JP2012130875A - Solvent recovery apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a solvent recovery apparatus which efficiently recovers a solvent at a low cost, from a gas to be treated discharged by e.g. a factory, and containing a high-boiling-point solvent.SOLUTION: The solvent recovery apparatus includes: a cooling recovery section 10 consisting of a heat exchanger 11 for carrying out primary cooling of the gas to be treated containing vapor of a high boiling-point solvent with a boiling point of ≥150°C and a cooler 13 for carrying out secondary cooling with cold water the gas G1 to be treated after the primary cooling; and an adsorption recovery section 20 adsorbing vapor of the high-boiling-point solvent remaining in the gas G1 to be treated after the cooling by the cooling recovery section 10, by an adsorbent, and separating and recovering the solvent from the gas G1to be treated. The apparatus is characterized in that the heat exchanger 11 for carrying out primary cooling of the gas G1to be treated uses outside air A for cooling a coolant for circulation.

Description

  The present invention relates to a solvent recovery apparatus that recovers the solvent efficiently and at low cost from a gas to be treated that contains a high-boiling solvent having a boiling point of 150 ° C. or higher, discharged from a factory or the like.

  High boiling solvents such as N-methyl-2-pyrrolidone (NMP), cyclohexanone, and high flash point hydrocarbons used in factories are harmful to the environment. It is necessary to separate and recover the high boiling point solvent from the air it contains.

  Conventionally, as a method for recovering a high boiling point solvent, a cooling method for directly cooling a gas to be treated containing a solvent has been adopted. However, a large amount of energy is required to almost completely condense a high-boiling solvent having a boiling point of about 150 to 300 ° C. only by cooling by this method. For example, in the case of NMP, the saturation concentration in air at 20 ° C. is about 400 ppm. If it is intended to condense 90% or more by cooling alone, it must be cooled to -10 ° C, which is not realistic.

  As another method, there is an adsorption method using activated carbon or the like. However, since this method uses water vapor as a heat source for desorption, the desorption capacity of the high-boiling solvent is small and regeneration is likely to be insufficient. Further, since the activated carbon is flammable, it cannot be desorbed at a high temperature, resulting in insufficient regeneration. For this reason, the adsorption method using activated carbon or the like is mainly used for the recovery of low boiling point solvents.

  In order to solve this problem, a recovery device that cools the gas to be treated with a cooler and condenses and recovers the solvent, and then adsorbs and removes the gas to be treated containing the residual solvent using an adsorbent is proposed. (For example, Patent Document 1). However, in this method, since the gas to be processed is directly cooled by the cooler, when cooling the gas to be processed at a high temperature, a large amount of cold water is required, and the operation cost becomes high.

  As a means for cooling the gas to be treated with a small amount of cooling water and cold water, a method is conceivable in which the gas to be treated is cooled with a circulation heat exchanger, and the outside air is first temperature-controlled as a cooling refrigerant for the circulation heat exchanger. . However, this method has a limit in cooling of the gas to be treated due to the performance of the circulation heat exchanger, and the cooling and recovery of the solvent cannot be performed appropriately. In such a case, the gas concentration of the residual solvent of the gas to be treated introduced into the adsorption recovery unit tends to increase. If the gas concentration of the residual solvent of the gas to be treated becomes high and exceeds the adsorption performance of the adsorption / recovery unit, the desired solvent purification performance cannot be obtained. Therefore, this method is not preferable.

  It is conceivable to introduce a gas / gas heat exchanger or continuously install two stages of circulating heat exchangers as cooling means for cooling water and gas to be treated without using cold water. However, since the gas to be treated containing the high-boiling solvent discharged from the factory has a large air volume, the introduction of the gas / gas heat exchanger is not realistic both physically and systematically. Also, it is not preferable to install a circulation heat exchanger in two stages because it is difficult to dissipate heat to the outside of the system, and the temperature of the circulation heat medium rises and the system may fail.

JP-A-9-173758

  An object of the present invention is to provide a solvent recovery device that recovers the high-boiling point solvent at low cost and efficiently from a gas to be treated containing the high-boiling point solvent discharged from a factory or the like.

