The Wormser Grate is a two stage fluidized bed combustor designed to retrofit industrial boilers to burn coal in an environmentally acceptable manner. A three million Btu/h. Wormser Grate was retrofitted to an old firetube boiler, and used to provide space heating for a United Shoe Corporation Plant in Beverly, Massachusetts. A one year, Department of Energy funded program was undertaken to provide valuable experience in operating an F.B.C. in an industrial setting. An instrumentation and data gathering system was assembled, and computer techniques developed to monitor F.B.C. performance. The operability of the unit was proven with 1000 h of continuous operation, and performance testing indicates that the Wormser Grate exceeds pollution regulations.