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研究报告

The co-combustion characteristics of coal and paper mill sludge and its kinetics

摘要：采用综合热重分析法,在不同升温速率及泥煤不同比例混合条件下,开展造纸污泥、煤及泥煤混合物的燃烧热重实验研究.结果表明,造纸污泥的热重曲线存在3个明显的失重区域,分别与2个挥发分析出阶段和1个固定碳燃烧阶段相对应.泥煤混合燃烧过程中,造纸污泥和煤基本保持各自的挥发分析出特性,其燃烧曲线基本位于污泥和煤燃烧曲线之间,且混合试样微熵热重(DTG)曲线的变化趋势与组成比例较大的成分的DTG曲线变化趋势更为接近.泥煤混合后其综合燃烧特性指数S有所下降,这说明挥发分含量高对应的燃烧特性好;随着升温速率的提高及煤比例的增加,燃尽指数C_b有上升的趋势.采用积分法(Coats-Redfern方程)计算得到各阶段燃烧反应的机理方程及相应的活化能参数,在第一阶段的挥发分析出燃烧峰前,活化能E值随着泥煤中粉煤比例的增加而降低,用方程f(α)=(1-α)^0.5来描述造纸污泥及泥煤混合试样的燃烧机理较为适合.

Abstract：The combustion characteristics of paper mill sludge, coal and blends of them with different proportions were studied by thermogravimetric analysis (TG-DTG) at different heating rates. Three obvious temperature zones existed in the paper mill sludge combustion curves, which corresponded to two stages of devolatilization and fixed carbon combustion, where the weight of sludge was lost promptly. During combustion of blended samples, the paper mill sludge and coal basically maintained their own devolatilization characteristics. The combustion curve of sludge-coal blends exhibited a transitional behavior from that of sludge to that of coal. The DTG curve of the blends was closer to that of the material in larger proportion. The comprehensive combustion characteristic index S of the sludge-coal blends declined, which demonstrated that samples with higher volatility had better combustion characteristics. The burnout index C_b increased with the heating rate and the proportion of coal. Both the combustion reaction equation during the different combustion periods and the corresponding kinetic parameters were calculated by the Coats-Redfern equation. Before the peak of combusted devolatilization in the first phase, the activation energy decreased with the increasing proportion of pulverized coal, and it was appropriate to describe the combustion mechanisms of paper mill sludge and sludge-coal blends by the equation f(α) = (1-α)^0.5.