JP2008279379A - Voc cooling/recovery device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a VOC cooling/recovery device which can inhibit the freezing of an outlet blocking valve at an outlet for exhausting the gas clear of the VOC. <P>SOLUTION: This VOC cooling/recovery device is provided with a two-element freezer 32 with a high-temperature side circuit 33 and a low-temperature side circuit 34 connected together thermally through a cascade condenser 36; a precooler 60 with an evaporator 46 of the high-temperature side circuit 33; a main cooler 62 with an evaporator 56 of the low-temperature side circuit 34; a gas exhaust pipe 71 which exhausts a residual gas out of the main cooler 62 after recovering the VOC by it, from the latter; an outlet blocking valve 70 which blocks an exhaust outlet 110 of the gas exhaust pipe 71; and an antifreezing means 83 for preventing the outlet blocking valve 70 from being frozen. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a cooling and recovery device for liquefying and recovering this VOC gas when a volatile organic compound (VOC) is a gas.

VOC is an organic compound that is volatile and is gaseous in the atmosphere, and includes various substances such as toluene, xylene, ethyl acetate, and decane.
VOC gas containing gaseous VOC is discharged in various facilities such as paint-related facilities, adhesive drying facilities, printing-related facilities, chemical product manufacturing facilities, and industrial cleaning facilities. However, VOC is a cause of suspended particulate matter (SPM) and photochemical oxidant, and in recent years, its emission is required to be suppressed from the viewpoint of preventing air pollution.

Therefore, in order to recover the discharged VOC gas, a gas recovery device for cooling the VOC gas to condense and liquefy it is conventionally known (for example, see Patent Document 1 and Patent Document 2).
Hereinafter, based on FIG. 3, the structure of the gas collection | recovery apparatus as shown by patent document 1 and patent document 2 is demonstrated.
The gas recovery device 10 includes a cooling device 11 configured as an airtight container and a refrigerator 12. The gas to be collected flows through the flow pipe 13 and is introduced into the cooling device 11. Two coils of a first coil 14 and a second coil 15 are arranged in the cooling device 11.

The refrigerator 12 is provided with a compressor 16 and a condenser 18 in a refrigerant flow pipe 17 through which the refrigerant flows. In addition, an expander 19 is provided between the condenser 18 and the first coil 14, and the refrigerant flow pipe 17 extending from the condenser 18 branches off before the expander 19 and branches off. 21 is connected, and the branch pipe 21 is provided with an expander 20 and a second coil 15.
The branch pipe 21 on the downstream side of the second coil 15 is connected to the suction portion of the ejector 22, and the second coil 15 becomes negative pressure by the ejector 22, and becomes lower temperature than the first coil 14.

Japanese Utility Model Publication No. 6-29603 (FIG. 2 etc.) JP-A-7-260345 (FIG. 2 etc.)

The conventional gas recovery apparatus as described above is provided with a gas exhaust pipe for exhausting the gas that has been cooled to a very low temperature and from which VOC has been removed, and this gas exhaust pipe is used to control the discharge of gas. An outlet closing valve is provided.
However, since the exhaust gas is at a very low temperature, the outlet closing valve is frozen, and there is a problem that the function as the valve may not be exhibited.

  Accordingly, the present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide a VOC recovery device that can prevent the outlet closing valve from being frozen at the outlet for discharging the gas after the VOC is removed. There is.

That is, according to the VOC cooling and recovery apparatus according to the present invention, the VOC cooling and recovery apparatus recovers by liquefying and recovering VOC from VOC gas containing VOC that is in the form of gas, and is a high temperature cooled by the first refrigerant. A binary refrigerator in which a side circuit and a low temperature side circuit cooled by a second refrigerant are thermally connected via a cascade condenser, and an evaporator of the high temperature side circuit disposed in a first sealed container A precooler for precooling the VOC gas to be introduced, a main cooler for cooling the precooled VOC gas, wherein the evaporator of the low-temperature circuit is disposed in a second sealed container, A gas introduction pipe for introducing VOC gas into the precooler, a gas distribution pipe for introducing VOC gas preliminarily cooled and discharged in the precooler into the main cooler, and the main cooler A gas exhaust pipe for discharging the remaining gas from which the VOC has been recovered by the main exhaust from the main cooler, an outlet closing valve for closing the exhaust outlet of the gas exhaust pipe, and a lower part of the precooler and the main cooler. A drain port, connected to each drain port of the precooler and the main cooler, connected to the drain recovery pipe for circulating the VOC liquefied in the precooler and the main cooler, and connected to the drain recovery pipe, And a freezing prevention means for preventing the outlet closing valve from freezing.
By adopting this configuration, the gas discharge pipe can be opened and closed without the outlet closing valve being frozen by the freeze prevention means.

