam supply device 34, first steam on-off valve 36, second The operation and opening / closing of the steam on / off valve 37, the third steam on / off valve 38, the condenser 25, the separator 27, and the blower 1 are appropriately controlled by a control device (not shown) so as to realize the following gas processing method.

  In the gas processing apparatus 100, at least the heating steam supply device 34, the first heating steam branch line 35A, the first steam on-off valve 36, the second heating steam branch line 35B, the second steam on-off valve 37, and the third heating The steam branch line 35C and the third steam on-off valve 38 constitute a heating steam supply unit.

  Further, at least the blower 1, the processing gas inlet line 32, the processing gas introduction line 31, the first branch line 31A, the first processing gas introduction line 31B, the first dilution gas introduction line 31C, the second introduction on-off valve 18, the first Introduction opening / closing valve 21, second branch line 31D, second processing gas introduction line 31E, second dilution gas introduction line 31F, fourth introduction opening / closing valve 19, third introduction opening / closing valve 22, third branch line 31G, third treatment The gas introduction line 31H, the third dilution gas introduction line 31I, the sixth introduction on-off valve 20, and the fifth introduction on-off valve 23 constitute a processing gas supply unit.

  At least the desorption gas line 24, the condenser 25, the recovery liquid line 26, the separator 27, and the recovery line 27C constitute a recovery mechanism unit.

(Gas treatment method)
Next, a gas processing method using the gas processing apparatus 100 having the above configuration will be described with reference to FIGS. 1 to 3. FIGS. 1 to 3 are views showing first to third steps of a gas processing method using the gas processing apparatus 100 in the present embodiment.

  In the first process shown in FIG. 1, the first treatment tank 2 of the gas processing apparatus 100 is subjected to the first adsorption process, the second treatment tank 3 is subjected to the second adsorption process, and the third treatment tank 4. The desorption process is performed.

  In the second step shown in FIG. 2, the first treatment tank 2 of the gas treatment apparatus 100 is subjected to the desorption process, the second treatment tank 3 is subjected to the first adsorption process, and the third treatment tank 4 is A second adsorption step is performed.

  In the third process shown in FIG. 3, the first treatment tank 2 of the gas treatment apparatus 100 is subjected to the second adsorption process, the second treatment tank 3 is subjected to the desorption process, and the third treatment tank 4 is A 1st adsorption | suction process is implemented.

<First step>
(First adsorption step of the first treatment tank 2)
Referring to FIG. 1, a gas to be processed A containing an organic solvent-containing gas is sent from a processing gas inlet line 32 to a first processing tank 2 that is a first adsorption process by a blower 1. The first automatic lower damper 9 is controlled to open the first branch line 31 </ b> A and close the desorption gas line 24.

  The first automatic upper damper 6 is controlled to an open state that allows the gas to be processed A to flow through the first adsorbent 5A. Further, the first introduction on-off valve 21 is controlled to be in an open state, and the third introduction on-off valve 22 and the fifth introduction on-off valve 23 are controlled to be in a closed state.

  Gas adsorption is performed by the first adsorbent 5A of the first treatment tank 2, and the first adsorption process outlet gas B is derived from the second derivation line 31K. The second derivation on-off valve 15 is controlled to be in an open state, and the first derivation on-off valve 12 is controlled to be in a closed state. Further, the first steam on-off valve 36 of the first heating steam branch line 35A is controlled to be closed.

(Second adsorption step of the second treatment tank 3)
Since the first adsorption process outlet gas B contains the organic solvent leaked in the first adsorption process, it is serially connected to the second treatment tank 3 serving as the second adsorption process in order to perform further adsorption treatment. It is connected and sent as the second adsorption inlet gas C to the second processing gas introduction line 31E. The second automatic lower damper 10 is controlled to open the second branch line 31D side and close the desorption gas line 24.

  At this time, in order to promote the drying of the second adsorbent 5B in the second treatment tank 3 during the second adsorption step, the second adsorption inlet gas C is supplied with the dilution gas L whose air volume is controlled from the second dilution gas introduction line 31F. Is mixed. The fourth introduction opening / closing valve 19 is controlled to be in an open state.

