Supercritical carbon dioxide cycle coal-fired power generation system integrated with low-temperature waste heat recovery and its operation method

Abstract

The invention discloses a supercritical carbon dioxide circulating flue gas coal-fired power generation system integrated with low-temperature waste heat recovery and its operation method. Heaters, boilers, high-pressure turbines, medium-pressure turbines, and low-pressure turbines; superheated gas-cooled walls and primary reheaters are arranged in the boiler furnace to jointly bear the furnace radiation heat load to prevent superheated supercritical carbon dioxide from overheating; The supercritical carbon dioxide working fluid diverted from the outlet of the thermoregenerator enters the rear shaft flue of the boiler. The medium-temperature economizer absorbs the heat of high-temperature flue gas, and the supercritical carbon dioxide working fluid diverts from the outlet of the second-stage main compressor into the tail of the boiler. The economizer absorbs the heat of low-temperature flue gas, so as to reach the temperature required for the operation of various auxiliary equipment, improve the efficiency of auxiliary equipment, and at the same time realize the cascade utilization of low-temperature flue gas heat in the boiler, reduce the exhaust gas temperature of the boiler, and improve the boiler efficiency and electrical efficiency.

Description

Technical field[0001]The invention relates to the technical field of coal-fired power generation, in particular to a supercritical carbon dioxide cycle coal-fired power generation system and an operation method integrated with low-temperature waste heat recovery.Background technique[0002]World energy demand continues to grow with the rapid economic development, and my country's fossil energy structure is seriously unbalanced. Therefore, coal has always been the main body of my country's primary energy consumption. Due to the fact that other forms of power generation have many restrictive factors and the large base of thermal power generation units, coal-fired power generation is still the main power generation method in my country in a short period of time. Thermal power units are a large consumer of coal in my country, and the annual coal consumption accounts for about 50% of the country's total coal consumption.[0003]In recent years, my country has made considerable progress in th...

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Problems solved by technology

However, due to the high radiation heat load of the boiler furnace, the heat absorption load of superheated carbon dioxide in the boiler is relatively low, and the arrangement of only a single superheated gas-cooled wall in the furnace will lead to overheating of superheated carbon dioxide, resulting in overheating of the metal wall temperature of the pipeline. It affects the safe operation of the boiler, so it is necessary to arrange the radiation heating surface in the boiler furnace reasonably; the low-temperature supercritical carbon dioxide is heated by the low-temperature regenerator, the medium-temperature regenerator and the high-temperature regenerator, resulting in a high temperature of the supercritical carbon dioxide at the boiler inlet. Unable to make full use of the flue gas heat at the tail of the boiler, resulting in the following problems:

[0006] 1. The inlet flue temperature of the SCR denitrification device is too high, which affects the SCR efficiency

[0007] 2. The inlet smoke temperature of the air preheater is too high, and the irreversible loss of the air preheater increases

[0008] 3. The exhaust gas temperature of the boiler is too high, the efficiency of the electrostatic precipitator is reduced, and the efficiency of the boiler is reduced

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