Solvent recovery device

Abstract

The invention provides a solvent recovery device which reduces the energy required for heating desorption gas for desorbing a solvent. This solvent recovery device is provided with: a cooling and recovering device to which untreated gas is supplied and which cools and condenses solvent vapor contained in the untreated gas; an adsorption concentrator to which a primary treated gas obtained by cooling and condensing the solvent vapor of the untreated gas in the cooling and recovering device is supplied; an adsorption rotor provided in the adsorption concentrator and having an adsorption region for adsorbing uncondensed solvent vapor contained in the primary treatment gas and a desorption region for desorbing the solvent vapor adsorbed in the adsorption region; a desorption gas supply path for supplying the untreated gas to the desorption region; and a desorption exhaust path that exhausts a concentrated gas containing the solvent vapor desorbed from the desorption region to the cooling recoverer.

Description

Technical Field

[0001] This disclosure relates to a solvent recovery apparatus that utilizes a cooling recovery unit to condense and recover volatile solvents. Background Technology

[0002] Patent document 1 discloses a solvent recovery device that does not require a cooler that uses cooling water to cool the gas being processed. Existing technical documents Patent documents

[0003] Patent Document 1: Japanese Patent Application Publication No. 2014-87746 Summary of the Invention The technical problem that the invention aims to solve

[0004] The purpose of this disclosure is to reduce the energy required for heating the desorbed gas to desorb the solvent from the adsorbent that has adsorbed the solvent in a solvent recovery device that recovers volatile solvent by condensing it through a cooling recovery unit. Solutions for solving technical problems

[0005] The solvent recovery apparatus disclosed herein comprises: a cooling recovery unit for cooling and condensing solvent vapors contained in an untreated gas; an adsorption concentrator supplied with a primary treated gas obtained by cooling and condensing the solvent vapors of the untreated gas in the cooling recovery unit; an adsorption rotor disposed in the adsorption concentrator, having an adsorption region for adsorbing uncondensed solvent vapors contained in the primary treated gas and a desorption region for desorbing the solvent vapors adsorbed in the adsorption region; a desorption gas supply path for supplying the untreated gas to the desorption region; and a desorption exhaust path for discharging concentrated gas containing solvent vapors desorbed from the desorption region back to the cooling recovery unit.

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

[0007] By employing this disclosure, in a solvent recovery apparatus that recovers volatile solvents by condensing them using a cooling recovery unit, the energy required for heating the desorbed gas used to desorb the solvent from the adsorbent containing the solvent can be reduced. Attached Figure Description

[0008] Figure 1 This is a schematic diagram showing the general structure of the solvent recovery apparatus according to the first embodiment. Figure 2 This is a schematic diagram illustrating a variation of the first embodiment. Figure 3 This is a schematic diagram showing the general structure of the solvent recovery apparatus according to the second embodiment. Figure 4 This is a schematic diagram illustrating a variation of the second embodiment. Figure 5 This is a schematic diagram showing the general structure of the solvent recovery apparatus according to the third embodiment. Figure 6 This is a block diagram showing the hardware structure of the control unit. Figure 7 This is a flowchart illustrating the functions of the control unit. Figure 8 This is a schematic diagram illustrating a variation of the third embodiment. Detailed Implementation

[0009] Hereinafter, an example of an embodiment for implementing the technology of this disclosure will be described in detail with reference to the accompanying drawings. It should be noted that sometimes, for constituent elements and processes that perform the same actions, functions, or effects, the same reference numerals are used in all the drawings, and repeated descriptions are appropriately omitted. The drawings are only schematically illustrated to a degree that allows a thorough understanding of the technology of this disclosure. Therefore, the technology of this disclosure is not limited to the illustrated examples. Furthermore, in this embodiment, descriptions of structures not directly related to the technology of this disclosure or of well-known structures are sometimes omitted.

