Indirect double-effect jet type heat pump system and control method

Abstract

The invention relates to an indirect double-effect jet type heat pump system and a control method.The system comprises a first-stage heat pump loop and a second-stage heat pump loop, and the first-stage heat pump loop comprises a first generator, a first ejector, a first economizer, a first gas-liquid separator, a first liquid storage tank and a first evaporator which are sequentially connected; the first generator is connected with a waste water heat source to form a heat extraction loop, the second-stage heat pump loop comprises a second generator, a second ejector, a second economizer, a second gas-liquid separator, a second liquid storage tank and a second evaporator which are sequentially connected, and the second generator is connected in a pipeline between the first gas-liquid separator and the first liquid storage tank in series; the pipeline between the second gas-liquid separator and the second liquid storage tank is connected with a condenser in series, the condenser is connected with a heat supply tail end to form a heat supply loop, the first evaporator and the second evaporator are connected with each other and are correspondingly connected with a flue gas heat source and an exhaust pipe, and the system has the advantages of being convenient to operate and control and good in stability; the method has the advantages of simple process, safety and reliability.

Description

Technical Field

[0001] The present invention relates to a heat pump system, in particular to an indirect double-effect ejector heat pump system with two-stage heat pumps connected in series, and a control method for the system. Background Art

[0002] With the development of economy and society, the significance of energy conservation has become increasingly prominent. During the industrial development process, a large amount of high-temperature wastewater (low-grade heat energy) is often directly discharged into the environment without energy recovery and utilization, resulting in energy waste; at the same time, the flue gas (waste gas) generated by gas boilers contains a large amount of latent heat, and the vast majority of this latent heat in the flue gas is also directly discharged, which also causes energy waste and will cause a certain amount of thermal pollution to the environment. As an air conditioner or heating device, a heat pump has certain technical advantages in the recovery and utilization of industrial waste heat (high-temperature wastewater, flue gas) and can generate good economic benefits. Compared with traditional heat pumps, an ejector heat pump uses an ejector to replace the compressor and has the advantages of simple structure, reliable operation, high thermal efficiency, and energy conservation. However, when the ejector heat pump works, it is driven by a high-level heat source and supplies heat by recovering the heat of a low-level heat source. Due to the large temperature difference between the high-level heat source and the low-level heat source, the expansion ratio (mainstream fluid pressure / secondary fluid pressure) and shock wave loss of the ejector heat pump are relatively large, which affects the ejector efficiency and the COP of the overall system. Summary of the Invention

[0003] The purpose of the present invention is to provide an indirect double-effect ejector heat pump system and a control method. The system has the advantages of simple structure, convenient operation, good stability, and high safety; the method has the advantages of simple process, safety, and reliability.

[0004] To solve the above problems existing in the prior art, the present invention provides an indirect double-effect ejector heat pump system, including a first generator, a first ejector, a first economizer, a first gas-liquid separator, a first liquid storage tank, a first evaporator, a second generator, a second ejector, a second economizer, a second gas-liquid separator, a second liquid storage tank, a second evaporator and a condenser. The primary side of the first generator is connected to a waste water heat source to form a heat extraction loop. The secondary side outlet of the first generator is connected to the main stream inlet of the first ejector through a first working medium pipeline. The outlet of the first ejector is connected to the primary side inlet of the first economizer through a second working medium pipeline. The primary side outlet of the first economizer is connected to the inlet of the first gas-liquid separator through a third working medium pipeline. The liquid phase outlet and the gas phase outlet of the first gas-liquid separator are respectively connected to the first liquid storage tank through a fourth working medium pipeline and a fifth working medium pipeline. The first liquid storage tank is connected to the secondary side inlet of the first economizer and the secondary side inlet of the first evaporator through a sixth working medium pipeline and a seventh working medium pipeline respectively. A first working medium pump and a first throttle valve are respectively arranged on the sixth working medium pipeline and the seventh working medium pipeline. The secondary side outlet of the first economizer is connected to the secondary side inlet of the first generator through an eighth working medium pipeline. The secondary side outlet of the first evaporator is connected to the secondary flow inlet of the first ejector through a ninth working medium pipeline. The primary side inlet of the first evaporator is connected to a flue gas heat source. The primary side outlet of the first evaporator is connected to the primary side inlet of the second evaporator. An exhaust pipe is connected to the primary side outlet of the second evaporator. The primary side of the second generator is connected in series in the fifth working medium pipeline. The secondary side outlet of the second generator is connected to the main stream inlet of the second ejector through a tenth working medium pipeline. The outlet of the second ejector is connected to the primary side inlet of the second economizer through an eleventh working medium pipeline. The primary side outlet of the second economizer is connected to the inlet of the second gas-liquid separator through a twelfth working medium pipeline. The liquid phase outlet and the gas phase outlet of the second gas-liquid separator are respectively connected to the second liquid storage tank through a thirteenth working medium pipeline and a fourteenth working medium pipeline. The second liquid storage tank is connected to the secondary side inlet of the second economizer and the secondary side inlet of the second evaporator through a fifteenth working medium pipeline and a sixteenth working medium pipeline respectively. A second working medium pump and a second throttle valve are respectively arranged on the fifteenth working medium pipeline and the sixteenth working medium pipeline. The secondary side outlet of the second economizer is connected to the secondary side inlet of the second generator through a seventeenth working medium pipeline. The secondary side outlet of the second evaporator is connected to the secondary flow inlet of the second ejector through an eighteenth working medium pipeline. The primary side of the condenser is connected in series in the fourteenth working medium pipeline. The secondary side of the condenser is connected to a heat supply end to form a heat supply loop.

