Purification and dehydration system and process for organic solvent containing solid impurities

Abstract

The invention provides a purification and dehydration system and process for an organic solvent containing solid impurities. The purification and dehydration system comprises a flash separator, an elutriation leg, a circulating pump, a flash heater, a slurry pump, a filter, a rectifying tower, a reboiler, a tower top fractional condenser, a liquid discharge pump and membrane dehydration equipment. Solid impurities in the water-containing organic solvent are concentrated and separated through flash separation, solid-liquid separation is conducted through the filter, a large amount of solid impurities are discharged out of the system, a small amount of solid impurities and filtrate return to the flash separator, and the recovery rate of the organic solvent is increased; the water-containing organic solvent gas obtained after flash separation enters a rectifying tower, the solvent is purified until azeotropic composition of the solvent and water is achieved, the water exceeding the azeotropic composition is discharged out of a system through a tower bottom liquid discharging pump, and primary separation of the solvent and the water is achieved; azeotropic steam of solvent and water at the top of the rectifying tower enters membrane dehydration equipment for deep dehydration. Continuous and efficient production of purification and dehydration of the organic solvent containing solid impurities is realized through flash evaporation solid removal, rectification purification and membrane dehydration.

Description

Technical Field

[0001] The invention relates to the field of pharmaceutical chemicals, and in particular to a purification and dehydration system and process for an organic solvent containing solid impurities. Background Art

[0002] At present, organic solvents are usually heated and evaporated by stirring kettles. The organic solvents and water are gasified and taken out from the top of the kettle and then condensed. The solid impurities are discharged from the bottom of the kettle as kettle residue. This method can only be operated in batches and intermittently, and the subsequent dehydration and purification process requires secondary gasification. The organic solvent after the separation of solid impurities is usually dehydrated and purified by azeotropic distillation process. This method has high energy consumption because it requires a high reflux ratio and recovery of the entrainer, and will also introduce a small amount of entrainer impurities. It can also be directly dehydrated and purified by membrane dehydration equipment, but because of the high water content, the membrane area used is large, which will increase equipment investment. Summary of the invention

[0003] In order to overcome the above-mentioned defects, the present invention provides a system and process for purifying and dehydrating an organic solvent containing solid impurities. The equipment realizes continuous operation of solid-liquid separation through flash separation and elutriation, saving the energy consumption of secondary gasification required for intermittent operation; in the dehydration and purification, the respective advantages of the distillation tower and the membrane dehydration equipment are fully utilized, the reflux ratio is reduced to save energy consumption, and no entrainer is used to further save energy consumption and prevent the introduction of impurities; after the mixed vapor of the solvent and water reaches the azeotropic composition, it enters the membrane dehydration equipment for deep dehydration, which minimizes the use area of ​​the membrane and reduces equipment investment. Through the three steps of flash evaporation for solid removal-distillation purification-membrane dehydration, continuous and efficient production of purification and dehydration of organic solvents containing solid impurities is realized.

[0004] The technical solution adopted by the present invention is as follows: A purification and dehydration system for an organic solvent containing solid impurities, wherein the raw material is an organic solvent containing more than 20% water and less than 10% solid impurities, and the system comprises: a flash separator, a distillation tower, and a membrane dehydration device; The raw material inlet is connected to the bottom inlet of the flash heater, the top outlet of the flash heater is connected to the middle of the flash separator, and the lower part of the flash separator is connected to the raw material inlet through a circulation pump; The bottom of the flash separator is connected to an elutriation leg, the bottom of the elutriation leg is connected to a filter, the filter comprises a solid impurity discharge port and a liquid outlet, the liquid outlet of the filter is connected to the bottom inlet of the flash heater after merging with the raw material inlet; This equipment realizes the continuous production of purification and dehydration of organic solvents containing solid impurities through flash evaporation to remove solids - distillation purification - membrane dehydration.

