Waste heat recovery system for decarburization process

Abstract

The invention provides a decarburization process waste heat recovery system which comprises an absorption tower used for receiving generated gas and carrying out decarburization treatment; the first regeneration tower is used for receiving the solution in the absorption tower and removing carbon dioxide in the solution to obtain a regenerated decarburized solution and carbon dioxide; the pressure reducing device is used for receiving the regenerated decarburization solution and reducing pressure, and the first refrigerating unit can take the regenerated decarburization solution as a driving heat source, so that the regenerated decarburization solution is cooled to a first preset temperature, and the circulating water is cooled to a second preset temperature; the second refrigerating unit is connected with the first refrigerating unit, and the second refrigerating unit can take the regenerated decarburization solution cooled by the first refrigerating unit as a driving heat source, so that the regenerated decarburization solution is cooled from the first preset temperature to a third preset temperature, and the circulating water is cooled to a fourth preset temperature. The heat of the regenerated decarburization solution is used as a driving heat source to cool the regenerated decarburization solution and circulating water, so that a more efficient carbon dioxide absorption process is carried out in the decarburization tower.

Description

Technical Field

[0001] The present invention relates to the technical field of synthetic ammonia, and in particular to a waste heat recovery system for a decarbonization process. Background Art

[0002] In the decarbonization process of synthetic ammonia, the carbon dioxide in the synthetic conversion gas is removed to below 0.5%wt, and then sent to the refining process, and part of the carbon dioxide is recovered. There are many existing decarbonization technologies, and the decarbonization process selection is also different for different materials and different methods of manufacturing synthesis gas. Among them, the improved hot potash method (Benzfield method) belongs to the chemical absorption method, using diethanolamine as the activator, and the industry adopts ejector flash technology and voltage swing regeneration energy-saving technology. This process is relatively mature and has certain advantages in energy saving and consumption reduction. Therefore, the Benzfield method is currently a more commonly used decarbonization method at home and abroad.

[0003] Among them, although the Benfil process adopts pressure swing regeneration decarbonization and steam ejector technology, in the actual production process, there is still a large amount of low-level heat energy in the decarbonization system that is not utilized. Summary of the invention

[0004] The object of the present invention is to provide a waste heat recovery system for a decarbonization process, so as to solve the problem that a large amount of low-level heat energy is not utilized in the decarbonization process of synthetic ammonia in the prior art.

[0005] In order to solve the above technical problems, the present invention provides a waste heat recovery system for a decarburization process, comprising:

[0006] An absorption tower, which is used to receive the generated gas containing carbon dioxide and perform decarbonization treatment; the absorption tower is provided with a decarbonization solution for absorbing carbon dioxide gas;

[0007] A first regeneration tower connected to the absorption tower; the first regeneration tower is used to receive the solution in the absorption tower and remove carbon dioxide from the solution to obtain a regenerated decarbonation solution and carbon dioxide;

[0008] A decompression device, connected to the first regeneration tower, for receiving the regenerated decarbonization solution and decompressing it;

[0009] A cold water tank for containing circulating water;

[0010] a first refrigeration unit, connected to the cold water tank and the pressure reducing device respectively to receive the circulating water and the regenerated decarbonization solution, wherein the first refrigeration unit can use the regenerated decarbonization solution as a driving heat source to cool the regenerated decarbonization solution to a first preset temperature and cool the circulating water to a second preset temperature;

[0011] a second refrigeration unit connected to the first refrigeration unit to receive the regenerated decarbonization solution and circulating water, the second refrigeration unit being capable of using the regenerated decarbonization solution cooled by the first refrigeration unit as a driving heat source to cool the regenerated decarbonization solution from the first preset temperature to the third preset temperature, and the circulating water to the fourth preset temperature;

[0012] The second refrigeration unit is connected to the absorption tower to transport the regenerated decarbonization solution to the absorption tower, and the second refrigeration unit is also used to connect to external equipment to transport circulating water.

[0013] In one embodiment, the external device is configured as a synthetic ammonia device of a synthetic ammonia system; the second refrigeration unit delivers circulating water to the synthetic ammonia device. The absorption tower receives the generated gas generated by the conversion process of the synthetic ammonia system, and delivers the generated gas after removing carbon dioxide to the synthetic ammonia device.

[0014] In one embodiment, the refrigerant of the first refrigeration unit includes water, and the absorbent of the first refrigeration unit includes at least one of calcium chloride, lithium nitrate or potassium formate.

[0015] In one embodiment, the refrigerant of the second refrigeration unit includes ethylene oxide, and the absorbent of the second refrigeration unit includes amino acid type ionic liquid.

[0016] In one embodiment, the cation in the amino acid type ionic liquid includes at least one of a quaternary ammonium type cation and an imidazolium type cation.

[0017] In one embodiment, the anions in the amino acid type ionic liquid include at least one of glutamic acid, glycine, and proline ions.

[0018] In one embodiment, the absorbent of the first refrigeration unit includes calcium chloride and lithium nitrate, wherein the content of the calcium chloride is 70 wt% to 90 wt%, and the content of the lithium nitrate is 10 wt% to 30 wt%.

[0019] In one embodiment, the absorbent of the first refrigeration unit includes calcium chloride and potassium formate, wherein the content of the calcium chloride is 70 wt % to 90 wt %, and the content of the potassium formate is 10 wt % to 30 wt %.

[0020] In one embodiment, the absorbent of the first refrigeration unit contains 75 wt% to 85 wt% of calcium chloride, 8 wt% to 10 wt% of lithium nitrate and 5 wt% to 10 wt% of potassium formate.

[0021] In one embodiment, the decarbonation solution comprises a potassium carbonate solution.

[0022] In one embodiment, the regenerated decarbonation solution includes a potassium carbonate solution.

[0023] In one embodiment, the circulating water in the cold water tank is desalted water.

[0024] In one embodiment, the first refrigeration unit includes a first generator, a first absorber, a first evaporator and a first condenser;

[0025] The first generator is provided with a first pipeline, the liquid inlet of the first pipeline is connected to the outlet of the pressure reducing device, the liquid outlet of the first pipeline is connected to the second refrigeration unit, and the first generator can cool the regenerated decarbonization solution and make the regenerated decarbonization solution flow to the second refrigeration unit;

[0026] The first condenser is connected between the first generator and the first evaporator, and is used to cool the refrigerant of the first refrigeration unit and transport it to the first evaporator;

[0027] The first evaporator is connected between the first condenser and the first absorber, and the first evaporator is provided with a second pipeline, the inlet of the second pipeline is connected to the cold water tank, and the first evaporator can cool the circulating water and make the circulating water flow to the second refrigeration unit;

[0028] The first absorber is connected between the first evaporator and the first generator, and is used to cool the refrigerant of the first refrigeration unit and transport it to the first generator.

