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The performance of the Trickle Bed Reactor (TBR) critically depends on the gas-liquid flow distribution in the reactor, which in turn depends on the catalyst shape, size, and structure. Extensive research has been carried out with spherical particles (catalyst),whereas industrially more complex-shaped particles (Cylindrical, Trilobe, and Quadrilobe) are used. Little work has been reported for the liquid distribution in packed beds employing these shapes.In this work, the liquid distribution was investigated in a cylindrical column of internal diameter 100 mm, containing particles of diameter 1.3 mm trilobed extrusions and length 1.8–8.8 mm. The influence of different loading methods - Central single source, solid cone, and hollow cone, gas and liquid flow rates, variation along the height of the column were studied. Air-water system was used. Pressure drop was measured with the help of a manometer and Maldistribution index (Mf) was calculated based on the variation of quantity of water collected at column outlet.It was observed that the Mf decreased with the increase in both the gas and liquid flow rate which was due to better spreading of the fluids with the increasing gas and liquid flow rate. The decrease in the Mf with the increasing gas and liquid flow rate indicates better distribution as reported in the literature 0 (best distribution) and 1 (worst distribution). Further, it was also noted that the pressure drop increased with the increasing gas and liquid flow rate. The hollow cone packing method shows the better distribution confirmed from the bulk voidage, Mf profiles, pressure drop variation, and flow profiles. A correlation has been proposed for the two-phase pressure drop for three packing methods.

Biological methanation is the production of CH4 from CO2 and H2. While this approach to carbon capture utilization have been widely researched in the recent years, there is a gap in the technology. The gap is towards the flexibility in biomethanation, utilizing biological trickling filters (BTF). With the current intermittent energy system, electricity is not a given surplus energy which will interfere with a continuous operation of biomethanation and will result in periods of operational downtime. This study investigated the effect of temperature and H2 supply during downtimes, to optimize the time needed to regain initial performance. Short (6 h), medium (24 h) and long (72 h) downtimes were investigated with combinations of three different temperatures and three different flow rates. The results from these 27 experiments showed that with the optimized parameters, it would take 60 min to reach 98.4% CH4 in the product gas for a short downtime, whereas longer downtimes needed 180 min to reach 91.0% CH4. With these results, the flexibility of biomethanation in BTFs have been proven feasible. This study shows that biomethanation in BTFs can be integrated into any intermittent energy system and thereby is a feasible Power-2-X technology. [ABSTRACT FROM AUTHOR]

A model with a high predictive quality to estimate pressure drops and liquid holdups in trickle bed reactors (TBR) is yet necessary to assist in design, up scaling, and the implementation of new processes tasks. The currently available models to estimate pressure drops and liquid holdups on TBRs exhibit important deviations, which lead to uncertainties in their applicability. To overcome the limitations in prediction deviations in the currently available models, a new model is developed based on the volume averaged two‐phase transport equations in a porous media, as developed by Whitaker. In order to develop a model that could simultaneously predict pressure drops and liquid holdup with a high accuracy, the developed model was coupled with a modification of the extended slit model reported in the literature, leading to a new hybrid model with enhanced predictability. Experimentally determined pressure drops and liquid holdup in a column with a 0.14 m internal diameter and a height of 2 m, packed with different extrudate geometries, cylinders, trilobes, and quadlobes, were used to determine the model parameters and to verify the quality of the proposed hybrid model predictions. The developed model, when compared with the experimentally determined data of pressure drops showed mean squared errors (MSE) of 0.89%, 2.31%, and 1.22% for the cylinders, trilobes, and quadlobes particles, respectively, while the liquid holdups were predicted with MSEs of 0.03%, 0.16%, and 0.01% for the cylinders, trilobes, and quadlobes particles, respectively. [ABSTRACT FROM AUTHOR]

Wall-to-bed (or wall-to-fluid) heat transfer issues in trickle bed reactors (TBR) has an important impact on operation and efficiency in this category of reactors. In this study, the hydrodynamic and thermal behavior of trickle bed reactors was simulated by means of computational fluid dynamics (CFD) technique. The multiphase behavior of trickle bed reactor was studied by the implementation of the Eulerian-Eulerian multiphase approach. Also, bed porosity effect was modeled by porosity function method. In order to study the effect of operating parameters on wall-to-bed heat transfer, the influence of catalyst particle diameter and catalytic bed porosity was investigated on wall-to-bed Nu number. The results showed that the enhancement of catalytic bed porosity from 0.36 to 0.5 decreases the Nu number about 15% due to a reduction of liquid velocity adjacent to the reactor wall. Also, the increase of particle diameter from 4 to 6 millimeter decreases wall-to-bed Nu number about 15% owing to a reduction in liquid phase volume fraction.

