A coal-fired magnetic fluid supercritical CO2 combined cycle power generation system and method

Abstract

A coal-fired magnetofluid supercritical CO2 combined cycle power generation system and method, the system includes a coal-fired magnetofluid generator, an air preheating system, a waste heat boiler and a supercritical CO2 cycle power generation system; the coal-fired magnetofluid generator of the present invention does not require rotating equipment, has a simple structure, and realizes direct conversion of thermal energy into electrical energy; the present invention can greatly improve the power generation efficiency and operation flexibility of the system by coupling the supercritical CO2 power cycle on the exhaust side of the coal-fired magnetofluid generator, increase the system compactness, and reduce the initial investment and power generation cost of the power station; at the same time, the system has a simple structure and less equipment, which can reduce the difficulty of system control and operation; the present invention uses the waste heat at the cold end of the supercritical CO2 power cycle to preheat the cold oxygen-enriched air, which can reduce the system cold source loss and improve the energy utilization efficiency. The present invention realizes the hierarchical and qualitative utilization of energy.

Description

Technical Field

[0001] The present invention relates to the technical field of coal-fired power generation, and in particular to a coal-fired magnetic fluid supercritical CO2 combined cycle power generation system and method. Background Art

[0002] Coal-fired magnetohydrodynamic power generation technology is a technology that directly converts the heat energy of the high-temperature and high-speed ionized flue gas (plasma) generated by the combustion of coal powder and oxygen-rich air in the burner into electrical energy through a magnetic field. This magnetohydrodynamic generator has no rotating parts, a simple structure, and rapid startup. It is a very promising way of power generation. The intake temperature of general magnetohydrodynamic power generation is 3000K, the exhaust temperature is 2000K, and its thermal efficiency can be as high as 20%. Due to its high exhaust temperature, the exhaust is generally used as a heat source to couple the steam power cycle, and the exhaust heat is further utilized to improve the overall power generation efficiency of the magnetohydrodynamic-steam combined cycle power station. The supercritical CO2 Brayton cycle, as a new type of power cycle, has the advantages of high thermal efficiency, compact structure, flexible operation, and low cost. It can replace the conventional steam power cycle and couple with the exhaust heat source of the magnetohydrodynamic generator, thereby greatly improving its power generation efficiency. The survey found that there is currently a lack of research on the coupling of coal-fired magnetohydrodynamic power generation and supercritical CO2 power cycle power generation, and these problems need to be solved. Summary of the invention

[0003] In order to overcome the deficiencies of the above-mentioned prior art, the purpose of the present invention is to provide a coal-fired magnetofluid supercritical CO2 combined cycle power generation system and method, which greatly improves the overall power generation efficiency of the system by adopting a high-efficiency supercritical CO2 power cycle to utilize the exhaust heat of the coal-fired magnetofluid generator; at the same time, by preheating the oxygen-enriched air at the cold end of the supercritical CO2 power cycle, the system's cold source loss can be reduced and the system's energy utilization efficiency can be improved.

[0004] In order to achieve the above object, the technical solution adopted by the present invention is:

[0005] A coal-fired magnetic fluid supercritical CO2 combined cycle power generation system, comprising a coal-fired magnetic fluid generator, an air preheating system and a supercritical CO2 cycle power generation system, wherein:

[0006] The coal-fired magnetohydrodynamic generator comprises a combustion chamber 1, a nozzle 2, a magnetohydrodynamic power generation channel 3 and a diffuser 4 which are connected in sequence, and also comprises magnets 5 arranged on both sides of the magnetohydrodynamic power generation channel 3 and an inverter converter 6 connected to the electrodes of the magnetohydrodynamic power generation channel 3. Seeds are mixed in the combustion chamber 1; a waste heat boiler is arranged at the tail of the diffuser 4;

[0007] The air preheating system comprises a low-temperature air preheater 7, an air compressor 8, a medium-temperature air preheater 9 and a high-temperature air preheater 10 which are connected in sequence; the outlet of the high-temperature air preheater 10 is connected to the inlet of the combustion chamber 1 of the coal-fired magnetohydrodynamic generator;

