A method and system for thermoelectric decoupling of a combined heat and power unit

Abstract

A method and system for thermoelectric decoupling of a cogeneration unit. First, a first thermoelectric decoupling method is adopted, that is, the self-decoupled heat of the first cogeneration unit is used to provide a self-decoupled heat load for the heating system; when the first thermoelectric decoupling method does not meet the thermoelectric decoupling requirement, a second thermoelectric decoupling method is adopted, that is, the self-decoupled heat of the first cogeneration unit is used to provide a self-decoupled heat load for the heating system, combined with providing an auxiliary decoupled heat load for the heating system by the second cogeneration unit, or, providing a supplementary decoupled heat load for the heating system by an external device; when the second thermoelectric decoupling method does not meet the thermoelectric decoupling requirement, the self-decoupled heat of the first cogeneration unit is used to provide a self-decoupled heat load for the heating system, the second cogeneration unit provides an auxiliary decoupled heat load for the heating system, and an external device provides a supplementary decoupled heat load for the heating system. The thermoelectric decoupling of the first cogeneration unit is realized.

Description

Technical Field

[0001] The present invention relates to the technical field of thermal power plants, and in particular to a thermoelectric decoupling method and system for a cogeneration unit. Background Art

[0002] The statements in this section merely provide background information related to the present invention and do not necessarily constitute prior art.

[0003] The current energy transition requires thermal power plants to possess a high degree of operational flexibility, enabling them to vary their power generation load over a wide range to absorb renewable energy. Cogeneration units shoulder the dual tasks of providing both heat and electricity. During the heating season, the power generation load is constrained by the heat load, preventing significant fluctuations in the power generation load. The heat and power loads are coupled, thus limiting the flexibility of cogeneration units. Traditionally, cogeneration units operate on a "heat-to-power" basis, where a certain amount of power generation load is matched by the amount of heat generated. Clearly, this operating model is no longer suitable for the current requirements for greater operational flexibility. Improving the flexibility of cogeneration units requires resolving the mutual constraints between heat and power loads—in other words, achieving thermal-electrical decoupling within the cogeneration system.

[0004] Although it is currently possible to use the waste heat of the cogeneration unit itself, the heat output of adjacent units and the heat output of external equipment to supplement the heating system, the three supplementary heating methods are not associated with the thermoelectric coupling of the cogeneration unit, and there is no limit on the order in which the three supplementary heating methods participate in the thermoelectric coupling of the cogeneration unit. When the unit is thermoelectrically coupled, there is a problem of waste of resources. Summary of the Invention

[0005] In order to solve the above problems, the present invention proposes a thermoelectric decoupling method and system for a cogeneration unit, which provides different thermoelectric decoupling modes for the thermoelectric decoupling of a first cogeneration unit and limits the priority of different thermoelectric decoupling modes. On the basis of ensuring that the thermoelectric decoupling requirements of the first cogeneration unit are met, resource waste is reduced.

[0006] To achieve the above object, the present invention adopts the following technical solutions:

[0007] In the first aspect, a method for thermal decoupling of a cogeneration unit is proposed, which is applied to a system including a first cogeneration unit, a second cogeneration unit, external equipment, and a heating system; the steam turbine of the first cogeneration unit, the self-decoupling heat of the first cogeneration unit, the second cogeneration unit, and the external equipment can all provide heat load for the heating system;

[0008] When the first combined heat and power unit performs heat-electricity decoupling, the first heat-electricity decoupling method is first adopted, that is, the self-decoupling heat of the first combined heat and power unit is used to provide the self-decoupling heat load for the heating system;

[0009] When the first heat-electricity decoupling method does not meet the heat-electricity decoupling requirements of the first combined heat and power unit, the second heat-electricity decoupling method is adopted, that is, the self-decoupling heat of the first combined heat and power unit is used to provide the self-decoupling heat load for the heating system, and the second combined heat and power unit is used to provide the auxiliary decoupling heat load for the heating system, or, the self-decoupling heat of the first combined heat and power unit is used to provide the self-decoupling heat load for the heating system, and an external device is used to provide the supplementary decoupling heat load for the heating system;

[0010] When the second heat-electricity decoupling method does not meet the heat-electricity decoupling requirements of the first combined heat and power unit, the third heat-electricity decoupling method is adopted, that is, the self-decoupling heat of the first combined heat and power unit is used to provide the self-decoupling heat load for the heating system, the second combined heat and power unit is used to provide the auxiliary decoupling heat load for the heating system, and an external device is used to provide the supplementary decoupling heat load for the heating system.

