JP2015142884A - Volatile organic compound treatment apparatus and treatment method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To treat drain G generated by condensing steam F for desorption when desorbing without requiring a special step in an organic compound treatment apparatus where a volatile organic compound A after being adsorbed by an adsorbent in an adsorption tower 11 is desorbed by supplying the steam F for desorption and incinerated by a combustion furnace 31.SOLUTION: Drain G is introduced into a steam generation recycling route 54 where steam F for desorption can be recycled to be heated to reach a sufficient temperature via a heat exchanger 32 generating the steam F for desorption.

Description

  The present invention relates to an apparatus for treating a volatile organic compound from a gas before discharging the gas containing the volatile organic compound.

  Exhaust gas generated from factories may contain volatile organic compounds that cause problems if discharged into the atmosphere as they are. In this case, before exhaust gas is discharged into the atmosphere, the contained volatile organic compounds must be treated. As a method for this, a volatile organic compound contained in exhaust gas is adsorbed on an adsorbent in an adsorption tower containing an adsorbent such as activated carbon, and the concentration in the gas is reduced and discharged to the atmosphere. Thereafter, an adsorption / desorption method is generally used in which water vapor is introduced into the adsorption tower to desorb the volatile organic compound from the adsorbent so that the adsorption tower can be reused and the volatile organic compound is treated. Further, the desorbed volatile organic compound can be burned, and desorption water vapor can be generated using the combustion heat.

  However, while the adsorbent in the adsorption tower is at a low temperature, the water vapor introduced into the adsorption tower is condensed to generate drain. Since this drain contains desorbed volatile organic compounds and other impurities, it must be separately discharged to discharge it outside the factory.

  Patent Document 1 describes that a boiler that generates desorption steam to be introduced into a fluorocarbon recovery device equipped with an adsorption tank is provided, and the drain of the desorption steam is reused as make-up water for the boiler (claim). Item 1, FIG. 1). The fluorocarbon contained in the drain is evaporated together with water by the heat of the boiler, transferred to the adsorption tower, once adsorbed, and then processed in a normal desorption process. Therefore, it is not necessary to separately perform a drain discharge process.

  Patent Document 2 describes a method of recovering dewatered steam drain, making the drain mist, spraying it into an adsorption tower, and adsorbing it again to the adsorbent. In mist formation, it is described that a part of desorption water vapor and drain are combined and introduced into an ejector. Since the volatile organic compound contained in the drain is adsorbed by the adsorbent and then desorbed and consumed as fuel in the combustion furnace, there is no need to perform a separate drain discharge process.

Japanese Utility Model Publication No. 3-11026 JP 2009-233617 A

  However, in the method described in Patent Document 1, since drain is supplied as boiler make-up water, impurities contained in the drain adhere to the heat transfer surface of the boiler as a scale, and are periodically removed to remove this. Maintenance is required.

  Further, in the method described in Patent Document 2, an ejector for misting the drain is required, so that the process is long and the entire apparatus is complicated. Furthermore, in order to make the drain mist, the water vapor originally used for desorption must be diverted, and since the water vapor is not used for desorption, the thermal energy efficiency of the entire apparatus has been reduced.

  SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to eliminate the need for treatment of the desorption water vapor drain without requiring a special process.

  The present invention solves the above-mentioned problem by introducing drain into a water vapor generation circulation path through which the desorption water vapor can be circulated until it is heated to a sufficient temperature via a heat exchanger.

  In the steam generation circulation path, the steam before being sent to the adsorption tower is circulated on the air, and the heat exchanger is heated while supplying water in addition to the steam returned through the path. Then, sufficiently high temperature desorption water vapor is generated. When drain is introduced into this water vapor generation and circulation path, the air flows by the circulating air and water vapor to form fine droplets that reach the heat exchanger and receive heat to become water vapor. Since this process can be performed in parallel with the adsorption and desorption processes in the adsorption tower or as preparations for those processes, it is not necessary to put extra steps in the use and regeneration cycle of the adsorption tower. Impurities including volatile organic compounds in the drain are air-flowed to the adsorption tower together with the generated desorption water vapor, burned as energy in the combustion furnace, and then discharged out of the system. As a result, it is possible to process the drain without having to separately expand the facility for the discharge process.

