Sludge drying heat pump unit, heat pump system and its control method

Abstract

The present invention belongs to the technical field of sludge drying treatment heat pump systems, and specifically discloses a sludge drying heat pump unit, a heat pump system and a control method thereof, which includes a low-pressure compressor and a high-pressure compressor arranged on the exhaust side of the low-pressure compressor. The exhaust side of the high-pressure compressor is divided into two branches. One of the branches passes through a sludge condenser and is respectively introduced into a steam source evaporator and an air source evaporator. The steam source evaporator has a first medium side and a second medium side. The first medium side is introduced with a refrigerant working medium, and the second medium side is used for introducing a water vapor medium. The second medium side is used for heating and evaporating the refrigerant medium on the first medium side. The refrigerant outlets of the first medium side of the steam source evaporator and the air source evaporator are connected in parallel to the suction side of the low-pressure compressor. This solution can effectively solve problems such as poor drying effect, breeding of secondary pollution, and difficulty in recovering waste heat in traditional sludge drying systems.

Description

Technical Field

[0001] The present invention belongs to the technical field of sludge drying treatment heat pump systems, and particularly relates to a sludge drying heat pump unit, a heat pump system and a control method thereof. Background Art

[0002] At present, whether it is biological treatment sludge or chemical precipitation sludge, after being treated by mechanical front-end dehydration equipment, the water content of the sludge is still relatively high, and the drying efficiency of the equipment is low. Methods such as plate and frame filter presses, centrifuges, spiral screw presses, high-pressure plate and frame filter presses for dehydration, etc., greatly affect the subsequent external transportation and resource utilization of sludge.

[0003] In related prior arts, sludge drying and dehumidification mainly adopt direct heating methods, that is, using forms such as steam, flue gas, and electric heating to heat the sludge to above 100 °C, so that the water in the sludge becomes water vapor and is directly discharged into the atmosphere. This drying method has problems such as high energy consumption and easy generation of secondary pollution.

[0004] To solve the problems of large energy consumption, high operating cost, environmental pollution, and low drying efficiency in existing sludge drying systems, a low-grade energy low-temperature drying technology has emerged as the times require. The prior art (publication number CN 112062441 A) discloses a sludge low-temperature drying device, which uses a combination of a heat pump cycle and an air cycle, adopts a unique independent air duct technology, has zero emissions and no odor, but the heat energy of gases such as water vapor discharged is not fully utilized. Therefore, how to improve the sludge drying efficiency, make full use of the waste heat of the gases generated by drying, and combine with a heat pump system to achieve efficient energy utilization and waste gas purification has become a key problem that urgently needs to be solved in the sludge drying field. Summary of the Invention

[0005] In order to solve the above problems existing in the prior art, the present solution provides a sludge drying heat pump unit, a heat pump system and a control method thereof. The present solution adopts a staged compression heat pump to recover and utilize the latent heat of water vapor generated by high-temperature dehydration and drying of sludge, uses ambient air heat energy to produce dual-temperature heat energy; uses a saline-alkali solution to absorb water vapor and remove waste gas pollutants such as sulfides or nitrogen oxides; the water vapor generated by the concentration of the saline-alkali solution is cooled to become condensed water for industrial makeup water, effectively solving the problems of poor drying effect, breeding secondary pollution, and difficulty in recovering waste heat in traditional sludge drying systems.

[0006] One of the objectives of the present invention is to provide a sludge drying heat pump unit, which includes a low-pressure compressor and a high-pressure compressor arranged on the exhaust side of the low-pressure compressor. The exhaust side of the high-pressure compressor is divided into two branches. One branch passes through a sludge condenser and then enters a steam-source evaporator and an air-source evaporator respectively. The steam-source evaporator has a first medium side and a second medium side. The first medium side is for introducing a refrigerant working medium, and the second medium side is for introducing a water vapor medium, and the second medium side is used to heat and evaporate the refrigerant medium on the first medium side; the refrigerant outlets of the first medium side of the steam-source evaporator and the air-source evaporator are connected in parallel to the suction side of the low-pressure compressor. The other branch of the exhaust side of the high-pressure compressor is connected to the suction side of the high-pressure compressor again after being connected in series through a solution condenser, a first throttling component, and a solution-source evaporator.

