What Are The Main Components Of Denitrification Catalyst? What Is The Basic Principle?

Denitrification catalyst is mainly TiO2 as the carrier, with WO3, MoO3 as antioxidant and anti-poisoning auxiliary components, in the SCR reaction, the denitrification catalyst is a substance that can prompt the reductant to selectively react chemically with the nitrogen oxides in the flue gas at a certain temperature, and the SCR catalyst components and ratios vary according to the content of the components in the flue gas as well as the guaranteed value of the denitrification performance.

TiO2: as the carrier of the catalyst, providing a larger specific surface area and more selective active sites.

WO3: as a catalytic additive to improve the thermal stability of the catalyst, inhibit and delay high temperature sintering of the catalyst, and inhibit sulfur conversion.

V2O5: as the most important active substance of the catalyst, degrading NOX.

SCR is selective catalytic reduction technology. This technology has the advantages of no by-products, no secondary pollution, simple device structure, high removal efficiency of more than 90%, reliable operation and easy maintenance, etc., and is widely used in denitrification projects.

Scr denitrification process

Reducing agent is transported by tank truck and stored in liquid form in ammonia tank; liquid ammonia is evaporated and gasified by evaporator before injecting into the flue gas of SCR system; gasified ammonia and dilution air are mixed and injected into the flue gas upstream of SCR reactor through ammonia spraying grill; after sufficient mixing, the reducing agent and the flue gas are reacted under the action of catalyst in the SCR reactor to remove NOx.

Principle of SCR denitrification system

SCR denitrification process mainly consists of SCR catalytic reactor, ammonia injection system, flue gas bypass system, ammonia storage and preparation system and so on.

The SCR catalytic reactor is generally arranged in a high dust arrangement, i.e., it is arranged in the high temperature flue between the coal economizer and the air preheater. At this location, the flue gas temperature can reach the optimum temperature for the reaction.

The flue gas is equally divided into two paths at the exit of the boiler economizer, and each path enters a vertically arranged SCR reactor in parallel, i.e., each boiler is equipped with two reactors, and the flue gas passes through the equalizer and enters the catalyst layer. Before the flue gas enters the catalyst layer, there is an ammonia injection system, the flue gas is mixed with ammonia and the catalyst reaction is carried out to remove NOX. the reacted flue gas enters into the air pre-preparator, electrostatic precipitator, induced draft fan and desulfurization device, and then discharged into the chimney. the SCR reactor is arranged on the top of the air pre-preparator. As the core of SCR process, the quality and performance of denitrification catalyst are directly related to the overall process efficiency. Therefore, in addition to the reactor and flue design should not be ignored in the denitrification project, the design of catalyst parameters is also crucial.

Generally speaking, denitrification catalysts are customized for the project, i.e. based on the project flue gas composition, characteristics, efficiency and customer requirements.