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

Abstract

The invention belongs to the technical field of sludge drying treatment heat pump systems, and particularly discloses a sludge drying heat pump unit, a heat pump system and a control method thereof.The sludge drying heat pump unit comprises a low-pressure compressor and a high-pressure compressor arranged on the exhaust side of the low-pressure compressor, and the exhaust side of the high-pressure compressor is divided into two branches; wherein one branch is communicated with a steam source evaporator and an air source evaporator through a sludge condenser, the steam source evaporator is provided with a first medium side and a second medium side, a refrigerant working medium is communicated with the first medium side, and a water vapor medium is communicated with the second medium side; the second medium side is used for heating and evaporating a refrigerant medium on the first medium side; and the first medium side of the steam source evaporator and the refrigerant outlet of the air source evaporator are connected in parallel to the air suction side of the low-pressure compressor. According to the scheme, the problems that a traditional sludge drying system is poor in drying effect, secondary pollution is generated, and waste heat is difficult to recover can be effectively solved.

Description

Technical Field

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

[0002] At present, no matter biological treatment sludge or chemical precipitation sludge, after being treated by mechanical front-end dehydration equipment, the moisture content of the sludge is still relatively high, and the drying efficiency of the equipment is low, such as plate and frame filter press, centrifuge, screw stack, high-pressure plate and frame filter press dehydration and other methods, which greatly affects the subsequent sludge transportation and resource disposal and utilization.

[0003] In the related existing technologies, sludge drying and dehumidification mainly adopts direct heating method, that is, using steam, flue gas, electric heating and other forms to heat the sludge to above 100°C, so that the moisture of the sludge is converted into water vapor and directly discharged into the atmosphere. This drying method has problems such as high energy consumption and easy to cause secondary pollution.

[0004] In order to solve the problems of high energy consumption, high operating costs, environmental pollution, and low drying efficiency in the existing sludge drying system, low-temperature drying technology using low-grade energy has emerged. The prior art (publication number CN 112062441 A) discloses a low-temperature sludge drying equipment that uses a combination of heat pump circulation and air circulation, adopts a unique independent air duct technology, has zero emissions and no odor, but the gas heat energy such as discharged water vapor is not fully utilized. Therefore, how to improve the sludge drying efficiency, make full use of the gas waste heat generated by drying, and combine with the heat pump system to achieve efficient energy utilization and waste gas purification has become a key issue that needs to be overcome in the field of sludge drying. Summary of the invention

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

[0006] One of the objects of the present invention is to provide a sludge drying heat pump unit, comprising 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 which is connected to a steam source evaporator and an air source evaporator through a sludge condenser respectively, the steam source evaporator has a first medium side and a second medium side, the first medium side is connected to a refrigerant medium, the second medium side is used to pass water vapor medium, and the second medium side is used to heat and evaporate 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, and the other branch on the exhaust side of the high-pressure compressor is connected in series through a solution condenser, a first throttling component and a solution source evaporator and then connected to the suction side of the high-pressure compressor again.

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

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

[0009] As a preferred solution, it also includes an absorber, in which a spray component and the solution source evaporator are arranged, and the solution source evaporator is located below the spray component; the solution outlet of the absorber is connected to the solution generator through a solution throttling component.

[0010] As a preferred embodiment, 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 spray component through a pump.

[0011] A second object of the present invention is to provide a heat pump system, comprising a sludge pool and any one of the above-mentioned sludge drying heat pump units for providing heat energy to the sludge pool.

[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] The third object of the present invention is to provide a control method according to the above-mentioned heat pump system, comprising the following steps: a high-temperature and high-pressure superheated gaseous refrigerant is discharged from the exhaust side of the high-pressure compressor and is divided into two parts, wherein a part of the refrigerant releases condensation heat through the sludge condenser to heat the sludge to realize the sludge dehydration and drying process, and the liquid refrigerant condensed by the sludge condenser is throttled and reduced in pressure through the second throttling component and the third throttling component connected in parallel, one refrigerant flows into the steam source evaporator to absorb heat and evaporate into refrigerant vapor, and the other refrigerant flows into the air source evaporator to absorb the heat energy of the external ambient air and evaporate into refrigerant vapor, and the refrigerant vapor passing through the outlet of the steam source evaporator and the air source evaporator is sucked into the low-pressure compressor to complete the step compression process; the other part of the refrigerant enters the solution condenser to release condensation heat to realize the saline-alkali solution concentration and water vapor generation process, and then this part of the refrigerant passes through the first throttling component to throttle and reduce the pressure, and the solution source evaporator is heated and evaporated into refrigerant vapor, and then enters the high-pressure compressor to complete the high compression ratio process.

