Exhaust Air Heat Recovery Systems
Heating process air for spray dryers consumes a significant amount of energy. The exhaust air typically leaves the spray dryer between 150° F and 200° F (60° C to 93° C) and substantial energy savings can be realized by preheating incoming process air utilizing the hot exhaust gas from the dryer.
Exhaust air heat recovery systems can typically reduce a dryer's energy consumption by up to 25%. Exhaust air heat recovery systems can be of either the Air-to-Air or the Air-Liquid-Air configuration.
Marriott Walker exhaust air heat recovery systems are engineered to fully drain condensed moisture in the exhaust stream and permit full CIP-cleaning. This rugged design approach, combined with all stainless steel construction, assures that processors have the tools they need to easily clean the unit thus maintaining high levels of both sanitation and heat transfer.
Air-to-Air Configuration
Marriott Walker Air-to-Air heat recovery units utilize one or more, 100% stainless steel, all welded heat exchangers, utilizing the dryer's hot exhaust air to preheat incoming air to the spray dryer's process air heater. Our air-to-air heat exchangers utilize a vertical I-Pass configuration for the dryer's exhaust air stream to manage condensate and the system is fitted with a permanently installed CIP system, to permit vigorous CIP cleaning of the unit's exhaust air side when required.
Air-Liquid-Air Configuration
The principal convenience of Marriott Walker Corporation Air-Liquid-Air heat exchangers is that they can be easily retro fitted to existing spray dryers where ducting the inlet and exhaust air streams to one another may not be practical. In this configuration, the heat transfer is accomplished by circulating a thermal fluid through a heat transfer surface arrayed in the hot exhaust air stream of the dryer and heat release coils installed in the inlet air stream. Thus, rather than using large ducts to conduct the dryer's air streams to the heat exchanger core, the processor simply needs to circulate a thermal fluid between the exhaust air module and the inlet air heat release coils to accomplish the desired heat transfer.
