MVR (mechanical vapor recompression) evaporation and concentration system for methanol-containing material

Abstract

The invention relates to an MVR (mechanical vapor recompression) evaporation and concentration system for a methanol-containing material, which comprises a material tank for storing the material, a feeding pump for conveying the material, a material evaporation system for evaporating and concentrating the material, and a water heater for heating water to generate steam by taking secondary steam generated by the material evaporation system as a heat source, the steam compressor, the live steam source, the tail gas condenser and the vacuum pump are used for heating water, and the steam compressor, the live steam source, the tail gas condenser and the vacuum pump are used for pressurizing and heating steam produced by the water heater. Pure steam enters the steam compressor to be compressed into high-pressure and high-temperature compressed steam, methanol-containing materials are evaporated and concentrated through the compressed steam, live steam is only used as a supplementary heat source, the use amount of the live steam can be effectively reduced, the cost is saved, meanwhile, the methanol explosion risk is also reduced, and the energy consumption is reduced. Corrosion of methanol to a mechanical structure of the compressor is reduced, and normal and stable operation of a system is guaranteed.

Description

Technical Field

[0001] The present invention relates to the technical field of evaporation concentration equipment, and particularly relates to an MVR evaporation concentration system for methanol-containing materials. Background Art

[0002] Methanol is the simplest saturated monohydric alcohol in structure. It is a colorless, transparent, volatile liquid with an alcohol smell, and can be miscible with water and various organic solvents. It is one of the basic chemical raw materials and is widely used in the fields of energy, medicine, agriculture, etc. Among them, in the fields of medicine and pesticides, methanol is a solvent or intermediate for drug production, used to dissolve the active ingredients of drugs or synthesize intermediates, which also makes the waste liquid after drug production contain methanol. For example, in the production process of vitamin C, in its fermentation, extraction, ester conversion and other processes, methanol is the main reaction solvent, used for the extraction of gulonic acid, esterification and conversion processes. In the synthesis process of sodium ascorbate, methanol is used in the crystallization process and subsequent processes to assist in removing impurities and promoting product purification. A large amount of waste liquid is generated during the production process of vitamin C, usually called VC waste liquid, such as the mother liquor after extracting gulonic acid, the conversion mother liquor of vitamin C and the refined mother liquor, etc. The VC waste liquid contains useful substances such as vitamin C, gulonic acid, sorbitol, polysaccharides, proteins, oxalic acid, methanol, etc. If the VC waste liquid is directly discharged, it will cause serious environmental pollution. If it is directly treated by sewage treatment, it will cause waste of resources. Therefore, technicians have developed various methods to reuse the VC waste liquid, such as recovering gulonic acid and oxalic acid from the VC waste liquid, or producing microbial protein and polypeptide organic fertilizer using the VC waste liquid. However, due to the low concentration of the VC waste liquid, no matter which method is used, the VC waste liquid needs to be evaporated and concentrated first.

[0003] Since the VC waste liquid contains methanol, and methanol is a volatile substance, when the VC waste liquid is evaporated and concentrated, the methanol in the VC waste liquid will also evaporate and mix with the evaporated secondary steam in the form of gaseous methanol. This results in that the MVR evaporator cannot be used when evaporating and concentrating the VC waste liquid, because: 1. The saturated vapor pressure of methanol is much higher than that of water. During the compression process, when the secondary steam and methanol gas are compressed together by the compressor, during the compression by the compressor, the methanol gas mixed therein will first liquefy, while the secondary steam is still in a superheated state. The liquefied droplets will impact the impeller of the compressor during the operation of the compressor, causing vibration or mechanical damage. At the same time, methanol is also likely to cause corrosion damage to mechanical equipment.

[0004] 2. Methanol is a flammable substance and there is a certain explosion risk. When the MVR steam compressor compresses the mixed gas, the temperature of the secondary steam will rise, increasing the possibility of methanol combustion and explosion.

[0005] Therefore, when evaporating and concentrating methanol-containing materials at present, only a multi-effect evaporator can be used, with live steam as the heat source to evaporate and concentrate methanol-containing materials. In this way, the secondary steam separated by the evaporator can only be discharged after washing and condensation. This method has a large consumption of live steam, high energy consumption, and high cost. Summary of the Invention

[0006] In summary, in order to overcome the deficiencies of the prior art, the present invention provides an MVR evaporation and concentration system for methanol-containing materials. It uses the secondary steam containing methanol gas generated during the evaporation of methanol-containing materials as the heat source to heat water, generating pure saturated steam. The pure saturated steam enters the steam compressor and is compressed into high-pressure and high-temperature compressed steam. The compressed steam is used to evaporate and concentrate methanol-containing materials. After the system is stable, live steam is only used as a supplementary heat source, which can effectively reduce the consumption of live steam, save costs, reduce the risk of methanol explosion, and reduce the corrosion of the mechanical structure of the compressor by methanol, ensuring the normal and stable operation of the system.

[0007] To solve the above technical problems, the technical solution adopted by the present invention is as follows: An MVR evaporation and concentration system for methanol-containing materials, comprising: A feeding device, including a material tank for storing methanol-containing materials and a feeding pump with an inlet end connected to the material tank, A material evaporation system for evaporating and concentrating methanol-containing materials. The outlet end of the feeding pump is connected to the inlet of the material evaporation system, the outlet of the material evaporation system is connected to the inlet of the discharging pump, and the outlet of the discharging pump is connected to the thick slurry discharging pipeline, A water evaporator that uses the secondary steam generated by the material evaporation system as the heat source to heat water to generate steam. The air inlet of the water evaporator is connected to the secondary steam outlet of the material evaporation system, A steam compressor that compresses the steam generated by the water evaporator. The air inlet of the steam compressor is connected to the steam outlet of the water evaporator, and the air outlet of the steam compressor is connected to the air inlet of the material evaporation system, A live steam source, and the live steam source is connected to the air inlet of the material evaporation system and the air supplement port of the steam compressor through a live steam pipeline, A tail gas condenser. The air inlet of the tail gas condenser is connected to the non-condensable gas outlet of the water evaporator, the water inlet of the tail gas condenser is connected to the cooling water inlet pipeline, and the water outlet of the tail gas condenser is connected to the cooling water return pipeline, A vacuum pump. The air inlet of the vacuum pump is connected to the air outlet of the tail gas condenser, and the air outlet of the vacuum pump is emptied.