[0005] Through the above technical scheme, the solvent and water are continuously separated from the solid-containing mixture through the circulation pump, flash heater and flash separator. The slurry is enriched and concentrated to 5 to 10 times in the elutriation leg and sent to the filter through the slurry pump to achieve solid-liquid separation. Most of the solid filter cake is discharged from the system, and a small amount of solid returns to the system with the filtrate for further flash separation. Through flash separation and elutriation, the solid-liquid separation is continuously and efficiently operated.

[0006] In the above continuous separation process, the density difference is utilized to make the solid components settle and enrich in the elutriation legs.

[0007] According to the above technical scheme, the concentrated slurry is separated from the solid by a filter, and the filtrate is returned to the flash separator to improve the solvent recovery rate.

[0008] Furthermore, in the above-mentioned purification and dehydration system for an organic solvent containing solid impurities, a slurry pump is connected to the pipeline between the washing leg and the filter.

[0009] Furthermore, in the above-mentioned purification and dehydration system of an organic solvent containing solid impurities, the top discharge port of the distillation tower is connected to the inlet pipeline of the top condenser; the gas phase outlet of the top condenser is connected to the pipeline of the membrane dehydration equipment; and the liquid phase outlet of the top condenser is connected to the reflux pipe of the upper part of the distillation tower.

[0010] In the above technical solution, the distillation tower is fed with gas phase, and the mixed steam of azeotropic composition is extracted from the top of the tower, and the excess water is discharged from the bottom of the tower. The mixed steam of azeotropic composition enters the membrane dehydration equipment for deep dehydration to obtain anhydrous solvent products. If the organic solvent does not need to be deeply dehydrated to anhydrous level, the organic solvent of azeotropic composition can be directly extracted from the top of the distillation tower through a bypass.

[0011] Furthermore, in the above-mentioned purification and dehydration system of an organic solvent containing solid impurities, the bottom discharge port of the distillation tower is respectively connected to the reboiler and the discharge pump inlet pipeline; the reboiler outlet is connected to the lower feed port pipeline of the distillation tower.

[0012] The flash separator+rectifying tower+molecular sieve adsorption process for preparing anhydrous solvent is applicable to a variety of different organic solvent systems, such as methanol, ethanol, isopropanol, tetrahydrofuran, acetonitrile, acetone, ethyl acetate, etc.

[0013] Furthermore, in the above-mentioned purification and dehydration system of an organic solvent containing solid impurities, when the organic solvent is ethanol, the ethanol recovery rate of the system is 98.7%. If the slurry is not filtered to recover the filtrate, the ethanol recovery rate is only 88%.

[0014] The purification and dehydration system for an organic solvent containing solid impurities as described in any one of the above items is used for desalination and dehydration purification operations of a salt-containing solvent.

[0015] A purification and dehydration process for an organic solvent containing solid impurities, using the above-mentioned equipment, an organic solvent containing water>20% and solid impurities<10% enters a flash separator from a raw material inlet through a pipeline, a circulation pump and a flash heater are turned on for steam heating, with continuous heating, water and solvent are continuously vaporized and discharged from the top of the flash separator, solid impurities are deposited in the elutriation legs during the circulation process, when the solid content in the elutriation legs is concentrated to 28%~32%, most of the solid impurities are separated by entering a filter, and the solid filter cake is directly discharged from the system from a solid impurity discharge port, and the filtrate with a solid content of 4%~6% is combined with the raw material at the raw material inlet and then returned to the flash separator.

[0016] Furthermore, in the above-mentioned purification and dehydration process of an organic solvent containing solid impurities, a mixed steam of water and an organic solvent enters a distillation tower for purification in the form of a gas phase feed, the top reflux-extraction ratio is controlled by controlling the circulating water volume of the top condenser, the bottom temperature is controlled by controlling the steam volume of the reboiler at the bottom of the tower, and the organic solvent content in the wastewater at the bottom of the tower is reduced. Finally, the wastewater with an organic solvent content of less than 0.5% at the bottom of the tower is discharged from the wastewater outlet through a drainage pump, and the mixed steam with an azeotropic composition is extracted from the top of the tower; The mixed steam with azeotropic composition enters the membrane dehydration equipment, and the selective permeability of the membrane is used to achieve deep separation of organic solvent and water. High-purity anhydrous organic solvent is obtained from the membrane retention side and extracted from the anhydrous product outlet. Wastewater with an organic solvent content of <0.5% on the membrane permeation side is discharged from the system from the permeate outlet.

