Absorption-compression type heat pump system for low-temperature waste heat recovery and control method of absorption-compression type heat pump system

Abstract

The invention relates to the technical field of industrial waste heat recovery and high-temperature heat energy supply, in particular to an absorption-compression type heat pump system for low-temperature waste heat recovery and a control method of the absorption-compression type heat pump system. The novel absorption-compression type heat pump system comprises a waste heat recovery system, an absorption system, a steam compression system and a load system. The invention further provides a control method of the novel absorption-compression type heat pump system. The problem that the temperature rise of a single heat pump system is limited can be solved, the requirement of an industrial high-temperature heat source is met, a low-temperature heat source can be directly utilized, multi-cycle efficient coupling is achieved, the comprehensive COP of the system is improved, and the operation safety and the compression efficiency of the system are improved. And environment-friendly working medium water is also adopted, so that the safety and the green performance are improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of industrial waste heat recovery and high-temperature heat supply, in particular to an absorption-compression heat pump system for low-temperature waste heat recovery and a control method thereof. BACKGROUND

[0002] Common heat pump recovery technologies include two categories: compression heat pump and absorption heat pump. The compression heat pump system has the advantages of high efficiency and compact structure, but its evaporator is usually limited to a higher evaporation temperature, which cannot directly utilize deep waste heat sources below the ambient temperature. The absorption heat pump system (especially the second type of absorption heat pump, i.e., the temperature-increasing absorption heat pump) can realize temperature-increasing utilization of low-temperature heat sources and is suitable for deep waste heat recovery. However, it has the following problems: high requirement for driving heat source (medium-high temperature heat source is required); limited temperature-increasing capacity, and the output temperature is difficult to meet the demand of high-grade heat utilization.

[0003] Therefore, some research attempts to use absorption heat pumps and compression heat pumps in combination, that is, to use the absorption system to preliminarily increase the temperature of the heat source, and then to use the compression system to further increase the temperature, so as to recover low-temperature waste heat and output high-temperature heat. However, most of the existing schemes are only used in series, and there is a lack of efficient energy coupling between the subsystems. The overall energy efficiency of the system is low, the structure is redundant, the economy is poor, and the heat transfer path is not optimized, which has problems such as large heat loss and low coupling efficiency.

[0004] Therefore, it is necessary to propose a new absorption-compression heat pump system and a control method thereof to realize efficient thermodynamic coupling between the two cycles and improve the overall performance of the system. SUMMARY

[0005] Through repeated experiments, the applicant found that the existing absorption-compression heat pump system has one or more of the following defects. 1. The temperature-increasing range of the absorption heat pump used alone is limited: the second type of absorption heat pump (temperature-increasing type) can recover heat sources with relatively low temperature, but the temperature of the output hot water is limited, which is usually difficult to meet the demand of some industrial processes for high-temperature heat sources. 2. The compression heat pump cannot directly utilize low-temperature heat sources: the evaporator of the compression heat pump system usually requires a higher evaporation temperature, and cannot effectively extract heat from lower-temperature waste heat, resulting in lower efficiency or even inability to operate. 3. In the existing system, the refrigerant working medium used by most compression heat pumps may have problems of flammability, safety, and environmental protection. 4. The waste heat only enters the evaporator of the absorption cycle, and the generator relies on steam or high-grade heat sources for a long time, resulting in low waste heat utilization rate. 5. The external medium usually only passes through single-stage preheating before entering the vapor compression circuit, and the compression ratio required by the compressor is large, resulting in high energy consumption. 6. The proportion of waste heat distribution is fixed, which is difficult to adapt to the fluctuations of heat side load and waste heat quality.

[0006] The present application aims to provide a novel absorption-compression heat pump system to eliminate one or more defects of the prior art. The present application also aims to provide a control method for the novel absorption-compression heat pump system.

[0007] To solve the above technical problems, the present application provides the following technical solutions.

