Rotating Packed Bed Research Articles

Enhancement of devolatilization performance in a rotating packed bed with different packing structures

• The 3D-printed mesh packing with drop-shaped fibers (PMP-D) was manufactured. • The PMP-D was employed to enhance the devolatilization performance in RPB. • Compared with traditional SMP, the η and K L a of PMP-D was drastically improved. • Correlations to predict K L a were established with deviations less than ±20%. The devolatilization of volatile organic compounds (VOCs) from the viscous liquid like polymers was necessary but of great challenge caused by the high viscosity. In this work, different packing structures were manufactured in a rotating packed bed (RPB), including the stainless steel wire mesh packing (SMP), 3D-printed column packing (PCP), 3D-printed mesh packing with circular fibers (PMP-C), and 3D-printed mesh packing with drop-shaped fibers (PMP-D). The devolatilization performance of the RPB was investigated with the acetone-silicon oil working system. Results indicated that modifying the fiber shape of packing effectively intensified the devolatilization in the RPB. The removal efficiency ( η ) and volumetric mass transfer coefficient ( K L a ) of the PMP-D were dramatically larger than the other three packings. Compared the PMP-D with the traditional SMP, the maximum η was enhanced from 40% to 50%, and the increment of K L a was 50% on average. The correlations to predict K L a were established, and the deviations from the experimental results were less than ± 20%.

Modeling and Parametric Investigation of Rotating Packed Bed Processes for CO2 Capture and Mineralisation

Rotating Packed Beds (RPB) are receiving increased attention in CO2 capture, due to their considerably lower volume compared to conventional packed-beds and their beneficial effects on process capital costs. As a result of these advantages, RPB have also been considered as a CO2 mineralisation option for the production of precipitated calcium carbonate (PCC). In the area of CO2 capture, the few model-based investigations employ either the two-film or Higbie’s penetration theory to model the gas-liquid mass transfer as the main driving force of the systems’ operation. In the area of PCC production, there is only one model type available that is based on the two-film theory. While the latter includes the limiting assumption of linear and steady-state mass transfer within the liquid film, Higbie’s theory is considerably closer to realistic operation due to the assumption of time-dependent and non-linear, gas-to-liquid mass transfer. Considering this significant advantage, this work proposes for the first time a model for RPB-based, PCC production using Higbie’s penetration theory. The model is first developed and validated considering solvent-based CO2 capture with monoethanolamine (MEA) solvent, taking advantage of the available experimental data in published literature. The model is then adapted to PCC production to perform a parametric investigation based on various performance indicators. Results indicate that the proposed model enables improved accuracy compared to the two film theory. Higher rotation speeds and liquid flowrates enable improved mass transfer, whereas PCC production can be achieved at lower energy consumption simultaneously with high CO2 capture efficiency.

Dynamic modeling of the absorption of acetic acid in rotating packed bed

BackgroundWe present a dynamic model for designing a rotating packed bed (RPB) demonstrating volatile organic compound absorptions with circulation. The developed RPB model can be applied for industrial process simulations and scale-up. MethodsThe industrial applicability of the model was validated using in-house steady-state and dynamic RPB experimental data. The absorption of acetic acid (AA) in gas stream by an RPB, evaluated using reverse osmosis (RO) water and 1 wt.% NaOH aqueous solution, established the model. The operational variables’ effects, such as rotational speed and gas to liquid ratio, on the AA absorption efficiency are discussed. Significant findingsThe height of transfer unit (HTU) of the RPB was less than 3 cm, indicating the superior mass-transfer efficiency of the RPB than that of conventional packed bed column. The RPB model could predict the HTU in a steady-state well for the AA absorption, and the average absolute deviations (AAD) of HTU for the absorbent using RO water and 1 wt.% NaOH solution were 19.2% and 15.2%, respectively. Furthermore, the RPB model accurately predicted the AA absorption in circulation well for 1 wt.% NaOH with initial AA loadings of 1.7, 1.9, and 2.0 wt.% and AADs of 3.5%, 1.7%, and 1.9%, respectively.

