Solvent recovery system for vinylene carbonate production

Abstract

The utility model belongs to the technical field of production of vinylene carbonate, and particularly relates to a solvent recovery system for production of vinylene carbonate. Comprising a vinylene carbonate production unit, a gas-liquid separation unit, a condenser, a methyl tert-butyl ether recovery unit and a gas storage tank, and a tail gas discharge pipeline of the vinylene carbonate production unit is sequentially connected with the gas-liquid separation unit, the condenser, the methyl tert-butyl ether recovery unit and the gas storage tank. The gas-liquid separation unit is used for separating nitrogen and a methyl tert-butyl ether solvent in the tail gas, the condenser is used for condensing the tail gas, and condensate returns to the gas-liquid separation unit; the methyl tert-butyl ether recovery unit is used for recovering methyl tert-butyl ether in tail gas, the gas storage tank is used for collecting nitrogen, and the gas storage tank is connected with the vinylene carbonate production unit through a nitrogen circulation pipeline and supplements material pressing nitrogen for the vinylene carbonate production unit. The methyl tert-butyl ether recovery device realizes high-efficiency recovery of methyl tert-butyl ether, reduces tail gas emission and reduces tail gas treatment difficulty.

Description

TECHNICAL FIELD

[0001] The utility model belongs to the production technology field of vinyl ethylene carbonate, and particularly relates to a solvent recovery system for vinyl ethylene carbonate production BACKGROUND

[0002] Vinyl ethylene carbonate is synthesized from chloroethylene carbonate and triethylamine in a solvent methyl tert-butyl ether, the boiling point of the methyl tert-butyl ether is 55.2 degrees under normal pressure, the control temperature for vinyl ethylene carbonate synthesis is 53-55 degrees, the reaction time is 10 hours, and the heat preservation time is 8 hours; because the boiling point is too close to that of the methyl tert-butyl ether, a large amount of the methyl tert-butyl ether will vaporize. The vinyl ethylene carbonate mother liquor and triethylamine hydrochloride after synthesis are separated by a filter press, nitrogen gas is needed to separate the mother liquor, then the methyl tert-butyl ether is added into the filter press to dissolve the vinyl ethylene carbonate on the surface of the triethylamine hydrochloride, then the pressure is reduced, and nitrogen gas is needed to dry after the pressure reduction. During the whole process, a large amount of nitrogen gas will be discharged from the mother liquor tank vent line, and the nitrogen gas will carry a large amount of the methyl tert-butyl ether.

[0003] Vinyl ethylene carbonate is a core film-forming additive for lithium battery electrolyte and a core additive in lithium battery electrolyte, can form a solid electrolyte interface film (SEI film) on the surface of a negative electrode through an electrochemical reaction during the initial charging and discharging of a lithium battery. The SEI film separates the electrode material and the electrolyte, allows lithium ions to transport in the SEI film, enter the electrode surface, and perform embedding or stripping operations. On the other hand, the SEI film can also prevent the passage of solvent molecules in the electrolyte, thereby effectively preventing the co-embedding of solvent molecules and avoiding the damage to the electrode material caused by the co-embedding of solvent molecules. The electrochemical performance of the film is stable, can effectively inhibit the embedding of solvent molecules, thereby avoiding the initiation of the solvation reaction of the electrode material and causing the performance decline of the battery cycle. The existing scheme is to install a condenser on the discharge pipeline of the synthesis kettle and the mother liquor tank to recover the methyl tert-butyl ether. The recovery effect of the methyl tert-butyl ether is not good when the condenser is installed on the discharge pipeline of the synthesis kettle, a large amount of the methyl tert-butyl ether will go to the tail gas treatment unit with the tail gas, and the investment cost of the tail gas treatment equipment is increased, otherwise the emission will not meet the standards. The condenser is installed on the discharge pipeline of the mother liquor tank, nitrogen gas is used to pressurize and dry the methyl tert-butyl ether, the nitrogen gas flow is large, the flow rate is fast, and the entrainment amount is large, so the condensation effect is not good, only a small amount of nitrogen gas can be used for drying, the surface area of the filter screen on the filter press is 7 m2, after the liquid seal is broken, the nitrogen gas will only go to the area with the smallest resistance, and the drying effect is not good in most places. Therefore, there is an urgent need for a solvent recovery system for vinyl ethylene carbonate production, which can more efficiently recover the methyl tert-butyl ether, reduce the tail gas emission, and reduce the difficulty of tail gas treatment. SUMMARY

[0004] The utility model discloses a solvent recovery system for vinylene carbonate production, which realizes efficient recovery of methyl tert-butyl ether, reduces tail gas emission and reduces tail gas treatment difficulty.