[0008] In a first aspect, the present application provides a novel absorption-compression heat pump system, comprising a waste heat recovery system, an absorption system, a vapor compression system, and a load system. The waste heat recovery system comprises a waste heat diversion valve, a generator, a first evaporator, and a secondary preheater, and the fluid providing waste heat flows through the waste heat diversion valve, the generator, and the secondary preheater in sequence and then exits the waste heat recovery system. The absorption system comprises a first evaporator, a second evaporator, a first solution pump, a solution heat exchanger, a first condenser, a second solution pump, and a generator, and the fluid providing waste heat flows through the first evaporator, the generator, and the secondary preheater in sequence and then exits the waste heat recovery system. The refrigerant solution circulates between the generator, the solution heat exchanger, and the second evaporator. The first solution pump is arranged on the circulation pipeline of the refrigerant solution. The shell side of the second evaporator releases heat, and the tube side of the second evaporator is heated. The vapor compression system comprises a first evaporator and a second evaporator, a flash device, a first compressor, a second condenser, and a condensate return connected in a circulation manner. The first evaporator is used to deliver steam to the second evaporator. The load system comprises a primary preheater, a secondary preheater, a second condenser, and a gas-liquid separation device. The external fluid flows through the primary preheater, the secondary preheater, the second condenser, and the gas-liquid separation device in sequence to obtain steam and condensate water, and the steam is used by the user.

[0009] In an embodiment of the first aspect, the waste heat recovery system further comprises a waste heat circulating pump for inputting the fluid providing waste heat into the waste heat recovery system.

[0010] In an embodiment of the first aspect, the pipeline connecting the waste heat circulating pump and the generator and the pipeline connecting the first evaporator and the generator at least partially share a section of the pipeline.

[0011] In an embodiment of the first aspect, the absorption system further comprises a first condenser and a second solution pump arranged on the pipeline connecting the first evaporator and the generator.

[0012] In an embodiment of the first aspect, cooling water circulates between the primary preheater and the first condenser, and a second circulating pump for providing power and a second control valve for controlling the flow of cooling water are arranged on their circulation pipelines.

[0013] In an embodiment of the first aspect, the vapor compression system further comprises a first throttling valve arranged on the pipeline connecting the second condenser and the second evaporator.

[0014] In an embodiment of the first aspect, the flash device is in circulation with the second evaporator, and a first control valve is arranged on the connecting pipeline for controlling the amount of liquid in the flash device re-entering the tube side of the second evaporator.

[0015] In an embodiment of the first aspect, the condensed water from the gas-liquid separation device is returned to the second condenser.

[0016] In the second aspect, the application provides a novel control method of an absorption-compression heat pump system, which is applied to the novel absorption-compression heat pump system as described in the first aspect, and comprises the following steps: S1: inputting user steam demand and error to the main controller; S2: starting the inner loop control to adjust the speed of the first compressor for realizing fast pressure / temperature stabilization; or, S3: starting the outer loop control, inputting the split ratio r of the waste heat split valve to the distribution controller, starting the vapor compression cycle process, or the regeneration or preheating process; wherein the vapor compression cycle process comprises: evaporating the refrigerant in the tube side of the second evaporator to obtain steam, and delivering the steam to the second condenser after being heated by the first compressor; wherein the regeneration or preheating process comprises: under the power provided by the first solution pump, delivering the refrigerant solution in the generator to the solution heat exchanger, and finally into the shell side of the second evaporator.

[0017] In an embodiment of the second aspect, the control method of the novel absorption-compression heat pump system further comprises the following steps: S4: making the external water flow through the second condenser, being heated by the steam from the second evaporator, and then entering the gas-liquid separation device for separation to obtain steam and condensed water, and the steam is heated by the second compressor for user use.

[0018] In an embodiment of the second aspect, the control method of the novel absorption-compression heat pump system further comprises the following steps: S5: returning the condensed water in the gas-liquid separation device to the second condenser.

[0019] Compared with the prior art, the positive effect of the application is that the application can break through the problem of limited temperature rise of a single heat pump system, meet the demand of industrial high-temperature heat source, directly utilize low-temperature heat source, realize multi-cycle efficient coupling, improve the comprehensive COP of the system, and improve the operation safety and compression efficiency of the system. The application also adopts the environmentally friendly working medium water to improve the safety and green performance. BRIEF DESCRIPTION OF DRAWINGS

[0020] In order to more clearly illustrate the implementation manners of the embodiments of the application, the related drawings will be briefly introduced below. It can be understood that the drawings described below are only used to illustrate some implementation manners of the embodiments of the application, and those skilled in the art can also obtain many other technical features and connection relationships not mentioned in the present application according to the drawings.