[0007] As a preferred solution, a second throttling component is arranged at the inlet of the first medium side of the steam-source evaporator.

[0008] As a preferred solution, a third throttling component is arranged on the refrigerant inlet side of the air-source evaporator.

[0009] As a preferred solution, an absorber is further included. A spraying component and the solution-source evaporator are arranged in the absorber, and the solution-source evaporator is located below the spraying component; the solution outlet of the absorber is connected to a solution generator through a solution throttling component.

[0010] As a preferred solution, the solution condenser is arranged in the solution generator; the water vapor outlet of the solution generator is connected to the inlet of the second medium side of the steam-source evaporator, and the bottom solution outlet side of the solution generator is connected to the spraying component through a pump.

[0011] Another objective of the present invention is to provide a heat pump system, which includes a sludge tank and the sludge drying heat pump unit described in any one of the above items for providing heat energy to the sludge tank.

[0012] As a preferred solution, the sludge condenser is placed inside the sludge tank, and the steam outlet of the sludge tank is connected to the steam inlet of the absorber.

[0013] A third object of the present invention is to provide a control method for a heat pump system as described above, comprising the following steps: The high-pressure compressor discharges high-temperature and high-pressure superheated gaseous refrigerant working medium at the exhaust side and divides it into two parts. One part of the refrigerant working medium releases condensation heat through the sludge condenser to heat the sludge to realize the sludge dehydration and drying process. The liquid refrigerant condensed by the sludge condenser is throttled and depressurized by the second throttling component and the third throttling component connected in parallel. One-way refrigerant working medium flows into the steam source evaporator to absorb heat and evaporates into refrigerant steam, and the other-way refrigerant working medium flows into the air source evaporator to absorb the heat energy of the external ambient air and evaporates into refrigerant steam. The refrigerant steam at the outlets of the steam source evaporator and the air source evaporator is sucked into the low-pressure compressor to complete the cascade compression process; The other part of the refrigerant working medium enters the solution condenser to release condensation heat to realize the saline-alkali solution concentration and water vapor generation process. Then, this part of the refrigerant working medium is throttled and depressurized by the first throttling component, heated and evaporated into refrigerant steam in the solution source evaporator, and then enters the high-pressure compressor to complete the high compression ratio process.

[0014] As a preferred solution, it further comprises the following steps: The sludge in the sludge tank is heated and dehydrated by the sludge condenser to generate waste gas and water vapor. The waste gas and water vapor enter the absorber and are sprayed and absorbed by the absorption solution. The released absorption heat is recovered by the solution source evaporator. After the waste gas absorption solution enters the solution generator, it is further heated, concentrated and generated by the solution condenser. The concentrated waste gas absorption solution is pumped back to the spraying component to further realize the circulating spraying and utilization of the waste gas absorption solution; The water vapor generated by the solution generator is used to heat the refrigerant on the suction port side of the low-pressure compressor and then condenses into condensed water.

[0015] As a preferred solution, the waste gas absorption solution in the absorber adopts a saline-alkali solution, and the saline-alkali solution is a ternary mixed solution composed of salt, alkali and water.

[0016] Compared with the prior art, the present invention has at least the following beneficial effects:

[0017] First, the present invention provides a novel sludge drying heat pump treatment system. By optimizing the structure of the heat pump unit, a staged compression heat pump unit is adopted to recover the latent heat of the water vapor generated during sludge drying. The refrigerant vapor discharged from the high-pressure compressor is shunted through two branches. The refrigerant working medium passage of one branch is used to heat the sludge pool to achieve sludge dehydration, and then through the steam source evaporator and the air source evaporator, it is used to preheat the refrigerant working medium and complete the cascade compression process of low compression ratio and high compression ratio. The refrigerant working medium passage of the other branch is used to supply the heat required for the generation of the waste gas treatment solution. Then, after throttling and heating by the solution source evaporator, it enters the suction port of the high-pressure compressor to complete the compression process of high compression ratio. The heat pump system of this solution effectively overcomes the problems of poor drying effect, secondary pollution generation, and difficult waste heat recovery in traditional drying systems. This system has the advantages of energy conservation, environmental protection, stability and reliability, and wide application areas, and has broad application prospects.

