A quick start system and method for a combined cycle unit decoupled steam turbine

Abstract

The application discloses a kind of decoupling steam engine combined cycle unit quick start system and method, including heat storage system, waste heat boiler, steam turbine power generation system and gas turbine power generation system, wherein, the outlet of gas turbine power generation system is communicated with the inlet of waste heat boiler, waste heat boiler is connected with heat storage system and steam turbine power generation system, the system and method can improve the power generation efficiency and flexibility of unit, while can avoid the problem of excessive pollutant emission caused by insufficient combustion.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of power generation, and relates to a combined cycle unit rapid starting system and method for decoupling steam turbines. BACKGROUND

[0002] With the increasing penetration of renewable energy year by year, the inherent properties of intermittency and volatility pose great challenges to the flexible regulation of power systems. Compared with conventional coal-fired units, gas-steam combined cycle units have become the first choice for flexible regulation power sources due to their rapid start-stop, high cycle efficiency, low pollutant emission and good peak shaving performance. In line with the principle of energy cascade utilization, a gas turbine is usually combined with a waste heat boiler and a steam turbine to form a combined cycle unit to improve energy utilization efficiency.

[0003] During the starting process of the gas-steam combined cycle unit, the gas turbine can quickly achieve ignition, speed-up and grid connection. However, the waste heat boiler and the steam turbine cannot achieve rapid starting due to the limitation of metal equipment thermal stress, and a large amount of time is needed for warm-up. Among them, the steam turbine rotor is more sensitive to thermal stress, so the long starting time caused by steam turbine warm-up is the main reason for limiting the starting speed of the gas-steam combined cycle unit. In order to wait for the steam turbine to warm up, the gas turbine needs to run at low load for a long time, which not only reduces the power generation efficiency of the unit, but also causes insufficient combustion and excessive emission of pollutants, and reduces the flexibility of the unit. SUMMARY

[0004] The purpose of the present application is to overcome the shortcomings of the prior art, and to provide a combined cycle unit rapid starting system and method for decoupling steam turbines, which can improve the power generation efficiency and flexibility of the unit, and avoid the problem of excessive emission of pollutants caused by insufficient combustion.

[0005] To achieve the above purpose, the present application discloses a combined cycle unit rapid starting system for decoupling steam turbines, which comprises a heat storage system, a waste heat boiler, a steam turbine power generation system and a gas turbine power generation system, wherein the outlet of the gas turbine power generation system is in communication with the inlet of the waste heat boiler, and the waste heat boiler is connected with the heat storage system and the steam turbine power generation system.

[0006] The waste heat boiler comprises a flue gas outlet, a high-pressure subsystem, a reheating subsystem, a medium-pressure subsystem and a low-pressure subsystem; the steam turbine power generation system comprises a high-pressure feedwater inlet, a medium-pressure feedwater inlet, a high-pressure cylinder, a medium-pressure cylinder and a low-pressure cylinder;

[0007] The outlet of the gas turbine power generation system is in communication with the flue gas outlet through the shell side of the high-pressure subsystem, the shell side of the reheating subsystem, the shell side of the medium-pressure subsystem and the shell side of the low-pressure subsystem in sequence;

[0008] The high-pressure water inlet is connected with the inlet of the high-pressure cylinder through the tube side of the high-pressure subsystem and the third valve, and the heat storage system is connected with the third valve in parallel;

[0009] The medium-pressure water inlet is connected with the inlet of the medium-pressure cylinder through the tube side of the medium-pressure subsystem, the pipe and the pipe of the outlet of the high-pressure cylinder, and the inlet of the low-pressure cylinder through the tube side of the reheating subsystem, the outlet of the medium-pressure cylinder is connected with the inlet of the low-pressure cylinder, the low-pressure water inlet is connected with the inlet of the low-pressure cylinder through the tube side of the low-pressure subsystem, and the outlet of the low-pressure cylinder is connected with the low-pressure cylinder exhaust pipe.

[0010] The heat storage system comprises a heat-releasing water inlet, a heat-releasing water outlet, a heat storage drainage outlet, a first molten salt-water heat exchanger, a second molten salt-water heat exchanger, a third molten salt-water heat exchanger, a high-temperature molten salt pump, a high-temperature molten salt tank, a low-temperature molten salt pump and a low-temperature molten salt tank.

