Solvent recovery system

Abstract

This reduces the energy required to heat the desorption gas used to desorb the solvent. [Solution] A solvent recovery apparatus comprising: a cooling recovery unit to which untreated gas is supplied and solvent vapor contained in the untreated gas is cooled and condensed; an adsorption concentrator to which primary treated gas obtained by cooling and condensing the solvent vapor of the untreated gas in the cooling recovery unit is supplied; an adsorption rotor provided in the adsorption concentrator and having an adsorption region for adsorbing uncondensed solvent vapor contained in the primary treated gas and a desorption region for desorbing the solvent vapor adsorbed in the adsorption region; a desorption supply passage for supplying the untreated gas to the desorption region; and a desorption exhaust passage for discharging concentrated gas containing solvent vapor desorbed from the desorption region to the cooling recovery unit.

Description

[Technical Field]

[0001] This disclosure relates to a solvent recovery apparatus that recovers volatile solvents by condensing them using a cooling recovery device. [Background technology]

[0002] Patent Document 1 discloses a solvent recovery system that does not require a cooler to cool the gas to be treated using cooling water. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2014-87746 [Overview of the project] [Problems that the invention aims to solve]

[0004] In a solvent recovery system that recovers volatile solvents by condensing them using a cooling recovery unit, the objective is to reduce the energy required to heat the desorption gas used to desorb the solvent from the adsorbent that has adsorbed the solvent. [Means for solving the problem]

[0005] A solvent recovery apparatus according to one aspect of the present disclosure comprises: a cooling recovery unit in which solvent vapor contained in an untreated gas is cooled and condensed; an adsorption concentrator to which a primary treated gas, obtained by cooling and condensing the solvent vapor of the untreated gas in the cooling recovery unit, is supplied; an adsorption rotor provided in the adsorption concentrator and having an adsorption region in which uncondensed solvent vapor contained in the primary treated gas is adsorbed and a desorption region in which the solvent vapor adsorbed on the adsorption region is desorbed; a desorption supply passage in which the untreated gas is supplied to the desorption region; and a desorption exhaust passage in which a concentrated gas containing the solvent vapor desorbed from the desorption region is discharged to the cooling recovery unit.

[0006] According to this embodiment, since a portion of the untreated gas originating from the production process is used as the desorption gas, there is no need to heat the desorption gas. [Effects of the Invention]

[0007] According to this disclosure, in a solvent recovery apparatus that recovers volatile solvents by condensing them using a cooling recovery device, it is possible to reduce the energy required to heat the desorption gas used to desorb the solvent from the adsorbent on which the solvent has been adsorbed. [Brief explanation of the drawing]

[0008] [Figure 1] This is a schematic diagram showing the general configuration of the solvent recovery apparatus according to the first embodiment. [Figure 2] This is a schematic diagram showing a modified example of the first embodiment. [Figure 3] This is a schematic diagram showing the general configuration of the solvent recovery apparatus of the second embodiment. [Figure 4] This is a schematic diagram showing a modified example of the second embodiment. [Figure 5] This is a schematic diagram showing the general configuration of the solvent recovery apparatus of the third embodiment. [Figure 6] Block diagram showing the hardware configuration of the control unit. [Figure 7] This is a flowchart explaining the functions of the control unit. [Figure 8] This is a schematic diagram showing a modified example of the third embodiment. [Modes for carrying out the invention]

[0009] Hereinafter, an example of an embodiment for carrying out the technology of this disclosure will be described in detail with reference to the drawings. Components and processes that perform similar operations, functions, and roles will be given the same reference numerals throughout the drawings, and redundant explanations may be omitted as appropriate. Each drawing is only a schematic representation to the extent that the technology of this disclosure can be fully understood. Therefore, the technology of this disclosure is not limited to the illustrated examples. Furthermore, in this embodiment, explanations of configurations not directly related to the technology of this disclosure or well-known configurations may be omitted.

