A heat pump rectification system based on heat shock flash circulation lifting heat exchange

Abstract

The present application relates to a kind of heat pump rectification systems based on heat shock flash circulation lift heat exchange, including rectifying tower, lift membrane reboiler, first throttling valve and heat shock heater, the secondary steam outlet of rectifying tower is connected with the heating steam import of lift membrane reboiler, the discharge port of the bottom of rectifying tower is connected with the cold side flow channel import of heat shock heater, and the cold side flow channel export of heat shock heater is connected with the feed inlet of lift membrane reboiler by first throttling valve;The vapor-liquid mixture outlet of lift membrane reboiler is connected with the column still liquid reflux port of rectifying tower, and the steam condensate outlet of lift membrane reboiler is connected with condensate tank, and the liquid outlet of condensate tank is connected with the condensate reflux port of rectifying tower side wall.The present application is combined by heat shock pressurization energy storage and throttling flash kinetic energy release, provides independent and stable lift membrane kinetic energy for lift membrane heat exchange, so that the flow pattern in the tube of lift membrane reboiler directly enters the efficient annular flow stage, improves the industrial applicability of lift membrane heat exchange technology in heat pump rectification system.

Description

Technical Field

[0001] This invention relates to the field of heat pump distillation technology, specifically to a heat pump distillation system based on thermal flash evaporation circulating rising film heat exchange. Background Technology

[0002] Heat pump distillation technology, with its energy-saving characteristics, has become a mainstream energy-saving technology in the chemical and petrochemical industries. Heat pump distillation uses a compressor to compress and heat the secondary vapor at the top of the distillation column, then reuses this high-temperature vapor as a heat source for the reboiler, thus achieving the recovery and reuse of heat energy in the distillation system and significantly reducing energy consumption in the distillation process. The main working medium in a heat pump distillation system is an organic solution. The distillation column in the system recovers the latent heat of the vapor generated by the evaporation of the lower-boiling-point solution at the top of the column. After compression and heating, this vapor enters the shell side of the reboiler as a heat source. The bottom liquid enters the tube side and exchanges heat with the vapor in the shell side. The condensate (i.e., the target purified solution with a lower boiling point) generated after the shell-side vapor cools down through heat exchange can be collected through the condensate outlet in the shell. Simultaneously, the bottom liquid in the tube side is preheated and then returned to the distillation column for further distillation. In other words, by using a reboiler in the system, the differences in boiling points of the components can be utilized to continuously purify and separate the solution through distillation, while the latent heat of the vapor at the top of the distillation column can be recovered and reused, thus significantly improving energy efficiency. Rising film reboilers have advantages such as high heat transfer efficiency, short material residence time, and compact structure, making them a typical choice for reboilers in heat pump distillation columns. In existing technologies, the flow pattern inside the heat exchange tubes of rising film reboilers needs to go through five evolution stages in sequence: single-phase two-liquid flow, bubbly flow, slug flow, annular flow, and mist flow, with the annular flow stage exhibiting the best heat transfer effect. The formation of annular flow is highly dependent on a large heat transfer temperature difference of over 20°C in the heat exchanger. Rapid vaporization of the inlet material is achieved through a large temperature difference and high heat flux density input, generating sufficient vapor phase kinetic energy to drive the annular rising film operation.

[0003] However, the reboiler in a heat pump distillation system is heated by compressed overhead vapor. Limited by factors such as the temperature difference between the top and bottom of the column and the compressor's limiting pressure ratio, the heat transfer temperature difference in the reboiler is generally no higher than 10°C, representing a typical narrow temperature difference heat exchange condition. Under this narrow temperature difference condition, if a heat pump system is used to heat the rising film reboiler, the low heat flux density of the reboiler leads to insufficient vaporization of the liquid in the heat exchange tubes. The vapor velocity cannot reach the critical velocity required for rising film heat exchange, and the flow pattern in the heat exchange tubes remains stagnant in inefficient heat exchange stages such as bubbly or slug flow. This prevents the achievement of a highly efficient circulating rising film heat exchange state, resulting in poor overall heat exchange performance of the reboiler and thus reducing the purification and heat recovery effects.

[0004] To compensate for insufficient rising film kinetic energy, existing technologies often employ the addition of a forced circulation pump to increase the apparent flow rate of the vapor-liquid mixture in the heat exchange tube by increasing the feed rate. However, this approach leads to a significant increase in the proportion of liquid phase in the heat exchange tube, and the flow pattern degenerates into a less efficient bubbly flow pattern, failing to achieve true rising film heat exchange. Consequently, the distillation efficiency and energy-saving effect of the heat pump distillation system are greatly reduced. Summary of the Invention

[0005] The present invention aims to provide a heat pump distillation system based on thermal flash evaporation circulating rising film heat exchange to overcome the shortcomings of the prior art. The technical problem to be solved by the present invention is achieved through the following technical solution.

