SPRAY DRYER EXHAUST TREATMENT AND ANAEROBIC DIGESTER

摘要

A spray dryer exhaust gas treatment system and process recovers waste heat, removes odors from the exhaust gas, or both. The spray dryer may be used to dry digestate from an anaerobic digester. Spray dryer exhaust is at least partially recirculated to the spray dryer, or condensable vapors are removed from the spray dryer exhaust, or both. Optionally, a bleed from a recirculating exhaust stream may pass through a combustion chamber. Preferably, waste heat is added to the recirculating exhaust stream or used to evaporate water upstream of the spray dryer. In a case where the spray dryer is used to treat digestate, a biogas burner may provide the combustion chamber and a source of waste heat. The system and method reduce odors from spray dryer exhaust by condensing odorous compounds, by combustion, or both while using waste heat and spray dryer exhaust gas recirculation to reduce energy consumption.

主权项

1. A process comprising steps of:
a) drying a liquid in a spray dryer to produce a dried substance and an exhaust gas; b) passing at least some of the spray dryer exhaust gas through a heat exchanger to produce a cooled spray dryer exhaust gas; c) passing at least some of the cooled spray dryer exhaust gas through a condenser to produce a dried spray dryer exhaust gas; d) passing at least some of the dried spray dryer exhaust gas through the heat exchanger of step b) to produce a warmed spray dryer exhaust gas; and, e) returning at least some of the warmed spray dryer exhaust gas to the spray dryer.