Rectification and purification system for water-containing triethylamine

Abstract

The invention belongs to the technical field of production of vinylene carbonate, and particularly relates to a rectification and purification system for water-containing triethylamine. Comprising a triethylamine azeotropic module, a triethylamine rectification module and a wastewater recovery module, wherein the triethylamine azeotropic module is used for impurity removal and primary water separation of a water-containing triethylamine solution; the triethylamine rectification module is connected with the triethylamine azeotropic module, and the triethylamine rectification module is used for purifying a water-containing triethylamine solution to produce a qualified triethylamine solution; the wastewater recovery module is connected with the triethylamine azeotropic module and the triethylamine rectification module, and the wastewater recovery module is used for wastewater recovery and sewage treatment of the triethylamine azeotropic module and the triethylamine rectification module. According to the method, impurities and polymers are separated in an azeotropic mode, meanwhile, the triethylamine yield and the continuous processing efficiency are improved, frequent cleaning of equipment is not needed, and the working efficiency is improved.

Description

Technical Field

[0001] The invention belongs to the technical field of vinylene carbonate production, and particularly relates to a distillation and purification system for aqueous triethylamine. Background Art

[0002] Chloroethylene carbonate reacts with triethylamine in the solvent methyl tert-butyl ether to obtain the target compound vinylene carbonate and the by-product triethylamine hydrochloride. In order to increase the effective utilization of triethylamine, triethylamine hydrochloride reacts with sodium hydroxide to generate triethylamine, sodium chloride and water. By standing and separating, the triethylamine in the upper part will contain a small amount of water, and the water content is unstable. Nowadays, the new energy industry has a serious overcapacity, and most companies are in a loss-making state. In order to achieve the purpose of turning losses into profits, on the basis of the existing synthesis of vinylene carbonate process, by effectively utilizing the by-product of triethylamine hydrochloride, the purpose of reducing costs is achieved. The existing technology mainly consists of three standard distillation towers, all of which are operated at normal pressure. The water-containing triethylamine enters the first distillation tower, and the water is divided in the reflux tank. The water returns to the first distillation tower, and the upper triethylamine goes to the triethylamine distillation tower. The first distillation tower kettle outputs triethylamine-containing sewage and enters the recovery tower. The kettle of the triethylamine distillation tower produces triethylamine products, part of the reflux tank material is used as reflux, and the remaining part is used as feed for the first distillation tower. The recovery tower kettle produces qualified wastewater for external delivery, and part of the reflux tank produces water-containing triethylamine for reflux, and the remaining part is also used as feed for the first distillation tower. Because the raw material source comes from the reaction product triethylamine hydrochloride, it will contain a large amount of impurities and a variety of unknown organic matter. The first distillation tower generally uses a traditional atmospheric distillation tower. The kettle temperature of the traditional atmospheric distillation tower needs to be controlled at about 100 degrees, which will cause side reactions in the reboiler due to high temperature, produce viscous macromolecular polymers, and adhere to the inside of the reboiler, resulting in poor heat exchange capacity and affecting the triethylamine yield. In addition, the first distillation tower adopts the top or middle feeding method. The mixture of impurities and viscous polymers can easily clog the internal packing of the distillation tower. It is necessary to use a filter with a smaller precision at the feed inlet. It will be found that the pressure difference between the top and bottom of the distillation tower is still increasing during long-term operation, and the packing in the distillation tower still needs to be cleaned regularly. At the same time, the cleaning cycle of the inlet filter is also relatively frequent, and the self-cleaning filter is not suitable for use due to the mixture of impurities and viscous polymers. The recovery tower usually adopts the control method of normal pressure. Under normal pressure conditions, the temperature of the tower kettle needs to be around 100 degrees to make the triethylamine content in the sodium chloride aqueous solution less than 0.05%. Too high temperature will also aggravate the side reactions in the recovery tower, affecting the operation of the recovery tower and the yield of triethylamine. Summary of the invention

[0003] In view of the above problems, the object of the present invention is to provide a distillation purification system for aqueous triethylamine to solve the problems of low triethylamine recovery efficiency and complicated operation in the existing aqueous triethylamine purification process.

[0004] In order to achieve the above object, the present invention adopts the following technical solutions:

[0005] The present invention provides a distillation and purification system for aqueous triethylamine, comprising:

[0006] Triethylamine azeotropic module, used for impurity removal and preliminary water separation of aqueous triethylamine solution;

[0007] A triethylamine distillation module is connected to the triethylamine azeotropic module, and the triethylamine distillation module is used for purifying an aqueous triethylamine solution to produce a qualified triethylamine solution;

[0008] The wastewater recovery module is connected with the triethylamine azeotropic module and the triethylamine distillation module. The wastewater recovery module is used for wastewater recovery and sewage treatment of the triethylamine azeotropic module and the triethylamine distillation module.

[0009] The triethylamine azeotropic module comprises an azeotropic kettle, an azeotropic kettle condenser, a water separator A, a water separator tank A and a feed tank which are sequentially connected by pipelines, wherein the azeotropic kettle has an azeotropic kettle circulation system, and the bottom sewage outlet of the water separator A is connected to the wastewater recovery module; the pipeline between the water separator tank A and the feed tank is connected to the wastewater recovery module through a bypass pipeline; the bottom discharge outlet of the water separator tank A is provided with a density meter, and the density meter is used to detect the density value of the solution discharged from the water separator tank A; a drainage cut-off valve a and a discharge cut-off valve a are respectively provided on the pipelines connecting the water separator tank A, the feed tank and the wastewater recovery module, and the drainage cut-off valve a and the discharge cut-off valve a are automatically switched according to the indication of the density meter; the feed tank is connected to the triethylamine distillation module.

[0010] A water baffle a is provided on the inner top of the water separator A, and a liquid inlet and a liquid outlet are provided on the top of the water separator A on both sides of the water baffle a, the liquid inlet is connected to the azeotropic kettle condenser, and the liquid outlet is connected to the water separator A;

[0011] The bottom sewage outlet of the water divider A is provided with a vortex preventer A, and the vortex preventer A is connected to the wastewater recovery module through a U-shaped drain pipe; the bottom discharge port of the water divider tank A is provided with a vortex preventer B.