[0018] Second, the present invention optimizes the sludge drying control method. By using the sludge drying heat pump system with the above structure, the latent heat of the water vapor generated during the high-temperature dehydration drying of sludge is recovered and utilized through the staged compression heat pump. At the same time, the environmental air heat energy is used to produce dual-temperature (high temperature, medium temperature) heat energy to provide the high-temperature heat energy for sludge dehydration drying and the medium-temperature heating amount for saline-alkali solution concentration. By utilizing the hygroscopicity of the saline-alkali solution to water vapor and the absorbability to acidic gases, the recovery and utilization of the absorption heat released by the saline-alkali mixed solution absorbing water vapor, etc. are realized, and at the same time, waste gas pollutants such as sulfides or nitrogen oxides are removed, so as to realize the purification of the pollutants generated during sludge heating and dehydration. The water vapor generated during the concentration of the saline-alkali solution is cooled by the steam source evaporator to release the condensation heat and becomes condensed water as industrial makeup water. The released condensation heat is used to heat the refrigerant for vaporization and recovery, so as to realize the recovery and utilization of the heat and mass of the water vapor generated during sludge dehydration. The sludge treatment method of this solution realizes the improvement of the heat energy grade, realizes the cascade preparation and utilization of heat energy, and simultaneously achieves the dual purposes of purifying the waste gas generated during high-temperature sludge dehydration. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the technical solutions in the embodiments of the invention or the prior art, the following will briefly introduce the drawings required to be used in the description of the embodiments or the prior art. Obviously, the following drawings are only some embodiments of the invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0020] Figure 1 It is a schematic diagram of the principle of the heat pump system of the present invention.

[0021] Markings in the figure: 1. Low-pressure compressor, 2. High-pressure compressor, 3. Sludge condenser, 4. Second throttling component, 5. Steam source evaporator, 51. External pipeline, 6. Third throttling component, 7. Air source evaporator, 8. Solution condenser, 9. First throttling component, 10. Solution source evaporator, 11. Sludge tank, 12. Absorber, 13. Solution generator, 14. Pump, 15. Solution throttling component, 16. Spraying component. Detailed implementation mode

[0022] The present invention will be specifically described below through exemplary implementation modes. However, it should be understood that, without further description, the elements, structures, and features in one implementation mode can also be beneficially combined into other implementation modes.

[0023] It should be noted that: Unless otherwise defined, the technical terms or scientific terms used herein should have the ordinary meaning understood by those with ordinary skills in the field to which the present invention belongs. The words such as "a", "one", or "the" used in the specification and claims of this patent application for the present invention do not express a quantity limitation, but rather indicate that there is at least one. Words such as "including" or "comprising" point out that the elements or objects appearing before "including" or "comprising" cover the elements or objects listed after "including" or "comprising" and their equivalents, but do not exclude other elements or objects with the same functions.

[0024] Embodiment 1

[0025] As Figure 1 shown, this embodiment provides a sludge drying heat pump unit, including a compression heat pump unit and an open absorption heat pump unit. Among them, the compression heat pump unit adopts a two-stage compression unit. The compression heat pump unit provides the high-temperature heating amount required for sludge dehydration and drying and the medium-temperature heating amount required for the concentration and generation of the waste gas absorption solution by producing dual-temperature heat energy, and the open absorption heat pump unit can not only recover the water vapor generated by sludge dehydration through the hygroscopicity of the saline-alkali solution to water vapor and the absorption of acidic gases, but also provide the generated absorption heat to the compression heat pump unit for recycling, and purify the pollutants generated by sludge heating and dehydration by removing waste gas pollutants such as sulfides or nitrogen oxides.

[0026] In a typical embodiment of the present invention, the compression heat pump unit includes a low-pressure compressor 1, a high-pressure compressor 2, a sludge condenser 3, a second throttling component 4, a steam source evaporator 5, a third throttling component 6, an air source evaporator 7, a solution condenser 8, a first throttling component 9, and a solution source evaporator 10.

