Waste heat utilization system capable of guaranteeing lignite boiler dry output and SCR safe flue gas temperature

Abstract

The invention discloses a bootstrap system capable of guaranteeing lignite boiler dry output and SCR safe flue gas temperature. The bootstrap system comprises a boiler tail flue and a flue gas denitrification SCR which is arranged at the tail end of the boil tail flue. A bypass flue communicated with the boil tail flue is further parallelly connected between a flue gas inlet of an economizer and a flue gas inlet of the flue gas denitrification SCR. The bypass flue is internally and sequentially provided with a primary-air tubular heater and a low-pressure economizer which are used for lowering temperature of flue gas entering the flue gas denitrification SCR. Due to the arrangement that the bypass flue is additionally arranged on the tail portion of a boiler, and the primary-air heater is arranged on the upper portion of the bypass flue, primary-air temperature is ensured to meet requirements of a coal pulverizing system. The amount of flue gas passing through the economizer can be regulated by the bypass flue, so that flue gas temperature at the exit of the economizer can be regulated. The primary air is heated to the temperature as required by the high-temperature flue gas at the inlet of the economizer, and meanwhile, the flue gas temperature in the bypass flue is lowered through the low-pressure economizer, so that the flue gas temperature at the inlet of the SCR can meet the requirements of catalyst.

Description

technical field [0001] The invention belongs to the technical field of waste heat recovery from flue gas of power station boilers, and in particular relates to a waste heat utilization system for ensuring the drying output of lignite boilers and the safe smoke temperature of SCR. Background technique [0002] The "Emission Standard of Air Pollutants for Thermal Power Plants" (GB13223-2011) has been implemented since 2012, replacing GB13223-2003 and further improving the SO2 of coal-fired power plants. 2 , NO x and dust emission standards. According to the new standard of GB13223-2011, coal-fired power plants are required to x Emission control at 100mg / Nm 3 , key areas controlled at 50mg / Nm 3 . With the promulgation and implementation of the new standard "Emission Standard of Air Pollutants for Thermal Power Plants" (GB13223-2011), it is imperative for coal-fired power plants to carry out flue gas denitrification SCR transformation. [0003] Due to the high moisture con...

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Problems solved by technology

However, the temperature of the flue gas at the inlet of the air preheater decreases, the temperature of the hot air decreases, and the moisture content of the lignite is high, and the drying output of the pulverizing system is insufficient, which affects the load capacity of the unit

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