  The dilution gas L is a gas added to promote drying of the adsorbent in the adsorption process after the second adsorption process, and includes any one of outside air, instrument air, nitrogen gas, and argon gas. It is good to be done.

  The second adsorption inlet gas C is purified air D after being adsorbed by the second adsorbent 5B in the second treatment tank 3 and is led out of the gas processing apparatus 100 from the third lead-out line 31L. The The second automatic upper damper 7 is controlled to an open state that allows the second adsorption inlet gas C to flow in the second adsorbent 5B. Further, the third derivation on / off valve 13 is controlled to be in an open state, and the fourth derivation on / off valve 16 is controlled to be in a closed state. Further, the second steam opening / closing valve 37 of the second heating steam branch line 35B is controlled to be closed.

(Desorption process of the third treatment tank 4)
In the first step, the gas to be treated is not sent to the third treatment tank 4, and the third automatic lower damper 11 controls the third branch line 31G to be closed and the desorption gas line 24 to be opened. Is done. Further, in the third automatic upper damper 8, the gas flow from the outside to the inside of the third adsorbent 5C is closed, and the desorption heating steam from the heating steam supply device 34 passes through the third heating steam branch line 35C. The third adsorbent 5C is introduced from the inside to the outside. The third steam on / off valve 38 of the third heating steam branch line 35C is controlled to be in an open state.

  In the third treatment tank 4, heated steam is ejected, and the organic solvent adsorbed on the third adsorbent 5 </ b> C is desorbed from the third adsorbent 5 </ b> C. The desorbed organic solvent gas is sent to the capacitor 25 through the desorption gas line 24.

  The desorbed organic solvent gas and the heated steam are condensed by the condenser 25, and a condensate containing a high concentration organic solvent is sent to the separator 27 through the recovery liquid line 26. The condensate is separated into an organic solvent and water in the separator 27, and the recovered solvent K is recovered from the recovery line 27C.

  The return gas staying in the capacitor 25 and the separator 27 is pushed out by the desorption gas, introduced into the processing gas inlet line 32 through the return gas line 28, and mixed with the gas A to be processed.

  The gas to be processed A and the return gas introduced from the processing gas inlet line 32 are processed in the preprocessing adsorption tank 29 and then sent to the first processing tank 2. In the first step, the above steps are repeated, and the recovered solvent K is recovered from the recovery line 27C.

<Second step>
With reference to FIG. 2, in the second process, the first treatment tank 2 of the gas treatment apparatus 100 is subjected to the desorption process, the second treatment tank 3 is subjected to the first adsorption process, and the third treatment tank 4. The first automatic upper damper 6, the second automatic upper damper 7, the third automatic upper damper 8, the first automatic lower damper 9, the second automatic are controlled by a control device (not shown) so that the second adsorption step is performed. Lower damper 10, third automatic lower damper 11, first introduction on-off valve 21, second introduction on-off valve 18, third introduction on-off valve 22, fourth introduction on-off valve 19, fifth introduction on-off valve 23, sixth introduction on-off valve Valve 20, first derivation on-off valve 12, second derivation on-off valve 15, third derivation on-off valve 13, fourth derivation on-off valve 16, fifth derivation on-off valve 14, sixth derivation on-off valve 17, capacitor 25, separator 27 , Blower 1, heating steam supply device 34, first heating steam branch line 35A, first steam Closing 36, the second heating steam branch line 35B, second steam-off valve 37, the third heating steam branch line 35C, and, the operation of the third steam-off valve 38, opening and closing switching of the valves are controlled appropriately.

