JP2008279380A - Voc cooling/recovery device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a VOC cooling/recovery device which can execute a defrosting operation without stopping a VOC cooling/recovery operation and requires no piping for introducing defrosting air. <P>SOLUTION: This VOC cooling/recovery device has a precooler 60 arranged in a high-temperature side circuit 33 of a two element-freezer 32, and a low-temperature side circuit 34 keeps two main coolers 62a and 62b connected in series by a main cooler connecting pipe 94 for circulating the VOC gas, so as to allow the VOC gas exhausted from the precooler 60 to be continuously introduced into the main coolers 62a and 62b. In addition, one main cooler 62b arranged on the precooler 60 side, is stopped cooling so that the main cooler 62b can be defrosted by the introduced VOC gas. The other main cooler 62a is arranged so as to recover the VOC by cooling the VOC gas, and thus these two main coolers 62a and 62b are arranged in a switchable manner to decide which one of the main coolers 62a and 62b should have the priority to first receive the VOC gas to be introduced from the precooler 60. <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. 5, 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.)

  In the conventional gas recovery apparatus as described above, defrost (removal of frost) is not particularly disclosed. That is, when the gas is cooled and recovered, frost adheres to the cooling device as long as the gas contains moisture. If this frost is not removed, the cooling efficiency is extremely deteriorated, and therefore there is a problem that it is necessary to perform defrosting after operating for a predetermined time.

  As a method of defrosting, there is a method in which the operation is stopped and frost is melted at room temperature. During that time, however, it becomes impossible to treat the VOC gas, so it is not preferable to stop the operation. There is a desire to make it as short as possible. In order to shorten the stop time, there are methods such as heater defrosting and hot gas defrosting, but these methods are difficult to adopt because of the danger of explosion.

  In addition, a configuration in which normal room temperature air for defrosting is introduced into the precooler and main cooler is also conceivable. However, piping and blowers for defrosting are required, which complicates the structure and increases the number of parts. There is also a problem of end.

  SUMMARY OF THE INVENTION 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 apparatus that can execute defrost without stopping the VOC cooling recovery operation and does not require introduction of defrost air.

  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 the VOC gas containing the VOC that is in the form of gas. An evaporator is arranged in the first sealed container, and a precooler for precooling the VOC gas introduced into the first sealed container is provided, and the low-temperature circuit of the dual refrigerator is switched to each other. The two evaporators are provided in parallel so that they can be operated, and the respective evaporators are arranged in the second sealed container and the third sealed container, respectively, and the VOC gas discharged from the precooler is disposed. Two main coolers to be introduced are provided, and the two main coolers are main coolers for circulating the VOC gas so that the VOC gas discharged from the precooler is continuously introduced into both main coolers. VOC gas introduced from the precooler so that the refrigerant does not flow to the evaporator in one of the main coolers provided on the precooler side of the two main coolers. The evaporator in the other main cooler is provided so as to flow refrigerant and cool the VOC gas discharged from one main cooler, and 2 VOC gas introduced from the precooler is supplied. It is characterized in that it can be switched to which of the main coolers of the stand is first introduced.

The effect | action by employ | adopting this structure is as follows.
That is, the VOC gas is precooled at a temperature at which frost does not adhere in the precooler. The precooled VOC gas is introduced into one of the uncooled main coolers, and the one main cooler can be defrosted. The VOC gas exiting from one main cooler is introduced into the other main cooler, where it is cooled and VOC is recovered.
When the defrosting of the other main cooler becomes necessary after a predetermined time has passed, the precooled VOC gas is introduced into the other main cooler to perform defrosting, and the VOC gas exiting the other main cooler It is switched to be introduced into the cooler and cooled.
As described above, according to the configuration of the present invention, the main cooler can be operated alternately, the main cooler on the non-operating side can be defrosted, and the defrost can be executed without interrupting the VOC recovery operation. Driving is now possible. Further, since defrosting is performed using VOC gas, defrosting can be performed without introducing defrosting air.

  In addition, the space between the precooler and the two main coolers is branched into the first gas circulation pipe and the second gas circulation pipe on the main cooler side from the place connected to the precooler. The first gas circulation pipe is connected to one end of one of the two main coolers, and the second gas circulation pipe is the other main of the two. Connected to one end of the cooler, the first gas circulation pipe is provided with a first main cooler connection valve for opening and closing the first gas circulation pipe, and the second gas circulation pipe has a second gas A second main cooler connection valve for opening and closing the flow pipe is provided, and the first gas discharge pipe branched between the first main cooler connection valve and one main cooler is provided in the first gas flow pipe. A pipe is provided, and the second gas flow pipe includes A second gas discharge pipe branched from the second main cooler connection valve and the other main cooler is provided, a first outlet valve for opening and closing the first gas discharge pipe is provided, and the second A second outlet valve that opens and closes the gas discharge pipe may be provided.

