A heat pump energy-saving distillation system and process based on absorption refrigeration unit

Abstract

The invention discloses a heat pump energy-saving distillation system and process based on an absorption refrigeration unit in the field of distillation technology, comprising: a distillation tower and a reboiler, wherein the distillation system further comprises a second-class heat pump and a refrigeration component; in the invention, the second-class heat pump is used to recover the condensation heat of the tower top gas, thereby reducing the consumption of circulating water in public works; at the same time, the steam condensate flowing out of the reboiler of the distillation system is used as a driving heat source of the refrigeration component to produce cold capacity, a part of the cold capacity is used to supply the second-class heat pump through cold water, and a thermal potential difference is formed with the tower top gas entering the second-class heat pump, steam with a higher temperature than the tower top gas is produced in the second-class heat pump, and is input into the reboiler, thereby reducing the consumption of external steam by the distillation system and improving the utilization rate of energy in the distillation system, another part of the cold capacity produced by the refrigeration component is used to supercool the tower top product condensate of the distillation system before entering the pump, thereby avoiding cavitation of the pump.

Description

Technical Field

[0001] The invention relates to the technical field of distillation, and in particular to a heat pump energy-saving distillation system and process based on an absorption refrigeration unit. Background Art

[0002] Distillation is a distillation method that uses reflux to separate liquid mixtures to high purity. It is the most widely used liquid mixture separation operation in industry and is widely used in petroleum, chemical, light industry, food, metallurgy and other sectors. Typical distillation equipment is a continuous distillation unit (such as Figure 2 ), including a distillation tower, a reboiler, a first condenser, etc.; the distillation tower provides vapor-liquid two-phase contact for interphase mass transfer, the first condenser located at the top of the tower partially condenses the vapor, part of the condensate returns to the top of the tower as reflux liquid, and the remaining distillate is the top product of the tower; the reboiler located at the bottom of the tower partially vaporizes the liquid, the vapor rises along the tower, and the remaining liquid is the bottom product of the tower; the top gas temperature is relatively high, and the first condenser needs to use a large amount of circulating water as a cooling medium, which increases the consumption of circulating water in public works; in addition, when the top product condensate is pumped into the next section, because the top product condensate is mostly saturated liquid, it is very easy to cavitation in the pump, causing damage to the pump; in addition, most of the reboilers at the bottom of the tower use steam as a heat source, and the steam condensate coming out of the reboiler contains a lot of heat that is not utilized, resulting in reduced energy utilization. Summary of the invention

[0003] The object of the present invention is to provide a heat pump energy-saving distillation system and process based on an absorption refrigeration unit to solve the problem proposed in the above background technology that a large amount of circulating water needs to be used as a cooling medium, which increases the consumption of circulating water in public works. When the top product condensate is pumped into the next work section, cavitation is very likely to occur in the pump because the top product condensate is mostly saturated liquid.

[0004] To achieve the above object, the present invention provides the following technical solutions: a heat pump energy-saving distillation system based on an absorption refrigeration unit, comprising: a distillation tower and a reboiler, the distillation system also comprising a second type of heat pump and a refrigeration component;

[0005] The refrigeration component is used to recover the heat of the steam condensate discharged from the reboiler and use the heat for refrigeration. A part of the cold energy generated by the refrigeration is used for the second-class heat pump through cold water to form a thermal potential difference with the top gas entering the second-class heat pump. Steam with a higher temperature than the top gas is produced in the second-class heat pump and input into the reboiler, thereby reducing the consumption of external steam by the distillation system and improving the energy utilization rate in the distillation system. Another part of the cold energy generated by the refrigeration is used to supercool the top product condensate of the distillation system before it enters the pump, which can avoid cavitation of the pump. The second-class heat pump is used to recover the heat of the top gas discharged from the distillation tower and use the heat to drive the reboiler to work.

[0006] Preferably, the distillation system further comprises a one-way valve and a regulating valve;

[0007] The steam inlet of the reboiler is connected to the steam outlet of the second type heat pump through a one-way valve, and the steam inlet of the reboiler is also connected to an external gas supply device through a regulating valve.

[0008] Preferably, a flow detection component and a temperature detection component are provided on the steam outlet of the one-way valve.

[0009] Preferably, the refrigeration assembly includes a generator, a second condenser, an evaporator, an absorber, a solution pump, an expansion member and a pressure reducing member;

[0010] The heat source inlet of the generator is connected to the steam condensate outlet of the reboiler, the heat source outlet of the generator is connected to the second type of heat pump, and the refrigerant inlet and outlet of the evaporator are connected to the second type of heat pump.

