A device and process for purifying a mixed solution of diethylene glycol and sodium chloride

Abstract

The invention discloses a device and a process for purifying a mixed liquid of diethylene glycol and sodium chloride. The device comprises an MVR evaporation crystallizer, a single-effect evaporation crystallizer, a distillation mechanism and a vacuum deoiling mechanism which are connected in sequence. The MVR evaporation crystallizer comprises an MVR feed pump, a preheating component, an MVR concentration component, a centrifugal compressor, an MVR solid-liquid separation component, an MVR condensation component and an MVR vacuum component; the single-effect evaporation crystallizer comprises a single-effect feed pump, a single-effect concentration component, a single-effect solid-liquid separation component, a single-effect condensation component and a single-effect vacuum component. The device and the process for purifying a mixed liquid of diethylene glycol and sodium chloride evaporate and concentrate the mixed liquid to remove water and most of the sodium chloride in the mixed liquid, evaporate the concentrated mother liquor to form steam and separate it from salt mud, and condense the steam to achieve purification, thereby ensuring the purity and recovery rate of diethylene glycol, saving energy consumption and avoiding pollution to the environment.

Description

Technical Field

[0001] The invention relates to the technical field of mixed liquid purification, in particular to a device and a process for purifying a mixed liquid of diethylene glycol and sodium chloride. Background Art

[0002] In industrial production, a mixture mainly composed of diethylene glycol and sodium chloride is often produced in a variety of chemical reactions and process. Diethylene glycol has many uses and values ​​in industrial production and is widely used in the production of chemical products, such as polyester resins, rubber plasticizers, fiberglass and other fields. With the rapid development of downstream industries, the market demand for diethylene glycol is also rising. Therefore, it is usually necessary to extract the mixture composed of diethylene glycol and sodium chloride.

[0003] For the above-mentioned mixed liquid, the purification methods mainly include distillation and extraction. The distillation method uses the difference in boiling points of diethylene glycol and sodium chloride to separate them, so that diethylene glycol evaporates and then condenses to obtain liquid diethylene glycol. However, this method consumes a lot of energy, and because the mixed liquid contains other impurities, the separation effect is poor and the separation purity is low. The extraction method uses the selective solubility of diethylene glycol and sodium chloride, selects a suitable solvent to contact the mixed liquid, and after diethylene glycol is extracted by the solvent, the solvent is separated from diethylene glycol by distillation. However, this method requires the selection of a suitable solvent, and the recovery and reuse of the solvent increase the purification cost. In addition, wastewater is easily generated during the extraction process, causing environmental pollution.

[0004] Therefore, a purification device for a mixed solution of diethylene glycol and sodium chloride is badly needed. Summary of the invention

[0005] The purpose of the present invention is to overcome the defects in the prior art and provide a device and process for purifying a mixed solution of diethylene glycol and sodium chloride which is energy-saving and environmentally friendly, reduces costs and improves separation effect.

[0006] In order to solve the above technical problems, the present invention discloses a mixed liquid purification device of diethylene glycol and sodium chloride, comprising an MVR evaporation crystallizer, a single-effect evaporation crystallizer, a distillation mechanism and a vacuum deoiling mechanism connected in sequence, wherein the MVR evaporation crystallizer comprises: an MVR feed pump, a preheating component, an MVR concentration component, a centrifugal compressor, an MVR solid-liquid separation component, an MVR condensation component and an MVR vacuum component; The input end of the MVR feed pump is connected to the raw liquid pool, and the output end is connected to the MVR concentration component through the preheating component. The MVR concentration component is used to heat the raw liquid to generate and output secondary steam and slurry. The heating source of the MVR concentration component includes raw steam provided by the raw steam source and compressed steam formed after the centrifugal compressor works on the secondary steam. The MVR solid-liquid separation component is used to discharge the separated solid after the solid-liquid separation of the slurry output by the MVR concentration component. A part of the separated mother liquor is discharged into the single-effect evaporation crystallizer, and the other part is returned to the MVR concentration component. The MVR condensation component is used to receive condensed water formed by cooling the raw steam and the compressed steam and then pass the condensed water into the condensed water discharge system. The MVR vacuum component is used to discharge the non-condensable gas in the MVR evaporation crystallizer into the tail gas treatment system; The single-effect evaporation crystallizer comprises: a single-effect feed pump, a single-effect concentration component, a single-effect solid-liquid separation component, a single-effect condensation component and a single-effect vacuum component; The single-effect feed pump is used to input the mother liquor output by the MVR solid-liquid separation component into the single-effect concentration component, the single-effect concentration component is used to heat the mother liquor to generate secondary steam and slurry, the heating source of the single-effect concentration component includes heat-conducting oil provided by a heat-conducting oil source, the single-effect solid-liquid separation component is used to discharge the separated solid after the solid-liquid separation of the slurry output by the single-effect concentration component, a part of the separated mother liquor is discharged into the distillation mechanism, and the other part is returned to the single-effect concentration component, the single-effect condensation component is used to condense the secondary steam output by the single-effect concentration component to form condensed water and then pass it into the condensed water discharge system, and the single-effect vacuum component is used to discharge the non-condensable gas in the single-effect evaporation crystallizer into the tail gas treatment system; The distillation mechanism comprises: a distillation tower, a distillation discharge pump and a distillation condensation component; The distillation tower is used to receive and heat the mother liquid output by the single-effect solid-liquid separation component to generate secondary steam and feed liquid. The heating source of the distillation tower includes heat transfer oil provided by a heat transfer oil source. The distillation discharge pump is used to return a part of the feed liquid output by the distillation tower to the input end of the single-effect feed pump, and discharge the other part into the vacuum deoiling mechanism. The distillation condensation component is used to condense the secondary steam output by the distillation tower to form condensed water and then pass it into the condensed water discharge system; The vacuum deoiling mechanism comprises: an enamel kettle, an enamel condensation component, an enamel vacuum component and an enamel discharge pump; The enamel kettle is used to receive and heat the mother liquor output by the distillation discharge pump to generate secondary steam and salt mud. The heating source of the enamel kettle includes heat transfer oil provided by a heat transfer oil source. The enamel discharge pump is used to discharge the salt mud generated by the enamel kettle out of the system. The enamel condensation component is used to condense the secondary steam output by the enamel kettle to form a purified liquid and then pass it into the purified liquid collection system. The enamel vacuum component is used to discharge the non-condensable gas in the vacuum de-oiling mechanism into the exhaust gas treatment system.

[0007] Preferably, in order to achieve multi-stage preheating of the mixed liquid so that the mixed liquid can enter the MVR concentration component at a stable temperature, ensure stable evaporation and concentration, reduce the consumption of live steam, and reduce energy consumption and costs, the preheating component includes a non-condensable gas preheater, a condensate preheater and a live steam preheater arranged in sequence, the heating source of the non-condensable gas preheater is the non-condensable gas in the MVR concentration component, the heating source of the condensate preheater is the condensate received by the MVR condensation component, and the heating source of the live steam preheater is the live steam provided by the live steam source.

[0008] Preferably, in order to achieve gas-liquid separation of the secondary steam mixed gas generated by the MVR concentrating component and ensure that dry saturated steam is passed into the centrifugal compressor, a scrubbing component is further arranged between the MVR concentrating component and the centrifugal compressor. The scrubbing component is used to perform gas-liquid separation on the secondary steam generated by the MVR concentrating component to input dry saturated steam into the centrifugal compressor. The cleaning liquid of the scrubbing component is the condensed water collected by the MVR condensing component.

[0009] Preferably, in order to improve the solute recovery and utilization rate, the scrubbing component includes a scrubbing tower, a scrubbing circulation pump and a scrubbing discharge pump, the scrubbing tower has a mixed steam inlet, a cleaning liquid discharge outlet and a cleaning liquid input port, the mixed steam inlet is used to input the secondary steam generated by the MVR concentration component, the cleaning liquid discharge outlet is connected with the mixed steam inlet through the scrubbing circulation pump, the input end of the scrubbing discharge pump is connected with the cleaning liquid discharge outlet, and the output end is arranged in the raw liquid pool, and the cleaning liquid input port is used to input the condensed water collected by the MVR condensation component.

[0010] Preferably, in order to achieve rapid concentration and evaporation of the mixed liquid, the MVR concentration component includes an MVR crystallizer, an MVR heater, an MVR circulation pump and an MVR discharge pump. The crystallizer has an MVR circulation inlet, an MVR circulation outlet and an MVR crystallization outlet. The MVR crystallization outlet is connected to the MVR solid-liquid separation component through the MVR discharge pump. Two MVR heaters are provided, which are respectively located between the MVR circulation inlet and the output end of the circulation pump and between the MVR circulation outlet and the input end of the circulation pump.

[0011] Preferably, in order to facilitate the input of mother liquor into the distillation tower, a cyclone is provided at the output end of the single-effect solid-liquid separation component, a cyclone inlet is provided on the side wall of the cyclone, and a heavy outlet and a light outlet are also provided on the cyclone, the heavy outlet is connected to the distillation tower, and the light outlet is connected to the input end of the single-effect feed pump.