[0005] Optionally, the indirect double-effect ejector heat pump system of the present invention further includes a subcooler. The primary side of the subcooler is connected to a cold water source to form a cooling loop. The secondary side of the subcooler is connected in series in the seventh working medium pipeline.

[0006] Further, for an indirect double-effect ejector heat pump system of the present invention, the first throttle valve is disposed on the seventh refrigerant pipeline between the subcooler and the first evaporator.

[0007] Optionally, an indirect double-effect ejector heat pump system of the present invention further includes a subcooler. The primary side of the subcooler is connected in series in the eighteenth refrigerant pipeline, and the secondary side of the subcooler is connected in series in the sixteenth refrigerant pipeline.

[0008] Further, for an indirect double-effect ejector heat pump system of the present invention, the second throttle valve is disposed on the sixteenth refrigerant pipeline between the subcooler and the second evaporator.

[0009] Further, for an indirect double-effect ejector heat pump system of the present invention, temperature sensors T 1 and T 2 are respectively disposed at two ports of the primary side of the first generator. Temperature sensors T 3 and T 4 are respectively disposed at two ports of the secondary side of the condenser.

[0010] Further, for an indirect double-effect ejector heat pump system of the present invention, a temperature sensor T 5 and a pressure sensor P 1 are disposed at the main stream inlet of the first ejector. A pressure sensor P 2 is disposed at the outlet of the first ejector.

[0011] Further, for an indirect double-effect ejector heat pump system of the present invention, a temperature sensor T 6 and a pressure sensor P 3 are disposed at the main stream inlet of the second ejector. A pressure sensor P 4 is disposed at the outlet of the second ejector.

[0012] Further, for an indirect double-effect ejector heat pump system of the present invention, a temperature sensor T 7 is disposed at the inlet of the primary side of the first evaporator. A temperature sensor T 8 is disposed at the outlet of the primary side of the second evaporator.

[0013] Based on the same concept, the present invention further provides a control method for the above-mentioned indirect double-effect ejector heat pump system, including the following steps:

[0014] S1. Start the system, and let the heat extraction loop, the heat supply loop, the primary heat pump loop, and the secondary heat pump loop operate in circulation. Flue gas continuously flows through the primary sides of the first evaporator and the second evaporator. Among them, the fluid in the heat extraction loop is wastewater, the fluid in the heat supply loop is water or antifreeze, simply referred to as the heat supply fluid, and the fluid in the primary heat pump loop and the secondary heat pump loop is refrigerant. The primary heat pump loop includes a primary main circuit formed by sequentially connecting the secondary side of the first generator, the first ejector, the primary side of the first economizer, the first gas-liquid separator, the first liquid storage tank, and the secondary side of the first economizer, and a primary secondary circuit formed by sequentially connecting the first ejector, the primary side of the first economizer, the first gas-liquid separator, the first liquid storage tank, and the secondary side of the first evaporator. The secondary heat pump loop includes a secondary main circuit formed by sequentially connecting the secondary side of the second generator, the second ejector, the primary side of the second economizer, the second gas-liquid separator, the second liquid storage tank, and the secondary side of the second economizer, and a secondary secondary circuit formed by sequentially connecting the second ejector, the primary side of the second economizer, the second gas-liquid separator, the second liquid storage tank, and the secondary side of the second evaporator.

[0015] S2. The wastewater transfers heat to the refrigerant through the first generator, the flue gas transfers heat to the refrigerant through the first evaporator and the second evaporator, the refrigerant transfers heat to the heat supply fluid through the condenser, and the heat supply fluid transfers heat to the heat supply end through the heat supply loop.

[0016] S3. The saturated liquid refrigerant flowing through the first generator absorbs heat and becomes high-pressure refrigerant vapor. The high-pressure refrigerant vapor enters the first ejector and mixes with the low-pressure refrigerant vapor from the first evaporator. The refrigerant vapor flowing out of the first ejector releases heat through the first economizer and becomes a refrigerant gas-liquid two-phase fluid. The refrigerant gas-liquid two-phase fluid is processed by the first gas-liquid separator and is divided into saturated liquid refrigerant and saturated vapor refrigerant. The saturated liquid refrigerant directly enters the first liquid storage tank. The saturated vapor refrigerant flows through the second generator, releases heat, and becomes saturated liquid refrigerant and enters the first liquid storage tank. A part of the saturated liquid refrigerant in the first liquid storage tank is pumped and pressurized by the first working medium pump and then enters the first economizer to absorb heat and increase in temperature. The saturated liquid refrigerant after pressurization and temperature increase enters the first generator to absorb heat and vaporize. Another part of the saturated liquid refrigerant in the first liquid storage tank is throttled and depressurized by the first throttle valve and then enters the first evaporator to absorb heat and vaporize;

[0017] S4. The refrigerant saturated liquid flowing through the second generator absorbs heat and turns into high-pressure refrigerant vapor. The high-pressure refrigerant vapor enters the second ejector and mixes with the low-pressure refrigerant vapor from the second evaporator. The refrigerant vapor flowing out of the second ejector absorbs heat in the second economizer and turns into a refrigerant gas-liquid two-phase fluid. The refrigerant gas-liquid two-phase fluid is processed by the second gas-liquid separator and is divided into refrigerant saturated liquid and refrigerant saturated vapor. The refrigerant saturated liquid directly enters the second liquid storage tank. The refrigerant saturated vapor flows through the condenser, releases heat, turns into refrigerant saturated liquid, and enters the second liquid storage tank. A part of the refrigerant saturated liquid in the second liquid storage tank is pumped and pressurized by the second working medium pump and then enters the second economizer to absorb heat and increase in temperature. The refrigerant saturated liquid after pressurization and temperature increase enters the second generator to absorb heat and vaporize. Another part of the refrigerant saturated liquid in the second liquid storage tank is throttled and depressurized by the second throttle valve and then enters the second evaporator to absorb heat and vaporize.

