New screw heat exchanger reaches up to 650°C

The thermal treatment of bulk materials is an energy-intensive process that is posing increasing challenges for plant operators. Conventional screw heat exchangers, which are operated indirectly using heat transfer fluids such as thermal oil or steam, reach their physical and economic limits at very high temperatures. Köllemann GmbH addresses this problem with the LiquiCore™, a high-temperature screw heat exchanger for electric process heat. This innovative system completely dispenses with liquid heat transfer fluids, thereby drastically reducing system complexity, maintenance requirements and potential leakage risks.

Innovation at its core:

the liquid metal ­principle

At the heart of the technology is an electrically heated screw shaft with a hermetically sealed core. Inside this core, integrated heating elements are embedded in a low-melting-point metal. 

Through the targeted use of heat-resistant stainless steels and an innovative bismuth-tin alloy as the heat transfer medium, the system’s operating range has recently been significantly expanded. As the special alloy melts at just 138°C, the machine can now operate efficiently from a process temperature of approximately 145°C. At the upper end, the new materials push the performance limit up to 650°C.

In its liquid state, the heat transfer medium ensures extremely rapid and uniform heat distribution across the entire shaft length. To further maximise heat input into the bulk material, the trough jacket can also be electrically heated as an option.

Precision and energy efficiency

Fully electric operation offers not only advantages in terms of infrastructure, but also in process control. The system enables precise temperature control and is characterised by short response times. This guarantees homogeneous, reproducible high-temperature process control. At the same time, the technology excels in terms of high energy efficiency and very rapid controllability.  To ensure optimal integration into existing plants, the design is tailored to the customer’s specific requirements using heat-resistant materials, optimised screw geometries and state-of-the-art control and regulation technology.

Applications in bulk materials and environmental technology

Thanks to its high performance, the LiquiCore™ is ideally suited to demanding environmental and high-temperature applications. The apparatus design makes it particularly well-suited to processes such as pyrolysis, calcination, high-temperature drying and the thermal activation of solids.

A particularly rapidly growing field of application in environmental technology is the thermal desorption of persistent pollutants, such as per- and polyfluorinated alkyl substances (PFAS). Here, the unit is used in the remediation of contaminated soil, the treatment of sewage sludge or the reactivation of loaded adsorbents.

With the LiquiCore™ high-temperature screw heat exchanger, the bulk materials industry now has access to a technology that not only reliably handles the highest process temperatures, but which, thanks to its purely electric operation, can also make a significant contribution to the decarbonisation of industrial heating processes.