Performance of nZVC/H2O2 process in degrading chloramphenicol in water

Background: To develop other H2O2-based approaches for the efficient degradation of chloramphenicol, this study elucidates the performance of the nZVC/H2O2 process in the degradation of chloramphenicol in water.Methods: A rotating packed bed (RPB) with blade packings was adopted in the mass-production of nanoscale zero-valent copper (RPB-nZVC). The effects of pH, initial chloramphenicol concentration, nZVC dosage, and H2O2 concentration on the degradation of chloramphenicol using the nZVC/H2O2 process with RPB-nZVC were studied.Significant findings: The results reveal that the optimal nZVC dosage and H2O2 concentration were 250 mg/L and 1.25 mmol/L, respectively. At pH 3 with an initial chloramphenicol concentration of 10 mg/L, an nZVC dosage of 250 mg/L, an H2O2 concentration of 1.25 mmol/L, and a degradation time of 30 min, the nZVC/H2O2 process with the RPB-nZVC degraded 93% of the chloramphenicol. However, at the same operating parameters, the efficiency of degradation of chloramphenicol of 63% was achieved in the nZVC/H2O2 process with commercial nZVC that was obtained from Sigma-Aldrich. Therefore, the nZVC/H2O2 process with RPB-nZVC can be used to degrade strongly chloramphenicol in water.

Highly dispersed and confined Ni/MMO catalyst synthesized in a rotating packed bed for hydrogenation of maleic anhydride

AbstractCatalytic hydrogenation of maleic anhydride (MA) into succinic anhydride (SA) is one of the most important transformations in synthetic organic chemistry. Herein, we firstly synthesized well‐dispersed nickel particles confined by mixed metal oxides (Ni/MMO) derived from in situ transformation of Ni‐Al hydrotalcite in a rotating packed bed (RPB) to catalyze this process. A series of Ni/MMO catalysts (63 wt%–89 wt% Ni) were effectively fabricated and the structure–activity relationship was established. Results showed that a Ni/MMO catalyst (82 wt% Ni) with substantial surface defect sites and the highest Ni surface area among the prepared Ni/MMO catalysts, demonstrates the highest activity with ~100% MA conversion and ~100% selectivity to SA under 25°C within 77 min. This is, to our knowledge, the highest conversion and selectivity under room temperature to date. Moreover, the Ni/MMO catalyst prepared by RPB has higher specific surface area and Ni surface area, therefore possessing a higher hydrogenation rate compared to that by stirred tank reactor (1.69 vs. 1.36, 10−3·molMA/gcat/min). These results will provide an attractive option of the catalysts for MA hydrogenation, and a novel strategy for synthesizing nickel catalyst derived from Ni‐Al hydrotalcite.

CFD Simulation of Dry Pressure Drop in a Cross-Flow Rotating Packed Bed

The cross-flow rotating packed bed (RPB) has attracted wide attention in recent years because of its advantages of large gas capacity, low pressure drop and lack of flooding limitation. However, the complex structure of the packing makes it difficult to obtain the gas flow characteristics in the cross-flow RPB by experiments. In this study, the dry pressure drop in the cross-flow RPB was investigated by computational fluid dynamics (CFD). The packing was modeled by the porous media model and the rotation of the packing was simulated by the sliding mesh model. The simulation results obtained by three turbulence models were compared with experimental results, and the RNG k-ε model was found to best describe the turbulence behaviors in the cross-flow RPB. Then, the effects of gas flow rate and rotating speed on dry pressure drop in different parts of the cross-flow RPB were analyzed. The results of this study can provide important insights into the design and scale-up of cross-flow RPB.