[0012] Preferably, in order to ensure pressure balance during condensation of secondary steam, the distillation condensation component includes a distillation condenser, a pressure regulating tank, a distillation cooler, a distillation condensation water tank and a distillation condensation water pump connected in sequence, and the distillation condenser is connected to the distillation tower.

[0013] Preferably, in order to facilitate rapid boiling and evaporation of the mixed liquid, at least two enamel kettles are provided and distributed in parallel.

[0014] Preferably, in order to facilitate cleaning of the enamel kettle, the enamel kettle is connected to the MVR condensation component, so that the condensed water collected by the MVR condensation component can dilute the sodium chloride salt mud formed after evaporation and concentration of the enamel kettle.

[0015] In order to solve the above technical problems, the present invention also discloses a process for purifying a mixed solution of diethylene glycol and sodium chloride, comprising the following steps: S100, MVR evaporation concentration: preheat the mixed liquid and then force circulation heating to concentrate the mixed liquid into slurry, then perform solid-liquid separation, the separated solid is discharged from the system, the separated mother liquor is a mother liquor with a sodium chloride content of ≤10% and a diethylene glycol content of ≥90%, the mother liquor is continued to be forced circulation heated and part of the mother liquor is discharged regularly and quantitatively; S200, single-effect evaporation and concentration: the mother liquor discharged in step S100 is subjected to single-effect evaporation and concentration treatment to obtain a slurry with a higher concentration, the slurry is subjected to solid-liquid separation, the separated solid is discharged from the system, the separated mother liquor is a mother liquor with a sodium chloride content of ≤1% and a diethylene glycol content of ≥95%, the mother liquor is further subjected to single-effect evaporation and concentration, and part of the mother liquor is discharged at a regular and quantitative time; S300, distillation: the mother liquor discharged in step S200 is distilled and evaporated, and concentrated to obtain a feed liquid with a sodium chloride content of ≤1% and a diethylene glycol content of ≥95%, and then discharged; S400, evaporation and purification: the feed liquid discharged in step S300 is subjected to boiling evaporation to separate the sodium chloride salt sludge and the secondary steam generated by the evaporation of diethylene glycol, the sodium chloride salt sludge is discharged from the system, and the secondary steam of diethylene glycol is heat-exchanged with condensed water, so that the secondary steam of diethylene glycol is condensed into diethylene glycol with a purity of more than 99% and is in liquid state, and then collected.

[0016] In summary, compared with the prior art, the device and process for purifying a mixed solution of diethylene glycol and sodium chloride of the present invention removes water and most of the sodium chloride in the mixed solution by evaporating and concentrating the mixed solution, then evaporates the concentrated mother liquor to form steam and separates it from the salt mud, and condenses the steam to achieve purification, thereby ensuring the purity and recovery rate of diethylene glycol, saving energy consumption and avoiding pollution to the environment. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a structural schematic diagram of the MVR evaporation crystallizer of the present invention; Figure 2 It is a schematic diagram of the structure of the MVR evaporation crystallizer for treating the mixed liquid of the present invention; Figure 3 It is a schematic diagram of the structure of the MVR evaporation crystallizer for processing steam of the present invention; Figure 4 It is a schematic diagram of the structure of the MVR evaporation crystallizer for treating condensed water of the present invention; Figure 5 It is a schematic diagram of the structure of the MVR evaporation crystallizer for treating non-condensable gas of the present invention; Figure 6 It is a structural schematic diagram of a single-effect evaporation crystallizer of the present invention; Figure 7 It is a structural schematic diagram of a single-effect evaporation crystallizer for treating a mixed liquid according to the present invention; Figure 8 It is a schematic diagram of the structure of the single-effect evaporation crystallizer for processing steam of the present invention; Fig. 9 It is a schematic diagram of the structure of the single-effect evaporation crystallizer for treating condensed water of the present invention; Fig.10 It is a structural schematic diagram of the distillation mechanism of the present invention; Fig.11 It is a schematic diagram of the structure of the distillation mechanism of the present invention for processing a mixed liquid; Fig.12 It is a schematic diagram of the structure of the distillation mechanism of the present invention for processing condensed water; Fig.13 It is a structural schematic diagram of the vacuum deoiling mechanism of the present invention; Fig.14 It is a schematic diagram of the structure of the vacuum deoiling mechanism of the present invention for treating the mixed liquid; Fig.15 It is a schematic diagram of the structure of the vacuum deoiling mechanism of the present invention for processing steam and condensed water; Fig.16 It is a process flow chart of the present invention; In the figure: 1. MVR evaporation crystallizer; 101. MVR feed pump; 102. centrifugal compressor; 10201. compressed steam inlet; 10202. compressed steam outlet; 103. non-condensable gas preheater; 10301. primary preheating inlet; 10302. primary preheating outlet; 10303. non-condensable gas preheating inlet; 10304. non-condensable gas preheating outlet; 104. condensate preheater; 10401. secondary preheating inlet; 10402. secondary preheating outlet; 10403. condensate preheating inlet; 10404. condensate preheating outlet; 105. raw steam preheater; 10501. tertiary preheating inlet; 10502. tertiary preheating outlet; 10503. raw steam preheating inlet; 10504 , raw steam preheating outlet; 106, scrubber; 10601, mixed steam inlet; 10602, cleaning liquid outlet; 10603, cleaning liquid inlet; 10604, dry steam outlet; 107, scrubber circulation pump; 108, scrubber discharge pump; 109, MVR crystallizer; 10901, MVR circulation inlet; 10902, MVR circulation outlet; 10903, MVR crystallization outlet; 10904, MVR secondary steam outlet; 110, MVR heater; 11001, MVR heating inlet; 11002, MVR heating outlet; 11003, MVR steam inlet; 11004, MVR non-condensable gas inlet; 11005, MVR heating condensate outlet; 11006 , MVR heating non-condensable gas outlet; 111, MVR circulation pump; 112, MVR discharge pump; 113, siphon tank; 114, MVR thickener; 11401, MVR thickening inlet; 11402, MVR thickening outlet; 11403, MVR overflow; 115, MVR centrifuge; 11501, MVR centrifugal inlet; 11502, MVR solid outlet; 11503, MVR liquid outlet; 116, MVR mother liquid tank; 117, MVR mother liquid pump; 118, MVR vacuum pump; 119, MVR vacuum tank; 120, MVR vacuum heat exchanger; 121, MVR non-condensable gas separator; 12101, MVR separation inlet; 12102, MVR non-condensable gas outlet; 12103, MVR drain outlet; 122, MVR condensate tank; 123, MVR condensate pump; 124, MVR spray pump; 125, MVR condensate tank; 126, MVR condensate pump; 127, volute tank; 128, volute pump; 2, single-effect evaporation crystallizer; 201, single-effect feed pump; 202, cyclone; 20201, cyclone inlet; 20202, heavy outlet; 20203, light outlet; 203, single-effect feed buffer tank; 204, single-effect heater; 20401, single-effect heating inlet; 20402, single-effect heating outlet; 20403, single-effect heat transfer oil inlet; 20404, single-effect heat transfer oil outlet; 205, single-effect separator; 20501, single-effect circulation inlet;20502, single-effect circulation outlet; 20503, single-effect secondary steam outlet; 20504, single-effect crystal slurry outlet; 20505, single-effect concentrate outlet; 20506, single-effect cleaning inlet; 206, single-effect circulation pump; 207, single-effect discharge pump; 208, single-effect condenser; 20801, single-effect secondary steam inlet; 20802, single-effect non-condensable gas inlet; 20803, single-effect non-condensable gas outlet; 20804, single-effect cooling inlet; 20805, single-effect cooling outlet; 20806, single-effect condensate outlet; 209, single-effect vacuum pump; 210, single-effect vacuum tank; 211, single-effect vacuum heat exchanger; 212, single-effect condensate tank; 213, single-effect condensate pump; 214, single-effect thickener; 2 1401, single-effect thick inlet; 21402, single-effect thick outlet; 21403, single-effect overflow port; 215, single-effect centrifuge; 21501, single-effect centrifuge inlet; 21502, single-effect solid outlet; 21503, single-effect liquid outlet; 216, single-effect mother liquid tank; 217, single-effect mother liquid pump; 3, distillation mechanism; 301, distillation tower; 30101, distillation material inlet; 30102, distillation material outlet; 30103, distillation heat transfer inlet; 30104, distillation heat transfer outlet; 30105, distillation reflux port; 302, distillation discharge pump; 303, distillation condenser; 30301, distillation secondary steam inlet; 30302, distillation condensation outlet; 30303, distillation circulation inlet; 3 0304, distillation circulation outlet; 30305, distillation condensation balance port; 304, pressure stabilizing tank; 30401, distillation pressure stabilizing inlet; 30402, distillation pressure stabilizing outlet; 30403, distillation pressure stabilizing balance port; 305, distillation cooler; 30501, distillation condensate water inlet; 30502, distillation condensate water outlet; 30503, distillation cooling water inlet; 30504, distillation cooling water outlet; 306, distillation condensate water tank; 307, distillation condensate water pump; 308, kettle section; 30801, distillation secondary steam outlet; 30802, distillation spray inlet; 4, vacuum deoiling mechanism; 401, enamel kettle; 40101, enamel feed inlet; 40102, enamel discharge port; 40103, enamel Secondary steam outlet; 40104, enamel dilution port; 40105, enamel overflow port; 40106, enamel heat transfer oil inlet; 40107, enamel heat transfer oil outlet; 402, enamel discharge pump; 403, enamel condenser; 40301, enamel secondary steam inlet; 40302, enamel condensate outlet; 40303, enamel cooling inlet; 40304, enamel cooling outlet; 404, enamel condensate tank; 405, enamel condensate pump; 406, enamel vacuum pump; 407, enamel vacuum tank; 408, enamel vacuum heat exchanger; 5, raw liquid pool; 6, raw steam source; 7, condensate discharge system; 8, exhaust gas treatment system; 9, heat transfer oil source; 10, cooling water source; 11, purified liquid collection system. ; DETAILED DESCRIPTION