[0011] Preferably, the generator, the second condenser, the evaporator, the absorber, the expansion member and the pressure reducing member are integrated into a tower refrigerator, the tower refrigerator comprises a tower body and a partition arranged in the tower body, the partition is used to divide the inner cavity of the tower body into a first cavity and a second cavity which are isolated from each other and distributed up and down;

[0012] A first right-angle baffle and a first spiral coil in the first right-angle baffle are provided above the inner cavity of the first cavity, a rich liquid outlet is provided at the bottom of the first right-angle baffle, a lean liquid inlet is provided at the top of the first cavity, a pressure reducing member is provided on the lean liquid inlet, a heat exchange straight pipe is provided below the inner cavity of the first cavity, both ends of the heat exchange straight pipe extend to the outside of the tower body and are respectively connected to two first pipe box barrel sections, a cold water inlet and a tower top product condensate inlet are provided on one of the first pipe box barrel sections, a cold water outlet and a tower top product condensate outlet are provided on the other first pipe box barrel section, a liquid refrigerant inlet between the first right-angle baffle and the heat exchange straight pipe is provided on the side wall of the first cavity, and an expansion member is provided on the liquid refrigerant inlet;

[0013] A second right-angle partition and a U-shaped heat exchange tube in the second right-angle partition are provided above the inner cavity of the second cavity, both ends of the U-shaped heat exchange tube extend to the outside of the tower body and are connected with the second tube box barrel section, a circulating water inlet and a circulating water outlet are provided on the second tube box barrel section, the circulating water inlet is connected with the first spiral coil, a liquid refrigerant outlet for connecting with the liquid refrigerant inlet is provided at the bottom of the second right-angle partition, a second spiral coil and a nozzle above the second spiral coil are provided below the inner cavity of the second cavity, a lean liquid outlet for connecting with the lean liquid inlet is provided at the bottom of the second cavity, and the rich liquid outlet is connected with the nozzle through a solution pump.

[0014] Preferably, a first orifice plate and a second orifice plate are provided in the first cavity, the first orifice plate is located above the first spiral coil, and the second orifice plate is located between the liquid refrigerant inlet and the heat exchange straight tube.

[0015] Preferably, the expansion member includes a second elastic member, a second plug plate, a second groove and a second bottom plate, and the pressure relief member includes a first bottom plate, a first groove, a first plug plate and a first elastic member.

[0016] Preferably, a first partition plate is provided in each of the two first pipe box barrel sections, and the first partition plate is used to separate the cold water inlet from the top product condensate inlet, and the cold water outlet from the top product condensate outlet. A second partition plate is provided in the second pipe box barrel section, and the second partition plate is used to separate the circulating water inlet from the circulating water outlet.

[0017] Preferably, a heat pump energy-saving distillation process based on an absorption refrigeration unit, using the above-mentioned heat pump energy-saving distillation system based on an absorption refrigeration unit, comprises the following steps:

[0018] S1: The steam condensate flowing out of the reboiler enters the generator, drives the refrigeration components to work, and makes the evaporator produce cold capacity. Part of the cold capacity is used to produce cold water and enters the second type heat pump. Part of the steam condensate from the generator is discharged from the unit, and the other part enters the second type heat pump;

[0019] S2: The top gas discharged from the distillation tower enters the second type heat pump, exchanges heat with cold water and steam condensate, heats the steam condensate into steam, and the steam enters the reboiler for circulation, and the cold water with increased temperature returns to the evaporator for circulation;

[0020] S3: The top gas is condensed into top product condensate in the second type heat pump, part of which is refluxed to the distillation tower, and the other part of the top product condensate enters the evaporator. The other part of the cooling capacity produced by the evaporator is cooled again and discharged.

[0021] Preferably, a heat pump energy-saving distillation process based on an absorption refrigeration unit, using the above-mentioned heat pump energy-saving distillation system based on an absorption refrigeration unit, further comprises the following steps:

[0022] S1: The steam condensate flowing out of the reboiler enters the second spiral coil, heats the high-pressure rich liquid sprayed on the surface of the second spiral coil through the nozzle, desorbs the refrigerant in the rich liquid and turns into high-pressure gaseous refrigerant. The high-pressure rich liquid turns into high-pressure lean liquid after the refrigerant is removed. Part of the steam condensate after heat exchange is discharged from the unit, and the other part enters the second type heat pump;

[0023] S2: The high-pressure gaseous refrigerant rises and contacts the U-shaped heat exchange tube, and is cooled by the circulating water flowing inside the U-shaped heat exchange tube into a high-pressure liquid refrigerant. The high-pressure liquid refrigerant rises through the pipeline and passes through the expansion piece, and then becomes a low-pressure liquid refrigerant.

[0024] S3: Low-pressure liquid refrigerant is evenly distributed on the outer surface of the heat exchange straight tube, absorbs the heat of the water flowing inside the heat exchange straight tube and the tower top product condensate, and vaporizes itself into low-pressure gaseous refrigerant. The water enters the second type of heat pump after cooling down. The tower top gas discharged from the distillation tower enters the second type of heat pump, exchanges heat with water and steam condensate, heats the steam condensate into steam and introduces it into the reboiler for recycling. The tower top gas is condensed into tower top product condensate in the second type of heat pump, part of which flows back to the distillation tower, and the other part enters the heat exchange straight tube to be cooled;

[0025] S4: The low-pressure gaseous refrigerant rises and contacts the first spiral coil. The high-pressure lean liquid in the second cavity rises through the pipeline and passes through the pressure reducing component to become a low-pressure lean liquid. The low-pressure lean liquid is evenly distributed on the outer surface of the first spiral coil and mixed with the low-pressure gaseous refrigerant to become a low-pressure rich liquid. The low-pressure rich liquid descends through the pipeline and is pressurized by the solution pump and sent to the nozzle for circulation.

