Mother liquor continuous treatment device

Abstract

The invention relates to a mother liquor continuous treatment device, which is used for treating mother liquor containing a high-boiling-point organic solvent, water and salt, and is characterized in that the device comprises a raw material tank, a scraper evaporator, a mother liquor recovery system and a condensation system, the mother liquor recovery system comprises a stirring tank connected with the bottom of the scraper evaporator, a centrifugal machine connected with the bottom of the stirring tank, and a centrifugal mother liquor receiving tank connected with the centrifugal machine; the condensation system comprises a first-stage preheater, a second-stage preheater, a condenser, a tail cooler and an evaporated liquid receiving tank, wherein the second-stage preheater and the condenser are connected with the first-stage preheater, the tail cooler is connected with the condenser, and the evaporated liquid receiving tank is respectively connected with the condenser and the tail cooler.

Description

Technical Field

[0001] The present application relates to a mother liquor continuous treatment device, which is used for treating a mother liquor containing a high-boiling-point organic solvent, water and a salt, so as to separate and recover the salt and the high-boiling-point organic solvent. Background Art

[0002] Post-treatment of salty solutions generally uses falling film evaporators, multiple-effect evaporators or reactors for intermittent distillation. Among these treatment methods: falling film evaporators have low operating flexibility and strict control parameter range requirements. If the control adjustment is not timely, it is easy to cause tube blockage; multiple-effect evaporators are mostly made of metal, and high-temperature solutions with high chloride ion content are highly corrosive to them, and there are also problems such as large floor space; reactor distillation has low heat transfer efficiency, and it is difficult to determine the evaporation end point of intermittent distillation, which requires multiple manual confirmations, resulting in low evaporation efficiency. Summary of the invention

[0003] In view of the above problems, the present application provides a mother liquor continuous treatment device, which is used to treat a mother liquor containing a high-boiling point organic solvent, water and salt, so as to separate and recover the salt and the high-boiling point organic solvent therein.

[0004] Specifically, this application relates to:

[0005] (1) a mother liquor continuous treatment device, which is used to treat a mother liquor containing a high-boiling-point organic solvent, water and salt, and the device comprises a raw material tank, a scraper evaporator, a mother liquor recovery system and a condensation system;

[0006] The mother liquor recovery system comprises a stirring tank connected to the bottom of the scraper evaporator, a centrifuge connected to the bottom of the stirring tank, and a centrifugal mother liquor receiving tank connected to the centrifuge;

[0007] The condensation system comprises a primary preheater, a secondary preheater and a condenser connected to the primary preheater, a tail cooler connected to the condenser, and a distillate receiving tank, wherein the distillate receiving tank is respectively connected to the condenser and the tail cooler.

[0008] (2) According to the mother liquor continuous treatment device described in (1) above, the scraper evaporator comprises a cylinder and a jacket on the outer wall of the cylinder, a stirring blade is provided in the cylinder, and a heat exchange medium flows in the jacket.

[0009] (3) According to the mother liquor continuous treatment device described in (2) above, two or more layers of the stirring blades are provided in the cylinder, and the scraper is preferably provided between the layers of the stirring blades or across the layers.

[0010] (4) According to the mother liquor continuous treatment device described in (3) above, three layers of stirring blades are arranged in the cylinder, and preferably scrapers are arranged between the first and second layers and the second and third layers of stirring blades respectively.

[0011] (5) According to the mother liquor continuous treatment device described in (3) above, six layers of stirring blades are arranged in the cylinder, and scrapers are preferably arranged across the layers between the first and third layers of stirring blades, between the second and fifth layers of stirring blades, and between the fourth and sixth layers of stirring blades.

[0012] (6) The mother liquor continuous treatment device according to any one of (1) to (5) above, wherein the scraper is about 2 mm away from the inner wall of the cylinder.

[0013] (7) According to any one of the mother liquor continuous treatment devices described in (2) to (6) above, a circular distribution plate is provided above the first layer of stirring blades at the upper part of the cylinder.

[0014] (8) The mother liquor continuous treatment apparatus according to any one of (1) to (7) above, wherein the centrifuge is a double-piston scraper centrifuge.

[0015] (9) A mother liquor continuous treatment device according to any one of (1) to (8) above, wherein the shell side inlet of the primary preheater is connected to the steam outlet of the scraper evaporator cylinder, and the steam evaporated from the scraper evaporator cylinder is introduced into the shell side of the primary preheater as a heating medium.

