One research focus of the Held group at the Lab of Thermodynamics is product purification and (bio)chemical conversion using rotating devices that utilize centrifugal forces for process intensification. Rotating Packed Beds (RPBs) are employed for this purpose.

RPBs are used to contact intensively two phases (for example, a gas and a liquid phase, or two liquid phases). An RPB consists of a rotor with structured packing, mounted on a shaft within a closed and stationary casing. In gas-liquid applications (e.g., distillation, absorption), the liquid is added to the rotor's eye. Due to centrifugal forces, the liquid moves outward through the packing. The gas is introduced at the outer edge of the casing and flows countercurrently to the liquid through the packing toward the center. The rotation of the packing multiplies mass transfer over non-rotating packings as used in stationary columns or reactors. The process efficiency increases significantly, especially for processes with severe mass transport limitations, such as stripping monomers from highly viscous polymers.

The Held research group, in collaboration with the APT (Prof. Schembecker) and FVT (Prof. Gorak), has already investigated stripping [1], absorption, and dsitillation processes [2] in RPBs. Industrial partners are of high importance for us, e.g. BYK CHemie GmBH. We are investigating the influence of internals (packing, liquid injection, and distributor) on the efficiency of an operation under investigation. Through collaboration with the Bieberle/Schubert research group in Dresden, we have experimentally determined the extent of misdistribution in packings using imaging techniques [3,4]. Based on this, we have been able to develop new internals, such as zigzag packings [5] and novel liquid distributors [4] in RPBs. Ideally, these findings are then correlated to make the knowledge tangible for engineering purposes and, in turn, to realize specially designed packings [6,7], which we are currently producing ourselves using polymer-based 3D printers.

Current research involves expanding the operating windows in RPBs compared to conventional equipment (column, reactor) in absorption, distillation, and chemical reactions. We are also investigating different rotor sizes, packing inner and outer diameters, and the type of packing itself.

[1]      J. Koop, N. Bera, E. Quickert, M. Schmitt, M. Schlüter, C. Held, G. Schembecker, Industrial & Engineering Chemistry Research 2023, 62 (46), 19855-19861. DOI: 10.1021/acs.iecr.3c01597

[2]      T. Pyka, V. Backhaus, C. Held, G. Schembecker, Industrial & Engineering Chemistry Research 2023, 62 (46), 19855-19861. DOI: 10.1021/acs.iecr.3c03173

[3]      T. Pyka, A. Bieberle, R. Loll, C. Held, M. Schubert, G Schembecker, Industrial & Engineering Chemistry Research 2024, 62 (14), 39-49. DOI: 10.1021/acs.iecr.3c03996

[4]      T. Pyka, M. Brunert, J. Koop, A. Bieberle, C. Held, G. Schembecker, Industrial & Engineering Chemistry Research 2023, 62 (14), 39-49. DOI: 10.1021/acs.iecr.3c00248

[5]      R. Loll, L. Runge, J. Koop, C. Held, G. Schembecker, Industrial & Engineering Chemistry Research 2022, 61 (32), 11934-11946. DOI: 10.1021/acs.iecr.2c01443

[6]      T. Pyka, J. Koop, C. Held, G. Schembecker, Industrial & Engineering Chemistry Research 2022, 61 (46), 17156-17165. DOI: 10.1021/acs.iecr.2c01443