[0018] The specific implementation of the present invention is further described below in conjunction with the accompanying drawings and embodiments. The following embodiments are only used to more clearly illustrate the technical solution of the present invention, and cannot be used to limit the protection scope of the present invention.

[0019] In order to facilitate the description of the flow direction of various fluids during the operation of the present invention, Figure 1-Figure 15 In the structural diagram shown, the solid isosceles triangle represents the flow direction of the mixed liquid, the hollow isosceles triangle represents the flow direction of the condensed water and cooling water, the solid arrow represents the flow direction of the steam and heat transfer oil, and the hollow arrow represents the flow direction of the non-condensable gas.

[0020] like Figure 1-Figure 15 As shown, the mixed solution purification device of diethylene glycol and sodium chloride of the present invention comprises an MVR evaporation crystallizer 1, a single-effect evaporation crystallizer 2, a distillation mechanism 3 and a vacuum deoiling mechanism 4 which are connected in sequence: The MVR evaporation crystallizer 1 includes: an MVR feed pump 101, a preheating component, an MVR concentration component, a centrifugal compressor 102, an MVR solid-liquid separation component, an MVR condensation component and an MVR vacuum component; The input end of the MVR feed pump 101 is connected to the raw liquid pool 5, and the output end is connected to the MVR concentration component through a preheating component. The MVR concentration component is used to heat the raw liquid to generate and output secondary steam and slurry. The heating source of the MVR concentration component includes the raw steam provided by the raw steam source 6 and the compressed steam formed after the centrifugal compressor 102 does work on the secondary steam. The MVR solid-liquid separation component is used to discharge the separated solid after the solid-liquid separation of the slurry output by the MVR concentration component. A part of the separated mother liquor is discharged into the single-effect evaporation crystallizer 2, and the other part is returned to the MVR concentration component. The MVR condensation component is used to receive the condensed water formed after the raw steam and the compressed steam are cooled and then pass the condensed water into the condensed water discharge system 7. The MVR vacuum component is used to discharge the non-condensable gas in the MVR evaporation crystallizer 1 into the tail gas treatment system 8; The single-effect evaporation crystallizer 2 comprises: a single-effect feed pump 201, a single-effect concentration component, a single-effect solid-liquid separation component, a single-effect condensation component and a single-effect vacuum component; The single-effect feed pump 201 is used to input the mother liquor output by the MVR solid-liquid separation component into the single-effect concentration component. The single-effect concentration component is used to heat the mother liquor to generate secondary steam and slurry. The heating source of the single-effect concentration component includes heat-conducting oil provided by the heat-conducting oil source 9. The single-effect solid-liquid separation component is used to discharge the separated solid after the solid-liquid separation of the slurry output by the single-effect concentration component. A part of the separated mother liquor is discharged into the distillation mechanism 3, and the other part is returned to the single-effect concentration component. The single-effect condensation component is used to condense the secondary steam output by the single-effect concentration component to form condensed water and then pass it into the condensed water discharge system 7. The single-effect vacuum component is used to discharge the non-condensable gas in the single-effect evaporation crystallizer 2 into the tail gas treatment system 8; The distillation mechanism 3 includes: a distillation tower 301, a distillation discharge pump 302 and a distillation condensation component; The distillation tower 301 is used to receive and heat the mother liquid output by the single-effect solid-liquid separation component to generate secondary steam and feed liquid. The heating source of the distillation tower 301 includes the heat transfer oil provided by the heat transfer oil source 9. The distillation discharge pump 302 is used to return a part of the feed liquid output by the distillation tower 301 to the input end of the single-effect feed pump 201, and the other part is discharged into the vacuum deoiling mechanism 4. The distillation condensation component is used to condense the secondary steam output by the distillation tower 301 to form condensed water and then pass it into the condensed water discharge system 7; The vacuum deoiling mechanism 4 comprises: an enamel kettle 401, an enamel condensation component, an enamel vacuum component and an enamel discharge pump 402; The enameled kettle 401 is used to receive and heat the mother liquor output by the distillation discharge pump 302 to generate secondary steam and salt mud. The heating source of the enameled kettle 401 includes the heat transfer oil provided by the heat transfer oil source 9. The enameled discharge pump 402 is used to discharge the salt mud generated by the enameled kettle 401 out of the system. The enameled condensation component is used to condense the secondary steam output by the enameled kettle 401 to form a purified liquid and then pass it into the purified liquid collection system 11. The enameled vacuum component is used to discharge the non-condensable gas in the vacuum de-oiling mechanism 4 into the exhaust gas treatment system 8.

[0021] The mixed liquid purification device of diethylene glycol and sodium chloride of the present invention mainly consists of an MVR evaporation crystallizer 1, a single-effect evaporation crystallizer 2, a rectification mechanism 3 and a vacuum deoiling mechanism 4, wherein: like Figure 1-Figure 5As shown, the MVR evaporation crystallizer 1 of the present invention extracts the stock liquid in the stock liquid pool 5 through the MVR feed pump 101, that is, the mixed liquid mainly composed of diethylene glycol, sodium chloride and water, and passes the mixed liquid into the preheating component for preheating, so that the mixed liquid is heated by preheating, and then enters the MVR concentration component. The MVR concentration component drives the mixed liquid to circulate under a negative pressure environment and heats the mixed liquid, so that the mixed liquid boils and evaporates under a negative pressure environment, generates secondary steam, and reduces the concentration of the mixed liquid, precipitates a large amount of sodium chloride crystals, thereby removing a large amount of water and sodium chloride components in the mixed liquid. Then, the concentrated mixed liquor is passed into the MVR solid-liquid separation component to remove solid particles in the mixed liquor to form a pure mixed liquor mother liquor, in which the mass fraction of sodium chloride is ≤10% and the fraction of diethylene glycol is ≥90%. The mixed liquor mother liquor is returned to the MVR concentration component for evaporation and concentration treatment, and part of the mother liquor is discharged from the MVR evaporation crystallizer 1 at a regular and quantitative manner and transported to the single-effect evaporation crystallizer 2 for further evaporation and concentration treatment to avoid the accumulation of organic matter and high-boiling-point substances in the MVR evaporation crystallizer 1, so as to maintain the stable operation of the MVR evaporation crystallizer 1.

[0022] During the evaporation and concentration process of the mixed liquid by the MVR evaporation crystallizer 1, the secondary steam generated by the evaporation of the mixed liquid is introduced into the centrifugal compressor 102, and the secondary steam is compressed and worked by the centrifugal compressor 102, so that the temperature can be increased by about 18°C. The compressed steam can be introduced into the MVR concentration component again to evaporate and concentrate the material, thereby avoiding the continuous introduction of a large amount of raw steam, thus saving energy consumption and reducing the purification cost.

[0023] The steam (including compressed steam formed by heat exchange between raw steam and secondary steam) is received by the MVR condensation component and cooled after heat exchange with the mixed liquid to form condensed water, and then the condensed water is discharged through the condensed water discharge system 7, while the MVR vacuum component is used to discharge the non-condensable gas in the MVR evaporation crystallizer 1 into the exhaust gas treatment system 8.

[0024] A further improvement is that the preheating component includes a non-condensable gas preheater 103, a condensate preheater 104 and a raw steam preheater 105 which are arranged in sequence, the heating source of the non-condensable gas preheater 103 is the non-condensable gas in the MVR concentration component, the heating source of the condensate preheater 104 is the condensate received by the MVR condensation component, and the heating source of the raw steam preheater 105 is the raw steam provided by the raw steam source 6.

