Method for operating a cogeneration system with an integrated heat pump

Abstract

The present application relates to a kind of integrated heat pump's combined heat and power system's operating method, combined heat and power system includes steam turbine system and heat network water heating system;Steam turbine system includes medium-pressure cylinder, low-pressure cylinder, generator and condenser;Heat network water heating system includes electric heat pump's no.1 condenser, absorber, absorption heat pump's no.2 condenser and peak heater.Heat network backwater is cooled after passing through no.2 evaporator, then in turn through electric heat pump, absorption heat pump and peak heater for cascade heating.In addition, by adjusting the opening of no.4 shunt valve, the participation degree of absorption heat pump can be controlled: when the outlet heat network water of no.1 condenser all directly flows to mixing valve, absorption heat pump does not run;When part or all heat network water enters absorber, absorption heat pump is put into operation.The present application can expand the operation adjustment range of unit, improve the energy utilization efficiency and heating flexibility of combined heat and power system under variable working condition.

Description

Technical Field

[0001] This invention belongs to the field of coal-fired power generation technology, specifically relating to an operation method of a combined heat and power system with an integrated heat pump. Background Technology

[0002] With the growth of energy demand and the shift towards low-carbon development, my country's energy production structure is undergoing a significant transformation. The proportion of renewable energy sources such as wind and solar power in power generation is continuously increasing, while the proportion of traditional coal-fired power units is gradually decreasing. This has a major impact on the security of the power system. On the one hand, the randomness and volatility of renewable energy sources such as wind and solar power pose new challenges to the grid's regulation capabilities. On the other hand, to enable large-scale grid integration of renewable energy, coal-fired power units, currently the main source of energy supply, need better peak-shaving capabilities.

[0003] Due to its high energy efficiency, combined heat and power (CHP) has been widely adopted as a low-carbon technology in China. CHP also plays a crucial role in energy security and the resilience of the power system. However, due to the characteristics of heat and electricity coupling, the load regulation range of CHP systems during the heating season is limited, hindering the development of regional renewable energy. Furthermore, to ensure operational safety, steam turbines inevitably require some cooling steam. However, due to its low temperature, cooling steam is often difficult to utilize.

[0004] Existing integrated heat pump solutions are one way to improve the peak-shaving performance of combined heat and power (CHP) units. Their main principle is to utilize heat pumps to recover waste heat from air, exhaust steam, or flue gas, thereby reducing the heat output from extracted steam and thus improving the load regulation capacity of the CHP unit to some extent. However, solutions that simply integrate electric or absorption heat pumps offer limited improvement in the unit's regulation capacity. Further improving the load flexibility of coal-fired CHP units during the heating season and reducing exhaust steam losses remain important directions for technological development. Summary of the Invention

[0005] To address the shortcomings of existing methods, this invention provides an operation method for a combined heat and power (CHP) system with an integrated heat pump. Integrating a heat pump into the CHP system increases the efficiency of the CHP unit and enhances its power generation load regulation and waste steam recovery capabilities.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] An operation method for an integrated heat pump cogeneration system, characterized in that it includes a steam turbine system and a heating network water heating system;

[0008] The turbine system includes an intermediate-pressure cylinder (1), steam from the high-pressure cylinder is connected to the inlet of the intermediate-pressure cylinder (1), the outlet of the intermediate-pressure cylinder (1) is connected to the inlet of the first diversion valve (20), the outlet of the first diversion valve (20) is connected to the inlets of the first pressure control valve (2) and the second pressure control valve (3) respectively, the outlet of the first pressure control valve (2) is connected to the inlet of the low-pressure cylinder (4), the steam outlet of the low-pressure cylinder (4) is connected to the steam inlet of the condenser (5), the condensate inlet of the condenser (5) is connected to the circulating cooling water outlet of the condenser tower (7), and the condensate outlet of the condenser (5) is connected to the inlet of the second diversion valve (8); the intermediate-pressure cylinder (1), the low-pressure cylinder (4) and the generator (6) are coaxially connected;

