Heat pump drying system and heating method thereof

Abstract

The invention belongs to the technical field of flue gas treatment heat pump systems, and particularly relates to a heat pump drying system and a heating method thereof.The heat pump drying system comprises an open type absorption heat pump unit and a parallel compression heat pump unit, and the parallel compression heat pump unit provides heating capacity needed by generation of a generator of the open type absorption heat pump unit by producing double-temperature-level heat energy; the open type absorption heat pump unit comprises an open type heat insulation absorption tower, a high-pressure generator, a low-pressure generator, a first ejector and a second ejector; a flue gas inlet of the open type heat insulation absorption tower is used for introducing hot and wet flue gas to be treated; a spraying piece and a filler layer are arranged in the open type heat insulation absorption tower, the spraying piece is located above the filler layer, and the filler layer is located above the flue gas inlet; according to the device, waste heat and waste moisture of flue gas can be recycled in order, and the problems that a traditional open type absorption heat pump is low in efficiency and water vapor contained in the flue gas cannot be recycled in the flue gas drying process are effectively solved.

Description

Technical Field

[0001] The present invention belongs to the technical field of flue gas treatment heat pump systems, and in particular relates to a heat pump drying system and a heating method thereof, which can be used for drying hot and wet flue gas and recovering waste heat. Background Art

[0002] In the related prior art, there are generally three methods for treating hot and wet waste gas (flue gas): the first is the flue gas water medium heat exchange system (MGGH), which uses water as a medium to absorb the heat of the high-temperature flue gas before desulfurization through a water circulation method, and is used to heat the clean flue gas after desulfurization, increase the temperature of the clean flue gas, increase the lifting height of the flue gas emission, and reduce the landing concentration of pollutants. The disadvantage of this method is that it cannot achieve the waste gas heat and mass recovery effect. The second is the wet method, that is, the wet tail gas is directly passed into the spray chamber, and the spray water contacts the tail gas for heat exchange; the heat released by the wet tail gas in this process is low in temperature and mixed with pollutants, and cannot be reused, but this method has the effect of dust removal and purification on the tail gas; the third is the indirect heat exchange method, that is, heat exchange is carried out through heat exchange components such as heat exchangers and evaporators of heat pump systems to achieve heat recovery. Compared with the wet method, the temperature of the recovered heat is significantly increased in this method, and its shortcomings are mainly reflected in the fact that the temperature of the heat recovery medium must be reduced to below the dew point temperature.

[0003] At present, the main energy-saving devices for waste heat recovery of hot and wet exhaust gas are wall heat exchangers, closed absorption heat pumps and open absorption heat pumps. The traditional "cooling and condensation method" for recovering latent heat of vaporization, that is, using the "wall heat exchanger + lithium bromide closed absorption heat pump" method, can realize the recovery and utilization of sensible heat and latent heat of hot and wet flue gas, but it has many disadvantages. First, lowering the flue gas temperature to recover waste heat will produce a large amount of sewage, causing secondary environmental disasters, and the cost of later treatment is high; secondly, the reduction of flue gas temperature is not conducive to flue gas emission, and "hanging ice" is formed at the top of the chimney, which has safety hazards; in addition, traditional heat pump products are affected by the fluctuation of heating water temperature in winter, and the heat extraction capacity fluctuates greatly, which seriously affects the waste heat recovery efficiency. In short, traditional latent heat recovery adopts the "cooling and condensation" method, which has a large exergy loss; in addition, during the flue gas condensation process, the condensed water will carry flue gas pollutants (SO2, NOX, dust, etc.), which will become industrial sewage and cause secondary environmental pollution. It can be seen that the traditional cooling and condensation method for treating waste heat and moisture in flue gas has problems such as low energy recovery rate, zero mass recovery rate and secondary disasters of pollutants in hot and wet waste gas.

[0004] Another method is the open absorption heat pump technology. Unlike the above methods, it realizes heat transfer through the mass transfer process to achieve the purpose of heat recovery. The advantages of this method are mainly reflected in: (1) The condensation process of water vapor in the humid gas is realized by the water vapor partial pressure difference between the dehumidifying solution and the humid gas. Therefore, the solution temperature does not need to be lowered to below the dew point temperature during the recovery process, and the heat recovery temperature is higher; (2) The working fluids used are humid gas and dehumidifying solution, both of which are natural working fluids with zero ODP and GWP. The dehumidifying solution can also play the role of dust removal and air purification; (3) The open absorption heat pump is a type of absorption heat pump. Both are heat-driven systems. Low-grade waste heat can be used as solution regeneration energy to reduce primary energy consumption. However, the existing open absorption heat pump technology cannot recover and reuse the water vapor contained in the hot and humid flue gas during the drying process of the hot and humid flue gas. Summary of the invention

[0005] The purpose of the present invention is to solve the above-mentioned problems existing in the prior art and to provide a heat pump drying system and a heating method thereof. The device can orderly recycle the waste heat and moisture of hot and humid exhaust gas, and can effectively solve the problems of low efficiency and inability to recover water vapor contained in the exhaust gas (flue gas) existing in the traditional open absorption heat pump.