The anti-freezing means is provided so that the gas introduction pipe and the gas discharge pipe can be arranged close to each other in a main body having a heat insulating structure, and the gas to be discharged according to the temperature of the VOC gas flowing through the gas introduction pipe. It may be characterized by being a heat exchanger for freeze prevention that raises the temperature and prevents the outlet closing valve from freezing.
According to this configuration, the temperature of the exhaust gas is increased by the VOC gas before introduction, which has a relatively high temperature, and the outlet closing valve is prevented from freezing. For this reason, since it is not necessary to heat with an electric heater or the like, the running cost can be reduced, and the VOC gas can be cooled before being introduced, so that the cooling efficiency of the VOC gas can be increased.

  According to the VOC cooling and recovery apparatus of the present invention, it is possible to prevent the outlet closing valve from freezing and becoming inoperable.

DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, preferred embodiments of the invention will be described in detail with reference to the accompanying drawings.
FIG. 1 shows the overall configuration of this embodiment.
The VOC cooling / recovery device 30 of the present embodiment uses a binary refrigerator 32, and after the VOC gas is precooled by the high temperature side circuit 33 of the binary refrigerator 32, it is further cooled by the low temperature side circuit 34. The VOC can be efficiently liquefied.

First, the configuration of the binary refrigerator 32 will be described.
The binary refrigerator 32 is configured by thermally connecting a high temperature side circuit 33 and a low temperature side circuit 34 by a cascade capacitor 36.
The high temperature side circuit 33 includes a high temperature side compressor (compressor) 38, a high temperature side condenser 40, a high temperature side pressure reducing valve 43, and a first high temperature side evaporator 44 constituting a cascade condenser. These devices are connected in series by a refrigerant flow pipe 45 through which the high-temperature side refrigerant flows.

A refrigerant dryer 50 is provided on the downstream side of the high-temperature side condenser 40 in the high-temperature side circuit 33 to remove moisture in the refrigerant.
A control valve 37 for adjusting the flow rate of the refrigerant flowing through the refrigerant flow pipe 45 is provided between the high temperature side pressure reducing valve 43 and the first high temperature side evaporator 44.

Further, the high temperature side circuit 33 is provided with a second high temperature side evaporator 46 in parallel with the first high temperature side evaporator 44. The first high temperature side evaporator 44 and the second high temperature side evaporator 46 use the high temperature side compressor 38 and the high temperature side condenser 40 in common, and the second high temperature side evaporator 46 is a refrigerant. It is provided in the branch pipe 49 which branches between the site | part connected to the high temperature side compressor 38 of the flow pipe 45, and the site | part connected to the high temperature side condenser 40 of the refrigerant | coolant flow pipe 45.
The branch pipe 49 is provided with a second high temperature side pressure reducing valve 43. A control valve 39 for adjusting the flow rate of the refrigerant flowing through the branch pipe 49 is provided between the high temperature side pressure reducing valve 43 of the branch pipe 49 and the second high temperature side evaporator 46.

The high-temperature side condenser 40 in the present embodiment is provided with a fan 35 so that the refrigerant is cooled and condensed by the outside air introduced by the fan.
In the high temperature side circuit 33 having such a configuration, a refrigerant having excellent characteristics at high temperatures is used.

Next, the configuration of the low temperature side circuit 34 will be described.
The low temperature side circuit 34 includes a low temperature side compressor (compressor) 51, a low temperature side condenser 52 constituting a cascade condenser 36, a low temperature side pressure reducing valve 54, and a low temperature side evaporator 56. The devices are connected by a refrigerant flow pipe 55 through which the low-temperature side refrigerant flows. Further, a refrigerant dryer 57 is provided on the downstream side of the low-temperature side condenser 52 in the low-temperature side circuit 34 so as to remove moisture in the refrigerant.
An oil separator 59 is provided between the low temperature side compressor 51 and the low temperature side condenser 52. The oil separator 59 separates the oil and returns it to the low temperature side compressor 51 so that the oil generated from the low temperature side compressor 51 does not flow into other devices.

A temperature sensor 53 for detecting the temperature in the cascade capacitor 36 is provided in the cascade capacitor 36.
A controller 58 is connected to the temperature sensor 53. The control unit 58 is provided so as to be able to control the operations of the high temperature side compressor 38 and the low temperature side compressor 51 so that the detected temperature in the cascade capacitor 36 becomes a predetermined temperature set in advance. Control. Specifically, the temperature in the cascade capacitor 36 is controlled to be about −10 ° C.

Next, the distribution route of the VOC gas will be described.
First, the 1st high temperature side evaporator 46 of the high temperature side circuit 33 comprises the precooler 60 which is arrange | positioned in an airtight container and precools VOC gas. By pre-cooling the VOC gas, the moisture contained in the VOC gas can be attached as frost to remove the moisture.
The low temperature side evaporator 56 of the low temperature side circuit 34 is also arranged in the sealed container, and constitutes a main cooler 62 that liquefies VOC.