[0005] In order to realize the above-mentioned purpose, the utility model adopts the following technical scheme:

[0006] The utility model provides a solvent recovery system for vinylene carbonate production, which comprises a vinylene carbonate production unit, a gas-liquid separation unit, a condenser, a methyl tert-butyl ether recovery unit and a gas storage tank. The tail gas discharge pipeline of the vinylene carbonate production unit is connected with the gas-liquid separation unit, the condenser, the methyl tert-butyl ether recovery unit and the gas storage tank in sequence. The gas-liquid separation unit is used for separating nitrogen and methyl tert-butyl ether solvent in the tail gas. The condenser is used for condensing the tail gas, and the condensed liquid returns to the gas-liquid separation unit. The methyl tert-butyl ether recovery unit is used for recovering methyl tert-butyl ether in the tail gas. The gas storage tank is used for collecting nitrogen. The gas storage tank is connected with the vinylene carbonate production unit through a nitrogen circulation pipeline and supplies pressure nitrogen to the vinylene carbonate production unit.

[0007] The gas-liquid separation unit comprises one or two gas-liquid separation buffer tanks connected in series. Each gas-liquid separation buffer tank is provided with a liquid ring compressor at the gas inlet. Nitrogen circulation is realized through the liquid ring compressor.

[0008] The gas-liquid separation unit is connected with a nitrogen supplement line and a liquid supplement line. The nitrogen supplement line is used for supplementing nitrogen and adjusting pressure of the gas-liquid separation unit. The liquid supplement line is used for supplementing methyl tert-butyl ether to the gas-liquid separation buffer tank or the vinylene carbonate production unit.

[0009] Each gas-liquid separation buffer tank is provided with a liquid level meter, a buffer tank pressure gauge and a safety valve. The top of the gas-liquid separation buffer tank is connected with the gas inlet of the liquid ring compressor through a nitrogen return pipeline. A return adjusting valve is arranged on the nitrogen return pipeline to control the inlet pressure of the liquid ring compressor.

[0010] A liquid level balance pipeline is arranged between the two gas-liquid separation buffer tanks. A liquid level balance adjusting valve is arranged on the liquid level balance pipeline.

[0011] The liquid inlet of the liquid ring compressor is connected with the gas-liquid separation buffer tank through a ring liquid pipeline. A heat exchanger is arranged on the ring liquid pipeline.

[0012] A mist catcher is arranged at the gas outlet of the condenser. The condensed liquid in the condenser flows into the gas-liquid separation buffer tank by gravity.

[0013] The methyl tert-butyl ether recovery unit comprises a coalescence filter and a membrane assembly connected in sequence, and the tail gas is filtered by the coalescence filter and the membrane assembly in sequence and then enters the gas storage tank; the coalescence filter and the membrane assembly are connected with the inlet pipeline of the gas-liquid separation unit through a return branch pipeline, and the filtered liquid is returned to the gas-liquid separation unit through the tail gas.

[0014] A liquid level meter C and an online oxygen analyzer are arranged on the gas storage tank, the oxygen content is measured by the online oxygen analyzer, the gas storage tank is connected with the vinylene carbonate production unit through a nitrogen circulation pipeline, and the gas storage tank provides the pressure nitrogen for the vinylene carbonate production unit.

[0015] The vinylene carbonate production unit comprises a reaction kettle group, a filter press group and a mother liquor tank connected in sequence, the reaction kettle group is used for synthesizing reaction of chloroethylene carbonate and triethylamine in a solvent methyl tert-butyl ether to generate vinylene carbonate, the filter press group is used for separation of the vinylene carbonate mother liquor and triethylamine hydrochloride, and the mother liquor tank is used for collecting the vinylene carbonate mother liquor; tail gas discharge pipelines of the reaction kettle group, the filter press group and the mother liquor tank are connected with the gas-liquid separation unit.

[0016] The reaction kettle group comprises 2n reaction kettles arranged in parallel, a discharge cut-off valve is arranged at the top of each reaction kettle, and a discharge cut-off valve is arranged at the bottom of each reaction kettle.

[0017] The filter press group comprises n filter presses arranged in parallel, a feeding port, an exhaust port, a methyl tert-butyl ether feeding port and a filter press nitrogen inlet are arranged at the upper portion of each filter press, and a mother liquor discharge port is arranged at the bottom of each filter press; control valves are arranged on the feeding port, the exhaust port, the methyl tert-butyl ether feeding port, the filter press nitrogen inlet and the mother liquor discharge port.