[0011] In a second aspect, a heat-electricity decoupling system of a combined heat and power unit is proposed, including a first combined heat and power unit, a second combined heat and power unit, an external device, and a heating system. The steam turbine of the first combined heat and power unit, the self-decoupling heat of the first combined heat and power unit, the second combined heat and power unit, and the external device can all provide heat load for the heating system;

[0012] When the first combined heat and power unit performs heat-electricity decoupling, the first combined heat and power unit, the second combined heat and power unit, and the external device adopt the heat-electricity decoupling method of a heat-electricity decoupling system of a combined heat and power unit proposed in the first aspect.

[0013] Compared with the prior art, the beneficial effects of the present invention are:

[0014] The present invention provides different thermoelectric decoupling methods for the first combined heat and power unit, and defines the priorities of different thermoelectric decoupling methods. On the basis of ensuring the thermoelectric decoupling requirements of the first combined heat and power unit, the problem of resource waste is reduced. The present invention combines one or several of the boiler waste heat, miscellaneous waste heat, main steam heat, reheated steam heat, extraction steam heat and intermediate pressure cylinder exhaust steam heat of the first combined heat and power unit itself as the self-decoupling heat of the first combined heat and power unit, and provides a self-decoupling heat load for the heating system, which can realize the deep thermoelectric decoupling of the first combined heat and power unit. The highest thermoelectric decoupling amplitude can realize the complete decoupling of the heat load and the electric load of the combined heat and power unit, and make full use of the heat of the first combined heat and power unit itself to achieve complete thermoelectric decoupling as much as possible. With relatively small investment, the flexibility of thermoelectric decoupling of the combined heat and power unit can be greatly improved, and the deep peak shaving ability of the combined heat and power unit is also improved. When the present invention uses the second combined heat and power unit to provide an auxiliary decoupling heat load for the heating system, it uses the boiler waste heat, miscellaneous waste heat, extraction steam and intermediate pressure cylinder exhaust steam heat of the second combined heat and power unit, and provides an auxiliary decoupling heat load for the heating system through these heats alone or in any combination of heats, realizing the auxiliary decoupling of adjacent units, improving the flexibility of auxiliary decoupling, and through the combination of auxiliary decoupling and self-decoupling, the thermoelectric decoupling ability of the first combined heat and power unit can be increased, and complete thermoelectric decoupling of the first combined heat and power unit can be achieved as much as possible, and large-range thermoelectric decoupling operation of the combined heat and power unit can be realized. The second thermoelectric decoupling method of the present invention is preferably a method of combining providing an auxiliary decoupling heat load for the heating system through the second combined heat and power unit with providing a self-decoupling heat load for the heating system through the self-decoupling heat of the first combined heat and power unit. Considering that the heat of the second combined heat and power unit may not have excess heat output due to participating in the thermoelectric decoupling of its own unit and thus cannot provide an auxiliary decoupling heat load for the heating system, the second thermoelectric decoupling method is also provided as a method of combining providing a supplementary decoupling heat load for the heating system through an external device with providing a self-decoupling heat load for the heating system through the self-decoupling heat of the first combined heat and power unit, so as to meet the thermoelectric decoupling requirements of the first combined heat and power unit. The present invention can also heat the heating system through the first combined heat and power unit, the second combined heat and power unit and the external device at the same time, so as to realize the deep thermoelectric decoupling of the combined heat and power unit. The advantages of the additional aspects of the present invention will be partially given in the following description, partially become obvious from the following description, or be understood through the practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] The specification drawings forming a part of the present application are used to provide a further understanding of the present application. The schematic embodiments of the present application and their descriptions are used to explain the present application and do not constitute an improper limitation of the present application.

[0016] Figure 1 Schematic diagram of the thermal-electric decoupling and self-decoupling system of the extraction steam heating combined heat and power unit in Embodiment 1 of the present invention;

[0017] Figure 2 Schematic diagram of the deep self-decoupling system of the thermal-electric decoupling of the extraction steam heating combined heat and power unit in Embodiment 1 of the present invention;

[0018] Figure 3 Schematic diagram of the combined system of thermal-electric decoupling, self-decoupling and auxiliary decoupling of the extraction steam heating combined heat and power unit in Embodiment 1 of the present invention;

[0019] Figure 4 Schematic diagram of the combined system of thermal-electric decoupling, self-decoupling and supplementary decoupling of the extraction steam heating combined heat and power unit in Embodiment 1 of the present invention;

[0020] Figure 5 Schematic diagram of the combined system of thermal-electric decoupling, self-decoupling, auxiliary decoupling and supplementary decoupling of the extraction steam heating combined heat and power unit in Embodiment 1 of the present invention;