[0012] The azeotropic kettle circulation system comprises an azeotropic circulation pump, an azeotropic kettle circulation flow regulating valve, an azeotropic kettle circulation flow meter and an azeotropic kettle reboiler, wherein the azeotropic kettle reboiler is arranged on the upper part of the azeotropic kettle, the bottom of the azeotropic kettle is connected to the top of the azeotropic kettle reboiler through the azeotropic circulation pump and the azeotropic kettle circulation pipeline, and the azeotropic kettle circulation flow regulating valve and the azeotropic kettle circulation flow meter are arranged on the azeotropic circulation pipeline; the azeotropic kettle circulation pipeline is respectively connected to the wastewater recovery module and the sewage pipeline through two pipelines;

[0013] The azeotropic kettle is provided with an azeotropic kettle level gauge, an azeotropic kettle liquid level gauge and an azeotropic kettle thermometer; the azeotropic kettle is connected with a pipeline of aqueous triethylamine solution and a pipeline of process water.

[0014] The triethylamine distillation module comprises a triethylamine distillation kettle, a triethylamine distillation tower, a distillation tower condenser, a water separator B and a water separator tank B which are connected in sequence, wherein the triethylamine distillation tower is connected to the feed tank via a triethylamine distillation feed pump and a feed pipeline, and a regulating valve c and a flow meter a are provided on the feed pipeline; the triethylamine distillation kettle has a distillation kettle circulation system, and the distillation kettle circulation system is connected to the triethylamine finished product line;

[0015] The inner top of the water separator B is provided with a water baffle B and a feed port and a discharge port located on both sides of the water baffle B, the feed port is connected to the distillation tower condenser, and the discharge port is connected to the water separator tank B; the side wall of the water separator B is connected to the top of the triethylamine distillation tower through a reflux pipe; the bottom of the water separator B is connected to the wastewater recovery module through a sewage pipeline;

[0016] The bottom discharge port of the water separation tank B is connected to the feed tank and the wastewater recovery module through a discharge pipeline and a drainage pipeline respectively.

[0017] The bottom discharge port of the water separation tank B is provided with a vortex preventer C and a density meter C, and the density meter C is used to detect the discharge density value of the water separation tank B;

[0018] A discharge shut-off valve b and a drainage shut-off valve b are respectively provided on the discharge pipeline and the drainage pipeline connected to the bottom discharge port of the water separation tank B. The discharge shut-off valve b and the drainage shut-off valve b are switched according to the detection value of the density meter c.

[0019] The rectifying kettle circulation system comprises a triethylamine rectifying kettle circulation pump, a flow meter b, a rectifying kettle circulation regulating valve and a rectifying tower reboiler, wherein the rectifying tower reboiler is arranged at the top of the triethylamine rectifying kettle, the bottom of the triethylamine rectifying kettle is connected to the top of the rectifying tower reboiler through the triethylamine rectifying kettle circulation pump and the rectifying tower circulation pipeline, and the rectifying tower circulation pipeline is provided with a flow meter b, a rectifying kettle circulation regulating valve and a sampling point a; the rectifying tower circulation pipeline is connected to the triethylamine finished product line;

[0020] The triethylamine distillation kettle is provided with a triethylamine distillation kettle liquid level gauge and a triethylamine distillation kettle thermometer.

[0021] The wastewater recovery module includes a sewage tank, a recovery tower, a recovery tower condenser and a recovery tower reflux tank which are connected in sequence through pipelines, wherein the bottom of the recovery tower reflux tank is respectively connected to the top of the recovery tower and the azeotropic kettle through a recovery tower reflux pump and two reflux pipelines; the middle of the recovery tower is connected to the sodium chloride solution feed line; the lower part of the recovery tower is provided with a recovery tower self-circulation system, and the recovery tower self-circulation system is connected to the sodium chloride solution delivery line.

[0022] The recovery tower self-circulation system comprises a recovery tower circulation pump and a recovery tower reboiler, wherein the water inlet of the recovery tower circulation pump is connected to the bottom of the recovery tower, the water outlet of the recovery tower circulation pump is respectively connected to the bottom of the recovery tower reboiler and the sodium chloride solution delivery line through two pipelines, and a sampling point b is provided at the water outlet of the recovery tower circulation pump; an inlet manual valve and a flow meter d are provided on the pipeline connected to the bottom of the recovery tower reboiler;

[0023] A recovery tower liquid level gauge and a recovery tower kettle temperature gauge are arranged at the lower part of the recovery tower.

[0024] The bottom of the sewage tank is connected to the water inlet of the sewage delivery pump, and the water outlet of the sewage delivery pump is respectively connected to the top of the recovery tower and the azeotropic kettle through two pipelines; the top of the sewage tank is connected to the azeotropic kettle circulation system, water separator A and water separator B; the pipeline connecting the sewage tank and the azeotropic kettle circulation system is sequentially provided with a self-cleaning filter, a water inlet flowmeter and a sewage tank water inlet regulating valve.

[0025] The advantages and beneficial effects of the present invention are as follows: the distillation and purification system of water-containing triethylamine provided by the present invention adopts an azeotropic method to separate impurities and polymers, and at the same time improves the triethylamine yield and continuous processing efficiency, and does not require frequent cleaning of equipment. The azeotropic kettle reboiler is located at the upper part of the azeotropic kettle, and adopts a top-in and bottom-out method to reduce the occurrence of side reactions. The self-cleaning filter is used intermittently to remove impurities, and the polymer separation and discharge method in the azeotropic kettle ensures the continuous operation of the system. The azeotropic kettle and the triethylamine distillation tower use a water separator and a water separator tank to divide water twice, and the design of the water baffle and the vortex preventer of the water separator, as well as the automatic drainage and overflow outlet method of triethylamine, improve the water separation effect. The recovery tower adopts negative pressure operation to simultaneously recover the triethylamine in the sewage and the reacted sodium chloride aqueous solution, thereby enhancing the recovery effect.