  The VOC to be recovered is provided so as to flow through the gas introduction pipe 64 connected to a VOC generation source (not shown) and be introduced into the VOC cooling and recovery apparatus 30. The gas introduction pipe 64 is provided with a blower (not shown) and a control valve 68, and a VOC gas is sent into the gas introduction pipe 64 by the blower 66. The VOC gas sent into the gas introduction pipe 64 is introduced into the precooler 60 and precooled.

A gas circulation pipe 67 is disposed between the precooler 60 and the main cooler 62, and the VOC gas precooled by the precooler 60 is introduced into the main cooler 62 through the gas circulation pipe 67.
The main cooler 62 is provided with a gas discharge pipe 71 for discharging the remaining gas from which the VOC has been separated. In this way, the VOC gas passes through both the precooler 60 and the main cooler 62 and is cooled in two stages, after which the VOC is removed and exhausted from the gas exhaust pipe 71. An exhaust outlet 110 is provided at the end of the gas exhaust pipe 71.
Further, the gas discharge pipe 71 is provided with an outlet closing valve 70 for closing the exhaust outlet 110.

A heat insulating member 91 is provided around the gas circulation pipe 67 so as to maintain a low temperature state of the VOC gas flowing while blocking the ambient temperature. For example, the heat insulating member 91 may be configured by winding a heat insulating material around the gas circulation pipe 67.
In the present embodiment, a heat insulating member 91 is also provided in a part of the gas introduction pipe 64 and a part of the gas discharge pipe 71 to further improve the cooling efficiency.

Further, since the gas discharged from the gas discharge pipe 71 is cooled to a very low temperature by the main cooler 62, the outlet closing valve 70 may be frozen. Therefore, anti-freezing means for preventing the outlet closing valve 70 from freezing is provided.
In the present embodiment, the antifreezing means includes a gas exhaust pipe 71 and a gas introduction pipe 64 arranged between the gas flowing through the gas exhaust pipe 71 and the VOC gas flowing through the gas introduction pipe 64. The anti-freezing heat exchanger 83 for exchanging heat in this case corresponds.

  The anti-freezing heat exchanger 83 is provided so that the gas discharge pipe 71 and the gas introduction pipe 64 are disposed in the vicinity of the main body 87 of the heat insulating structure. Further, the heat insulating member 91 provided in the gas discharge pipe 71 is not arranged in the anti-freezing heat exchanger 83 so that heat exchange is possible between the gas discharge pipe 71 and the gas introduction pipe 64. .

Drain ports 72 and 74 are provided at the lower portions of the precooler 60 and the main cooler 62, respectively.
The drain port 72 is connected to a drain recovery pipe 76 provided with a drain control valve (not shown), and the drain recovery pipe 76 is connected to a recovery tank 78. The drain port 74 is connected to a drain recovery pipe 77 provided with a drain control valve 92, and the drain recovery pipe 77 is connected to a recovery tank 78.
Further, the control unit 58 can control the opening and closing of both drain control valves (not shown) by outputting a control signal. At the time of VOC recovery, both drain control valves are controlled to be open, and VOC is always recovered as drain.

  As described above, when the VOC is condensed and liquefied by the precooler 60 and the main cooler 62, the liquefied VOC is stored in the recovery tank 78 via the drain recovery pipe 76 and the drain recovery pipe 77. The recovery tank 78 is provided with an exhaust pipe 79 that exhausts the air in the recovery tank 78, and an exhaust filter 80 is attached to the exhaust pipe 79. The exhaust filter 80 uses a catalyst or the like that decomposes VOC.

It is preferable to introduce defrosting air into the gas introduction pipe 64 at the time of defrosting. As the defrost air in the present embodiment, normal outside air is employed.
That is, a branch pipe 82 for introducing outside air is provided on the upstream side of the precooler 60 in the gas introduction pipe 64, a control valve 84 for opening and closing the branch pipe 82, and a blower for feeding outside air to the branch pipe 82. 86 is provided.

Hereinafter, the operation of the VOC cooling recovery apparatus 30 in the present embodiment will be described.
First, before the operation of the VOC cooling and recovery apparatus 30, the control valve 68 of the gas introduction pipe 64 and the control valve 84 of the branch pipe 82 are closed so that neither VOC gas nor defrost air flows into the gas introduction pipe 64. Keep it.
Then, before the operation of the VOC cooling / recovery device 30, the control valve 37 is also closed so that the precooler 60 is not initially operated.

First, the high temperature side compressor 38 is turned on.
When the high temperature side compressor 38 is operated, the refrigerant in the high temperature side circuit 33 is compressed and sent to the high temperature side condenser 40, and the high temperature side condenser 40 cools and liquefies the refrigerant at a constant pressure. The liquefied refrigerant is expanded by the high temperature side pressure reducing valve 43 to lower the boiling point, and the first high temperature side evaporator 44 in the cascade condenser 36 takes the heat of the low temperature side condenser 52 of the low temperature side circuit 34. Evaporate.

