Cogeneration system integrating a regenerative heat exchanger and a heat pump and method of operation thereof

Abstract

The present application relates to a kind of integrated regenerative heat exchanger and heat pump's combined heat and power system and its 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 regenerative heat exchanger (electric heat pump), absorber, condenser (absorption heat pump), peak heater.Heat network backwater is connected with the heat network water inlet of regenerative heat exchanger, the heat network water outlet of regenerative heat exchanger is connected with the heat network water inlet of absorption heat pump's absorber, the heat network water outlet of absorber is connected with the heat network water inlet of absorption heat pump's condenser, condenser heat network water outlet is connected with the heat network water inlet of peak heater, the heat network water outlet of peak heater is connected with heat network as heat network supply water.The present application can recover the power and more waste heat generated by power plant by changing the traditional condenser in electric heat pump into regenerative heat exchanger, so that combined heat and power system can obtain more flexible power load adjustment capability, reduce energy loss, improve the heating capacity of unit and system total efficiency.

Description

Technical Field

[0001] This invention belongs to the field of coal-fired power generation technology, specifically relating to a combined heat and power system integrating a thermal storage heat exchanger and a heat pump, and its operation method. 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 amount of steam extracted 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 a combined heat and power (CHP) system integrating a regenerative heat exchanger and a heat pump, along with its operation method. Integrating a heat pump with a regenerative heat exchanger 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: A combined heat and power system integrating a regenerative heat exchanger and a heat pump, characterized in that it includes a steam turbine system and a heating network water heating system; 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 diverter valve (19), the outlet of the first diverter valve (19) is connected to the inlets of the first pressure control valve (2) and the second pressure control valve (3), 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 diverter 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 heat storage heat exchanger (9) of an electric heat pump, an absorber (10) of an absorption heat pump, a 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 evaporator (13), respectively; the heat source outlet of the evaporator (13) is connected to the inlet of the circulating cooling water of the condensing tower (7); the refrigerant outlet of the evaporator (13) is connected to the inlet of the compressor (14). The outlet of the compressor (14) is connected to the inlet of the regenerative heat exchanger (9), the outlet of the regenerative heat exchanger (9) is connected to the inlet of the first throttle valve (15), and the outlet of the first throttle valve (15) is connected to the refrigerant inlet of the evaporator (13); the refrigerant outlet of the regenerative heat exchanger (9) is connected to the inlet of the absorber (10), and the dilute solution outlet of the absorber (10) is sequentially connected to the solution pump (16), the heat exchanger (20), and the generator (17). The concentrated solution outlet of generator (17) is connected in sequence to heat exchanger (20) and second throttle valve (18). The outlet of second throttle valve (18) is connected to concentrated solution inlet of absorber (10). The refrigerant outlet of generator (17) is connected in sequence to condenser (11), third throttle valve (22), and regenerative heat exchanger (9). The outlet of second pressure control valve (3) is connected to inlet of third diverter valve (21). The outlet of third diverter valve (21) is connected to generator (17) and condenser (20) and condenser (9) respectively. 7) Connect to the peak heater (12); the return water outlet of the heat network is first connected to the heat network water inlet of the heat storage heat exchanger (9), the heat network water outlet of the heat storage heat exchanger (9) is connected to the heat network water inlet of the absorber (10), the heat network water outlet of the absorber (10) is connected to the heat network water inlet of the condenser (11), the heat network water outlet of the condenser (11) is connected to the heat network water inlet of the peak heater (12), and the heat network water outlet of the peak heater (12) is connected to the heat network.

[0007] The integrated heat and power system of the integrated regenerative heat exchanger and heat pump is 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.

[0008] The integrated heat and power system with integrated heat storage heat exchanger and heat pump is characterized in that the return water of the heat network can be heated for the first time not only by an electric heat pump, but also by other heat pumps, including absorption heat pumps, air source heat pumps and ground source heat pumps.

[0009] The integrated heat and power system of the integrated regenerative heat exchanger and heat pump is characterized in that the condensate from the peak heater (12) can enter the condenser (5) or the deaerator.

