Combined heat and power generation system

Abstract

The invention provides a combined heat and power generation system. The combined heat and power generation system comprises a low-pressure bypass pipeline, a first branch pipe, a first three-way valve, a heating main pipe, a second branch pipe, a heat storage heat exchanger, a low-temperature water storage tank, a high-temperature water storage tank, a third branch pipe and a fourth branch pipe. An inlet of the first three-way valve is connected with the low-pressure bypass pipeline, and a first outlet of the first three-way valve is connected with the first branch pipe; the heating main pipe is connected with the input end of the second branch pipe, and the output end of the second branch pipe is connected with the first input end of the heat storage heat exchanger; the first output end of the heat storage heat exchanger is connected with the high-temperature water storage tank through a third branch pipe; the second input end of the heat storage heat exchanger is connected with the low-temperature water storage tank, and the second output end of the heat storage heat exchanger is connected with the high-temperature water storage tank through a fourth branch pipe. The method has the technical effects that the design is reasonable, the requirement for flexibility adjustment of a novel electric power system cogeneration unit can be met, and unit thermoelectric deep decoupling is achieved.

Description

Technical Field

[0001] This invention belongs to the technical field of combined heat and power (CHP) units, and specifically relates to a CHP system. Background Technology

[0002] For most heating units, low-pressure cylinders operate at zero output during the heating season. While this achieves a significant degree of thermoelectric decoupling, their heating capacity can be further explored. During the non-heating season, when there is no external heating demand, the unit operates in pure condensing mode, with a minimum deep-adjustment load of approximately 25-30% THA. If further reduction in unit output is required, the conventional approach is to configure molten salt thermal storage or battery systems, which have drawbacks such as high investment costs and low adoption rates.

[0003] Therefore, there is an urgent need for a combined heat and power system that can improve the deep adjustment capability of the unit, has low investment and high adoption rate. Summary of the Invention

[0004] The present invention aims to solve at least one of the technical problems existing in the prior art and provide a new technical solution for a combined heat and power system.

[0005] According to a first aspect of the present invention, a combined heat and power system is provided, comprising: The system includes a low-pressure bypass pipeline, a first branch pipe, a first three-way valve, and a heating main pipe. The inlet of the first three-way valve is connected to the low-pressure bypass pipeline, the first outlet of the first three-way valve is connected to the first branch pipe, and the second outlet of the first three-way valve is used to output hot reheat steam. The low-pressure bypass pipeline is connected to the heating main pipe through the first branch pipe. The system comprises a second branch pipe, a heat storage heat exchanger, a low-temperature water storage tank, a high-temperature water storage tank, a third branch pipe, and a fourth branch pipe. The heating main pipe is connected to the input end of the second branch pipe, and the output end of the second branch pipe is connected to the first input end of the heat storage heat exchanger. The first output end of the heat storage heat exchanger is connected to the high-temperature water storage tank via the third branch pipe. The second input end of the heat storage heat exchanger is connected to the low-temperature water storage tank, and the second output end of the heat storage heat exchanger is connected to the high-temperature water storage tank via the fourth branch pipe. Steam in the heating main pipe enters the heat storage heat exchanger through the second branch pipe and heats the cold water input into the heat storage heat exchanger from the low temperature water storage tank. After the cold water is heated, it enters the high temperature water storage tank through the fourth branch pipe, and the condensate after the steam is cooled enters the high temperature water storage tank through the third branch pipe.

[0006] Optionally, the cogeneration system also includes a low-pressure heater and a fine processor; The input end of the low-temperature water storage tank is connected to the outlet of the fine processor; the output end of the high-temperature water storage tank is connected to the inlet of the low-pressure heater.

[0007] Optionally, the cogeneration system also includes a fifth branch pipe; One end of the fifth branch pipe is connected to the high-temperature water storage tank, and the other end is connected to the low-temperature water storage tank.

[0008] Optionally, the cogeneration system also includes a first check valve, a first isolation valve, and a first regulating valve; The first branch pipe is sequentially equipped with the first check valve, the first isolation valve and the first regulating valve, and the first check valve is close to the first three-way valve.

[0009] Optionally, the cogeneration system further includes a second three-way valve, the inlet of which is connected to the heating main pipe, the first outlet of which is connected to the second branch pipe, and the second outlet of which is used to output steam from the heating main pipe.

[0010] Optionally, the cogeneration system also includes a second check valve, a second isolation valve, and a second regulating valve; The second branch pipe is sequentially equipped with the second check valve, the second isolation valve, and the second regulating valve, with the second check valve located near the heating main pipe.

