A continuous flow expander for expanding particulate material, more specifically for grain or cattle fodder, is provided whereby material to be expanded is transported in a substantially continuous manner through a pressurized region wherein it is heated, steamed and pressurized by a counterflow of dry steam created from available city water by a recirculating steam boiler. The material is then ejected by another flow of dry steam created from available water into a lower pressure region for expansion. Enthalpy in the ejection region is automatically maintained within a predetermined range, for grain or cattle fodder from 450 to 750 BTU per pound of moisture being ejected, regardless of the moisture content of the material, by varying steam boiler output and, if necessary, material flow rate. An expanded product requiring no further drying prior to use or storage is thereby provided with minimum energy use.