[0010] (1) First Embodiment Figure 1 is a schematic diagram showing the general configuration of the solvent recovery apparatus 1 of the first embodiment. The solvent recovery apparatus 1 of this embodiment includes a raw exhaust passage 100 from which untreated gas containing solvent vapor generated in the production process 5 is discharged, a cooling recovery unit 10 to which the untreated gas is supplied from the raw exhaust passage 100 and the solvent vapor contained in the untreated gas is cooled and condensed, a primary exhaust passage 110 from which primary treated gas obtained by cooling and condensing the solvent vapor of the untreated gas in the cooling recovery unit 10 is discharged, an adsorption concentrator 20 to which the primary treated gas is supplied from the primary exhaust passage 110, an adsorption rotor 21 provided inside the adsorption concentrator 20 to adsorb uncondensed solvent vapor contained in the primary treated gas, and a device arranged inside the adsorption concentrator 20 that flows the primary treated gas through the adsorption rotor 21 to remove the solvent vapor The device comprises an adsorption region 22 where gas adsorption processing takes place, a desorption region 23 located inside the adsorption concentrator 20 and separated from the adsorption region 22, where solvent vapor adsorbed in the adsorption region 22 is heated and desorbed by a desorption gas at a higher temperature than the primary processing gas, a secondary exhaust passage 120 through which the secondary processing gas, in which the primary processing gas has been adsorbed in the adsorption region 22, is discharged, a desorption supply passage 130 branching off from the primary exhaust passage 100, to which a portion of the unprocessed gas is supplied to the desorption region 23 as the desorption gas, and a desorption exhaust passage 140 through which concentrated gas, in which solvent vapor desorbed from the adsorption rotor 21 is contained in the desorption gas in the desorption region 23, is discharged to the cooling recovery device 10.

[0011] That is, the solvent recovery device 1 of the present embodiment includes a cooling recovery unit 10 to which untreated gas is supplied and in which solvent vapor contained in the untreated gas is cooled and condensed, an adsorption concentrator 20 to which the primary treated gas in which the solvent vapor of the untreated gas is cooled and condensed in the cooling recovery unit 10 is supplied, an adsorption rotor 21 provided in the adsorption concentrator 20 and having an adsorption region 22 in which uncondensed solvent vapor contained in the primary treated gas is adsorbed and a desorption region 23 in which the solvent vapor adsorbed in the adsorption region 22 is desorbed, a desorption air supply passage 130 through which the untreated gas is supplied to the desorption region 23, and a desorption exhaust passage 140 through which the concentrated gas containing the solvent vapor desorbed from the desorption region 23 is discharged to the cooling recovery unit 10.

[0012] Further, the solvent recovery device 1 of the present embodiment further includes a heat exchanger 50 that performs heat exchange between the hotter untreated gas in the raw exhaust passage 100 and the cooler secondary treated gas in the secondary exhaust passage 120. That is, the solvent recovery device 1 of the present embodiment further includes a heat exchanger 50 that performs heat exchange between the untreated gas supplied to the cooling recovery unit 10 and the secondary treated gas.

[0013] The untreated gas containing the solvent vapor generated in the production process 5 is supplied to the cooling recovery unit 10 by the raw exhaust blower fan 101 through the raw exhaust passage 100 and the cooling supply passage 105. A desorption air supply passage 130 branches from the raw exhaust passage 100, and a part of the untreated gas is supplied as desorption gas to the adsorption concentrator 20 through this desorption air supply passage 130, which will be described later. The untreated gas supplied from the raw exhaust passage 100 to the cooling recovery unit 10 is cooled through the heat exchanger 50 with the secondary treated gas flowing through a secondary heating passage 170 described later. The cooled untreated gas is supplied to the cooling recovery unit 10 through the cooling supply passage 105. The cooling recovery unit 10 is also supplied with a concentrated gas containing a relatively high-concentration solvent vapor from the adsorption concentrator 20 through the desorption exhaust passage 140 described later.

