The Experimental Study Of Furfural Residue And Chongqing High Sulfur Content Coalco-combustion In Circulating Fluidized Bed

In recent years, due to the rapid development of economy, the consumption of fossilfuels is increasing, and the environmental pollution is getting worse. Biomass energy isconsidered as an environmental friendly and renewable energy, and its development andutilization will be an important guarantee for the future energy supply. Furfural residueis a kind of biomass remnants after furfural is extracted from corncob. The annualoutput of furfural residue is huge but lack of use. The large amount of accumulation offurfural residue will cause pollution to the environment. Using furfural residue asbiomass fuel can replace some fossil fuel consumption and reduce its damage to theenvironment.Circulating fluidized bed boiler combustion technology is a kind of lowtemperature and high efficiency combustion mode. Its ability to adapt to fuel changesand the pollution control capacity is excellent, so it is the best combustion mode offurfural residue and other biomass fuels. As the volatile and alkali metal content offurfural residue are relatively high, burning furfural residue alone may cause problemslike unstable combustion, slagging problem of bed material, ash corrosion at the heatingarea and so on. Burning furfural residue mixed with coal is the more efficient utilizedway of furfural residue.And high sulfur content coal is the mainly coal type of the minein southwest region. Furfural residue and high sulfur content coal co-combustion canguarantee the stability of furfural residue burning and reduce the emission of pollutantsof high sulfur content coal. The combustion characteristic and emission of pollutants offurfural residue and Chongqing high sulfur coal mixed in circulating fluidized bedcombustion are still lack of research.This paper firstly study the thermo gravimetric analysis about furfural residue,Chongqing high sulfur content coal and their three kinds of mixed fuel samples inwhich the furfural residue mass content is10%,20%,30%respectively. In the analysis,the combustion process of each sample is studied to get the combustion characteristicsand the influence on combustion due to the different mixture ratios; Then four kinds ofmixed fuels, which are coal respectively mixed with10%,20%,30%and50%furfuralresidue, are burnt in a small scale CFB combustor to study the stability andcharacteristics of combustion. The influence on combustion and emission of pollutantsare also studied under different mixture ratios and different fluidizing velocities. The studies are likely to provide experimental reference for using furfural residue as fuelrationally. The result of the study shows：①The test results of Thermo gravimetric analysis show that the ignitiontemperature of furfural residue is relatively low. After the furfural residue is mixed, theignition of the coal become earlier. The coal and furfural residue can mutually promotecombustion. The ignition performance, burn-out performance and combustioncharacteristics of the samples are improved.②In thermo gravimetric experiments, when the heating rate is higher, thecombustion rate of samples are also higher, but the ignition temperature of samplesdecrease. Due to the reason of thermal lag, the burnout time delays relatively, and theburnout temperature increases.③Coats-Redfern integral method and distributed activation energy model are usedto calculate the combustion activation energy. When furfural residue and coalco-combustion, the reactions are divided into volatile segment and the fixed carbonsegment, which have different orders of reaction. As the heating rate, furfural residueratio or the combustion conversion rate increases, the activation energy decrease. Theresults of the activation energy by using Coats-Redfern integral method and distributedactivation energy model are consistent, and the accuracy of the results can be proved byeach other.④In the CFB combustion experiments, all the mixed fuel samples, which furfuralresidue blending ratio were10%、20%、30%、50%, can stably ignite and combustion.⑤In the CFB combustion experiments, as furfural residue blending ratio increases,the upper furnace temperature will increases. The furnace temperature become uniformand the high temperature combustion zone move to the upper part of the furnace. As thefluidizing velocity increases, the temperature of the mid upper furnace also increases.⑥As the blending ratio of furfural residue or fluidization velocity increases, theupper part of the furnace pressure will increase. The main reason is the increasing of theparticle concentration at the upper part of furnace.⑦As the blending ratio of furfural residue increase, the carbon content of fly ashwill decrease, but the particle emission concentration will increase.⑧As the temperature of dense zone of furnace increase, the oxygen content in rearsmoke channel decrease, and the CO, SO2, NOxemission concentration will increase.As the blending ratio of furfural residue increase, CO emission concentration will increase, but SO2, NOxemission concentration will decrease.