Next, after a predetermined time has elapsed since the high temperature side compressor 38 was turned on, the low temperature side compressor 51 is turned on in the low temperature side circuit 34.
Then, the refrigerant in the low-temperature side circuit 34 is compressed and sent to the low-temperature side condenser 52, and heat is exchanged with the high-temperature side evaporator 44 so that the refrigerant is cooled and liquefied at a constant pressure.
The liquefied refrigerant is expanded by the low temperature side pressure reducing valve 54 to lower the boiling point. In the low temperature side evaporator 56, the refrigerant takes the heat in the main cooler 62 and evaporates. Then, the evaporated and vaporized refrigerant flows into the low temperature side compressor 51.

  When the control unit 58 detects that the temperature in the cascade capacitor 36 has reached −10 ° C., the control unit 58 opens the control valve 37 and causes the refrigerant to flow through the branch pipe 49 on the precooler 60 side. The liquefied refrigerant is expanded by the high temperature side pressure reducing valve 43 of the branch pipe 49 to lower the boiling point, and in the second high temperature side evaporator 46, the heat in the precooler 60 is taken away and evaporated.

  At the same time, the controller 58 adjusts the opening degree of the control valve 39 so that the amount of refrigerant flowing to the precooler 60 side and the amount of refrigerant flowing to the cascade capacitor 36 are adjusted so that the temperature in the cascade capacitor 36 becomes constant. To distribute.

Next, by opening the control valve 68 and starting the operation of the blower 66, the VOC gas flows into the precooler 60 through the gas introduction pipe 64.
When the VOC gas flows into the precooler 60, in the second high temperature side evaporator 46 in the precooler 60, the refrigerant that has been expanded by the high temperature side pressure reducing valve 43 to lower the boiling point is introduced from the gas introduction pipe 64. VOC gas takes heat and evaporates. At this time, moisture contained in the VOC gas becomes frost and adheres to the precooler 60. For this reason, the VOC gas that has been preliminarily cooled after the removal of moisture is introduced into the next main cooler 62.
At this time, the temperature in the precooler 60 is about −10 ° C.

The VOC gas precooled by the precooler 60 is introduced into the main cooler 62 through the gas distribution pipe 67.
When the VOC gas flows into the main cooler 62, in the low temperature side evaporator 56 in the main cooler 62, the refrigerant that has been expanded by the low temperature side pressure reducing valve 54 to lower its boiling point is introduced from the gas circulation pipe 67. Takes away the heat and evaporates.
At this time, the temperature in the main cooler 62 is about −55 to −65 ° C.

  In this way, the VOC gas is cooled in the precooler 60 and the main cooler 62, and condensed and liquefied. The liquefied VOC accumulates in the lower part inside the precooler 60 and the main cooler 62. Since drain ports 72 and 74 are provided below the precooler 60 and the main cooler 62, the liquefied VOC flows out from the drain ports 72 and 74 through the drain recovery pipes 76 and 77 into the recovery tank 78, Collected.

The remaining gas from which the VOC has been removed is exhausted from the exhaust outlet 110 through the gas exhaust pipe 71, and the gas exhaust pipe 71 is disposed in the gas introduction pipe 64 disposed in the antifreezing heat exchanger 83. It is heated by the VOC gas that circulates. For this reason, it is possible to prevent the outlet closing valve 70 provided in front of the exhaust outlet 110 from being frozen and not operating.
In the main cooler 62, the VOC gas is cooled to −55 to −65 ° C., but the VOC gas flowing through the gas introduction pipe 64 has a temperature of about 50 ° C. For this reason, the temperature of the gas to be discharged can be raised to such an extent that the valve does not freeze. On the other hand, since the temperature of the VOC gas to be introduced is lowered before it is introduced into the precooler 60, the cooling efficiency can be increased.

In addition, when the VOC cooling and recovery operation is continuously performed, it is necessary to perform defrosting for removing frost attached to the precooler 60 in particular. In order to increase the cooling efficiency, it is necessary to defrost approximately every 8 hours.
At the time of defrosting, the high temperature side compressor 38 and the low temperature side compressor 51 are turned off to stop the refrigeration cycle. Then, the control valve 68 is closed to prevent VOC gas from flowing into the VOC gas introduction pipe 64, and the control valve 84 is opened to allow outside air as defrost air to flow into the gas introduction pipe 64. Further, the outlet closing valve 70 of the exhaust outlet 110 at the tip of the gas discharge pipe 71 is closed.

  When the defrost is performed in this manner, the frost in the precooler 60 is melted and the water is liquefied, and the liquefied water is recovered in the recovery tank 78 through the drain recovery pipe 76. Further, frost in the main cooler 62 is also collected in the collection tank 78 through the drain collection pipe 77.

