Experimental Study Of The Combustion Performance Of Lignite And Municipal Solid Waste

Coal dominates the world energy structure,and the lignite reserves is large compared with other coals.The yield of solid wastes grows largely in recent years,which can be regarded as a substitute for conventional fossil fuels.It's critical to investigate the combustion performance of lignite and solid wastes.The main purpose for this work is to address the combustion behaviors of lignite and solid wastes based on a thermogravimetric analyzer and a lab-scale fixed bed furnace.Based on a thermogravimetric technique and solid state reaction kinetics theory,the effects of microwave pretreatment and heating rate on combustion characteristics and kinetics of lignite/municipal solid wastes were obtained.The results indicated that the ignition temperature region of lignite was 357-376 ??which was higher than that of sewage sludge and eucalyptus bark.The average combustion rate of every sample increased with increasing heating rates.When the heating rate increased from 10 ?min-1 to 30 ? min-1,the average combustion rate of lignite,sewage sludge and eucalyptus bark increased about 2 times.The average combustion rate of lignite and eucalyptus bark increased after microwave pretreatment,while sewage sludge decreased.The ignition index of treated lignite,sewage sludge and eucalyptus bark increased by 38%,3.2%and 4.8%,respectively.The activation energy of lignite and sewage sludge increased after pretreated by microwave,while eucalyptus bark decreased.The activation energy of lignite and sewage sludge treated by microwave increased 32%and 7%,respectively.While the eucalyptus bark decreased about 7%.After microwave pretreatment,the hydroxyl and aromatic compounds contents of lignite increased,while the hydroxyl and aromatic hydrocarbons contents of eucalyptus bark and sewage sludge also increased.Meanwhile the inorganic carbonate and ash contents of sewage sludge also increased after preated by microwave.The non-thermal and iso-isothermal combustion experiments of lignite and municipal solid wastes were carried on the fixed bed furnace,the effects of microwave pretreatment,heating rate and combustion temperature on the combustion characteristics,kinetic characteristics and emission characteristics of the samples were obtained.The results indicated that the ignition index of lignite and sewage sludge were lower than eucalyptus bark,plastic,A4 paper,textile,rice and tissue at the same heating rate.The burnout index and comprehensive characteristic index of lignite are lower than solid wastes.The comprehensive characteristic index of tissue higher than others.With the increase of heating rate,the peak value of CO emission of lignite and municipal solid waste mixture increases,and the emission of SO2 from lignite and NO from municipal solid waste also increaseed with the increasing of heating rates.The average combustion rate and the burnout characteristic increased with the increasing of furnace temperature from 500 ? to 800 ?.The activation energy of lignite,sewage sludge and eucalyptus bark increased after microwave treatment.Compared with lignite,the mixture of lignite,sewage sludge and lignite,eucalyptus bark have higher combustion rate,which indicated that there was a synergistic effect in the combustion process of the mixture.With the increase of furnace temperature,the CO emissions of lignite,eucalyptus bark,lignite,eucalyptus bark mixture and municipal solid waste mixture decreased,and the combustion process more completed.The emission of NO also increase with increasing temperature.The study can provide some basic data for the further study and practical production of lignite and solid wastes.