[0014] In the cooling and recovery device 10, the untreated gas supplied from the raw exhaust gas passage 100 is cooled by the built-in pre-cooler 11, primary cooler 12, and secondary cooler 13. The pre-cooler 11 supplies cold heat by circulating a refrigerant between it and the air supply pre-heater 40, which will be described later. The primary cooler 12 and secondary cooler 13 supply cold heat by circulating a refrigerant between them and an external heat source through the primary refrigerant flow path 12a and secondary refrigerant flow path 13a, respectively. As the untreated gas is cooled inside the cooling and recovery device 10, the contained solvent vapor is condensed and liquefied, and is recovered as a liquid organic solvent through the solvent recovery path 14.

[0015] The untreated gas from which the solvent vapor has been recovered by the cooling and recovery device 10 and the concentrated gas, which will be described later, become the primary treated gas and are supplied to the adsorption concentrator 20 through the primary exhaust passage 110 by the primary exhaust blower fan 111. The adsorption concentrator 20 incorporates a disk-shaped adsorption rotor 21 composed of a structure having a ventilation gap carrying an adsorbent. The adsorption rotor 21 is provided inside the adsorption concentrator 20 perpendicular to the flow path direction of the primary treated gas. The inside of the adsorption concentrator 20 is partitioned into two mutually isolated regions: a relatively large-volume adsorption region 22 and a relatively small-volume desorption region 23. While the adsorption rotor 21 rotates around its axis inside the adsorption concentrator 20, the solvent vapor remaining in the relatively low-temperature primary treated gas in the adsorption region 22 is adsorbed by the adsorption rotor 21, and the solvent vapor adsorbed in the desorption region 23 is heated and desorbed from the adsorption rotor 21 by the desorption gas that is hotter than the primary treated gas.

[0016] Through the desorption supply air passage 130, which branches off from the aforementioned original exhaust passage 100, the untreated gas is supplied to the desorption region 23 of the adsorption concentrator 20 as desorbed gas by the desorption fan 131, without passing through the heat exchanger 50, while maintaining a high temperature. In the desorption region, the adsorption rotor 21 is exposed to the high-temperature desorption gas, causing the adsorbed solvent vapor to desorb and mix with the desorption gas to become a concentrated gas with a higher concentration of solvent vapor. As described above, the concentrated gas is supplied to the cooling recovery unit 10 through the desorption exhaust passage 140, where the contained solvent vapor is recovered as a liquid organic solvent. Here, although the desorption gas contains a relatively high concentration of solvent vapor, it has not reached a saturated state, so it can contain even more desorbed solvent vapor. Furthermore, while it is necessary to heat the desorption gas to a high temperature for desorption of solvent vapor from the adsorption rotor 21, in this embodiment, the originally high-temperature untreated gas is used almost as is as the desorption gas, so there is no need to heat the desorption gas, and the energy required for heating can be reduced.

[0017] In the adsorption concentrator 20, the primary treatment gas undergoes adsorption and concentration of solvent vapor, and is discharged from the downstream secondary exhaust passage 120 as a secondary treatment gas with a significantly reduced solvent vapor concentration. A portion of the secondary treatment gas is released to the outside through the discharge passage 150. The secondary treatment gas that is not released to the outside through the discharge passage 150 is sent to the supply air preheater 40 via the primary heating passage 160 by the heated air blower fan 161 and heated. In this supply air preheater 40, while supplying cold energy to the precooler 11 of the cooling and recovery unit 10 mentioned above, the secondary treatment gas is heated by the heat supplied from the precooler 11. The heated secondary treatment gas is further heated through the secondary heating passage 170 and the heat exchanger 50, where it is heated by heat exchange with the original exhaust flowing through the original exhaust passage 100 mentioned above. The secondary treatment gas is heated in the heat exchanger 50 and sent to the production process 5 via the supply air passage 180.

