For many types of digestate and effluent, low-temperature evaporation can be an energy-efficient way to remove water.
Such a process combines the use of a vacuum to reduce the boiling point of the liquid along with traditional high-temperature evaporators. This is based on heat exchanger technology utilising surplus heat from heaters and combined heat and power (CHP) engines.
Heat exchangers from HRS can recover heat from other sources, such as that left from the CHP engine or from pasteurisation, and using this as the basis for an evaporation system can further improve the overall process efficiency.
The ultimate use of HRS heat exchangers for low-temperature evaporation can be found in the company’s Digestate Concentration System, which uses multiple evaporation effects to increase the solids in liquid digestate up to four-fold.