JP5600048B2 - Solvent recovery device - Google Patents

Description

  The present invention relates to a solvent recovery apparatus.

  In production facilities involving chemical treatment, solvent vapor is included in the exhausted gas. As a technique for recovering such solvent vapor, for example, a technique in which the solvent vapor is condensed and adsorbed on an adsorbent has been proposed (see Patent Document 1).

JP 2010-69435 A Japanese Patent Laid-Open No. 5-15725 JP 2008-180459 A JP 2009-66578 A JP-A-2005-103378

  In order to condense the solvent vapor contained in the gas, it is necessary to flow cooling water or a refrigerant in the tube of the coil disposed in the flow path through which the gas flows. In this case, examples of the cold heat source include a refrigerator and a cooling tower. Here, in the case of a refrigerator, a large amount of power is required in the compressor to perform an expansion and compression cycle, whereas in the case of a cooling tower, cooling is performed by heat exchange with the atmosphere and the action of heat of vaporization. It only needs the power of auxiliary equipment such as a pump. For this reason, when cooling the gas containing the solvent vapor, using the cooling tower as a cooling heat source as much as possible leads to a reduction in running cost.

  However, since the temperature of the cooling water supplied from the cooling tower can be reduced only to the outside temperature in principle, when cooling the gas, the cooling water is simply first cooled with the cooling water from the cooling tower, and then If only cooling is performed with the cooling medium from the refrigerator, the running cost cannot be further reduced.

  This invention is made | formed in view of such a problem, and makes it a subject to provide the solvent collection | recovery apparatus which reduces the thermal load of a refrigerator as much as possible, and suppresses running cost.

  In order to solve the above-mentioned problem, the present invention cascades a coil in which cooling water from a cooling tower flows in a pipe on the downstream side and the upstream side of a first cooler having a coil in which a cooling medium from a refrigerator flows in the pipe. Arranged. The path through which the cooling water from the cooling tower flows first passes through the coil installed on the downstream side of the first cooler, and then passes through the coil installed on the upstream side of the first cooler. The structure to do is taken.

Specifically, it is a solvent recovery device for recovering a solvent from a gas containing a solvent vapor, the cooling medium cooled in a refrigeration facility contacting the gas with a coil flowing in a pipe, and the solvent vapor contained in the gas A first cooler that condenses the cooling water, a heater that heats the gas that has passed through the first cooler in contact with a coil in which cooling water supplied from the cooling tower flows in the pipe, and the cooling tower. A second cooler that cools by contacting the gas before flowing into the first cooler with a coil in which the cooling water supplied and passed through the coil of the coil of the heater flows in the tube.

  Said cooling medium is the liquid or gas which conveys the cold produced by the refrigeration equipment, for example, water, brine, refrigerant gas etc. can be illustrated. When recovering the solvent from the gas containing the solvent vapor, it is not necessary to adjust the temperature of the gas. Therefore, it is not necessary to discharge the gas cooled for the purpose of condensing the solvent vapor at a constant temperature.

  Here, if the temperature of the cooling medium flowing through the coil of the first cooler is lower than at least the cooling water supplied from the cooling tower, the gas after passing through the first cooler is supplied from at least the cooling tower. Therefore, if the cooling water from the cooling tower is allowed to flow into the tube of the coil that performs heat exchange with the gas, the cooling water from the cooling tower is further cooled with cooling ( When viewed from the passing gas, since the temperature rises downstream of this coil, this coil acts as a heating coil). The cooling water having a temperature lower than that of the cooling water immediately after exiting the cooling tower is caused to flow into the tube of the coil of the second cooler arranged on the upstream side of the first cooler. The temperature of the gas flowing into the vessel is lowered to a temperature lower than the outdoor temperature where the cooling tower is located.

  As a result, the heat load of the refrigeration equipment that supplies the cooling medium to the first cooler is greatly reduced compared to the case where the cooling water from the cooling tower is simply passed through the coil disposed upstream of the first cooler. It becomes possible to do. Thereby, it becomes possible to reduce the thermal load of a refrigerator as much as possible, and to suppress running cost.

  The cooling water flowing in the coil of the heater and the coil of the second cooler is a water circulation path passing through the cooling tower, and passes through the heater from the cooling tower and then the second cooling water. It may circulate through a water circulation path that returns to the cooling tower again through a vessel. By configuring the solvent recovery device in this way, even if the temperature of the gas sent from a higher-level device than the solvent recovery device is high, the second cooler or the heater deviates from an appropriate temperature range. The operation state of the solvent recovery device can be maintained without any trouble.

