Energy-saving multi-effect evaporation system and process based on absorption refrigeration and heat pump

Abstract

This invention discloses an energy-saving multi-effect evaporation system and process based on absorption refrigeration and heat pump in the field of multi-effect evaporation technology. The system includes: a first-effect evaporator, a second-effect evaporator, a third-effect evaporator, a steam condenser, a primary feed pump, and a secondary feed pump. The multi-effect evaporation system also includes a refrigeration unit, a high-pressure evaporator, and a high-pressure absorber. This application recovers waste heat from the multi-effect evaporation process using absorption refrigeration and heat pump technology to generate circulating steam of the same grade as the source steam. This serves as a supplement to the source steam during the evaporation process, reducing both the consumption of source steam and the energy consumption of the cooling tower for cooling medium-temperature water.

Description

Technical Field

[0001] This invention relates to the field of multi-effect evaporation, specifically to an energy-saving multi-effect evaporation system and process based on absorption refrigeration and heat pump. Background Technology

[0002] Multi-effect evaporation technology connects multiple single-effect evaporators in series, reusing the vaporization and condensation of steam generated during evaporation, significantly reducing the consumption of source steam and thus improving the economic efficiency of the evaporation unit. Triple-effect evaporation is a commonly used form in multi-effect evaporation systems, consisting of three evaporators, two feed pumps, and a steam condensation tower (e.g., Figure 1 , Figure 2 (As shown in the upper part) The source steam and the feed liquid are respectively processed in countercurrent operation through the first-effect evaporator, the second-effect evaporator, and the third-effect evaporator;

[0003] The specific process is as follows: Source steam enters the first-effect evaporator, heating the secondary feed liquid pumped from the second-effect evaporator. This evaporates the water in the secondary feed liquid into primary steam, turning the source steam into source steam condensate. The secondary feed liquid then passes through the first-effect evaporator to become the finished liquid and is transported to the downstream process. The primary steam serves as the heat source for the second-effect evaporator, heating the primary feed liquid pumped from the third-effect evaporator. This evaporates the water in the primary feed liquid into secondary steam, turning the primary steam into primary steam condensate. The primary feed liquid then passes through the second-effect evaporator to become the secondary feed liquid. The secondary steam is then used as... The heat source of the triple-effect evaporator heats the initial feed liquid, causing the water in the initial feed liquid to evaporate into tertiary steam. The secondary steam becomes secondary steam condensate. The initial feed liquid becomes primary feed liquid after passing through the triple-effect evaporator. The tertiary steam enters the steam condenser tower and is condensed by cooling water into medium-temperature water, which is then sent to the cooling tower to be cooled to room temperature and recycled. However, although the multi-effect evaporation process can reduce the consumption of source steam, the heat energy consumption in the evaporation process is still relatively large, and the waste heat in the multi-effect evaporation process (such as source steam condensate, primary steam condensate, secondary steam condensate, and medium-temperature water) is not fully utilized. Summary of the Invention

[0004] The purpose of this invention is to provide an energy-saving multi-effect evaporation system and process based on absorption refrigeration and heat pump, which solves the defects of existing multi-effect evaporation processes.

[0005] The present invention achieves the above objectives through the following technical solution: an energy-saving multi-effect evaporation system based on absorption refrigeration and heat pump, comprising: a first-effect evaporator, a second-effect evaporator, a third-effect evaporator, a steam condenser, a primary feed pump and a secondary feed pump, wherein the multi-effect evaporation system further comprises a refrigeration unit, a high-pressure evaporator and a high-pressure absorber.

[0006] The refrigeration unit is used to absorb the heat of the steam condensate discharged from the second-effect evaporator and the third-effect evaporator to produce cooling capacity. The high-pressure evaporator is used to absorb the heat of the steam condensate discharged from the second-effect evaporator and the third-effect evaporator using part of the cooling capacity produced by the refrigeration unit. The high-pressure absorber is used to heat the steam condensate discharged from the first-effect evaporator using the heat generated from producing rich liquid, so that it is vaporized and used as a heat source for the first-effect evaporator.

[0007] Preferably, the multi-effect evaporation system further includes a steam condensate ejector, which is used to use the steam condensate discharged from the second-effect evaporator as an ejector source to eject the steam condensate discharged from the third-effect evaporator.

[0008] Preferably, the steam condensate ejector is located above the high-pressure evaporator, and the first-effect evaporator is located above the high-pressure absorber.

[0009] Preferably, the refrigeration unit includes a medium-pressure generator, a medium-pressure condenser, an expansion valve, a first pressure reducing valve, a low-pressure evaporator, a low-pressure absorber, and a solution pump.

[0010] Preferably, the multi-effect evaporation system further includes a second pressure reducing valve and a liquid refrigerant pump;

[0011] The second pressure reducing valve is used to reduce the pressure of the rich liquid introduced from the high-pressure absorber into the medium-pressure generator, and the liquid refrigerant pump is used to increase the pressure of the liquid refrigerant introduced from the medium-pressure condenser into the high-pressure evaporator.