[0018] Compared with the prior art, an indirect double-effect ejector heat pump system and a control method thereof according to the present invention have the following advantages: By providing a first generator, a first ejector, a first economizer, a first gas-liquid separator, a first liquid storage tank, a first evaporator, a second generator, a second ejector, a second economizer, a second gas-liquid separator, a second liquid storage tank, a second evaporator and a condenser, the primary side of the first generator is connected to a waste heat source to form a heat extraction loop. The secondary side outlet of the first generator is connected to the main stream inlet of the first ejector through a first working medium pipeline. The outlet of the first ejector is connected to the primary side inlet of the first economizer through a second working medium pipeline. The primary side outlet of the first economizer is connected to the inlet of the first gas-liquid separator through a third working medium pipeline. The liquid phase outlet and the gas phase outlet of the first gas-liquid separator are respectively connected to the first liquid storage tank through a fourth working medium pipeline and a fifth working medium pipeline. The first liquid storage tank is connected to the secondary side inlet of the first economizer and the secondary side inlet of the first evaporator through a sixth working medium pipeline and a seventh working medium pipeline respectively. The secondary side outlet of the first economizer is connected to the secondary side inlet of the first generator through an eighth working medium pipeline. The secondary side outlet of the first evaporator is connected to the secondary flow inlet of the first ejector through a ninth working medium pipeline. Among them, a first working medium pump and a first throttle valve are respectively provided on the sixth working medium pipeline and the seventh working medium pipeline. The primary side inlet of the first evaporator is connected to a flue gas heat source. The primary side outlet of the first evaporator is connected to the primary side inlet of the second evaporator. The primary side outlet of the second evaporator is connected with an exhaust pipe. The primary side of the second generator is connected in series in the fifth working medium pipeline. The secondary side outlet of the second generator is connected to the main stream inlet of the second ejector through a tenth working medium pipeline. The outlet of the second ejector is connected to the primary side inlet of the second economizer through an eleventh working medium pipeline. The primary side outlet of the second economizer is connected to the inlet of the second gas-liquid separator through a twelfth working medium pipeline. The liquid phase outlet and the gas phase outlet of the second gas-liquid separator are respectively connected to the second liquid storage tank through a thirteenth working medium pipeline and a fourteenth working medium pipeline. The second liquid storage tank is connected to the secondary side inlet of the second economizer and the secondary side inlet of the second evaporator through a fifteenth working medium pipeline and a sixteenth working medium pipeline respectively. The secondary side outlet of the second economizer is connected to the secondary side inlet of the second generator through a seventeenth working medium pipeline. The secondary side outlet of the second evaporator is connected to the secondary flow inlet of the second ejector through an eighteenth working medium pipeline. Among them, a second working medium pump and a second throttle valve are respectively provided on the fifteenth working medium pipeline and the sixteenth working medium pipeline. The primary side of the condenser is connected in series in the fourteenth working medium pipeline. The secondary side of the condenser is connected to a heat supply end to form a heat supply loop. Thus, an indirect double-effect ejector heat pump system with a simple structure, convenient operation, good stability and high safety is formed.In practical applications, after the system is started, the heat extraction loop, the heat supply loop, the primary heat pump loop, and the secondary heat pump loop will operate in a cycle, and the flue gas will continuously flow through the primary sides of the first evaporator and the second evaporator. Among them, the fluid in the heat extraction loop is wastewater, the fluid in the heat supply loop is water or antifreeze, simply referred to as the heat supply fluid, and the fluid in the primary heat pump loop and the secondary heat pump loop is refrigerant. When the system operates, the wastewater will continuously transfer heat to the refrigerant through the first generator, the flue gas will continuously transfer heat to the refrigerant through the first evaporator and the second evaporator, the refrigerant will continuously transfer heat to the heat supply fluid through the condenser, and the heat supply fluid will continuously transfer heat to the heat supply end through the heat supply loop. By setting up two-stage ejector heat pumps connected indirectly, the present invention utilizes the first generator to recover the heat energy in the wastewater and use it as the driving force, and utilizes the first evaporator and the second evaporator to recover the heat energy in the flue gas and use it as the heat of the secondary flow refrigerant of the vaporization ejector, realizing the deep recovery and utilization of industrial waste heat. By using the first economizer and the second economizer to conduct heat exchange on the refrigerant flowing through them, the irreversible losses caused by the heat exchange temperature difference in the first generator, the second generator, and the condenser are reduced. Compared with the existing ejector heat pump system, the expansion ratio of a single ejector is reduced, the internal loss of the ejector is reduced, the cascade utilization of energy is realized, the ejector efficiency and the overall COP of the system are improved. The heat pump system control method provided by the present invention has the advantages of simple process, safety and reliability.

