Mechanical vapor recompression heat pump distillation system

Abstract

Embodiments of the present invention relate to the technical field of rectification and evaporation, and provide a mechanical vapor recompression heat pump rectification system. The mechanical vapor recompression heat pump rectification system provided by the embodiments of the present invention includes: a material preheating subsystem, a rectification subsystem, and an evaporation subsystem. Among them, the outlet of the material preheating subsystem is connected to the inlet of the rectification subsystem; the outlet of the rectification subsystem is connected to the inlet of the evaporation subsystem to discharge the steam generated during the rectification process into the evaporation subsystem for heat exchange, and then condense the steam into a liquid and discharge it to the finished product tank; the outlet of the evaporation subsystem is connected to the inlet of the material preheating subsystem to use the secondary steam generated during the evaporation process as the heat source for preheating the material in the material preheating subsystem after compression. The mechanical vapor recompression heat pump rectification system provided by the embodiments of the present invention solves the problems of difficult compressor selection and high manufacturing cost existing in the traditional direct compression heat pump rectification system for the steam at the top of the rectification column.

Description

Technical Field

[0001] The present invention relates to the technical field of rectification and evaporation, and particularly to a mechanical vapor recompression heat pump rectification system. Background Art

[0002] Rectification is an indispensable part in the production processes of industries such as petroleum and chemical industry, and is also a major energy-consuming link. Traditional processes mainly rely on single-effect and double-effect rectification. The equipment is simple and the investment is relatively low. However, the whole process requires a large amount of live steam as the heat source, resulting in high system energy consumption, greatly increasing the operating cost, and bringing huge challenges to the energy field.

[0003] MVR (mechanical vapor recompression) is the abbreviation of mechanical vapor recompression technology. The MVR mechanical vapor recompression heat pump rectification technology effectively reduces the consumption of bottom heat utility and top cold utility by fully recycling the top steam of the tower, and is a prominent and effective energy-saving method. However, most of the currently developed mechanical vapor recompression heat pump rectification processes adopt the form of directly compressing the top steam of the tower. Since the material concentration in the steam is relatively high and it directly contacts the compressor, there are potential hazards such as leakage, explosion, and corrosion during the compression process, resulting in problems such as difficult compressor selection and high manufacturing cost, and also restricting the development of the mechanical vapor recompression heat pump rectification technology. Therefore, designing a safe and efficient mechanical vapor recompression heat pump rectification system has become an urgent problem to be solved. Summary of the Invention

[0004] In order to solve the problems of difficult compressor selection and high manufacturing cost caused by directly compressing the top steam of the rectification tower in the prior art, an embodiment of the present invention provides a mechanical vapor recompression heat pump rectification system.

[0005] According to an embodiment of the present invention, the mechanical vapor recompression heat pump rectification system includes: a material preheating subsystem, a rectification subsystem, and an evaporation subsystem. Among them, the outlet of the material preheating subsystem is connected to the inlet of the rectification subsystem; the outlet of the rectification subsystem is connected to the inlet of the evaporation subsystem to discharge the steam generated during the rectification process into the evaporation subsystem for heat exchange, and then condense the steam into a liquid and discharge it to the product tank; the outlet of the evaporation subsystem is connected to the inlet of the material preheating subsystem to use the secondary steam generated during the evaporation process as the heat source for preheating the material in the material preheating subsystem after compression.

[0006] According to an embodiment of the present invention, the rectification subsystem includes: a rectification column and a reboiler, wherein a first outlet of the rectification column is connected to an inlet of the evaporation subsystem, a second outlet of the rectification column is connected to a first inlet of the reboiler, and a first inlet of the rectification column is connected to an outlet of the material preheating subsystem; a first outlet of the reboiler is connected to a second inlet of the rectification column.

[0007] According to an embodiment of the present invention, the evaporation subsystem includes: an evaporator, a finished product buffer tank, and a finished product pump, wherein a first inlet of the evaporator is connected to a first outlet of the rectifier, a first outlet of the evaporator is connected to an inlet of the finished product pump through the finished product buffer tank, and an outlet of the finished product pump is connected to an inlet of the material preheating subsystem.

[0008] According to an embodiment of the present invention, the rectification subsystem further includes a reflux pump, an inlet of the reflux pump is connected to an outlet of the finished product buffer tank, and an outlet of the reflux pump is connected to a third inlet of the rectification column.