[0027] In this solution, the high-pressure compressor 2 is arranged on the exhaust side of the low-pressure compressor 1, and the exhaust port of the high-pressure compressor 2 is divided into two branches:

[0028] One branch passes through the solution condenser 8, the first throttling component 9, and the solution source evaporator 10 and then is connected to the suction side of the high-pressure compressor 2 again. The refrigerant channels of the solution condenser 8, the first throttling component 9, and the solution source evaporator 10 are connected in series in sequence. The outlet of the solution source evaporator 10 and the exhaust port of the low-pressure compressor 1 are connected in parallel to the suction port side of the high-pressure compressor 2. The superheated refrigerant vapor discharged from the exhaust port of the high-pressure compressor 2 realizes the concentration and generation of the saline-alkali solution in the solution generator 13 through the solution condenser 8, and the refrigerant vapor condenses into liquid refrigerant inside the solution condenser 8. After the condensed liquid refrigerant is throttled and depressurized by the first throttling component 9, it enters the solution source evaporator 10 to recover the heat of the saline-alkali solution in the absorber 12, thereby vaporizing the liquid refrigerant into gaseous refrigerant, and the gaseous refrigerant directly enters the suction port of the high-pressure compressor 2, thus completing the compression process with a high compression ratio.

[0029] The other branch is respectively connected to the steam source evaporator 5 and the air source evaporator 7 through the sludge condenser 3. The steam source evaporator 5 has a first medium side and a second medium side. The refrigerant working medium is introduced into the first medium side, and the heating medium (steam) is introduced into the second medium side. The second medium side is used to preheat the refrigerant working medium on the first medium side. The first medium side of the steam source evaporator 5 and the refrigerant outlet of the air source evaporator 7 are connected in parallel to the suction side of the low-pressure compressor 1. The outlet of the sludge condenser 3 is divided into two branches, and the two branches are respectively connected to the inlets of the second throttling component 4 and the third throttling component 6. Among them, the outlet of the second throttling component 4 is connected to the inlet of the steam source evaporator 5, the outlet of the steam source evaporator 5 is connected to the suction port of the low-pressure compressor 1, the outlet of the third throttling component 6 is connected to the inlet of the air source evaporator 7, the outlet of the air source evaporator 7 is connected to the suction port of the low-pressure compressor 1, and the exhaust port of the low-pressure compressor 1 is connected to the suction port of the high-pressure compressor 2.

[0030] In this solution, the high-temperature and high-pressure superheated gaseous refrigerant working medium passing through the sludge condenser 3 can heat the sludge, so that the moisture of the sludge evaporates and is discharged into the absorber 12 through the top steam outlet. After the gaseous refrigerant condenses into liquid refrigerant, it is throttled and depressurized respectively by the second throttling component 4 and the third throttling component 6 arranged in parallel, and then flows into the refrigerant channel inside the steam source evaporator 5 through the second throttling component 4, which is used to recover the condensation heat of the water vapor of the open absorption heat pump unit through the refrigerant working medium. After passing through the third throttling component 6, it flows into the refrigerant channel of the air source evaporator 7, thereby absorbing the heat energy of the external ambient air and vaporizing the refrigerant working medium into refrigerant vapor. The refrigerant vapor discharged from the steam source evaporator 5 and the air source evaporator 7 is then sucked into the suction port of the low-pressure compressor 1, thus completing the cascade compression process.