[0010] (1) First implementation method Figure 1This is a schematic diagram showing the general structure of the solvent recovery apparatus 1 according to the first embodiment. The solvent recovery apparatus 1 of this embodiment includes: a primary exhaust path 100, which discharges untreated gas containing solvent vapor generated in production step 5; a cooling recovery unit 10, which is supplied with the untreated gas from the primary exhaust path 100 and cools and condenses the solvent vapor contained in the untreated gas; a primary exhaust path 110, which discharges primary treated gas obtained after cooling and condensing the solvent vapor of the untreated gas in the cooling recovery unit 10; an adsorption concentrator 20, which is supplied with the primary treated gas from the primary exhaust path 110; an adsorption rotor 21, which is disposed in the adsorption concentrator 20 to adsorb uncondensed solvent vapor contained in the primary treated gas; and an adsorption zone 22, which is disposed inside the adsorption concentrator 20 to adsorb the primary treated gas. The adsorption region 23, which is partitioned with the adsorption region 22 and located inside the adsorption concentrator 20, uses a desorption gas at a higher temperature than the primary treated gas to heat and desorb the solvent vapor adsorbed in the adsorption region 22; a secondary exhaust path 120 discharges the secondary treated gas obtained after adsorption treatment of the primary treated gas in the adsorption region 22; a desorption gas supply path 130 branches off from the original exhaust path 100 and supplies a portion of the untreated gas as the desorption gas to the desorption region 23; and a desorption exhaust path 140 discharges the concentrated gas obtained in the desorption region 23 containing the solvent vapor desorbed from the adsorption rotor 21 to the cooling recovery unit 10.

[0011] That is, the solvent recovery apparatus 1 of this embodiment includes: a cooling recovery unit 10, which is supplied with untreated gas and cools and condenses the solvent vapor contained in the untreated gas; an adsorption concentrator 20, which is supplied with a primary treated gas obtained by cooling and condensing the solvent vapor of the untreated gas in the cooling recovery unit 10; an adsorption rotor 21, which is disposed in the adsorption concentrator 20 and has an adsorption region 22 for adsorbing uncondensed solvent vapor contained in the primary treated gas and a desorption region 23 for desorbing the solvent vapor adsorbed in the adsorption region 22; a desorption gas supply path 130, which supplies the untreated gas to the desorption region 23; and a desorption exhaust path 140, which discharges concentrated gas containing solvent vapor desorbed from the desorption region 23 to the cooling recovery unit 10.

[0012] Furthermore, the solvent recovery apparatus 1 of this embodiment also includes a heat exchanger 50, which exchanges heat between the higher-temperature untreated gas in the original exhaust path 100 and the lower-temperature secondary treated gas in the secondary exhaust path 120. That is, the solvent recovery apparatus 1 of this embodiment also includes a heat exchanger 50, which exchanges heat between the untreated gas supplied to the cooling recovery unit 10 and the secondary treated gas.

[0013] The untreated gas containing solvent vapor generated in production step 5 is supplied to the cooling recovery unit 10 by the original exhaust blower 101 through the original exhaust path 100 and the cooling supply path 105. A desorption gas supply path 130 branches off from the original exhaust path 100, through which a portion of the untreated gas is supplied as desorbed gas to the adsorption concentrator 20, as will be described below. The untreated gas supplied to the cooling recovery unit 10 from the original exhaust path 100 is cooled between the heat exchanger 50 and the secondary treated gas flowing in the secondary heating path 170 (described below). The cooled untreated gas is then supplied to the cooling recovery unit 10 through the cooling supply path 105. Additionally, a concentrated gas containing a relatively high concentration of solvent vapor is supplied from the adsorption concentrator 20 (described below) to the cooling recovery unit 10 through the desorption exhaust path 140.

[0014] In the cooling recovery unit 10, the untreated gas supplied from the original exhaust path 100 is cooled by a built-in precooler 11, primary cooler 12, and secondary cooler 13. The precooler 11 supplies cooling capacity by allowing refrigerant to flow between itself and the gas supply preheater 40, which will be described below. Cooling capacity is supplied to the primary cooler 12 and secondary cooler 13 by allowing refrigerant to flow between them and an external heat source via primary refrigerant flow path 12a and secondary refrigerant flow path 13a, respectively. As the untreated gas is cooled inside the cooling recovery unit 10, the contained solvent vapors condense and liquefy, and are recovered as a liquid organic solvent from the solvent recovery path 14.

[0015] The untreated gas from which solvent vapors have been recovered in the cooling recovery unit 10, along with the concentrated gas (described below), becomes the primary treated gas, which is supplied to the adsorption concentrator 20 by the primary exhaust blower 111 through the primary exhaust path 110. The adsorption concentrator 20 houses a disc-shaped adsorption rotor 21, which is a structure carrying adsorbent and having an air gap. The adsorption rotor 21 is positioned perpendicular to the flow direction of the primary treated gas inside the adsorption concentrator 20. The interior of the adsorption concentrator 20 is divided into two isolated regions: a larger adsorption region 22 and a smaller desorption region 23. While the adsorption rotor 21 rotates around its axis inside the adsorption concentrator 20, residual solvent vapors from the primary treated gas at a lower temperature are adsorbed onto the adsorption rotor 21 in the adsorption region 22, and in the desorption region 23, the adsorbed solvent vapors are heated and desorbed from the adsorption rotor 21 using a desorption gas at a higher temperature than the primary treated gas.