[0025] In the present invention, the preheating component uses a non-condensable gas preheater 103, a condensed water preheater 104 and a raw steam preheater 105 to preheat the mixed liquid in sequence, which mainly depends on the temperature of the mixed liquid in the raw liquid pool 5, the non-condensable gas temperature in the evaporation and concentration process, the condensed water temperature and the raw steam temperature provided by the raw steam source 6. Therefore, the non-condensable gas, condensed water and raw steam can be used to preheat the mixed liquid flowing out of the raw liquid pool 5 three times in sequence. After three preheatings, not only can the heat be fully recovered, the heat loss can be reduced, the heat utilization rate can be improved, and the cost can be reduced, but also After the mixed liquid is finally heat-exchanged with the raw steam, it can reach the boiling point feed. The benefits of boiling point feed are: the mixed liquid enters the MVR concentration component within a specific temperature range, ensuring that its entry temperature is close to the evaporation and concentration temperature of the MVR concentration component, avoiding fluctuations caused by too low or too high feed temperature, making the evaporation system run more smoothly, and at the same time facilitating the adjustment of the internal pressure of the MVR concentration component, reducing the huge changes in the raw steam input amount that cause excessive changes in the internal pressure of the MVR concentration component, so that the MVR vacuum component can more stably adjust the internal pressure of the MVR evaporation crystallizer 1.

[0026] like Figure 2-Figure 5 As shown, the MVR concentration component includes an MVR crystallizer 109, an MVR heater 110, an MVR circulation pump 111 and an MVR discharge pump 112. The crystallizer has an MVR circulation inlet 10901, an MVR circulation outlet 10902, an MVR crystallization outlet 10903 and an MVR secondary steam outlet 10904. The MVR crystallization outlet 10903 is connected to the MVR solid-liquid separation component through the MVR discharge pump 112. Two MVR heaters 110 are provided, which are respectively located between the MVR circulation inlet 10901 and the output end of the circulation pump and between the MVR circulation outlet 10902 and the input end of the circulation pump.

[0027] The MVR heater 110 has an MVR heating inlet 11001, an MVR heating outlet 11002, an MVR steam inlet 11003, an MVR non-condensable gas inlet 11004, an MVR heating condensate outlet 11005, and an MVR heating non-condensable gas outlet 11006, wherein the MVR heating inlet 11001 and the MVR heating outlet 11002 are respectively used for the mixed liquid to enter and discharge, the MVR steam inlet 11003 is used for the raw steam provided by the raw steam source 6 to enter, and after the raw steam exchanges heat with the mixed liquid, condensate is formed and discharged through the MVR heating condensate outlet 11005, the MVR heating non-condensable gas outlet 11006 is used for the non-condensable gas in the MVR condensation component to enter, and the MVR heating non-condensable gas outlet 11006 is used for the non-condensable gas to be discharged.

[0028] After adopting the above structure, after the mixed liquid reaches the boiling point after the three-stage preheating by the preheating component, it enters the MVR concentration component. Under the action of the MVR circulation pump 111, the mixed liquid circulates between the MVR heater 110, the MVR circulation pump 111 and the two MVR heaters 110. During the circulation of the mixed liquid, when passing through the two MVR heaters 110, it exchanges heat with the raw steam introduced into the inside, so that the temperature of the mixed liquid increases. After entering the MVR crystallizer 109, it boils and evaporates to generate secondary steam. While the secondary steam is discharged through the MVR secondary steam outlet 10904, the concentration of the mixed liquid in the MVR crystallizer 109 decreases and reaches a supersaturated state, and sodium chloride crystals are precipitated, thereby removing a large amount of water and sodium chloride in the mixed liquid. Then, under the action of the MVR discharge pump 112, it is discharged from the MVR crystallizer 109 through the MVR crystallization outlet 10903.

[0029] The MVR condensation component includes an MVR condensate water tank 122, an MVR condensate water pump 123 and an MVR spray pump 124, wherein the MVR heating condensate water outlet 11005 is connected to the MVR condensate water tank 122, so that the condensate formed after the condensation of the raw steam in the MVR heater 110 can pass into the MVR condensate water tank 122, and the top of the MVR condensate water tank 122 is connected to the MVR non-condensable gas inlet 11004, so that the non-condensable gas in the MVR condensate water tank 122 can enter the MVR heater 110.

[0030] In the preheating component, the non-condensable gas preheater 103 has a first-level preheating inlet 10301, a first-level preheating outlet 10302, a non-condensable gas preheating inlet 10303 and a non-condensable gas preheating outlet 10304, wherein the first-level preheating inlet 10301 is connected to the output end of the MVR feed pump 101, the first-level preheating inlet 10301 and the first-level preheating outlet 10302 are respectively used for the mixed liquid to enter and discharge, the non-condensable gas preheating inlet 10303 is connected to the MVR heating non-condensable gas outlet 11006, and the non-condensable gas preheating outlet 10304 is connected to the MVR vacuum component, so that the non-condensable gas in the MVR heater 110 can be passed into the non-condensable gas preheater 103 for heat exchange.

[0031] The condensate preheater 104 has a secondary preheating inlet 10401, a secondary preheating outlet 10402, a condensate preheating inlet 10403 and a condensate preheating outlet 10404, wherein the secondary preheating inlet 10401 is connected with the primary preheating outlet 10302, so that the mixed liquid after the condensate gas preheating is passed into the condensate preheater 104 for secondary preheating, and then the mixed liquid is discharged through the secondary preheating outlet 10402, and the condensate preheating inlet 10403 is connected with the output end of the MVR condensate pump 123, so that the MVR condensate pump 123 can extract the high-temperature condensate of the MVR condensate tank 122 and transport it to the condensate preheater 104 for secondary preheating of the mixed liquid. After preheating, the temperature of the condensate drops and is divided into two paths, one of which is discharged through the condensate discharge system 7, and the other enters the enamel kettle 401 for flushing and cleaning.

[0032] The live steam preheater 105 includes a three-stage preheating inlet 10501, a three-stage preheating outlet 10502, a live steam preheating inlet 10503 and a live steam preheating outlet 10504, wherein the three-stage preheating inlet 10501 is connected to the two-stage preheating outlet 10402, and the three-stage preheating outlet 10502 is connected to the MVR circulation inlet 10901, so that the mixed liquid after condensed water preheating is passed into the live steam preheater 105 for secondary preheating, and then the mixed liquid is discharged through the three-stage preheating outlet 10502 and then passed into the MVR crystallizer 109. The live steam preheating inlet 10503 is used for the live steam provided by the live steam source 6 to pass in, and after the live steam exchanges heat with the internal mixed liquid, condensed water is formed. The live steam preheating outlet 10504 is connected to the MVR condensed water tank 122, so that the formed condensed water can enter the MVR condensed water tank 122.

[0033] The MVR vacuum component includes an MVR non-condensable gas separator 121, an MVR vacuum pump 118, an MVR vacuum tank 119 and an MVR vacuum heat exchanger 120, wherein the MVR non-condensable gas separator 121 has an MVR separation inlet 12101, an MVR non-condensable gas outlet 12102 and an MVR drain 12103. Specifically, the MVR separation inlet 12101 is connected to the non-condensable gas preheating outlet 10304, the MVR non-condensable gas outlet 12102 is connected to the MVR vacuum tank 119 through the MVR vacuum pump 118, the MVR vacuum tank 119 is connected to the exhaust gas treatment system 8, the MVR vacuum pump 118 and the MVR vacuum tank 119 are connected through the MVR vacuum heat exchanger 120, the refrigerant of the MVR vacuum heat exchanger 120 is the circulating cooling water provided by the cooling water source 10, and the MVR drain 12103 is connected to the input end of the MVR condensate pump 123.

[0034] After adopting the above structure, the non-condensable gas mixture is separated into gas and liquid through the MVR non-condensable gas separator 121, and the liquid produced by the separation enters the input end of the MVR condensate pump 123 through the MVR drain port 12103, while the non-condensable gas formed by the separation is discharged into the exhaust gas treatment system 8 through the MVR vacuum pump 118 and the MVR vacuum tank 119.

[0035] The centrifugal compressor 102 has a compressed steam inlet 10201 and a compressed steam outlet 10202, and the compressed steam inlet 10201 and the compressed steam outlet 10202 are respectively connected to the MVR secondary steam outlet 10904 and the MVR steam inlet 11003, so that the centrifugal compressor 102 can receive the secondary steam discharged from the compressed steam outlet 10202 and compress it to form high-temperature compressed steam, and then pass it into the MVR heater 110 to heat the mixed liquid, thereby saving the amount of raw steam and reducing the cost of evaporation and concentration.

[0036] The centrifugal compressor 102 is also connected to a volute water tank 127, which is connected to the MVR condensate water tank 122 via a volute water pump 128. When the centrifugal compressor 102 is running, the generated condensate can be collected and stored via the volute water tank 127. When a certain amount is reached, the condensate is passed into the volute water tank 127 via the volute water pump 128.

