Abstract: A heat recovery system for at least partially cooling and at least partially cleaning an exhaust stream of hot air from a heating operation which is contaminated with vaporized, condensable liquids and with finely divided particulate solids comprising (a) a first indirect heat exchange means for partially cooling the hot exhaust stream with a fresh stream of cold air to a temperature not significantly above the dew point of vaporized liquids entrained in the hot air stream and for partially heating the fresh stream of air, (b) solids collecting means for centrifugally separating a substantial portion of the finely divided solids from the partially cooled exhaust stream and (c) second indirect heat exchange means for further cooling the exhaust stream to a temperature below the dew point of vaporized liquids initially contained therein to thereby liquefy a significant portion of the vaporized liquids and to further heat the stream of fresh air.

Abstract: A heat recovery method for at least partially cooling and at least partially cleaning an exhaust stream of hot air from a heating operation which is contaminated with vaporized, condensable liquids and with finely divided particulate solids comprising (a) a first indirect heat exchange means for partially cooling the hot exhaust stream with a fresh stream of cold air to a temperature not significantly below the dew point of vaporized liquids entrained in the hot air stream and for partially heating the fresh stream of air, (b) solids collecting means for centrifugally separating a substantial portion of the finely divided solids from the partially cooled exhaust stream and (c) second indirect heat exchange means for further cooling the exhaust stream to a temperature below the dew point of vaporized liquids initially contained therein to thereby liquefy a significant portion of the vaporized liquids and to further heat the stream of fresh air.