Processing
Dahmes Introduces VacuCoil High Pressure Preheater for Spray Drying
Dahmes, a Minnesota-based manufacturer of spray drying and powder processing systems, recently introduced the VacuCoil High Pressure Preheater, a feed preheater for spray drying operations.
The unit mounts on the high-pressure side of the feed line, immediately before the atomizer, and heats liquid concentrate, often dairy protein or other heat-sensitive proteins, using condensing steam held under vacuum before the product reaches the dryer.
Spray dryer output for heat-sensitive concentrates is often limited by the viscosity of the feed rather than by the dryer itself. Raising the feed temperature lowers viscosity and allows more solids to reach the atomizer, but excess heat, or extended exposure to heat, can denature protein and reduce product quality. For that reason, some processors have opted to keep preheat temperatures conservative, even when it limits dryer output.
The VacuCoil preheater uses condensing steam held under vacuum to hold a set surface temperature, commonly around 160°F, evenly across the unit. Because it is installed on the high-pressure side of the feed line, 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 Dahmes, the preheater typically increases dryer output by 7% to 9%, with more than 11% seen in specific scenarios. The VacuCoil is installed on the feed line, with most of the work conducted while the plant continues operating, requires no new building or permitting, and 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. 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, and that the same approach applies to other heat-sensitive concentrates, including plant proteins, egg, flavors 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.”
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