[0021] Figure 6 Schematic diagram of the thermal-electric decoupling and self-decoupling system of the high back pressure (back pressure) combined heat and power unit in Embodiment 2 of the present invention;

[0022] Figure 7 Schematic diagram of the deep self-decoupling system of the thermal-electric decoupling of the high back pressure (back pressure) combined heat and power unit in Embodiment 2 of the present invention;

[0023] Figure 8 Schematic diagram of the combined system of thermal-electric decoupling, self-decoupling and auxiliary decoupling of the high back pressure (back pressure) combined heat and power unit in Embodiment 2 of the present invention;

[0024] Figure 9 Schematic diagram of the combined system of thermal-electric decoupling, self-decoupling and supplementary decoupling of the high back pressure (back pressure) combined heat and power unit in Embodiment 2 of the present invention;

[0025] Figure 10 Schematic diagram of the combined system of thermal-electric decoupling, self-decoupling, auxiliary decoupling and supplementary decoupling of the high back pressure (back pressure) combined heat and power unit in Embodiment 2 of the present invention;

[0026] Figure 11 Schematic diagram of the thermal-electric decoupling and self-decoupling system of the low-pressure cylinder zero output combined heat and power unit in Embodiment 3 of the present invention;

[0027] Figure 12 Schematic diagram of the deep self-decoupling system of the thermal-electric decoupling of the low-pressure cylinder zero output combined heat and power unit in Embodiment 3 of the present invention;

[0028] Figure 13 Schematic diagram of the combined system of thermal-electric decoupling, self-decoupling and auxiliary decoupling of the low-pressure cylinder zero output combined heat and power unit in Embodiment 3 of the present invention;

[0029] Figure 14 Schematic diagram of the combined system of thermal-electric decoupling self-decoupling and supplementary decoupling for the low-pressure cylinder zero-output cogeneration unit in Embodiment 3 of the present invention;

[0030] Figure 15 Schematic diagram of the combined system of thermal-electric decoupling self-decoupling, auxiliary decoupling and supplementary decoupling for the low-pressure cylinder zero-output cogeneration unit in Embodiment 3 of the present invention.

[0031] Wherein: 1. Boiler; 2. High-pressure cylinder; 3. Intermediate-pressure cylinder; 4. Low-pressure cylinder; 5. Main steam pipeline; 6. Reheat hot-section steam pipeline; 7. Generator; 8. Back-pressure heating pipeline; 9 - Boiler waste heat; 10. Low-pressure cylinder exhaust steam; 11. Heating system pipeline; 12. Intermediate-low pressure connection pipe; 13. Miscellaneous waste heat; 14. Intermediate pipeline; 15. Reheat steam heating pipeline; 16. Exhaust steam heating pipeline; 17. Main steam and reheat cold-section steam matcher; 18. Reheat hot-section steam and heating steam matcher; 19. Intermediate-pressure cylinder exhaust steam and heating steam matcher; 20. Reheat cold-section steam pipeline; 21. Main steam heating pipeline; 22. Main steam and heating steam matcher; 23. Steam extraction of steam turbine; 24. Reheat hot-section extraction steam of the second cogeneration unit; 25. Reheat cold-section extraction steam of the second cogeneration unit; 26. Regenerative extraction steam of the second cogeneration unit; 27. Intermediate-pressure cylinder exhaust steam of the second cogeneration unit; 28. Thermal energy storage tank; 29. Electric heating boiler; 30. Molten salt thermal energy storage heating system; 31. Main steam desuperheating and pressure-reducing heating system; 32. Bypass heating system; 33. Steam jet ejector variable pressure system. Detailed implementation manners

[0032] The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0033] It should be noted that the following detailed description is exemplary and is intended to provide further explanation of the present application. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the technical field to which the present application belongs.

[0034] Embodiment 1

[0035] In this embodiment, a method for thermal-electric decoupling of a cogeneration unit is disclosed, as Figures 1 - 15 shown, which is applied to a system including a first cogeneration unit, a second cogeneration unit, external equipment and a heating system; the steam turbine of the first cogeneration unit, the self-decoupling heat of the first cogeneration unit, the second cogeneration unit and the external equipment can all provide heat loads for the heating system;

[0036] When the first combined heat and power (CHP) unit undergoes heat and power decoupling, in addition to providing non-decoupled heat load for the heating system through the steam turbine of the first CHP unit, the first heat and power decoupling method is first adopted, that is, the self-decoupled heat of the first CHP unit is used to provide self-decoupled heat load for the heating system;