A vanadium phosphorus oxide catalyst synthesized in rotating packed bed for high‐efficiency selective oxidation of n‐butane

AbstractOxidation of n‐butane to produce maleic anhydride (MA) by the vanadium phosphorus oxide (VPO) catalyst is important for the fine chemical industry. However, the improvement in MA yield exceeding 60% is still a big challenge. In this article, a VPO catalyst with increased MA yield originated from the tailored structure of VPO precursor prepared in a rotating packed bed (RPB) reactor with excellent micro‐mixing efficiency. The activated VPO‐RPB catalyst displayed the coexistence of X1‐VOPO4 and αI‐VOPO4 phases and enhanced reducibility of V4+ state. Remarkably, the MA yield in n‐butane oxidation catalyzed by VPO‐RPB reached up to 66%, showing an increment by 14% compared with VPO‐STR prepared in a stirring tank reactor (STR). The VPO‐RPB showed the repeatable catalytic performance and achieved a promising scale‐up production. This work provides the experimental evidence of a dual‐phase (X1‐VOPO4 and αI‐VOPO4) mechanism for n‐butane oxidation, and reveals the structure–activity dependence of VPO catalyst.

Advanced treatment of coal gasification wastewater by O3/Fenton in a rotating packed bed in tandem with coagulation

In this study, the O3/Fenton system in a rotating packed bed (RPB) in tandem with coagulation process was applied to the advanced treatment of coal gasification wastewater (CGW). The removal of COD reached 35.4% in the O3/Fenton@RPB process, and the total removal of COD rose to 47.8% after the effluent of the O3/Fenton@RPB process was further treated with coagulation. The O3/Fenton@RPB + coagulation tandem process also demonstrates good effect on enhancing biodegradation and removing color of the CGW, with the BOD5/COD and decolorization in the tandem process reaching 0.49 and 87.5%, respectively. In addition, an artificial neural network model was established to predict the mass transfer performance of the O3/Fenton system in the RPB and exhibited a good predictability. The O3/Fenton@RPB + coagulation tandem process shows the application potential in the advanced treatment of CGW.

Experimental analysis and rate-based stage modeling of multicomponent distillation in a Rotating Packed Bed

Rotating Packed Beds (RPBs) offer increased flexibility and the potential of significant size-reductions for distillation processes through mass transfer intensification. This may be of interest for example for retrofits or off-shore applications. However, validated models for process design of multicomponent distillation in RPBs are not available up to now. To bridge this gap, distillation of binary and ternary mixtures at total reflux was experimentally investigated in an RPB test rig. Depending on the flowrate and rotational speed, up to 10 theoretical stages were achieved in the investigated RPB, corresponding to an HETP (height equivalent of a theoretical plate) of as low as 17mm at the best operating point. With increasing centrifugal acceleration, separation efficiency increased at first, but decreased again at high centrifugal accelerations. Using the rate-based stage approach, a correlation for gas-side volumetric mass transfer coefficient in the RPB is developed. It is capable of reproducing the observed maximum of separation efficiency. Coefficients are fitted for this correlation, based on results obtained from distillation of ethanol/n-propanol. The model is validated using data obtained from distillation of ethanol/water and ethanol/n-propanol/water. Overall volumetric mass transfer coefficients and numbers of theoretical stages are described for most of the data within ±30%.

Degradation of nitrobenzene by high-gravity intensified heterogeneous catalytic ozonation with Mn-Fe/ZSM-5 catalysts

In this study, high-gravity intensified heterogeneous catalytic ozonation is proposed for degradation of nitrobenzene (NB) in wastewater using Mn-Fe/ZSM-5 as the packing of the high-gravity rotating packed bed (RPB). The effects of inlet O3 concentration, liquid flow rate, initial pH, and high-gravity factor on the removal rate of total organic carbon (TOC) at room temperature are investigated and compared with that in a bubbling reactor (BR), and the degradation mechanism is also discussed. The results show that under the optimal conditions of the high-gravity factor β = 20, initial O3 concentration CO3 = 25 mg/L, liquid flow rate QL = 60 L/h, and initial pH = 6, the removal rate of TOC reaches 72% after 40 min. The removal rate of TOC in RPB is 33.5% higher than that in BR. The radical quenching experiment shows that •OH plays a dominant role in high-gravity intensified heterogeneous catalytic ozonation with Mn-Fe/ZSM-5. It is concluded that high-gravity intensified heterogeneous catalytic ozonation with Mn-Fe/ZSM-5 can effectively improve the degradation efficiency of organic wastewater.