[0009] The heating network water heating system includes a first condenser (9) of an electric heat pump, an absorber (10) of an absorption heat pump, a second condenser (11), and a peak heater (12); the outlet of the second diversion valve (8) is connected to the inlet of the circulating cooling water of the condensing tower (7) and the heat source inlet of the first evaporator (14), respectively; the heat source outlet of the first evaporator (14) is connected to the circulating cooling water inlet of the condensing tower (7); the refrigerant outlet of the first evaporator (14) is connected to the inlet of the compressor (15), and the outlet of the compressor (15) is connected to the first condenser (9). The inlet of the first condenser (9) is connected to the inlet of the first throttle valve (16), and the outlet of the first throttle valve (16) is connected to the refrigerant inlet of the first evaporator (14); the refrigerant outlet of the second evaporator (13) is connected to the inlet of the absorber (10), the dilute solution outlet of the absorber (10) is connected to the solution pump (17), the heat exchanger (21) and the generator (18) in sequence, the concentrated solution outlet of the generator (18) is connected to the heat exchanger (21) and the second throttle valve (19) in sequence, and the outlet of the second throttle valve (19) is connected to the ...throttle valve (16). The concentrated solution inlet of the absorber (10) is connected, and the refrigerant outlet of the generator (18) is connected in sequence to the second condenser (11), the third throttle valve (23), and the second evaporator (13); the outlet of the second pressure control valve (3) is connected to the inlet of the third diversion valve (22), and the outlet of the third diversion valve (22) is connected to the generator (18) and the peak heater (12) respectively; the heat network return water outlet is first connected to the heat source inlet of the second evaporator (13), and the heat source outlet of the second evaporator (13) is connected to the heat network water inlet of the first condenser (9). The hot water outlet of the No. 1 condenser (9) is connected to the inlet of the No. 4 diversion valve (24). The outlet of the No. 4 diversion valve (24) is connected to the inlet of the mixing valve (25) and the hot water inlet of the absorber (10). The hot water outlet of the absorber (10) is connected to the hot water inlet of the No. 2 condenser (11). The hot water outlet of the No. 2 condenser (11) is connected to the inlet of the mixing valve (25). The outlet of the mixing valve (25) is connected to the hot water inlet of the peak heater (12). The hot water outlet of the peak heater (12) is connected to the hot water network.

[0010] The operation method of the integrated heat pump cogeneration system is characterized in that the return water of the heat network enters the low temperature heat source inlet of the No. 2 evaporator (13) to heat the circulating working fluid, and then enters the heat network water inlet of the No. 1 condenser (9) from the low temperature heat source outlet of the No. 2 evaporator (13) to complete the first heating, then enters the heat network water inlet of the absorber (10) from the heat network water outlet of the No. 1 condenser (9) to complete the second heating, then enters the heat network water inlet of the No. 2 condenser (11) from the heat network water outlet of the absorber (10) to complete the third heating, and finally enters the peak heater (12) from the heat network water outlet of the No. 2 condenser (11) to complete the fourth heating, and after reaching the required temperature, it is used as the heat network water supply.

[0011] Given a fixed temperature rise range for each heating cycle, the remaining parameters can be determined by determining any one of the following: the return water volume of the heat network of the No. 2 evaporator (13), the mass flow rate of the working fluid in the electric heat pump, and the flow ratio of the No. 2 diversion valve (8) and the No. 3 diversion valve (22).

[0012] The operation method of the integrated heat pump cogeneration system is characterized in that the degree of participation of the absorption heat pump is controlled by adjusting the opening of the No. 4 diversion valve (24), thereby expanding the operating range of the unit; assuming the mass flow rate of the circulating working fluid is the same, when the heat network water at the outlet of the No. 1 condenser (9) flows entirely to the mixing valve (25) through the No. 4 diversion valve (24), the absorption heat pump does not operate, the maximum heating load of the system is the lowest, and the power generation under the maximum heating condition is the highest; when the heat network water at the outlet of the No. 1 condenser (9) flows entirely to the absorber (10) through the No. 4 diversion valve (24), the absorption heat pump operates, the maximum heating load of the system is the highest, and the power generation under the maximum heating condition is the lowest; when the heat network water at the outlet of the No. 1 condenser (9) partially flows to the absorber (10) through the No. 4 diversion valve (24), the maximum heating load and power generation of the system are between the two.

