Combined cycle power plant having supercritical steam turbine
10316700 · 2019-06-11
Assignee
Inventors
Cpc classification
F01K23/101
MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
F01K7/32
MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
F01K7/22
MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
F01K23/106
MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
Y02E20/16
GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
F01K3/26
MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
F01K23/10
MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
International classification
F01K3/26
MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
F01K23/10
MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
F01K7/32
MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
F01K7/22
MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
Abstract
A combine cycle power plant is presented. The combine cycle power plant includes a gas turbine, a heat recovery steam generator, a main steam turbine and a supercritical steam turbine. The supercritical steam turbine may be operated as a separate steam turbine that may be not a single steam turboset with the main steam turbine. The supercritical steam turbine receives supercritical steam generated in the heat recovery steam generator to produce power output. Exiting steam from the supercritical steam turbine may be routed to the main steam turbine. The supercritical steam turbine may be operated at a rotational speed that is higher than a grid frequency. The rotational speed of the supercritical steam turbine may be reduced to the grid frequency via a gearbox.
Claims
1. A combined cycle power plant comprising: a gas turbine that is configured to generate power output; a heat recovery steam generator located downstream of the gas turbine that is configured to receive exhaust gas from the gas turbines and produce steam by extracting energy from the exhaust gas; a main steam turbine that is configured to generate power output; and a supercritical steam turbine that is configured to generate power output, wherein the heat recovery steam generator comprises multiple pressure steam systems comprising a low pressure steam system, an intermediate pressure steam system, and a high pressure steam system, wherein the low pressure steam system is configured to generate low pressure steam, wherein the intermediate pressure steam system is configured to generate intermediate pressure steam, wherein the high pressure steam system is configured to generate supercritical steam, wherein the supercritical steam is transferred to the supercritical steam turbine, wherein the supercritical steam turbine is configured to expand the supercritical steam to generate power output and produce exiting steam, wherein the main steam turbine is configured to generate power output from the exiting steam from the supercritical steam turbine, the intermediate pressure steam generated in the heat recovery steam generator, and the low pressure steam generated in the heat recovery steam generator, and wherein the high pressure steam system is configured to further generate subcritical high pressure steam, wherein the subcritical high pressure steam is mixed with the exiting steam from the supercritical steam turbine to generate high pressure steam mixture, and wherein the high pressure steam mixture is transferred to the main steam turbine.
2. The combined cycle power plant as claimed in claim 1, wherein the supercritical steam turbine is configured to be operated at a rotational speed that is higher than a grid frequency.
3. The combined cycle power plant as claimed in claim 2, further comprising a gearbox connected to the supercritical steam turbine, wherein the gearbox is configured to reduce the rotational speed of the supercritical steam turbine to the grid frequency.
4. The combined cycle power plant as claimed in claim 3, further comprising a supercritical steam turbine generator, wherein the supercritical steam turbine is connected to the supercritical steam turbine generator via the gearbox after reducing the rotational speed to the grid frequency.
5. The combined cycle power plant as claimed in claim 3, wherein the supercritical steam turbine is connected to the main steam turbine via the gearbox after reducing the rotational speed to the grid frequency.
6. The combined cycle power plant as claimed in claim 1, wherein the exiting steam from the supercritical steam turbine is reheated in the heat recovery steam generator prior to be transferred to the main steam turbine.
7. The combined cycle power plant as claimed in claim 1, wherein the high pressure steam mixture is reheated in the heat recovery steam generator prior to be transferred to the main steam turbine.
8. The combined cycle power plant as claimed in claim 1, further comprising a supercritical steam bypass line to bypass the supercritical steam turbine during power plant startup or when the supercritical steam turbine is unavailable, wherein the supercritical steam bypass line comprises a supercritical steam bypass valve, and wherein the supercritical steam bypass valve is configured to expand the supercritical steam to produce a high pressure steam that is suitable to the main steam turbine.
9. The combined cycle power plant as claimed in claim 8, further comprising a water injection device arranged in the supercritical steam bypass line downstream of the supercritical steam bypass valve, wherein the water injection device is configured to reduce temperature of the supercritical steam by injecting water to the supercritical steam.