[0006] To achieve the above object, one of the objects of the present invention is to provide a heat pump drying system. It comprises an open absorption heat pump unit and a parallel compression heat pump unit, wherein the parallel compression heat pump unit produces dual-temperature heat energy to provide the generator of the open absorption heat pump unit with the required heating amount; The open absorption heat pump unit comprises an open adiabatic absorption tower, a high pressure generator, a low pressure generator, a first ejector and a second ejector; The flue gas inlet of the open-type heat-insulating absorption tower is used to introduce the hot and humid flue gas to be treated; a spraying element and a packing layer are arranged in the open-type heat-insulating absorption tower, the spraying element is located above the packing layer, and the packing layer is located above the flue gas inlet; the spraying element is used to spray a solution to form a dilute solution with a lower concentration by absorbing water vapor in the hot and humid flue gas, and at the same time release absorption heat to heat the dilute solution and the flue gas; The bottom solution outlet of the open adiabatic absorption tower is divided into two branches; The first branch is connected to the solution inlet of the open adiabatic absorption tower through a pump; The second branch is connected to the inlet of the high-pressure generator and the inlet of the low-pressure generator respectively; The steam outlet of the high pressure generator is connected to the working fluid inlet of the second ejector, and the solution outlet of the high pressure generator is connected to the working fluid inlet of the first ejector; The steam outlet of the low-pressure generator is connected to the injection fluid inlet of the second ejector, and the solution outlet of the low-pressure generator is connected to the injection fluid inlet of the first ejector; The mixed fluid outlet of the second ejector is connected to the condensed water storage tank; the mixed fluid outlet of the first ejector is connected to the top solution inlet of the open adiabatic absorption tower, and the solution inlet of the open adiabatic absorption tower is connected to the spraying element.

[0007] As a preferred solution, it also includes a solution heat exchanger; The inlet and outlet of the dilute solution channel of the solution heat exchanger are connected to the pipeline between the solution outlet and the generator inlet of the open adiabatic absorption tower; The inlet and outlet of the concentrated solution channel of the solution heat exchanger are connected to the pipeline between the mixed fluid outlet of the first ejector and the solution inlet of the open adiabatic absorption tower.

[0008] As a preferred solution, the parallel compression heat pump unit comprises a first refrigerant channel and a second refrigerant channel arranged in parallel; The first refrigerant channel is provided with a first compressor, a high-temperature solution condenser and a first throttling component in series in sequence; The second refrigerant channel is provided with a second compressor, a low-temperature solution condenser and a second throttling component in series in sequence; The refrigerant medium throttled by the first throttling component and the second throttling component is divided into two paths after absorbing heat from an external heat source and heat provided by the open absorption heat pump unit, and enters the first compressor and the second compressor respectively.

[0009] As a preferred solution, it also includes an external heat source evaporator; The inlet of the refrigerant channel of the external heat source evaporator is connected to the outlet of the first throttling component and the outlet of the second throttling component respectively; The outlet of the refrigerant channel of the external heat source evaporator is connected to the inlet of the first compressor and the inlet of the second compressor respectively.

[0010] As a preferred solution, it also includes a solution evaporator; the solution evaporator is located outside the tower body of the open adiabatic absorption tower; The inlet and outlet of the solution channel of the solution evaporator are respectively connected to the pump outlet and the solution inlet of the open adiabatic absorption tower; The refrigerant channel inlet and outlet of the solution evaporator are respectively connected to the refrigerant channel outlet of the external heat source evaporator and the inlets of the first compressor and the second compressor.

[0011] As a preferred solution, it also includes a solution cooler and a water vapor condenser; the solution cooler is located outside the tower body of the open adiabatic absorption tower; The solution cooler comprises a solution channel and a medium channel for realizing heat exchange, the inlet of the solution channel of the solution cooler is connected to the pump outlet, the outlet of the solution channel of the solution cooler is connected to the solution inlet of the open adiabatic absorption tower via the solution evaporator, the outlet of the medium channel of the solution cooler is connected to the inlet of the water vapor condenser, and the inlet of the medium channel is connected to the heating return pipe; The water vapor condenser is placed inside the condensate storage tank. The water vapor condenser is used to heat the heating medium passing through it and condense the steam in the condensate storage tank. The outlet of the water vapor condenser is connected to the heating drain pipe.

[0012] As a preferred solution, the condensate outlet of the condensate storage tank is connected to an industrial water replenishment pipe for discharging the internal condensate for industrial water replenishment.

[0013] The second object of the present invention is to provide a heating method according to the above heat pump drying system, comprising an open absorption heat pump unit operation step and a parallel compression heat pump unit operation step; The operation steps of the open absorption heat pump unit include the following steps: The concentrated solution generated in the high-pressure generator is used as a working fluid to enter the first ejector to eject the concentrated solution generated in the low-pressure generator. After the mixed concentrated solution at the outlet of the first ejector is heat-exchanged with the dilute solution from the open adiabatic absorption tower, the mixed concentrated solution at the outlet of the first ejector enters the open adiabatic absorption tower to absorb moisture and dry the flue gas and turn it into a dilute solution, while releasing absorption heat to heat the dilute solution and the flue gas. The water vapor with a first pressure value generated by the high-pressure generator enters the second ejector as a working fluid to eject the water vapor with a second pressure value generated by the low-pressure generator; the mixed water vapor at the outlet of the second ejector releases condensation heat and is condensed into liquid water; The dilute solution flowing out of the open adiabatic absorption tower is divided into two branches, one of which is used to realize the cascade utilization of the recovered flue gas waste heat; the other branch is preheated by the mixed concentrated solution at the outlet of the first ejector, and then enters the generator to absorb heat and generate.