[0019] The following further describes in detail an indirect double-effect ejector heat pump system and a control method thereof according to the present invention with reference to the specific embodiments shown in the drawings. Brief Description of the Drawings

[0020] Figure 1 It is a schematic structural diagram of the first embodiment of an indirect double-effect ejector heat pump system according to the present invention;

[0021] Figure 2 It is a schematic structural diagram of the second embodiment of an indirect double-effect ejector heat pump system according to the present invention;

[0022] Figure 3 It is a schematic structural diagram of the third embodiment of an indirect double-effect ejector heat pump system according to the present invention. Specific Embodiments

[0023] First of all, it should be noted that the orientation words such as up, down, left, right, front, and back described in the present invention are only for description according to the drawings for easy understanding, and do not limit the technical solutions and the scope of claims of the present invention.

[0024] As Figure 1The first embodiment of an indirect double-effect ejector heat pump system of the present invention is shown, including a first generator 1, a first ejector 2, a first economizer 3, a first gas-liquid separator 4, a first liquid storage tank 5, a first evaporator 6, a second generator 7, a second ejector 8, a second economizer 9, a second gas-liquid separator 10, a second liquid storage tank 11, a second evaporator 12 and a condenser 13. Connect the primary side of the first generator 1 to the waste heat source to form a heat extraction loop. Connect the secondary side outlet of the first generator 1 to the main stream inlet of the first ejector 2 through the first working medium pipeline 14. Connect the outlet of the first ejector 2 to the primary side inlet of the first economizer 3 through the second working medium pipeline 15. Connect the primary side outlet of the first economizer 3 to the inlet of the first gas-liquid separator 4 through the third working medium pipeline 16. Connect the liquid phase outlet and the gas phase outlet of the first gas-liquid separator 4 to the first liquid storage tank 5 through the fourth working medium pipeline 17 and the fifth working medium pipeline 18 respectively. Connect the first liquid storage tank 5 to the secondary side inlet of the first economizer 3 and the secondary side inlet of the first evaporator 6 through the sixth working medium pipeline 19 and the seventh working medium pipeline 20 respectively. Connect the secondary side outlet of the first economizer 3 to the secondary side inlet of the first generator 1 through the eighth working medium pipeline 23. Connect the secondary side outlet of the first evaporator 6 to the secondary flow inlet of the first ejector 2 through the ninth working medium pipeline 24. Among them, a first working medium pump 21 and a first throttle valve 22 are respectively provided on the sixth working medium pipeline 19 and the seventh working medium pipeline 20. Connect the primary side inlet of the first evaporator 6 to the flue gas heat source. Connect the primary side outlet of the first evaporator 6 to the primary side inlet of the second evaporator 12. An exhaust pipe is connected to the primary side outlet of the second evaporator 12. Connect the primary side of the second generator 7 in series in the fifth working medium pipeline 18. Connect the secondary side outlet of the second generator 7 to the main stream inlet of the second ejector 8 through the tenth working medium pipeline 25. Connect the outlet of the second ejector 8 to the primary side inlet of the second economizer 9 through the eleventh working medium pipeline 26. Connect the primary side outlet of the second economizer 9 to the inlet of the second gas-liquid separator 10 through the twelfth working medium pipeline 27. Connect the liquid phase outlet and the gas phase outlet of the second gas-liquid separator 10 to the second liquid storage tank 11 through the thirteenth working medium pipeline 28 and the fourteenth working medium pipeline 29 respectively. Connect the second liquid storage tank 11 to the secondary side inlet of the second economizer 9 and the secondary side inlet of the second evaporator 12 through the fifteenth working medium pipeline 30 and the sixteenth working medium pipeline 31 respectively. Connect the secondary side outlet of the second economizer 9 to the secondary side inlet of the second generator 7 through the seventeenth working medium pipeline 34. Connect the secondary side outlet of the second evaporator 12 to the secondary flow inlet of the second ejector 8 through the eighteenth working medium pipeline 35. Among them, a second working medium pump 32 and a second throttle valve 33 are respectively provided on the fifteenth working medium pipeline 30 and the sixteenth working medium pipeline 31. Connect the primary side of the condenser 13 in series in the fourteenth working medium pipeline 29. Connect the secondary side of the condenser 13 to the heat supply end to form a heat supply loop.

