Studies on Coal Slurry Fuel(Part 4). Effects of Additive and Particle Size Distribution on Characteristics of Coal-Water Mixture(CWM).

Abstract

Six anionic polyelectrolytes (poly(styrenesulfonate) (PSS), three poly(isoprenesulfonate)s (PIPSs), a copolymer of sodium poly(methacrylate) and poly(methacrylate) ester (PMA), and a melamineformaldehyde condensate sulfonate (MFCS)) were tested for additives for coal-water mixtures (CWMs), which were, prepared either by dry grinding method or by wet grinding method, and evaluated by their viscosity and storage stability. A poly(isoprenesulfonate) PIPS-1 was found as effective as PSS, which is now most commonly used in practical CWM processes. A new parameter is proposed. The parameter is defined as the minimum quantity of liquid (water: ethylene glycol 4:6) necessary for a certain amount of powdery coal to form a putty-like lump when the liquid is titrated on the powdery coal. Liquid-absorption reveals the quantity of the liquid that is tightly retained on the surface of coal particles and locked in the apertures of the particles. Various powdery coals, for which their mean particle sizes were adjusted to be about the same while their size distributions remained different, were prepared. For CWMs prepared from powdery coals, when the size of coal particles was more distributed, the liquid-absorption was reduced and the CWM viscosity was decreased. By use of powdery calcium carbonates, it was found that liquid-absorption for the powders was influenced both by the magnitude of the apertures of the particles and by the specific surface area.