[0016] Through the desorption gas supply path 130, which branches off from the original exhaust path 100, the untreated gas, while maintaining a high temperature, is supplied as desorption gas by the desorption blower 131 to the desorption zone 23 of the adsorption concentrator 20 without passing through the heat exchanger 50. In the desorption zone, since the adsorption rotor 21 is exposed to the high-temperature desorption gas, the adsorbed solvent vapors are desorbed and mixed into the desorption gas, thereby forming a concentrated gas with a higher concentration of solvent vapors. As described above, the concentrated gas is supplied to the cooling recovery unit 10 through the desorption exhaust path 140, and the contained solvent vapors are recovered as liquid organic solvents. Here, although the desorption gas contains a relatively high concentration of solvent vapors, it is not saturated, so it does not prevent the further inclusion of desorbed solvent vapors. In addition, desorbing solvent vapors from the adsorption rotor 21 requires the desorption gas to be heated to a high temperature, but in this embodiment, the originally high-temperature untreated gas is used almost directly as the desorption gas, so there is no need to heat the desorption gas, which reduces the energy required for heating.

[0017] In the adsorption concentrator 20, the primary processed gas is concentrated by the adsorption of solvent vapor, and the resulting secondary processed gas, with a significantly reduced concentration of solvent vapor, is discharged from the downstream secondary exhaust path 120. A portion of the secondary processed gas is released to the outside through the release path 150. The secondary processed gas that is not released to the outside through the release path 150 is sent to the gas supply preheater 40 for heating by the heating blower 161 via the primary heating path 160. In the gas supply preheater 40, while supplying cooling energy to the precooler 11 of the aforementioned cooling recovery unit 10, the secondary processed gas is heated using the heat energy supplied from the precooler 11. The heated secondary processed gas is further heated by heat exchange with the original exhaust gas flowing in the aforementioned original exhaust path 100 through the secondary heating path 170 and the heat exchanger 50. The secondary processed gas is heated in the heat exchanger 50 and sent to the production process 5 via the gas supply path 180.

[0018] For example, in process 5 of a lithium-ion battery manufacturing plant, N-methylpyrrolidone is generated as a solvent vapor. This is illustrated in Table 1 below.

[0019] [Table 1]

[0020] In the original exhaust path 100, the raw exhaust gas with a solvent concentration of 2000 ppm at 120°C is cooled to 70°C by heat exchanger 50 and then reaches the cooling recovery unit via cooling supply path 105. On the other hand, in the desorption gas supply path 130, which branches off from the original exhaust path 100, the desorbed gas with a solvent concentration of 2000 ppm at 100°C becomes concentrated gas with a solvent concentration of 2600 ppm at 60°C in the desorption zone 23 of the adsorption concentrator 20, and then reaches the cooling recovery unit 10 via desorption exhaust path 140. The cooled raw exhaust gas and concentrated gas become primary treated gas, cooled to 12°C and with a solvent concentration reduced to 200 ppm by the cooling recovery unit 10, and then reach the primary exhaust path 110.

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

[0022] It should be noted that, in this embodiment, as Figure 2As shown in the modified example, the structure can also be configured such that a cooling zone 24, isolated from the desorption zone 23 and the adsorption zone 22, is provided between the internal desorption zone 23 and the adsorption zone 22 of the adsorption concentrator 20. In this cooling zone 24, a portion of the cooled primary processing gas supplied from the primary exhaust path 110 is used to cool the adsorption rotor 21, which has been heated in the desorption zone 23, thereby allowing the adsorption rotor 21 to be used again for the adsorption of solvent vapors in the adsorption zone 22. The primary processing gas, after being cooled in the cooling zone 24, is then supplied again from the adsorption concentrator 20 to the cooling recovery unit 10 via the cooling circulation path 147. That is, the adsorption rotor 21 may also have a cooling zone 24, which is disposed between the desorption zone 23 and the adsorption zone 22 and is supplied with the primary processing gas.