  Furthermore, even after supplying drain to the steam generation and circulation path, it can be circulated in the path until it reaches a predetermined temperature, so the temperature of the desorption steam supplied to the adsorption tower decreases and the desorption efficiency decreases. There is no such thing as to do. And instead of supplying the drain directly to the heat exchanger, it is introduced into the steam generation and circulation path and transported by airflow, so that not only water but also impurities are heated while being transported by airflow, so the heat transfer of the heat exchanger It becomes difficult to scale in terms of surface and increase in the number of maintenance can be suppressed.

  When the drain is sent to the steam generation circulation path, a drain storage tank is provided so that the drain discharged from the adsorption tower can be stored there once, and the necessary amount can be sent to the steam generation circulation path. This is preferable because the drain can be steamed at an optimal timing according to the temperature of the combustion furnace. This is just a tank and can be installed without complicating the structure of the device.

  According to the present invention, it is possible to treat the drainage of the desorption water vapor without adding a process for complicating the apparatus and without causing additional maintenance work.

Embodiment of the first organic compound processing apparatus according to the present invention The flowchart which shows the example of the operation method of the 1st organic compound processing apparatus concerning this invention Example diagram of the second organic compound processing apparatus according to the present invention

  Embodiments of the present invention will be described below. The present invention relates to a volatile organic compound processing apparatus that reduces the concentration of a volatile organic compound-containing gas so that the gas can be discharged into the atmosphere, collects the volatile organic compound, and uses it as a fuel. FIG. 1 shows an example of an overall image of a volatile organic compound processing apparatus according to the present invention.

  The volatile organic compound to be treated in the present invention is an organic compound that can be converted into a gas when heated at normal pressure, and particularly, a liquid that is liquid at room temperature is easily adsorbed. Examples thereof include hydrocarbon solvents such as alcohols having about 1 to 8 carbon atoms such as methanol, ethanol and isopropyl alcohol, and aromatic organic compounds such as toluene and benzene.

  The volatile organic compound processing apparatus for carrying out the present invention includes one or a plurality of adsorption towers 11, a combustion furnace 31, a heat exchanger 32, and piping connecting them. Here, a configuration having two adsorption towers 11 (11a, 11b) is shown as an example.

  Each adsorption tower 11 has a rectangular shape, and the inside is partitioned by a single porous plate 20 (20a, 20b) provided in the vicinity of the lower end. On the perforated plate 20, an adsorption layer 12 (12a, 12b) filled with an adsorbent that adsorbs a volatile organic compound and can be desorbed by heating is provided. Examples of the adsorbent include activated carbon.

  The inlet 17 (17a, 17b) of the volatile organic compound-containing gas A is provided on the upper end side of the adsorption layer 11 of the adsorption tower 11, and the volatile organic compound is adsorbed on the lower end side of the adsorption layer 12. Are provided with discharge ports 18 (18a, 18b) for the treated gas B that are adsorbed by the gas and have a reduced concentration. The discharge port 18 discharges into the atmosphere.

  Moreover, the supply ports 24 and 25 of the desorption water vapor | steam F are provided in the side surface and lower end of the part in which the adsorption layer 12 of the adsorption tower 11 was provided. The side supply ports 24 a and 24 b are located above the vertical center of the adsorption layer 12 and below the upper end of the adsorption layer 12, and the lower supply ports 25 a and 25 b are below the lower end of the adsorption layer 12. positioned. In addition, supply ports may be provided in more stages. Further, outlets 26 a and 26 b for extracting the vapor organic compound accompanying gas K from which the organic compound has been desorbed are provided on the upper end side of the adsorption layer 12. The steam organic compound entrained gas K is transported through the entrained gas delivery path 21 leading from the feed outlet 26 to the combustion furnace 31.

  Further, drain outlets 27 a and 27 b for the generated drain are provided near the bottom of the adsorption tower 11 below the lower end of the adsorption layer 12 of the adsorption tower 11. Further, a drain pipe 28 for feeding the drain that has escaped from the outlets 27 a and 27 b to the drain storage device 29 is provided.

  The combustion furnace 31 generates heat for generating the desorption water vapor F, and is accompanied by the water vapor organic compound sent from the fuel supply port 42 for supplying the fuel D and the outlet 26 of the adsorption tower 11. It has a contained gas supply port 43 for supplying the gas K, a burner (not shown), a chimney 60, and a combustion furnace temperature sensor 44 for measuring the internal temperature. The heat generated in the combustion furnace 31 is supplied to the heat exchanger 32 through the high temperature gas supply passage 45 as the generated high temperature gas.