[0011] The heat-releasing water inlet is connected with the primary side inlet of the first molten salt-water heat exchanger, and the primary side outlet of the first molten salt-water heat exchanger is connected with the heat-releasing water outlet.

[0012] The secondary side outlet of the first molten salt-water heat exchanger is connected with the secondary side inlet of the first molten salt-water heat exchanger in sequence through the low-temperature molten salt tank, the low-temperature molten salt pump, the primary side of the third molten salt-water heat exchanger and the primary side of the second molten salt-water heat exchanger, the high-temperature molten salt tank and the high-temperature molten salt pump.

[0013] The high-pressure water inlet is divided into two routes after the tube side of the high-pressure subsystem, one of which is connected with the inlet of the high-pressure cylinder through the third valve, and the other is connected with the secondary side inlet of the second molten salt-water heat exchanger through the second valve, and the secondary side outlet of the second molten salt-water heat exchanger is divided into two routes, one of which is connected with the inlet of the high-pressure cylinder, and the other is connected with the heat storage drainage outlet through the secondary side of the third molten salt-water heat exchanger.

[0014] The secondary side outlet of the first molten salt-water heat exchanger is connected with the secondary side inlet of the first molten salt-water heat exchanger in sequence through the sixth valve, the low-temperature molten salt tank, the low-temperature molten salt pump, the primary side of the third molten salt-water heat exchanger and the primary side of the second molten salt-water heat exchanger, the first valve, the high-temperature molten salt tank and the high-temperature molten salt pump.

[0015] The high-pressure water inlet is divided into two routes after the tube side of the high-pressure subsystem, one of which is connected with the inlet of the high-pressure cylinder through the third valve, and the other is connected with the secondary side inlet of the second molten salt-water heat exchanger through the second valve, and the secondary side outlet of the second molten salt-water heat exchanger is divided into two routes, one of which is connected with the inlet of the high-pressure cylinder through the fourth valve, and the other is connected with the heat storage drainage outlet in sequence through the fifth valve and the secondary side of the third molten salt-water heat exchanger.

[0016] The high-pressure cylinder, the medium-pressure cylinder, the low-pressure cylinder and the second generator are coaxially arranged.

[0017] The gas turbine power generation system comprises a fuel pipe, a compressor, a combustion chamber and a turbine, the outlet of the compressor and the fuel pipe are communicated with the inlet of the combustion chamber, the outlet of the combustion chamber is communicated with the inlet of the turbine, the outlet of the turbine is communicated with the inlet of the high-pressure sub-system,

[0018] The system further comprises a first generator, the turbine, the compressor and the first generator are coaxially arranged.

[0019] The quick start method of the combined cycle unit of the decoupled steam turbine comprises the following steps:

[0020] 1) the steam parameters of the waste heat boiler do not reach the turbine warm-up condition;

[0021] 2) the steam parameters of the waste heat boiler reach the turbine warm-up condition;

[0022] 3) the turbine warm-up process is completed;

[0023] 4) the heat release of the heat storage system.

[0024] Specifically, the method comprises the following steps:

[0025] 1) the steam parameters of the waste heat boiler do not reach the turbine warm-up condition;

[0026] The low-temperature molten salt pump is started, the high-temperature molten salt pump is stopped, the low-temperature molten salt is discharged from the low-temperature molten salt tank through the low-temperature molten salt pump, and then sequentially passes through the third molten salt-water heat exchanger and the second molten salt-water heat exchanger, and is then transported into the high-temperature molten salt tank; the high-temperature and high-pressure main steam is output from the high-pressure sub-system, and then sequentially passes through the second molten salt-water heat exchanger and the third molten salt-water heat exchanger to exchange heat with the molten salt, and then is discharged from the heat storage water outlet;

[0027] 2) the steam parameters of the waste heat boiler reach the turbine warm-up condition;

[0028] The low-temperature molten salt pump is started, the high-temperature molten salt pump is stopped, the low-temperature molten salt is discharged from the low-temperature molten salt tank through the low-temperature molten salt pump, and then sequentially passes through the third molten salt-water heat exchanger and the second molten salt-water heat exchanger, and is then transported into the high-temperature molten salt tank; the high-temperature and high-pressure main steam is output from the high-pressure sub-system, and then sequentially passes through the second molten salt-water heat exchanger and the third molten salt-water heat exchanger to exchange heat with the molten salt, and then is discharged from the heat storage water outlet;