[0008] The technical solution of the present invention can also be implemented as follows: The material evaporation system includes a second-effect evaporator, a first-effect evaporator, a third-effect evaporator, and a fourth-effect evaporator that are connected in sequence along the material flow direction. The first-effect evaporator and the second-effect evaporator are both falling-film evaporators, and the third-effect evaporator and the fourth-effect evaporator are both forced-circulation evaporators. The second-effect evaporator uses the secondary steam separated by the first-effect evaporator as a heat source to evaporate and concentrate the material. The feed inlet of the second-effect evaporator is connected to the outlet end of the feed pump. The steam inlet of the second-effect evaporator is connected to the secondary steam outlet of the first-effect evaporator. The secondary steam outlet of the second-effect evaporator is connected to the steam inlet of the water evaporator. The first-effect evaporator, the third-effect evaporator, and the fourth-effect evaporator use steam as a heat source to evaporate and concentrate the material. The steam inlets of the first-effect evaporator, the third-effect evaporator, and the fourth-effect evaporator are all connected to the compressed steam pipeline. The compressed steam pipeline is connected to the outlet of the steam compressor. The raw steam source is connected to the compressed steam pipeline through the raw steam pipeline. The secondary steam outlets of the third-effect evaporator and the fourth-effect evaporator are both connected to the steam inlet of the water evaporator.

[0009] The technical solution of the present invention can also be implemented as follows: The water evaporator includes a water heater and a circulation pump. The shell-side steam inlet of the water heater is connected to the secondary steam outlets of the second-effect evaporator, the third-effect evaporator, and the fourth-effect evaporator through pipelines. The tube-side water inlet of the water heater is connected to the condensate outlets of the first-effect evaporator, the third-effect evaporator, and the fourth-effect evaporator through pipelines. The tube-side water outlet of the water heater is connected to the inlet of the circulation pump. The outlet of the circulation pump is connected to the tube-side water inlet of the water heater. The tube-side steam outlet of the water heater is connected to the inlet of the steam compressor.

[0010] The technical solution of the present invention can also be implemented as follows: The tube-side water outlet of the water heater is connected to the inlet of the spray pump through a pipeline. The outlet of the spray pump is connected to the spray inlet of the steam compressor.

[0011] The technical solution of the present invention can also be implemented as follows: It further includes a make-up water pipeline and a water outlet pipeline. The make-up water pipeline is connected to the water supply system and the tube-side water inlet of the water heater. The outlet of the circulation pump is connected to the water outlet pipeline. A make-up water valve is provided on the make-up water pipeline, and a water outlet valve is provided on the water outlet pipeline. A water level gauge for detecting the tube-side water level is provided on the water heater. The water level gauge is electrically connected to the make-up water valve and the water outlet valve, and the make-up water valve and the water outlet valve are controlled and adjusted through the tube-side water level in the water heater.

[0012] The technical solution of the present invention can also be implemented as follows: The condensate outlet of the fan of the steam compressor is connected to the inlet of the fan condensate tank, the outlet of the fan condensate tank is connected to the inlet of the fan condensate pump, the outlet of the fan condensate pump is connected to the inlet of the circulation pump. A fan condensate level gauge is provided on the fan condensate tank, and the fan condensate level gauge is electrically connected to the fan condensate pump to control and adjust the fan condensate pump through the water level in the fan condensate tank.

[0013] The technical solution of the present invention can also be implemented as follows: It further includes a preheating system. The preheating system includes a condensate preheater and a non-condensable gas preheater. The feed inlet of the condensate preheater is connected to the discharge outlet of the feed pump, the discharge outlet of the condensate preheater is connected to the feed inlet of the non-condensable gas preheater, and the discharge outlet of the non-condensable gas preheater is connected to the feed inlet of the second-effect evaporator. The preheating medium inlet of the condensate preheater is connected to the discharge outlet of the condensate pump, and the preheating medium outlet of the condensate preheater is connected to the drainage system. The inlet of the condensate pump is connected to the discharge outlet of the condensate tank for collecting and storing condensate. The inlet of the condensate tank is connected to the condensate outlet of the second-effect evaporator, the condensate outlet of the water evaporator, the condensate outlet of the tail gas condenser, and the condensate outlet of the non-condensable gas preheater. The inlet of the non-condensable gas preheater is connected to the non-condensable gas outlet of the water heater of the water evaporator, and the outlet of the non-condensable gas preheater is connected to the inlet of the tail gas condenser.

[0014] The technical solution of the present invention can also be implemented as follows: A condensate level gauge is provided on the condensate tank, and a condensate preheating valve is provided on the pipeline connecting the discharge outlet of the condensate pump and the preheating medium inlet of the condensate preheater. The condensate level gauge is electrically connected to the condensate preheating valve to control and adjust the condensate preheating valve through the water level in the condensate tank.

[0015] The technical solution of the present invention can also be implemented as follows: It further includes a second-effect pre-preheater. The feed inlet of the second-effect pre-preheater is connected to the outlet end of the feed pump, the discharge outlet of the second-effect pre-preheater is connected to the feed inlet of the second-effect evaporator, the inlet of the second-effect pre-preheater is connected to the non-condensable gas outlet of the second-effect evaporator, and the outlet of the second-effect pre-preheater is connected to the inlet of the water evaporator.

[0016] The technical solution of the present invention can also be implemented as follows: It further includes a first-effect pre-preheater. The feed inlet of the first-effect pre-preheater is connected to the discharge outlet of the second-effect evaporator, the discharge outlet of the first-effect pre-preheater is connected to the feed inlet of the first-effect evaporator, the inlet of the first-effect pre-preheater is connected to the non-condensable gas outlets of the first-effect evaporator, the third-effect evaporator, and the fourth-effect evaporator, and the outlet of the first-effect pre-preheater is connected to the inlet of the second-effect evaporator.

[0017] The technical solution of the present invention can also be implemented as follows: A fourth-effect liquid level gauge for detecting the liquid level of the fourth-effect evaporator is provided on the separator of the fourth-effect evaporator. A third-effect feed valve is provided on the pipeline connecting the discharge port of the first-effect evaporator and the feed port of the third-effect evaporator. The fourth-effect liquid level gauge is electrically connected to the third-effect feed valve, and the third-effect feed valve is controlled and adjusted by the liquid level in the separator of the fourth-effect evaporator.

[0018] The technical solution of the present invention can also be implemented as follows: A first-effect feed valve is provided on the pipeline connecting the discharge port of the second-effect evaporator and the feed port of the first-effect preheater. A first-effect liquid level gauge for detecting the liquid level of the first-effect evaporator is provided on the heater of the first-effect evaporator. The first-effect liquid level gauge is electrically connected to the first-effect feed valve, and the first-effect feed valve is controlled and adjusted by the liquid level in the heater of the first-effect evaporator.

[0019] The technical solution of the present invention can also be implemented as follows: The condensate tank has an air outlet, and the air outlet of the condensate tank is connected to the air inlet of the non-condensable gas preheater through a pipeline. The beneficial effects of the present invention are as follows:

[0020] 1. In the present invention, the secondary steam containing methanol gas generated during the evaporation of the methanol-containing material is used as a heat source to heat water, generating pure saturated steam. The pure saturated steam enters the steam compressor and is compressed into high-pressure and high-temperature compressed steam. The compressed steam is used to heat the methanol-containing material to evaporate and concentrate it. After the system is stable, the live steam is only used as a supplementary heat source, which can effectively reduce the consumption of live steam, save costs, reduce the risk of methanol explosion, and reduce the corrosion of the mechanical structure of the compressor by methanol, ensuring the normal and stable operation of the system.