[0026] Compared with the prior art, the present invention has the following beneficial effects:

[0027] 1. Optimize and improve the distillation system. Set a second-class heat pump at the top of the distillation tower to replace the original first condenser, and set a refrigeration component at the bottom of the distillation tower. Use the second-class heat pump to recover the condensation heat of the tower top gas. Compared with the original first condenser using circulating water as the cooling medium, it reduces the consumption of circulating water in public works. At the same time, the steam condensate flowing out of the reboiler of the distillation system is used as the driving heat source of the refrigeration component to produce cold capacity. A part of the cold capacity is used to supply the second-class heat pump through cold water, forming a thermal potential difference with the tower top gas entering the second-class heat pump. Steam with a higher temperature than the tower top gas is produced in the second-class heat pump and input into the reboiler, which can reduce the consumption of external steam by the distillation system and improve the energy utilization rate in the distillation system. Another part of the cold capacity produced by the refrigeration component is used to supercool the tower top product condensate of the distillation system before it enters the pump, which can avoid pump cavitation.

[0028] 2. The optimized and improved distillation system can integrate the refrigeration unit into a tower refrigerator and a solution pump through equipment integration, which can reduce the floor space of the distillation system;

[0029] 3. The tower refrigerator is divided into absorption section, evaporation section, condensation section and generation section from top to bottom through reasonable spatial arrangement. The height difference of the liquid level and the mutual conversion between the static pressure energy and the pressure energy of the liquid are utilized to change the low-pressure rich liquid before entering the solution pump into medium-pressure rich liquid, which can reduce the lift of the solution pump in the refrigeration unit, thereby reducing energy consumption, and changing the high-pressure liquid refrigerant before entering the expansion component into medium-pressure liquid refrigerant, and changing the high-pressure lean liquid before entering the pressure reducing component into medium-pressure lean liquid. At the same time, by setting the expansion component and the pressure reducing component, the expansion valve and the pressure reducing valve in the original refrigeration unit are replaced, and the expansion valve and the pressure reducing valve originally placed externally in the pipeline are built into the tower body, which reduces the risk of valve leakage and improves the safety and reliability of operation. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 It is a schematic diagram of the heat pump energy-saving distillation system of the present invention;

[0031] Figure 2 It is a schematic diagram of a distillation component in the prior art;

[0032] Figure 3 It is a schematic diagram of an absorption refrigeration unit in the prior art;

[0033] Figure 4 It is a schematic diagram of the connection structure between the reboiler and the tower refrigerator of the present invention;

[0034] Figure 5 It is a schematic diagram of the cross-sectional structure of the tower refrigerator of the present invention;

[0035] Figure 6 For the present invention Figure 5 The enlarged structural diagram at A in the middle;

[0036] Figure 7 For the present invention Figure 5 Enlarged structural diagram at B in the middle.

[0037] In the figure: 1, distillation tower; 2, reboiler; 3, first condenser; 4, generator; 5, second condenser; 6, evaporator; 7, absorber; 8, expansion valve; 9, pressure reducing valve; 10, solution pump; 11, second type heat pump; 12, one-way valve; 13, flow detection element; 14, temperature detection element; 15, regulating valve; 16, expansion element; 161, second elastic element; 162, second plug plate; 163, second groove; 164, second bottom plate; 17, pressure reducing element; 171, first bottom plate; 172 , the first groove; 173, the first plug plate; 174, the first elastic member; 18, the tower body; 181, the first cavity; 182, the second cavity; 19, the partition; 20, the first orifice plate; 21, the first right-angle partition; 22, the first spiral coil; 23, the second orifice plate; 24, the heat exchange straight tube; 25, the first tube box barrel section; 26, the first partition plate; 27, the second right-angle partition plate; 28, the U-shaped heat exchange tube; 29, the second tube box barrel section; 30, the second partition plate; 31, the second spiral coil; 32, the nozzle. DETAILED DESCRIPTION

[0038] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0039] Example 1

[0040] See also Figure 1 A heat pump energy-saving distillation system based on an absorption refrigeration unit includes: a distillation tower 1, a reboiler 2, a second type heat pump 11, a refrigeration component, a one-way valve 12 and a regulating valve 15.

[0041] It should be noted that the second type of heat pump 11 refers to a heat pump that utilizes the thermal potential difference between medium-temperature waste heat and low-temperature waste heat to produce a small amount of heat with a temperature higher than that of medium-temperature waste heat, thereby improving the quality of part of the waste heat. It is also called a temperature-raising heat pump.

[0042] See also Figure 1 , the refrigeration assembly includes a generator 4, a second condenser 5, an evaporator 6, an absorber 7, a solution pump 10, an expansion member 16 and a pressure reducing member 17;