Further, heat exchange is performed such that the first gas circulation pipe and the second gas circulation pipe are arranged close to each other, and heat is exchanged between the first gas circulation pipe and the second gas circulation pipe. A vessel may be provided.
By adopting this configuration, heat is exchanged between the relatively high temperature VOC gas coming out of the precooler and the very low temperature gas coming out of the main cooler (the VOC is separated by the main cooler). The temperature of the gas that comes out of the main cooler and is exhausted slightly increases. For this reason, there is a possibility that the outlet valve of the gas exhaust pipe will freeze when exhausted at an extremely low temperature, but the temperature of the gas exhausted from the exhaust outlet will rise slightly, so that the outlet valve can be prevented from freezing. it can.

  According to the VOC cooling and recovery apparatus of the present invention, defrosting can be performed without interrupting the VOC recovery operation. In addition, since defrosting can be performed without introducing defrosting air, downsizing can be achieved at low cost.

DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, preferred embodiments of the invention will be described in detail with reference to the accompanying drawings.
FIG. 1 and FIG. 2 are explanatory diagrams for illustrating the operation principle in the VOC cooling and recovery apparatus of the present invention.
As shown in FIG. 1, in the VOC cooling and recovery apparatus 30, a precooler 60 is disposed in the high temperature side circuit 33 of the binary refrigerator 32, and two main coolers 62 a and 62 b are disposed in the low temperature side circuit 34. . In the precooler 60, the VOC gas is precooled to about 0 ° C. The precooled VOC gas is introduced into the main coolers 62a and 62b.

The VOC gas preliminarily cooled by the precooler 60 is first introduced into the other main cooler 62b of the two main coolers connected in series, and defrosts inside the main cooler 62b.
The VOC gas exiting from the main ink cooler 62b is introduced into one main cooler 62a, cooled to an extremely low temperature of about −55 to −65 ° C., and the VOC is liquefied, condensed and recovered. The remaining gas from which the VOC has been separated is exhausted.

When the operation shown in FIG. 1 is executed for a predetermined time, frost adheres in one main cooler 62a, so it is necessary to defrost the main cooler 62a.
Therefore, as shown in FIG. 2, the introduction destination of the VOC gas discharged from the precooler 60 is switched to the main cooler 62a, the cooling operation of the main cooler 62a is stopped, and the cooling of the main cooler 62b is started. Then, the main cooler 62a that has been performing the cooling operation until now is defrosted by the relatively high temperature VOC gas, and the main cooler 62b that has been defrosted and has not been attached with frost performs the cooling operation.

  In this way, the main coolers are connected in series so that the main cooler existing on the precooler side does not perform cooling operation, the main cooler not existing on the precooler side is cooled, and the connection order of the main coolers is set every predetermined time. By reversing, defrost and VOC recovery can be executed alternately. For this reason, defrosting is possible without continuously operating the dual refrigerator and without introducing defrost air.

(First embodiment)
FIG. 3 shows the overall configuration of the first specific embodiment of the VOC cooling and recovery apparatus of the present invention.
The VOC cooling and recovery apparatus 30 of the present embodiment uses a binary refrigerator 32, and after preliminarily cooling the VOC gas by the high temperature side circuit 33 of the binary refrigerator 32, the VOC gas is further cooled by the low temperature side circuit 34.

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 two low temperature side evaporators 56a and 56b. These devices are connected by a refrigerant flow pipe 55 through which the low-temperature side refrigerant flows. Of the two low-temperature evaporators 56a and 56b, the low-temperature evaporator 56b is provided in a branch pipe 69 branched from the refrigerant flow pipe 55, and the two low-temperature evaporators 56a and 56b are low-temperature evaporators. The side condenser 52 is connected in parallel.

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.
Further, 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.

The refrigerant flow pipe 55 connected to the low temperature side evaporator 56a is provided with a control valve 54a for adjusting the flow rate of the refrigerant flowing through the refrigerant flow pipe 55, and the branch pipe connected to the low temperature side evaporator 56b. 69 is provided with a control valve 54 b for adjusting the flow rate of the refrigerant flowing through the branch pipe 69.
By switching between opening and closing of these control valves 54a and 54b, it is possible to switch between the evaporator 56a and the evaporator 56b.