[0006] A heat pump distillation system based on thermal quench flash evaporation circulating rising film heat exchange includes a distillation column, a rising film reboiler, a first throttling valve, and a thermal quench heater. The secondary steam outlet at the top of the distillation column is connected to the heating steam inlet of the rising film reboiler, allowing the pressurized secondary steam generated at the top of the distillation column to be introduced into the rising film reboiler as a heat source. The discharge port at the bottom of the distillation column is connected to the cold-side inlet of the thermal quench heater, allowing the pressurized feed solution from the distillation column to be introduced into the thermal quench heater. The cold-side outlet of the thermal quench heater is connected to the feed inlet of the rising film reboiler via the first throttling valve, allowing the feed solution entering the thermal quench heater to be heated by high-temperature live steam to form a high-temperature, high-pressure feed solution. The liquid is then throttled and depressurized by the first throttling valve, causing the liquid to undergo isenthalpic flash evaporation to form a high-speed vapor-liquid mixture, which enters the heat exchange tube of the rising film reboiler. Driven by the kinetic energy of vapor expansion, the liquid rises along the inner wall of the heat exchange tube to form a stable liquid film. The vapor-liquid mixture outlet on the upper end wall of the rising film reboiler is connected to the bottom liquid reflux port of the distillation column, so that the vapor-liquid mixture at the upper end of the rising film reboiler flows back into the distillation column. The vapor condensate outlet on the lower side wall of the rising film reboiler shell is connected to the condensate tank, and the outlet of the condensate tank is connected to the condensate reflux port on the side wall of the distillation column, so that the vapor condensate in the rising film reboiler flows into the condensate tank. Part of the condensate in the condensate tank is collected as needed, and the other part is cooled and returned to the distillation column.

[0007] Preferably, the lower end cap of the rising film reboiler is provided with a vapor-liquid distributor.

[0008] Preferably, a cooler is provided between the outlet of the condensate tank and the condensate reflux port of the distillation column.

[0009] Preferably, a second throttling valve is provided between the liquid outlet of the condensate tank and the condensate reflux port of the distillation column.

[0010] Preferably, the outlet of the condensate tank is connected to the inlet of the reflux pump, and the outlet of the reflux pump is connected to the condensate reflux port of the distillation column.

[0011] Preferably, a compressor is provided between the secondary steam outlet of the distillation column and the heating steam inlet of the rising film reboiler, the compressor being used to pressurize and heat the secondary steam flowing out from the top of the distillation column.

[0012] Preferably, the compressor is one of a centrifugal compressor, a twin-screw compressor, or a Roots compressor.

[0013] Preferably, a circulation pump is installed at the outlet of the distillation column.

[0014] Preferably, the system also includes a measurement and control system, which is used to monitor the temperature, pressure, and flow parameters within the system in real time, and to adjust the outlet temperature of the thermal shock heater and the outlet pressure of the first throttle valve in real time.

[0015] Preferably, the measurement and control system includes a temperature sensor and a pressure sensor disposed between the thermal shock heater and the first throttling valve, and also includes a pressure sensor disposed between the first throttling valve and the rising film reboiler.

[0016] In this invention, the feed liquid to be processed enters the distillation column through the feed inlet to complete the initial distillation separation. The low-temperature, low-pressure secondary steam generated at the top of the distillation column enters the compressor, is compressed and heated to form high-temperature, high-pressure secondary steam, and is then fed into the shell side of the rising film reboiler as its heating source. The feed liquid in the bottom of the distillation column is pressurized by the circulating pump and then fed into the cold side channel of the thermal shock heater, where it is heated by the high-temperature live steam on the hot side, thus completing the storage of high-temperature heat energy from the heating source into the internal energy of the liquid in the bottom of the column. The high-temperature, high-pressure liquid in the bottom of the column is throttled and depressurized through the first throttling valve, resulting in isenthalpic throttling flash evaporation. The internal energy stored in the liquid in the bottom of the column is converted into the expansion kinetic energy of the vapor and liquid phases after throttling, forming a high-energy, high-speed vapor-liquid mixture. The high-speed vapor-liquid mixture enters the lower head of the rising film reboiler, where it is evenly distributed to each heat exchange tube by an internal vapor-liquid distributor. Utilizing the kinetic energy of vapor expansion generated by throttling flash evaporation, the liquid is driven to climb along the tube wall and form an ultra-thin liquid film, directly entering the high-efficiency annular flow stage. The vapor-liquid mixture in the upper head of the rising film reboiler returns to the distillation column. The condensate from the shell side of the rising film reboiler flows into a condensate tank. A portion of the condensate in the tank is collected as needed by a reflux pump, while the remaining portion is cooled by a cooler and returned to the distillation column. When the bottom liquid concentration exceeds a set value, the bottom liquid is collected from the outlet of the circulation pump.