[0021] Figure 1 A novel absorption-compression heat pump system according to the present application is shown.

[0022] In Figure 1 In the drawings, the meanings of the reference signs are as follows: 1, first evaporator; 2, generator; 3, first condenser; 4, second evaporator; 5, flash device; 6, gas-liquid separation device; 7, first-stage preheater; 8, second-stage preheater; 9, second condenser; 10, waste heat circulating pump; 11, waste heat shunt valve; 12, second solution pump; 13, solution heat exchanger; 14, second throttling valve; 15, first solution pump; 16, condensate return pump; 17, first control valve; 18, first compressor; 19, first throttling valve; 20, second control valve; 21, second water pump; 22, first water pump; 23, second compressor; 24, third control valve. DETAILED DESCRIPTION

[0023] Unless otherwise defined, technical or scientific terms used in the specification and claims of the present application should be interpreted as is customary in the art to which this application pertains.

[0024] In the description of the present application, it should be understood that the terms "center", "longitudinal", "transverse", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only used to facilitate the description of the present application and simplify the description, and therefore cannot be understood as indicating or implying that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the present application.

[0025] In addition, the terms "first", "second", etc. are used only for descriptive purposes and should not be construed as indicating or implying relative importance or an indicated number of the technical features indicated. Therefore, the features defined with "first", "second", etc. can explicitly or implicitly include one or more of the features. In the description of the present application, the meaning of "a plurality of" is two or more, unless otherwise specified.

[0026] In the description of the present application, it should be noted that, unless otherwise explicitly specified and limited, the terms "mounting", "connection", "connection" should be understood broadly, for example, it can be connected, or detachable connection, or integrally connected; it can be mechanical connection, or electrical connection; it can be directly connected, or indirectly connected through intermediate medium, it can be the communication inside two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood through specific circumstances.

[0027] The technical solutions of the present application will be described clearly and completely in the following with reference to the drawings and examples of the present application.

[0028] Reference Figure 1 The present application provides a new absorption-compression heat pump system, which comprises a waste heat recovery system, an absorption system, a vapor compression system, and a load system.

[0029] The waste heat recovery system comprises a waste heat diversion valve 11, a generator 2, a first evaporator 1 and a two-stage preheater 8, and the fluid for providing waste heat flows through the waste heat diversion valve 11, the generator 2 and the two-stage preheater 8 in turn and then discharges from the waste heat recovery system.

[0030] The absorption system comprises a first evaporator 1, a second evaporator 4, a first condenser 3, a second solution pump 12, a first solution pump 15, a solution heat exchanger 13 and a generator 2. The fluid for providing waste heat flows through the first evaporator 1, the generator 2 and the two-stage preheater 8 in turn and then discharges from the waste heat recovery system. In addition, the refrigerant solution circulates between the generator 2, the solution heat exchanger 13 and the second evaporator 4. The shell side of the second evaporator 4 is heat-released, and the tube side of the second evaporator 4 is heated. The absorption system can further comprise a first condenser 3 and a second solution pump 12 arranged on the pipeline connecting the first evaporator 1 and the generator 2.

[0031] The vapor compression system comprises a second evaporator 4, a flash device 5, a first compressor 18, a second condenser 9 and a condensate return pump 16. The first evaporator 1 is used to deliver steam to the second evaporator 4. The vapor compression system can further comprise a first throttling valve 19 arranged on the pipeline connecting the second condenser 9 and the second evaporator 4.

[0032] The load system comprises a first preheater 7, a second preheater 8, a second condenser 9 and a gas-liquid separation device 6. The external fluid flows through the first preheater 7, the second preheater 8, the second condenser 9 and the gas-liquid separation device 6 in sequence, to obtain steam and condensed water. The steam is used by the user. The condensed water is returned to the second condenser 9.