[0037] When the first heat and power decoupling method does not meet the heat and power decoupling requirements of the first CHP unit, the second heat and power decoupling method is adopted, that is, the self-decoupled heat of the first CHP unit is used to provide self-decoupled heat load for the heating system, and the second CHP unit is used to provide auxiliary decoupled heat load for the heating system, or, the self-decoupled heat of the first CHP unit is used to provide self-decoupled heat load for the heating system, and an external device is used to provide supplementary decoupled heat load for the heating system;

[0038] When the second heat and power decoupling method does not meet the heat and power decoupling requirements of the first CHP unit, the third heat and power decoupling method is adopted, that is, the self-decoupled heat of the first CHP unit is used to provide self-decoupled heat load for the heating system, the second CHP unit is used to provide auxiliary decoupled heat load for the heating system, and an external device is used to provide supplementary decoupled heat load for the heating system.

[0039] Each combined heat and power unit includes a boiler 1 and a steam turbine. Among them, the main steam pipeline 5, the reheater hot section steam pipeline 6 and the reheater cold section steam pipeline 20 are connected between the boiler 1 and the high-pressure cylinder 2 and the intermediate-pressure cylinder 3 of the steam turbine. The intermediate-pressure cylinder 3 and the low-pressure cylinder 4 are connected by an intermediate-low pressure connecting pipe 12. The shafts of the high-pressure cylinder 2, the intermediate-pressure cylinder 3 and the low-pressure cylinder 4 of the steam turbine are connected to the shaft of the generator 7 to output mechanical work and generate electricity for the generator 7. During this process, the heat output by the steam turbine of the first combined heat and power unit is also input into the heating system pipeline 11 as heating heat load to heat the heating system, and the heat output by the steam turbine of the second combined heat and power unit is input into the heating system pipeline corresponding to the second combined heat and power unit as heating heat load.

[0040] The combined heat and power unit can be a extraction steam unit, a backpressure unit, a condensing retrofit unit, a high backpressure retrofit unit or a low-pressure cylinder zero output unit.

[0041] In this embodiment, the heating heat load input into the heating system pipeline 11 is decomposed into a decoupled heat load and a non-decoupled heat load. The non-decoupled heat load is provided by the heat output of the steam turbine of the first cogeneration unit, and this non-decoupled heat load is positively correlated with the power generation load. When the power generation load is large, the non-decoupled heat load is large; when the power generation load is small, the non-decoupled heat load is small. The decoupled heat load is provided by one or any combination of the self-decoupled heat of the first cogeneration unit, the heat output of the second cogeneration unit, and the heat output of additional equipment. Among them, the self-decoupled heat of the first cogeneration unit includes the waste heat of the first cogeneration unit and the available steam heat of the steam turbine of the first cogeneration unit. The waste heat of the first cogeneration unit includes one or a combination of the boiler waste heat and miscellaneous waste heat of the first cogeneration unit. The available steam heat of the steam turbine of the first cogeneration unit includes one or a combination of the main steam heat, reheat steam heat, extraction steam heat from the intermediate pressure cylinder, and extraction steam heat. The heat output of the second cogeneration unit includes one or a combination of the boiler waste heat, miscellaneous waste heat, main steam heat, reheat steam heat, extraction steam heat, and extraction steam heat from the intermediate pressure cylinder of the second cogeneration unit.

[0042] The heat output of the steam turbine in the first cogeneration unit is input into the heating system pipeline through the non-decoupled pipeline to provide the non-decoupled heat load for the heating system.

[0043] The self-decoupled heat of the first cogeneration unit is input into the heating system pipeline through the self-decoupled pipeline to provide the self-decoupled heat load for the heating system. The self-decoupled pipeline includes the boiler waste heat pipeline and the miscellaneous waste heat pipeline. The boiler waste heat 9 of the first cogeneration unit is input into the heating system pipeline 11 through the boiler waste heat pipeline, and the miscellaneous waste heat 13 of the first cogeneration unit is input into the heating system pipeline through the miscellaneous waste heat pipeline.

[0044] The miscellaneous waste heat 13 includes one or a combination of boiler flue gas waste heat, blowdown waste heat, ash and slag waste heat, deaerator exhaust steam waste heat, and valve stem leakage waste heat, and is not limited to the waste heat listed.

[0045] As Figures 1 - 5 shown, when the first cogeneration unit is a steam extraction heating cogeneration unit, the non-decoupled pipeline is the heating system pipeline 11. The steam extraction 23 of the steam turbine of the first cogeneration unit is input into the heating system pipeline through the heating system pipeline 11 to provide the non-decoupled heat load for the heating system. Among them, the steam extraction 23 of the steam turbine can be any stage of steam extraction.

