阅读说明：本技术 一种燃煤磁流体超临界co2联合循环发电系统及方法 (Coal-fired magnetic fluid supercritical CO2Combined cycle power generation system and method ) 是由 张旭伟 李红智 顾正萌 杨玉 乔永强 张天宇 白文刚 于 2021-08-11 设计创作，主要内容包括：一种燃煤磁流体超临界CO2联合循环发电系统及方法,该系统包括燃煤磁流体发电机、空气预热系统、余热锅炉和超临界CO2循环发电系统；本发明燃煤磁流体发电机无需旋转设备,结构简单,实现了热能到电能的直接转化；本发明通过在燃煤磁流体发电机排气侧耦合超临界CO2动力循环,可以大幅提高系统发电效率及运行灵活,增加系统紧凑程度,降低电站初投资及发电成本；同时,系统结构简单,设备较少,可以降低系统控制运行难度；本发明利用超临界CO2动力循环冷端余热预热冷的富氧空气,可以减少系统冷源损失,提高能量利用效率。本发明实现能量梯级分质利用。(A coal-fired magnetofluid supercritical CO2 combined cycle power generation system and a method thereof are provided, wherein the system comprises a coal-fired magnetofluid power generator, an air preheating system, a waste heat boiler and a supercritical CO2 cycle power generation system; the coal-fired magnetohydrodynamic generator does not need rotating equipment, has a simple structure, and realizes the direct conversion from heat energy to electric energy; according to the invention, by coupling the supercritical CO2 power cycle on the exhaust side of the coal-fired magnetohydrodynamic generator, the power generation efficiency and the operation flexibility of the system can be greatly improved, the system compactness is increased, and the initial investment and the power generation cost of a power station are reduced; meanwhile, the system has a simple structure and less equipment, and can reduce the difficulty of system control and operation; the invention utilizes the waste heat of the supercritical CO2 power cycle cold end to preheat the cold oxygen-enriched air, thereby reducing the cold source loss of the system and improving the energy utilization efficiency. The invention realizes the energy gradient quality-based utilization.)

1. A coal-fired magnetofluid supercritical CO2 combined cycle power generation system comprises a coal-fired magnetofluid power generator, an air preheating system and a supercritical CO2 cycle power generation system, and is characterized in that,

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 sequentially communicated, and further comprises magnets (5) arranged on two sides of the magnetohydrodynamic power generation channel (3) and an inverter converter (6) connected with electrodes of the magnetohydrodynamic power generation channel (3), wherein seeds are mixed in the combustion chamber (1); the tail part of the diffuser (4) is provided with a waste heat boiler;

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 communicated in sequence; the outlet of the high-temperature air preheater (10) is communicated with the inlet of a combustion chamber (1) of the coal-fired magnetohydrodynamic generator;

the supercritical CO2 cycle power generation system comprises a main compressor (11), wherein an outlet of the main compressor (11), a cold side inlet and outlet of a low-temperature regenerator (12), a cold side inlet and outlet of a high-temperature regenerator (13), a superheated air cooling wall (14), a superheater (15), a high-pressure turbine (16), a reheated air cooling wall (17), a reheater (18), a low-pressure turbine (19), a hot side inlet and outlet of the high-temperature regenerator (13), a hot side inlet and outlet of the low-temperature regenerator (12), a hot side inlet and outlet of a low-temperature air preheater (7), and inlets of a precooler (20) and the main compressor (11) are sequentially communicated; an inlet and an outlet of the recompressor (21) are respectively communicated with an inlet at the hot side of the low-temperature air preheater (7) and an inlet at the cold side of the high-temperature regenerator (13); the inlet and the outlet of the economizer (22) are respectively communicated with the outlet of the main compressor (11) and the inlet of the superheated air-cooled wall (14).

2. The coal-fired magnetohydrodynamic supercritical CO2 combined cycle power generation system according to claim 1, wherein a furnace of the waste heat boiler is sequentially provided with a superheated air-cooled wall (14) and a reheated air-cooled wall (17) from bottom to top; a high-temperature air preheater (10), a superheater (15) and a reheater (18) are sequentially arranged in a horizontal flue of the waste heat boiler from left to right; the tail vertical flue of the waste heat boiler is sequentially provided with a medium-temperature air preheater (9) and an economizer (22) from top to bottom.

3. The coal-fired magnetohydrodynamic supercritical CO2 combined cycle power generation system according to claim 1, wherein the cold end of the supercritical CO2 combined cycle power generation system reduces system cold source loss by arranging a low temperature air preheater (7) for heating cold oxygen-enriched air.

4. The coal-fired magnetofluid supercritical CO2 combined cycle power generation system according to claim 1, wherein the temperature of flue gas at the outlet of the economizer (22) in the tail vertical flue of the waste heat boiler is 90 ℃, and part of low-temperature working medium is shunted to the outlet of the main compressor (11) and enters the economizer (22), so that the exhaust gas waste heat of the waste heat boiler is completely recovered.

