Abstract: A material transfer system for transferring particulate material from a first fluidized bed to a second fluidized bed includes a rectangular, vertically-aligned downcomer communicating at its lower end with a rectangular, horizontally-aligned exhaust duct. A sparger assembly having plural gas injection tubes communicates with the exhaust duct and is provided to direct horizontally spaced gas flows into the exhaust duct. A control valve coupled to the sparger assembly selectively starts and stops the flow of an activating gas to define gas flow pulses having a selected pulse duration. Particulate material from the first fluidized bed enters the downcomer through a catch pocket formed at the upper end of the downcomer and fills both the downcomer and the exhaust duct. The gas flow pulses entrain the particulate material in the exhaust duct and transport it through an outlet into the second fluidized bed.