[0033] In one embodiment, the industrial hot fluid is delivered to the first evaporator 1 and the generator 2 by a waste heat circulating pump 10. The first evaporator 1 is used to evaporate the refrigerant by using the waste heat. The generator is used to heat the concentrated solution to desorb the refrigerant by using the waste heat. In one embodiment, a waste heat shunt valve 11 can be arranged on the connecting pipeline between the waste heat circulating pump 10 and the first evaporator 1 or between the waste heat circulating pump 10 and the generator 2, to adjust the amount of industrial hot fluid entering the first evaporator 1 and the generator 2. The industrial hot fluid flowing through the first evaporator 1 is cooled, and then flows into the generator 2 to recover the remaining heat. The industrial hot fluid flowing through the generator 2 is cooled, and then flows through the second preheater 8 to preheat the external fluid by using the tail end of the waste heat. The pipeline connecting the waste heat circulating pump 10 and the generator 2 and the pipeline connecting the first evaporator 1 and the generator 2 at least partially share a section of the pipeline.

[0034] The absorption-compression heat pump system described herein is an absorption-coupled compression cycle structure. The refrigerant used in the absorption end is still LiBr-H2O, so there are concentrated and dilute solutions. In the compression end, the refrigerant used is water.

[0035] In one embodiment, the steam generated in the first evaporator 1 enters the second evaporator 4. In the second evaporator 4, the shell side absorbs heat and the tube side water evaporates. In other words, the steam in the shell of the second evaporator 4 absorbs the heat from the concentrated solution from the solution heat exchanger 13 and releases heat, while heating the water flowing through the pipeline arranged in the second evaporator 4 to obtain water vapor, which enters the downstream flash device 5. The concentrated solution stored in the generator 2 is delivered to the solution heat exchanger 13 by the first solution pump 15 and eventually reaches the second evaporator 4. In the second evaporator 4, the concentrated solution is changed into a dilute solution because the water vapor becomes condensed water. The dilute solution stored in the second evaporator 4 is further delivered to the solution heat exchanger 13 to exchange heat with the concentrated solution, and then returns to the generator 2 through the second throttling valve 14. It should be noted that the first solution pump 15 can be arranged at any position in the circulation loop. In one embodiment, the absorption system can further comprise a first condenser 3 arranged on the pipeline connecting the first evaporator 1 and the generator 2, for cooling the refrigerant. In addition, a second solution pump 12 can also be arranged on the pipeline connecting the first evaporator 1 and the generator 2, to provide power for the circulation of the refrigerant.

[0036] In one embodiment, cooling water can be circulated between the first preheater 7 and the first condenser 3, and a second circulating pump 21 for providing power and a second control valve 20 for controlling the flow of cooling water can be provided on their circulating pipelines.

[0037] In one embodiment, the second evaporator 4, the flash device 5, the first compressor 18, the second condenser 9 and the condensate return pump 16 are connected in circulation to complete a vapor compression cycle. The first throttling valve 19 is provided on the pipeline connecting the second condenser 9 and the second evaporator 4. In a specific embodiment, the flash device 5 can also be connected in circulation with the second evaporator 4, and a first control valve 17 for controlling the amount of liquid in the flash device 5 re-entering the tube side of the second evaporator 4 can be provided on their connecting pipeline.

[0038] In one embodiment, the novel absorption-compression heat pump system described herein further comprises an external load system. The external fluid is made to flow through the first preheater 7, the second preheater 8, the second condenser 9 and the gas-liquid separation device 6 in sequence by the first water pump 22, to obtain steam and condensate water, and the steam is provided to the user. The condensate water can be returned to the second condenser 9. In a specific embodiment, the steam can be warmed by the second compressor 23 before being provided to the user. In one embodiment, a third control valve 24 for controlling the return and makeup of condensate water can be provided on the pipeline connecting the second condenser 9 and the gas-liquid separation device 6.

[0039] Next, the control method of the novel absorption-compression heat pump system described herein will be described in detail.