[0037] The MVR solid-liquid separation component includes an MVR thickener 114, an MVR centrifuge 115, an MVR mother liquid tank 116 and an MVR mother liquid pump 117, wherein the MVR thickener 114 has an MVR thickening inlet 11401, an MVR thickening outlet 11402 and an MVR overflow port 11403, and the MVR centrifuge 115 has an MVR centrifugal inlet 11501, an MVR solid outlet 11502 and an MVR liquid outlet 11503. The MVR thick inlet 11401 is connected to the output end of the MVR discharge pump 112, the MVR thick outlet 11402 is connected to the MVR centrifugal inlet 11501, the MVR overflow port 11403 and the MVR liquid outlet 11503 are both connected to the MVR mother liquor tank 116, the MVR mother liquor tank 116 is connected to the input end of the MVR circulation pump 111 through the MVR mother liquor pump 117, and the output end of the MVR mother liquor pump 117 is also connected to the single-effect evaporation crystallizer 2.

[0038] After adopting the above structure, the MVR discharge pump 112 transports the slurry concentrated to a certain degree to the MVR thickener 114 for precipitation treatment. After precipitation, the slurry concentration at the bottom of the MVR thickener 114 increases, and is discharged through the MVR thickening outlet 11402, and enters the MVR centrifuge 115 through the MVR centrifugal inlet 11501 for centrifugal treatment to separate the sodium chloride crystal solid and the mixed liquid mother liquor, and is discharged from the system through the MVR solid outlet 11502, while the mixed liquid mother liquor enters the MVR mother liquor tank 116 through the MVR liquid outlet 11503. At the same time, as the precipitation increases, the clear liquid at the top of the MVR thickener 114 enters the MVR mother liquor tank 116 through the MVR overflow port 11403, and the MVR mother liquor pump 117 transports the mixed liquid to the MVR concentrating component for further concentration and evaporation, and the concentrated mother liquor is regularly discharged and transported to the single-effect evaporation crystallizer 2.

[0039] A further improvement is that a scrubbing assembly is further provided between the MVR concentrating assembly and the centrifugal compressor 102, the scrubbing assembly is used to perform vapor-liquid separation on the secondary steam generated by the MVR concentrating assembly to input dry saturated steam to the centrifugal compressor 102, and the cleaning liquid of the scrubbing assembly is the condensed water collected by the MVR condensing assembly; the scrubbing assembly includes a scrubbing tower 106, a scrubbing circulation pump 107 and a scrubbing discharge pump 108, the scrubbing tower 106 has a mixed steam inlet 10601, a cleaning liquid discharge port 10602 and a cleaning liquid input port 10603, the mixed steam inlet 10601 is used to input the secondary steam generated by the MVR concentrating assembly, the cleaning liquid discharge port 10602 is connected to the mixed steam inlet 10601 through the scrubbing circulation pump 107, the input end of the scrubbing discharge pump 108 is connected to the cleaning liquid discharge port 10602, the output end is arranged in the raw liquid pool 5, and the cleaning liquid input port 10603 is used to input the condensed water collected by the MVR condensing assembly.

[0040] Specifically, in the air intake assembly, the scrubbing tower 106 also has a dry steam exhaust port 10604, which is connected to the compressed steam inlet 10201, and the input end of the scrubbing circulation pump 107 is connected to the output end of the MVR condensate water pump 123. The dry steam exhaust port 10604 is also connected to the MVR condensate tank 125, and the MVR condensate tank 125 is connected to the MVR condensate tank 122 through the MVR condensate pump 126, and the MVR condensate tank 122 is connected to the cleaning liquid input port 10603.

[0041] After adopting the above structure, the condensed water in the MVR condensed water tank 122 is extracted by the MVR spray pump 124 and transported to the scrubber 106. At the same time, the secondary steam containing droplets is introduced into the scrubber 106 through the mixed steam inlet 10601. The condensed water flowing out of the cleaning liquid discharge port 10602 is extracted by the scrubbing circulation pump 107, and is continuously circulated and transported to the scrubber 106 to scrub the secondary steam mixture, so that the dry steam discharge port 10604 discharges dry saturated steam and enters the centrifugal compressor 102 for compression treatment, and the water discharged from the cleaning liquid discharge port 10602 is transported to the raw liquid pool 5 through the scrubbing discharge pump 108, so as to be subsequently transported to the MVR concentration component for further concentration, thereby improving the solute recovery rate; in the process of the dry saturated steam being introduced into the centrifugal compressor 102, the condensed water generated enters the MVR condensed water tank 125, and the condensed water is transported to the MVR condensed water tank 122 through the MVR condensed water pump 126.

[0042] In order to achieve stable delivery of the mixed liquid, a siphon tank 113 is further provided between the input end of the MVR feed pump 101 and the raw liquid pool 5 .

[0043] like Figure 6-Figure 9 As shown, the single-effect evaporation crystallizer 2 of the present invention receives the mixed liquor mother liquor with a mass fraction of sodium chloride ≤10% and a diethylene glycol fraction ≥90% output by the MVR mother liquor pump 117 through the single-effect feed pump 201, passes the mixed liquor into the single-effect concentration component, continues to heat the mother liquor through the single-effect concentration component, makes it boil and evaporate, removes most of the water, precipitates crystals, forms a concentrated liquid with a higher concentration, passes the concentrated liquid into the single-effect concentration component, performs solid-liquid separation on it through the single-effect concentration component, and the separated solid is discharged from the system, and the liquid returns to the single-effect concentration component to continue evaporation and concentration, and the concentrated liquid is regularly and quantitatively discharged into the distillation mechanism 3 to avoid the accumulation of organic matter and high-boiling-point substances in the single-effect evaporation crystallizer 2, so as to maintain the stable operation of the single-effect evaporation crystallizer 2. During operation, the single-effect evaporation crystallizer 2 intermittently outputs a concentrated liquid with a mass fraction of sodium chloride ≤1% and a diethylene glycol fraction ≥95% to the distillation mechanism 3 through the single-effect solid-liquid separation component.

[0044] When the single-effect evaporation crystallizer 2 evaporates and concentrates the mixed liquid, the water in the mixed liquid evaporates, and the generated secondary steam is condensed through the single-effect condensation component, and the formed condensed water is discharged into the condensed water discharge system 7; the non-condensable gas in the single-effect evaporation crystallizer 2 is extracted through the single-effect vacuum component and discharged into the exhaust gas treatment system 8.

[0045] In order to ensure orderly feeding, a single-effect feeding buffer tank 203 is provided at the input end of the single-effect feeding pump 201. A single-effect stirring device is provided on the single-effect feeding buffer tank 203, which can stir the mixed liquid entering the single-effect feeding buffer tank 203 to ensure the fluidity of the mixed liquid and avoid its agglomeration and affect the flow.

[0046] In order to achieve heating and concentrating treatment of the concentrated liquid discharged from the output end of the single-effect feed pump 201, the single-effect concentrating components in the single-effect evaporation crystallizer 2 include a single-effect heater 204, a single-effect separator 205, a single-effect circulation pump 206 and a single-effect discharge pump 207.

[0047] The single-effect heater 204 has a single-effect heating inlet 20401, a single-effect heating outlet 20402, a single-effect heat transfer oil inlet 20403 and a single-effect heat transfer oil outlet 20404; the single-effect separator 205 has a single-effect circulation inlet 20501, a single-effect circulation outlet 20502, a single-effect secondary steam outlet 20503, a single-effect slurry outlet 20504, a single-effect concentrated liquid outlet 20505 and a single-effect cleaning inlet 20506. Among them, the single-effect heat transfer oil inlet 20403 and the single-effect heat transfer oil outlet 20404 allow the high-temperature heat transfer oil provided by the heat transfer oil source 9 to pass through the single-effect heater 204 to heat the mixed liquid in the single-effect heater 204; the single-effect circulation inlet 20501 is connected with the output end of the single-effect feed pump 201 and the single-effect heating inlet 20401, the single-effect heating outlet 20402 and the single-effect concentrated liquid outlet 20505 are both connected with the single-effect heating inlet 20401 through the single-effect circulation pump 206, the single-effect slurry outlet 20504 is connected with the input end of the single-effect discharge pump 207, and the output end of the single-effect discharge pump 207 is connected with the single-effect solid-liquid separation component; the single-effect cleaning inlet 20506 is connected with the single-effect condensation component.

[0048] After adopting the above structure, the high-temperature heat transfer oil provided by the heat transfer oil source 9 passes through the single-effect heat transfer oil inlet 20403 and the single-effect heat transfer oil outlet 20404 through the single-effect heater 204, and the single-effect feed pump 201 transports the mixed liquid to the single-effect circulation inlet 20501. Under the action of the single-effect circulation pump 206, the mixed liquid circulates between the single-effect separator 205 and the single-effect heater 204, and exchanges heat with the heat transfer oil to increase the temperature, so that the mixed liquid evaporates and concentrates after entering the single-effect separator 205. After the mixed liquid reaches the supersaturated state, crystals precipitate. The mixed liquid crystal slurry composed of the alert and the mother liquor is discharged from the single-effect concentrated liquid outlet 20505 by the single-effect discharge pump 207 for solid-liquid separation.