[0017] Furthermore, in the above-mentioned purification and dehydration process of an organic solvent containing solid impurities, the steam pressure is controlled at 0.25 MPa and the bottom temperature is 119°C.

[0018] Furthermore, in the above-mentioned process for purifying and dehydrating an organic solvent containing solid impurities, the type of membrane is a molecular sieve water-permeable membrane with a membrane pore size of 0.4 nm.

[0019] Furthermore, in the above-mentioned purification and dehydration process of an organic solvent containing solid impurities, the high-purity anhydrous organic solvent refers to a product with a water content of <0.5%.

[0020] Furthermore, in the above-mentioned process for purifying and dehydrating an organic solvent containing solid impurities, the organic solvent content on the permeate side of the membrane dehydration device is less than 0.5%.

[0021] Furthermore, in the above-mentioned purification and dehydration process of an organic solvent containing solid impurities, when the opening degree of the top circulating water valve of the top condenser is 30% to 70%, the top reflux-production ratio is controlled to be 0.3 to 1.5.

[0022] The beneficial technical effects of the present invention are as follows: (1) In the present invention, continuous operation of solid-liquid separation is realized through flash separation and washing, saving the energy consumption of secondary gasification required for intermittent operation; (2) in the dehydration purification, the respective advantages of the distillation tower and the membrane dehydration equipment are fully utilized, the reflux ratio is reduced to save energy consumption, and no entrainer is used to further save energy consumption and prevent the introduction of impurities; (3) after the mixed vapor of the solvent and water reaches the azeotropic composition, it enters the membrane dehydration equipment for deep dehydration, which minimizes the use area of ​​the membrane and reduces the equipment investment. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 A schematic structural diagram of a system for purifying and dehydrating an organic solvent containing solid impurities provided in an embodiment of the present invention; Among them: 1. Flash separator; 2. Elution leg; 3. Circulation pump; 4. Flash heater; 5. Slurry pump; 6. Filter; 7. Distillation tower; 8. Reboiler; 9. Top condenser; 10. Drain pump; 11. Membrane dehydration equipment; 12. Raw material inlet; 13. Solid impurity outlet; 14. Anhydrous product outlet; 15. Permeate outlet; 16. Wastewater outlet. DETAILED DESCRIPTION

[0024] In order to facilitate understanding of the present application, the present application will be described more comprehensively below. The present application can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the disclosure of the present application more thorough and comprehensive.

[0025] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which this application belongs. The terms used herein in the specification of this application are only for the purpose of describing specific embodiments and are not intended to limit this application.

[0026] The technical solution adopted by the present invention is as follows: A purification and dehydration system for an organic solvent containing solid impurities, wherein the raw material is an organic solvent containing more than 20% water and less than 10% solid impurities, and the system comprises: a flash separator 1, a distillation tower 7, and a membrane dehydration device 11; The raw material inlet 12 is connected to the bottom inlet of the flash heater 4, and the top outlet of the flash heater 4 is connected to the middle of the flash separator 1. The lower part of the flash separator 1 is connected to the raw material inlet 12 through the circulation pump 3; The bottom of the flash separator 1 is connected to the elutriation leg 2, and the bottom of the elutriation leg 2 is connected to the filter 6, and the filter 6 includes a solid impurity discharge port 13 and a liquid outlet. The liquid outlet of the filter 6 is connected to the bottom inlet of the flash heater 4 after merging with the raw material inlet 12; This equipment realizes the continuous production of purification and dehydration of organic solvents containing solid impurities through flash evaporation to remove solids - distillation purification - membrane dehydration.