[0011] Optionally, the cogeneration system also includes a first water pump, which is installed on the pipeline connecting the low-temperature water storage tank and the heat exchanger.

[0012] Optionally, the cogeneration system also includes a second water pump, which is installed on the pipeline connecting the high-temperature water storage tank and the low-pressure heater.

[0013] Optionally, the second water pump is located on the pipeline connecting the high-temperature water storage tank and the low-temperature water storage tank.

[0014] Optionally, the cogeneration system also includes a heating network heater and a condenser; The second outlet of the second three-way valve is connected to the first input end of the heating network heater, and the first output end of the heating network heater is connected to the outlet of the condenser; the second input end of the heating network heater is used to input heating return water, and the second output end of the heating network heater is used to output heating supply water.

[0015] One technical advantage of this invention is that: In the embodiments of this application, the cogeneration system can adapt to the requirements of flexible adjustment of cogeneration units in new power systems, realize deep decoupling of heat and electricity in the unit, and enable the heating unit to have a high heating capacity in the heating season and a higher deep peak shaving capacity in the non-heating season. Attached Figure Description

[0016] Figure 1This is a schematic diagram of a combined heat and power system according to an embodiment of the present invention.

[0017] In the diagram: 1. Low-pressure bypass pipe; 2. First branch pipe; 3. First three-way valve; 4. Heating main pipe; 5. Second branch pipe; 6. Heat exchanger; 7. Low-temperature water storage tank; 8. High-temperature water storage tank; 9. Third branch pipe; 10. Fourth branch pipe; 11. Low-pressure bypass valve; 12. Low-pressure heater; 13. Fine processor; 14. Fifth branch pipe; 15. First check valve; 16. First isolation valve; 17. First regulating valve; 18. Second three-way valve; 19. Second check valve; 20. Second isolation valve; 21. Second regulating valve; 22. First water pump; 23. Second water pump; 24. Heat network heater; 25. Condenser; 26. Third isolation valve. Detailed Implementation

[0018] Various exemplary embodiments of this application will now be described in detail with reference to the accompanying drawings. It should be noted that, unless otherwise specifically stated, the relative arrangement, numerical expressions, and values ​​of the components and steps set forth in these embodiments do not limit the scope of this application.

[0019] The embodiments of this application will now be described in detail. Examples of these embodiments are illustrated in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain this application, and should not be construed as limiting this application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application.

[0020] The terms "first" and "second" in the specification and claims of this application may explicitly or implicitly include one or more of the features. In the description of this application, unless otherwise stated, "multiple" means two or more. Furthermore, "and / or" in the specification and claims indicates at least one of the connected objects, and the character " / " generally indicates that the preceding and following objects are in an "or" relationship.

[0021] In the description of this application, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc., indicating the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application.

[0022] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection between two components. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0023] According to a first aspect of the invention, see Figure 1 This invention provides a combined heat and power system that achieves deep decoupling of heat and electricity in the unit, and enables the heating unit to have a high heating capacity during the heating season and a higher peak-shaving capacity during the non-heating season.

[0024] Specifically, the combined heat and power system includes: The system includes a low-pressure bypass pipe 1, a first branch pipe 2, a first three-way valve 3, and a heating main pipe 4. The inlet of the first three-way valve 3 is connected to the low-pressure bypass pipe 1, the first outlet of the first three-way valve 3 is connected to the first branch pipe 2, and the second outlet of the first three-way valve 3 is used to output hot reheat steam. The low-pressure bypass pipe 1 is connected to the heating main pipe 4 through the first branch pipe 2. The system comprises a second branch pipe 5, a heat storage heat exchanger 6, a low-temperature water storage tank 7, a high-temperature water storage tank 8, a third branch pipe 9, and a fourth branch pipe 10. The heating main pipe 4 is connected to the input end of the second branch pipe 5, and the output end of the second branch pipe 5 is connected to the first input end of the heat storage heat exchanger 6. The first output end of the heat storage heat exchanger 6 is connected to the high-temperature water storage tank 8 through the third branch pipe 9. The second input end of the heat storage heat exchanger 6 is connected to the low-temperature water storage tank 7, and the second output end of the heat storage heat exchanger 6 is connected to the high-temperature water storage tank 8 through the fourth branch pipe 10. Steam in the heating main pipe 4 enters the heat storage heat exchanger 6 through the second branch pipe 5 and heats the cold water input into the heat storage heat exchanger 6 from the low temperature water storage tank 7. After the cold water is heated, it enters the high temperature water storage tank 8 through the fourth branch pipe 10, and the condensate after the steam is cooled enters the high temperature water storage tank 8 through the third branch pipe 9.