[0013] The method for operating an integrated heat pump cogeneration system is characterized in that the working fluid of the electric heat pump includes R134a, and the solution in the absorption heat pump includes a lithium bromide solution.

[0014] The operation method of the integrated heat pump cogeneration system is characterized in that the heat network water at the heat source outlet of the No. 2 evaporator (13) can be heated by an absorption heat pump, an air source heat pump, or a ground source heat pump.

[0015] The operation method of the integrated heat pump cogeneration system is characterized in that the condensate from the peak heater (12) can enter the condenser (5) or the deaerator.

[0016] The positive and beneficial effects of this invention are:

[0017] This invention discloses an operation method for a combined heat and power (CHP) system integrating a heat pump. By integrating a heat pump system into a traditional CHP system, the waste steam recovery capacity is improved, while achieving better operational flexibility than traditional integrated electric heat pump or absorption heat pump systems. In this invention, the return water from the heating network first enters the second evaporator of the absorption heat pump to heat the circulating working fluid, further reducing its temperature. At this point, since the low-temperature heat source of the absorption heat pump is the return water from the heating network, its temperature is higher than that of the circulating cooling water, thus increasing the temperature rise range of the absorption heat pump. Subsequently, it enters the first condenser of the electric heat pump for initial heating. Compared to a CHP system integrating only an electric heat pump, the waste heat utilization of the first evaporator of the electric heat pump will be higher. Then, it sequentially enters the absorber, the second condenser, and the peak heater of the absorption heat pump for further heating, achieving cascaded energy utilization and reducing heat exchange losses. Because electric heat pumps have a higher COP (coefficient of performance) and recover more waste steam, the unit's heating capacity and overall system efficiency are improved. Due to the increased electricity required to drive the compressor, the new system consistently offers a wider power generation regulation range and a higher power load regulation rate compared to traditional systems. Furthermore, by installing a diversion valve at the heat network water outlet of the electric heat pump condenser and a mixing valve at the heat network water outlet of the absorption heat pump condenser, the cogeneration system can still operate normally using the electric heat pump and peak heaters even if the absorption heat pump fails. Attached Figure Description

[0018] Figure 1 A schematic diagram of the operation method of a combined heat and power system with an integrated heat pump;

[0019] In the diagram: 1-Intermediate pressure cylinder; 2-Pressure control valve 1; 3-Pressure control valve 2; 4-Low pressure cylinder; 5-Condenser; 6-Generator; 7-Condensing tower; 8-Diverter valve 2; 9-Condenser 1; 10-Absorber; 11-Condenser 2; 12-Peak heater; 13-Evaporator 2; 14-Evaporator 1; 15-Compressor; 16-Throttle valve 1; 17-Solution pump; 18-Generator; 19-Throttle valve 2; 20-Diverter valve 1; 21-Heat exchanger; 22-Diverter valve 3; 23-Throttle valve 3; 24-Diverter valve 4; 25-Mixing valve

[0020] Figure 2 A schematic diagram of the peak-shaving range of the integrated heat pump and cogeneration system.

[0021] In the diagram: ① represents the peak-shaving range of the original cogeneration system; ② represents the peak-shaving range of the integrated heat pump cogeneration system under its operating method. Detailed Implementation

[0022] The present invention will be further described below with reference to the accompanying drawings and some specific embodiments.

