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Item type:Publication, Access status: without files , A guide on the industrial application of rotating packed beds(2018-06); ; ; ; Rotating packed beds (RPBs) exploit centrifugal fields in order to improve separations and reactions. The reported advantages of RPBs compared to state of the art equipment for the mixing and contacting of different fluids are significant reductions in equipment volume, corresponding large capacities and improved selectivities. These benefits can be attributed to the intense micromixing of the fluids and the intense internal mass transfer between different phases. Further advantages of RPBs are fast dynamics resulting in a quick achievement of steady state operation, the possibility to process highly viscous fluids and the additional degree of freedom resulting from the variable rotational speed. Although various successful implementations of RPBs on an industrial scale have been reported, conclusive criteria and guidelines for the selection of RPBs are still missing. Consequently, they are seldomly considered during process design. In order to derive explicit criteria that indicate the suitability of an RPB, known industrial applications for gas-liquid, vapor-liquid and liquid-liquid contacting applications are analyzed in the present study. On this basis, distinctive decision trees are introduced in order to facilitate the identification of processes in which the use of an RPB is expected to be beneficial.Publicationtype: Review Article91 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Mass Transfer Studies in a Pilot Scale RPB with Different Packing Diameters(2018-02-14); ; ; ; Rotating packed beds (RPBs) aim to intensify mass transfer processes by exploiting centrifugal forces. The limited use of RPBs in the chemical industry can be explained among others by missing comparative studies between state of the art equipment (e.g., packed columns) and RPBs to quantify the benefits that come along by the use of RPBs. The effective interfacial area, mainly dependent on the rotational speed, was found to be equal for both rotors (outer packing radii of 0.18 and 0.28 m, respectively) for rotational speeds larger than 20 s-1. The specific energy dissipation per provided interfacial area is newly introduced in order to link the pressure drop with the mass transfer. Compared to packed columns, the moles of CO2 absorbed per packing volume were found to increase by a factor of up to 3 in RPBs.Publicationtype: Journal Article34 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Analysing the operating limits in high gravity equipmentThe enhancement of gas-liquid mass transfer is one of the key challenges in chemical separation processes. So far, gas-liquid contacting is predominantly performed in counter-currently operated conventional columns. However, economic and environmental constraints require continuous process improvement in terms of separation efficiency and capacity. Therefore, new column internals have been developed for conventional columns allowing for increased throughput at high performance (Spiegel and Duss, 2014). A fundamentally different approach to increase the hydraulic capacity in contacting equipment is to superimpose the gravitational force by applying a centrifugal force. To realize this approach a ring shaped packing is mounted on a rotating shaft in a so-called rotating packed bed (RPB). By application of centrifugal forces, 10-1000 times higher than the gravitational force, a capacity increase is achieved. Although the increased throughput comes at the price of an elevated pressure drop and additional power consumption of the rotating equipment, it provides a great potential for debottlenecking of existing processes or implementing gas-liquid separation technologies in space limited environment and mobile environments, like off-shore applications. Furthermore, the rotational speed acts as an additional degree of freedom for an RPB, which provides additional flexibility in terms of applicable operational conditions. Besides the height of a packing and the specific packing material, recent studies by Neumann et al. have shown that also the type of nozzle for the distribution of the liquid in the eye of the rotor is of significant importance for the specific operating limits of an RPB. Therefore, the right choice of a nozzle design can facilitate a significant higher hydraulic capacity (Neumann et al., 2017a). In the present study, we investigate the operating limits with liquid loads, at the inner cross-sectional area, up to 320 m3m2h-1 and a F-factor of 4 Pa0.5. We provide detailed insights on the relationship between the pressure drop and the rotational speed and elucidate which rotational speed is needed to achieve a certain capacity for the equipment.Publicationtype: Journal Article43 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Dry Pressure Drop in Rotating Packed Beds - Systematic Experimental Studies(2017-11-01); ; ; In rotating packed beds (RPBs) centrifugal forces are exploited in order to intensify the mass transfer between different phases. In order to derive correlations describing the hydrodynamics and the mass transfer in RPBs and to improve the understanding of fundamentals, comprehensive and systematic experimental investigations are required. The present study focuses on the dry pressure drop that was investigated for different packing materials and rotor dimensions. The pressure drop induced by rotation, defined as centrifugal head, mainly