[0014] As a preferred solution, the parallel compression heat pump unit operation steps include the following steps: The refrigerant working medium of the parallel compression heat pump unit is divided into two paths; wherein; A gaseous refrigerant is compressed by a first compressor into high-pressure, high-temperature, superheated refrigerant vapor to complete a high compression ratio compression process, and then enters a high-temperature solution condenser to provide heat required for the high-pressure generator to generate superheated water vapor of a first pressure value; The other gaseous refrigerant is compressed by the second compressor into a higher pressure, higher temperature superheated refrigerant vapor to complete a compression process with a higher compression ratio, and then enters the low-temperature solution condenser to provide the low-pressure generator with the heat required for generation, and the low-pressure generator generates superheated water vapor of a second pressure value; The liquid refrigerant discharged from the high-temperature solution condenser and the low-temperature solution condenser becomes a refrigerant of the same pressure after throttling and depressurization by the throttling component and returns to the suction port of the first compressor and the second compressor to complete the compression process after absorbing heat.

[0015] As a preferred solution, the liquid refrigerant discharged from the high-temperature solution condenser and the low-temperature solution condenser becomes a refrigerant of the same pressure after throttling and reducing the pressure through a throttling component, and after absorbing heat from an external heat source and recovering the waste heat of the flue gas absorbed by the open absorption heat pump unit, returns to the suction port of the first compressor and the second compressor to complete the compression process.

[0016] As a preferred embodiment, the refrigerant of the parallel compression heat pump unit is a mixed refrigerant composed of one or more of R32, R290, R600a, and R1234yf.

[0017] As a preferred embodiment, the circulating solution of the open absorption heat pump unit is a binary non-azeotropic mixed working fluid composed of salt and water, and the circulating solution is a lithium chloride aqueous solution, a calcium chloride aqueous solution, a lithium bromide solution or a potassium formate solution.

[0018] Compared with the prior art, the present invention has at least the following beneficial effects: First, the present invention provides a heat pump drying system, including an open absorption heat pump unit and a parallel compression heat pump unit. The parallel compression heat pump unit extracts dual-temperature heat energy through a parallel compressor to provide the required heating capacity of the generator of the open absorption heat pump unit, thereby eliminating the high-temperature heat source heating capacity required by the traditional absorption heat pump generator. The solution and water vapor generated by the high-pressure generator are respectively used as the working fluid of the first ejector and the second ejector to eject the solution and water vapor generated by the low-pressure generator, thereby eliminating the pressurized conveying equipment such as a solution pump or a compressor. Therefore, this scheme realizes the reasonable optimization of the heat pump system structure. Inside the tower body of the open insulated absorption tower, the hot and humid flue gas meets the spray solution in the packing layer and heat and mass transfer occur. The solution recovers the residual heat and residual moisture carried by the flue gas. The spray solution absorbs the water vapor in the flue gas to form a dilute solution with a lower concentration, and releases the absorption heat to heat the dilute solution and flue gas at the same time. The moisture content of the flue gas is reduced and the temperature is increased. The system has a significant energy-saving effect, stable and reliable operation, and broad application prospects.

[0019] Secondly, in this scheme, the solution cooler and solution evaporator of the open adiabatic absorption tower are designed in series, and by arranging the solution cooler and solution evaporator outside the tower body, instead of the traditional open adiabatic absorption tower structure in which a water-cooled cooler is arranged inside the tower body, the heat and mass transfer process of the solution absorbing water vapor is separated, so that the two processes are strengthened separately.

[0020] Thirdly, the present invention optimizes the heating method of the heat pump system. By combining with the heat pump drying system of the above-mentioned specific structure, a part of the flue gas waste heat recovered by the open absorption heat pump unit is directly used for primary heating of hot water, and the other part is used for secondary heating of hot water through a parallel compression heat pump unit to improve the thermal energy quality, thereby realizing a step-by-step heating process for heating water; the waste heat generated by the open absorption heat pump unit can be used as a secondary heat source for the parallel compressor heat pump unit to ensure that the refrigerant at the compressor suction port is always in a superheated gas state, and by drying the hot and humid flue gas, the waste moisture recovered from the hot and humid flue gas can be condensed into condensed water as industrial water, which significantly reduces the heating amount of the high-temperature heat source required for the open absorption heat pump, solves the problem of low efficiency of the traditional open absorption heat pump, and at the same time realizes the recovery and reuse of the water vapor contained in the flue gas during the hot and humid flue gas drying process. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] 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.

[0022] Figure 1 It is a structural schematic diagram of the heat pump drying system of the present invention; Markings in the figure: 1. high-pressure generator, 2. low-pressure generator, 3. first ejector, 4. solution heat exchanger, 5. open insulated absorption tower, 51. tower body, 52. flue gas inlet, 53. solution inlet, 54. solution outlet, 55. flue gas outlet, 6. pump, 7. solution cooler, 8. solution evaporator, 9. second ejector, 10. condensate storage tank, 101. heating return pipe, 102. heating drain pipe, 103. industrial feed water pipe, 11. steam condenser, 12. first compressor, 13. second compressor, 14. high-temperature solution condenser, 15. low-temperature solution condenser, 16. first throttling component, 17. second throttling component, 18. external heat source evaporator, 181. external heat source side channel, 19. spraying part, 20. packing layer. DETAILED DESCRIPTION

[0023] 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.

[0024] 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.

[0025] As shown in the figure, this embodiment provides a heat pump drying system that can be used for waste heat recovery and drying of hot and humid flue gas. It includes the following two parts: an open absorption heat pump unit and a parallel compression heat pump unit, wherein the open absorption heat pump unit is an open double-effect absorption heat pump unit, which is used to recover the waste heat in the hot and humid flue gas, and at the same time dry the hot and humid flue gas, and recycle the waste heat and moisture in the flue gas. The parallel compression heat pump unit utilizes the waste heat of the absorbed flue gas and the external air heat source, and produces dual-temperature heat energy to provide the required heating for the generator of the open absorption heat pump unit. The heat pump system of this scheme not only realizes the orderly recovery and utilization of waste heat and moisture in flue gas, but also solves the technical problem of low efficiency in the existing open absorption heat pump system.

