(71b) Effect of Physical Properties of Coal Gasification Fine Ash on Its Wettability

Optical contact angle measurement was used to measure the contact angle of different size of fine ash particles. The fractal characteristics of fine ash was studied from size and surface porous structure based on fractal theory and effect of fractal dimension on wetting ability of fine ash was also investigated. Scanning Electron Microscope (SEM), Fourier Transform Infrared Spectroscopy (FTIR), X-Ray Diffraction (XRD) and humidity measuring instrument and other experimental measurements have been applied to study the effect of physical characteristic on fine ash wettability. The research shows that wettability increases with the fractal dimension of particle size and particle surface. With the particle size decreasing, surface roughness and structure irregularity decrease and the amount of spheroidal particle increases. The content of unsaturated functional group increases and the hydrophilic mineral substance decreases with particle size decreasing, resulting in the decease of its wettability. For particles larger than 40μm, the wettability increases with the increase of moisture content. On the contrary, for particles smaller than 40μm, the wettability increases at first and then decreases with the increase of moisture content.