This paper discusses the effect of the second (heterogeneous) phase on the extent of heat recycle, lowering of the lean flammability limit, stability and performance of a spouted-bed combustor. Experiments suggest that the extent of heat recycle. and therefore the lowering in the lean flammability limit, is controlled by both particle circulation rate and particle physical properties. This concept of heat recycle can be utilized in the burning of low heating value chemical and toxic wastes. The stability of a spouted-bed combustor depends upon the geometric design ratios d(i)/D-c, d(i)/d(p), and h(d)/H, based on studies with columns of two different sizes burning propane. The introduction of a draft tube improves the flexibility of the combustor in terms of residence time control and bed stability. A well-designed draft tube spouted bed combustor can yield a destruction and removal efficiency, i.e. conversion, of greater than or equal to 99.99.