Agglomeration characteristics of silica sand-rice husk ash mixtures at elevated temperatures
- Technical Univ. of Nova Scotia, Halifax (Canada). Agricultural Engineering Dept.
Rice husk, a major by-product of the rice milling process, can be a significant energy resource in rice producing countries because of its high energy content. Fluidized bed gasifiers have been proposed for the recovery of energy from rice husk. The major advantage of fluidized bed gasifiers over fixed bed gasifiers is the high mass and heat transfer capability due to very high percentage of inert bed material such as silica sand. In addition, the vigorous mixing and agitation of solid particles in fluidized beds promote a uniform temperature distribution and a high conversion efficiency. However, attempts to utilize rice husk as a feed in fluidized bed gasifiers have been unsuccessful because of the high ash content of rice husk that may result in the agglomeration of inert bed materials at high temperatures. In this work, the effect of rice husk ash content on the agglomeration characteristics of silica sand was investigated at various temperatures using a muffle furnace. A light microscope, an environmental scanning electron microscope, and an energy dispersive X-ray analyzer were used to characterize the structural changes and elemental makeup of the samples. There was no indication of agglomeration below 850 C, but at temperatures of 850--1,000 C the silica sand loosely agglomerated in the presence of rice husk ash at all levels of ash content. The effect was more pronounced at 1,000 C. The chemical interaction of the SiO{sub 2} and the low melting temperature mineral oxides present in notably low concentrations in rice husk ash, appeared to be the mechanism resulting in the formation of the loose agglomerates.
- Sponsoring Organization:
- USDOE
- OSTI ID:
- 634716
- Journal Information:
- Energy Sources, Vol. 20, Issue 7; Other Information: PBD: Aug-Sep 1998
- Country of Publication:
- United States
- Language:
- English
Similar Records
Mathematical modeling of a fluidized bed rice husk gasifier: Part 2 -- Model sensitivity
Recovery of silica from the gasification of rice husks/coal in the presence of a pilot flame in a modified fluidized bed