[0026] In a typical embodiment of the present invention, the open absorption heat pump unit includes a high-pressure generator 1, a low-pressure generator 2, a first ejector 3, a second ejector 9, a condensed water storage tank 10, a water vapor condenser 11, a solution heat exchanger 4, a pump 6, a solution evaporator 8 and an open adiabatic absorption tower 5.

[0027] In this scheme, the open insulated absorption tower 5 includes a tower body 51, and the tower body 51 is provided with a flue gas inlet 52, a solution inlet 53, a solution outlet 54 and a flue gas outlet 55. The flue gas inlet 52 is located at the lower section of the side wall of the tower body 51, and the flue gas outlet 55 is arranged at the top of the tower body 51. The function of the flue gas inlet 52 is to introduce industrial waste gas (hot and wet flue gas) into the tower body 51, and the flue gas flows from bottom to top in the tower body 51 and is discharged from the tower body 51 to the outside through the flue gas outlet 55. A spraying part 19 and a packing layer 20 are arranged inside the tower body 51, wherein the spraying part 19 is connected with the pipeline of the solution inlet 53, the spraying part 19 includes a spraying pipe and a solution spray head is distributed on the spraying pipe, and the spraying part 19 is located above the packing layer 20, and the flue gas inlet 52 is located below the packing layer 20, the solution inlet 53 is located at the upper section of the side wall of the tower body 51, and the solution outlet 54 is located at the bottom of the tower body 51. With such a design, when the flue gas enters the interior of the open insulated absorption tower 5 from the flue gas inlet 52, the flue gas passes through the packing layer 20 from bottom to top, and the solution sprayed by the spray element 19 enters and passes through the packing layer 20 from top to bottom. The flue gas and the spray solution meet in the packing layer 20 and heat and mass transfer occur. The solution recovers the residual heat carried in the flue gas and realizes the drying treatment of the flue gas by recovering the residual moisture contained in the flue gas. The spray solution absorbs water vapor in the flue gas to form a dilute solution with lower concentration, and releases absorption heat to heat the dilute solution and the flue gas at the same time. After treatment, the moisture content of the flue gas is reduced and the temperature is increased.

[0028] In this scheme, the solution outlet 54 of the open adiabatic absorption tower 5 is divided into two branches, wherein the first branch is connected to the solution inlet 53 of the open adiabatic absorption tower 5 through a pump 6. More specifically, a solution cooler 7 is provided at the outlet of the pump 6. The solution cooler 7 is located outside the tower body 51 of the open adiabatic absorption tower 5. The solution cooler 7 includes a solution channel and a medium channel capable of realizing heat exchange, wherein the outlet of the pump 6 is connected to the solution channel of the solution cooler 7. The medium channel of the solution cooler 7 is used to be connected to an external heating water channel. The waste heat of the exhaust gas recovered by the solution in the solution channel is used to preheat the heating medium in the medium channel. Specifically, the inlet of the medium channel of the solution cooler 7 is connected to the heating return water pipe 101, and the outlet of the medium channel of the solution cooler 7 is connected to the heating drain pipe 102.

[0029] In this embodiment, a solution evaporator 8 is also included. The solution evaporator 8 is located outside the tower body 51 of the open adiabatic absorption tower 5. The solution evaporator 8 includes a solution channel and a refrigerant channel, wherein the inlet of the solution channel of the solution evaporator 8 is connected to the solution channel outlet of the solution cooler 7, and the solution channel outlet of the solution evaporator 8 is connected to the spray part 19 connected to the solution inlet 53 of the open adiabatic absorption tower 5, and the refrigerant channel of the solution evaporator 8 is connected to the refrigerant channel of the parallel compression heat pump unit, which is used to heat the refrigerant working medium in the refrigerant channel by the waste heat of the waste gas recovered by the solution, thereby fully utilizing the waste heat recovery of the waste gas. The open adiabatic absorption tower 5 of the present scheme is designed with a solution cooler 7 and a solution evaporator 8 in series outside the tower body 51, replacing the structure of the traditional open adiabatic absorption tower 5 in the prior art in which a water-cooled cooler is arranged inside the tower body 51. The heat and mass transfer processes of the solution absorbing water vapor are separated, so that the two processes are strengthened respectively. In addition, the present scheme increases the contact time and contact area of ​​the solution absorbing water vapor by arranging a packing layer 20 in the open adiabatic absorption tower 5, thereby further strengthening the heat and mass transfer processes of the solution absorbing water vapor.

[0030] In addition, a solution heat exchanger 4 is provided at the second branch of the solution outlet 54 at the bottom of the open adiabatic absorption tower 5. The function of the solution heat exchanger 4 is to preheat the dilute solution discharged from the open adiabatic absorption tower 5 by the concentrated solution that is about to enter the open adiabatic absorption tower 5, and then the preheated dilute solution will enter the generator for generation. Specifically, the solution heat exchanger 4 includes a concentrated solution channel and a dilute solution channel, wherein the inlet of the dilute solution channel is connected to the outlet at the bottom of the tower body of the open adiabatic absorption tower 5, and the outlet of the dilute solution channel is connected to the solution inlet of the high-pressure generator 1 and the low-pressure generator 2, respectively, for supplying the required generation solution to the high-pressure generator 1 and the low-pressure generator 2. The inlet of the concentrated solution channel is connected to the outlet of the first injector 3, for sending the mixed fluid injected by the first injector 3 to the spraying part 19 for spraying.

