A concept design for a spouted bed combustor/boiler was developed. The concept is based on a mechanical design derived from a fire-tube boiler and is thus restricted to relatively small boilers (say, 20,000 lb/hr and below) generating saturated steam at 250 psig or less. The spouted bed combustor/boiler is projected as having a number of advantages compared to conventional atmospheric fluidized bed combustion. These are greater turndown capability, improved calcium utilization, elimination of the need to withdraw solids, and a single point fuel feed. The spouted bed combustor shares the great fuel flexibility of the conventional fluidized bed combustor. Various coals, wood chips or waste and low grade solid, liquid and gaseous fuels can be burned. An R and D program to carry development of the spouted bed combustor/boiler through the PDU stage is provided. Also, recommendations for the design of a multiuse PDU support facility are made.