[0018] For example, in production process 5 of a lithium-ion battery manufacturing plant, N-methylpyrrolidone is generated as solvent vapor. In this case, the gas temperature and solvent concentration in each flow path in Figure 1 are as shown in Table 1 below.

[0019] [Table 1]

[0020] In the original exhaust passage 100, the original exhaust gas, with a temperature of 120°C and a solvent concentration of 2,000 ppm, is cooled to 70°C via the heat exchanger 50 and then reaches the cooled recovery unit via the cooled supply passage 105. Meanwhile, in the desorption supply passage 130 branched from the original exhaust passage 100, the desorbed gas, with a temperature of 100°C and a solvent concentration of 2,000 ppm, passes through the desorption region 23 of the adsorption concentrator 20 to become a concentrated gas with a temperature of 60°C and a solvent concentration of 2,600 ppm, and then reaches the cooled recovery unit 10 via the desorption exhaust passage 140. The cooled original exhaust gas and concentrated gas pass through the cooled recovery unit 10 to become a primary treated gas, with its temperature reduced to 12°C and its solvent concentration reduced to 200 ppm, and then reaches the primary exhaust passage 110.

[0021] The primary treatment gas passes through the adsorption concentrator 20, where the solvent concentration is reduced to 10 ppm at a temperature of 15°C, becoming the secondary treatment gas. It is then heated to 45°C in the supply air preheater 40, further heated to 90°C in the heat exchanger 50, and supplied again to the production process 5.

[0022] In this embodiment, as shown in the modified example in Figure 2, a cooling region 24 may be provided inside the adsorption concentrator 20 between the desorption region 23 and the adsorption region 22, and isolated from the desorption region 23 and the adsorption region 22. In this cooling region 24, the adsorption rotor 21 heated in the desorption region 23 is cooled by a portion of the cooled primary treatment gas supplied from the primary exhaust passage 110, and is then used again for adsorption of solvent vapor in the adsorption region 22. The primary treatment gas that has cooled the adsorption rotor 21 in the cooling region 24 is supplied again to the cooling recovery unit 10 from the adsorption concentrator 20 via the cooling recirculation passage 147. That is, the adsorption rotor 21 may be positioned between the desorption region 23 and the adsorption region 22 and further have a cooling region 24 to which the primary treatment gas is supplied.

[0023] (2) Second Embodiment Figure 3 is a schematic diagram showing the general configuration of the solvent recovery device 1 of the second embodiment. The solvent recovery device 1 of this embodiment further includes a recirculating air supply passage 190 that branches off from downstream of the secondary exhaust passage 120 and merges with the desorption supply passage 130, in addition to the configuration of the solvent recovery device 1 of the first embodiment. By mixing the secondary processed gas from this recirculating air supply passage 190 with the unprocessed gas in the desorption supply passage 130, the solvent concentration in the desorbed gas and concentrated gas can be reduced. In this embodiment as well, as shown in the modified example in Figure 4, a cooling area 24 may be provided inside the adsorption concentrator 20 between the desorption area 23 and the adsorption area 22, and is isolated from the desorption area 23 and the adsorption area 22. The structure and significance of the cooling area 24 are the same as in the first embodiment described above. That is, the adsorption recovery device 1 of this embodiment further includes a recirculating air supply passage 190 that supplies the secondary processed gas, from which the primary processed gas has been adsorbed in the adsorption area 22, to the desorption supply passage 130.