[0040] In the control of the novel absorption-compression heat pump system described herein, the main control quantity includes the second condenser 9 steam side supply parameter—pressure / saturation priority, Psteam,sec. The main execution quantity includes the split ratio r =m1 / (m1+m2) of the waste heat split valve 11 for distributing the waste heat between the first evaporator 1 and the generator 2. m1 represents the mass of the industrial heat fluid flowing into the first evaporator 1, and m2 represents the mass of the industrial heat fluid flowing into the generator 2. The auxiliary execution quantity includes the load of the first compressor 18; the waste heat circulating pump 10 / first water pump 22 / variable frequency (flow stabilizing), the second throttling valve 14 (solution bypass / return stabilizing concentration), the first control valve 17 (steam superheat adjustment), and the third control valve 24 (condensate water return / makeup).

[0041] The start-stop and operation steps of the novel absorption-compression heat pump system described herein are as follows.

[0042] Cold start (sequential control SFC) 1. System self-check and interlock setting: liquid level, pressure, temperature, solution concentration / density probe online; valve position feedback normal; safety valve available.

[0043] 2. Open the open circuit water side first water pump 22, small flow of external fluid (such as water) flows through the first preheater 7, the second preheater 8 and the second condenser 9 in turn, and the waste heat circulating pump 10 is started (low frequency), and a small cycle of the waste heat side is established; the first solution pump 15 is started (low frequency) to establish the circulation of the absorption solution, so that the refrigerant solution realizes circulation among the generator 2, the first solution pump 15, the solution heat exchanger 13 and the second evaporator 4.

[0044] 3. The second solution pump 12 (refrigerant passage) and the condensate return pump 16 (condensate returns to the second evaporator 4) are started, and the second throttling valve 14 is set to a small opening degree (to prevent crystallization and stabilize the return flow).

[0045] 4. The cooling water enters the second evaporator 4 absorber, and the outlet solution temperature of the second evaporator 4 is controlled to be greater than or equal to the crystallization line + ΔT safety margin (typically 5-10K).

[0046] 5. The waste heat diversion valve 11 is adjusted (small diversion ratio r value) to gradually allow more waste heat into the first evaporator 1, and after the first evaporator 1 stabilizes evaporation, the second evaporator 4 tube side begins to evaporate steam.

[0047] 6. The first compressor 18 is started (low speed), and the closed loop PIC: Psteam adjusts the equipment first compressor 18.

[0048] 7. The gas-liquid separation device 6 and the superheating control of the second compressor 23 are put into operation, the liquid level of the gas-liquid separation device 6 is confirmed to be normal, the separation efficiency meets the standard, and the user is connected to the grid.

[0049] B. Normal operation (cascade + proportional distribution + constraint) Main loop: Main control Tsteam,sec (or Psteam,sec) → DCC output target r → waste heat diversion valve 11.

[0050] Inner loop: The first compressor 18 uses PIC / TIC to keep the second condenser 9 side pressure / temperature, and compensates for high frequency fluctuations.

[0051] Feedforward: The instantaneous steam flow ms of the user side, the open circuit raw water temperature Tin, and the waste heat inlet temperature Twas are detected, and the feedforward correction is made to r and the component first compressor 18 to reduce overshoot.

[0052] Limiting / anti-saturation: When the generator 2 or the second evaporator 4 approaches the crystallization line or the shell side temperature of the second evaporator 4 is too high, the diversion ratio r is reduced, the opening degree of the second throttling valve 14 is increased, the power of the first solution pump 15 is increased to dilute the circuit, and if necessary, the operation of the component first compressor 18 is reduced.

[0053] Quality / Quality: The liquid level of the gas-liquid separator 6 is controlled by LIC, and the gas-liquid separator 6 is returned to the second condenser 9; the excessive liquid carrying / humidity alarm interlocks the second compressor 23 to reduce superheat and ensure steam quality.

[0054] C. Rapid load changes (load tracking) When a deviation in the main control quantity occurs, the speed of the first compressor 18 is quickly adjusted (faster in the inner loop) to stabilize the pressure / temperature on the second condenser 9 side; the flow ratio r of the waste heat diversion valve 11 is simultaneously adjusted (slower in the outer loop) to shift the system's new "thermal balance point" to a higher / lower absorption + vaporization combined capacity; if the feedforward detects a significant change in the opening degree of the user's steam valve group, r and the speed of the first compressor 18 are adjusted in advance in small steps to avoid overshoot.

