What are the methods for denitration of boilers?

The emission of nitrogen oxides from boilers is a major source of air pollution. For the sake of human beings and the environment, we need to remove nitrogen oxides from flue gas. Therefore, it is necessary to develop and design a method for denitration of boilers to help them meet the emission standards.

At present, the methods of boiler denitration are mainly divided into selective catalytic reduction (SCR), non-selective catalytic reduction (SNCR), HNCR polymer denitration technology, SNCR+SCR and HNCR+SCR combined flue gas boiler denitration equipment.

1, SCR boiler denitration method

Principle: Install the SCR denitration module on the flue outside the boiler, and the flue gas enters the SCR reactor vertically, and NOX is reduced to N2 and H2O through each layer of catalyst modules. The reaction temperature of the SCR boiler denitration equipment is generally between 200 and 400, and the denitration efficiency is 80%-90%. There are also low-temperature catalysts, which are about 100 degrees. The cost of this catalyst is high.

Application: There are mature cases of SCR boiler denitration in large boilers, but the investment is too large. The catalyst is a consumable and needs to be replaced once every 2-3 years, which is expensive. Denitrifying agent is also needed in operation, so the later operation cost is high and it is suitable for larger boilers.

2, SNCR boiler denitration method

Principle: Punch a hole in the proper position of the boiler, extend the spray gun into the proper high temperature area (generally 750-1100℃) inside the furnace, and reduce NOX into harmless N2 and H2O by denitrating agent urea or ammonia water.

Application: Generally, the denitration efficiency is between 50% and 60%, which is not a problem for areas where the standard of nitrogen oxides falls below 200 mg. The method of denitration with SNCR boiler is more suitable and the operating cost is low. The denitration price of SNCR boiler is relatively low, and the denitration agent with later operation cost is also relatively low.

3, HNCR boiler denitration method

Principle: In order to denitrate in the furnace, a hole is drilled in the appropriate position of the boiler, and the spray gun is extended into the appropriate high temperature area (generally 750-1100℃) inside the furnace, and NOX is reduced to harmless N2 and H2O by uniformly spraying denitrating agent.

Application: The denitration efficiency is about 70%-80%, and the denitration agent is solid powder or particles, which has low operating cost and low consumption of denitration agent. No matter large, medium and small boilers, HNCR boiler can be used for denitration, which is also a denitration process with high utilization rate at present.

4, Denitrification method of SNCR/HNCR+SCR combined boiler

Application: There are cases in chemical plants, power plants and steel plants, and the denitration efficiency is generally around 90%. This technology reduces the installation cost of SCR boiler denitration equipment, can use less catalyst and save some costs for customers.

As a boiler manufacturer for more than 30 years, ZOZEN Boiler has strong strength, good reputation, rich experience in boiler projects, strong scientific research strength and many achievements in energy conservation and environmental protection. At present, the company has formed a number of specifications such as gas boilers, biomass boilers, coal-fired boilers, circulating fluidized bed boilers, and thermal oil heaters, which are widely used in chemical industry, food, wine making, heating, paper making, printing and dyeing, rubber and other industries.