A supplementary combustion compressed air energy storage system based on premixed combustion

Abstract

The present invention discloses a supplementary combustion type compressed air energy storage system based on a premixed combustion mode, comprising a connected compressed air storage unit and a compressed air energy release unit, the compressed air energy release unit comprising at least two stages of connected turbines, namely an air turbine and a flue gas turbine, the air inlet end of the air turbine is connected in series with a second heat exchanger for heating compressed air, the air inlet end of the flue gas turbine is connected in series with a first supplementary combustion burner, a third heat exchanger is connected between the first supplementary combustion burner and the air turbine, the third heat exchanger is used to heat the compressed air entering the first supplementary combustion burner, and the heat exchange medium of the second heat exchanger and the third heat exchanger is provided by the exhaust gas of the flue gas turbine; the present invention is a supplementary combustion type energy storage system with compressed air as the medium, which improves the electric energy storage efficiency by stepwise utilization of flue gas waste heat; based on the core equipment in the relatively mature type selection system, the difficulty and risk of research and development are reduced.

Description

Technical Field

[0001] The invention relates to a supplementary combustion type compressed air energy storage system based on a premixed combustion mode, belonging to the technical field of electric energy storage. Background Art

[0002] Compressed air energy storage: During periods of low grid load, air is compressed by a compressor, and electrical energy is converted into compressed potential energy for storage, and the compressed air is transported to rock caves, abandoned salt caves, abandoned mines or other pressure vessels. During periods of high grid load, high-pressure gas in the gas storage is released, heated by a combustion chamber or heat exchanger, raised to a certain temperature and sent to a turbo expander, which converts the thermal potential energy of the compressed air into mechanical work output of the expander, driving the generator to generate electricity.

[0003] According to the different heat sources of the system, compressed air energy storage systems can be divided into: compressed air energy storage systems without heat sources, compressed air energy storage systems with heat storage, and supplementary combustion compressed air energy storage systems. Among them, the compressed air system without heat sources has a simple structure, but the system energy density and efficiency are low, and it is only used in micro-sized systems. The heat storage type compressed air energy storage system can be divided into two types: storing compression heat and storing external heat sources. Since the temperature of the compression heat and the external heat source determines the upper limit of the temperature of the air before the expansion turbine, it limits the compressed air's external work capacity, that is, the scale of energy storage. At the same time, large-capacity heat storage devices also greatly increase the cost of energy storage power stations.

[0004] The supplementary combustion compressed air system is based on gas turbine technology, but the compressor and expansion turbine do not work at the same time. When storing energy, the electric energy is stored in the air storage chamber, and when releasing energy, the compressed air is released and enters the combustion chamber to burn the fuel to drive the expansion turbine. Due to the reduction of compressor energy consumption, the output power consumed by the compression section can be saved compared with similar gas turbine power generation systems. The burner in the high pressure environment before the expansion turbine is based on gas turbine technology, and can adopt two different combustion modes: diffusion combustion and premixed combustion: diffusion combustion refers to the combustion in which the mixed diffusion factor plays a controlling role. The fuel and air are mixed and burned after being sent to the combustion chamber separately. The equivalence ratio at the combustion flame surface is 1, the combustion temperature is high, the flame stability is good, but the NOx emission is high. Premixed combustion refers to the fuel and air being fully mixed into a combustible mixture in the fuel nozzle premixer before combustion, and then ignited and burned in the combustion chamber. The combustion temperature can be reduced by controlling the mixing ratio, thereby reducing the amount of NOx generated, but the equivalence ratio at the flame surface is less than 1, the combustion flame surface temperature is low, and the combustion stability is poor. Summary of the invention

[0005] The purpose of the present invention is to overcome the deficiencies in the prior art and to provide a supplementary combustion type compressed air energy storage system based on premixed combustion, which uses compressed air with supplementary combustion as the working medium, realizes the storage and conversion of larger-scale electric energy, and plays a role in regulating the "peak shaving and valley filling" of the power grid load.

