SCR technology for denitrification in China more than 95% of the thermal power industry production line is widely used, but at the same time the technology in the glass furnace and other industrial furnaces also successfully applied, such as the cement industry. But there is a technical difficulty is low-temperature catalyst, in the “denitrification catalyst should be to which direction,” a paper also said that low-temperature denitration catalyst is one of the research direction.
Honeycomb Denitrification Catalyst in Cement
The main components of honeycomb denitration catalyst for cement kiln are TiO2, V2O5 and WO3, axial / radial compressive strength≥2.5 / 0.8Mpa, mass specific surface area≥60m2 / g. Mainly used for 120-200 ℃ boiler flue gas denitrification.
In fact, SCR is the industry’s most widely used denitrification technology, nitrogen oxide removal efficiency is high known: the ideal state, can nitrogen oxide removal rate of 90% or more, into the flue gas Of the ammonia almost completely and nitrogen oxides reaction, is the best fixed source denitrification technology. In the power industry to implement the nitrogen oxide emission value of 50mg / Nm3 circumstances, can still be a good emission requirements. However, such a high efficiency of denitration technology in the cement industry why little application? The reason, the cement industry complex working conditions and high one-time investment and other unfavorable factors restricting the SCR technology in the cement industry applications.
1, cost constraints: the use of SCR denitrification technology needs to be additional devices, space, investment, operating costs higher. Data show that, 2500t / d SCR production line with a total investment of 20 million yuan, the operating cost of about 6 tons of clinker tons.
2, the temperature limit: It is understood that the catalyst is currently the most widely used porous Ti2O5 (carrier) made of honeycomb modular, carrier surface coated with the catalytic active ingredients V2O5 and WO3, the reaction temperature of 280 ℃ ~ 400 ℃ is better . In the new dry process cement production line, the preheater outlet temperature has advanced to below 300 ℃, and to implement the national energy saving policy, China’s more than 2500t / d production line generally installed waste heat boiler, the exhaust temperature At around 150 ° C, this presents a new challenge for denitration catalysts that can achieve denitrification efficiencies above 80% at lower temperatures, for domestic catalyst producers whose core technologies are purchased from Japan and Germany Is a huge challenge.
The ammonia gas or other reducing agent is injected into the flue gas upstream of the catalyst, and the nitrogen oxide in the flue gas is converted into nitrogen and water by the catalyst so as to achieve the purpose of denitration. So the flue gas temperature on the efficiency of the catalyst greatly, and in the cement industry, the most difficult technical difficulties is low-temperature denitrification catalyst, if it can develop low-temperature denitrification catalyst to improve the catalytic efficiency, then the denitrification catalyst will be greater opportunities.