Novel combined cycle generator set and method of operating the same

Abstract

The application provides a novel combined cycle generating unit and an operation method thereof. The novel combined cycle generating unit comprises: a gas turbine generating unit for burning to generate high-temperature flue gas and generating electricity by using the high-temperature flue gas; a waste heat boiler for receiving the high-temperature flue gas and generating steam by using the high-temperature flue gas; a steam turbine generating unit comprising a steam turbine, a condenser, a condensate pump and a multi-stage high-pressure heater, the steam turbine being used for receiving the steam and generating electricity by expanding the steam, the condenser being used for cooling the steam to generate condensate, the condensate pump being used for conveying the condensate to the waste heat boiler, and the multi-stage high-pressure heater being used for extracting steam from different stages of the steam turbine and heating the condensate in stages; and an organic Rankine cycle unit for converting low-temperature waste heat of the waste heat boiler into electric energy. The unit can reduce the cold-end loss of the steam turbine and reduce the flue gas emission temperature of the waste heat boiler, thereby improving the overall efficiency of the combined cycle unit.

Description

Technical Field

[0001] This application relates to the field of thermoelectric technology, and more specifically, to a novel combined cycle generator set and its operation method. Background Technology

[0002] Traditional combined cycle generator sets typically consist of a gas turbine, a waste heat boiler, and a steam turbine to improve energy efficiency. However, existing technologies present a contradiction between steam extraction and flue gas temperature. Specifically, conventional systems typically employ a turbine design without steam extraction to avoid increasing the flue gas temperature of the waste heat boiler. However, this leads to increased cold-end losses, affecting overall efficiency. On the other hand, while using an extraction-type steam turbine can reduce cold-end losses, the steam extraction causes the flue gas temperature of the waste heat boiler to rise, which in turn reduces the unit's efficiency. Summary of the Invention

[0003] This application provides at least one novel combined cycle generator set and its operation method. By introducing a turbine cold-end waste heat utilization mechanism and an organic Rankine cycle (ORC), the unit can reduce the turbine cold-end losses while lowering the exhaust temperature of the waste heat boiler, thereby improving the overall efficiency of the combined cycle unit.

[0004] In a first aspect, embodiments of this application provide a novel combined cycle generator set, comprising: Gas turbine generator sets are used to generate high-temperature flue gas through combustion and to generate electricity using the high-temperature flue gas. A waste heat boiler is used to receive the high-temperature flue gas and use the high-temperature flue gas to generate steam. A steam turbine generator set is used to receive the steam and generate electricity using the steam. The steam turbine generator set includes a steam turbine, a condenser, a condensate pump, and a multi-stage high-pressure heater. The steam turbine is used to receive the steam and generate electricity by expanding the steam. The condenser is used to cool the exhaust steam discharged after the steam has done work into condensate. The condensate pump is used to transport the condensate to the waste heat boiler. The multi-stage high-pressure heater is used to extract steam from different stages of the steam turbine and heat the condensate in stages. Organic Rankine cycle units are used to convert the low-temperature waste heat from the waste heat boiler into electrical energy.

[0005] In one optional embodiment, the steam turbine includes a low-pressure section, a medium-pressure section, and a high-pressure section; The multi-stage high-pressure heater includes a first high-pressure heater, a second high-pressure heater, and a third high-pressure heater. The gas path of the first high-pressure heater is connected to the low-pressure section and the condenser at both ends, the gas path of the second high-pressure heater is connected to the medium-pressure section and the condenser at both ends, and the gas path of the third high-pressure heater is connected to the high-pressure section and the condenser at both ends.

[0006] In one optional embodiment, an electric door is provided between the gas inlet of the first high-pressure heater and the low-pressure section, between the gas inlet of the second high-pressure heater and the medium-pressure section, and between the gas inlet of the third high-pressure heater and the high-pressure section.