[0025] Through the above settings, an indirect double-effect ejector heat pump system with a simple structure, convenient operation, good stability and high safety is formed. In practical applications, after the system is started, the heat extraction circuit, the heat supply circuit, the first-stage heat pump circuit and the second-stage heat pump circuit will operate in a cycle, and the flue gas will continuously flow through the primary sides of the first evaporator 6 and the second evaporator 12. Among them, the fluid in the heat extraction circuit is wastewater, the fluid in the heat supply circuit is water or antifreeze, simply referred to as the heat supply fluid, and the fluid in the first-stage heat pump circuit and the second-stage heat pump circuit is refrigerant. During the operation of the system, the wastewater will continuously transfer heat to the refrigerant through the first generator 1, the flue gas will continuously transfer heat to the refrigerant through the first evaporator 6 and the second evaporator 12, the refrigerant will continuously transfer heat to the heat supply fluid through the condenser 13, and the heat supply fluid will continuously transfer heat to the heat supply end through the heat supply circuit. By setting two-stage ejector heat pumps connected indirectly, the present invention utilizes the first generator 1 to recover the thermal energy in the wastewater and use it as the driving force, and utilizes the first evaporator 6 and the second evaporator 12 to recover the thermal energy in the flue gas and use it as the heat of the secondary flow refrigerant of the vapor ejector, realizing the deep recovery and utilization of industrial waste heat. By using the first economizer 3 and the second economizer 8 to conduct heat exchange on the refrigerant flowing through them, the irreversible losses caused by the heat exchange temperature difference in the first generator 1, the second generator 7 and the condenser 13 are reduced. Compared with the existing ejector heat pump system, the expansion ratio of a single ejector is reduced, the internal loss of the ejector is reduced, the cascade utilization of energy is realized, the ejector efficiency and the overall COP of the system are improved. It should be noted that the first-stage heat pump circuit includes a first main flow circuit formed by sequentially connecting the secondary side of the first generator 1, the first ejector 2, the primary side of the first economizer 3, the first gas-liquid separator 4, the first liquid storage tank 5, and the secondary side of the first economizer 3, and a first secondary flow circuit formed by sequentially connecting the first ejector 2, the primary side of the first economizer 3, the first gas-liquid separator 4, the first liquid storage tank 5, and the secondary side of the first evaporator 6; the second-stage heat pump circuit includes a second main flow circuit formed by sequentially connecting the secondary side of the second generator 7, the second ejector 8, the primary side of the second economizer 9, the second gas-liquid separator 10, the second liquid storage tank 11, and the secondary side of the second economizer 9, and a second secondary flow circuit formed by sequentially connecting the second ejector 8, the primary side of the second economizer 9, the second gas-liquid separator 10, the second liquid storage tank 11, and the secondary side of the second evaporator 12.The flow and heat transfer process of the refrigerant in the primary heat pump loop are as follows: The saturated liquid refrigerant flowing through the first generator 1 absorbs heat and becomes high-pressure refrigerant vapor. The high-pressure refrigerant vapor enters the first ejector 2 and mixes with the low-pressure refrigerant vapor from the first evaporator 6. The refrigerant vapor flowing out of the first ejector 2 releases heat when flowing through the first economizer 3 and becomes a refrigerant gas-liquid two-phase fluid. The refrigerant gas-liquid two-phase fluid is processed by the first gas-liquid separator 4 and is divided into saturated liquid refrigerant and saturated vapor refrigerant. The saturated liquid refrigerant directly enters the first liquid storage tank 5. The saturated vapor refrigerant releases heat when flowing through the second generator 7 and becomes saturated liquid refrigerant and enters the first liquid storage tank 5. A part of the saturated liquid refrigerant in the first liquid storage tank 5 is pumped and pressurized by the first working fluid pump 21 and then enters the first economizer 3 to absorb heat and increase in temperature. The saturated liquid refrigerant after being pressurized and heated enters the first generator 1 to absorb heat and vaporize, and becomes high-pressure refrigerant vapor. Another part of the saturated liquid refrigerant in the first liquid storage tank 5 is throttled and depressurized by the first throttle valve 22 and then enters the first evaporator 6 to absorb heat and vaporize, and becomes low-pressure refrigerant vapor. The flow and heat transfer process of the refrigerant in the secondary heat pump loop are as follows: The saturated liquid refrigerant flowing through the second generator 7 absorbs heat and becomes high-pressure refrigerant vapor. The high-pressure refrigerant vapor enters the second ejector 8 and mixes with the low-pressure refrigerant vapor from the second evaporator 12. The refrigerant vapor flowing out of the second ejector 8 releases heat when flowing through the second economizer 9 and becomes a refrigerant gas-liquid two-phase fluid. The refrigerant gas-liquid two-phase fluid is processed by the second gas-liquid separator 10 and is divided into saturated liquid refrigerant and saturated vapor refrigerant. The saturated liquid refrigerant directly enters the second liquid storage tank 11. The saturated vapor refrigerant releases heat when flowing through the condenser 13 and becomes saturated liquid refrigerant and enters the second liquid storage tank 11. A part of the saturated liquid refrigerant in the second liquid storage tank 11 is pumped and pressurized by the second working fluid pump 32 and then enters the second economizer 8 to absorb heat and increase in temperature. The saturated liquid refrigerant after being pressurized and heated enters the second generator 7 to absorb heat and vaporize, and becomes high-pressure refrigerant vapor. Another part of the saturated liquid refrigerant in the second liquid storage tank 11 is throttled and depressurized by the second throttle valve 33 and then enters the second evaporator 12 to absorb heat and vaporize, and becomes low-pressure refrigerant vapor. Additionally, it should be noted that the wastewater in this document refers to high-temperature industrial wastewater containing a large amount of thermal energy.

[0026] As Figure 2 shown in the second embodiment of an indirect double-effect ejector heat pump system of the present invention, different from the first embodiment, a subcooler 36 is added in the second embodiment. Among them, the primary side of the subcooler 36 is connected to a cold water source to form a cooling loop, and the secondary side of the subcooler 36 is connected in series in the seventh working fluid pipeline 20. The first throttle valve 22 is arranged on the seventh working fluid pipeline 20 between the subcooler 36 and the first evaporator 6. This embodiment uses the subcooler 36 to cool down the refrigerant in the seventh working fluid pipeline 20, which can effectively prevent vapor from entering the first throttle valve 22 and improve the stability and reliability. AsFigure 3 The third embodiment of an indirect double-effect ejector heat pump system according to the present invention is shown. Different from the first embodiment, a subcooler 36 is also added in the third embodiment. Among them, the primary side of the subcooler 36 is connected in series in the eighteenth refrigerant pipeline 35, and the secondary side of the subcooler 36 is connected in series in the sixteenth refrigerant pipeline 31. The second throttle valve 33 is arranged on the sixteenth refrigerant pipeline 31 between the subcooler 36 and the second evaporator 12. This embodiment uses the subcooler 36 to conduct heat exchange between the refrigerant at the outlet of the second evaporator 12 and the refrigerant entering the second throttle valve 33, so that the temperature of the refrigerant at the inlet of the throttle valve 8 is reduced, which can also prevent steam from entering the second throttle valve 33 and improve the stability and reliability.