[0029] 3) the turbine warm-up process is completed;

[0030] When the turbine warm-up process is completed, the high-temperature molten salt pump and the low-temperature molten salt pump are stopped, and the heat storage system stops running;

[0031] 4) the heat release of the heat storage system;

[0032] When the combined cycle unit needs heat, the high-temperature molten salt pump is started, the low-temperature molten salt pump is closed, the high-temperature molten salt is discharged from the high-temperature molten salt tank through the low-temperature molten salt pump, and then sequentially passes through the first molten salt-water heat exchanger and is transported into the high-temperature molten salt tank; the feed water enters the first molten salt-water heat exchanger from the heat-releasing feed water inlet, is heated into high-temperature high-pressure steam, and is then discharged from the heat-releasing feed water outlet.

[0033] The application has the following beneficial effects:

[0034] The combined cycle unit rapid starting system and method of the decoupled steam turbine have the following beneficial effects: BRIEF DESCRIPTION OF DRAWINGS

[0035] The accompanying drawings, which form a part of the specification, are included to provide a further understanding of the application and are incorporated herein for explanation by illustrating a preferred embodiment of the present application. In the drawings:

[0036] Figure 1 The accompanying drawings, which form a part of the specification, are included to provide a further understanding of the application and are incorporated herein for explanation by illustrating a preferred embodiment of the present application. In the drawings:

[0037] Wherein, 1 is a first generator, 2 is a compressor, 3 is a combustion chamber, 4 is a turbine, 5 is a high-pressure subsystem, 6 is a reheating subsystem, 7 is a medium-pressure subsystem, 8 is a low-pressure subsystem, 9 is a smoke exhaust outlet, 10 is a high-pressure feed water inlet, 11 is a medium-pressure feed water inlet, 12 is a low-pressure feed water inlet, 13 is a high-pressure cylinder, 14 is a medium-pressure cylinder, 15 is a low-pressure cylinder, 16 is a low-pressure cylinder exhaust pipeline, 17 is a second generator, 18 is a heat-releasing feed water inlet, 19 is a first molten salt-water heat exchanger, 20 is a heat-releasing feed water outlet, 21 is a high-temperature molten salt pump, 22 is a high-temperature molten salt tank, 23 is a first valve, 24 is a second valve, 25 is a third valve, 26 is a second molten salt-water heat exchanger, 27 is a fourth valve, 28 is a fifth valve, 29 is a third molten salt-water heat exchanger, 30 is a heat storage drain outlet, 31 is a low-temperature molten salt pump, 32 is a low-temperature molten salt tank, and 33 is a sixth valve. DETAILED DESCRIPTION

[0038] Clearly, the described embodiments are only a part of the embodiments of the present application, but not all the embodiments. Based on the embodiments of the present application, all the other embodiments obtained by a person of ordinary skill in the art without creative effort belong to the scope of protection of the present application.

[0039] In the description of the present application, it should be understood that the terms "comprising" and "including" indicate the presence of the described features, integers, steps, operations, elements, and / or components, but do not exclude one or more other features, integers, steps, operations, elements, components, and / or groups thereof.

[0040] It should also be understood that the terms used in the present application specification are only for the purpose of describing particular embodiments and are not intended to limit the present application. As used in the present application specification and the appended claims, unless otherwise clearly indicated, the singular forms "a," "an," and "the" are intended to include the plural forms as well.

[0041] It should be further understood that the term "and / or" used in the present application specification and the appended claims means one or more of the associated listed items as well as all possible combinations of the items and includes these combinations, for example, A and / or B can mean A alone, A and B, and B alone. In addition, the character " / " in the present application generally represents an "or" relationship between the front and rear associated objects.

[0042] It should be understood that although the terms first, second, third, etc. may be used in the embodiments of the present application to describe a predetermined range, etc., these predetermined ranges should not be limited to these terms. These terms are only used to distinguish the predetermined ranges from each other. For example, the first predetermined range can also be referred to as the second predetermined range, and similarly, the second predetermined range can also be referred to as the first predetermined range without departing from the scope of the embodiments of the present application.

