Investigation Of Sulfur-containing Particles Generation During Coal Combustion

It is well known that coal is the main consumption energy for a long time in ourcountry. Sulfur-containing particles generation in the process of coal combustion is one ofthe main sources of atmospheric particles, which has side effects on the human’s health andenvironmental quality. Therefore, it is significant to investigate the sulfur-containingparticles generation during coal combustion.Numerical simulation is the main research method. According to the structure ofcombustion equipment and operating conditions, the corresponding mathematical modelsand the control equations are selected. The concentration fields of soot particles, SO2,CO2and other substances are obtained by changing the furnace temperatures（400、600、800、1000、1200、1400、1600、1800K）、gas velocity（0.75、0.6、0.45、0.3、0.15m/s）andmolar fraction of O2（10、20、30、40、50、60%），which the analysis are based on. Theinfluences of different combustion conditions on sulfur-containing particles generation andsulfur-containing rate are investigated. By means of orthogonal simulation, further analysisof comprehensive influence among combustion conditions are got, then the effects ofdifferent parameters on sulfur-containing particles generation in the process of coalcombustion are obtained.Firstly, according to the comparison of variation of main productions in the furnacewith the generation of related substances during coal combustion actually, the two trendbasically coincide. It explains that the numerical simulation can describe the coalcombustion actually.Secondly, according to the process of flow rate variation of main sulfur-containingsubstances, the results suggest that the generated soot particles enrich a portion of the sulfurelement from coal. On the other hand, soot particles which not be oxidized after coalcombustion are an important source of sulfur-containing particles.Thirdly, furnace temperature, oxygen molar fraction and gas velocity at inlet haveeffects on the generation of soot particles. Total mass fraction and max mass fraction ofsoot particles during the furnace decrease with the increase of furnace temperature. It isdifficult for the generation of soot particles when temperature increases,so emissions ofsulfur-containing particles from soot particles decrease gradually at outlet. With theincrease of oxygen molar fraction, emissions of sulfur-containing particles from soot particles decrease gradually at outlet. The max mass fraction of soot particles during thefurnace decrease gradually with the increase of gas velocity at inlet.Fourth, by means of orthogonal simulation, the ranges of furnace temperature、oxygenmolar fraction and gas velocity are RA、RBand RCrespectively, which the relationshipamong them is RC>RB>RA. According to comprehensive analysis,oxygen plays animportant role in the generation of soot particles.Finally, the calculation and analysis of the sulfur-containing rate of soot particles atoutlet shows that the sulfur-containing rate of soot particles has slight changes with theincrease of temperature. In addition, the sulfur-containing rate under the oxygen molarfraction of0.2is larger than that under the oxygen molar fraction of10%. The higheroxygen molar fraction is in favor of the enrichment of S element for the soot particles, sooxygen is conducive to the generation of soot particles with higher sulfur-containing rate.Therefore, it is likely that oxygen and sulfur exist in the functional group of sootparticles after the interaction between them during the process of soot particles generated,which is an important process of sulfur-containing particles forming.