  Moreover, the said solvent collection | recovery apparatus may further be equipped with the adsorption collection part which adsorb | sucks the solvent vapor | steam in the said gas which passed the said heater with adsorption material. By configuring the solvent recovery device in this way, the gas exhausted from the solvent recovery device can be reliably supplied even if solvent vapor that has not been condensed by the first cooler or the second cooler remains. It is possible to purify.

  If it is the said solvent collection | recovery apparatus, it is possible to reduce the thermal load of a refrigerator as much as possible, and to suppress running cost.

It is a block diagram of a solvent collection | recovery apparatus. It is the graph which showed NMP saturation concentration. It is a block diagram of a general solvent collection | recovery apparatus. It is the figure which expanded the condensation collection | recovery part of the solvent collection | recovery apparatus which concerns on a modification.

  FIG. 1 shows the configuration of a solvent recovery apparatus according to an embodiment of the present invention. As shown in FIG. 1, the solvent recovery apparatus 1 includes a condensation recovery unit 2 that condenses and recovers a solvent by cooling a predetermined gas containing solvent vapor (hereinafter simply referred to as gas) with a coil, and a condensation recovery unit 2. An adsorption / recovery unit 3 is provided that adsorbs and recovers a solvent remaining in the gas that has passed through an adsorbent such as zeolite or activated carbon. Moreover, the solvent collection | recovery apparatus 1 is provided with the coil which performs the various fan which heats gas, and heat exchange.

The solvent recovery apparatus 1 is an apparatus that recovers solvent vapor in exhaust gas exhausted from production facilities that perform various chemical treatments with an organic solvent. In the present embodiment, description will be made on the assumption that NMP is recovered from production exhaust gas containing solvent vapor of N-methylpyrrolidone (hereinafter referred to as NMP) used in a lithium ion battery factory. Also good. In lithium ion battery factories, NMP is used when manufacturing electrodes. The NMP applied to the electrode is evaporated and exhausted by a dryer (referred to here as a drying processing furnace). The solvent recovery apparatus 1 is an apparatus that is attached to the building where the dryer is installed, and recovers the solvent vapor in the exhaust of the dryer. In this embodiment, the assumed concentration of the solvent vapor exhausted from the dryer is 2000 ppm. The exhaust of the dryer has an air volume of 200 to 1000 Nm ³ / min and a temperature of 80 to 10
0 ° C. is assumed, but in the following description, the air volume is 480 Nm ³ / min and the temperature is 9
Set to 7 ° C. The cooling water used in the solvent recovery device 1 is that of an air conditioning facility generated by a cooling tower that cools the heat generating part of the production device in a building where the production facility is installed. Hereinafter, in the present embodiment, the configuration and operation of the solvent recovery device 1 will be described on the assumption that the solvent recovery device 1 is installed in a building in which cooling water of two types of temperature zones is circulated as cooling water for air conditioning. .

  Here, the cooling water in the two types of temperature zones is cooling water cooled by a cooling tower installed outdoors and cooling water cooled by a refrigerator (may be referred to as cold water). Although the former depends on the outside air temperature, the design temperature is set to 32 ° C., and hence the cooling water cooled by the cooling tower is hereinafter referred to as 32 ° C. cooling water. On the other hand, since the latter is cooling water cooled to 7 ° C. by the refrigerator, the cooling water cooled by the refrigerator is hereinafter referred to as 7 ° C. cooling water. The power required for producing the 32 ° C. cooling water is much smaller than the power required for producing the 7 ° C. cooling water using the heat pump. It is effective in reducing the power consumed by the whole.

  The condensation collection | recovery part 2 has four heat exchange coils (code | symbols 4-7) arranged in series, as shown in FIG. Hereinafter, in order from the upstream side, the precooler 4, the precooler 5 (corresponding to the second cooler referred to in the present invention), and the main cooler 6 (corresponding to the first cooler referred to in the present invention). The post heater 7 (corresponding to the heater in the present invention) will be referred to.