  The solvent recovery apparatus of the present invention includes a circulating heat exchanger that primarily cools a gas to be treated containing a vapor of a high boiling solvent having a boiling point of 150 ° C. or higher, and a secondary gas that is treated with cold water after the primary cooling. A cooling recovery unit comprising a cooler for cooling, and the adsorbent absorbs the vapor of the high-boiling-point solvent remaining in the gas to be treated after cooling in the cooling recovery unit, and the solvent is removed from the gas to be treated. And the adsorbing / recovering unit for separating and recovering the gas, and the circulating heat exchanger that primarily cools the gas to be treated uses outside air for cooling the circulating refrigerant.

  The solvent recovery apparatus of the present invention is a solvent recovery apparatus characterized in that the temperature of the gas to be treated cooled by the cooling recovery section and introduced into the adsorption recovery section is 20 ° C. or less.

  Moreover, the solvent recovery apparatus of the present invention uses the circulating heat exchanger that primarily cools the gas to be treated as a first heat exchanger, and the gas to be treated before being primarily cooled by the first heat exchanger. The second heat exchanger cools the gas to be treated with the treated gas processed by the cooling recovery unit and the adsorption recovery unit. It is a solvent recovery device.

  In the present invention, a circulation heat exchanger is used for primary cooling of a gas to be treated which is discharged from a factory and contains a vapor of a high boiling point solvent having a boiling point of 150 ° C. or higher. The outside air is used as it is for cooling the circulation refrigerant of the circulation heat exchanger. Thus, even when the gas to be treated is at a high temperature or has a large air volume, the gas to be treated is sufficiently primary without requiring a large amount of cold water to cool the refrigerant for circulation of the heat exchanger. Can be cooled. Therefore, the high boiling point solvent in the gas to be treated can be appropriately cooled and recovered.

  As a result, the gas to be treated after cooling and recovery is introduced into the adsorption and recovery unit in a state where the residual solvent concentration is low. Accordingly, the residual solvent can be effectively recovered even in the adsorption recovery unit.

  Since the present invention does not use cold water for the primary cooling heat exchanger, the amount of cold water required for cooling recovery can be reduced as compared with the case where the entire amount of the gas to be treated is cooled with cold water. In particular, since the heat exchanger uses outside air as it is, primary cooling can be performed quickly and effectively when it is operated at night or in winter when the outside air temperature is low. In that case, the amount of cold water required for secondary cooling can be further reduced.

  The primary cooling does not require a cooling tower for continuously supplying cold water to the heat exchanger, and has a simple device configuration that can be operated only by the heat exchanger and a blower fan for introducing outside air as it is. Therefore, it is maintenance-free compared to the conventional apparatus, and the operating cost for cooling the gas to be processed can be reduced.

  Furthermore, by pre-cooling the gas to be treated before the primary cooling with a heat exchanger in advance, the solvent recovery by the cooling recovery unit can be performed more quickly. When the low-temperature treated gas from which the solvent has been recovered through the adsorption recovery unit is used for heat exchange of the heat exchanger used for the pre-cooling, rapid cooling recovery can be performed while maintaining low cost.

  In the present invention, when the hot air used for heat exchange becomes necessary in the production facility, it can be supplied and used effectively without being discharged outside the system.

  As described above, the present invention can efficiently perform solvent recovery combining cooling recovery and adsorption recovery at low cost without requiring a large amount of cold water.

It is a flow sheet which shows an example of the solvent recovery device of the present invention. It is a flow sheet which shows an example of the conventional solvent recovery device. It is a flow sheet which shows an example of a solvent recovery device which provided a cooler for outside temperature control.

  The solvent recovery apparatus of the present invention includes a circulating heat exchanger that primarily cools a gas to be treated containing a vapor of a high boiling solvent having a boiling point of 150 ° C. or higher, and a secondary gas that is treated with cold water after the primary cooling. A cooling recovery unit comprising a cooler for cooling, and the adsorbent absorbs the vapor of the high-boiling-point solvent remaining in the gas to be treated after cooling in the cooling recovery unit, and the solvent is removed from the gas to be treated. The circulation heat exchanger that primarily cools the gas to be treated uses outside air for cooling the circulation refrigerant.

  The gas to be treated (the gas to be treated) of the solvent recovery apparatus of the present invention contains a high-boiling solvent in air or an inert gas. The high boiling point solvent contained in the gas to be treated and suitably recovered in the present invention is an organic solvent having a boiling point of 150 ° C. or higher, preferably 150 to 300 ° C., for example, NMP, cyclohexanone, N, N-dimethyl. Examples include formamide (DMF), N, N-dimethylacetamide (DMAc), and the like.