A high-productivity process for mass-producing Fe3O4 nanoparticles by co-precipitation in a rotating packed bed

Fe3O4 nanoparticles were mass-produced using a rotating packed bed (RPB) and the role of stoichiometric ratio and the effects of the FeCl2 and FeCl3 concentrations, aging temperature, and Fe2+ and Fe3+ sources on the characteristics of the obtained Fe3O4 nanoparticles were examined. A high-productivity process for mass-producing Fe3O4 nanoparticles with a rate of approximately 23 kg/day was developed with an FeSO4 concentration of 0.15 mol/L, an FeCl3 concentration of 0.3 mol/L, an NaOH concentration of 1.2 mol/L, a production temperature of 25 °C, an aging temperature of 25 °C, a rotational speed of 1800 rpm, a flow rate of aqueous FeSO4/FeCl3 of 0.5 L/min, and a flow rate of aqueous NaOH of 0.5 L/min. The thus mass-produced Fe3O4 nanoparticles had a mean diameter of 8.4 nm and exhibited superparamagnetism with a saturation magnetization of 61 emu/g. Since the RPB provides excellent micromixing and overcomes the difficulty of mass-production that is associated with traditional co-precipitation in a batch process, Fe3O4 nanoparticles that are mass-produced in an RPB are smaller than Fe3O4 nanoparticles that are batch-produced in a batch reactor, and so have a greater adsorption capacity to remove Reactive Red 2 from water. The results in this work demonstrate that an RPB can mass-produce Fe3O4 nanoparticles at a production temperature of 25 °C and an aging temperature of 25 °C with a low molar ratio of OH− to Fe2+ (8:1). Accordingly, a high-productivity process for mass-producing Fe3O4 nanoparticles can be implemented using an RPB with co-precipitation.

Modeling of carbon dioxide absorption by solution of piperazine and methyldiethanolamine in a rotating packed bed

CO2 removal by the blended amine solution of piperazine (PZ) and methyldiethanolamine (MDEA) with the various molar concentration ratios in a rotating packed bed (RPB) was modelled using MATLAB linked to Aspen Plus. All the required correlations for the RPB in addition to the mass and energy balances were written in MATLAB while the demanded physical and transport properties were extracted from Aspen Plus. The similar operating conditions and compositions in the reported experiments were used to run the model by the two-film theory for mass transfer as steady state, while the impact of five different parameters on the CO2 absorption efficiency was examined to validate the model. The modeling results are in good agreement with the experimental data for which the average absolute deviation is less than 7.0%. The process analysis revealed that rotational speed and PZ concentration have the most significant effects on CO2 absorption efficiency.

Chlorine dioxide gas generation using rotating packed bed for air disinfection in a hospital

Chlorine dioxide (ClO2) has proven its efficiency as a fumigant toward bacteria and viruses. However, it still has challenges on its portability and simplicity of ClO2 generation to meet the demand for disinfection in public and medical sectors. In this study, ClO2 stripping process via a rotating packed bed (RPB) from the commercial ClO2 solution was developed to a non-chemical-reaction ClO2 generation for air sterilization in a hospital. The ClO2 stripping efficiency (η) and the volumetric liquid mass-transfer coefficient (KLa) were examined under various operating variables, such as initial liquid concentration (CLi), rotational speed (ω), gas-to-liquid flow rate ratio (QG/QL), and liquid flow rate (QL). The results indicated that the gaseous ClO2 can be rapidly and continuously generated via stripping using RPB with η varied above 97% in the certain range of CLi (100–2000 mg/L) and QL (0.04–0.250 L/min). The overall KLa depends on the change of QL and ω, varied from 0.009 s−1 to 0.027 s−1. The output concentration of gaseous ClO2 (CG) can be adjusted from around 10 ppm to over 1000 ppm based on the established prediction model and controlling CLi, QL, QG, and ω. The results of the on-site disinfection test in the Mycobacterium Tuberculosis Laboratory in a hospital have shown effective elimination of all sites of E. coli and 2 of 5 sites of G. stearothermophilus with a CT value at the gas monitoring point of 642 ppm-h and humidity of 81%.