[0026] The invention adopts the feeding at the top of the reboiler to reduce the residence time of the material in the reboiler. Meanwhile, the trace polymer generated during heat exchange will follow the fluid back to the azeotropic kettle, and the attachment to the inner wall of the reboiler is reduced. Meanwhile, the azeotropic kettle adopts the azeotropic principle to complete the separation. The azeotropic temperature of triethylamine and water is 75 degrees, which fundamentally reduces the occurrence of side reactions. Meanwhile, most of the water circulating in the reboiler is the water at the bottom of the kettle. The water absorbs heat in the reboiler and then mixes with the triethylamine in the upper layer of the kettle to conduct the heat to the triethylamine and form azeotropy, thereby improving the working efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 The present invention is a structural schematic diagram of a distillation and purification system for aqueous triethylamine;

[0028] Figure 2 This is one of the partial structural schematic diagrams of a distillation and purification system for aqueous triethylamine of the present invention;

[0029] Figure 3 The second partial structural schematic diagram of a distillation and purification system of aqueous triethylamine according to the present invention;

[0030] Figure 4 The third schematic diagram of the partial structure of a distillation and purification system for aqueous triethylamine of the present invention.

[0031] In the figure: 1-aqueous triethylamine solution pipeline, 2-azeotropic kettle, 3-process water pipeline, 4-azeotropic kettle interface level meter, 5-azeotropic kettle liquid level meter, 6-azeotropic circulation pump, 7-azeotropic kettle circulation flow regulating valve, 8-azeotropic kettle circulation flow meter, 9-azeotropic kettle reboiler, 10-azeotropic kettle thermometer, 11-azeotropic kettle condenser, 12-azeotropic kettle condenser vent line, 13-water distributor A, 14-water retaining plate a, 15-water seal, 16-U-type drain pipe, 17-water distributor tank A, 18-vortex preventer A, 19-vortex preventer B, 20-sewage tank, 21-self-cleaning filter, 22-water inlet flow meter, 23-sewage tank water inlet regulating valve, 24-sewage hand valve, 25-sewage Pipeline, 26-density meter a, 27-drainage cut-off valve a, 28-discharge cut-off valve a, 29-water distribution tank level gauge A, 30-sewage delivery pump, 31-sewage tank level gauge, 32-regulating valve a, 33-regulating valve b, 34-feed flow meter, 35-feed tank, 36-feed tank level gauge, 37-triethylamine distillation feed pump, 38-regulating valve c, 39-flow meter a, 40-triethylamine distillation tower, 41-triethylamine distillation kettle, 42-triethylamine distillation kettle level gauge, 43-triethylamine distillation kettle circulation pump, 44-flow meter b, 45-distillation kettle circulation regulating valve, 46-distillation tower reboiler, 47-external regulating valve, 48-flow meter c, 49- triethylamine finished product line, 50-distillation tower condenser, 51-distillation tower condenser vent line, 52-water distributor B, 53-reflux flowmeter, 54-reflux regulating valve, 55-vortex preventer C, 56-density meter b, 57-regulating valve d, 58-water retaining plate B, 59-water distributor B, 60-water distributor level gauge B, 61-vortex preventer B, 62-density meter c, 63-drainage cut-off valve b, 64-discharge cut-off valve b, 65-recovery tower, 66-recovery tower level gauge, 67-recovery tower circulation pump, 68-flowmeter d, 69-inlet manual valve, 70-flowmeter e, 71-sodium chloride external delivery regulating valve, 72-sodium chloride solution external delivery line, 73-recovery tower top pressure Table, 74-recovery tower condenser, 75-vacuum line, 76-recovery tower reflux tank, 77-recovery tower reflux tank level gauge, 78-recovery tower reflux pump, 79-flow meter f, 80-regulating valve e, 81-flow meter g, 82-regulating valve f, 83-triethylamine distillation kettle thermometer, 84-triethylamine distillation tower thermometer Ⅰ, 85-triethylamine distillation tower thermometer Ⅱ, 86-distillation tower top thermometer, 87-recovery tower kettle thermometer, 88-recovery tower middle thermometer, 89-recovery tower top thermometer, 90-recovery tower reboiler, 91-sampling point b, 92-regulating valve g, 93-flow meter h, 94-sodium chloride solution feed line, 95-sampling point a. DETAILED DESCRIPTION

[0032] In order to make the purpose, technical solutions and advantages of the present invention more clear, the present invention is described in detail below with reference to the accompanying drawings and specific embodiments.

[0033] See also Figures 1 to 4 As shown, the present invention provides a distillation and purification system for aqueous triethylamine, comprising a triethylamine azeotropic module, a triethylamine distillation module and a wastewater recovery module, wherein the triethylamine azeotropic module is used for removing impurities and preliminary water separation of the aqueous triethylamine solution; the triethylamine distillation module is connected with the triethylamine azeotropic module, and the triethylamine distillation module is used for purifying the aqueous triethylamine solution to produce a qualified triethylamine solution; the wastewater recovery module is connected with the triethylamine azeotropic module and the triethylamine distillation module, and the wastewater recovery module is used for wastewater recovery and sewage treatment of the triethylamine azeotropic module and the triethylamine distillation module.

[0034] See also Figure 1 , Figure 2 As shown, in an embodiment of the present invention, the triethylamine azeotropic module comprises an azeotropic kettle 2, an azeotropic kettle condenser 11, a water separator A13, a water separator tank A17 and a feed tank 35 connected in sequence by pipelines, wherein the azeotropic kettle 2 has an azeotropic kettle circulation system, and the bottom sewage outlet of the water separator A13 is connected to the wastewater recovery module; the pipeline between the water separator tank A17 and the feed tank 35 is connected to the wastewater recovery module through a bypass pipeline; the bottom discharge port of the water separator tank A17 is provided with a density meter 16, and the density meter 16 is used to detect the density value of the solution discharged from the water separator tank A17; the pipelines connecting the water separator tank A17, the feed tank 35 and the wastewater recovery module are respectively provided with a drainage cut-off valve a27 and a discharge cut-off valve a28, and the drainage cut-off valve a27 and the discharge cut-off valve a28 are automatically switched according to the indication of the density meter 16; the top of the feed tank 35 is provided with a feed tank level gauge 36, and the bottom of the feed tank 35 is connected to the triethylamine distillation module. Preferably, the position of the drain cut-off valve a27 is higher than that of the discharge cut-off valve a28, in order to prevent water from accumulating in the dead zone of the pipeline.