[0014] As a preferred scheme, it also includes the following steps: the sludge in the sludge pool 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, and after the waste gas absorption solution enters the solution generator, it is further heated and concentrated by the solution condenser, and the concentrated waste gas absorption solution is pumped back to the spray component to further realize the cyclic spraying 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.

[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: First, the present invention provides a new type of sludge drying heat pump treatment system. By optimizing the structure of the heat pump unit, a graded compression heat pump unit is used to recover the latent heat of water vapor generated by sludge drying, and the refrigerant steam discharged by the high-pressure compressor is split 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 to complete the low compression ratio and high compression ratio step compression process, while 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, and then after throttling and heating by the solution source evaporator, it enters the air intake of the high-pressure compressor to complete the high compression ratio compression process. The heat pump system of this scheme effectively overcomes the problems of poor drying effect, breeding of secondary pollution, and difficulty in recovering waste heat in the traditional drying system. The system has the advantages of energy saving and environmental protection, stability and reliability, and wide application area, and has broad application prospects.

[0017] Secondly, the present invention optimizes the sludge drying control method. By adopting the sludge drying heat pump system of the above structure, the latent heat of water vapor generated by the high-temperature dehydration and drying of the sludge is recovered and utilized through the graded compression heat pump. At the same time, the ambient air heat energy is used to produce dual-temperature (high temperature, medium temperature) heat energy to provide high-temperature heat energy for sludge dehydration and drying and medium-temperature heating for the concentration of saline-alkali solution. The hygroscopicity of the saline-alkali solution to water vapor and the absorption of acidic gases are utilized to realize the recovery and utilization of the absorption heat released by the saline-alkali mixed solution absorbing water vapor, etc., and at the same time, waste gas pollutants such as sulfide or nitrogen oxides are removed, thereby realizing the purification effect of pollutants generated by sludge heating and dehydration. The water vapor generated by the concentration of the saline-alkali solution is cooled by the steam source evaporator to release condensation heat and become condensed water as industrial make-up water. The released condensation heat is used to heat the refrigerant for vaporization and is recovered and utilized, thereby realizing the recovery and utilization of the heat quality of water vapor generated by sludge dehydration. The sludge treatment method of this scheme realizes the dual purposes of improving the quality of thermal energy, realizing the step-by-step preparation and utilization of thermal energy, and simultaneously completing the purification of waste gas generated by sludge high-temperature dehydration. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the embodiments of the invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0019] Figure 1 It is a schematic diagram of the principle of the heat pump system of the present invention.

[0020] 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. spray component. DETAILED DESCRIPTION

[0021] The present invention is described in detail below by means of exemplary embodiments. However, it should be understood that, without further description, elements, structures and features in one embodiment may also be beneficially combined in other embodiments.

[0022] It should be noted that, unless otherwise defined, the technical terms or scientific terms used herein shall have the usual meanings understood by persons with ordinary skills in the field to which the invention belongs. The words "one", "an" or "the" and the like used in the patent application specification and claims of the present invention do not express quantitative limitations, but indicate the existence of at least one. Words such as "include" or "comprise" indicate that the elements or objects appearing before "include" or "comprises" include the elements or objects listed after "include" or "comprises" and their equivalents, but do not exclude other elements or objects with the same function.

[0023] Example 1 like Figure 1 As shown, this embodiment provides a sludge drying heat pump unit, including a compression heat pump unit and an open absorption heat pump unit, wherein the compression heat pump unit adopts a two-stage compressor unit, and the compression heat pump unit produces dual-temperature heat energy and provides it to the open absorption heat pump unit to achieve the high-temperature heating required for sludge dehydration and drying and the medium-temperature heating required for the concentration of the waste gas absorption solution, while the open absorption heat pump unit can not only recover the water vapor generated by sludge dehydration through the hygroscopicity of saline-alkali solution on water vapor and the absorption of acidic gas, but also provide the generated absorption heat to the compression heat pump unit for recycling, and remove waste gas pollutants such as sulfide or nitrogen oxides, thereby achieving the purification of pollutants generated by sludge heating and dehydration.

[0024] 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.

