A gas-steam combined cycle power and heat supply system

Abstract

The present application relates to the technical field of heat supply system, in particular to a gas-steam combined cycle power generation and heat supply system, comprising: a gas turbine power generation subsystem comprising a gas turbine body and a first generator; a steam turbine power generation subsystem comprising a waste heat boiler, a steam turbine body, a condenser and a second generator which are sequentially and circularly connected; a molten salt energy storage subsystem comprising a low-temperature molten salt storage, a first heat exchanger, a high-temperature molten salt storage and a second heat exchanger which are sequentially and circularly connected; a flue gas outlet of the gas turbine body is communicated with a high-temperature side inlet of the first heat exchanger, a high-temperature side outlet of the first heat exchanger is communicated with a flue gas side inlet of the waste heat boiler, and a low-temperature side of the second heat exchanger is communicated with a heat supply channel. By coupling the molten salt energy storage subsystem, the gas turbine body can always work in a high-efficiency state, the heat supply of the system in the non-peaking frequency modulation stage is realized, the economy of the power plant is improved, and the operation and maintenance cost of the gas turbine body is reduced.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of heat supply system, in particular to a gas-steam combined cycle power generation and heat supply system. BACKGROUND

[0002] Compared with thermal power, gas-steam combined cycle generating unit has the characteristics of large emission reduction potential, fast start-stop speed, fast installation and small water consumption, and gradually becomes the main force of peak load and frequency modulation. The whole gas-steam combined cycle is composed of a gas turbine, a waste heat boiler, a steam turbine and a generator. On the one hand, the gas turbine drives the generator to generate electricity, and on the other hand, the high-temperature flue gas discharged from the gas turbine is recovered and converted into steam through the waste heat boiler, and then the steam is injected into the steam turbine to generate electricity. In addition to power generation, the gas-steam combined cycle unit also needs to meet the heating demand of surrounding factories and residents.

[0003] Due to the relative lack of natural gas resources, the power generation cost of gas turbine power plant is higher than that of coal-fired power plant, so the gas turbine power plant is mainly responsible for the peak load and frequency modulation of the power grid. In addition to peak load and frequency modulation, gas turbine power plants that undertake power generation and heating tasks also need to run at low load to meet heating demand. When running at low load, the operating efficiency of the gas turbine body is low, the pollution emission is high, the frequency of gas turbine maintenance increases, and the operating cost increases. This leads to a significant reduction in the economic efficiency of the gas turbine power plant, and at the same time, it also increases the frequency of gas turbine maintenance and increases the operating cost of the gas turbine power plant. SUMMARY

[0004] Therefore, the technical problem to be solved by the present application is to overcome the defect that the operating cost of the existing gas-steam combined cycle power generation and heat supply system is high, so as to provide a gas-steam combined cycle power generation and heat supply system.

[0005] In order to solve the above technical problems, the present application provides a gas-steam combined cycle power generation and heat supply system, comprising:

[0006] A gas turbine power generation system comprising a gas turbine body and a first generator;

[0007] A steam turbine power generation system comprising a steam side of a waste heat boiler, a steam turbine body, a condenser and a second generator which are sequentially and circularly connected;

[0008] A molten salt energy storage subsystem comprising a low-temperature molten salt storage, a low-temperature side of a first heat exchanger, a high-temperature molten salt storage and a high-temperature side of a second heat exchanger which are sequentially and circularly connected;

[0009] The flue gas outlet of the gas turbine body is in communication with the high-temperature side inlet of the first heat exchanger, the high-temperature side outlet of the first heat exchanger is in communication with the flue gas side inlet of the waste heat boiler, and the low-temperature side of the second heat exchanger is provided with a heat supply channel.

[0010] Optionally, the steam turbine body is provided with a steam extraction channel, and the steam extraction channel is communicated with the heat supply channel.

[0011] Optionally, a feedwater channel is communicated with the condenser, and a boiler feedwater filter is installed on the feedwater channel.

[0012] Optionally, a boiler feedwater pump is installed on the feedwater channel upstream of the boiler feedwater filter.

[0013] Optionally, the flue gas outlet of the gas turbine body and the flue gas side inlet of the waste heat boiler are communicated through a main flue gas channel.