[0043] Depending on the context, the word "if" as used herein can be interpreted as meaning "when" or "while" or "in response to determining" or "in response to detecting". Similarly, depending on the context, the phrase "if determined" or "if detecting (a stated condition or event)" can be interpreted as meaning "when determined" or "in response to determining" or "when detecting (a stated condition or event)" or "in response to detecting (a stated condition or event)".

[0044] In order to make the purposes, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only some but not all of the embodiments of the present application. The components of the embodiments of the present application described and shown in the drawings herein can be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present application provided in the drawings is not intended to limit the scope of the claimed present application, but only represents selected embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative work fall within the scope of protection of the present application.

[0045] Various structural schematic diagrams according to the disclosed embodiments of the present application are shown in the drawings. These diagrams are not drawn to scale, in which some details are exaggerated for the purpose of clear expression, and some details can be omitted. The shapes of various regions, layers and their relative sizes and positional relationships shown in the drawings are only exemplary, and in actuality, there can be deviations due to manufacturing tolerances or technical limitations, and regions / layers with different shapes, sizes and relative positions can be additionally designed by those skilled in the art according to actual needs.

[0046] Embodiment one

[0047] With reference to Figure 1 The combined cycle unit rapid start system of the decoupled steam turbine according to the present application comprises a first generator 1, a compressor 2, a combustion chamber 3, a turbine 4, a high-pressure subsystem 5, a reheat subsystem 6, a medium-pressure subsystem 7, a low-pressure subsystem 8, a flue gas outlet 9, a high-pressure feedwater inlet 10, a medium-pressure feedwater inlet 11, a low-pressure feedwater inlet 12, a high-pressure cylinder 13, a medium-pressure cylinder 14, a low-pressure cylinder 15, a low-pressure cylinder exhaust pipe 16, a second generator 17, a heat-releasing feedwater inlet 18, a first molten salt-water heat exchanger 19, a heat-releasing feedwater outlet 20, a high-temperature molten salt pump 21, a high-temperature molten salt tank 22, a first valve 23, a second valve 24, a third valve 25, a second molten salt-water heat exchanger 26, a fourth valve 27, a fifth valve 28, a third molten salt-water heat exchanger 29, a heat storage drain outlet 30, a low-temperature molten salt pump 31, a low-temperature molten salt tank 32 and a sixth valve 33.

[0048] The heat-releasing feedwater inlet 18 is connected to the primary side inlet of the first molten salt-water heat exchanger 19, and the primary side outlet of the first molten salt-water heat exchanger 19 is connected to the heat-releasing feedwater outlet 20.

[0049] The second side outlet of the first molten salt-water heat exchanger 19 is connected with the first side inlet of the second molten salt-water heat exchanger 26 in sequence through the sixth valve 33, the low-temperature molten salt tank 32, the low-temperature molten salt pump 31, the third molten salt-water heat exchanger 29 and the first valve 23.

[0050] The outlet of the compressor 2 and the fuel pipe are connected with the inlet of the combustion chamber 3, the outlet of the combustion chamber 3 is connected with the inlet of the turbine 4, the turbine 4, the compressor 2 and the first generator 1 are coaxially arranged, and the outlet of the turbine 4 is connected with the exhaust outlet 9 in sequence through the shell side of the high-pressure subsystem 5, the shell side of the reheating subsystem 6, the shell side of the medium-pressure subsystem 7, the shell side of the low-pressure subsystem 8.

[0051] The high-pressure water inlet 10 is divided into two routes after passing through the tube side of the high-pressure subsystem 5, one of which is connected with the inlet of the high-pressure cylinder 13 through the third valve 25, and the other is connected with the second side inlet of the second molten salt-water heat exchanger 26 through the second valve 24, the second side outlet of the second molten salt-water heat exchanger 26 is divided into two routes, one of which is connected with the inlet of the high-pressure cylinder 13 through the fourth valve 27, and the other is connected with the heat storage and drainage outlet 30 in sequence through the fifth valve 28 and the second side of the third molten salt-water heat exchanger 29.

[0052] The medium-pressure water inlet 11 is connected with the outlet of the high-pressure cylinder 13 through a pipe after passing through the tube side of the medium-pressure subsystem 7, and then connected with the inlet of the medium-pressure cylinder 14 through the tube side of the reheating subsystem 6, the outlet of the medium-pressure cylinder 14 is connected with the inlet of the low-pressure cylinder 15, the low-pressure water inlet 12 is connected with the inlet of the low-pressure cylinder 15 through the tube side of the low-pressure subsystem 8, and the outlet of the low-pressure cylinder 15 is connected with the low-pressure cylinder exhaust pipe 16.