[0012] Preferably, the cooling water outlet of the low-pressure absorber is connected to the cooling water inlet of the medium-pressure condenser, the cooling water outlet of the medium-pressure condenser is connected to the steam condensing tower, and the low-pressure evaporator is used to cool the medium-temperature water discharged from the steam condensing tower.

[0013] Preferably, a composite cooler is used to replace the medium-pressure generator, medium-pressure condenser, low-pressure evaporator and low-pressure absorber, and a composite heat pump is used to replace the high-pressure evaporator and high-pressure absorber. Both the composite cooler and the composite heat pump are fixed tube sheet heat exchangers whose main structure consists of a head, tube box section, tube sheet, heat exchange tubes and shell.

[0014] The composite cooler includes a low-pressure absorption chamber, a low-pressure evaporation chamber, a medium-pressure condensation chamber, and a medium-pressure generating chamber, while the composite heat pump includes a high-pressure absorption chamber and a high-pressure evaporation chamber.

[0015] Preferably, the low-pressure absorption chamber, low-pressure evaporation chamber, medium-pressure condensation chamber and medium-pressure generating chamber are separated by a first partition, and the high-pressure absorption chamber and high-pressure evaporation chamber are separated by a second partition.

[0016] Preferably, an energy-saving multi-effect evaporation process based on absorption refrigeration and heat pumps, utilizing the aforementioned energy-saving multi-effect evaporation system based on absorption refrigeration and heat pumps, includes the following steps:

[0017] The steam condensate discharged from the double-effect evaporator and the triple-effect evaporator sequentially enters the high-pressure evaporation chamber and the medium-pressure generating chamber;

[0018] The vapor condensate is used as a heat source to heat the medium-pressure rich liquid in the medium-pressure generating chamber to produce medium-pressure gaseous refrigerant. The medium-pressure gaseous refrigerant enters the medium-pressure condensing chamber and is condensed into medium-pressure liquid refrigerant. It is then divided into two paths: one path enters the low-pressure evaporating chamber to continue circulating, and the other path enters the high-pressure evaporating chamber to absorb the heat of the vapor condensate discharged from the double-effect evaporator and triple-effect evaporator, and vaporizes itself into high-pressure gaseous refrigerant.

[0019] High-pressure gaseous refrigerant enters the high-pressure absorption chamber and is absorbed by the secondary rich liquid discharged from the low-pressure absorption chamber to form a high-pressure rich liquid, which continues to circulate. The heat generated during the absorption process is used to heat the vapor condensate discharged from the first-effect evaporator, so that it is vaporized and used as the heat source for the first-effect evaporator.

[0020] An energy-saving multi-effect evaporation process based on absorption refrigeration and heat pumps, further utilizing the aforementioned energy-saving multi-effect evaporation system based on absorption refrigeration and heat pumps, includes the following steps:

[0021] The steam condensate discharged from the double-effect evaporator and the triple-effect evaporator sequentially enters the high-pressure evaporator and the medium-pressure generator;

[0022] The vapor condensate is used as a heat source to heat the medium-pressure rich liquid in the medium-pressure generator to produce medium-pressure gaseous refrigerant. The medium-pressure gaseous refrigerant enters the medium-pressure condenser and is condensed into medium-pressure liquid refrigerant. It is then divided into two paths: one path enters the low-pressure evaporator to continue circulating, and the other path enters the high-pressure evaporator to absorb the heat from the vapor condensate discharged from the double-effect and triple-effect evaporators and vaporize itself into high-pressure gaseous refrigerant.

[0023] High-pressure gaseous refrigerant enters the high-pressure absorber and is absorbed by the secondary rich liquid discharged from the low-pressure absorber to form a high-pressure rich liquid, which continues to circulate. The heat generated during the absorption process is used to heat the vapor condensate discharged from the first-effect evaporator, causing it to vaporize and serve as the heat source for the first-effect evaporator.

[0024] The beneficial effects of this invention are as follows:

[0025] 1. Waste heat from the multi-effect evaporation process (such as source steam condensate, primary steam condensate, secondary steam condensate, and medium-temperature water) is recovered through absorption refrigeration and heat pump technology to generate circulating steam of the same grade as the source steam. This replenishes the source steam in the evaporation process, reducing the consumption of source steam and thus reducing heat energy consumption. It also reduces the energy consumption required for cooling towers to cool medium-temperature water. Furthermore, embedding absorption refrigeration and heat pump technology into the multi-effect evaporation process expands the application scenarios of absorption refrigeration and heat pump technology, which is of great strategic significance for achieving energy conservation and emission reduction.

[0026] 2. The steam condensate ejector uses primary steam condensate to eject secondary steam condensate, which can mix two streams of waste heat of different grades into a single grade of waste heat, avoiding the risk of water hammer and pipeline vibration caused by flash evaporation of waste heat of different grades in the pipeline.

