Pilot steam dryer could cut energy use by up to 80%

The pilot system at Fraunhofer IGB is already running: a superheated-steam spray dryer has been built and tested, bringing the technology closer to real-world use. Their laboratory tests on food, mineral raw materials and construction materials indicated that the approach could cut energy consumption by up to 80% when combined with heat pumps and smart controls.

The problem is familiar in factories but costly at scale. Hot air dries fruits and vegetables, grains, spices, powdered milk, instant coffee, fertilizers, fabrics and medicines. Much of the energy still comes from natural gas, while heat escapes with the outgoing air instead of doing useful work again.

Fraunhofer’s system keeps that work inside the dryer. Electricity first creates superheated steam, meaning steam heated beyond the point at which water boils. As the steam draws moisture from a product, it becomes wetter; the system cools it until it condenses back into water and recovers heat at around 90-100 °C. A heat pump then compresses the remaining steam, increasing its temperature so the heat can return to the drying process.

The same principle could be used in belt, drum and spray dryers. An integrated control system adds a second lever: it can activate the dryer when wind and solar power are plentiful and cheaper, a useful feature for manufacturers trying to match electricity use with variable renewable production.

So what changes in practice? A factory could reuse heat that conventional drying sends into the atmosphere, while shifting some operation toward periods of lower-cost renewable electricity. The current result is a pilot system, and the reported figures come from laboratory testing. The institute’s target is a two- to fourfold reduction in drying energy needs, but the final performance will depend on the drying method and temperature level.