A heat and power cogeneration system coupled with a water vapor compression ultra-high temperature heat pump

Abstract

The application aims to provide a heat and power supply system coupled with a water vapor compression type ultra-high temperature heat pump, so as to fully utilize the current industrial flue gas waste heat resource and improve the energy utilization rate. The heat and power supply system of the application is designed to utilize a flue gas waste heat power generation system and a steam generation system, and realizes the energy cascade utilization of the flue gas waste heat based on an organic Rankine cycle and a water vapor compression type ultra-high temperature heat pump.

Description

Technical Field

[0001] This invention relates to a thermoelectric system coupled with a water vapor compression type ultra-high temperature heat pump, which is mainly used to recover and utilize the energy in the flue gas emitted by industrial boilers, belonging to the field of industrial waste heat utilization. Background Technology

[0002] Currently, 45% of the heat in the heat source structure is provided by coal-fired and gas-fired boilers, directly causing 1 billion tons of CO2 emissions, which will seriously pollute the environment. The five major energy-intensive industries account for about 50% of the total energy consumption of the society. During the combustion process, a large amount of waste heat is generated, of which flue gas waste heat accounts for 50% of the waste heat resources. The waste heat is large and concentrated, relatively high in grade, and has great potential for utilization, but it has not been fully recovered and reused.

[0003] For research on industrial waste heat utilization, the thermoelectric conversion efficiency of ORC systems is mostly concentrated between 5% and 25%, and the generated electricity has problems such as fluctuation and instability, making it difficult to directly connect to the power grid to meet other electricity demands. Therefore, in practical applications, organic Rankine cycles are often combined with production heating and cooling systems.

[0004] Chinese invention patent application number 201510198714.2 discloses a coupling system of an organic Rankine cycle and a heat pump cycle. This system consists of two parts: an organic Rankine cycle power generation system and a heat pump cycle system. The heat pump cycle system is coupled to the organic Rankine cycle power generation system via an evaporator. The expander of the ORC cycle system is connected to the compressor of the heat pump system via a transmission device. During operation, the expander performs work, driving the compressor through the transmission device. During operation, the circulating working fluid and the recovered low-temperature waste heat exchange heat in the evaporator, resulting in two gaseous working fluids. One gaseous working fluid enters the expander to participate in the organic Rankine cycle, and the other gaseous working fluid enters the compressor to participate in the heat pump cycle. The work done by the expander preferentially drives the compressor connected to the expander, realizing the output of high-temperature heat energy from the heat pump cycle. The remaining work drives the generator to generate electricity, thus achieving co-generation of heat and power. The technical solution disclosed in the aforementioned patent mainly provides production heat and electricity by dividing waste heat into two parts: one part for power generation and the other for heat generation. This weakens heat and electricity generation, resulting in low energy utilization efficiency of the entire system. Furthermore, the provided heat energy needs to be obtained through a heat exchange device and cannot directly generate steam.

[0005] The invention patent with application number 201310164791.7 discloses a combined heat and power system based on organic Rankine cycle and flue gas condensation heat recovery. Compared with the process of separating heat energy for power generation and heat generation respectively, it improves the energy utilization efficiency. However, its energy utilization efficiency for the second stage of the process is still insufficient, and the heat energy utilization method is too simple. Summary of the Invention

[0006] To address the shortcomings of the existing system, this invention aims to provide a combined heat and power system coupled with a water vapor compression ultra-high temperature heat pump, thereby fully utilizing existing industrial flue gas waste heat resources and improving energy efficiency. The combined heat and power system of this invention is designed to utilize flue gas waste heat to generate electricity and produce steam, achieving cascaded energy utilization of flue gas waste heat based on an organic Rankine cycle and a water vapor compression ultra-high temperature heat pump.