[0049] The single-effect condensing component includes a single-effect condenser 208, a single-effect condensing water tank 212 and a single-effect condensing water pump 213. The single-effect condenser 208 has a single-effect secondary steam inlet 20801, a single-effect non-condensable gas inlet 20802, a single-effect non-condensable gas outlet 20803, a single-effect cooling inlet 20804, a single-effect cooling outlet 20805 and a single-effect condensing water outlet 20806; the single-effect vacuum component includes a single-effect vacuum pump 209, a single-effect vacuum tank 210 and a single-effect vacuum heat exchanger 211.

[0050] Specifically, the single-effect secondary steam inlet 20801 is connected to the single-effect secondary steam outlet 20503, the single-effect condensed water outlet 20806 is connected to the single-effect condensed water tank 212, the single-effect non-condensable gas inlet 20802 is connected to the top of the single-effect condensed water tank 212, the single-effect non-condensable gas outlet 20803 is connected to the input end of the single-effect vacuum pump 209, the output end of the single-effect vacuum pump 209 is connected to the single-effect vacuum tank 210, the single-effect vacuum tank 210 is connected to the exhaust gas treatment system 8, the single-effect vacuum pump 209 and the single-effect vacuum tank 210 are connected through the single-effect vacuum heat exchanger 211, and the refrigerant of the single-effect vacuum heat exchanger 211 is the circulating cooling water provided by the cooling water source 10; the single-effect cooling inlet 20804 is used for the introduction of circulating cooling water of the cooling water source 10, and the single-effect cooling inlet 20804 is used to pass the circulating cooling water after heat exchange into the cooling water source 10.

[0051] After adopting the above structure, during the evaporation and concentration process, the secondary steam generated by the single-effect separator 205 enters the single-effect condenser 208 through the single-effect secondary steam inlet 20801, and at the same time, the circulating cooling water of the cooling water source 10 enters the single-effect condenser 208 through the single-effect cooling inlet 20804, exchanges heat with the secondary steam, and is discharged through the single-effect cooling outlet 20805. After the secondary steam is cooled after the heat exchange, it forms condensed water, which is discharged through the single-effect condensed water outlet 20806 and enters the single-effect condensed water tank 212 for storage. The single-effect condensed water tank 212 is pumped into the single-effect condensed water tank 212 by the single-effect condensed water pump 213. The condensed water is discharged into the condensed water discharge system 7; the output end of the single-effect condensed water pump 213 is also connected to the single-effect cleaning inlet 20506, which is convenient for flushing and cleaning the inside of the single-effect separator 205, removing the sediment and crystalline impurities attached to the inner wall, and ensuring the normal evaporation and concentration of the single-effect separator 205; the non-condensable gas in the single-effect condensed water tank 212 can enter the single-effect condenser 208 through the single-effect non-condensable gas outlet 20803. After starting the single-effect vacuum pump 209, the non-condensable gas can be extracted from the single-effect non-condensable gas outlet 20803 and then discharged into the exhaust gas treatment system 8 through the single-effect vacuum tank 210.

[0052] The single-effect solid-liquid separation component includes a single-effect thickener 214, a single-effect centrifuge 215, a single-effect mother liquid tank 216 and a single-effect mother liquid pump 217, wherein the single-effect thickener 214 has a single-effect thickening inlet 21401, a single-effect thickening outlet 21402 and a single-effect overflow port 21403, and the single-effect centrifuge 215 has a single-effect centrifuge inlet 21501, a single-effect solid outlet 21502 and a single-effect liquid outlet 21503. The single-effect thick inlet 21401 is connected to the output end of the single-effect discharge pump 207, the single-effect thick outlet 21402 is connected to the single-effect centrifugal inlet 21501, the single-effect overflow port 21403 and the single-effect liquid outlet 21503 are both connected to the single-effect mother liquid tank 216, and the single-effect mother liquid tank 216 is connected to the input end of the single-effect feed pump 201 through the single-effect mother liquid pump 217, and the output end of the single-effect mother liquid pump 217 is also connected to the distillation mechanism 3.

[0053] The structure of the single-effect solid-liquid separation component and its function in the single-effect evaporation crystallizer 2 are similar to the structure of the MVR solid-liquid separation component and its function in the MVR evaporation crystallizer 1. Both are used to separate the thick slurry into solid and liquid, discharge the solid from the system, return the mother liquor to continue evaporation and concentration, and input part of the mother liquor to the next process for processing at a regular and quantitative manner. No further details will be given here.

[0054] A further improvement is that a cyclone 202 is provided at the output end of the single-effect solid-liquid separation component, and a cyclone inlet 20201 is provided on the side wall of the cyclone 202, and the cyclone inlet 20201 is connected to the output end of the single-effect mother liquor pump 217. The cyclone 202 is also provided with a heavy outlet 20202 and a light outlet 20203, and the heavy outlet 20202 is connected to the distillation tower 301, and the light outlet 20203 is connected to the input end of the single-effect feed pump 201. Specifically, the light outlet 20203 is connected to the single-effect feed buffer tank 203.

[0055] After adopting the above structure, the mother liquor in the thick slurry is separated by the single-effect solid-liquid separation component, and the separated mother liquor is transported from the cyclone inlet 20201 to the cyclone 202 by the single-effect mother liquor pump 217. After the mother liquor enters from the periphery of the inner wall of the cyclone 202, a strong cyclone shear turbulent motion is generated. Due to the density difference between the two-phase mixed liquids, the centrifugal force, centripetal buoyancy and fluid drag they are subjected to are different, thereby achieving the purpose of separation and classification. The lighter mother liquor is returned to the single-effect feed buffer tank 203, and is continuously transported to the single-effect concentration component through the single-effect feed pump 201 for evaporation and concentration treatment, thereby improving the solute recovery and utilization rate. In the heavier mother liquor, the mass fraction of sodium chloride is ≤1% and the fraction of diethylene glycol is ≥95%. The mother liquor is transported to the distillation mechanism 3 for distillation and purification treatment.

[0056] like Figure 10-12As shown, the distillation mechanism 3 of the present invention mainly includes a distillation tower 301, a distillation discharge pump 302 and a distillation condensation component. The distillation tower 301 receives the high-concentration diethylene glycol mixed liquid graded by the single-effect mother liquor pump 217 through the cyclone 202, and at the same time, the distillation tower 301 inputs the heat transfer oil provided by the heat transfer oil source 9. After the heat transfer oil and the diethylene glycol mixed liquid are heat-exchanged, secondary steam and concentrated liquid are formed. The concentrated liquid is divided into two parts by the distillation discharge pump 302, one part of which is returned to the single-effect evaporation crystallizer 2 of the previous process to continue heating and concentrating, and the other part is input to the vacuum de-oiling mechanism 4 of the next process for further purification. In the distillation process, the secondary steam generated is condensed by the distillation condensation component, and the formed condensed water is passed into the condensed water discharge system 7.

[0057] Specifically, the distillation tower 301 is arranged horizontally, and is provided with a distillation material inlet 30101, a distillation material outlet 30102, a distillation heat transfer inlet 30103, a distillation heat transfer outlet 30104 and a distillation reflux port 30105. A heat transfer oil pipe is fixed in the distillation tower 301, and the two ends of the heat transfer oil pipe are respectively connected to the distillation heat transfer inlet 30103 and the distillation heat transfer outlet 30104. The top of the distillation tower 301 is fixedly connected with a kettle section 308 arranged in a vertical direction, and the top of the kettle section 308 is provided with a distillation secondary steam outlet 30801. The upper side of the kettle section 308 is provided with a distillation secondary steam outlet 30802. A distillation spray inlet 30802 is provided on the wall; the distillation material inlet 30101 is connected with the heavy outlet 20202, the distillation material outlet 30102 is connected with the input end of the distillation discharge pump 302, the output end of the distillation discharge pump 302 is connected with the vacuum de-oiling mechanism 4, and the output end of the distillation discharge pump 302 is also connected with the distillation reflux port 30105; the distillation heat transfer inlet 30103 and the distillation heat transfer outlet 30104 are respectively used for introducing heat transfer oil, which is provided by a heat transfer oil source 9; the distillation secondary steam outlet 30801 and the distillation spray inlet 30802 are both connected with the distillation condensation component.

[0058] After adopting the above structure, the heat transfer oil source 9 transports the heat transfer oil to the heat transfer oil pipe in the distillation tower 301 through the distillation heat transfer inlet 30103, and at the same time, the mixed liquid output by the single-effect evaporation crystallizer 2 is introduced into the distillation material inlet 30101. The mixed liquid exchanges heat with the heat transfer oil to generate secondary steam, which is discharged through the distillation secondary steam outlet 30801 and then condensed by the distillation condensation component. After the solute in the mixed liquid evaporates, it is discharged through the distillation material outlet 30102. Under the action of the distillation discharge pump 302, it returns to the distillation tower 301 through the distillation reflux port 30105 to continue to exchange heat with the heat transfer oil, gradually increase the concentration, and remove moisture until the mass fraction of sodium chloride in the mixed liquid is ≤1% and the fraction of diethylene glycol is ≥99%. The distillation discharge pump 302 transports the concentrated liquid to the vacuum deoiling mechanism 4 for purification.