[0007] In one optional embodiment, a check valve is provided between the gas inlet of the first high-pressure heater and the low-pressure section, between the gas inlet of the second high-pressure heater and the medium-pressure section, and between the gas inlet of the third high-pressure heater and the high-pressure section.

[0008] In one optional embodiment, the gas inlet of the first high-pressure heater is connected to the gas outlet of the second high-pressure heater, and the gas inlet of the second high-pressure heater is connected to the gas outlet of the third high-pressure heater.

[0009] In one optional embodiment, a condensate regulating valve is provided between the gas outlet of the first high-pressure heater and the condenser, between the gas inlet of the first high-pressure heater and the gas outlet of the second high-pressure heater, and between the gas inlet of the second high-pressure heater and the gas outlet of the third high-pressure heater.

[0010] In one alternative embodiment, a shaft seal heater is provided between the water inlet of the first high-pressure heater and the condenser.

[0011] In one alternative embodiment, the waste heat boiler is equipped with an evaporator that uses the low-temperature waste heat from the waste heat boiler to heat a low-boiling-point organic working fluid. The organic Rankine cycle unit includes an ORC turbine, an ORC condenser, an ORC booster pump, and an ORC cycle generator. The ORC turbine is connected to the ORC cycle generator. The ORC turbine, the ORC condenser, and the ORC booster pump are connected in series to form a loop, and the low-boiling-point organic working fluid circulates in the loop.

[0012] Secondly, this application also provides a novel operating method for a combined cycle generator set, applicable to the novel combined cycle generator set described above. The method includes: during operation, the condenser cools the exhaust steam generated by the steam doing work into condensate, the condensate pump transports the condensate to the waste heat boiler, the multi-stage high-pressure heater extracts steam from different stages of the turbine, and the condensate passes through the multi-stage high-pressure heater sequentially during transport for staged heating, with the drained water flowing back to the condenser; simultaneously, the organic Rankine cycle unit converts the low-temperature waste heat of the waste heat boiler into electrical energy.

[0013] The above-mentioned technical solution of this application has the following beneficial technical effects: The novel combined cycle generator set of this application, by introducing a turbine cold-end waste heat utilization mechanism and an organic Rankine cycle (ORC), can reduce turbine cold-end losses while lowering the flue gas temperature of the waste heat boiler, thereby improving the overall efficiency of the combined cycle unit.

[0014] To make the above-mentioned objectives, features and advantages of this application more apparent and understandable, preferred embodiments are described below in detail with reference to the accompanying drawings. Attached Figure Description

[0015] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments will be briefly described below. These drawings are incorporated in and constitute a part of this specification. They illustrate embodiments conforming to this application and, together with the specification, serve to explain the technical solutions of this application. It should be understood that the following drawings only show some embodiments of this application and should not be considered as limiting the scope. For those skilled in the art, other related drawings can be obtained from these drawings without creative effort.

[0016] Figure 1 A schematic diagram of a novel combined cycle generator set provided in an embodiment of this application is shown; In the diagram: 1. Compressor; 2. Combustion chamber; 3. Turbine; 4. First generator; 5. Waste heat boiler; 6. Steam turbine; 7. Second generator; 8. Condenser; 9. Condensate pump; 10. First high-pressure heater; 11. Second high-pressure heater; 12. Third high-pressure heater; 13. First electric valve; 14. Second electric valve; 15. Third electric valve; 16. First non-return valve; 17. Second non-return valve; 18. Third non-return valve; 19. First drain regulating valve; 20. Second drain regulating valve; 21. Third drain regulating valve; 22. Shaft seal heater; 23. ORC turbine; 24. ORC condenser; 25. ORC booster pump; 26. ORC cycle generator. Detailed Implementation

[0017] Various exemplary embodiments of the present 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 the present application.

[0018] 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.

[0019] 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.

[0020] 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.

[0021] 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.