[0008] The supercritical CO2 cycle power generation system includes a main compressor 11, an outlet of the main compressor 11, an inlet and outlet of the cold side of a low-temperature reheater 12, an inlet and outlet of the cold side of a high-temperature reheater 13, a superheated gas-cooled wall 14, a superheater 15, a high-pressure turbine 16, a reheated gas-cooled wall 17, a reheater 18, a low-pressure turbine 19, an inlet and outlet of the hot side of a high-temperature reheater 13, an inlet and outlet of the hot side of a low-temperature reheater 12, an inlet and outlet of a hot side of a low-temperature air preheater 7, a precooler 20 and an inlet of the main compressor 11 are connected in sequence; an inlet and outlet of the recompressor 21 are respectively connected to an inlet and outlet of the hot side of a low-temperature air preheater 7 and an inlet and outlet of a cold side of a high-temperature reheater 13; an inlet and outlet of an economizer 22 are respectively connected to an outlet of the main compressor 11 and an inlet of a superheated gas-cooled wall 14.

[0009] The furnace of the waste heat boiler is arranged with a superheated air-cooled wall 14 and a reheated air-cooled wall 17 from bottom to top; the horizontal flue of the waste heat boiler is arranged with a high-temperature air preheater 10, a superheater 15 and a reheater 18 from left to right; the tail vertical flue of the waste heat boiler is arranged with a medium-temperature air preheater 9 and an economizer 22 from top to bottom.

[0010] The cold end of the supercritical CO2 cycle power generation system is equipped with a low-temperature air preheater 7 for heating the cold oxygen-rich air, thereby reducing the cold source loss of the system.

[0011] The flue gas temperature at the outlet of the economizer 22 in the tail vertical flue of the waste heat boiler is 90° C. Part of the low-temperature working fluid is diverted from the outlet of the main compressor 11 to enter the economizer 22, thereby completely recovering the exhaust heat of the waste heat boiler.

[0012] The arrangement of the low-temperature air preheater 7, the medium-temperature air preheater 9 and the high-temperature air preheater 10 in the air preheating system realizes the step-by-step preheating of the oxygen-enriched air and can heat the oxygen-enriched air to 1700-800K.

[0013] The seed is an alkali metal salt, such as K2CO3 or KCl.

[0014] An operation method of a coal-fired magnetic fluid supercritical CO2 combined cycle power generation system, wherein the cold oxygen-enriched air first absorbs heat and heats up in a low-temperature air preheater 7, then is pressurized by an air compressor 8, and then successively absorbs heat in a medium-temperature air preheater 9 and a high-temperature air preheater 10 to become high-temperature oxygen-enriched air of 1700-1800K; the high-temperature oxygen-enriched air and coal powder are mixed with alkali metal salt seeds and burned in a combustion chamber 1 to form high-temperature ionized exhaust gas, which is decompressed and accelerated by a nozzle 2, and then passes through a magnetic fluid power generation channel 3 with a strong magnetic field at high speed, The heat energy is converted into electrical energy, and the electrical energy is converted from direct current to alternating current through the inverter 6 and sent to the power grid; the temperature of the exhaust gas decreases after coming out of the magnetohydrodynamic power generation channel 3, but the temperature is still 2000K~2100K. After being pressurized and decelerated by the diffuser 4, it enters the boiler to heat the supercritical CO2 working fluid; the supercritical CO2 cycle power generation system adopts a single reheating and recompression configuration. After the working fluid fully absorbs the exhaust heat of the magnetohydrodynamic generator in the waste heat boiler, it drives the high-pressure turbine 16 and the low-pressure turbine 19 to do work, thereby realizing the conversion of heat energy into electrical energy.

[0015] Beneficial effects of the present invention:

[0016] 1. The present invention can improve the power generation efficiency of the system and increase the operational flexibility, increase the compactness of the system, and reduce the initial investment and power generation cost of the power station by coupling the supercritical CO2 power cycle on the exhaust side of the coal-fired magnetohydrodynamic generator.