[0025] 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: One of the branches passes through the solution condenser 8, the first throttling component 9 and the solution source evaporator 10 and is then connected to the suction side of the high-pressure compressor 2. 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, and 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 passes through the solution condenser 8 to condense and generate the saline-alkali solution in the solution generator 13, and the refrigerant vapor is condensed into liquid refrigerant inside the solution condenser 8. The condensed liquid refrigerant is throttled and depressurized by the first throttling component 9, and then enters the solution source evaporator 10 to recover heat from 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, thereby completing the compression process with a high compression ratio.

[0026] The other branch is connected to the steam source evaporator 5 and the air source evaporator 7 respectively 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 (water vapor) 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 refrigerant outlet of the first medium side of the steam source evaporator 5 and the air source evaporator 7 are connected in parallel to the suction side of the low-pressure compressor 1, and the outlet of the sludge condenser 3 is divided into two branches, which are respectively connected to the inlets of the second throttling component 4 and the third throttling component 6, wherein 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.

[0027] In this solution, the high-temperature and high-pressure superheated gaseous refrigerant of the sludge condenser 3 can heat the sludge, so that the water in the sludge evaporates and is discharged into the absorber 12 through the top steam outlet. After the gaseous refrigerant is condensed into liquid refrigerant, it is throttled and depressurized by the second throttling component 4 and the third throttling component 6 respectively arranged in parallel, and then flows into the refrigerant channel of 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, and flows into the refrigerant channel of the air source evaporator 7 after passing through the third throttling component 6, thereby absorbing the heat energy of the external ambient air, so that the refrigerant evaporates into refrigerant vapor. The refrigerant vapor discharged from the steam source evaporator 5 and the air source evaporator 7 is sucked into the air intake of the low-pressure compressor 1, thereby completing the step compression process.

[0028] 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 spray component 16. The absorber 12 includes a steam inlet, a solution inlet and a solution outlet, wherein the steam inlet of the absorber 12 is used to be connected to the steam outlet of the sludge tank 11, and the absorber 12 is used to pass water vapor containing waste gas evaporated and separated by the sludge tank 11. A spray component 16 and a solution source evaporator 10 are arranged in the absorber 12, and the solution source evaporator 10 is located below the spray component 16; the solution source evaporator 10 is arranged in the absorber 12 and submerged in the saline-alkali mixed solution, and the spray component 16 is used to be connected to the solution inlet. Preferably, the steam inlet of the absorber 12 is located on its side wall and below the spray component 16. The saline-alkali solution sprayed by the spray component 16 can absorb the water vapor containing acidic waste gas entering the steam inlet and release the absorption heat at the same time. The function of the solution source evaporator 10 is to recover the absorption heat released in the absorber 12 through the refrigerant working medium introduced into it, and the refrigerant working medium directly enters the high-pressure compressor 2 after absorbing and recovering the heat to complete the compression process of the high-pressure compression ratio. It should be noted that the spray component 16 includes one or more spray heads.

[0029] 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 water vapor from the sludge pool 11. During the process of the saline-alkali solution absorbing water vapor and pollutants such as sulfides and nitrogen oxides, the absorption 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 further heat required for sludge dehydration and drying. The saline-alkali solution absorbs water vapor and further becomes a dilute saline-alkali solution, and enters the solution generator 13 for further concentration. The solution condenser 8 is provided in the solution generator 13; specifically, the solution condenser 8 is provided in the internal space of the solution generator 13 and submerged in the saline-alkali mixed solution.

[0030] 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 spray component 16 through the pump 14. The solution condenser 8 is used to provide heat for the concentration of the dilute saline-alkali solution in the solution generator 13. The water vapor generated by the concentration of the dilute saline-alkali solution can be further condensed and recovered through the steam source evaporator 5, and the recovered condensed water enters the water collection tank through the external pipe 51, so as to be further used as industrial water replenishment; the concentrated saline-alkali solution will be discharged through the bottom solution outlet of the solution generator 13, and will be sprayed again through the spray component 16 through the circulation of the pump 14 into the absorber 12, completing the cyclic absorption process of the saline-alkali solution and the water vapor with pickling waste gas from the sludge tank 11.

[0031] In this scheme, 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 is a mixed fluid composed of one or more of HC, HFC or HFO refrigerants such as R32, R290, R245fa, R1234yf, R1234ze(Z), R1233zd(E).

[0032] 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 throttling valve, a capillary tube, a thermal expansion valve or an electronic expansion valve.