[0023] (2) Second implementation method Figure 3 This is a schematic diagram showing the general structure of the solvent recovery apparatus 1 according to the second embodiment. In addition to the structure of the solvent recovery apparatus 1 of the first embodiment, the solvent recovery apparatus 1 of this embodiment also includes a circulating gas supply path 190 that branches off downstream from the secondary exhaust path 120 and merges with the desorption gas supply path 130. By mixing the secondary treated gas from this circulating gas supply path 190 with the untreated gas from the desorption gas supply path 130, the solvent concentration in the desorbed gas and the concentrated gas can be reduced. It should be noted that in this embodiment, as... Figure 4 As shown in the modified example, it can also be configured such that a cooling region 24, isolated from the desorption region 23 and the adsorption region 22, is provided between the desorption region 23 and the adsorption region 22 inside the adsorption concentrator 20. The structure and significance of the cooling region 24 are the same as in the first embodiment described above. That is, the adsorption recovery device 1 of this embodiment also includes a circulating gas supply path 190, which supplies the secondary treated gas obtained after adsorption treatment of the primary treated gas in the adsorption region 22 to the desorption gas supply path 130.

[0024] (3) Third implementation method Figure 5This is a schematic diagram showing the general structure of the solvent recovery apparatus 1 according to the third embodiment. In addition to the structure of the solvent recovery apparatus 1 of the second embodiment, the solvent recovery apparatus 1 of this embodiment further includes: a concentration sensor 145 that measures the concentration of solvent vapor contained in the concentrated gas of the desorption exhaust path 140; a desorption gas supply valve 135 that opens and closes the desorption gas supply path 130; a recirculation gas supply valve 195 that opens and closes the recirculation gas supply path 190; and a control unit 200 that controls the opening and closing of the desorption gas supply valve 135 and the recirculation gas supply valve 195 based on the concentration measured by the concentration sensor 145. That is, the adsorption recovery device 1 of this embodiment further includes: a concentration sensor 145, which measures the concentration of solvent vapor in the desorption exhaust path 140; a desorption gas supply valve 135, which opens and closes the desorption gas supply path 130; a recirculation gas supply valve 195, which opens and closes the recirculation gas supply path 190; and a control unit 200, which controls the opening and closing of the desorption gas supply valve 135 and the recirculation gas supply valve 195 according to the concentration measured by the concentration sensor 145.

[0025] like Figure 6 As shown in the hardware structure, the control unit 200 includes a CPU (Central Processing Unit) 210, a ROM (Read Only Memory) 220, a RAM (Random Access Memory) 230, and a storage device 250. These components are connected to each other via a bus 290 in a manner that enables communication.

[0026] CPU 210 is a central processing unit that executes various programs that can be implemented by the installed application program, or controls various parts. That is, CPU 210 reads programs from ROM 220 or storage device 250 and uses RAM 230 as the working area to execute the programs. CPU 210 opens and closes the air supply valve 135 and the circulating air supply valve 195 according to the programs recorded in ROM 220 or storage device 250.

[0027] ROM 220 stores various programs and data. RAM 230 serves as a working area to temporarily store programs or data. Storage device 250 is configured as a memory based on HDD (Hard Disk Drive), SSD (Solid State Drive), or flash memory, storing various programs, including the operating system, and various data.

[0028] Reference Figure 7The flowchart illustrates a specific example of the function of the control unit 70. It should be noted that, in this example, the setpoint for the solvent concentration (C) in the desorption exhaust path 140 is set to T, and the lower limit of the setpoint range for the solvent concentration centered on T is set to T0. L Set the upper limit value to T. H If the solvent recovery device 1 is operating, the control unit 200 first opens the desorption gas supply valve 135 and closes the circulating gas supply valve 195 in the stage shown in S10. Then, in the stage shown in S20, if it is determined that the solvent concentration (C) detected by the concentration sensor 145 has not reached the lower limit value (T)... L During this period, the control unit 200 maintains the open state of the desorption air supply valve 135 and the closed state of the return air supply valve 195.

[0029] On the other hand, in the stage shown in S20, if it is determined that the solvent concentration (C) detected by the concentration sensor 145 is the lower limit value (T) L In the above steps, the control unit 200 opens the return gas supply valve 195 and the desorption gas supply valve 135 together in the stage shown in S30. As a result, the secondary processing gas is mixed with the untreated gas in the desorption gas supply path 130, thereby reducing the solvent concentration in the desorption gas supply path 130.

[0030] Next, in stage S40, the control unit 200 determines whether 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 in stage S20, the control unit 200 again determines whether the solvent concentration (C) detected by the concentration sensor 145 has reached the lower limit value (T). L ).