  The cooling recovery unit uses a circulation type heat exchanger that performs primary cooling using the outside air as it is for cooling the circulating gas for the gas to be processed, and cold water for the gas to be processed after the primary cooling. An embodiment composed of a cooler that performs secondary cooling is preferred.

  It is also preferable to pre-cool the gas to be treated before the primary cooling because it facilitates rapid cooling and recovery. Since the processed gas from which the solvent has been recovered in the cooling recovery unit and the adsorption recovery unit is at a low temperature, the target gas before the primary cooling is further cooled by pre-cooling by heat exchange using the processed gas. Cost reduction can be achieved.

  The temperature of the gas to be treated after the primary cooling is preferably 20 to 40 ° C, more preferably 20 to 30 ° C, and further preferably 20 to 25 ° C.

  The refrigerant for circulation of the circulation heat exchanger varies depending on the operating conditions and environment, and examples thereof include alternative chlorofluorocarbon, methanol, ammonia, and pure water. Among them, it is preferable to use alternative chlorofluorocarbons depending on characteristics such as ease of conversion between the gas and liquid phases, low surface tension in the liquid phase, chemical and thermal stability, and large specific gravity.

  As a cooling medium used for secondary cooling, it is preferable to use cold water of 2 to 10 ° C, and more preferably cold water of 5 to 7 ° C. As the cold water, it is preferable to use pure water or an ethylene glycol aqueous solution.

  The temperature of the gas to be treated after the secondary cooling is preferably 20 ° C. or lower. If the temperature of the gas to be processed before being introduced into the adsorption recovery unit after the secondary cooling is higher than 20 ° C., the cooling recovery cannot be performed properly, and the concentration of the gas to be processed cannot be sufficiently reduced. For this reason, the adsorption efficiency to the adsorbent tends to decrease.

  The system of the adsorption / recovery device used in the adsorption / recovery unit is not particularly limited, but it is preferable to use, for example, a rotary organic solvent vapor adsorption device disclosed in JP-A-9-173758.

  The adsorption / recovery unit of the apparatus is formed in a cylindrical shape and is rotatable around a cylindrical axis. The cylindrical shaft is arranged in the supply direction of the gas to be treated, and a circular end surface perpendicular to the cylindrical shaft is radially divided by a casing and a heat-resistant seal around the axial point of the cylindrical shaft. Yes. Each of the divided zones is an adsorption zone, a regeneration zone, and a cooling zone. In the adsorption zone, the solvent contained in the gas to be treated is adsorbed and recovered with an adsorbent. In the regeneration zone, the adsorbent is regenerated by desorbing the solvent adsorbed on the adsorbent with high-temperature heated air. The cooling zone cools the adsorbent heated by the regeneration process.

  Examples of the adsorbent used include hydrophobic zeolite, activated carbon, activated carbon fiber, silica gel, activated alumina and the like. Of these, hydrophobic zeolite is preferable. Hydrophobic zeolite can be regenerated at high temperature due to its nonflammability and high heat resistance, and can be treated with a solvent having high thermal polymerization properties such as cyclohexanone because it is inert.

  The adsorption / recovery section divided into the adsorption zone, the regeneration zone, and the cooling zone continuously rotates around the cylindrical axis. By this rotation, the supply of the gas to be processed and the supply of the processed gas are alternately performed according to each zone, and the adsorption process, the regeneration process, and the cooling process can be performed continuously. Below, the structure of the adsorption | suction collection | recovery part of a rotary solvent adsorption | suction apparatus is demonstrated.

  In the adsorption zone, the high boiling point solvent is adsorbed and recovered by passing the gas to be treated after cooling and recovery. When the adsorption recovery unit rotates, the part of the adsorption recovery unit that has adsorbed and recovered the high boiling point solvent moves from the adsorption zone to the regeneration zone. A part of the processed gas that has passed through the adsorption zone is supplied to the regeneration zone in a heated state. The portion moved to the regeneration zone of the adsorption recovery unit is subjected to regeneration treatment by desorbing the adsorbed high-boiling point solvent by supplying heated treated gas. When the adsorption recovery unit further rotates, the regenerated portion moves from the regeneration zone to the cooling zone. A part of the processed gas that has passed through the adsorption zone is supplied to the cooling zone. The portion moved to the cooling zone of the adsorption / recovery unit is cooled by supplying the treated gas, and the adsorption process can be performed again. When the adsorption recovery unit further rotates, the cooled part moves from the cooling zone to the adsorption zone again. Thus, the adsorption recovery unit of the present invention can continuously perform the adsorption process, the regeneration process, and the cooling process.

