Device and method for preparing ammonia by hydrolyzing urea for flue gas denitrification of thermal power plant

Abstract

The invention relates to a device and a method for preparing ammonia by hydrolyzing urea for flue gas denitrification of a thermal power plant. A urea solution with the mass concentration of 40-60% is hydrolyzed into ammonia gas by utilizing a kettle reactor, and then the ammonia gas is fed into a SCR (Selective Catalytic Reduction) device of a power station boiler to be used as a denitrification reducing agent; water, electricity and steam required by operation of the whole hydrolysis device are all provided by the power station boiler, and the steam exchanges heat in the hydrolysis reactor and a urea dissolving tank through a coil pipe, is not in contact with the urea solution, and returns to the power station boiler to be heated to form circulation after releasing heat; FeAl powder and Al2O3 mixed solid powder are adopted to prepare a hydrolysis catalyst, the hydrolysis catalyst is mixed with the urea solution to form a turbid liquid, and meanwhile, a reaction solution is fed into the feeding urea solution through a circulating pump to form circulating flow of the reaction solution, so that uniform distribution of catalyst particles is promoted, and the hydrolysis reaction rate is increased.

Description

technical field [0001] The invention relates to flue gas denitrification technology in thermal power plants, in particular to a device and method for producing ammonia by hydrolyzing urea for flue gas denitrification in thermal power plants. Background technique [0002] In the SCR denitrification system of thermal power plants, the reducing agent is the largest consumable, and its consumption cost directly affects the overall economic indicators of the denitrification system. The preparation of denitrification reducing agent can adopt liquid ammonia method and urea method. Among them, the liquid ammonia method has a simple process system and low investment and operation costs. It has been widely used in current projects, but the disadvantage is that it requires higher system safety. According to the "Identification Standards for Major Hazardous Sources of Hazardous Chemicals" (GB18218-2009), liquid ammonia reserves exceeding 10 tons are regarded as major hazards, and liquid...

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Problems solved by technology

[0005] There are some problems in the operation of the existing urea hydrolysis ammonia production process, for example: the low temperature crystallization of urea solution leads to the blockage of the delivery pipeline; The composition of diurea causes blockage of the urea hydrolysis system; urea will produce some acidic substances (such as ammonium carbamate, etc.) during the hydrolysis process, which will destroy the oxide film on the stainless steel surface and accelerate the corrosion rate of the pipeline; The volume is too large, and the variable load response time is difficult to meet the denitrification requirements of the boiler

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