[0017] The heat pump distillation system based on thermal flash evaporation circulating rising film heat exchange provided by this invention has the following beneficial effects: This invention utilizes a thermal shock heater to achieve a rapid thermal pressure increase and energy storage of the material. Combined with the throttling flash effect of a throttling valve, it releases sufficient kinetic energy, providing an independent and stable power source for the rising film reboiler's heat exchange. This allows the vapor-liquid mixture within the reboiler's heat exchange tubes to skip the inefficient bubbly and slug-like flow stages and directly enter the efficient annular flow stage. This solves the technical problem of insufficient kinetic energy for rising film heat exchange and prolonged flow pattern stagnation in inefficient stages in conventional technologies under narrow temperature difference conditions below 10°C. Consequently, the flow at the top of the distillation column... The temperature of the steam after compression by the compressor is only within 10°C higher than the evaporation temperature of the rising film reboiler, which can achieve efficient heat exchange in the rising film reboiler. This realizes efficient rising film heat exchange in the heat pump distillation system under narrow temperature difference conditions, thereby realizing the reuse of the latent heat of the steam at the top of the distillation column, and enabling the collection or reflux of the solution to be purified. This allows the distillation column to achieve better purification effect through repeated distillation with low energy consumption, significantly reducing the demand of the distillation system for high-temperature heat sources and improving the operating economy of the distillation system. Attached Figure Description

[0018] Figure 1 This is a structural block diagram of one embodiment of the present invention; Figure 2 This is a schematic diagram of the rising film reboiler in this invention; Figure 3 This is a schematic diagram of one embodiment of the vapor-liquid distributor in this invention; Figure 4 This is a schematic diagram of the flow pattern inside the heat exchange tube of a rising film reboiler in one embodiment of the present invention; Figure 5 This is a structural block diagram of another embodiment of the present invention.

[0019] The reference numerals in the attached figures are as follows: 1. Distillation column, 2. Compressor, 3. Cooler, 4. Reflux pump, 5. Condensate tank, 6. Rising film reboiler, 7. First throttling valve, 8. Measurement and control system, 9. Thermal shock heater, 10. Circulation pump, 11. Second throttling valve, 61. Vapor-liquid distributor. Detailed Implementation

[0020] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0021] Example 1: Reference Figure 1As shown, a heat pump distillation system based on thermal quench flash evaporation circulating rising film heat exchange is improved in that it includes a distillation column 1, a rising film reboiler 6, a first throttling valve 7, and a thermal quench heater 9. The secondary steam outlet at the top of the distillation column 1 is connected to the heating steam inlet of the rising film reboiler 6, so that the secondary steam generated at the top of the distillation column 1 is pressurized and introduced into the rising film reboiler 6 as a heat source for the rising film reboiler 6. The discharge port at the bottom of the distillation column 1 is connected to the cold side inlet of the thermal quench heater 9, so that the feed liquid with the required concentration from the distillation column 1 is pressurized and introduced into the thermal quench heater 9. The cold side outlet of the thermal quench heater 9 is connected to the feed port of the rising film reboiler 6 through the first throttling valve 7, so that the feed liquid introduced into the thermal quench heater 9 is heated by high-temperature live steam to form a film reboiler 6. The high-temperature, high-pressure feed liquid is then throttled and depressurized by the first throttling valve 7, causing the feed liquid to undergo isenthalpic flash evaporation to form a high-speed vapor-liquid mixture. This mixture enters the heat exchange tubes of the rising film reboiler 6. Driven by the kinetic energy of vapor phase expansion, the feed liquid climbs along the inner wall of the heat exchange tubes to form a stable liquid film. The vapor-liquid mixture outlet on the upper end wall of the rising film reboiler 6 is connected to the bottom liquid reflux port of the distillation column 1, so that the vapor-liquid mixture at the upper end of the rising film reboiler 6 flows back into the distillation column 1. The vapor condensate outlet on the lower side wall of the rising film reboiler 6 is connected to the condensate tank 5, and the outlet of the condensate tank 5 is connected to the condensate reflux port on the side wall of the distillation column 1, so that the vapor condensate in the rising film reboiler 6 flows into the condensate tank 5. Part of the condensate in the condensate tank 5 is collected as needed, and the other part is cooled and returned to the distillation column 1.