10. A method for operating a combined cycle power plant, wherein the combined cycle power plant comprises a gas turbine, a heat recovery steam generator located downstream of the gas turbine, a main steam turbine, and a supercritical steam turbine, wherein the heat recovery steam generator comprises multiple pressure steam systems comprising a low pressure steam system, an intermediate pressure steam system, and a high pressure steam system, the method comprising: operating the gas turbine to generate power output; generating low pressure steam in the low pressure steam system of the heat recovery steam generator by extracting energy from exhaust gas of the gas turbine; generating intermediate pressure steam in the intermediate pressure steam system of the heat recovery steam generator by extracting energy from the exhaust gas of the gas turbine; generating supercritical steam in the high pressure steam system of the heat recovery steam generator by extracting energy from the exhaust gas of the gas turbine; transferring the supercritical steam to the supercritical steam turbine; expanding the supercritical steam in the supercritical steam turbine to generate power output and producing exiting steam; and operating the main steam turbine to generate power output from the exiting steam from the supercritical steam turbine, the intermediate pressure steam generated in the heat recovery steam generator, and the low pressure steam generated in the heat recovery steam generator, wherein the method further comprising: generating a subcritical high pressure steam in the high pressure steam system of the heat recovery steam generator, mixing the subcritical high pressure steam with the exiting steam from the supercritical steam turbine to generate a high pressure steam mixture, and transferring the high pressure steam mixture to the main steam turbine.
11. The method as claimed in claim 10, further comprising operating the supercritical steam turbine at a rotational speed that is higher than a grid frequency.
12. The method as claimed in claim 11, further comprising reducing the rotational speed of the supercritical steam turbine to the grid frequency via a gearbox.
13. The method as claimed in claim 12, wherein the supercritical steam turbine is connected to a supercritical steam turbine generator via the gearbox after reducing the rotational speed to the grid frequency.
14. The method as claimed in claim 12, wherein the supercritical steam turbine is connected to the main steam turbine via the gearbox after reducing the rotational speed to the grid frequency.
15. The method as claimed in claim 10, further comprising reheating the exiting steam from the supercritical steam turbine in the heat recovery steam generator prior to transferring to the main steam turbine.
16. The method as claimed in claim 10, further comprising: reheating the high pressure steam mixture in the heat recovery steam generator, transferring the reheated high pressure steam mixture to the main steam turbine.
17. The method as claimed in claim 10, further comprising bypassing the supercritical steam turbine during power plant startup or when the supercritical steam turbine is unavailable via a supercritical steam bypass line, wherein the supercritical steam is expanded in the supercritical steam bypass line via a supercritical steam bypass valve to produce a high pressure steam that is suitable to the main steam turbine.
18. A combined cycle power plant comprising: a gas turbine that is configured to generate power output; a heat recovery steam generators located downstream of the gas turbine that is configured to receive exhaust gas from the gas turbines and produce steam by extracting energy from the exhaust gas; a main steam turbine that is configured to generate power output; a supercritical steam turbine that is configured to generate power output, wherein the supercritical steam turbine is configured to be operated at a rotational speed that is higher than a grid frequency; and a gearbox connected to the supercritical steam turbine, wherein the gearbox is configured to reduce the rotational speed of the supercritical steam turbine to the grid frequency, wherein the heat recovery steam generator comprises multiple pressure steam systems comprising a low pressure steam system, an intermediate pressure steam system, and a high pressure steam system, wherein the low pressure steam system is configured to generate low pressure steam, wherein the intermediate pressure steam system is configured to generate intermediate pressure steam, wherein the high pressure steam system is configured to generate supercritical steam, wherein the supercritical steam is transferred to the supercritical steam turbine, wherein the supercritical steam turbine is configured to expand the supercritical steam to generate power output and produce exiting steam, wherein the main steam turbine is configured to generate power output from the exiting steam from the supercritical steam turbine, the intermediate pressure steam generated in the heat recovery steam generator, and the low pressure steam generated in the heat recovery steam generator, and wherein the high pressure steam system is configured to further generate subcritical high pressure steam, wherein the subcritical high pressure steam is mixed with the exiting steam from the supercritical steam turbine to generate high pressure steam mixture, and wherein the high pressure steam mixture is transferred to the main steam turbine.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
(1) Exemplary embodiments of the application are explained in further detail with respect to the accompanying drawings. In the drawings:
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(9) To facilitate understanding, identical reference numerals have been used, where possible, to designate identical elements that are common to the figures.
