Combined air supply heating depth waste heat recycling system of low-low-temperature economizer of coal-fired unit

Abstract

The invention relates to the field of smoke exhaust waste heat utilization of a boiler, and particularly discloses a combined air supply heating depth waste heat recycling system of a low-low-temperature economizer of a coal-fired unit. The waste heat recycling system is characterized in that a low-low-temperature economizer high-temperature segment is arranged in a front flue of an electrostatic precipitator, and a low-low-temperature economizer low-temperature segment is arranged at the position from an induced draft fan outlet to a desulfurizing tower inlet flue; the low-low-temperature economizer high-temperature segment is connected with a condensate pipeline of a condenser, and the low-low-temperature economizer low-temperature segment is in parallel connection with a primary air heater and a secondary air heater through low-low-temperature economizer low-temperature segment water outlet pipelines; and the water outlet pipeline of the primary air heater and the water outlet pipeline of the secondary air heater are communicated with a low-low-temperature economizer low-temperature segment water returning pipeline of the low-low-temperature economizer low-temperature segment. The temperature of the smoke of the desulfurizing tower inlet is reduced to about 50 DEG C, coal saving benefits are obtained, meanwhile, the water consumption of a desulfurizing tower is reduced, and the whole running benefits of a power plant is greatly improved.

Description

(1) Technical field [0001] The invention relates to the field of boiler exhaust waste heat utilization, in particular to a low-low temperature economizer combined with air supply heating depth waste heat recovery system of a coal-fired unit. (2) Background technology [0002] At present, the cooling range of domestic conventional low-pressure economizers is as low as about 90°C, and the low-temperature section of the heating surface often needs to use alloy steel to meet low-temperature corrosion and other problems. The country's new 2014-2020 "Coal Power Energy Conservation and Emission Reduction Upgrading and Transformation Action Plan" requires that the coal consumption of active units for power supply reach the international advanced level, which requires boiler exhaust waste heat recovery and utilization technology to deeply reduce the exhaust gas temperature. breakthrough. [0003] In addition, the optimum reaction temperature for wet desulfurization is about 50°C...

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Problems solved by technology

[0003] In addition, the optimum reaction temperature for wet desulfurization is about 50°C. Higher flue gas entering the desulfurization system will lead to an increase in desulfurization water consumption, which in turn will increase the moisture content of the chimney and reduce the self-extraction force of the chimney.

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