The report describes the third phase of studies on the CAFB process for desulfurization/gasification of heavy fuel oil in a bed of hot lime. Major conclusions relating to process performance and operability are: (1) water, either in the fuel or in the fluidizing air, has a strongly adverse effect on desulfurizing efficiency; (2) good desulfurizing efficiencies are obtainable at very low stone replacement rates; (3) process performance can be expressed as a statistically derived equation; (4) a burnback burner is feasible for coke removal; (5) SO2/stone disposal by sulfation is not feasible, but dead-burning looks promising; and (6) most trace elements are retained in the bed. Among tasks included in this phase were: (1) batch reactor evaluation of three limestones and gasification/desulfurization of a vacuum bottoms fuel; (2) two pilot plant runs using deep beds and demonstrating improved operational techniques; (3) development of a statistical method for analyzing results of the two pilot plant test runs and reconciling them with earlier results; (4) sulfation of bed material as a means of disposing of SO2 and spent lime; (5) dead-burning as a means of treating spent bed material prior to disposal; (6) retention of the bed material of a wide range of trace elements contained in the fuel; and (7) demonstration of a burn-back burner to overcome coke lay-down in cyclone inlets.

Prepared under contract no. 68-02-1359, ROAP no. 21ADD-BE, program element no. 1ABO13. Issued Sept. 1976. Includes bibliographical references.