[0007] The technical solution adopted in this invention is as follows: a thermoelectric system coupled with a water vapor compression ultra-high temperature heat pump, comprising an organic Rankine cycle system and a water vapor compression ultra-high temperature heat pump system;

[0008] The organic Rankine cycle system includes a first evaporator, a medium-low temperature expander, a generator, a first condenser, and a working fluid pump connected in sequence by pipes. The working fluid pump is connected back to the first evaporator to form a cycle.

[0009] The water vapor compression ultra-high temperature heat pump system includes a second evaporator, a circulating water pump, a flash tank, a first compressor, a second condenser, a liquid collection tank, and an expansion valve. The flash tank includes ports a, b, c, and d, wherein ports a and b of the flash tank are connected to form a steam path, and ports c and d are connected to form a circulating water path. The liquid collection tank also includes ports a, b, and c.

[0010] The second evaporator is connected to port a of the flash tank via a pipeline. Port b of the flash tank is connected to the first compressor and the second condenser via a pipeline. The second condenser is connected to port b of the liquid collection tank. Port c of the liquid collection tank is connected to port c of the flash tank via a pipeline. Port d of the flash tank is connected back to the second evaporator via a pipeline connected in series with the circulating water pump.

[0011] It also includes flue gas pipelines, cooling water pipelines, and heat energy export pipelines. The flue gas pipelines flow sequentially through the first evaporator and the second evaporator to provide heat energy. The cooling water pipelines flow through the first condenser and are connected to port a of the liquid collection tank. The heat energy export pipelines flow through the second condenser to absorb heat energy.

[0012] Furthermore, a three-way diverter valve is connected in series between the first compressor and the second condenser. Port a of the three-way diverter valve is connected to the second condenser, and port b of the three-way diverter valve is connected to the second compressor. A throttling valve is installed on the cooling water pipeline; an expansion valve is installed on the pipeline connecting port c of the liquid collection tank to the flash tank.

[0013] A first shut-off valve is installed upstream of the first evaporator in the flue gas pipeline; a second shut-off valve is installed in the pipeline of the organic Rankine cycle system; and a third shut-off valve is installed on the pipeline connecting the flash tank of the water vapor compression ultra-high temperature heat pump system to the first compressor.

[0014] A second flow meter is installed between the first condenser and the liquid collection tank; a first flow meter is installed between the three-way diverter valve and the second condenser; and a third flow meter is installed between the three-way diverter valve and the second compressor.

[0015] The space connecting ports a and b within the flash evaporator is used to flash wet steam into saturated steam, and the space connecting ports c and d within the flash evaporator is used to flash condensate into saturated liquid. Ports a and b of the collection tank are input ports, and port c is a common output port.

[0016] Preferably, the heat energy transmission pipeline is a heating pipeline.

[0017] Furthermore, the present invention also claims protection for an operating method of a thermoelectric power supply system based on a coupled water vapor compression ultra-high temperature heat pump, which includes a summer operating mode and a winter operating mode.

[0018] The summer operation mode is as follows: the condensate from the cooling water pipeline after flowing through the organic Rankine circulation system enters the liquid collection tank of the water vapor compression ultra-high temperature heat pump system after passing through the throttling valve, and then flows sequentially through the expansion valve, flash tank, and circulating water pump into the second evaporator. The outlet end of the second evaporator is connected to port a in the flash tank inlet, port b of the flash tank is connected to the inlet end of the first compressor, and the outlet end of the first compressor is connected to the inlet end of the three-way diverter valve. The port a of the three-way diverter valve is closed, and the port b of the three-way diverter valve is opened. After passing through the second compressor, steam is produced for drying, drying and other processes that require steam, forming an open system.