[0010] The operation method of the integrated heat and power cogeneration system with integrated heat storage heat exchanger and heat pump is characterized by including a heat storage mode and a heat release mode. The heat storage mode includes: the combined heat and power system of the integrated heat storage heat exchanger and heat pump, when the unit does not supply heat to the outside and generates excess electricity, the excess electricity is transmitted to the compressor (14) through the transmission line. The circulating working fluid is compressed by the compressor (14) and becomes a high temperature and high pressure gas, which then enters the heat storage heat exchanger (9) to store the heat. The heating mode includes: the combined heat and power system integrating the heat storage heat exchanger and the heat pump, when the unit supplies heat to the outside, the heat network return water enters from the heat network water inlet of the heat storage heat exchanger (9) and is heated by absorbing the heat stored in the heat storage heat exchanger (9); at the same time, the refrigerant of the absorption heat pump enters from the refrigerant inlet of the heat storage heat exchanger (9) and becomes saturated steam by absorbing the heat stored in the heat storage heat exchanger (9), and then flows to the absorber (10).

[0011] The return water from the heat exchanger enters the heat exchanger (9) and exchanges heat with the circulating medium in the electric heat pump to complete the first heating. Then, the water from the heat exchanger (9) enters the absorber (10) and the heat exchanger water inlet to complete the second heating. Then, the water from the absorber (10) enters the condenser (11) and the heat exchanger water inlet to complete the third heating. Finally, the water from the condenser (11) enters the peak heater (12) to complete the fourth heating. After reaching the required temperature, it is used as the heat supply water for the heat exchanger.

[0012] Given a fixed temperature rise range for each heating cycle, the remaining parameters can be determined by determining one of the following: the return water volume of the heat exchanger (9), the mass flow rate of the working fluid in the electric heat pump, and the flow ratio of the second diversion valve (8) and the third diversion valve (21).

[0013] The positive and beneficial effects of this invention are: This invention discloses a combined heat and power (CHP) system integrating a regenerative heat exchanger and a heat pump, and its operation method. By integrating a heat pump system with a regenerative heat exchanger 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 regenerative heat exchanger is responsible for heating the refrigerant and heat network return water in the absorption heat pump, thus increasing the waste heat utilization. Since the low-temperature heat source of the absorption heat pump is the heat network return water, its temperature is higher than that of the circulating cooling water, resulting in a larger temperature rise range for the absorption heat pump. The heat network return water sequentially enters the regenerative heat exchanger, absorber, condenser (absorption heat pump), and peak heater for heating, achieving cascaded energy utilization and reducing heat exchange losses. Because the electric heat pump has a higher COP (coefficient of performance), and the compressor utilizes excess electrical energy to do work, more waste steam is recovered, thereby improving the unit's heating capacity and overall system efficiency. Attached Figure Description

[0014] Figure 1 A schematic diagram of a combined heat and power system integrating a thermal storage heat exchanger and a heat pump; In the diagram: 1-Intermediate pressure cylinder; 2-First pressure control valve; 3-Second pressure control valve; 4-Low pressure cylinder; 5-Condenser; 6-Generator; 7-Condensing tower; 8-Second diversion valve; 9-Regenerative heat exchanger; 10-Absorber; 11-Condenser; 12-Peak heater; 13-Evaporator; 14-Compressor; 15-First throttle valve; 16-Solution pump; 17-Generator; 18-Second throttle valve; 19-First diversion valve; 20-Heat exchanger; 21-Third diversion valve; 22-Third throttle valve Detailed Implementation

[0015] The present invention will be further described below with reference to the accompanying drawings and some specific embodiments.