[0027] 3. This application utilizes the height difference of the equipment arrangement to allow the source steam condensate and the primary and secondary steam condensate to enter the composite heat pump cooler under the action of gravity, thereby reducing the power consumption required for steam condensate transportation. Attached Figure Description

[0028] Figure 1 This is a schematic diagram of the energy-saving multi-effect evaporation system based on absorption refrigeration and heat pump of the present invention;

[0029] Figure 2 This is a schematic diagram showing the connection between the composite heat pump cooler and the steam condensate ejector of the present invention;

[0030] Figure 3 This is a cross-sectional view of the connection between the composite cooler and the composite heat pump of the present invention;

[0031] Figure 4 For the present invention Figure 3 Schematic diagram of the CC direction;

[0032] Figure 5 For the present invention Figure 3 Schematic diagram of the DD direction.

[0033] In the diagram: 1. First-effect evaporator; 2. Second-effect evaporator; 3. Third-effect evaporator; 4. Steam condenser; 5. Primary feed pump; 6. Secondary feed pump; 7. Steam condensate ejector; 8. High-pressure evaporator; 9. High-pressure absorber; 10. Second pressure reducing valve; 11. Liquid refrigerant pump; 12. Medium-pressure generator; 13. Medium-pressure condenser; 14. Expansion valve; 15. First pressure reducing valve; 16. Low-pressure evaporator; 17. Low-pressure absorber; 18. Solution pump; 19. Composite cooler; 191. Low-pressure absorption chamber; 192. Low-pressure evaporation chamber; 193. Medium-pressure condensation chamber; 194. Medium-pressure generator chamber; 195. First baffle; 20. Composite heat pump; 201. High-pressure absorption chamber; 202. High-pressure evaporation chamber; 203. Second baffle. Detailed Implementation

[0034] The present application will now be described in further detail with reference to the accompanying drawings. It should be noted that the following specific embodiments are only used to further illustrate the present application and should not be construed as limiting the scope of protection of the present application. Those skilled in the art can make some non-essential improvements and adjustments to the present application based on the above application content.

[0035] Example 1

[0036] Please see Figure 1 An energy-saving multi-effect evaporation system based on absorption refrigeration and heat pump includes: a first-effect evaporator 1, a second-effect evaporator 2, a third-effect evaporator 3, a steam condenser tower 4, a primary feed pump 5, a secondary feed pump 6, a refrigeration unit, a steam condensate ejector 7, a high-pressure evaporator 8, a high-pressure absorber 9, a second pressure reducing valve 10, and a liquid refrigerant pump 11.

[0037] Among them, there are medium-pressure generator 12, medium-pressure condenser 13, expansion valve 14, first pressure reducing valve 15, low-pressure evaporator 16, low-pressure absorber 17 and solution pump 18.

[0038] The two inlets of the condensate ejector 7 are connected to the condensate outlets of the second-effect evaporator 2 and the third-effect evaporator 3, respectively. The outlet of the condensate ejector 7 is connected to the heat source inlet of the high-pressure evaporator 8. The heat source outlet of the high-pressure evaporator 8 is connected to the heat source inlet of the medium-pressure generator 12. The high-pressure gaseous refrigerant outlet of the high-pressure evaporator 8 is connected to the high-pressure gaseous refrigerant inlet of the high-pressure absorber 9. The high-pressure liquid refrigerant inlet of the high-pressure evaporator 8 is connected to one outlet of the medium-pressure liquid refrigerant of the medium-pressure condenser 13 (the medium-pressure condenser 13 has two medium-pressure liquid refrigerant outlets) via the liquid refrigerant pump 11. The high-pressure secondary rich liquid inlet of the high-pressure absorber 9 is connected to the low-pressure secondary rich liquid outlet of the low-pressure absorber 17 via the solution pump 18. The high-pressure rich liquid outlet of the high-pressure absorber 9 is connected to the medium-pressure rich liquid inlet of the medium-pressure generator 12 via the second pressure reducing valve 10. The cooling medium inlet and outlet are respectively connected to the steam condensate outlet and source steam inlet of the first-effect evaporator 1; the medium-pressure lean liquid outlet of the medium-pressure generator 12 is connected to the low-pressure lean liquid inlet of the low-pressure absorber 17 through the first pressure reducing valve 15; the medium-pressure gaseous refrigerant outlet of the medium-pressure generator 12 is connected to the medium-pressure gaseous refrigerant inlet of the medium-pressure condenser 13; another medium-pressure liquid refrigerant outlet of the medium-pressure condenser 13 is connected to the low-pressure liquid refrigerant inlet of the low-pressure evaporator 16 through the expansion valve 14; the low-pressure gaseous refrigerant outlet of the low-pressure evaporator 16 is connected to the low-pressure gaseous refrigerant inlet of the low-pressure absorber 17; the cooling water outlet of the low-pressure absorber 17 is connected to the cooling water inlet of the medium-pressure condenser 13; the cooling water outlet of the medium-pressure condenser 13 is connected to the cooling water inlet of the steam condensing tower 4; and the medium-temperature water outlet of the steam condensing tower 4 is connected to the refrigerant inlet (i.e., the medium-temperature water inlet) of the low-pressure evaporator 16.