[0046] As Figure 2As shown in the figure, the self-decoupling pipeline further includes a main steam heating pipeline 21 connecting the main steam pipeline 5 of the first combined heat and power unit and the heating system pipeline 11, a reheated steam heating pipeline 15 connecting the reheated hot section steam pipeline 6 of the first combined heat and power unit and the heating system pipeline 11, an intermediate pipeline 14 connecting the main steam pipeline 5 of the first combined heat and power unit and the reheated cold section steam pipeline 20 of the first combined heat and power unit, and an extraction steam heating pipeline 16 connecting the medium and low pressure connecting pipe 12 and the heating system pipeline 11.

[0047] The main steam of the first combined heat and power unit is introduced into the heating system pipeline through the main steam heating pipeline 21, the reheated steam of the first combined heat and power unit is introduced into the heating system pipeline through the reheated steam heating pipeline 15, and the extraction steam from the intermediate pressure cylinder of the first combined heat and power unit is introduced into the heating system pipeline through the extraction steam heating pipeline 16.

[0048] A main steam and heating steam matcher 22 is provided on the main steam heating pipeline 21, and the main steam is desuperheated and depressurized through the main steam and heating steam matcher 22 and then introduced into the heating system pipeline 11.

[0049] A reheated hot section steam and heating steam matcher 18 is provided on the reheated steam heating pipeline 15, and the reheated steam is desuperheated and depressurized through the reheated hot section steam and heating steam matcher 18 and then introduced into the heating system pipeline 11.

[0050] A main steam and reheated cold section steam matcher 17 is provided on the intermediate pipeline 14, and the main steam is desuperheated and depressurized through the main steam and reheated cold section steam matcher 17 and then introduced into the reheated cold section steam pipeline 20. After this part of the steam flows through the boiler reheater, it enters the reheated hot section steam pipeline 6 and is then connected to the heating system pipeline 11 through the main steam and reheated cold section steam matcher 17.

[0051] An intermediate pressure cylinder extraction steam and heating steam matcher 19 is provided on the extraction steam heating pipeline 16, and the intermediate pressure cylinder extraction steam is desuperheated and depressurized through the intermediate pressure cylinder extraction steam and heating steam matcher 19 and then introduced into the heating system pipeline 11.

[0052] The main steam and heating steam matcher 22, the reheated hot section steam and heating steam matcher 18, the main steam and reheated cold section steam matcher 17, and the intermediate pressure cylinder extraction steam and heating steam matcher 19 can all adopt desuperheaters or steam matchers.

[0053] When the main steam heating pipeline 21, the reheated steam heating pipeline 15, the intermediate pipeline 14, and the extraction steam heating pipeline 16 are separately connected or coupled and connected, the main steam, reheated steam, and intermediate pressure cylinder extraction steam of the first combined heat and power unit can be used to supplement heating for the heating system.

[0054] When the self-decoupling pipeline is connected, the first combined heat and power unit realizes self-decoupling.

[0055] In this embodiment, a second combined heat and power unit is also provided. In addition to the steam turbine of the second combined heat and power unit providing the non-decoupled heat load for the second heating system, when the waste heat of the second combined heat and power unit is thermally decoupled, it also provides the self-decoupled heat load for the second heating system. In addition, the second combined heat and power unit also outputs heat into the heating system pipeline 11 to provide the auxiliary decoupled heat load for the heating system.

[0056] The heat output by the second combined heat and power unit includes one or several of the boiler waste heat, miscellaneous waste heat, extraction steam heating, and exhaust steam heating of the second combined heat and power unit.

[0057] The heat output by the second combined heat and power unit is introduced into the heating system pipeline 11 through the auxiliary decoupling pipeline to provide the auxiliary decoupled heat load for the heating system. The extraction steam heating provided by the second combined heat and power unit includes one or several of the extraction steam from the hot reheat section, the extraction steam from the cold reheat section, and the regenerative extraction steam.

[0058] As Figure 3 shown, the auxiliary decoupling pipeline includes a boiler waste heat auxiliary pipeline capable of introducing the boiler waste heat of the second combined heat and power unit into the heating system pipeline 11, a miscellaneous waste heat auxiliary pipeline capable of introducing the miscellaneous waste heat of the second combined heat and power unit into the heating system pipeline 11, an extraction steam heating auxiliary pipeline capable of introducing the extraction steam of the second combined heat and power unit into the heating system pipeline 11, and an exhaust steam heating auxiliary pipeline capable of introducing the exhaust steam 27 from the intermediate pressure cylinder of the second combined heat and power unit into the heating system pipeline 11.