5. The coal-fired magnetic fluid supercritical CO2 combined cycle power generation system according to claim 1, wherein 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 preheating of oxygen-enriched air, and can heat the oxygen-enriched air to 1700-1800K.

6. The coal-fired magnetohydrodynamic supercritical CO2 combined cycle power generation system of claim 1, wherein the seed is an alkali metal salt.

7. The coal-fired magnetohydrodynamic supercritical CO2 combined cycle power generation system of claim 1, wherein the alkali metal salt is K2CO3 or KCl.

8. The operation method of the coal-fired magnetic fluid supercritical CO2 combined cycle power generation system according to any one of claims 1 to 7, characterized in that cold oxygen-enriched air firstly absorbs heat in a low-temperature air preheater (7) to raise the temperature, then the cold oxygen-enriched air is boosted by an air compressor (8), and then the cold oxygen-enriched air absorbs heat in a medium-temperature air preheater (9) and a high-temperature air preheater (10) in sequence to become 1700-1800K high-temperature oxygen-enriched air; after the high-temperature oxygen-enriched air and the coal powder are mixed with alkali metal salt seeds in the combustion chamber (1) and combusted, high-temperature ionized exhaust is formed, after the pressure and the speed are reduced and increased through the nozzle (2), heat energy is converted into electric energy through a magnetofluid power generation channel (3) of a strong magnetic field at high speed, and the electric energy converts direct current into alternating current through an inverter converter (6) and then is sent to a power grid; the temperature of the exhaust gas is reduced after the exhaust gas comes out of the magnetofluid power generation channel (3), but the temperature is still 2000K-2100K, and the exhaust gas enters a waste heat boiler to heat a supercritical CO2 working medium after being pressurized and decelerated by a diffuser (4); the supercritical CO2 circulating power generation system adopts a once-reheat recompression configuration, and the working medium fully absorbs the exhaust heat of the magnetohydrodynamic generator in the waste heat boiler and then pushes the high-pressure turbine (16) and the low-pressure turbine (19) to do work, so that the conversion from heat energy to electric energy is realized.

Technical Field

The invention relates to the technical field of coal-fired power generation, in particular to a coal-fired magnetofluid supercritical CO2 combined cycle power generation system and method.

Background

The coal-fired magnetohydrodynamic power generation technology is a technology for directly converting heat energy into electric energy by high-temperature high-speed ionized flue gas (plasma) generated by burning coal powder and oxygen-enriched air in a combustor through a magnetic field. The air inlet temperature of the general magnetofluid power generation is 3000K, the air outlet temperature is 2000K, and the heat efficiency can reach 20%. Because the exhaust temperature is very high, the exhaust is generally taken as a heat source to be coupled with steam power circulation, the exhaust heat is further utilized, and the overall power generation efficiency of the magnetofluid-steam combined cycle power station is improved. The supercritical CO2 Brayton cycle is used as a novel power cycle, has the advantages of high thermal efficiency, compact structure, flexible operation, low cost and the like, can replace the conventional steam power cycle and is coupled with the exhaust heat source of the magnetohydrodynamic generator, so that the power generation efficiency of the generator is greatly improved. Research shows that the coupling research of a coal-fired magnetohydrodynamic power generation mode and a supercritical CO2 power cycle power generation mode is not available at present, and the problems need to be solved.

Disclosure of Invention

In order to overcome the defects of the prior art, the invention aims to provide a coal-fired magnetofluid supercritical CO2 combined cycle power generation system and method, wherein the exhaust heat of a coal-fired magnetofluid power generator is recycled by adopting high-efficiency supercritical CO2 power, so that the overall power generation efficiency of the system is greatly improved; meanwhile, the oxygen-enriched air is preheated through the cold end of the supercritical CO2 power cycle, so that the cold source loss of the system can be reduced, and the energy utilization efficiency of the system can be improved.

In order to achieve the purpose, the invention adopts the technical scheme that:

a coal-fired magnetofluid supercritical CO2 combined cycle power generation system comprises a coal-fired magnetofluid power generator, an air preheating system and a supercritical CO2 cycle power generation system, wherein,

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 sequentially communicated, and also comprises magnets 5 arranged on two sides of the magnetohydrodynamic power generation channel 3 and an inverter converter 6 connected with electrodes of the magnetohydrodynamic power generation channel 3, wherein seeds are mixed in the combustion chamber 1; the tail part of the diffuser 4 is provided with a waste heat boiler;