<Third step>
Referring to FIG. 3, in the third process, the first treatment tank 2 of the gas treatment apparatus 100 is subjected to the second adsorption process, the second treatment tank 3 is subjected to the desorption process, and the third treatment tank 4. The first automatic upper damper 6, the second automatic upper damper 7, the third automatic upper damper 8, the first automatic lower damper 9, and the second automatic are controlled by a control device (not shown) so that the first adsorption step is performed. Lower damper 10, third automatic lower damper 11, first introduction on-off valve 21, second introduction on-off valve 18, third introduction on-off valve 22, fourth introduction on-off valve 19, fifth introduction on-off valve 23, sixth introduction on-off valve Valve 20, first derivation on-off valve 12, second derivation on-off valve 15, third derivation on-off valve 13, fourth derivation on-off valve 16, fifth derivation on-off valve 14, sixth derivation on-off valve 17, capacitor 25, separator 27 , Blower 1, heating steam supply device 34, first heating steam branch line 35A, first steam Closing 36, the second heating steam branch line 35B, second steam-off valve 37, the third heating steam branch line 35C, and, the operation of the third steam-off valve 38, opening and closing switching of the valves are controlled appropriately.

  As described above, by controlling the processing cycle in each processing tank to repeat the cycle of the desorption process → the second adsorption process → the first adsorption process → the desorption process, in the gas processing apparatus 100 in the present embodiment. Thus, it is possible to continuously process the gas A to be processed.

  Thus, according to the gas processing apparatus 100 in the present embodiment, the one-stage adsorption is performed by the series multistage adsorption method in which the organic solvent-containing gas as the gas to be treated A is processed in two or more stages of series-connected treatment tanks. High removal rate can be achieved compared to the method.

  Further, according to the gas processing apparatus 100 in the present embodiment, the return gas is sent to the preceding stage of the pretreatment adsorption tank 29, mixed with the gas to be treated A, and passed through the pretreatment adsorption tank 29, whereby the treatment is performed. A substance that degrades the adsorbent provided in the tank can be removed by the pretreatment adsorption tank 29.

  The substance that degrades the adsorbent herein refers to a non-desorbable substance such as a high boiling point substance having a boiling point of 200 ° C. or higher, an oxidizing gas, a polymerizable substance, and the like. In addition, it is possible to reduce the fluctuation of the gas concentration at the inlet of the adsorption process due to the return gas and to level it. As a result, thermal runaway due to heat of adsorption generated in the first stage adsorption tank can be suppressed, and it is possible to prevent deterioration of the adsorbent and lowering of the adsorption performance.

  Moreover, according to the gas processing apparatus 100 in this Embodiment, return gas is mixed with to-be-processed gas, and it carries out an adsorption | suction collection process again in the 1st process tank, A return gas is oxidative decomposition equipment and collection | recovery equipment. It can be expected to obtain a higher recovery efficiency of the organic solvent than when it is separately treated.

  In addition, according to the gas processing apparatus 100 in the present embodiment, no equipment for separately processing the return gas is required, so that the space for the gas processing apparatus can be saved, and the manufacturing cost is higher than that of the conventional gas processing apparatus. It can be expected to be inexpensive.

  Moreover, according to the gas processing apparatus 100 in this Embodiment, since the installation which processes a return gas separately is not required, it can be anticipated that the running cost of a gas processing apparatus is restrained cheaply conventionally.

  Further, according to the gas processing apparatus 100 in the present embodiment, the return gas is processed in the first stage processing tank, so that the concentration of the gas to be processed increases, but leaked out in the first adsorption step. Since the organic solvent-containing gas is adsorbed without any problem by the second-stage adsorbent connected in series, the gas to be treated can be processed with the same removal performance as that of the conventional serial multistage adsorption method.

The adsorbent used in the gas processing apparatus 100 in the present embodiment may be ACF or granular activated carbon. As used herein, ACF refers to a specific surface area of 300 to 300 obtained by treating raw materials such as acrylonitrile (PAN) fiber, rayon fiber, coal pitch fiber, phenol resin resin, petroleum pitch fiber, and plant-derived fiber by an existing method. It is preferable that the diameter is about 3000 m ² / g, the fiber diameter is about ² μm to 30 μm, the fiber length is about 0.5 mm to 100 mm, and the average pore diameter is about 4 to 30 mm.

  Hereinafter, the gas treatment apparatus 100 according to the present embodiment will be described in more detail with reference to examples.

<Example>
An organic solvent-containing gas, which is an example of the gas to be treated, is methylene chloride, and the adsorbent is ACF “K-FILTER” 3.8 kg / tank manufactured by Toyobo Co., Ltd. The amount of vapor required for one desorption is 1 .9 kg.