[0031] In this solution, the open absorption heat pump unit includes an absorber 12, a solution generator 13, a pump 14, a solution throttling component 15, and a spraying component 16. The absorber 12 includes a steam inlet, a solution inlet, and a solution outlet. The steam inlet of the absorber 12 is used to connect to the steam outlet of the sludge tank 11. The absorber 12 is used to introduce the water vapor containing waste gas evaporated and separated from the sludge tank 11. A spraying component 16 and a solution source evaporator 10 are arranged in the absorber 12, and the solution source evaporator 10 is located below the spraying component 16. The solution source evaporator 10 is arranged in the absorber 12 and submerged in the saline-alkali mixed solution. The spraying component 16 is used to connect to the solution inlet. Preferably, the steam inlet of the absorber 12 is located on its side wall and below the spraying component 16. The saline-alkali solution sprayed by the spraying component 16 can absorb the water vapor containing acidic waste gas entering from the steam inlet, and at the same time release the absorbed heat. The function of the solution source evaporator 10 is to recover the absorbed heat released in the absorber 12 through the refrigerant working medium introduced into it. After the refrigerant working medium absorbs and recovers the heat, it directly enters the high-pressure compressor 2 to complete the compression process with a high pressure compression ratio. It should be noted that the spraying component 16 includes one or several spray heads.

[0032] In this solution, the solution outlet of the absorber 12 is connected to the solution generator 13 through the solution throttling component 15. The saline-alkali solution sprayed in the absorber 12 absorbs the water vapor from the sludge tank 11. During the process of the saline-alkali solution absorbing the water vapor and pollutants such as sulfides and nitrogen oxides, the absorbed heat released is recovered by the refrigerant working medium passing through the solution source evaporator 10. The recovered heat is used to compress the heat pump unit to produce high-temperature heat energy to provide the heat required for further sludge dewatering and drying. The saline-alkali solution absorbs the water vapor and further becomes a dilute saline-alkali solution, and enters the solution generator 13 for further concentration and occurrence. A solution condenser 8 is arranged in the solution generator 13. Specifically, the solution condenser 8 is arranged in the internal space of the solution generator 13 and submerged in the saline-alkali mixed solution.

[0033] More specifically, the top steam outlet of the solution generator 13 is connected to the inlet of the second medium side of the steam source evaporator 5, and the bottom solution outlet of the solution generator 13 is connected to the spraying component 16 through the pump 14. The solution condenser 8 is used to provide heat for the concentration and occurrence of the dilute saline-alkali solution in the solution generator 13. The water vapor generated by the concentration and occurrence of the dilute saline-alkali solution can be further condensed and recovered through the steam source evaporator 5. The recovered condensed water enters the water collection tank through the external pipeline 51, so as to be further used as industrial make-up water. The concentrated saline-alkali solution will be discharged through the bottom solution outlet of the solution generator 13, and through the circulation of the pump 14, it will be sprayed again through the spraying component 16 and enter the inside of the absorber 12 to complete the cyclic absorption process of the saline-alkali solution and the water vapor with pickling waste gas from the sludge tank 11.

[0034] In this solution, the saline-alkali solution used in the heat pump system refers to a ternary mixed solution composed of salt, alkali and water. The salt is one or more of lithium chloride, calcium chloride, lithium bromide or potassium formate, and the alkali is one or more of sodium hydroxide, potassium hydroxide or calcium hydroxide; the refrigerant working medium is a mixed working medium composed of one or more of HC, HFC or HFO refrigerants such as R32, R290, R245fa, R1234yf, R1234ze(Z), R1233zd(E).

[0035] In this solution, the first throttling component 9, the second throttling component 4, the third throttling component 6 and the solution throttling component 15 are any one, two or three of a manual throttle valve, a capillary tube, a thermostatic expansion valve or an electronic expansion valve.

[0036] Embodiment 2

[0037] As Figure 1 shown, this embodiment provides a heat pump system, including the sludge drying heat pump unit of Embodiment 1 and a sludge tank 11. The sludge tank 11 has a closed space structure. A sludge condenser 3 is arranged inside the sludge tank 11. Part of the high-temperature and high-pressure superheated gaseous refrigerant working medium discharged from the exhaust port of the high-pressure compressor 2 enters the sludge condenser 3 to heat the sludge in the sludge tank 11 and generate water vapor and waste gases such as sulfides and nitrogen oxides. The water vapor carrying waste gases discharged from the steam outlet at the top of the sludge tank 11 enters the absorber 12 and is sprayed with saline-alkali to further recover heat and surplus moisture.