[0029] In one embodiment, the second refrigeration unit includes a second generator, a second absorber, a second evaporator and a second condenser;

[0030] The second generator is provided with a third pipeline, the liquid inlet of the third pipeline is connected to the outlet of the first pipeline, the liquid outlet of the third pipeline is connected to the absorption tower, and the second generator can cool the regenerated decarbonization solution and make the regenerated decarbonization solution flow to the absorption tower;

[0031] The second condenser is connected between the second generator and the second evaporator, and is used to cool the refrigerant of the second refrigeration unit and transport it to the second evaporator;

[0032] The second evaporator is connected between the second condenser and the second absorber, and the second evaporator is provided with a fourth pipeline, the inlet of the fourth pipeline is connected with the outlet of the second pipeline, and the second evaporator can cool the circulating water and transport the circulating water to an external device;

[0033] The second absorber is connected between the second evaporator and the second generator, and is used to cool the refrigerant of the second refrigeration unit and transport it to the second generator.

[0034] In one embodiment, a second regeneration tower is further included, wherein the inlet of the second regeneration tower is connected to the decompression device to receive the partially vaporized regenerated decarbonization solution, and the second regeneration tower is used to remove carbon dioxide from the regenerated decarbonization solution;

[0035] A delivery pump is connected to the outlet of the absorption tower and the outlet of the second regeneration tower respectively, and the delivery pump can deliver the solution at the outlet of the absorption tower and the outlet of the second regeneration tower to the first regeneration tower.

[0036] In one embodiment, it also includes a first water cooler, the inlet of which is connected to the pressure reducing device, and the first water cooler can receive the pressurized regenerated decarbonization solution and is used to cool the regenerated decarbonization solution; the outlet of the first water cooler is connected to the absorption tower so that the cooled regenerated decarbonization solution flows to the absorption tower.

[0037] In one embodiment, the three-way valve has three communication ports, and the three communication ports are respectively connected to the outlet of the pressure reducing device, the first refrigeration unit and the inlet of the first water cooler.

[0038] In one embodiment, a first switch valve is connected between the pressure reducing device and the first water cooler, and the first switch valve is configured to control the conduction and cutoff of the pipeline between the pressure reducing device and the first water cooler.

[0039] In one embodiment, a second switch valve is connected between the pressure reducing device and the first refrigeration unit, and the second switch valve is configured to control the conduction and cutoff of the pipeline between the pressure reducing device and the first refrigeration unit.

[0040] It can be seen from the above technical solution that the advantages and positive effects of the present invention are:

[0041] The present application provides a waste heat recovery system for a decarbonization process, which includes an absorption tower, a first regeneration tower, a pressure reducing device, a cold water tank, a first refrigeration unit, and a second refrigeration unit. The waste heat of the regenerated decarbonization solution generated by the first regeneration tower is used as a driving heat source for the first refrigeration unit, thereby cooling the regenerated decarbonization solution for the first time, and at the same time, the circulating water in the cold water tank can be heat exchanged with the first refrigeration unit to obtain cooled circulating water; further, the regenerated decarbonization solution continues to flow to the second refrigeration unit and is cooled for the second time in the second refrigeration unit, wherein the second refrigeration unit can further fully recover the low-level heat energy of the regenerated decarbonization solution that has been cooled once as a driving heat source for the second refrigeration unit, so that the regenerated decarbonization solution can be further cooled in the second refrigeration unit, and at the same time, the circulating water of the second refrigeration unit to which the first refrigeration unit flows can also be further cooled by heat exchange with the second refrigeration unit. In this way, after two gradient coolings by the first refrigeration unit and the second refrigeration unit, the decarbonization solution can have a lower temperature, thereby carrying out a more efficient carbon dioxide absorption process in the decarbonization tower. At the same time, the circulating water that has been heat exchanged and cooled with the first refrigeration unit and the second refrigeration unit can be transported to subsequent external equipment, and the circulating water can be used in subsequent synthesis processes that require cooling. Not only can the low-level thermal energy of the regenerated decarbonization solution be fully utilized, but also low-temperature circulating water can be provided for subsequent synthesis processes, reducing the overall process cooling water consumption of external equipment and achieving energy saving and efficiency improvement of the entire process. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 It is a schematic diagram of the waste heat recovery system of the decarbonization process in the present invention.

[0043] Figure 2 is a schematic diagram of the first refrigeration unit in the present invention;

[0044] Figure 3 It is a schematic diagram of the second refrigeration unit in the present invention.

[0045] The following are the descriptions of the reference numerals:

[0046] 1. Absorption tower; 2. First regeneration tower; 3. Pressure reducing device;

[0047] 4. First refrigeration unit; 41. First generator; 42. First absorber; 43. First evaporator; 44. First condenser; 45. First pipeline; 46. Second pipeline; 47. First solution heat exchanger; 48. First steam heat exchanger;

[0048] 5. Second refrigeration unit; 51. Second generator; 52. Second absorber; 53. Second evaporator; 54. Second condenser; 55. Third pipeline; 56. Fourth pipeline; 57. Second solution heat exchanger; 58. Second steam heat exchanger;

[0049] 6. The first water cooler;

[0050] 7. Second water cooler;

[0051] 8. Injector. DETAILED DESCRIPTION

[0052] Although the present invention can be easily embodied in different forms of embodiments, only some of the specific embodiments are shown in the drawings and will be described in detail in this specification. It should be understood that this description should be regarded as an exemplary illustration of the principles of the invention and is not intended to limit the invention to that described herein.

[0053] Thus, a feature indicated in this specification will be used to illustrate one of the features of an embodiment of the present invention, rather than implying that each embodiment of the present invention must have the described feature. In addition, it should be noted that this specification describes many features. Although some features can be combined together to illustrate possible system designs, these features can also be used in other combinations that are not explicitly described. Thus, unless otherwise stated, the described combinations are not intended to be limiting.

[0054] In the description of this application, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection, an electrical connection, or mutual communication; it can be a direct connection, or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0055] There are many existing decarbonization technologies. Different materials and different methods of producing syngas have different decarbonization process options. Among them, the modified hot potash method (Benzene Field method) belongs to the chemical absorption method, using diethanolamine as the activator. The industry uses ejector flash technology and voltage-switching regeneration energy-saving technology. This process is relatively mature and has certain advantages in energy saving and consumption reduction. Therefore, the Benfield method is currently a more commonly used decarbonization method at home and abroad.

[0056] However, in the current decarbonization system, there is still a large amount of low-level heat energy that has not been utilized, such as low-level heat from transformers and waste heat from lean liquid. Since these waste heat from transformers and waste heat from lean liquid are of low quality and inconvenient to use, they are not fully developed and utilized at present. Therefore, it is necessary to effectively utilize these low-level heat energies to achieve further energy conservation and environmental protection in the decarbonization process.