DETAILED DESCRIPTION OF INVENTION
(10) A detailed description related to aspects of the present invention is described hereafter with respect to the accompanying figures.
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(12) A combined cycle power plant 100 may be in a single shaft configuration, or in a multi-shaft configuration. The combined cycle power plant 100 illustrated in
(13) According to an embodiment, a HRSG 500 may comprise multiple pressure steam systems. In the example embodiment illustrated in
(14) According to an embodiment illustrated in
(15) According to an embodiment illustrated in
(16) According to an embodiment illustrated in
(17) According to an embodiment illustrated in
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(22) A combined cycle power plant 100 may be in a single shaft configuration, or in a multi-shaft configuration. The illustrated example embodiments of a combined cycle power plant 100 in
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(25) According to an aspect, the disclosed embodiments may include a separate supercritical steam turbine 600 and a main steam turbine 300. The separate supercritical steam turbine 600 may be operated at a rotational speed that is much higher than a grid frequency. The rotational speed of the supercritical steam turbine 600 may be reduced to a grid frequency by a gearbox 620.
(26) According to an aspect, the disclosed embodiments may address limitation of a power plant efficiency improvement of a single steam turboset. In a single steam turboset, a supercritical section, a high pressure section, an intermediate pressure, and a low pressure section may be all operated at the same speed at a grid frequency. This may impact plant efficiency improvement due to effects of the supercritical steam. For example, high pressure of the supercritical steam may increase shaft seal leakage losses. High pressure of the supercritical steam may reduce flow volume resulting in low turbine efficiency. The disclosed embodiments comprise a separate supercritical steam turbine and a main turbine. The disclosed embodiments may allow optimizing steam parameters to individual needs of each steam turbine section.
(27) Although various embodiments that incorporate the teachings of the present invention have been shown and described in detail herein, those skilled in the art can readily devise many other varied embodiments that still incorporate these teachings. The invention is not limited in its application to the exemplary embodiment details of construction and the arrangement of components set forth in the description or illustrated in the drawings. The invention is capable of other embodiments and of being practiced or of being carried out in various ways. Also, it is to be understood that the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting. The use of including, comprising, or having and variations thereof herein is meant to encompass the items listed thereafter and equivalents thereof as well as additional items. Unless specified or limited otherwise, the terms mounted, connected, supported, and coupled and variations thereof are used broadly and encompass direct and indirect mountings, connections, supports, and couplings. Further, connected and coupled are not restricted to physical or mechanical connections or couplings.
LIST OF REFERENCES
(28) 100 Combined Cycle Power Plant 200 Gas Turbine 220 Gas Turbine Generator 300 Main Steam Turbine 320 Main Steam Turbine Generator 400 Generator 500 Heat Recovery Steam Generator (HRSG) 520 High Pressure (HP) Steam System of the HRSG 522 HP Steam Line 524 Supercritical HP Steam System of the HRSG 526 Subcritical HP Steam System of the HRSG 530 Additional Reheater 540 Intermediate Pressure (IP) Steam System of the HRSG 542 IP Steam Line 544 Cold Reheat Line 546 Reheater 560 Low Pressure (LP) Steam System of the HRSG 562 LP Steam Line 564 Condensate Preheater 570 Condenser 572 Condensate Line 574 Condensate Extraction Pump 576 Boiler Feed Pump 580 Exhaust Stack 600 Supercritical Steam Turbine 610 Supercritical Steam Line 612 Supercritical Steam Flow Control Valve 620 Gearbox 630 Supercritical Steam Turbine Generator 640 Exiting Line of the Supercritical Steam Turbine 650 Supercritical Steam Bypass Line 652 Supercritical Steam Bypass Valve 654 Water Injection Device