[0014] Optionally, the outlet of the low-temperature molten salt storage component and the inlet of the high-temperature molten salt storage component are further communicated with a heat release branch; and / or the outlet of the high-temperature molten salt storage component and the inlet of the low-temperature molten salt storage component are further communicated with a heat storage branch.

[0015] Optionally, the flue gas side outlet end of the waste heat boiler is communicated with a smoke exhaust device, and a flue gas treatment device is installed between the waste heat boiler and the smoke exhaust device.

[0016] Optionally, a heat supply pressurizing pump is installed on the heat supply channel.

[0017] Optionally, a deaerator is installed between the condenser and the waste heat boiler.

[0018] Optionally, a heat supply feedwater filter is installed on the heat supply channel upstream of the second heat exchanger, and a heat supply feedwater pump is installed upstream of the heat supply feedwater filter.

[0019] The technical scheme of the present application has the following advantages:

[0020] 1. The gas-steam combined cycle power generation and heat supply system provided by the present application comprises: a gas turbine power generation system comprising a gas turbine body and a first generator; a steam turbine power generation system comprising a steam side of a waste heat boiler, a steam turbine body, a condenser and a second generator which are sequentially and circularly communicated; a molten salt energy storage subsystem comprising a low-temperature molten salt storage component, a low-temperature side of a first heat exchanger, a high-temperature molten salt storage component and a high-temperature side of a second heat exchanger which are sequentially and circularly communicated; the flue gas outlet of the gas turbine body is communicated with the high-temperature side inlet of the first heat exchanger, the high-temperature side outlet of the first heat exchanger is communicated with the flue gas side inlet of the waste heat boiler, and the low-temperature side of the second heat exchanger is communicated with a heat supply channel.

[0021] In the gas turbine power generation system and the steam turbine power generation system, the molten salt energy storage subsystem is coupled, the gas-steam combined cycle power generation and heating system, when needing low load peak shaving and frequency modulation, the gas turbine body and the steam turbine body still keep high load work, part of the flue gas generated in the gas turbine body is introduced into the first heat exchanger, the molten salt circulates between the high-temperature molten salt storage and the low-temperature molten salt storage in the molten salt energy storage subsystem, the molten salt absorbs the heat of the flue gas in the first heat exchanger and stores into the high-temperature molten salt storage, part of the flue gas heat is stored in the high-temperature molten salt storage of the molten salt energy storage subsystem. When the gas-steam combined cycle power generation and heating system generates power in the peak shaving and frequency modulation, the steam is extracted from the steam turbine to output steam for external heating; when the gas-steam combined cycle power generation and heating system does not generate power in the peak shaving and frequency modulation, the gas turbine body and the steam turbine body do not work, at this time, the molten salt circulates between the high-temperature molten salt storage and the low-temperature molten salt storage, when the molten salt passes through the second heat exchanger, the molten salt exchanges heat with the heat supply channel of the low-temperature side of the second heat exchanger, the heat energy stored in the molten salt is released to the heat supply medium in the heat supply channel, which is used for external heating when the gas-steam combined cycle power generation and heating system does not generate power in the peak shaving and frequency modulation. By coupling the molten salt energy storage subsystem, on the one hand, the gas turbine body can work in the high-efficiency state after starting, and on the other hand, the heating of the combined cycle power generation and heating system in the non-peak shaving and frequency modulation stage is realized, which greatly improves the economy of the power plant and effectively reduces the operation and maintenance cost of the gas turbine body.

[0022] 2. The gas-steam combined cycle power generation and heating system provided by the present application, the steam extraction channel is arranged on the steam turbine body and communicates with the heat supply channel. The steam turbine body and the molten salt energy storage subsystem share the same heat supply channel for external heating, the heating steam is generated by the steam extraction channel of the steam turbine body when the gas-steam combined cycle power generation and heating system generates power in the peak shaving and frequency modulation, and the heating steam is generated by the molten salt energy storage subsystem when the system does not generate power in the peak shaving and frequency modulation, which completely solves the problem that the gas turbine power plant cannot continuously heat or the economy of continuous heating is poor. BRIEF DESCRIPTION OF DRAWINGS

[0023] In order to more clearly illustrate the specific embodiments of the present application or the technical solutions in the prior art, the following will briefly introduce the drawings needed to be used in the description of the specific embodiments or the prior art. Obviously, the drawings described below are some embodiments of the present application, and other drawings can also be obtained by those skilled in the art without creative labor.

