JP6577339B2 - VOC processing system and method - Google Patents

Description

  The present invention relates to a VOC processing system.

  In recent years, VOC (Volatile Organic Compounds) are handled at various manufacturing sites. For example, in production facilities for adhesive tapes and various films, and industrial printing facilities that handle a large amount of printed matter, VOCs contained in the exhaust gas are processed by various means such as a combustion method and an adsorption recovery method, and reduced to a predetermined VOC concentration. Since then, it has been discharged out of the system. Various systems have been proposed as systems for purifying exhaust from facilities (see, for example, Patent Documents 1-3).

JP 2007-301480 A JP 2000-84340 A Japanese Patent Laid-Open No. 11-90177

  A type of system for processing VOCs vaporized in equipment that handles VOCs is a system that vents gas exhausted from the equipment to the adsorption rotor, adsorbs VOC to the adsorbent, and supplies the purified gas to the equipment again. is there. In such a system, in order to maintain the adsorption performance of the adsorption rotor, a regeneration facility for desorbing the VOC adsorbed on the adsorption rotor is provided. If this regeneration facility is formed with a closed-loop circulation path in which the VOC vapor desorbed by heating the adsorption rotor is condensed by a cooler, the VOC vaporized in the operating facility is continuously condensed as a solution solvent. A system that collects and does not discharge VOCs outside the system is theoretically feasible. As a result, the needs for environmental conservation, energy saving, and resource saving, which have been increasing in recent years, can be met.

  However, in the above-described system, the condensation recovery is not performed unless the VOC concentration in the gas circulating through the circulation path of the regeneration facility reaches a concentration that can be condensed by a low-temperature cooler. Therefore, when the operation of the facility that handles VOC is stopped, the VOC adsorbed by the adsorption rotor is reduced, the VOC concentration in the circulation path for regenerating the adsorption rotor is gradually decreased, and the condensation of VOC in the cooler of the regeneration facility is eliminated. The VOC concentration is balanced at the timing. Therefore, when the VOC concentration of the manufacturing facility that discharges VOC is balanced in a state exceeding the concentration that humans can enter (for example, 200 ppm), the facility that handles the VOC will be ventilated and the VOC will be ventilated. Will inevitably be released out of the system.

  Therefore, the present application has an object to provide a VOC processing system that suppresses as much as possible the amount of VOC released to the outside of the system when the facility handling the VOC is stopped and the inside of the facility is ventilated. .

  In order to solve the above problems, in the present invention, an adsorbent that adsorbs and recovers VOC while the VOC handling facility is stopped is provided separately from the adsorption rotor that adsorbs VOC during operation of the VOC handling facility.

  Specifically, it is a VOC processing system that recovers VOCs vaporized in equipment that handles VOCs, and forms a first circulation path that is a gas circulation path that returns from the equipment to the equipment through the adsorption zone of the adsorption rotor. The main adsorption recovery unit and the condensation that forms the second circulation path, which is a gas circulation path from the desorption zone of the adsorption rotor to the cooling zone of the adsorption rotor through the cooler and back to the desorption zone through the heater A recovery unit, and an adsorbent provided in at least one of the first circulation path and the second circulation path or a path communicating with the circulation path, and the VOC in the cooler is stopped by the stop of the equipment. A sub-adsorption recovery unit that adsorbs and recovers VOC in the gas in any circulation path with the adsorbent when there is no condensation.

  Even if the VOC processing system is the above, even if the VOC discharge from the equipment is reduced by stopping the equipment that handles the VOC, and the condensation of the VOC in the condenser of the condensation recovery unit that regenerates the adsorption rotor disappears, The residual VOC is adsorbed by an adsorbent provided separately from the adsorption rotor. For this reason, after the VOC handling facility stops, the VOC concentration in the circulation path for regenerating the adsorption rotor gradually decreases, and even if the VOC concentration in the cooler is eliminated and the VOC concentration is balanced, separately from the adsorption rotor Residual VOCs are adsorbed by the adsorbent provided, and the VOC concentration of the facility that handles VOCs can be further reduced. Therefore, when the facility that handles the VOC is stopped and the facility is ventilated, the amount of VOC released to the outside of the system is suppressed as much as possible.

  The sub-adsorption recovery unit has an adsorbent in the second circulation path, bypasses the adsorbent in the second circulation path when the equipment is in operation, and does not condense VOC in the cooler due to the equipment being stopped. In some cases, the adsorbent may be vented. The sub-adsorption recovery unit has an adsorbent in the first circulation path, bypasses the adsorbent in the first circulation path when the equipment is in operation, and does not condense VOC in the cooler due to the equipment being stopped. In some cases, the adsorbent may be vented. If the VOC treatment system is configured in this way, the adsorbent is bypassed when the equipment is in an operating state, so that the VOC is adsorbed on the adsorbent and can be prevented from becoming saturated. It can prepare for ventilation | gas_flowing of the adsorbent after an equipment stop.

  The sub-adsorption recovery unit has an adsorbent in the first circulation path, and when the facility is stopped, the adsorbent is heated to start regeneration of the adsorbent, and after the regeneration of the adsorbent is started, the VOC in the cooler is started. When the condensation disappears, the heating of the adsorbent may be stopped to ventilate the adsorbent. If the VOC processing system is configured in this way, the equipment that handles the VOC stops even if there is no flow path switching means such as a damper for changing the aeration state of the adsorbent provided separately from the adsorption rotor. The residual VOC can be adsorbed by the adsorbent after condensing and recovering in the cooler is lost.

  The first circulation path may be provided with a path that bypasses the adsorption zone of the adsorption rotor during adsorption by the adsorbent. When the adsorbent is provided in the first circulation path, if the path for bypassing the adsorption zone of the adsorption rotor is provided during the adsorption in the adsorbent, the adsorption rotor is vented during the adsorption of the residual VOC by the adsorbent. Therefore, the VOC adsorbed on the adsorption rotor is not desorbed and the decrease in the VOC concentration by the adsorbent is not hindered.

