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Fakultät BCI

Research topics

Rotating Packed Beds
A common and in the chemical industry well established way to carry out absorption or distillation processes is the use of vertically orientated columns. Rotating Packed Beds (RPBs) are a promising technology to intensify those processes and to overcome the limitations linked with the gravitational field. By rotating a packed bed, a centrifugal field is generated leading to an intense contact between a liquid and a gas. In counter-current operation gas flows through the donut-shaped rotating packing from the outside to the middle of the rotor. Simultaneously liquid is sprayed into the eye of the rotor and flows, driven by the centrifugal movement, to the outside of the rotor. For experimental and theoretical investigation multiple pilot-scale RPB devices are available at the chair.

• Tobias Pyka (, G2-626, Tel.: 6002).
• Rouven Loll (, G2-611, Tel.: 2357).

Membrane processes
Membrane processes have been attracting more and more attention in industry. Because of different interactions between components and the membrane material some components can permeate through the membrane preferably which leads to a selective separation. In particular pervaporation and vapor permeation have great potential for the selective removal of trace substances from aqueous and organic mixtures. Another promising new technology is organic solvent nanofiltration which can be employed for the retention of catalysts.

• Stefan Schlüter (, G2-609A, Tel.: 4319)

Process design and optimization
Process design in general requires accurate models for dimensioning of separation units, i.e. for the design of distillation columns. At present process engineers commonly use equilibrium (EQ) models for column dimensioning. However, in some cases EQ models lead to considerable design errors and consequently significant costs. Therefore, so called non-equilibrium (NEQ) models have to be used. NEQ models consider the actual mass and energy transfers within the column and thus, allow correct design and dimensioning of columns even for the separation of highly non-ideal mixtures. At the laboratory of fluid separations, the need for NEQ modeling of non-ideal mixtures is systematically investigated. Moreover, optimization-based methods for the design of energy efficient distillation processes are developed. Conventional distillation processes suffer from low energy efficiency. The energy efficiency can be significantly improved by using alternative process variants such as heat-pump assisted and thermally coupled distillation columns. The developed design methods are based on rigorous models and can consider different process configurations, e.g. dividing wall columns. These methods are extended step by step and are applied for the design of difficult separation tasks such as extractive or azeotropic distillation processes.

• Jerzy Pela (, G2-609, Tel.: 2342)
• Thulasi Sasi (, G2-626, Tel.: 6002)

Hybrid separation
In hybrid separations two or more unit operations, based on different separation phenomena, are combined which leads to more efficient and sustainable processes. The most common combinations are (reactive) distillation and membrane separation, distillation and crystallization as well as distillation and extraction. At this laboratory hybrid separations are investigated experimentally and theoretically with a main focus on modeling and optimization.

• Tobias Hubach (, G2-613, Tel.: 6192)

Chemical recycling of PET bottles
Chemical depolymerization of PET is performed via glycolysis. The resulting BHET monomer can be used as raw material for the production of fresh PET. This equilibrium reaction is examined experimentally as well as theoretically. By means of thermodynamic modelling the yield of BHET monomers is optimized. In order to separate BHET monomers selectively out of the reaction mixture crystallization is used. The influence of process parameters on the efficiency of separation is determined by design of experiment. Finally, all process steps – from shredded PET flakes to pure BHET crystals – are performed one after another. Subsequently, the whole process is economically assessed.

• Maria Schlüter (, G2-614, Tel.: 2356)