A dual-path dual-circulation heat exchange system

Abstract

The invention discloses a double-circuit and double-circulation heat exchanging system.A smoke cooler, a boiler water feeding heater and a flue-gas reheater are sequentially connected to form a closed circulation loop, and heated medium water is continuously circulated in the closed circulation loop; a first low-pressure heater, a second low-pressure heater, a third low-temperature heater, a fourth low-temperature heater and the boiler water feeding heater are sequentially connected to form an open circulation loop, and condensate water operates in the open circulation loop to be sent to a boiler.Environmental protection is achieved, energy is saved, and the removal efficiency of pollutant of the system can be effectively improved; as heat is released through the heated medium water, the temperature of discharged smoke is increased, visual pollution is eliminated, a chimney is omitted, and the antiseptic aim is achieved; the spare smoke heat can be further used for heating fed boiler water, the steam extracting amount of a steam turbine is decreased, the heat efficiency of a unit is improved, the coal consumption of the unit is reduced, and CO2 emission is reduced.The series-parallel combining design is adopted, and the smoke temperature and the temperature of the heated medium water are dynamically and accurately adjusted in a preliminary-adjustment and accurate-adjustment combined mode.

Description

technical field [0001] The invention relates to a flue gas waste heat recovery and utilization device in the field of ultra-low emission of flue gas in a thermal power plant, in particular to a dual-path dual-cycle heat exchange system, which belongs to the technical field of energy-saving and environmental protection equipment. Background technique [0002] The flue gas temperature of boilers in thermal power plants is generally 120-160°C. In order to meet the demand for ultra-low emission of flue gas, it is often necessary to reduce the flue gas temperature to below the acid dew point (about 90°C) to improve the dust removal efficiency of the electrostatic precipitator. The usual practice is to install a flue gas cooler in the inlet flue before the electrostatic precipitator to reduce the temperature of the flue gas, and the heat recovered from the flue gas is used to heat the boiler feed water, improve the thermal efficiency of the boiler, and save coal consumption. This m...

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Problems solved by technology

[0004] (1) The flue gas purification system adopts the "energy-saving heat exchange system". The exhaust gas temperature of the chimney is about 50°C, and the flue gas contains a large amount of white water mist, which causes serious visual pollution. The corrosion of the chimney is serious, and it is necessary to increase the anti-corrosion investment of the chimney

In addition, low-temperature flue gas has low lifting and diffusion capabilities, and water mist and fine particles fuse to form aerosols, which can easily cause haze weather

[0005] (2) The flue gas purification system adopts the "environmentally friendly heat exchange system". All the surplus heat of the original flue gas is used to heat the clean flue gas, which has no energy-saving function, especially in summer or when the unit is under high load. The gas temperature is high, and there is a lot of surplus heat. If all the surplus heat of the original flue gas is used to heat the clean flue gas, the use of heat is unreasonable, and there is a waste of heat.

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