Dahmes has introduced the VacuCoil High Pressure Preheater, a feed preheater designed to increase spray dryer output for heat-sensitive concentrates.

The Minnesota-based manufacturer designed the unit for installation on the high-pressure side of the feed line, immediately before the atomizer. It uses condensing steam held under vacuum to heat liquid concentrate before it enters the dryer.

Feed viscosity can limit spray dryer output when processing dairy proteins and other heat-sensitive concentrates. Increasing feed temperature lowers viscosity and allows more solids to reach the atomizer.

However, excessive heat or prolonged exposure can denature proteins and affect product quality. Dahmes designed the VacuCoil to address that trade-off by placing the heating step immediately before atomization.

The concentrate is exposed to the preheater's surface temperature for several seconds. Dahmes said conventional preheaters installed earlier in the process can expose the product to heat for several minutes.

The VacuCoil commonly operates at a surface temperature of about 160°F. Dahmes said the process also reduces microbial load in the concentrate.

According to Dahmes, the preheater typically increases spray dryer output by 7% to 9%. The company has seen increases of more than 11% in specific applications.

The unit can be installed as a retrofit on spray dryers from any manufacturer or specified for new systems. Installation takes place on the existing feed line, and Dahmes said most work can be completed while the plant remains operational.

The company said the VacuCoil does not require new building or permitting. Additional capacity becomes available as soon as installation is complete.

A VacuCoil unit is currently operating on sodium and calcium caseinate at a customer facility, according to Dahmes. The company said the approach also applies to plant proteins, egg, flavors and extracts, and protein hydrolysates.