Highlights • Analysis for HDS process at three different scales. • Study of the validity of idealities as flow plug in TBR for HDS process. • The lack of exchange information between two scales leads to important deviations. • Effectiveness factor in insolated catalysts differ from embedded particles. • External mass resistances for catalyst leads to field jumps at the interface. Abstract For the hydrotreatment process of petroleum cuts, there is a great diversity and level of Trickle Bed Reactors (TBR) models, in which it is very common to use important simplifications, such as the consideration of plug flow; these simplifications restrict the analysis of the multiphysics and multiscale nature of the phenomena that take place in such systems. The analysis of the phenomena that take place at different scales in the TBRs is very scarce; moreover, the qualitative and quantitative determination of the information that passes from one to another scale and its influence on the mass transport nature in these systems is even more difficult to find. With the purpose of analyzing the multiphysic and multiscale nature of a reactor for an HDS process, three Computational Fluid Dynamics (CFD) models were studied at three different scales, corresponding to: (i) Heterogeneous micropores model (HMM) for a particle with explicit representation of the internal surface microstructure of the catalyst, (ii) Pseudohomogeneous catalyst particle model (PCM), and (iii) Reactor scale model (RSM). The objective sought is to establish the validity of some of the assumptions commonly made in the simulation of these types of reactors and develop an analysis to determine the importance of establishing bridges of information between the phenomena that take place at different scales. The results show that despite the small dimensions of the reactor, the plug flow assumptions might not be valid, due to the presence of strong radial gradients. It was also determined that the models that do not take into account the communication between scales (catalysts to reactor scale) differ substantially from those that do, which can be verified by the differences found for the effectiveness factors, of around 35%. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Molecular-level modelling of FCC slurry oil hydrotreating process. • Complex reaction network involving more than 15,000 reactions was built and visualized. • A method combining molecular-level kinetic model and trickle-bed reactor model is proposed. Abstract In this study, a molecular-level kinetic model of fluid catalytic cracking (FCC) slurry oil (SLO) hydrotreating in a trickle-bed reactor was developed. The physical and chemical properties of SLO were measured, and the data were used as input to tune the composition model parameters. A series of reaction rules were collected and established in terms of the reaction family according to the hydrotreating reaction mechanism. After applying the reaction rules on all the SLO molecules, a reaction network was generated containing 5,753 molecules and 15,830 reactions. The kinetic model was then built employing the Langmuir−Hinshelwood−Hougen−Watson (LHHW) formalism. The kinetic model parameters were reduced using the linear free energy relationship (LFER) and quantitative structure-reactivity correlations (QSRCs). The kinetic model was delivered to the trickle-bed reactor model, and the model parameters were tuned using experimental data obtained from a pilot hydrotreating unit. The obtained SLO hydrotreating model showed good agreement between the predicted and experimental product properties and composition under various processing conditions. The model was able to predict the concentration distribution of each species along the reactor. In addition, the influence of reaction temperature on the aromatic content and thiophene compound content was also evaluated. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Local holdup measurements in TBR for trickle to transition regimes using ERT. • Validation of ERT measurements using bottom liquid collection measurements. • Effect of distributors, gas and liquid flow rates on radial liquid distribution. • Time-resolved ERT measurements for artificial pulses verified by multi-point conductivity sensors. • Analysis of void-scale liquid structure using multi-point conductivity sensors. Abstract Trickle bed reactors (TBRs) are widely used in chemical and oil industries. Owing to complex nature of flow in TBRs, measurements of local liquid holdup distribution are rather limited. While several non-invasive measurement techniques have been used to measure liquid distribution in TBRs, the applicability of Electrical Resistance Tomography (ERT) for quantitative measurement of liquid holdup distribution is not yet verified. In the present work, measurements of local liquid distribution in a laboratory-scale TBR are carried out using ERT for trickle to transition flow regimes. The time-averaged liquid holdup distributions measured using the ERT and BLC methods were compared using the liquid maldistribution factor to demonstrate the feasibility of the ERT to measure liquid holdup distribution. The effect of liquid-distributor configurations (semi-uniform, local and one-sided) was investigated on the radial liquid distribution at different axial locations of TBR. Further, the ability of ERT to measure time-resolved local liquid distribution was verified using multi-point conductivity sensors for artificially created pulsing flow. Also, the comparison of liquid pulse width with multi-point conductivity sensor measurements was carried out and of the dispersion of liquid pulse along the length of TBR was analyzed. The ERT measurements were performed to quantify the effects of gas and liquid flow rates, and particle size on the local liquid holdup. The void-scale flow structure measured by multi-point conductivity sensors was used to analyze the macroscopic (bed-scale) liquid holdup distribution measured by ERT. Thus, the comparison of ERT measurements with time-averaged BLC and time-resolved multi-point conductivity sensor measurements is important to establish the applicability of ERT for quantitative spatial and in particular the time-resolved measurements of liquid holdup in TBRs. [ABSTRACT FROM AUTHOR]

A simulation of a trickle bed reactor aided by computational fluid dynamics was implemented. With a Eulerian approach, geometrical characteristics were explicitly considered and two simultaneous heterogeneous reactions were included, hydrodesulphurization (HDS) and hydrodenitrogenation (HDN). This was performed in order to achieve the following: (1) attain further insight into a proper scaling‐up procedure to be able to obtain the same hydrodynamics and kinetics behaviour in two reactors of different length and diameter scales; (2) develop a multiscale analysis regarding the communication of information between scales through the construction of a porous microstructure model from which the geometrical information of the microscale is captured by the effective transport coefficients (which affect the overall reactor behaviour); (3) investigate the effect of operation condition variations on hydrodynamics and kinetics; and (4) assess the deviations and further differences observed from average to punctual conversion values and the assumptions from kinetic literature models through a preliminary multiscale analysis. The CFD results were validated against experimental pressure drop data as well as HDS and HDN conversion theoretical data. An excellent agreement was found. The model produces a significant improvement in hydrodynamic parameter prediction, achieving 5 times better accuracy in predicting pressure drops and 50 % improvement in holdup prediction. The fully coupled model predicts HDS conversion with 96 % accuracy and HDN conversion with 94 % accuracy. Results suggest that the best way to obtain similar kinetic and hydrodynamic behaviour in TBRs with different lengths and diameter length scales is by equaling the liquid holdup (ϵγ) or the mass velocities (L‐G). [ABSTRACT FROM AUTHOR]