[0025] In this embodiment, the high-temperature water storage tank 8 enables the recovery of energy from reheated steam, achieving efficient utilization of reheated steam energy in combined heat and power (CHP) systems. This effectively avoids the significant high-temperature waste caused by directly depressurizing and supplying reheated steam externally. It also enables the recovery of energy from the exhaust gas from the intermediate-pressure cylinder, thus reducing the unit's load. Furthermore, the recovered heat can be injected into the unit's regenerative system, reducing steam extraction from the regenerative system (deaerator, four-stage low-pressure heater 12), thereby increasing the unit's work output and achieving a load increase. This CHP system can adapt to the flexible adjustment requirements of CHP units in new power systems, achieving deep decoupling of the unit's heat and electricity, and enabling heating units to have high heating capacity during the heating season and higher peak-shaving capacity during the non-heating season.

[0026] For example, the cold water (around 35°C) in the low-temperature water storage tank 7 can be heated to around 95°C in the heat exchanger 6, and then flows into the high-temperature water storage tank 8.

[0027] Optionally, the cogeneration system also includes a low-pressure heater 12 and a fine processor 13; The input end of the low-temperature water storage tank 7 is connected to the outlet of the fine processor 13; the output end of the high-temperature water storage tank 8 is connected to the inlet of the low-pressure heater 12.

[0028] In the above embodiment, the hot water in the high-temperature water storage tank 8 can be injected into the low-pressure heater 12, thereby realizing the recycling of energy and helping to save energy.

[0029] For example, the inlet of the fine processor 13 is connected to the condenser. The fine processor 13 and the low-pressure heater 12 are connected by a pipe.

[0030] Optionally, the cogeneration system also includes a fifth branch pipe 14; One end of the fifth branch pipe 14 is connected to the high-temperature water storage tank 8, and the other end is connected to the low-temperature water storage tank 7.

[0031] In the above embodiment, if the high-temperature water storage tank 8 reaches its water storage limit, hot water can be injected into the low-temperature water storage tank 7 through the fifth branch pipe 14, and the low-temperature water storage tank 7 can be used for hot water storage. The water storage method is relatively simple.

[0032] Optionally, the cogeneration system also includes a first check valve 15, a first isolation valve 16, and a first regulating valve 17; The first branch pipe 2 is sequentially provided with the first check valve 15, the first isolation valve 16 and the first regulating valve 17, and the first check valve 15 is close to the first three-way valve 3.

[0033] In the above embodiments, the flow rate of steam in the first branch pipe 2 can be adjusted by the first check valve 15, the first isolation valve 16 and the first regulating valve 17, which is simple and convenient to operate.

[0034] Optionally, the cogeneration system also includes a second three-way valve 18. The inlet of the second three-way valve 18 is connected to the heating main pipe 4, the first outlet of the second three-way valve 18 is connected to the second branch pipe 5, and the second outlet of the second three-way valve 18 is used to output steam from the heating main pipe 4. This simplifies the connection between the heating main pipe 4, the second branch pipe 5, and the heat network heater 24.

[0035] Optionally, the cogeneration system also includes a second check valve 19, a second isolation valve 20, and a second regulating valve 21; The second branch pipe 5 is sequentially equipped with the second check valve 19, the second isolation valve 20, and the second regulating valve 21, with the second check valve 19 being close to the heating main pipe 4.

[0036] In the above embodiments, the flow rate of steam in the second branch pipe 5 can be adjusted by the first check valve 15, the first isolation valve 16 and the first regulating valve 17, which is simple and convenient to operate.

[0037] Optionally, the cogeneration system also includes a first water pump 22, which is installed on the pipeline connecting the low-temperature water storage tank 7 and the heat exchanger 6. The first water pump 22 can effectively pump the cold water in the low-temperature water storage tank 7 into the heat exchanger 6 for heating, and the operation is simple and convenient.

[0038] Optionally, the cogeneration system also includes a second water pump 23, which is installed on the pipeline connecting the high-temperature water storage tank 8 and the low-pressure heater 12. The second water pump 23 can effectively pump the hot water from the high-temperature water storage tank 8 into the low-pressure heater 12 for recycling, thus helping to save energy.

[0039] Optionally, the second water pump 23 is located on the pipeline connecting the high-temperature water storage tank 8 and the low-temperature water storage tank 7. The second water pump 23 can effectively pump hot water from the high-temperature water storage tank 8 into the low-temperature water storage tank 7 to achieve hot water storage.