[0024] (3) Third Embodiment Figure 5 is a schematic diagram showing the general configuration of the solvent recovery device 1 of the third embodiment. The solvent recovery device 1 of this embodiment further includes, in addition to the configuration of the solvent recovery device 1 of the second embodiment, a concentration sensor 145 for measuring the concentration of solvent vapor contained in the concentrated gas of the desorption exhaust passage 140, a desorption supply valve 135 for opening and closing the desorption supply passage 130, a recirculation supply valve 195 for opening and closing the recirculation supply passage 190, and a control unit 200 for controlling the opening and closing of the desorption supply valve 135 and the recirculation supply valve 195 according to the concentration measured by the concentration sensor 145. In other words, the adsorption recovery device 1 of this embodiment further comprises a concentration sensor 145 for measuring the concentration of solvent vapor in the desorption exhaust passage 140, a desorption supply valve 135 for opening and closing the desorption supply passage 130, a recirculation supply valve 195 for opening and closing the recirculation supply passage 190, and a control unit 200 for controlling the opening and closing of the desorption supply valve 135 and the recirculation supply valve 195 according to the concentration measured by the concentration sensor 145.

[0025] As shown in the hardware configuration of Figure 6, the control unit 200 includes a CPU (Central Processing Unit) 210, ROM (Read Only Memory) 220, RAM (Random Access Memory) 230, and storage device 250. Each component is connected to the others via a bus 290 so that they can communicate with each other.

[0026] The CPU 210 is the central processing unit and executes various programs that can be implemented as installed applications, as well as controlling various parts. Specifically, the CPU 210 reads programs from the ROM 220 or storage device 250 and executes them using the RAM 230 as the working area. The CPU 210 opens and closes the detachable air supply valve 135 and the recirculating air supply valve 195 according to the program recorded in the ROM 220 or storage device 250.

[0027] ROM220 stores various programs and data. RAM230 temporarily stores programs or data as a working area. Storage device250 is configured as storage using an HDD (Hard Disk Drive), SSD (Solid State Drive), or flash memory, and stores various programs, including the operating system, and various data.

[0028] A specific example of the function of the control unit 70 will be explained with reference to the flowchart in Figure 7. In this example, the set value of the solvent concentration (C) in the detachable exhaust passage 140 is T, and the lower limit of the set range of solvent concentration centered on T is T. L and the upper limit is T H The control unit 200, upon activation of the solvent recovery device 1, first opens the detachable air supply valve 135 and closes the recirculation air supply valve 195 in the step shown in S10. Then, in the step shown in S20, when the solvent concentration (C) detected by the concentration sensor 145 reaches the lower limit (T) L As long as it determines that the condition has not been reached, the control unit 200 maintains the open state of the detachable air supply valve 135 and the closed state of the recirculating air supply valve 195.

[0029] On the other hand, in the stage shown in S20, when it is determined that the solvent concentration (C) detected by the concentration sensor 145 is equal to or higher than the lower limit value (T L ), the control unit 200 opens the reflux air supply valve 195 together with the desorption air supply valve 135 in the stage shown in S30. As a result, the secondary treated gas is mixed with the untreated gas in the desorption air supply passage 130 to reduce the solvent concentration in the desorption air supply passage 130.

[0030] Next, in the stage shown in S40, the control unit 200 determines whether or not the solvent concentration (C) detected by the concentration sensor 145 has reached the set value (T). If it is determined that the solvent concentration (C) has not reached the set value (T), then again in the stage shown in S20, the control unit 200 determines whether or not the solvent concentration (C) detected by the concentration sensor 145 has reached the lower limit value (T L ).

[0031] On the other hand, in the stage shown in S40, when the control unit 200 determines that the solvent concentration (C) detected by the concentration sensor 145 is equal to or higher than the set value (T), in the stage shown in S50, it is determined whether or not the solvent concentration (C) has exceeded the upper limit value (T H ). If it is determined that the solvent concentration (C) is equal to or lower than the upper limit value (T H ), the open states of both the desorption air supply valve and the reflux air supply valve 195 in the stage shown in S30 are maintained.