[0024] Figure 1 The schematic diagram of the gas-steam combined cycle power generation and heating system provided in the embodiments of the present application.

[0025] Explanation of reference signs: 1, first generator; 2, compressor; 3, fuel inlet; 4, combustion chamber; 5, gas turbine turbine; 6, waste heat boiler; 7, flue gas treatment device; 8, chimney; 9, steam turbine body; 10, second generator; 11, condenser; 12, boiler feed water pump; 13, boiler feed water filter; 14, circulating water pump; 15, deaerator; 16, first heat supply switch; 17, first flue gas switch; 18, first heat exchanger; 19, high-temperature molten salt tank; 20, second molten salt pump; 21, first circulation switch; 22, second heat exchanger; 23, low-temperature molten salt tank; 24, first molten salt pump; 25, second circulation switch; 26, second flue gas switch; 27, third circulation switch; 28, fourth circulation switch; 29, heat supply feed water pump; 30, heat supply feed water filter; 31, second heat supply switch; 32, heat supply pressurizing pump; 33, user. DETAILED DESCRIPTION

[0026] The technical solutions of the present application will be described clearly and completely below in conjunction with the drawings. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0027] In the description of the present application, it should be noted that the orientations or positional relationships indicated by the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. are based on the orientations or positional relationships shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and therefore cannot be understood as indicating or implying that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the present application. In addition, the terms "first", "second", "third" are only for descriptive purposes and cannot be understood as indicating or implying relative importance.

[0028] In the description of the present application, it should be noted that unless otherwise explicitly specified and limited, the terms "mounting", "connection", "connection" should be understood broadly, for example, it can be fixedly connected, or it can be detachably connected, or integrally connected; it can be mechanically connected, or it can be electrically connected; it can be directly connected, or it can be indirectly connected through an intermediate medium; it can be the communication inside two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0029] In addition, the technical features involved in the different embodiments of the present application described below can be combined with each other as long as they do not conflict with each other.

[0030] Figure 1The gas-steam combined cycle power and heat supply system provided by the embodiment comprises a gas turbine power generation subsystem, a steam turbine power generation subsystem and a molten salt energy storage subsystem.

[0031] The gas turbine power generation subsystem comprises a gas turbine body and a first generator 1 coaxially installed with the gas turbine body. The steam turbine power generation subsystem comprises a steam side of a waste heat boiler 6, a steam turbine body 9, a condenser 11, a circulating water pump 14, a deaerator 15 and a second generator 10 connected in sequence. The molten salt energy storage subsystem comprises a low-temperature molten salt tank 23 as a low-temperature molten salt storage unit, a first molten salt pump 24, a second circulating switch 25, a low-temperature side of a first heat exchanger 18, a second molten salt pump 20, a first circulating switch 21, a high-temperature molten salt tank 19 as a high-temperature molten salt storage unit and a high-temperature side of a second heat exchanger 22 connected in sequence.

[0032] In order to provide high-temperature steam to the outside when the system is in peak regulation and frequency modulation, an extraction channel is arranged on the steam turbine body 9 and is connected with the heat supply channel.

[0033] The high-temperature flue gas output from the gas turbine body is connected with the flue gas side inlet of the waste heat boiler 6 through a main flue gas channel, and the waste heat boiler 6 is heated by the high-temperature flue gas output from the gas turbine body to heat water into steam, which drives the steam turbine body to operate and drive the second generator 10 to generate electricity, thereby improving the thermal efficiency of the gas-steam combined cycle power and heat supply system.

[0034] The outlet of the low-temperature molten salt storage unit is connected with the inlet of the high-temperature molten salt storage unit through a heat release branch, and the third circulating switch 27 is arranged on the heat release branch.