[0017] 2. The system structure of the present invention is simple, with less equipment, which can reduce the difficulty of system control and operation. The coal-fired magnetohydrodynamic generator does not require rotating equipment, has a simple structure, and realizes the direct conversion of thermal energy into electrical energy.

[0018] 3. The present invention utilizes the waste heat at the cold end of the supercritical CO2 power cycle to preheat the cold oxygen-rich air, which can reduce the system's cold source loss, improve energy utilization efficiency, and achieve energy tiered and differentiated utilization. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 This is a schematic diagram of a coal-fired magnetic fluid supercritical CO2 combined cycle power generation system of the present invention. DETAILED DESCRIPTION

[0020] The present invention will be further described in detail below in conjunction with the accompanying drawings.

[0021] like Figure 1 As shown, a coal-fired magnetic fluid supercritical CO2 combined cycle power generation system includes a coal-fired magnetic fluid generator, an air preheating system and a supercritical CO2 cycle power generation system, wherein:

[0022] The coal-fired magnetohydrodynamic generator comprises a combustion chamber 1, a nozzle 2, a magnetohydrodynamic power generation channel 3 and a diffuser 4 which are connected in sequence, and also comprises magnets 5 arranged on both sides of the magnetohydrodynamic power generation channel 3 and an inverter 6 connected to the electrodes of the magnetohydrodynamic power generation channel 3. Seeds are mixed in the combustion chamber 1; a waste heat boiler is arranged at the tail of the diffuser 4;

[0023] The air preheating system comprises a low-temperature air preheater 7, an air compressor 8, a medium-temperature air preheater 9 and a high-temperature air preheater 10 which are connected in sequence; the outlet of the high-temperature air preheater 10 is connected to the inlet of the combustion chamber 1 of the coal-fired magnetohydrodynamic generator;

[0024] The supercritical CO2 cycle power generation system includes a main compressor 11, an outlet of the main compressor 11, an inlet and outlet of the cold side of a low-temperature reheater 12, an inlet and outlet of the cold side of a high-temperature reheater 13, a superheated gas-cooled wall 14, a superheater 15, a high-pressure turbine 16, a reheated gas-cooled wall 17, a reheater 18, a low-pressure turbine 19, an inlet and outlet of the hot side of a high-temperature reheater 13, an inlet and outlet of the hot side of a low-temperature reheater 12, an inlet and outlet of a hot side of a low-temperature air preheater 7, a precooler 20 and an inlet of the main compressor 11 are connected in sequence; the inlet and outlet of the recompressor 21 are respectively connected to the hot side port and inlet of the low-temperature air preheater 7 and the cold side inlet of the high-temperature reheater 13; the inlet and outlet of the economizer 22 are respectively connected to the outlet of the main compressor 11 and the inlet of the superheated gas-cooled wall 14.

[0025] As a preferred embodiment of the present invention, the furnace of the waste heat boiler is arranged with a superheated air-cooled wall 14 and a reheated air-cooled wall 17 in sequence from bottom to top; the horizontal flue of the waste heat boiler is arranged with a high-temperature air preheater 10, a superheater 15 and a reheater 18 in sequence from left to right; the tail vertical flue of the waste heat boiler is arranged with a medium-temperature air preheater 9 and an economizer 22 in sequence from top to bottom.

[0026] As a preferred embodiment of the present invention, the cold end of the supercritical CO2 cycle power generation system is equipped with a low-temperature air preheater 7 for heating the cold oxygen-rich air, thereby reducing the cold source loss of the system.

[0027] As a preferred embodiment of the present invention, the flue gas temperature at the outlet of the economizer 22 in the tail vertical flue of the waste heat boiler is 90°C, and part of the low-temperature working medium is diverted from the outlet of the main compressor 11 to enter the economizer 22, thereby completely recovering the waste heat of the waste heat boiler exhaust.