[0016] (10) A mother liquor continuous treatment device according to any one of (1) to (9) above, wherein the shell side inlet of the secondary preheater is connected to the bottom of the jacket on the outer wall of the scraper evaporator, and the liquid (e.g., steam condensate) cooled in the jacket as a heating medium (e.g., water vapor) is introduced into the shell side of the secondary preheater as a heating medium.

[0017] (11) The mother liquor continuous treatment device according to any one of (1) to (10) above, wherein the centrifugal mother liquor receiving tank is connected to the raw material tank, and the liquid in the centrifugal mother liquor receiving tank is returned to the raw material tank through the mother liquor pump.

[0018] (12) The mother liquor continuous treatment apparatus according to any one of (1) to (11) above, wherein the high boiling point solvent is one or more selected from N,N-dimethylformamide, N,N-dimethylacetamide, and ethylene glycol.

[0019] (13) A mother liquor continuous treatment apparatus according to any one of (1) to (12) above, wherein the salt is an alkali metal salt or an alkaline earth metal salt, preferably a hydrochloride, sulfate, nitrate, carbonate, bicarbonate, or hydroxide of an alkali metal or an alkaline earth metal.

[0020] (14) A mother liquor continuous treatment device according to any one of (1) to (13) above, which is used to treat the mother liquor obtained by the following reaction after phase separation and removal of petroleum ether solvent, wherein the mother liquor contains a high boiling point solvent N,N-dimethylacetamide and NaCl salt.

[0021]

[0022] The scraper evaporator is used in the mother liquor continuous treatment device of the present application. The scraper evaporator has the characteristics of large operating flexibility, high heat transfer efficiency and short residence time. It will not accumulate materials and can avoid the problem of blockage caused by excessive evaporation and excessive salt precipitation. In addition, the saline solution can be continuously distilled to improve the evaporation efficiency and avoid the corrosion of chloride ions to the equipment at high temperature. At the same time, the mother liquor continuous treatment device of the present application also effectively utilizes the steam evaporated by the scraper evaporator as the heating medium of the first-stage preheater, and the steam condensed water after the steam condensation in the outer wall jacket of the scraper evaporator as the heating medium is further used as the heating medium of the second-stage preheater, which greatly improves the energy utilization efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 This is a schematic structural diagram of one of the preferred embodiments of the mother liquor continuous treatment device of the present application.

[0024] Figure 2 This is a structural schematic diagram of one of other preferred embodiments of the scraper evaporator used in the mother liquor continuous processing device of the present application, in which stirring blades and scrapers are provided inside.

[0025] In the figure: 1. Raw material tank; 2. Primary preheater; 3. Secondary preheater; 4. Scraper evaporator; 4-1. Scraper evaporator cylinder; 4-2. Scraper evaporator outer wall jacket; 5. Mixing tank; 6. Centrifuge; 7. Centrifugal mother liquor receiving tank; 8. Condenser; 9. Tail cooler; 10. Distillate receiving tank; 11. Feed pump; 12. Mother liquor pump; 13. Mixing blade; 14. Scraper; 15. Circular distribution plate. DETAILED DESCRIPTION

[0026] The mother liquor continuous treatment device of the present application is further described in detail below in conjunction with the accompanying drawings and specific implementation methods, but the present application is not limited thereto, and any modifications or changes that do not deviate from the subject matter of the present application fall within the scope of the present application.

[0027] like Figure 1 As shown, the mother liquor continuous processing device of the present application includes a raw material tank 1, a scraper evaporator 4, a mother liquor recovery system and a condensation system.

[0028] The raw material tank 1 is used to store the mother liquor to be treated. The mother liquor to be treated contains a high boiling point solvent, water and salt.

[0029] Examples of the high boiling point solvent include N,N-dimethylformamide, N,N-dimethylacetamide (DMAC), and ethylene glycol.

[0030] Examples of salts include alkali metal salts or alkaline earth metal salts, and more specifically, examples include hydrochlorides, sulfates, nitrates, carbonates, bicarbonates, or hydroxides of alkali metals or alkaline earth metals, and typical examples are NaCl, NaSO4, NaOH, etc.

