SCR (Selective Catalytic Reduction) denitration method and device with urea pyrolysis pipes in boiler

Abstract

The invention discloses an SCR (Selective Catalytic Reduction) denitration method and device with urea pyrolysis pipes in a boiler and belongs to the field of boiler denitration. According to the denitration method, boiler flue gas in a corresponding region is used for heating a urea solution in a urea pyrolysis pipe bundle to decompose the urea solution into mixed gas containing NH3, and NH3 is used as a reducing agent of a downstream SCR flue gas denitration chemical reaction. The device comprises the urea pyrolysis pipe bundle; the inlet of the urea pyrolysis pipe bundle is communicated with primary air or secondary air of an air pre-heater by a urea pyrolysis pipe bundle inlet distribution pipe and a urea pyrolysis air supplying pipe; the outlet of the urea pyrolysis pipe bundle is communicated with an SCR denitration reaction device or an upstream thereof by a urea pyrolysis product collection pipe and a urea pyrolysis product supplying pipe; the urea pyrolysis pipe bundle inlet distribution pipe is further provided with an atomization device which is communicated with a urea solution supplying pipe. By virtue of the SCR denitration method and device, the investment cost of an SCR denitration reducing agent urea pyrolysis process can be greatly reduced, the operation energy consumption of urea pyrolysis is reduced and the operation cost is saved.

Description

technical field [0001] The invention belongs to the field of boiler denitrification, in particular to boiler SCR denitrification. Background technique [0002] Selective Catalytic Reduction of NO x , SCR denitrification process for short) There are three main reducing agents: liquid ammonia, ammonia water, and urea. Liquid ammonia is widely used in the SCR denitrification process due to its simple process system and low investment and operating costs. However, liquid ammonia is a hazardous chemical with strict requirements for transportation and storage, and its approval is increasingly subject to regulations. It is extremely inconvenient; similarly, ammonia water is also limited in application due to its transportation, storage problems and high investment and operation costs; as a SCR denitrification reducing agent with relatively low safety requirements-urea has the same denitrification performance as liquid ammonia, There are no regulations on hazardous chemicals, and ...

AI Technical Summary

Problems solved by technology

At present, the heat source of urea pyrolysis mainly adopts the primary air heated by the boiler and is equipped with an electric heater or a gas heater. For example, for the flue gas denitrification device of a 600MW unit, the energy consumption of the urea pyrolysis process using electric heating is: 500kW / h- 1800kW / h, urea pyrolysis consumes a lot of energy and high operating costs

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