[0039] In this embodiment, as a further optimization, please refer to... Figure 1 The steam condensate ejector 7 is located above the high-pressure evaporator 8, and the first-effect evaporator 1 is located above the high-pressure absorber 9. The source steam condensate flowing out of the first-effect evaporator 1 enters the high-pressure absorber 9 under the action of gravity by utilizing the height difference of the equipment arrangement. The primary and secondary steam condensates flowing out of the steam condensate ejector 7 enter the high-pressure evaporator 8 and the medium-pressure generator 12 in sequence under the action of gravity, reducing the power consumption required for steam condensate transportation.

[0040] An energy-saving multi-effect evaporation process based on absorption refrigeration and heat pump includes the following steps:

[0041] Source steam enters the first-effect evaporator 1 and heats the secondary feed liquid delivered from the second-effect evaporator 2 by the secondary feed pump 6, causing the water in the secondary feed liquid to evaporate into primary steam. The source steam becomes source steam condensate. The secondary feed liquid is then processed by the first-effect evaporator 1 to become a finished liquid and is transported to the downstream process. The primary steam serves as the heat source for the second-effect evaporator 2 and heats the primary feed liquid delivered from the third-effect evaporator 3 by the primary feed pump 5, causing the water in the primary feed liquid to evaporate into secondary steam. The primary steam becomes primary steam condensate. The primary feed liquid is then processed by the second-effect evaporator 2 to become a secondary feed liquid. The secondary steam serves as the heat source for the third-effect evaporator 3 and heats the initial feed liquid, causing the water in the initial feed liquid to evaporate into tertiary steam. The secondary steam becomes secondary steam condensate. The initial feed liquid is then processed by the third-effect evaporator 3 to become a primary feed liquid. The tertiary steam enters the steam condenser 4 and is condensed by cooling water to become medium-temperature water.

[0042] The primary steam condensate flowing out of the double-effect evaporator 2 is used as the ejector source and enters the steam condensate ejector 7 to eject the secondary steam condensate flowing out of the triple-effect evaporator 3. The two are mixed to become primary and secondary steam condensate (the temperature is between that of primary and secondary steam condensate). Utilizing the height difference of the equipment arrangement, the mixed primary and secondary steam condensate enters the high-pressure evaporator 8 first under the action of gravity, and then enters the medium-pressure generator 12.

[0043] The primary and secondary steam condensate is heated in the medium-pressure generator 12 to obtain the medium-pressure rich liquid which is depressurized by the second pressure reducing valve 10, causing most of the low-boiling-point refrigerant in the medium-pressure rich liquid to desorb and become medium-pressure gaseous refrigerant. The medium-pressure gaseous refrigerant enters the medium-pressure condenser 13, where it is cooled by cooling water into medium-pressure liquid refrigerant. It is then divided into two paths: one path is depressurized by the expansion valve 14 to become low-pressure liquid refrigerant and enters the low-pressure evaporator 16; the other path is pressurized by the liquid refrigerant pump 11 to become high-pressure liquid refrigerant and enters the high-pressure evaporator 8.

[0044] The low-pressure liquid refrigerant entering the low-pressure evaporator 16 absorbs heat from the medium-temperature water flowing out of the steam condenser 4 and vaporizes into low-pressure gaseous refrigerant, which then enters the low-pressure absorber 17. The medium-pressure lean liquid remaining in the medium-pressure generator 12 is depressurized into low-pressure lean liquid by the first pressure reducing valve 15 and enters the low-pressure absorber 17, where it mixes and absorbs with the low-pressure gaseous refrigerant coming out of the low-pressure evaporator 16 to become low-pressure secondary rich liquid. The heat released during the absorption process is carried away by the cooling water. The low-pressure secondary rich liquid is pressurized by the solution pump 18 to become high-pressure secondary rich liquid, and then enters the high-pressure absorber 9.

[0045] The high-pressure liquid refrigerant entering the high-pressure evaporator 8 absorbs heat from the primary and secondary steam condensate and vaporizes into high-pressure gaseous refrigerant. It then enters the high-pressure absorber 9 and mixes with the high-pressure secondary rich liquid to form a high-pressure rich liquid. The heat released during the absorption process heats the source steam condensate flowing in under gravity into circulating steam (the source steam condensate is discharged from the first-effect evaporator 1). The circulating steam serves as supplementary steam for the source steam and enters the first-effect evaporator 1 to continue the subsequent cycle. The high-pressure rich liquid formed in the high-pressure absorber 9 is depressurized by the second pressure reducing valve 10 to become a medium-pressure rich liquid and enters the medium-pressure generator 12 to continue the subsequent cycle.