[0006] To achieve the above object, the present invention is implemented by adopting the following technical solutions:

[0007] A supplementary combustion type compressed air energy release system based on premixed combustion mode, comprising:

[0008] A compressed air storage unit and a compressed air energy release unit connected to each other;

[0009] The compressed air energy release unit comprises at least two turbines connected to the generator, namely an air turbine and a flue gas turbine;

[0010] The air inlet end of the air turbine is connected in series with a second heat exchanger for heating the compressed air;

[0011] The air inlet end of the flue gas turbine is connected in series with a first supplementary combustion burner, and a third heat exchanger is connected between the first supplementary combustion burner and the air turbine, and the third heat exchanger is used to heat the compressed air entering the first supplementary combustion burner so that its temperature is greater than the temperature required for stable combustion in the premixed combustion mode;

[0012] The heat exchange medium of the second heat exchanger and the third heat exchanger is provided by exhaust gas of a flue gas turbine.

[0013] In this technical solution, the compressed air drawn out from the compressed air storage unit undergoes multiple heat exchange, expansion work and supplementary combustion links. Based on mature gas turbine models, it fully utilizes the exhaust waste heat of the flue gas turbine to form a self-coupled cascade compressed air energy release and power generation system.

[0014] Furthermore, the inlet of the second heat exchanger for circulating the heat exchange medium is connected to the second supplementary combustion burner for heating the heat exchange medium entering the second heat exchanger, and the temperature of the heat exchange medium entering the second supplementary combustion burner is greater than the temperature required for stable combustion in the premixed combustion mode, so that the heat exchange medium can ensure stable combustion after entering the second supplementary combustion burner;

[0015] The inlet of the third heat exchanger for circulating the heat exchange medium is connected to the third supplementary combustion burner, which is used to heat the heat exchange medium entering the third heat exchanger. The temperature of the heat exchange medium entering the third supplementary combustion burner is greater than the temperature required for stable combustion in the premixed combustion mode, so that stable combustion can be guaranteed after the heat exchange medium enters the second supplementary combustion burner.

[0016] Furthermore, the air inlet of the second heat exchanger is connected to the first heat exchanger for preheating compressed air. The heat exchange medium of the first heat exchanger is provided by exhaust gas of the flue gas turbine, making full use of the waste heat of the flue gas.

[0017] Furthermore, the inlets and outlets of the first heat exchanger, the second heat exchanger and the third heat exchanger for circulating the heat exchange medium are sealed with isolation dampers and insulation devices, which can maintain the heat exchangers in a warm state for a long time to meet the requirements of rapid startup of the compressed air energy storage system under frequent start-stop conditions.

[0018] Further, the compressed air storage unit includes an air compression system, an air cooling system and an air storage system;

[0019] The air cooling system comprises a cooling device and a fourth heat exchanger through which a cooling medium flows. The fourth heat exchanger is arranged in the air compression system and is used to cool the compressed air. The cooling medium is heated up by heat exchange with the compressed air in the fourth heat exchanger and then enters the cooling device for cooling. After being cooled down, the cooling medium returns to the fourth heat exchanger to form a cooling cycle.

[0020] The air compression system is in communication with an air storage system, and the compressed air output by the air compression system is stored in the air storage system.

[0021] Furthermore, the air compression system includes multiple sections of air compressors connected in series, and a fourth heat exchanger is connected in series at the outlet of each section of the air compressor to cool the high-temperature compressed gas after compression, thereby reducing the material requirements and manufacturing difficulty of the rear-stage air compressor, while reducing the volume flow rate of the compressed air and reducing the power consumption of the air compressor.

[0022] Furthermore, the first supplementary combustion burner, the second supplementary combustion burner and the third supplementary combustion burner are all premixed burners, which can control the mixing ratio of fuel and air to make the combustion temperature lower than the theoretical combustion temperature, thereby reducing the amount of NOx generated.