[0043] Among them, the second type heat pump 11 replaces the condensing equipment in the original distillation process, and the second type heat pump 11 is connected to the top gas outlet and the top reflux liquid inlet of the distillation tower 1; the steam outlet of the second type heat pump 11 is connected to the steam inlet of the reboiler 2 through the one-way valve 12, and the steam inlet of the reboiler 2 is also connected to the external gas supply equipment through the regulating valve 15 (the external gas supply equipment refers to the device for introducing steam from the outside to the inside of the reboiler 2); the high-pressure gaseous refrigerant outlet of the generator 4 is connected to the high-pressure gaseous refrigerant inlet of the second condenser 5, the lean liquid outlet of the generator 4 is connected to the lean liquid inlet of the absorber 7 through the pressure reducing member 17, and the rich liquid inlet of the generator 4 is connected to the rich liquid outlet of the absorber 7 through the solution pump 10; the circulating water outlet of the absorber 7 is connected to the circulating water outlet of the second condenser 5 The water inlet is connected, the low-pressure gaseous refrigerant inlet of the absorber 7 is connected to the low-pressure gaseous refrigerant outlet of the evaporator 6, and the low-pressure liquid refrigerant inlet of the evaporator 6 is connected to the high-pressure liquid refrigerant outlet of the second condenser 5 through the expansion piece 16; the heat source inlet of the generator 4 is connected to the steam condensate outlet of the reboiler 2, and a three-way pipe is provided on the heat source outlet of the generator 4, and one interface of the three-way pipe is connected to the second type of heat pump 11, the coolant inlet and outlet (cold water inlet and outlet) of the evaporator 6 are connected to the cold water inlet and outlet of the second type of heat pump 11, and the tower top product condensate outlet of the second type of heat pump 11 is connected to the coolant inlet of the evaporator 6 (the coolant inlet and the above-mentioned cold water inlet are two separate inlets, and the flow pipes of the tower top product condensate and water in the evaporator 6 are different).

[0044] In this embodiment, as a further optimized solution, please refer to Figure 1 A flow detection component 13 and a temperature detection component 14 are provided on the steam outlet pipe of the one-way valve 12. The flow detection component 13 can be a gas flow detector, and the temperature detection component 14 can be a gas temperature detector.

[0045] It should be noted that the absorption refrigeration unit uses low-grade waste heat to drive the thermal working medium and performs refrigeration through the phase change of the working medium (such as ammonia) (this technology belongs to the prior art); the main equipment includes a generator 4, a second condenser 5, an evaporator 6, an absorber 7, a solution pump 10, etc. Figure 3As shown, the low-grade waste heat is used to heat the generator 4, and the mixed solution (referred to as rich liquid) with a certain concentration of refrigerant is delivered from the absorber 7 by the solution pump 10, so that most of the low-boiling-point refrigerant in the rich solution is desorbed and becomes high-pressure gaseous refrigerant, which enters the second condenser 5 and is cooled by circulating water to become high-pressure liquid refrigerant. The high-pressure liquid refrigerant is decompressed into low-pressure liquid refrigerant through the expansion valve 8, and the low-pressure liquid refrigerant enters the evaporator 6, absorbs the heat of the medium (coolant) to be cooled, and vaporizes into Low-pressure gaseous refrigerant, low-pressure gaseous refrigerant enters the absorber 7; the high-pressure lean liquid remaining after the generation process in the generator 4 is reduced in pressure by the pressure reducing valve 9 to become a low-pressure lean liquid, enters the absorber 7, and is mixed and absorbed with the low-pressure gaseous refrigerant coming out of the evaporator 6, and restored to its original concentration to become a room-temperature rich liquid. The room-temperature rich liquid is pressurized by the solution pump 10 and then sent to the generator to continue circulating; the circulating water is first used to cool the absorber solution and then to cool the condenser; the above process is the working process of the absorption refrigeration unit in the prior art.

[0046] A heat pump energy-saving distillation process based on an absorption refrigeration unit comprises the following steps:

[0047] First, the regulating valve 15 is opened, and the steam added from the outside enters the reboiler 2 (providing the first heat in the distillation process), heats the bottom liquid, and provides reboiled gas for the distillation tower 1 in the distillation process. The steam after heat exchange becomes steam condensate and flows into the generator 4; in the distillation process, the top gas generated by the distillation tower 1 enters the second type heat pump 11 (the distillation step belongs to the prior art and is not described in detail here);

[0048] Second, the steam condensate enters the generator 4, heats the rich liquid in the generator 4, and splits the rich liquid into a lean liquid and a high-pressure gaseous refrigerant. The high-pressure gaseous refrigerant enters the second condenser 5 to exchange heat with the circulating water and condenses into a high-pressure liquid refrigerant. The high-pressure liquid refrigerant is decompressed into a low-pressure liquid refrigerant through the expansion element 16 and enters the evaporator 6 to exchange heat with the coolant in the evaporator 6 to cool the coolant. A part of the coolant is water. After the water is cooled to cold water, the cold water enters the second type heat pump 11. The steam condensate is heated from the generator 11 to The condensate is discharged from the generator 4, a part of which is discharged from the unit, and the other part of which enters the second type heat pump 11 (the low-pressure liquid refrigerant in the evaporator 6 becomes a low-pressure gaseous refrigerant after cooling the refrigerant and enters the absorber 7. The lean liquid produced by the generator 4 is decompressed by the decompression member 17 and enters the absorber 7 to mix with the low-pressure gaseous refrigerant to form a rich liquid. The rich liquid is transported to the generator 4 by the solution pump 10 to continue to circulate. The working mode of the refrigeration component is the same as that of the absorption refrigeration unit, which will not be described in detail here);

[0049] Third, the top gas discharged from the distillation tower 1 enters the second type heat pump 11, and exchanges heat with cold water and steam condensate (the second type heat pump 11 uses the incoming top gas as a medium-temperature heat source to form a thermal potential difference with the cold water entering it, and heats the incoming steam condensate to steam with a higher temperature than the top gas). After the steam condensate is heated to steam, the steam passes through the one-way valve 12 and enters the reboiler 2 for recycling; the regulating valve 15 detects the steam produced by the second type heat pump 11 through the flow detection component 13 and the temperature detection component 14, senses the flow rate and temperature of the steam, and compares them with the theoretical value set by the distillation process, thereby controlling the opening of the regulating valve 15 (the control process is controlled and regulated by a control device, such as a PLC controller), which can reduce the input of supplementary steam; after heat exchange, the cold water with increased temperature returns to the evaporator 6 for circulation;

[0050] Fourth, the top gas is condensed into top product condensate in the second type heat pump 11 (the second type heat pump 11 recovers the condensation heat of the top gas), part of which flows back to the distillation tower 1, and the other part of the top product condensate enters the evaporator 6 to exchange heat with the low-pressure liquid refrigerant. The top product condensate is cooled again and then discharged from the evaporator 6 to become supercooled top product condensate. When the supercooled top product condensate is transported to the next stage by a pump, it enters the pump to avoid pump cavitation.