[0022] In this embodiment, the distillation column 1 is a plate column or a packed column. The secondary steam outlet is located at the top of the distillation column 1, and the feed outlet is located at the bottom of the distillation column 1. The side wall of the distillation column 1 is provided with a condensate reflux port, a feed port, and a bottom liquid reflux port from top to bottom.

[0023] The rising film reboiler 6 is a vertical shell-and-tube heat exchanger with a length-to-diameter ratio of 100 to 250 for the heat exchange tubes. The shell side of the rising film reboiler 6 is a hot medium flow channel, and the upper side wall of the shell is provided with a heating steam inlet, while the lower side wall is provided with a steam condensate outlet. The tube side of the heat exchange tubes of the rising film reboiler 6 is a cold medium flow channel, with a feed inlet on the lower end cap and a vapor-liquid mixture outlet on the side wall of the upper end cap.

[0024] Furthermore, a vapor-liquid distributor 61 is provided inside the lower end cap of the rising film reboiler 6.

[0025] In this embodiment, the vapor-liquid distributor 61 is used to achieve uniform distribution of the high-speed vapor-liquid mixture after throttling and flashing in each heat exchange tube, so as to avoid uneven distribution of vapor-liquid ratio in each heat exchange tube.

[0026] Furthermore, the vapor-liquid distributor 61 is a conical perforated plate, a cyclone separator, or a windowed structured packing.

[0027] The function of the heat shock heater 9 is to heat the bottom liquid of the tower at high temperature and store the complete high-temperature heat energy into the internal energy of the bottom liquid. The heat shock heater 9 is a wall-type heat exchanger, with the bottom liquid in the cold side and the high-temperature live steam in the hot side.

[0028] Furthermore, the heat-induced heater 9 is a fully welded plate heat exchanger, a shell-and-tube heat exchanger, or a spiral plate heat exchanger.

[0029] The function of the first throttling valve 7 is to throttle and reduce the pressure of the liquid in the bottom of the tower after thermal shock heating, thereby achieving isenthalpic throttling flash evaporation of the liquid. Through throttling flash evaporation, the internal energy accumulated by the thermal shock heating of the liquid is converted into the expansion kinetic energy of the vapor and liquid phases after flash evaporation.

[0030] Furthermore, the first throttle valve 7 is an electronic expansion valve or a thermostatic expansion valve.

[0031] Furthermore, the outlet of the condensate tank 5 is connected to the inlet of the reflux pump 4, and the outlet of the reflux pump 4 is connected to the condensate reflux port of the distillation column 1. One outlet of the reflux pump 4 collects liquid, and the other outlet is connected to the condensate reflux port of the distillation column 1.

[0032] Furthermore, the reflux pump 4 is an explosion-proof magnetic pump or a shielded pump.

[0033] Furthermore, a compressor 2 is provided between the secondary steam outlet of the distillation column 1 and the heating steam inlet of the rising film reboiler 6. The compressor 2 is used to pressurize and heat the secondary steam flowing out from the top of the distillation column 1.

[0034] Furthermore, the compressor 2 is one of a centrifugal compressor, a twin-screw compressor, or a Roots compressor.

[0035] Furthermore, the compressor 2 can be configured as a single-stage or multi-stage compressor.

[0036] Furthermore, the motor of the compressor 2 is an explosion-proof motor.

[0037] Furthermore, a circulation pump 10 is installed at the outlet of the distillation column 1. One outlet of the circulation pump 10 is used to collect water, and the other outlet is connected to the inlet of the cold side flow channel of the thermal quench heater 9.

[0038] Furthermore, the circulating pump is a 10-position explosion-proof magnetic pump or a shielded pump.

[0039] Furthermore, it also includes a measurement and control system 8, which is used to monitor the temperature, pressure, and flow parameters within the system in real time, and to adjust the outlet temperature of the thermal shock heater 9, the outlet pressure of the first throttle valve 7, and the pressure ratio parameter of the compressor 2 in real time.

[0040] Furthermore, the measurement and control system 8 includes a temperature sensor and a pressure sensor disposed between the thermal heater 9 and the first throttle valve 7, and also includes a pressure sensor disposed between the first throttle valve 7 and the rising film reboiler 6.