[0038] Specifically, the sludge drying unit includes a two-stage compression heat pump unit and an open absorption heat pump unit. The two-stage compression heat pump unit includes a low-pressure compressor 1, a high-pressure compressor 2, a sludge condenser 3, a second throttling component 4, a steam source evaporator 5, a third throttling component 6, an air source evaporator 7, a solution condenser 8, a first throttling component 9 and a solution source evaporator 10. The exhaust port of the high-pressure compressor 2 is divided into two branches. One branch is connected in series with the solution condenser 8, the first throttling component 9 and the inlet of the solution source evaporator 10 in sequence. The outlet of the solution source evaporator 10 is connected to the suction port of the high-pressure compressor 2. The other branch is connected to the inlet of the sludge condenser 3. The outlet of the sludge condenser 3 is respectively connected to the second throttling component 4 and the third throttling component 6. The outlet of the second throttling component 4 is connected to the inlet of the steam source evaporator 5. The outlet of the steam source evaporator 5 is connected to the suction port of the low-pressure compressor 1. The outlet of the third throttling component 6 is connected to the inlet of the air source evaporator 7. The outlet of the air source evaporator 7 is connected to the suction port of the low-pressure compressor 1. The exhaust port of the low-pressure compressor 1 is connected to the suction port of the high-pressure compressor 2.

[0039] In this solution, the open absorption heat pump unit includes an absorber 12, a solution generator 13, a pump 14, and a spraying component 16. The sludge tank 11 is structured as a closed space. The steam outlet at the top of the sludge tank 11 is connected to the steam inlet of the absorber 12. The solution outlet at the bottom of the absorber 12 is connected to the solution generator 13. The solution outlet at the bottom of the solution generator 13 is connected to the spraying component 16 via the pump 14. The steam outlet at the top of the solution generator 13 is connected to the inlet of the second-side medium channel (water vapor channel) of the steam source evaporator 5. The water vapor channel outlet of the steam source evaporator 5 is connected to the water collection tank through an external pipeline 51.

[0040] In this invention, the saline-alkali solution generated in the solution generator 13 is sent back to the absorber 12 via the pump 14 to continuously absorb water vapor and pollutants such as sulfides and nitrogen oxides, thereby realizing the purification of pollutants generated by sludge heating and dehydration. The water vapor generated by the concentration of the saline-alkali solution in the solution generator 13 enters the steam source evaporator 5 to release the condensation heat and turn into condensed water as industrial makeup water. The released condensation heat is used to heat the refrigerant to vaporize and be recycled, thereby realizing the recovery and utilization of the heat and mass of the water vapor generated by sludge dehydration.

[0041] Embodiment 3

[0042] This embodiment provides a control method for the heat pump system using the heat pump system of Embodiment 2, including the following steps: The high-temperature and high-pressure superheated gaseous refrigerant working medium discharged from the exhaust side of the high-pressure compressor 2 is divided into two parts. One part of the refrigerant working medium releases the condensation heat through the sludge condenser 3 to heat the sludge to realize the sludge dehydration and drying process. The liquid refrigerant condensed by the sludge condenser 3 is throttled and depressurized by the parallel second throttling component 4 and the third throttling component 6. One path of the refrigerant working medium flows into the steam source evaporator 5 to absorb heat and evaporate into refrigerant vapor. The other path of the refrigerant working medium flows into the air source evaporator 7 to absorb the heat energy of the external ambient air and evaporate into refrigerant vapor. The refrigerant vapor at the outlets of the steam source evaporator 5 and the air source evaporator 7 is sucked into the low-pressure compressor 1 to complete the cascade compression process. The other part of the refrigerant working medium enters the solution condenser 8 to release the condensation heat to realize the generation of the waste gas absorption solution, and then this part of the refrigerant working medium enters the high-pressure compressor 2 after throttling, heating, and vaporization to complete the high compression ratio process.