[0021] 2. The second-effect preheater of the present invention uses the non-condensable gas generated by the second-effect evaporator to preheat the material, which can recover the waste heat of the non-condensable gas generated by the second-effect evaporator. The first-effect preheater of the present invention uses the non-condensable gas generated by the first-effect evaporator to preheat the material, realizing the recycling and reuse of the non-condensable gas generated by the first-effect evaporator. The non-condensable gas preheater is provided in the present invention, which uses the waste heat in the non-condensable gas discharged from the water evaporator to preheat the material. The settings of the second-effect preheater, the first-effect preheater and the non-condensable gas preheater can fully recover the waste heat in the non-condensable gas, improve the energy utilization rate and reduce the energy consumption.

[0022] 3. The first-effect evaporator and the second-effect evaporator of the present invention are falling-film evaporators, and the third-effect evaporator and the fourth-effect evaporator of the present invention are forced-circulation evaporators. The combination of the falling-film evaporator and the forced-circulation evaporator can ensure that the material has sufficient effective heat transfer temperature difference and evaporation intensity at different concentrations, effectively improving the evaporation efficiency.

[0023] 4. The first-effect evaporator, third-effect evaporator, and fourth-effect evaporator of the present invention use pure steam as a heat source to evaporate and concentrate the material. Then, the condensed water formed after the pure steam exchanges heat is pure condensed water, which can be directly used to produce pure steam. Therefore, the condensed water discharged from the first-effect evaporator, third-effect evaporator, and fourth-effect evaporator directly enters the water evaporator. The steam entering the steam compressor of the present invention is pure steam, and the condensed water generated when it is compressed and heated is also pure condensed water, which directly enters the water evaporator to produce pure steam. The pure steam is pressurized and heated by the compressor and then re-enters the first-effect evaporator, third-effect evaporator, and fourth-effect evaporator to heat the material. Therefore, the present invention can realize the recycling of condensed water, save water resources, and reduce costs.

[0024] 5. The second-effect evaporator of the present invention uses the secondary steam separated by the separator of the first-effect evaporator as a heat source to evaporate and concentrate the material. The secondary steam contains methanol gas and other impurities. Therefore, after the secondary steam heats the material in the second-effect evaporator and condenses, methanol and other impurities exist in the generated condensed water. Therefore, the condensed water generated by the second-effect evaporator cannot be transported to the water evaporator. The condensed water containing impurities is stored in the condensed water tank. The water evaporator of the present invention uses the secondary steam separated by the second-effect evaporator, third-effect evaporator, and fourth-effect evaporator as a heat source to heat water. The water is heated and evaporated to produce pure steam, and the secondary steam releases heat and cools down and condenses. This kind of condensed water contains impurities and cannot be used to produce steam. Therefore, the condensed water of the second-effect evaporator and the condensed water of the water evaporator are both collected in the condensed water tank and then enter the condensed water preheater to preheat the material, realizing the recovery and utilization of the waste heat in the condensed water containing impurities.

[0025] 6. The tail gas condenser of the present invention is provided with a pressure sensor. The pressure sensor detects the pressure in the tail gas condenser, that is, the system vacuum degree. A make-up gas pipeline communicating with this pipeline is provided on the pipeline connecting the gas outlet of the tail gas condenser and the gas inlet of the vacuum pump. A vacuum regulating valve is provided on the make-up gas pipeline. The pressure sensor is electrically connected to the vacuum regulating valve. The vacuum regulating valve is controlled and adjusted by the pressure in the tail gas condenser, thereby realizing the regulation and control of the system vacuum degree, enabling the present invention to operate under appropriate vacuum degree conditions and ensuring the stability of equipment operation.

[0026] 7. The present invention is provided with a make-up water pipeline and a water outlet pipeline. When the water level in the tube side of the water evaporator is too low, water can be supplemented to the water evaporator through the make-up water pipeline to meet the evaporation requirement and ensure the steam requirement of the system. When the water level in the tube side of the water evaporator is too high, the excess water in the water evaporator can be discharged through the water outlet pipeline. The setting of the make-up water pipeline and the water outlet pipeline can effectively ensure the water balance in the system.

[0027] 8. The structure of the present invention is simple, easy to use, novel in concept and low in cost. It can effectively realize the MVR evaporation and concentration of methanol-containing materials, reduce the steam consumption during the evaporation and concentration of the materials, reduce energy consumption and lower the evaporation and concentration cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 It is a schematic structural diagram of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0029] The present invention will be further described in detail below with reference to the accompanying drawings.

[0030] As Figure 1 shown, an MVR evaporation and concentration system for methanol-containing materials includes a material tank 1 for storing methanol-containing materials, a feed pump 2 with an inlet end connected to the material tank 1, a preheating system for preheating the materials, the preheating system includes a condensate preheater 3 and a non-condensable gas preheater 4, a material evaporation system for evaporating and concentrating the methanol-containing materials, the material evaporation system includes a second-effect evaporator 8, a first-effect evaporator 7, a third-effect evaporator 9 and a fourth-effect evaporator 10 connected in series along the material flow direction. The first-effect evaporator 7 and the second-effect evaporator 8 are both falling-film evaporators, and the third-effect evaporator 9 and the fourth-effect evaporator 10 are both forced-circulation evaporators. A water evaporator 11 that uses secondary steam to heat water to generate pure steam, a steam compressor 12 that compresses pure steam to generate high-temperature and high-pressure compressed steam, a condensate tank 28 for recovering condensate, a fan condensate tank 21 for recovering the fan condensate of the steam compressor 12, a second-effect preheater 18 that uses the non-condensable gas flowing out of the second-effect evaporator 8 to preheat the materials, a first-effect preheater 19 that uses the non-condensable gas flowing out of the first-effect evaporator 7, the third-effect evaporator 9 and the fourth-effect evaporator 10 to preheat the materials. The first-effect preheater 19, the second-effect preheater 18, the non-condensable gas preheater 4 and the tail gas condenser 5 are all shell-and-tube heat exchangers, and the condensate preheater 3 is a plate heat exchanger.

[0031] The first-effect evaporator 7 includes a first-effect heat exchanger 71, a first-effect separator 72 and a first-effect circulation pump 73. The first-effect heat exchanger 71 is a shell-and-tube heat exchanger. The tube-side gas outlet of the first-effect heat exchanger 71 is connected to the inlet of the first-effect separator 72. The discharge port of the first-effect separator 72 and the tube-side discharge port at the lower end of the first-effect heat exchanger 71 are connected to the inlet of the first-effect circulation pump 73. The discharge port of the first-effect circulation pump 73 is connected to the tube-side inlet at the upper end of the first-effect heat exchanger 71. The discharge port of the first-effect circulation pump 73 is also connected to a first-effect discharge pipeline 74. The upper end of the first-effect separator 72 has a secondary steam outlet. The first-effect heat exchanger 71 has a shell-side inlet, a non-condensable gas outlet and a condensate outlet. The shell-side inlet, the non-condensable gas outlet and the condensate outlet are all connected to the shell side of the first-effect heat exchanger 71.

