The report describes cold-modeling efforts directed toward the development of a solids-transport system capable of transferring 40,000 lb/hr of bed material between two operating fluidized beds of a chemically active fluidized bed (CAFB) gasification/desulfurization commercial demonstration unit. Three completely different configurations were tested, including at least one modification of each design. The optimum system would: transfer the required amount of bed material per unit time between the two fluidized beds; use the minimum quantity of activating gas; maintain the minimum activating gas pressure; allow only minimal gas leakage back into the supply bed; and provide an accurate and reliable control of transfer rate. A modified version of the third configuration tested (consisting of vertical and horizontal tubes with rectangular cross section and a multitube transport-gas sparger) was selected as coming closest to these specifications.