[0035] In the gas turbine power generation system, the first generator 1 is connected with the gas turbine body, for converting the mechanical energy generated by the gas turbine body into electric energy; the flue gas side inlet of the waste heat boiler 6 is connected with the gas turbine body through the main flue gas passage, for generating high temperature and high pressure steam by using the high temperature flue gas generated by the gas turbine body. The steam turbine body 9 is connected with the waste heat boiler 6, the high temperature and high pressure steam generated by the waste heat boiler 6 is introduced into the steam turbine body 9 to do work, and the second generator 10 is installed on the steam turbine body 9, for converting the mechanical energy generated by the steam turbine body 9 into electric energy. In the embodiment, in the gas turbine body, the air is heated and pressurized by the compressor 2 and then enters the combustion chamber 4, the fuel enters the combustion chamber 4 from the fuel inlet 3, mixes with the air and burns, and the chemical energy of the fuel is converted into mechanical energy. The first generator 1 is connected with the gas turbine, and converts the mechanical energy generated by the gas turbine into electric energy. In order to improve the thermal efficiency of the gas turbine, the high temperature flue gas discharged from the gas turbine turbine 5 is introduced into the waste heat boiler 6 through the main flue gas passage to form high temperature and high pressure steam, and then the high temperature and high pressure steam is introduced into the steam turbine body 9 to do work. The second generator 10 is connected with the steam turbine body 9, and converts the mechanical energy generated by the steam turbine body 9 into electric energy. The flue gas formed by heat exchange in the waste heat boiler 6 is treated by desulfurization and denitrification in the flue gas treatment device 7, and then is discharged through the chimney 8 under the premise of meeting the local emission requirements.

[0036] In order to improve the economic benefit of the gas turbine power plant, the water circulation is realized by a closed circulation system on the steam side of the system, a backwater pipeline is arranged downstream of the steam turbine body 9, and a condenser 11, a circulating water pump 14 and a deaerator 15 are arranged in the backwater pipeline. The condenser 11 condenses the steam after work into water, which is pressurized by the circulating water pump 14 and deaerated by the deaerator 15, and then is returned to the waste heat boiler 6 for recycling. The circulating water is deaerated in order to avoid corrosion of the waste heat boiler 6 and the steam turbine body 9 as much as possible. A boiler feed water device is also arranged at the condenser 11, municipal water is pressurized by a boiler feed water pump 12 and filtered by a boiler feed water filter 13, and then is introduced into the waste heat boiler 6 to supplement the water consumed by steam extraction for heating from the steam turbine body 9.

[0037] In the embodiment, since the gas-steam combined cycle system has a fast start-up speed, when the power grid side needs to be adjusted for peak and frequency, the entire unit is started up quickly, the first generator 1 and the second generator 10 generate electricity and are connected to the grid, and the rapid peak and frequency adjustment of the power grid side is realized. At the same time, heating can also be realized by extracting steam from the steam turbine body 9. The flue gas treatment device 7 and the chimney 8 arranged downstream of the flue gas side of the waste heat boiler 6 are used for denitrification and desulfurization treatment of the spent gas after work, and the flue gas is discharged under the premise of meeting the local emission requirements.