[0051] Example 2

[0052] As a further optimized solution of Example 1, please refer to Figure 4 and Figure 5 , the generator 4, the second condenser 5, the evaporator 6, the absorber 7, the expansion member 16 and the pressure reducing member 17 are integrated into a tower refrigerator;

[0053] The tower refrigerator includes a tower body 18, in which a partition 19 is installed. The partition 19 is used to divide the inner cavity of the tower body 18 into a first cavity 181 and a second cavity 182. The first cavity 181 and the second cavity 182 are isolated from each other, and the first cavity 181 is located above the second cavity 182.

[0054] A first right-angle partition 21 is provided on one side wall above the inner cavity of the first cavity 181 (the first right-angle partition 21 cooperates with the inner side wall of the tower body 18 to form a space with only the top open), a channel is formed between the side wall of the first right-angle partition 21 and the other side wall above the inner cavity of the first cavity 181 (the channel is for gaseous refrigerant to pass through), a first spiral coil 22 is installed in the inner cavity of the first cavity 181, the first spiral coil 22 is located on the inner side of the first right-angle partition 21, a rich liquid outlet is provided at the bottom of the first right-angle partition 21, and a lean liquid inlet is provided at the top of the first cavity 181 (the lean liquid inlet is located just above the first spiral coil 22). The lean liquid inlet is provided with a pressure reducing member 17; a transversely arranged heat exchange straight tube 24 is provided below the inner cavity of the first cavity 181, both ends of the heat exchange straight tube 24 extend to the outside of the tower body 18, and both ends of the heat exchange straight tube 24 are connected to the first pipe box barrel section 25, one first pipe box barrel section 25 is provided with a cold water inlet and a tower top product condensate inlet, and the other first pipe box barrel section 25 is provided with a cold water outlet and a tower top product condensate outlet, a liquid refrigerant inlet is opened on the side wall of the first cavity 181, the liquid refrigerant inlet is located between the first right angle partition 21 and the heat exchange straight tube 24, and an expansion member 16 is provided on the liquid refrigerant inlet;

[0055] It should be noted that the cold water inlet and the cold water outlet of the first pipe-box barrel section 25 are respectively connected to the cold water outlet and the cold water inlet of the second type heat pump 11; the tower top product condensate inlet of the first pipe-box barrel section 25 is connected to the tower top product condensate outlet of the second type heat pump 11; the first spiral coil 22 is used to pass circulating water; the expansion member 16 and the pressure reducing member 17 are both installed inside the tower body 18;

[0056] A second right-angled partition plate 27 is provided on one side wall above the inner cavity of the second cavity 182 (the second right-angled partition plate 27 cooperates with the inner side wall of the tower body 18 to form a space with only the top open), a channel is formed between the side wall of the second right-angled partition plate 27 and the other side wall above the inner cavity of the first cavity 181 (the channel is for the gaseous refrigerant to pass through), a U-shaped heat exchange tube 28 is installed in the inner cavity of the second cavity 182, the U-shaped heat exchange tube 28 is located on the inner side of the second right-angled partition plate 27, both ends of the U-shaped heat exchange tube 28 extend to the outer side of the tower body 18, and both ends of the U-shaped heat exchange tube 28 are connected to the outer side of the tower body 18. A second pipe-box barrel section 29 is connected, and a circulating water inlet and a circulating water outlet are arranged on the second pipe-box barrel section 29, and the circulating water inlet is connected to the outlet of the first spiral coil 22. A liquid refrigerant outlet is opened at the bottom of the second right-angle partition plate 27, and the liquid refrigerant outlet is connected to the liquid refrigerant inlet. A second spiral coil 31 and a nozzle 32 are arranged below the inner cavity of the second cavity 182, and the nozzle 32 is located above the second spiral coil 31. A lean liquid outlet is opened at the bottom of the second cavity 182, and the lean liquid outlet is connected to the lean liquid inlet. The rich liquid outlet is connected to the nozzle 32 through the solution pump 10;

[0057] It should be noted that the inlet end of the second spiral coil 31 is connected to the steam condensate outlet of the reboiler 2 , and a tee is provided on the outlet end of the second spiral coil 31 , wherein one interface of the tee is connected to the second type heat pump 11 .

[0058] In this embodiment, as a further optimized solution, please refer to Figure 5 A first orifice plate 20 and a second orifice plate 23 are provided in the inner cavity of the first cavity 181 . The first orifice plate 20 is located above the first spiral coil 22 , and the second orifice plate 23 is located between the liquid refrigerant inlet and the heat exchange straight tube 24 .