A gas to be treated at 25 ° C. containing 22,000 ppm of methylene chloride was blown from the blower 1 to the first treatment tank 2 serving as the first adsorption step at an air volume of 2.7 Nm ³ / min. Subsequently, the first adsorption process outlet gas B discharged from the first treatment tank 2 was blown to the second treatment tank 3 serving as the second adsorption process as the second adsorption inlet gas C. At this time, the second adsorption inlet gas C was diluted with 0.6 Nm ³ / min of outside air and the temperature was adjusted to 40 ° C. After being processed in the second processing tank 3, it was discharged out of the system from the third lead-out line 31L as clean air.

  Each process was switched when the methylene chloride concentration of the first adsorption process outlet gas B discharged from the first treatment tank 2 reached 1,100 ppm. While the 1st processing tank 2 was performing the 1st adsorption process, in the 3rd processing tank 4, the desorption vapor was spouted and the desorption process was performed.

  The desorption gas was condensed by a condenser 25 and separated into an organic solvent and water by a separator 27. The gas staying in the capacitor 25 and the separator 27 was pushed out by the desorption gas and sent as a return gas through the return gas line 28 to the process gas inlet line 32 in the preceding stage of the pretreatment adsorption tank 29. Granular activated carbon was used for the pretreatment adsorbent 30 in the pretreatment adsorption tank 29.

  The treatment cycle in a specific treatment tank is performed in the order of desorption process-> second adsorption process-> first adsorption process, and desorption process-> second adsorption process-> first adsorption process is 1 cycle, and a total of 8 cycles are carried out did. One set was made by 8-cycle operation, and this was repeated 100 sets, and the deterioration of each treatment tank ACF was checked.

<Comparative Example 1>
Except that the pretreatment adsorption tank 29 was not provided in the series two-stage adsorption method, the same gas treatment as in the above example was performed, and the deterioration of ACF was confirmed.

<Comparative example 2>
The return gas line 28 and the pretreatment adsorption tank 29 were not provided in the series two-stage adsorption method, and the return gas was separately processed by an oxidative decomposition treatment apparatus. Otherwise, the same gas treatment as in the above example was performed, and the deterioration of ACF was confirmed.

<Comparative Example 3>
The conditions of the gas to be treated, the adsorbent, and the amount of desorbed vapor were set in the same manner as in the above example, and the gas treatment was carried out by the one-stage adsorption method instead of the series two-stage adsorption method. The gas remaining in the condenser and separator pushed out by the desorption gas was sent as a return gas to the pretreatment adsorption tank. A total of 12 cycles were carried out, with one cycle consisting of the adsorption step and the desorption step. A set of 12 cycles was used, and this was repeated 66 sets, and ACF deterioration was confirmed.

  In the adsorption steps of Examples and Comparative Examples 1 to 3, the concentration of the gas discharged out of the system from the final outlet of the adsorption step and the concentration of the first adsorption step inlet gas were measured using a total hydrocarbon meter manufactured by Shimadzu Corporation. And measured.

  The BET specific surface area of the ACF before and after the deterioration confirmation was performed using a specific surface area / pore distribution measuring device (Gemini 2375) manufactured by Micromeritics Japan GK. The ACF was vacuum dried at 120 ° C. for 12 hours, and the amount of nitrogen gas adsorbed at the boiling point of liquid nitrogen (-195.8 ° C.) was measured in a relative pressure range of 0.02 to 0.95. It was created. Based on the result in the range of relative pressure 0.02-0.15, it computed by BET method.

  The micropore pore volume of ACF with a pore diameter of 10 mm or less before and after the deterioration confirmation was measured using a specific surface area / pore distribution measuring device (Gemini 2375) manufactured by Micromeritics Japan LLC. The ACF was vacuum dried at 120 ° C. for 12 hours, and the amount of nitrogen gas adsorbed at the boiling point of liquid nitrogen (-195.8 ° C.) was measured in a relative pressure range of 0.02 to 0.95. It was created.

  This result was analyzed by the MP method with an analysis range of 0 to 20 cm, t determination formula H. The analysis was performed under the conditions of J, and the micropore pore volume having a pore diameter of 10.03 mm or more was subtracted from the total micropore pore volume from the results of the micropore pore size distribution number table at the time of adsorption.

