Abstract: A method and system for recovering heat from a pretreated hot biomass stream is described. The method and system for heat recovery includes a flash cooler connected to a direct contact condenser. A liquid portion of the hot biomass stream flashes into vapors upon the hot biomass stream entering the flash cooler. The flashed vapors are transferred to the direct contact condenser. The flashed vapors and an incoming cold biomass stream subsequently come into contact with each other in the direct contact condenser, thereby causing heat to be transferred from the hot biomass stream to the cold biomass stream. As the heat transfer occurs, the flashed vapors condense onto the surface of the cold biomass.