Supercritical co2 cycle combined heat and power system and method of operation thereof

Abstract

The embodiment of the present disclosure provides a supercritical CO2 combined heat and power system and an operation method thereof. One of the outlet of a boiler, the cold side outlet of a high-temperature regenerator and the cold side outlet of a low-temperature regenerator is selectively connected with a high-pressure inlet of an ejector to deliver high-temperature and high-pressure CO2 to the ejector; the hot side outlet of the low-temperature regenerator is connected with a low-pressure inlet of the ejector to deliver low-temperature and low-pressure CO2 to the ejector; the outlet of the ejector is connected with an inlet of a heat network heater, and the outlet of the heat network heater is connected with a supercritical CO2 coal-fired power generation system and a heating user respectively. The supercritical CO2 coal-fired power generation system cold end low-temperature and low-pressure CO2 is heated by the ejector, the system cold end waste heat can be recovered, the cold source loss is reduced, and the system energy comprehensive utilization efficiency is improved; according to the heating condition, different high-temperature and high-pressure CO2 sources are selected to flexibly meet the demand of the user for different heat loads.

Description

TECHNICAL FIELD

[0001] The embodiment of the present disclosure belongs to the technical field of combined heat and power generation, and particularly relates to a supercritical CO2 cycle combined heat and power generation system and a method for operating the same. BACKGROUND

[0002] The supercritical CO2 power cycle has advantages of high efficiency and flexibility, and is expected to replace the traditional steam Rankine cycle in the field of coal-fired power generation, greatly improve the power generation efficiency and peak shaving capacity of the coal-fired unit, reduce the pollution and CO2 emission of the unit, and promote large-scale consumption of renewable energy and low-carbon development of the power industry. However, the demand for energy products in the society is diversified, not only including power demand, but also heat demand. The traditional thermal power unit can generally meet the demand of the society for power and heat. The combined heat and power unit can not only reduce the loss of cold source and improve the energy utilization efficiency of the unit through heat supply, but also can generate great economic benefits. Therefore, the design of combined heat and power generation of the new supercritical CO2 power unit is particularly important. At present, the research on the supercritical CO2 cycle coal-fired power generation technology pays more attention to the efficient and flexible power generation, and less attention to the efficient heat supply design of the unit.

[0003] In view of the above problems, it is necessary to provide a supercritical CO2 cycle combined heat and power generation system and a method for operating the same, which are reasonable in design and effective in solving the above problems. SUMMARY

[0004] The embodiment of the present disclosure aims to at least solve one of the technical problems existing in the prior art, and provides a supercritical CO2 cycle combined heat and power generation system and a method for operating the same.

[0005] One aspect of the embodiment of the present disclosure provides a supercritical CO2 cycle combined heat and power generation system, comprising a supercritical CO2 coal-fired power generation system and a heat supply system; the supercritical CO2 coal-fired power generation system comprises a boiler, a high-temperature regenerator, a low-temperature regenerator and a second-stage precooler, and the heat supply system comprises an ejector and a heat network heater; wherein,

[0006] The hot side outlet of the low-temperature regenerator is in communication with the low-pressure inlet of the ejector to transport low-temperature and low-pressure CO2 to the ejector;

[0007] One of the outlet of the boiler, the cold side outlet of the high-temperature regenerator and the cold side outlet of the low-temperature regenerator is selectively in communication with the high-pressure inlet of the ejector to transport high-temperature and high-pressure CO2 to the ejector;

[0008] The inlet of the heat network heater is in communication with the outlet of the ejector, and the outlet of the heat network heater is in communication with the supercritical CO2 coal-fired power generation system and a heating user, respectively;

[0009] The ejector is configured to mix the high-temperature and high-pressure CO2 and the low-temperature and low-pressure CO2 into medium-temperature and medium-pressure CO2 and then deliver the medium-temperature and medium-pressure CO2 to the heat network heater.

[0010] Optionally, during the initial and final periods of heating, the cold side outlet of the low-temperature recuperator is connected in communication with the high-pressure inlet of the ejector.

[0011] During the middle period of heating, one of the outlet of the boiler or the cold side outlet of the high-temperature recuperator is connected in communication with the high-pressure inlet of the ejector.

[0012] Optionally, the heating system further comprises a first valve.