[Display omitted] • Successful biomethanation in trickle bed reactors following a solar energy pattern. • Ramp-up times of < 16 min was achieved at a rate of 40.65 ± 0.11 NL H 2 L−1 d−1. • Standby periods function as a natural clean-in-place to convert accumulated acids. • Producing grid injected CH 4 retained 50.70 % of the photovoltaic power input. • Levelised cost of production of CH 4 was demonstrated to be 147.84 $ (MWh)−1. The accelerating green transition envisions large shares of renewable intermittent power supplies, which challenges the balancing of the grid. A promising approach to long-term storage is the power-to-X technology of biomethanation. This study developed an operating model for ex situ biomethanation in a trickle bed reactor (TBR) based on daily photovoltaic (PV) solar generation profiles from the California Flats solar cell park and demonstrated long-term discontinuous biomethanation of raw biogas. The TBR was operated discontinuously for 29 days, where biomethane admissible for natural gas grid injection could be achieved within a ramp-up time of < 16 min after an adaptation period of 6 days with a purity of < 2 % hydrogen and > 97.5 % biomethane. The shutdown periods demonstrated a continuous digestion of accumulated acids and biomass. Therefore, shutting off the hydrogen addition could synergistically be employed as a clean-in-place procedure, where ∼60 % of the accumulated volatile fatty acids were converted during 12 h of standby. The TBR performance was subsequently used to evaluate the economic feasibility of integrating biomethanation to convert and store solar PV energy. The levelized cost of production of grid-quality biomethane by a small commercial biomethanation system, subject to solar PV energy (28 MWh e d−1), was found to be 147.84 $ (MWh CH4 HHV)−1 in a 2030 scenario. [ABSTRACT FROM AUTHOR]

Highlights • Finite element model of composite sorbent packed bed reactor in open-source software. • Sorption equilibrium model for CaCl 2 /zeolite Ca-X composite sorbents for various salt loadings. • Prediction of sorption kinetics of CaCl 2 /zeolite Ca-X, validated with experimental data. Abstract Composite materials consisting of a salt-impregnated porous host matrix constitute a way to combine the high energy storage density of hygroscopic salts with the fast kinetics of the carrier material. Depending on its pore structure the carrier can furthermore prevent or inhibit leakage of the salt solution. It has been shown experimentally that by impregnation with CaCl 2 the heat storage density of zeolite Ca-X can be increased by 53 % to 270 kWh m−3, which confirms the potential of this material class. In transforming this potential into technical heat storage solutions, numerical simulations can support the design process by bridging the gap between material characterization, process specification and reactor design. Such simulations rest, among others, on suitable constitutive relations. For the equilibria and kinetics of salt/zeolite composite sorbents those relations are still missing in the literature. In this work, we present an axisymmetric model of the mass and heat transport through a packed bed of composite sorbent pellets accounting for radial effects such as increased bed void fraction near the sorption chamber walls. Special focus is laid on the modelling of the sorption equilibria and kinetics of CaCl 2 /zeolite Ca-X composites of various salt loadings. The developed sorption equilibrium model for arbitrary salt loadings of the CaCl 2 /zeolite Ca-X is based on isotherm measurements of only one composite sample and one sample of pure zeolite Ca-X thereby enabling reduced experimental effort for the equilibrium characterization. The linear driving force kinetics is calibrated using data from dynamic sorption experiments on zeolite Ca-X and used to predict the dynamic sorption behaviour of CaCl 2 /zeolite Ca-X composites. We found a good predictive capability of the unmodified kinetics model for high inlet humidities—i.e., the practically most relevant cases where the composite plays its strengths. Contrarily, for low inlet humidities, the used kinetics model strongly overestimates the sorption rate, which indicates the presence of additional kinetic inhibition mechanisms under such conditions. [ABSTRACT FROM AUTHOR]

Experiments were carried out to investigate the influence of liquid flow modulation of trickle bed reactors (TBR) on biological hydrogen methanation (BHM). The modulation promises to improve the gas‐liquid mass transfer and has already been demonstrated in trickle bed reactors of other fields of application. Therefore, the influence of four different circulation intervals with pauses from two to 1,440 min was investigated in TBR for BHM. The results showed that as pause intervals without sprinkling became longer, the methane content increased from 88.61 ± 1.58 vol‐% at a circulation interval of 2 min to up to 97.19 ± 0.46 vol‐% at a circulation interval of 1,440 min. The analysis of the process liquid indicated a stable biological process at any trial phase. This study demonstrated that the performance of TBR on BHM can be significantly improved by liquid flow modulation, thus significantly reducing operating costs. To increase the performance of biological hydrogen methanation with trickle bed reactors, the influence of four different circulation intervals with pauses from two to 1,440 min was investigated. The results showed that as pause intervals without sprinkling became longer, the methane content increased from 88.61 ± 1.58 vol‐% at a circulation interval of 2 min to up to 97.19 ± 0.46 vol‐% at a circulation interval of 1,440 min. [ABSTRACT FROM AUTHOR]

Accurate prediction of the local liquid volume fraction ( ε L ) distribution, an important process parameter that governs the performance of Trickle Bed Reactors (TBRs), is still a challenge. In the present work, Eulerian multi-fluid simulations of local ε L distribution were performed in a laboratory-scale pseudo-3D (rectangular) and cylindrical TBR and the predictions were compared with the Electrical Resistance Tomography (ERT) measurements of Singh et al. (2017). The effect of formulation of capillary pressure force ( F ‾ C ) was investigated and it was found that - P C ∇ ε L definition of F ‾ C preserved the functional relation between the capillary pressure ( P C ) and ε L , and that ε L ∇ P C definition of F ‾ C reversed the same. Through the simulations performed for the pseudo-3D column, we showed that the alteration in the functional relation severely affects the ability of F ‾ C = ε L ∇ P C definition to predict the effects of particle diameter, gas and liquid flow rates. It was elucidated that such an alteration underpredicts F ‾ C and could necessitate the inclusion of additional dispersion forces for particles with small diameters. F ‾ C implemented as - P C ∇ ε L provided satisfactory predictions of the steady-state local ε L distribution for the bed pre-wetted with the pseudo-Kan pre-wetting method. However, the P C model required an empirical correction ( [ ( d P / d thr ) ( ε S ) 0.6 ] - 13.957 ) to predict the steady-state local ε L distribution in the bed pre-wetted using the Levec method. While the modified F ‾ C predicted the time-averaged local ε L distribution satisfactorily for different liquid flow rates and liquid distributor configurations, it was seen that further reduction in F ‾ C was required to predict the dynamic liquid spreading behavior under synthetically created pulsing flow conditions. [ABSTRACT FROM AUTHOR]

