A coal-fired generator set coupled with liquid compressed air energy storage peak regulation system and method

Abstract

The present invention relates to a coal-fired generator set coupled with a liquid compressed air energy storage peak-shaving system and method, comprising a coal-fired generator set, a first clutch-gearbox, a second clutch-gearbox, and a liquid compressed air energy storage system. The low-pressure cylinder in the coal-fired generator set is connected to a first generator in the coal-fired generator set through the first clutch-gearbox, and is connected to an air compressor in the liquid compressed air energy storage system through the second clutch-gearbox; after the air is pressurized in the air compressor, the air enters a refrigeration expander to expand and release heat, and the liquid air and gaseous air are separated in a gas-liquid separation device, and the liquid air is stored in an air storage tank; when the liquid compressed air energy storage system generates electricity externally, the liquid air is pressurized by a booster pump and heated by a heater, and then enters an air expander to expand and do work, thereby driving the second generator to generate electricity.

Description

[Technical field]

[0001] The present invention belongs to the technical field of liquid compressed air energy storage, and relates to an energy storage peak-shaving system and method, in particular to a coal-fired generator set coupled liquid compressed air energy storage peak-shaving system and method. [Background technology]

[0002] With the improvement of people's environmental awareness and the necessity of sustainable development of the global economy, renewable energy generation such as wind power and photovoltaics has developed rapidly in recent years. However, the characteristics of renewable energy such as large peak-to-valley difference and strong volatility during the day and night are in conflict with the requirements of continuous and stable operation of the power grid. Energy storage technology can well bridge the characteristic differences between renewable energy generation and the power grid, and solve the bottleneck that restricts the large-scale utilization of renewable energy.

[0003] Energy storage technologies can be divided into three categories according to their principles: mechanical energy storage (such as pumped storage, compressed air energy storage, etc.), electrochemical energy storage (lead-acid batteries, lithium-ion batteries, etc.) and electromagnetic energy storage. Compressed air energy storage technology has the characteristics of long life, low environmental pollution, and low operation and maintenance costs. It has the potential for large-scale promotion and application, especially liquid compressed air energy storage technology, which achieves liquid storage of compressed air by deep cooling and liquefying air, greatly reducing the storage volume and greatly improving the system energy storage density. However, the overall energy storage efficiency of conventional liquid compressed air energy storage systems is low and the operating costs are high. [Summary of the invention]

[0004] The purpose of the present invention is to solve the above-mentioned problems in the prior art and to propose a coal-fired generator set coupled with liquid compressed air energy storage peak-shaving system and method.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions:

[0006] A coal-fired generator set coupled with liquid compressed air energy storage peak-shaving system, comprising a coal-fired generator set, a first clutch-gearbox, a second clutch-gearbox, and an air compressor, a refrigeration expander, a gas-liquid separation device, an air storage tank, a booster pump, a heater, an air expander, and a second generator connected in sequence;

[0007] The low-pressure cylinder in the coal-fired generator set is connected to the first generator in the coal-fired generator set through a first clutch-gearbox;

[0008] The low-pressure cylinder in the coal-fired generator set is connected to the air compressor via a second clutch-gearbox;

[0009] After the air is pressurized by the air compressor, it enters the refrigeration expander to expand and release heat, and the liquid air and gaseous air are separated in the gas-liquid separation device. The liquid air is stored in the air storage tank, and after being pressurized by the booster pump, it enters the heater to heat up, and then enters the air expander to expand and do work, driving the second generator to generate electricity.

[0010] The present invention is further improved in that:

[0011] The low-pressure cylinder, the first clutch-gearbox and the second clutch-gearbox in the coal-fired generator set are coaxially arranged;

[0012] The coal-fired power generation unit comprises a boiler, a high-pressure cylinder, a medium-pressure cylinder and a low-pressure cylinder connected in sequence;

[0013] The new steam at the boiler outlet enters the high-pressure cylinder to perform work, then returns to the boiler for secondary heating, and then enters the medium-pressure cylinder and the low-pressure cylinder in sequence to expand and perform work.

[0014] It also includes a condenser, a condensate pump, a low-pressure heater group, a feedwater pump and a high-pressure heater group connected in sequence;

[0015] The exhaust steam from the low-pressure cylinder of the coal-fired generator set enters the condenser for condensation, passes through the condensate pump, the low-pressure heater group, the feed water pump, and the high-pressure heater group in sequence for temperature and pressure increase, and then returns to the boiler.