[0031] In this solution, the high-pressure generator 1 includes a solution inlet, a steam outlet and a solution outlet, the steam outlet of the high-pressure generator 1 is connected to the working fluid inlet of the second ejector 9, the solution outlet of the high-pressure generator 1 is connected to the working fluid inlet of the first ejector 3, the low-pressure generator 2 includes a solution inlet, a steam outlet and a solution outlet, the steam outlet of the low-pressure generator 2 is connected to the induced fluid inlet of the second ejector 9; the solution outlet of the low-pressure generator 2 is connected to the induced fluid inlet of the first ejector 3, the first ejector 3 is a liquid-liquid ejector, and the concentrated solution discharged from the high-pressure generator 1 is used as the working fluid to eject the concentrated solution discharged from the low-pressure generator 2, and the second ejector 9 is a steam-steam ejector, and the steam discharged from the high-pressure generator 1 is used as the working fluid to eject the steam discharged from the low-pressure generator 2.

[0032] In this embodiment, the condensed water storage tank 10 includes a steam inlet and a condensed water outlet. The condensed water storage tank 10 is in a closed state. The steam inlet of the condensed water storage tank 10 is connected to the outlet of the second ejector 9, and the condensed water outlet at the bottom of the condensed water storage tank 10 is connected to the industrial water supply pipe 103. A water vapor condenser 11 is arranged in the condensed water storage tank 10. The inlet end of the water vapor condenser 11 is connected to the outlet of the medium channel of the solution cooler 7. After the solution cooler 7 preheats the heating medium once by recovering the waste heat from the waste gas, the water vapor condenser 11 is used to perform secondary heating on the heating medium before sending it out. The waste heat of the waste gas recovered by the open double-effect absorption heat pump unit, a part of the waste heat of the waste gas is directly heated once by the solution cooler 7, and the other part of the waste heat of the waste gas is heated twice by the water vapor condenser 11 for hot water. The heat energy grade is improved by the parallel compression heat pump unit, thereby realizing the cascade heating process of the heating water.

[0033] In this embodiment, the outlet of the second ejector 9 is connected to the steam inlet of the condensed water storage tank 10, which is used to send the mixed steam discharged from the second ejector 9 into the condensed water storage tank 10 for condensation. The steam condensed water condensed by the water vapor condenser 11 can be used as industrial water replenishment. That is, the open double-effect absorption heat pump unit recovers the residual heat of the waste gas and generates water vapor through the high-pressure generator 1 and the low-pressure generator 2. The concentrated water vapor enters the condensed water storage tank 10 and condenses into condensed water, thereby realizing the orderly recovery and utilization of the residual heat and residual moisture of the waste gas. The generated condensed water is industrially replenished through the industrial water replenishment pipe 103, thereby realizing the utilization of the recovered residual moisture of the waste gas. This solution not only solves the waste heat recovery and drying treatment of the waste gas, but also the recovered residual heat can be used for heating heating water, and at the same time, it provides heat for the parallel compression heat pump unit. In addition, the residual moisture of the waste gas recovered during the drying process can also be used as industrial water replenishment, achieving energy saving and consumption reduction.

[0034] In this solution, the outlet of the first injector 3 is connected to the inlet of the concentrated solution channel of the solution heat exchanger 4, so as to send the mixed solution discharged from the first injector 3 into the solution inlet 53 of the open insulated absorption tower 5 through the concentrated solution channel, thereby realizing spray absorption treatment of the exhaust gas through the spray element 19.

[0035] More specifically, the open absorption heat pump unit includes a high pressure generator 1, a low pressure generator 2, a first ejector 3, a solution heat exchanger 4, an open adiabatic absorption tower 5, a pump 6, a solution evaporator 8, a second ejector 9, a condensed water storage tank 10 and a water vapor condenser 11. The bottom solution outlet of the open adiabatic absorption tower 5 is divided into two branches, one of which is connected in series with the solution cooler 7, the solution evaporator 8 and the spraying element 19 through the pump 6, and the other branch is connected to the inlet of the dilute solution channel of the solution heat exchanger 4, and the outlet of the dilute solution channel of the solution heat exchanger 4 is connected to the solution inlets of the high pressure generator 1 and the low pressure generator 2 respectively. The steam outlet of the high-pressure generator 1 is connected to the working fluid inlet of the second ejector 9, the steam outlet of the low-pressure generator 2 is connected to the induced fluid inlet of the second ejector 9, the mixed fluid outlet of the second ejector 9 is connected to the steam inlet of the condensed water storage tank 10, the concentrated solution outlet at the bottom of the high-pressure generator 1 is connected to the working fluid inlet of the first ejector 3, the concentrated solution outlet at the bottom of the low-pressure generator 2 is connected to the induced fluid inlet of the first ejector 3, and the mixed fluid outlet of the first ejector 3 is connected to the spray part 19 in the open insulated absorption tower 5 through the concentrated solution channel of the solution heat exchanger 4.

[0036] In this embodiment, the parallel compression heat pump unit uses the parallel compressor to produce dual-temperature heat energy from flue gas waste heat and external heat source heat to provide heating for the high-pressure generator 1 and the low-pressure generator 2. The parallel compression heat pump unit can adopt the following implementation structure: including a first compressor 12, a second compressor 13, a high-temperature solution condenser 14, a low-temperature solution condenser 15, a first throttling component 16, a second throttling component 17, an external heat source evaporator 18 and a solution evaporator 8, and the solution evaporator 8 is a common component of the parallel compression heat pump unit and the open absorption heat pump unit.