[0027] According to the above technical scheme, the solvent and water are continuously separated from the solid-containing mixture through the circulation pump 3, the flash heater 4, and the flash separator 1. The slurry is enriched and concentrated to 5 to 10 times in the elutriation leg 2, and sent to the filter 6 through the slurry pump 5 to achieve solid-liquid separation. Most of the solid filter cake is discharged from the system, and a small amount of solid returns to the system with the filtrate to continue flash separation. Through flash separation and elutriation, the solid-liquid separation is continuously and efficiently operated.

[0028] In the above-mentioned continuous separation process, the density difference is utilized to make the solid components settle and be enriched in the elutriation legs 2.

[0029] According to the above technical scheme, the concentrated slurry is separated into solids through the filter 6, and the filtrate is returned to the flash separator 1 to improve the solvent recovery rate.

[0030] Furthermore, in the above-mentioned purification and dehydration system for an organic solvent containing solid impurities, a slurry pump 5 is connected to the pipeline between the washing leg 2 and the filter 6 .

[0031] Furthermore, in the above-mentioned purification and dehydration system of an organic solvent containing solid impurities, the top discharge port of the distillation tower 7 is connected to the inlet pipeline of the top condenser 9; the gas phase outlet of the top condenser 9 is connected to the pipeline of the membrane dehydration equipment 11; and the liquid phase outlet of the top condenser 9 is connected to the reflux outlet pipeline of the upper part of the distillation tower 7.

[0032] In the above technical solution, the distillation tower 7 is fed with gas phase, and the mixed steam of azeotropic composition is extracted from the top of the tower, and the excess water is discharged from the bottom of the tower. The mixed steam of azeotropic composition is used in the membrane dehydration device 11, and the selective permeability of the membrane is used to achieve deep separation of organic solvent and water, thereby obtaining a high-purity anhydrous organic solvent. If the organic solvent does not need to be deeply dehydrated to anhydrous level, the organic solvent of azeotropic composition can be directly extracted from the top of the distillation tower 7 through a bypass.

[0033] Furthermore, in the above-mentioned purification and dehydration system of an organic solvent containing solid impurities, the bottom discharge port of the distillation tower 7 is respectively connected to the reboiler 8 and the inlet pipeline of the discharge pump 10; the outlet of the reboiler 8 is connected to the lower feed port pipeline of the distillation tower 7.

[0034] The flash separator+rectifying tower+molecular sieve adsorption process for preparing anhydrous solvent is applicable to a variety of different organic solvent systems, such as methanol, ethanol, isopropanol, tetrahydrofuran, acetonitrile, acetone, ethyl acetate, etc.

[0035] Furthermore, in the above-mentioned purification and dehydration system of an organic solvent containing solid impurities, when the organic solvent is ethanol, the ethanol recovery rate of the system is 98.7%.

[0036] The purification and dehydration system for an organic solvent containing solid impurities as described in any one of the above items is used for desalination and dehydration purification operations of a salt-containing solvent.

[0037] A purification and dehydration process for an organic solvent containing solid impurities, using the above-mentioned equipment, an organic solvent containing water>20% and solid impurities<10% enters a flash separator 1 from a raw material inlet 12 through a pipeline, a circulation pump 3 and a flash heater 4 are turned on for steam heating, with continuous heating, water and solvent are continuously vaporized and discharged from the top of the flash separator 1, and solid impurities are deposited in the elutriation leg 2 during the circulation process, when the solid content in the elutriation leg 2 is concentrated to 28%~32%, it enters a filter 6 to separate most of the solid impurities, and the solid filter cake is directly discharged from the system from a solid impurity discharge port 13, and the filtrate with a solid content of 4%~6% is combined with the raw material from the raw material inlet 12 and then returned to the flash separator 1.

