Co-pyrolysis Behaviors Of Low Rank Coal With Coal Tar And Residual Oil

Coal pyrolysis was operated in a fixed bed reactor to investigate the influence of coal type,temperature,reaction time,atmosphere,heating rate and solvent pretreatment,then tar and gas were analyzed by column chromatography and GC respectively.The results showed great difference in yield,distribution and composition of pyrolysis products generated from different coals.The yield of coal tar reached the highest value at 600 ?,and weight loss stopped increasing after 15 minutes.The weight loss of coal pyrolysis at the atmosphere of CO2 was lower than that of N2,which indicated that CO2 has inhibitory effect.The weight loss remained with the increasing of heating rate,while the temperature corresponding to the maximum weight loss rate increased.Solvent pretreatment by tetralin and methylnaphthalene oil could change the coal structure,which resulted in the increasement of weight loss of pyrolysis.Meanwhile,the pretreatment effect of tetralin was better than that of methylnaphthalene oil.The results of co-pyrolysis of Huainan coal with low temperature coal tar showed that co-pyrolysis could make tar yield increase,and the experimental value was higher than the theoretical value when coal tar or its distillation residues:Huainan coal was less than 5:100,which indicated synergistic effect on tar yield.The most significant synergistic effect appeared when the blending ratio was 1:100 with coal tar yield relatively increasing 7.66%and 7.39%respectively.However when the blending ratio was 10:100,there was an inhibitory effect on tar yield due to polymerization.The existence of synergistic and inhibitory effect was proved by the analysis results of TG,EPR,and microscope.The results of n-hexane soluble fraction,GC/MS,1H-NMR showed the quality of co-pyrolysis tar was improved.The yields of toluene,dimethylbenzene,trimethylbenzene,phenol,cresol,dimethylphenol increased.Meanwhile,the result of GC analysis showed that there were more H· and CH3·fragments to be stabilized by fragments generated from coal pyrolysis and formed medium molecular tar.? C1-C4 contents in gas increased,while the content of CO and CO2 decreased with the increasing of additives ratio,which resulted in the increasement of higher heating value of gas.The co-pyrolysis of Huainan,Juger and Daliuta coal with residual oil could increase tar yield owing to synergistic effect.However,the effect differed because of different coal structure.The quality of tar was improved as the percents of n-hexane soluble fraction and aliphatics increased.The GC analysis results showed ?C1-C4 content increased while the content of CO and CO2 decreased with the residual oil ratio increasing.Furthermore the concentration of CH4 in ? C1-C4 increased,though that of C2?C3?C4 decreased,which illustrated that residual oil had the effect of hydrogen-donor during co-pyrolysis resulting in an improvement of tar yield and its quality.The mechanism of synergistic effect was similar to that of co-pyrolysis of Huainan coal with low temperature coal tar.