[0032] On the other hand, in the stage shown in S50, when the control unit 200 determines that the solvent concentration (C) detected by the concentration sensor 145 has exceeded the upper limit value (T H ), the control unit 200 closes the desorption air supply valve 135 and opens the reflux air supply valve 195 in the stage shown in S60. As a result, the supply of the untreated gas to the desorption air supply passage 130 is blocked, and only the secondary treated gas is supplied to the adsorption concentrator 20 through the desorption air supply passage 130. And, as long as the solvent concentration (C) detected by the concentration sensor 145 in the stage shown in S50 does not become lower than the upper limit value (T H ), the closed state of the desorption air supply valve 135 and the open state of the reflux air supply valve 195 in the stage shown in S60 are maintained.

[0033] Based on the above, the solvent concentration of the concentrated gas in the detachable exhaust passage 140, as detected by the concentration sensor 145, is set to a lower limit (T) centered around the set value (T). L ) and upper limit (T H Control is implemented to maintain the value within the range between )

[0034] In this embodiment as well, as shown in the modified example in Figure 8, a cooling region 24 may be provided inside the adsorption concentrator 20 between the desorption region 23 and the adsorption region 22, and isolated from the desorption region 23 and the adsorption region 22. The structure and significance of the cooling region 24 are the same as in the first embodiment described above. [Explanation of symbols]

[0035] 1. Solvent recovery system 5. Production process 10 Cooling recovery unit 11 Pre-cooler 12 Primary cooler 12a Primary refrigerant flow path 13 Secondary cooler 13a Secondary refrigerant flow path 14 Solvent recovery route 20 Adsorption concentrator 21 Adsorption rotor 22 Adsorption area 23 Desorption area 24 Cooling area 40 Air supply preheater 50 heat exchanger 100 Main exhaust passage 101 Main exhaust fan 105 Cooling supply passage 110 Primary exhaust passage 111 Primary exhaust fan 120 Secondary exhaust passage 130 Detachable air intake passage 131 Detachable blower fan 135 Detachable air intake valve 140 Detachable exhaust path 145 Concentration sensor 147 Cooling circulation path 150 Release channel 160 Primary heating path 161 Heating fan 170 Secondary heating path 180 Air intake passage 181 Air intake fan 190 Return air supply path 195 Return air supply valve 200 Control Unit 210 CPU 220 ROM 230 RAM, 250 storage devices, 290 buses

Claims

1. A cooling and recovery unit into which untreated gas is supplied and the solvent vapor contained in the untreated gas is cooled and condensed, The cooling and recovery unit is supplied with an adsorption concentrator to which a primary treated gas is obtained by cooling and condensing the solvent vapor of the untreated gas, An adsorption rotor is provided in the adsorption concentrator and has an adsorption region where uncondensed solvent vapor contained in the primary treatment gas is adsorbed and a desorption region where the solvent vapor adsorbed in the adsorption region is desorbed. A desorption supply passage through which the untreated gas is supplied to the desorption region, A desorption exhaust passage through which concentrated gas containing solvent vapor desorbed from the desorption region is discharged to the cooling recovery unit, A solvent recovery device equipped with a solvent recovery system.

2. The solvent recovery apparatus according to claim 1, further comprising a recirculating air supply passage for supplying the secondary processed gas, which has been treated by adsorption of the primary processed gas in the adsorption region, to the desorption air supply passage.

3. A concentration sensor for measuring the concentration of solvent vapor in the detachable exhaust passage, A detachable air supply valve that opens and closes the aforementioned detachable air supply passage, A recirculating air supply valve that opens and closes the aforementioned recirculating air supply passage, A control unit that controls the opening and closing of the detachable air supply valve and the recirculating air supply valve according to the concentration measured by the concentration sensor, The solvent recovery apparatus according to claim 2, further comprising:

4. The solvent recovery apparatus according to claim 2, further comprising a heat exchanger that performs heat exchange between the untreated gas supplied to the cooling recovery unit and the secondary treated gas.

5. The solvent recovery apparatus according to claim 1, wherein the adsorption rotor further comprises a cooling region disposed between the desorption region and the adsorption region, to which the primary processing gas is supplied.

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