[0016] A combined heat and power system integrating a regenerative heat exchanger and a heat pump, characterized in that it includes a steam turbine system and a heating network water heating system; 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 diverter valve (19), the outlet of the first diverter valve (19) is connected to the inlets of the first pressure control valve (2) and the second pressure control valve (3), 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 diverter 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 heat storage heat exchanger (9) of an electric heat pump, an absorber (10) of an absorption heat pump, a 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 evaporator (13), respectively; the heat source outlet of the evaporator (13) is connected to the inlet of the circulating cooling water of the condensing tower (7); the refrigerant outlet of the evaporator (13) is connected to the inlet of the compressor (14). The outlet of the compressor (14) is connected to the inlet of the regenerative heat exchanger (9), the outlet of the regenerative heat exchanger (9) is connected to the inlet of the first throttle valve (15), and the outlet of the first throttle valve (15) is connected to the refrigerant inlet of the evaporator (13); the refrigerant outlet of the regenerative heat exchanger (9) is connected to the inlet of the absorber (10), and the dilute solution outlet of the absorber (10) is sequentially connected to the solution pump (16), the heat exchanger (20), and the generator (17). The concentrated solution outlet of generator (17) is connected in sequence to heat exchanger (20) and second throttle valve (18). The outlet of second throttle valve (18) is connected to concentrated solution inlet of absorber (10). The refrigerant outlet of generator (17) is connected in sequence to condenser (11), third throttle valve (22), and regenerative heat exchanger (9). The outlet of second pressure control valve (3) is connected to inlet of third diverter valve (21). The outlet of third diverter valve (21) is connected to generator (17) and condenser (20) and condenser (9) respectively. 7) Connect to the peak heater (12); the return water outlet of the heat network is first connected to the heat network water inlet of the heat storage heat exchanger (9), the heat network water outlet of the heat storage heat exchanger (9) is connected to the heat network water inlet of the absorber (10), the heat network water outlet of the absorber (10) is connected to the heat network water inlet of the condenser (11), the heat network water outlet of the condenser (11) is connected to the heat network water inlet of the peak heater (12), and the heat network water outlet of the peak heater (12) is connected to the heat network.

[0017] The integrated heat and power system of the integrated regenerative heat exchanger and heat pump is 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.

[0018] The integrated heat and power system with integrated heat storage heat exchanger and heat pump is characterized in that the return water of the heat network can be heated for the first time not only by an electric heat pump, but also by other heat pumps, including absorption heat pumps, air source heat pumps and ground source heat pumps.

[0019] The integrated heat and power system of the integrated regenerative heat exchanger and heat pump is characterized in that the condensate from the peak heater (12) can enter the condenser (5) or the deaerator.

[0020] The operation method of the integrated heat and power cogeneration system with integrated heat storage heat exchanger and heat pump is characterized by including a heat storage mode and a heat release mode. The heat storage mode includes: the combined heat and power system of the integrated heat storage heat exchanger and heat pump, when the unit does not supply heat to the outside and generates excess electricity, the excess electricity is transmitted to the compressor (14) through the transmission line. The circulating working fluid is compressed by the compressor (14) and becomes a high temperature and high pressure gas, which then enters the heat storage heat exchanger (9) to store the heat. The heating mode includes: the combined heat and power system integrating the heat storage heat exchanger and the heat pump, when the unit supplies heat to the outside, the heat network return water enters from the heat network water inlet of the heat storage heat exchanger (9) and is heated by absorbing the heat stored in the heat storage heat exchanger (9); at the same time, the refrigerant of the absorption heat pump enters from the refrigerant inlet of the heat storage heat exchanger (9) and becomes saturated steam by absorbing the heat stored in the heat storage heat exchanger (9), and then flows to the absorber (10).

[0021] The return water from the heat exchanger enters the heat exchanger (9) and exchanges heat with the circulating medium in the electric heat pump to complete the first heating. Then, the water from the heat exchanger (9) enters the absorber (10) and the heat exchanger water inlet to complete the second heating. Then, the water from the absorber (10) enters the condenser (11) and the heat exchanger water inlet to complete the third heating. Finally, the water from the condenser (11) enters the peak heater (12) to complete the fourth heating. After reaching the required temperature, it is used as the heat supply water for the heat exchanger.

[0022] Given a fixed temperature rise range for each heating cycle, the remaining parameters can be determined by determining one of the following: the return water volume of the heat exchanger (9), the mass flow rate of the working fluid in the electric heat pump, and the flow ratio of the second diversion valve (8) and the third diversion valve (21).