[0037] In this solution, the solution evaporator 8 includes a solution side channel and a refrigerant side channel capable of achieving heat exchange, the solution side channel inlet of the solution evaporator 8 is connected to the solution channel outlet of the solution cooler 7, the solution side channel outlet of the solution evaporator 8 is connected to the solution inlet 53 between the open adiabatic absorption tower 5, the refrigerant side channel inlet of the solution evaporator 8 is connected to the refrigerant channel outlet of the external heat source evaporator 18, and the refrigerant side channel outlet of the solution evaporator 8 is respectively connected to the suction ports of the first compressor 12 and the second compressor 13. The refrigerant working fluid of the parallel compression heat pump unit can recover the flue gas waste heat absorbed by the open absorption heat pump unit through the solution evaporator 8.

[0038] In this embodiment, the external heat source evaporator 18 includes a refrigerant side channel and an external heat source side channel 181 capable of achieving heat exchange. The inlet of the refrigerant channel of the external heat source evaporator 18 is respectively connected to the outlet of the first throttling component 16 and the second throttling component 17, and the outlet of the refrigerant channel of the external heat source evaporator 18 is respectively connected to the suction port of the first compressor 12 and the second compressor 13 through the solution evaporator 8. The refrigerant absorbs high-temperature heat energy from the external environment through the external heat source evaporator 18. The external heat source evaporator 18 is provided with heating by an external heat source. The heat source required for the external heat source side channel 181 can come from low-grade heat sources such as solar energy and industrial waste heat, or from energy or heat sources such as fuel oil, gas or steam. Thus, the above energy and heat sources are used to provide thermal energy for the refrigerant of the parallel compression heat pump unit.

[0039] Specifically, the first compressor 12 and the second compressor 13 are connected in parallel, the exhaust port of the first compressor 12, the high-temperature solution condenser 14, and the inlet of the first throttling component 16 are connected in series in sequence, wherein the high-temperature solution condenser 14 is built into the high-pressure generator 1 in a sealed state, and the exhaust port of the second compressor 13, the low-temperature solution condenser 15, and the inlet of the second throttling component 17 are connected in series in sequence, wherein the low-temperature solution condenser 15 is built into the low-pressure generator 2 in a sealed state. The outlets of the first throttling component 16 and the second throttling component 17 are both connected to the inlet of the refrigerant channel of the external heat source evaporator 18, the outlet of the refrigerant channel of the external heat source evaporator 18 is connected to the inlet of the refrigerant side channel of the solution evaporator 8, and the outlet of the refrigerant side channel of the solution evaporator 8 is connected to the air intake of the first compressor 12 and the second compressor 13, respectively.

[0040] The present invention also provides a heating method of a heat pump drying system, comprising an open absorption heat pump unit operation step and a parallel compression heat pump unit operation step; The operation steps of the open absorption heat pump unit include the following steps: The concentrated solution generated in the high-pressure generator 1 enters the first ejector 3 as a working fluid to draw out the concentrated solution generated in the low-pressure generator 2. After the mixed concentrated solution at the outlet of the first ejector 3 undergoes heat exchange with the dilute solution from the open adiabatic absorption tower 5, the concentrated solution then enters the open adiabatic absorption tower 5 for spraying to absorb water vapor in the flue gas to achieve flue gas drying. The concentrated solution becomes a dilute solution and releases absorption heat to heat the dilute solution and the flue gas. The water vapor generated by the high-pressure generator 1 enters the second ejector 9 as a working fluid to draw out the water vapor generated by the low-pressure generator 2. The mixed water vapor at the outlet of the second ejector 9 releases condensation heat and is condensed into liquid water. The dilute solution flowing out of the open adiabatic absorption tower 5 is divided into two branches, one of which is used to realize the step-by-step utilization of flue gas waste heat recovery. The other branch of the dilute solution is preheated by the mixed concentrated solution at the outlet of the first ejector 3, and the preheated dilute solution enters the generator to absorb heat and generate.

[0041] In this scheme, the concentrated solution generated and discharged in the high-pressure generator 1 of the open double-effect absorption heat pump unit enters the first ejector 3 as the working fluid to induce the concentrated solution generated and discharged in the low-pressure generator 2. The mixed concentrated solution at the outlet of the first ejector 3 is preheated by the solution heat exchanger 4 with the dilute solution from the open adiabatic absorption tower 5, and then enters the open adiabatic absorption tower 5 to spray and absorb the water vapor in the flue gas to become a dilute solution and release the absorption heat to heat the dilute solution and flue gas, so that the flue gas temperature increases and the moisture content decreases; the dilute solution flowing out of the open adiabatic absorption tower 5 is divided into two branches, one of which is preheated after entering the solution heat exchanger 4, and then enters the high-pressure generator 1 and the low-pressure generator 2 respectively. The water vapor generated by the high-pressure generator 1 enters the second ejector 9 as the working fluid to eject the water vapor generated by the low-pressure generator 2. The mixed water vapor at the outlet of the second ejector 9 enters the condensed water storage tank 10 to release the condensation heat and is condensed into liquid water to be used as industrial makeup water. At the same time, the secondary heating of the heating water is completed. The dilute solution in the other branch is sequentially sent to the solution cooler 7 by the pump 6 to preheat the heating water. The solution evaporator 8 serves as the low-temperature heat source of the parallel compression heat pump unit to heat the refrigerant to realize the vaporization of the refrigerant.