  In addition, a dryer is attached to the equipment, and when the equipment is stopped, the sub-adsorption recovery unit heats the adsorbent with the exhaust of the dryer and starts regeneration of the adsorbent. When the condensation of VOC is eliminated, the heating of the adsorbent by the dryer may be stopped to ventilate the adsorbent. If the heat of the dryer is used to regenerate the adsorbent, a heat source for regenerating the adsorbent can be omitted.

Further, a plurality of adsorbents may be provided in parallel depending on the type of VOC handled by the facility. If a plurality of adsorbents are provided in parallel according to the type of VOC handled in the facility, various types of VOCs can be prevented from being mixed in the solvent solution to be condensed and recovered.

  If it is said VOC processing system, the amount of VOC discharge | released when the equipment which handles VOC is stopped and the said equipment is ventilated can be suppressed as much as possible.

FIG. 1 is a diagram showing a VOC processing system according to the first embodiment. FIG. 2 is a view showing each section of the suction rotor. FIG. 3 is a state diagram of the VOC processing system according to the first embodiment when the dryer is stopped. FIG. 4 is a state diagram of the VOC processing system of the first embodiment when the adsorbent is regenerated. FIG. 5 is a diagram showing a VOC processing system of a comparative example. FIG. 6 is a diagram showing a VOC processing system according to the second embodiment. FIG. 7 is a state diagram of the VOC processing system of the second embodiment when the dryer is stopped. FIG. 8 is a state diagram of the VOC processing system of the second embodiment when the adsorbent is regenerated. FIG. 9 is a diagram showing a VOC processing system according to the third embodiment. FIG. 10 is a state diagram of the VOC processing system according to the third embodiment when the production facility shifts to a stopped state and generation of a new VOC stops. FIG. 11 is a state diagram of the VOC processing system of the third embodiment when the dryer is stopped. FIG. 12 is a state diagram of the VOC processing system of the third embodiment when the circulation in the second circulation path is stopped. FIG. 13 shows a first modification in which the VOC processing system of the third embodiment is modified. FIG. 14 shows a second modified example in which the VOC processing system of the third embodiment is modified. FIG. 15 is a diagram showing a modification of the VOC processing system according to the first embodiment. FIG. 16 is a diagram showing a VOC processing system according to the second embodiment provided with a path that bypasses the adsorption zone.

  Hereinafter, embodiments of the present invention will be described. Embodiment shown below is an example of this invention and the technical scope of this invention is not limited to the following embodiment.

<First Embodiment>
FIG. 1 is a diagram showing a VOC processing system according to the first embodiment. As shown in FIG. 1, the VOC processing system 1 of the first embodiment collects VOC vapor generated in a dryer (which is an example of “equipment” in the present application) 2 that dries an object to be coated with VOC. A main adsorption recovery unit 10 that forms a first circulation path 11 that is a gas circulation path from the dryer 2 through the adsorption zone 12Z1 of the adsorption rotor 12 to the dryer 2 again, and a desorption zone of the adsorption rotor 12 A condensing and recovering unit that forms a second circulation path 21 that is a gas circulation path from 12Z2 through the cooler 23 to the cooling zone 12Z3 of the adsorption rotor 12 and through the adsorption rotor heater 22 back to the desorption zone 12Z2. 20. The component of the gas circulating through the first circulation path 11 and the second circulation path 21 is not particularly limited. For example, mere air or a chemically stable inert gas such as nitrogen gas is suitable. Examples of the dryer 2 that dries an object to be coated with VOC include an adhesive tape production facility that discharges ethyl acetate as VOC. In addition, as equipment to which the VOC processing system 1 of the first embodiment can be applied, instead of the dryer 2, for example, painting equipment that simply applies VOC and does not heat, painting provided in a closed space or sealed space The equipment group which consists of equipment and a dryer, and other various equipment can be mentioned. Examples of the object on which the VOC is applied include an automobile.

  The first circulation path 11 is provided with a main circulation fan 13 that sucks the gas in the dryer 2 and blows it to the adsorption zone 12Z1 of the adsorption rotor 12. Further, in the first circulation path 11, a gas that is blown from the main circulation fan 13 and flows into the adsorption zone 12 </ b> Z <b> 1 of the adsorption rotor 12, and a gas that flows out of the adsorption zone 12 </ b> Z <b> 1 of the adsorption rotor 12 and returns into the dryer 2 again. The main circulation system regenerative heat exchanger 14 that performs heat exchange between the two is provided.

  The second circulation path 21 includes a condensation recovery system first circulation fan 24 that blows gas to the desorption zone 12Z2, and an adsorption rotor that heats the gas flowing from the condensation recovery system first circulation fan 24 to the desorption zone 12Z2 of the adsorption rotor 12. Heater 22, a cooler 23 that cools the gas that has passed through the desorption zone 12 </ b> Z <b> 2 of the adsorption rotor 12, and a condensation recovery system second circulation fan that blows the gas that has passed through the cooler 23 to the cooling zone 12 </ b> Z <b> 3 of the adsorption rotor 12. 25 is provided. The gas that has passed through the cooling zone 12Z3 of the adsorption rotor 12 flows to the condensation recovery system first circulation fan 24. In the second circulation path 21, condensation is performed to exchange heat between the gas flowing from the desorption zone 12 </ b> Z <b> 2 of the adsorption rotor 12 to the cooler 23 and the gas flowing from the cooler 23 to the condensation recovery system second circulation fan 25. A recovery system regenerative heat exchanger 26 is provided. The cooler 23 is provided with a drain pan (not shown) so that the condensed VOC dripped from the cooler 23 can be received by the drain pan and the VOC can be recovered. The adsorption rotor heater 22 may use the residual heat of the production facility that discharges the VOC as a heat source, or may use the heat of the electric heater as a heat source.

