With the development of our economy, environmental pollution has become a major obstacle to the long-term development of the country and society. Environmental protection has become one of our current and future important tasks.
Where do nitrogen oxides mainly come from?
NOx in China mainly comes from the power industry, motor vehicle exhaust and non-metallic mineral products industry. The total emissions of these three L-domains account for 83% of the total NOx emissions.
NOx is formed in the following ways:
1. When the generator set or engine is burning at high temperature, NOx is the product of the complete combustion of the fuel, and a large amount of NOx is produced when the fuel is burning at high temperature;
2. Under the condition of high temperature decomposition, the volatile matter of the fuel decomposes at high temperature, reacts with nitrogen in the air, and is produced at a very fast speed with oxygen;
3. It is formed by oxidation of nitrogen compounds in fuel during combustion;
4. Organic compounds containing nitrogen are decomposed and then oxidized;
Reaction mode of SCR denitration -- selective catalytic reduction
To control NOx in generator tail gas, NH3 or urea (usually urea aqueous solution with mass ratio of 32.5%) is used as reducing agent. Under certain temperature and catalyst, NH3 is used to reduce NOx to N2 and H2O. As NH3 has high selectivity, NOx is preferentially reduced without reacting with O2 first.