With whole-fraction low temperature coal tar (LTCT) as raw material, which boiling point range is 209–514 °C. This paper conducts hydrotreatment (HDT) test for 1176 h on trickle-bed reactor (TBR) with commercial NiMo/Al 2 O 3 -SiO 2 catalyst. The reaction conditions are as follows: reaction temperature 613–653 K, reaction pressure 10–14 MPa, liquid hourly space velocity (LHSV) 0.2–0.4 h −1 , and hydrogen-to-oil volume ratio 1000:1. Considering the short life of coal tar HDT catalyst, a kinetic model of whole-fraction LTCT hydrodesulfurization (HDS) including running time ( t 1 ) and catalyst half-life ( t c ) was established. The kinetic parameter estimation was conducted according to the experimental data, and the results are as follows: activation energy 94965 J/mol, reaction order 1.5, and the relative error of the model is less than 5%. Based on the premise of steady state operation, the HDS reaction happened in the three-phase trickle-bed reactor was simulated by combining the mass transfer, reaction kinetics model and physical property data of LTCT. The results show that the experimental and simulated values of sulphur content at the exit of the reactor are within the error range of 5%. By simulating the whole-fraction LTCT HDS reactor, the pattern of changes in the concentrations of hydrogen sulfide, hydrogen and sulfur in gas, liquid and solid phases according to the length of the reactor were obtained. Based on this, this paper discusses on the impacts of each process parameter and hydrogen sulfide partial pressure on LTCT HDS, and works out the reaction characteristics of whole-fraction LTCT HDS different from crude oil fraction. Finally, this paper analyzes the influence of different process conditions on internal gradients of catalyst, and concludes the influence of each parameter on effectiveness factor of particle. The increase of temperature, decrease of pressure or increase of LHSV can all cause the decrease of effectiveness factor, wherein the temperature has the most significant effect on the effectiveness factor, followed by LHSV, and pressure has the weakest effect. These findings contribute to a more in-depth understanding of the features and rules of LTCT HDS, and can also give us some guidance for industrial reactor simulation. [ABSTRACT FROM AUTHOR]

The paper introduces an alternative optical-based methodology allowing to investigate a liquid spreading process inside packed beds. In particular it allows determining the boundary between the wetted and the dry region inside the packing section. Due to optical nature of the approach it can be applied only when both column and its internals are made of transparent materials. The proposed experimental procedure has been used to investigate the liquid distribution inside the packed bed composed of 6 mm Raschig rings made of glass. Distilled water was adopted as a flowing medium and was injected into the column from a source point. The obtained results allowed performing qualitative assessment of the process and allowed determining both the contact distance (required for the liquid to reach the column wall) and the wetted volume of the column as a function of the liquid Reynolds number. The experiment has been also supplemented with measurements of a liquid holdup performed with the use of two different methods. [ABSTRACT FROM AUTHOR]

Hydrodynamic data obtained from laboratory‐scale trickle‐beds often fail to accurately represent industrial‐scale systems with high packing aspect ratios and column‐to‐particle diameter ratios. In this study, pressure drop, liquid holdup, and flow regime transition were investigated in a pilot‐scale trickle‐bed column of 33 cm ID and 2.45 m bed height packed with 1.6 mm × 8.4 ± 1.4 mm cylindrical extrudates for air‐water mass superficial velocities of 0.0023 – 0.094 kg/m2s and 4.5 – 45 kg/m2s, respectively, at atmospheric pressure. Significant deviation was observed from pressure drop and liquid holdup correlations at low liquid flows rates, corresponding to gravity‐driven flow limit. Likewise, liquid saturation is overestimated by correlations at high liquid flow rates, owing to significantly reduced wall effects. Lastly, trickle‐to‐dispersed bubble flow and trickle‐to‐pulsing flow regime transitions are reported using a combination of visual observations and analysis of the magnitude of local pressure fluctuations within the column. © 2018 American Institute of Chemical Engineers AIChE J, 64: 2560–2569, 2018 [ABSTRACT FROM AUTHOR]

Phenol and phenolic derivatives found in different industrial effluents are highly toxic and extremely harmful to human and the aquatic ecosystem. In the past, trickle bed reactor (TBR), reverse osmosis (RO) and other processes have been used to remove phenol from wastewater. However, each of these technologies has limitations in terms of the phenol concentration in the feed water and the efficiency of phenol rejection rate. In this work, an integrated hybrid TBR–RO process for removing high concentration phenol from wastewater is suggested and model-based simulation of the process is presented to evaluate the performance of the process. The models for both TBR and RO processes were independently validated against experimental data from the literature before coupling together to make the hybrid process. The results clearly show that the combined process significantly improves the rejection rate of phenol compared to that obtained via the individual processes. [ABSTRACT FROM AUTHOR]