[0041] In this embodiment, the operation process of the heat pump distillation system is as follows: The feed liquid to be processed enters the distillation column 1 through the feed inlet to complete the initial distillation separation. The low-temperature, low-pressure secondary steam generated by the evaporation of the solution with a lower boiling point at the top of the distillation column 1 enters the compressor 2, is compressed and heated to form high-temperature, high-pressure secondary steam, and is then fed into the shell side of the rising film reboiler 6 as its heating source. The material in the bottom of the distillation column 1 is a solution with a higher boiling point that has not been distilled and evaporated. When the concentration does not meet the collection standard, it is pressurized by the circulating pump 10 and fed into the cold side flow channel of the thermal shock heater 9, where it is heated by the high-temperature live steam on the other side, thus completing the storage of high-temperature heat energy from the heating source into the internal energy of the liquid in the bottom of the column. The high-temperature, high-pressure liquid in the bottom of the column is throttled and depressurized through the first throttling valve 7, resulting in isenthalpic throttling flash evaporation. The internal energy stored in the liquid in the bottom of the column is converted into the expansion kinetic energy of the vapor and liquid phases after throttling, forming a high-energy, high-speed vapor-liquid mixture. The high-speed vapor-liquid mixture enters the lower head of the rising film reboiler 6 and is evenly distributed to each heat exchange tube of the reboiler 6 by the internal vapor-liquid distributor 61. Utilizing the kinetic energy of vapor expansion generated by throttling flash evaporation, the liquid is driven to climb along the heat exchange tube wall and form an ultra-thin liquid film, directly entering the high-efficiency annular flow stage. The vapor-liquid mixture in the upper head of the reboiler 6 returns to the distillation column 1 for further distillation. The condensate from the shell side of the reboiler 6 flows into the condensate tank 5. A portion of the condensate in the condensate tank 5 is collected as needed by the reflux pump 4, while the remaining portion is cooled and returned to the distillation column 1. When the bottom liquid concentration reaches the collection standard, the bottom liquid is collected by the outlet of the circulation pump 10.

[0042] Example 2: Based on Example 1, this example uses methanol distillation as an example to illustrate the thermal flash evaporation circulating rising film heat pump distillation system.

[0043] The relevant system parameters are as follows: the feed methanol content is 15%, the water content is 85%, the feed rate is 9.3 t / h, the methanol concentration at the top of the column is required to be greater than 99.9%, and the methanol concentration at the bottom of the column is required to be less than 0.2%; the distillation column 1 adopts atmospheric pressure distillation operation.

[0044] Reference Figure 1As shown, this embodiment provides a heat pump distillation system based on thermally stimulated flash evaporation and circulating rising film heat exchange, including a distillation column 1, a compressor 2, a cooler 3, a reflux pump 4, a condensate tank 5, a rising film reboiler 6, a first throttling valve 7, a measurement and control system 8, a thermally stimulated heater 9, a circulating pump 10, and a vapor-liquid distributor 61. The cooler 3 is located between the liquid outlet of the condensate tank 5 and the condensate reflux port of the distillation column 1.

[0045] Distillation column 1 is a packed distillation column with a secondary steam outlet at the top and a feed outlet at the bottom. The side wall of the distillation column has a condensate reflux port, a feed port, and a bottom liquid reflux port from top to bottom. The function of compressor 2 is to pressurize and heat the secondary steam at the top of the distillation column. The compressor is a twin-screw compressor. The compressor has an intake temperature of 65℃, an intake pressure of 101kPa(a), an exhaust pressure of 550kPa, a corresponding exhaust saturation temperature of 115℃, and a compressor pressure ratio of 5.4.

[0046] Reference Figure 2 As shown, the rising film reboiler 6 is a vertical shell-and-tube heat exchanger with heat exchange tubes of 25mm diameter, 1mm wall thickness, 3000mm length, a length-to-diameter ratio of 120, and made of 304 stainless steel. The heat exchanger area is 200m². 2 The shell diameter is 1000mm; the shell side of the rising film reboiler 6 is a hot medium flow channel, the upper side wall of the shell of the rising film reboiler 6 is provided with a heating steam inlet, and the lower side wall of the shell is provided with a steam condensate outlet; the tube side of the rising film reboiler 6 is a cold medium flow channel, the lower end cap is provided with a feed inlet, and the upper end cap side wall is provided with a vapor-liquid mixture outlet.

