CO2/N2高压密相输送弯管压降特性实验研究

在高压密相气力输送实验装置上,研究了兖州烟煤在CO2和N2作为输送介质时,输送管路中水平弯管和垂直弯管压降的特性,以及云南褐煤煤粉含水率对水平弯管和垂直弯管压降的影响.结果表明:在系统压差相同,输送介质为CO2和N2时,水平弯管压降随表观气速U的下降而逐渐减小,CO2时煤粉体积分数比N2时小；垂直弯管压降随U的下降而减小,当U下降至5.3 m/s时,N2下垂直弯管压降达到最小值,CO2下没有出现压降最低拐点,CO2时垂直弯管的压降比N2时略高.由实验还发现,煤粉中水的质量分数增加会导致煤粉颗粒间相互粘黏、团聚,致使N2和CO2下水平弯管压降增大,垂直弯管压降小幅降低.通过模化理论和实验分析获得了不同输送介质下水平、垂直弯管的固相附加压损系数的拟合公式,由该式得到的弯管压降与实验吻合良好,误差在±5％以内.

Experimental Research on Pressure Drop in Elbows in Dense Phase Pneumatic Conveying of Pulverized Coal at High Pressure Using CO2/N2 as Carriers

The pressure drop characteristics in the horizontal and vertical elbows of the pipeline for pulverized Yanzhou bituminous coal using CO2 and N2 as conveying gas separately were investigated at high operating pressures in the experimental equipment for dense phase pneumatic conveying.Then the effect of the moisture content of Yunnan lignite powder on pressure drop in the horizontal and vertical elbows was studied.The experimental results show that the pressure drop in the horizontal elbow decreased with the decrease in the apparent gas velocity using CO2 or N2 at the same total conveying differential pressure,and the concentration of the powder with CO2 was smaller than that with N2.The pressure drop in the vertical elbow decreased with the decrease in the apparent gas velocity,and the pressure drop in the vertical elbow using N2 as conveying gas reached the minimum value when the apparent velocity dropped to around 5.3 m/s,while the pressure drop change in the vertical elbow using CO2 as conveying gas had no such inflexion.Moreover,due to the change of the elbow location,the pressure drop in the vertical elbow with CO2 was higher than that with N2.Further,the pressure drop in the horizontal elbow increased with an increase in the moisture content of pulverized coal with CO2 or N2 because of the powder adhesion and agglomeration caused by the increasing moisture content.Generally,the pressure drop in the vertical elbow decreased slightly with an increase in the moisture content.The regression formulae were obtained to predict additional pressure loss coefficient of the solid phase in horizontal and vertical elbows with different conveying gas on the basis of the modeling theory and analysis on the experiment,and the predicted results are in accordance with the experimental data with the relative error of within ±5%.