[0013] The first valve is arranged in a communication pipeline between the boiler and the ejector.

[0014] Optionally, the heating system further comprises a second valve.

[0015] The second valve is arranged in a communication pipeline between the high-temperature recuperator and the ejector.

[0016] Optionally, the heating system further comprises a third valve.

[0017] The third valve is arranged in a communication pipeline between the low-temperature recuperator and the ejector.

[0018] Optionally, the supercritical CO2 coal-fired power generation system further comprises a first-stage main compressor, a second-stage main compressor, a first-stage pre-cooler and a second-stage pre-cooler.

[0019] The inlet of the first-stage pre-cooler is connected in communication with the hot side outlet of the low-temperature recuperator, and the outlet of the first-stage pre-cooler is connected in communication with the inlet of the first-stage main compressor.

[0020] The inlet of the second-stage pre-cooler is connected in communication with the outlet of the first-stage main compressor and the low-pressure inlet of the ejector respectively, and the outlet of the second-stage pre-cooler is connected in communication with the inlet of the second-stage main compressor.

[0021] The outlet of the second-stage main compressor is connected in communication with the cold side inlet of the low-temperature recuperator.

[0022] Optionally, the supercritical CO2 coal-fired power generation system further comprises a re-compressor.

[0023] The inlet and outlet of the re-compressor are connected in communication with the hot side outlet of the low-temperature recuperator and the cold side outlet of the low-temperature recuperator respectively.

[0024] Optionally, the supercritical CO2 coal-fired power generation system further comprises a turbine.

[0025] The inlet of the turbine is connected with the outlet of the boiler, and the outlet of the turbine is connected with the inlet of the high-temperature regenerator;

[0026] The cold side outlet of the high-temperature regenerator is connected with the inlet of the boiler;

[0027] The hot side outlet of the high-temperature regenerator is connected with the hot side inlet of the low-temperature regenerator;

[0028] The cold side outlet of the low-temperature regenerator is connected with the cold side inlet of the high-temperature regenerator.

[0029] Another aspect of the embodiments of the present disclosure provides a method for operating a supercritical CO2 cycle combined heat and power system, which adopts the supercritical CO2 cycle combined heat and power system described above; the method comprises:

[0030] The hot side outlet of the low-temperature regenerator is connected with the low-pressure inlet of the ejector to deliver low-temperature and low-pressure CO2 to the ejector;

[0031] According to the heating condition, one of the outlet of the boiler, the cold side outlet of the high-temperature regenerator and the cold side outlet of the low-temperature regenerator is selectively connected with the high-pressure inlet of the ejector to deliver high-temperature and high-pressure CO2 to the ejector;

[0032] The inlet of the heat network heater is connected with the outlet of the ejector, and the outlet of the heat network heater is connected with the supercritical CO2 coal-fired power generation system and the heating user respectively; wherein

[0033] The high-temperature and high-pressure CO2 and the low-temperature and low-pressure CO2 are mixed into medium-temperature and medium-pressure CO2 by the ejector and then delivered to the heat network heater.

[0034] Optionally, the method further comprises:

[0035] During the initial and final periods of heating, the cold side outlet of the low-temperature regenerator is connected with the high-pressure inlet of the ejector, and the high-temperature and high-pressure CO2 of the low-temperature regenerator is delivered to the ejector;

[0036] During the middle period of heating, one of the outlet of the boiler or the cold side outlet of the high-temperature regenerator is connected with the high-pressure inlet of the ejector, and the high-temperature and high-pressure CO2 of the boiler or the high-temperature regenerator is delivered to the ejector.

[0037] This disclosure discloses a supercritical CO2 cycle cogeneration system and its operation method. In this system, an ejector is used to extract a low-temperature, low-pressure CO2 stream from the cold end of a supercritical CO2 coal-fired power generation system using a high-temperature, high-pressure CO2 stream from one of three sources: a boiler, a high-temperature regenerator, or a low-temperature regenerator. The two streams mix in the ejector to form a medium-temperature, medium-pressure CO2 stream, which then enters the heating network heater for heating. Part of the heated medium-temperature, medium-pressure CO2 is used for user heating, while the other part returns to the supercritical CO2 coal-fired power generation system to participate in the cycle. By extracting low-temperature, low-pressure CO2 from the cold end of the supercritical CO2 coal-fired power generation system for heating, waste heat from the cold end of the system can be recovered, cold source losses can be reduced, and the overall energy utilization efficiency of the system can be improved. Different high-temperature, high-pressure CO2 sources can be selected according to the heating conditions to flexibly meet the user's different heat load requirements. The ejector has no moving parts.