  In FIG. 4, the concentration of methylene chloride at the inlet and outlet of the examples and comparative examples 1 to 3, the recovery rate of liquid methylene chloride separated by the separator after completion of the cycle, and the adsorption / desorption cycle of about 800 times were repeated. The surface property of ACF after is shown.

The surface physical properties of the ACF before cycle operation were such that the BET specific surface area was 1610 m ² / g, and the total micropore volume of 10 cm or less was 0.64 m ³ / g.

  As shown in FIG. 4, according to the gas processing apparatus in this embodiment and the gas processing method using this gas processing apparatus, there is a two-stage adsorption system in series and a return gas, compared with Comparative Example 1 in which no pretreatment adsorption tank is provided. The adsorption process outlet concentration and methylene chloride recovery were the same.

  However, in the surface property evaluation of ACF after repeating the adsorption / desorption cycle about 800 times, it was found that the deterioration was observed in Comparative Example 1, whereas the gas treatment apparatus in this example did not deteriorate at all. It can be said that it was effective that the temperature of the excess ACF due to heat of adsorption could be suppressed by allowing the gas to be treated to pass through the pretreatment adsorption tank and leveling the adsorption inlet.

  The gas treatment apparatus in this example has the same surface physical properties of ACF after repeating the adsorption / desorption cycle about 800 times as compared with Comparative Example 2 in which the two-stage adsorption system is in series, no return gas is used, and no pretreatment adsorption tank is used. There was no deterioration at all.

  Moreover, although the average methylene chloride density | concentration of an adsorption | suction outlet was equivalent, it became clear that a methylene chloride recovery rate improved about 11.4%. This can be said that the return gas line 28 and the pretreatment adsorption tank 29 of this embodiment are effective in improving the organic solvent recovery rate. In addition, 4.9% of methylene chloride, which could not be recovered in the examples, means an amount dissolved or dispersed on the water layer side in the separator, and is irrelevant to the discharge amount outside the system.

  The gas treatment apparatus of the present invention has a one-stage adsorption method and a return gas, and the average methylene chloride concentration at the adsorption outlet is significantly lower than that of the gas treatment apparatus with the pretreatment adsorption tank (Comparative Example 3). It was revealed that the rate was also improved by about 1.0%.

  As described above, according to the gas treatment apparatus of this example, by returning to the serial multistage adsorption method and providing the gas line and the pretreatment adsorption tank, the average removal rate and the recovery rate of the organic solvent are improved, and the adsorbent is deteriorated. We were able to demonstrate that the effect is exhibited by suppression.

  As described above, according to the gas treatment device in this embodiment and the gas treatment method using this gas treatment device, the return gas is sent to the front stage of the pretreatment adsorption tank in the serial multistage adsorption method and mixed with the gas to be treated. After that, by providing a means for passing through the pretreatment adsorption tank and processing in the first stage adsorption tank, it is possible not only to achieve a higher removal rate than the conventional apparatus but also for pretreatment of substances that degrade the adsorbent It can be removed in an adsorption tank.

  Moreover, since the fluctuation | variation of the adsorption process inlet_port | entrance gas concentration by return gas can be remarkably eased and leveled, deterioration of an adsorbent and a performance fall by adsorption heat can be prevented. Further, by treating the return gas in the first stage adsorption tank, the organic solvent can be obtained at a higher recovery rate than when the return gas is treated separately. Furthermore, since no separate equipment for processing the return gas is required, it is possible to provide a gas processing apparatus that is more compact than conventional and has a lower running cost.

  In addition, in order to implement | achieve the serial multistage adsorption | suction system, the gas processing apparatus 100 of the said embodiment uses the 3 tank structure of the 1st processing tank 2, the 2nd processing tank 3, and the 3rd processing tank 4, The method of adopting the series two-stage adsorption method and repeating the cycle of the desorption process → the second adsorption process → the first adsorption process → the desorption process in each treatment tank has been explained. However, the method is limited to the series two-stage adsorption method. Rather, the same effects can be obtained even when employed in a series multi-stage adsorption system such as a series three-stage adsorption system or a series four-stage adsorption system.