[0057] Therefore, the present invention provides a waste heat recovery system for the decarbonization process, which can fully recycle and utilize these low-level thermal energies.

[0058] The first embodiment of the waste heat recovery system for decarbonization process

[0059] Figure 1 The schematic diagram of the waste heat recovery system of the decarbonization process in this embodiment is shown. Figure 1 The waste heat recovery system of the decarbonization process includes an absorption tower 1, a first regeneration tower 2, a pressure reducing device 3, a cold water tank (not shown in the figure), a first refrigeration unit 4 and a second refrigeration unit 5.

[0060] The absorption tower 1 is used to receive the generated gas containing carbon dioxide and perform decarbonization. A decarbonization solution for absorbing carbon dioxide gas can be provided in the absorption tower 1. Then, carbon dioxide in the generated gas is removed. In this way, the generated gas after carbon dioxide removal can be transported to the next process for reaction, so as to avoid carbon dioxide affecting the synthesis process of the next process.

[0061] The decarbonation solution may include a potassium carbonate solution, and the reaction equation for potassium carbonate absorbing carbon dioxide is as follows:

[0062] K 2 CO 3 +H 2 O+CO 2 →2KHCO 3 .

[0063] The first regeneration tower 2 is connected to the absorption tower 1 and is used to receive the solution in the absorption tower 1 and remove the carbon dioxide in the solution to obtain a regenerated decarbonation solution and carbon dioxide.

[0064] Among them, since the decarbonization solution absorbs carbon dioxide in the generated gas in the absorption tower 1 to generate a solution rich in carbon dioxide, the carbon dioxide rich solution can be transported to the first regeneration tower 2. The first regeneration tower 2 removes carbon dioxide from the solution to obtain a regenerated decarbonization solution. The regenerated decarbonization solution can be transported to the absorption tower 1 again to absorb carbon dioxide to achieve the purpose of reuse.

[0065] Specifically, the regeneration tower can desorb carbon dioxide from the decarbonized solution by controlling specific process conditions (such as temperature, pressure, etc.), thereby achieving regeneration of the solution. The regenerated decarbonized solution can be recycled, thereby improving resource utilization. At the same time, the removed carbon dioxide can be collected by the ejector 9.

[0066] The reaction equation for removing carbon dioxide from the solution is as follows:

[0067] 2KHCO 3 →K 2 CO 3 +H 2 O+CO2 .

[0068] After removing carbon dioxide from the solution, a regenerated decarbonization solution is obtained, and the regenerated decarbonization solution includes a potassium carbonate solution, wherein the concentration of potassium carbonate in the potassium carbonate solution can be 25% to 28%.

[0069] That is, the potassium carbonate solution in the absorption tower 1 absorbs carbon dioxide to generate a potassium bicarbonate solution, and the potassium bicarbonate solution enters the first regeneration tower 2 for decarbonization and regeneration, so that the potassium bicarbonate is decomposed into potassium carbonate and carbon dioxide. At this time, the potassium carbonate solution obtained restores its ability to absorb carbon dioxide, and the potassium carbonate solution is effectively regenerated.

[0070] The pressure reducing device 3 is connected to the first regeneration tower 2, and the pressure reducing device 3 can be used to receive the regenerated decarbonization solution and reduce the pressure of the regenerated decarbonization solution.

[0071] The pressure reducing device 3 reduces the pressure of the regenerated decarbonization solution. Due to the pressure reduction, the solute in the regenerated decarbonization solution, that is, carbon dioxide, can be reduced in solubility and precipitated. When the solution flows through the pressure reducing device 3, since the pressure in the device is lower than the original pressure of the solution, the carbon dioxide and other gases in the solution will be quickly released, which is conducive to further removing the carbon dioxide gas in the regenerated decarbonization solution.

[0072] Specifically, the decompression device 3 is a flash tank, which utilizes the difference in saturated vapor pressure of a substance under different pressures to rapidly evaporate the liquid substance by reducing the pressure, thereby achieving the conversion of the liquid into a gaseous state.

[0073] Furthermore, the waste heat recovery system of the decarbonization process may include a pressurized conveying device to convey the regenerated decarbonization solution vaporized in the flash tank to subsequent equipment. The pressurized conveying device is arranged downstream of the decompression device 3 .

[0074] The first refrigeration unit 4 is connected to the cold water tank and the pressure reducing device 3 respectively to receive the circulating water and the regenerated decarbonization solution after pressure reduction. The first refrigeration unit 4 can use the regenerated decarbonization solution as a driving heat source to cool the regenerated decarbonization solution to a first preset temperature and cool the circulating water to a second preset temperature.

[0075] Specifically, the first refrigeration unit 4 is an absorption refrigeration unit.

[0076] The first refrigeration unit 4 includes a first generator 41 , a first absorber 42 , a first evaporator 43 and a first condenser 44 .

[0077] The first generator 41 is provided with a first pipeline 45 , the liquid inlet of the first pipeline 45 is connected to the outlet of the pressure reducing device 3 , and the liquid outlet of the first pipeline 45 is connected to the second refrigeration unit 5 . The first generator 41 can cool the regenerated decarbonization solution and make the regenerated decarbonization solution flow to the second refrigeration unit 5 .

[0078] The regenerated decarbonization solution is transported to the first generator 41 through the first pipeline 45, and the regenerated decarbonization solution exchanges heat with the refrigerant of the first refrigeration unit 4. The refrigerant absorbs the heat of the regenerated decarbonization solution and evaporates, so that the regenerated decarbonization solution is cooled to a first preset temperature and flows to the second refrigeration unit 5 through the outlet of the first pipeline 45 for secondary cooling, while the steam absorbent flows to the condenser.

[0079] The first condenser 44 is connected between the first generator 41 and the first evaporator 43 . The first condenser 44 is used to cool the refrigerant of the first refrigeration unit 4 and transport the refrigerant to the first evaporator 43 .

[0080] In the first condenser 44 , the refrigerant can be condensed from a vapor state to a liquid state under high pressure. A heat exchange circulating fluid can be provided in the first condenser 44 . When the heat exchange circulating fluid flows through the first condenser 44 , it can absorb the heat of the refrigerant, thereby cooling the refrigerant. The cooled refrigerant can flow to the first evaporator 43 .

[0081] The first evaporator 43 can be connected between the first condenser 44 and the first absorber 42 . The first evaporator 43 is provided with a second pipe 46 . The inlet of the second pipe 46 is connected to the cold water tank. The first evaporator 43 can cool the circulating water and make the circulating water flow to the second refrigeration unit 5 .