An A. nidulans strain with a pyridoxine marker was used for continuous production of aryl alcohol oxidase (AAO) in a trickle bed reactor (TBR). Modified medium with reduced zinc, no copper, and 5 g/L ascorbic acid that reduced melanin production and increased AAO productivity under growth limited conditions was used. Two air flow rates, 0.11 L/min (0.1 vvm) and 1.1 L/min (1.0 vvm) were tested. More melanin formation and reduced protein productivity were observed with air flow rate of 1.1 L/min. Three random packings were used as support for the fungus inside the TBR column, two of which were hydrophobic and one which was hydrophilic, and three different dilution rates were tested. The use of GEA BCN 030 hydrophobic packing resulted in greater AAO yield and productivity than the other packings. Increasing dilution rates favored melanin formation and citric, lactic and succinic acid accumulation, which decreased AAO yield and productivity. [ABSTRACT FROM AUTHOR]

Bifunctional hydrodeoxygenation catalysts containing both metal and metal oxide phases are widely employed in biomass upgrading reactions. Determining the oxidation state of metals in such complex reaction media has been challenging. In this work, we developed a high-pressure trickle-bed reactor capable of conducting temperature-programed reduction of catalysts after liquid-phase reactions without exposing the catalyst bed to ambient conditions. Two case studies on metal/metal oxide catalysts employed in key biomass upgrading processes were investigated. The reduction of the RuOx phase in Ru/RuOx/SiO2 occurs at temperatures as low as 115 °C via catalytic transfer hydrogenation reactions using liquid 2-propanol as a hydrogen source. Pretreatment of Ir-ReOx/SiO2 catalyst with H2 in the presence of either liquid cyclohexane or liquid water reduces Re to an oxidation state of +2.6, while the residual ReOx phase cannot be reduced in H2 at up to 900 °C. [ABSTRACT FROM AUTHOR]

Abstract: BACKGROUND: Hydrogenolysis of glycerol to glycols in continuous flow three phase reactors is of practical importance due to the need to give value to huge amounts of surplus glycerol. Thermodynamic and kinetic aspects must be revised for a proper design. The system was studied in a trickle‐bed reactor using copper chromite and Cu/Al2O3 as catalysts. RESULTS: Phase equilibrium and flow pattern were verified. Solid, liquid and gas phases were present, with the liquid phase in ‘trickling’ flow. Catalysts were characterized by inductively coupled plasma (ICP), nitrogen sortometry, X‐ray photoelectron spectroscopy (XPS), X‐ray diffraction (XRD), temperature programmed reduction (TPR) and pyridine thermal programmed desorption (TPD). The average reaction rate was found to be practically constant under different process conditions. A theoretical analysis indicated that the resistance to the transfer of hydrogen from the gas to the liquid phase dominated the overall kinetics. Selectivity to 1,2‐propanediol varied with temperature, with a maximum at 230 °C (97%). Selectivity was a function of the catalyst acidity. When the pressure was increased the selectivity to 1,2‐propanediol was increased, up to 97% at 14 bar. Higher pressures did not modify this value. CONCLUSIONS: Optimum reaction conditions for maximum selectivity to 1,2‐propanediol with Cu‐based catalysts are 230 °C and 14 bar. System kinetics are, however, dominated by the gas–liquid mass transfer resistance. © 2017 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

Many industrial scale trickle bed reactors (TBR) operate at lower liquid superficial velocities (

This work presents a model for UOP Coker Complex Hydrotreating Process using Aspen HYSYS Petroleum Refining module. The model depends on routinely taken industrial data of process streams during normal operating conditions. Acquired data sets have been tested and screened in order to ensure data validity for building the model and avoiding erroneous results. A detailed kinetic model of hydrotreating reactions in the reactor has been applied. The trickle bed reactor (TBR) model has been validated using 3 months of industrial plant data. In addition, rigorous tray-by-tray simulations for hydrogen sulfide absorption tower and TBR effluent fractionation tower have been utilized to match the performance of the plant’s towers. The model has been used then for studying the effects of different process variables on the plant performance. In addition, the model has been used in optimizing the operating conditions of the process. This optimization showed a potential for notable savings of fuel and energy consumption in the process, while increasing the process productivity. [ABSTRACT FROM AUTHOR]

A sorption enhanced-steam methane reforming (SE-SMR) process was investigated in a countercurrent gas-solid trickle flow reactor packed with regularly stacked catalyst. The stacked catalyst was made of corrugated Pt/Ni/Al2O3 plates in the form of static mixers. Experiments were carried out in a temperature range of 550-600 °C, total pressure of 4.0 bar, and water to methane ratio of 4.0 in the reactor feed. Within the investigated conditions, experimental results offered a solid proof of concept for new continuous SE-SMR operation for production of hydrogen where sorbent can be regenerated separately from the catalyst. Experimental data were reasonably well described by a plug flow model for both the gas and solid phases. The mathematical model was further used to optimize the continuous SE-SMR operation: it could be demonstrated that the level of the hydrogen purity in the reactor exit stream could be controlled by a multistage reactor consisting of alternating catalytic active and stainless-steel inert static mixers. [ABSTRACT FROM AUTHOR]

Liquid holdup is a crucial parameter when operating catalytic trickle bed reactors related to wetting efficiency and residence time. Most of the classical methods are expensive, time-consuming, or not valid for high pressures. Liquid holdup by gravimetric recirculation (LHGR) measurement method determines the average total liquid holdup using a closed loop with total recirculation of liquid. The recirculating liquid is contained in a vessel that is weighed instantaneously with a known amount of liquid. The difference between the initial amount of liquid and the instantaneous weight gives the liquid holdup. Main benefits are the following: first, the measurement takes only the time of stabilization that at laboratory scale is 2-5 min; second, the system is ready for the next measurement without any modification (the bed is not disturbed nor modified); third, it works for high pressures; finally, it gives values comparable to those from classical techniques like RTD or conductivity methods. [ABSTRACT FROM AUTHOR]