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 communicated in sequence; the outlet of the high-temperature air preheater 10 is communicated with the inlet of a 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 an outlet of a cold side of a low-temperature heat regenerator 12, an inlet and an outlet of a cold side of a high-temperature heat regenerator 13, a superheated air cooling wall 14, a superheater 15, a high-pressure turbine 16, a reheated air cooling wall 17, a reheater 18, a low-pressure turbine 19, an inlet and an outlet of a hot side of the high-temperature heat regenerator 13, an inlet and an outlet of a hot side of the low-temperature heat regenerator 12, an inlet and an outlet of a hot side of a low-temperature air preheater 7, and an inlet of a precooler 20 and an inlet of the main compressor 11 are sequentially communicated; the inlet and the outlet of the recompressor 21 are respectively communicated with the inlet and the outlet of the hot side of the low-temperature air preheater 7 and the inlet and the outlet of the cold side of the high-temperature heat regenerator 13; the inlet and outlet of the economizer 22 are communicated with the outlet of the main compressor 11 and the inlet of the superheated air-cooled wall 14, respectively.

The hearth of the waste heat boiler is sequentially provided with an overheating air cooling wall 14 and a reheating air cooling wall 17 from bottom to top; a high-temperature air preheater 10, a superheater 15 and a reheater 18 are sequentially arranged in a horizontal flue of the waste heat boiler from left to right; the middle-temperature air preheater 9 and the economizer 22 are sequentially arranged on a vertical flue at the tail part of the waste heat boiler from top to bottom.

The cold end of the supercritical CO2 circulating power generation system can reduce the loss of a system cold source by arranging a low-temperature air preheater 7 for heating cold oxygen-enriched air.

The temperature of the flue gas at the outlet of the economizer 22 in the vertical flue at the tail of the waste heat boiler is 90 ℃, and the low-temperature working medium at the outlet of the main compressor 11 is partially shunted and enters the economizer 22, so that the exhaust waste heat of the waste heat boiler is completely recovered.

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 gradient preheating of the oxygen-enriched air, and can heat the oxygen-enriched air to 1700-800K.

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

A running method of a coal-fired magnetofluid supercritical CO2 combined cycle power generation system is characterized in that cold oxygen-enriched air firstly absorbs heat in a low-temperature air preheater 7 to be heated, then is subjected to pressure boosting through an air compressor 8, and then sequentially absorbs heat in a medium-temperature air preheater 9 and a high-temperature air preheater 10 to become 1700-1800K high-temperature oxygen-enriched air; after the high-temperature oxygen-enriched air and the coal powder are mixed with alkali metal salt seeds in the combustion chamber 1 and combusted, high-temperature ionized exhaust is formed, the exhaust is decompressed and accelerated through the nozzle 2, then the exhaust passes through the magnetofluid power generation channel 3 of the high-intensity magnetic field at high speed, heat energy is converted into electric energy, and the electric energy converts direct current into alternating current through the inverter converter 6 and then is sent to a power grid; the temperature of the exhaust gas is reduced after the exhaust gas comes out of the magnetofluid power generation channel 3, but the temperature is still 2000K-2100K, and the exhaust gas enters a boiler to heat a supercritical CO2 working medium after being pressurized and decelerated by a diffuser 4; the supercritical CO2 circulating power generation system adopts a once-reheat recompression configuration, and the working medium fully absorbs the exhaust heat of the magnetohydrodynamic generator in the waste heat boiler and then pushes the high-pressure turbine 16 and the low-pressure turbine 19 to do work, so that the conversion from heat energy to electric energy is realized.

The invention has the beneficial effects that:

1. according to the invention, by coupling the supercritical CO2 power cycle on the exhaust side of the coal-fired magnetohydrodynamic generator, the power generation efficiency of the system can be improved, the operation flexibility can be increased, the system compactness can be increased, and the initial investment and the power generation cost of a power station can be reduced.

2. The system has simple structure and less equipment, and can reduce the difficulty of system control and operation. The coal-fired magnetohydrodynamic generator does not need rotating equipment, has a simple structure, and realizes the direct conversion from heat energy to electric energy.

3. The invention utilizes the waste heat of the supercritical CO2 power cycle cold end to preheat the cold oxygen-enriched air, can reduce the cold source loss of the system, improves the energy utilization efficiency and realizes the energy gradient quality-based utilization.

Drawings

FIG. 1 is a schematic diagram of a coal-fired magnetofluid supercritical CO2 combined cycle power generation system.

Detailed Description

The present invention will be described in further detail with reference to the accompanying drawings.