[0082] The first evaporator 43 can receive the liquid refrigerant from the first condenser 44, and the circulating water in the cold water tank can flow in the second pipe 46 in the first evaporator 43. The liquid refrigerant cooled by the first condenser 44 exchanges heat with the circulating water. The liquid refrigerant absorbs the heat of the circulating water and then evaporates, and the circulating water can be further cooled. The cooled circulating water can flow to the second refrigeration unit 5 for secondary cooling.

[0083] The first absorber 42 is connected between the first evaporator 43 and the first generator 41 . The first absorber 42 is used to cool the refrigerant of the first refrigeration unit 4 and transport the refrigerant to the first generator 41 .

[0084] The first absorber 42 can receive refrigerant vapor from the first evaporator 43 and mix it with the absorbent concentrated solution from the first generator 41. During the mixing process, the vapor is absorbed by the absorbent concentrated solution to form a dilute absorbent solution, and heat is released in the process. When the heat exchange circulating fluid flows through the first absorber 42, it can absorb the heat generated in the process.

[0085] The second refrigeration unit 5 is connected to the first refrigeration unit 4 to receive the regenerated decarbonization solution and circulating water. The second refrigeration unit 5 can use the regenerated decarbonization solution after cooling by the first refrigeration unit 4 as a driving heat source to cool the regenerated decarbonization solution from the first preset temperature to the third preset temperature, and cool the circulating water to the fourth preset temperature; wherein the second refrigeration unit 5 is connected to the absorption tower 1 to transport the regenerated decarbonization solution to the absorption tower 1, and the second refrigeration unit 5 is also used to be connected to external equipment to transport circulating water.

[0086] Specifically, the second refrigeration unit 5 is an absorption refrigeration unit.

[0087] The second refrigeration unit 5 includes a second generator 51 , a second absorber 52 , a second evaporator 53 and a second condenser 54 .

[0088] The second generator 51 is provided with a third pipeline 55 , the liquid inlet of the third pipeline 55 is connected to the outlet of the first pipeline 45 , and the liquid outlet of the third pipeline 55 is connected to the absorption tower 1 . The second generator 51 can cool the regenerated decarbonization solution and make the regenerated decarbonization solution flow to the absorption tower 1 .

[0089] Among them, the regenerated decarbonization solution after the first cooling by the first refrigeration unit 4 can be transported to the second generator 51 through the third pipeline 55, and the regenerated decarbonization solution exchanges heat with the refrigerant of the second refrigeration unit 5. The refrigerant absorbs the heat of the regenerated decarbonization solution and evaporates, so that the regenerated decarbonization solution can be cooled for a second time in the second generator 51, from the first preset temperature to the third preset temperature, and then flow to the absorption tower 1 through the outlet of the third pipeline 55, and then a more efficient carbon dioxide absorption process is carried out in the decarbonization tower.

[0090] The second condenser 54 is connected between the second generator 51 and the second evaporator 53 . The second condenser 54 is used to cool the refrigerant of the second refrigeration unit 5 and transport it to the second evaporator 53 .

[0091] In the second condenser 54 , the refrigerant can be condensed from a vapor state to a liquid state under high pressure. A heat exchange circulating fluid can be provided in the second condenser 54 . When the heat exchange circulating fluid flows through the second condenser 54 , it can absorb the heat of the refrigerant, thereby cooling the refrigerant. The cooled refrigerant can flow to the second evaporator 53 .

[0092] The second evaporator 53 is connected between the second condenser 54 and the second absorber 52. The second evaporator 53 is provided with a fourth pipe 56. The inlet of the fourth pipe 56 is connected to the outlet of the second pipe 46. The second evaporator 53 can cool the circulating water and transport the circulating water to external equipment.

[0093] Among them, the second evaporator 53 can receive liquid refrigerant from the second condenser 54. The circulating water after the first cooling by the second refrigeration unit 5 can be transported to the second evaporator 53 through the fourth pipe 56. The liquid refrigerant cooled by the second condenser 54 exchanges heat with the circulating water. The liquid refrigerant absorbs the heat of the circulating water and then evaporates, and the circulating water can be further cooled from the second preset temperature to the fourth preset temperature. The further cooled circulating water can be transported to external equipment for use.

[0094] The second absorber 52 is connected between the second evaporator 53 and the second generator 51 . The second absorber 52 is used to cool the refrigerant of the second refrigeration unit 5 and transport the refrigerant to the second generator 51 .

[0095] The second absorber 52 can receive refrigerant vapor from the second evaporator 53 and mix it with the absorbent concentrated solution from the second generator 51. During the mixing process, the vapor is absorbed by the absorbent concentrated solution to form a dilute absorbent solution, releasing heat in the process. When the heat exchange circulating fluid flows through the second absorber 52, it can absorb the heat generated in the process.

[0096] In the waste heat recovery system of the decarbonization process disclosed in the present application, by arranging the first refrigeration unit 4 and the second refrigeration unit 5 in series, and using the waste heat of the reduced-pressure regenerated decarbonization solution as the driving heat source of the first refrigeration unit 4 and the second refrigeration unit 5, not only the temperature of the regenerated decarbonization solution can be reduced, but also the temperature of the circulating water that exchanges heat with the first refrigeration unit 4 and the second refrigeration unit 5 can be further cooled. In this way, the cooled circulating water can be used in subsequent synthesis processes that require cooling. Not only can the low-level thermal energy of the regenerated decarbonization solution be fully utilized, but also low-temperature circulating water can be provided for subsequent synthesis processes, thereby reducing the overall process cooling water consumption of external equipment and achieving energy saving and efficiency improvement of the entire process.

[0097] It should be noted that since the low-level heat energy in the regenerated decarbonization solution is not easy to utilize, the present application sets the first refrigeration unit 4 and the second refrigeration unit 5 in series, and the first refrigeration unit 4 and the second refrigeration unit 5 are both absorption refrigeration units, so that the low-level heat energy in the regenerated decarbonization solution can be utilized. In addition, two different refrigeration units, namely the first refrigeration unit 4 and the second refrigeration unit 5, are set up, and the second refrigeration unit 5 can further utilize the low-level heat energy after the first refrigeration unit 4 is cooled, and then continue to reduce the temperature of the regenerated decarbonization solution. In this way, after the first refrigeration unit 4 and the second refrigeration unit 5 are cooled twice, the decarbonization process waste heat recovery system of the present application can fully recover and utilize the low-level heat energy in the regenerated decarbonization solution, so that the first decarbonization solution flowing to the decarbonization tower has a lower temperature, and then a more efficient carbon dioxide absorption process is carried out in the decarbonization tower. The generated gas after decarbonization by the decarbonization tower is used in subsequent production equipment, which can significantly improve the synthesis efficiency. At the same time, the circulating water having a lower temperature after secondary heat exchange and cooling by the first refrigeration unit 4 and the second refrigeration unit 5 can be transported to subsequent external equipment, which not only reduces the overall process cooling water consumption of the external equipment, but also achieves energy saving and efficiency improvement of the entire process.