  The heat exchanger 32 includes a water supply port 58 that supplies water E that is a source of water vapor, and supplies desorption water vapor F obtained by heating the water E to the supply ports 24 and 25 of the adsorption tower 11. It has a desorption water vapor supply path 52 and a water vapor temperature sensor 56 for measuring the internal temperature. The water supply port 58 has a function of spraying water E into the heat exchanger 32.

  The desorption water vapor supply path 52 through which the water vapor F generated in the heat exchanger 32 is extracted branches on the way (circulation path branch point 53), and one of the water vapor generation paths returns to the heat exchanger 32 to the water vapor generation circulation path 54 The other is divided into a water vapor supply path 55 that leads to the adsorption tower 11. A blower 61 that blows up toward the heat exchanger 32 is provided in the middle of the water vapor generation circulation path 54 to generate a circulating air flow. A drain supply pipe 62 that supplies the drain stored in the drain storage device 29 is connected to a portion of the steam generation circulation path 54 where the air flow generated from the blower 61 passes (the air flow passage point 63). The drain G introduced into the air flow in the water vapor generation circulation path 54 does not stay at the air flow passage point 63 to be introduced, but exchanges heat with fine soot or circulating water vapor, and is sequentially conveyed as water vapor. . For this reason, it is possible to continue supplying the drain G while preventing the impurities in the drain G from being scaled from the airflow passage point 63 to the blower 61.

  The water vapor supply path 55 leading to the adsorption tower 11 is also branched on the way (atmosphere opening path branching point 57), one leading to the opening 59 to the atmosphere, and the other to the supply openings 24 and 25 of the adsorption tower 11. It is connected. The water vapor and the organic component evaporated from the drain G reach the combustion furnace 31 from the outlet 26 through the accompanying gas supply passage 21 after the water vapor contributes to desorption in the adsorption tower 11, and the organic component is consumed as fuel. The

An example of a procedure for processing a volatile organic compound by the apparatus according to the present invention will be described.
In the volatile organic compound processing apparatus according to the present invention, first, the volatile organic compound contained in the volatile organic compound-containing gas A introduced into the adsorption tower 11 is adsorbed by the adsorbent of the adsorption layer 12. The treated gas B that has passed through the adsorption layer 12 exits from the outlet 18 and is released into the atmosphere. This adsorption work is performed until a certain period of time elapses or until the adsorption capacity becomes below a certain level. In order to stop the adsorption by detecting a decrease in the adsorption capacity, a volatile organic compound detection device (not shown) is provided at the discharge port 18 where the concentration of the volatile organic compound contained in the gas B after the treatment is determined. A control circuit is provided that, when measured and exceeds a predetermined value, interprets that the adsorption capacity of the adsorption layer 12 has reached its limit and issues a command to close the valve of the inlet 17.

  On the other hand, preparation for desorption is proceeded before the adsorption is completed. Since the desorption water vapor F cannot be supplied immediately, if heating is started after the completion of adsorption, a time lag occurs before the desorption begins, and the originally necessary adsorption process is stopped. In addition, when there are two or more adsorption towers 11, the adsorption process can be performed on the other side even if the adsorption process is stopped on one side, but in that case, the desorption water vapor F is always prepared. At this time, the desorption water vapor F can be kept at a high temperature by circulating the water vapor generation circulation path 54.

  This desorption process will be described with reference to the flow of FIG. First, combustion of the fuel D is started in the combustion furnace 31, and the air in the water vapor generation circulation path 54 is circulated by the blower 61 provided in the path (S11). When the air temperature at this time is detected by the water vapor temperature sensor 56 and it is confirmed that the temperature is equal to or higher than the set temperature T1 at which water vapor can be generated (S12), the valve of the water supply port 58 of water E is opened and water E is sprayed. Then, water vapor is generated in the heat exchanger 32 (S13). In the heat exchanger 32, the temperature of the water vapor generated by the water vapor temperature sensor 56 is detected, and the opening 59 is used until the desorption water vapor F reaches a temperature T2 suitable for desorption (S14) or until the adsorption is completed. The valve is opened and released into the atmosphere (S15). This is because desorption is an endothermic reaction, and desorption does not proceed quickly unless the steam is sufficiently hot. Therefore, the desorption water vapor F here is superheated water vapor. Further, a part of the desorption steam F branched at the circulation path branch point 53 is circulated to the heat exchanger 32 through the steam generation circulation path 54.