As shown in fig. 1, a coal-fired magnetohydrodynamic supercritical CO2 combined cycle power generation system comprises a coal-fired magnetohydrodynamic generator, an air preheating system and a supercritical CO2 cycle power generation system, wherein,

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 sequentially communicated, and also comprises magnets 5 arranged on two sides of the magnetohydrodynamic power generation channel 3 and an inverter converter 6 connected with electrodes of the magnetohydrodynamic power generation channel 3, wherein seeds are mixed in the combustion chamber 1; the tail part of the diffuser 4 is provided with a waste heat boiler;

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 communicated in sequence; the outlet of the high-temperature air preheater 10 is communicated with the inlet of a 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 an outlet of a cold side of a low-temperature heat regenerator 12, an inlet and an outlet of a cold side of a high-temperature heat regenerator 13, a superheated air cooling wall 14, a superheater 15, a high-pressure turbine 16, a reheated air cooling wall 17, a reheater 18, a low-pressure turbine 19, an inlet and an outlet of a hot side of the high-temperature heat regenerator 13, an inlet and an outlet of a hot side of the low-temperature heat regenerator 12, an inlet and an outlet of a hot side of a low-temperature air preheater 7, and an inlet of a precooler 20 and an inlet of the main compressor 11 are sequentially communicated; the inlet and the outlet of the recompressor 21 are respectively communicated with the hot side port and the inlet of the low-temperature air preheater 7 and the cold side inlet of the high-temperature heat regenerator 13; the inlet and outlet of the economizer 22 are communicated with the outlet of the main compressor 11 and the inlet of the superheated air-cooled wall 14, respectively.

As a preferred embodiment of the invention, the furnace chamber of the waste heat boiler is sequentially provided with an overheating air-cooled wall 14 and a reheating air-cooled wall 17 from bottom to top; a high-temperature air preheater 10, a superheater 15 and a reheater 18 are sequentially arranged in a horizontal flue of the waste heat boiler from left to right; the middle-temperature air preheater 9 and the economizer 22 are sequentially arranged on a vertical flue at the tail part of the waste heat boiler from top to bottom.

As a preferred embodiment of the invention, the cold end of the supercritical CO2 cycle power generation system can reduce the system cold source loss by arranging a low-temperature air preheater 7 for heating cold oxygen-enriched air.

As the preferred embodiment of the invention, the temperature of the flue gas at the outlet of the coal economizer 22 in the vertical flue at the tail part of the waste heat boiler is 90 ℃, and part of the low-temperature working medium is shunted at the outlet of the main compressor 11 and enters the coal economizer 22, thereby completely recovering the exhaust waste heat of the waste heat boiler.

As a preferred embodiment of the 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 preheating of the oxygen-enriched air, and can heat the oxygen-enriched air to 1700-1800K.

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

As shown in fig. 1, in the operation method of the coal-fired magnetofluid supercritical CO2 combined cycle power generation system, cold oxygen-enriched air firstly absorbs heat in a low-temperature air preheater 7 to raise the temperature, then the cold oxygen-enriched air is boosted by an air compressor 8 and then sequentially absorbs heat in a medium-temperature air preheater 9 and a high-temperature air preheater 10 to become 1700-1800K high-temperature oxygen-enriched air; after the high-temperature oxygen-enriched air and the coal powder are mixed with alkali metal salt seeds in the combustion chamber 1 and combusted, high-temperature ionized exhaust is formed, after the pressure and the speed are reduced and increased through the nozzle 2, heat energy is converted into electric energy through the magnetofluid power generation channel 3 of a strong magnetic field at a high speed, and the electric energy is converted into alternating current through the inverter converter 6 and is sent to a power grid; the temperature of the exhaust gas is reduced after the exhaust gas comes out of the magnetofluid power generation channel 3, but the exhaust gas still has about 2000K, and the exhaust gas enters a boiler to heat a supercritical CO2 working medium after being pressurized and decelerated by a diffuser 4; the supercritical CO2 circulating power generation system adopts a once-reheating recompression configuration, and the working medium fully absorbs the exhaust heat of the magnetohydrodynamic generator in the waste heat boiler and then pushes the high-low pressure turbine to do work, thereby realizing the conversion from heat energy to electric energy.

Based on the electromagnetic induction law, when ionized flue gas (plasma) passes through a magnetic field at a high speed, charged particles in the flue gas move to electrodes under the action of Lorentz force to generate current. The flue gas conductivity is lower, the temperature can be fully ionized up to 8000K, and the magnetohydrodynamic generator can realize higher thermoelectric conversion rate. However, coal powder cannot generate such high temperature during combustion, so that the coal powder is doped with seed materials such as alkali metal salt and the like for combustion so as to improve the conductivity of the flue gas, so that the flue gas can be fully ionized at about 3000K. In addition, the oxidant during combustion adopts oxygen-enriched air and is preheated to about 1700K, so that the temperature of the flue gas is greatly increased, and the ionization degree of the flue gas is further increased. The heat carried by the high-temperature exhaust gas of the magnetofluid generator is converted into electric energy through a high-efficiency supercritical CO2 circulating power generation system based on the Brayton cycle principle.