[0059] The extraction steam heating auxiliary pipeline includes a hot reheat section extraction steam heating auxiliary pipeline capable of introducing the extraction steam 24 from the hot reheat section of the second combined heat and power unit into the heating system pipeline, a cold reheat section extraction steam heating auxiliary pipeline capable of introducing the extraction steam 25 from the cold reheat section of the second combined heat and power unit into the heating system pipeline, and a regenerative extraction steam heating auxiliary pipeline capable of introducing the regenerative extraction steam 26 of the second combined heat and power unit into the heating system pipeline.

[0060] When the self-decoupling of the first combined heat and power unit cannot meet the thermal decoupling requirements of the first combined heat and power unit, the auxiliary decoupling pipeline is connected. On the basis of the self-decoupling of the first combined heat and power unit, heat is output from the second combined heat and power unit to the heating system to achieve the auxiliary decoupling of the second combined heat and power unit.

[0061] Among them, the connection of the auxiliary decoupling pipeline means that any one of the boiler waste heat auxiliary pipeline, the miscellaneous waste heat auxiliary pipeline, the hot reheat section extraction steam heating auxiliary pipeline, the cold reheat section extraction steam heating auxiliary pipeline, the regenerative extraction steam heating auxiliary pipeline, and the exhaust steam heating auxiliary pipeline is connected alone or any combination of several pipelines is connected.

[0062] Through the auxiliary decoupling pipeline, the auxiliary decoupling of the second cogeneration unit is realized. In cooperation with the self-decoupling of the first cogeneration unit, the thermoelectric decoupling ability of the cogeneration unit can be improved, and even the complete decoupling of the heat load and the electric load of the cogeneration unit can be achieved.

[0063] In this embodiment, an additional device is also provided to provide supplementary decoupling heat load for the heating system through the additional device.

[0064] The additional device is connected to the heating system pipeline 11 through the supplementary decoupling pipeline, and the heat output by the additional device is introduced into the heating system pipeline through the supplementary decoupling pipeline to provide supplementary decoupling heat load for the heating system.

[0065] Such as Figure 4 shown, the additional device can be one or several of a heat storage tank 28, an electric boiler 29, a molten salt heat storage heating system 30, a main steam desuperheating and pressure-reducing heating system 31, a bypass heating system 32, and a steam injection and ejector variable pressure system 33.

[0066] When it is necessary to supply heat to the heating system, the non-decoupling pipeline is connected, and the heat output by the steam turbine in the first cogeneration unit is used to supply heat to the heating system. When the first cogeneration unit participates in peak shaving, the steam turbine of the first cogeneration unit operates at a low load. At this time, the heat output by the steam turbine decreases, and there may be a problem that the heat supply demand of the heating system cannot be met.

[0067] At this time, in order to achieve the thermoelectric decoupling of the first cogeneration unit, first, the first thermoelectric decoupling method is adopted, that is, the self-decoupled heat of the first cogeneration unit is used to provide self-decoupled heat load for the heating system;

[0068] When the first thermoelectric decoupling method does not meet the thermoelectric decoupling requirements of the first cogeneration unit, the second thermoelectric decoupling method is adopted, that is, the self-decoupled heat of the first cogeneration unit is used to provide self-decoupled heat load for the heating system, combined with the auxiliary decoupled heat load provided by the second cogeneration unit for the heating system, or, the self-decoupled heat of the first cogeneration unit is used to provide self-decoupled heat load for the heating system, combined with the supplementary decoupled heat load provided by the additional device for the heating system;

[0069] When the second thermoelectric decoupling method does not meet the thermoelectric decoupling requirements of the first cogeneration unit, the third thermoelectric decoupling method is adopted, that is, the self-decoupled heat of the first cogeneration unit is used to provide self-decoupled heat load for the heating system, the auxiliary decoupled heat load is provided by the second cogeneration unit for the heating system, and the supplementary decoupled heat load is provided by the additional device for the heating system.

[0070] In addition, when selecting the second method of thermal power-electricity decoupling, it is preferred to adopt a thermal power-electricity decoupling method that combines the self-decoupling heat of the first combined heat and power unit to provide a self-decoupling heat load for the heating system and the second combined heat and power unit to provide an auxiliary decoupling heat load for the heating system. When the second combined heat and power unit cannot output additional heat to the heating system to meet its own thermal power-electricity decoupling requirements, then select a thermal power-electricity decoupling method that combines the self-decoupling heat of the first combined heat and power unit to provide a self-decoupling heat load for the heating system and an additional device to provide a supplementary decoupling heat load for the heating system, so as to ensure that on the basis of realizing the thermal power-electricity decoupling of the first combined heat and power unit, the thermal power-electricity decoupling of the second combined heat and power unit is not affected.