[0018] The solvent recovery system for vinylene carbonate production provided by the utility model has the advantages that: the two-stage liquid ring compressor circulates nitrogen, the pressure of the synthesis kettle is controlled at 10kpa, the boiling point of the methyl tert-butyl ether is indirectly improved, the consumption is reduced, the test result shows that the synthesis reaction is almost not affected, the circulating liquid in the liquid ring compressor adopts liquid methyl tert-butyl ether, the coalescence filter and the membrane assembly are arranged at the rear, the content of the methyl tert-butyl ether in the nitrogen is further reduced, and the content of the organic matter in the nitrogen is less than 3%; when the triethylamine hydrochloride is dried by blowing, the nitrogen flow is larger, the drying effect is better, and the recovery amount of the methyl tert-butyl ether is improved. BRIEF DESCRIPTION OF DRAWINGS

[0019] Fig. 1 Fig. 1 is a structural schematic view of the solvent recovery system for vinylene carbonate production of the utility model;

[0020] Fig. 2 Fig. 2 is a structural schematic view of the vinylene carbonate production unit in the utility model.

[0021] Fig. 3 It is a structure schematic view of the gas-liquid separation unit and the methyl tert-butyl ether recovery unit in the utility model.

[0022] In the figure: 1-reaction kettle A, 2-reaction kettle E, 3-reaction kettle F, 4-discharge cut-off valve A, 5-discharge cut-off valve E, 6-discharge cut-off valve F, 7-outlet cut-off valve A, 8-outlet cut-off valve E, 9-outlet cut-off valve F, 10-filter press A, 11-filter press B, 12-filter press C, 13-feeding cut-off valve A, 14-feeding cut-off valve B, 15-feeding cut-off valve C, 16-exhaust regulating valve A, 17-exhaust regulating valve B, 18-exhaust regulating valve C, 19-methyl tert-butyl ether feeding cut-off valve A, 20-methyl tert-butyl ether feeding cut-off valve B, 21-methyl tert-butyl ether feeding cut-off valve C, 22-filter press nitrogen regulating valve A, 23-filter press nitrogen regulating valve B, 24-filter press nitrogen regulating valve C, 25-mother liquor outlet valve A, 26-mother liquor outlet valve B, 27-mother liquor outlet valve C, 28-filter press nitrogen flow meter A, 29-filter press nitrogen flow meter B, 30-filter press nitrogen flow meter C, 31-mother liquor tank, 32-liquid ring compressor A, 33-thermometer A, 34-heat exchanger A, 35-gas-liquid separation buffer tank A, 36-liquid level meter A, 37-buffer tank pressure gauge A, 38-safety valve A, 39-return regulating valve A, 40-nitrogen regulating valve, 41-nitrogen supplement line, 42-evacuation line, 43-liquid supplement regulating valve, 44-liquid supplement line, 45-liquid level balance regulating valve, 46-liquid ring compressor B, 47-thermometer B, 48-heat exchanger B, 49-gas-liquid separation buffer tank B, 50-liquid level meter B, 51-buffer tank pressure gauge B, 52-safety valve B, 53-return regulating valve B, 54-condenser, 55-mist catcher, 56-coalescence filter, 57-hand valve, 58-membrane assembly, 59-discharge hand valve, 60-gas storage tank, 61-online oxygen analyzer, 62-liquid level meter C, 63-evacuation regulating valve, 64-gas-liquid separation unit inlet pressure gauge, 65-liquid supplement line flow meter. DETAILED DESCRIPTION

[0023] In order to make the purpose, technical scheme and advantages of the utility model more clear, the utility model is described in detail below by combining with the drawings and specific embodiments.

[0024] Reference Figs. 1 to 3As shown in the utility model provide a kind of solvent recovery system for vinylene carbonate production, including vinylene carbonate production unit, gas-liquid separation unit, condenser 54, methyl tert-butyl ether recovery unit and gas storage tank 60, wherein the tail gas discharge line of vinylene carbonate production unit is sequentially connected with gas-liquid separation unit, condenser 54, methyl tert-butyl ether recovery unit and gas storage tank 60, gas-liquid separation unit is used for the separation of nitrogen and methyl tert-butyl ether solvent in tail gas, condenser 54 is used for the condensation of tail gas, and condensate returns to gas-liquid separation unit;Methyl tert-butyl ether recovery unit is used for the recovery of methyl tert-butyl ether in tail gas, gas storage tank 60 is used for collecting nitrogen, and gas storage tank 60 is connected with vinylene carbonate production unit by nitrogen circulation pipeline, and nitrogen is supplied to vinylene carbonate production unit.