In this work, computational fluid dynamics (CFD) has been used to investigate diesel hydrotreating (Hydrodesulfurization (HDS) and Hydrodearomatization (HDA)) in a laboratory scale trickle bed reactor (TBR). In order to investigate these reactions, the 3D model was developed using a multi-phase Eulerian-Eulerian approach, an inter-phase interaction model, a porosity distribution model for the trilobe particles, mass transfer and chemical reactions model. Due to the small dimensions of the reactor, the simulations are carried out at isothermal and transient conditions and the catalyst bed is considered to be fully wetted. In this first phase of the work, a reaction model was used, which was later validated. Then, a counter-current reactor is simulated and the results are compared with a co-current reactor. The analyzed parameters are conversion, pressure drop and liquid holdup and a special attention was given in order to verify how operational changes on pressure, temperature, velocity and gas and liquid flows influence the reactor performance. The influence of porosity on fluid velocity and volume fraction of liquid is also investigated. Finally, the influence of the liquid hourly space velocity (LHSV), temperature, gas-liquid ratio and partial pressure of H 2 S are also discussed. The results for the two types of reactors are similar despite the fact that the counter-current arrangement has achieved lower conversions. [ABSTRACT FROM AUTHOR]

The catalytic exchange column of countercurrent trickle bed for deuterium removal from hydrogen is simulated based on experimental results along with established reaction and mass transfer models, accounting for the humidification of hydrogen in a catalyst bed filled with platinum/styrene-divinylbenzene copolymer pellets and Dixon rings. Relative deviations of less than 30% are achieved between the experimental and the simulated HD molar fractions at the column outlet. Simulation results indicate that hydrogen humidification exerts a noticeable influence on gas and liquid phase flow rates, leading to an overestimated removal percentage of deuterium when such flow rate variances are neglected. Rate limiting step for the overall gas-liquid isotopic exchange is discussed. Finally, the operation conditions are optimized using the developed model. [ABSTRACT FROM AUTHOR]

A divided-cell trickle bed electrochemical reactor (TBER) with a porous cathode composed of carbon black and polytetrafluoroethylene was developed for generation of hydrogen peroxide. An important feature of the reactor is a divided cathode of different cells made with stainless steel mesh. This division into a sectional cathode resulted in a concentration of hydrogen peroxide that is more than twice that produced in an undivided cathode. The much improved performance was attributed to the even distribution of electrolyte and oxygen in the cathode bed, as well as an effective mass transport of oxygen from the gas phase to the electrolyte-cathode interface. Hydrogen peroxide generation was demonstrated from electrochemically reducing oxygen in concentrated alkaline electrolyte solutions using the TBER. Factors for the hydrogen peroxide electrosynthesis were systematically studied, including cell potential, electrolyte flow rates and concentrations, temperatures, and the number of cells. [ABSTRACT FROM AUTHOR]

In this contribution we report on spatially resolved analysis of multiphase hydrodynamics in solid foam packed trickle bed reactors. For the investigation we used ultrafast X-ray computed tomography and fast response pressure transducers. The SiSiC foams’ pore density, the liquid distribution system as well as gas and liquid flow rates were varied. The transient behavior of the liquid holdup at trickle and pulse flow as well as after drainage were examined and correlations for static and dynamic holdups were derived. The correlations are based on Eötvös, Reynolds and Galileo number, using porosity and specific area for the definition of the hydraulic diameter. The correlations are applicable to a wide range of foam morphologies, pore densities and operating conditions reported in the literature. The axial pressure gradients in the solid foams showed significantly lower pressure drop compared to particle packings of similar specific surface area. The evolution of liquid spreading was analyzed qualitatively and quantitatively with various irrigation patterns. In addition, an approach for the determination of radial liquid dispersion coefficients in solid foams is presented. [ABSTRACT FROM AUTHOR]

Heat transfer plays an important role in several applications of packed bed reactors with cocurrent downflow of liquid and gas (widely known as trickle-bed reactor – TBR). A literature survey shows that the amount of articles dealing with the prediction of heat transfer rates between a TBR and an external heating or cooling source is limited for spherical catalyst pellets and definitively scarce for other pellet shapes as cylinders and multilobes. Results from an experimental program devoted to study heat transfer between a TBR and an external jacket, employing spherical and cylindrical particles and a commercial trilobe pellet, are presented. A wide range of gas (air) and liquid (water) flow rates were covered corresponding to low and high interaction regime. A two dimensional pseudohomogeneous model was employed to represent the thermal behavior of the packed bed. Values of the effective radial thermal conductivity and the wall heat transfer coefficient were obtained by regression of radial temperature profiles for three different bed lengths. Finally, expressions to estimate both parameters for the different particle shapes were developed, thus providing a useful predictive tool, not available in the literature up to the best of our knowledge. [ABSTRACT FROM AUTHOR]

Wetting of partially wettable porous solids is encountered in many and diverse applications such as imbibition of liquid reactants into pores of porous catalysts and adsorbents in reactor beds, water vapor condensation on porous substrates like leaves, and spreading of liquid condensate on fuel cell membranes. This wetting is a combination of liquid spreading/retraction on the external surface and imbibition into the pores. In this paper, we establish the basic “building block” of this problem, i.e. , the dynamics of wetting and retraction of a thin film in the vicinity of a single infinite pore of a porous solid and show the way forward by discussing the case of two such adjacent pores. The coupled process described by a unified and simple model derived from equations of motion under the lubrication approximation for thin film flow on the external surface and Hagen-Poiseulle flow inside the pores. A single final evolution equation tracks the externally wetted region in time by solving for the height of the liquid surface starting from an initial liquid droplet. The wetted area initially expands as the droplet spreads and then contracts as droplet retracts due to imbibition in the pore. The liquid surface becomes increasingly liable to rupture under the influence of intermolecular forces as it thins because of imbibition. The governing equation can track the rupture and subsequent dewetting of the surface also. The liquid morphology and kinetics of wetting show good agreement with the reported experiments implying that the description of a spreading liquid as a thin film indeed manages to incorporate the most important physics governing the internal wetting of liquids on porous substrates at the micro scale. The model shows a possible way to develop wetting correlations for larger scales of flow in industrial trickle bed reactors in a bottom-up manner. [ABSTRACT FROM AUTHOR]