[0009] According to an embodiment of the present invention, the evaporation subsystem further includes: a separator, a first steam compressor, and a forced circulation pump, wherein an inlet of the separator is connected to a second outlet of the evaporator, a first outlet of the separator is connected to an inlet of the first steam compressor, and an outlet of the first steam compressor is connected to an inlet of the material preheating subsystem; a second outlet of the separator is connected to an inlet of the forced circulation pump, and an outlet of the forced circulation pump is connected to a second inlet of the evaporator.

[0010] According to an embodiment of the present invention, the evaporation subsystem further includes a second steam compressor, an inlet of the second steam compressor is connected to an outlet of the first steam compressor, and an outlet of the second steam compressor is connected to a second inlet of the reboiler through a first pipeline, wherein a pipe section for introducing live steam is also connected to the first pipeline.

[0011] According to an embodiment of the present invention, the evaporation subsystem further includes a first condensate tank and a first condensate pump connected in series with the first condensate tank, and a second condensate tank and a second condensate pump connected in series with the second condensate tank, wherein an inlet of the first condensate tank is connected to an outlet of the material preheating subsystem, and an inlet of the second condensate tank is connected to a second outlet of the reboiler; outlets of the first condensate pump and the second condensate pump are respectively connected to an inlet of the material preheating subsystem; and an outlet of the first condensate pump is connected to the first steam compressor and the second steam compressor respectively through a second pipeline.

[0012] According to an embodiment of the present invention, the material preheating subsystem includes: a primary preheater, a secondary preheater, and a tertiary preheater that are serially arranged in sequence, wherein a first inlet of the primary preheater is connected to an outlet of the finished product pump; a first inlet of the secondary preheater is connected to outlets of the first condensate pump and the second condensate pump; a first inlet of the tertiary preheater is connected to an outlet of the first steam compressor, a first outlet of the tertiary preheater is connected to a first inlet of the rectifier, and a second outlet of the tertiary preheater is connected to the first condensate tank.

[0013] According to an embodiment of the present invention, the mechanical vapor recompression heat pump rectification system further includes a feed subsystem, the feed subsystem includes a raw material buffer tank and a feed pump that are serially arranged in sequence, wherein an outlet of the feed pump is connected to a second inlet of the primary preheater.

[0014] According to an embodiment of the present invention, the mechanical vapor recompression heat pump rectification system further includes: a finished product subsystem, the finished product subsystem includes: the finished product tank, a vacuum pump, a tail gas cooler, and a bottom product cooler and a bottom product tank that are serially arranged in sequence, wherein an inlet of the finished product tank is connected to a first outlet of the primary preheater; a first inlet of the bottom product cooler is connected to a first outlet of the secondary preheater, a second inlet of the bottom product cooler is connected to a third outlet of the reboiler, a first outlet of the bottom product cooler is connected to a second inlet of the separator; an inlet of the vacuum pump is connected to a third outlet of the tertiary preheater and is connected to a fourth outlet of the reboiler; an inlet of the tail gas cooler is connected to a third outlet of the evaporator, and an outlet of the tail gas cooler is connected to an inlet of the finished product buffer tank.

[0015] The mechanical vapor recompression heat pump rectification system provided by the embodiment of the present invention exchanges heat for the steam generated during the rectification process of the rectification subsystem in the evaporation subsystem, and then condenses the steam into a liquid state. After heat exchange, the water in the evaporation subsystem becomes a gas-liquid mixture. This gas-liquid mixture is used as the heat source for preheating in the material preheating subsystem after gas-liquid separation and compression, solving the problems of difficult compressor selection and high manufacturing cost existing in the traditional direct compression type heat pump rectification system for the steam at the top of the rectification tower, eliminating the potential problems of steam leakage, explosion, and corrosion during the compression process, and at the same time recovering the latent heat of the top steam and the heat of the bottom product, improving the heat utilization rate of the rectification process, and greatly saving the operation cost. Description of the Drawings

[0016] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0017] Figure 1 It is a schematic structural diagram of the mechanical vapor recompression heat pump distillation system provided by the embodiment of the present invention.