[0023] Compared with the prior art, the present invention has the following beneficial effects:

[0024] The present invention uses compressed air with supplementary combustion as the working medium to achieve storage and conversion of larger-scale electric energy, and plays a role in regulating the "peak shaving and valley filling" of power grid load;

[0025] The compressed air of the present invention is first subjected to supplementary combustion before entering the flue gas turbine. Before the supplementary combustion, the compressed air is first heated to the stable combustion temperature required by the premixed combustion mode, which is conducive to the stable combustion of the mixture of compressed air and supplementary combustion fuel in the supplementary combustion burner.

[0026] The present invention utilizes the waste heat of flue gas released by the combustion of a mixture of supplementary combustion fuel and compressed air to increase the expansion capacity of compressed air in the supplementary combustion compressed air energy storage system, which can effectively improve the storage efficiency of electric energy;

[0027] The selection of the flue gas turbine and burner of the present invention is based on the currently more mature gas turbine models and premixed combustion methods, which reduces the difficulty and risk of the research and development of the core equipment of the system, shortens the research and development cycle, and can effectively control the emission concentration of pollutants such as NOx. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 It is a structural schematic diagram of a supplementary combustion type compressed air energy storage system based on a premixed combustion method provided by the present invention.

[0029] In the figure: 1. air compressor; 2. electric motor; 3. fourth heat exchanger; 4. cooling device; 5. air storage system; 6. first heat exchanger; 7. second heat exchanger; 8. air turbine; 9. generator; 10. third heat exchanger; 11. first supplementary burner; 12. flue gas turbine; 14. second supplementary burner; 15. third supplementary burner. DETAILED DESCRIPTION

[0030] The present invention will be further described below in conjunction with the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present invention, and cannot be used to limit the protection scope of the present invention.

[0031] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying 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 limiting the present invention. In addition, the terms "first", "second", and the like are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, features defined as "first", "second", and the like may explicitly or implicitly include one or more of the features. In the description of the present invention, unless otherwise specified, "multiple" means two or more.

[0032] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" 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 communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood by specific circumstances.

[0033] The embodiment of the present invention provides a supplementary combustion type compressed air energy storage system based on premixed combustion mode, such as Figure 1 As shown, it includes a gas-connected compressed air storage unit and a compressed air energy release unit. The compressed air storage unit compresses, cools, and stores the air during the off-peak period of electricity consumption, and then transmits it to the compressed air energy release unit. The compressed air energy release unit releases the compressed air and converts it into mechanical energy to generate electricity during the peak period of electricity consumption, thereby realizing large-scale storage and conversion of electric energy, and playing a regulatory role in "peak shaving and valley filling" of the power grid load.

[0034] The compressed air energy release unit comprises an air turbine 8 and a flue gas turbine 12 which are gas-connected, and the output ends of the air turbine 8 and the flue gas turbine 12 are both drivingly connected to a generator 9.

[0035] The air turbine 8 is connected to the compressed air storage unit, receives the compressed air input from the compressed air storage unit, expands and performs work, and drives the generator 9 to generate electricity. The air inlet end of the air turbine 8 is connected in series with a second heat exchanger 7, which is used to heat the compressed air before the compressed air expands and performs work, so that the compressed air has and improves the ability to expand and perform work.

[0036] The air inlet end of the flue gas turbine 12 is connected in series with a first supplementary combustion burner 11. The compressed air after expansion and work by the air turbine 8 first enters the first supplementary combustion burner 11 before entering the flue gas turbine 12. Fuel is passed through the first supplementary combustion burner 11. The compressed air and fuel in the first supplementary combustion burner 11 are premixed and ignited. The high-temperature flue gas formed by the combustion is passed into the flue gas turbine 12 to expand and do work, thereby driving the generator 9 to generate electricity.

[0037] The air inlet of the first supplementary combustion burner 11 is provided with a third heat exchanger 10 for heating the compressed air entering the first supplementary combustion burner 11 so that its temperature is greater than the stable combustion temperature required by the premixed combustion mode to ensure the stability of its combustion.