[0055] D. Normal shutdown Remove the load on the user side (or switch back to the standby boiler); gradually reduce the speed of the first compressor 18 to the minimum, keep the waste heat diversion valve 11 back to the preheating side (generator 2) as the main function, and reduce the load on the first evaporator 1; maintain the first solution pump 15 / waste heat circulation pump 10 for a period of time (cold circulation) to ensure that the generator 2 or the second evaporator 4 does not fall into the crystallization zone; close the refrigerant passage valve group, stop the pump at zero speed, and finally close the open-circuit side valve and drain the low point.

[0056] The main measurement points and loops of the control method described in this article include: TIC-9: Secondary side steam temperature of the second condenser 9 (or PIC-09: pressure) → Main setpoint; DCC-11: Distribution controller (output split ratio r) → opening degree of waste heat split valve 11; PIC / TIC-18: Second condenser 9 shell-side pressure / temperature → First compressor 18 frequency; FIC-10 / 15: Waste heat circulation pump 10 / first solution pump 15 flow maintenance (cavitation prevention / maintaining circulation ΔP); LIC-6: Gas-liquid separator 6 liquid level → drain / return valve; QIC-4: Absorber heat release monitoring for the second evaporator 4 (for redundancy / optimization); ρ-2 / concentration-2: Solution concentration / density of generator 2 online → crystallization protection logic; DP-4, TT-1 / 2: Differential pressure and critical temperature points → Safety and model feedforward.

[0057] In one specific embodiment, the control method for the novel absorption-compression heat pump system described herein includes the following steps: S1: input user steam demand (set temperature / pressure) and error to master controller TIC / PIC-09; S2: start inner loop control, adjust the rotating speed of the first compressor 18, for realizing fast pressure / temperature stabilization; or, S3: start outer loop control, input the split ratio r of the waste heat split valve 11 to the distribution controller DCC-11, start the steam compression cycle process, or the regeneration or preheating process; wherein the steam compression cycle process comprises: evaporating the refrigerant in the second evaporator 4 tube side to obtain steam, and delivering the steam to the second condenser 9 after being heated by the first compressor 18; wherein the regeneration or preheating process comprises: under the power provided by the first solution pump 15, delivering the refrigerant solution in the generator 2 to the solution heat exchanger 13, and finally into the second evaporator 4 shell side.

[0058] In one specific embodiment, the control method of the new absorption-compression heat pump system described herein further comprises the following steps: S4: making the external water flow through the second condenser 9, after being heated by the steam from the second evaporator 4, entering the gas-liquid separation device 6 for separation to obtain steam and condensed water, and the steam being heated by the second compressor 23 for user use.

[0059] In one specific embodiment, the control method of the new absorption-compression heat pump system described herein further comprises the following steps: S5: making the condensed water in the gas-liquid separation device 6 backflow to the second condenser 9 to supplement water for the second condenser 9.

[0060] The application scenarios of the new absorption-compression heat pump system described herein include the integration of SIP / CIP steam and process hot water in food / beverage factories.

[0061] The demand characteristics include strong production paragraphs, steam short-time peak (sterilization / disinfection 120-140℃ saturated or slightly superheated steam), and the need for 60-90℃ process hot water / hot cleaning in the remaining period.

[0062] The available waste heat includes cleaning / preheating section drainage (40-70℃), refrigeration and compressor cooling water (35-45℃), and part of the tail gas / ventilation waste heat.

[0063] System docking: 1. Distribute the low-temperature waste heat by the waste heat split valve 11 first: part of it enters the generator 2 to raise the solution temperature (improve the absorption capacity of the second evaporator 4), and part of it enters the first evaporator 1 to directly produce refrigerant steam (enhance the steam supply of the second evaporator 4 tube side evaporation); 2. The first compressor 18 lifts the second evaporator 4 tube side steam to the second condenser 9 to condense and release heat, forming an open circuit steam / hot water dual output: 3. Steam (open circuit): Second condenser 9→ Gas-liquid separation device 6→ Second compressor 23, for SIP / CIP or packaging section sterilization; 4. Hot water (closed circuit): The second condenser 9 condenses and releases heat to the process hot water plate, stabilizing at 60-80°C.