The use of high-pressure, high-temperature diesel stripper ahead of the reactors boosts low-sulfur diesel production on existing HDT units. The new hydrotreating process scheme use a combination gas phase and liquid phase reactors to treat Diesel. The gas and liquid properties of the stream were determined in dynamic conditions and hydrocarbon vaporization and gases solubility simulated based on Peng-Robinson state equation with modified pseudo-species properties, interaction coefficients and mixing rules. The gas-liquid pseudo-equilibrium simulation allows calculation of concentration of pseudo-species present in gas-liquid separators and in reactors along the cycle length. The new experimental vapor-liquid equilibria data were developed for synthetic feed, diesel, diesel plus hydrotreated product and product of reaction at high-temperature and high-pressure. This data was used to developed new sets of A kl , B kl , E and F parameters for interaction coefficients and blending values. The results of simulation using Peng Robinson EOS state equation with new interaction coefficients and rules for blending show an improvement in the prediction of pseudo-species vaporization and solubility of hydrogen, methane, ethane, and hydrogen sulfide on liquid phase (diesel). Prediction of gas-liquid pseudo species concentration and phase properties along the cycle length have significant impact on the economy of the new HDT process. Experimental dynamic VLPE data is included. [ABSTRACT FROM AUTHOR]

Bistable ring (BR) based strong PUFs are promising candidates for lightweight authentication applications. It has been observed that a good ‘0’/‘1’-balance of their responses correlates with longer settling times. This is problematic, since the state-of-the-art evaluation method requires the BR to be settled in order to generate a reliable PUF response. We show that settling times can easily extend beyond 100 ms for 70 percent of the responses in the TBR PUF, which is a BR-based PUF with good ‘0’/‘1’-balance characteristics. Hence, it is practically impossible to wait for all BRs to settle, which results in a reliability penalty. In order to solve this problem, we present three new methods, which allow the evaluation of unsettled BRs with increased reliability compared to the state-of-the-art method. We were able to improve response reliability from 81 percent to up to 98.5 percent and achieve response reliabilities of 97 percent at an evaluation time of 320 ns. This enables the fast and reliable use of BR-based PUFs in strong PUF applications. [ABSTRACT FROM AUTHOR]

Biological conversion of the biogas produced by landfills and anaerobic digestion systems (60–70% methane (CH 4 ), 30–40% carbon dioxide (CO 2 )) to methanol using methanotrophs (aerobic CH 4 -oxidizing bacteria) is an emerging approach to convert waste-derived biogas to liquid chemicals and fuels. The purpose of this work was to develop a trickle-bed reactor (TBR) to improve mass transfer of CH 4 and oxygen (O 2 ) to methanotroph growth media for enhanced CH 4 oxidation and methanol production. Mass transport of O 2 in a TBR packed with ceramic balls was nearly two-fold higher than an unpacked TBR. CH 4 oxidation in the TBR (0.4–0.6 mmol/h) was about four times higher than that in shake flasks that used similar inoculum and headspace:volume and biogas:air ratios. Using optimal operating parameters (biogas:air = 1:2.5, 12 mmol formate addition, 3.6 mmol phosphate), methanol productivity (0.9 g/L/d) from the non-sterile TBR was among the highest reported in the literature. Operation under non-sterile conditions caused differences in the microbial community composition between experiments, and the most predominant methanotrophs appeared to be members of the genus in which the inoculum is classified ( Methylocaldum sp. 14B). [ABSTRACT FROM AUTHOR]

Flow regime effect and reactor modeling studies in a gas-liquid downward flow fixed bed reactor were conducted for acetophenone hydrogenation on 1% Rh/Al 2 O 3 catalyst, a relatively complex reaction scheme typical of pharmaceutical applications, using a 7.1 mm ID stainless steel reactor with 0.5 mm catalyst spheres at elevated pressures. A flow regime transition map for trickle and bubbly flows was determined visually in a transparent reactor surrogate and confirmed by monitoring pressure drop fluctuations for different gas/liquid systems, tube/particle materials, and operating pressure and temperature. The flow regime at each operating condition for the opaque stainless steel reactor was identified solely using pressure drop fluctuations. The beneficial effect of bubbly flow on reaction rate was confirmed experimentally at gas and liquid superficial velocity ranges of 0.02–0.19 m/s and 2.5–12 mm/s, respectively, under 80–100 °C, 11–26 bar and 0.04–0.6 M initial substrate concentration. Gas flow rate, temperature, and pressure variations were used to study the effects on reaction performance of partial wetting of the catalyst and of liquid-solid diffusion limited reaction. A reactor model including external/internal mass transfer and flow regime effects was developed using an adjustable parameter to account for partial wetting and flow regime effects. The parameter was fitted using a subset of the experiments, and the model provided good prediction (R 2 > 95%) of all remaining experiments. [ABSTRACT FROM AUTHOR]