  In the middle of the path from the cooler 23 to the condensation recovery system regenerative heat exchanger 26, a first damper 31D1 for blocking the path is provided. A bypass path 32 that bypasses the first damper 31D1 is provided in the path from the cooler 23 to the condensation recovery system regeneration heat exchanger 26. The bypass path 32 is provided with a second damper 31D2 that blocks the bypass path 32, and an adsorbent 30 (an example of an “adsorption / recovery unit” in the present application) located on the downstream side of the second damper 31D2. It has been. In addition, the path connecting the second damper 31D2 and the adsorbent 30 is connected to a branch path 33 that branches from the middle of the path from the adsorption rotor heater 22 to the desorption zone 12Z2. The branch path 33 is provided with a third damper 31D3 that blocks the branch path 33.

  As the adsorbent 30, for example, activated carbon, zeolite, hydrophobic treated silica gel, or the like can be used. The necessary minimum amount of the adsorbent 30 is determined by the VOC concentrations of the first circulation path 11 and the second circulation path 21 when adsorption by the adsorbent 30 is performed and the volume of each circulation path. For example, the necessary minimum amount of the adsorbent 30 is obtained by multiplying the average VOC concentration of the first circulation path 11 by the volume of the first circulation path 11 and the average VOC concentration of the second circulation path 21 to the second circulation path 21. A value obtained by adding up the values multiplied by the volume (= average VOC concentration of the first circulation path 11 × same volume + average VOC concentration of the second circulation path 21 × same volume).

FIG. 2 is a view showing each section of the suction rotor 12. The adsorption rotor 12 carries an adsorbent mainly composed of synthetic zeolite, silica gel or the like inside a cylindrical member, and is configured so that gas flows along the axial direction inside. A section dividing cassette (not shown) is arranged on both end faces of the adsorption rotor 12, and the cassette passes through the gas passage area of the adsorption rotor 12 into at least three sections. The adsorption rotor 12 is rotatable relative to the section division cassette, and an adsorption zone 12Z1, a desorption zone 12Z2, and a cooling zone 12Z3 are formed in the adsorption rotor 12 by this cassette. The suction rotor 12 is not limited to one divided into three regions, and for example, a purge region or a preheating region may be further divided. When the adsorption rotor 12 is rotationally driven by a drive device such as a motor (not shown), the adsorbent carried in a specific region of the adsorption rotor 12 changes in the order of adsorption state, desorption state, and cooling state.

  In the VOC processing system 1 configured as described above, the following operation state is realized.

  For example, during the operation of the dryer 2, the main circulation fan 13 is rotating in the VOC processing system 1 as shown in FIG. 1. Thereby, in the 1st circulation path 11, the circulating flow which the gas attracted | sucked from the inside of the dryer 2 passes the adsorption | suction zone 12Z1, and returns to the inside of the dryer 2 arises again. The VOC vaporized in the dryer 2 is adsorbed by the adsorption zone 12Z1 of the adsorption rotor 12. For example, when about 4000 ppm of ethyl acetate gas flows into the adsorption zone 12Z1 from the dryer 2, the ethyl acetate is adsorbed in the adsorption zone 12Z1 of the adsorption rotor 12, and the ethyl acetate remaining in the gas that has passed through the adsorption zone 12Z1 becomes about 1000 ppm. Until it is removed by suction and sent to the dryer 2 again.

  Further, during the operation of the dryer 2, in the VOC processing system 1, the first damper 31D1 is opened, the second damper 31D2 and the third damper 31D3 are closed, and the cooler 23 and the adsorption rotor heater 22 are in an operating state. The condensation recovery system first circulation fan 24 and the condensation recovery system second circulation fan 25 are rotating. For this reason, in the second circulation path 21, the gas heated by the adsorption rotor heater 22 passes through the desorption zone 12Z2. Therefore, the VOC adsorbed in the adsorption zone 12Z1 is desorbed from the adsorption rotor 12 in the desorption zone 12Z2, and is sent to the cooler 23 on the gas circulating in the second circulation path 21. The VOC vapor desorbed from the adsorption rotor 12 and sent to the cooler 23 is condensed on the outer surface of the cooler 23, dropped onto a drain pan provided in the cooler 23, and collected as a solution solvent. The gas from which VOC has been removed by the condensation of VOC on the outer surface of the cooler 23 passes through the cooling zone 12Z3, is heated again through the adsorption rotor heater 22, and flows again into the desorption zone 12Z2. Since the saturated vapor pressure concentration of ethyl acetate is about 4200 ppm at −30 ° C., for example, if the cooler 23 is set to −30 ° C., the gas that has passed through the desorption zone 12Z2 contains about 28000 ppm of ethyl acetate. However, the ethyl acetate is condensed on the outer surface of the cooler 23, and the ethyl acetate remaining in the gas that has passed through the cooler 23 is condensed and removed to about 4200 ppm and sent to the cooling zone 12Z3.

  During the operation of the dryer 2, the VOC processing system 1 maintains the above-described operation state so that the VOC vaporized in the dryer 2 is continuously collected without leaking out of the system.

  FIG. 3 is a state diagram of the VOC processing system 1 of the first embodiment when the dryer 2 is stopped. When the production facility is stopped and no new VOC is generated in the dryer 2, the VOC concentration of the gas circulating in the first circulation path 11 and the second circulation path 21 decreases. When the VOC concentration uniquely determined by the cooling temperature of the cooler 23 is reached, the VOC cannot be condensed and recovered in the cooler 23, and the VOC of the gas circulating in the first circulation path 11 and the second circulation path 21 is lost. The concentration becomes an equilibrium concentration. The cooler 23 is a device that performs condensation recovery at about −30 ° C., and when the VOC is ethyl acetate, the VOC concentration of the gas circulating in the second circulation path 21 is in an equilibrium state at about 4200 ppm. Further, the VOC concentration of the gas circulating in the first circulation path 11 is in an equilibrium state at about 300 ppm, for example, depending on the performance of the adsorption rotor, the capacity of the circulation path, and the like.