[0025] Referring to Fig. 2 As shown in the utility model, in the embodiment, the vinylene carbonate production unit includes reaction kettle group, filter press group and mother liquor tank 31 connected in sequence, wherein the reaction kettle group is used for the synthesis reaction of chloroethylene carbonate and triethylamine in solvent methyl tert-butyl ether to generate vinylene carbonate;The filter press group is used for the separation of vinylene carbonate mother liquor and triethylamine hydrochloride;The mother liquor tank 31 is used for collecting vinylene carbonate mother liquor;The tail gas discharge line of reaction kettle group, filter press group and mother liquor tank 31 is connected with gas-liquid separation unit.

[0026] In the embodiment of the utility model, the reaction kettle group includes 2n reaction kettles arranged in parallel, the top of each reaction kettle is provided with a discharge cut-off valve, and the bottom is provided with a discharge cut-off valve;The filter press group includes n filter presses arranged in parallel, each filter press is provided with a stirring device, the upper part of the filter press is provided with a feed inlet, an exhaust port, a methyl tert-butyl ether feed inlet and a filter press nitrogen inlet, and the bottom is provided with a mother liquor discharge port;Control valve is arranged on the feed inlet, exhaust port, methyl tert-butyl ether feed inlet, filter press nitrogen inlet and mother liquor discharge port.

[0027] The embodiment is described by taking six reactors and three filter presses as a set, the six reactors are reactor A1, … reactor E2 and reactor F3 respectively, the top and bottom of reactor A1 are respectively provided with discharge cut-off valve A4 and discharge cut-off valve A7, the top and bottom of reactor E2 are respectively provided with discharge cut-off valve E5 and discharge cut-off valve E8, and the top of reactor F3 is respectively provided with discharge cut-off valve F6 and discharge cut-off valve F9. The three filter presses are filter press A10, filter press B11 and filter press C12, wherein the pipelines connected to the upper part of filter press A10 are respectively provided with feed cut-off valve A13, exhaust regulating valve A16, methyl tert-butyl ether feed cut-off valve A19 and filter press nitrogen regulating valve A22, and the front end of filter press nitrogen regulating valve A22 is provided with filter press nitrogen flow meter A28, and the bottom of filter press A10 is provided with mother liquor discharge valve A25. The pipelines connected to the upper part of filter press B11 are respectively provided with feed cut-off valve B14, exhaust regulating valve B17, methyl tert-butyl ether feed cut-off valve B20 and filter press nitrogen regulating valve B23, wherein the front end of filter press nitrogen regulating valve B23 is also provided with filter press nitrogen flow meter B29; the bottom of filter press B11 is provided with mother liquor discharge valve B26. The pipelines connected to the upper part of filter press C12 are respectively provided with feed cut-off valve C15, exhaust regulating valve C18, methyl tert-butyl ether feed cut-off valve C21 and filter press nitrogen regulating valve C24, and the front end of filter press nitrogen regulating valve C24 is also provided with filter press nitrogen flow meter C30; the bottom of filter press C12 is provided with mother liquor discharge valve C27.

[0028] Referring to Fig. 3 In the embodiment of the utility model, the gas-liquid separation unit includes one or two gas-liquid separation buffer tanks connected in series, each gas-liquid separation buffer tank is provided with a liquid ring compressor at the gas inlet, and nitrogen circulation is realized through the liquid ring compressor.

[0029] Further, the gas-liquid separation unit is connected with a nitrogen supplement line 41 and a liquid supplement line 44, the nitrogen supplement line 41 is used for supplementing nitrogen and adjusting pressure of the gas-liquid separation unit, and a nitrogen regulating valve 40 is arranged on the nitrogen supplement line 41; the liquid supplement line 44 is used for supplementing methyl tert-butyl ether to each filter press in the gas-liquid separation buffer tank or the vinylene carbonate production unit, a liquid supplement regulating valve 43 is arranged on the pipeline connected with the gas-liquid separation unit, and a liquid supplement line flow meter 65 is arranged on the pipeline connected with the vinylene carbonate production unit.