[0018] Explanation of the reference numerals in the drawings:

[0019] 1 - Raw material buffer tank; 2 - Feed pump; 3 - Primary preheater; 4 - Secondary preheater; 5 - Tertiary preheater; 6 - Distillation column; 7 - Reboiler; 8 - Evaporator; 9 - Separator; 10 - Forced circulation pump; 11 - Product buffer tank; 12 - First steam compressor; 13 - Second steam compressor; 14 - Reflux pump; 15 - Product pump; 16 - First condensate tank; 17 - Second condensate tank; 18 - Second condensate pump; 19 - First condensate pump; 20 - Product tank; 21 - Bottoms cooler; 22 - Bottoms tank; 23 - Tail gas cooler; 24 - Vacuum pump; 31 - First pipeline; 32 - Second pipeline. Detailed implementation manners

[0020] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the drawings in the embodiments of the present invention. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts fall within the scope of protection of the present invention.

[0021] In the description of the present invention, it should be noted that unless otherwise clearly defined and limited, the terms "installed", "connected", and "coupled" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two components. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0022] In addition, in the description of the present invention, unless otherwise stated, the meanings of "multiple", "multiple roots", "multiple groups" are two or more, and the meanings of "several", "several roots", "several groups" are one or more.

[0023] Now refer to Figure 1, embodiments provided by the present invention are described. It should be understood that the following is only a schematic embodiment of the present invention and does not constitute any special limitation to the present invention.

[0024] The mechanical vapor recompression heat pump distillation system provided by the embodiments of the present invention includes: a material preheating subsystem, a distillation subsystem, and an evaporation subsystem. Specifically, after being preheated in the material preheating subsystem, the material enters the distillation subsystem. The distillation subsystem utilizes the characteristics that each component in the material has different volatilities to achieve the separation of various substances with different boiling points. During the distillation process, the generated steam is discharged from the distillation subsystem and enters the evaporation subsystem. In the evaporation subsystem, the steam exchanges heat with the water in the evaporation subsystem, and then the steam is condensed into a liquid and discharged to the product tank. The water in the evaporation subsystem is heated and becomes a gas-liquid mixture. The gas-liquid mixture undergoes gas-liquid separation and compression to become high-temperature and high-pressure secondary steam, which enters the material preheating subsystem as the heat source for material preheating.

[0025] The mechanical vapor recompression heat pump distillation system provided by the embodiments of the present invention exchanges heat of the steam generated during the distillation process of the distillation subsystem in the evaporation subsystem, and then condenses the steam into a liquid state. The water after heat exchange becomes a gas-liquid mixture. The gas-liquid mixture undergoes gas-liquid separation and compression and is used as the heat source for preheating the material preheating subsystem, solving the problems of difficult compressor selection and high manufacturing cost existing in the traditional direct compression heat pump distillation system for the steam at the top of the distillation column. At the same time, it also eliminates the potential problems of steam leakage, explosion, and corrosion during the compression process, and at the same time recovers the latent heat of the top steam, improves the heat utilization rate of the distillation process, and greatly saves the operating cost.

[0026] As Figure 1 shown, in an embodiment of the present invention, the distillation subsystem includes: a distillation column 6 and a reboiler 7. Specifically, the outlet of the material preheating subsystem is connected to the first inlet of the distillation column 6. After being preheated, the material enters the distillation column 6. The steam generated during the distillation process enters the evaporation subsystem from the first outlet of the distillation column 6, exchanges heat with the water in the evaporation subsystem, and then the steam is condensed into a liquid and discharged to the product tank 20. The bottom liquid is discharged from the second outlet of the distillation column 6 into the tube-side logistics inlet of the reboiler 7. After heat exchange in the reboiler 7, part of the bottom liquid enters the distillation column 6 from the tube-side logistics outlet of the reboiler 7.

[0027] Further, in the embodiment of the present invention, the distillation column 6 can be a tray-type distillation column, a packed distillation column, or a hybrid distillation column.

[0028] Further, in the embodiment of the present invention, optionally, the reboiler 7 is a shell-and-tube heat exchanger. It should be noted that the reboiler 7 is only illustrative, and other forms of reboilers are also applicable to the present invention, not limited to the shell-and-tube heat exchanger defined in this embodiment.

[0029] As Figure 1 shown, in an embodiment of the present invention, the evaporation subsystem includes: an evaporator 8, a finished product buffer tank 11, and a finished product pump 15. Specifically, the steam generated during the rectification process enters the shell side of the evaporator 8 and exchanges heat with the water in the tube side of the evaporator 8. After heat exchange, the steam condenses into a liquid and is discharged from the shell side outlet of the evaporator 8 to the finished product buffer tank 11, and then enters the material preheating subsystem under the drive of the finished product pump 15 to preheat the material, thereby recycling the waste heat of the liquid. After the waste heat is recovered, the liquid enters the finished product tank 20 to achieve the collection of the finished product.