[0038] Furthermore, in the above-mentioned purification and dehydration process of an organic solvent containing solid impurities, a mixed steam of water and an organic solvent enters a distillation tower 7 in the form of a gas phase feed for purification, the top reflux-extraction ratio is controlled by controlling the circulating water volume of a tower top partial condenser 9, the tower bottom temperature is controlled by controlling the steam volume of a tower bottom reboiler 8, the organic solvent content in the tower bottom wastewater is reduced, and finally the wastewater with an organic solvent content of less than 0.5% at the bottom of the tower is discharged from the system from a wastewater outlet 16 through a drainage pump 10, and a mixed steam with an azeotropic composition is extracted from the top of the tower; The mixed steam of azeotropic composition enters the membrane dehydration equipment 11, and the selective permeability of the membrane is used to achieve deep separation of organic solvent and water, and high-purity anhydrous organic solvent is obtained from the membrane retention side and extracted from the anhydrous product outlet 14. The wastewater with an organic solvent content of <0.5% on the membrane permeation side is discharged from the system from the permeate outlet 15.

[0039] Furthermore, in the above-mentioned purification and dehydration process of an organic solvent containing solid impurities, the steam pressure is controlled at 0.25 MPa and the bottom temperature is 119°C.

[0040] Furthermore, in the above-mentioned process for purifying and dehydrating an organic solvent containing solid impurities, the type of membrane is a molecular sieve water-permeable membrane with a membrane pore size of 0.4 nm.

[0041] Furthermore, in the above-mentioned purification and dehydration process of an organic solvent containing solid impurities, the high-purity anhydrous organic solvent refers to a product with a water content of <0.5%.

[0042] Furthermore, in the above-mentioned process for purifying and dehydrating an organic solvent containing solid impurities, the organic solvent content on the permeate side of the membrane dehydration device 11 is less than 0.5%.

[0043] Furthermore, in the above-mentioned purification and dehydration process of an organic solvent containing solid impurities, when the circulating water volume of the tower top partial condenser 9 is 30% to 70% of the tower top circulating water valve opening, the tower top reflux-production ratio is controlled to be 0.3 to 1.5.

[0044] In the above technical solution, the organic solvent vapor separated by the flash separator 11 contains a large amount of water. By controlling the reflux ratio of the distillation tower 7, a mixed vapor composed of an azeotropic mixture of organic solvent and water can be obtained from the top of the tower, and most of the water is discharged from the bottom of the tower.

[0045] Example 1 A purification and dehydration system for an organic solvent containing solid impurities, comprising a flash separator 1, an elutriation leg 2, a circulation pump 3, a flash heater 4, a slurry pump 5, a filter 6, a rectification tower 7, a reboiler 8, a tower top partial condenser 9, a drainage pump 10, and a membrane dehydration device 11; The bottom of the flash separator 1 is directly connected to the elutriation leg 2; the bottom of the elutriation leg 2, the slurry pump 5, and the filter 6 are connected in sequence through pipelines; the solid impurity discharge port 13 of the filter 6 is used to discharge the solid filter cake out of the system, and the liquid outlet of the filter 6 merges with the raw material inlet and returns to the bottom of the flash heater 4; the lower part of the flash separator 1, the circulation pump 3, the flash heater 4, and the middle of the flash separator 1 are connected in sequence through pipelines; the filtrate side of the filter 6, the raw material inlet pipeline and the outlet pipeline of the circulation pump 3 are simultaneously connected The inlet of the flash heater 4 is connected; the top discharge port of the flash separator 1 is connected to the feed port pipeline in the middle of the distillation tower 7; the bottom discharge port of the distillation tower 7 is respectively connected to the reboiler 8 and the discharge pump 10 inlet pipelines; the outlet of the reboiler 8 is connected to the feed port pipeline at the lower portion of the distillation tower 7; the top discharge port of the distillation tower 7 is connected to the inlet pipeline of the top condenser 9; the gas phase outlet of the top condenser 9 is connected to the pipeline of the membrane dehydration equipment 11; the liquid phase outlet of the top condenser 9 is connected to the reflux port pipeline at the upper portion of the distillation tower 7.