  When the adsorption in the adsorption tower 11 is completed and the desorption water vapor F becomes equal to or higher than the predetermined temperature T2 (S14), the valve to the open port 59 is closed by the open port control circuit, and the side near the outlet 26 is closed. The valve of the desorption water vapor F to the supply port 24 is opened (S16). The desorption water vapor F supplied to the supply port 24 comes into contact with the adsorbent of the adsorption layer 12 and heats the adsorbent by holding the heat, and a part of the water vapor is condensed to become water. The water takes a part of volatile organic compounds and other impurities that are adsorbed in contact with the adsorbent and becomes drain. The collected drain falls in the adsorption tower 11 by its own weight, and starts to be discharged as drain G from the outlet 27 at the bottom of the tower (S17). After the adsorbent in the upper layer portion of the adsorption layer 12 is sufficiently heated, the desorption reaction of the volatile organic compound proceeds by contacting with the desorption water vapor F. The water vapor that has not been condensed and the desorbed volatile organic compound are combined with the vapor organic compound accompanying gas K and delivered from the outlet 26 (S18).

  When the steam organic compound entrained gas K reaches the combustion furnace 31 (S19), the total amount of combustibles supplied to the combustion furnace 31 increases, so that the temperature in the combustion furnace 31 rises. This temperature rise is detected by the combustion furnace temperature sensor 44. When a specified temperature T3 that is defined as exceeding the error in temperature rise during combustion of only the fuel D is specified in advance, and the temperature detected by the combustion furnace temperature sensor 44 is equal to or higher than T3 (S20), the water vapor organic compound Considering that the combustibles have increased due to the arrival of the accompanying gas K, the valve of the fuel D supplied to the fuel supply port 42 is throttled to save the fuel D (S21).

  However, since the organic compound contained in the vapor organic compound accompanying gas K decreases as the volatile organic compound adsorbed in the vicinity of the supply port 24 is gradually desorbed, the valve of the supply port 25 is opened at a timing. Thus, the amount of the volatile organic compound supplied to the combustion furnace 31 is prevented from excessively decreasing. In the case where the supply ports are provided in multiple stages between 24 and 25, the supply ports that are closest to the supply port 26 are sequentially opened and timed. This opening timing may be determined by the elapsed time since the supply port 24 on the side close to the outlet 26 is opened, or a temperature drop that is defined in advance by the combustion furnace temperature sensor 44 of the combustion furnace 31. In other words, when it is detected that the amount of combustible material to be burned has decreased, the battery may be opened sequentially. When detecting a temperature drop, if a control circuit that preliminarily defines a furnace temperature T4 that should be dealt with by reducing combustibles detects a temperature drop of the combustion furnace temperature sensor 44 (S22), the supply port is not connected. Among the opened valves, the valve on the outlet 26 side (upper end side) is opened (S23). One valve is opened, and once the furnace temperature rises, the furnace temperature is monitored again, and when the temperature drop is detected, the next valve is opened. If there are supply ports in more stages than in FIG. 1, this continues until all the supply ports are opened. When the next valve is opened, the supply port valve that has been opened is closed.

  When the time t1 at which the desorption in the adsorption layer 12 sufficiently proceeds after the supply ports 24, 25, etc. are all opened (S26), all the supply ports 24, 25, etc. are closed to complete the desorption (S27). .

  Thus, the desorption of the adsorption tower 11 is completed, and the adsorption layer 12 can be again adsorbed. Therefore, the inlet 17 of the volatile organic compound-containing gas A is opened to start the adsorption, and the adsorption is performed for a certain time After that, desorption is performed in the same procedure as described above.

  On the other hand, the drain G discharged in S17 is once stored in the drain storage device 29 and then supplied to the water vapor generation circulation path 54 (S17). By temporarily storing in the drain storage device 29, the drain storage device 29 functions as a water seal device, and the backflow of water vapor from the water vapor generation circulation path 54 to the adsorption tower 11 can be prevented. The supplied drain G becomes fine soot and is heated by the heat exchanger 32 to evaporate, or exchanges heat with the circulating desorption water vapor F to form water vapor, which is sequentially conveyed. Thereafter, when the desorption water vapor F is sufficiently heated (S14, S15), the desorption water vapor F is supplied to the adsorption tower 11 at a necessary timing (S16). The adsorption tower 11 may be the adsorption tower 11 that has been previously desorbed, and when the two adsorption towers 11 are provided, it becomes the second adsorption tower 11.