[0030] Further, in this embodiment, the evaporator 8 can be a falling film evaporator, a forced circulation evaporator, or a natural circulation evaporator. In terms of the heat exchange form, the evaporator 8 can be a shell and tube heat exchanger or a plate heat exchanger.

[0031] Further, in this embodiment, the finished product pump 15 can be a variable frequency pump or a power frequency pump.

[0032] Further, in an embodiment of the present invention, the rectification subsystem further includes a reflux pump 14. When the liquid flows out of the finished product buffer tank 11, it is divided into two branches. Part of the liquid enters the material waste heat subsystem under the drive of the finished product pump 15, and part of the liquid enters the rectification tower 6 under the drive of the reflux pump 14.

[0033] Further, in this embodiment, the reflux pump 14 can be a variable frequency pump or a power frequency pump.

[0034] Referring to Figure 1 , in an embodiment of the present invention, the evaporation subsystem further includes: a separator 9, a first steam compressor 12, and a forced circulation pump 10. Specifically, the steam generated during the rectification process exchanges heat with the water in the tube side of the evaporator 8 in the evaporator 8. After heat exchange, the water becomes a gas-liquid mixture. The gas-liquid mixture enters the separator 9 for gas-liquid separation. The separated steam enters the first steam compressor 12 and is compressed into a high-temperature and high-pressure gas, which enters the material preheating subsystem as a heat source for material preheating. The separated liquid continues to enter the tube side of the evaporator 8 under the drive of the forced circulation pump 10 and continues to exchange heat with the steam generated during the rectification process.

[0035] Further, in this embodiment, the first steam compressor 12 can be any one of a centrifugal steam compressor, a Roots steam compressor, or a screw steam compressor.

[0036] Further, in this embodiment, the forced circulation pump 10 can be a variable frequency pump or a power frequency pump.

[0037] Continuing to refer to Figure 1, in an embodiment of the present invention, the evaporation subsystem further includes: a second steam compressor 13. Specifically, after the gas separated from the separator 9 is compressed by the first steam compressor 12, a part of the gas enters the material preheating subsystem as the heat source for material preheating; a part is compressed again by the second steam compressor 13 and then enters the shell side of the reboiler 7 through the first pipeline 31 as the heat source for heating the bottom liquid in the tube side of the reboiler 7. Further, a pipe section for introducing live steam is also connected to the first pipeline 31, and the live steam enters the mechanical vapor recompression heat pump distillation system through the first pipeline 31 as the heat source for preheating the distillation system at startup or for supplementary heating of the distillation system.

[0038] Further, in this embodiment, the second steam compressor 13 can be any one of a centrifugal steam compressor, a Roots steam compressor, or a screw steam compressor.

[0039] The mechanical vapor recompression heat pump distillation system provided by the embodiment of the present invention, by setting the evaporation subsystem, enables the gas-liquid mixture generated by heat exchange in the evaporator to become a high-temperature and high-pressure gas after gas-liquid separation and compression, and then serves as the heat source for preheating the material in the material preheating subsystem and heating the bottom liquid of the reboiler, thereby greatly improving the heat utilization rate of the distillation system and significantly saving the operating cost.

[0040] Refer to Figure 1 , in an embodiment of the present invention, the evaporation subsystem further includes: a first condensate tank 16, a first condensate pump 19, a second condensate tank 17, and a second condensate pump 18. Specifically, the first condensate tank 16 and the first condensate pump 19 are connected in series. The high-temperature and high-pressure steam formed after being compressed by the first steam compressor 12 enters the material preheating subsystem to preheat the material, condenses into water after heat exchange with the material, and enters the first condensate tank 16, and then is driven by the first condensate pump 19 to enter the material preheating subsystem again to preheat the material again.

[0041] The second condensate tank 17 and the second condensate pump 18 are connected in series. The high-temperature and high-pressure steam formed after being compressed by the second steam compressor 13 enters the shell side of the reboiler 7 to exchange heat with the bottom liquid in the tube side, condenses into water after heat exchange, enters the second condensate tank 17, and is driven by the second condensate pump 18 to enter the material preheating subsystem together with the water in the first condensate tank 16 to preheat the material.

