Preparation and Pumping Characteristics of Coal Water Paste Fired Into PFBC

Water seepage properties of coal water paste (CWP) under pressure are studied experimentally; the influences of particle size distribution, water content and limestone on the pumping properties of CWP are analyzed. By analyzing the pile pattern of coal particles and flowing properties of CWP in pipe, a novel method for evaluation coal water paste pumpability based on combination of the slump index and the amount of water seepage under pressure is proposed. It is found that the optimum mass ratio of coarse coal powders to the fines is 60:40 for Xuzhou coal of 0∼6 mm, coal water paste pumpability can be described by two indices, namely the slump index and the total water seepage quantity under pressure. The CWP with a good pumpability has a slump in the range of 80∼240mm. The corresponding relative water seepage rate and water seepage quantity are S₁₀ ≤ 40% and V = 70∼110 ml, respectively.