Therefore, in the VOC processing system 1, the main circulation fan 13 rotates while the dryer 2 is stopped as shown in FIG. As a result, in the first circulation path 11, a gas sucked from the dryer 2 passes through the adsorption zone 12 </ b> Z <b> 1 and returns to the dryer 2 again, and the VOC remaining in the first circulation path 11 is absorbed by the adsorption rotor 12. Is adsorbed to the adsorption zone 12Z1. In the VOC processing system 1, the first damper 31D1 is closed, the second damper 31D2 is opened, and the third damper 31D3 is closed while the dryer 2 is stopped. The cooler 23 and the adsorption rotor heater 22 are closed. Is in an operating state, and the condensation recovery system first circulation fan 24 and the condensation recovery system second circulation fan 25 are rotating. For this reason, in the second circulation path 21, the gas heated by the adsorption rotor heater 22 passes through the desorption zone 12Z2. Therefore, the VOC adsorbed in the adsorption zone 12Z1 is desorbed from the adsorption rotor 12 in the desorption zone 12Z2, and is sent to the cooler 23 on the gas circulating in the second circulation path 21. The gas containing residual VOC that is desorbed from the adsorption rotor 12 and sent to the cooler 23 and cannot be completely removed by the condensation of VOC in the cooler 23 is removed in the process of passing through the adsorbent 30, and then After passing through the cooling zone 12Z3, it is heated again through the adsorption rotor heater 22 and flows again into the desorption zone 12Z2.

  For example, after the gas circulating through the second circulation path 21 reaches an equilibrium state with a VOC concentration of 4200 ppm, if the above-described system configuration shown in FIG. Although depending on the performance of 30, the VOC concentration of the gas that has passed through the adsorbent 30 can be reduced to about 30 ppm. The gas whose VOC concentration has been reduced to about 30 ppm passes through the cooling zone 12Z3, is heated by the adsorption rotor heater 22 and passes through the desorption zone 12Z2, whereby the VOC adsorbed on the adsorption rotor 12 is desorbed, The adsorption rotor 12 is regenerated. Therefore, the gas in the first circulation path 11 that is in an equilibrium state with a VOC concentration of about 300 ppm is further adsorbed when passing through the adsorption zone 12Z1, and the VOC concentration of the gas flowing from the dryer 2 to the adsorption zone 12Z1 is further increased. It goes down. For example, when the management concentration as a working environment where a person enters is 200 ppm, and the target value of the VOC concentration in the manufacturing facility is set to about 100 ppm, the VOC concentration of the gas flowing from the dryer 2 to the adsorption zone 12Z1 becomes 100 ppm. When the voltage drops to the above level, the operation of the VOC processing system 1 having the above-described system configuration shown in FIG. 3 is stopped. As a result, the VOC concentration in the production facility is suppressed as much as possible. If the target value of the VOC concentration in the manufacturing facility is high, the amount of VOC leaking out of the system increases, and if the target value of the VOC concentration in the manufacturing facility is low, the operation time of the VOC processing system 1 becomes long. The target value of the VOC concentration in the manufacturing facility is determined by comprehensively considering these values.

  By performing the above operation in the VOC processing system 1 while the dryer 2 is stopped, the VOC concentration remaining in the dryer 2 in the stopped state can be reduced as much as possible. Therefore, for example, when a person enters the dryer 2, the VOC concentration remaining in the dryer 2 is temporarily reduced, so that the dryer 2 remains in the dryer 2 even when it is connected to the outside of the system. The amount of VOC released outside the system is suppressed as much as possible.

The adsorbent 30 is regenerated as follows. FIG. 4 is a state diagram of the VOC processing system 1 of the first embodiment when the adsorbent 30 is regenerated. The adsorbent 30 is regenerated before the operation of the dryer 2 is started. That is, in the VOC processing system 1, as shown in FIG. 4, the first damper 31D1 is opened, the second damper 31D2 is closed, and the third damper 31D3 is opened. The condenser 22 is in an operating state, and the condensation recovery system first circulation fan 24 and the condensation recovery system second circulation fan 25 are rotating. The suction rotor 12 continues to rotate. In the second circulation path 21, the gas heated by the adsorption rotor heater 22 flows through the branch path 33 to the adsorbent 30, and the adsorbent 30 is heated. The VOC adsorbed on the adsorbent 30 is exposed to a high temperature and desorbed from the adsorbent 30. The gas that has passed through the adsorbent 30 joins the second circulation path 21 in a state including VOC desorbed from the adsorbent 30. In the second circulation path 21, there is a circulation flow in which the gas heated by the adsorption rotor heater 22 passes through the desorption zone 12 </ b> Z <b> 2, passes through the cooler 23, and flows again to the adsorption rotor heater 22 through the cooling zone 12 </ b> Z <b> 3. Therefore, the VOC desorbed from the adsorbent 30 contained in the gas joined again from the branch path 33 to the second circulation path 21 has a concentration of VOC vapor in the gas circulating in the second circulation path 21. If it is equal to or higher than the saturated vapor concentration at the temperature of the cooler 23, it is condensed on the outer surface of the cooler 23, and if it is less than the saturated vapor concentration at the temperature of the cooler 23, it is circulated as it is without condensing on the outer surface of the cooler 23 Keep doing. When regeneration of the adsorbent 30 is completed, the third damper 31D3 is closed, the ventilation of the adsorbent 30 is stopped, and the VOC processing system 1 is shifted to a steady operation state.