[0038] The compressed air inlet of the second heat exchanger 7 is connected in series with the first heat exchanger 6 for preheating the normal temperature compressed air input from the compressed air storage unit by using a lower grade heat source.

[0039] The first heat exchanger 6, the second heat exchanger 7 and the third heat exchanger 10 are all flue gas-compressed air heat exchangers, and their heat sources are all provided by the flue gas produced after the flue gas turbine 12 expands and does work. The outlet end of the flue gas turbine 12 is connected in series with the second heat exchanger 7, the third heat exchanger 10 and the flue gas side of the first heat exchanger 6 in sequence.

[0040] A second supplementary combustion burner 14 is connected in series in front of the flue gas inlet of the second heat exchanger 7. The heat exchanged flue gas is heated and heated in the second supplementary combustion burner 14 before entering the second heat exchanger 7, so that the compressed air can obtain higher heat when exchanging heat with the compressed air in the second heat exchanger 7, thereby improving the working capacity of the compressed air at the outlet of the second heat exchanger 7 and ensuring that the flue gas temperature at the outlet of the second heat exchanger 7 meets the stable combustion temperature required for the premixed combustion mode in the third supplementary combustion burner 15.

[0041] A third supplementary combustion burner 15 is connected in series at the inlet of the flue gas side of the third heat exchanger 10, which is used to heat the heat exchange flue gas entering the third heat exchanger 10, so that the heat exchange flue gas in the third heat exchanger 10 obtains a higher heat exchange temperature, so as to ensure that the heat exchange flue gas entering the third heat exchanger 10 can heat the compressed air flowing through the third heat exchanger 10 and about to enter the first supplementary combustion burner 11 to a temperature greater than the temperature required for stable combustion in the premixed combustion mode, so as to ensure the stability of the supplementary combustion of the compressed air.

[0042] The flue gas side inlet of the first heat exchanger 6 receives the heat exchange flue gas flowing out of the third heat exchanger 10, and after preheating the normal temperature compressed air output by the compressed air storage system 5, it is passed into the atmosphere.

[0043] After being drawn out from the compressed air storage unit, the room temperature compressed air is preheated through the first heat exchanger 6 and then passed into the second heat exchanger 7 for further heating, and then enters the air turbine 8 to expand and do work, driving the generator 9 to generate electricity. The compressed air after expansion and cooling enters the third heat exchanger 10, and after being heated to a temperature that can meet the stable combustion of the premixed fuel, enters the first supplementary combustion burner 11 for combustion and temperature increase. The flue gas generated by the supplementary combustion enters the flue gas turbine 12 to expand and do work, driving the generator 9 to generate electricity. The temperature of the flue gas after the expansion and work still meets the stable combustion conditions of the premixed combustion, and the flue gas after the expansion and work can be passed into the second supplementary combustion burner 14 for supplementary combustion and temperature increase. After being heated, the flue gas is passed into the heat exchange flue gas channel of the second heat exchanger 7 to heat the compressed air that is about to enter the air turbine 8, and is led out of the second heat exchanger 7 before the temperature drops to the stable combustion temperature of premixed combustion, and then passed into the third supplementary combustion burner 11 for supplementary combustion and heating. After being heated, it is passed into the heat exchange flue gas channel of the third heat exchanger 10 to heat the compressed air that is about to enter the first supplementary combustion burner 11 to the stable combustion temperature of premixed combustion. The flue gas flowing out of the heat exchange flue gas channel of the third heat exchanger 10 still has a relatively high temperature, and is passed into the heat exchange flue gas channel of the first heat exchanger 6 to preheat the compressed air at room temperature connected to the compressed air storage unit, and then discharged into the atmosphere.

[0044] In the embodiment, the supplementary fuel of each supplementary burner is natural gas. To meet the stable combustion of the premixed supplementary burner, the inlet compressed air temperature of each supplementary burner is 417°C, and the pressure is less than the pressure of the natural gas supplement. To avoid the upgrading of the materials of each flue gas-compressed air heat exchanger, the outlet flue gas temperature of the second supplementary burner 14 is set to 600°C, and the outlet flue gas temperature of the third supplementary burner 15 is set to 467°C.