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.
The temperature of the precooler 60 in this invention shall be about 0 degreeC. At the temperature of about 0 ° C., moisture contained in the VOC gas cannot be attached as frost in the precooler 60.
On the other hand, the low-temperature side evaporators 56a and 56b of the low-temperature side circuit 34 are also arranged in sealed containers, respectively, and constitute main coolers 62a and 62b that liquefy VOC. The temperature in the main cooler 62 is controlled to be about −55 to −65 ° C.
In addition, as the airtight container which comprises the main coolers 62a and 62b, it is cylindrical shape, and is made into the one side and the other side along the axial direction of a cylinder.

  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 so that the VOC gas is fed into the gas introduction pipe 64 by the blower (not shown). 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 passes through the gas circulation pipe 67 in the two main coolers 62a and 62b. To be introduced.
The gas circulation pipe 67 exiting from the precooler 60 is branched into two in the middle, and one is a first gas circulation pipe 67a and the other is a second gas circulation pipe 67b. In the present embodiment, the first gas flow pipe 67a is connected to one side of the main cooler 62a, and the second gas flow pipe 67b is connected to one side of the main cooler 62b.

The first gas circulation pipe 67a is provided with a first main cooler connection valve 90a for opening and closing the first gas circulation pipe 67a, and the second gas circulation pipe 67b includes a second gas circulation pipe. A second main cooler connection valve 90b that opens and closes 67b is provided.
When one of the first main cooler connection valve 90a and the second main cooler connection valve 90b is open, the other is closed, and VOC gas is simultaneously introduced into the two main coolers 62a and 62b. It is controlled not to be done.

  Between the other end side of the main cooler 62a and the other end side of the main cooler 62b, a main cooler connection pipe 94 that distributes the VOC gas between the main coolers 62a and 62b is disposed.

In addition, after the VOC gas is introduced into the first gas circulation pipe 67a of the main cooler 62a from the other side of the main cooler 62a, a first gas for exhausting the remaining gas from which the VOC has been cooled and recovered by the main cooler 62a. One gas discharge pipe 71a is branched and provided. The first gas discharge pipe 71a is provided between the first main cooler connection valve 90a and the main cooler 62a of the first gas circulation pipe 67a.
Similarly, after the VOC gas is introduced into the second gas circulation pipe 67b of the main cooler 62b from the other side of the main cooler 62b, the remaining gas from which the VOC has been cooled and recovered by the main cooler 62b is exhausted. The second gas exhaust pipe 71b is branched and provided. The second gas discharge pipe 71b is provided between the second main cooler connection valve 90b and the main cooler 62b of the second gas circulation pipe 67b.

  Exhaust outlets 110a and 110b are provided at the ends of the gas exhaust pipes 71a and 71b. Further, the gas exhaust pipes 71a and 71b are provided with outlet valves 70a and 70b for opening and closing the exhaust outlets 110a and 110b, respectively.

  Around the gas circulation pipe 67, the first gas circulation pipe 67a, the second gas circulation pipe 67b, the main cooler connection pipe 94, the first gas discharge pipe 71a, and the second gas discharge pipe 71b, there are ambient temperatures. The heat insulating member 91 is provided so that the low temperature state of the VOC gas flowing can be maintained.

Further, since the gas discharged from the gas discharge pipes 71a and 71b is cooled to a very low temperature by the main coolers 62a and 62b, the outlet valves 70a and 70b may be frozen. Therefore, it is preferable to provide anti-freezing means for preventing the outlet valves 70a and 70b from freezing.
As an example of the freeze prevention means in the present embodiment, a heat exchanger 96 that performs heat exchange between the first gas circulation pipe 67a and the second gas circulation pipe 67b is applicable.

  The heat exchanger 96 is provided in the main body 97 of the heat insulating structure so that the first gas circulation pipe 67a and the second gas circulation pipe 67b are arranged close to each other. Further, the heat insulating member 91 is not arranged in the heat exchanger 96 so that heat exchange is possible between the first gas flow pipe 67a and the second gas flow pipe 67b.