[0098] In some embodiments, the external device is configured as a synthetic ammonia device (not shown in the figure) of a synthetic ammonia system, and the second refrigeration machine 5 group delivers circulating water to the synthetic ammonia device.

[0099] Specifically, the waste heat recovery system of the decarbonization process of the present application can be applied to the preparation system of synthetic ammonia, and the circulating water after secondary heat exchange and cooling by the first refrigeration unit 4 and the second refrigeration unit 5 can be transported to the synthetic ammonia equipment. Among them, the circulating water can reduce the temperature of the raw gas, thereby reducing the ammonia cold separation temperature, thereby increasing the synthetic ammonia output.

[0100] In some embodiments, the absorption tower 1 receives the product gas generated by the conversion process of the synthetic ammonia system, and transports the product gas after the carbon dioxide is removed to the synthetic ammonia equipment.

[0101] Specifically, in the preparation system of synthetic ammonia, its production process includes: desulfurization, conversion, transformation, decarbonization, methanation, ammonia synthesis, absorption refrigeration, and input into ammonia reservoir and ammonia absorption. The absorption tower 1 of the waste heat recovery system of the decarbonization process in the present application can receive the generated gas generated from the end of the transformation process, and can use potassium carbonate to absorb the carbon dioxide in the generated gas, and then transport it to the synthetic ammonia equipment as the raw gas for the synthetic ammonia reaction. Among them, by utilizing the first refrigeration unit 4 and the second refrigeration unit 5 arranged in series to fully utilize the heat of the regenerated decarbonization solution to cool the regenerated decarbonization solution, the decarbonization efficiency in the decarbonization tower and the purity of the generated gas can be improved, thereby improving the efficiency and output of synthetic ammonia.

[0102] Furthermore, the absorption tower 1 receives the generated gas generated in the shift process. The generated gas containing carbon dioxide has a large amount of heat since it flows out in the shift process. Before entering the absorption tower 1, the generated gas can be passed through the low-shift gas boiler 10 to exchange heat with the liquid in the low-shift gas boiler 10.

[0103] In some embodiments, the first refrigeration unit 4 further includes a first solution heat exchanger 47 and a first steam heat exchanger 48 .

[0104] The first solution heat exchanger 47 can be connected to the first generator 41 and the first absorber 42 respectively. After the mixed working fluid solution formed by the mixture of the refrigerant and the absorbent absorbs the heat of the regenerated decarbonization solution, the refrigerant therein vaporizes to generate refrigerant vapor and forms a mixed working fluid concentrated solution, which is then transported from the first generator 41 to the first solution heat exchanger 47 for heat exchange and cooling, and the cooled mixed working fluid concentrated solution is transported to the first absorber 42.

[0105] The first steam heat exchanger 48 can be connected to the first generator 41 and the first absorber 42 respectively. The mixed working fluid dilute solution formed by the first absorber 42 can flow to the first solution heat exchanger 47 and the first steam heat exchanger 48 respectively, and the mixed working fluid dilute solution after heat exchange and temperature reduction in the first steam heat exchanger 48 can continue to flow to the first generator 41, so that the mixed working fluid solution can be circulated.

[0106] In some embodiments, the second refrigeration unit 5 further includes a second solution heat exchanger 57 and a second steam heat exchanger 58 .

[0107] The second solution heat exchanger 57 can be connected to the second generator 51 and the second absorber 52 respectively. After the mixed working fluid solution formed by the mixture of the refrigerant and the absorbent absorbs the heat of the regenerated decarbonization solution, the refrigerant therein vaporizes to generate refrigerant vapor and forms a mixed working fluid concentrated solution, which is then transported from the second generator 51 to the second solution heat exchanger 57 for heat exchange and cooling, and the cooled mixed working fluid concentrated solution is transported to the second absorber 52.

[0108] The second steam heat exchanger 58 can be connected to the second generator 51 and the second absorber 52 respectively. The mixed working fluid dilute solution formed by the second absorber 52 can flow to the second solution heat exchanger 57 and the second steam heat exchanger 58 respectively, and the mixed working fluid dilute solution after heat exchange and temperature reduction in the second steam heat exchanger 58 can continue to flow to the second generator 51, so that the mixed working fluid solution can be circulated.

[0109] In some embodiments, the refrigerant of the first refrigeration unit 4 includes water, and the absorbent of the first refrigeration unit 4 includes at least one of calcium chloride, lithium nitrate, or potassium formate. By using at least one of calcium chloride, lithium nitrate, or potassium formate as the absorbent of the first refrigeration unit 4, the regeneration decarbonization solution having a temperature of 105° C. to 115° C. in the synthetic ammonia decarbonization process can be fully utilized.

[0110] Specifically, compared with the traditional absorption refrigeration technology using lithium bromide as an absorbent, water-lithium bromide has the problems of strong corrosiveness, easy crystallization and poor refrigeration effect. The first refrigeration unit 4 in the present application uses at least one of calcium chloride, lithium nitrate or potassium formate as an absorbent, wherein calcium chloride can effectively reduce the system blockage and performance degradation caused by solution crystallization. Moreover, the absorbent used in the first refrigeration unit 4 is relatively less corrosive to the equipment, which is also conducive to extending the service life of the equipment.

[0111] In some embodiments, the absorbent of the first refrigeration unit 4 includes calcium chloride and lithium nitrate, the content of calcium chloride is 70wt% to 90wt%, and the content of lithium nitrate is 10wt% to 30wt%.

[0112] In some embodiments, the absorbent of the first refrigeration unit includes calcium chloride and potassium formate, the content of calcium chloride is 70wt% to 90wt%, and the content of potassium formate is 10wt% to 30wt%.

[0113] In some embodiments, the absorbent of the first refrigeration unit 4 contains 75 wt % to 85 wt % of calcium chloride, 8 wt % to 10 wt % of lithium nitrate and 5 wt % to 10 wt % of potassium formate.

[0114] Among them, calcium chloride as the main component can make the absorbent have good thermal stability and chemical stability, and can effectively absorb refrigerant vapor. Moreover, the addition of lithium nitrate or potassium formate helps to improve the corrosiveness of the solution and the stability of the crystallization temperature, thereby further optimizing the refrigeration effect.

[0115] In some embodiments, the refrigerant of the second refrigeration unit 5 includes ethylene oxide, and the absorbent of the second refrigeration unit 5 includes an amino acid type ionic liquid.