[0031] On the other hand, in stage S40, if the control unit 200 determines that the solvent concentration (C) detected by the concentration sensor 145 is above the set value (T), then in stage S50, it determines whether the solvent concentration (C) exceeds the upper limit value (T). H If the solvent concentration (C) is determined to be at the upper limit (T) H From here on, the desorption gas supply valve and the recirculation gas supply valve 195 remain open in the stage shown in S30.

[0032] On the other hand, in the stage shown in S50, if the control unit 200 determines that the solvent concentration (C) detected by the concentration sensor 145 exceeds the upper limit value (T)... HIf, in stage S60, the control unit 200 closes the desorption gas supply valve 135 and opens the recirculation gas supply valve 195, the supply of untreated gas to the desorption gas supply path 130 is cut off, and only secondary treated gas is supplied to the adsorption concentrator 20 through the desorption gas supply path 130. Then, in stage S50, if the solvent concentration (C) detected by the concentration sensor 145 is not at the upper limit value (T), H During the following period, the desorption gas supply valve 135 and the recirculation gas supply valve 195 are maintained in the closed state and open state respectively in the stage shown in S60.

[0033] Through the above, the solvent concentration of the concentrated gas in the desorption exhaust path 140, detected by the concentration sensor 145, is maintained at a lower limit value (T) centered on a set value T. L ) and upper limit (T) H Control within the range between ).

[0034] It should be noted that, in this embodiment, as Figure 8 As shown in the modified example, it can also be configured such that a cooling region 24, isolated from the desorption region 23 and the adsorption region 22, is provided between the desorption region 23 and the adsorption region 22 inside the adsorption concentrator 20. The structure and significance of the cooling region 24 are the same as in the first embodiment described above. Explanation of reference numerals in the attached figures

[0035] 1. Solvent recovery unit; 5. Production process 10 Cooling recovery unit 11 Precooler 12 Primary cooler 12a Primary refrigerant flow path; 13 Secondary cooler; 13a Secondary refrigerant flow path 14 Solvent Recovery Pathways 20 Adsorption concentrator 21 Adsorption rotor 22 Adsorption zone 23 Desorption Zone 24 Cooling Zone 40 Gas preheater 50 heat exchanger 100 Original exhaust path 101 Original exhaust blower 105 Cooling supply path 110 Primary exhaust path 111 Primary exhaust blower 120 Secondary Exhaust Path 130 Desorption air supply path; 131 Desorption blower; 135 Desorption air supply valve 140 Desorption exhaust path; 145 Concentration sensor; 147 Cooling circulation path 150 Release Path 160 Primary heating path 161 Heating blower 170 Secondary heating path 180 Gas supply path 181 Gas supply blower 190 Circulating air supply path 195 Circulating air supply valve 200 Control Unit 210 CPU 220 ROM 230 RAM, 250 storage devices, 290 bus.

Claims

1. A solvent recovery device, comprising: A cooling recovery unit is supplied with untreated gas and cools and condenses the solvent vapor contained in the untreated gas. An adsorption concentrator is supplied with primary treated gas obtained by cooling and condensing the solvent vapor of the untreated gas in the cooling recovery unit. An adsorption rotor, disposed in the adsorption concentrator, has an adsorption region for adsorbing uncondensed solvent vapors contained in the primary treated gas, and a desorption region for desorbing the solvent vapors adsorbed in the adsorption region. A desorption gas supply path that supplies the untreated gas to the desorption area; as well as The desorption exhaust path discharges concentrated gas containing solvent vapors desorbed from the desorption region to the cooling recovery unit.

2. The solvent recovery device according to claim 1, wherein, The solvent recovery device also has a circulating gas supply path, which supplies the secondary treated gas obtained after the primary treated gas is adsorbed in the adsorption zone to the desorption gas supply path.

3. The solvent recovery device according to claim 2, wherein, The solvent recovery device also includes: A concentration sensor that measures the concentration of solvent vapor within the desorption exhaust path; Desorption gas supply valve, which opens and closes the desorption gas supply path; The recirculation gas supply valve opens and closes the recirculation gas supply path; and The control unit controls the opening and closing of the desorption gas supply valve and the circulating gas supply valve based on the concentration measured by the concentration sensor.

4. The solvent recovery device according to claim 2, wherein, The solvent recovery device also includes a heat exchanger that exchanges heat between the untreated gas supplied to the cooling recovery unit and the secondary treated gas.

5. The solvent recovery device according to claim 1, wherein, The adsorption rotor also has a cooling zone disposed between the desorption zone and the adsorption zone, which is supplied with the primary treatment gas.

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