[0045] Sealed isolation dampers are provided at the inlets and outlets of the first heat exchanger 6, the second heat exchanger 7 and the third heat exchanger 10 for circulating the heat exchange flue gas and compressed air, and effective insulation devices are provided, which can utilize the waste heat of the heat exchange medium to maintain the temperature of the heat exchanger for a long time and reduce the startup time of the compressed air energy release unit under frequent start-stop conditions.

[0046] The number of compressed air energy release units provided by the present invention can be set according to work requirements. The compressed air energy release unit provided by the present invention uses compressed air with supplementary combustion as the working medium to achieve large-scale storage and conversion of electric energy, play a role in "peak shaving and valley filling" of the power grid load, and cascade utilize the flue gas waste heat released after the combustion of gas fuel to improve the efficiency of electric energy storage. At the same time, the selection of the flue gas turbine 12 and the burner is based on the currently more mature gas turbine models and premixed combustion methods, which reduces the difficulty and risk of the research and development of the core equipment of the system, and can effectively control the emission concentration of pollutants such as NOx.

[0047] The compressed air storage unit includes an air compression system, an air cooling system and an air storage system 5 . During the low electricity consumption period, the air storage system 5 absorbs and compresses external air and stores it in the air storage system 5 .

[0048] The air cooling system includes a cooling device 4 and a fourth heat exchanger 3 through which a cooling medium flows. The fourth heat exchanger 3 is arranged in the air compression system and is used to cool the air during the air compression process. The cooling medium exchanges heat with the compressed air in the fourth heat exchanger 3 and heats up before entering the cooling device 4 for cooling. The cooling medium after cooling is passed into the fourth heat exchanger 3 to form a cooling cycle. In this embodiment, the cooling device 4 is a cooling tower.

[0049] The air compression system includes a plurality of air compressors 1 connected in series, each of which is powered by an electric motor 2. The type, number and connection mode of the air compressors 1 can be specifically set according to air compression requirements.

[0050] The present embodiment preferably uses a three-stage cascade staged compression scheme, the outlet pressure of the first-stage air compressor 1 is 0.29 MPa.a, an axial flow compressor is selected, an inter-stage cooling method is adopted, and the outlet exhaust temperature is 150°C.

[0051] The second and third stage air compressors 1 are centrifugal compressors, and adopt inter-stage cooling and intra-stage cooling. The outlet pressure of the compressed air of the third stage air compressor 1 is the air storage pressure, and the temperature of the air does not exceed 150°C during the compression process.

[0052] Inter-stage cooling method: The fourth heat exchanger 3 is connected in series to the outlet of the air compressor 1, and the high-temperature air compressed by the air compressor 1 is passed into the fourth heat exchanger 3 for heat exchange cooling. The inter-stage cooling method makes the compression process of the air compressor 1 closer to adiabatic compression. The cooling medium with a sufficiently high temperature during heat exchange in the heat exchanger can be used to supply external heat load users.

[0053] In-segment cooling method: The air compressor 1 adopting the in-segment cooling method includes a plurality of compression stages connected in series. The plurality of compression stages are divided into a plurality of cooling sections according to the control requirements of the thermal system for the working medium temperature. A fourth heat exchanger 3 for heat exchange cooling is connected in series between each cooling section. The in-segment cooling method makes the compression process of the air compressor 1 closer to isothermal compression, reduces the energy consumed by the air compressor 1, and at the same time reduces the working medium temperature in the air compressor 1, reduces material requirements and manufacturing difficulty.

[0054] The air storage system 5 is used to receive and store compressed air that has been compressed and cooled by the air compression system and the air cooling system. In the embodiment, the storage pressure of the compressed air is 12 MPa-14 MPa, and the flow rate is 400,000 cubic meters per hour. During power generation, the compressed air is delivered to the compressed air energy release unit at a pressure of 12 MPa.a and 40°C.