[0046] It should be noted that the source steam condensate flowing out of the first-effect evaporator 1 enters the high-pressure absorber 9, where it is heated by the heat generated during the absorption process and becomes circulating steam, which then returns to the first-effect evaporator 1 as supplementary steam for the source steam. The primary and secondary steam condensates flowing out of the steam condensate ejector 7 enter the high-pressure evaporator 8 and the medium-pressure generator 12 in sequence, where the heat contained therein is recovered and utilized in the high-pressure evaporator 8 and the medium-pressure generator 12, respectively.

[0047] It should also be noted that the cooling water sequentially enters the low-pressure absorber 17, the medium-pressure condenser 13, and the steam condensing tower 4. It is first used to cool the solution in the low-pressure absorber 17, then used to cool the medium-pressure condenser 13, and finally condenses the tertiary steam flowing out of the triple-effect evaporator 3 and mixes it with the steam to become medium-temperature water. The medium-temperature water enters the low-pressure evaporator 16 and is cooled by heat absorption to become medium-room temperature water, and then goes to the cooling tower.

[0048] Example 2

[0049] As a further optimization of Example 1, please refer to Figure 2 The high-pressure absorber 9, high-pressure evaporator 8, medium-pressure generator 12, medium-pressure condenser 13, low-pressure absorber 17, low-pressure evaporator 16, solution pump 18, liquid refrigerant pump 11, expansion valve 14, first pressure reducing valve 15, and second pressure reducing valve 10 are integrated into a composite heat pump cooler; the composite heat pump cooler consists of a composite cooler 19, a composite heat pump 20, a solution pump 18, a liquid refrigerant pump 11, an expansion valve 14, a first pressure reducing valve 15, and a second pressure reducing valve 10;

[0050] Please see Figure 3 , Figure 4 and Figure 5 Both the composite cooler 19 and the composite heat pump 20 are fixed tube sheet heat exchangers whose main structure consists of a head, tube box section, tube sheet, heat exchange tubes and shell.

[0051] The composite cooler 19 has a first partition 195 in its inner cavity, which divides the inner cavity of the composite cooler 19 into a low-pressure absorption chamber 191, a low-pressure evaporation chamber 192, a medium-pressure condensation chamber 193, and a medium-pressure generating chamber 194; the composite heat pump 20 has a second partition 203 in its inner cavity, which divides the inner cavity of the composite heat pump 20 into a high-pressure absorption chamber 201 and a high-pressure evaporation chamber 202.

[0052] The low-pressure absorption chamber 191 is equipped with a spray assembly (including a spray pipe and a nozzle) inside its shell. The shell of the low-pressure absorption chamber 191 is provided with a low-pressure lean solution inlet and a low-pressure secondary rich solution outlet. The low-pressure lean solution inlet is connected to the spray pipe and the first pressure reducing valve 15 through a pipe. The low-pressure secondary rich solution outlet is connected to the inlet of the solution pump 18 through a pipe. The left and right pipe boxes of the low-pressure absorption chamber 191 are respectively provided with cooling water inlet and outlet.

[0053] The low-pressure evaporator chamber 192 is equipped with a spray assembly (including a spray pipe and a nozzle) inside its shell. The low-pressure liquid refrigerant inlet is provided on the shell of the low-pressure evaporator chamber 192. The low-pressure liquid refrigerant inlet is connected to the spray pipe and the expansion valve 14 through a pipe. The left and right pipe boxes of the low-pressure evaporator chamber 192 are respectively equipped with a medium-temperature water inlet and a medium-normal temperature water outlet.

[0054] The shell of the medium-pressure condensing chamber 193 is provided with a medium-pressure liquid refrigerant outlet. The medium-pressure liquid refrigerant outlet is divided into two paths through a pipeline. One path is connected to the expansion valve 14, and the other path is connected to the inlet of the liquid refrigerant pump 11. The left and right tube boxes of the medium-pressure condensing chamber 193 are respectively provided with cooling water inlet and outlet. The cooling water inlet is connected to the cooling water outlet on the right tube box of the low-pressure absorption chamber 191 through a pipeline. The cooling water outlet is connected to the cooling water inlet of the steam condensing tower 4.

[0055] The shell of the medium-pressure generating chamber 194 is equipped with a spray assembly (including a spray pipe and a nozzle). The shell of the medium-pressure generating chamber 194 is equipped with a medium-pressure rich liquid inlet and a medium-pressure lean liquid outlet. The medium-pressure rich liquid inlet is connected to the spray pipe and the second pressure reducing valve 10 through a pipe. The medium-pressure lean liquid outlet is connected to the first pressure reducing valve 15 through a pipe. The left and right pipe boxes of the medium-pressure generating chamber 194 are respectively equipped with primary and secondary steam condensate inlets and outlets.