At the time of defrosting, the exhaust outlet 110 is closed, so that the defrost air is not discharged from the exhaust outlet 110 but is recovered in the recovery tank 78 through the drain recovery pipes 76 and 77.
In the recovery tank 78, the recovered defrost air passes through the exhaust filter 80, and the VOC is recovered and exhausted to the outside.

  That is, at the time of defrosting, VOC remaining in the precooler 60 and the main cooler 62 is discharged together with the defrosting gas, so that it is not discharged from the exhaust outlet 110 of the gas discharge pipe 71. It can be recovered in the recovery tank 78.

(Second Embodiment)
Next, a second embodiment of the present invention will be described with reference to FIG.
In addition, about the same component as 1st Embodiment mentioned above, the same code | symbol is attached | subjected and description may be abbreviate | omitted.
In the second embodiment, two precoolers and two main coolers are provided so that VOC recovery and defrosting can be performed alternately, and antifreezing means are provided in the gas discharge pipes provided in each main cooler. There is a feature in the point.

Three high temperature side evaporators are connected in parallel to the high temperature side circuit 33 in the VOC cooling and recovery device 90 of the second embodiment, and one of the high temperature side evaporators constitutes the cascade condenser 36. Device 44. The other two units are two second high temperature side evaporators 46a and 46b, which are arranged in a sealed container and constitute precoolers 60a and 60b.
The second high temperature side evaporators 46a and 46b are provided so as to be branched from the refrigerant flow pipe 45 by branch pipes 49a and 49b, respectively, and are provided so that they can be alternately operated. Are provided with control valves 37a and 37b for controlling the flow of the refrigerant in the branch pipes 49a and 49b.
Further, drain recovery pipes 76a and 76b communicating with the recovery tank 78 are connected to the drain ports 72a and 72b provided in the precoolers 60a and 60b, respectively.

Moreover, in the low temperature side circuit 34, the two low temperature side evaporators 56a and 56b are provided in parallel, and each is arrange | positioned in an airtight container and comprises the main coolers 62a and 62b.
Of the two low temperature side evaporators 56a and 56b, one of the low temperature side evaporators 56a is provided to be branched from the refrigerant flow pipe 55 by a branch pipe 94a, and provided so that each can be operated alternately. Yes. For this reason, the refrigerant flow pipe 55 and the branch pipe 94a are provided with control valves 96a and 96b for controlling the flow of the refrigerant in the refrigerant flow pipe 55 and the branch pipe 94a.
Further, drain recovery pipes 77a and 77b communicating with the recovery tank 78 are connected to the drain ports 74a and 74b provided in the main coolers 62a and 62b.

  The drain collection pipes 76a, 76b, 77a, 77b are used for collecting the VOCs liquefied by the precoolers 60a, 60b and the main coolers 62a, 62b, and also have a role of circulating the defrost air to the collection tank 78 at the time of defrosting. is doing.

In the present embodiment, two systems of gas introduction pipes 65 for introducing the VOC gas into the precooler are provided. That is, one gas introduction pipe 65 connected to the VOC gas generation source is branched into two to constitute two systems of gas introduction pipes 65a and 65b.
One branched is a first gas introduction pipe 65a that introduces VOC gas into the precooler 60a, and the other branched is a second gas introduction pipe 65b that introduces VOC gas into the precooler 60b.
A check valve 98a and a control valve 99a for controlling the flow of VOC gas are provided upstream of the precooler 60a in the first gas introduction pipe 65a.
A check valve 98b and a control valve 99b for controlling the flow of VOC gas are provided upstream of the precooler 60b in the second gas introduction pipe 65b.

  In the present embodiment, the defrosting air is provided so as to pass through independent pipes up to the precoolers 60a and 60b, not the gas introduction pipes 65a and 65b. That is, the blower 86 is provided in the pipe extending from the introduction port for the defrost air, and the pipe branches into two downstream of the blower 86. One of the two branches is a defrost air introduction pipe 100a that introduces defrost air into the precooler 60a, and the other of the two branches is a defrost air introduction pipe 100b that introduces defrost air into the precooler 60b. is there.

A check valve 102a and a control valve 104a for controlling the flow of the defrost air are provided upstream of the precooler 60a of the defrost air introduction pipe 100a.
Further, a check valve 102b and a control valve 104b for controlling the flow of the defrost air are provided upstream of the precooler 60b of the defrost air introduction pipe 100b.

Between the precooler 60a and the main cooler 62a, a gas circulation pipe 106a through which the VOC gas and the defrost air are circulated is provided.
Similarly, between the precooler 60b and the main cooler 62b, a gas circulation pipe 106b through which VOC gas and defrost air can be circulated in common is provided.