[0116] Specifically, since the first refrigeration unit 4 uses the low-level heat energy of the regenerated decarbonization solution at 105°C to 115°C to cool the regenerated decarbonization solution, in order to continue to use the low-level heat energy of the regenerated decarbonization solution after cooling and further cool it, the refrigerant of the second refrigeration unit 5 uses ethylene oxide. Among them, ethylene oxide, as a low-boiling point, high-vapor pressure refrigerant, has excellent refrigeration performance. Moreover, the second refrigeration unit uses amino acid-type ionic liquid as an absorbent. The amino acid-type ionic liquid can effectively absorb ethylene oxide vapor and release heat during the regeneration process, providing continuous refrigeration capacity for the system. In addition, the environmental friendliness and recyclability of the amino acid-type ionic liquid also meet the current environmental protection requirements.

[0117] In this way, the second refrigeration unit 5 uses ethylene oxide and the absorbent uses amino acid type ionic liquid, which can further tap the lower temperature low-level heat energy in the regenerated decarbonization solution that cannot be utilized by the first refrigeration unit 4.

[0118] In some embodiments, the cation in the amino acid-type ionic liquid includes at least one of a quaternary ammonium cation and an imidazolium cation.

[0119] Among them, quaternary ammonium cations have good thermal and chemical stability, and can maintain structural stability under high temperature and strong acid and alkali environments. Imidazole cations have excellent solubility and coordination ability, and can form stable ionic liquids with a variety of anions. By selecting at least one of these two cations, amino acid ionic liquids can have stable performance and efficient refrigeration capacity during the refrigeration process.

[0120] In some embodiments, the anions in the amino acid type ionic liquid include at least one of glutamic acid, glycine, and proline ions. Glutamic acid, glycine, and proline ions have good thermal stability and chemical stability, so that they can form tight ion pairs with cations during the refrigeration process, thereby effectively absorbing and releasing heat, thereby improving the refrigeration efficiency and stability of the amino acid type ionic liquid.

[0121] In some embodiments, the circulating water in the cold water tank is configured as desalted water.

[0122] It should be noted that desalted water is water that has been desalted, and the soluble salts (such as sodium chloride, calcium chloride, etc.) in the water have been mostly or completely removed. In the waste heat recovery system of the decarbonization process, desalted water is used as the circulating water in the cold water tank. Since the salt content in the desalted water is extremely low, its corrosiveness to the system equipment and pipelines is greatly reduced. The use of desalted water can reduce the corrosion risk of equipment and pipelines, thereby improving the stability and reliability of the entire waste heat recovery system.

[0123] On the other hand, the presence of salt in water will affect the thermal conductivity of water. The use of desalted water can ensure that the circulating water in the system has a higher thermal conductivity, thereby improving the thermal efficiency of the entire waste heat recovery system.

[0124] In some embodiments, the waste heat recovery system of the decarbonization process also includes a second regeneration tower 6, the inlet of the second regeneration tower 6 is connected to the pressure reducing device 3 to receive partially vaporized regenerated decarbonization solution, and the second regeneration tower 6 is used to remove carbon dioxide from the regenerated decarbonization solution.

[0125] Specifically, due to the pressure reduction in the pressure reducing device 3, the solute in the regenerated decarbonization solution, that is, carbon dioxide, can be reduced in solubility and precipitated. The top outlet of the pressure reducing device 3 can be connected to the second regeneration tower 6, and then the steam of part of the regenerated decarbonization solution and carbon dioxide gas generated by the pressure reducing device 3 can be transported to the second regeneration tower 6, and the second regeneration tower 6 can further remove carbon dioxide.

[0126] The first regeneration tower 2 may be a pressure regeneration tower, and the second regeneration tower 6 may be a normal pressure regeneration tower.

[0127] In some embodiments, the waste heat recovery system of the decarbonization process also includes a delivery pump, which is respectively connected to the outlet of the absorption tower 1 and the outlet of the second regeneration tower 6, and the delivery pump can deliver the solution at the outlet of the absorption tower 1 and the outlet of the second regeneration tower 6 to the first regeneration tower 2.

[0128] Among them, by setting up a delivery pump, the solutions at the two outlets of the absorption tower 1 and the second regeneration tower 6 can be transported back to the first regeneration tower 2, so as to realize the continuous circulation and regeneration of the solution absorbing carbon dioxide in the waste heat recovery system of the decarbonization process, that is, the decarbonization solution, so that the solution can be efficiently circulated between the absorption tower 1, the second regeneration tower 6 and the first regeneration tower 2.

[0129] In some embodiments, the waste heat recovery system of the decarbonization process also includes a first water cooler 7, the inlet of the first water cooler 7 is connected to the pressure reducing device 3, the first water cooler 7 can receive the pressurized regenerated decarbonization solution and is used to cool the regenerated decarbonization solution; the outlet of the first water cooler 7 is connected to the absorption tower 1 so that the cooled regenerated decarbonization solution flows to the absorption tower 1.

[0130] The first water cooler 7 can receive the pressurized regenerated decarbonization solution from the pressure reducing device 3. The first water cooler 7 uses a cooling medium (such as water) to cool the solution to reduce its temperature and prepare to send it back to the absorption tower 1 for the next cycle.

[0131] Specifically, after the regenerated decarbonization solution is decompressed and flashed in the decompression device 3, it is partially vaporized and releases heat. Subsequently, the solution enters the first water cooler 7 for cooling treatment. The cooled solution flows to the absorption tower 1 through the outlet of the first water cooler 7, ready to absorb carbon dioxide again. In this way, the cooling treatment of the regenerated decarbonization solution by the first water cooler 7 helps to lower the temperature of the solution, thereby improving its ability to absorb carbon dioxide. Moreover, the low-temperature solution can absorb carbon dioxide more effectively in the absorption tower 1, thereby improving the efficiency of the entire decarbonization process.

[0132] It should be noted that the first water cooler 7, the first refrigeration unit 4 and the second refrigeration unit 5 can be adjusted according to actual production needs. For example, the user can choose to use the first water cooler 7 to cool the regenerated decarbonization solution, or can choose the first refrigeration unit 4 and the second refrigeration unit 5 to cool the regenerated decarbonization solution.

[0133] In some embodiments, the waste heat recovery system of the decarbonization process further includes a three-way valve (not shown in the figure). The three-way valve may have three connecting ports. The three connecting ports are respectively connected to the outlet of the pressure reducing device 3, the first refrigeration unit 4 and the inlet of the first water cooler 7. Among them, by setting the three-way valve, the user can flexibly switch the flow direction of the solution according to the needs during the production process to select measures to cool the regenerated decarbonization solution.