[0059] In this embodiment, as a further optimized solution, please refer to Figure 5 , Figure 6 and Figure 7 The expansion member 16 includes a second elastic member 161 (spring), a second plug plate 162, a second groove 163 and a second bottom plate 164. The second bottom plate 164 is installed on the right side wall of the first cavity 181. The second groove 163 is arranged on the left side wall of the second bottom plate 164, and the second groove 163 is communicated with the liquid refrigerant inlet. The second elastic member 161 is arranged on the left side wall of the first cavity 181. The right end of the second elastic member 161 is connected to the second plug plate 162. The right side wall of the second plug plate 162 is in contact with the left side wall of the second bottom plate 164, and the second plug Plate 162 covers the second groove 163; the pressure relief member 17 includes a first bottom plate 171, a first groove 172, a first plug plate 173 and a first elastic member 174 (spring), the first bottom plate 171 is installed at the top of the inner cavity of the first cavity 181, the first groove 172 is arranged at the bottom of the first bottom plate 171, the first elastic member 174 is installed on the first orifice plate 20, the top of the first elastic member 174 is connected to the first plug plate 173, the top of the first plug plate 173 is in contact with the bottom of the first bottom plate 171, and the first plug plate 173 covers the first groove 172.

[0060] It should be noted that the expansion valve 8 and the pressure reducing valve 9 in the original refrigeration unit are replaced by the expansion member 16 and the pressure reducing member 17, and the expansion valve 8 and the pressure reducing valve 9 originally placed outside in the pipeline are built into the tower body 18, thereby reducing the risk of valve leakage and improving the safety and reliability of operation.

[0061] In this embodiment, as a further optimized solution, please refer to Figure 5 A first partition plate 26 is provided in the inner cavity of the two first pipe box barrel sections 25. The first partition plate 26 is used to separate the cold water inlet from the tower top product condensate inlet and the cold water outlet from the tower top product condensate outlet, so that the cold water and the tower top product condensate will not be mixed together. A second partition plate 30 is provided in the inner cavity of the second pipe box barrel section 29. The second partition plate 30 is used to separate the circulating water inlet and the circulating water outlet.

[0062] It should be noted that the partition 19 , the first right-angle partition 21 , the second right-angle partition 27 , the first partition plate 26 , and the second partition plate 30 are all made of heat-insulating materials.

[0063] It should also be noted that when the refrigeration component is a tower refrigerator, the working mode of the distillation system is:

[0064] First, the regulating valve 15 is opened, and the steam added from the outside enters the reboiler 2, providing the first heat for the distillation system, driving the distillation tower 1 to work (the distillation process is a prior art and is not described in detail here), preparing the top gas and introducing it into the second type heat pump 11, and the steam after heat exchange becomes steam condensate and is discharged from the reboiler 2;

[0065] Second, the steam condensate flowing out of the reboiler 2 enters the second spiral coil 31 inside the second cavity 182, and heats the high-pressure rich liquid sprayed on the surface of the second spiral coil 31 through the nozzle 32, so that most of the low-boiling-point refrigerant in the rich liquid is desorbed to become a high-pressure gaseous refrigerant. The high-pressure rich liquid becomes a high-pressure lean liquid after the refrigerant is removed. The steam condensate after heat exchange is discharged from the second spiral coil 31, a part of which is discharged from the unit, and the other part of the steam condensate enters the second type heat pump 11;

[0066] Third, the high-pressure gaseous refrigerant moves upward and enters the inner side of the second right-angle partition 27 and contacts the U-shaped heat exchange tube 28, and is cooled by the circulating water flowing inside the U-shaped heat exchange tube 28 into a high-pressure liquid refrigerant. The high-pressure liquid refrigerant is discharged from the liquid refrigerant outlet of the second right-angle partition 27, enters the interior of the first cavity 181 from the liquid refrigerant inlet, and is decompressed by the expansion member 16 (due to the increase in the height of the pipeline and the increase in the static pressure of the liquid column, the high-pressure liquid refrigerant has become a medium-pressure liquid refrigerant before entering the expansion member 16, and the medium-pressure liquid refrigerant pushes the second elastic member 161 of the expansion member 16. Because the pressure of the medium-pressure liquid refrigerant is slightly greater than the thrust of the second elastic member 161, the second plug plate 162 is slightly opened, and the medium-pressure liquid refrigerant is throttled and decompressed into a low-pressure liquid refrigerant through the micro-opening between the second bottom plate 164 and the second plug plate 162), and becomes a low-pressure liquid refrigerant;

[0067] Fourth, the low-pressure liquid refrigerant is evenly distributed on the outer surface of the heat exchange straight tube 24 through the second orifice plate 23, absorbs the heat of the refrigerant (the refrigerant is water and the tower top product condensate) flowing inside the heat exchange straight tube 24, and vaporizes itself into a low-pressure gaseous refrigerant. After cooling, the water enters the second type heat pump 11 through the cold water outlet, and the tower top gas discharged from the distillation tower 1 enters the second type heat pump 11, exchanges heat with the cold water and the steam condensate, and after the steam condensate is heated into steam, the steam enters the reboiler 2 through the one-way valve 12 for recycling. The tower top gas is condensed into tower top product condensate in the second type heat pump 11, a part of which flows back to the distillation tower 1, and the other part of the tower top product condensate enters the heat exchange straight tube 24, is cooled into a supercooled tower top product condensate and is discharged;

