Fluidized-bed combustion: industrial application demonstration projects. Special technical report on Battelle's multi-solids fluidized-bed combustion process

The Multi-Solids Fluidized-Bed Combustion (MS-FBC) process consists of an entrained bed superimposed on a dense or conventional bed of selected high specific gravity material. Crushed coal and finely ground limestone are fed to the dense bed. The entrained bed is recycled continuously through the dense bed. The heat of combustion released in the dense bed is absorbed by the entrained bed material. Heat extraction from the process is accomplished by a heat exchanger in the entrained bed. No heat exchanger surface is located in the dense bed. Advantages of the MS-FBC process compared to conventional FBC processes are the higher fluidization velocities, 30 to 40 ft/sec, which permits higher heat release rates; excellent limestone utilization, with required Ca/S ratios of about 2, and increased start-up, turndown and standby capabilities which result from the absence of heat exchanger surface in the dense bed. Various experimental results involving erosion, heat transfer and sulfur retention at different conditions are reported.