[0016] A method for peak regulation of coal-fired generator sets coupled with liquid compressed air energy storage comprises the following steps:

[0017] When Q1≤60%Q2, the low-pressure cylinder is disconnected from the first generator through the first clutch-gearbox, and the air compressor is driven by the low-pressure cylinder to operate; after the air compressor is pressurized, the air enters the refrigeration expander to expand and release heat, and the liquid air and gaseous air are separated in the gas-liquid separation device, and the liquid air is stored in the air storage tank, completing the liquid air compression energy storage process; wherein Q1 is the grid dispatching load, and Q2 is the rated load of the coal-fired generator set;

[0018] When 60% Q2<Q1≤Q2, the low-pressure cylinder is disconnected from the air compressor through the second clutch-gearbox, and the low-pressure cylinder drives the first generator to generate electricity through the first clutch-gearbox;

[0019] When Q1>Q2, the liquid air stored in the air storage tank is pressurized and heated by the booster pump and air heater in turn, and then enters the air expander to expand and perform work, driving the second generator to generate electricity.

[0020] The further improvement of the above method is:

[0021] The gaseous air separated in the gas-liquid separation device is led back to the air compressor for recompression.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] 1. The present invention proposes a coal-fired generator set coupled with a liquid compressed air energy storage peak-shaving system that can realize low-pressure cylinder cut-off operation. Through a first clutch-gearbox and a second clutch-gearbox, the low-pressure cylinder output is switched between the coal-fired generator set and the liquid compressed air energy storage system, thereby improving the electrical output regulation capability of the coal-fired generator set and improving the overall system operation efficiency.

[0024] 2. In the present invention, the low-pressure cylinder, the first clutch-gearbox and the second clutch-gearbox are coaxially arranged, which is convenient for adjusting the connection or disconnection between the first generator and the low-pressure cylinder, and the air compressor and the low-pressure cylinder.

[0025] 3. The present invention proposes a method for peak-shaving of a coal-fired generator set coupled with liquid compressed air energy storage that can realize low-pressure cylinder removal operation. The first clutch-gearbox and the second clutch-gearbox are used to switch the low-pressure cylinder output between the coal-fired generator set and the liquid compressed air energy storage system. When the grid dispatching load is reduced, the low-pressure cylinder is disconnected from the coal-fired generator set through the first clutch-gearbox, and the low-pressure cylinder output is used to drive the air compressor of the liquid compressed air energy storage system to operate, thereby reducing the unit's power generation output; when the grid dispatching load increases, the low-pressure cylinder output is used to drive the coal-fired generator set generator to operate through the clutch-gearbox group. When the grid dispatching load further increases, the liquid compressed air energy storage system releases energy to the outside to generate electricity, and the liquid air is pressurized and heated and then enters the air expander to do work, driving the second generator to generate electricity, thereby increasing the system's external power supply. Compared with conventional liquid compressed air energy storage systems, this system eliminates the air compression system motor configuration, simplifies the system layout, and reduces system construction investment.

Brief Description of the Drawings

[0026] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments are briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without creative work.

[0027] Figure 1 It is a schematic diagram of an embodiment of a coal-fired power generation unit coupled with a liquid compressed air energy storage peak-shaving system according to the present invention.

[0028] Among them: 1- boiler, 2- high-pressure cylinder, 3- medium-pressure cylinder, 4- low-pressure cylinder, 5- first generator, 6- condenser, 7- condensate pump, 8- low-pressure heater group, 9- feed water pump, 10- high-pressure heater group, 11- first clutch-gear box, 12- second clutch-gear box, 13- air compressor, 14- refrigeration expander, 15- gas-liquid separation device, 16- air storage tank, 17- booster pump, 18- heater, 19- air expander, 20- second generator. [Specific implementation method]

[0029] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings here can be arranged and designed in various different configurations.

[0030] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0031] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, further definition and explanation thereof is not required in subsequent drawings.

[0032] In the description of the embodiments of the present invention, it should be noted that if the terms "upper", "lower", "horizontal", "inner", etc. indicate an orientation or positional relationship based on the orientation or positional relationship shown in the drawings, or the orientation or positional relationship in which the product of the invention is usually placed when in use, it is only for the convenience of describing the present invention and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention. In addition, the terms "first", "second", etc. are only used to distinguish the description, and cannot be understood as indicating or implying relative importance.

