城市污泥掺煤混烧特性及污染物排放研究

STUDY ON CO-COMBUSTION CHARACTERISTICS AND POLLUTANTS EMISSION OF MUNICIPAL SLUDGE AND COAL

采用20 k W多功能沉降炉管开展了城市污泥掺煤混烧试验,着重研究不同含水率、不同比例污泥掺混条件下,混合燃料的燃烧特性和尾气污染物的排放情况。结果表明,污泥主要失重区间在180~520℃,存在两个失重阶段,是挥发分的析出和燃烧的过程,污泥掺煤混烧可以改善燃料的着火性能和燃尽性能。污泥掺烧后尾气中NO_x排放浓度没有明显的变化规律,为350~450 mg/m^3;SO_2排放浓度随污泥掺混的比例增加呈线性增加;掺混10%污泥(含水率为30%)后,尾气二恶英的浓度约为单煤焚烧的2.4倍。各类污染物经过锅炉尾气净化系统处置均能达标排放,且本实验中污泥的最佳掺混比例为20%。

The tests of co-combustion of municipal sewage sludge and coal were conducted in a 20 k W multi-functional tube furnace,focusing on the combustion characteristics of the mixed fuel and the emission pollutants in the flue gas,in the cases of coal blending combustion of dried sludge,with different water contents and proportions. The results showed that the major weight loss of sludge was within the temperature ranged in 180 ~ 520 ℃,which covered two weight loss phases,namely resulting from the separation and combustion of volatile components. At the same time,the ignition and burnout performance of coal could be improved by co-combustion with dried sludge. Compared with single coal combustion,concentration of NO_x didn＇t change regularly,fluctuating from 350 mg/m3 to 450 mg/m^3; concentration of SO_2 increased with the increase of sludge mixing ratio; concentration of dioxin of 30% of sludge with water content of 10% combusted with coal was about 2. 4 times of that with single coal combustion. All the pollutants in the flue gas purified by treatment system could be discharged obeying the current national standard,and the optimum blending ratio of dried sludge should be 20%.