[0038] The first molten salt pump 24 and the second molten salt pump 20 are respectively arranged downstream of the low-temperature molten salt tank 23 and the high-temperature molten salt tank 19 in the molten salt energy storage subsystem provided in the embodiment, for realizing circulation of the molten salt medium in the heat storage and heat release processes. In addition, a heat storage loop is arranged between the outlet of the high-temperature molten salt tank 19 and the inlet of the low-temperature molten salt tank 23, a heat release loop is arranged between the outlet of the low-temperature molten salt tank 23 and the inlet of the high-temperature molten salt tank 19, and the fourth circulating switch 28 and the third circulating switch 27 are respectively arranged on the heat storage loop and the heat release loop. The high-temperature side inlet of the first heat exchanger 18 is connected with the gas turbine body exhaust, the high-temperature side outlet is connected with the waste heat boiler 6, the low-temperature side inlet of the first heat exchanger 18 is connected with the low-temperature molten salt tank 23, and the low-temperature side outlet is connected with the high-temperature molten salt tank 19. The high-temperature side inlet of the second heat exchanger 22 is connected with the high-temperature molten salt tank 19, and the high-temperature side outlet of the second heat exchanger 22 is connected with the low-temperature molten salt tank 23. In the heat storage stage, the first flue gas switch 17, the second flue gas switch 26, the second circulating switch 25 and the fourth circulating switch 28 are all opened. The high-temperature flue gas discharged from the gas turbine turbine 5 is introduced into the first heat exchanger 18 through the bypass flue gas passage, the low-temperature molten salt is pressurized by the first molten salt pump 24 and then introduced into the first heat exchanger 18 from the low-temperature molten salt tank 23 to exchange heat with the high-temperature flue gas, the high-temperature molten salt after being heated is introduced into the high-temperature molten salt tank 19 from the first heat exchanger 18, and a heat storage circulation is formed through the heat storage loop. In the heat release stage, the first circulating switch 21, the third circulating switch 27 and the second heat supply switch 31 are all opened. The high-temperature molten salt is pressurized by the second molten salt pump 20 and then introduced into the second heat exchanger 22 from the high-temperature molten salt tank 19 to exchange heat with water, the water is heated to become heat supply steam, the low-temperature molten salt after being released is introduced into the low-temperature molten salt tank 23 from the second heat exchanger 22, and a heat release circulation is formed through the heat release loop.

[0039] In the embodiment, the molten salt tanks in the molten salt energy storage subsystem are composed of the low-temperature molten salt tank 23 and the high-temperature molten salt tank 19, and a split structure is adopted. The molten salt energy storage subsystem is in two states for heat storage: when the gas-steam combined cycle subsystem is in peak shaving and frequency modulation, if the power grid side electricity demand is lower than the full load power generation amount, part of the flue gas discharged from the gas turbine is introduced into the first heat exchanger 18, and the energy is stored in the high-temperature molten salt tank 19 through circulation between the low-temperature molten salt tank 23 and the high-temperature molten salt tank 19; if the power grid side electricity demand is equal to the full load power generation amount, the flue gas discharged from the gas turbine is introduced into the first heat exchanger 18 after the gas-steam combined cycle subsystem is in peak shaving and frequency modulation, so that the energy is stored in the high-temperature molten salt tank 19.

[0040] The external heat supply side provided by the embodiment includes a heat supply pressurizing pump 32, a user 33, and a return water or water supply channel. Steam can be generated by the extraction channel of the steam turbine body 9 or by the second heat exchanger 22. The selection of steam is controlled by the first heat supply switch 16 and the second heat supply switch 31. The heat supply pressurizing pump 32 provided on the heat supply channel of the power plant side pressurizes the steam to achieve long-distance delivery to the user 33.

[0041] In the heat supply working state of the system: when the gas-steam combined cycle power generation and heat supply system is in peak regulation and frequency modulation, the heat supply steam is generated by the extraction channel of the steam turbine body 9, at which time the first heat supply switch 16 is opened and the second heat supply switch 31 is closed; when the gas-steam combined cycle power generation and heat supply system is not in peak regulation and frequency modulation, the heat supply steam is generated by the second heat exchanger 22 in the molten salt energy storage subsystem to ensure that the gas turbine power plant realizes continuous heat supply throughout the day, at which time the second heat supply switch 31 is opened and the first heat supply switch 16 is closed. The water supply in the heat supply channel is switched according to actual needs. When the system is in peak regulation and frequency modulation, the water supply source of the boiler water supply pump 12 is municipal water, regardless of whether the user 33 is for residential heating or industrial production, to ensure the safe and stable operation of the equipment; when the system is not in peak regulation and frequency modulation, if the user 33 is for residential heating, the water with reduced temperature after being heated for the user 33 is connected to the second heat exchanger 22. If the user 33 is for industrial production, additional municipal water is connected to the second heat exchanger 22 through the heat supply channel to supplement the water consumed by heat supply.