[0053] The high-pressure cylinder 13, the medium-pressure cylinder 14, the low-pressure cylinder 15 and the second generator 17 are coaxially arranged.

[0054] The first molten salt-water heat exchanger 19, the second molten salt-water heat exchanger 26, the third molten salt-water heat exchanger 29, the high-temperature molten salt pump 21, the high-temperature molten salt tank 22, the low-temperature molten salt pump 31 and the low-temperature molten salt tank 32 constitute a heat storage system. The high-pressure subsystem 5, the reheating subsystem 6, the medium-pressure subsystem 7 and the low-pressure subsystem 8 constitute a waste heat boiler. The high-pressure cylinder 13, the medium-pressure cylinder 14, the low-pressure cylinder 15 and the second generator 17 constitute a steam turbine power generation system. The first generator 1, the compressor 2, the combustion chamber 3 and the turbine 4 constitute a gas turbine power generation system.

[0055] Example two

[0056] Reference Figure 1 The combined cycle unit rapid start system of the decoupling steam turbine of the application comprises the following steps:

[0057] The air after filtering the screen enters the compressor 2 to be compressed into high pressure air, then enters the combustion chamber 3 to be mixed with fuel to burn, and after forming high temperature and high pressure gas, the high temperature and high pressure gas enters the turbine 4 to drive the turbine to work, and the rotating mechanical energy generated by the turbine 4 is used to drive the compressor 2 to compress air, and the remaining is used to drive the first generator 1 to generate electricity; the gas after the turbine 4 works still has a very high temperature, enters the waste heat boiler composed of the high pressure subsystem 5, the reheating subsystem 6, the medium pressure subsystem 7 and the low pressure subsystem 8 to exchange heat, and after the heat exchange is completed, the gas is discharged into the atmosphere through the exhaust gas outlet 9. The high pressure feed water enters the high pressure subsystem 5 through the high pressure feed water inlet 10 to generate high pressure superheated steam, the medium pressure feed water enters the medium pressure subsystem 7 through the medium pressure feed water inlet 11 to generate medium pressure superheated steam, and after being mixed with the cold re-steam discharged from the high pressure cylinder 13, the medium pressure feed water enters the reheating subsystem 6 to generate medium pressure hot re-steam, and the low pressure feed water enters the low pressure subsystem 8 through the low pressure feed water inlet 12 to generate low pressure superheated steam. The high pressure subsystem 5, the medium pressure subsystem 7 and the low pressure subsystem 8 are composed of staggered arrangements of multiple economizers, evaporators and superheaters, and the reheating subsystem 6 is composed of multiple superheaters. Since the flow of the high pressure feed water is much larger than the flow of the medium pressure feed water and the flow of the low pressure feed water, the steam generation performance of the waste heat boiler mainly depends on the high pressure steam parameters.

[0058] 1) The steam generation parameters of the waste heat boiler do not reach the warm-up conditions of the steam turbine;

[0059] In the early stage of starting the combined cycle unit, the exhaust gas temperature and flow of the gas turbine are low, and the steam generation parameters of the waste heat boiler are also low, so that the steam turbine cannot be warmed up. In the traditional combined cycle unit, the exhaust gas is directly discharged into the atmosphere or the condenser, causing a large amount of waste of heat energy. In the present application, the heat energy is recovered through the heat storage system, and the specific process is as follows: the first valve 23, the second valve 24 and the fifth valve 28 are opened, the third valve 25, the fourth valve 27 and the sixth valve 33 are closed, the low temperature molten salt pump 31 is started, and the high temperature molten salt pump 21 is closed. The low temperature molten salt is discharged from the low temperature molten salt tank 32 through the low temperature molten salt pump 31, and then sequentially passes through the third molten salt-water heat exchanger 29, the second molten salt-water heat exchanger 26 and the first valve 23, and is then delivered to the high temperature molten salt tank 22. The high temperature and high pressure main steam is output from the high pressure subsystem 5, and then exchanges heat with the molten salt through the second valve 24, the second molten salt-water heat exchanger 26, the fifth valve 28 and the third molten salt-water heat exchanger 29, and then is discharged from the heat storage water outlet 30.

