Research On The Waste Gas Emission And Prevention Of Sulfur And Nitrate From Cement Kiln

The SO2 and NOx emission from cement kiln has become a serious problem to the ecological protection. In this chapter, Combining laboratory research to factory reality ,We studied the factors on the emission of SO2 and NOx from the cement kiln by using X-ray diffraction photoelectron spectroscopy analysis ,coal proximate and ultimate analysis ,waste gas composition analysis and XRD analysis. We also proposed effective preventions to control SO2 and NOx Pollution of cement industry . Results show as follow:The presence of nitrogen in the raw and fuel material plays an important role in the fuel NOx emission. Because of the different main nitrogen functional groups, the waste leather,which has the amino acid nitrogen as the main form generates the highest concentration of fuel NOx in the same condition of 900℃and oxygen-rich ambience .The Sewage sludge with the amino acid and amide as the main nitrogen followes .The coal mainly existed with pyrrole-type nitrogen produces the lowest fuel NOx concentration.The fuel NOx concentration increases with burning more raw material as well as fuel in the excess air ratio over one and oxygen-rich condition. Calcining coal with waste leather could increases the fuel NOx emission. CaO and cement clinker affectes the NOx concentration to some extent. Mixing coal and waste leather, cement clinker has a more obvious effect than CaO.NOx concentration would go down with the SO2 emission increasing when burning the original fuel materials. SO2 can catalyze thus reduce the concentration of free radicals, which could accelerate the nitrogen intermediates Oxidation. Besides,some sulfur material can response with nitrogen directly to inhibit the formation of NOx in some way.Precalcining kilns produces higher NOx concentration than Shaft kilns. Kiln grinding integrated system could not reduce the NOx concentration .Reducing the coal materials ratio, tertiary air temperature, gas oxygen content and other parameters could save the usage of coal and inhibit the NOx emission.The form of sulfur in cement material affect the releaseing of sulfur in somewhat different . Iron sulfide sulfur shedding is lower, calcium sulfate sulfur shedding is higher. The SM of the cement material has little effect on the the sulfur emission. But the sulfur content of cement materials has great influence of sulfur shedding in cement calcination .The higher of the sulfur contains , the more of the SO2 releases.Precalcining kilns causes lower SO2 concentration than Shaft kiln, because the pre-calcining kiln raw mill system can absorb SO2. Putting lime into mill or filter can reduce the SO2 emission. When Ca/S = 0.5, the former desulfurization rate is 32.16%, which is better than the latter with 9.47% desulfurization rate .Using CKD with high Sulfur content as cement mixture can reduce the sulfur circulation and SO2 emission and also has little effect on the mainly Performance of the cement.Researching on the emission of SO2, NOx from the cement kiln to control their pollution has an important meaning for the cement industry's environment-friendly development.