Thermal water treatment

Thermal water treatment processes are widely used today in various branches of industry. Besides simple heating these processes include, for example, distillation, sterilization and rectification (thermal material separation). The advantage of these methods is that the technologies are often relatively simple and of robust design. Thermal energy supply can generally be achieved without great technical efforts by means of direct firing, process vapor, or electric heating.

On the other hand, thermal treatment methods are mostly energy-intensive. New technical solutions are necessary to ensure a responsible use of energy resources and to offset the increasing cost pressure.

Solutions viable for the future are required

Thermal methods offer many possibilities for use in the context of the secondary utilization of energy by means of waste heat and the application of thermal solar technology.

The Fraunhofer Institute for Interfacial Engineering and Biotechnology IGB has set itself the objective – by developing innovative concepts as well as optimizing and combining various methods – to realize efficient and inexpensive thermal treatment methods in order to be able to use these sources of energy. Solar seawater desalination, the concentration of industrial wastewater and the recovery of resolvents are examples of applications that are being worked on at Fraunhofer IGB.

Thermal treatment methods are especially well suited for decentralized solutions and those independent of the infrastructure, as they can have a simple set-up and locally accruing thermal solar energy and/or waste heat become available.

The solution of customer-specific problems demands flexible and optimized, adaptable concepts. As a result of the interdisciplinary composition of our expertise and the independence from specific technology solutions, we can carry out these tasks objectively and in a customer-oriented way.

Most solution concepts for the thermal treatment of water and other materials are based on a multi-effect vacuum distillation which enables heat to be used efficiently at low temperatures. Due to the vacuum, the technology works at low boiling temperatures and energy can be recovered from within the system in several pressure stages. This means that energy is used several times, lowering the specific energy requirements significantly. The boiling temperature in the vacuum is also considerably lower so that the energy requirements can be met with simple solar thermal collectors or by using waste heat from approx. 60 °C.

Innovative vacuum process

Although this is a vacuum process, vacuum or jet pumps are no longer required as the vacuum is created and maintained by gravitation only. Two simple hydraulic pumps are enough to serve the entire plant. The process is controlled mainly by hydraulic and/or mechanical principles and components so that electrical measuring and controlling equipment can be kept to a minimum.

This innovative vacuum process can be run independent of fossil energy sources and power grids because simple solar thermal collectors provide the necessary thermal energy and few photovoltaic collectors are sufficient for running the electrical components of process control.