  FIG. 5 is a diagram showing a VOC processing system of a comparative example. As shown in FIG. 5, the VOC processing system 301 of the comparative example is obtained by omitting the bypass path 32 and the adsorbent 30 from the VOC processing system 1 of the first embodiment, and the other configurations are the same. As a system aimed at reducing the amount of VOC emission to the atmosphere to the limit, for example, as shown in FIG. 5, a system that removes VOC from the exhaust of the dryer 2 and returns it to the dryer 2 again can be considered. In this VOC processing system 301, the VOC vapor generated in the drying process in the dryer 2 is adsorbed by the adsorption rotor 12, and the VOC concentration is increased by desorbing the adsorbed VOC to a high temperature. It is condensed and recovered as a solution. However, after the dryer 2 is stopped, the VOC concentration in the gas passing through the cooler 23 is lowered with the decrease in the VOC concentration in the exhaust of the dryer 2, and cooling condensation cannot be performed. The concentration of VOC that cannot be condensed and recovered varies depending on the type of VOC and the cooling temperature, but a high VOC concentration reaches a level of several thousand ppm, and new adsorption of VOC in the exhaust of the dryer 2 becomes impossible (adsorption equilibrium state). For example, the concentration is 300 ppm, which is higher than the environmental standard concentration suitable for an operator to enter the dryer 2 after the dryer 2 is stopped. In this way, in the system that applies the means for concentrating VOC and recovering the solvent by cooling condensation and returning the total amount of the processed gas, the lower limit value of the VOC concentration of the processed gas is higher than the allowable working environment concentration. In order for the worker to enter for this purpose, it is necessary to take in fresh fresh air by exhausting the remaining VOC out of the system. In this case, several hundred ppm of VOCs are discharged outdoors at least for the production environment volume.

  In this regard, with the VOC processing system 1 according to the first embodiment, the VOC concentration that cannot be lowered by cooling condensation is temporarily adsorbed by the adsorbent 30, thereby allowing the amount of VOC to be discharged out of the system. It can be suppressed as much as possible. That is, with the VOC processing system 1 according to the first embodiment, after reaching a VOC concentration that cannot be cooled and condensed on the outer surface of the cooler 23, the adsorbent 30 that is not vented during normal operation is vented. As a result, VOC is adsorbed, and the VOC concentration in the air decreases. The VOC adsorbed by the adsorbent 30 is desorbed by passing a part of the heated gas for regeneration of the adsorption rotor 12 through the adsorbent 30 at the next startup of the dryer 2. Together with the new VOC generated, it can be recovered by normal cooling condensation in the cooler 23.

  The specific numerical values such as the VOC concentration shown above vary depending on the size and rotation speed of the adsorption rotor 12, the processing wind speed, the desorption temperature, the cooling temperature, the concentration of VOC exhausted from the dryer 2, and the like. The technical scope of the invention disclosed in the present application is not limited to the above specific numerical forms.

  Further, in the first embodiment, the adsorbent 30 is regenerated by the heat of the adsorption rotor heater 22 that sends the heated gas to the desorption zone 12Z2 of the adsorption rotor 12, but for example, for the regeneration of the adsorbent 30 A heating means prepared alone may be provided on the upstream side of the adsorbent 30.

In the first embodiment, the adsorbent 30 is provided in the bypass path 32 provided on the downstream side of the cooler 23 in order to quickly adsorb the VOC to the adsorbent 30, but the adsorbent 30 is regenerated. Any part of the first circulation path 11 and the second circulation path 21 may be used as long as it can supply a high-temperature gas. Hereinafter, other forms in which the position of the adsorbent 30 is changed will be described.

Second Embodiment
FIG. 6 is a diagram showing a VOC processing system according to the second embodiment. The VOC processing system 101 of the second embodiment is obtained by replacing the adsorbent 30 provided in the second circulation path 21 with the first circulation path 11 in the VOC processing system 1 of the first embodiment. Therefore, the same components as those in the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.

  That is, the first circulation path 111 of the main adsorption recovery unit 110 is provided with the main circulation fan 13 and the main circulation system regenerative heat exchanger 14. The first circulation path 111 is provided with a first damper 131D1 that blocks the path from the main circulation fan 13 to the main circulation system regenerative heat exchanger 14. A bypass path 132 that bypasses the first damper 131D1 is provided in the path from the main circulation fan 13 to the main circulation system regenerative heat exchanger 14. The bypass path 132 is provided with a second damper 131D2 that blocks the bypass path 132, and an adsorbent 130 that is located downstream of the second damper 131D2. An adsorbent heater 134 is provided in the middle of the path from the second damper 131D2 to the adsorbent 130. Further, the condensing and collecting unit 120 corresponding to the adsorbent 30 and the bypass path 32 provided in the condensing and collecting unit 20 of the first embodiment is omitted.

  In the VOC processing system 101 configured as described above, the following operation state is realized.

  For example, during operation of the dryer 2, in the VOC processing system 101, as shown in FIG. 6, the first damper 131D1 is opened and the second damper 131D2 is closed, and the cooler 23 and the adsorption rotor heater 22 are closed. Is in an operating state, and the main circulation fan 13, the condensation recovery system first circulation fan 24, and the condensation recovery system second circulation fan 25 are rotating. Thereby, in the 1st circulation path 111, the gas attracted | sucked from the inside of the dryer 2 passes the adsorption | suction zone 12Z1, and the circulating flow which returns to the dryer 2 again arises. The VOC vaporized in the dryer 2 is adsorbed by the adsorption zone 12Z1 of the adsorption rotor 12. In the second circulation path 121, the VOC desorbed from the adsorption rotor 12 by the gas heated by the adsorption rotor heater 22 is sent to the cooler 23, condensed, and dropped onto a drain pan provided in the cooler 23. It is recovered as a solution solvent. During the operation of the dryer 2, the VOC processing system 101 collects all the VOC vaporized in the dryer 2 without leaking outside the system by maintaining such an operating state.