Drain ports 72, 74a, and 74b are provided at the lower portions of the precooler 60 and the two main coolers 62a and 62b, respectively.
The drain port 72 is connected to a drain recovery pipe 76 provided with a drain control valve 81, and the drain recovery pipe 76 is connected to a recovery tank 78. The drain ports 74 a and 74 b are connected to drain recovery pipes 77 a and 77 b provided with drain control valves 83 a and 83 b, and the drain recovery pipes 77 a and 77 b are connected to a recovery tank 78.

  As described above, when the VOC is condensed and liquefied by the precooler 60, the main cooler 62a, or the main cooler 62b, the liquefied VOC is stored in the recovery tank 78 via the drain recovery pipe 76 and the drain recovery pipes 77a and 77b. . 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.

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 is closed so that the VOC gas does not flow into the gas introduction pipe 64.
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.

In addition, one of the refrigerant flow pipe 55a and the branch pipe 55b of the low temperature side circuit 34 is opened and the other is closed. For this reason, in the low temperature side circuit 34, only one of the main coolers operates. In the following, first, the main cooler 62a is controlled to operate.
Further, the first gas circulation pipe 67a is introduced so that the introduction of the VOC gas does not flow into the first main cooler 62a that operates first, that is, the VOC gas is first introduced into the main cooler 62b that does not operate. The first main cooler connection valve 90a is closed to close, and the second main cooler connection valve 90b is opened to open the second gas flow pipe 67b.
The outlet valve 70a of the first gas discharge pipe 71a is opened, and the outlet valve 70b of the second gas discharge pipe 71b is closed.

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 62a 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 condenser 36 has reached 0 ° C., the control unit 58 opens the control valve 37 and causes the refrigerant to flow through the branch pipe 49 of the precooler 60. 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 a blower (not shown), 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, the temperature in the precooler 60 is about 0 ° C., and frost does not adhere in the precooler 60.

The VOC gas precooled by the precooler 60 is introduced into the main cooler 62b through the second gas circulation pipe 67b.
In the main cooler 62b, the refrigerant does not flow into the evaporator 56b and is not cooled. The VOC gas passes through the main cooler 62b as it is and flows into the main cooler connection pipe 94.
The VOC gas that has circulated through the main cooler connection pipe 94 flows into the main cooler 62a where the refrigerant flows into the evaporator 56a and cooling is being performed.

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 the boiling point takes the heat of the introduced VOC gas. Evaporate.
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 62a, condensed and liquefied. The liquefied VOC accumulates in the lower part of the precooler 60 and the main cooler 62a. Since drain ports 72 and 74a are provided below the precooler 60 and the main cooler 62a, the liquefied VOC flows out from the drain ports 72 and 74a into the recovery tank 78 through the drain recovery pipes 76 and 77a. Collected.

The remaining gas from which the VOC has been removed is exhausted from the exhaust outlet 110 through the first gas exhaust pipe 71a.
At this time, the temperature of the discharged gas is raised by the VOC gas flowing through the second gas flow pipe 67b in the heat exchanger 96. Thereby, it is possible to prevent the outlet valve 70a from being frozen.

If the VOC cooling and recovery operation is continuously performed, it is necessary to perform defrosting to remove frost attached to the main cooler 62a. In order to increase the cooling efficiency, it is necessary to defrost approximately every 8 hours.
At the time of defrosting, the VOC gas discharged from the precooler 60 is introduced into the main cooler 62a that has been used for cooling so far, defrosting is performed, the inside of the main cooler 62b is cooled, and the VOC is recovered by the main cooler 62b. I do.

That is, at the time of defrosting, the first main cooler connection valve 90a is opened, the second main cooler connection valve 90b is closed, the outlet valve 70a is closed, and the outlet valve 70b is opened.
Further, by closing the control valve 54a of the low temperature side circuit 34 and opening the control valve 54b, the cooling of the main cooler 62a is stopped and the main cooler 62b is cooled.
Therefore, the VOC gas discharged from the precooler 60 is introduced into the main cooler 62a through the first gas circulation pipe 67a and defrosted by the VOC gas at about 0 ° C. The VOC gas that has passed through the main cooler 62a is introduced into the main cooler 62b through the main cooler connecting pipe 94, and liquefaction recovery of the VOC is performed.
The remaining gas from which the VOC has been separated is discharged from the exhaust outlet 110b through the second gas discharge pipe 71b.
When defrosting is performed in this manner, the frost in the main cooler 62a is melted and the water is liquefied, and the liquefied water is recovered in the recovery tank 78 through the drain recovery pipe 76a.

(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.
The second embodiment is provided with anti-freezing means for the outlet valve that is different from the first embodiment.