depends on the outer diameter of the rotor. The frictional pressure drop in the packed bed depends on the rotor dimensions and the packing properties as well as on the operating conditions. Existing correlations do not predict the pressure drop accurately; thus, a modified correlation basing on the extended channel model is proposed, estimating the dry pressure drop in RPBs with deviations below ±15% for knit meshes and metal foams for rotors with outer packing diameters of 0.36 and 0.56 m.Publicationtype: Journal Article49 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Enzyme Accelerated Carbon Capture in different Contacting Equipment - A Comparative Study(Elsevier, 2016-11); ; ; ; CO2 capture is an essential step for providing a sustainable and ecological solution to cope with increasing energy supply burning fossil fuels. However, industrial application of current CO2 capture technologies is limited due to the significant energy penalty. In order to reduce this energy penalty two different approaches of process intensification are examined in this study. The first approach aims at the intensification of mass transfer to compensate for low absorption rates of solvents with high capacity that would allow for more energy-efficient CO2 capture. Here the tertiary amine methyldiethanolamine (MDEA) is combined with a highly efficient biocatalyst, the enzyme Carbonic Anhydrase (CA), for which significant enhancement of absorption performance was demonstrated in literature. In addition to the intensification of the solvent system, the contacting of gas and liquid streams in ab- and desorption can be improved in intensified contacting devices (ICD). Here especially membrane contactors (MC) and rotating packed beds (RPB) are promising alternatives to classical packed columns. MC provide a well-defined interfacial area that is orders of magnitude higher than for conventional equipment and introduces additional operational flexibility, expressed by the independent flow ratio between liquid and gas phase. In a RPB centrifugal forces are exploited to increase acceleration of the liquid and improve turbulence and mass transfer. The rotational speed of the rotating packing introduces an additional degree of freedom compared to common static equipment. Both ICDs offer a very compact design. While both, ICD and the improved solvent system with CA, can significantly intensify the CO2 capture process, research on the combination of both is scarce. In order to evaluate the potential benefit of a joint implementation, a first step of imminent importance is to characterize the operating windows of such an intensified process. Based on prior results concerning the energy requirements for solvent regeneration, an aqueous amine solution with 30 wt.-% MDEA is investigated in this study without and with dissolved CA. In order to evaluate the potential improvement of a joint application of the ICD and the application of CA absorption experiments in a packed column and in the two ICDs are performed. While all three devices show similar absorption performance without CA added, the RPB offers the advantage to handle exceptionally high gas loads while the MC can be operated over a much wider range of liquid loads. When CA is added to the solvent system the packed column and the RPB show superior performance compared to the MC. While none of the combinations is generally superior, the different means for process intensification extent the operating window and facilitate improved absorption performances.Publicationtype: Conference Paper36 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Improving the energy efficiency of carbon capture processes - Combining enzyme accelerated solvent systems and improved contacting equipmentIn order to achieve the ambitious targets specified by the United Nations Framework Convention on Climate Change in 2011 and reduce GHG emission in the EU by 2020 at least 20% below those in 1990 carbon dioxide (CO2) emissions have to be reduced significantly. Fossil-fired power plants are identified as major targets for carbon capture processes, since they are responsible for 40 % of the total global CO2 emissions (Mondal et al., 2012). Efficient post-combustion capture of CO2is one of the most promising options to face this crucial challenge and to achieve at least the specified short-term targets (Rochelle, 2009).Publicationtype: Conference Paper41 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , HiGee-Technologie – Untersuchung von Hydrodynamik und StofftransportPublicationtype: Journal Article40 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Computer-aided process analysis of an integrated biodiesel process incorporating reactive distillation and organic solvent nanofiltrationTo enable the use of alternative cheap feedstock in the production of biodiesel, such as waste cooking oils, the contained free fatty acids have to be separated from the triglycerides. For that purpose an integrated process incorporating reactive distillation and organic solvent nanofiltration is proposed. To determine the potential of the integrated process a detailed model was developed for computer-aided process analysis. Necessary parameters such as permeabilities and kinetics were estimated based on experimental investigations. Process analysis revealed that reactive distillation is a suitable process for the pre-treatment of waste cooking oil and that the application of organic solvent nanofiltration could enhance profitability of the process.Publicationtype: Conference Paper32