[0027] In practical applications, for the convenience of parameter detection and control, temperature sensors T 1 and temperature sensors T 2 are correspondingly arranged at both ports on the primary side of the first generator 1, temperature sensors T 3 and temperature sensors T 4 are correspondingly arranged at both ports on the secondary side of the condenser 13, temperature sensors T 5 and a pressure sensor P 1 are arranged at the main flow inlet of the first ejector 2, a pressure sensor P 2 is arranged at the outlet of the first ejector 2, temperature sensors T 6 and a pressure sensor P 3 are arranged at the main flow inlet of the second ejector 8, a pressure sensor P 4 is arranged at the outlet of the second ejector 8, temperature sensors T 7 is arranged at the inlet of the primary side of the first evaporator 6, and temperature sensors T 8 is arranged at the outlet of the primary side of the second evaporator 12; and controllers respectively connected to the temperature sensors T 1 , temperature sensors T 2 , temperature sensors T 3 , temperature sensors T 4 , temperature sensors T 5 , temperature sensors T 6 , temperature sensors T 7 , temperature sensors T 8 , pressure sensors P 1 , pressure sensors P 2 , pressure sensors P 3 and pressure sensors P 4 are provided.

[0028] Based on the same concept, the present invention also provides a control method for an indirect double-effect ejector heat pump system, which specifically includes the following steps:

[0029] S1. Start the system, and let the heat extraction loop, the heat supply loop, the first-stage heat pump loop, and the second-stage heat pump loop operate in circulation. Flue gas continuously flows through the primary sides of the first evaporator 6 and the second evaporator 12. Among them, the fluid in the heat extraction loop is wastewater, the fluid in the heat supply loop is water or antifreeze, simply referred to as the heat supply fluid, and the fluid in the first-stage heat pump loop and the second-stage heat pump loop is refrigerant. The first-stage heat pump loop includes a first-stage main flow loop formed by sequentially connecting the secondary side of the first generator 1, the first ejector 2, the primary side of the first economizer 3, the first gas-liquid separator 4, the first liquid storage tank 5, and the secondary side of the first economizer 3, and a first-stage secondary flow loop formed by sequentially connecting the first ejector 2, the primary side of the first economizer 3, the first gas-liquid separator 4, the first liquid storage tank 5, and the secondary side of the first evaporator 6. The second-stage heat pump loop includes a second-stage main flow loop formed by sequentially connecting the secondary side of the second generator 7, the second ejector 8, the primary side of the second economizer 9, the second gas-liquid separator 10, the second liquid storage tank 11, and the secondary side of the second economizer 9, and a second-stage secondary flow loop formed by sequentially connecting the second ejector 8, the primary side of the second economizer 9, the second gas-liquid separator 10, the second liquid storage tank 11, and the secondary side of the second evaporator 12.

[0030] S2. The wastewater transfers heat to the refrigerant through the first generator 1, the flue gas transfers heat to the refrigerant through the first evaporator 6 and the second evaporator 12, the refrigerant transfers heat to the heat supply fluid through the condenser 13, and the heat supply fluid transfers heat to the heat supply end through the heat supply loop.

[0031] S3. The saturated liquid refrigerant flowing through the first generator 1 absorbs heat and becomes high-pressure refrigerant vapor. The high-pressure refrigerant vapor enters the first ejector 2 and mixes with the low-pressure refrigerant vapor from the first evaporator 6. The refrigerant vapor flowing out of the first ejector 2 flows through the first economizer 3 and releases heat to become a refrigerant gas-liquid two-phase fluid. The refrigerant gas-liquid two-phase fluid is processed by the first gas-liquid separator 4 and is divided into saturated liquid refrigerant and saturated vapor refrigerant. The saturated liquid refrigerant directly enters the first liquid storage tank 5. The saturated vapor refrigerant flows through the second generator 7, releases heat, becomes saturated liquid refrigerant, and enters the first liquid storage tank 5. A part of the saturated liquid refrigerant in the first liquid storage tank 5 is pumped and pressurized by the first working medium pump 21 and then enters the first economizer 3 to absorb heat and increase in temperature. The saturated liquid refrigerant after pressurization and temperature increase enters the first generator 1 to absorb heat and vaporize. Another part of the saturated liquid refrigerant in the first liquid storage tank 5 is throttled and depressurized by the first throttle valve 22 and then enters the first evaporator 6 to absorb heat and vaporize.

[0032] S4. The refrigerant saturated liquid flowing through the second generator 7 absorbs heat and turns into high-pressure refrigerant vapor. The high-pressure refrigerant vapor enters the second ejector 8 and mixes with the low-pressure refrigerant vapor from the second evaporator 12. The refrigerant vapor at the outlet of the second ejector 8 flows through the second economizer 9, releases heat and turns into a refrigerant gas-liquid two-phase fluid. The refrigerant gas-liquid two-phase fluid is processed by the second gas-liquid separator 10 and is divided into refrigerant saturated liquid and refrigerant saturated vapor. The refrigerant saturated liquid directly enters the second liquid storage tank 11. The refrigerant saturated vapor flows through the condenser 13, releases heat and turns into refrigerant saturated liquid and enters the second liquid storage tank 11. A part of the refrigerant saturated liquid in the second liquid storage tank 11 is pumped and pressurized by the second working fluid pump 32 and then enters the second economizer 8 to absorb heat and increase in temperature. After the refrigerant saturated liquid is pressurized and heated, it enters the second generator 7 to absorb heat and vaporize. Another part of the refrigerant saturated liquid in the second liquid storage tank 11 is throttled and depressurized by the second throttle valve 33 and then enters the second evaporator 12 to absorb heat and vaporize.