[0030] Further, each gas-liquid separation buffer tank is provided with a liquid level meter, a buffer tank pressure gauge and a safety valve, the top of the gas-liquid separation buffer tank is connected with the gas inlet of the liquid ring compressor through a nitrogen return pipeline, a return regulating valve is arranged on the nitrogen return pipeline, and the inlet pressure of the liquid ring compressor is controlled through the return regulating valve;

[0031] Specifically, the embodiment takes two-stage gas-liquid separation buffer tanks as an example for illustration, and the two-stage gas-liquid separation buffer tanks are gas-liquid separation buffer tank A 35 and gas-liquid separation buffer tank B 49; the front end of the gas-liquid separation buffer tank A 35 is provided with a liquid ring compressor A 32, the gas inlet of the liquid ring compressor A 32 is connected with a tail gas discharge pipeline of the vinylene carbonate production unit, and a gas-liquid separation unit inlet pressure gauge 64 is arranged at the gas inlet of the liquid ring compressor A 32; the gas-liquid outlet of the liquid ring compressor A 32 is connected with the feed inlet of the gas-liquid separation buffer tank A 35, the liquid inlet of the liquid ring compressor A 32 is connected with the liquid discharge port of the gas-liquid separation buffer tank A 35 through a ring liquid pipeline A, and a thermometer A 33 and a heat exchanger A 34 are arranged on the ring liquid pipeline A. The gas-liquid separation buffer tank A 35 is connected with the gas inlet pipeline of the liquid ring compressor A 32 through a return line A, and a return adjusting valve A 39 is arranged on the return line A; the gas-liquid separation buffer tank A 35 is further provided with a liquid level gauge A 36, a buffer tank pressure gauge A 37 and a safety valve A 38. The front end of the gas-liquid separation buffer tank B 49 is provided with a liquid ring compressor B 46, the gas inlet of the liquid ring compressor B 46 is connected with the gas discharge port of the gas-liquid separation buffer tank A 35, the gas-liquid outlet of the liquid ring compressor B 46 is connected with the feed inlet of the gas-liquid separation buffer tank B 49, the liquid inlet of the liquid ring compressor B 46 is connected with the liquid discharge port of the gas-liquid separation buffer tank B 49 through a ring liquid pipeline B, and a thermometer B 47 and a heat exchanger B 48 are arranged on the ring liquid pipeline B; the gas-liquid separation buffer tank B 49 is connected with the gas inlet pipeline of the liquid ring compressor B 46 through a return line B, and a return adjusting valve B 53 is arranged on the return line B; the gas-liquid separation buffer tank B 49 is further provided with a liquid level gauge B 50, a buffer tank pressure gauge B 51 and a safety valve B 52, and the safety valve A 38 and the safety valve B 52 are connected with a vent line 42. A liquid level balance pipeline is arranged between the gas-liquid separation buffer tank A 35 and the gas-liquid separation buffer tank B 49, a liquid level balance adjusting valve 45 is arranged on the liquid level balance pipeline, and the liquid level balance pipeline is connected with a liquid supplement line 44.

[0032] As shown in Fig. 3 In the embodiment of the utility model, the gas outlet of condenser 54 is provided with a mist catcher 55, and the condensate in the condenser 54 flows into the gas-liquid separation buffer tank B 49 by gravity.

[0033] As shown in Fig. 3 In the embodiment of the utility model, the methyl tert-butyl ether recovery unit comprises coalescing filter 56 and membrane assembly 58 connected in sequence, and the tail gas is filtered by coalescing filter 56 and membrane assembly 58 in sequence and then enters into gas storage tank 60; coalescing filter 56 and membrane assembly 58 are connected with the inlet pipeline of the gas-liquid separation unit through a return branch pipeline, and the filtered liquid is returned to the gas-liquid separation unit through the tail gas.

[0034] Further, the gas tank 60 is provided with a liquid level meter C62 and an online oxygen analyzer 61, the oxygen content is measured through the online oxygen analyzer 61, the gas tank 60 is connected with the vinylene carbonate production unit through a nitrogen circulating pipeline, and the gas tank 60 provides pressure nitrogen gas for the vinylene carbonate production unit.

[0035] The working principle of the solvent recovery system for vinylene carbonate production is as follows:

[0036] Methyl tert-butyl ether is added to the gas-liquid separation buffer tank A 35 and the gas-liquid separation buffer tank B 49 through the liquid supplement line 44, and the amount of liquid supplement is controlled through the liquid supplement regulating valve 43; when the readings of the liquid level gauge A 36 and the liquid level gauge B 50 reach 30%, the liquid supplement regulating valve 43 is closed. After the system is provided with nitrogen gas, the nitrogen gas regulating valve 40 is opened, and nitrogen gas is supplemented through the nitrogen supplement line 41; when the reading of the gas-liquid separation unit inlet pressure gauge 64 reaches 0.03 MPa, the liquid ring compressor A 32 is started, and the liquid ring compressor A 32 is controlled by frequency conversion; in the early stage, the liquid ring compressor A 32 is started at low load, and the inlet and outlet pressure requirements are met; the reading of the gas-liquid separation unit inlet pressure gauge 64 is controlled to be 0.01 MPa through the return regulating valve A 39; when the reading of the buffer tank pressure gauge A 37 on the gas-liquid separation buffer tank A 35 reaches 0.05 MPa, the liquid ring compressor B 46 is started, and the pressure on both sides is controlled through the return regulating valve B 53; when the reading of the buffer tank pressure gauge B 51 on the gas-liquid separation buffer tank B 49 reaches 0.25 MPa, the nitrogen supplement regulating valve 40 is closed. In the later stage, the nitrogen supplement regulating valve 40 is automatically adjusted according to the gas-liquid separation unit inlet pressure gauge 64. When the reaction kettle A 1, ……, the reaction kettle E 2 and the reaction kettle F 3 are put into operation, the corresponding discharge cut-off valves A 4, ……, the discharge cut-off valves E 5 and the discharge cut-off valves F 6 are opened, and the tail gas directly enters the gas-liquid separation unit. When the reading of the buffer tank pressure gauge B 51 on the gas-liquid separation buffer tank B 49 exceeds 0.3 MPa, the vent regulating valve 63 is opened to control the system pressure. After the reaction is completed, the corresponding reaction kettle bottom discharge cut-off valves A 7, ……, the discharge cut-off valves E 8 and the discharge cut-off valves F 9 are opened, the inlet cut-off valves A 13, the inlet cut-off valves B 14 and the inlet cut-off valves C 15 of the pressure filters A 10, the pressure filters B 11 and the pressure filters C 12 provided with the reaction kettle are opened, and the corresponding exhaust regulating valves A 16, the exhaust regulating valves B 17 and the exhaust regulating valves C 18 of each pressure filter are opened to ensure that the material flows from the reaction kettle to the pressure filter by gravity, and after the material transfer is completed, the discharge cut-off valves A 4, ……, the discharge cut-off valves E 5 and the discharge cut-off valves F 6 of each reaction kettle are closed, the discharge cut-off valves A 7, ……, the discharge cut-off valves E 8 and the discharge cut-off valves F 9 are closed, and the exhaust regulating valves A 16, the exhaust regulating valves B 17 and the exhaust regulating valves C 18 of each pressure filter are closed. The mother liquor discharge valves A 25, the mother liquor discharge valves B 26 and the mother liquor discharge valves C 27 of each pressure filter are opened, the pressure filter nitrogen regulating valves A 22, the pressure filter nitrogen regulating valves B 23 and the pressure filter nitrogen regulating valves C 24 of each pressure filter are slightly opened, the material is pressed into the mother liquor tank 31, the valve opening degree is 5%, the purpose is to slowly increase the pressure in each pressure filter to 0.25 MPa, and the nitrogen supplement regulating valve 40 is slowly opened to make the system nitrogen pressure run stably. The readings of the pressure filter nitrogen flow gauges A 28, the pressure filter nitrogen flow gauges B 29 and the pressure filter nitrogen flow gauges C 30 of each pressure filter are checked to confirm the state in each pressure filter.When the flow meter suddenly becomes large, it proves that there is a part of the area in the filter press has broken the mother liquor seal, at this time, close the filter press nitrogen regulating valve A22, filter press nitrogen regulating valve B23 and filter press nitrogen regulating valve C24 of each filter press. Open the corresponding exhaust regulating valve A16, exhaust regulating valve B17 and exhaust regulating valve C18 of each filter press, the valve opening degree is 5%, slow pressure relief, reduce the impact of high pressure in the filter press on the stable operation of the system, open the corresponding methyl tert-butyl ether feed cut-off valve A19, methyl tert-butyl ether feed cut-off valve B20 and methyl tert-butyl ether feed cut-off valve C21 of each filter press. When the liquid supplementing line flow meter 65 reaches the quantitative value, close the methyl tert-butyl ether feed cut-off valve A19, methyl tert-butyl ether feed cut-off valve B20 and methyl tert-butyl ether feed cut-off valve C21. Open the stirring motor on the corresponding filter press, so that the triethylamine hydrochloride and methyl tert-butyl ether are in full contact, and the carbonic acid ethylene ester on the surface of the triethylamine hydrochloride is dissolved into the methyl tert-butyl ether. After stirring for twenty minutes, stop the stirring motor, close the corresponding exhaust regulating valve A16, exhaust regulating valve B17 and exhaust regulating valve C18 on each filter press, open the mother liquor discharge valve A25, mother liquor discharge valve B26 and mother liquor discharge valve C27 on each filter press, slightly open the filter press nitrogen regulating valve A22, filter press nitrogen regulating valve B23 and filter press nitrogen regulating valve C24 on each filter press, the valve opening degree is 5%, repeat the pressure charging, when the filter press nitrogen flow meter A28, filter press nitrogen flow meter B29 and filter press nitrogen flow meter C30 on each filter press suddenly become large, gradually fully open the corresponding filter press nitrogen regulating valve A22, filter press nitrogen regulating valve B23 and filter press nitrogen regulating valve C24, the purpose is to ensure the drying effect of the filter screen with a surface area of 7㎡ in the filter press through high flow nitrogen, and recover as much solvent as possible. After blowing and drying for half an hour, close the filter press nitrogen regulating valve A22, filter press nitrogen regulating valve B23 and filter press nitrogen regulating valve C24 of each filter press, open the corresponding exhaust regulating valve A16, exhaust regulating valve B17 and exhaust regulating valve C18 on each filter press, the valve opening degree is 5%, slow pressure relief. When reaching 10kpa, close the exhaust regulating valve A16, exhaust regulating valve B17 and exhaust regulating valve C18, then unload the triethylamine hydrochloride in the filter press. The liquid ring compressor A32 and liquid ring compressor B46 of the nitrogen circulation system are variable frequency compressors, according to the required amount of nitrogen, adjust the load, so that the pressure gauge B51 of the buffer tank is stable at 0.25-0.3mpa, in this range, it can minimize the nitrogen supplement and exhaust gas emission when each reaction kettle and filter press is put into use or cut out. The temperature of the thermometer A33 and thermometer B47 at the inlet of each liquid ring compressor is controlled at-10 degrees through the-20 degree refrigerated brine flow adjustment of heat exchanger A34 and heat exchanger B48.Safety valve A 38 and safety valve B 52 are arranged on the top of gas-liquid separation buffer tank A 35 and gas-liquid separation buffer tank B 49, liquid level balance regulating valve 45 is arranged between the two gas-liquid separation buffer tanks, and the purpose is to balance the liquid levels of the two tanks, and to transfer the methyl tert-butyl ether rising in gas-liquid separation buffer tank B 49 into gas-liquid separation buffer tank A 35. In addition to the liquid supplement control before starting, liquid supplement regulating valve 43 can be opened when the liquid level of the recovered methyl tert-butyl ether is high, and the nitrogen gas enters the condenser 54, the condenser 54 is connected with -40-degree cold salt, the upper outlet of the condenser 54 is provided with a mist eliminator 55, and the condensed liquid is gravity-fed into the gas-liquid separation buffer tank B 49. The nitrogen gas enters the coalescing filter 56, the coalescing filter is provided with a hand valve 57 at the bottom, the hand valve 57 is slightly opened, and the liquid after coalescing is returned to the inlet of the liquid ring compressor A 32 together with a small amount of gas, the nitrogen gas passes through the membrane assembly 58, and the membrane assembly 58 is also provided with a discharge hand valve 59 on the side. The nitrogen gas finally enters the gas storage tank 60, the gas storage tank 60 is provided with a liquid level meter C 62 and an online oxygen analyzer 61, and the oxygen content is controlled; if the oxygen content is too high, the system is replaced again to avoid danger.

