Ash Deposition Mechanism Research Of High Alkali Metal Coal And Coal Water Slurry

Traditional coal industry that high risk, pollution, extensive, disorderly mode of development has long been criticized. The high efficency and clean coal utilization should be vigorously promoted. Coal resources in Xinjiang is abundant and has a low ignition point, high burning rate, medium calorific value, low pollution element content and low mining cost, which show excellent performance as coal for power plants and clean raw material, and consistent with the clean coal utilization policy. However, Xinjiang coal also known as high alkali metal content, burning in the boiler will cause serious ash deposition on the heated surface, to bring a great threat to the safety of production. For the efficient use of Xinjiang high alkali metal coal resources, this paper has done the following two aspects. One is that research on ash deposition mechanism in heat transfer surface (HTS) taking Zhundong coal mixed burning on power plant as an example. The other is that "Xinjiang coal and oil field sewage" for preparing coal water slurry (CWS) is proposed and validated its feasibility.About ash deposition mechanism, the main conclusions are as follows. Slagging experiments shows that slagging rate is enhanced as result of the formation of stickiness surface. Outer layer shows more serious sintering and conversion of crystal phases to amorphous phases compared to inner layer. At high temperature HTS, albite, anorthite and other phases helped eutectics precipitate to take shape, which sticked to fly ash particles and formed indurate bulk ash deposits. At low temperature HTS, sulphur-containing species condensed from flue gas to form deposits with evidence that the main crystalline phase was anhydrite. At economizer HTS, The deposits consisted of amorphous phases carried by flue gas were loosely bonded. Calculated results by Factsage basically agreed with phase composition of actual samples and were of assistance to mineral conversion analyses.About " Xinj iang coal and oil field sewage" for preparing coal water slurry (CWS), the main conclusions are as follows. The concentration of coal water slurry, apparent viscosity and stability meet the requirements of industrial application. Slag-tap can be possibly formed by several judgements. CWS combustion test shows that part of the slurry particles burning on slag-tap cyclone furnace wall and part of the slurry particles in the combustion space, and continue to the horizontal flue. In comparison, the combustion temperature is higher with the centralized air distribution and higher quantity of CWS and higher calorific value.The conclusion that CWS was burnned completely can be drawn by the low carbon content of liquid slag and fly ash, the flue gas oxygen content was at 4%-7%, and CO concentration was less than 60 ppm.30 min after cast slurry, liquid slag period the overall flow smoothly, with continuous burning, because of the alkali metal in the wall deposition film formation, prevent liquid slag liquid slag flow sluggish acerbity. In general, the scheme of "Xinjiang coal and oil field sewage" has application value.