ALKALI-INDUCED AGGLOMERATION OF SOLID PARTICLES IN COAL COMBUSTORS AND GASIFIERS

The effect of alkali adsorption on the agglomeration of particles of bauxite, kaolinite, emathlite, lime and two types of coal ash is studied. An agglomeration (adhesion) temperature is defined which characterizes the adhesion propensity of particles. An experimental technique is developed to measure this agglomeration point in situ and without sample quenching or removal. The effect of alkali adsorption on the agglomeration characteristics of the substrates is determined. The agglomeration temperature for all substrates decreases a:, alkali content increases. At low loadings the alkali adsorption enhances particle agglomeration by forming new compounds of lower melting points. At high concentrations, the agglomeration point of all substrates approaches the melting point of condensing alkali. Under these conditions, adhesion and agglomeration are caused by a layer of molten alkali which covers the exterior of the particles.