Urea pyrolysis and ejection system used for low-temperature flue gas SCR denitration

Abstract

The invention discloses a urea pyrolysis and ejection system used for low-temperature flue gas SCR denitration. The outlet flue of a heating furnace communicates with a urea metering supply system, a urea solution is atomized and ejected into the outlet flue of the heating furnace by the urea metering supply system and is heated and decomposed into ammonia gas under the action of 500-600 DEG C flue gas, and the ammonia gas and the heating flue gas are sent into raw denitration flue gas, are uniformly mixed with the raw denitration flue gas under the assistance of a flow disturbing device, and heat the raw denitration flue gas to a reaction temperature needed by an SCR. A urea solution spray gun is only arranged on the outlet flue of the heating furnace, the high temperature flue gas generated by the heating furnace is used to heat and decompose the urea, and the high temperature flue gas and the heating furnace flue gas are uniformly ejected into the raw denitration flue gas without additionally arranging a urea pyrolysis furnace having a large size, the high temperature gas needed by the pyrolysis of the urea, and a matched dilution fan, heater and ammonia gas ejection distribution device, so the technology is simple, and the system is reliable, and is convenient to enforce.

Description

technical field [0001] The invention belongs to the technical field of nitrogen oxide emission reduction (denitration) of industrial flue gas, and relates to a urea pyrolysis and injection system for SCR denitrification of low-temperature flue gas. Background technique [0002] Flue gas selective catalytic reduction (SCR) denitrification technology is currently the most effective and widely used technology for denitrification of industrial flue gas (including electric power, chemical industry, steel, cement, glass furnace, waste incineration, etc.). The SCR denitrification technology is under the action of a catalyst, the amino reducing agent and the NOx in the flue gas undergo a selective reduction reaction to generate N 2 and H 2 O, and clean technology without any waste gas and waste water discharge. [0003] In the SCR flue gas denitrification technology, the amino reducing agent can be liquid ammonia, ammonia water and urea. Since liquid ammonia is a dangerous and exp...

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Problems solved by technology

[0003] In the SCR flue gas denitrification technology, the amino reducing agent can be liquid ammonia, ammonia water and urea. Since liquid ammonia is a dangerous and explosive chemical, its transportation, storage and use are strictly restricted. Therefore, with the increasing safety awareness of people More and more places began to restrict the application of liquid ammonia in the flue gas SCR denitrification system

Ammonia water below 25% can be stored under normal pressure, and there are no potential safety hazards in transportation and use. However, due to the relatively low concentration of ammonia water, about 80% of useless water is gasified at the same time during the ammonia gasification process, which consumes a lot of heat energy. , the high cost of using

Urea is the safest and environmentally friendly amino reducing agent in SCR denitrification technology, but it needs high temperature, high pressure hydrolysis or high temperature, high heat demand pyrolysis process during use, and the operating cost is also high. In order to reduce the operating cost of urea pyrolysis

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