[0037] The two-stage liquid ring compressor is adopted in the application, the tail gas recovery during the reaction process and the purging and drying are considered at the same time, the recovery effect is better, the consumption of nitrogen gas is lower, the content of organic matters in the tail gas is effectively reduced, the tail gas emission is reduced, and the tail gas treatment difficulty is reduced.

[0038] The above only describes the implementation manners of the present application, and is not used to limit the protection scope of the present application. Any modification, equivalent replacement, improvement, expansion, etc. made within the spirit and principle of the present application are included in the protection scope of the present application.

Claims

1. A solvent recovery system for vinylene carbonate production, characterized in that: The invention comprises a vinylene carbonate production unit, a gas-liquid separation unit, a condenser (54), a methyl tert-butyl ether recovery unit and a gas storage tank (60), wherein the tail gas discharge pipeline of the vinylene carbonate production unit is connected to the gas-liquid separation unit, the condenser (54), the methyl tert-butyl ether recovery unit and the gas storage tank (60) in sequence; the gas-liquid separation unit is used to separate nitrogen and methyl tert-butyl ether solvent in the tail gas; the condenser (54) is used to condense the tail gas, and the condensate is returned to the gas-liquid separation unit; the methyl tert-butyl ether recovery unit is used to recover methyl tert-butyl ether in the tail gas; the gas storage tank (60) is used to collect nitrogen; the gas storage tank (60) is connected to the vinylene carbonate production unit through a nitrogen circulation pipeline, and replenishes the pressurized nitrogen for the vinylene carbonate production unit.