[0056] The high-pressure evaporator 202 is equipped with a spray assembly (including a spray pipe and a nozzle) inside its shell. The high-pressure liquid refrigerant inlet is provided on the shell of the high-pressure evaporator 202. The high-pressure liquid refrigerant inlet is connected to the spray pipe and the outlet of the liquid refrigerant pump 11 through a pipe. The left and right tube boxes of the high-pressure evaporator 202 are respectively provided with primary and secondary steam condensate outlets and inlets. The primary and secondary steam condensate outlets are connected to the primary and secondary steam condensate inlet on the left tube box of the medium-pressure generating chamber 194 through a pipe.

[0057] The high-pressure absorption chamber 201 is equipped with a spray assembly (including a spray pipe and a nozzle) inside its shell. The high-pressure absorption chamber 201 is equipped with a high-pressure secondary rich liquid inlet and a high-pressure rich liquid outlet. The high-pressure secondary rich liquid inlet is connected to the spray pipe and the outlet of the solution pump 18 through a pipe. The high-pressure rich liquid outlet is connected to the second pressure reducing valve 10 through a pipe. The left and right pipe boxes of the high-pressure absorption chamber 201 are respectively equipped with a circulating steam outlet and a source steam condensate inlet. The circulating steam outlet and the source steam condensate inlet are respectively connected to the source steam inlet and the source steam condensate outlet of the first-effect evaporator 1.

[0058] In this embodiment, as a further optimization, please refer to... Figure 4 A first opening is provided on the second partition 203 inside the shell of the high-pressure absorption chamber 201, through which the inner cavity of the high-pressure absorption chamber 201 is connected to the inner cavity of the high-pressure evaporation chamber 202; a second opening is provided on the first partition 195 inside the shell of the low-pressure absorption chamber 191, through which the inner cavity of the low-pressure absorption chamber 191 is connected to the inner cavity of the low-pressure evaporation chamber 192; a third opening is provided on the first partition 195 inside the shell of the medium-pressure condensation chamber 193, through which the inner cavity of the medium-pressure condensation chamber 193 is connected to the inner cavity of the medium-pressure generating chamber 194; each of the first, second, and third openings is provided with a baffle plate.

[0059] In this embodiment, as a further optimization, please refer to... Figure 3 , Figure 4 and Figure 5 The composite cooler 19 and the composite heat pump 20 are connected together by a support plate.

[0060] An energy-saving multi-effect evaporation process based on absorption refrigeration and heat pump includes the following steps:

[0061] Source steam enters the first-effect evaporator 1 and heats the secondary feed liquid delivered from the second-effect evaporator 2 by the secondary feed pump 6, causing the water in the secondary feed liquid to evaporate into primary steam. The source steam becomes source steam condensate. The secondary feed liquid is then processed by the first-effect evaporator 1 to become the finished liquid and is transported to the downstream process. The primary steam serves as the heat source for the second-effect evaporator 2 and heats the primary feed liquid delivered from the third-effect evaporator 3 by the primary feed pump 5, causing the water in the primary feed liquid to evaporate into secondary steam. The primary steam becomes primary steam condensate. The primary feed liquid is then processed by the second-effect evaporator 2 to become the secondary feed liquid. The secondary steam serves as the heat source for the third-effect evaporator 3 and heats the initial feed liquid, causing the water in the initial feed liquid to evaporate into tertiary steam. The secondary steam becomes secondary steam condensate. The initial feed liquid is then processed by the third-effect evaporator 3 to become the primary feed liquid. The tertiary steam enters the steam condenser 4 and is condensed by cooling water to become medium-temperature water.

[0062] The primary steam condensate flowing out of the double-effect evaporator 2 is used as the ejector source and enters the steam condensate ejector 7 to eject the secondary steam condensate flowing out of the triple-effect evaporator 3. The two are mixed to become primary and secondary steam condensate (the temperature is between that of the primary and secondary steam condensate). Utilizing the height difference of the equipment arrangement, the mixed primary and secondary steam condensate first enters the tube side of the high-pressure evaporation chamber 202 under the action of gravity, and then enters the tube side of the medium-pressure generating chamber 194.

[0063] The primary and secondary vapor condensate heats the medium-pressure rich liquid, which is depressurized by the second pressure reducing valve 10, in the tube side of the medium-pressure generating chamber 194, causing most of the low-boiling-point refrigerant in the medium-pressure rich liquid to desorb and become medium-pressure gaseous refrigerant. The medium-pressure gaseous refrigerant enters the shell side of the medium-pressure condensing chamber 193, where it is cooled into medium-pressure liquid refrigerant by the cooling water in the tube side. Then, it is divided into two paths: one path is depressurized by the expansion valve 14 to become low-pressure liquid refrigerant and enters the shell side of the low-pressure evaporating chamber 192; the other path is pressurized by the liquid refrigerant pump 11 to become high-pressure liquid refrigerant and enters the shell side of the high-pressure evaporating chamber 202.