[0035] Furthermore, a water retaining plate a14 is provided at the inner top of the water separator A13, and a liquid inlet and a liquid outlet are provided at the top of the water separator tank A17 on both sides of the water retaining plate a14, the liquid inlet is connected to the azeotropic kettle condenser 11, and the liquid outlet is connected to the water separator tank A17; the bottom sewage outlet of the water separator A13 is provided with a vortex preventer A18, and the vortex preventer A18 is connected to the wastewater recovery module through a U-shaped drain pipe 16; the U-shaped drain pipe 16 is provided with a U-shaped bend, and the height is about half of the position of the water separator A13, at this time, a water seal 15 will be formed at the bottom of the water separator A13. The bottom discharge port of the water separator tank A17 is provided with a vortex preventer B19, and the top of the water separator tank A17 is provided with a water separator tank level gauge A29. The azeotropic kettle condenser 11 is provided with an azeotropic kettle condenser vent line 12.

[0036] In an embodiment of the present invention, the azeotropic kettle circulation system includes an azeotropic circulation pump 6, an azeotropic kettle circulation flow regulating valve 7, an azeotropic kettle circulation flow meter 8 and an azeotropic kettle reboiler 9, wherein the azeotropic kettle reboiler 9 is arranged on the upper part of the azeotropic kettle 2, and the bottom of the azeotropic kettle 2 is connected to the top of the azeotropic kettle reboiler 9 through the azeotropic circulation pump 6 and the azeotropic kettle circulation pipeline, and the azeotropic kettle circulation flow regulating valve 7 and the azeotropic kettle circulation flow meter 8 are arranged on the azeotropic circulation pipeline; the azeotropic kettle circulation pipeline is respectively connected to the wastewater recovery module and the sewage pipeline 25 through two pipelines; the azeotropic kettle 2 is provided with an azeotropic kettle level meter 4, an azeotropic kettle liquid level meter 5 and an azeotropic kettle thermometer 10; the azeotropic kettle 2 is connected to the aqueous triethylamine solution pipeline 1 and the process water pipeline 3.

[0037] See also Figure 1 , Figure 3 As shown, in the embodiment of the present invention, the triethylamine distillation module includes a triethylamine distillation kettle 41, a triethylamine distillation tower 40, a distillation tower condenser 50, a water separator B52 and a water separator B59 connected in sequence, wherein the triethylamine distillation tower 40 is connected to the feed tank 35 through a triethylamine distillation feed pump 37 and a feed pipeline, and a regulating valve c38 and a flowmeter a39 are provided on the feed pipeline; the triethylamine distillation kettle 41 has a distillation kettle circulation system, and the distillation kettle circulation system is connected to the triethylamine finished product line 49. The top of the triethylamine distillation tower 40 is connected to one end of the distillation tower condenser 50 through a pipeline with a distillation tower top thermometer 86, and a triethylamine distillation tower thermometer I84 and a triethylamine distillation tower thermometer II85 are provided on the triethylamine distillation tower 40 at intervals along the height direction. The other end of the distillation tower condenser 50 is connected to the top of the water separator B52 , and a distillation tower condenser vent line 51 is provided at the top of the distillation tower condenser 50 . The inner top of the water separator B52 is provided with a water retaining plate B58 and a feed port and a discharge port located on both sides of the water retaining plate B58, the feed port is connected to the distillation tower condenser 50, and the discharge port is connected to the top of the water separator tank B59, and the top of the water separator tank B59 is provided with a water separator tank level gauge B60; the side wall of the water separator B52 is connected to the top of the triethylamine distillation tower 40 through a reflux pipe, and the reflux flowmeter 53 and the reflux regulating valve 54 are provided on the reflux pipe; the bottom of the water separator B52 is provided with a vortex preventer C55, and the vortex preventer C55 is connected to the wastewater recovery module through a sewage pipeline, and the sewage pipeline is provided with a density meter b56 and a regulating valve d57; the bottom discharge port of the water separator tank B59 is connected to the feed tank 35 and the wastewater recovery module through the discharge pipeline and the drainage pipeline respectively.

[0038] Furthermore, the bottom discharge port of the water diversion tank B59 is provided with a vortex preventer C55 and a density meter c62, and the density meter c62 is used to detect the discharge liquid density value of the water diversion tank B59; the discharge pipeline and the drainage pipeline connected to the bottom discharge port of the water diversion tank B59 are respectively provided with a discharge cut-off valve b64 and a drainage cut-off valve b63, and the discharge cut-off valve b64 and the drainage cut-off valve b63 are switched according to the detection value of the density meter c62.

[0039] In the embodiment of the present invention, the rectifying kettle circulation system comprises a triethylamine rectifying kettle circulation pump 43, a flow meter b44, a rectifying kettle circulation regulating valve 45 and a rectifying tower reboiler 46, wherein the rectifying tower reboiler 46 is arranged at the top of the triethylamine rectifying kettle 41, the bottom of the triethylamine rectifying kettle 41 is connected to the top of the rectifying tower reboiler 46 through the triethylamine rectifying kettle circulation pump 43 and the rectifying tower circulation pipeline, and the rectifying tower circulation pipeline is provided with a flow meter b44, a rectifying kettle circulation regulating valve 45 and a sampling point a95; the rectifying tower circulation pipeline is connected to the triethylamine finished product line 49, and the triethylamine finished product line 49 is provided with an external delivery regulating valve 47 and a flow meter c48. The triethylamine rectifying kettle 41 is provided with a triethylamine rectifying kettle liquid level meter 42 and a triethylamine rectifying kettle thermometer 83.