[0134] In some embodiments, the waste heat recovery system of the decarbonization process also includes a first switch valve (not shown in the figure). The first switch valve is connected between the pressure reducing device 3 and the first water cooler 7, and the first switch valve is configured to control the conduction and cutoff of the pipeline between the pressure reducing device 3 and the first water cooler 7. In this way, when the system needs to regenerate the decarbonization solution through the first water cooler 7 for cooling treatment, the first switch valve is opened to allow the solution to flow from the pressure reducing device 3 to the first water cooler 7; when the system does not need the first water cooler 7 to process the solution or needs to switch to other processing paths, the first switch valve is closed to cut off the passage of the solution to the first water cooler 7.

[0135] In some embodiments, the waste heat recovery system of the decarbonization process further includes a second switch valve (not shown in the figure). The second switch valve is connected between the pressure reducing device 3 and the first refrigeration unit 4, and the second switch valve is configured to control the conduction and cutoff of the pipeline between the pressure reducing device 3 and the first refrigeration unit 4. When it is necessary to recover the waste heat in the regenerated decarbonization solution, the second switch valve is opened to allow the solution to flow from the pressure reducing device 3 to the first refrigeration unit 4 for energy recovery; when it is not necessary to recover the waste heat or to switch to other processing paths, the second switch valve is closed to cut off the passage of the solution to the first refrigeration unit 4.

[0136] In some embodiments, the waste heat recovery system of the decarbonization process further includes a second water cooler 8. The second water cooler 8 is connected to the top air supply ports of the first regeneration tower 2 and the second regeneration tower 6, respectively, so that the carbon dioxide desorbed from the first regeneration tower 2 and the second regeneration tower 6 can be cooled by the second water cooler 8.

[0137] In some embodiments, the waste heat recovery system for the decarbonization process further includes an ejector 9. The ejector 9 is connected to one side of the liquid inlet end of the second water cooler 8.

[0138] Second embodiment of waste heat recovery system for decarbonization process

[0139] The present invention is described in detail below using specific embodiments.

[0140] Taking a plant's 2×105t / y synthetic ammonia production unit as an example, its Benfield process decarbonization process produces about 125t / h of regenerated decarbonization solution with a temperature of 110°C. It is used as a driving heat source and first introduced into the first refrigeration unit, using the prepared water-calcium chloride / lithium nitrate / potassium formate mixed working fluid. The circulating water contained in the cold water tank is desalted water.

[0141] Based on the water absorption performance of concentration changes and the easy boiling and heat absorption of water under a certain vacuum degree, the heat exchange is cooled to 10℃~13℃ low-temperature desalted water, and then it is passed into the second refrigeration unit. The ethylene oxide / tetraethylammonium amino acid ionic liquid working fluid pair is used to obtain the heat of the 60℃~90℃ temperature zone of the regenerated decarbonized solution, and the low-temperature desalted water is further cooled to about 6℃, and transported to the cold point of the raw gas compression and synthesis section through the storage tank. After the heat exchange in the section, the 18℃ desalted water obtained by heating is returned to the first refrigeration unit, and heat is exchanged again with the mixed working fluid of the two-stage unit under a certain vacuum degree, and the temperature is reduced to 6℃ low-temperature desalted water. The regenerated decarbonized solution is cascaded heat exchanged through this two-stage absorption refrigeration device, replacing the equipment for producing low-temperature desalted water with high-grade thermal energy, and achieving significant benefits of energy saving and consumption reduction.

[0142] Among them, the regenerated decarbonization solution generated from the first regeneration tower has a temperature of about 110°C after flowing out of the pressure reducing device, and then enters the first refrigeration unit and the second refrigeration unit after being pressurized by the booster pump, and cools down to about 60°C. The cooled regenerated decarbonization solution is pumped to the absorption tower and used as a decarbonization solution to absorb carbon dioxide in the generated gas. Furthermore, the decarbonization solution after the absorption tower absorbs carbon dioxide enters the first regeneration tower again to generate a regenerated decarbonization solution again, completing the working cycle.

[0143] The process of transporting low-temperature desalted water to the synthetic ammonia equipment: the low-temperature desalted water at about 6°C coming out of the second refrigeration unit is sent to the semi-water gas heat exchanger and the water cooler of the synthesis system. After heat exchange with the gas, it is heated to about 18°C ​​and sent back to the desalted water tank. It is then pressurized by a pump and enters the absorption refrigeration device to complete the working cycle.

[0144] The regenerated decarbonization solution is sent to the first generator of the first refrigeration unit through a booster pump, and the mixed working fluid water - calcium chloride / lithium nitrate / potassium formate is heated inside it, and the water is continuously heated and evaporated. The obtained water vapor passes through the partition and enters the first condenser of the device, where it exchanges heat with the circulating cooling water and condenses to obtain refrigerant water. The obtained refrigerant water is sent to the first evaporator of the device for spraying, and continuously evaporates under a certain vacuum degree, absorbing the heat of the desalted water through the tube wall, lowering its temperature, and obtaining low-temperature desalted water of about 12°C. Then it is pumped into the second refrigeration unit, continues to exchange heat and cool to 6°C, and then sent to the cold points of each section of synthetic ammonia. After evaporation, the refrigerant water vapor or ethylene oxide vapor enters the absorber in the device and is absorbed by the relatively concentrated mixed working fluid solution being sprayed, reducing the concentration of the spray solution. The heat of solution absorbed by the concentrated solution in the absorption of water vapor or ethylene oxide vapor is absorbed by the circulating water and taken out of the device.

[0145] In summary, according to the liquid density of the regenerated decarbonization solution of 1.15×10 3 kg / m 3 , specific heat capacity 3.05kJ / (kg·K), the inlet and outlet temperatures of the heat exchange circulating fluid are 30℃ and 35℃, and the flow rate of the heat exchange circulating fluid is 750m 3 / h, specific heat capacity 4.20 kJ / (kg·K), the efficiency of the first refrigeration unit and the second refrigeration unit are approximately 0.65 and 0.8 respectively, and the heat release of the desalted water refrigeration process is calculated to be 4.975×10 6 kJ / h, and the flow rate of low-temperature desalted water is 415t / h. Taking the ammonia cold separation temperature as an example, the ammonia temperature is 8℃, the gas ammonia temperature is 5℃, and the outlet pressure is 28MPa. According to the start-up time of 350 days per year, the increase in synthetic ammonia production is about 210t / y.

[0146] Although the present invention has been described with reference to several typical embodiments, it should be understood that the terms used are illustrative and exemplary, rather than restrictive. Since the present invention can be embodied in a variety of forms without departing from the spirit or essence of the invention, it should be understood that the above embodiments are not limited to any of the foregoing details, but should be interpreted broadly within the spirit and scope defined by the appended claims, so all changes and modifications falling within the scope of the claims or their equivalents should be covered by the appended claims.