[0032] The double-effect evaporator 8 includes a double-effect heat exchanger 81, a double-effect separator 82, and a double-effect circulation pump 83. The double-effect heat exchanger 81 is a shell-and-tube heat exchanger. The outlet of the tube side of the double-effect heat exchanger 81 is connected to the inlet of the double-effect separator 82. The outlet of the double-effect separator 82 and the outlet of the tube side at the lower end of the double-effect heat exchanger 81 are connected to the inlet of the double-effect circulation pump 83. The outlet of the double-effect circulation pump 83 is connected to the inlet of the tube side at the upper end of the double-effect heat exchanger 81. The outlet of the double-effect circulation pump 83 is also connected to a double-effect discharge pipeline 84. The upper end of the double-effect separator 82 has a secondary steam outlet. The double-effect heat exchanger 81 has a shell-side inlet, a non-condensable gas outlet, and a condensate outlet. The shell-side inlet, the non-condensable gas outlet, and the condensate outlet are all connected to the shell side of the double-effect heat exchanger 81.

[0033] The triple-effect evaporator 9 includes a triple-effect heat exchanger 91, a triple-effect separator 92, and a triple-effect forced circulation pump 93. The triple-effect heat exchanger 91 is a shell-and-tube heat exchanger. The outlet of the tube side at the upper end of the triple-effect heat exchanger 91 is connected to the inlet of the triple-effect separator 92. The outlet at the lower end of the triple-effect separator 92 is connected to the inlet of the triple-effect forced circulation pump 93. The outlet of the triple-effect forced circulation pump 93 is connected to the inlet of the tube side at the lower end of the triple-effect heat exchanger 91. The upper end of the triple-effect separator 92 is provided with a secondary steam outlet. The triple-effect heat exchanger 91 has a shell-side inlet, a non-condensable gas outlet, and a condensate outlet. The shell-side inlet, the non-condensable gas outlet, and the condensate outlet are all connected to the shell side of the triple-effect heat exchanger 91.

[0034] The quadruple-effect evaporator 10 includes a quadruple-effect heat exchanger 101, a quadruple-effect separator 102, and a quadruple-effect forced circulation pump 103. The quadruple-effect heat exchanger 101 is a shell-and-tube heat exchanger. The outlet of the tube side at the upper end of the quadruple-effect heat exchanger 101 is connected to the inlet of the quadruple-effect separator 102. The outlet at the lower end of the quadruple-effect separator 102 is connected to the inlet of the quadruple-effect forced circulation pump 103. The outlet of the quadruple-effect forced circulation pump 103 is connected to the inlet of the tube side at the lower end of the quadruple-effect heat exchanger 101. The upper end of the quadruple-effect separator 102 is provided with a secondary steam outlet. The quadruple-effect heat exchanger 101 has a shell-side inlet, a non-condensable gas outlet, and a condensate outlet. The shell-side inlet, the non-condensable gas outlet, and the condensate outlet are all connected to the shell side of the quadruple-effect heat exchanger 101. A quadruple-effect level gauge 104 for detecting the liquid level in the quadruple-effect separator 102 is provided on the quadruple-effect separator 102. The outlet of the first-effect circulation pump 73 is connected to the inlet of the triple-effect forced circulation pump 93 through a first-effect discharge pipeline 74. A triple-effect feed valve 75 is provided on the first-effect discharge pipeline 74. The quadruple-effect level gauge 104 is electrically connected to the triple-effect feed valve 75, and the triple-effect feed valve 75 is controlled and adjusted by the liquid level in the separator of the quadruple-effect evaporator 10.

[0035] The water evaporator 11 includes a water heater 110 and a circulation pump 111. The water heater 110 is a shell-and-tube heat exchanger. The outlet of the shell side at the lower end of the water heater 110 is connected to the inlet of the circulation pump 111, and the outlet of the circulation pump 111 is connected to the inlet of the shell side at the upper end of the water heater 110. The water heater 110 has an inlet for shell-side gas, an outlet for non-condensable gas, an outlet for gas in the tube side, and an outlet for condensate. The inlet for shell-side gas, the outlet for non-condensable gas, and the outlet for condensate are all connected to the shell side of the water heater 110, and the outlet for gas in the tube side is connected to the tube side of the water heater 110. The outlet of the shell side of the water heater 110 is connected to the inlet of the spray pump 20 through a pipeline, and the outlet of the spray pump 20 is connected to the spray inlet of the steam compressor 12 through a pipeline. A spray flowmeter and a spray valve are provided on this pipeline. The spray flowmeter is electrically connected to the spray valve, and the spray valve can be controlled and adjusted according to the flow rate in the pipeline.

[0036] The outlet end of the feed pump 2 is connected to the feed inlet of the condensate preheater 3. The outlet of the condensate preheater 3 is connected to the feed inlet of the non-condensable gas preheater 4. The outlet of the non-condensable gas preheater 4 is connected to the feed inlet of the second-effect preheater 18. The outlet of the second-effect restricted preheater is connected to the tube-side feed inlet of the second-effect heat exchanger 81 of the second-effect evaporator 8. The outlet of the second-effect circulation pump 83 is connected to the feed inlet of the first-effect preheater 19 through a second-effect discharge pipeline 84. The outlet of the first-effect preheater 19 is connected to the tube-side feed inlet of the first-effect heat exchanger 71. The outlet of the first-effect circulation pump 73 is connected to the feed inlet of the third-effect forced circulation pump 93 through a first-effect discharge pipeline 74. The outlet of the third-effect separator 92 is connected to the feed inlet of the fourth-effect forced circulation pump 103 through a third-effect discharge pipeline. The outlet of the fourth-effect separator 102 is connected to the feed inlet of the discharge pump 13. The outlet of the discharge pump 13 is connected to the thick slurry discharge pipeline 14. According to the above connection method, the material containing methanol flows in the flow direction of the material tank 1 → feed pump 2 → condensate preheater 3 → non-condensable gas preheater 4 → second-effect preheater 18 → second-effect evaporator 8 → first-effect preheater 19 → first-effect evaporator 7 → third-effect evaporator 9 → fourth-effect evaporator 10 → thick slurry discharge pipeline 14.