[0040] See also Figure 1 , Figure 4 As shown, in the embodiment of the present invention, the wastewater recovery module includes a sewage tank 20, a recovery tower 65, a recovery tower condenser 74 and a recovery tower reflux tank 76 which are connected in sequence through pipelines, wherein a recovery tower top pressure gauge 73 and a recovery tower top thermometer 89 are provided on the pipeline between the recovery tower 65 and the recovery tower condenser 74, and the recovery tower condenser 74 is connected to the vacuum line 75; the bottom of the recovery tower reflux tank 76 is respectively connected to the top of the recovery tower 65 and the azeotropic kettle 2 through a recovery tower reflux pump 78 and two reflux pipelines, and a flow meter is provided on the pipeline between the bottom of the recovery tower reflux tank 76 and the recovery tower reflux pump 78. f79 and regulating valve e80, a flowmeter g81 and a regulating valve f82 are provided on the pipeline to the azeotropic kettle 2, a feed port and a recovery tower reflux tank liquid level gauge 77 are provided on the top of the recovery tower reflux tank 76; a recovery tower middle thermometer 88 is provided in the middle of the recovery tower 65, and a recovery tower liquid level gauge 66 and a recovery tower kettle thermometer 87 are provided in the lower part; the middle part of the recovery tower 65 is connected to the sodium chloride solution feed line 94, and the sodium chloride solution feed line 94 is provided with a regulating valve g92 and a flowmeter h93; the lower part of the recovery tower 65 is provided with a recovery tower self-circulation system, and the recovery tower self-circulation system is connected to the sodium chloride solution delivery line 72.

[0041] In an embodiment of the present invention, the recovery tower self-circulation system includes a recovery tower circulation pump 67 and a recovery tower reboiler 90, wherein the water inlet of the recovery tower circulation pump 67 is connected to the bottom of the recovery tower 65, and the water outlet of the recovery tower circulation pump 67 is respectively connected to the bottom of the recovery tower reboiler 90 and the sodium chloride solution delivery line 72 through two pipelines, and the sodium chloride solution delivery line 72 is provided with a flow meter e70 and a sodium chloride delivery regulating valve 71; a sampling point b91 is provided at the water outlet of the recovery tower circulation pump 67; an inlet manual valve 69 and a flow meter d68 are provided on the pipeline connected to the bottom of the recovery tower reboiler 90;

[0042] Specifically, the top of the sewage tank 20 is connected to the azeotropic kettle circulation pipeline, the water separator A13 and the water separator B52; the pipeline connecting the azeotropic kettle circulation pipeline and the sewage tank 20 is provided with a self-cleaning filter 21, a water inlet flowmeter 22 and a sewage tank inlet regulating valve 23 in sequence, and the top of the sewage tank 20 is provided with a sewage tank level gauge 31. The bottom of the sewage tank 20 is connected to the water inlet of the sewage delivery pump 30, and the water outlet of the sewage delivery pump 30 is respectively connected to the top of the recovery tower 65 and the azeotropic kettle 2 through two pipelines, and the pipeline from the sewage delivery pump 30 to the azeotropic kettle 2 is provided with a regulating valve a32, and the pipeline to the recovery tower 65 is provided with a regulating valve b33 and a feed flowmeter 34.

[0043] The present invention provides a distillation and purification system for aqueous triethylamine, and its working principle is:

[0044] The aqueous triethylamine solution is transported to the azeotropic kettle 2 through the aqueous triethylamine solution pipeline 1, and can be fed continuously or intermittently. When the machine is started for the first time, because the water content in the aqueous triethylamine is low and does not meet the azeotropic demand, it is necessary to replenish water through the process water pipeline 3, and the replenishment amount reaches 10%-15% of the reading of the azeotropic kettle interface level meter 4, and the reading of the azeotropic kettle liquid level meter 5 is generally controlled at 25%-70%. Start the azeotropic circulation pump 6, open the azeotropic kettle circulation flow regulating valve 7, make the reading of the azeotropic kettle circulation flow meter 8 reach 20t / h, put into use the steam of the azeotropic kettle reboiler 9, and slowly heat up. When the reading of the azeotropic kettle thermometer 10 reaches 75 degrees, triethylamine and water enter the azeotropic kettle condenser 11 according to the relationship of 9:1, and the azeotropic kettle condenser vent line 12 is provided at the upper part of the condenser tube outlet, the purpose is to discharge a trace amount of light components and non-condensable gases. The condensed triethylamine and water enter the water separator A13. A water retaining plate a14 is provided at the middle position of the top of the water separator A13, and the height is about 1 / 3 of the height of the water separator A13. The purpose is to reduce the water entering the water separator A13 and directly follow the triethylamine into the azeotropic kettle water separator A17. The water outlet at the bottom of the water separator A13 is provided with a vortex preventer A18, and the purpose is to avoid the formation of vortices when draining water, so that the triethylamine is discharged with water. The U-shaped drainage pipe 16 is provided with a U-shaped bend, and the height is about half of the water separator A13. According to P=ρgh, the density of triethylamine is 0.728g / ml, and the density of water is 1g / ml. At this time, a water seal 15 will be formed at the bottom of the water separator A13. The oblique line area in the figure is the water seal 15, and the height is about 1 / 3 of the water separator A13. The purpose is to automatically drain water to the sewage tank 20 according to the pressure without controlling the water level. When the triethylamine is full at the top of the water separator A13, it overflows from the top of the side to the water separator A17. The outlet of the azeotropic circulating pump 6 has a path through a self-cleaning filter 21 to a sewage tank 20. The purpose is that when the azeotropic kettle 2 is operated for a long time, there will be high-density impurities at the bottom, and the impurities in the water need to be removed regularly. The specific operation is to first stop the feeding of the azeotropic kettle 2, and evaporate all the triethylamine in the kettle by azeotropy. When the readings of the azeotropic kettle liquid level meter 5 and the azeotropic kettle interface level meter 4 are close, and the reading of the azeotropic kettle thermometer 10 at the bottom of the azeotropic kettle reaches 80 degrees, it proves that the triethylamine in the azeotropic kettle 2 has been evaporated, and the azeotropic kettle circulation flow regulating valve 7 is closed, and the water inlet regulating valve 23 to the sewage tank is opened, and the reading of the water inlet flow meter 22 is controlled to reach 10t / h, and the self-cleaning filter 21 is put into use; when the reading of the azeotropic kettle liquid level meter 5 reaches 5%, the remaining materials in the azeotropic kettle are mostly large molecular polymers, and the water inlet regulating valve 23 to the sewage tank is closed, and the sewage discharge hand valve 24 is opened, and the sewage is transported to incineration through the sewage discharge pipeline 25; when the operating current of the azeotropic kettle circulation pump 6 drops significantly, it proves that the material has been emptied, and the pump is stopped immediately.A vortex preventer B19 is provided at the bottom discharge port of the water distribution tank A17, and a density meter a26 is provided in the outlet pipeline. The purpose of positioning the drain shut-off valve a27 higher than the discharge shut-off valve a28 is to prevent water from accumulating in the dead zone of the pipeline. When the reading of the water distribution tank level gauge A29 reaches 75%, prepare to cut off the water. Before cutting off the water, confirm the reading of the density meter a26, which is normally around 1g / ml, and open the drain shut-off valve a27. When the reading of the density meter a26 drops to 0.75g / ml, close the drain shut-off valve a27 and open the discharge shut-off valve a28. When the reading of the water distribution tank level gauge A29 reaches 10%, close the discharge shut-off valve a28. There are two main destinations for the sewage in the sewage tank 20. During normal operation, the sewage is returned to the azeotropic kettle 2 through the sewage delivery pump 30 to supplement the water consumed by azeotropy, and the reading of the azeotropic kettle interface level meter 4 is controlled by the regulating valve a32; the sewage is delivered to the recovery tower 65 through the regulating valve b33 and the feed flow meter 34 according to the reading of the sewage tank level meter 31. The feed tank 35 is delivered to the triethylamine distillation tower 40 through the triethylamine distillation feed pump 37 according to the reading of the feed tank level meter 36, and the feed flow is controlled by the regulating valve c38 and the flow meter a39. The reading of the triethylamine distillation kettle level meter 42 is generally controlled at about 30%, in order to avoid excessive water content at the bottom of the kettle and reduce the purification time. Start the triethylamine rectification kettle circulation pump 43, through the rectification circulation regulating valve 45, make the flow meter b44 reading reach 25t / h, open the steam of the distillation tower reboiler 46, and slowly heat up the triethylamine; when the temperature of the triethylamine rectification kettle thermometer 83 reaches 90 degrees, the boiling point of triethylamine, it runs stably for 2 hours. During this period, the reading of the triethylamine rectification kettle thermometer 83 will rise because the vaporized triethylamine has resistance when flowing in the triethylamine distillation tower 40, so the reading of the triethylamine rectification kettle thermometer 83 is generally controlled at 91-93 degrees, and the triethylamine distillation tower thermometer I 84 is above 82 degrees. Under this condition, qualified triethylamine with a water content of less than 300ppm can be produced. The triethylamine distillation tower thermometer II 85 and the distillation tower top thermometer 86 are used as monitoring points. The parameters of the distillation tower feed, reflux, and reboiled steam can be adjusted in advance according to the fluctuation trend of this point to ensure stable and qualified products. After the sampling and analysis at the sampling point a95 are qualified, the external delivery regulating valve 47 is opened, the flowmeter c48 measures the triethylamine output, and the qualified triethylamine is output through the triethylamine finished product line 49. The mixture of triethylamine and water enters the distillation tower condenser 50 from the top of the triethylamine distillation tower 40, and the distillation tower condenser vent line 51 is arranged on the upper part of the condenser tube. The condensed material enters the water separator B52, and the upper part of the water separator B52 is also provided with a water retaining plate B58, the height of the water retaining plate B is one third of the height of the water separator B52, and a reflux port is arranged in the middle of the side, and the reflux amount is controlled by the reflux regulating valve 54 and the reflux flowmeter 53; a vortex preventer c55 is arranged at the bottom of the water separator B52, and a density meter b56 and a regulating valve d57 are arranged on the outlet pipeline of the water separator B52, and the two are in automatic relationship, and the set value is 0.8g / ml, and the water is automatically drained according to the indication of the density meter b56.The remaining material in the water distributor B52 flows into the water distributor tank B59 from the upper side by overflow. The bottom outlet of the water distributor tank B59 is equipped with a vortex preventer B61, and the outlet pipeline is equipped with a density meter c62; when the reading of the water distributor tank level meter B60 reaches 75%, prepare to cut off the water. Before cutting off the water, confirm the reading of the density meter c62D, which is normally around 1g / ml, and open the drainage cut-off valve b63; when the reading of the density meter c62 drops to 0.75g / ml, close the drainage cut-off valve b63 and open the discharge cut-off valve b64; when the reading of the water distributor tank level meter A29 reaches 10%, close the discharge cut-off valve b64. Before the sewage enters the recovery tower 65, the vacuum system is first put into use to make the reading of the pressure gauge 73 at the top of the recovery tower reach -80kpa, and then the recovery tower 65 is fed. When the reading of the recovery tower liquid level meter 66 reaches 70%, the recovery tower circulation pump 67 is started, and the steam of the recovery tower reboiler 90 is put into use. The material is slowly heated up. The reading of the recovery tower kettle thermometer 87 controls the temperature at 75 degrees. The recovery tower middle thermometer 88 and the recovery tower top thermometer 89 are used to monitor the operation of the recovery tower. The parameters of the recovery tower feed, reflux, and reboiled steam can be adjusted in advance according to the fluctuation trend at this point. The mixture of triethylamine and water produced at the top of the recovery tower 65 enters the recovery tower condenser 74, and the condensate enters the recovery tower reflux tank 76. It is used as reflux through the recovery tower reflux pump 78, which is controlled by the regulating valve e80 and the flow meter f79. The other way controls the flow to the azeotropic kettle 2 according to the reading of the recovery tower reflux tank liquid level meter 77, which is controlled by the regulating valve f82 and the flow meter g81. When the recovery tower 65 is running stably, sampling and analysis are performed at sampling point b91 at the outlet of the recovery tower circulation pump. After the analysis result shows that the triethylamine content is less than 0.02%, the sodium chloride delivery regulating valve 71 is opened and the sodium chloride solution is delivered to the downstream workshop through the sodium chloride solution delivery line 72. The flow meter e70 is used to count the amount of sodium chloride solution. The function of the inlet hand valve 69 of the recovery tower reboiler 90 is to adjust the circulation volume to keep the recovery tower circulation pump 67 with sufficient pressure head. If the amount is not limited, the sodium chloride solution may not be delivered due to insufficient pressure head. The lower layer of sodium chloride aqueous solution after the reaction with sodium hydroxide will also contain a small amount of triethylamine after static separation. It enters the recovery tower 65 through the sodium chloride solution feed pipeline 94 and is controlled by the regulating valve g92 and the flow meter h93.