[0055] The air storage system 5 of this embodiment includes an underground salt cavern. The underground salt cavern for storing compressed air has the characteristics of large gas storage capacity, high gas storage pressure, high stability, good sealing, and small footprint. At the same time, it has little impact on the environment, low construction cost, low operation and maintenance cost, wide distribution and mature technology, which can provide excellent conditions for the large-scale, safe and efficient construction and operation of compressed air energy storage systems.

[0056] The fourth heat exchanger 3 is designed in number and series-parallel connection mode according to the heat exchange capacity. The fourth heat exchanger 3 is an air cooler.

[0057] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the technical principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A supplementary combustion type compressed air energy storage system based on premixed combustion, characterized in that: It includes a compressed air storage unit and a compressed air energy release unit which are connected to each other; The compressed air energy release unit comprises at least two turbines connected to the generator (9), namely an air turbine (8) and a flue gas turbine (12); The air inlet end of the air turbine (8) is connected in series with a second heat exchanger (7) for heating compressed air; The air inlet end of the flue gas turbine (12) is connected in series with a first supplementary combustion burner (11), and a third heat exchanger (10) is connected between the first supplementary combustion burner (11) and the air turbine (8), and the third heat exchanger (10) is used to heat the compressed air entering the first supplementary combustion burner (11) so that its temperature is greater than the temperature required for stable combustion in a premixed combustion mode; The heat exchange medium of the second heat exchanger (7) and the third heat exchanger (10) is provided by exhaust gas of the flue gas turbine (12).

2. A supplementary combustion type compressed air energy storage system based on premixed combustion according to claim 1, characterized in that: The inlet of the second heat exchanger (7) for circulating the heat exchange medium is connected to a second supplementary combustion burner (14) for heating the heat exchange medium entering the second heat exchanger (7), and the temperature of the heat exchange medium entering the second supplementary combustion burner (14) is greater than the temperature required for stable combustion in a premixed combustion mode; The inlet of the third heat exchanger (10) for circulating the heat exchange medium is connected to a third supplementary combustion burner (15) for heating the heat exchange medium entering the third heat exchanger (10), and the temperature of the heat exchange medium entering the third supplementary combustion burner (15) is greater than the temperature required for stable combustion in a premixed combustion mode.

3. A premixed combustion type compressed air energy storage system according to claim 1, characterized in that: The air inlet of the second heat exchanger (7) is connected to the first heat exchanger (6) for preheating compressed air. The heat exchange medium of the first heat exchanger (6) is provided by exhaust gas of the flue gas turbine (12).

4. A premixed combustion type compressed air energy storage system according to claim 3, characterized in that: The inlets and outlets of the first heat exchanger (6), the second heat exchanger (7) and the third heat exchanger (10) for circulating the heat exchange medium are all sealed with isolation dampers and heat preservation devices.

5. The post-combustion type compressed air energy storage system based on premixed combustion according to claim 1, characterized in that: The compressed air storage unit comprises an air compression system, an air cooling system and an air storage system (5); The air cooling system comprises a cooling device (4) through which a cooling medium flows and a fourth heat exchanger (3); the fourth heat exchanger (3) is arranged in the air compression system and is used to cool the compressed air; the cooling medium exchanges heat with the compressed air in the fourth heat exchanger (3) and heats up before entering the cooling device (4) for cooling; and after cooling down, it returns to the fourth heat exchanger (3), thereby forming a cooling cycle; The air compression system is connected to an air storage system (5), and the compressed air output by the air compression system is stored in the air storage system (5).

6. A supplementary combustion type compressed air energy storage system based on premixed combustion according to claim 5, characterized in that: The air compression system comprises a plurality of air compressors (1) connected in series, and a fourth heat exchanger (3) is connected in series at the outlet of each air compressor (1) to cool the high-temperature compressed gas after compression.

7. A premixed combustion type compressed air energy storage system according to claim 2, characterized in that ； The first supplementary combustion burner (11), the second supplementary combustion burner (14) and the third supplementary combustion burner (15) are all premixing burners.

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