Experimental Study On Thermochemical Reaction And Synergistic NO Reduction Of Dry Sludge Under Ca-L Decarbonized Flue Gas Atmosphere

The greenhouse effect which caused by CO₂ emission has seriously affected the survival and development of human,so carbon emission reduction has become inevitable.Calcium looping?Ca-L?is one of the effective technologies to absorb CO2from flue gas of power plants.However,during CO₂ capture process,a large amount of heat is discharged with the flue gas,resulting in energy waste.In addition,Ca-L decarbonization flue gas still contains a lot of NOx,in which is one of the main cause of environment pollution.This paper proposes to use the heat and reducing environment by the Ca-L decarbonized flue gas,and select dry municipal sludge to conduct sludge char preparation and synergistically remove NOx under Ca-L decarbonized flue gas,while achieving sludge resource utilization.The research is carried out from the following three aspects by using self-built macro thermogravimetric experimental equipment and aperture analyzer and other experimental equipment.?1?The thermochemical reaction characteristics of dry sludge under decarbonization atmosphere were studied,and the reaction kinetics model was established.?2?The effect of char making conditions on pore characteristics and fractal mechanism of sludge char were studied.?3?The nitro oxide reduction characteristics of dry sludge and the transformation mechanism of nitrogen foundational groups of sludge char were studied.The thermochemical reaction characteristics of dry sludge under different conditions?heating rate,carbon dioxide concentration and oxygen content?in Ca-L decarbonization flue gas were studied in self-built macro thermogravimetric experimental equipment.In addition,the reaction kinetics model was established.The results demonstrate that,the weight loss peak,ignition temperature and burnout temperature of sludge move to the high temperature zone with the increase of heating rate,and move to the low temperature zone with the increases of oxygen content and carbon dioxide concentration.According to the kinetic analysis,the reaction order model is suitable for macro thermogravimetric experiments of sludge.The apparent activation energy E and pre-exponential factor A rise with the increase of heating rate and oxygen content,but reduce with the increase of CO₂ concentration.By conducting rapid char making experimental equipment,this paper researches the effect of char making conditions on pore characteristics and fractal mechanism of sludge char.The results show that,the higher the char marking temperature,the better the pore structure of the sludge char.The pore structure and specific surface area of the sludge char firstly developed and then destroyed with the increase of char making time.The increases of oxygen content and carbon dioxide concentration in Ca-L decarbonization flue gas are not conducive to the development of pore structure of sludge char.According to the study of fractal mechanism,it is found that the variation of fractal dimension D of sludge char is consistent with the development of pore structure.The nitro oxide reduction characteristics of dry sludge and the transformation mechanism of nitrogen foundational groups of sludge char were studied in nitro oxide reduction experimental equipment.The results illustrate that,with the increase of reaction temperature and initial concentration of NO,the nitro oxide reduction ratio of sludge increased.Also,with the increase of oxygen content,the nitro oxide reduction ratio of sludge and sludge char decreases,and the contribution rate of sludge char can not be ignored.After removal of ash by acid washing,the nitro oxide reduction ratio of sludge char increased slightly.The sludge contains four nitrogen functional groups:P-N,N-6,N-5 and N-Q,of which P-N content is the most.With the increase of oxygen content,the content of N-6,N-5 and N-Q in residual char decreased while the content of N-X increased.