[0022] refer to Figure 1This application provides a novel combined cycle generator set, comprising: a gas turbine generator set, a waste heat boiler 5, a steam turbine generator set 6, and an organic Rankine cycle unit. The gas turbine generator set is used to generate high-temperature flue gas through combustion and to generate electricity using the high-temperature flue gas. The waste heat boiler 5 is used to receive the high-temperature flue gas and to generate steam using the high-temperature flue gas. The steam turbine generator set 6 is used to receive the steam and to generate electricity using the steam. The steam turbine generator set 6 includes a steam turbine 6, a condenser 8, a condensate pump 9, and a multi-stage high-pressure heater. The steam turbine 6 is used to receive steam and to generate electricity using the expansion of the steam. The condenser 8 is used to cool the exhaust steam discharged after the steam has done work into condensate. The condensate pump is used to transport the condensate to the waste heat boiler 5. The multi-stage high-pressure heater is used to extract steam from different stages of the steam turbine 6 and to heat the condensate in stages. The organic Rankine cycle unit is used to convert the low-temperature waste heat from the waste heat boiler 5 into electrical energy.

[0023] A gas turbine generator set includes a compressor 1, a combustion chamber 2, a turbine 3, and a first generator 4. The main task of the compressor 1 is to draw in outside air, compress it to a high-pressure state, and then send it into the combustion chamber 2. The combustion chamber 2 injects fuel into the high-pressure air and ignites it, producing high-temperature, high-pressure gas. The turbine 3 utilizes the energy of the high-temperature, high-pressure gas produced in the combustion chamber 2, converting it into mechanical energy. The generator converts the mechanical energy provided by the turbine 3 into electrical energy.

[0024] Waste heat boiler 5 includes a condensate heater, a low-pressure economizer, a high-pressure economizer, a low-pressure superheater, a high-pressure evaporator, and two high-pressure superheaters. The condensate heater preheats the low-temperature condensate from the turbine 6 condenser. The low-pressure economizer further heats the condensate, bringing it close to saturation temperature but not yet to boiling. The high-pressure economizer preheats the high-pressure feedwater from the feedwater pump to near saturation temperature. The low-pressure superheater superheats the low-pressure steam to increase its dryness and work capacity. The high-pressure evaporator heats the high-pressure feedwater to boiling, generating saturated steam. The high-pressure superheater further superheats the high-pressure saturated steam to increase its dryness and enhance its work capacity. Waste heat boiler 5 and steam turbine 6 are connected via high-pressure main steam pipeline and low-pressure main steam pipeline. The high-pressure main steam pipeline delivers the final high-pressure saturated steam to the high-pressure section of steam turbine 6, while the low-pressure main steam pipeline delivers the low-pressure steam generated by the low-pressure superheater to the low-pressure section of steam turbine 6. Additionally, waste heat boiler 5 is equipped with an evaporator that utilizes the low-temperature waste heat from waste heat boiler 5 to heat a low-boiling-point organic working fluid (such as ammonia).

[0025] The turbine 6 generator set includes a low-pressure section, an intermediate-pressure section, and a high-pressure section. The low-pressure section receives low-temperature, low-pressure steam from the waste heat boiler 5. For example, the low-pressure section is connected to the low-pressure superheater of the waste heat boiler 5 via a low-pressure main steam pipeline, receiving the low-temperature, low-pressure steam generated by the superheater. Its temperature range is typically between 100°C and 200°C, and its pressure range is typically between 0.01 MPa and 1 MPa. The high-pressure section receives high-temperature, high-pressure steam from the waste heat boiler 5. For example, the high-pressure section is connected to the high-pressure superheater of the waste heat boiler 5 via a high-pressure main steam pipeline, receiving the high-pressure saturated steam ultimately generated by the waste heat boiler 5. Its temperature range is typically between 500°C and 600°C, and its pressure range is typically between 10 MPa and 25 MPa. The intermediate-pressure section receives steam that has undergone expansion and work in the high-pressure section. The steam pressure and temperature have decreased, with a temperature range typically between 300°C and 400°C and a pressure range typically between 1 MPa and 10 MPa. It should be noted that the turbine 6 generator set also includes a second generator 7, the function of which is to convert the mechanical energy provided by the turbine 6 into electrical energy.

