Abstract: A regenerative device can thermally treat gases. This device has a housing with a gas inlet and a gas outlet. A cage having a central interior is rotatably mounted in the housing between the inlet and the outlet. A plurality of gas permeable blocks are mounted peripherally in the cage around its central interior to provide therethrough: (a) an incoming flow path from the inlet to the central interior, and (b) an outgoing flow path from the central interior to the gas outlet. This incoming flow path within the blocks is non-converging. A drive motor can rotate the cage to move blocks successively past the inlet and the outlet.