[0033] The control method of the indirect double-effect ejector heat pump system provided by the present invention has the advantages of simple process, safety and reliability.

[0034] The above embodiments are only descriptions of the preferred embodiments of the present invention, and do not limit the scope of the claims of the present invention. Without departing from the design concept of the present invention, various deformations made by those skilled in the art according to the technical solution of the present invention should fall within the protection scope determined by the claims of the present invention.

Claims

1. An indirect double-effect jet heat pump system, characterized in that: The invention comprises a first generator (1), a first ejector (2), a first economizer (3), a first gas-liquid separator (4), a first liquid storage tank (5), a first evaporator (6), a second generator (7), a second ejector (8), a second economizer (9), a second gas-liquid separator (10), a second liquid storage tank (11), a second evaporator (12) and a condenser (13); the primary side of the first generator (1) is connected to a wastewater heat source to form a heat extraction circuit; the secondary side outlet of the first generator (1) is connected to the mainstream inlet of the first ejector (2) through a first working fluid pipeline (14); the outlet of the first ejector (2) is connected to the primary side inlet of the first economizer (3) through a second working fluid pipeline (15); the primary side outlet of the first economizer (3) is connected to the primary side outlet of the first economizer (3); The inlet of the first gas-liquid separator (4) is connected to the inlet of the first gas-liquid separator (4) through a third working fluid pipeline (16); the liquid phase outlet and the gas phase outlet of the first gas-liquid separator (4) are connected to the first liquid storage tank (5) through a fourth working fluid pipeline (17) and a fifth working fluid pipeline (18) respectively; the first liquid storage tank (5) is connected to the secondary side inlet of the first economizer (3) and the secondary side inlet of the first evaporator (6) through a sixth working fluid pipeline (19) and a seventh working fluid pipeline (20) respectively; the sixth working fluid pipeline (19) and the seventh working fluid pipeline (20) are provided with a first working fluid pump (21) and a first throttle valve (22) respectively; the secondary side outlet of the first economizer (3) is connected to the secondary side inlet of the first generator (1) through an eighth working fluid pipeline (23); the first evaporator (6) is connected to the secondary side outlet of the first economizer (3) through an eighth working fluid pipeline (23); The secondary side outlet of the second generator (6) is connected to the secondary flow inlet of the first ejector (2) through the ninth working fluid pipeline (24), the primary side inlet of the first evaporator (6) is connected to the flue gas heat source, the primary side outlet of the first evaporator (6) is connected to the primary side inlet of the second evaporator (12), the primary side outlet of the second evaporator (12) is connected to the exhaust pipe, the primary side of the second generator (7) is connected in series with the fifth working fluid pipeline (18), the secondary side outlet of the second generator (7) is connected to the mainstream inlet of the second ejector (8) through the tenth working fluid pipeline (25), the outlet of the second ejector (8) is connected to the primary side inlet of the second economizer (9) through the eleventh working fluid pipeline (26), the primary side outlet of the second economizer (9) is connected to the primary side outlet of the second economizer (9) through the twelfth working fluid pipeline (28), and the secondary side outlet of the second generator (7) is connected to the primary side inlet of the second economizer (9) through the twelfth working fluid pipeline (29). The second gas-liquid separator (10) is connected to a gas pipeline (27) and an inlet of the second gas-liquid separator (10); the liquid phase outlet and the gas phase outlet of the second gas-liquid separator (10) are connected to the second liquid storage tank (11) through a thirteenth working fluid pipeline (28) and a fourteenth working fluid pipeline (29) respectively; the second liquid storage tank (11) is connected to the secondary side inlet of the second economizer (9) and the secondary side inlet of the second evaporator (12) through a fifteenth working fluid pipeline (30) and a sixteenth working fluid pipeline (31) respectively; a second working fluid pump (32) and a second throttle valve (33) are provided on the fifteenth working fluid pipeline (30) and the sixteenth working fluid pipeline (31) respectively; the secondary side outlet of the second economizer (9) is connected to the secondary side inlet of the second generator (7) through a seventeenth working fluid pipeline (34);The secondary side outlet of the second evaporator (12) is connected to the secondary flow inlet of the second ejector (8) through the eighteenth working medium pipeline (35), the primary side of the condenser (13) is connected in series to the fourteenth working medium pipeline (29), and the secondary side of the condenser (13) is connected to the heating terminal to form a heating circuit.

2. The indirect double-effect jet heat pump system according to claim 1, characterized in that: It also includes a subcooler (36), wherein the primary side of the subcooler (36) is connected to a cold water source to form a cooling circuit, and the secondary side of the subcooler (36) is connected in series to the seventh working fluid pipeline (20).

3. The indirect double-effect jet heat pump system according to claim 2, characterized in that: The first throttle valve (22) is arranged on the seventh working medium pipeline (20) between the subcooler (36) and the first evaporator (6).

4. The indirect double-effect jet heat pump system according to claim 1, characterized in that: It also includes a subcooler (36), wherein the primary side of the subcooler (36) is connected in series to the eighteenth working fluid pipeline (35), and the secondary side of the subcooler (36) is connected in series to the sixteenth working fluid pipeline (31).

5. The indirect double-effect jet heat pump system according to claim 4, characterized in that: The second throttle valve (33) is arranged on the sixteenth working fluid pipeline (31) between the subcooler (36) and the second evaporator (12).