[0026] The Organic Rankine Cycle (ORC) unit includes an ORC turbine 23, an ORC condenser 24, an ORC booster pump 25, and an ORC cycle generator 26. The ORC turbine 23 is connected to the ORC cycle generator 26. The ORC turbine 23, ORC condenser 24, and ORC booster pump 25 are connected in series to form a loop, in which the low-boiling-point organic working fluid circulates. During operation, the evaporator of the waste heat boiler 5 uses the low-temperature waste heat of the waste heat boiler 5 to heat the low-boiling-point organic working fluid, converting it into a gaseous state. The gaseous working fluid expands at the ORC turbine 23, doing work and driving the ORC cycle generator 26 to generate electricity. After the exhaust gas is discharged from the ORC turbine 23, it enters the ORC condenser 24, is cooled into a liquid state, and is then pressurized by the ORC booster pump 25 and sent back to the evaporator for heating, completing the cycle.

[0027] During operation, the gas turbine generator set burns gas to generate electricity. Simultaneously, the high-temperature flue gas enters the waste heat boiler 5, which uses the high-temperature flue gas to generate steam and then sends the steam to the turbine 6. The turbine 6 generator set uses the steam to generate electricity. In this process, the condenser 8 cools the exhaust steam generated by the steam to condensate. The condensate pump sends the condensate to the waste heat boiler 5. The multi-stage high-pressure heater draws steam from different stages of the turbine 6. During the transport process, the condensate passes through the multi-stage high-pressure heater for staged heating, and the drained water flows back to the condenser 8. At the same time, the organic Rankine cycle unit converts the low-temperature waste heat of the waste heat boiler 5 into electrical energy.

[0028] The novel combined cycle generator set of this application, by introducing a waste heat utilization mechanism at the cold end of the turbine 6 and an organic Rankine cycle (ORC), can reduce the exhaust temperature of the waste heat boiler 5 while reducing the cold end loss of the turbine 6, thereby improving the overall efficiency of the combined cycle unit.

[0029] In some embodiments, the multi-stage high-pressure heater includes a first high-pressure heater 10, a second high-pressure heater 11, and a third high-pressure heater 12. The gas path of the first high-pressure heater 10 is connected to the low-pressure section and the condenser 8 at both ends, the gas path of the second high-pressure heater 11 is connected to the intermediate-pressure section and the condenser 8 at both ends, and the gas path of the third high-pressure heater 12 is connected to the high-pressure section and the condenser 8 at both ends. That is, there can be three high-pressure heaters. When condensate passes through, the first high-pressure heater 10, the second high-pressure heater 11, and the third high-pressure heater 12 can heat the condensate in stages. Specifically, steam discharged from the low-pressure section passes through the gas path of the first high-pressure heater 10 to heat the condensate passing through the water path of the first high-pressure heater 10 for the first time. Steam discharged from the intermediate-pressure section passes through the gas path of the second high-pressure heater 11 to heat the condensate passing through the water path of the second high-pressure heater 11 for the second time. Steam discharged from the high-pressure section passes through the gas path of the third high-pressure heater 12 to heat the condensate passing through the water path of the third high-pressure heater 12 for the third time. It should be understood that the steam after heat exchange will return to condenser 8.