[0071] In this embodiment, through the self-decoupling heat of the first combined heat and power unit, the second combined heat and power unit and additional devices, different thermal power-electricity decoupling methods are provided for the thermal power-electricity decoupling of the first combined heat and power unit, and the priorities of different thermal power-electricity decoupling methods are defined, reducing resource waste while ensuring that the thermal power-electricity decoupling requirements of the first combined heat and power unit are met.

[0072] The method proposed in this embodiment, which operates with the self-decoupling of the unit as the main decoupling method, the adjacent unit provides auxiliary decoupling operation, and the additional device completes the supplementary decoupling operation, can realize the large-scale thermal power-electricity decoupling operation of the combined heat and power unit. This thermal power-electricity decoupling method, with self-decoupling as the main method, can greatly improve the flexibility of the combined heat and power unit with relatively small investment.

[0073] The combined heat and power unit described in this embodiment can be either a combined heat and power unit originally designed for heating or a combined heat and power unit originally designed as a condensing unit and later transformed for heating.

[0074] Embodiment 2

[0075] In this embodiment, a method for thermal power-electricity decoupling of a combined heat and power unit is disclosed. As Figures 6 - 10 shown, the combined heat and power unit is a backpressure unit. Therefore, in this embodiment, the steam turbine of the first combined heat and power unit provides a non-decoupled heat load for the heating system through the exhaust steam of the low-pressure cylinder. The corresponding non-decoupled pipeline is the backpressure heating pipeline 8 that can introduce the exhaust steam of the low-pressure cylinder of the first combined heat and power unit into the heating system pipeline. The backpressure heating pipeline 8 introduces the exhaust steam of the low-pressure cylinder of the first combined heat and power unit into the heating system pipeline 11 to provide a non-decoupled heat load for the heating system.

[0076] Except that the combined heat and power unit in this embodiment is a backpressure unit and the non-decoupled pipeline is the backpressure heating pipeline 8, the rest of the structure and method are the same as those in Embodiment 1.

[0077] Embodiment 3

[0078] In this embodiment, a method for thermal power-electricity decoupling of a combined heat and power unit is disclosed. AsFigures 11 - 15 As shown, the combined heat and power unit is a unit with zero output of the low-pressure cylinder. Therefore, in this embodiment, the steam turbine of the first combined heat and power unit provides a non-decoupled heat load for the heating system through the extraction steam of the intermediate-pressure cylinder. The non-decoupled pipeline is the extraction steam heating pipeline 16 that leads the extraction steam of the intermediate-pressure cylinder of the first combined heat and power unit into the heating system pipeline. The extraction steam heating pipeline 16 leads the extraction steam of the intermediate-pressure cylinder of the first combined heat and power unit into the heating system pipeline 11 to provide a non-decoupled heat load for the heating system.

[0079] At this time, the self-decoupled pipeline includes the boiler waste heat pipeline, miscellaneous waste heat pipeline, the main steam heating pipeline 21 connecting the main steam pipeline 5 of the first combined heat and power unit and the heating system pipeline 11, the reheated steam heating pipeline 15 connecting the reheated hot section steam pipeline 6 of the first combined heat and power unit and the heating system pipeline 11, and the intermediate pipeline 14 connecting the main steam pipeline 5 of the first combined heat and power unit and the reheated cold section steam pipeline 20 of the first combined heat and power unit.

[0080] Except that the combined heat and power unit in this embodiment is a unit with zero output of the low-pressure cylinder, the non-decoupled pipeline is the extraction steam heating pipeline 16, and its own auxiliary heating pipeline does not include the extraction steam heating pipeline 16, the rest of the structure and method are the same as those in Embodiment 1.

[0081] Embodiment 4

[0082] In this embodiment, a heat decoupling system of a combined heat and power unit is disclosed, which includes a first combined heat and power unit, a second combined heat and power unit, an external device, and a heating system. The steam turbine of the first combined heat and power unit, the self-decoupled heat of the first combined heat and power unit, the second combined heat and power unit, and the external device can all provide heat loads for the heating system;

[0083] When the first combined heat and power unit is heat decoupled, the first combined heat and power unit, the second combined heat and power unit, and the external device adopt the heat decoupling method of a heat decoupling system of a combined heat and power unit disclosed in Embodiment 1 or 2 or 3.

[0084] Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit them. Although the present invention has been described in detail with reference to the above embodiments, those of ordinary skill in the art should understand that: the specific implementation manners of the present invention can still be modified or equivalently replaced, and any modification or equivalent replacement without departing from the spirit and scope of the present invention shall be covered by the protection scope of the claims of the present invention.