[0047] Reference Figure 3 As shown, the vapor-liquid distributor 61 adopts a lower conical perforated plate structure with a taper angle of 150°, an orifice diameter of 10mm, and an orifice spacing of 15mm. The function of the vapor-liquid distributor 61 is to evenly distribute the throttled vapor-liquid mixture in the bottom of the gas-liquid mixing tower into each heat exchange tube of the rising film reboiler 6, so as to avoid uneven vapor-liquid distribution in the heat exchange tubes. The vapor-liquid distributor 61 is fixed inside the lower head of the rising film reboiler 6. The function of the heat shock heater 9 is to heat the bottom liquid of the tower at high temperature, thereby storing the high-temperature heat energy into the internal energy of the bottom liquid. In this embodiment, the heat shock heater 9 is a fully welded heater. The bottom liquid in the heat shock heater 9 is heated by 150°C live steam. After heating, the temperature of the bottom liquid is 120°C, and the corresponding saturation pressure of the bottom liquid is 198 kPa(a). The function of the circulating pump 10 is to pressurize and circulate the liquid in the bottom of distillation column 1. In this embodiment, the circulating pump 10 is an explosion-proof shielded pump with a circulation flow rate of 35 m³ / h. 3 / h, with a head of 32m; the function of the first throttling valve 7 is to throttle and reduce the pressure of the bottom liquid after thermal shock heating. After throttling, the high-temperature bottom liquid undergoes isenthalpic flash evaporation, converting the internal energy accumulated by the thermal shock heating of the liquid into the expansion kinetic energy of the vapor and liquid phases after flash evaporation. The first throttling valve 7 is an electronic expansion valve with an inlet pressure of about 250 kPa (a) and an outlet pressure of 115 kPa (a), resulting in a pressure drop of about 135 kPa. The connection methods of each component in this embodiment are as follows: The secondary steam outlet at the top of distillation column 1 is connected to the inlet of compressor 2. The compressor outlet is connected to the heating steam inlet of the shell of rising film reboiler 6. The steam condensate outlet on the side wall of the shell is connected to the liquid inlet of condensate tank 5. The outlet of condensate tank 5 is connected to the inlet of reflux pump 4. One outlet of reflux pump 4 is discharged, and the other is connected to the condensate reflux port on the side wall of distillation column 1. A cooler 3 is installed on this pipeline. The discharge port at the bottom of distillation column 1 is connected to the inlet of circulation pump 10. One outlet of circulation pump 10 is discharged, and the other is connected to the inlet of the cold side channel of thermal quench heater 9. The cold side channel outlet of thermal quench heater 9 is connected to the feed port at the bottom of rising film reboiler 6. A first throttling valve 7 is installed on this connecting pipeline. The vapor-liquid mixture outlet on the side wall of the upper head of rising film reboiler 6 is connected to the bottom liquid reflux port on the side wall of distillation column 1. Vapor-liquid distributor 61 is fixed inside the lower head of rising film reboiler 6. The measurement and control system 8 includes temperature sensors, pressure sensors, flow sensors, and a PLC programmable controller. Each sensor is installed at key locations such as the top of the distillation column 1, the bottom of the column, the rising film reboiler 6, the heat shock heater 9, and the inlet and outlet of the compressor 2. It is used to detect parameters such as temperature, pressure, and flow rate in the system in real time; and to adjust parameters such as the outlet temperature of the heat shock heater 9, the pressure after the first throttle valve 7, and the pressure ratio of the compressor 2 in real time.

[0048] The working process of this embodiment is as follows: The methanol-water solution to be treated enters the distillation column 1 through the feed inlet for preliminary distillation separation. The 65°C atmospheric pressure vapor at the top of distillation column 1, which has a high methanol content, enters compressor 2 for compression. The discharge pressure of compressor 2 is 550 kPa, and the corresponding discharge saturation temperature is 115°C. The compressed vapor at approximately 115°C is passed into the shell side of the rising film reboiler 6 as its heating source. The feed liquid in the bottom of distillation column 1 is a solution with a low methanol content after distillation. After being pressurized by circulating pump 10, it is passed into the thermal blast heater 9 and... The 150°C high-temperature live steam on the hot side is heated to about 120°C, completing the storage of high-temperature heat energy from the heat source into the internal energy of the liquid in the bottom of the tower. Then, the pressure is reduced to 115 kPa through the first throttling valve 7. During the isenthalpic throttling flash evaporation process of the feed liquid, the internal energy stored in the liquid in the bottom of the tower is converted into the expansion kinetic energy of the vapor and liquid phases after throttling. The temperature of the vapor-liquid mixture after throttling is 105°C and the vaporization rate is about 3.4%. The volume of the vapor-liquid mixture after throttling is about 47.2 times that of the pure liquid phase before throttling, thus forming a high-kinetic-energy vapor-liquid mixture.

