Surplus heat utilization system of boiler for deeply reducing exhausted smoke temperature

Abstract

The invention relates to a surplus heat utilization system of a boiler for deeply reducing exhausted smoke temperature, and belongs to a surplus heat recycling energy-saving system of a boiler for deeply reducing exhausted smoke temperature to below a dew point. The system uses a low-pressure coal economizer as a heat absorption main body, and the low-pressure coal economizer is arranged on a tail flue of a dust remover outlet and a desulphurization system inlet of the boiler; and a heat exchange element of the low-pressure coal economizer is made of enamel or nickel-based seepage anticorrosive material or anticorrosive steel to improve the anticorrosive capability of equipment after the dew point and improve the reliability. A heat absorption medium is water and is from a heat return system or a heat supply system for heat cycle of a power plant, and the heat return system and the heat supply system can be switched according to the requirement. Through the surplus heat utilization system of the boiler for deeply reducing the exhausted smoke temperature, the flue-gas temperature can be reduced to 80 to 100 DEG C; therefore, the system not only reclaims the heat, but also can meet the requirement of the desulphurization system, and creates conditions for high-efficiency work of the desulphurization system.

Description

technical field [0001] The invention belongs to a boiler waste heat recovery and energy saving system, in particular to a system capable of deeply reducing the exhaust gas temperature of various boilers below the dew point, maximizing the use of boiler waste heat, and having no influence on boiler operating parameters and operation modes. Take advantage of the system. Background technique [0002] At present, the designed exhaust gas temperature of the boiler is about 120-150°C, which varies due to the difference in boiler capacity and coal type. The most important factor to control the exhaust gas temperature is the dew point temperature of the flue gas, which mainly depends on the sulfur content and ash content of the coal. The wall temperature of the heated surface at the rear of the traditional boiler is mostly affected by this. In order to avoid the influence of corrosion and ash plugging, it cannot break through this limitation. In fact, the exhaust gas temperature o...

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Problems solved by technology

[0004] Chinese patent ZL200620088594.7 discloses a "low-pressure economizer", which is a device that utilizes the waste heat of boiler flue gas to reduce the exhaust gas temperature, but the temperature range of the exhaust gas temperature lowered by this low-pressure economizer is generally limited to The exhaust gas temperature of the boiler is above the designed exhaust gas temperature, and the exhaust gas temperature cannot be lowered below the dew point

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