半焦气力输送模型及在煤拔头中试装置中的应用

A Semi-coke Pneumatic Transmission Model and its Applications in a Coal-topping Pilot Plant

对半焦气力输送系统建立了一维数学模型,考虑了半焦气力输送中的固体颗粒运动、气固间的对流和辐射换热、半焦中残余挥发分的析出和燃烧、焦炭的燃烧、焦炭表面CO2的还原以及气相中CO的燃烧等过程。介绍了煤拔头中试装置及其系统构成,并用建立的模型对其物料输配系统进行数值模拟,得到半焦输送过程中的截面气固平均速度、沿程压力损失、气固两相温度等参数,为中试的进行提供指导。计算表明,在半焦气力输送过程中可忽略焦炭的燃烧,而挥发分的燃烧会导致气体温度由180℃升至800℃;气体速度增加,使压力损失增加,同时会引起管道磨损严重,因此中试装置中宜采用变管径的输送方法。

A one-dimensional mathematical model was established for a semi-coke pneumatic transmission system.In this connection,a variety of semi-coke pneumatic transmission processes were taken into account.They include:solid particle movement,convection and radiation heat exchange between gas and solid,precipitation and combustion of residual volatile component in semi-coke,combustion of coke,reduction of CO2 on the coke surface and combustion of CO in gas phase etc.The pilot plant of coal topping and its systematic configuration were described,and the model thus established was used to numerically simulate the material transmission and distribution system.A variety of parameters in the semi-coke transmission process were obtained,including sectional gas-solid average speed,en route pressure loss and gas-solid two-phase temperature etc.,providing guidance for the running of the pilot plant.The calculation results show that in the semi-coke pneumatic transmission process,the combustion of coke can be neglected.The combustion of volatile component can lead to an increase of gas temperature from 180 ℃ to 800 ℃.An increase of gas speed will increase the pressure loss.In the meanwhile,it can also result in a serious wear and tear of pipes.Hence,a variable tube-diameter transmission method is recommended for the pilot-plant test.