[0064] The low-pressure liquid refrigerant entering the shell side of the low-pressure evaporator 192 absorbs the heat from the medium-temperature water flowing out of the steam condenser 4 in the tube side and vaporizes into low-pressure gaseous refrigerant, which then enters the shell side of the low-pressure absorption chamber 191. The medium-pressure lean liquid remaining in the shell side of the medium-pressure generating chamber 194 is depressurized into low-pressure lean liquid by the first pressure reducing valve 15 and enters the shell side of the low-pressure absorption chamber 191, where it mixes and absorbs with the low-pressure gaseous refrigerant coming out of the low-pressure evaporator 192 to become low-pressure secondary rich liquid. The heat released during the absorption process is carried away by the cooling water in the tube side. The low-pressure secondary rich liquid formed in the shell side of the low-pressure absorption chamber 191 is pressurized by the solution pump 18 to become high-pressure secondary rich liquid and enters the shell side of the high-pressure absorption chamber 201.

[0065] The high-pressure liquid refrigerant entering the shell side of the high-pressure evaporator 202 absorbs heat from the primary and secondary vapor condensate entering the tube side and vaporizes into high-pressure gaseous refrigerant. This gaseous refrigerant then enters the shell side of the high-pressure absorption chamber 201, where it mixes and absorbs with the incoming high-pressure secondary rich liquid, becoming high-pressure rich liquid. The heat released during absorption heats the source vapor condensate flowing in under gravity, turning it into circulating steam. This circulating steam serves as supplementary steam to the source steam and enters the first-effect evaporator 1 to continue the subsequent cycle. The high-pressure rich liquid formed in the shell side of the high-pressure absorption chamber 201 is then depressurized by the second pressure reducing valve 10 to become medium-pressure rich liquid, which enters the shell side of the medium-pressure generating chamber 194 to continue the subsequent cycle.

[0066] It should be noted that the source steam condensate flowing out of the first-effect evaporator 1 enters the tube side of the high-pressure absorption chamber 201, where it is heated by the heat generated during the absorption process and becomes circulating steam, returning to the first-effect evaporator 1 as supplementary steam to the source steam. The primary and secondary steam condensates flowing out of the steam condensate ejector 7 sequentially enter the tube side of the high-pressure evaporation chamber 202 and the tube side of the medium-pressure generating chamber 194, where the heat contained therein is recovered and utilized in the high-pressure evaporation chamber 202 and the medium-pressure generating chamber 194, respectively. The cooling water sequentially enters the tube side of the low-pressure absorption chamber 191, the tube side of the medium-pressure condensing chamber 193, and the steam condensing tower 4. It is first used to cool the solution in the low-pressure absorption chamber 191, then used to cool the solution in the medium-pressure condensing chamber 193, and finally condenses the tertiary steam flowing out of the third-effect evaporator 3 and mixes it with the tertiary steam to become medium-temperature water, which enters the tube side of the low-pressure evaporation chamber 192 and is cooled by heat absorption to become medium-room temperature water, before going to the cooling tower.

[0067] It should also be noted that the integration of the above equipment can reduce the cost of equipment and piping, greatly reduce the footprint of the unit, and facilitate skid-mounted installation of the unit.

[0068] The embodiments described above are merely examples of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention.

Claims

1. An energy-saving multi-effect evaporation system based on absorption refrigeration and heat pump, comprising: The multi-effect evaporator system comprises a single-effect evaporator (1), a double-effect evaporator (2), a triple-effect evaporator (3), a steam condenser (4), a primary feed pump (5), and a secondary feed pump (6), characterized in that the multi-effect evaporation system further comprises a refrigeration unit, a high-pressure evaporator (8), and a high-pressure absorber (9). The refrigeration unit is used to absorb the heat of the steam condensate discharged from the second-effect evaporator (2) and the third-effect evaporator (3) to produce cooling capacity. The high-pressure evaporator (8) is used to absorb the heat of the steam condensate discharged from the second-effect evaporator (2) and the third-effect evaporator (3) using part of the cooling capacity produced by the refrigeration unit. The high-pressure absorber (9) is used to heat the steam condensate discharged from the first-effect evaporator (1) using the heat generated from producing rich liquid, so that it is vaporized and used as the heat source of the first-effect evaporator (1). The refrigeration unit includes a medium-pressure generator (12), a medium-pressure condenser (13), an expansion valve (14), a first pressure reducing valve (15), a low-pressure evaporator (16), a low-pressure absorber (17), and a solution pump (18). The cooling water outlet of the low-pressure absorber (17) is connected to the cooling water inlet of the medium-pressure condenser (13), the cooling water outlet of the medium-pressure condenser (13) is connected to the steam condensing tower (4), and the low-pressure evaporator (16) is used to cool the medium-temperature water discharged from the steam condensing tower (4).

2. The energy-saving multi-effect evaporation system based on absorption refrigeration and heat pump according to claim 1, characterized in that, The multi-effect evaporation system also includes a steam condensate ejector (7), which is used to eject the steam condensate discharged from the second-effect evaporator (2) as an ejector source to eject the steam condensate discharged from the third-effect evaporator (3).

