掺烧不同种类污泥锅炉的燃烧特性

Eddy-dissipation model based numerical simulation on co-combustion characteristics of a coal-fired boiler co-firing with different kinds of sludge

对某台420t/h四角切圆燃煤锅炉进行了单煤燃烧和2种污泥在不同含水率和质量配比下的掺烧数值模拟研究。采用涡耗散模型(EDM)模拟气相湍流燃烧,研究多工况下的炉内流动、燃烧、污染物排放和燃料总燃尽率、煤粉颗粒燃尽率等。结果表明:EDM能较好地模拟污泥配比和含水率对锅炉燃烧及污染物排放特性的影响;随着掺混比和污泥含水率的增加,水蒸气吸热造成炉膛整体温度水平下降,且燃料总燃尽率呈下降趋势;掺烧污泥后,由于燃料型NOx生成量的减少,锅炉总NOx排放质量浓度明显呈下降趋势;由于不同污泥中硫含量各异,2种污泥掺烧后锅炉SO2排放特性差异较大。

Taking a 420 t/h tangentially coal-fired boiler as the object,numerical simulation using eddy-dis-sipation model （EDM）was carried out to evaluate the combustion characteristics of pure coal and mixtures of coal and sludge with different moisture contents and mass ratios.Several parameters under various oper-ation conditions were investigated,such as the flow field,combustion,pollutants emission characteristics, total fuel burn out rate and coal particle burnout rate during the gas phase turbulent co-combustion.The results show that,the EDM can reasonably simulate the effects of mass ratio and moisture content of sludge on the combustion characteristics and pollutants emissions after co-firing.With the increasing mass ratio and moisture content of sludge,the vapor absorbed the heat,causing a decrease in furnace tempera-ture,thus the total fuel burn out rate decreased.After the sludge was co-fired,the formation of fuel-NOx reduced,leading to an significant reduction in total NOx emission.The SO2 emission characteristics were obviously different in co-combustion of different kinds of sludge.This is mainly because the sulfur content in different kinds of sludge varies from each other.