[0037] The shell-side inlet of the first-effect heat exchanger 71, the shell-side inlet of the third-effect heat exchanger 91, and the shell-side inlet of the fourth-effect heat exchanger 101 are all connected to the compressed steam pipeline 17. The compressed steam pipeline 17 is connected to the outlet of the steam compressor 12. The compressed steam pipeline 17 is also connected to the live steam source 15 through the live steam pipeline 16, and a live steam valve is provided on the live steam pipeline 16. The inlet of the steam compressor 12 is connected to the tube-side outlet of the water heater 110. The non-condensable gas outlets of the first-effect heat exchanger 71, the third-effect heat exchanger 91, and the fourth-effect heat exchanger 101 are all connected to the inlet of the first-effect preheater 19. The outlet of the first-effect preheater 19 is connected to the shell-side inlet of the second-effect heat exchanger 81. The secondary steam outlet of the first-effect separator 72 is connected to the shell-side inlet of the second-effect heat exchanger 81. The non-condensable gas outlet of the second-effect heat exchanger 81 is connected to the inlet of the second-effect preheater 18. The outlet of the second-effect preheater 18, the secondary steam outlets of the second-effect separator 82, the third-effect separator 92, and the fourth-effect separator 102 are all connected to the shell-side inlet of the water heater 110. The non-condensable gas outlet of the water heater 110 is connected to the inlet of the non-condensable gas preheater 4. The outlet of the non-condensable gas preheater 4 is connected to the inlet of the tail gas condenser 5. The outlet of the tail gas condenser 5 is connected to the inlet of the vacuum pump 6, and the outlet of the vacuum pump 6 is emptied. The inlet of the tail gas condenser 5 is connected to the cooling water inlet pipeline, and the outlet of the tail gas condenser 5 is connected to the cooling water return pipeline. The condensate tank 28 has an outlet, and the outlet of the condensate tank 28 is connected to the inlet of the non-condensable gas preheater 4 through a pipeline.

[0038] The condensate outlet of the second-effect heat exchanger 81, the condensate outlet of the second-effect preheater 18, the condensate outlet of the water heater 110, the condensate outlet of the non-condensable gas preheater 4, and the condensate outlet of the tail gas condenser 5 are connected to the water inlet of the condensate tank 28. The water outlet of the condensate tank 28 is connected to the water inlet of the condensate pump 29. The water outlet of the condensate pump 29 is connected to the preheating medium inlet of the condensate preheater 3. The preheating medium outlet of the condensate preheater 3 is connected to the sewage treatment system or the drainage system. A condensate level gauge 30 is provided on the condensate tank 28. A condensate preheating valve 31 is provided on the pipeline connecting the water outlet of the condensate pump 29 and the preheating medium inlet of the condensate preheater 3. The condensate level gauge 30 is electrically connected to the condensate preheating valve 31, and the condensate preheating valve 31 is controlled and adjusted by the water level in the condensate tank 28. The shell side of the second-effect heat exchanger 81 flows with the secondary steam separated by the first-effect separator 72. The secondary steam contains impurities such as materials and methanol gas. Therefore, the condensate flowing out of the second-effect heat exchanger 81 contains impurities and is not pure condensate. Similarly, the non-condensable gas flowing out of the second-effect heat exchanger 81 is used as the preheating medium in the second-effect preheater 18 to preheat the material, and the condensate after the non-condensable gas condenses contains impurities. The shell side of the water heater 110 flows with the secondary steam separated by the second-effect separator 82, the third-effect separator 92, and the fourth-effect separator 102. The condensate formed by the condensation of the secondary steam still contains impurities. The non-condensable gas preheater 4 uses the non-condensable gas flowing out of the water heater 110 as the preheating medium, and the condensate after the non-condensable gas condenses contains impurities. The tail gas condenser 5 condenses the non-condensable gas flowing out of the non-condensable gas preheater 4, and the condensate flowing out of it contains impurities. That is to say, the condensate tank 28 recovers the condensate containing impurities. This condensate preheats the material in the condensate preheater 3 and then is transported to the drainage system for direct discharge, or is sent to the sewage system for purification and then discharged.

[0039] The condensate outlet of the first-effect heat exchanger 71, the condensate outlet of the first-effect preheater 19, the condensate outlet of the third-effect heat exchanger 91, and the condensate outlet of the fourth-effect heat exchanger 101 are connected to the tube-side inlet of the water heater 110. The fan condensate outlet of the steam compressor 12 is connected to the inlet of the fan condensate tank 21. The outlet of the fan condensate tank 21 is connected to the inlet of the fan condensate pump 22. The outlet of the fan condensate pump 22 is connected to the inlet of the circulation pump 111 of the water evaporator 11. The first-effect heat exchanger 71, the third-effect heat exchanger 91, and the fourth-effect heat exchanger 101 use live steam or pure compressed steam as the heat source to heat the material. The condensate after condensation is pure condensate without impurities. Therefore, the condensate generated by the first-effect heat exchanger 71, the condensate generated by the third-effect heat exchanger 91, and the condensate generated by the fourth-effect heat exchanger 101 are all transported to the water evaporator 11 and reheated and evaporated again. The first-effect preheater 19 uses the non-condensable gas flowing out of the first-effect heat exchanger 71 as the heat source to preheat the material, and the condensate it generates is also free of impurities. Therefore, this condensate can also be directly transported to the water evaporator 11. The steam entering the steam compressor 12 is pure steam. Therefore, the condensate generated after its compression is also pure condensate. Therefore, the fan condensate stored in the fan condensate tank 21 is pure condensate, which is directly transported into the water evaporator 11 by the fan condensate pump 22 and reheated and evaporated again to generate pure steam. A fan condensate level gauge 23 is provided on the fan condensate tank 21. The fan condensate level gauge 23 is electrically connected to the fan condensate pump 22, and the fan condensate pump 22 is controlled and adjusted by the water level in the fan condensate tank 21.

[0040] The tube-side inlet of the water heater 110 is connected to the water supply system through a make-up water pipeline 24. The outlet of the circulation pump 111 is connected to an outlet pipeline 26. A make-up water valve 25 is provided on the make-up water pipeline 24. An outlet valve 27 is provided on the outlet pipeline 26. A water level gauge 112 for detecting the tube-side water level is provided on the water heater 110. The water level gauge 112 is electrically connected to the make-up water valve 25 and the outlet valve 27, and the make-up water valve 25 and the outlet valve 27 are controlled and adjusted by the tube-side water level in the water heater 110.

[0041] A first-effect level gauge 76 for detecting the tube-side liquid level of the first-effect heat exchanger 71 is provided on the first-effect heat exchanger 71 of the first-effect evaporator 7. A first-effect feed valve 75 is provided on the first-effect discharge pipeline 84. The first-effect level gauge 76 is electrically connected to the first-effect feed valve 75, and the first-effect feed valve 75 is controlled and adjusted by the material level in the heater of the first-effect evaporator 7.

[0042] During the initial operation, the methanol-containing material is evaporated and concentrated using the live steam provided by the live steam source 15 as the heat source. Open the live steam valve and start the vacuum pump 6. The live steam enters the compressed steam pipeline 17 through the live steam pipeline 16, and then enters the shell sides of the first-effect heat exchanger 71, the third-effect heat exchanger 91, and the fourth-effect heat exchanger 101 along the compressed steam pipeline 17 respectively.