[0030] In some embodiments, electric valves are provided between the gas inlet and the low-pressure section of the first high-pressure heater 10, between the gas inlet and the intermediate-pressure section of the second high-pressure heater 11, and between the gas inlet and the high-pressure section of the third high-pressure heater 12. Specifically, a first electric valve 13 is provided between the gas inlet and the low-pressure section of the first high-pressure heater 10, and opening the first electric valve 13 allows steam from the low-pressure section to be delivered to the first high-pressure heater 10. A second electric valve 14 is provided between the gas inlet and the intermediate-pressure section of the second high-pressure heater 11, and opening the second electric valve 14 allows steam from the intermediate-pressure section to be delivered to the second high-pressure heater 11. A third electric valve 15 is provided between the gas inlet and the low-pressure section of the third high-pressure heater 12, and opening the third electric valve 15 allows steam from the high-pressure section to be delivered to the third high-pressure heater 12. Of course, each electric valve can also be used to control the exhaust volume of the corresponding stage to balance cold end losses and flue gas temperature.

[0031] In some embodiments, check valves are provided between the gas inlet and the low-pressure section of the first high-pressure heater 10, between the gas inlet and the intermediate-pressure section of the second high-pressure heater 11, and between the gas inlet and the high-pressure section of the third high-pressure heater 12. Specifically, a first check valve 16 is provided between the gas inlet and the low-pressure section of the first high-pressure heater 10, which prevents steam from flowing back to the low-pressure section. A second check valve 17 is provided between the gas inlet and the intermediate-pressure section of the second high-pressure heater 11, which prevents steam from flowing back to the intermediate-pressure section. A first check valve 16 is provided between the gas inlet and the high-pressure section of the third high-pressure heater 12, which prevents steam from flowing back to the low-pressure section.

[0032] In some embodiments, the gas inlet of the first high-pressure heater 10 is connected to the gas outlet of the second high-pressure heater 11, and the gas inlet of the second high-pressure heater 11 is connected to the gas outlet of the third high-pressure heater 12. That is, the first high-pressure heater 10, the second high-pressure heater 11, and the third high-pressure heater 12 can be connected through their respective gas paths. In operation, the low-pressure steam returns directly to the condenser 8 after the first heating of the condensate. The medium-pressure steam, after the second heating of the condensate, first passes through the gas path of the first high-pressure heater 10 and then returns to the condenser 8. The high-pressure steam, after the third heating of the condensate, first passes through the gas path of the second high-pressure heater 11, then through the gas path of the first high-pressure heater 10, and finally returns to the condenser 8.

[0033] In some embodiments, drain regulating valves are provided between the gas outlet of the first high-pressure heater 10 and the condenser 8, between the gas inlet of the first high-pressure heater 10 and the gas outlet of the second high-pressure heater 11, and between the gas inlet of the second high-pressure heater 11 and the gas outlet of the third high-pressure heater 12. Each drain regulating valve can not only return condensate to the condenser 8 but also regulate the condensate flow rate. Specifically, a first drain regulating valve 19 is provided between the gas outlet of the first high-pressure heater 10 and the condenser 8, which can regulate the condensate flow rate to control the water level of the first high-pressure heater 10 within a certain range. A second drain regulating valve 20 is provided between the gas inlet of the first high-pressure heater 10 and the gas outlet of the second high-pressure heater 11, which can regulate the condensate flow rate to control the water level of the second high-pressure heater 11 within a certain range. A third drain regulating valve 21 is provided between the gas inlet of the second high-pressure heater 11 and the gas outlet of the third high-pressure heater 12. The third drain regulating valve 21 can adjust the drain flow rate to control the water level of the third high-pressure heater 12 within a certain range.

[0034] In some embodiments, a shaft seal heater 22 is provided between the water inlet of the first high-pressure heater 10 and the condenser 8. In practical use, the shaft seal heater 22 can be used to recover steam heat leaked from the shaft seal of the turbine 6.

[0035] One or more embodiments in this specification are intended to cover all such substitutions, modifications, and variations that fall within the broad scope of the appended claims. Therefore, any omissions, modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of one or more embodiments in this specification should be included within the protection scope of this application.

