Preparation and characterization of new porous ceramic filters for hot gas clean-up
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The excellent particulate removal efficiency of ceramic candle filters has prompted efforts to develop a more durable and economical alternative to existing ceramic candle filters. Porous ceramic candle filter elements were successfully fabricated from calcium aluminate cement, calcined fireclay aggregate, and organic pore formers using refractory concrete casting techniques. Methods used to characterize the porous ceramic filter elements included determination of pore size and distribution, permeability, resistance to alkali attack, and mechanical strength. Various pore formers and casting, curing, and sintering conditions were examined to produce highly permeable and structurally sound filter elements.
The optimized fabrication procedure produced porous ceramic candle filter elements with pore diameters between 20.3 to 43.1 tlm, porosities of 38 to 60%, and pressure drops of 3 to 24 mbars at a face velocity of 100 mjh. These characteristics are comparable to existing ceramic filters which are noted for their > 99% collection efficiencies of submicrometer-sized particles, but short-term durability in advanced coal combustion clean-up systems. Test specimens of the alumino silicate refractory concrete proved more durable by showing no severe attack following exposures to alkali-containing atmospheres at 700-1000Â°C. The strength of the cast samples ranged from 200 to 1139 psi depending on the relative densities and pore formers. Porous fliter elements with different porous structures, permeabilities, and shapes can be easily produced with this technique.
- Masters Theses