[0046] When the present invention is in operation, an organic solvent containing more than 20% water and about 5% solid impurities enters the flash separator 1 from the raw material inlet 12 through a pipeline, and the circulation pump 3 and the flash heater 4 are turned on for steam heating. With continuous heating, water and solvent are continuously vaporized and discharged from the top of the flash separator 1, and solid impurities are deposited in the elutriation leg 2 during the circulation process. When the solid content in the elutriation leg 2 is concentrated to about 30%, it is discharged through the slurry pump 5 and enters the filter 6 to separate most of the solid impurities. The solid filter cake is directly discharged from the system from the solid impurity discharge port 13, and the filtrate with a solid content of about 5% is combined with the raw material at the raw material inlet and then returned to the flash separator 1.

[0047] The mixed steam of water and organic solvent enters the distillation tower 7 in the form of gas phase feed for purification. The top reflux-extraction ratio is controlled to 0.3-1.5 by controlling the opening of the top circulating water valve of the top condenser 9 to 30%-70%. The bottom temperature of the tower is controlled by controlling the steam volume of the bottom reboiler 8 to minimize the organic solvent content in the wastewater at the bottom of the tower. Finally, the wastewater with an organic solvent content of less than 0.5% at the bottom of the tower is discharged from the system from the wastewater outlet 16 through the drainage pump 10, and the mixed steam with azeotropic composition is extracted from the top of the tower.

[0048] The mixed steam of azeotropic composition enters the membrane dehydration equipment 11, and the selective permeability of the membrane is used to achieve deep separation of organic solvent and water, and high-purity anhydrous organic solvent is obtained from the membrane retention side and extracted from the anhydrous product outlet 14. The wastewater with an organic solvent content of <0.5% on the membrane permeation side is discharged from the system from the permeate outlet 15.

[0049] Through the three steps of flash evaporation to remove solids - distillation purification - membrane dehydration, the continuous and efficient production of purification and dehydration of organic solvents containing solid impurities is achieved.

[0050] Although the present specification uses more terms such as flash separator 1, elutriation leg 2, circulation pump 3, flash heater 4, slurry pump 5, filter 6, rectification column 7, reboiler 8, top condenser 9, drainage pump 10, membrane dehydration equipment 11, etc., it does not exclude the possibility of using other terms. The use of these terms is only for more convenient description of the essence of the present invention, and interpreting them as any additional limitation is contrary to the spirit of the present invention.

[0051] Application Example 1 When the organic solvent containing solid impurities is ethanol, the specific data are shown in the following table: Table 1 When the organic solvent containing solid impurities is ethanol, the ethanol recovery rate of the method of the present invention

[0052] If the slurry is not filtered to recover the filtrate, the ethanol recovery rate is only 88%.

[0053] Table 2 When the organic solvent containing solid impurities is ethanol, the ethanol recovery rate when the filtrate is not treated in the prior art

[0054] It should be understood that parts not elaborated in detail in this specification belong to the prior art.

[0055] It should be understood that the above description of the preferred embodiment is relatively detailed and cannot be regarded as limiting the scope of patent protection of the present invention. Under the enlightenment of the present invention, ordinary technicians in this field can also make substitutions or modifications without departing from the scope of protection of the claims of the present invention, which all fall within the scope of protection of the present invention. The scope of protection requested for the present invention shall be based on the attached claims.

Claims

1. A purification and dehydration system for an organic solvent containing solid impurities, characterized in that: The raw material is an organic solvent containing more than 20% water and less than 10% solid impurities. The system comprises: a flash separator (1), a distillation tower (7), and a membrane dehydration device (11); The raw material inlet (12) is connected to the bottom inlet of the flash heater (4), and the top outlet of the flash heater (4) is connected to the middle of the flash separator (1). The lower part of the flash separator (1) is connected to the raw material inlet through the circulation pump (3); The bottom of the flash separator (1) is connected to an elutriation leg (2), the bottom of the elutriation leg (2) is connected to a filter (6), the filter (6) comprises a solid impurity discharge port (13) and a liquid outlet, and the liquid outlet of the filter (6) is connected to the bottom inlet of the flash heater (4) after merging with the raw material inlet; This equipment realizes the continuous production of purification and dehydration of organic solvents containing solid impurities through flash evaporation to remove solids - distillation purification - membrane dehydration.