[0043] Start the feed pump 2. The feed pump 2 transports the methanol-containing material in the material tank 1 to the condensate preheater 3, then through the non-condensable gas preheater 4, and then through the preheater before the second effect, and finally enters the tube side of the second-effect heat exchanger 81. Since there is insufficient condensate in the condensate tank 28 and insufficient non-condensable gas in the system during the initial startup of the system, and little non-condensable gas is discharged from the second-effect heat exchanger 81, at this time, the condensate preheater 3, the non-condensable gas preheater 4, and the preheater before the second effect basically achieve the purpose of not preheating the material. The second-effect heat exchanger 81 uses the secondary steam separated by the first-effect separator 72 as the heat source to heat the material. At this time, there is no material in the first-effect evaporator 7, so no secondary steam is generated, and no heat source gas flows into the second-effect heat exchanger 81. Therefore, at this time, the second-effect evaporator 8 does not work, and the material entering the second-effect heat exchanger 81 directly enters the preheater before the first effect 19 through the second-effect discharge pipeline 84. Since there is no material in the first-effect evaporator 7, the live steam in the shell side of the first-effect heat exchanger 71 directly flows out from the non-condensable gas outlet and enters the preheater before the first effect 19. Then, in the preheater before the first effect 19, the material is preheated using the live steam, and the temperature of the material rises. Since the live steam is directly used to preheat the material at this time and the live steam temperature is high, the material temperature can rise rapidly.

[0044] The material flowing out from the preheater before the first effect 19 directly enters the tube side of the first-effect heat exchanger 71 and exchanges heat with the live steam in the shell side of the first-effect heat exchanger 71. The live steam heats the material, and the temperature of the material rises. The water in the material evaporates, and the evaporated secondary steam and part of the material enter the first-effect separator 72 from the tube side gas outlet of the first-effect heat exchanger 71. Gas-liquid separation is carried out in the first-effect separator 72. The separated secondary steam enters the shell side of the second-effect heat exchanger 81, and the separated material is again fed into the tube side of the first-effect heat exchanger 71 from the upper tube side feed port of the first-effect heat exchanger 71 under the action of the first-effect circulation pump 73 for heating. The material flowing out from the tube side discharge port of the first-effect heat exchanger 71 is again fed into the tube side of the first-effect heat exchanger 71 from the upper tube side feed port of the first-effect heat exchanger 71 under the action of the first-effect circulation pump 73 for heating. This cycle repeats, causing the material to be evaporated and concentrated in the first-effect evaporator 7.

[0045] Open the triple-effect feed valve 75. The material concentrated by the first-effect evaporator 7 flows along the first-effect discharge pipeline 74 and enters the tube side of the triple-effect heat exchanger 91 under the action of the triple-effect forced circulation pump 93. The live steam in the compressed steam pipeline 17 enters the shell side of the triple-effect heat exchanger 91. In the triple-effect heat exchanger 91, the live steam in the shell side heats the material in the tube side. The material temperature rises and water evaporates. After that, the heated material and the evaporated secondary steam enter the triple-effect separator 92 together. Gas-liquid separation is carried out in the triple-effect separator 92. The separated secondary steam flows out from the secondary steam outlet of the triple-effect separator 92. The separated material enters the feed port of the triple-effect forced circulation pump 93 from the discharge port of the triple-effect separator 92 and re-enters the tube side of the triple-effect heat exchanger 91 under the action of the triple-effect forced circulation pump 93. This cycle repeats, causing the material to be concentrated by evaporation in the triple-effect evaporator 9.

[0046] The material concentrated by the triple-effect evaporator 9 enters the tube side of the quadruple-effect heat exchanger 101 under the action of the quadruple-effect forced circulation pump 103. The live steam in the compressed steam pipeline 17 enters the shell side of the quadruple-effect heat exchanger 101. In the quadruple-effect heat exchanger 101, the live steam in the shell side heats the material in the tube side. The material temperature rises and water evaporates. After that, the heated material and the evaporated secondary steam enter the quadruple-effect separator 102 together. Gas-liquid separation is carried out in the quadruple-effect separator 102. The separated secondary steam flows out from the secondary steam outlet of the quadruple-effect separator 102. The separated material enters the feed port of the quadruple-effect forced circulation pump 103 from the discharge port of the quadruple-effect separator 102 and re-enters the tube side of the quadruple-effect heat exchanger 101 under the action of the quadruple-effect forced circulation pump 103. This cycle repeats, causing the material to be concentrated by evaporation in the quadruple-effect evaporator 10. Start the discharge pump 13. The material concentrated by the quadruple-effect evaporator 10 is discharged from the thick slurry discharge pipeline 14 under the action of the discharge pump 13. A thick slurry discharge valve and a thick slurry flowmeter are provided on the thick slurry discharge pipeline 14. The thick slurry flowmeter is electrically connected to the thick slurry discharge valve. The thick slurry discharge valve is controlled and adjusted by the thick slurry flow in the thick slurry discharge pipeline 14. The thick slurry discharge pipeline 14 is communicated with the feed port of the quadruple-effect forced circulation pump 103 through a return pipeline. A return valve is provided on the return pipeline. When the concentration of the material discharged from the thick slurry discharge pipeline 14 does not meet the discharge requirement, start the return valve and re-concentrate the material by evaporation in the quadruple-effect evaporator 10 through the return pipeline.

[0047] The secondary steam separated by the first-effect separator 72 enters the shell side of the second-effect heat exchanger 81, where it heats the material in the tube side of the second-effect heat exchanger 81. The material is heated, evaporated, and concentrated. The evaporated secondary steam enters the second-effect separator 82 for gas-liquid separation. The separated secondary steam flows out from the secondary steam outlet of the second-effect separator 82. The separated material and the material flowing out from the tube-side outlet of the second-effect heat exchanger 81 re-enter the tube side of the second-effect heat exchanger 81 from the tube-side inlet at the upper end of the second-effect heat exchanger 81 under the action of the circulation pump 111. This cycle continues, causing the material to be evaporated and concentrated in the second-effect evaporator 8. The material evaporated and concentrated by the second-effect evaporator 8 enters the tube side of the first-effect preheater 19. The non-condensable gas discharged from the non-condensable gas outlet of the first-effect heat exchanger 71 enters the shell side of the first-effect preheater 19. In the first-effect preheater 19, the non-condensable gas in the shell side heats the material in the tube side, achieving preheating of the material before it enters the first-effect evaporator 7.

[0048] The secondary steam separated by the second-effect separator 82, the secondary steam separated by the third-effect separator 92, and the secondary steam separated by the fourth-effect separator 102 enter the shell side of the water heater 110 through the pipeline. The condensate outlets of the first-effect heat exchanger 71, the first-effect preheater 19, the third-effect heat exchanger 91, and the fourth-effect heat exchanger 101 enter the tube side of the water heater 110. In the water heater 110, the secondary steam in the shell side is used to heat the condensate in the tube side. The condensate is heated, evaporated, and generates pure steam. The pure steam enters the steam compressor 12 from the tube-side gas outlet of the water heater 110. The steam compressor 12 compresses the pure steam, increasing its pressure and temperature to form high-quality pure steam. The high-quality pure steam enters the compressed steam pipeline 17 from the gas outlet of the steam compressor 12, and then re-enters the first-effect heat exchanger 71, the second-effect heat exchanger 81, and the third-effect heat exchanger 91 along the compressed steam pipeline 17 to participate in the heating of the material.