Connected to the main cooler 62a is a gas exhaust pipe 108a for exhausting the recovered gas that has passed through the main cooler 62a and recovered the VOC gas. The gas discharge pipe 108a is provided with an outlet closing valve 70a that can close the exhaust outlet 110a formed at the tip of the gas discharge pipe 108a.
Similarly, the main cooler 62b is also connected to a gas exhaust pipe 108b that exhausts the recovered gas that has passed through the main cooler 62b and recovered the VOC gas. The gas discharge pipe 108b is provided with an outlet closing valve 70b that can close the exhaust outlet 110b formed at the tip of the gas discharge pipe 108b.

  The two gas discharge pipes 108a and 108b are provided with a common anti-freezing heat exchanger 83 for preventing freezing of the outlet closing valves 70a and 70b. The anti-freezing heat exchanger 83 has two gas discharge pipes 108a and 108b and a gas introduction pipe 65 arranged close to each other in a main body 87 having a heat insulating structure. Specifically, the gas introduction pipe 65 is arranged between the two gas discharge pipes 108a and 108b. In this way, in the heat exchanger 83 for preventing freezing, heat can be exchanged between the gas discharge pipes 108 a and 108 b and the single gas introduction pipe 65. The gas introduction pipe 65 disposed in the anti-freezing heat exchanger 83 is a single gas introduction pipe 65 before being branched into the two systems of gas introduction pipes 65a and 65b.

  Thus, in the present embodiment, there are provided two VOC gas distribution paths of the gas recovery unit in which the precooler 60a and the main cooler 62a are connected and the gas recovery unit in which the precooler 60b and the main cooler 62b are connected. And VOC recovery and defrosting can be executed. By alternately executing VOC recovery and defrosting in each gas recovery unit, VOC recovery processing can always be performed without stopping the operation.

Next, the operation of the VOC cooling and recovery device 90 in the second embodiment will be described.
First, before the operation of the VOC cooling and recovery device 90, the control valves 99a and 99b of the gas introduction pipes 65a and 65b are closed, and the control valves 104a and 104b of the defrost air introduction pipes 100a and 100b are also closed. Keep it.
Then, before the operation of the VOC cooling and recovery apparatus 30, the control valves 37a and 37b are also closed, and initially, the precoolers 60a and 60b are provided so as not to operate.
Further, one of the control valves 96a and 96b of the low temperature side circuit 34 is opened, and the other is closed. Here, it is assumed that the control valve 96a is opened.

First, the high temperature side compressor 38 is turned on.
When the high temperature side compressor 38 is operated, the refrigerant in the high temperature side circuit 33 is compressed and sent to the high temperature side condenser 40, and the high temperature side condenser 40 cools and liquefies the refrigerant at a constant pressure. The liquefied refrigerant is expanded by the high temperature side pressure reducing valve 43 to lower the boiling point, and the first high temperature side evaporator 44 in the cascade condenser 36 takes the heat of the low temperature side condenser 52 of the low temperature side circuit 34. Evaporate.

Next, after a predetermined time has elapsed since the high temperature side compressor 38 was turned on, the low temperature side compressor 51 is turned on in the low temperature side circuit 34.
Then, the refrigerant in the low-temperature side circuit 34 is compressed and sent to the low-temperature side condenser 52, and heat is exchanged with the high-temperature side evaporator 44 so that the refrigerant is cooled and liquefied at a constant pressure.
The liquefied refrigerant is expanded by the low temperature side pressure reducing valve 54 to lower the boiling point. Then, the refrigerant flows through the low temperature side evaporator 56a communicating with the open control valve 96a, and the heat in the main cooler 62 is taken away and evaporated. Then, the evaporated and vaporized refrigerant flows into the low temperature side compressor 51.

  When the control unit 58 detects that the temperature in the cascade capacitor 36 has become −10 ° C., the control unit 58 controls the control valve 37a of the precooler 60a connected to the operating main cooler 62a. Open and let the refrigerant flow through the branch pipe 49a on the precooler 60a side. The liquefied refrigerant is expanded by the high temperature side pressure reducing valve 43a of the branch pipe 49a to lower the boiling point, and evaporates by taking the heat in the precooler 60a in the second high temperature side evaporator 46a.

  At the same time, the control unit 58 adjusts the opening degree of the control valve 39 to adjust the amount of refrigerant flowing to the precooler 60a side and the amount of refrigerant flowing to the cascade capacitor 36 so that the temperature in the cascade capacitor 36 becomes constant. To distribute.

Next, by opening the control valve 99a and starting the operation of the blower (not shown), the VOC gas flows into the precooler 60a through the gas introduction pipe 65a.
When the VOC gas flows into the precooler 60a, in the second high temperature side evaporator 46a in the precooler 60a, the refrigerant having the boiling point lowered by being expanded by the high temperature side pressure reducing valve 43a is introduced from the gas introduction pipe 65a. VOC gas takes heat and evaporates. At this time, moisture contained in the VOC gas becomes frost and adheres to the precooler 60a. For this reason, the VOC gas from which moisture has been removed and precooled is introduced into the next main cooler 62a.
At this time, the temperature in the precooler 60a is about −10 ° C.