[0019] The winter operation mode is as follows: condensate from the cooling water pipeline flowing through the organic Rankine circulation system passes through a throttling valve and enters the collection tank of the water vapor compression ultra-high temperature heat pump system. It then flows sequentially through the expansion valve, flash tank, and circulating water pump into the second evaporator. The outlet of the second evaporator is connected to port a of the flash tank inlet. Port b of the flash tank is connected to the inlet of the first compressor. The outlet of the first compressor is connected to the inlet of the three-way diverter valve. Port a of the three-way diverter valve is open and connected to the inlet of the second condenser, providing heat energy for user-side heating. The outlet of the second condenser is connected to port b of the collection tank. Condensate entering from port a and port b of the collection tank mixes and flows to the flash tank, forming a closed system. Port b of the three-way diverter valve selectively opens or closes the medium-low temperature expander for power generation, and the compressor for generating heat energy and steam.

[0020] The organic Rankine cycle system also includes a generator that is connected to the expander drive.

[0021] The expander and generator can be connected by pulleys, gears, or directly through shaft transmission.

[0022] The advantages of this invention are:

[0023] 1. The flue gas energy cascade utilization system of the present invention is equipped with two circulation systems: a flue gas waste heat power generation system and a flue gas waste heat heat pump system, which can make full use of the energy of flue gas waste heat and has a high waste heat recovery and utilization rate.

[0024] 2. For high-temperature heat pump systems, water with zero ODP and GWP is used. It is non-toxic, harmless, stable, durable, and has a high latent heat of vaporization. Compared with CO2 and NH3, water has a very low evaporation pressure, which reduces potential safety hazards.

[0025] 3. The power generation system uses organic working fluid as the circulating working fluid. Compared with water, organic working fluid has a higher condensation pressure. The entire system operates at pressure close to or slightly higher than atmospheric pressure, which greatly reduces the leakage of organic working fluid. At the same time, the freezing point of organic working fluid is very low, which allows it to release energy at lower temperatures. Even in cold weather, the condenser does not need to be equipped with antifreeze facilities.

[0026] 4. In the system, shut-off valves are installed before the expander and compressor. The shut-off valves are used to stop the power generation system and heat pump system in case of emergency or during troubleshooting and maintenance.

[0027] 5. Single-screw expanders can achieve high isentropic efficiency, good dynamic balance, are simple and reliable, have no easily damaged parts, no gaps, and have a certain descaling and self-cleaning ability. Attached Figure Description

[0028] Figure 1 This is a schematic diagram of the thermoelectric power supply system of the present invention coupled with a water vapor compression ultra-high temperature heat pump;

[0029] In the diagram: 1. First shut-off valve, 2. First evaporator, 3. Second shut-off valve, 4. Medium-low temperature expander, 5. Generator, 6. First condenser, 7. Working fluid pump, 8. Second evaporator, 9. Flash tank, 10. Third shut-off valve, 11. First compressor, 12. Three-way diverter valve, 13. First flow meter, 14. Second condenser, 15. Liquid collection tank, 16. Throttling valve, 17. Second flow meter, 18. Expansion valve, 19. Circulating water pump, 20. Third flow meter, 21. Second compressor. Detailed Implementation

[0030] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0031] The following specific embodiments illustrate the implementation method of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification.

[0032] Referring to the accompanying drawings, the structures, proportions, sizes, etc., depicted in the drawings are merely for illustrative purposes to aid those skilled in the art in understanding and reading the content disclosed herein. They are not intended to limit the conditions under which the invention can be implemented and therefore have no substantial technical significance. Any modifications to the structure, changes in proportions, or adjustments to the size, without affecting the effects and objectives achieved by the invention, should still fall within the scope of the technical content disclosed herein. Furthermore, the positional limitations used in this specification are merely for clarity of description and are not intended to limit the scope of the invention. Changes or adjustments to their relative relationships, without substantially altering the technical content, should also be considered within the scope of the invention's implementation.

[0033] Figure 1 This is a schematic diagram of the thermoelectric power supply system of the present invention, which is coupled with a water vapor compression type ultra-high temperature heat pump. The following is a description of the process in conjunction with the attached diagram. Figure 1 The technical solution of the present invention is described as follows:

[0034] A thermoelectric system coupled with a water vapor compression ultra-high temperature heat pump includes an organic Rankine cycle system and a water vapor compression ultra-high temperature heat pump system.

