The Preparation Of Coal Water Slurry Of Low Rank Coal For Coal Gasification Using The Particle Size Distribution Technology

Three kinds of low-rank coal samples were chosen and the proximate analysis, ultimate analysis and HGI were analyzed to investigate the slurryability of low-rank coals. Different particle size distribution coal samples were obtained and screened by grinding and sieving method. The characteristics of coal water slurry (CWS) prepared by blending different particle size distribution coal samples and the influence of particle size distribution on low-rank coal-water slurry were studied. Gray correlation analysis method was used to study the relationship between particle size distribution parameters and the maximum solid concentration of CWS. Based on the influence rules of particle size distribution of peak parameters on the maximum solid concentration of CWS, the optimal size distribution of low-rank coal to prepare CWS was put forward. Finally, the realization way of improving low-rank coal-water slurry solid concentration by particle size distribution technology was explored. The following conclusions could be reached:1. The characteristics of the CWS were influenced significantly by particle size distribution. The maximum solid concentration of CWS increased firstly and then decreased as the weight proportion of fine particle (size<75μm) increased from10%to90%. The concentration of CWS reached to maximum as the weight proportion of fine particle was about50%. The fine particle and reasonable size distribution can improve the fluidity and the rheological behavior of CWS.2. The maximum solid concentration of CWS gradually increased as bi-modal peaks spacing increased. The concentration of CWS was affected significantly by the weight proportion of different particle size distribution coal samples. According to the results of CWS prepared by different particle size distribution coal samples, the ideal bi-modal distribution model with the smaller size mode at5～25μ, the lager size mode at250-450μm and the trough of two peaks at25～75μm for preparing low-rank coal-water slurry was put forward. The two peaks area ratio of the ideal bi-modal distribution for preparing low-rank coal-water slurry is from0.7to1.5.3. The particle size distribution of the GE (Texaco) gasification process requirements could be optimized by adding micronized particle with the median diameter (D50) at about10μ. The solid concentration could be increased by2%～3%with the addition of20%-30%micronized particles.