[0059] A further improvement is that the distillation condensation component includes a distillation condenser 303, a pressure stabilizing tank 304, a distillation cooler 305, a distillation condensation water tank 306 and a distillation condensation water pump 307 which are connected in sequence, and the distillation condenser 303 is connected to the distillation tower 301.

[0060] Specifically, the rectification condenser 303 is provided with a rectification secondary steam inlet 30301, a rectification condensation outlet 30302, a rectification circulation inlet 30303, a rectification circulation outlet 30304 and a rectification condensation balance port 30305, the pressure stabilizing tank 304 is provided with a rectification stabilizing pressure inlet 30401, a rectification stabilizing pressure outlet 30402 and a rectification stabilizing pressure balance port 30403, and the rectification cooler 305 is provided with a rectification condensation water inlet 30501, a rectification condensation water outlet 30502, The rectification cooling water inlet 30503 and the rectification cooling water outlet 30504, wherein the rectification secondary steam inlet 30301 is connected with the rectification secondary steam outlet 30801, the rectification condensation outlet 30302 is connected with the rectification pressure stabilizing inlet 30401, the rectification pressure stabilizing outlet 30402 is connected with the rectification condensation water inlet 30501, the rectification condensation water outlet 30502 is connected with the input end of the rectification condensation water pump 307, and the output end of the rectification condensation water pump 307 is connected with the condensation water discharge system 7; The distillation condensation balance port 30305 is connected to the distillation pressure stabilization balance port 30403; the distillation condensation water inlet 30501, the distillation condensation water outlet 30502, the distillation circulation inlet 30303 and the distillation circulation outlet 30304 are connected in sequence, and the refrigerant entering the distillation condensation water inlet 30501 is the cooling water provided by the cooling water source 10, so that the circulating cooling water can pass through the distillation condensation water tank 306, the distillation cooler 305 and the distillation condenser 303 in sequence; and the distillation condenser 303 The secondary steam discharged from the kettle section 308 is introduced into the distillation secondary steam inlet 30301, and after the secondary steam is condensed to form condensed water, it enters the distillation condensate water tank 306 through the pressure-stabilizing tank 304, and is finally transported to the condensate water discharge system 7 by the distillation condensate pump 307. The pressure-stabilizing tank 304 can stabilize the high-frequency pressure fluctuations and low-frequency pressure fluctuations caused by the generation of secondary steam in the distillation mechanism 3, reduce the amplitude and frequency of the pressure fluctuations, and make the steam pressure output from the pressure-stabilizing tank 304 more stable.

[0061] like Figure 13-Figure 15 As shown, the vacuum deoiling mechanism 4 of the present invention mainly includes an enamel kettle 401 , an enamel condensation component, an enamel vacuum component and an enamel discharge pump 402 .

[0062] When the vacuum deoiling mechanism 4 is in operation, the mixed liquid with a sodium chloride mass fraction of ≤1% and a diethylene glycol fraction of ≥99 output by the distillation discharge pump 302 is received by the enamel kettle 401, and the mixed liquid is evenly heated by the stirring of the paddle blades in the enamel kettle 401. A vacuum negative pressure environment is generated under the action of the enamel vacuum component, so that the diethylene glycol boils and evaporates. The secondary steam formed is condensed by the enamel condensation component to form high-purity liquid diethylene glycol, which is then transported to the purified liquid collection system 11 through the enamel discharge pump 402. The concentrated sodium chloride salt mud in the enamel kettle 401 is diluted by the condensed water produced by the MVR evaporation crystallizer 1 and discharged out of the system by the enamel discharge pump 402.

[0063] Specifically, in the vacuum deoiling mechanism 4, two enamel kettles 401 are provided and distributed in parallel to ensure the purification efficiency, and the enamel kettle 401 is provided with an enamel feed inlet 40101, an enamel discharge port 40102, an enamel secondary steam outlet 40103, an enamel dilution port 40104, an enamel overflow port 40105, an enamel thermal oil inlet 40106 and an enamel thermal oil outlet 40107.

[0064] The enamel feed port 40101 is connected to the output end of the distillation discharge pump 302 so that the mixed liquid to be evaporated is input into the enamel kettle 401 through the distillation discharge pump 302. The enamel discharge port 40102 is connected to the input end of the enamel discharge pump 402. The enamel dilution port 40104 is connected to the output end of the MVR condensate water pump 123, so that after evaporation and concentration, the sodium chloride salt mud remaining in the enamel kettle 401 can be extracted by the MVR condensate water pump 123 to extract the condensate in the MVR condensate water tank 122, and transported to the enamel kettle 401 through the enamel dilution port 40104 to dilute the salt mud and increase its fluidity, so as to facilitate discharge through the enamel discharge port 40102. Under the action of the enamel discharge pump 402, the system is discharged. The enamel overflow port 40105 facilitates the discharge of excess condensate.

[0065] The enameled heat transfer oil inlet 40106 and the enameled heat transfer oil outlet 40107 are respectively used for introducing and discharging heat transfer oil. The heat transfer oil is provided by a heat transfer oil source 9 to heat the concentrated liquid in the enameled kettle 401, so that the diethylene glycol in the concentrated liquid boils and evaporates, and after forming secondary steam, it is discharged through the enameled secondary steam outlet 40103.

[0066] The enamel condensation component includes an enamel condenser 403, an enamel condensation water tank 404, and an enamel condensation water pump 405. The enamel condenser 403 is provided with an enamel secondary steam inlet 40301, an enamel condensation water outlet 40302, an enamel cooling inlet 40303 and an enamel cooling outlet 40304. The enamel secondary steam inlet 40301 is connected to the enamel secondary steam outlet 40103 to pass the diethylene glycol vapor generated during the evaporation process into the enamel condenser 403. The enamel cooling inlet 40303 and the enamel cooling outlet 40304 are connected to the cooling water source 10, so that the cooling water source 10 can pass circulating cooling water into the enamel condenser 403 to condense the diethylene glycol vapor. After condensation, the diethylene glycol vapor is converted into liquid and enters the enamel condensation water tank 404. The liquid diethylene glycol is extracted by the enamel condensation water pump 405 and transported to the purification liquid collection system 11 to complete the purification and collection work.

[0067] The enamel vacuum component includes an enamel vacuum pump 406, an enamel vacuum tank 407 and an enamel vacuum heat exchanger 408. The input end of the enamel vacuum pump 406 is connected to the top of the enamel condensate tank 404, and the output end is connected to the enamel vacuum tank 407. The enamel vacuum tank 407 is connected to the exhaust gas treatment system 8. The enamel vacuum pump 406 and the enamel vacuum tank 407 are both connected to the enamel vacuum heat exchanger 408. The refrigerant of the enamel vacuum heat exchanger 408 is the circulating cooling water provided by the cooling water source 10.

[0068] After adopting the above structure, the non-condensable gas in the enamel condensate tank 404 can be extracted by the enamel vacuum pump 406, transported to the enamel vacuum tank 407, and then discharged into the exhaust gas treatment system 8.

[0069] Based on the diethylene glycol and sodium chloride mixed solution purification device of the present invention, the present invention also discloses a diethylene glycol and sodium chloride mixed solution purification process, such as Fig.16 As shown, the following steps are included: S100, MVR evaporation concentration: preheat the mixed liquid and then force circulation heating to concentrate the mixed liquid into slurry, then perform solid-liquid separation, the separated solid is discharged from the system, the separated mother liquor is a mother liquor with a sodium chloride content of ≤10% and a diethylene glycol content of ≥90%, the mother liquor is continued to be forced circulation heated and part of the mother liquor is discharged regularly and quantitatively; S200, single-effect evaporation and concentration: the mother liquor discharged in step S100 is subjected to single-effect evaporation and concentration treatment to obtain a slurry with a higher concentration, the slurry is subjected to solid-liquid separation, the separated solid is discharged from the system, the separated mother liquor is a mother liquor with a sodium chloride content of ≤1% and a diethylene glycol content of ≥95%, the mother liquor is further subjected to single-effect evaporation and concentration, and part of the mother liquor is discharged at a regular and quantitative time; S300, distillation: the mother liquor discharged in step S200 is distilled and evaporated, and concentrated to obtain a feed liquid with a sodium chloride content of ≤1% and a diethylene glycol content of ≥95%, and then discharged; S400, evaporation and purification: the feed liquid discharged in step S300 is subjected to boiling evaporation to separate the sodium chloride salt sludge and the secondary steam generated by the evaporation of diethylene glycol, the sodium chloride salt sludge is discharged from the system, and the secondary steam of diethylene glycol is heat-exchanged with condensed water, so that the secondary steam of diethylene glycol is condensed into diethylene glycol with a purity of more than 99% and is in liquid state, and then collected.