[0064] 5. Through temperature control of the second condenser 9, power control of the compressor 18, and waste heat diversion valve 11, the dual-time-scale regulation of "steam peak fast compensation + diversion slow migration" is realized.

[0065] Expected benefits: Compared with only using a boiler, the hybrid system uses waste heat "pavement base", and the compressor does "peak lifting", so the boiler's appearance rate is significantly reduced; Steam quality control is more stable (compressor internal ring pressure stabilization + gas-liquid separation device 06 to ensure dryness); Comprehensive COP improvement: low load on the absorption side, high load on the steam side, and higher overall energy efficiency throughout the year.

[0066] In summary, the present application has the following beneficial effects.

[0067] 1. Overcome the problem of limited temperature rise of traditional absorption heat pumps The present application adopts a two-stage temperature rise structure, which first raises the low-temperature waste heat to medium temperature through an absorption heat transformation sub-cycle (temperature rise type second absorption heat pump), and then further raises the heat to a high temperature section through a compression heat pump cycle, thereby breaking through the problem of limited temperature rise of a single heat pump system and meeting the demand for industrial high-temperature heat sources.

[0068] 2. Overcome the problem that compression heat pumps cannot directly utilize low-temperature heat sources The present application provides a stable medium-temperature evaporation environment for the compression side through pre-stage temperature rise processing on the absorption side, avoiding the compression heat pump from directly working under low-temperature heat source conditions, thereby ensuring its efficient operation.

[0069] 3. Realize multi-cycle efficient coupling and improve the overall COP of the system The multi-cycle transfers heat through the shared second evaporator 4, directly drives the compression side evaporation through absorption heat release, reduces intermediate heat exchange equipment and heat transfer paths, reduces system heat loss, and improves thermal matching, thereby fundamentally overcoming the problems of large heat loss and low efficiency of traditional series coupling structures. And through the temperature rise of the two-stage compressor, the compressor pressure ratio can be reduced, the compressor load can be reduced, the compressor efficiency can be improved, and a larger temperature rise can be achieved.

[0070] 4. Solve the problem of unstable compressor inlet and liquid hammer risk By setting a flash tank in the compression loop, vapor / liquid separation is achieved, ensuring that superheated water vapor enters the compressor, avoiding liquid water entering the compressor causing liquid knock, improving system operation safety and compression efficiency.

[0071] 5. Using environmentally friendly working fluid water to improve safety and green performance The entire system only uses water as the only circulating working fluid, which is non-toxic, non-corrosive, and non-flammable, while avoiding the greenhouse effect and environmental regulation restrictions of traditional working fluids, and has good popularization prospects.

[0072] 6. System energy efficiency is significantly improved By fully utilizing the solution heat exchanger to recover heat, optimizing the fluid path and circulating pressure distribution, the system can minimize thermodynamic irreversibility, with overall COP better than traditional single-cycle or loosely coupled double-cycle heat pump structure, with significant energy-saving effect and operation economy.

[0073] 7. Two-stage water preheating and evaporation path: External water is first preheated by a primary preheater to absorb heat from the absorber, and then by a secondary preheater to absorb residual heat at the tail end, significantly reducing the subsequent evaporation and compression load.

[0074] 8. Dynamic waste heat diversion valve 11: By simply using PID, the first evaporator 1 and the generator 2 can be automatically switched according to the load, and the system will greatly improve the waste heat temperature and the steam demand will also be applicable to a wider operating condition range.

[0075] The above description of the embodiments is to facilitate the understanding and application of the application by those of ordinary skill in the art. Those skilled in the art can easily make various modifications to these embodiments, and apply the general principles described herein to other embodiments without having to exert creative labor. Therefore, the present application is not limited to the embodiments described herein, and those skilled in the art can make improvements and modifications based on the disclosure without departing from the scope and spirit of the application.