Claims

1. A waste heat recovery system for a decarbonization process, characterized in that: include: An absorption tower, which is used to receive the generated gas containing carbon dioxide and perform decarbonization treatment; the absorption tower is provided with a decarbonization solution for absorbing carbon dioxide gas; A first regeneration tower connected to the absorption tower; the first regeneration tower is used to receive the solution in the absorption tower and remove carbon dioxide from the solution to obtain a regenerated decarbonation solution and carbon dioxide; A decompression device, connected to the first regeneration tower, for receiving the regenerated decarbonization solution and decompressing it; A cold water tank for containing circulating water; a first refrigeration unit, connected to the cold water tank and the pressure reducing device respectively to receive the circulating water and the regenerated decarbonization solution, wherein the first refrigeration unit can use the regenerated decarbonization solution as a driving heat source to cool the regenerated decarbonization solution to a first preset temperature and cool the circulating water to a second preset temperature; a second refrigeration unit connected to the first refrigeration unit to receive the regenerated decarbonization solution and circulating water, the second refrigeration unit being capable of using the regenerated decarbonization solution cooled by the first refrigeration unit as a driving heat source to cool the regenerated decarbonization solution from the first preset temperature to the third preset temperature, and the circulating water to the fourth preset temperature; The second refrigeration unit is connected to the absorption tower to transport the regenerated decarbonization solution to the absorption tower, and the second refrigeration unit is also used to connect to external equipment to transport circulating water.

2. The waste heat recovery system for decarbonization process according to claim 1 is characterized in that: The external device is configured as a synthetic ammonia device of a synthetic ammonia system, and the second refrigeration unit delivers circulating water to the synthetic ammonia device; The absorption tower receives the product gas generated by the conversion process of the synthetic ammonia system, and transports the product gas after the carbon dioxide is removed to the synthetic ammonia equipment.

3. The waste heat recovery system for decarbonization process according to claim 1 is characterized in that: The refrigerant of the first refrigeration unit includes water, and the absorbent of the first refrigeration unit includes at least one of calcium chloride, lithium nitrate or potassium formate; The refrigerant of the second refrigeration unit includes ethylene oxide, and the absorbent of the second refrigeration unit includes amino acid type ionic liquid.

4. The waste heat recovery system for decarbonization process according to claim 3 is characterized in that: The cations in the amino acid type ionic liquid include at least one of quaternary ammonium type cations and imidazole type cations; The anions in the amino acid type ionic liquid include at least one of glutamic acid, glycine and proline ions.

5. The waste heat recovery system for decarbonization process according to claim 3 is characterized in that: The absorbent of the first refrigeration unit comprises calcium chloride and lithium nitrate, wherein the content of the calcium chloride is 70wt% to 90wt%, and the content of the lithium nitrate is 10wt% to 30wt%; or The absorbent of the first refrigeration unit comprises calcium chloride and potassium formate, wherein the content of the calcium chloride is 70wt% to 90wt%, and the content of the potassium formate is 10wt% to 30wt%; or The absorbent of the first refrigeration unit contains 75wt% to 85wt% of calcium chloride, 8wt% to 10wt% of lithium nitrate and 5wt% to 10wt% of potassium formate.

6. The waste heat recovery system for decarbonization process according to claim 1, characterized in that: The decarbonation solution comprises a potassium carbonate solution; and / or The regeneration decarbonization solution comprises a potassium carbonate solution; and / or The circulating water contained in the cold water tank is configured as desalted water.

7. The waste heat recovery system for decarbonization process according to claim 1, characterized in that: The first refrigeration unit includes a first generator, a first absorber, a first evaporator and a first condenser; The first generator is provided with a first pipeline, the liquid inlet of the first pipeline is connected to the outlet of the pressure reducing device, the liquid outlet of the first pipeline is connected to the second refrigeration unit, and the first generator can cool the regenerated decarbonization solution and make the regenerated decarbonization solution flow to the second refrigeration unit; The first condenser is connected between the first generator and the first evaporator, and is used to cool the refrigerant of the first refrigeration unit and transport it to the first evaporator; The first evaporator is connected between the first condenser and the first absorber, and the first evaporator is provided with a second pipeline, the inlet of the second pipeline is connected to the cold water tank, and the first evaporator can cool the circulating water and make the circulating water flow to the second refrigeration unit; The first absorber is connected between the first evaporator and the first generator, and is used to cool the refrigerant of the first refrigeration unit and transport it to the first generator.

8. The waste heat recovery system for decarbonization process according to claim 6, characterized in that: The second refrigeration unit includes a second generator, a second absorber, a second evaporator and a second condenser; The second generator is provided with a third pipeline, the liquid inlet of the third pipeline is connected to the outlet of the first pipeline, the liquid outlet of the third pipeline is connected to the absorption tower, and the second generator can cool the regenerated decarbonization solution and make the regenerated decarbonization solution flow to the absorption tower; The second condenser is connected between the second generator and the second evaporator, and is used to cool the refrigerant of the second refrigeration unit and transport it to the second evaporator; The second evaporator is connected between the second condenser and the second absorber, and the second evaporator is provided with a fourth pipeline, the inlet of the fourth pipeline is connected with the outlet of the second pipeline, and the second evaporator can cool the circulating water and transport the circulating water to an external device; The second absorber is connected between the second evaporator and the second generator, and is used to cool the refrigerant of the second refrigeration unit and transport it to the second generator.

9. The waste heat recovery system for decarbonization process according to claim 1, characterized in that: It also includes a second regeneration tower, the inlet of which is connected to the pressure reducing device to receive the partially vaporized regenerated decarbonization solution, and the second regeneration tower is used to remove carbon dioxide from the regenerated decarbonization solution; A delivery pump is connected to the outlet of the absorption tower and the outlet of the second regeneration tower respectively, and the delivery pump can deliver the solution at the outlet of the absorption tower and the outlet of the second regeneration tower to the first regeneration tower.

10. The waste heat recovery system for decarbonization process according to claim 1, characterized in that: It also includes a first water cooler, the inlet of which is connected to the pressure reducing device, and the first water cooler can receive the pressurized regenerated decarbonization solution and is used to cool the regenerated decarbonization solution; the outlet of the first water cooler is connected to the absorption tower so that the cooled regenerated decarbonization solution flows to the absorption tower.

11. The waste heat recovery system for decarbonization process according to claim 10, characterized in that: Also includes: A three-way valve, the three-way valve having three communication ports, the three communication ports being respectively connected to the outlet of the pressure reducing device, the first refrigeration unit and the inlet of the first water cooler; and / or a first switch valve, the first switch valve being connected between the pressure reducing device and the first water cooler, the first switch valve being configured to control the conduction and cutoff of a pipeline between the pressure reducing device and the first water cooler; and / or A second switch valve, wherein the second switch valve is connected between the pressure reducing device and the first refrigeration unit, and the second switch valve is configured to control the conduction and cutoff of the pipeline between the pressure reducing device and the first refrigeration unit.

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