Development And Process Design Of Low-rank Coal Biochemical Synergistic Combustion-assisted Emission Reduction Technology

With the rapid development of modern industry,coal,oil,natural gas and other fossil energy sources are consumed in large quantities,especially the polluting gases such as SO2and H2S produced by coal combustion,which cause serious harm to the environment and society.Recently,low-rank coal resources such as lignite and long-flame coal have become an important direction for coal energy utilization.As my country's coal production capacity gradually moves westward,the scale of low-rank coal development has increased,the depth of mining in central and eastern regions and southern regions has increased,the coal quality has become worse,and the sulfur content of raw coal has increased.Improving the combustion efficiency of low-rank coal,reducing polluting gas emissions from coal combustion,and achieving environmental protection and efficient use have become issues of common concern to our government,enterprises,and academia.In this paper,microbial desulfurization and chemical catalysis technology are used to conduct emission reduction and combustion research for low-rank coal,and a pilot process design is carried out based on the experimental results.In this paper,optimization experiments were carried out on the desulfurization bacteria,desulfurization cycle,coal powder particle size and desulfurization atmosphere in the biological desulfurization process,and found that the desulfurization process conditions were:temperature 30?,initial pH=2,coal slurry concentration 10%,The inoculation amount is10%,the rotation speed is 150rpm/min,the particle size of the coal powder is 80 mesh,the desulfurization atmosphere is the introduction of CO2 with a gas flow of 30ml/min,and the desulfurization is mixed together by Thiobacillus ferrooxidans and Thiobacillus acidophilus.At that time,the measured sulfur removal rate of iron sulfide in low rank coal was about 90%.Various physical and chemical characterization methods such as SEM,IR,XRD,XPS,BET,TG,etc.were used to analyze the change of coal surface structure before and after desulfurization,and the removed amount?molar amount?of Fe?in iron sulfide in coal?in the process of biological desulfurization as a benchmark,the metal nitrate of Mn,Fe,Ni,Cu,Ce,Ca,etc.is introduced as a combustion-supporting catalyst by the equal volume impregnation method,and the combustion performance of coal before and after desulfurization is compared.Preliminary determination of adding 0.1%of coal-fired composite catalyst?main chemical composition:Cu?NO₃?₂-38.4%,Fe?NO₃?₃-8.0%,Ce?NO₃?₂-3.5%,Mn?NO₃?₂-25.3%,Ca?NO₃?₂-5.0%?,the ignition temperature of low rank coal after desulfurization is reduced by about 10?,and the total sulfur emission reduction reaches about 60%.Based on the experimental results,a set of 5000t/a low-rank coal biochemical synergistic combustion and emission reduction pilot process was designed.The process flow includes batching section,desulfurization section,chemical combustion-supporting sulfur fixation section and tail gas treatment section.The crushed and sieved low-rank coal is desulfurized in the bioreactor,and the desulfurized low-rank coal filtered by the filter press is loaded with a coal-fired composite catalyst on the conveyor;the desulfurized coal loaded with the coal-fired composite catalyst enters the pulverized coal furnace for combustion Energy supply?heating?,after cooling and dust removal,the generated flue gas enters the denitration tower to complete the denitration operation.After the remaining tail gas reaches the emission standard,it is introduced into the bioreactor with an induced draft fan to achieve CO₂ recovery and utilization.According to the aforementioned process flow,the equipment design of the bioreactor and denitration tower was carried out,and the environmental impact,safety and economic evaluation of the designed low-rank coal biochemical cooperative combustion and emission reduction process were analyzed.