  The above-described embodiments and examples disclosed herein are illustrative and non-restrictive in every respect. The technical scope of the present invention is defined by the terms of the claims, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

  DESCRIPTION OF SYMBOLS 1 Blower, 2 1st processing tank, 3rd processing tank, 4th 3rd processing tank, 5A 1st adsorption material, 5B 2nd adsorption material, 5C 3rd adsorption material, 6 1st automatic upper damper, 7 2nd automatic Upper damper, 8 Third automatic upper damper, 9 First automatic lower damper, 10 Second automatic lower damper, 11 Third automatic lower damper, 12 First derivation on-off valve, 13 Third derivation on-off valve, 14 Fifth derivation on-off Valve, 15 second derivation on-off valve, 16 fourth derivation on-off valve, 17 sixth derivation on-off valve, 18 second introduction on-off valve, 19 fourth introduction on-off valve, 20 sixth introduction on-off valve, 21 first introduction on-off valve , 22 3rd introduction on-off valve, 23 5th introduction on-off valve, 24 desorption gas line, 25 condenser, 26 recovery liquid line, 27 separator, 27A liquid phase area, 27B gas phase area, 27C recovery line, 28 return gas line, 29 Pretreatment adsorption 30 pretreatment adsorbent, 31 process gas introduction line, 31A first branch line, 31B first process gas introduction line, 31C first dilution gas introduction line, 31D second branch line, 31E second process gas introduction line, 31F 2nd dilution gas introduction line, 31G 3rd branch line, 31H 3rd process gas introduction line, 31I 3rd dilution gas introduction line, 31J 1st derivation line, 31K 2nd derivation line, 31L 3rd derivation line, 31M 1st 4 lead-out line, 31N fifth lead-out line, 31P sixth lead-out line, 32 processing gas inlet line, 34 heating steam supply device, 35 heating steam line, 35A first heating steam branching line, 35B second heating steam branching line, 35C 3rd heating steam branch line, 36 1st steam on-off valve, 37 2nd steam on-off valve, 38 3rd steam Off valve, 100 gas treatment device.

Claims (4)

Having an adsorbent capable of adsorbing an organic solvent, having at least three treatment tanks in which a gas to be treated containing the organic solvent and heated steam for desorbing the organic solvent from the adsorbent are alternately supplied;
A heating steam supply unit for introducing the heating steam into one processing tank selected from a plurality of the processing tanks;
A plurality of treatment tanks connected in series in a multistage connection, and a gas to be processed supply section that introduces the gas to be processed into the plurality of treatment tanks connected in series in multiple stages,
A recovery mechanism including a condenser and / or a separator that has a gas phase portion communicated with the heating steam supply portion and recovers the organic solvent from the desorption gas discharged from the processing tank when the heating steam is supplied; Prepared,
The to-be-treated gas supply unit is
A processing gas inlet line for introducing the processing gas;
A pretreatment adsorption tank provided in the treatment gas inlet line and containing a pretreatment adsorbent;
The recovery mechanism section is
The gas processing apparatus which has a return line which returns the return gas extruded from the said capacitor | condenser and / or a separator by the said desorption gas to the upstream from the adsorption tank for pre-processing of the said process gas inlet line.   The gas processing apparatus according to claim 1, wherein the adsorbent is activated carbon fiber or granular activated carbon.   The gas according to claim 1 or 2, wherein the pretreatment adsorbent is a material selected from at least one of the group of granular activated carbon, activated carbon fiber, zeolite, silica gel, ion exchange resin, and activated alumina. Processing equipment. A gas treatment method for recovering an organic solvent from a gas to be treated containing an organic solvent,
Using the gas treatment device according to any one of claims 1 to 3,
The return gas extruded from the capacitor and / or separator by the desorption gas is mixed with the gas to be processed, and the desorption gas after passing through the pretreatment adsorption tank is supplied from the gas to be processed supply section. A gas processing method for introducing an organic solvent from a gas to be processed that is introduced into a plurality of remaining processing tanks connected in series and containing an organic solvent.

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