[0045] The present invention adopts the form of a distillation kettle. The materials in the kettle will automatically be stratified due to the density relationship. The top layer is triethylamine, the middle layer is a macromolecular polymer, and the bottom layer is water. The water will contain salts that are easily soluble in water and high-density impurities at the bottom. Triethylamine and water azeotropy enter the condenser of the azeotropic kettle in a ratio of 9:1. The high-density impurities at the bottom of the kettle have a low content. After accumulating for a period of time, the distillation kettle is suspended. According to the indication of the level meter on the side of the kettle, all of them are sent to the sewage tank through a self-cleaning filter, in order to filter the high-density impurities. As for the macromolecular polymer in the middle of the kettle, after the water is drained, it is discharged from the system regularly through the sewage outlet according to the needs. This method solves the blockage problem of the first distillation tower in the prior art, and also solves the blockage problem of the feed sewage of the recovery tower from the root.

[0046] The present invention can produce triethylamine with a water content of less than 300ppm, and the sodium chloride aqueous solution at the bottom also contains a small amount of triethylamine, which is also recycled in a recovery tower, and the triethylamine content in the sodium chloride solution sent out is less than 0.02%. The triethylamine can be recycled, effectively reducing the production and operation cost and improving the competitiveness of the main product vinylene carbonate.

[0047] The present invention adopts a negative pressure mode, and the pressure at the top of the recovery tower is controlled at -80 kPa, so that the temperature of the tower can be controlled at 75 degrees, which can effectively reduce the occurrence of side reactions. The azeotropic kettle and the triethylamine distillation tower of the present invention are not only provided with a water separator, but also provided with a vertical water separation tank, and the stratification of water is checked by a density meter at the bottom of the tank. Before the water separation tank is discharged, water is cut according to the density meter reading, and a vortex preventer is provided at the bottom of the water separation tank to avoid the formation of a vortex to discharge the upper triethylamine, and at the same time reduce the disturbance of water in the triethylamine, so that the water cutting effect is better.

[0048] The present invention adopts an azeotropic method to separate impurities and polymers, and at the same time improves the triethylamine yield and continuous processing efficiency, and does not need to frequently clean the equipment. The azeotropic kettle reboiler is located at the top of the azeotropic kettle, and adopts a top-in and bottom-out method to reduce the occurrence of side reactions. The self-cleaning filter is intermittently used to remove impurities, and the polymer separation and discharge method in the azeotropic kettle ensures the continuous operation of the system. The azeotropic kettle and the triethylamine rectification tower use a water separator and a water separator tank to divide water twice, and the design of the water baffle and the vortex preventer of the water separator, as well as the automatic drainage and overflow of the triethylamine outlet method, improve the water separation effect. The recovery tower adopts negative pressure operation to simultaneously recover the triethylamine in the sewage and the reacted sodium chloride aqueous solution, thereby enhancing the recovery effect.

[0049] The above description is only an embodiment of the present invention and is not intended to limit the protection scope of the present invention. Any modification, equivalent replacement, improvement, expansion, etc. made within the spirit and principle of the present invention are included in the protection scope of the present invention.

Claims

1. A distillation and purification system for aqueous triethylamine, characterized in that, include: Triethylamine azeotropic module, used for impurity removal and preliminary water separation of aqueous triethylamine solution; A triethylamine distillation module is connected to the triethylamine azeotropic module, and the triethylamine distillation module is used for purifying an aqueous triethylamine solution to produce a qualified triethylamine solution; The wastewater recovery module is connected with the triethylamine azeotropic module and the triethylamine distillation module. The wastewater recovery module is used for wastewater recovery and sewage treatment of the triethylamine azeotropic module and the triethylamine distillation module.

2. The distillation and purification system of aqueous triethylamine according to claim 1, characterized in that, The triethylamine azeotropic module comprises an azeotropic kettle (2), an azeotropic kettle condenser (11), a water separator A (13), a water separator tank A (17) and a feed tank (35) which are sequentially connected by pipelines, wherein the azeotropic kettle (2) has an azeotropic kettle circulation system, and the bottom sewage outlet of the water separator A (13) is connected to the wastewater recovery module; the pipeline between the water separator tank A (17) and the feed tank (35) is connected to the wastewater recovery module through a bypass pipeline; the bottom of the water separator tank A (17) A density meter (16) is provided at the discharge port, and the density meter (16) is used to detect the density value of the solution discharged from the water separation tank A (17); a water discharge cut-off valve a (27) and a discharge cut-off valve a (28) are respectively provided on the pipelines connecting the water separation tank A (17) with the feed tank (35) and the wastewater recovery module, and the water discharge cut-off valve a (27) and the discharge cut-off valve a (28) are automatically switched according to the reading of the density meter (16); the feed tank (35) is connected to the triethylamine distillation module.

3. The rectification and purification system of aqueous triethylamine according to claim 2, characterized in that, The inner top of the water separator A (13) is provided with a water retaining plate a (14), and the top of the water separation tank A (17) is provided with a liquid inlet and a liquid outlet located on both sides of the water retaining plate a (14), the liquid inlet is connected to the azeotropic kettle condenser (11), and the liquid outlet is connected to the water separation tank A (17); The bottom sewage outlet of the water separator A (13) is provided with a vortex preventer A (18), and the vortex preventer A (18) is connected to the wastewater recovery module through a U-shaped drainage pipe (16); the bottom discharge outlet of the water separation tank A (17) is provided with a vortex preventer B (19).

