Steam-jet heat recovery in a lumber dry kiln

Graduation date: 1980Lumber drying accounts for about 70 percent of sawmill energy\ud requirements. Significant recovery of energy used to dry lumber\ud would result in significant energy recovery for the mill. This is\ud desirable because of today's high cost of energy. The objective of\ud this study was to recover some of the energy required to dry Douglas-fir\ud [Pseudotsuga menziesii (Mirb.) Franco] with a superheated steam\ud schedule by compressing kiln exhaust in a steam-jet thermocompressor\ud and condensing this compressed steam in the kiln steam heating coils.\ud Once the steam recovery was determined, an economic sensitivity\ud analysis was performed.\ud The recovery system resulted in approximately 20 percent recovery\ud of the steam required to dry the charge of lumber. The economic\ud sensitivity analysis showed that the recovery system is sensitive to\ud the size of the kiln on which it is used, and steam value factors\ud which include the fuel cost to produce steam, steam recovery, and\ud the steam flow requirement of the kiln