[0049] Reference Figure 4 As shown, the high-speed vapor-liquid mixture enters the lower head of the rising film reboiler 6 and is evenly distributed to each heat exchange tube of the rising film reboiler 6 by the internal vapor-liquid distributor 61. Driven by the kinetic energy of flash expansion, the liquid climbs along the heat exchange tube wall, forming a uniform and stable ultra-thin liquid film. This directly skips the inefficient flow pattern and enters the efficient annular flow stage. The evaporation temperature of the liquid in the bottom of the column within the heat exchange tube is approximately 105℃, and the heat transfer temperature difference in the rising film reboiler 6 is 10℃. The vapor-liquid mixture in the upper head of the rising film reboiler 6 returns to the distillation column 1 for further distillation. Separation has achieved the purification effect; the condensate from the 115℃ steam in the shell side of the rising film reboiler 6 flows into the condensate tank 5, and the methanol content in the condensate is detected by the monitoring and control system 8. When the methanol purity is greater than 99.9%, a portion of the methanol condensate is collected by the reflux pump 4, with a collection rate of about 1370 kg / h. The remaining portion is cooled to 65℃ by the cooler 3 and then refluxed into the distillation column, with a reflux ratio of about 2.3. When the methanol concentration in the bottom liquid of the column is detected to be less than 0.2%, the bottom liquid is collected by the circulation pump 10.

[0050] This embodiment uses the thermal shock heater 9 to achieve a thermal surge and pressure storage of the material. Combined with the throttling flash evaporation effect of the first throttling valve 7, it releases sufficient kinetic energy, providing an independent and stable power source for rising film heat exchange. This allows the vapor-liquid mixture in the heat exchange tube of the rising film reboiler 6 to skip the inefficient bubbly and slug flow stages and directly enter the efficient annular flow stage. This completely solves the industry-wide technical problem that conventional technologies cannot use rising film heat exchange technology in reboilers under narrow temperature difference conditions of 4~10℃. Thus, the latent heat in the methanol vapor at the top of the column is recovered and utilized, and purification can be achieved through repeated distillation. This ensures the low-energy consumption and high-efficiency operation of the heat pump distillation system under narrow temperature difference conditions.

[0051] Example 3: Based on Example 1, referring to Figure 5 As shown, a heat pump distillation system based on thermally stimulated flash evaporation and circulating rising film heat exchange includes a distillation column 1, a compressor 2, a reflux pump 4, a condensate tank 5, a rising film reboiler 6, a first throttling valve 7, a measurement and control system 8, a thermally stimulated heater 9, a circulating pump 10, a vapor-liquid distributor 61, and a second throttling valve 11; the second throttling valve 11 is located between the liquid outlet of the condensate tank 5 and the condensate reflux port of the distillation column 1.

[0052] The equipment structure and system connection method of this embodiment are the same as those of embodiment 2. The difference is that the high-temperature reflux liquid in this embodiment returns to the distillation column 1 after passing through the second throttling valve 11. The pressure after throttling is 101 kPa, and the temperature of the gas-liquid mixture after throttling is about 65°C.

[0053] Compared with Example 2, this example recovers the sensible heat of the high-temperature condensate through isenthalpic throttling flash evaporation, avoiding heat loss during the cooling of the high-temperature condensate and improving the overall energy utilization efficiency of the heat pump distillation system.

[0054] It should be noted that the above detailed descriptions are exemplary and intended to provide further explanation of this application. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains.

[0055] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments described in this application. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0056] It should be noted that the terms "first," "second," etc., used in the specification, claims, and accompanying drawings of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such terms can be used interchangeably where appropriate so that the embodiments of this application described herein can be implemented in sequences other than those illustrated or described herein.

[0057] Furthermore, the terms “comprising” and “having”, and any variations thereof, are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or apparatus that includes a series of steps or units is not necessarily limited to those steps or units that are explicitly listed, but may include other steps or units that are not explicitly listed or that are inherent to such process, method, product, or apparatus.

[0058] For ease of description, spatial relative terms such as "above," "on top of," "on the upper surface of," "above," etc., are used herein to describe the spatial positional relationship of a device or feature as shown in the figures to other devices or features. It should be understood that spatial relative terms are intended to encompass different orientations in use or operation beyond the orientation of the device as described in the figures. For example, if the device in the figures were inverted, a device described as "above" or "on top of" other devices or structures would subsequently be positioned as "below" or "under" other devices or structures. Thus, the exemplary term "above" can include both "above" and "below." The device may also be positioned in other different ways, such as rotated 90 degrees or in other orientations, and the spatial relative descriptions used herein will be interpreted accordingly.

[0059] In the detailed description above, reference has been made to the accompanying drawings, which form part of this document. In the drawings, similar symbols typically identify similar parts unless the context otherwise indicates otherwise. The illustrated embodiments described in the detailed specification, drawings, and claims are not intended to be limiting. Other embodiments may be used and other changes may be made without departing from the spirit or scope of the subject matter presented herein.

