SCR denitration process

SCR denitration process

System process diagram

Principle of SCR denitration technology
The reducing agent (ammonia) is transported by tank trucks and stored in the ammonia tank in liquid form; the liquid ammonia is evaporated and gasified by the evaporator before being injected into the flue gas of the SCR system; the vaporized ammonia is mixed with the dilution air and passed through the ammonia injection grille It is injected into the flue gas upstream of the SCR reactor; the fully mixed reducing agent and flue gas react under the action of the catalyst in the SCR reactor, and the reaction generates harmless nitrogen and water to remove NOx.
Selectivity means that under the action of a catalyst and in the presence of oxygen, NH3 preferentially undergoes a reduction and removal reaction with NOx to generate nitrogen and water, rather than an oxidation reaction with oxygen in the flue gas. The main reaction formula is:
4NO+4NH3+O2→4N2+6H2O
2NO2+4NH3+O2→3N2+6H2O
In the absence of a catalyst, the above chemical reaction is only carried out in a very narrow temperature range (about 980°C). When a catalyst is used, the reaction temperature can be controlled at 300-400°C, which is equivalent to the boiler economizer and air preheater. The temperature of the flue gas between the heaters is an exothermic reaction. Since the concentration of NOx in the flue gas is low, the increase in the temperature of the catalyst caused by the reaction can be ignored.
Technical characteristics of SCR flue gas denitrification
a. The denitration efficiency is high, up to 80-90%, which can ensure that the flue gas emission meets the national ultra-clean emission standard;
b. The technology is mature and reliable, and the coal quality and unit load adapt to a wide range.
c. There are various reducing agents and various layout forms;
d. Modular design, pay equal attention to overall and detail design, and strive for accurate design;
e. The system is fully automated, easy to install and maintain.