[0033] In addition, if the term "horizontal" appears, it does not mean that the component must be absolutely horizontal, but can be slightly tilted. For example, "horizontal" only means that its direction is more horizontal than "vertical", which does not mean that the structure must be completely horizontal, but can be slightly tilted.

[0034] In the description of the embodiments of the present invention, it is also necessary to explain that, unless otherwise clearly specified and limited, the terms "set", "install", "connect", and "connect" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal connection of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0035] The present invention is further described in detail below in conjunction with the accompanying drawings:

[0036] See also Figure 1 The present invention proposes a coal-fired generator set coupled with a liquid compressed air energy storage peak-shaving system that can realize low-pressure cylinder cut-off operation. As a preferred solution, it consists of a boiler 1, a high-pressure cylinder 2, a medium-pressure cylinder 3, a low-pressure cylinder 4, a first generator 5, a condenser 6, a condensate pump 7, a low-pressure heater group 8, a feed water pump 9, a high-pressure heater group 10, a first clutch-gear box 11, a second clutch-gear box 12, an air compressor 13, a refrigeration expander 14, a gas-liquid separation device 15, an air storage tank 16, a booster pump 17, a heater 18, an air expander 19, and a second generator 20.

[0037] The new steam at the outlet of boiler 1 enters the high-pressure cylinder 2 to perform work and then returns to boiler 1 for secondary heating. It then enters the medium-pressure cylinder 3 and the low-pressure cylinder 4 in turn to expand and perform work, driving the first generator 5 to generate electricity. The exhaust steam from the low-pressure cylinder 4 enters the condenser 6 for condensation, and then passes through the condensate pump 7, the low-pressure heater group 8, the feed water pump 9, and the high-pressure heater group 10 to increase the temperature and pressure, and then returns to boiler 1 to complete the steam-water cycle of the coal-fired generator set.

[0038] When the liquid compressed air energy storage system is in energy storage mode, the coal-fired generator set is combined with the air compressor 13 through the second clutch-gearbox 12 to drive the air compressor 13 to operate. The air is pressurized and enters the refrigeration expander 14 to expand and release heat. The liquid air and gaseous air are separated in the gas-liquid separation device 15. The liquid air is stored in the air storage tank 16, and the separated gaseous air returns to the inlet of the air compressor 13 for recompression. The air compression and liquefaction energy storage process of the liquid compressed air energy storage system is completed.

[0039] When the liquid compressed air energy storage system is operating in the energy release and power generation mode, the liquid air at the outlet of the air storage tank 16 is pressurized by the booster pump 17 and then enters the heater 18 for heating, and then enters the air expander 19 for expansion and work, driving the second generator 20 to generate electricity, thus completing the power generation and energy release process of the liquid compressed air energy storage system.

[0040] The present invention proposes a coal-fired generator set coupled with a liquid compressed air energy storage peak-shaving system that can realize low-pressure cylinder cut-off operation, coupling the coal-fired generator set with the liquid compressed air energy storage system, and the air compressor 13 in the liquid compressed air energy storage system is coaxially arranged with the steam turbine set. When the liquid compressed air energy storage system is operating in the energy storage mode, the steam turbine generator set is combined with the air compressor 13 through the second clutch-gearbox 12 to drive the air compressor 13 to operate. When the liquid compressed air energy storage system does not perform air compression energy storage, the second clutch-gearbox 12 is disengaged. Compared with conventional liquid compressed air energy storage systems, the system proposed by the present invention avoids the configuration of the drive motor required for the air compressor, thereby simplifying the system layout and reducing the system construction investment.

[0041] The low-pressure cylinder 4 is arranged between the first generator 5 and the air compressor 13. Through the first clutch-gearbox 11 and the second clutch-gearbox 12, the output of the low-pressure cylinder 4 is switched between the coal-fired generator set and the liquid compressed air energy storage system.

