Advanced flash exhaust heat recovery

Abstract

Waste heat is extracted in two stages from the exhaust (20) of a biomass dryer (14) in a grain alcohol plant (10). A boiler circuit (56) provides a first steam at high pressure. A first energy recovery circuit (36) extracts heat from the exhaust via a non-contact heat exchanger (24) and provides a second, relatively lower pressure steam (78), thereby bypassing a portion of the boiler circuit. Working fluids in the boiler and first energy recovery circuits are maintained within boiler water quality specifications and are intermixed to allow the production of the second steam without a pressure reduction device. A second energy recovery circuit (44) extracts heat from the exhaust downstream of the first energy recovery circuit using a direct contact heat exchanger (38) and provides a non-boiler quality heated fluid (52), which may be a heated liquid or a third steam.

Dependencies are inferred from the claim text.