[0033] Example 2 like Figure 1 As shown, this embodiment provides a heat pump system, including the sludge drying heat pump unit of Example 1 and a sludge pool 11. The sludge pool 11 is a closed space structure. A sludge condenser 3 is arranged inside the sludge pool 11. A part of the high-temperature and high-pressure superheated gaseous refrigerant discharged from the exhaust port of the high-pressure compressor 2 enters the sludge condenser 3, which is used to heat the sludge in the sludge pool 11 and generate water vapor and waste gases such as sulfides and nitrogen oxides. The water vapor carrying the waste gas discharged from the steam outlet at the top of the sludge pool 11 enters the absorber 12 and is sprayed with salt and alkali to further realize the recovery of heat and residual moisture.

[0034] 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 of which 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, and the other branch is connected to the inlet of the sludge condenser 3, the outlet of the sludge condenser 3 is connected to the second throttling component 4 and the third throttling component 6 respectively, 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.

[0035] In this solution, the open absorption heat pump unit includes an absorber 12, a solution generator 13, a pump 14, and a spray component 16. The sludge tank 11 is 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 spray 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, and the outlet of the water vapor channel of the steam source evaporator 5 is connected to the water collecting tank via the external pipe 51.

[0036] In the present invention, the saline-alkali solution generated in the solution generator 13 is sent back to the absorber 12 through the pump 14 to continuously absorb water vapor and pollutants such as sulfides and nitrogen oxides, thereby achieving 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 condensation heat and become condensed water as industrial makeup water. The released condensation heat is used to heat the refrigerant to vaporize and is recycled, thereby achieving the heat and mass recovery of the water vapor generated by sludge dehydration.

[0037] Example 3 The present embodiment provides a control method for a heat pump system using the embodiment 2, comprising the following steps: a high-temperature and high-pressure superheated gaseous refrigerant is discharged from the exhaust side of the high-pressure compressor 2 and is divided into two parts, wherein a part of the refrigerant releases 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 reduced in pressure through the second throttling component 4 and the third throttling component 6 connected in parallel, one path of the refrigerant flows into the steam source evaporator 5 to absorb heat and evaporate into refrigerant vapor; the other path of the refrigerant 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 passing through 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 step compression process, and the other part of the refrigerant enters the solution condenser 8 to release condensation heat to realize the generation of the exhaust gas absorption solution, and then this part of the refrigerant enters the high-pressure compressor 2 after being throttled, heated and vaporized to complete the high compression ratio process.

[0038] Specifically, the high-temperature and high-pressure superheated gaseous refrigerant discharged by the high-pressure compressor 2, wherein a part of the refrigerant flows into the sludge condenser 3 to release the condensation heat to heat the sludge, thereby realizing the sludge dehydration and drying process. The condensed liquid refrigerant is throttled and reduced in pressure by the second throttling component 4 and the third throttling component 6 in parallel, and then flows into the steam source evaporator 5 through the second throttling component 4 to absorb the condensation heat of water vapor and evaporate into refrigerant vapor, thereby realizing the recovery and utilization of the condensation heat of water vapor and the purification of pollutants such as exhaust gas generated by sludge heating. At the same time, the refrigerant after throttling and reducing in pressure 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 to complete the step compression process of low compression ratio and high compression ratio in turn, thereby realizing the recovery and utilization of the condensation heat of water vapor generated in 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 enters the solution condenser 8 to release condensation heat to heat the saline-alkali mixed solution, thereby realizing the concentration of the saline-alkali mixed solution and the generation of water vapor. The condensed liquid refrigerant is throttled and reduced in pressure 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 absorbing water vapor and the like and vaporizes into a refrigerant gas, which is then sucked into the high-pressure compressor 2 to complete the high-pressure ratio compression process of the refrigerant.

[0039] In this scheme, the sludge in the sludge pool 11 is heated and dehydrated by the sludge condenser 3 to generate water vapor carrying waste gas, the water vapor discharged from the sludge pool 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, the waste gas absorption solution discharged from the absorber 12 enters the solution generator 13, and is further heated and concentrated by the solution condenser 8, the concentrated waste gas absorption solution in the solution generator 13 is sent back to the spray component 16 through the pump 14, and the cyclic spraying utilization of the waste gas absorption solution is further realized; the water vapor generated by the solution generator 13 is used to heat the refrigerant on the suction side of the low-pressure compressor 1, and then the water vapor is condensed into condensed water and discharged to be collected in the water collecting tank for recovery.