[0035] The organic Rankine cycle system includes a first evaporator 2, a second shut-off valve 3, a low-temperature expander 4, a generator 5, a first condenser 6, and a working fluid pump 7, which are connected sequentially via pipelines. The first evaporator 2 evaporates the organic working fluid into saturated steam through heat exchange with the flue gas, which then enters the low-temperature expander 4. The low-temperature expander 4 is used for power generation and is connected to the generator 5. The outlet of the low-temperature expander 4 is connected to the first inlet of the first condenser 6 via a pipeline. The first condenser 6 is used to cool the exhaust steam after it has done work in the expander. The first outlet of the first condenser 6 is connected to the inlet of the working fluid pump 7 via a pipeline. The working fluid pump 7 is used to adjust the pressure entering the first inlet of the evaporator 2, thus forming a closed loop. The second outlet of the first condenser 6 is connected to a throttle valve 16 via a pipeline. The throttle valve 16 is connected to a second flow meter 17 via a pipeline. The outlet of the second flow meter 17 is connected to the inlet a of the collection tank 15. The first condenser 6 is connected to its second outlet end and has a corresponding second inlet end. Cooling water flows through the second inlet end and the second outlet end to the first condenser 6 to cool the working fluid in the organic Rankine cycle system.

[0036] The water vapor compression type ultra-high temperature heat pump system includes a second evaporator 8, a flash tank 9, a third shut-off valve 10, a first compressor 11, a three-way diverter valve 12, a first flow meter 13, a second condenser 14, a liquid collection tank 15, an expansion valve 18, and a circulating water pump 19, which are connected sequentially through pipelines to form a closed loop; it also includes a third flow meter 20 and a second compressor 21. The second evaporator 8 heats the circulating water into wet steam by exchanging heat with the flue gas, which then enters the flash tank 9. After flashing, the water becomes saturated steam and is drawn into the first compressor 11 for compression, temperature increase, and pressure increase. The discharged high-temperature water vapor passes through the three-way diverter valve 12, which divides the high-temperature steam into two operating states: 1. Both ports a and b are opened simultaneously, and part of the steam passes through the first flow meter 13 and enters the first inlet end of the second condenser 14, providing heat energy to the second condenser 14. The second inlet end and the second outlet end of the second condenser 14 supply heating water to users. The water flows through the second condenser 14 to absorb heat energy, thereby supplying heating to the user side. Steam entering from the first inlet of the second condenser 14 condenses and the condensate enters the b port of the collection tank 15. After mixing with the condensate at the second outlet of the first condenser 6 of the organic Rankine cycle system, the condensate enters the flash tank 9 through the expansion valve 18. The saturated liquid after flashing enters the circulating water pump 19, which is connected to the second evaporator 8 to complete one closed cycle. Part of the steam is supplied from the b port to the second compressor 21. 2. The a port is closed and the b port is opened. The steam passes through the third flow meter 20 and then through the second compressor 21 to generate steam that is fed into the process route that requires steam, forming an open cycle.