  As the treated gas supplied to the regeneration zone or the cooling zone, 1/10 to 1/3 of the treated gas is preferably used. When supplying the treated gas to the regeneration zone, it is preferable to heat the treated gas to 100 to 200 ° C. by a heat exchanger using steam or the like and supply it to the regeneration zone in order to improve the desorption efficiency of the solvent. .

  The temperature of the treated gas after passing through the cooling zone to cool the adsorbent is increased by heat exchange with the adsorbent. Therefore, when it uses as a gas supplied to a regeneration zone continuously, the steam load of the heat exchanger at the time of supplying gas to a regeneration zone can be reduced.

  In the regeneration zone, the organic solvent adsorbed by the adsorbent in the adsorption zone is desorbed with heated air having a flow rate smaller than the flow rate of the gas to be treated. By this operation, desorption exhaust gas containing a high-boiling solvent at a higher concentration than the gas to be treated can be obtained. The concentration ratio X of the high boiling point solvent vapor by adsorption / desorption on the apparatus is determined by the ratio of the gas flow rate V to be processed and the desorption gas flow rate v per unit time, and there is a relationship of X = V / v. Usually, the apparatus constant and operating conditions are selected so that the concentration ratio is about 5-15.

  When the rotary organic solvent vapor adsorption apparatus is used in the present invention, the preferred size of the regeneration zone and the cooling zone is the type and concentration of the organic solvent contained in the gas to be treated, the adsorption / desorption characteristics of the adsorbent used, and the desired concentration. Although it varies depending on the magnification, the rotational speed of the rotor, etc., usually, about 1/10 to 1/3 of the area ratio is used for the regeneration zone, and if it has a cooling zone, this is about the same as the regeneration zone or about 1/2. It is preferable to do this.

  Further, in the heat exchanger, when the hot air used for heat exchange becomes necessary in the production facility, it can be supplied and used as it is without being discharged outside the system.

The present invention will be described in more detail with reference to the drawings. However, this is merely an example and does not limit the present invention.
[Example]
FIG. 1 shows an example of a flow sheet of the solvent recovery apparatus of the present invention.
<Pre-cooling>
The to-be-processed gas G1 discharged | emitted from production processes, such as a factory, contains 2000 ppm NMP at 900 Nm < ³ > / min and 130 degreeC. The gas to be processed G1 is cooled to about 50 ° C. by heat exchange with the processed gas G2 (T1). The treated gas G2 is a gas that is discharged from the adsorption recovery unit 20 and returned to the production process by the second heat exchanger 31.
<< Cooling recovery >>
<Primary cooling>
After pre-cooling, the gas to be treated G1 discharged from the second heat exchanger 31 is primarily cooled to about 20 to 40 ° C. (varies depending on the outside air temperature) by heat exchange in the first heat exchanger 11 (T2). ). The first heat exchanger 11 introduces the outside air A by the fan 12, and uses the introduced outside air A as it is for cooling the circulating refrigerant of the first heat exchanger 11.
<Secondary cooling>
The to-be-treated gas G1 after the primary cooling is secondarily cooled to 18 ° C. in the cooler 13 using cold water as a cooling medium (T3). NMP contained in the gas to be treated G1 after the secondary cooling was about 400 ppm.

In this cooling recovery unit that combines primary cooling and secondary cooling, the amount of cooling water used in one hour is only 32 m ³ used in the cooler 13 (annual average value because it varies depending on the outside air temperature). No cooling water was used.
<< Adsorption recovery >>
The treated gas G1 after the secondary cooling is sent to the adsorption zone of the adsorption recovery unit 20 (rotary solvent adsorption device 21) using zeolite as an adsorbent to further remove the remaining NMP, and the NMP is separated and recovered. The The amount of NMP remaining in the treated gas G2 after the adsorption recovery process was 20 ppm or less.
<< After adsorption recovery >>
A part of the treated gas G2 after the adsorption recovery is introduced into the cooling zone of the adsorption recovery unit 20 (rotary adsorption device 21) and used as a cooling medium. The temperature of the processed gas G <b> 2 is increased by heat exchange in the cooling process of the adsorption recovery unit 20. The treated gas G2 whose temperature has risen is introduced into the heat exchanger 22 using steam as a heating medium and heated to 140 ° C. in order to be used for the regeneration process. The heated treated gas G2 is adsorbed and recovered as heated air for desorbing the adsorbent of the adsorption recovery unit 20 (rotary solvent adsorbing device 21) (gas for desorbing the solvent absorbed by the adsorbent). 20 (rotary adsorption recovery device 21) is introduced into the regeneration zone.