[0036] The above are merely specific embodiments of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A novel combined cycle generator set, characterized in that, include: Gas turbine generator sets are used to generate high-temperature flue gas through combustion and to generate electricity using the high-temperature flue gas. A waste heat boiler is used to receive the high-temperature flue gas and use the high-temperature flue gas to generate steam. A steam turbine generator set is used to receive the steam and generate electricity using the steam. The steam turbine generator set includes a steam turbine, a condenser, a condensate pump, and a multi-stage high-pressure heater. The steam turbine is used to receive the steam and generate electricity by expanding the steam. The condenser is used to cool the exhaust steam discharged after the steam has done work into condensate. The condensate pump is used to transport the condensate to the waste heat boiler. The multi-stage high-pressure heater is used to extract steam from different stages of the steam turbine and heat the condensate in stages. Organic Rankine cycle units are used to convert the low-temperature waste heat from the waste heat boiler into electrical energy.

2. The novel combined cycle generator set according to claim 1, characterized in that, The steam turbine includes a low-pressure section, a medium-pressure section, and a high-pressure section; The multi-stage high-pressure heater includes a first high-pressure heater, a second high-pressure heater, and a third high-pressure heater. The gas path of the first high-pressure heater is connected to the low-pressure section and the condenser at both ends, the gas path of the second high-pressure heater is connected to the medium-pressure section and the condenser at both ends, and the gas path of the third high-pressure heater is connected to the high-pressure section and the condenser at both ends.

3. The novel combined cycle generator set according to claim 2, characterized in that, Electric gates are provided between the gas inlet of the first high-pressure heater and the low-pressure section, between the gas inlet of the second high-pressure heater and the medium-pressure section, and between the gas inlet of the third high-pressure heater and the high-pressure section.

4. The novel combined cycle generator set according to claim 3, characterized in that, Check valves are provided between the gas inlet of the first high-pressure heater and the low-pressure section, between the gas inlet of the second high-pressure heater and the medium-pressure section, and between the gas inlet of the third high-pressure heater and the high-pressure section.

5. The novel combined cycle generator set according to claim 2, characterized in that, The gas inlet of the first high-pressure heater is connected to the gas outlet of the second high-pressure heater, and the gas inlet of the second high-pressure heater is connected to the gas outlet of the third high-pressure heater.

6. The novel combined cycle generator set according to claim 5, characterized in that, A drain regulating valve is provided between the gas outlet of the first high-pressure heater and the condenser, between the gas inlet of the first high-pressure heater and the gas outlet of the second high-pressure heater, and between the gas inlet of the second high-pressure heater and the gas outlet of the third high-pressure heater.

7. The novel combined cycle generator set according to claim 2, characterized in that, A shaft seal heater is provided between the water inlet of the first high-pressure heater and the condenser.

8. The novel combined cycle generator set according to claim 1, characterized in that, The waste heat boiler is equipped with an evaporator, which uses the low-temperature waste heat of the waste heat boiler to heat a low-boiling-point organic working fluid. The organic Rankine cycle unit includes an ORC turbine, an ORC condenser, an ORC booster pump, and an ORC cycle generator. The ORC turbine is connected to the ORC cycle generator. The ORC turbine, the ORC condenser, and the ORC booster pump are connected in series to form a loop, and the low-boiling-point organic working fluid circulates in the loop.

9. A novel operating method for a combined cycle generator set, applicable to the novel combined cycle generator set according to any one of claims 1-8, characterized in that, The method includes: during operation, the condenser cools the exhaust steam generated by the steam to condensate, the condensate pump transports the condensate to the waste heat boiler, the multi-stage high-pressure heater draws steam from different stages of the turbine, the condensate passes through the multi-stage high-pressure heater sequentially during transport for staged heating, and the drained water flows back to the condenser; simultaneously, the organic Rankine cycle unit converts the low-temperature waste heat of the waste heat boiler into electrical energy.

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