The VOC gas precooled by the precooler 60a is introduced into the main cooler 62a through the gas circulation pipe 106a.
When the VOC gas flows into the main cooler 62a, in the low-temperature side evaporator 56a in the main cooler 62a, the refrigerant that has been expanded by the low-temperature side pressure reducing valve 54 to lower its boiling point is introduced from the gas circulation pipe 106a. Takes away the heat and evaporates.
At this time, the temperature in the main cooler 62a is about −55 to −65 ° C.

  In this way, the VOC gas is cooled in the precooler 60a and the main cooler 62a, condensed and liquefied. The liquefied VOC accumulates in the lower part of the precooler 60a and the main cooler 62a. Since drain ports 72a and 74a are provided below the precooler 60a and the main cooler 62a, the liquefied VOC flows from the drain ports 72a and 74a through the drain recovery pipes 76a and 77a into the recovery tank 78, Collected.

  The remaining gas from which the VOC has been removed is discharged from the gas discharge pipe 108a of the main cooler 62a to the exhaust outlet 110a. At this time, the gas at −55 to −65 ° C. flowing through the gas discharge pipe 108 a is heated by the 50 ° C. VOC gas flowing through the gas introduction pipe 65. For this reason, it is possible to prevent the outlet closing valve 70a provided in front of the exhaust outlet 110 from being frozen and not operating. On the other hand, since the temperature of the introduced VOC gas is lowered before being introduced into the precooler 60a, the cooling efficiency can be increased.

In addition, when the VOC cooling and recovery operation is continuously performed, it is necessary to perform defrosting for removing frost attached to the precooler 60 in particular. In order to increase the cooling efficiency, it is necessary to defrost approximately every 8 hours.
Therefore, when the defrost execution time comes, the control valve 37a to the precooler 60a is closed and the control valve 37b to the precooler 60b is opened. At the same time, in order to switch the introduction of VOC, the control valve 99a of the gas introduction pipe 65a is closed and the control valve 99b of the gas introduction pipe 65b is opened. Then, the high-temperature side refrigerant flows to the precooler 60b without flowing to the precooler 60a, and the inside of the precooler 60b is cooled. At the same time, VOC gas is introduced into the precooler 60b and precooled.

Further, the low temperature side circuit 34 also switches the introduction of the VOC gas. That is, the control valve 96a is closed and the control valve 96b is opened. Then, the low temperature side refrigerant flows to the main cooler 62b without flowing to the main cooler 62a.
The VOC gas preliminarily cooled by the precooler 60b is introduced into the main cooler 62b through the gas circulation pipe 106b, and the VOC is separated and discharged from the gas discharge pipe 108b.

  The remaining gas from which the VOC has been removed is discharged from the gas discharge pipe 108b of the main cooler 62b to the exhaust outlet 110b. At this time, the gas at −55 to −65 ° C. flowing through the gas discharge pipe 108 b is heated by the 50 ° C. VOC gas flowing through the gas introduction pipe 65. Therefore, it is possible to prevent the outlet closing valve 70b provided in front of the exhaust outlet 110 from being frozen and not operating. On the other hand, since the temperature of the VOC gas to be introduced is lowered before being introduced into the precooler 60b, the cooling efficiency can be increased.

The VOC recovery unit that has been used for VOC recovery until now is defrosted. That is, the control valve 104a of the defrost air introduction pipe 100a is opened and the blower 86 is operated, so that the defrost air is introduced into the precooler 60a that has been used for VOC recovery until now. Here, normal outside air is used as defrost air.
In the precooler 60a into which the defrost air is introduced, frost is melted, and the melted frost becomes water containing VOC and is recovered from the drain port 72a through the drain recovery pipe 76a to the recovery tank 78.

The defrost air that has passed through the precooler 60a is introduced into the main cooler 62a through the gas flow pipe 106a. In the main cooler 62a, almost no frost is attached, but some frost is attached, so that the frost melts, and the melted frost becomes water containing VOC from the drain port 74a to the drain recovery pipe 77a. It passes through the recovery tank 78 and passes through.
When defrosting is performed, the outlet closing valve 70a of the gas discharge pipe 108a provided in the main cooler 62 is closed. For this reason, the defrost air is not discharged from the gas discharge pipe 108a, but is discharged from the drain port 74a of the main cooler 62a or the drain port 72a of the precooler 60a. In this way, the defrost air is introduced into the recovery tank 78 from the drain recovery pipes 76a and 77a.
In the recovery tank 78, the recovered defrost air passes through the exhaust filter 80, VOC is removed, and the air is exhausted to the outside.

