PURE Steam Drying is a continuous drying process of highest energy efficiency and without CO2 emissions. It operates in the absence of air in an atmosphere of superheated steam with steam temperatures between 100° and 200°C at atmospheric pressure. This approach allows the continuous recovery of the evaporation heat necessary for drying in a simple way by recompressing the vapor by means of a high temperature heat pump. The heat required to evaporate the liquid water from the material is returned to the process in a heat exchanger by condensing the vapor. Vapor recompression (MVR) gives the technology maximum energy efficiency. While moist material is fed into the process from below through open airlocks from the ambient air through the steam-air separation layer, dry material and liquid water of 100°C leave the plant in a sterile condition, which allows the water to be reused.
The technology can be powered exclusively by electricity, which means that CO2 emissions are zero if a renewable source is used. The process can achieve a specific energy requirement of 0.3 kWh/kg of evaporated water (including preheating), depending on the material, the initial moisture content and the desired target drying level. If waste heat of at least 100°C is available, it can be fed into the process, further increasing energy efficiency.