[0043] Specifically, for the superheated gaseous refrigerant working medium with high temperature and high pressure discharged by the high-pressure compressor 2, a part of the refrigerant working medium flows into the sludge condenser 3 to release the condensation heat for heating the sludge, thereby realizing the sludge dehydration and drying process. The condensed liquid refrigerant is throttled and depressurized by the parallel second throttling component 4 and the third throttling component 6, and then flows through the second throttling component 4 into the steam-source evaporator 5 to absorb the condensation heat of the water vapor and evaporate into refrigerant vapor, thus realizing the recovery and utilization of the condensation heat of the water vapor and the purification of pollutants such as the waste gas generated by the sludge heating. At the same time, the refrigerant working medium throttled and depressurized by the third throttling component 6 flows into the air-source evaporator 7 to absorb the heat energy of the external ambient air and evaporate into refrigerant vapor. The refrigerant vapor at the outlets of the steam-source evaporator 5 and the air-source evaporator 7 is sucked into the low-pressure compressor 1 and the high-pressure compressor 2 in sequence to complete the step-by-step compression process with low compression ratio and high compression ratio, thereby realizing the recovery and utilization of the condensation heat of the water vapor generated during the sludge dehydration process; and absorbing the heat energy of the outdoor ambient air to produce high-temperature heat energy to provide the heat required for sludge dehydration and drying. Another part of the refrigerant working medium enters the solution condenser 8 to release the condensation heat for heating the saline-alkali mixed solution, realizing the concentration of the saline-alkali mixed solution and the water vapor generation process. The condensed liquid refrigerant is throttled and depressurized by the first throttling component 9 and then enters the solution-source evaporator 10 to recover the absorption heat released by the saline-alkali mixed solution when absorbing the water vapor and other substances and vaporize into refrigerant working medium gas, and then is sucked into the high-pressure compressor 2 to complete the compression process with a high compression ratio of the refrigerant.

[0044] In this solution, the sludge in the sludge tank 11 is heated and dehydrated by the sludge condenser 3 to generate water vapor carrying waste gas. The water vapor discharged from the sludge tank 11 enters the absorber 12 and is sprayed and absorbed by the absorption solution. The released absorption heat is recovered by the refrigerant working medium in the solution-source evaporator 10. After the waste gas absorption solution discharged from the absorber 12 enters the solution generator 13, it is further heated and concentrated by the solution condenser 8 to generate. The concentrated waste gas absorption solution in the solution generator 13 is sent back to the spraying component 16 by the pump 14 to further realize the cyclic spraying and utilization of the waste gas absorption solution; the water vapor generated by the solution generator 13 is used to heat the refrigerant on the suction port side of the low-pressure compressor 1, and then the water vapor condenses into condensed water and is discharged and collected in the water collection tank for recovery.

[0045] Specifically, the sludge in the sludge tank 11 is heated and dehydrated by the sludge condenser 3 to generate water vapor carrying acidic gases. The acidic gases include waste gases such as sulfides or nitrogen oxides. The water vapor carrying acidic gases enters the absorber 12 and is sprayed with a saline-alkali solution. The saline-alkali solution absorbs the water vapor and pollutants such as sulfides or nitrogen oxides and releases the heat of absorption. The released heat of absorption is recovered by the solution source evaporator 10 to produce high-temperature heat energy to provide the heat required for sludge dehydration and drying. The saline-alkali solution in the absorber 12 becomes a dilute solution due to the absorption of water vapor and enters the solution generator 13, where it is heated and concentrated by the solution condenser 8. The concentrated saline-alkali solution in the solution generator 13 is sent back to the absorber 12 by the pump 14 to continuously absorb water vapor and pollutants such as sulfides or nitrogen oxides, thereby realizing the purification of pollutants generated by sludge heating and dehydration. The water vapor generated by the concentration of the saline-alkali solution inside the solution generator 13 enters the steam source evaporator 5, releases the heat of condensation, and becomes condensed water as industrial make-up water. The released heat of condensation is used to heat the refrigerant working medium to vaporize it and is recycled by the compression heat pump unit, thereby realizing the recovery and utilization of the heat and mass of the water vapor generated by sludge dehydration.