[0040] Specifically, the sludge in the sludge pool 11 is heated and dehydrated by the sludge condenser 3 to generate water vapor carrying acidic gas, and the acidic gas includes waste gas such as sulfide or nitrogen oxide. The water vapor carrying acidic gas enters the absorber 12 and is sprayed with saline-alkali solution. The saline-alkali solution absorbs water vapor and pollutants such as sulfide or nitrogen oxide and releases absorption heat. The released absorption heat 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 becomes a dilute solution due to the absorption of water vapor in the absorber 12 and enters the solution generator 13 to be dissolved by the solution. The condenser 8 is heated and concentrated, and the saline-alkali solution concentrated by the solution generator 13 is sent back to the absorber 12 through the pump 14 to continuously absorb water vapor and pollutants such as sulfide or nitrogen oxide, thereby achieving the purification of pollutants generated by the 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 to release condensation heat and become condensed water as industrial makeup water. The released condensation heat is used to heat the refrigerant working fluid to vaporize it and is recycled by the compression heat pump unit, thereby achieving the heat recovery of the water vapor generated by the sludge dehydration.

[0041] The above are only preferred embodiments of the present invention, and are not intended to limit the present invention in any form. Although the present invention has been disclosed as a preferred embodiment as above, it is not intended to limit the present invention. Any technician familiar with the profession can make some changes or modifications to equivalent embodiments of equivalent changes using the technical contents disclosed above without departing from the scope of the technical solution of the present invention. However, any simple modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention are still within the scope of the technical solution of the present invention.

Claims

1. A sludge drying heat pump unit, comprising a low-pressure compressor and a high-pressure compressor arranged on the exhaust side of the low-pressure compressor, characterized in that: The exhaust side of the high-pressure compressor is divided into two branches, one of which is respectively connected to the steam source evaporator and the air source evaporator through the sludge condenser, and the steam source evaporator has a first medium side and a second medium side, the first medium side is connected to the refrigerant medium, and the second medium side is used to connect the water vapor medium, and the second medium side is used to heat and evaporate 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, and the other branch on the exhaust side of the high-pressure compressor is connected in series through the solution condenser, the first throttling component and the solution source evaporator and then connected to the suction side of the high-pressure compressor again.

2. The sludge drying heat pump unit according to claim 1, characterized in that: A second throttling component is provided at the inlet of the first medium side of the steam source evaporator.

3. The sludge drying heat pump unit according to claim 1 or 2, characterized in that: A third throttling component is provided on the refrigerant inlet side of the air source evaporator.

4. The sludge drying heat pump unit according to claim 3 is characterized in that: It also includes an absorber, in which a spray component and the solution source evaporator are arranged, and the solution source evaporator is located below the spray component; the solution outlet of the absorber is connected to the solution generator through a solution throttling component.

5. The sludge drying heat pump unit according to claim 4, characterized in that: 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 spray component through a pump.

6. Heat pump system, characterized in that: The invention comprises a sludge pool and a sludge drying heat pump unit as claimed in any one of claims 1 to 5 for providing heat energy to the sludge pool.

7. The heat pump system according to claim 6, characterized in that: The 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.

8. The control method of the heat pump system according to claim 7, characterized in that: The method comprises the following steps: a high-temperature and high-pressure superheated gaseous refrigerant is discharged from the exhaust side of the high-pressure compressor and is divided into two parts, wherein a part of the refrigerant releases condensation heat through the sludge condenser to heat the sludge to realize the sludge dehydration and drying process, and the liquid refrigerant condensed by the sludge condenser is throttled and depressurized through the second throttling component and the third throttling component connected in parallel, one part of the refrigerant flows into the steam source evaporator to absorb heat and evaporate into refrigerant steam, and the other part of the refrigerant flows into the air source evaporator to absorb heat energy of the external ambient air and evaporate into refrigerant steam, and the refrigerant steam passing through the outlets of the steam source evaporator and the air source evaporator is sucked into the low-pressure compressor to complete the step compression process; the other part of the refrigerant enters the solution condenser to release condensation heat to realize the saline-alkali solution concentration and water vapor generation process, and then this part of the refrigerant passes through the first throttling component to throttle and depressurize, and the solution source evaporator is heated and evaporated into refrigerant steam, and then enters the high-pressure compressor to complete the high compression ratio process.

9. The control method of the heat pump system according to claim 8, characterized in that: It also includes the following steps: the sludge in the sludge pool 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, and the waste gas absorption solution enters the solution generator and is further heated and concentrated by the solution condenser, and the concentrated waste gas absorption solution is pumped back to the spray component to further realize the cyclic spraying 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.

10. The control method of the heat pump system according to claim 9, characterized in that: The waste gas absorption solution in the absorber adopts a saline-alkali solution, which is a ternary mixed solution composed of salt, alkali and water.

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