Viscosity sets the ceiling

Dahmes notes that spray dryer output for heat-sensitive concentrates is often limited by the viscosity of the feed rather than by the dryer itself. Raising feed temperature lowers viscosity and allows more solids to reach the atomiser, but excess heat, or extended exposure to it, can denature protein and reduce product quality. For that reason, some processors have kept preheat temperatures conservative, even where this limits dryer output.

Seconds rather than minutes

The VacuCoil preheater uses condensing steam held under vacuum to hold a set surface temperature, commonly around 160°F (71°C), evenly across the unit. Because it is installed immediately before the nozzle, the concentrate is exposed to that temperature for a few seconds rather than the several minutes typical of a preheater installed earlier in the process. Dahmes said the same heating step also reduces microbial load in the concentrate.

According to the company, the preheater typically increases dryer output by 7% to 9%, with more than 11% seen in specific scenarios.

Retrofit or specify new

The VacuCoil is installed on the feed line, with most of the work conducted while the plant continues operating. Dahmes says it requires no new building or permitting and that the added capacity is available as soon as installation is complete. The unit is compatible with spray dryers of any manufacturer and can be installed as a retrofit or specified into a new system.

Running on caseinate

The company noted that a unit is currently running at a customer facility on sodium and calcium caseinate, among the highest-viscosity feeds in dairy processing. It says the same approach applies to other heat-sensitive concentrates, including plant proteins, egg, flavours and extracts, and protein hydrolysates.

“Protecting the protein and pushing the dryer have always been a trade-off. The VacuCoil removes that trade-off,” said Hans Kabat, Vice President of Engineering at Dahmes. “This product gives processors the increased capacity that comes with a hotter feed without the denaturation risk that has kept preheat conservative for years, and that is the part that makes plants comfortable saying yes.”

Dahmes, founded in 1995 and based in New London, Minnesota, engineers, builds and supports custom evaporation, spray drying and powder-handling systems for food and ingredient processors. The company is vertically integrated, providing engineering, fabrication, construction, installation, startup, and parts and service, and is taking inquiries from processors whose dryer output is limited by feed viscosity.

For more information, visit: www.dahmes.com
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