[0060] 2) The steam generation parameters of the waste heat boiler reach the warm-up conditions of the steam turbine;

[0061] With the start-up process, the steam parameters of the waste heat boiler are rising, when reaching the warm-up conditions of the steam turbine, the traditional combined cycle unit will make the gas turbine run at low load conditions, so that the steam parameters generated by the waste heat boiler can just meet the warm-up conditions of the steam turbine, but the gas turbine will produce problems such as efficiency decline and excessive pollutant emission when running at low load for a long time. Therefore, in the present application, the gas turbine will continue to increase the load until full load, and the high-parameter steam generated by the waste heat boiler will be introduced into the steam turbine for warm-up after being branched, cooled and decompressed through the heat storage system. The specific process is as follows: the first valve 23, the second valve 24, the third valve 25, the fourth valve 27 and the fifth valve 28 are opened, the sixth valve 33 is closed, the low-temperature molten salt pump 31 is started, the high-temperature molten salt pump 21 is closed, the low-temperature molten salt is discharged from the low-temperature molten salt tank 32 through the low-temperature molten salt pump 31, and then sequentially passes through the third molten salt-water heat exchanger 29, the second molten salt-water heat exchanger 26 and the first valve 23, and is transported into the high-temperature molten salt tank 22; the high-pressure main steam is output from the high-pressure subsystem 5, and then sequentially passes through the second valve 24, the second molten salt-water heat exchanger 26, the fifth valve 28 and the third molten salt-water heat exchanger 29 and exchanges heat with the molten salt, and then is discharged from the heat storage water outlet 30; with the progress of the warm-up process, the warm-up steam parameters of the steam turbine are also changing, so the valve opening degrees of the first valve 23, the second valve 24, the third valve 25, the fourth valve 27 and the fifth valve 28 can be adjusted to make the warm-up steam parameters of the steam turbine meet the requirements.

[0062] 3) The warm-up process of the steam turbine is completed;

[0063] When the warm-up process of the steam turbine is completed, the third valve 25 is opened, the first valve 23, the second valve 24, the fourth valve 27, the fifth valve 28 and the sixth valve 33 are closed, the high-temperature molten salt pump 21 and the low-temperature molten salt pump 31 are closed, and the heat storage system stops running. The combined cycle unit in the present application and the traditional unit have the same operation mode.

[0064] 4) Heat release of the heat storage system;

[0065] When the combined cycle unit needs heat, for example, for external heat supply, inlet air cooling and fuel heating, the sixth valve 33 is opened, the first valve 23, the second valve 24, the third valve 25, the fourth valve 27 and the fifth valve 28 are closed, the high-temperature molten salt pump 21 is started, and the low-temperature molten salt pump 31 is closed. The high-temperature molten salt is discharged from the high-temperature molten salt tank 22 through the low-temperature molten salt pump 31, and then sequentially passes through the first molten salt-water heat exchanger 19 and the sixth valve 33, and is transported into the high-temperature molten salt tank 22; the feed water enters the first molten salt-water heat exchanger 19 from the heat release feed water inlet 18, is heated into high-pressure steam, and is discharged from the heat release feed water outlet 20, and is used for different heat supply requirements.

[0066] The present application has the following characteristics:

[0067] 1) The combined cycle unit is started, without considering the warming process of the steam turbine, the gas turbine and the waste heat boiler can quickly reach full load operation condition, improve the flexibility of the unit;

[0068] 2) The time interval of the gas turbine in low load state is shortened, the emission of pollutants is reduced, the power generation efficiency of the unit is improved, and the economy is enhanced;

[0069] 3) The thermal energy stored in the heat storage system during the starting process can be used for subsequent different heat utilization scenarios, such as inlet cooling and fuel heating, etc., improving the comprehensive complementary utilization ability of the system, and getting rid of the dependence on other heat sources.

[0070] 4) The application only needs to extract steam on the main steam pipe of the existing combined cycle unit, and will not change the normal operation mode of the unit, the risk degree of the modification is low, and the promotion is good.

[0071] Other embodiments of the application will be apparent to those skilled in the art from consideration of the specification and practice of the application disclosed herein. This application is intended to cover any variations, uses or adaptations of the application following, in general, the principles of the application and including such departures from the present disclosure as come within known or customary practice in the art. The specification and examples are to be regarded as illustrative only, and the true scope and spirit of the application is indicated by the following claims.