[0070] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the technical principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A device for purifying a mixture of diethylene glycol and sodium chloride, comprising an MVR evaporation crystallizer (1), a single-effect evaporation crystallizer (2), a rectification mechanism (3) and a vacuum deoiling mechanism (4) connected in sequence, characterized in that: The MVR evaporation crystallizer (1) comprises: an MVR feed pump (101), a preheating component, an MVR concentration component, a centrifugal compressor (102), an MVR solid-liquid separation component, an MVR condensation component and an MVR vacuum component; The input end of the MVR feed pump (101) is connected to the raw liquid pool (5), and the output end is connected to the MVR concentration component through the preheating component. The MVR concentration component is used to heat the raw liquid to generate and output secondary steam and crystal slurry. The heating source of the MVR concentration component includes raw steam provided by the raw steam source (6) and compressed steam formed after the centrifugal compressor (102) performs work on the secondary steam. The MVR solid-liquid separation component is used to discharge the separated solid after the solid-liquid separation of the crystal slurry output by the MVR concentration component. A part of the separated mother liquid is discharged into the single-effect evaporation crystallizer (2), and the other part is returned to the MVR concentration component. The MVR condensation component is used to receive condensed water formed by cooling the raw steam and the compressed steam and then pass the condensed water into the condensed water discharge system (7). The MVR vacuum component is used to discharge the non-condensable gas in the MVR evaporation crystallizer (1) into the tail gas treatment system (8); The single-effect evaporation crystallizer (2) comprises: a single-effect feed pump (201), a single-effect concentration component, a single-effect solid-liquid separation component, a single-effect condensation component and a single-effect vacuum component; The single-effect feed pump (201) is used to input the mother liquor output by the MVR solid-liquid separation component into the single-effect concentration component. The single-effect concentration component is used to heat the mother liquor to generate secondary steam and crystal slurry. The heating source of the single-effect concentration component includes heat transfer oil provided by a heat transfer oil source (9). The single-effect solid-liquid separation component is used to discharge the separated solid after solid-liquid separation of the crystal slurry output by the single-effect concentration component. A part of the separated mother liquor is discharged into the distillation mechanism (3), and the other part is returned to the single-effect concentration component. The single-effect condensation component is used to condense the secondary steam output by the single-effect concentration component to form condensed water, which is then introduced into the condensed water discharge system (7). The single-effect vacuum component is used to discharge the non-condensable gas in the single-effect evaporation crystallizer (2) into the tail gas treatment system (8); The distillation mechanism (3) comprises: a distillation tower (301), a distillation discharge pump (302) and a distillation condensation component; The distillation tower (301) is used to receive and heat the mother liquid output by the single-effect solid-liquid separation component to generate secondary steam and feed liquid. The heating source of the distillation tower (301) includes heat transfer oil provided by a heat transfer oil source (9). The distillation discharge pump (302) is used to return a portion of the feed liquid output by the distillation tower (301) to the input end of the single-effect feed pump (201), and discharge the other portion into the vacuum deoiling mechanism (4). The distillation condensation component is used to condense the secondary steam output by the distillation tower (301) into condensed water, and then pass it into the condensed water discharge system (7). The vacuum deoiling mechanism (4) comprises: an enamel kettle (401), an enamel condensation component, an enamel vacuum component and an enamel discharge pump (402); The enamel kettle (401) is used to receive and heat the mother liquor output by the distillation discharge pump (302) to generate secondary steam and salt mud. The heating source of the enamel kettle (401) includes heat transfer oil provided by a heat transfer oil source (9). The enamel discharge pump (402) is used to discharge the salt mud generated by the enamel kettle (401) out of the system. The enamel condensation component is used to condense the secondary steam output by the enamel kettle (401) to form a purified liquid and then pass it into the purified liquid collection system (11). The enamel vacuum component is used to discharge the non-condensable gas in the vacuum de-oiling mechanism (4) into the exhaust gas treatment system (8).

2. The mixed solution purification device of diethylene glycol and sodium chloride according to claim 1, characterized in that: The preheating component comprises a non-condensable gas preheater (103), a condensate preheater (104) and a live steam preheater (105) which are arranged in sequence, the heating source of the non-condensable gas preheater (103) being the non-condensable gas in the MVR concentration component, the heating source of the condensate preheater (104) being the condensate received by the MVR condensation component, and the heating source of the live steam preheater (105) being the live steam provided by the live steam source (6).

3. The mixed solution purification device of diethylene glycol and sodium chloride according to claim 1, characterized in that: A scrubbing assembly is also provided between the MVR concentrating assembly and the centrifugal compressor (102). The scrubbing assembly is used to perform vapor-liquid separation on the secondary steam generated by the MVR concentrating assembly so as to input dry saturated steam into the centrifugal compressor (102). The cleaning liquid of the scrubbing assembly is condensed water collected by the MVR condensing assembly.

4. The mixed solution purification device of diethylene glycol and sodium chloride according to claim 3, characterized in that: The scrubbing component comprises a scrubbing tower (106), a scrubbing circulation pump (107) and a scrubbing discharge pump (108). The scrubbing tower (106) has a mixed steam inlet (10601), a cleaning liquid discharge outlet (10602) and a cleaning liquid input port (10603). The mixed steam inlet (10601) is used to input secondary steam generated by the MVR concentration component. The cleaning liquid discharge outlet (10602) is connected to the mixed steam inlet (10601) through the scrubbing circulation pump (107). The input end of the scrubbing discharge pump (108) is connected to the cleaning liquid discharge outlet (10602), and the output end is arranged in the raw liquid pool (5). The cleaning liquid input port (10603) is used to input condensed water collected by the MVR condensation component.

5. The mixed solution purification device of diethylene glycol and sodium chloride according to claim 1, characterized in that: The MVR concentration component comprises an MVR crystallizer (109), an MVR heater (110), an MVR circulation pump (111) and an MVR discharge pump (112); the crystallizer has an MVR circulation inlet (10901), an MVR circulation outlet (10902) and an MVR crystallization outlet (10903); the MVR crystallization outlet (10903) is connected to the MVR solid-liquid separation component via the MVR discharge pump (112); two MVR heaters (110) are provided, which are respectively located between the MVR circulation inlet (10901) and the output end of the circulation pump and between the MVR circulation outlet (10902) and the input end of the circulation pump.

6. The device for purifying a mixed solution of diethylene glycol and sodium chloride according to claim 1, characterized in that: A cyclone (202) is provided at the output end of the single-effect solid-liquid separation component, a cyclone inlet (20201) is provided on the side wall of the cyclone (202), and a heavy outlet (20202) and a light outlet (20203) are also provided on the cyclone (202), the heavy outlet (20202) is connected to the distillation tower (301), and the light outlet (20203) is connected to the input end of the single-effect feed pump (201).

7. The device for purifying a mixed solution of diethylene glycol and sodium chloride according to claim 1, characterized in that: The rectification and condensation component comprises a rectification condenser (303), a pressure stabilizing tank (304), a rectification cooler (305), a rectification condensation water tank (306) and a rectification condensation water pump (307) which are connected in sequence; the rectification condenser (303) is connected to the rectification tower (301).

8. The device for purifying a mixed solution of diethylene glycol and sodium chloride according to claim 1, characterized in that: At least two enamel kettles (401) are provided and distributed in parallel.

9. The device for purifying a mixed solution of diethylene glycol and sodium chloride according to claim 1, characterized in that: The enamel kettle (401) is connected to the MVR condensation component so that the condensed water collected by the MVR condensation component can dilute the sodium chloride salt mud formed after evaporation and concentration in the enamel kettle (401).

10. A process for purifying a mixed solution of diethylene glycol and sodium chloride, characterized in that: The following steps are involved: S100, MVR evaporation concentration: preheat the mixed liquid and then force circulation heating to concentrate the mixed liquid into slurry, then perform solid-liquid separation, the separated solid is discharged from the system, the separated mother liquor is a mother liquor with a sodium chloride content of ≤10% and a diethylene glycol content of ≥90%, the mother liquor is continued to be forced circulation heated and part of the mother liquor is discharged regularly and quantitatively; S200, single-effect evaporation and concentration: the mother liquor discharged in step S100 is subjected to single-effect evaporation and concentration treatment to obtain a slurry with a higher concentration, the slurry is subjected to solid-liquid separation, the separated solid is discharged from the system, the separated mother liquor is a mother liquor with a sodium chloride content of ≤1% and a diethylene glycol content of ≥95%, the mother liquor is further subjected to single-effect evaporation and concentration, and part of the mother liquor is discharged at a regular and quantitative time; S300, distillation: the mother liquor discharged in step S200 is distilled and evaporated, and concentrated to obtain a feed liquid with a sodium chloride content of ≤1% and a diethylene glycol content of ≥95%, and then discharged; S400, evaporation and purification: the feed liquid discharged in step S300 is subjected to boiling evaporation to separate the sodium chloride salt sludge and the secondary steam generated by the evaporation of diethylene glycol, the sodium chloride salt sludge is discharged from the system, and the secondary steam of diethylene glycol is heat exchanged with condensed water, so that the secondary steam of diethylene glycol is condensed into diethylene glycol with a purity of more than 99% and is in liquid state, and then collected.

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