The precooler 4 is connected to a preheater 8 provided on the downstream side of the fan 15A for supplying outside air to the dryer via a water circulation system 9. In addition, the solvent recovery apparatus 1 includes a fan 15 </ b> B that feeds the gas mixed with the remaining solvent vapor that is cooled and condensed to the adsorption rotor 13, which will be described later, and a fan 15 </ b> C for regenerating the adsorption function of the adsorption rotor 13. Design air volume of each fan, the fan 15A is 450 Nm ³ / min, a fan 15B is 534 nm ³ / min, the fan 15C is 54Nm ³ / min. The precooler 4 cools the gas sent from the dryer. The heat of the gas removed by the precooler 4 is transferred to the preheater 8 by the water circulating in the water circulation system 9 by the circulation pump 19, heated by the adsorption recovery unit 3 and again sent to the dryer. . The 97 ° C. gas flowing into the precooler 4 reaches 63 ° C. and is sent to the precooler 5. In addition, the enclosing number shown in FIG. 1 has shown the temperature of the gas of each site | part.

  In the water circulation system 9, the pressure in the circulation system is higher than atmospheric pressure (for example, if the gauge pressure is 0.2 MPa, the saturated steam temperature is 133.7 ° C., and if it is below this temperature, it will not boil), Even if the temperature of the gas sent from the dryer becomes high, the water in the system does not boil. The pressure in the water circulation system 9 is kept constant by the accumulator.

  The precooler 5 further cools the gas cooled by the precooler 4. The precooler 4 cools the gas with the cooling water of the 32 ° C. cooling water circulation system 11 having a cooling tower in the path. The 63 ° C. gas flowing into the precooler 5 reaches 27 ° C. and is sent to the main cooler 6.

  The main cooler 6 further cools the gas cooled by the pre-cooler 5. The main cooler 6 cools the gas with the cooling water of the 7 ° C. cooling water circulation system 12 having a refrigerator in the path. The main cooler 6 cools the 27 ° C. gas sent from the precooler 5 to 12 ° C. The flow rate of the cooling water passing through the main cooler 6 is adjusted by the flow rate adjusting valve 10 that controls the temperature so that the temperature of the gas on the downstream side of the main cooler 6 becomes 12 ° C. When the gas sent from the dryer is cooled to 12 ° C. by the main cooler 6, NMP vapor is condensed on the surface of the cooling coil of the main cooler 6.

  FIG. 2 is a graph showing the NMP saturation concentration. In the condensation recovery unit 2, when the gas containing the solvent vapor passes through the precooler 4 and reaches 63 ° C., the concentration of the solvent vapor reaches about 2000 ppm, and when the gas passes through the precooler 5 and reaches 27 ° C. The concentration of the solvent vapor becomes about 800 ppm, and when it passes through the main cooler 6 and reaches 12 ° C., the concentration of the solvent vapor becomes about 270 ppm.

  The post heater 7 heats the gas cooled by the main cooler 6. The post heater 7 heats the gas with the cooling water of the 32 ° C. cooling water circulation system 11 that requires a cooling tower in the path. The post heater 7 heats the 12 ° C. gas sent from the main cooler 6 to 27 ° C.

  Here, the cooling water of the 32 ° C. cooling water circulation system 11 follows the following path. That is, the cooling water cooled in the cooling tower passes through the post heater 7 after leaving the cooling tower, and then returns to the cooling tower through the pre cooler 5 again. Since the temperature of the gas flowing into the post heater 7 is 12 ° C., the 32 ° C. cooling water flowing into the post heater 7 becomes 17 ° C. after passing through the post heater 7 and flows into the pre cooler 5. To do. Since the temperature of the gas flowing into the precooler 5 is 63 ° C., the cooling water flowing into the precooler 5 becomes 53 ° C. after passing through the precooler 5 and is sent again to the cooling tower. In addition, since the cooling tower provided in the 32 degreeC cooling water circulation system 11 is integrated and operated with the cooling tower of another production facility, the 53 degreeC cooling water sent to the cooling tower again cools the other production equipment. By mixing with water, the return temperature of the cooling water returning to the cooling tower is lower than 53 ° C.

  If it is the condensing collection part 2 comprised as mentioned above, much heat will be processed by the 32 degreeC cooling water circulation system 11. FIG. That is, when the cooling water of the 32 ° C. cooling water circulation system 11 is flowed to the pre-cooler 5 without passing through the post-heater 7, the gas that has passed through the pre-cooler 5 does not decrease to 27 ° C. The load of the refrigerator of the 7 degreeC cooling water circulation system 12 will increase. However, in the case of the condensing and collecting unit 2 according to the present embodiment, the post-heater 7 is made to flow by flowing the cooling water of the 32 ° C. cooling water circulation system 11 to the pre-cooler 5 through the post-heater 7. Since the cooling water cooled to 17 ° C. by passing through the pre-cooler 5, the gas flowing into the main cooler 6 can be cooled to 27 ° C. in advance.