6. The indirect double-effect jet heat pump system according to claim 1, characterized in that: The two ports on the primary side of the first generator (1) are correspondingly provided with a temperature sensor T1 and a temperature sensor T2, and the two ports on the secondary side of the condenser (13) are correspondingly provided with a temperature sensor T3 and a temperature sensor T4.

7. The indirect double-effect jet heat pump system according to claim 1, characterized in that: The main flow inlet of the first ejector (2) is provided with a temperature sensor T5 and a pressure sensor P1, and the outlet of the first ejector (2) is provided with a pressure sensor P2.

8. The indirect double-effect jet heat pump system according to claim 1, characterized in that: The main flow inlet of the second injector (8) is provided with a temperature sensor T6 and a pressure sensor P3, and the outlet of the second injector (8) is provided with a pressure sensor P4.

9. The indirect double-effect jet heat pump system according to claim 1, characterized in that: A temperature sensor T7 is provided at the primary side inlet of the first evaporator (6), and a temperature sensor T8 is provided at the primary side outlet of the second evaporator (12).

10. A control method for the indirect double-effect jet heat pump system according to claim 1, characterized in that: The following steps are involved: S1. Start the system, the heat extraction circuit, the heat supply circuit, the primary heat pump circuit and the secondary heat pump circuit are circulated, and the flue gas continuously flows through the primary side of the first evaporator (6) and the second evaporator (12), wherein the fluid in the heat extraction circuit is waste water, the fluid in the heat supply circuit is water or antifreeze, referred to as the heat supply fluid, the fluid in the primary heat pump circuit and the secondary heat pump circuit is refrigerant, and the primary heat pump circuit includes a primary mainstream circuit formed by sequentially connecting the secondary side of the first generator (1), the first ejector (2), the primary side of the first economizer (3), the first gas-liquid separator (4), the first liquid storage tank (5), and the secondary side of the first economizer (3), and a first ejector (2), A primary secondary flow loop is formed by sequentially connecting the primary side of the first economizer (3), the first gas-liquid separator (4), the first liquid storage tank (5), and the secondary side of the first evaporator (6); a secondary heat pump loop includes a secondary mainstream loop formed by sequentially connecting the secondary side of the second generator (7), the second ejector (8), the primary side of the second economizer (9), the second gas-liquid separator (10), the second liquid storage tank (11), and the secondary side of the second economizer (9); and a secondary secondary flow loop is formed by sequentially connecting the second ejector (8), the primary side of the second economizer (9), the second gas-liquid separator (10), the second liquid storage tank (11), and the secondary side of the second evaporator (12); S2, wastewater transfers heat to refrigerant through the first generator (1), flue gas transfers heat to refrigerant through the first evaporator (6) and the second evaporator (12), the refrigerant transfers heat to the heating fluid through the condenser (13), and the heating fluid transfers heat to the heating terminal through the heating circuit; S3, the saturated refrigerant liquid flowing through the first generator (1) absorbs heat and becomes high-pressure refrigerant vapor, the high-pressure refrigerant vapor enters the first ejector (2) and mixes with the low-pressure refrigerant vapor from the first evaporator (6), the refrigerant vapor at the outlet of the first ejector (2) flows through the first economizer (3) and releases heat and becomes a refrigerant gas-liquid two-phase fluid, the refrigerant gas-liquid two-phase fluid is processed by the first gas-liquid separator (4) and is divided into a refrigerant saturated liquid and a refrigerant saturated vapor, and the refrigerant saturated liquid directly enters the first liquid storage tank (5) , the saturated vapor of the refrigerant flows through the second generator (7) to release heat and then becomes a saturated liquid refrigerant and enters the first liquid storage tank (5); a portion of the saturated liquid refrigerant in the first liquid storage tank (5) is pumped and pressurized by the first working fluid pump (21) and then enters the first economizer (3) to absorb heat and heat up; the saturated liquid refrigerant after the pressure and temperature increase enters the first generator (1) to absorb heat and vaporize; another portion of the saturated liquid refrigerant in the first liquid storage tank (5) is throttled and depressurized by the first throttle valve (22) and then enters the first evaporator (6) to absorb heat and vaporize; S4. The saturated refrigerant liquid flowing through the second generator (7) absorbs heat and becomes high-pressure refrigerant vapor. The high-pressure refrigerant vapor enters the second ejector (8) and mixes with the low-pressure refrigerant vapor from the second evaporator (12). The refrigerant vapor at the outlet of the second ejector (8) flows through the second economizer (9) and releases heat and becomes a refrigerant gas-liquid two-phase fluid. The refrigerant gas-liquid two-phase fluid is processed by the second gas-liquid separator (10) and is divided into a refrigerant saturated liquid and a refrigerant saturated vapor. The refrigerant saturated liquid directly enters the second liquid storage tank (11). The saturated vapor of the refrigerant flows through the condenser (13) to release heat and then becomes a saturated liquid refrigerant and enters the second liquid storage tank (11). A portion of the saturated liquid refrigerant in the second liquid storage tank (11) is pumped and pressurized by the second working fluid pump (32) and then enters the second economizer (8) to absorb heat and heat up. The saturated liquid refrigerant after the pressure and temperature are increased enters the second generator (7) to absorb heat and vaporize. Another portion of the saturated liquid refrigerant in the second liquid storage tank (11) is throttled and depressurized by the second throttle valve (33) and then enters the second evaporator (12) to absorb heat and vaporize.

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