SCR Denitrification Device

Selective catalytic reduction technology (SCR) is a treatment process for NOx in flue gas emissions, that is, under the action of a catalyst, the reducing agent ammonia or urea is injected to reduce NOx in flue gas to N2 and H2O.

The working principle of SNCR denitrification deviceS is a very mature flue gas denitrification technology, and it is a post-furnace denitrification treatment method. SCR denitration device--The principle of selective catalytic reduction (SCR) denitrification is to use a reducing agent to selectively reduce NOX in the flue gas to non-toxic and pollution-free N2 and H2O under the action of a certain temperature and a catalyst. The role of the catalyst is to reduce the activation energy of the decomposition reaction and reduce the reaction temperature to 150-450°C. Because the actual temperature range of the kiln in a coal-fired power plant is 290 ° C ~ 430 ° C, if no catalyst is added, the reaction temperature will be higher (about 980 ° C), which is far beyond the temperature adaptation range of the power plant. SCR denitrification reducing agents usually include ammonia water, liquid ammonia and urea. Liquid ammonia is commonly used in industry, followed by urea.

The system composition of SNCR denitrification device is mainly composed of SCR catalytic reactor, ammonia injection system, flue gas bypass system, ammonia storage and preparation system, etc. At present, the layout of SCR reactors at home and abroad is generally high-dust, that is, it is arranged in the high-temperature flue between the economizer and the air preheater. In this position, the flue gas temperature can reach the reaction temperature. Therefore, the denitrification device of this project is planned to adopt a high-dust arrangement. The flue gas is evenly divided into two paths at the outlet of the boiler economizer, and each path of flue gas enters a vertically arranged SCR reactor in parallel, that is, each boiler is equipped with two reactors, and the flue gas enters the catalyst layer after passing through the flow equalizer. Before the flue gas enters the catalyst layer, there is an ammonia injection system. After the flue gas and ammonia are fully mixed, the catalyst reacts to remove NOX. The flue gas after the reaction enters the air preheater, electrostatic precipitator, induced draft fan and desulfurization device, and is discharged into the chimney. The SCR reactor is arranged above the air preheater.

At present, the main process flow of a typical SNCR denitrification device is as follows: the denitrification reducing agent is liquid ammonia, which is transported by the filling truck and stored in the ammonia tank in liquid form. The liquid ammonia is vaporized by the evaporator and then injected into the flue gas of the SCR system; the vaporized ammonia It is mixed with dilution air and sprayed into the flue gas upstream of the SCR reactor through the ammonia injection grid; the fully mixed reducing agent reacts with the flue gas under the action of the catalyst in the SCR reactor, so as to achieve the purpose of removing NOX.

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