  FIG. 7 is a state diagram of the VOC processing system 101 of the second embodiment when the dryer 2 is stopped. If no new VOC is generated in the dryer 2 due to the stop of the production facility, the VOC concentration of the gas circulating in the first circulation path 111 and the second circulation path 121 decreases. When the VOC concentration uniquely determined by the cooling temperature of the cooler 23 is reached, the VOC cannot be condensed and recovered in the cooler 23, and the VOC of the gas circulating in the first circulation path 111 and the second circulation path 121 is lost. The concentration becomes an equilibrium concentration.

Therefore, in the VOC processing system 101, after the dryer 2 is stopped and the VOC concentration of the gas circulating in the first circulation path 111 and the second circulation path 121 reaches the equilibrium concentration, as shown in FIG. The damper 131D1 is closed and the second damper 131D2 is opened. The adsorbent heater 134 remains stopped, and the main circulation fan 13 remains activated. The cooler 23, the adsorption rotor heater 22, the condensation recovery system first circulation fan 24, and the condensation recovery system second circulation fan 25 provided in the second circulation path 121 are stopped, and the rotation of the adsorption rotor 12 is also stopped. . Thereby, in the first circulation path 111, a circulating flow is generated in which the gas sucked from the dryer 2 passes through the adsorbent 130 and returns to the dryer 2 again. The VOC remaining in the first circulation path 11 is adsorbed by the adsorbent 130.

  While the dryer 2 is stopped, the VOC processing system 101 performs the operation as described above, thereby removing as much as possible the VOC remaining in the stopped dryer 2. Therefore, when a person enters the dryer 2, the concentration of VOC remaining in the dryer 2 is temporarily reduced to, for example, about 100 ppm, so that the inside of the dryer 2 is connected to the outside of the system. The amount of VOC remaining in the system is released as much as possible.

  The adsorbent 130 is regenerated as follows. FIG. 8 is a state diagram of the VOC processing system 101 of the second embodiment when the adsorbent 130 is regenerated. The adsorbent 130 is regenerated before the operation of the dryer 2 is started. That is, in the VOC processing system 101, as shown in FIG. 8, the adsorbent heater 134 is activated (if it is an electric heater) with the first damper 131D1 closed and the second damper 131D2 opened. Energized). Also, the condensation recovery system first circulation fan 24 and the condensation recovery system second circulation fan 25 are activated, and the cooler 23 and the adsorption rotor heater 22 are shifted to the operating state. Accordingly, in the first circulation path 111, the gas heated by the adsorbent heater 134 flows to the adsorbent 130, and the adsorbent 130 is heated. The VOC adsorbed on the adsorbent 130 is exposed to a high temperature and desorbed from the adsorbent 130. The gas that has passed through the adsorbent 130 is adsorbed to the adsorption zone 12Z1 of the adsorption rotor 12 in a state including VOC desorbed from the adsorbent 130. In the second circulation path 21, the VOC adsorbed by the adsorption rotor 12 is desorbed and condensed and recovered by the cooler 23, so that the VOC adsorbed by the adsorbent 130 becomes a solution solvent and recovered by the cooler 23. Is done. When the regeneration of the adsorbent 130 is completed, the adsorbent heater 134 is stopped (the power supply is stopped in the case of an electric heater), the first damper 131D1 is opened and the second damper 131D2 is closed, and the VOC processing system 101 is normally operated. Transition to the state.

  As with the VOC processing system 1 of the first embodiment, the VOC processing system 101 according to the second embodiment is temporarily absorbed by the adsorbent 130 at a VOC concentration that cannot be lowered by cooling and condensation. Can be reduced as much as possible.

<Third Embodiment>
FIG. 9 is a diagram showing a VOC processing system according to the third embodiment. The VOC processing system 201 of the third embodiment is obtained by replacing the adsorbent 130 provided in the bypass path 132 with the circulation path of the first circulation path 111 in the VOC processing system 1 of the second embodiment. That is, the adsorbent 230 is provided in the first circulation path 211 of the main adsorption recovery unit 210 along the path from the main circulation system regeneration heat exchanger 14 to the adsorption zone 12Z1 of the adsorption rotor 12. A cooler 223 is provided in the middle of the path from the adsorbent 230 to the adsorption zone 12Z1 of the adsorption rotor 12. Further, the bypass path 132, the first damper 131D1, and the second damper 131D2 provided in the VOC processing system 101 of the second embodiment are omitted. Since other components are the same as those of the VOC processing system 101 of the second embodiment, the same reference numerals are given and detailed descriptions thereof are omitted.

  In the VOC processing system 201 configured as described above, the following operation state is realized.

For example, during operation of the dryer 2, in the VOC processing system 201, as shown in FIG. 9, the main circulation fan 13 is rotating. As a result, in the first circulation path 211, a gas sucked from the dryer 2 passes through the adsorption zone 12Z1 and returns to the dryer 2 again, and the VOC vaporized in the dryer 2 is adsorbed by the adsorption rotor 12. Adsorbed to the zone 12Z1. The adsorbent 230 has a VOC when the gas flowing from the main circulation fan 13 is vented.
Is almost adsorbed to the saturated state, so that the VOC concentrations before and after the adsorbent 230 are equal. During the operation of the dryer 2, in the VOC processing system 201, the cooler 23 and the adsorption rotor heater 22 of the condensation recovery unit 220 are in operation, the cooler 223 is in operation, and the condensation recovery system first circulation The fan 24 and the condensing recovery system second circulation fan 25 are rotating. As a result, in the second circulation path 221, the VOC desorbed from the adsorption rotor 12 by the gas heated by the adsorption rotor heater 22 is sent to the cooler 23 to be condensed and dropped onto the drain pan provided in the cooler 23. And recovered as a solution solvent. During the operation of the dryer 2, the VOC processing system 201 collects all the VOC vaporized in the dryer 2 without leaking outside the system by maintaining such an operating state.