Claims

1. A method for thermoelectric decoupling of a combined heat and power unit, characterized in that, Applied to a system including a first combined heat and power unit, a second combined heat and power unit, additional equipment, and a heating system; the steam turbine of the first combined heat and power unit, the self-decoupled heat of the first combined heat and power unit, the second combined heat and power unit, and the additional equipment can all provide heat loads for the heating system; When the first combined heat and power unit performs heat and power decoupling, first adopt the first heat and power decoupling method, that is, provide the self-decoupled heat load for the heating system through the self-decoupled heat of the first combined heat and power unit; The self-decoupled heat of the first combined heat and power unit includes the waste heat of the first combined heat and power unit and the available steam heat of the steam turbine of the first combined heat and power unit; The waste heat of the first combined heat and power unit includes one or several of the boiler waste heat and miscellaneous waste heat of the first combined heat and power unit; The available steam heat of the steam turbine of the first combined heat and power unit includes one or several of the main steam heat, reheated steam heat, extraction steam heat, and extraction steam heat from the intermediate pressure cylinder exhaust of the steam turbine of the first combined heat and power unit; When the first heat and power decoupling method does not meet the heat and power decoupling requirements of the first combined heat and power unit, adopt the second heat and power decoupling method, that is, provide the self-decoupled heat load for the heating system through the self-decoupled heat of the first combined heat and power unit, and provide the auxiliary decoupled heat load for the heating system through the second combined heat and power unit, or, provide the self-decoupled heat load for the heating system through the self-decoupled heat of the first combined heat and power unit, and provide the supplementary decoupled heat load for the heating system through the additional equipment; When the second heat and power decoupling method does not meet the heat and power decoupling requirements of the first combined heat and power unit, adopt the third heat and power decoupling method, that is, provide the self-decoupled heat load for the heating system through the self-decoupled heat of the first combined heat and power unit, provide the auxiliary decoupled heat load for the heating system through the second combined heat and power unit, and provide the supplementary decoupled heat load for the heating system through the additional equipment.

2. The thermoelectric decoupling system of a combined heat and power unit according to claim 1, wherein When adopting the second heat and power decoupling method, preferably adopt the heat and power decoupling method of providing the self-decoupled heat load for the heating system through the self-decoupled heat of the first combined heat and power unit, and providing the auxiliary decoupled heat load for the heating system through the second combined heat and power unit.

3. The thermoelectric decoupling system of a cogeneration unit according to claim 1, characterized in that, Miscellaneous waste heat includes one or several of boiler flue gas waste heat, blowdown waste heat, ash and slag waste heat, deaerator exhaust waste heat, and valve stem leakage waste heat.

4. The thermoelectric decoupling system of a cogeneration unit according to claim 1, characterized in that When the first combined heat and power unit performs heat and power decoupling, provide the non-decoupled heat load for the heating system through the steam turbine of the first combined heat and power unit.

5. The thermoelectric decoupling system of a combined heat and power unit according to claim 4, characterized in that The steam turbine of the first combined heat and power unit provides the non-decoupled heat load for the heating system through the extraction steam from the intermediate pressure cylinder, the exhaust steam from the low pressure cylinder, or the extraction steam from the intermediate pressure cylinder exhaust.

6. The thermoelectric decoupling system of a cogeneration unit according to claim 1, characterized in that, The auxiliary decoupled load provided by the second combined heat and power unit includes one or several of the boiler waste heat, miscellaneous waste heat, extraction steam heating, and exhaust steam heating of the second combined heat and power unit.

7. The thermoelectric decoupling system of a combined heat and power unit according to claim 1, characterized in that, The extraction steam heating provided by the second combined heat and power unit includes one or several of the extraction steam from the hot reheat section, the extraction steam from the cold reheat section, and the regenerative extraction steam.

8. The thermoelectric decoupling system of a cogeneration unit according to claim 1, characterized in that, The additional equipment is one or several of a heat storage tank, an electric boiler, a molten salt heat storage heating system, a main steam desuperheating and pressure reducing heating system, a bypass heating system, and a steam jet ejector variable pressure system.

9. A thermoelectric decoupling system for a combined heat and power unit, characterized in that, It includes a first cogeneration unit, a second cogeneration unit, additional equipment and a heating system. The steam turbine of the first cogeneration unit, the self-decoupled heat of the first cogeneration unit, the second cogeneration unit and the additional equipment can all provide heat load for the heating system; When the heat and power of the first cogeneration unit are decoupled, the first cogeneration unit, the second cogeneration unit and the additional equipment adopt the heat and power decoupling method of a heat and power decoupling system of a cogeneration unit described in any one of claims 1-8.

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