[0042] The operation steps of the parallel compression heat pump unit include the following steps: The refrigerant working medium of the parallel compression heat pump unit is divided into two paths, one of which is a gaseous refrigerant that is compressed by the first compressor 12 into a high-pressure, high-temperature superheated refrigerant vapor to complete a compression process with a high compression ratio, and then enters the high-temperature solution condenser 14 to provide the high-pressure generator 1 with the heat required for generation, and the high-pressure generator generates superheated water vapor with a first pressure value; the other gaseous refrigerant is compressed by the second compressor 13 into a relatively high-pressure, relatively high-temperature superheated refrigerant vapor to complete a compression process with a relatively high compression ratio, and then enters the low-temperature solution condenser 15 to provide the low-pressure generator 2 with the heat required for generation, and the low-pressure generator generates superheated water vapor with a second pressure value; the first pressure value is higher than the second pressure value; the refrigerant working medium discharged from the high-temperature solution condenser 14 and the low-temperature solution condenser 15 becomes a refrigerant working medium with the same pressure after throttling and reducing the pressure through the throttling component, and after absorbing the heat from the external heat source, returns to the suction port of the first compressor 12 and the second compressor 13 to complete the compression process. This solution uses a parallel compressor to extract dual-temperature heat energy to provide heating for the high-pressure generator 1 and the low-pressure generator 2, thereby eliminating the high-temperature heat source heating required by the traditional absorption heat pump generator.

[0043] In this scheme, in the operation steps of the parallel compression heat pump unit: the refrigerant medium passes through the external heat source evaporator 18 in sequence to absorb the heat of the external heat source, and the solution evaporator 8 recovers the waste heat of the flue gas to become low-temperature and low-pressure steam, wherein a part of the gaseous refrigerant medium is compressed by the first compressor 12 to become superheated steam with high temperature and high pressure to complete the compression process with a high compression ratio, and enters the high-temperature solution condenser 14 to provide heating for the high-pressure generator 1, and the high-pressure generator 1 generates superheated water vapor with a pressure higher than 0.1MPa, and the other part of the gaseous refrigerant medium is compressed by the second compressor 13 It becomes superheated steam with higher temperature and higher pressure to complete the compression process with higher compression ratio, and enters the low-temperature solution condenser 15 to provide heating for the low-pressure generator 2. The low-pressure generator 2 generates superheated steam with a pressure lower than 0.1MPa. The liquid refrigerant working medium from the high-temperature solution condenser 14 and the low-temperature solution condenser 15 respectively passes through the first throttling component 16 and the second throttling component 17 connected in parallel to become the working medium with the same pressure, and then enters the external heat source evaporator 18 and the solution evaporator 8 in turn to absorb the heat from the external heat source and recover the waste heat of the flue gas.

[0044] In this scheme, the circulating solution of the open absorption heat pump unit is a binary non-azeotropic mixture of salt and water, and the circulating solution adopts lithium chloride aqueous solution, calcium chloride aqueous solution, lithium bromide solution or potassium formate solution; the refrigerant working medium of the parallel compression heat pump unit is a mixed working medium composed of one or two or more HC or HFC refrigerants such as R32, R290, R600a, R1234yf.

[0045] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any form. Although the present invention has been disclosed as a preferred embodiment as above, it is not used to limit the present invention. Any technician familiar with this 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 modification, equivalent change and modification 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 still fall within the scope of the technical solution of the present invention.

Claims

1. A heat pump drying system, characterized in that: It comprises an open absorption heat pump unit and a parallel compression heat pump unit, wherein the parallel compression heat pump unit produces dual-temperature heat energy to provide the generator of the open absorption heat pump unit with the required heating amount; The open absorption heat pump unit comprises an open adiabatic absorption tower, a high pressure generator, a low pressure generator, a first ejector and a second ejector; The flue gas inlet of the open-type heat-insulating absorption tower is used to introduce the hot and humid flue gas to be treated; a spraying element and a packing layer are arranged in the open-type heat-insulating absorption tower, the spraying element is located above the packing layer, and the packing layer is located above the flue gas inlet; the spraying element is used to spray a solution to form a dilute solution with a lower concentration by absorbing water vapor in the hot and humid flue gas, and at the same time release absorption heat to heat the dilute solution and the flue gas; The bottom solution outlet of the open adiabatic absorption tower is divided into two branches; The first branch is connected to the solution inlet of the open adiabatic absorption tower through a pump; The second branch is connected to the inlet of the high-pressure generator and the inlet of the low-pressure generator respectively; The steam outlet of the high pressure generator is connected to the working fluid inlet of the second ejector, and the solution outlet of the high pressure generator is connected to the working fluid inlet of the first ejector; The steam outlet of the low-pressure generator is connected to the injection fluid inlet of the second ejector, and the solution outlet of the low-pressure generator is connected to the injection fluid inlet of the first ejector; The mixed fluid outlet of the second ejector is connected to the condensed water storage tank; the mixed fluid outlet of the first ejector is connected to the top solution inlet of the open adiabatic absorption tower, and the solution inlet of the open adiabatic absorption tower is connected to the spraying element.

2. A heat pump drying system according to claim 1, characterized in that: Also includes a solution heat exchanger; The inlet and outlet of the dilute solution channel of the solution heat exchanger are connected to the pipeline between the solution outlet and the generator inlet of the open adiabatic absorption tower; The inlet and outlet of the concentrated solution channel of the solution heat exchanger are connected to the pipeline between the mixed fluid outlet of the first ejector and the solution inlet of the open adiabatic absorption tower.

