Study On Influencing Factors Of Fly Ash Adhesion Features And Simulating Process Of Shell Coal Gasification

Fly ash adhered and deposited on syngas cooler in Shell coal gasification process, then threatened the safety, stability and economic profits of the coal gasification units. So studying on fly ash adhesion and deposition was very important.In this paper, two representative fly ashes selected from Liuer and Yunnan coal were used in the study. The particle size distribution, chemical composition, surface topography of fly ash samples were studied by JX-2000 microscopic image analyzer, X-ray fluorescence spectrometer and scanning electron microscopy respectively.The mechanisms of adhesion and deposition were analied. Some primary results were obtained as follows:1. The particle size of fly ash which produced from Liuer coal and Yunnan coal were concentrated on less than 2μm.The weight percent of particles in 0～1μm gradually decreasing in A11 to A15. The number of particle which diameters between 0～1μm in Liuer fly ash was much larger than in Yunnan fly ash, while the number of particle which diameters between 1～2μm in Liuer fly ash was much smaller than in Yunnan fly ash.Small diameters of fly ash could be caused fly ash deposited on syngas cooler.2. The CaO and Fe2O3 enrichment coefficients of these two different fly ashes were different. The CaO enrichment coefficient of Yunan fly ash was 2.13 times as high as that of Liuer and Fe2O3 enrichment coefficient was 0.33. Those two alkali metal oxide enrichment coefficients difference was one of reasons why the level of ash deposition difference.3. The micromor-phologies of fly ash was spherical. The particle size was small and the specific surface area was big.The adhesive force was formed by the molecular surface tension. The forces analysis and the adhesion model established based on the physicochemical changes of coal gasification process. It could be describe the existent forces in different areas and the process of fly ash particle deposition.