[0031] The scraper evaporator 4 comprises a barrel 4-1 and a barrel outer wall jacket 4-2. A stirring blade 13 is arranged in the barrel 4-1, and a heat exchange medium is passed through the barrel outer wall jacket 4-2 for heat exchange. The heat exchange medium can be, but is not limited to, steam.

[0032] The stirring blade 13 may be, for example, an equilateral triangle. In some specific embodiments, more than two layers of stirring blades 13 are arranged in the cylinder 4-1.

[0033] In other specific embodiments, Figure 1 As shown, three layers of stirring blades 13 are arranged in the cylinder 4-1. In this structure, preferably, scrapers 14 are arranged between the first, second and second, third layers of stirring blades 13, respectively.

[0034] In other specific embodiments, Figure 2 As shown, six layers of stirring blades 13 are arranged in the cylinder 4-1. In this structure, preferably, a scraper 14 is arranged between the first and third layers of stirring blades 13, between the second and fifth layers of stirring blades 13, and between the fourth and sixth layers of stirring blades 13.

[0035] The scraper 14 is preferably about 2 mm away from the inner wall of the cylinder 4 - 1 .

[0036] In some specific embodiments, a circular distribution plate 15 is disposed above the first layer of stirring blades 13. The material enters the circular distribution plate 15, and is distributed to the inner wall of the cylinder 4-1 by the rotation of the circular distribution plate 15, and flows downward by gravity.

[0037] The mother liquor recovery system comprises a stirring tank 5 connected to the bottom of the scraper evaporator 4, a centrifuge 6 connected to the stirring tank 5, and a centrifugal mother liquor receiving tank 7 connected to the centrifuge 6. The liquid in the centrifugal mother liquor receiving tank 7 is preferably powered by a mother liquor pump 12 and returned to the raw material tank 1.

[0038] The condensation system includes a primary preheater 2, a secondary preheater 3 connected to the primary preheater 2, a condenser 8, a tail cooler 9 connected to the condenser 8, and a distillate receiving tank 10 respectively connected to the condenser 8 and the tail cooler 9 and used for receiving the liquid condensed by the condenser 8 and the tail cooler 9.

[0039] The mother liquor buffered in the raw material tank 1 is introduced into the scraper evaporator 4 from the feed pipeline through the tubes of the primary preheater 2 and the secondary preheater 3 by the feed pump 11. The mother liquor is evenly distributed on the inner wall of the cylinder 4-1 through the scraper 14 inside the scraper evaporator 4, and exchanges heat with the medium in the jacket 4-2 on the outer wall of the cylinder.

[0040] Most of the water and a small amount of high boiling point solvent evaporated by the scraper evaporator 4 in the mother liquor are vaporized and enter the condensation system from the top of the scraper evaporator 4. Most of the high boiling point solvent and a small amount of water and salt remain at the bottom of the scraper evaporator 4.

[0041] The gas phase after the mother liquid in the scraper evaporator 4 is first used as a heating heat source to enter the shell side of the primary preheater 2 to heat the mother liquid, and then enters the shell side of the condenser 8 for condensation, and the condensed liquid enters the distilled liquid receiving tank 10 for storage. The uncondensed gas in the condenser 8 enters the tube side of the tail cooler 9 for further condensation and then enters the distilled liquid receiving tank 10, thereby reducing losses.

[0042] The shell side inlet of the primary preheater 2 is connected to the steam outlet of the scraper evaporator cylinder 4-1, and the steam evaporated from the scraper evaporator cylinder 4-1 is introduced into the shell side of the primary preheater 2 as a heating medium for heating the mother liquor introduced from the raw material tank 1 into the scraper evaporator 4.

[0043] In some specific embodiments, the high boiling point solvent is DMAC, the salt is NaCl, the temperature of the gas evaporated from the scraper evaporator 4 is about 70° C., and the steam at about 70° C. is introduced into the shell side of the primary preheater 2 .

[0044] The shell side inlet of the secondary preheater 3 is connected to the bottom of the outer wall jacket 4-2 of the scraper evaporator, and the liquid after the heating medium in the jacket is cooled is introduced into the shell side of the secondary preheater 3 as the heating medium, which is used to further heat the mother liquor introduced from the raw material tank 1 into the scraper evaporator 4.

