Biomass gasifying coupled coal-fired boiler full-load SCR denitration system and technique

Abstract

The invention provides a biomass gasifying coupled coal-fired boiler full-load SCR denitration system and technique. The system comprises a biomass gasifying system and a coal-fired boiler SCR denitration system. The biomass gasifying system comprises a biomass gasifying furnace and a heat exchanger. The biomass gasifying furnace is connected to the heat exchanger. The heat exchanger is connectedto the coal-fired boiler SCR denitration system. The coal-fired boiler SCR denitration system comprises a coal-fired boiler and a coal saver. The flue gas outlet of the coal saver is sequentially connected to ammonia spraying grating, a SCR denitration reactor, an air preheater, an electrostatic dust collector, a desulfurization device, and a chimney. The provided denitration system and techniquecan increase the temperature of flue gas in the denitration inlet, the feeding / transporting requirements of a low-load denitration device of a boiler can be satisfied, at the same time, a large amountof biomass is consumed, and the using of clean energy is increased.

Description

technical field [0001] The invention belongs to the technical field of flue gas denitrification in coal-fired power plants, and in particular relates to a biomass gasification coupled coal-fired boiler full-load SCR denitrification system and a process method. Background technique [0002] Selective Catalytic Reduction (SCR) is the most widely used and mature flue gas denitrification technology at home and abroad. It is a post-furnace denitrification method, which uses the reducing agent NH 3 , optionally with NO x The reaction produces harmless N 2 and H 2 O. [0003] In recent years, the national environmental protection requirements have been continuously improved, and the requirements for the emission of flue gas pollutants from coal-fired power plants have become more and more stringent. The denitrification of power plants requires not only high efficiency and stability, but also the denitrification of the units during medium and low load operation, and the ability t...

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Problems solved by technology

At present, when domestic coal-fired units are operating at medium and low loads, the flue gas temperature at the inlet of the SCR reactor is less than 300°C, which is lower than the lower limit of the optimal reaction temperature of the SCR catalyst, which will lead to low denitrification efficiency, poor catalyst activity, and ammonia High escape rate, even out of operation, it is difficult to meet low NO under full load x emission requirements

[0004] At the same time, when the SCR smoke temperature is too low, side reactions will also occur on the catalyst, and the generated (NH 4 ) 2 SO 4 or NH 4 HSO 4 It will stick to the denitrification catalyst and air preheater, and absorb dust, resulting in reduced catalyst activity and blockage of air preheater, which will seriously affect the denitrification efficiency and NOx of the boiler. x Emission concentration affects the safe and stable operation of the unit

[0005] In order to ensure that the flue gas temperature at the inlet of the SCR reactor meets the conditions for the catalyst to be put into operation during the daily operation of the coal-fired boiler, the technical means usually used include high-temperature flue gas heating, economizer section layout, bypass part of the economizer water supply, and raising the boiler Feed water temperature, etc., but these solutions are all based on the traditional combustion method of the boiler, and each has its own advantages and disadvantages. For example, the actual exhaust gas temperature of the boiler will be continuously increased, and the working efficiency of the boiler will be reduced; the increased smoke temperature is limited, and the effect is not ideal; the investment cost Higher

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