[0040] Optionally, the cogeneration system also includes a heat network heater 24 and a condenser 25; The second outlet of the second three-way valve 18 is connected to the first input end of the heating network heater 24, and the first output end of the heating network heater 24 is connected to the outlet of the condenser 25; the second input end of the heating network heater 24 is used to input heating return water, and the second output end of the heating network heater 24 is used to output heating supply water.

[0041] In the above embodiment, the steam in the heating main pipe 4 heats the heating return water at the heating network heater 24 to form heating water supply, while the condensate flows to the outlet of the condenser 25 for recycling.

[0042] Optionally, the second outlet of the first three-way valve 3 is connected to the condenser 25, and a third isolation valve 26 is provided on the pipeline connecting the second outlet of the first three-way valve 3 to the condenser 25. This helps to control the steam flow pattern in the low-pressure bypass pipeline 1 and is easy to operate.

[0043] For example, the low-pressure bypass pipeline 1 is provided with a low-pressure bypass valve 11, and the connection point between the first branch pipe 2 and the low-pressure bypass pipeline 1 is located downstream of the low-pressure bypass valve 11.

[0044] It should be noted that, Figure 1 The connection relationships of the various components in the technical solution of this application are shown, while the connection relationships of the various components in the prior art (such as high-pressure cylinder, medium-pressure cylinder, low-pressure cylinder, boiler, etc.) will not be described in detail here. Moreover, in order to facilitate the control of the flow rate of steam or water in the pipeline, the corresponding pipeline is equipped with check valves, isolation valves and regulating valves, which are conventional technologies and will not be described in detail here.

[0045] In this embodiment, the cogeneration system can achieve supplementary heating operation during the heating season. Specifically, during the heating season, when the steam turbine operates in the low-pressure cylinder zero-output heating mode, the valves between the low-pressure bypass valve 11 and the heating supply main pipe 4 (i.e., the low-pressure cylinder zero-output main pipe) can be opened, so that the reheated steam can be de-heated and depressurized through the low-pressure bypass valve 11 to supplement the heating steam supply, thereby improving the unit's heating capacity.

[0046] Furthermore, this cogeneration system can also achieve a heat storage and peak-shaving operation mode for the unit's regenerative system during the heating season. When the unit is operating at a deep peak load P, the heating capacity in the low-pressure cylinder zero-output mode is Q_supply. If Q_supply exceeds the user demand Q_demand, the steam supply in the low-pressure cylinder zero-output heating mode exceeds the external heating demand. This results in some unused exhaust steam from the intermediate-pressure cylinder. In this case, the valves between the heating supply header 4 and the heat exchanger 6 are opened to heat the cold water with this unused steam, converting it into hot water which is then stored in the high-temperature storage tank 8. When user demand increases (demand changes with temperature), the hot water stored in the high-temperature tank is injected into the inlet of the low-pressure heater 12, reducing the steam extraction from the regenerative system and thus increasing the external steam supply from the heating supply header, thereby increasing the unit's heating capacity.

[0047] Furthermore, this cogeneration system can also achieve peak-shaving operation of the unit's regenerative system during the non-heating season. During non-heating season operation, the minimum pure condensing load of a conventional unit is about 30% Pe (electrical power). At this time, the cogeneration system of this invention can be used to extract the exhaust steam from the intermediate-pressure cylinder through the heating supply main pipe 4 and the second branch pipe 5 (most of the exhaust steam can be extracted, for example, by using the low-pressure cylinder zero-output mode). The exhaust steam from the intermediate-pressure cylinder exchanges heat in the heat storage heat exchanger 6, and the condensate flows into the high-temperature water storage tank 8. When operating in this way, the minimum load of the unit can reach 24% Pe, which is 6% lower than the minimum electrical load of the unit under traditional pure condensing conditions.

[0048] In addition, this cogeneration system can also achieve auxiliary frequency regulation operation, as detailed below: First, reduce the unit load: When the unit needs to reduce the electrical load, the exhaust steam from the medium-pressure cylinder can be drawn through the heating main pipe 4 and the second branch pipe 5 and then stored in the heat storage heat exchanger 6 and stored in the high-temperature water tank. At this time, the amount of steam entering the low-pressure cylinder is reduced, the work done by the low-pressure cylinder is reduced, and the unit's electrical load decreases. Second, unit load increase: When the unit needs to increase the load, the cold water at the outlet of the fine processor 13 enters the low temperature water tank, and the high temperature water tank 8 injects the same mass of high temperature water into the unit's regenerative system. This can reduce the steam extraction of the regenerative system (deaerator, fourth-stage low-pressure heater 12), thereby increasing the unit's work and realizing the unit load increase.