[0028] As a preferred embodiment of the present invention, the arrangement of the low-temperature air preheater 7, the medium-temperature air preheater 9 and the high-temperature air preheater 10 in the air preheating system realizes the step-by-step preheating of the oxygen-enriched air and can heat the oxygen-enriched air to 1700-1800K.

[0029] As a preferred embodiment of the present invention, the seed is an alkali metal salt, such as K2CO3 or KCl.

[0030] like Figure 1 As shown, an operation method of a coal-fired magnetic fluid supercritical CO2 combined cycle power generation system is shown, the cold oxygen-enriched air first absorbs heat and heats up in the low-temperature air preheater 7, then is pressurized by the air compressor 8, and then absorbs heat in the medium-temperature air preheater 9 and the high-temperature air preheater 10 in turn to become high-temperature oxygen-enriched air of 1700-1800K; the high-temperature oxygen-enriched air and coal powder are mixed with alkali metal salt seeds in the combustion chamber 1 and burned to form high-temperature ionized exhaust gas, which is decompressed and accelerated by the nozzle 2 and passes through the strong magnetic field at a very high speed. The magnetohydrodynamic power generation channel 3 converts thermal energy into electrical energy, and the electrical energy is converted from direct current to alternating current through the inverter converter 6 and sent to the power grid; the exhaust gas has a lower temperature after coming out of the magnetohydrodynamic power generation channel 3, but it is still around 2000K, and after being pressurized and decelerated by the diffuser 4, it enters the boiler to heat the supercritical CO2 working fluid; the supercritical CO2 cycle power generation system adopts a single reheat and recompression configuration, and the working fluid fully absorbs the exhaust heat of the magnetohydrodynamic generator in the waste heat boiler and then drives the high and low pressure turbines to do work, thereby realizing the conversion of thermal energy into electrical energy.

[0031] Coal-fired magnetohydrodynamic generators are based on the law of electromagnetic induction. When ionized flue gas (plasma) passes through a magnetic field at high speed, the charged particles in the flue gas move to the electrodes under the action of the Lorentz force to generate current. However, the conductivity of flue gas is low, and the temperature must be as high as 8000K to be fully ionized, so that the magnetohydrodynamic generator can achieve a high thermoelectric conversion rate. However, coal powder combustion cannot produce such a high temperature, so seed materials such as alkali metal salts are added to the coal powder for combustion to increase the conductivity of the flue gas so that the flue gas can be fully ionized at around 3000K. In addition, the oxidant during combustion uses oxygen-enriched air and is preheated to around 1700K, thereby greatly increasing the flue gas temperature and thus the degree of flue gas ionization. The heat carried by the high-temperature exhaust gas of the magnetohydrodynamic generator is converted into electrical energy through an efficient supercritical CO2 cycle power generation system based on the Brayton cycle principle.