[0042] The gas-steam combined cycle power generation and heat supply system provided by the embodiment generates heat supply steam by the extraction channel of the steam turbine body 9 when in peak regulation and frequency modulation, and generates heat supply steam by the molten salt energy storage subsystem when not in peak regulation and frequency modulation, thereby completely solving the problem of poor economy of continuous heat supply or continuous heat supply of the gas turbine power plant. When the system is in peak regulation and frequency modulation and meets the heat supply demand through low-load operation, the gas turbine body is in a low-efficiency state, has high pollution emissions, has an increased frequency of gas turbine maintenance, and has a high operation cost. When the gas-steam combined cycle power generation and heat supply system is coupled with the molten salt energy storage subsystem to realize heat supply in the non-peak regulation and frequency modulation stage, the gas turbine body can be kept in a high-efficiency state after being started, thereby greatly improving the economy of the gas turbine power plant and effectively reducing the operation and maintenance cost of the gas turbine. Meanwhile, according to the system operation time and heat supply demand, the capacity of the low-temperature molten salt tank 23 and the high-temperature molten salt tank 19 is designed, and the gas-steam combined cycle power generation and heat supply system can realize continuous, stable, and efficient heat supply for twenty-four hours a day on the premise of realizing the basic functions of peak regulation and frequency modulation.

[0043] Obviously, the above embodiments are merely example for clearly illustrating but not limitation to the embodiments. Based on the above description, other different forms of changes or variations can be made by those skilled in the art. Here, all the embodiments need not and can not be enumerated. The obvious changes or variations derived from the above description are still within the protection scope of the present application.

Claims

1. A combined gas and steam cycle power and heat generation system, characterized in that, The application relates to a combined cycle power generation system. The combined cycle power generation system comprises a gas turbine unit and a first generator (1); a steam turbine unit comprising a steam side of a waste heat boiler (6), a steam turbine unit (9), a condenser (11) and a second generator (10) which are sequentially and circularly connected; a molten salt energy storage subsystem comprising a low-temperature molten salt storage unit, a low-temperature side of a first heat exchanger (18), a high-temperature molten salt storage unit and a high-temperature side of a second heat exchanger (22) which are sequentially and circularly connected. The flue gas outlet of the gas turbine unit is connected with the high-temperature side inlet of the first heat exchanger (18), the high-temperature side outlet of the first heat exchanger (18) is connected with the flue gas side inlet of the waste heat boiler (6), and the low-temperature side of the second heat exchanger (22) is connected with a heat supply channel. The steam turbine unit (9) is provided with a steam extraction channel, the steam extraction channel is connected with the heat supply channel, and a heat release branch is further connected between the outlet of the low-temperature molten salt storage unit and the inlet of the high-temperature molten salt storage unit, and a heat storage branch is further connected between the outlet of the high-temperature molten salt storage unit and the inlet of the low-temperature molten salt storage unit. A feedwater channel is connected with the condenser (11), and a boiler feedwater filter (13) is arranged on the feedwater channel. A boiler feedwater pump (12) is arranged on the feedwater channel upstream of the boiler feedwater filter (13).

2. The combined cycle gas and steam power generation and heating system of claim 1, wherein, The flue gas outlet of the gas turbine unit is connected with the flue gas side inlet of the waste heat boiler (6) through a main flue gas channel.

3. The combined cycle gas and steam power and heat generation system of claim 2, wherein, An exhaust device is connected with the flue gas side outlet end of the waste heat boiler (6), and a flue gas treatment device (7) is arranged between the waste heat boiler (6) and the exhaust device.

4. The combined cycle gas and steam power heating system according to any one of claims 1 to 3, characterized in that, A heat supply pressurizing pump (32) is arranged on the heat supply channel.

5. The combined cycle gas and steam power heating system according to any one of claims 1 to 3, characterized in that, An oxygen remover (15) is arranged between the condenser (11) and the waste heat boiler (6).

6. The combined cycle gas and steam power heating system according to any one of claims 1 to 3, characterized in that, A heat supply feedwater filter (30) is arranged on the heat supply channel upstream of the second heat exchanger (22), and a heat supply feedwater pump (29) is arranged upstream of the heat supply feedwater filter (30).

7. The combined cycle gas and steam power heating system according to any of claims 1 to 3, characterized in that, ​ 8. The combined cycle gas and steam power heating system according to any one of claims 1 to 3, characterized in that, ​

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