[0038] It has a simple structure and requires relatively little investment. Attached Figure Description

[0039] Figure 1 This is a schematic diagram of the structure of a supercritical CO2 cycle cogeneration system according to one embodiment of the present disclosure;

[0040] Figure 2 This is a flowchart illustrating the operation method of a supercritical CO2 cycle cogeneration system according to another embodiment of this disclosure. Detailed Implementation

[0041] To enable those skilled in the art to better understand the technical solutions of the embodiments of this disclosure, the embodiments of this disclosure will be further described in detail below with reference to the accompanying drawings and specific implementation methods.

[0042] like Figure 1 As shown, this disclosure provides a supercritical CO2 cycle cogeneration system, which includes a supercritical CO2 coal-fired power generation system and a heating system. The supercritical CO2 coal-fired power generation system includes a first-stage main compressor 1, a second-stage precooler 2, a second-stage main compressor 3, a low-temperature regenerator 4, a high-temperature regenerator 5, a boiler 6, a turbine 7, a high-temperature regenerator 5, a low-temperature regenerator 4, and a first-stage precooler 8, connected in sequence. It also includes a re-compressor 9, whose inlet and outlet are connected to the hot-side outlet and cold-side outlet of the low-temperature regenerator 4, respectively.

[0043] The heating system includes an ejector 10 and a heating network heater 11.

[0044] The inlet of the first-stage precooler 8 is connected to the hot-side outlet of the low-temperature regenerator 4, and the outlet of the first-stage precooler 8 is connected to the inlet of the first-stage main compressor 1.

[0045] The inlet of the second stage pre-cooler 2 is connected with the outlet of the first stage main compressor 1 and the low pressure inlet of the ejector 10 respectively, and the outlet of the second stage pre-cooler 2 is connected with the inlet of the second stage main compressor 3.

[0046] The outlet of the second stage main compressor 3 is connected with the cold side inlet of the low temperature recuperator 4.

[0047] The inlet of the turbine 7 is connected with the outlet of the boiler 6, and the outlet of the turbine 7 is connected with the inlet of the high temperature recuperator 5.

[0048] The cold side outlet of the high temperature recuperator 5 is connected with the inlet of the boiler 6.

[0049] The hot side outlet of the high temperature recuperator 5 is connected with the hot side inlet of the low temperature recuperator 4.

[0050] The cold side outlet of the low temperature recuperator 4 is connected with the cold side inlet of the high temperature recuperator 5.

[0051] The hot side outlet of the low temperature recuperator 4 is connected with the low pressure inlet of the ejector 10, so as to deliver low temperature and low pressure CO2 to the ejector 10.

[0052] One of the outlet of the boiler 6, the cold side outlet of the high temperature recuperator 5 and the cold side outlet of the low temperature recuperator 4 is selectively connected with the high pressure inlet of the ejector 10, so as to deliver high temperature and high pressure CO2 to the ejector 10.

[0053] The inlet of the heat network heater 11 is connected with the outlet of the ejector 10, and the outlet of the heat network heater 11 is connected with the second stage pre-cooler 2 of the supercritical CO2 coal-fired power generation system and the heating user respectively.

[0054] The ejector 10 is used to mix the high temperature and high pressure CO2 and the low temperature and low pressure CO2 into medium temperature and medium pressure CO2, and then deliver the medium temperature and medium pressure CO2 to the heat network heater 11.

[0055] The supercritical CO2 working medium is compressed by the first stage main compressor 1 and the second stage main compressor 3, and the inter-stage pressure is matched with the CO2 pressure at the outlet of the heat network heater 11.