[0023] 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 combined heat and power system integrating a thermal storage heat exchanger and a heat pump, characterized in that, This includes steam turbine systems and thermal 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 diverter valve (19), the outlet of the first diverter valve (19) is connected to the inlets of the first pressure control valve (2) and the second pressure control valve (3), 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 diverter 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 heat storage heat exchanger (9) of an electric heat pump, an absorber (10) of an absorption heat pump, a 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 evaporator (13), respectively; the heat source outlet of the evaporator (13) is connected to the inlet of the circulating cooling water of the condensing tower (7); the refrigerant outlet of the evaporator (13) is connected to the inlet of the compressor (14). The outlet of the compressor (14) is connected to the inlet of the regenerative heat exchanger (9), the outlet of the regenerative heat exchanger (9) is connected to the inlet of the first throttle valve (15), and the outlet of the first throttle valve (15) is connected to the refrigerant inlet of the evaporator (13); the refrigerant outlet of the regenerative heat exchanger (9) is connected to the inlet of the absorber (10), and the dilute solution outlet of the absorber (10) is sequentially connected to the solution pump (16), the heat exchanger (20), and the generator (17). The concentrated solution outlet of generator (17) is connected in sequence to heat exchanger (20) and second throttle valve (18). The outlet of second throttle valve (18) is connected to concentrated solution inlet of absorber (10). The refrigerant outlet of generator (17) is connected in sequence to condenser (11), third throttle valve (22), and regenerative heat exchanger (9). The outlet of second pressure control valve (3) is connected to inlet of third diverter valve (21). The outlet of third diverter valve (21) is connected to generator (17) and condenser (20) and condenser (9) respectively. 7) Connect to the peak heater (12); the return water outlet of the heat network is first connected to the heat network water inlet of the heat storage heat exchanger (9), the heat network water outlet of the heat storage heat exchanger (9) is connected to the heat network water inlet of the absorber (10), the heat network water outlet of the absorber (10) is connected to the heat network water inlet of the condenser (11), the heat network water outlet of the condenser (11) is connected to the heat network water inlet of the peak heater (12), and the heat network water outlet of the peak heater (12) is connected to the heat network.

2. The combined heat and power system of the integrated thermal storage heat exchanger and heat pump 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.

3. The combined heat and power system of the integrated thermal storage heat exchanger and heat pump according to claim 1, characterized in that, The hydrophobic material from the peak heater (12) can enter the condenser (5) or deaerator.

4. The method for operating a combined heat and power system with an integrated thermal storage heat exchanger and a heat pump according to any one of claims 1-3, characterized in that: Includes heat storage mode and heat release mode; The heat storage mode includes: the combined heat and power system of the integrated heat storage heat exchanger and heat pump, when the unit does not supply heat to the outside and generates excess electricity, the excess electricity is transmitted to the compressor (14) through the transmission line. The circulating working fluid is compressed by the compressor (14) and becomes a high temperature and high pressure gas, which then enters the heat storage heat exchanger (9) to store the heat. The heat release mode includes: the combined heat and power system integrating the heat storage heat exchanger and the heat pump, when the unit supplies heat to the outside, the heat network return water enters from the heat network water inlet of the heat storage heat exchanger (9) and is heated by absorbing the heat stored in the heat storage heat exchanger (9); at the same time, the refrigerant of the absorption heat pump enters from the refrigerant inlet of the heat storage heat exchanger (9) and becomes saturated steam by absorbing the heat stored in the heat storage heat exchanger (9), and then flows to the absorber (10).

5. The operation method of the combined heat and power system integrating a thermal storage heat exchanger and a heat pump according to claim 4, characterized in that, The return water from the heat exchanger enters the heat exchanger (9) and exchanges heat with the circulating medium in the electric heat pump to complete the first heating. Then, the water from the heat exchanger (9) enters the absorber (10) and the heat exchanger water inlet to complete the second heating. Then, the water from the absorber (10) enters the condenser (11) and the heat exchanger water inlet to complete the third heating. Finally, the water from the condenser (11) enters the peak heater (12) to complete the fourth heating. After reaching the required temperature, it is used as the heat supply water for the heat exchanger.

6. The operation method of the combined heat and power system integrating a thermal storage heat exchanger and a heat pump according to claim 4, characterized in that, Given a fixed temperature rise range for each heating cycle, the remaining parameters can be determined by determining one of the following: the return water volume of the heat exchanger (9), the mass flow rate of the working fluid in the electric heat pump, and the flow ratio of the second diversion valve (8) and the third diversion valve (21).

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