  The form of the organic compound processing apparatus for carrying out the present invention is not limited to the form shown in FIG. 1, and includes an adsorption tower 11, a combustion furnace 31, and a heat exchanger 32. If it is a processing apparatus which reproduces | regenerates an agent, it can implement as an apparatus concerning this invention by providing the piping which supplies the water vapor | steam production | generation circulation path 54 which circulates the drain discharged | emitted from the adsorption tower 11 to the heat exchanger 32 similarly.

  As a form other than the above, for example, the high-temperature gas generated in the combustion furnace 31 or the exhaust gas after the high-temperature gas is supplied to the heat exchanger 32 and heat-exchanged is partially branched and introduced into the water vapor generation circulation path 54. Thus, the conveyance and evaporation of the drain G and the heating of the water vapor may be promoted. This embodiment is shown in the example of FIG. A high-temperature gas supply path 45 and an exhaust gas supply path 46 are branched to provide a high-temperature gas branch supply path 47 and an exhaust gas branch supply path 48 that are supplied to the water vapor generation circulation path 54.

  In the embodiment when carrying out the present invention, the vertical direction of the positions of the supply ports 24 and 25, the supply port 26, the introduction port 17 and the discharge port 18 provided in the adsorption tower 11 may be reversed. Further, in principle, the present invention can also be implemented in a form in which the adsorption tower 11 is oriented in the horizontal direction and rotated 90 degrees from the form shown in the figure. Whatever direction the adsorption tower 11 faces, the inlet 17 for introducing the volatile organic compound-containing gas A to the adsorption tower 11 and the outlet 26 for delivering the steam organic compound-containing gas K are adsorbed. There is no change in the form in which the exhaust port 18 for exhausting the treated gas B on one end side (one end side) of the tower 11 is located on the other end side (other end side).

11, 11a, 11b Adsorption tower 12 Adsorption layer 17 Inlet (volatile organic compound-containing gas)
18 Outlet (Gas after treatment)
20 perforated plate 21 entrained gas delivery path 24, 24a, 24b, 25, 25a, 25b supply port 26, 26a, 26b outlet (water vapor organic compound accompanying gas)
27, 27a, 27b Drain outlet 28 Drain piping 29 Drain storage device 31 Combustion furnace 32 Heat exchanger 42 Fuel supply port 43 Contained gas supply port 44 Combustion furnace temperature sensor 45 High temperature gas supply path 46 Exhaust gas supply path 47 High temperature gas branch supply path 48 Exhaust gas branch supply path 52 Desorption water vapor supply path 53 Circulation path branch point 54 Steam generation circulation path 55 Water vapor supply path 56 Water vapor temperature sensor 57 Atmospheric open path branch point 58 Water supply port 59 Open port 60 Chimney 61 Blower 62 Drain supply pipe 63 Airflow passage point A Gas containing volatile organic compound B Gas after treatment D Fuel E Water F Desorption water vapor G Drain K Water vapor organic compound gas

Claims (4)

An adsorption tower having an adsorption layer filled with an adsorbent that adsorbs a volatile organic compound, and can be supplied with desorption water vapor that desorbs the volatile organic compound from the adsorption layer;
A combustion furnace capable of using the desorbed volatile organic compound as a part of the fuel;
A heat exchanger that exchanges heat between the high-temperature gas generated in the combustion furnace and water to generate the desorption water vapor, and
A pipe that can be introduced into the water vapor generation circulation path for circulating the drain generated by condensation of the desorption water vapor in the adsorption tower to the heat exchanger in order to reheat the desorption water vapor generated in the heat exchanger. An organic compound processing apparatus.   The organic compound processing apparatus according to claim 1, further comprising a drain storage device capable of temporarily storing drain generated in the adsorption tower before introducing the drain into the water vapor generation circulation path. Using the organic compound processing apparatus according to claim 1 or 2,
In the organic compound treatment method in which after the volatile organic compound is adsorbed on the adsorbent, the desorption water vapor is introduced, the volatile organic compound is desorbed from the adsorbent, and delivered to the combustion furnace for combustion. ,
The drain containing the volatile organic compound generated in the adsorption tower at the time of the desorption is introduced into the water vapor generation circulation path circulating for heating the desorption water vapor, and the volatilization contained in the drain is performed. An organic compound treatment method in which an organic compound is entrained in the desorption water vapor and burned in the combustion furnace.   The organic compound processing method according to claim 3, wherein the high-temperature gas, the exhaust gas after heat-exchanging the high-temperature gas, or both are introduced into the water vapor generation circulation path.

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