[0056] Specifically, according to the heating condition, one of the outlet of the boiler 6, the cold side outlet of the high temperature recuperator 5 and the cold side outlet of the low temperature recuperator 4 is selectively connected with the high pressure inlet of the ejector 10, so as to deliver high temperature and high pressure CO2 to the ejector 10. 2。The hot side outlet of the low temperature recuperator 4 is communicated with the low pressure inlet of the ejector 10 to deliver low temperature and low pressure CO2 to the ejector 10. The ejector 10 mixes the high temperature and high pressure CO2 and the low temperature and low pressure CO2 into medium temperature and medium pressure CO2, and then delivers the medium temperature and medium pressure CO2 to the heat network heater 11 for heating. The heated medium temperature and medium pressure CO2 is used for heating users, and part of the heated medium temperature and medium pressure CO2 is returned to the supercritical CO2 coal-fired power generation system to participate in the cycle.

[0057] The supercritical CO2 combined cycle system of the embodiment of the present disclosure uses the high temperature and high pressure working medium to inject the low temperature and low pressure working medium at the cold end of the system, mixes the medium temperature and medium pressure working medium, and then heats the medium temperature and medium pressure working medium in the heat network heater to heat users, so that the purpose of efficient heating is achieved. In addition, part of the heated medium temperature and medium pressure working medium participates in the cycle of the critical CO2 coal-fired power generation system again, so that the energy utilization efficiency is improved. The system uses the supercritical CO2 coal-fired power generation system to inject the low temperature and low pressure CO2 at the cold end of the system to heat, so that the waste heat at the cold end of the system can be recovered, the loss of the cold source is reduced, and the comprehensive energy utilization efficiency of the system is improved. According to the heating condition, the high temperature and high pressure CO2 source with different temperatures is selected to flexibly meet the demand of users for different heat loads. The ejector has no moving parts, the structure is simple, and the investment is small.

[0058] For example, at the beginning and end of heating, the cold side outlet of the low temperature recuperator 4 is communicated with the high pressure inlet of the ejector 10.

[0059] During the middle of heating, one of the outlet of the boiler 6 or the cold side outlet of the high temperature recuperator 5 is communicated with the high pressure inlet of the ejector 10.

[0060] Specifically, at the beginning and end of heating, since the heating load demand is small, the high temperature and high pressure CO2 used for injection can be selected from the working medium with a lower temperature at the cold side outlet of the low temperature recuperator 4.

[0061] That is, at the beginning and end of heating, the cold side outlet of the low temperature recuperator 4 is communicated with the high pressure inlet of the ejector 10, the high temperature and high pressure CO2 used for injection is provided to the ejector 10 through the low temperature recuperator 4, and the high temperature and high pressure CO2 is mixed with the low temperature and low pressure CO2 at the cold end of the system to form the medium temperature and medium pressure CO2. 2。

[0062] During the middle of heating, since the heating load demand is large, the high temperature and high pressure CO2 can be selected from the working medium with a higher temperature at the cold side outlet of the high temperature recuperator 5 or the working medium with a higher temperature at the outlet of the boiler 6.

[0063] That is, during the middle of heating, one of the outlet of the boiler 6 or the cold side outlet of the high temperature recuperator 5 is communicated with the high pressure inlet of the ejector 10, the high temperature and high pressure CO2 used for injection is provided to the ejector 10 through the boiler 6 or the high temperature recuperator 5, and the high temperature and high pressure CO2 is mixed with the low temperature and low pressure CO2 at the cold end of the system to form the medium temperature and medium pressure CO2. 2。

[0064] In the embodiment, different high-temperature and high-pressure CO2 sources with different temperatures can be selected according to the heating condition, so as to flexibly meet the demand of the user for different heat loads, and further improve the energy comprehensive utilization efficiency of the system.

[0065] As shown in Figure 1 , the heating system further comprises a first valve 14 arranged in the communication pipeline between the boiler 6 and the ejector 10. The first valve 14 can be used to control the opening or closing of the communication pipeline between the boiler 6 and the ejector 10.

[0066] As shown in Figure 1 , the heating system further comprises a second valve 13 arranged in the communication pipeline between the high-temperature regenerator 5 and the ejector 10. The second valve 13 can be used to control the opening or closing of the communication pipeline between the high-temperature regenerator 5 and the ejector 10.

[0067] As shown in Figure 1 , the heating system further comprises a third valve 12 arranged in the communication pipeline between the low-temperature regenerator 4 and the ejector 10. The third valve 12 can be used to control the opening or closing of the communication pipeline between the low-temperature regenerator 4 and the ejector 10.