[0049] Therefore, the cogeneration system of this application has the following technical advantages: First, improved heating capacity: The combined heat and power system proposed in this invention can increase the heating capacity of a single unit by 20% compared to the current mainstream low-pressure cylinder zero-output heating mode.

[0050] Second, enhanced peak shaving capability: Through the heat storage and peak shaving of the regenerator system, the unit can further reduce the output load by 6%Pe on the basis of the original minimum output of pure condensing.

[0051] Third, the frequency regulation capability of the unit is improved: the cogeneration system proposed in this invention can improve the frequency regulation and load change rate by 15% compared with the unmodified unit.

[0052] Fourth, high thermoelectric conversion efficiency: Compared to the approximately 15% electro-thermal-electric conversion efficiency of molten salt thermal storage, the electro-thermal-electric conversion efficiency of the thermal storage process in this invention reaches as high as 75%. It is understood that the above embodiments are merely exemplary embodiments used to illustrate the principles of this invention; however, this invention is not limited thereto. For those skilled in the art, various modifications and improvements can be made without departing from the spirit and essence of this invention, and these modifications and improvements are also considered to be within the scope of protection of this invention.

Claims

1. A combined heat and power system, characterized in that, include: The system includes a low-pressure bypass pipeline, a first branch pipe, a first three-way valve, and a heating main pipe. The inlet of the first three-way valve is connected to the low-pressure bypass pipeline, the first outlet of the first three-way valve is connected to the first branch pipe, and the second outlet of the first three-way valve is used to output hot reheat steam. The low-pressure bypass pipeline is connected to the heating main pipe through the first branch pipe. The system comprises a second branch pipe, a heat storage heat exchanger, a low-temperature water storage tank, a high-temperature water storage tank, a third branch pipe, and a fourth branch pipe. The heating main pipe is connected to the input end of the second branch pipe, and the output end of the second branch pipe is connected to the first input end of the heat storage heat exchanger. The first output end of the heat storage heat exchanger is connected to the high-temperature water storage tank via the third branch pipe. The second input end of the heat storage heat exchanger is connected to the low-temperature water storage tank, and the second output end of the heat storage heat exchanger is connected to the high-temperature water storage tank via the fourth branch pipe. Steam in the heating main pipe enters the heat storage heat exchanger through the second branch pipe and heats the cold water input into the heat storage heat exchanger from the low temperature water storage tank. After the cold water is heated, it enters the high temperature water storage tank through the fourth branch pipe, and the condensate after the steam is cooled enters the high temperature water storage tank through the third branch pipe.

2. The cogeneration system according to claim 1, characterized in that, It also includes a low-pressure heater and a fine processor; The input end of the low-temperature water storage tank is connected to the outlet of the fine processor; the output end of the high-temperature water storage tank is connected to the inlet of the low-pressure heater.

3. The cogeneration system according to claim 2, characterized in that, It also includes the fifth branch pipe; One end of the fifth branch pipe is connected to the high-temperature water storage tank, and the other end is connected to the low-temperature water storage tank.

4. The cogeneration system according to claim 1, characterized in that, It also includes a first check valve, a first isolation valve, and a first regulating valve; The first branch pipe is sequentially equipped with the first check valve, the first isolation valve and the first regulating valve, and the first check valve is close to the first three-way valve.

5. The cogeneration system according to claim 1, characterized in that, It also includes a second three-way valve, the inlet of which is connected to the heating main pipe, the first outlet of which is connected to the second branch pipe, and the second outlet of which is used to output steam from the heating main pipe.

6. The cogeneration system according to claim 1, characterized in that, It also includes a second check valve, a second isolation valve, and a second regulating valve; The second branch pipe is sequentially equipped with the second check valve, the second isolation valve, and the second regulating valve, with the second check valve located near the heating main pipe.

7. The cogeneration system according to claim 1, characterized in that, It also includes a first water pump, which is installed on the pipeline connecting the low-temperature water storage tank and the heat exchanger.

8. The cogeneration system according to claim 2, characterized in that, It also includes a second water pump, which is installed on the pipeline connecting the high-temperature water storage tank and the low-pressure heater.

9. The cogeneration system according to claim 8, characterized in that, The second water pump is located on the pipeline connecting the high-temperature water storage tank and the low-temperature water storage tank.

10. The cogeneration system according to claim 5, characterized in that, It also includes heating network heaters and condensers; The second outlet of the second three-way valve is connected to the first input end of the heating network heater, and the first output end of the heating network heater is connected to the outlet of the condenser; the second input end of the heating network heater is used to input heating return water, and the second output end of the heating network heater is used to output heating supply water.

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