[0049] The non-condensable gas flowing out from the non-condensable gas outlet of the water heater 110 enters the shell side of the non-condensable gas preheater 4, heating the material in the tube side of the non-condensable gas preheater 4 to achieve preheating of the material. The material is heated, and the non-condensable gas is cooled. The cooled non-condensable gas flows out from the gas outlet of the non-condensable gas preheater 4 and enters the shell side of the tail gas condenser 5. Cooling water enters the tube side of the tail gas condenser 5. In the tail gas condenser 5, the non-condensable gas is condensed using the cooling water. After the non-condensable gas is cooled, it is discharged from the gas outlet of the tail gas condenser 5 and exhausted from the gas outlet of the vacuum pump 6.

[0050] The condensate flowing out from the condensate outlet of the double-effect heat exchanger 81, the condensate flowing out from the condensate outlet of the double-effect preheater 18, and the condensate flowing out from the condensate outlet of the non-condensable gas preheater 4 enter the condensate tank 28. Start the condensate pump 29. Under the action of the condensate pump 29, the condensate in the condensate tank 28 enters the condensate preheater 3, and the condensate is used to heat the material to realize the preheating of the material.

[0051] After the system runs stably and the high-grade compressed steam flowing out from the outlet of the steam compressor 12 is sufficient to meet the evaporation requirement, close the steam valve. The live steam provided by the live steam source 15 only enters the system from the air make-up port of the steam compressor 12 and is used as supplementary steam.

[0052] The material flows along the direction of the material tank 1 → feed pump 2 → condensate preheater 3 → non-condensable gas preheater 4 → double-effect preheater 18 → double-effect evaporator 8 → first-effect preheater 19 → first-effect evaporator 7 → third-effect evaporator 9 → fourth-effect evaporator 10 → thick slurry discharge pipeline 14. The material entering the condensate preheater 3 is first preheated by the condensate in the condensate tank 28. The material after the first preheating is secondarily preheated by the non-condensable gas in the non-condensable gas preheater 4, and then enters the double-effect preheater 18, where the non-condensable gas flowing out from the double-effect heat exchanger 81 is used to preheat the material for the third time. The material after the three-time preheating enters the double-effect heat exchanger 81, and the secondary steam separated by the first-effect separator 72 is used to perform the first evaporation and concentration on the material. The material after the first evaporation and concentration enters the first-effect preheater 19, and in the first-effect preheater 19, the non-condensable gas flowing out from the first-effect heat exchanger 71 is used to preheat the material before the first-effect evaporation. After that, the material enters the first-effect evaporator 7, and in the first-effect evaporator 7, pure compressed steam is used to perform the second evaporation and concentration on the material. The material after evaporation and concentration in the first-effect evaporator 7 enters the third-effect evaporator 9, and pure compressed steam is used to perform the third evaporation and concentration on the material. After that, the material enters the fourth-effect evaporator 10, and pure compressed steam is used to perform the fourth evaporation and concentration on the material. The secondary steam separated by the second-effect separator 82, the secondary steam separated by the third-effect separator 92, and the secondary steam separated by the fourth-effect separator 102 enter the shell side of the water heater 110. The condensate flowing out from the first-effect heat exchanger 71, the condensate flowing out from the first-effect preheater 19, the condensate flowing out from the third-effect heat exchanger 91, and the condensate flowing out from the fourth-effect heat exchanger 101 enter the tube side of the water heater 110. In the water heater 110, the secondary steam heats the condensate to make the condensate re-evaporate into pure steam. The pure steam is compressed by the steam compressor 12 and then enters the first-effect evaporator 7, the third-effect evaporator 9, and the fourth-effect evaporator 10 again as a heat source, so as to realize the recovery and recycling of steam and condensate, reduce the water resource consumption, use the live steam only as supplementary steam, save energy, and reduce costs.

[0053] When the steam compressor 12 needs to be spray-cleaned, start the spray water pump 20. The condensed water in the tube side of the water heater 110 enters from the spray port of the steam compressor 12 under the action of the spray water pump 20 to spray the steam compressor 12, and the spray water enters the fan condensate tank 21 for storage. When the water level of the condensate in the fan condensate tank 21 rises to the set water level, start the fan condensate water pump 22, which sends the condensate stored in the fan condensate tank 21 into the tube side of the water heater 110 to participate in the production of pure steam. When the water level in the tube side of the water heater 110 is lower than the set lower limit, start the makeup water valve 25 to supplement water to the tube side of the water heater 110 from the water supply system through the makeup water pipeline 24. When the water level in the tube side of the water heater 110 is higher than the set upper water level limit, start the outlet valve 27 to discharge the excess condensate through the outlet pipeline 26.

[0054] It should be noted that the above-described embodiments are illustrative rather than restrictive of the technical solutions of the present invention. Equivalent substitutions by those of ordinary skill in the art or other modifications made according to the prior art, as long as they do not exceed the scope and spirit of the technical solutions of the present invention, shall be included within the scope of the rights required by the present invention.

Claims

1. An MVR evaporation and concentration system for methanol-containing materials, characterized in that: Comprising: A feeding device, including a material tank (1) for storing methanol-containing materials and a feeding pump (2) with its inlet end connected to the material tank (1). A material evaporation system for evaporating and concentrating methanol-containing materials. The outlet end of the feeding pump (2) is connected to the inlet of the material evaporation system, the outlet of the material evaporation system is connected to the inlet of a discharging pump (13), and the outlet of the discharging pump (13) is connected to a thick slurry discharging pipeline (14). A water evaporator (11) heats water to generate steam using the secondary steam generated by the material evaporation system. The steam inlet of the water evaporator (11) is connected to the secondary steam outlet of the material evaporation system. A steam compressor (12) compresses the steam generated by the water evaporator (11). The steam inlet of the steam compressor (12) is connected to the steam outlet of the water evaporator (11), and the steam outlet of the steam compressor (12) is connected to the inlet of the material evaporation system. A live steam source (15). The live steam source (15) is connected to the inlet of the material evaporation system and the air supplement port of the steam compressor (12) through a live steam pipeline (16). A tail gas condenser (5). The steam inlet of the tail gas condenser (5) is connected to the non-condensable gas outlet of the water evaporator (11), the water inlet of the tail gas condenser (5) is connected to a cooling water inlet pipeline, and the water outlet of the tail gas condenser (5) is connected to a cooling water return pipeline. A vacuum pump (6). The steam inlet of the vacuum pump (6) is connected to the steam outlet of the tail gas condenser (5), and the steam outlet of the vacuum pump (6) is emptied.