Process intensification of reactive extraction for hydrogen peroxide production in a rotating packed bed reactor

Anthrahydroquinone oxidation and H2O2 extraction are essential steps for commercial production of H2O2 via the anthraquinone route. However, high demand of mass transfer in the oxidation and extraction for the complicated production procedure is still a challenge. In this work, a rotating packed bed (RPB) reactor with superior mass transfer efficiency was applied to the simultaneous oxidation reaction and extraction for the first time. Effects of various operating parameters on the efficiency of reactive extraction were investigated. The intensified gas-liquid-liquid mass transfer in the tandem RPB reactor + stirring tank reactor (STR) contributed to the anthrahydroquinone conversion and H2O2 extraction efficiency up to 92% and 89%, respectively, while only 9.1% and 69% in the STR. Compared with the bubble column, the RPB reactor + STR also showed higher H2O2 production efficiency and obvious advantage with a shorter reaction time, which paves a new way for gas-liquid-liquid reactive extraction.

Synthesis of petroleum sulfonate via gas-phase sulfonation in rotating packed bed: Process optimization and interfacial tension-composition relationship

This study presents the synthesis of petroleum sulfonate (PS) via gas-phase SO3 sulfonation in a rotating packed bed (RPB) and the relationship between the interfacial tension (IFT) at the oil-aqueous interface and the composition of PS. Through the process optimization, the content of active matter in the prepared PS could reach up to 42.5%, which was significantly higher than that in the industrial production (38%). Moreover, the oil-aqueous IFT could reach an ultra-low value of 1.41×10-3 mN/m. The analysis results of PS composition and IFT indicated that the oil-aqueous IFT was mainly affected by the content of alkyl benzene, alkyl indane, alkyl acenaphthylene and alkyl naphthalene sulfonates in PS. In addition, a correlation coefficient, which was consistent with the interfacial tension, was established for evaluation of the similarity between PS samples.

Degradation Kinetics Study of Fast Ozonation Reaction in a Rotating Packed Bed

ABSTRACT The degradation kinetics of different organic compounds in a rotating packed bed (RPB) were investigated in this work. Phenol, catechol, hydroquinone, and aniline that can react rapidly with ozone were chosen to be the model pollutants, and the lumped parameter models were established to characterize the reaction rate of fast ozonation of those organic compounds in the RPB. Correlations for the lumped parameters of the organic compounds degradation (A 1) and COD removal (A 2) were obtained by fitting the experimental data. The deviations between experimental and predicted A 1 and A 2 were generally within 25%, indicating that the ozonation rate model has a good predictability for fast ozonation between ozone and organic compounds in the RPB.

Scalable synthesis of ytterbium and erbium codoped calcium molybdate phosphors as upconversion luminescent thermometer

AbstractLuminescent thermometry is a noninvasive method of temperature detection with high sensitivity and response speed. The present study demonstrated the process‐intensified synthesis of ytterbium and erbium codoped calcium molybdate phosphors (CaMoO4:Yb3+/Er3+). The experiment involved the initial premixing of the precursors using a high‐gravity rotating packed bed (RPB) reactor and subsequent calcination processing. The pronounced mass transfer and micromixing of the reactants in the RPB facilitated the scalable and controllable synthesis of CaMoO4:Yb3+/Er3+ particles with submicron sizes and regular morphologies. The CaMoO4:Yb3+/Er3+ particles exhibited a bright‐green emission with temperature‐dependent luminescence characteristics under 980 nm laser irradiation. Furthermore, the maximum absolute sensitivity was determined to be 0.02837 K−1. These results indicated that the synthesized product was a suitable candidate for application in upconversion luminescent thermometers capable of temperature sensing at the microscale.

