Catalytic Caking Destruction And Gasification Of Caking Bituminous Coal

China’s coking industry produces a large amount of middlings with low volatile matter,high ash content,poor reactivity,and certain cohesiveness each year.These poorly-middlings are generally sold cheaply as boiler fuel,have high transportation costs and are economically poor.In view of the characteristics of certain adhesion for middlings,this study takes Pingdingshan lean coal and Yanzhou gas coal as the research object,and studies different catalysts（NaCl,KCl,Na₂CO₃,K₂CO₃,and CaO）and different catalyst loadings（0.001 mol,0.002 and 0.003 mol）and coal particle size（d<0.2mm and 0.5mm<d<1mm）on coal-visbreaking effect.The catalyst（K₂CO₃）which achieves the complete caking destruction effect and the coal sample corresponding to the particle size are selected to make coke sample under fixed temperature for 950℃.In the gasification experiment,the effects of coal char（2g,3g,4g and 5g）and carbon dioxide gas flow(0.5L·min^-1,0.75L·min^-1,1L·min^-1 and1.25L·min^-1)on the internal and external diffusion were first investigated.Then the experimental conditions were selected to eliminate the internal and external diffusion,and the different temperatures（750℃、800℃、850℃and 900℃）were studied.And the influence of different catalysts’loading capacity on coal char conversion rate and establishment of reaction kinetics model（homogeneous model and shrinking core model）.The results of the study show that:（1）The order of the coal samples caking destruction effect of different catalysts is K₂CO₃>Na₂CO₃>KCl>CaO>NaCl,and the coal samples with a particle size of less than 0.2mm can be completely broken by using K₂CO₃ loaded;the loading capacity of the catalyst is larger,the caking destruction effect is better.（2）When the coal coke mass is 3g and the carbon dioxide gas flow rate is 1 L·min^-1,the effect of the internal and external diffusion of carbon dioxide gasification in the fixed bed can be eliminated.（3）Higher is the temperature,greater is the catalyst loading capacity,then higher is the carbon conversion rate of char.Among them,the K₂CO₃ loading capacity per gram of Yanzhou gas coal is 0.003 mol and the temperature is 850°C,the reaction time is 60 minutes,and the carbon conversion can reach 100%.When the temperature is 900°C,the reaction time is 40 minutes,and the carbon conversion rate can reach 100%.When the K₂CO₃loading capacity per gram of Yanzhou coal is 0.002 mol,the reaction time is 50 minutes,and the carbon conversion can reach 100%.（4）The homogeneity model and the shrinking model have a higher correlation with the forecast of lean coal gasification kinetics in Pingdingshan,with a correlation coefficient of more than 0.98.The correlation of the prediction of gasification kinetics in Yanzhou is slightly lower,and the correlation coefficient is about 0.95.