3. A heat pump drying system according to claim 1 or 2, characterized in that: The parallel compression heat pump unit comprises a first refrigerant channel and a second refrigerant channel arranged in parallel; The first refrigerant channel is provided with a first compressor, a high-temperature solution condenser and a first throttling component in series in sequence; The second refrigerant channel is provided with a second compressor, a low-temperature solution condenser and a second throttling component in series in sequence; The refrigerant medium throttled by the first throttling component and the second throttling component is divided into two paths after absorbing heat from an external heat source and heat provided by the open absorption heat pump unit, and enters the first compressor and the second compressor respectively.

4. A heat pump drying system according to claim 3, characterized in that: Also includes an external heat source evaporator; The inlet of the refrigerant channel of the external heat source evaporator is connected to the outlet of the first throttling component and the outlet of the second throttling component respectively; The outlet of the refrigerant channel of the external heat source evaporator is connected to the inlet of the first compressor and the inlet of the second compressor respectively.

5. A heat pump drying system according to claim 4, characterized in that: Also includes a solution evaporator; The solution evaporator is located outside the tower body of the open adiabatic absorption tower; The inlet and outlet of the solution channel of the solution evaporator are respectively connected to the pump outlet and the solution inlet of the open adiabatic absorption tower; The refrigerant channel inlet and outlet of the solution evaporator are respectively connected to the refrigerant channel outlet of the external heat source evaporator and the inlets of the first compressor and the second compressor.

6. A heat pump drying system according to claim 5, characterized in that: It also includes a solution cooler and a water vapor condenser; the solution cooler is located outside the tower body of the open adiabatic absorption tower; The solution cooler comprises a solution channel and a medium channel for realizing heat exchange, the inlet of the solution channel of the solution cooler is connected to the pump outlet, the outlet of the solution channel of the solution cooler is connected to the solution inlet of the open adiabatic absorption tower via the solution evaporator, the outlet of the medium channel of the solution cooler is connected to the inlet of the water vapor condenser, and the inlet of the medium channel is connected to the heating return pipe; The water vapor condenser is placed inside the condensate storage tank. The water vapor condenser is used to heat the heating medium passing through it and condense the steam in the condensate storage tank. The outlet of the water vapor condenser is connected to the heating drain pipe.

7. A heat pump drying system according to claim 6, characterized in that: The condensed water outlet of the condensed water storage tank is connected to the industrial water supply pipe, which is used to discharge the internal condensed water for industrial water supply.

8. A heating method for a heat pump drying system according to claim 7, characterized in that: The method comprises the steps of operating an open absorption heat pump unit and operating a parallel compression heat pump unit; The operation steps of the open absorption heat pump unit include the following steps: The concentrated solution generated in the high-pressure generator is used as a working fluid to enter the first ejector to eject the concentrated solution generated in the low-pressure generator. After the mixed concentrated solution at the outlet of the first ejector is heat-exchanged with the dilute solution from the open adiabatic absorption tower, the mixed concentrated solution at the outlet of the first ejector enters the open adiabatic absorption tower to absorb moisture and dry the flue gas and turn it into a dilute solution, while releasing absorption heat to heat the dilute solution and the flue gas. The water vapor with a first pressure value generated by the high-pressure generator enters the second ejector as a working fluid to eject the water vapor with a second pressure value generated by the low-pressure generator; the mixed water vapor at the outlet of the second ejector releases condensation heat and is condensed into liquid water; The dilute solution flowing out of the open adiabatic absorption tower is divided into two branches, one of which is used to realize the cascade utilization of the recovered flue gas waste heat; the other branch is preheated by the mixed concentrated solution at the outlet of the first ejector, and then enters the generator to absorb heat and generate.

9. A heating method for a heat pump drying system according to claim 8, characterized in that: The parallel compression heat pump unit operation steps include the following steps: The refrigerant working medium of the parallel compression heat pump unit is divided into two paths; wherein; A gaseous refrigerant is compressed by a first compressor into high-pressure, high-temperature, superheated refrigerant vapor to complete a high compression ratio compression process, and then enters a high-temperature solution condenser to provide heat required for the high-pressure generator to generate superheated water vapor of a first pressure value; The other gaseous refrigerant is compressed by the second compressor into a higher pressure, higher temperature superheated refrigerant vapor to complete a compression process with a higher compression ratio, and then enters the low-temperature solution condenser to provide the low-pressure generator with the heat required for generation, and the low-pressure generator generates superheated water vapor of a second pressure value; The liquid refrigerant discharged from the high-temperature solution condenser and the low-temperature solution condenser becomes a refrigerant of the same pressure after throttling and depressurization by the throttling component and returns to the suction port of the first compressor and the second compressor to complete the compression process after absorbing heat.

10. A heating method for a heat pump drying system according to claim 9, characterized in that: The liquid refrigerant discharged from the high-temperature solution condenser and the low-temperature solution condenser becomes a refrigerant of the same pressure after throttling and reducing the pressure through the throttling component, and after absorbing the heat from the external heat source and recovering the waste heat of the flue gas absorbed by the open absorption heat pump unit, returns to the suction port of the first compressor and the second compressor to complete the compression process.

11. A heating method for a heat pump drying system according to claim 9 or 10, characterized in that: The refrigerant medium of the parallel compression heat pump unit is a mixed medium composed of one or more of R32, R290, R600a, and R1234yf.

12. A heating method for a heat pump drying system according to any one of claims 8 to 10, characterized in that: The circulating solution of the open absorption heat pump unit is a binary non-azeotropic mixed working fluid composed of salt and water, and the circulating solution is a lithium chloride aqueous solution, a calcium chloride aqueous solution, a lithium bromide solution or a potassium formate solution.

Images