When the defrosting of the VOC recovery unit is completed, the control valve 104a may be closed and the operation of the blower 86 may be stopped in order to stop the introduction of the defrosting air. During this time, the other VOC recovery units continue to execute the VOC recovery operation until a predetermined time elapses.
Then, after a predetermined time elapses, the operation of the VOC recovery unit that has been executing the VOC recovery is stopped, and the defrost air is sent to execute the defrost. Further, the VOC recovery unit that has been defrosted is caused to introduce a VOC gas and execute a VOC recovery operation.

  The switching operation of each control valve as described above may be performed manually, or the control unit 58 may automatically control the control valve by outputting a control signal to each control valve.

  Further, in each of the embodiments described above, the antifreezing heat exchanger in which the gas discharge pipe and the gas introduction pipe are arranged close to each other as the antifreezing means has been described. It is not limited to the anti-freezing heat exchanger configured as described above.

  Further, as described in the second embodiment, when a plurality of gas discharge pipes are provided, all the gas discharge pipes and one gas introduction pipe are placed in one antifreeze heat exchanger. You may arrange | position, and you may provide the heat exchanger for antifreezing one by one in each gas discharge pipe. When one anti-freezing heat exchanger is provided for each gas discharge pipe, one gas introducing pipe may be arranged in common for each anti-freezing heat exchanger, or the gas introducing pipe is branched. You may arrange | position to each heat exchanger for antifreezing.

  While the present invention has been described above with reference to a preferred embodiment, the present invention is not limited to this embodiment, and it goes without saying that many modifications can be made without departing from the spirit of the invention. .

It is explanatory drawing which shows the whole structure of 1st Embodiment of the VOC cooling recovery apparatus of this invention. It is explanatory drawing which shows the whole structure of 2nd Embodiment of the VOC cooling recovery apparatus of this invention. It is explanatory drawing which shows the conventional gas collection | recovery apparatus.

Explanation of symbols

Reference Signs List 30 Cooling recovery device 32 Dual refrigerator 33 High temperature side circuit 34 Low temperature side circuit 35 Fan 36 Cascade capacitor 37 Control valve 38 High temperature side compressor 39 Control valve 40 High temperature side condenser 43 High temperature side pressure reducing valve 44 First high temperature side evaporation 45 Refrigerant flow pipe 46 Second high temperature side evaporator 49 Branch pipe 50 Refrigerant dryer 51 Low temperature side compressor 52 Low temperature side condenser 53 Temperature sensor 54 Low temperature side pressure reducing valve 55 Refrigerant flow pipe 56 Low temperature side evaporator 57 Refrigerant dryer 58 Control unit 59 Oil separator 60 Precooler 62 Main cooler 64, 65 Gas introduction pipe 66 Blower 67 Gas distribution pipe 68 Control valve 70 Outlet closing valve 71 Gas discharge pipe 72, 74 Drain port 76, 77 Drain collection pipe 78 Collection tank 79 Exhaust Pipe 80 Exhaust filter 82 Branch pipe 83 Freezing Prevention heat exchanger 84 Control valve 86 Blower 87 Main body 90 Cooling recovery device 91 Heat insulation member 94 Branch pipe 96 Control valve 98 Check valve 99 Control valve 100 Defrost air introduction pipe 102 Check valve 104 Control valve 106 Gas flow pipe 108 Gas exhaust pipe 110 Exhaust outlet

Claims (2)

A VOC cooling and recovery device that liquefies and recovers VOC from VOC gas containing VOC that is in the form of gas,
A binary refrigerator in which a high temperature side circuit cooled by a first refrigerant and a low temperature side circuit cooled by a second refrigerant are thermally connected via a cascade capacitor;
A precooler that preliminarily cools the VOC gas to be introduced, wherein the evaporator of the high-temperature circuit is disposed in the first sealed container;
A main cooler for cooling the pre-cooled VOC gas, wherein the evaporator of the low-temperature circuit is disposed in a second sealed container;
A gas introduction pipe for introducing VOC gas into the precooler;
A gas distribution pipe for introducing the VOC gas preliminarily cooled and discharged in the precooler into the main cooler;
A gas discharge pipe for discharging the remaining gas from which the VOC has been recovered by the main cooler from the main cooler;
An outlet closing valve for closing the exhaust outlet of the gas exhaust pipe;
A drain port provided at a lower portion of the pre-cooler and the main cooler;
A drain recovery pipe connected to each drain port of the precooler and the main cooler, and for circulating VOCs liquefied in the precooler and the main cooler;
A recovery tank connected to the drain recovery pipe and storing the recovered VOC;
A VOC cooling and recovery apparatus comprising: an anti-freezing means for preventing the outlet closing valve from freezing. The anti-freezing means includes
The gas introduction pipe and the gas discharge pipe are provided in a main body having a heat insulating structure so that they can be arranged close to each other, and the temperature of the gas to be discharged is increased by the temperature of the VOC gas flowing through the gas introduction pipe to thereby close the outlet closing valve. A VOC cooling and recovery device, which is a freeze-preventing heat exchanger that prevents freezing of the water.

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