[0023] An operation method for an integrated heat pump cogeneration system, characterized in that it includes a steam turbine system and a heating network water heating system;

[0024] The turbine system includes an intermediate-pressure cylinder (1), steam from the high-pressure cylinder is connected to the inlet of the intermediate-pressure cylinder (1), the outlet of the intermediate-pressure cylinder (1) is connected to the inlet of the first diversion valve (20), the outlet of the first diversion valve (20) is connected to the inlets of the first pressure control valve (2) and the second pressure control valve (3) respectively, the outlet of the first pressure control valve (2) is connected to the inlet of the low-pressure cylinder (4), the steam outlet of the low-pressure cylinder (4) is connected to the steam inlet of the condenser (5), the condensate inlet of the condenser (5) is connected to the circulating cooling water outlet of the condenser tower (7), and the condensate outlet of the condenser (5) is connected to the inlet of the second diversion valve (8); the intermediate-pressure cylinder (1), the low-pressure cylinder (4) and the generator (6) are coaxially connected;

[0025] The heating network water heating system includes a first condenser (9) of an electric heat pump, an absorber (10) of an absorption heat pump, a second condenser (11), and a peak heater (12); the outlet of the second diversion valve (8) is connected to the inlet of the circulating cooling water of the condensing tower (7) and the heat source inlet of the first evaporator (14), respectively; the heat source outlet of the first evaporator (14) is connected to the circulating cooling water inlet of the condensing tower (7); the refrigerant outlet of the first evaporator (14) is connected to the inlet of the compressor (15), and the outlet of the compressor (15) is connected to the first condenser (9). The inlet of the first condenser (9) is connected to the inlet of the first throttle valve (16), and the outlet of the first throttle valve (16) is connected to the refrigerant inlet of the first evaporator (14); the refrigerant outlet of the second evaporator (13) is connected to the inlet of the absorber (10), the dilute solution outlet of the absorber (10) is connected to the solution pump (17), the heat exchanger (21) and the generator (18) in sequence, the concentrated solution outlet of the generator (18) is connected to the heat exchanger (21) and the second throttle valve (19) in sequence, and the outlet of the second throttle valve (19) is connected to the ...throttle valve (16). The concentrated solution inlet of the absorber (10) is connected, and the refrigerant outlet of the generator (18) is connected in sequence to the second condenser (11), the third throttle valve (23), and the second evaporator (13); the outlet of the second pressure control valve (3) is connected to the inlet of the third diversion valve (22), and the outlet of the third diversion valve (22) is connected to the generator (18) and the peak heater (12) respectively; the heat network return water outlet is first connected to the heat source inlet of the second evaporator (13), and the heat source outlet of the second evaporator (13) is connected to the heat network water inlet of the first condenser (9). The hot water outlet of the No. 1 condenser (9) is connected to the inlet of the No. 4 diversion valve (24). The outlet of the No. 4 diversion valve (24) is connected to the inlet of the mixing valve (25) and the hot water inlet of the absorber (10). The hot water outlet of the absorber (10) is connected to the hot water inlet of the No. 2 condenser (11). The hot water outlet of the No. 2 condenser (11) is connected to the inlet of the mixing valve (25). The outlet of the mixing valve (25) is connected to the hot water inlet of the peak heater (12). The hot water outlet of the peak heater (12) is connected to the hot water network.

[0026] The operation method of the integrated heat pump cogeneration system is characterized in that the return water of the heat network enters the low temperature heat source inlet of the No. 2 evaporator (13) to heat the circulating working fluid, and then enters the heat network water inlet of the No. 1 condenser (9) from the low temperature heat source outlet of the No. 2 evaporator (13) to complete the first heating, then enters the heat network water inlet of the absorber (10) from the heat network water outlet of the No. 1 condenser (9) to complete the second heating, then enters the heat network water inlet of the No. 2 condenser (11) from the heat network water outlet of the absorber (10) to complete the third heating, and finally enters the peak heater (12) from the heat network water outlet of the No. 2 condenser (11) to complete the fourth heating, and after reaching the required temperature, it is used as the heat network water supply.

[0027] Given a fixed temperature rise range for each heating cycle, the remaining parameters can be determined by determining any one of the following: the return water volume of the heat network of the No. 2 evaporator (13), the mass flow rate of the working fluid in the electric heat pump, and the flow ratio of the No. 2 diversion valve (8) and the No. 3 diversion valve (22).