3. The energy-saving multi-effect evaporation system based on absorption refrigeration and heat pump according to claim 2, characterized in that, The steam condensate ejector (7) is located above the high-pressure evaporator (8), and the single-effect evaporator (1) is located above the high-pressure absorber (9).

4. The energy-saving multi-effect evaporation system based on absorption refrigeration and heat pump according to claim 1, characterized in that, The multi-effect evaporation system also includes a second pressure reducing valve (10) and a liquid refrigerant pump (11). The second pressure reducing valve (10) is used to reduce the pressure of the rich liquid introduced into the medium-pressure generator (12) by the high-pressure absorber (9), and the liquid refrigerant pump (11) is used to increase the pressure of the liquid refrigerant introduced into the high-pressure evaporator (8) by the medium-pressure condenser (13).

5. The energy-saving multi-effect evaporation system based on absorption refrigeration and heat pump according to claim 1, characterized in that, A composite cooler (19) is used to replace the medium-pressure generator (12), medium-pressure condenser (13), low-pressure evaporator (16) and low-pressure absorber (17), and a composite heat pump (20) is used to replace the high-pressure evaporator (8) and high-pressure absorber (9). Both the composite cooler (19) and the composite heat pump (20) are fixed tube sheet heat exchangers whose main structure consists of a head, tube box section, tube sheet, heat exchange tube and shell. The composite cooler (19) includes a low-pressure absorption chamber (191), a low-pressure evaporation chamber (192), a medium-pressure condensation chamber (193), and a medium-pressure generating chamber (194), and the composite heat pump (20) includes a high-pressure absorption chamber (201) and a high-pressure evaporation chamber (202).

6. The energy-saving multi-effect evaporation system based on absorption refrigeration and heat pump according to claim 5, characterized in that, The low-pressure absorption chamber (191), low-pressure evaporation chamber (192), medium-pressure condensation chamber (193) and medium-pressure generating chamber (194) are separated by a first partition (195), and the high-pressure absorption chamber (201) and high-pressure evaporation chamber (202) are separated by a second partition (203).

7. An energy-saving multi-effect evaporation process based on absorption refrigeration and heat pump, utilizing the energy-saving multi-effect evaporation system based on absorption refrigeration and heat pump as described in claim 1, characterized in that... Includes the following steps: The steam condensate discharged from the double-effect evaporator (2) and the triple-effect evaporator (3) sequentially enters the high-pressure evaporator (8) and the medium-pressure generator (12); The vapor condensate is used as a heat source to heat the medium-pressure rich liquid in the medium-pressure generator (12) to produce medium-pressure gaseous refrigerant. The medium-pressure gaseous refrigerant enters the medium-pressure condenser (13) and is condensed into medium-pressure liquid refrigerant. It is then divided into two paths: one path enters the low-pressure evaporator (16) to continue circulating, and the other path enters the high-pressure evaporator (8) to absorb the heat of the vapor condensate discharged from the double-effect evaporator (2) and the triple-effect evaporator (3) and vaporizes itself into high-pressure gaseous refrigerant. High-pressure gaseous refrigerant enters the high-pressure absorber (9) and is absorbed by the secondary rich liquid discharged from the low-pressure absorber (17) to form a high-pressure rich liquid, which continues to circulate. The heat generated during the absorption process is used to heat the steam condensate discharged from the first-effect evaporator (1) so that it is vaporized and used as the heat source of the first-effect evaporator (1).

8. An energy-saving multi-effect evaporation process based on absorption refrigeration and heat pump, utilizing an energy-saving multi-effect evaporation system based on absorption refrigeration and heat pump as described in any one of claims 5-6, characterized in that, Includes the following steps: The steam condensate discharged from the double-effect evaporator (2) and the triple-effect evaporator (3) enters the high-pressure evaporation chamber (202) and the medium-pressure generating chamber (194) in sequence; The vapor condensate is used as a heat source to heat the medium-pressure rich liquid in the medium-pressure generating chamber (194) to produce medium-pressure gaseous refrigerant. The medium-pressure gaseous refrigerant enters the medium-pressure condensing chamber (193) and is condensed into medium-pressure liquid refrigerant. It is then divided into two paths: one path enters the low-pressure evaporating chamber (192) to continue circulating, and the other path enters the high-pressure evaporating chamber (202) to absorb the heat of the vapor condensate discharged from the double-effect evaporator (2) and the triple-effect evaporator (3) and vaporizes itself into high-pressure gaseous refrigerant. High-pressure gaseous refrigerant enters the high-pressure absorption chamber (201) and is absorbed by the secondary rich liquid discharged from the low-pressure absorption chamber (191) to form a high-pressure rich liquid, which continues to circulate. The heat generated during the absorption process is used to heat the steam condensate discharged from the first-effect evaporator (1) so that it is vaporized and used as the heat source of the first-effect evaporator (1).

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