2. A purification and dehydration system for an organic solvent containing solid impurities according to claim 1, characterized in that: A slurry pump (5) is connected to the pipeline between the washing leg (2) and the filter (6).

3. A purification and dehydration system for an organic solvent containing solid impurities according to claim 2, characterized in that: The top discharge port of the distillation tower (7) is connected to the inlet pipeline of the top condenser (9); the gas phase outlet of the top condenser (9) is connected to the pipeline of the membrane dehydration equipment (11); and the liquid phase outlet of the top condenser (9) is connected to the reflux outlet pipeline at the top of the distillation tower (7).

4. A purification and dehydration system for an organic solvent containing solid impurities according to claim 3, characterized in that: The bottom discharge port of the distillation tower (7) is connected to the inlet pipelines of the reboiler (8) and the discharge pump (10) respectively; the outlet of the reboiler (8) is connected to the feed inlet pipeline at the bottom of the distillation tower (7).

5. The purification and dehydration system of an organic solvent containing solid impurities according to claim 1, characterized in that: The organic solvent is methanol, ethanol, isopropanol, tetrahydrofuran, acetonitrile, acetone or ethyl acetate.

6. The purification and dehydration system of an organic solvent containing solid impurities according to claim 1, characterized in that: When the organic solvent is ethanol, the ethanol recovery rate of the system is 98.7%.

7. The purification and dehydration system for an organic solvent containing solid impurities according to any one of claims 1 to 6 is used for desalination and dehydration purification operations of a salt-containing solvent.

8. A process for purifying and dehydrating an organic solvent containing solid impurities, characterized in that: Using the device described in claim 4, an organic solvent containing more than 20% water and less than 10% solid impurities enters the flash separator (1) from the raw material inlet (12) through a pipeline, and the circulation pump (3) and the flash heater (4) are turned on for steam heating. As the heating continues, the water and the solvent are continuously vaporized and discharged from the top of the flash separator (1), and the solid impurities are deposited in the washing leg (2) during the circulation process. When the solid content in the washing leg (2) is concentrated to 28% to 32%, it enters the filter (6) to separate most of the solid impurities, and the solid filter cake is directly discharged from the system from the solid impurity discharge port (13). The filtrate with a solid content of 4% to 6% is combined with the raw material from the raw material inlet (12) and then returns to the flash separator (1).

9. The process for purifying and dehydrating an organic solvent containing solid impurities according to claim 8, characterized in that: The mixed steam of water and organic solvent enters the distillation tower (7) for purification in the form of gas phase feed. The reflux-extraction ratio at the top of the tower is controlled by controlling the circulating water volume of the tower top condenser (9). The temperature of the tower bottom is controlled by controlling the steam volume of the tower bottom reboiler (8) to reduce the organic solvent content in the wastewater at the bottom of the tower. Finally, the wastewater with an organic solvent content of less than 0.5% at the bottom of the tower is discharged from the system through the wastewater outlet (16) through the drainage pump (10). The mixed steam with an azeotropic composition is extracted from the top of the tower. The mixed steam of azeotropic composition enters the membrane dehydration device (11), and the selective permeability of the membrane is used to achieve deep separation of organic solvent and water, and a high-purity anhydrous organic solvent is obtained from the membrane retention side and extracted from the anhydrous product outlet (14). Wastewater with an organic solvent content of less than 0.5% on the membrane permeation side is discharged from the system from the permeate outlet (15).

10. The process for purifying and dehydrating an organic solvent containing solid impurities according to claim 8, characterized in that: The organic solvent content on the permeate side of the membrane dehydration device (11) is less than 0.5%.

Images