[0042] Further, in this embodiment, the outlet of the first condensate pump 19 is connected to the first steam compressor 12 and the second steam compressor 13 through a second pipeline 32. Specifically, the second pipeline 32 is a spray water pipeline, which can spray water to cool the exhaust pipes of the first steam compressor 12 and the second steam compressor 13.

[0043] Further, in this embodiment, the first condensate pump 19 and the second condensate pump 18 can be variable-frequency pumps or industrial-frequency pumps.

[0044] Continuing to refer to Figure 1 , in an embodiment of the present invention, the material preheating subsystem includes: a primary preheater 3, a secondary preheater 4, and a tertiary preheater 5. Specifically, the material is preheated in the primary preheater 3 and then enters the secondary preheater 4 for preheating and then enters the tertiary preheater 5 for preheating. After three-stage preheating, the material enters the distillation column 6 from the tertiary preheater 5 for distillation.

[0045] Further, the steam generated during the distillation process undergoes heat exchange in the evaporator 8 and becomes a liquid. This liquid is driven by the product pump 15 and enters the primary preheater 3 to preheat the material, thereby recovering and utilizing the waste heat of the liquid.

[0046] The high-temperature and high-pressure gas formed after being compressed by the first steam compressor 12 enters the tertiary preheater 5 to preheat the material. After heat exchange, it condenses into water and enters the first condensate tank 16. The water in the first condensate tank 16 and the second condensate tank 17 are respectively driven by the first condensate pump 19 and the second condensate pump 18 and enter the secondary preheater 4 to preheat the material, thereby recovering and utilizing the waste heat of the water in the first condensate tank 16 and the second condensate tank 17.

[0047] Further, in this embodiment, the primary preheater 3 and the secondary preheater 4 can be plate heat exchangers, and the tertiary preheater 5 can be a shell-and-tube heat exchanger. It can be understood that in this embodiment, the primary preheater 3, the secondary preheater 4, and the tertiary preheater 5 are all schematic and can all be shell-and-tube heat exchangers or plate heat exchangers, or other forms of heat exchangers, not limited to the scope defined in this embodiment.

[0048] In addition, it should be noted that: the three-stage preheating is only an embodiment of the present invention. In the specific implementation process, the number of preheating stages can be set according to the energy-saving requirements and stability of the system, not limited to the content of this embodiment.

[0049] Continuing to refer to Figure 1 , in an embodiment of the present invention, the mechanical vapor recompression heat pump distillation system further includes a feeding subsystem. Specifically, the feeding subsystem includes a raw material buffer tank 1 and a feeding pump 2 connected to the raw material buffer tank 1. The material is driven by the feeding pump 2 and enters the primary preheater 3 from the raw material buffer tank 1. After three-stage preheating in sequence, it enters the distillation column 6 for distillation.

[0050] Further, in this embodiment, the feeding pump 2 can be a variable-frequency pump or an industrial-frequency pump.

[0051] Continuing to refer to Figure 1, in an embodiment of the present invention, the mechanical vapor recompression heat pump distillation system further includes a finished product subsystem. Specifically, the finished product subsystem includes a finished product tank 20 connected to the primary preheater 3. The steam generated during the distillation process is condensed into a liquid after heat exchange with water in the evaporator 8, and this liquid enters the finished product tank 20 after preheating the material in the primary preheater 3, achieving the collection of the finished product.

[0052] The finished product subsystem further includes a bottoms cooler 21 and a bottoms tank 22 connected to the bottoms cooler 21. The bottoms liquid enters the bottoms cooler 21 from the reboiler 7 for cooling, and the cooled bottoms liquid enters the bottoms tank 22, achieving the collection of the bottoms liquid. The water in the first condensate tank 16 and the second condensate tank 17 enters the secondary preheater 4 to preheat the material and then enters the bottoms cooler 21 to cool the bottoms liquid, and becomes a high-temperature liquid after heat exchange and enters the separator 9.

[0053] The finished product subsystem further includes a vacuum pump 24. Non-condensable gas discharge outlets are provided on both the shell side of the tertiary preheater 5 and the shell side of the reboiler 7, and these discharge outlets are connected to the vacuum pump 24, which is used for evacuating the distillation system and discharging non-condensable gas.