[0068] Fifth, the low-pressure gaseous refrigerant enters upward into the inner side of the first right-angle partition plate 21 and contacts the first spiral coil 22. The high-pressure lean liquid in the second cavity 182 is discharged from the lean liquid outlet, and is transported upward through the pipeline to enter the inner cavity of the first cavity 181 from the lean liquid inlet, and is decompressed into a low-pressure lean liquid through the pressure reducing member 17 (due to the increase in the height of the pipeline and the increase in the static pressure of the liquid column, the high-pressure lean liquid has become a medium-pressure lean liquid before entering the pressure reducing member 17, and the medium-pressure lean liquid pushes the first elastic member 174 of the pressure reducing member 17. Because the pressure of the medium-pressure lean liquid is slightly greater than the thrust of the first elastic member 174, the first plug plate 173 is slightly moved downward to open, and the medium-pressure lean liquid is throttled and decompressed into a low-pressure lean liquid through the micro-opening between the first bottom plate 171 and the first plug plate 173). The low-pressure lean liquid passes through the first orifice plate 20 is evenly distributed on the outer surface of the first spiral coil 22, and is mixed with the incoming low-pressure gaseous refrigerant to form a low-pressure rich liquid. The heat generated in the process is taken away by the circulating water in the first spiral coil 22 (the circulating water inside the first spiral coil 22 is discharged and enters the U-shaped heat exchange tube 28 for internal flow), and the low-pressure rich liquid is discharged from the rich liquid outlet and transported to the solution pump 10 through a pipeline. As the height of the pipeline is decreasing, the gravitational potential energy of the liquid is converted into the pressure energy of the liquid. The low-pressure rich liquid has become a medium-pressure rich liquid before entering the solution pump 10 (the lift of the solution pump 10 can be reduced, thereby reducing energy consumption). The medium-pressure rich liquid is further pressurized by the solution pump 10 and then sent to the nozzle 32 for circulation. The circulating water is first used to cool the solution in the absorption section and then used to cool the condensation section.

[0069] It should be noted that the "high pressure" in "high pressure liquid refrigerant, high pressure gaseous refrigerant, high pressure lean liquid, high pressure rich liquid" is (1.0~2.1) MPa (G); the "low pressure" in "low pressure liquid refrigerant, low pressure gaseous refrigerant, low pressure lean liquid, low pressure rich liquid" is (-0.06~0.33) MPa (G).

[0070] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A heat pump energy-saving distillation system based on an absorption refrigeration unit, comprising: A distillation tower (1) and a reboiler (2), characterized in that: the distillation system further comprises a second type heat pump (11) and a refrigeration component; The refrigeration component is used to recover the heat of the steam condensate discharged from the reboiler (2) and use the heat to perform refrigeration. A portion of the cold energy generated by the refrigeration enters the second-class heat pump (11) to cool the top gas discharged from the distillation tower (1). Another portion of the cold energy generated by the refrigeration is used to cool the top product condensate discharged from the second-class heat pump (11). The second-class heat pump (11) is used to recover the heat of the top gas discharged from the distillation tower (1) and use the heat to drive the reboiler (2) to work. The refrigeration assembly comprises a generator (4), a second condenser (5), an evaporator (6), an absorber (7), a solution pump (10), an expansion member (16) and a pressure reducing member (17); The heat source inlet of the generator (4) is connected to the steam condensate outlet of the reboiler (2), the heat source outlet of the generator (4) is connected to the second type of heat pump (11), and the refrigerant inlet and outlet of the evaporator (6) are connected to the second type of heat pump (11); The distillation system further comprises a one-way valve (12) and a regulating valve (15); The steam inlet of the reboiler (2) is connected to the steam outlet of the second type heat pump (11) through a one-way valve (12), and the steam inlet of the reboiler (2) is also connected to an external gas supply device through a regulating valve (15); A flow detection component (13) and a temperature detection component (14) are provided on the steam outlet of the one-way valve (12); The generator (4), the second condenser (5), the evaporator (6), the absorber (7), the expansion element (16) and the pressure reducing element (17) are integrated into a tower refrigerator, the tower refrigerator comprising a tower body (18) and a partition (19) arranged in the tower body (18), the partition (19) being used to divide the inner cavity of the tower body (18) into a first cavity (181) and a second cavity (182) which are isolated from each other and are distributed up and down; A first right-angle baffle (21) and a first spiral coil (22) located in the first right-angle baffle (21) are provided above the inner cavity of the first cavity (181); a rich liquid outlet is provided at the bottom of the first right-angle baffle (21); a lean liquid inlet is provided at the top of the first cavity (181); a pressure reducing member (17) is provided on the lean liquid inlet; a heat exchange straight tube (24) is provided below the inner cavity of the first cavity (181); both ends of the heat exchange straight tube (24) extend to the outside of the tower body (18) and are respectively connected to two first pipe box barrel sections (25); one of the first pipe box barrel sections (25) is provided with a cold water inlet and a tower top product condensate inlet; the other first pipe box barrel section (25) is provided with a cold water outlet and a tower top product condensate outlet; a liquid refrigerant inlet is provided on the side wall of the first cavity (181) and is located between the first right-angle baffle (21) and the heat exchange straight tube (24); an expansion member (16) is provided on the liquid refrigerant inlet; A second right-angled baffle (27) and a U-shaped heat exchange tube (28) located in the second right-angled baffle (27) are provided above the inner cavity of the second cavity (182); both ends of the U-shaped heat exchange tube (28) extend to the outside of the tower body (18) and are connected to the second tube box barrel section (29); a circulating water inlet and a circulating water outlet are provided on the second tube box barrel section (29); the circulating water inlet is connected to the first spiral coil (22); a liquid refrigerant outlet for connecting to the liquid refrigerant inlet is provided at the bottom of the second right-angled baffle (27); a second spiral coil (31) and a nozzle (32) located above the second spiral coil (31) are provided below the inner cavity of the second cavity (182); a lean liquid outlet for connecting to the lean liquid inlet is provided at the bottom of the second cavity (182); and the rich liquid outlet is connected to the nozzle (32) via a solution pump (10).