Claims

1. A novel absorption-compression heat pump system, characterized by, The system comprises a waste heat recovery system, an absorption system, a vapor compression system, and a load system. The waste heat recovery system comprises a waste heat diversion valve, a generator, a first evaporator, and a secondary preheater, and is configured to allow a waste heat providing fluid to sequentially flow through the waste heat diversion valve, the generator, and the secondary preheater, and then to be discharged from the waste heat recovery system. The absorption system comprises the first evaporator, a second evaporator, a first solution pump, a solution heat exchanger, a first condenser, a second solution pump, and the generator, and is configured to allow the waste heat providing fluid to sequentially flow through the first evaporator, the generator, and the secondary preheater, and then to be discharged from the waste heat recovery system, and to allow a refrigerant solution to circulate between the generator, the solution heat exchanger, and the second evaporator, and to allow the first solution pump to be arranged on a circulation pipeline of the refrigerant solution, and to allow the shell side of the second evaporator to release heat, and to allow the tube side of the second evaporator to be heated. The vapor compression system comprises the first evaporator, and a second evaporator, a flash device, a first compressor, a second condenser, and a condensate return, which are connected in a circulation manner, and is configured to allow the first evaporator to supply steam to the second evaporator. The load system comprises a primary preheater, the secondary preheater, the second condenser, and a gas-liquid separation device, and is configured to allow an external fluid to sequentially flow through the primary preheater, the secondary preheater, the second condenser, and the gas-liquid separation device, to obtain steam and condensate water, and to allow the steam to be supplied to a user.

2. The novel absorption-compression heat pump system according to claim 1, wherein, The waste heat recovery system further comprises a waste heat circulation pump configured to input the waste heat providing fluid into the waste heat recovery system.

3. The novel absorption-compression heat pump system according to claim 2, wherein, A pipeline connecting the waste heat circulation pump and the generator and a pipeline connecting the first evaporator and the generator at least partially share a same pipeline.

4. The novel absorption-compression heat pump system according to claim 1, wherein, The absorption system further comprises the first condenser and the second solution pump arranged on the pipeline connecting the first evaporator and the generator.

5. The novel absorption-compression heat pump system according to claim 4, wherein Cooling water circulates between the primary preheater and the first condenser, and a second circulation pump configured to provide power and a second control valve configured to control the flow of the cooling water are arranged on circulation pipelines of the primary preheater and the first condenser.

6. The novel absorption-compression heat pump system according to claim 1, wherein, The vapor compression system further comprises a first throttling valve arranged on a pipeline connecting the second condenser and the second evaporator.

7. The novel absorption-compression heat pump system according to claim 1, wherein, The flash device is in circulation communication with the second evaporator, and a first control valve configured to control the amount of liquid in the flash device re-entering the tube side of the second evaporator is arranged on a connecting pipeline of the flash device and the second evaporator.

8. The novel absorption-compression heat pump system according to claim 1, wherein, The condensate water from the gas-liquid separation device returns to the second condenser.

9. A novel control method of an absorption-compression heat pump system, characterized by, The application is applied to the novel absorption-compression heat pump system as claimed in any one of claims 1-8, and comprises the following steps: S1: inputting user steam demand and error to a main controller; S2: starting inner ring control, adjusting the rotating speed of the first compressor, and realizing fast pressure / temperature stabilization; or S3: starting outer ring control, inputting a diversion ratio r of the waste heat diversion valve to a distribution controller, starting a vapor compression circulation process, or a regeneration or preheating process; The vapor compression circulation process comprises: evaporating the refrigerant in the tube side of the second evaporator to obtain steam, and supplying the steam to the second condenser after the steam is heated by the first compressor; The regeneration or preheating process comprises: under the power provided by the first solution pump, supplying the refrigerant solution in the generator to the solution heat exchanger, and finally to the shell side of the second evaporator.

10. The control method of the novel absorption-compression heat pump system according to claim 9, characterized by, The application further comprises the following steps: S4: the external water flows through the second condenser, is heated by the steam from the second evaporator, enters the gas-liquid separation device for separation to obtain steam and condensed water, and the steam is heated by the second compressor and supplied to the user; Preferably, further comprising the steps of: S5: the condensed water in the gas-liquid separation device is returned to the second condenser.

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