Claims

1. A coal-fired magnetic fluid supercritical CO2 combined cycle power generation system, comprising a coal-fired magnetic fluid generator, an air preheating system and a supercritical CO2 cycle power generation system, characterized in that: in, The coal-fired magnetohydrodynamic generator comprises a combustion chamber (1), a nozzle (2), a magnetohydrodynamic power generation channel (3) and a diffuser (4) which are connected in sequence, and also comprises magnets (5) arranged on both sides of the magnetohydrodynamic power generation channel (3) and an inverter converter (6) connected to the electrodes of the magnetohydrodynamic power generation channel (3); seeds are mixed in the combustion chamber (1); a waste heat boiler is arranged at the tail of the diffuser (4); The air preheating system comprises a low-temperature air preheater (7), an air compressor (8), a medium-temperature air preheater (9) and a high-temperature air preheater (10) which are connected in sequence; the outlet of the high-temperature air preheater (10) is connected to the inlet of the combustion chamber (1) of the coal-fired magnetohydrodynamic generator; The supercritical CO2 cycle power generation system comprises a main compressor (11), an outlet of the main compressor (11), an inlet and outlet of the cold side of a low-temperature reheater (12), an inlet and outlet of the cold side of a high-temperature reheater (13), a superheated gas wall (14), a superheater (15), a high-pressure turbine (16), a reheated gas wall (17), a reheater (18), a low-pressure turbine (19), an inlet and outlet of the hot side of a high-temperature reheater (13), an inlet and outlet of the hot side of a low-temperature reheater (12), an inlet and outlet of the hot side of a low-temperature air preheater (7), a precooler (20) and an inlet of the main compressor (11), which are connected in sequence; an inlet and outlet of the recompressor (21) are respectively connected to an inlet of the hot side of a low-temperature air preheater (7) and an inlet of a cold side of a high-temperature reheater (13); an inlet and outlet of an economizer (22) are respectively connected to an outlet of the main compressor (11) and an inlet of a superheated gas wall (14); The furnace of the waste heat boiler is arranged with a superheated air cooling wall (14) and a reheated air cooling wall (17) in order from bottom to top; the horizontal flue of the waste heat boiler is arranged with a high-temperature air preheater (10), a superheater (15) and a reheater (18) in order from left to right; the tail vertical flue of the waste heat boiler is arranged with a medium-temperature air preheater (9) and an economizer (22) in order from top to bottom; The flue gas temperature at the outlet of the economizer (22) in the tail vertical flue of the waste heat boiler is 90° C. Part of the low-temperature working fluid diverted from the outlet of the main compressor (11) enters the economizer (22), thereby completely recovering the exhaust heat of the waste heat boiler.

2. A coal-fired magnetic fluid supercritical CO2 combined cycle power generation system according to claim 1, characterized in that: The cold end of the supercritical CO2 cycle power generation system is equipped with a low-temperature air preheater (7) for heating cold oxygen-rich air, thereby reducing the cold source loss of the system.

3. A coal-fired magnetic fluid supercritical CO2 combined cycle power generation system according to claim 1, characterized in that: The arrangement of the low-temperature air preheater (7), the medium-temperature air preheater (9) and the high-temperature air preheater (10) in the air preheating system realizes step-by-step preheating of the oxygen-enriched air, and can heat the oxygen-enriched air to 1700-1800K.

4. A coal-fired magnetic fluid supercritical CO2 combined cycle power generation system according to claim 1, characterized in that: The seeds are alkali metal salts.

5. A coal-fired magnetic fluid supercritical CO2 combined cycle power generation system according to claim 4, characterized in that: The alkali metal salt is K2CO3 or KCl.

6. The method for operating a coal-fired magnetic fluid supercritical CO2 combined cycle power generation system according to any one of claims 1 to 5, characterized in that: The cold oxygen-enriched air first absorbs heat and heats up in the low-temperature air preheater (7), then is pressurized by the air compressor (8), and then absorbs heat in the medium-temperature air preheater (9) and the high-temperature air preheater (10) in turn, becoming high-temperature oxygen-enriched air of 1700-1800K; the high-temperature oxygen-enriched air and coal powder are mixed with alkali metal salt seeds and burned in the combustion chamber (1), forming high-temperature ionized exhaust gas, which is decompressed and accelerated by the nozzle (2), and then passes through the magnetohydrodynamic power generation channel (3) with a strong magnetic field at a high speed, converting thermal energy into electrical energy, and the electrical energy is converted from direct current to alternating current through the inverter converter (6) and sent to the power grid; the exhaust gas has a lower temperature after coming out of the magnetohydrodynamic power generation channel (3), but the temperature is still 2000K-2100K, and after being pressurized and decelerated by the diffuser (4), it enters the waste heat boiler to heat the supercritical CO2 working medium; The supercritical CO2 cycle power generation system adopts a one-time reheating and recompression configuration. After the working fluid fully absorbs the exhaust heat of the magnetohydrodynamic generator in the waste heat boiler, it drives the high-pressure turbine (16) and the low-pressure turbine (19) to do work, thereby realizing the conversion of thermal energy into electrical energy.

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