2. The solvent recovery system for vinylene carbonate production according to claim 1, characterized in that: The gas-liquid separation unit includes one or two gas-liquid separation buffer tanks connected in series. The gas inlet of each gas-liquid separation buffer tank is equipped with a liquid ring compressor, and nitrogen circulation is achieved through the liquid ring compressor.

3. The solvent recovery system for vinylene carbonate production according to claim 2, characterized in that: The gas-liquid separation unit is connected to a nitrogen replenishment line (41) and a liquid replenishment line (44). The nitrogen replenishment line (41) is used to replenish nitrogen and adjust the pressure of the gas-liquid separation unit; and the liquid replenishment line (44) is used to replenish methyl tert-butyl ether to the gas-liquid separation buffer tank or the vinylene carbonate production unit.

4. The solvent recovery system for vinylene carbonate production according to claim 2, characterized in that: Each of the gas-liquid separation buffer tanks is equipped with a liquid level gauge, a buffer tank pressure gauge and a safety valve. The top of the gas-liquid separation buffer tank is connected to the air inlet of the liquid ring compressor through a nitrogen return pipeline. A return regulating valve is provided on the nitrogen return pipeline to control the inlet pressure of the liquid ring compressor through the return regulating valve. A liquid level balancing pipeline is provided between the two gas-liquid separation buffer tanks, and a liquid level balancing regulating valve (45) is provided on the liquid level balancing pipeline.

5. The solvent recovery system for vinylene carbonate production according to claim 2, characterized in that: The liquid inlet of the liquid ring compressor is connected to the gas-liquid separation buffer tank through a ring liquid pipeline, and a heat exchanger is provided on the ring liquid pipeline.

6. The solvent recovery system for vinylene carbonate production according to claim 2, characterized in that: A mist catcher (55) is provided at the gas outlet of the condenser (54), and the condensate in the condenser (54) flows into the gas-liquid separation buffer tank by gravity.

7. The solvent recovery system for vinylene carbonate production according to claim 2, characterized in that: The methyl tert-butyl ether recovery unit comprises a coalescing filter (56) and a membrane assembly (58) connected in sequence, and the tail gas is filtered by the coalescing filter (56) and the membrane assembly (58) in sequence and then enters the gas storage tank (60); the coalescing filter (56) and the membrane assembly (58) are connected to the inlet pipeline of the gas-liquid separation unit through a return branch pipeline, and the filtered liquid is returned to the gas-liquid separation unit through the tail gas.

8. The solvent recovery system for vinylene carbonate production according to claim 2, characterized in that: The gas storage tank (60) is provided with a liquid level meter C (62) and an online oxygen analyzer (61), and the oxygen content is measured by the online oxygen analyzer (61). The gas storage tank (60) is connected to the vinylene carbonate production unit through a nitrogen circulation pipeline, and the gas storage tank (60) provides pressurized nitrogen for the vinylene carbonate production unit.

9. The solvent recovery system for vinylene carbonate production according to claim 1, characterized in that: The vinylene carbonate production unit comprises a reactor group, a filter press group and a mother liquid tank (31) connected in sequence, wherein the reactor group is used for carrying out a synthesis reaction between vinylene carbonate and triethylamine in a solvent of methyl tert-butyl ether to generate vinylene carbonate; the filter press group is used for separating vinylene carbonate mother liquor from triethylamine hydrochloride; the mother liquid tank (31) is used for collecting the vinylene carbonate mother liquor; and the tail gas emission pipelines of the reactor group, the filter press group and the mother liquid tank (31) are all connected to the gas-liquid separation unit.

10. The solvent recovery system for vinylene carbonate production according to claim 9, characterized in that: The reactor group includes 2n reactors arranged in parallel, each reactor is provided with a discharge shut-off valve at the top and a discharge shut-off valve at the bottom; The filter press unit includes n filter presses arranged in parallel, each filter press is provided with a feed port, an exhaust port, a methyl tert-butyl ether feed port and a filter press nitrogen inlet at the top, and a mother liquor discharge port at the bottom; the feed port, the exhaust port, the methyl tert-butyl ether feed port, the filter press nitrogen inlet and the mother liquor discharge port are all provided with control valves.

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