[0042] When Q1≤60%Q2, the low-pressure cylinder 4 is disconnected from the first generator 5 through the first clutch-gearbox 11, and the air compressor 13 is driven by the low-pressure cylinder 4 to operate; after the air compressor 13 is pressurized, the air enters the refrigeration expander 14 to expand and release heat, and the liquid air and gaseous air are separated in the gas-liquid separation device 15, and the liquid air is stored in the air storage tank 16, completing the liquid air compression energy storage process; wherein Q1 is the grid dispatching load, and Q2 is the rated load of the coal-fired generator set;

[0043] When 60% Q2<Q1≤Q2, the low-pressure cylinder 4 is disconnected from the air compressor 13 through the second clutch-gearbox 12, and the low-pressure cylinder 4 drives the first generator 5 to generate electricity through the first clutch-gearbox 11;

[0044] When Q1>Q2, the liquid air stored in the air storage tank 16 is pressurized and heated by the booster pump 17 and the air heater 18, and then enters the air expander 19 to expand and perform work, thereby driving the second generator 20 to generate electricity and meet the load demand of the power grid.

[0045] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for peak-shaving of a coal-fired generator set coupled with liquid compressed air energy storage, the method being based on a coal-fired generator set coupled with liquid compressed air energy storage peak-shaving system, comprising a coal-fired generator set, a first clutch-gearbox (11), a second clutch-gearbox (12), and an air compressor (13), a refrigeration expander (14), a gas-liquid separation device (15), an air storage tank (16), a booster pump (17), a heater (18), an air expander (19) and a second generator (20) connected in sequence; The low-pressure cylinder (4) in the coal-fired generator set is connected to the first generator (5) in the coal-fired generator set via a first clutch-gearbox (11); the low-pressure cylinder (4) in the coal-fired generator set is connected to the air compressor (13) via a second clutch-gearbox (12); the low-pressure cylinder (4) in the coal-fired generator set, the first clutch-gearbox (11) and the second clutch-gearbox (12) are coaxially arranged; The coal-fired power generation unit comprises a boiler (1), a high-pressure cylinder (2), a medium-pressure cylinder (3) and a low-pressure cylinder (4) which are connected in sequence; new steam from the outlet of the boiler (1) enters the high-pressure cylinder (2) to perform work, then returns to the boiler (1) for secondary heating, and then enters the medium-pressure cylinder (3) and the low-pressure cylinder (4) in sequence to expand and perform work; The coal-fired power generation unit further comprises a condenser (6), a condensate pump (7), a low-pressure heater group (8), a feed water pump (9) and a high-pressure heater group (10) which are connected in sequence; exhaust steam from the low-pressure cylinder (4) of the coal-fired power generation unit enters the condenser (6) for condensation, and then passes through the condensate pump (7), the low-pressure heater group (8), the feed water pump (9) and the high-pressure heater group (10) in sequence for temperature and pressure increase before returning to the boiler (1); After the air is pressurized in the air compressor (13), the air enters the refrigeration expander (14) to expand and release heat, and the liquid air and the gaseous air are separated in the gas-liquid separation device (15). The liquid air is stored in the air storage tank (16), and after being pressurized by the booster pump (17), the air enters the heater (18) to increase the temperature, and then enters the air expander (19) to expand and perform work, thereby driving the second generator (20) to generate electricity; It is characterized in that The method comprises the following steps: When Q1≤60%Q2, the low-pressure cylinder (4) is disconnected from the first generator (5) through the first clutch-gearbox (11), and the air compressor (13) is driven to operate through the low-pressure cylinder (4); after the air is pressurized in the air compressor (13), the air enters the refrigeration expander (14) to expand and release heat, and the liquid air and gaseous air are separated in the gas-liquid separation device (15), and the liquid air is stored in the air storage tank (16), completing the liquid air compression energy storage process; wherein Q1 is the grid dispatching load, and Q2 is the rated load of the coal-fired generator set; When 60%Q2<Q1≤Q2, the low-pressure cylinder (4) is disconnected from the air compressor (13) through the second clutch-gearbox (12), and the low-pressure cylinder (4) drives the first generator (5) to generate electricity through the first clutch-gearbox (11); When Q1>Q2, the liquid air stored in the air storage tank (16) is pressurized and heated by the booster pump (17) and the air heater (18) in sequence, and then enters the air expander (19) to expand and perform work, thereby driving the second generator (20) to generate electricity.

2. The method for peak-shaving of coal-fired power generation units coupled with liquid compressed air energy storage according to claim 1, characterized in that: The gaseous air separated in the gas-liquid separation device (15) is led back to the air compressor (13) for re-compression.

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