  FIG. 10 is a state diagram of the VOC processing system 201 of the third embodiment when the production facility shifts to the stop state and the generation of a new VOC stops. When no new VOC is generated in the dryer 2 due to the stop of the production equipment, the heat exchange in the main circulation system regenerative heat exchanger 14 is stopped. At this time, in order to increase the temperature of the gas that has flowed into the adsorbent 230 at about 40 ° C., the dryer 2 is kept operating. When heat exchange in the main circulation system regenerative heat exchanger 14 is stopped and the operation of the dryer 2 is continued, the temperature of the gas flowing into the adsorbent 230 rises to about 70 ° C. and is adsorbed by the adsorbent 230. VOCs are desorbed. The VOC desorbed from the adsorbent 230 is adsorbed by the adsorption zone 12Z1 of the adsorption rotor 12. Since the adsorption rotor 12 is regenerated by the second circulation path 221, the VOC desorbed from the adsorbent 230 is condensed in the cooler 23 of the second circulation path 221 and recovered as a solution solvent.

  FIG. 11 is a state diagram of the VOC processing system 201 of the third embodiment when the dryer 2 is stopped. When the above-described system configuration shown in FIG. 10 is continued and the VOC concentrations in the first circulation path 211 and the second circulation path 221 gradually decrease and the VOC no longer condenses in the cooler 23, the dryer 2 is stopped. When the dryer 2 is stopped, the temperature of the gas flowing into the adsorbent 230 decreases, and the VOC desorption from the adsorbent 230 stops.

  FIG. 12 is a state diagram of the VOC processing system 201 of the third embodiment when the circulation in the second circulation path 221 is stopped. After the temperature of the gas flowing into the adsorbent 230 decreases due to the stop of the dryer 2 and the desorption of the VOC in the adsorbent 230 stops, the cooler 23 and the adsorption rotor heater 22 are stopped, and the condensation recovery system The first circulation fan 24 and the condensation recovery system second circulation fan 25 are stopped. Further, the rotation of the suction rotor 12 is stopped. In the first circulation path 11, the circulation of the gas by the main circulation fan 13 is continued, and the temperature of the gas flowing into the adsorbent 230 is decreased as the dryer 2 is stopped. The VOC remaining in 211 is adsorbed by the adsorbent 230.

  In the VOC processing system 201, by performing the operation as described above, after the dryer 2 is stopped, VOC remaining in the stopped dryer 2 is removed as much as possible. Therefore, when a person enters the dryer 2, the concentration of VOC remaining in the dryer 2 is temporarily reduced to, for example, about 100 ppm, so that the dryer 2 can be connected to the outside of the system. The amount of VOC remaining outside the system is suppressed as much as possible.

The capacity of the adsorbent 230 in the VOC processing system 201 of the third embodiment is, for example, the VOC concentration in the first circulation path 211 when the VOC concentration is in an equilibrium state in the system configuration shown in FIG. The remaining amount of VOC is determined based on the relationship with the target value. For example, the adsorbent when the VOC concentration in the first circulation path 211 is 300 ppm and the temperature of the gas in the first circulation path 11 is 70 ° C. when the VOC concentration is in an equilibrium state in the system configuration shown in FIG. The total adsorption amount 230 is M0. In addition, when the target value of the remaining VOC concentration in the dryer 2 is 100 ppm and the temperature of the gas in the first circulation path 11 is 30 ° C., when the total amount of adsorption of the adsorbent 230 is M1, at least the following An amount of adsorbent that satisfies the relational expression is required.
(M1-M0)> (VOC amount in first circulation path 211 at 300 ppm−VOC amount in first circulation path 211 at 100 ppm)
In addition, the adsorbent 230 has an amount of adsorbent that allows for a decrease in the amount of VOC adsorbed due to the adsorption of the high-boiling organic matter because the adsorption capacity of the VOC decreases with the accumulation of the high-boiling organic matter. preferable.

  For example, the adsorbent 230 may be substituted for the purpose of removing high-boiling organic substances that degrade the performance of the adsorbent carried on the adsorption rotor 12. Examples of the adsorbent 230 that can remove high-boiling organic substances include activated carbon. Further, as shown in FIG. 12, the adsorbent 230 is not limited to the one provided in the middle of the path from the main circulation system regenerative heat exchanger 14 to the cooler 223. The adsorbent 230 for the purpose of removing the high-boiling organic substances only needs to be disposed at a position where the high-boiling organic substances can be prevented from flowing into the adsorption rotor 12, that is, upstream of the adsorption rotor 12. May be provided in the middle of a path from the suction rotor 12 to the suction rotor 12.

  By the way, the VOC processing system 201 of the third embodiment can be modified as follows, for example.

  FIG. 13 shows a first modification in which the VOC processing system 201 of the third embodiment is modified. When the adsorbent 230 is provided at the exhaust outlet portion of the dryer 2, for example, as shown in FIG. 13, a route connecting from the exhaust outlet of the dryer 2 where the adsorbent 230 is not provided to the first circulation path 211 is further provided. Thus, it is possible to form a path that substantially bypasses the adsorbent 230. In this case, for example, when it is not desired to adsorb the VOC to the adsorbent 230, the adsorbent 230 can be bypassed by the gas passing through the first circulation path 211.

  FIG. 14 is a second modified example in which the VOC processing system 201 of the third embodiment is modified. For example, as illustrated in FIG. 14, the adsorbent 230 provided in the VOC processing system 201 of the third embodiment is a circulation path that is different from the first circulation path 211, and passes through the dryer 2. It may be provided in the path 135. Since the third circulation path 135 communicates with the first circulation path 211 through the dryer 2, the third circulation path 135 is provided in the third circulation path 135 by the circulation flow generated by the adsorbent circulation fan 136 provided in the third circulation path 135. If the gas in the dryer 2 is vented to the adsorbent 230, the VOC concentration remaining in the dryer 2 is reduced after the dryer 2 is stopped, as in the VOC processing system 201 of the third embodiment. The amount released to the outside can be suppressed as much as possible.