  The gas G3 containing the solvent after desorbing the solvent from the adsorbent merges with the gas to be treated G1 before the primary cooling. The high boiling point solvent is recovered from the combined gas by cooling recovery and adsorption recovery.

Another part of the treated gas G2 after the adsorption recovery is used as a cooling medium for the second heat exchanger 31 when the gas to be treated is precooled, and then returned to the production process.
[Comparative Example 1]
FIG. 2 shows an example of a flow sheet of a conventional solvent recovery apparatus. According to FIG. 2, the primary cooling in the apparatus is performed by heat exchange using cooling water, and the outside air A is not used.
<Pre-cooling>
The to-be-processed gas G1 discharged | emitted from production processes, such as a factory, contains 2000 ppm NMP at 900 Nm < ³ > / min and 130 degreeC. The gas G1 to be treated is cooled to about 50 ° C. by heat exchange between the treated gas G2 and the second heat exchanger 31 (T1). The treated gas G2 is a gas that is discharged from the adsorption recovery unit 20 and returned to the production process.
<< Cooling recovery >>
<Primary cooling>
After pre-cooling, the gas G1 discharged from the second heat exchanger 31 is cooled to about 40 ° C. by heat exchange in the primary cooler 14 (T4). The cooling medium used in the primary cooler 14 is cooling water continuously supplied from the cooling tower.
<Secondary cooling>
The to-be-treated gas G1 after the primary cooling is cooled to 18 ° C. using the cold water as a cooling medium in the secondary cooler 13 ′ (T5). NMP contained in the gas to be treated G1 after the secondary cooling was about 400 ppm.

In the cooling recovery unit of Comparative Example 1, the amount of cooling water and cold water used for 1 hour was 47 m ³ of cooling water used in the primary cooler 14, and the cold water used in the secondary cooler 13 ′. Was 72 m ³ (annual average because it fluctuates depending on the outside temperature). Compared with the examples, cooling water is required, and the amount of cooling water is twice or more, which requires a great operating cost.
<< Adsorption recovery >>
The treated gas G2 after the secondary cooling is sent to the adsorption zone of the adsorption recovery unit 20 (rotary solvent adsorption device 21) using zeolite as an adsorbent to further remove the remaining NMP, and the NMP is separated and recovered. The The amount of NMP remaining in the treated gas G2 after the adsorption recovery process was 20 ppm or less.
<< After adsorption recovery >>
A part of the treated gas G2 after the adsorption recovery is introduced into the cooling zone of the adsorption recovery unit 20 (rotary adsorption device 21) and used as a cooling medium. The temperature of the processed gas G <b> 2 is increased by heat exchange in the cooling process of the adsorption recovery unit 20. The treated gas G2 whose temperature has risen is introduced into the heat exchanger 22 using steam as a heating medium and heated to 140 ° C. in order to be used for the regeneration process. The heated treated gas G2 is adsorbed and recovered as heated air for desorbing the adsorbent of the adsorption recovery unit 20 (rotary solvent adsorbing device 21) (gas for desorbing the solvent absorbed by the adsorbent). 20 (rotary adsorption recovery device 21) is introduced into the regeneration zone.

  The gas G3 containing the solvent after desorbing the solvent from the adsorbent merges with the gas to be treated G1 before the primary cooling. The high boiling point solvent is recovered from the combined gas by cooling recovery and adsorption recovery.