[0054] The finished product subsystem further includes a tail gas cooler 23. Circulating water is introduced into the tail gas cooler 23, and a non-condensable gas discharge outlet is also provided on the shell side of the evaporator 8. The non-condensable gas enters the tail gas cooler 23 from the non-condensable gas discharge outlet, undergoes heat exchange with the circulating water, and after condensation, enters the finished product buffer tank 11.

[0055] The mechanical vapor recompression heat pump distillation system provided by the embodiment of the present invention fully recovers and utilizes the latent heat of the top steam and the heat of the bottoms liquid, improving the thermal utilization rate of the distillation process and greatly saving the operation cost.

[0056] The following takes Figure 1 the embodiment shown as an example to detail the working principle of the mechanical vapor recompression heat pump distillation system provided by the embodiment of the present invention.

[0057] The material in the raw material buffer tank 1 is driven by the feed pump 2 and sequentially enters the primary preheater 3, the secondary preheater 4, and the tertiary preheater 5 for multi-stage preheating. After preheating, the material enters the distillation column 6 for distillation.

[0058] The steam generated during the distillation process is discharged from the steam outlet at the top of the distillation column 6 and enters the shell side of the evaporator 8. The steam undergoes heat exchange with the water in the tube side of the evaporator 8, and the steam is condensed into a liquid after heat exchange and enters the finished product buffer tank 11. Part of the liquid is driven by the finished product pump 15 to enter the primary preheater 3 to preheat the material, and then enters the finished product tank 20 for finished product collection; part of the liquid is driven by the reflux pump 14 to enter the distillation column 6. The bottoms liquid is discharged from the distillation column 6 into the tube side of the reboiler 7.

[0059] The steam generated during the rectification process enters the shell side of the evaporator 8, where it undergoes heat exchange with the water in the tube side. After heat exchange, the water becomes a gas-liquid mixture and enters the separator 9 for gas-liquid separation. The separated gas is compressed by the first steam compressor 12 into high-temperature and high-pressure steam, and part of the gas enters the three-stage preheater 5 to preheat the material, thereby realizing the recovery and utilization of the latent heat of the steam. After heat exchange with the material, the steam condenses into water and enters the first condensate tank 16. Driven by the first condensate pump 19, it enters the second-stage preheater 4 to preheat the material. Part of the gas continues to be compressed in the second steam compressor 13, and the formed high-temperature and high-pressure gas enters the shell side of the reboiler 7 as the heat source for heat exchange with the bottom liquid in the tube side. After heat exchange, part of the heated bottom liquid in the tube side enters the rectification column 6, and part is discharged to the bottom liquid cooler 21. After heat exchange, the steam condenses into water and enters the second condensate tank 17. Driven by the second condensate pump 18, it enters the second-stage preheater 4 to preheat the material, thereby recovering the waste heat of the condensed water.

[0060] After the waste heat of the condensed water is recovered in the second-stage preheater 4, it enters the bottom liquid cooler 21 to cool the bottom liquid. The cooled bottom liquid enters the bottom liquid tank 22 for collection. After heat exchange between the water and the bottom liquid in the bottom liquid cooler 21, it enters the separator 9.

[0061] The rectification system shown in this embodiment further includes a first pipeline 31 and a second pipeline 32. A pipe section for introducing live steam is connected to the first pipeline 31, which can be used as the heat source for start-up preheating of the rectification system or for supplementary heating of the rectification system. The second pipeline 32 is a water spray pipeline, which can spray water for cooling the exhaust pipes of the first steam compressor 12 and the second steam compressor 13.

[0062] In this embodiment, non-condensable gas discharge outlets are provided on the shell sides of the reboiler 7 and the three-stage preheater 5. The discharge outlets are connected to the vacuum pump 24 for evacuating the rectification system and discharging non-condensable gases. A non-condensable gas discharge outlet is also provided on the shell side of the evaporator 8. The non-condensable gas undergoes heat exchange with the circulating water in the tail gas cooler 23 and then condenses and flows into the finished product buffer tank 11.