[0045] In some specific embodiments, water vapor is introduced into the outer wall jacket 4 - 2 of the scraper evaporator as a heating medium, and the water vapor condenses into condensed water at about 90° C., and the condensed water at about 90° C. is introduced into the shell side of the secondary preheater 3 .

[0046] Circulating water is passed through the tube side of the condenser 8, and low-temperature water of about 7° C. is passed through the shell side of the aftercooler 9.

[0047] The unvaporized mother liquor at the bottom of the scraper evaporator 4 enters the stirring tank 5 for temporary storage. When a certain volume of mother liquor is stored, the bottom valve of the stirring tank 5 is opened to allow the mother liquor to enter the centrifuge 6, which centrifuges and separates the salt in the mother liquor. The remaining liquid enters the centrifugal mother liquor receiving tank 7, and can be subsequently returned to the raw material tank 1 through the mother liquor pump 12 for the next steaming.

[0048] The stirring tank 5 may be provided with a stirrer and a jacket for cooling the un-vaporized mother liquor.

[0049] The centrifuge 6 can be any centrifuge that can be operated continuously, and preferably a double piston scraper centrifuge is suitable. The advantage of using such a centrifuge is that the humidity of the solid salt obtained by centrifugation is lower. The solid salt separated by the centrifuge 6 enters the silo for processing in the next step.

[0050] In a preferred embodiment, the scraper evaporator barrel 4-1 is made of glass-lined material, and the scraper evaporator outer wall jacket 4-2 is made of Q235B carbon steel. Such materials have good corrosion resistance to high-concentration chloride ion solutions.

[0051] The device of the present application can be widely used to treat mother liquor containing high boiling point solvent, water and salt. As a specific example, it can be cited that it is used to treat the mother liquor produced by the preparation of diphenyldiazomethane intermediate as shown below in the preparation of isoxadifen-ethyl. The mother liquor is the mother liquor after the low boiling point solvent petroleum ether is removed by phase separation, and contains water, high boiling point solvent DMAC, and NaCl salt generated as a product.

[0052]

[0053] The mother liquor continuous treatment device of the present application is described in detail below through examples, but the present application is not limited to these specific examples, and any modifications and changes that do not depart from the scope of the present application fall within the scope of the present application.

[0054] Example

[0055] Start the vacuum pump and control the vacuum degree in the scraper evaporator 4 to about -80 kPa; open the feed valve of the raw material tank 1, start the feed pump 11, and control the feed flow rate to 0.8 m 3 / h, the mother liquor produced by preparing diphenyldiazomethane, an intermediate of isoxadifen ethyl, is introduced into the scraper evaporator 4; steam is slowly introduced into the scraper evaporator jacket 4-2 to heat the material, and the steam flow rate is 800-850kg / h; after the system is stable for 5 minutes, a sample is taken from the stirring tank 5 to detect the moisture content. If the detected moisture content is greater than 5%, the steam flow rate is increased to 900kg / h, and the sampling operation is repeated after stabilization for another 5 minutes until the moisture content is less than 5%; when the liquid level in the stirring tank 5 reaches 1500mm, the feeding and heating steam are stopped, the bottom of the scraper evaporator 4 stops discharging the material to the stirring tank 5, and the stirring tank 5 is restored to normal pressure; the centrifuge 6 is started, the material in the stirring tank 5 is placed in the centrifuge 6, and centrifugal filtration is started to separate the NaCl salt and the liquid; the liquid enters the centrifugal mother liquor receiving tank 7, and returns to the raw material tank 1 under the power of the mother liquor pump, waiting for the next jacket steaming, and the NaCl salt in the centrifuge 6 enters the silo.

[0056] After most of the water evaporated by the scraper evaporator 4 and a small amount of high-boiling-point solvent are vaporized, they first enter the shell side of the primary preheater 2 as a heating heat source from the top of the scraper evaporator 4, and then enter the shell side of the condenser 8 for condensation, and the condensed liquid enters the distillate receiving tank 10 for storage. The uncondensed gas in the condenser 8 enters the tube side of the tail cooler 9 for further condensation and then enters the distillate receiving tank 10, thereby reducing losses.

[0057] The working time of centrifuge 6 for processing a single batch of materials is 8 hours, and the scraper evaporator 4 works for 16 hours per day, with a total average processing capacity of 12.8m 3 / d.