2. The MVR evaporation and concentration system for methanol-containing materials according to claim 1, wherein: The material evaporation system includes a second-effect evaporator (8), a first-effect evaporator (7), a third-effect evaporator (9), and a fourth-effect evaporator (10) connected in sequence along the material flow direction. The first-effect evaporator (7) and the second-effect evaporator (8) are both falling-film evaporators, and the third-effect evaporator (9) and the fourth-effect evaporator (10) are both forced circulation evaporators. The second-effect evaporator (8) evaporates and concentrates the material using the secondary steam separated by the first-effect evaporator (7) as a heat source. The inlet of the second-effect evaporator (8) is connected to the outlet end of the feeding pump (2), the steam inlet of the second-effect evaporator (8) is connected to the secondary steam outlet of the first-effect evaporator (7), and the secondary steam outlet of the second-effect evaporator (8) is connected to the steam inlet of the water evaporator (11). The first-effect evaporator (7), the third-effect evaporator (9), and the fourth-effect evaporator (10) evaporate and concentrate the material using steam as a heat source. The steam inlets of the first-effect evaporator (7), the third-effect evaporator (9), and the fourth-effect evaporator (10) are all connected to a compressed steam pipeline (17). The compressed steam pipeline (17) is connected to the steam outlet of the steam compressor (12). The live steam source (15) is connected to the compressed steam pipeline (17) through the live steam pipeline (16). The secondary steam outlets of the third-effect evaporator (9) and the fourth-effect evaporator (10) are both connected to the steam inlet of the water evaporator (11).

3. The MVR evaporation and concentration system for methanol-containing materials according to claim 2, wherein: It further includes a preheater (18) for the second effect, the feed inlet of the preheater (18) for the second effect is communicated with the outlet end of the feed pump (2), the discharge outlet of the preheater (18) for the second effect is communicated with the feed inlet of the evaporator (8) for the second effect, the gas inlet of the preheater (18) for the second effect is communicated with the non-condensable gas outlet of the evaporator (8) for the second effect, and the gas outlet of the preheater (18) for the second effect is communicated with the gas inlet of the water evaporator (11).

4. The MVR evaporation and concentration system for methanol-containing materials according to claim 2 or 3, characterized in that: It further includes a preheater (19) for the first effect, the feed inlet of the preheater (19) for the first effect is communicated with the discharge outlet of the evaporator (8) for the second effect, the discharge outlet of the preheater (19) for the first effect is communicated with the feed inlet of the evaporator (7) for the first effect, the gas inlet of the preheater (19) for the first effect is communicated with the non-condensable gas outlets of the evaporator (7) for the first effect, the evaporator (9) for the third effect and the evaporator (10) for the fourth effect, and the gas outlet of the preheater (19) for the first effect is communicated with the gas inlet of the evaporator (8) for the second effect.

5. The MVR evaporation and concentration system for methanol-containing materials according to claim 1, wherein: The water evaporator (11) includes a water heater (110) and a circulation pump (111). The shell-side gas inlet of the water heater (110) is communicated with the secondary steam outlets of the evaporator (8) for the second effect, the evaporator (9) for the third effect and the evaporator (10) for the fourth effect through pipelines. The tube-side water inlet of the water heater (110) is communicated with the condensate outlets of the evaporator (7) for the first effect, the evaporator (9) for the third effect and the evaporator (10) for the fourth effect through pipelines. The tube-side water outlet of the water heater (110) is communicated with the water inlet of the circulation pump (111), the water outlet of the circulation pump (111) is communicated with the tube-side water inlet of the water heater (110), and the tube-side gas outlet of the water heater (110) is communicated with the gas inlet of the steam compressor (12).

6. The MVR evaporation and concentration system for methanol-containing materials according to claim 5, wherein: It further includes a make-up water pipeline (24) and a water outlet pipeline (26). The make-up water pipeline (24) is communicated with the water supply system and the tube-side water inlet of the water heater (110). The water outlet of the circulation pump (111) is communicated with the water outlet pipeline (26). A make-up water valve (25) is provided on the make-up water pipeline (24), and a water outlet valve (27) is provided on the water outlet pipeline (26). A water level gauge for detecting the water level in the tube side is provided on the water heater (110), and the water level gauge is electrically connected to the make-up water valve (25) and the water outlet valve (27). The make-up water valve (25) and the water outlet valve (27) are controlled and adjusted by the water level in the tube side of the water heater (110).

7. The MVR evaporation and concentration system for methanol-containing materials according to claim 5, characterized in that: The fan condensate outlet of the steam compressor (12) is communicated with the water inlet of the fan condensate tank (21). The water outlet of the fan condensate tank (21) is communicated with the water inlet of the fan condensate pump (22). The water outlet of the fan condensate pump (22) is communicated with the water inlet of the circulation pump (111). A fan condensate water level gauge (23) is provided on the fan condensate tank (21), and the fan condensate water level gauge (23) is electrically connected to the fan condensate pump (22). The fan condensate pump (22) is controlled and adjusted by the water level in the fan condensate tank (21).

8. The MVR evaporation and concentration system for methanol-containing materials according to any one of claims 5 to 7, characterized in that: The outlet of the tube side of the water heater (110) is connected to the inlet of the spray pump (20) through a pipeline, and the outlet of the spray pump (20) is connected to the spray inlet of the steam compressor (12).

9. The MVR evaporation and concentration system for methanol-containing materials according to any one of claims 1, 2, and 5, characterized in that: It further includes a preheating system. The preheating system includes a condensate preheater (3) and a non-condensable gas preheater (4). The feed inlet of the condensate preheater (3) is connected to the discharge outlet of the feed pump (2), the discharge outlet of the condensate preheater (3) is connected to the feed inlet of the non-condensable gas preheater (4), and the discharge outlet of the non-condensable gas preheater (4) is connected to the feed inlet of the second-effect evaporator (8). The preheating medium inlet of the condensate preheater (3) is connected to the discharge outlet of the condensate pump (29), and the preheating medium outlet of the condensate preheater (3) is connected to the drainage system. The inlet of the condensate pump (29) is connected to the discharge outlet of the condensate tank (28) for collecting and storing condensate. The inlet of the condensate tank (28) is connected to the condensate outlet of the second-effect evaporator (8), the condensate outlet of the water evaporator (11), the condensate outlet of the tail gas condenser (5), and the condensate outlet of the non-condensable gas preheater (4). The inlet of the non-condensable gas preheater (4) is connected to the non-condensable gas outlet of the water heater (110) of the water evaporator (11), and the outlet of the non-condensable gas preheater (4) is connected to the inlet of the tail gas condenser (5).

10. The MVR evaporation and concentration system for methanol-containing materials according to claim 9, wherein: A condensate water level gauge (30) is provided on the condensate tank (28). A condensate water preheating valve (31) is provided on the pipeline connecting the discharge outlet of the condensate pump (29) and the preheating medium inlet of the condensate preheater (3). The condensate water level gauge (30) is electrically connected to the condensate water preheating valve (31), and the condensate water preheating valve (31) is controlled and adjusted by the water level in the condensate tank (28).

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