Performance Evaluation of Rotating Packed Beds for Distillation Using Improved Packing Design

Towards the Development of Advanced Packing Design for Distillation in Rotating Packed Beds

“…These results align with theoretical considerations derived by the correlations of Burns et al for liquid holdup and also with the liquid holdup measurements using γ ‐ray tomography by Gross et al , which indicate that the liquid holdup in the packing decreases significantly with increasing rotational speed while the contribution of the casing to the overall mass transfer increases due to reduced mass‐transfer in the packing . At the previously determined maximum separation efficiency, the contribution of the casing is determined to be 0.77 and the contribution of the packing to be 1.86 theoretical stages, resulting in a fraction of only 71 % of the mass transfer happening inside the packing.…”

“…However, there is still a severe need for reliable mass transfer analysis and modeling since most published data for RPBs reflect results of rather small‐scale laboratory equipment while assuming that all mass transfer in the RPB can be attributed to the packing. As illustrated in a previous work a differentiation between mass transfer in the packing and the casing is, however, of significant importance when characterizing the performance of a specific type of packing for different operating parameters, like rotational speed and F ‐factor. Therefore, different rotor configurations, with and without packing, have to be evaluated, in order to quantify the mass transfer inside the packing and compare the performance of different packings.…”

“…In the first section ( n ≤ n opt ) the separation efficiency increases with rotational speed, while in the second section ( n > n opt ) an opposite relation is observed. These results clearly indicate a trade‐off between contacting time or liquid holdup in the packing and effective interfacial area as previously analyzed by Qammar et al . This trade‐off is further observed during the liquid holdup measurements using γ ‐ray tomography by Gross et al , who clearly documented the decreasing liquid holdup in the packing with increasing rotational speed as well as increasing the radial depth of the packing .…”

“…For an accurate characterization of the separation performance of a specific packing and as a consequence a reliable scale‐up, it is important to determine the actual contribution of the packing and the casing to the overall separation efficiency. As indicated in previous investigations there can be a substantial contribution of the casing to the overall separation efficiency. The results of temperature measurements at the vapor inlet, in the casing and at the vapor outlet indicate that the casing contributes almost an equivalent to one theoretical stage to the overall mass transfer in the RPB, as illustrated in Fig.…”

“…To evaluate the contribution of the casing and packing to the overall mass transfer, PT100 thermocouples were installed at the vapor inlet, outlet and in the casing of the RPB. The vapor compositions were determined based on vapor‐liquid equilibria calculated on the basis of the temperature measurement at 101.325 kPa . The vapor pressure of the pure components was calculated using the Antoine equation, Eq.…”