4. The distillation and purification system of aqueous triethylamine according to claim 2, characterized in that, The azeotropic kettle circulation system comprises an azeotropic kettle circulation pump (6), an azeotropic kettle circulation flow regulating valve (7), an azeotropic kettle circulation flow meter (8) and an azeotropic kettle reboiler (9), wherein the azeotropic kettle reboiler (9) is arranged on the upper part of the azeotropic kettle (2), the bottom of the azeotropic kettle (2) is connected to the top of the azeotropic kettle reboiler (9) through the azeotropic kettle circulation pump (6) and the azeotropic kettle circulation pipeline, and the azeotropic kettle circulation flow regulating valve (7) and the azeotropic kettle circulation flow meter (8) are arranged on the azeotropic circulation pipeline; the azeotropic kettle circulation pipeline is connected to the wastewater recovery module and the sewage pipeline (25) respectively through two pipelines; The azeotropic kettle (2) is provided with an azeotropic kettle level gauge (4), an azeotropic kettle liquid level gauge (5) and an azeotropic kettle thermometer (10); the azeotropic kettle (2) is connected to an aqueous triethylamine solution pipeline (1) and a process water pipeline (3).

5. The distillation and purification system of aqueous triethylamine according to claim 2, characterized in that, The triethylamine distillation module comprises a triethylamine distillation kettle (41), a triethylamine distillation tower (40), a distillation tower condenser (50), a water separator B (52) and a water separator tank B (59) which are connected in sequence, wherein the triethylamine distillation tower (40) is connected to the feed tank (35) via a triethylamine distillation feed pump (37) and a feed pipeline, and a regulating valve c (38) and a flow meter a (39) are provided on the feed pipeline; the triethylamine distillation kettle (41) has a distillation kettle circulation system, and the distillation kettle circulation system is connected to a triethylamine finished product line (49); The inner top of the water separator B (52) is provided with a water baffle plate B (58) and a feed port and a discharge port located on both sides of the water baffle plate B (58), the feed port is connected to the distillation tower condenser (50), and the discharge port is connected to the water separator tank B (59); the side wall of the water separator B (52) is connected to the top of the triethylamine distillation tower (40) through a reflux pipe; the bottom of the water separator B (52) is connected to the wastewater recovery module through a sewage pipeline; The bottom discharge port of the water separation tank B (59) is connected to the feed tank (35) and the wastewater recovery module respectively through a discharge pipeline and a drainage pipeline.

6. The distillation and purification system of aqueous triethylamine according to claim 5, characterized in that: The bottom discharge port of the water separation tank B (59) is provided with a vortex preventer C (55) and a density meter C (62), and the density meter C (62) is used to detect the density value of the discharge liquid of the water separation tank B (59); A discharge pipe and a drainage pipe connected to the bottom discharge port of the water separation tank B (59) are provided with a discharge cut-off valve b (64) and a drainage cut-off valve b (63) respectively. The discharge cut-off valve b (64) and the drainage cut-off valve b (63) are switched according to the detection value of the density meter c (62).

7. The distillation and purification system of aqueous triethylamine according to claim 5, characterized in that: The rectifying kettle circulation system comprises a triethylamine rectifying kettle circulation pump (43), a flow meter b (44), a rectifying kettle circulation regulating valve (45) and a rectifying tower reboiler (46), wherein the rectifying tower reboiler (46) is arranged at the top of the triethylamine rectifying kettle (41), the bottom of the triethylamine rectifying kettle (41) is connected to the top of the rectifying tower reboiler (46) through the triethylamine rectifying kettle circulation pump (43) and a rectifying tower circulation pipeline, and the rectifying tower circulation pipeline is provided with a flow meter b (44), a rectifying kettle circulation regulating valve (45) and a sampling point a (95); the rectifying tower circulation pipeline is connected to the triethylamine finished product line (49); The triethylamine distillation kettle (41) is provided with a triethylamine distillation kettle liquid level meter (42) and a triethylamine distillation kettle thermometer (83).

8. The distillation and purification system of aqueous triethylamine according to claim 5, characterized in that: The wastewater recovery module comprises a sewage tank (20), a recovery tower (65), a recovery tower condenser (74) and a recovery tower reflux tank (76) which are connected in sequence through pipelines, wherein the bottom of the recovery tower reflux tank (76) is respectively connected to the top of the recovery tower (65) and the azeotropic kettle (2) through a recovery tower reflux pump (78) and two reflux pipelines; the middle of the recovery tower (65) is connected to a sodium chloride solution feed line (94); and a recovery tower self-circulation system is provided at the bottom of the recovery tower (65), and the recovery tower self-circulation system is connected to a sodium chloride solution delivery line (72).

9. The distillation and purification system of aqueous triethylamine according to claim 8, characterized in that: The recovery tower self-circulation system comprises a recovery tower circulation pump (67) and a recovery tower reboiler (90), wherein the water inlet of the recovery tower circulation pump (67) is connected to the bottom of the recovery tower (65), the water outlet of the recovery tower circulation pump (67) is respectively connected to the bottom of the recovery tower reboiler (90) and the sodium chloride solution delivery line (72) through two pipelines, and a sampling point b (91) is provided at the water outlet of the recovery tower circulation pump (67); an inlet manual valve (69) and a flow meter d (68) are provided on the pipeline connected to the bottom of the recovery tower reboiler (90); A recovery tower liquid level gauge (66) and a recovery tower kettle temperature gauge (87) are provided at the lower part of the recovery tower (65).

10. The distillation and purification system of aqueous triethylamine according to claim 8, characterized in that: The bottom of the sewage tank (20) is connected to the water inlet of the sewage delivery pump (30), and the water outlet of the sewage delivery pump (30) is respectively connected to the top of the recovery tower (65) and the azeotropic kettle (2) through two pipelines; the top of the sewage tank (20) is connected to the azeotropic kettle circulation system, the water separator A (13) and the water separator B (52); and the pipeline connecting the sewage tank (20) and the azeotropic kettle circulation system is provided with a self-cleaning filter (21), a water inlet flowmeter (22) and a sewage tank water inlet regulating valve (23) in sequence.

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