[0046] The above is only a preferred embodiment of the present invention, and it is not intended to limit the present invention in any form. Although the present invention has been disclosed above with a preferred embodiment, it is not intended to limit the present invention. Any person skilled in the art can make some changes or modifications to the above-disclosed technical content within the scope of the technical solution of the present invention to obtain equivalent embodiments with equivalent changes. However, as long as it does not depart from the content of the technical solution of the present invention, any simple modification, equivalent change, and modification made to the above embodiment based on the technical essence of the present invention still fall within the scope of the technical solution of the present invention.

Claims

1. A heat pump system, characterized in that: It includes a sludge pool and a sludge drying heat pump unit for providing heat energy to the sludge pool; A sludge condenser is placed inside the sludge pool, and the steam outlet of the sludge pool is connected to the steam inlet of the absorber; The sludge drying heat pump unit includes a low-pressure compressor, a high-pressure compressor arranged on the exhaust side of the low-pressure compressor, and an absorber. The exhaust side of the high-pressure compressor is divided into two branches. One branch passes through the sludge condenser and is respectively introduced into a steam-source evaporator and an air-source evaporator. The steam-source evaporator has a first medium side and a second medium side. The first medium side is introduced with a refrigerant working medium, and the second medium side is used for introducing a water vapor medium, and the second medium side is used for heating and evaporating the refrigerant medium on the first medium side; The first medium side of the steam-source evaporator and the refrigerant outlet of the air-source evaporator are connected in parallel to the suction side of the low-pressure compressor. The other branch of the exhaust side of the high-pressure compressor passes through a solution condenser, a first throttling component, and a solution-source evaporator in series and then is connected again to the suction side of the high-pressure compressor; A second throttling component is arranged at the inlet of the first medium side of the steam-source evaporator; a third throttling component is arranged on the refrigerant inlet side of the air-source evaporator; A spraying component and the solution-source evaporator are arranged inside the absorber, and the solution-source evaporator is located below the spraying component; the solution outlet of the absorber is connected to the solution generator through a solution throttling component; the solution condenser is arranged inside the solution generator; The water vapor outlet of the solution generator is connected to the inlet of the second medium side of the steam-source evaporator, and the bottom solution outlet side of the solution generator is connected to the spraying component through a pump.

2. The control method of the heat pump system according to claim 1, characterized in that: It includes the following steps: The high-temperature and high-pressure superheated gaseous refrigerant working medium discharged from the exhaust side of the high-pressure compressor is divided into two parts. One part of the refrigerant working medium releases condensation heat through the sludge condenser to heat the sludge to realize the sludge dehydration and drying process. The liquid refrigerant condensed by the sludge condenser is throttled and depressurized by the parallel second throttling component and third throttling component. One path of the refrigerant working medium flows into the steam-source evaporator to absorb heat and evaporate into refrigerant steam, and the other path of the refrigerant working medium flows into the air-source evaporator to absorb the heat energy of the external ambient air and evaporate into refrigerant steam. The refrigerant steam at the outlets of the steam-source evaporator and the air-source evaporator is sucked into the low-pressure compressor to complete the cascade compression process; the other part of the refrigerant working medium enters the solution condenser to release condensation heat to realize the saline-alkali solution concentration and water vapor generation process. Then, this part of the refrigerant working medium is throttled and depressurized by the first throttling component, heated and evaporated into refrigerant steam by the solution-source evaporator, and then enters the high-pressure compressor to complete the high compression ratio process.

3. The control method of the heat pump system according to claim 2, characterized in that: It further includes the following steps: The sludge in the sludge tank is heated and dehydrated by a sludge condenser to generate waste gas and water vapor. The waste gas and water vapor enter the absorber and are sprayed and absorbed by the absorption solution. The released absorption heat is recovered by the solution source evaporator. After the waste gas absorption solution enters the solution generator, it is further heated and concentrated by the solution condenser to occur. The concentrated waste gas absorption solution is pumped back to the spraying component to further realize the cyclic spraying and utilization of the waste gas absorption solution; The water vapor generated by the solution generator is used to heat the refrigerant on the suction side of the low-pressure compressor and then condensed into condensed water.

4. The control method of the heat pump system according to claim 3, characterized in that: The waste gas absorption solution in the absorber uses a saline-alkali solution, and the saline-alkali solution is a ternary mixed solution composed of salt, alkali, and water.

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