[0028] Reference Appendix Figure 2 The operation method of the integrated heat pump cogeneration system is characterized in that the degree of participation of the absorption heat pump is controlled by adjusting the opening of the No. 4 diversion valve (24), thereby expanding the operating range of the unit; assuming the mass flow rate of the circulating working fluid is the same, when all the heat network water at the outlet of the No. 1 condenser (9) flows to the mixing valve (25) through the No. 4 diversion valve (24), the absorption heat pump does not operate, the maximum heating load of the system is the lowest, and the power generation is the highest under the maximum heating condition. Figure 2 The area enclosed by 1 in the diagram is the system operating range; when the hot water from the outlet of the No. 1 condenser (9) flows entirely to the absorber (10) through the No. 4 diversion valve (24), the absorption heat pump is in operation, the system's maximum heating load is the highest, and the power generation under the maximum heating condition is the lowest; when the hot water from the outlet of the No. 1 condenser (9) partially flows to the absorber (10) through the No. 4 diversion valve (24), the system's maximum heating load and power generation are between the two, and the attached diagram is provided. Figure 2 The 2 in the figure represents the increased operating range of the system.

[0029] The method for operating an integrated heat pump cogeneration system is characterized in that the working fluid of the electric heat pump includes R134a, and the solution in the absorption heat pump includes a lithium bromide solution.

[0030] The operation method of the integrated heat pump cogeneration system is characterized in that the heat network water at the heat source outlet of the No. 2 evaporator (13) can be heated by an absorption heat pump, an air source heat pump, or a ground source heat pump.

[0031] The operation method of the integrated heat pump cogeneration system is characterized in that the condensate from the peak heater (12) can enter the condenser (5) or the deaerator.

[0032] Finally, it should be noted that the above examples are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Any other modifications or equivalent substitutions made by those skilled in the art to the technical solutions of the present invention, as long as they do not depart from the spirit and scope of the technical solutions of the present invention, should be covered within the scope of the claims of the present invention.