  In the case of the solvent recovery device 1 according to the present embodiment, heat is effectively used in a cascade manner in the condensation recovery unit 2, and thus, for example, a 32 ° C. cooling water circulation system 11x as in the solvent recovery device 1x shown in FIG. The precooler 5x through which the cooling water flows through and the main cooler 6x through which the cooling water of the 7 ° C. cooling water circulation system 12x flow are arranged in order, and the precooler 4x and the main cooler 6x provided upstream of the precooler 5x. Compared with a general solvent recovery device in which the water in the water circulation system 9 flows through the post heater 7x provided on the downstream side, the heat load on the 7 ° C. cooling water circulation system 12 can be greatly reduced (estimated) Then, the running cost can be reduced by about 40%). That is, most of the heat processed in the condensing and recovering unit 2 is processed by the 32 ° C. cooling water circulation system 11 having much smaller power than the 7 ° C. cooling water circulation system 12, so that the entire solvent recovery device 1 is consumed. It is effective in reducing power. Further, since the cooling water of the 32 ° C. cooling water circulation system 11 is operated with a large temperature difference, the conveyance power for circulating the cooling water can be reduced.

  A certain amount of solvent is recovered by the condensation recovery unit 2, and the gas heated at the most downstream side is sent to the adsorption recovery unit 3 for further purification. As shown in FIG. 1, the adsorption recovery unit 3 includes an adsorption rotor 13 and a steam heating coil 14 and is configured as follows.

  The adsorption rotor 13 carries an adsorbent such as zeolite inside a cylindrical member. A section division cassette (not shown) is arranged on both end faces of the adsorption rotor 13, and the gas passage area of the adsorption rotor 13 is divided into three sections by this cassette. The suction rotor 13 is rotatable relative to the section division cassette, and a processing region R1, a regeneration region R2, and a purge region R3 are formed in the suction rotor 13 by this cassette.

  The 27 ° C. gas exiting the condensation recovery unit 2 sent by the fan 15B passes through the processing region R1. The processing region R1 adsorbs NMP in the gas to be vented and discharges the purified gas. Most of the gas exiting the processing region R1 exits the solvent recovery device 1 and joins with the outside air and is sent to the dryer. Further, part of the gas exiting the processing region R1 is sent to the purge region R3. Note that part or all of the gas exiting the processing region R1 may be exhausted outdoors.

  The purge region R3 is a region formed in the middle of the transition of the suction rotor 13 from the regeneration region R2 to the processing region R1 as the suction rotor 13 rotates relative to the section division cassette. The purge region R3 is a region for cooling the adsorbent that is in a high-temperature state immediately after regeneration and before in-service, and is cooled by passing a part of the gas exiting the processing region R1. As the suction rotor 13 rotates in the direction indicated by the arrow in FIG. 1, one point of the suction rotor 13 repeatedly changes in the order of the processing region R1, the regeneration region R2, and the purge region R3.

  The gas exiting the purge region R3 is heated by the steam heating coil 14 and then sent to the regeneration region R2. The steam heating coil 14 heats the gas with the steam of the boiler supplied from the utility pipe of the building where the solvent recovery device 1 is installed. Condensate in the steam heating coil 14 is returned again to the boiler water supply tank via the drain trap. The gas at 68 ° C. discharged from the purge region R3 becomes 130 ° C. by heating by the steam heating coil 14, and is sent to the regeneration region R2. As a result, the regeneration region R2 becomes high temperature, and the adsorbed solvent is released. The gas exiting the regeneration region R2 is sent again to the condensation recovery unit 2. As a result, most of the solvent separated from the adsorption rotor 13 by regenerative heating is condensed and recovered by the main cooler 6 of the condensation recovery unit 2. As described above, the heat exchange of the cooling water exiting the cooling tower of the 32 ° C. cooling water circulation system 11 with the gas exiting the main cooler 6 at the same temperature is the boiler that supplies the steam heating coil 14 with high heat. This contributes to a reduction in the load.

  Further, the precooler 4, the precooler 5, the main cooler 6, the postheater 7, and the fans 15 </ b> A, B, and C are accommodated below the condensation recovery unit 2 and the fans 15 </ b> A, B, and C. A drain pipe 16 and a drain tank 17 for collecting condensed NMP are connected to the casing. The NMP collected in the drain tank 17 is drained out of the system by a drain pump 20 that starts and stops by an electrode type level sensor 18 installed in the drain tank 17.