[0068] Specifically, when the boiler 6 needs to provide high-temperature and high-pressure CO2, the first valve 14 is opened, and the second valve 13 and the third valve 12 are closed. When the high-temperature regenerator 5 needs to provide high-temperature and high-pressure CO2, the second valve 13 is opened, and the first valve 14 and the third valve 12 are closed. When the low-temperature regenerator 4 needs to provide high-temperature and high-pressure CO2, the third valve 12 is opened, and the first valve 14 and the second valve 13 are closed.

[0069] In the embodiment, the high-temperature and high-pressure CO2 source for the ejection can be flexibly switched and combined among the three high-temperature and high-pressure CO2 sources by adjusting the first valve 14, the second valve 13 and the third valve 12 according to the size of the heat load.

[0070] As shown in Figure 2 , another aspect of the embodiment of the present disclosure provides a method S100 for operating a supercritical CO2 cycle combined heat and power system, which adopts the supercritical CO2 cycle combined heat and power system described above. The specific structural features of the supercritical CO2 cycle combined heat and power system have been described in detail above, and will not be described again here.

[0071] The method S100 for operating the supercritical CO2 cycle combined heat and power system specifically comprises:

[0072] S110, according to the heating condition, one of the outlet of the boiler, the cold side outlet of the high-temperature regenerator and the cold side outlet of the low-temperature regenerator is selectively communicated with the high-pressure inlet of the ejector to deliver high-temperature and high-pressure CO2 to the ejector.

[0073] Specifically, at the beginning and end of heating, the cold side outlet of the low-temperature regenerator 4 is communicated with the high-pressure inlet of the ejector 10, and the high-temperature and high-pressure CO2 of the low-temperature regenerator 4 is delivered to the ejector 10.

[0074] At the middle of heating, one of the outlet of the boiler 6 or the cold side outlet of the high-temperature regenerator 5 is communicated with the high-pressure inlet of the ejector 10, and the high-temperature and high-pressure CO2 of the boiler 6 or the high-temperature regenerator 5 is delivered to the ejector 10.

[0075] S120, the hot side outlet of the low-temperature regenerator is communicated with the low-pressure inlet of the ejector to deliver low-temperature and low-pressure CO2 to the ejector.

[0076] Specifically, the hot side outlet of the low-temperature regenerator 4 is communicated with the low-pressure inlet of the ejector 10 to deliver low-temperature and low-pressure CO2 to the ejector 10. That is, the low-temperature and low-pressure CO2 at the cold end of the supercritical CO2 coal-fired power generation system is injected by the ejector 10.

[0077] S130, the inlet of the heat network heater is communicated with the outlet of the ejector, and the outlet of the heat network heater is respectively communicated with the supercritical CO2 coal-fired power generation system and the heating user; wherein the high-temperature and high-pressure CO2 and the low-temperature and low-pressure CO2 are mixed into medium-temperature and medium-pressure CO2 by the ejector and then delivered to the heat network heater.

[0078] Specifically, the high-temperature and high-pressure CO2 and the low-temperature and low-pressure CO2 are mixed into medium-temperature and medium-pressure CO2 by the ejector 10 and then delivered to the heat network heater 11 for heating. Part of the medium-temperature and medium-pressure CO2 after heating is used for user heating, and the other part returns to the supercritical CO2 coal-fired power generation system to participate in the cycle.

[0079] The operation method of the supercritical CO2 combined cycle system of the embodiment of the present disclosure can recover the waste heat at the cold end of the system, reduce the loss of the cold source, and improve the comprehensive energy utilization efficiency of the system by injecting the low-temperature and low-pressure CO2 at the cold end of the supercritical CO2 coal-fired power generation system for heating. According to the heating condition, different sources of high-temperature and high-pressure CO2 are selected to flexibly meet the demand of users for different heat loads. The ejector has no moving parts, simple structure and small investment.

[0080] It can be understood that the above implementation is only an exemplary implementation adopted for illustrating the principles of the embodiments of the present disclosure, however, the embodiments of the present disclosure are not limited thereto. Various modifications and improvements can be made by those of ordinary skill in the art without departing from the spirit and principle of the embodiments of the present disclosure, and these modifications and improvements are also considered to be within the scope of protection of the embodiments of the present disclosure.