Another part of the treated gas G2 after the adsorption recovery is used as a cooling medium for the second heat exchanger 31 when the gas to be treated is precooled, and then returned to the production process.
[Comparative Example 2]
FIG. 3 shows an example of a flow sheet of a solvent recovery apparatus in which the cooler 15 is provided for adjusting the outside air temperature. According to FIG. 3, the cooling recovery in the apparatus is performed only once. The heat exchanger (first heat exchanger) 11 used for the cooling uses the outside air A adjusted in temperature by the cooler 15 for cooling the circulating refrigerant.
<Pre-cooling>
The to-be-processed gas G1 discharged | emitted from production processes, such as a factory, contains 2000 ppm NMP at 900 Nm < ³ > / min and 130 degreeC. The gas G1 to be treated is cooled to about 50 ° C. by heat exchange between the treated gas G2 and the second heat exchanger 31 (T1). The treated gas G2 is a gas that is discharged from the adsorption recovery unit 20 and returned to the production process.
<< Cooling recovery >>
After pre-cooling, the gas G1 discharged from the second heat exchanger 31 is cooled to about 22 ° C. by heat exchange in the first heat exchanger 11 (T6). The first heat exchanger 11 uses the outside air A whose temperature has been adjusted by the cooler 15 to cool the circulating refrigerant. The cooling medium of the cooler 15 is cold water. NMP contained in the gas to be treated G1 after cooling was about 480 ppm.
<< Adsorption recovery >>
The gas to be treated G1 after cooling is sent to the adsorption zone of the adsorption recovery unit 20 (rotary solvent adsorption device 21) using zeolite as an adsorbent to further remove remaining NMP, and NMP is separated and recovered. The amount of NMP remaining in the treated gas G1 after the adsorption recovery treatment was 20 ppm or more.

The first heat exchanger 11 of the solvent recovery apparatus of Comparative Example 2 has a limit in cooling the gas G1 to be processed to about 22 ° C. due to its performance. As a result, the apparatus could not properly recover the cooling, and the gas concentration introduced into the adsorption recovery unit 20 (rotary solvent adsorption apparatus 21) was too high (about 480 ppm). Therefore, the solvent recovery apparatus of Comparative Example 2 was not sufficient in solvent purification performance as compared with the Example of the present invention.
<< After adsorption recovery >>
A part of the treated gas G2 after the adsorption recovery is introduced into the cooling zone of the adsorption recovery unit 20 (rotary adsorption device 21) and used as a cooling medium. The temperature of the processed gas G <b> 2 is increased by heat exchange in the cooling process of the adsorption recovery unit 20. The treated gas G2 whose temperature has risen is introduced into the heat exchanger 22 using steam as a heating medium and heated to 140 ° C. in order to be used for the regeneration process. The heated treated gas G2 is adsorbed and recovered as heated air for desorbing the adsorbent of the adsorption recovery unit 20 (rotary solvent adsorbing device 21) (gas for desorbing the solvent absorbed by the adsorbent). 20 (rotary adsorption recovery device 21) is introduced into the regeneration zone.

  The gas G3 containing the solvent after desorbing the solvent from the adsorbent merges with the gas to be treated G1 before the primary cooling. The high boiling point solvent is recovered from the combined gas by cooling recovery and adsorption recovery.

  Another part of the treated gas G2 after the adsorption recovery is used as a cooling medium for the second heat exchanger 31 when the gas to be treated is precooled, and then returned to the production process.

10 cooling recovery unit, 11 (first) heat exchanger, 12 fans, 13 cooler,
13 'secondary cooler, 14 primary cooler, 15 cooler, 20 adsorption recovery unit,
21 rotary solvent adsorption device, 22 heat exchanger, 31 (second) heat exchanger,
G1 Gas to be treated, G2 Processed gas, G3 Gas containing solvent A Outside air

Claims (3)

A circulation type heat exchanger that primarily cools a gas to be treated containing a vapor of a high boiling point solvent having a boiling point of 150 ° C. or higher, and a cooler that secondarily cools the gas to be treated after the primary cooling with cold water. A cooling recovery unit,
An adsorption recovery unit that absorbs the vapor of the high boiling point solvent remaining in the gas to be treated after cooling in the cooling recovery unit by an adsorbent, and separates and recovers the solvent from the gas to be processed.
The solvent recovery apparatus according to claim 1, wherein the circulating heat exchanger that primarily cools the gas to be treated uses outside air for cooling the circulating refrigerant.   2. The solvent recovery apparatus according to claim 1, wherein the temperature of the gas to be treated that is cooled by the cooling recovery unit and introduced into the adsorption recovery unit is 20 ° C. or less. . The solvent recovery apparatus according to claim 1 or 2, wherein the circulating heat exchanger that primarily cools the gas to be treated is a first heat exchanger,
A second heat exchanger for cooling the gas to be treated before being primarily cooled by the first heat exchanger;
Said 2nd heat exchanger cools this to-be-processed gas with the processed gas processed by the said cooling recovery part and the said adsorption | suction recovery part, The solvent recovery apparatus characterized by the above-mentioned.

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