<When handling multiple types of VOCs>
By the way, when handling a plurality of types of VOCs, it is preferable that the VOC processing systems 1, 101, and 201 according to the above embodiments and modifications are modified as follows. For example, when two types of VOC are handled, it is preferable that the VOC processing systems 1, 101, and 201 according to the above-described embodiments and modifications are modified as follows.

  FIG. 15 is a diagram showing a modification of the VOC processing system 1 according to the first embodiment. When handling a plurality of types of VOCs, a plurality of adsorbents 30 and 30 are provided in parallel in the bypass path 32 of the VOC processing system 1 according to the first embodiment, and the second adsorbents 30 and 30 are provided at the inlets. The dampers 31D2 and 31D2 may be switched according to the type of VOC. Similarly, the VOC processing system 101 according to the second embodiment and the VOC processing system 301 according to the third embodiment are provided with a plurality of adsorbents in parallel, and the adsorbent to be ventilated is switched according to the type of VOC to be handled. It may be.

<When bypassing the suction rotor>
By the way, when the residual VOC of the dryer is removed by the adsorbents 130 and 230 provided in the first circulation paths 111 and 211, the adsorption rotor 12 may be bypassed. FIG. 16 is a diagram showing a VOC processing system 101 according to the second embodiment provided with a path that bypasses the suction zone 12Z1 of the suction rotor 12. As shown in FIG. When the residual VOC of the dryer 2 is removed by the adsorbent 130 provided in the first circulation path 111, for example, as shown in FIG. 16, if the adsorption zone 12Z1 of the adsorption rotor 12 is bypassed, the adsorption zone 12Z1 of the adsorption rotor 12 Since the VOCs adsorbed on the adsorbent 130 are not desorbed and the adsorption of the residual VOC by the adsorbent 130 is not inhibited, the VOC concentration in the first circulation path 111 can be further suppressed as much as possible.

<Other variations>
The above embodiments and modifications can be combined with each other. For example, the VOC processing system 1 of the first embodiment and the VOC processing system 101 of the second embodiment may be combined, and an adsorbent may be provided in each of the first circulation path and the second circulation path.

1, 101, 201, 301 ··· VOC treatment system: 2 · Dryer: 10, 110, 210 ·· Main adsorption recovery unit: 11, 111, 211 · · First circulation path: 12 · · Adsorption rotor: 12Z1 ·・ Adsorption zone: 12Z2 ・ ・ Desorption zone: 12Z3 ・ ・ Cooling zone: 13 ・ ・ Main circulation fan: 14 ・ ・ Main circulation system regenerative heat exchanger: 20,120,220 ・ ・ Condensation recovery part: 21,121,221・ ・ Second circulation path: 22 ・ ・ Adsorption rotor heater: 23, 223 ・ ・ Cooler: 24 ・ ・ Condensation recovery system first circulation fan: 25 ・ ・ Condensation recovery system second circulation fan: 26 ・ ・ Condensation Recovery system regenerative heat exchanger: 30, 130, 230 ... Adsorbent: 31D1, 131D1 ... First damper: 31D2, 131D2 ... Second damper: 31D3 ... Third damper: 32, 132 ... : 33 · branch path: 134 · adsorbent for heater: 135 · third circulation path: the circulation fan 136 ... adsorbent

Claims (7)

A VOC processing system for recovering VOC vaporized in a facility that handles VOC,
A main adsorption / recovery unit that forms a first circulation path that is a gas circulation path from the equipment to the equipment again through the adsorption zone of the adsorption rotor;
A condensation recovery unit that forms a second circulation path that is a gas circulation path from the desorption zone of the adsorption rotor to the cooling zone of the adsorption rotor through a cooler and then returns to the desorption zone again through a heater;
It has an adsorbent provided in at least one of the first circulation path and the second circulation path or a path communicating with the circulation path, and condenses VOC in the cooler when the equipment is stopped. And a sub-adsorption recovery unit that adsorbs and recovers VOC in the gas in any one of the circulation paths with the adsorbent when there is no VOC processing system. The sub-adsorption recovery unit has the adsorbent in the second circulation path, bypasses the adsorbent in the second circulation path when the equipment is in an operating state, and stops the cooler by stopping the equipment. Venting the adsorbent when there is no VOC condensation in
The VOC processing system according to claim 1. The sub-adsorption recovery unit has the adsorbent in the first circulation path, bypasses the adsorbent in the first circulation path when the equipment is in an operating state, and stops the cooler by stopping the equipment. Venting the adsorbent when there is no VOC condensation in
The VOC processing system according to claim 1. The sub-adsorption recovery unit has the adsorbent in the first circulation path, and when the facility is stopped, the adsorbent is heated to start regeneration of the adsorbent, and after the regeneration of the adsorbent is started, the cooling is performed. When there is no VOC condensation in the vessel, the heating of the adsorbent is stopped and the adsorbent is vented.
The VOC processing system according to claim 1. The first circulation path includes a path that bypasses the adsorption zone of the adsorption rotor during adsorption in the adsorbent.
The VOC processing system according to claim 3 or 4. The equipment is equipped with a dryer,
The sub-adsorption recovery unit starts the regeneration of the adsorbent by heating the adsorbent with the exhaust of the dryer when the equipment is stopped, and when the condensation of VOC in the cooler disappears after the regeneration of the adsorbent is started. Stop the heating of the adsorbent by the dryer and vent the adsorbent.
The VOC processing system according to any one of claims 3 to 5.   A VOC processing method for recovering VOC vaporized in a facility that handles VOC,
  The adsorption recovery unit is provided separately from the adsorption rotor that adsorbs VOC in the circulation path passing through the equipment, and passes from the desorption zone of the adsorption rotor to the cooling zone of the adsorption rotor through the cooler. Using the adsorbent of the sub-adsorption recovery unit provided in the gas circulation path that returns to the desorption zone through again, recover the VOC before ventilating the equipment that is ventilated when stopped,
  VOC processing method.

Images