[0063] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements for some of the technical features. However, these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A mechanical vapor recompression heat pump distillation system, characterized in that, Comprising: A material preheating subsystem, a rectification subsystem, and an evaporation subsystem, wherein the outlet of the material preheating subsystem is connected to the inlet of the rectification subsystem; the outlet of the rectification subsystem is connected to the inlet of the evaporation subsystem to discharge the steam generated during the rectification process into the evaporation subsystem for heat exchange, and then condense the steam into a liquid and discharge it into the finished product tank; the outlet of the evaporation subsystem is connected to the inlet of the material preheating subsystem to use the secondary steam generated during the evaporation process after compression as the heat source for preheating the material in the material preheating subsystem; the rectification subsystem includes: a rectification column and a reboiler; the evaporation subsystem includes: an evaporator, a finished product buffer tank, and a finished product pump; the rectification subsystem further includes a reflux pump; the evaporation subsystem further includes: a separator, a first steam compressor, and a forced circulation pump, wherein the inlet of the separator is connected to the second outlet of the evaporator, the first outlet of the separator is connected to the inlet of the first steam compressor, and the outlet of the first steam compressor is connected to the inlet of the material preheating subsystem; the second outlet of the separator is connected to the inlet of the forced circulation pump, and the outlet of the forced circulation pump is connected to the second inlet of the evaporator; the evaporation subsystem further includes a second steam compressor, the inlet of the second steam compressor is connected to the outlet of the first steam compressor, and the outlet of the second steam compressor is connected to the second inlet of the reboiler through a first pipeline, wherein a pipe section for introducing live steam is also connected to the first pipeline; the evaporation subsystem further includes a first condensate tank and a first condensate pump connected in series with the first condensate tank, and a second condensate tank and a second condensate pump connected in series with the second condensate tank, wherein the inlet of the first condensate tank is connected to the outlet of the material preheating subsystem, and the inlet of the second condensate tank is connected to the second outlet of the reboiler; the outlets of the first condensate pump and the second condensate pump are respectively connected to the inlet of the material preheating subsystem; and the outlet of the first condensate pump is respectively connected to the first steam compressor and the second steam compressor through a second pipeline; the material preheating subsystem includes: a primary preheater, a secondary preheater, and a tertiary preheater connected in series in sequence, wherein the first inlet of the primary preheater is connected to the outlet of the finished product pump; the first inlet of the secondary preheater is connected to the outlets of the first condensate pump and the second condensate pump; the first inlet of the tertiary preheater is connected to the outlet of the first steam compressor, the first outlet of the tertiary preheater is connected to the first inlet of the rectification column, and the second outlet of the tertiary preheater is connected to the first condensate tank.

2. The mechanical vapor recompression heat pump distillation system according to claim 1, wherein The first outlet of the rectification column is connected to the inlet of the evaporation subsystem, the second outlet of the rectification column is connected to the first inlet of the reboiler, and the first inlet of the rectification column is connected to the outlet of the material preheating subsystem; the first outlet of the reboiler is connected to the second inlet of the rectification column.

3. The mechanical vapor recompression heat pump distillation system according to claim 2, wherein The first inlet of the evaporator is connected to the first outlet of the rectification column. The first outlet of the evaporator is connected to the inlet of the finished product pump through the finished product buffer tank. The outlet of the finished product pump is connected to the inlet of the material preheating subsystem.

4. The mechanical vapor recompression heat pump distillation system according to claim 3, characterized in that, The inlet of the reflux pump is connected to the outlet of the finished product buffer tank. The outlet of the reflux pump is connected to the third inlet of the rectification column.

5. The mechanical vapor recompression heat pump distillation system according to claim 1, characterized in that, It further includes a feeding subsystem, which includes a raw material buffer tank and a feeding pump arranged in series in sequence. Among them, the outlet of the feeding pump is connected to the second inlet of the primary preheater.

6. The mechanical vapor recompression heat pump distillation system according to claim 1, wherein It further includes: A finished product subsystem, which includes: the finished product tank, a vacuum pump, a tail gas cooler, and a bottom liquid cooler and a bottom liquid tank arranged in series in sequence. Among them, the inlet of the finished product tank is connected to the first outlet of the primary preheater. The first inlet of the bottom liquid cooler is connected to the first outlet of the secondary preheater. The second inlet of the bottom liquid cooler is connected to the third outlet of the reboiler. The first outlet of the bottom liquid cooler is connected to the second inlet of the separator. The inlet of the vacuum pump is connected to the third outlet of the tertiary preheater and is connected to the fourth outlet of the reboiler. The inlet of the tail gas cooler is connected to the third outlet of the evaporator. The outlet of the tail gas cooler is connected to the inlet of the finished product buffer tank.

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