Mechanism Study On Flow Of CWM(Coal Water Mixture) Based On The Discontinuous Gradation

The coal water mixture (CWM) is made up of coal, additives and water mixture. And it can be used as the fuel in boiler and used as raw material in TEXACO gasification process. The high concentration CWM is advantageous to the promotion. Particle size distribution, additives and so on are the main factors influencing the concentration of CWM. So the particle size distribution is the important research direction of high concentration CWM preparation.For this reason, a study on particle size distribution technology of CWM was conducted through establishing the model and the new experimental methods.The result may be providing to CWM production as reference.CWM is made up of granularity of different particles and formation of the complex flow. The solid particles of CWM have both very coarse particles and fine cohesive particles. The fine particles to form a stable grout with water, Coarse particle relative to become a solid phase, so the compound flow also called two phase flow. Coarse and fine particles play different roles in fluid. Coarse particle size is relatively large in the fluid, the surface physical and chemical effects are negligible, therefore it constitutes a suspension with low viscosity, but it has a relatively high packing density of fine particles, so the coarse particle content on the concentration influence in CWM. Fine particles in the fluid have an obvious phenomenon of surface physical chemistry, can produce strong viscosity. So it can delay the vertical sedimentation of particles in CWM, and the content of fine particles can significantly change the fluid viscosity. So to control the content of fine particle in CWM has important significance.After understanding of coarse and fine particles, the model is established. Model is with the method of discontinuous gradation, then research the particle size distribution. The coarse particle size is as far as possible big, guarantee the fine particles can effectively fill between the coarse particles. Because studies have found that the particle size distribution of coal water slurry, the middle part of the particles of coal slurry concentration and the stability of contribution is very small. So CWM has a poor stability.According to the relationship between the three variables in the model, select a little experiment. Results show that Xinjiang Kuangou coal preparation of CWM, coarse particle average particle size of 1 mm, the thickness ratio of 6/4, fine particle average particle size of 0.025 mm, CWM concentration is 59%, the highest performance meet the requirement of gasification coal slurry. The results are further modified and perfected the theory model.Using two kinds of craft, Xinjiang coal preparation of CWM experiment was carried out, CWM concentration 51%,55% respectively, than the new technology of poor results.