Claims

1. A method for operating a supercritical CO2 cycle combined heat and power system, characterized by, The application discloses a supercritical CO2 combined heat and power system, which comprises a supercritical CO2 coal-fired power generation system and a heating system; the supercritical CO2 coal-fired power generation system comprises a boiler, a high-temperature regenerator, a low-temperature regenerator and a second-stage pre-cooler; the heating system comprises an ejector and a heat network heater; wherein, one of the outlet of the boiler, the cold side outlet of the high-temperature regenerator and the cold side outlet of the low-temperature regenerator is selectively communicated with the high-pressure inlet of the ejector to deliver high-temperature and high-pressure CO2 to the ejector; the hot side outlet of the low-temperature regenerator is communicated with the low-pressure inlet of the ejector to deliver low-temperature and low-pressure CO2 to the ejector; the inlet of the heat network heater is communicated with the outlet of the ejector, and the outlet of the heat network heater is respectively communicated with the supercritical CO2 coal-fired power generation system and a heating user; wherein, the ejector is used for mixing the high-temperature and high-pressure CO2 and the low-temperature and low-pressure CO2 into medium-temperature and medium-pressure CO2 and then delivering the medium-temperature and medium-pressure CO2 to the heat network heater; the supercritical CO2 coal-fired power generation system further comprises a first-stage main compressor, a second-stage main compressor, a first-stage pre-cooler and a second-stage pre-cooler; the inlet of the first-stage pre-cooler is communicated with the hot side outlet of the low-temperature regenerator, and the outlet of the first-stage pre-cooler is communicated with the inlet of the first-stage main compressor; the inlet of the second-stage pre-cooler is respectively communicated with the outlet of the first-stage main compressor and the low-pressure inlet of the ejector, and the outlet of the second-stage pre-cooler is communicated with the inlet of the second-stage main compressor; the outlet of the second-stage main compressor is communicated with the cold side inlet of the low-temperature regenerator; the supercritical CO2 coal-fired power generation system further comprises a re-compressor; the inlet and the outlet of the re-compressor are respectively communicated with the hot side outlet of the low-temperature regenerator and the cold side outlet of the low-temperature regenerator; the supercritical CO2 coal-fired power generation system further comprises a turbine; the inlet of the turbine is communicated with the outlet of the boiler, and the outlet of the turbine is communicated with the inlet of the high-temperature regenerator; the cold side outlet of the high-temperature regenerator is communicated with the inlet of the boiler; the hot side outlet of the high-temperature regenerator is communicated with the hot side inlet of the low-temperature regenerator; the cold side outlet of the low-temperature regenerator is communicated with the cold side inlet of the high-temperature regenerator; wherein, the operation method comprises: selectively communicating one of the outlet of the boiler, the cold side outlet of the high-temperature regenerator and the cold side outlet of the low-temperature regenerator with the high-pressure inlet of the ejector to deliver high-temperature and high-pressure CO2 to the ejector according to the heating condition; communicating the hot side outlet of the low-temperature regenerator with the low-pressure inlet of the ejector to deliver low-temperature and low-pressure CO2 to the ejector; communicating the inlet of the heat network heater with the outlet of the ejector, and respectively communicating the outlet of the heat network heater with the supercritical CO2 coal-fired power generation system and a heating user; wherein, the high-temperature and high-pressure CO2 and the low-temperature and low-pressure CO2 are mixed into medium-temperature and medium-pressure CO2 by the ejector and then delivered to the heat network heater.

2. The method of claim 1, wherein, The operation method further comprises: in the initial and final stage of heating, connecting the cold side outlet of the low temperature recuperator with the high pressure inlet of the ejector, and delivering the high temperature and high pressure CO2 of the low temperature recuperator to the ejector; in the middle stage of heating, connecting one of the outlet of the boiler or the cold side outlet of the high temperature recuperator with the high pressure inlet of the ejector, and delivering the high temperature and high pressure CO2 of the boiler or the high temperature recuperator to the ejector.

3. The method of claim 1, wherein, The heating system further comprises a first valve; The first valve is arranged in the connecting pipeline between the boiler and the ejector.

4. The method of claim 1, wherein, The heating system further comprises a second valve; The second valve is arranged in the connecting pipeline between the high temperature recuperator and the ejector.

5. The method of claim 1, wherein, The heating system further comprises a third valve; The third valve is arranged in the connecting pipeline between the low temperature recuperator and the ejector.

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