[0037] The following is in conjunction with the appendix Figure 1The working process of the thermoelectric power supply system of the superheated water vapor compression ultra-high temperature heat pump of the present invention is further explained as follows: Flue gas enters the first evaporator 2 and the second evaporator 8 sequentially through the first shut-off valve 1. The waste heat of the flue gas provides heat energy to the first evaporator 2 and the second evaporator 8 in a cascade manner. The first shut-off valve 1 is used to stop the system in an emergency. After the flue gas enters the first evaporator 2, it exchanges heat with the organic working fluid of the organic Rankine cycle system. The organic working fluid is heated into dry steam. The second shut-off valve 3 is opened. The second shut-off valve 3 is used to stop or repair the organic Rankine cycle system in an emergency. The dry steam enters the medium-low temperature expander 4 to expand and do work. Exhaust steam is generated at the power generation outlet of thermal expander 4. This exhaust steam enters the first condenser 6 via a pipeline, where it exchanges heat with cooling water to release its latent heat of vaporization, becoming a liquid working fluid. This fluid flows into the working fluid pump 7, where it is pressurized and enters the first evaporator 2, where it undergoes the first stage of waste heat utilization for power generation based on an organic Rankine system. The flue gas then enters the second evaporator 8 and exchanges heat with circulating water for the second stage of waste heat utilization. The heated circulating water becomes wet steam, which enters port a of flash tank 9. After flashing, it becomes saturated steam and is drawn into the first compressor 11 from port b of flash tank 9 for compression, heating, and pressurization. The discharged high-temperature steam is then distributed through a three-way valve. High-temperature steam is diverted through a three-way diverter valve 12 into two operating states: 1. Both ports a and b are opened simultaneously. Part of the steam passes through the first flow meter 13 and enters the second condenser 14 to provide heat energy for user-side heating. After condensation, the condensate enters port b of the collection tank 15, while the condensate generated by the organic Rankine cycle enters port a of the collection tank 15. The two streams of condensate mix and flow out from the outlet of the collection tank 15, passing through the expansion valve 18 into the flash tank 9. The saturated liquid after flash evaporation enters the circulating water pump 19, which is connected to the second evaporator 8, completing one closed cycle. Part of the steam passes through the third flow meter 14 into the second condenser 14, providing heat energy for user-side heating. 1. Steam enters the second compressor 21, generating high-temperature steam that flows into the process route requiring steam, forming an open cycle. At this point, the flow rate needs to be controlled by the first flow meter 13 and the third flow meter 20 to ensure that the amount of cooling water entering the first condenser 6 matches the amount of steam exiting from the third flow meter 20, guaranteeing a relatively stable circulation flow rate for the water vapor compression ultra-high temperature heat pump system. 2. Closing port a of the three-way diverter valve 12 and opening port b, steam flows through the third flow meter 20 into the second compressor 21, generating high-temperature steam that flows into the process route requiring steam, forming an open cycle. Of course, it is obvious to those skilled in the art that the three-way diverter valve can also temporarily open only port a and close port b, allowing all steam to enter the heating cycle via the first flow meter 13. In this cycle, where the working fluid phase change remains stable, the increased circulation flow rate can more fully utilize the waste heat from the second stage flue gas, supplying more heating energy to the user side.

[0038] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the claimed invention.

Claims

1. A heat and power supply system coupled with a water vapor compression ultra-high temperature heat pump, comprising an organic Rankine cycle system and a water vapor compression ultra-high temperature heat pump system; the organic Rankine cycle system comprises a first evaporator (2), a low-medium temperature expander (4), a generator (5), a first condenser (6) and a working medium pump (7) connected in sequence by pipelines, and the working medium pump (7) is communicated back to the first evaporator (2) to form a cycle; the water vapor compression ultra-high temperature heat pump system comprises a second evaporator (8), a circulating water pump (19), a flash tank (9), a first compressor (11), a second condenser (14), a liquid collecting tank (15) and an expansion valve (18), the flash tank (9) comprises a port a, a port b, a port c and a port d, wherein the port a and the port b of the flash tank (9) are communicated as a steam route, and the port c and the port d are communicated as a circulating water route; the liquid collecting tank (15) also comprises a port a, a port b and a port c; the second evaporator (8) is communicated to the port a of the flash tank (9) through a pipeline, the port b of the flash tank (9) is communicated to the first compressor (11) and the second condenser (14) in sequence through a pipeline, the second condenser (14) is communicated to the port b of the liquid collecting tank (15), the port c of the liquid collecting tank (15) is communicated to the port c of the flash tank (9) through a pipeline, and the port d of the flash tank (9) is communicated back to the second evaporator (8) after connecting the circulating water pump (19) in sequence through a pipeline; it also comprises a flue gas pipeline, a cooling water pipeline and a heat energy export pipeline, the flue gas pipeline flows through the first evaporator (2) and the second evaporator (8) in sequence to provide heat energy; the cooling water pipeline is communicated to the port a of the liquid collecting tank (15) after flowing through the first condenser (6); the heat energy export pipeline absorbs heat energy by flowing through the second condenser (14).