  The solvent recovery apparatus 1 may be modified as follows. FIG. 4 shows an enlarged view of the condensation recovery unit of the solvent recovery apparatus according to this modification. The condensation recovery unit 2 ′ of the solvent recovery apparatus according to this modification is provided with two precoolers and two postheaters each through which 32 ° C. cooling water flows. About another structure, it is the same as that of the said solvent collection | recovery apparatus 1. FIG. As shown in FIG. 4, the condensation recovery unit 2 ′ of the solvent recovery apparatus according to this modification includes a precooler 4, precoolers 5F and 5R, a main cooler 6, and postheaters 7F and 7R. The dryer gas that has flowed into the condensing and collecting unit 2 ′ passes through these heat exchange coils in order.

In the solvent recovery apparatus according to this modification, the cooling water in the 32 ° C. cooling water circulation system 11 ′ follows the following path. That is, the cooling water cooled by the cooling tower passes through the post-heater 7R after leaving the cooling tower, and is then sent to the pre-cooler 5F. The cooling water that has passed through the pre-cooler 5F is sent to the post-heater 7F, and then passes through the pre-cooler 5R and is then sent again to the cooling tower.

  In the case of the condensing and collecting unit 2 ′ configured as described above, most of the heat is processed by the 32 ° C. cooling water circulation system 11 ′. Therefore, most of the heat processed in the condensing and recovering unit 2 is processed by the 32 ° C. cooling water circulation system 11 ′, which has much lower power than the 7 ° C. cooling water circulation system 12 ′. Is effective in reducing the power consumed by In this modification, two precoolers and two postheaters are provided, but there may be three or more.

  Further, the solvent recovery apparatus 1 has a configuration in which the cooling water of the 7 ° C. cooling water circulation system 12 flows in the cooling coil of the main cooler 6, but the configuration in which the refrigerant gas depressurized by the heat pump of the refrigeration facility flows directly. It may be.

  In the solvent recovery apparatus 1, 7 ° C. cooling water flows in the cooling coil of the main cooler 6, and 32 ° C. cooling water supplied from the cooling tower to the pre-cooler 5 and the post-heater 7. However, the present invention is not limited to this mode, and the cooling water flowing in the cooling coil of the main cooler 6 is at least lower than the cooling water supplied from the cooling tower. Any temperature is acceptable.

  In the solvent recovery apparatus 1, the flow rate adjusting valve 10 is provided only in the 7 ° C. cooling water circulation system 12, but the 32 ° C. cooling water circulation system 11 may be provided with a flow rate adjusting valve. In this case, the flow rate adjusting valve provided in the 32 ° C. cooling water circulation system 11 controls, for example, the temperature of the gas that has passed through the cooler 5 or the post heater 7 to a predetermined control target value. If the circulation flow rate of the 32 ° C. cooling water circulation system 11 is controlled in this way, the conveyance power of the cooling water can be further reduced.

1. Solvent recovery device 2, 2 '... Condensation recovery part 3 ... Adsorption recovery part 4 ... Precooler 5, 5F, 5R ... Precooler 6 ... Main coolers 7, 7F, 7R ... -Post-heater 8-Preheater 9-Water circulation system 11, 11 '-32 ° C cooling water circulation system 12, 12'-7 ° C cooling water circulation system 13-Adsorption rotor

Claims (4)

A solvent recovery device for recovering a solvent from a gas containing solvent vapor,
A first cooler for bringing the gas into contact with a coil in which a cooling medium cooled in a refrigeration facility flows in a pipe, and condensing the solvent vapor contained in the gas;
The coil water cooled in the cooling tower flows through the tube, and pressurized heat heater the gas which has passed through the first cooler,
By a coil through the water pipe passing through the tubes of the coil is cooled the heater in the cooling tower, and a second cooler for cooling the gas prior to flowing said to first cooler,
Comprising
Solvent recovery device. The heater and the second pipe flow Ru water condenser coils is a water circulation path through the cooling tower, after a the heating unit from the cooling tower, the said second cooler Circulates through the water circulation path back to the cooling tower
The solvent recovery apparatus according to claim 1. An adsorption recovery unit for adsorbing the solvent vapor in the gas that has passed through the heater with an adsorbent;
The solvent recovery apparatus of Claim 1 or 2. The temperature of the cooling medium flowing through the coil of the first cooler is at least lower than the temperature of the water cooled in the cooling tower;
The solvent collection | recovery apparatus as described in any one of Claim 1 to 3.

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