[0060] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A heat pump distillation system based on thermal flash evaporation circulating rising film heat exchange, characterized in that: The system includes a distillation column (1), a rising film reboiler (6), a first throttle valve (7), and a heat blast heater (9). The secondary steam outlet at the top of the distillation column (1) is connected to the heating steam inlet of the rising film reboiler (6) to allow the secondary steam generated at the top of the distillation column (1) to be pressurized and then fed into the rising film reboiler (6) as a heat source for the rising film reboiler (6). The discharge port at the bottom of the distillation column (1) is connected to the cold side inlet of the heat blast heater (9) to allow the feed liquid from the distillation column (1) with the required concentration to be pressurized and then fed into the heat blast heater (9). The cold side outlet of the heat blast heater (9) is connected to the feed port of the rising film reboiler (6) through the first throttle valve (7) to allow the feed liquid fed into the heat blast heater (9) to be heated by high-temperature live steam to form a high-temperature and high-pressure feed liquid, which is then fed into the heat blast heater (9). The first throttling valve (7) reduces pressure, causing the liquid to undergo isenthalpic flash evaporation to form a high-speed vapor-liquid mixture, which enters the heat exchange tube of the rising film reboiler (6). Driven by the kinetic energy of vapor expansion, the liquid rises along the inner wall of the heat exchange tube to form a stable liquid film. The vapor-liquid mixture outlet on the side wall of the upper end cap of the rising film reboiler (6) is connected to the bottom liquid reflux port of the distillation column (1) so that the vapor-liquid mixture at the upper end of the rising film reboiler (6) is returned to the bottom liquid reflux port. Inside the distillation column (1); the steam condensate outlet of the lower side wall of the rising film reboiler (6) is connected to the condensate tank (5), and the liquid outlet of the condensate tank (5) is connected to the condensate return port on the side wall of the distillation column (1), so that the steam condensate in the rising film reboiler (6) flows into the condensate tank (5), and part of the condensate in the condensate tank (5) is collected as needed, and the other part is returned to the distillation column (1) after cooling.

2. The heat pump distillation system based on thermal flash evaporation circulating rising film heat exchange according to claim 1, characterized in that: The lower head of the rising film reboiler (6) is equipped with a vapor-liquid distributor (61).

3. The heat pump distillation system based on thermal flash evaporation circulating rising film heat exchange according to claim 1, characterized in that: A cooler (3) is provided between the outlet of the condensate tank (5) and the condensate reflux port of the distillation column (1).

4. A heat pump distillation system based on thermal flash evaporation circulating rising film heat exchange as described in claim 1, characterized in that: A second throttle valve (11) is provided between the outlet of the condensate tank (5) and the condensate reflux port of the distillation column (1).

5. A heat pump distillation system based on thermal flash evaporation circulating rising film heat exchange as described in claim 1, characterized in that: The outlet of the condensate tank (5) is connected to the inlet of the reflux pump (4), and the outlet of the reflux pump (4) is connected to the condensate reflux port of the distillation column (1).

6. A heat pump distillation system based on thermal flash evaporation circulating rising film heat exchange as described in claim 1, characterized in that: A compressor (2) is provided between the secondary steam outlet of the distillation column (1) and the heating steam inlet of the rising film reboiler (6). The compressor (2) is used to pressurize and heat the secondary steam flowing out from the top of the distillation column (1).

7. A heat pump distillation system based on thermal flash evaporation circulating rising film heat exchange as described in claim 6, characterized in that: The compressor (2) is one of the following: centrifugal compressor, twin-screw compressor, or Roots compressor.

8. A heat pump distillation system based on thermal flash evaporation circulating rising film heat exchange according to claim 1, characterized in that: A circulating pump (10) is installed at the outlet of the distillation column (1).

9. A heat pump distillation system based on thermal flash evaporation circulating rising film heat exchange according to claim 1, characterized in that: It also includes a measurement and control system (8), which is used to monitor the temperature, pressure and flow parameters in the system in real time, and adjust the outlet temperature of the heat-induced heater (9) and the outlet pressure of the first throttle valve (7) in real time.

10. A heat pump distillation system based on thermal flash evaporation circulating rising film heat exchange according to claim 9, characterized in that: The measurement and control system (8) includes a temperature sensor and a pressure sensor disposed between the heat shock heater (9) and the first throttle valve (7), and also includes a pressure sensor disposed between the first throttle valve (7) and the rising film reboiler (6).

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