Claims

1. A method for operating an integrated heat pump cogeneration system, characterized in that, Integrated heat pump cogeneration systems include steam turbine systems and heating network water heating systems; The turbine system includes an intermediate-pressure cylinder (1), steam from the high-pressure cylinder is connected to the inlet of the intermediate-pressure cylinder (1), the outlet of the intermediate-pressure cylinder (1) is connected to the inlet of the first diversion valve (20), the outlet of the first diversion valve (20) is connected to the inlets of the first pressure control valve (2) and the second pressure control valve (3) respectively, the outlet of the first pressure control valve (2) is connected to the inlet of the low-pressure cylinder (4), the steam outlet of the low-pressure cylinder (4) is connected to the steam inlet of the condenser (5), the condensate inlet of the condenser (5) is connected to the circulating cooling water outlet of the condenser tower (7), and the condensate outlet of the condenser (5) is connected to the inlet of the second diversion valve (8); the intermediate-pressure cylinder (1), the low-pressure cylinder (4) and the generator (6) are coaxially connected; The heating network water heating system includes a first condenser (9) of an electric heat pump, an absorber (10) of an absorption heat pump, a second condenser (11), and a peak heater (12); the outlet of the second diversion valve (8) is connected to the inlet of the circulating cooling water of the condensing tower (7) and the heat source inlet of the first evaporator (14), respectively; the heat source outlet of the first evaporator (14) is connected to the circulating cooling water inlet of the condensing tower (7); the refrigerant outlet of the first evaporator (14) is connected to the inlet of the compressor (15), and the outlet of the compressor (15) is connected to the first condenser (9). The inlet of the first condenser (9) is connected to the inlet of the first throttle valve (16), and the outlet of the first throttle valve (16) is connected to the refrigerant inlet of the first evaporator (14); the refrigerant outlet of the second evaporator (13) is connected to the inlet of the absorber (10), the dilute solution outlet of the absorber (10) is connected to the solution pump (17), the heat exchanger (21) and the generator (18) in sequence, the concentrated solution outlet of the generator (18) is connected to the heat exchanger (21) and the second throttle valve (19) in sequence, and the outlet of the second throttle valve (19) is connected to the ...throttle valve (16). The concentrated solution inlet of the absorber (10) is connected, and the refrigerant outlet of the generator (18) is connected in sequence to the second condenser (11), the third throttle valve (23), and the second evaporator (13); the outlet of the second pressure control valve (3) is connected to the inlet of the third diversion valve (22), and the outlet of the third diversion valve (22) is connected to the generator (18) and the peak heater (12) respectively; the heat network return water outlet is first connected to the heat source inlet of the second evaporator (13), and the heat source outlet of the second evaporator (13) is connected to the heat network water inlet of the first condenser (9). The hot water outlet of the No. 1 condenser (9) is connected to the inlet of the No. 4 diversion valve (24). The outlet of the No. 4 diversion valve (24) is connected to the inlet of the mixing valve (25) and the hot water inlet of the absorber (10) respectively. The hot water outlet of the absorber (10) is connected to the hot water inlet of the No. 2 condenser (11). The hot water outlet of the No. 2 condenser (11) is connected to the inlet of the mixing valve (25). The outlet of the mixing valve (25) is connected to the hot water inlet of the peak heater (12). The hot water outlet of the peak heater (12) is connected to the hot water network. The operation method of the integrated heat pump cogeneration system described above controls the participation of the absorption heat pump by adjusting the opening of the No. 4 diversion valve (24), thereby expanding the operating adjustment range of the unit. When the heat network water at the outlet of the No. 1 condenser (9) flows entirely to the mixing valve (25) through the No. 4 diversion valve (24), the absorption heat pump system is not running, the maximum heating load of the system is the lowest, and the power generation under the maximum heating condition is the highest. When the heat network water at the outlet of the No. 1 condenser (9) flows entirely to the absorber (10) through the No. 4 diversion valve (24), the absorption heat pump is running, the maximum heating load of the system is the highest, and the power generation under the maximum heating condition is the lowest. When the heat network water at the outlet of the No. 1 condenser (9) flows partially to the absorber (10) through the No. 4 diversion valve (24), the maximum heating load and power generation of the system are between the two.

2. The operation method of an integrated heat pump cogeneration system according to claim 1, characterized in that, The return water from the heating network enters the low-temperature heat source inlet of the No. 2 evaporator (13) to heat the circulating working fluid. Then, it enters the heating network water inlet of the No. 1 condenser (9) from the low-temperature heat source outlet of the No. 2 evaporator (13) to complete the first heating. Then, it enters the absorption tank (10) from the heating network water outlet of the No. 1 condenser (10) to complete the second heating. Then, it enters the No. 2 condenser (11) from the heating network water outlet to complete the third heating. Finally, it enters the peak heater (12) from the heating network water outlet of the No. 2 condenser (11) to complete the fourth heating. After reaching the required temperature, it is used as heating network water supply.

3. The operation method of an integrated heat pump cogeneration system according to claim 1, characterized in that, Given a fixed temperature rise range for each heating cycle, the remaining parameters can be determined by determining any one of the following: the return water volume of the heat network of the No. 2 evaporator (13), the mass flow rate of the working fluid in the electric heat pump, and the flow ratio of the No. 2 diversion valve (8) and the No. 3 diversion valve (22).

4. The operation method of an integrated heat pump cogeneration system according to claim 1, characterized in that, The working fluid of the electric heat pump includes R134a, and the solution in the absorption heat pump includes lithium bromide solution.

5. The operation method of an integrated heat pump cogeneration system according to claim 1, characterized in that, The heat source outlet of the No. 2 evaporator (13) is heated by an absorption heat pump, an air source heat pump, or a ground source heat pump.

6. The operation method of an integrated heat pump cogeneration system according to claim 1, characterized in that, The hydrophobic material from the peak heater (12) enters the condenser (5) or deaerator.

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