Degradation of Bisphenol A by ozonation in a rotating packed bed: Modeling by response surface methodology and artificial neural network

The ozonation process of Bisphenol A (BPA) in a rotating packed bed (RPB) was modeled by response surface methodology (RSM) and artificial neural network (ANN). Experiments were performed according to the Box-Behnken design, and the interactive effects of various parameters including ozone concentration, pH, rotation speed of RPB and liquid flow rate on BPA degradation efficiency were investigated. Ozone concentration and pH had the most significant interactive effects on BPA degradation efficiency while rotation speed of RPB had no significant interactive effects with other variables. A second order polynomial equation was obtained to predict BPA degradation efficiency. Also, a multi-layered feed-forward ANN model was constructed based on the data of RSM experiments. Six neurons in hidden layer had the highest correlation coefficient (RANN = 0.99158). A comparison between RSM and ANN models suggested that both can accurately predict BPA degradation efficiency (RRSM = 0.99559). The highest BPA degradation efficiency (99.52 %) was achieved under the conditions of ozone concentration of 20 mg L−1, pH of 11, liquid flow rate of 10 L h−1 and rotation speed of RPB of 800 rpm, which was well predicted by the RSM model (99.54 %) and the ANN model (99.82 %). However, the RSM model was slightly better than the ANN model owing to its higher determination coefficient (R2RSM = 0.9912, R2ANN = 0.9827) and lower mean square error (MSERSM = 0.0001684, MSEANN = 0.0003305).

Enhanced Regeneration of Triethylene Glycol Solution by Rotating Packed Bed for Offshore Natural Gas Dehydration Process: Experimental and Modeling Study

To address the problems of confined space for offshore application, rotating packed bed (RPB) was firstly used to enhance the regeneration of TEG solution in natural gas dehydration process. The performance of the regeneration, which was exhibited in terms of the desorption efficiency and mass transfer coefficient, was investigated experimentally. The effects of various operating parameters, including rotation speed, gas-liquid ratio, liquid flow rate, liquid inlet temperature, and inlet concentration of rich TEG were studied to assess the impacts on the regeneration process. It was found that the purity of regenerated TEG solution by RPB was basically above 99.7% under a common gas-liquid ratio of 45 (volume ratio), and even higher than 99.98% under the optimal conditions. A mass transfer model combined two-film theory and penetration theory was established, which could well predict the TEG solution regeneration performance in RPB. According to the established model and ASPEN simulation result, an RPB and a packed column were designed respectively for a specific TEG regeneration task. It was found the volume reduction factor of RPB was about 8, which showed well adaptation of RPB for the offshore natural gas extraction due to the outstanding mass transfer performance in the TEG regeneration process.

A Review of Modeling Rotating Packed Beds and Improving Their Parameters: Gas–Liquid Contact

The aim of this review is to investigate a kind of process intensification equipment called a rotating packed bed (RPB), which improves transport via centrifugal force in the gas–liquid field, especially by absorption. Different types of RPB, and their advantages and effects on hydrodynamics, mass transfer, and power consumption under available models, are analyzed. Moreover, different approaches to the modeling of RPB are discussed, their mass transfer characteristics and hydrodynamic features are compared, and all models are reviewed. A dimensional analysis showed that suitable dimensionless numbers could make for a more realistic definition of the system, and could be used for prototype scale-up and benchmarking purposes. Additionally, comparisons of the results demonstrated that Re, Gr, Sc, Fr, We, and shape factors are effective. In addition, a study of mass transfer models revealed that the contact zone was the main area of interest in previous studies, and this zone was not evaluated in the same way as packed beds. Moreover, CFD studies revealed that the realizable k-ε turbulence model and the VOF two-phase model, combined with experimental reaction or mass transfer equations for analyzing hydrodynamic and mass transfer coefficients, could help define an RPB system in a more realistic way.