Double-working medium coal-fired power generation system and method

Abstract

The invention discloses a double-working medium coal-fired power generation system according to the technical scheme. The double-working medium coal-fired power generation system comprises a boiler, a supercritical carbon dioxide cycle and an ultra-supercritical steam cycle. The boiler is provided with a hearth, a horizontal flue and a tail flue, a water cooling wall and an air cooling wall are installed on the lower portion of the hearth, and a steam superheater and a carbon dioxide superheater are installed on the upper portion of the hearth. The supercritical carbon dioxide cycle comprises a main compressor, a low-temperature regenerator, a high-temperature regenerator, a high-pressure carbon dioxide turbine, a medium-pressure carbon dioxide turbine, a low-pressure carbon dioxide turbine inlet, a recompressor and a first generator. The ultra-supercritical steam cycle comprises a waste heat exchanger, a precooler, a condensate pump, a low-pressure heater, a deaerator, a feed water pump, a high-pressure heater, an economizer, a stream superheater, a high-pressure stream turbine, a medium-pressure stream turbine, a lower-pressure stream turbine, a condenser and a second generator. According to the technical scheme, the power generation system combines the advantages of the ultra-supercritical steam cycle and the supercritical carbon dioxide cycle, and greatly improves the power generation efficiency of a unit.

Description

technical field [0001] The invention relates to the technical field of power generation, in particular to a duplex coal-fired power generation system and method. Background technique [0002] Coal-fired power generation is one of the main power supply methods in my country, and will still occupy the largest share of power generation at present and for a long period of time in the future. However, coal-fired power generation is facing a severe situation of quality improvement, efficiency improvement and transformation development. In the long run, in order to meet the requirements of reducing carbon dioxide emissions, on the one hand, it is necessary to speed up the development of units with higher parameters, that is, the next generation of 700°C ultra-supercritical units. However, this technical route requires a large number of expensive nickel-based superalloys. The cost of the unit is very high; on the other hand, it is necessary to innovatively develop new coal-fired pow...

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Problems solved by technology

[0004] However, the supercritical carbon dioxide cycle has the characteristics of deep heat recovery. When it is directly combined with the boiler, the temperature of the working fluid entering the boiler is very high, which will cause two problems.

On the one hand, the exhaust gas temperature of the boiler is too high, which will damage the thermal efficiency of the boiler; on the other hand, the wall of the furnace cannot be effectively cooled, and the temperature is too high, which affects the insulation of the wall and the structural strength of the furnace wall

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