[0072] It should be understood that the application is not limited to the precise construction that has been described above and illustrated in the accompanying drawings, and that various modifications and changes can be made by those skilled in the art without departing from the scope of the application. The scope of the application is limited only by the appended claims.

[0073] The above is only the preferred embodiment of the application, not any limitation on the application, any simple modification, change and equivalent structure change of the above embodiment according to the technical essence of the application are still within the protection scope of the technical scheme of the application.

Claims

1. A method for quickly starting a combined cycle unit with a decoupled steam turbine, characterized in that: A combined cycle unit rapid start-up system based on a decoupled steam turbine, comprising a heat storage system, a waste heat boiler, a steam turbine power generation system, and a gas turbine power generation system, wherein the outlet of the gas turbine power generation system is connected to the inlet of the waste heat boiler, and the waste heat boiler is connected to the heat storage system and the steam turbine power generation system; The waste heat boiler includes a smoke exhaust outlet (9), a high-pressure subsystem (5), a reheat subsystem (6), a medium-pressure subsystem (7), and a low-pressure subsystem (8); the steam turbine power generation system includes a high-pressure feed water inlet (10), a medium-pressure feed water inlet (11), a high-pressure cylinder (13), a medium-pressure cylinder (14), and a low-pressure cylinder (15); The outlet of the gas turbine power generation system is connected to the exhaust outlet (9) through the shell side of the high-pressure subsystem (5), the shell side of the reheat subsystem (6), the shell side of the medium-pressure subsystem (7) and the shell side of the low-pressure subsystem (8); The high-pressure water supply inlet (10) is connected to the inlet of the high-pressure cylinder (13) through the pipe side of the high-pressure subsystem (5) and the third valve (25), and the heat storage system is connected in parallel with the third valve (25); The medium-pressure water supply inlet (11) passes through the pipe side of the medium-pressure subsystem (7) and is connected to the outlet of the high-pressure cylinder (13) through a pipe, and then is connected to the inlet of the medium-pressure cylinder (14) through the pipe side of the reheat subsystem (6). The outlet of the medium-pressure cylinder (14) is connected to the inlet of the low-pressure cylinder (15). The low-pressure water supply inlet (12) passes through the pipe side of the low-pressure subsystem (8) and is connected to the inlet of the low-pressure cylinder (15). The outlet of the low-pressure cylinder (15) is connected to the low-pressure cylinder exhaust pipe (16). The heat storage system comprises a heat release water inlet (18), a heat release water outlet (20), a heat storage water outlet (30), a first molten salt-water heat exchanger (19), a second molten salt-water heat exchanger (26), a third molten salt-water heat exchanger (29), a high-temperature molten salt pump (21), a high-temperature molten salt tank (22), a low-temperature molten salt pump (31) and a low-temperature molten salt tank (32); The heat release water inlet (18) is connected to the primary side inlet of the first molten salt-water heat exchanger (19), and the primary side outlet of the first molten salt-water heat exchanger (19) is connected to the heat release water outlet (20); The secondary side outlet of the first molten salt-water heat exchanger (19) is connected to the secondary side inlet of the first molten salt-water heat exchanger (19) through the low-temperature molten salt tank (32), the low-temperature molten salt pump (31), the primary side of the third molten salt-water heat exchanger (29), the primary side of the second molten salt-water heat exchanger (26), the high-temperature molten salt tank (22) and the high-temperature molten salt pump (21); The high-pressure water supply inlet (10) is divided into two paths after passing through the pipe side of the high-pressure subsystem (5), one of which is connected to the inlet of the high-pressure cylinder (13) through the third valve (25), and the second is connected to the secondary side inlet of the second molten salt-water heat exchanger (26). The secondary side outlet of the second molten salt-water heat exchanger (26) is divided into two paths, one of which is connected to the inlet of the high-pressure cylinder (13), and the other is connected to the heat storage drainage outlet (30) through the secondary side of the third molten salt-water heat exchanger (29); The method comprises the following steps: 1) The steam production parameters of the waste heat boiler do not meet the steam turbine warm-up conditions; The low-temperature molten salt pump (31) is started, and the high-temperature molten salt pump (21) is closed. The low-temperature molten salt is discharged from the low-temperature molten salt tank (32) through the low-temperature molten salt pump (31), passes through the third molten salt-water heat exchanger (29), the second molten salt-water heat exchanger (26), and then is transported to the high-temperature molten salt tank (22). The high-temperature and high-pressure main steam is output from the high-pressure subsystem (5), and then passes through the second molten salt-water heat exchanger (26) and the third molten salt-water heat exchanger (29) to exchange heat with the molten salt, and then is discharged from the heat storage drainage outlet (30); 2) The steam production parameters of the waste heat boiler meet the steam turbine warm-up conditions; The low-temperature molten salt pump (31) is started, and the high-temperature molten salt pump (21) is closed. The low-temperature molten salt is discharged from the low-temperature molten salt tank (32) through the low-temperature molten salt pump (31), and then passes through the third molten salt-water heat exchanger (29) and the second molten salt-water heat exchanger (26) in sequence, and then is transported to the high-temperature molten salt tank (22); the high-temperature and high-pressure main steam is output from the high-pressure subsystem (5), and then passes through the second molten salt-water heat exchanger (26) and the third molten salt-water heat exchanger (29) in sequence to exchange heat with the molten salt, and then is discharged from the heat storage drainage outlet (30); 3) The turbine warm-up process is completed; When the turbine warm-up process is completed, the high-temperature molten salt pump (21) and the low-temperature molten salt pump (31) are turned off, and the heat storage system stops operating; 4) Heat storage system releases heat; When the combined cycle unit needs heat, the high-temperature molten salt pump (21) is started and the low-temperature molten salt pump (31) is closed. The high-temperature molten salt is discharged from the high-temperature molten salt tank (22) through the low-temperature molten salt pump (31) and then passes through the first molten salt-water heat exchanger (19) in sequence and is then transported to the high-temperature molten salt tank (22). The feed water enters the first molten salt-water heat exchanger (19) from the heat release feed water inlet (18) and is heated to high-temperature and high-pressure steam, and then is discharged from the heat release feed water outlet (20).