[0058] Comparative Example

[0059] Three 6300L glass-lined reactors were used to intermittently distill the mother liquor of diphenyldiazomethane intermediate in the preparation of bisoxadifen. The receiving tanks for the distilled liquid were three 2000L storage tanks. Each reactor was fed with 5000L of material, and after feeding, the vacuum was turned on and steam was used for heating. When the distilled liquid receiving tank reached a certain liquid level, the distilled liquid was poured into a large buffer tank for temporary storage; after the liquid level of the distilled liquid receiving tank was lower than the set value, the material was stopped from being discharged, and when the set vacuum was reached, the distillation was restarted by passing steam; when the liquid level of the receiving tank reached a certain height again, the operation was repeated; after the liquid level of the distillation kettle reached the lower limit, the steam and vacuum were turned off, and samples were taken for testing. If the water content was higher than 5%, the vacuum and steam were restarted, the distillation continued, and samples were taken for testing at regular intervals; if the water content was lower than 5%, when the temperature dropped to 40-50°C, the material entered the rotary drum centrifuge for centrifugal throwing.

[0060] The distillation process takes 12 hours. Because the drum centrifuge has a limited processing capacity, each batch of materials needs to be fed into the centrifuge twice, and the working time of a single centrifuge is 4 hours. The total average processing capacity is 12.8m 3 / d.

Claims

1. A mother liquor continuous treatment device, which is used to treat a mother liquor containing a high boiling point organic solvent, water and a salt, characterized in that: The device includes a raw material tank, a scraper evaporator, a mother liquor recovery system and a condensation system; The mother liquor recovery system comprises a stirring tank connected to the bottom of the scraper evaporator, a centrifuge connected to the bottom of the stirring tank, and a centrifugal mother liquor receiving tank connected to the centrifuge; The condensation system comprises a primary preheater, a secondary preheater and a condenser connected to the primary preheater, a tail cooler connected to the condenser, and a distillate receiving tank, wherein the distillate receiving tank is respectively connected to the condenser and the tail cooler.

2. The mother liquor continuous treatment device according to claim 1, characterized in that: The scraper evaporator comprises a cylinder and a jacket on the outer wall of the cylinder. A stirring blade is arranged in the cylinder and a heat exchange medium flows through the jacket.

3. The mother liquor continuous treatment device according to claim 2, characterized in that: The cylinder body is provided with two or more layers of the stirring blades, and the scraper is preferably provided between the layers of the stirring blades or across the layers.

4. The mother liquor continuous treatment device according to claim 2 or 3, characterized in that: A circular distribution plate is arranged above the first layer of stirring blades at the upper part of the cylinder.

5. The mother liquor continuous treatment device according to any one of claims 1 to 4, characterized in that: The centrifuge is a double-piston scraper centrifuge.

6. The mother liquor continuous treatment device according to any one of claims 1 to 5, characterized in that: The shell side inlet of the primary preheater is connected to the steam outlet of the scraper evaporator cylinder, and the steam evaporated from the scraper evaporator cylinder is introduced into the shell side of the primary preheater as a heating medium.

7. The mother liquor continuous treatment device according to any one of claims 1 to 6, characterized in that: The shell side inlet of the secondary preheater is connected to the bottom of the outer wall jacket of the scraper evaporator, and the liquid after the heating medium in the jacket is cooled is introduced into the shell side of the secondary preheater as the heating medium.

8. The mother liquor continuous treatment device according to any one of claims 1 to 7, characterized in that: The centrifugal mother liquor receiving tank is connected to the raw material tank, and the liquid in the centrifugal mother liquor receiving tank is returned to the raw material tank through the mother liquor pump.

9. The mother liquor continuous treatment device according to any one of claims 1 to 8, characterized in that: The high boiling point solvent is one or more selected from N,N-dimethylformamide, N,N-dimethylacetamide, and ethylene glycol; the salt is an alkali metal salt or an alkaline earth metal salt, preferably an alkali metal or alkaline earth metal hydrochloride, sulfate, nitrate, carbonate, bicarbonate, or hydroxide of an alkali metal or alkaline earth metal.

10. The mother liquor continuous treatment device according to any one of claims 1 to 9, characterized in that: The device is used to process the mother liquor obtained by phase separation and removal of petroleum ether solvent from the following reaction, wherein the mother liquor contains high boiling point solvent DMAC and NaCl salt:

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