System and method for preventing crystallization blockage of gas turbine denitration urea pyrolyzing furnace

Abstract

The invention discloses a system and a method for preventing crystal blockage of a denitration urea pyrolyzing furnace of a gas turbine, and belongs to the field of pollutant treatment of gas power plants. The system comprises a urea pyrolysis system and a high-temperature flue gas auxiliary heating system, high-temperature flue gas is led out from an inlet of a gas turbine waste heat boiler to serve as dilution air to enter a urea pyrolysis furnace, and meanwhile part of the high-temperature flue gas is led out to enter an annular heater in the pyrolysis furnace through a high-temperature fan and an electric heater; a urea solution which comes from the metering and distributing device and is sprayed by the atomizing spray gun is subjected to pyrolytic reaction under the heating action of heat of the two strands of flue gas to generate ammonia-containing mixed gas, and the ammonia-containing mixed gas is injected into upstream flue gas of a denitration catalyst through the ammonia spraying grid. High-temperature flue gas is assisted by electric heating to serve as an extra heat source, the overall temperature level in the pyrolyzing furnace can be effectively improved, the urea pyrolysis reaction conversion rate can be increased, generation of pyrolysis by-products is reduced, the problem of crystallization blockage of the pyrolyzing furnace is effectively prevented, the annular heating pipe is not prone to blockage, heating is uniform, and heat of the high-temperature flue gas can be fully utilized.

Description

technical field [0001] The invention relates to the field of pollutant treatment in gas-fired power plants, in particular to a system and method for preventing crystallization blockage in a gas-fired denitrification urea pyrolysis furnace. Background technique [0002] At present, the vast majority of domestic coal-fired units or gas-fired units have completed the ultra-low emission transformation of NOx, mainly using low-nitrogen combustion + selective catalytic reduction (SCR) denitration technology. SCR denitration technology is to inject nitrogen reducing agent from ammonia injection grid into the inlet of SCR reactor according to a certain ammonia-nitrogen molar ratio and mix with flue gas into the catalyst layer, and reduce NOx to N under the action of catalyst. 2 and H 2 O. Nitrogen reducing agents mainly include ammonia water, liquid ammonia and urea. Due to the high transportation cost, investment cost and energy consumption of ammonia water process, they are rare...

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Problems solved by technology

[0005] The purpose of this invention is to solve the problem that the overall temperature level in the pyrolysis furnace cannot be effectively guaranteed during the low-load operation of the unit or when the urea injection volume fluctuates greatly due to a sudden load change, resulting in pyrolysis side effects. The amount of product generated increases, long-term operation causes the crystallization blockage of the pyrolysis furnace, and the ammonia supply cannot be normal, and the NOx emission concentration at the outlet of the denitrification device has a large risk of exceeding the standard. method

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