  That is, as the outlet valve freezing prevention means, the gas discharge pipes 71a and 71b from the two main coolers 62a and 62b and the gas introduction pipe 64 for introducing the VOC gas to the precooler 60 are arranged inside. A heat exchanger 100 is provided for heat exchange between the gas flowing through the gas discharge pipes 71a and 71b and the VOC gas flowing through the gas introduction pipe 64.

  The heat exchanger 100 is provided in the main body 101 of the heat insulating structure so that the two gas discharge pipes 71a and 71b and the gas introduction pipe 64 are arranged close to each other. Further, the heat insulating member 91 provided in each gas discharge pipe 71a, 71b is placed in the heat exchanger 100 so that heat exchange is possible between each gas discharge pipe 71a, 71b and the gas introduction pipe 64. Is not placed.

  In the main coolers 62a and 62b, 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 FIG. 4, in addition to the heat exchanger 100 having the gas discharge pipes 71a, 71b and the gas introduction pipe 64, the heat exchanger 96 having the gas flow pipes 76a, 76b as shown in the first embodiment. The place where was provided.
However, as the freeze prevention means, the gas exhaust pipes 71a and 71b and the gas introduction pipe 64 are built in without providing the heat exchanger 96 containing the gas flow pipes 76a and 76b as shown in the first embodiment. Only the heat exchanger 100 may be provided.

  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.

  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 schematic structure of the VOC cooling recovery apparatus of this invention. It is explanatory drawing which shows the place which switched the connection of the main cooler in the schematic structure of FIG. 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 Control valve 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 Gas introduction pipe 67 Gas distribution pipe 68 Control valve 69 Branch pipe 70 Outlet valve 71 Gas exhaust pipe 72, 74 Drain port 76, 77 Drain collection pipe 78 Collection tank 79 Exhaust pipe 80 Exhaust filter 81, 83 Drain Control valve 90 main cooler connection valve 91 heat insulation member 94 main cooler connection pipe 96 heat exchanger 97 heat exchanger body 100 heat exchanger 101 heat exchanger body 110 exhaust outlet

Claims (3)

A VOC cooling and recovery device that liquefies and recovers VOC from VOC gas containing VOC that is in the form of gas,
The evaporator of the high temperature side circuit of the binary refrigerator is arranged in the first sealed container, and a precooler for precooling the VOC gas introduced into the first sealed container is provided,
In the low-temperature circuit of the dual refrigerator, two evaporators are provided in parallel so that they can be switched to operate, and each evaporator is disposed in the second sealed container and the third sealed container, respectively. Two main coolers for introducing the VOC gas discharged from the precooler are provided,
The two main coolers are connected in series by a main cooler connecting pipe for circulating the VOC gas so that the VOC gas discharged from the precooler is continuously introduced into both main coolers.
The refrigerant in one main cooler arranged on the precooler side of both main coolers is provided so as to be defrosted by the VOC gas introduced from the precooler so that the refrigerant does not flow,
The evaporator in the other main cooler is provided to flow the refrigerant and cool the VOC gas discharged from the one main cooler,
A VOC cooling and recovery apparatus, wherein the VOC gas introduced from the precooler is provided so as to be switched to which of the two main coolers is first introduced. Between the precooler and the two main coolers, the gas branched into two of the first gas circulation pipe and the second gas circulation pipe on the main cooler side from the portion connected to the precooler. A distribution pipe is provided,
A first gas distribution pipe is connected to one end of one of the two main coolers;
A second gas distribution pipe is connected to one end of the other main cooler of the two units;
The first gas circulation pipe is provided with a first main cooler connection valve that opens and closes the first gas circulation pipe,
The second gas circulation pipe is provided with a second main cooler connection valve that opens and closes the second gas circulation pipe,
The first gas circulation pipe is provided with a first gas discharge pipe that is branched between the first main cooler connection valve and one main cooler,
The second gas circulation pipe is provided with a second gas discharge pipe that is branched between the second main cooler connection valve and the other main cooler,
A first outlet valve for opening and closing the first gas exhaust pipe is provided;
2. The VOC cooling and recovery apparatus according to claim 1, further comprising a second outlet valve for opening and closing the second gas discharge pipe.   A heat exchanger in which the first gas circulation pipe and the second gas circulation pipe are arranged close to each other and heat exchange is performed between the first gas circulation pipe and the second gas circulation pipe. The VOC cooling and recovery apparatus according to claim 2, wherein the VOC cooling and recovery apparatus is provided.