2. A heat pump energy-saving distillation system based on an absorption refrigeration unit according to claim 1, characterized in that: A first orifice plate (20) and a second orifice plate (23) are provided in the first cavity (181); the first orifice plate (20) is located above the first spiral coil (22), and the second orifice plate (23) is located between the liquid refrigerant inlet and the heat exchange straight tube (24).

3. A heat pump energy-saving distillation system based on an absorption refrigeration unit according to claim 2, characterized in that: The expansion member (16) comprises a second elastic member (161), a second plug plate (162), a second groove (163) and a second bottom plate (164); the pressure relief member (17) comprises a first bottom plate (171), a first groove (172), a first plug plate (173) and a first elastic member (174).

4. A heat pump energy-saving distillation system based on an absorption refrigeration unit according to claim 3, characterized in that: A first partition plate (26) is provided in each of the two first pipe box barrel sections (25), and the first partition plate (26) is used to separate the cold water inlet from the tower top product condensate inlet, and the cold water outlet from the tower top product condensate outlet. A second partition plate (30) is provided in the second pipe box barrel section (29), and the second partition plate (30) is used to separate the circulating water inlet from the circulating water outlet.

5. A heat pump energy-saving distillation process based on an absorption refrigeration unit, using a heat pump energy-saving distillation system based on an absorption refrigeration unit as claimed in claim 1, characterized in that: The following steps are involved: S1: The steam condensate flowing out of the reboiler (2) enters the generator (4), drives the refrigeration component to work, and makes the evaporator (6) produce cold energy. A part of the cold energy is used to produce cold water and enters the second type heat pump (11). A part of the steam condensate flowing out of the generator (4) is discharged from the unit, and the other part enters the second type heat pump (11); S2: The top gas discharged from the distillation tower (1) enters the second type heat pump (11), exchanges heat with cold water and steam condensate, heats the steam condensate into steam, and the steam enters the reboiler (2) for recycling. The cold water with increased temperature returns to the evaporator (6) for circulation; S3: The tower top gas is condensed into tower top product condensate in the second type heat pump (11), a part of which is refluxed to the distillation tower (1), and another part of the tower top product condensate enters the evaporator (6). The other part of the cold energy produced by the evaporator (6) is cooled again and then discharged.

6. A heat pump energy-saving distillation process based on an absorption refrigeration unit, using a heat pump energy-saving distillation system based on an absorption refrigeration unit as claimed in any one of claims 1 to 4, characterized in that: The following steps are involved: S1: The steam condensate flowing out of the reboiler (2) enters the second spiral coil (31), heats the high-pressure rich liquid sprayed on the surface of the second spiral coil (31) through the nozzle (32), desorbs the refrigerant in the rich liquid, and turns into a high-pressure gaseous refrigerant. After the refrigerant is removed, the high-pressure rich liquid turns into a high-pressure lean liquid. After the heat exchange, part of the steam condensate is discharged from the unit, and the other part enters the second type heat pump (11); S2: The high-pressure gaseous refrigerant rises and contacts the U-shaped heat exchange tube (28), and is cooled by the circulating water flowing inside the U-shaped heat exchange tube (28) to become a high-pressure liquid refrigerant. The high-pressure liquid refrigerant rises through the pipeline and passes through the expansion element (16), and then becomes a low-pressure liquid refrigerant. S3: The low-pressure liquid refrigerant is evenly distributed on the outer surface of the heat exchange straight tube (24), absorbs the heat of the water flowing inside the heat exchange straight tube (24) and the tower top product condensate, and vaporizes itself into a low-pressure gaseous refrigerant. After the water is cooled, it enters the second-class heat pump (11). The tower top gas discharged from the distillation tower (1) enters the second-class heat pump (11) and exchanges heat with the water and the steam condensate. The steam condensate is heated into steam and introduced into the reboiler (2) for recycling. The tower top gas is condensed into tower top product condensate in the second-class heat pump (11), a part of which flows back to the distillation tower (1), and the other part enters the heat exchange straight tube (24) to be cooled; S4: The low-pressure gaseous refrigerant rises and contacts the first spiral coil (22). The high-pressure lean liquid in the second chamber (182) rises through the pipeline and passes through the pressure reducing member (17) to become a low-pressure lean liquid. The low-pressure lean liquid is evenly distributed on the outer surface of the first spiral coil (22) and is mixed with the low-pressure gaseous refrigerant to become a low-pressure rich liquid. The low-pressure rich liquid is transported down through the pipeline and then pressurized by the solution pump (10) and sent to the nozzle (32) for recycling.

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