2. The method for rapid startup of a combined cycle unit with a decoupled steam turbine according to claim 1, characterized in that: The secondary side outlet of the first molten salt-water heat exchanger (19) is connected to the secondary side inlet of the first molten salt-water heat exchanger (19) through the sixth valve (33), the low-temperature molten salt tank (32), the low-temperature molten salt pump (31), the primary side of the third molten salt-water heat exchanger (29) and the primary side of the second molten salt-water heat exchanger (26), the first valve (23), the high-temperature molten salt tank (22) and the high-temperature molten salt pump (21).

3. The method for rapid startup of a combined cycle unit with a decoupled steam turbine according to claim 1, characterized in that: The high-pressure water supply inlet (10) is divided into two paths after passing through the pipe side of the high-pressure subsystem (5), one of which is connected to the inlet of the high-pressure cylinder (13) through the third valve (25), and the second is connected to the secondary side inlet of the second molten salt-water heat exchanger (26) through the second valve (24). The secondary side outlet of the second molten salt-water heat exchanger (26) is divided into two paths, one of which is connected to the inlet of the high-pressure cylinder (13) through the fourth valve (27), and the other is connected to the heat storage drainage outlet (30) through the fifth valve (28) and the secondary side of the third molten salt-water heat exchanger (29) in sequence.

4. The method for rapid startup of a combined cycle unit with a decoupled steam turbine according to claim 1, characterized in that: The high-pressure cylinder (13), the medium-pressure cylinder (14), the low-pressure cylinder (15) and the second generator (17) are coaxially arranged.

5. The method for rapid startup of a combined cycle unit with a decoupled steam turbine according to claim 1, characterized in that: The gas turbine power generation system includes a fuel pipeline, a compressor (2), a combustion chamber (3) and a turbine (4). The outlet of the compressor (2) and the fuel pipeline are connected to the inlet of the combustion chamber (3). The outlet of the combustion chamber (3) is connected to the inlet of the turbine (4). The outlet of the turbine (4) passes through the shell side of the high-pressure subsystem (5) in turn.

6. The method for rapid startup of a combined cycle unit with a decoupled steam turbine according to claim 1, characterized in that: It also includes a first generator (1), a turbine (4), a compressor (2) and the first generator (1) arranged coaxially.

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