2. The combined heat and power system of claim 1, further characterized by, a three-way diverter valve (12) is connected in series between the first compressor (11) and the second condenser (14), the port a of the three-way diverter valve (12) is communicated to the second condenser (14), and the port b of the three-way diverter valve (12) is communicated to a second compressor (21).

3. The combined heat and power system of claim 1 or 2, further characterized by, a throttling valve (16) is arranged on the cooling water pipeline; an expansion valve (18) is arranged on the pipeline communicated from the port c of the liquid collecting tank (15) to the flash tank (9).

4. The combined heat and power system of claim 1 or 2, further characterized by, a first stop valve (1) is arranged on the flue gas pipeline upstream of the first evaporator (2); a second stop valve (3) is arranged in the pipeline of the organic Rankine cycle system; a third stop valve (10) is arranged on the pipeline communicated from the flash tank (9) to the first compressor (11) in the water vapor compression ultra-high temperature heat pump system.

5. The combined heat and power system of claim 2, further characterized by, a second flow meter (17) is installed between the first condenser (6) and the liquid collecting tank (15); a first flow meter (13) is installed between the three-way diverter valve (12) and the second condenser (14), and a third flow meter (20) is installed between the three-way diverter valve (12) and the second compressor (21).

6. The combined heat and power system of claim 1, further characterized by The connecting space between a port and b port in the flash tank (9) is used for flashing the wet steam into saturated steam, and the connecting space between c port and d port in the flash tank (9) is used for flashing the condensed water into saturated liquid.

7. The combined heat and power system of claim 1, further characterized by The a port and b port of the collecting tank (15) are input ports, and the c port is a common output port.

8. The combined heat and power system of claim 1, further characterized by The heat energy export pipeline is a heating pipeline.

9. The method of operating a cogeneration system coupled to a water vapor compression ultra-high temperature heat pump according to any of claims 2-5, further characterized by, The heat and power supply system comprises a summer operation mode and a winter operation mode. In the summer operation mode, the condensed water after flowing through the organic Rankine cycle system of the cooling water pipeline enters the collecting tank of the water vapor compression type ultra-high temperature heat pump system through a throttle valve, and then sequentially flows through an expansion valve, a flash tank and a circulating water pump to enter a second evaporator, the outlet end of the second evaporator is connected with the a port in the inlet of the flash tank, the b port of the flash tank is connected with the inlet end of a first compressor, the outlet end of the first compressor is connected with the inlet end of a three-way shunt valve, the a port of the three-way shunt valve is closed, the b port of the three-way shunt valve is opened, and steam is generated after passing through a second compressor and is used for drying, drying and other processes requiring steam, thereby forming an open system. In the winter operation mode, the condensed water after flowing through the organic Rankine cycle system of the cooling water pipeline enters the collecting tank of the water vapor compression type ultra-high temperature heat pump system through a throttle valve, and then sequentially flows through an expansion valve, a flash tank and a circulating water pump to enter a second evaporator, the outlet end of the second evaporator is connected with the a port in the inlet of the flash tank, the b port of the flash tank is connected with the inlet end of a first compressor, the outlet end of the first compressor is connected with the inlet end of a three-way shunt valve, the a port of the three-way shunt valve is opened and connected with the inlet end of a second condenser to provide heat energy for the second condenser, thereby being used for user side heating, the outlet end of the second condenser is connected with the b port of the collecting tank, the condensed water entering the a port of the collecting tank and the condensed water entering the b port of the collecting tank are mixed and then flow to the flash tank, thereby forming a closed system, and the b port of the three-way shunt valve is selectively opened or closed.

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