We performed a numerical analysis for simulating granular media structures containing non-spherical elements and the liquid trickle flow characteristics of such structures. Fully-Lagrangian numerical simulation methods can track all motion information for solid or liquid elements at each point in time. We introduced suitable compressibility to moving particle semi-implicit (MPS) and performed individual packing behavior calculations for non-spherical elements, based on discrete element method (DEM) with expanded functions. Rigid bodies-DEM is a method using a DEM contact force model that is expanded to handle the motion of freely shaped solids. It expresses complex shapes to enable low calculation costs and intuitive mounting. We used the boundary for the granular media configured with non-spherical elements to implement a trickle flow simulation based on weakly compressible-MPS. Even for elements of equal volume, different shapes changed the liquid passage velocity and hold-up amount. The mean downflow velocity of the liquid phase was not always dependent on the void fraction. For the plane of projection, we obtained a good correlation with the mean downflow velocity in each packed structure, and successfully performed arrangements according to the new liquid-passage shape coefficient. © 2016 American Institute of Chemical Engineers AIChE J, 63: 2257-2271, 2017 [ABSTRACT FROM AUTHOR]

The paper is devoted to interfacial heat exchange between gas and liquid flowing countercurrently through a packed bed in a trickling flow regime. The lack of correlations describing the interfacial gas-liquid heat transfer coefficient makes problems when numerical models of non-isothermal flows in porous media are being developed. Thus the experimental investigation was undertaken with the use of a column of 0.1 m inner diameter, equipped with 6 mm glass Raschig rings. Air and water were used as working fluids. The loads of media ranged between 0.0177–0.1415 m 3 ·(m 2 s) − 1 and 0.0007–0.0053 m 3 ·(m 2 s) − 1 for gas and liquid phases, respectively. The inlet water temperature was changed within the range between 30 °C and 70 °C whereas the inlet air temperature was kept constant at the level of (21 ± 1) °C. It was found that interfacial heat transfer coefficient is strongly dependent on the gas load, noticeably dependent on the temperature difference between phases and slightly dependent on the liquid load. The results of the experiment were used to develop a new correlation describing the interfacial heat transfer in the packed bed expressed by the Nusselt number. Various group numbers were considered in order to account for the impact of gravity, surface tension, thermal diffusion and free convection on the interfacial heat transfer. After detailed regression analysis the correlation of the form Nu = Re G 1.169 · Ga G - 0.8399 · E o ¨ 0.7176 was finally proposed as the most fitting the experimental data. [ABSTRACT FROM AUTHOR]

A wide range of volatile organic compounds (VOCs) chemical characteristics (aromatic, sulfur-containing organics and alcohol) were selected to demonstrate a prospective potential of the biotrickling technology in practical applications through the appropriate selection and combination of biological ‘agents’. The principal objective of this study was to specify operating boundaries of parameters at which the sampled microorganisms were most effective in the biodegradation of gaseous streams containing styrene, ethanol and dimethyl sulfide mixture at dynamic variations of pollutant load. The average conversion factor for the 3-component VOCs mixture was higher than 95% at lower range of the individual pollutant load and basically fell to 80% at middle range vs. 55% at the higher contaminant loads; however, the effectiveness of ethanol biodegradation is stable at the entire investigated range of the mass load. The consequences of an unexpected pollutant overload (media clogging) and the time necessary for the subsequent regeneration of the microbial community and restoring the process stability were investigated as well. [ABSTRACT FROM AUTHOR]

Various Ni-based catalysts were tested in the continuous liquid phase hydrogenation of levulinic acid (LA) to γ-valerolactone (GVL) in a trickle-bed reactor using water as solvent with the aim to develop an economic and environmentally friendly way for the GVL synthesis. For this purpose, various synthesis methods were used to prepare Ni-based catalysts, which were first screened in batch reactors. Characterization by X-ray diffraction, temperature-programmed reduction, electron microscopy, hydrogen chemisorption, and X-ray absorption spectroscopy showed that slow precipitation using urea resulted in a good Ni dispersion. The dispersion also improved at lower Ni loading, and smaller Ni particles mostly showed an enhanced catalytic performance for the synthesis of GVL. 5 wt % Ni/Al2O3 prepared by wet impregnation showed the highest specific activity for the hydrogenation of LA to GVL (90% LA conversion and 75% GVL yield) featuring an average Ni particle size of 6 nm. Some deactivation of the catalysts was observed, probably due to transformation of γ-Al2O3 to boehmite and sintering of the Ni particles. In addition, reoxidation of Ni particles may additionally lead to deactivation as concluded by comparison with screening studies in batch reactors. [ABSTRACT FROM AUTHOR]

In the class of three-phase catalytic reactors, trickle-bed reactors (TBRs) are the most extensively used in industry. They are utilized in petrochemicals, petroleum, chemicals, waste treatment, electrochemical and biochemical processing, and many other applications. One of the most significant applications of TBRs is their utilization in the process of purification. Since the purified product has to meet the required specifications of a high quality chemical, the TBRs operation control is very critical. Considerable fluctuation of the operating parameters values adversely affects the reactor efficient performance. In this paper, the effect of hydrodynamic parameters on the hydropurification TBR operation is investigated considering the product quality. A first principle heterogeneous model incorporating the hydrodynamic parameters and catalyst deactivation has been developed to analyze the reactor performance under the fluctuation of the hydrodynamic parameters. The devised model along with its mathematical solution has been coded into MATLAB R2016a environment. The results reveal that the deviation of hydrodynamic parameters of liquid holdup and gas holdup considerably influence the efficiency of the purified terephthalic acid reactor operation in term of product quality. Moreover, the impact of liquid holdup on the reactor operation is more than gas holdup in term of product quality. These research findings might be applied into an actual operating system mentioning that the deviation from trickling flow regime is to be avoided in the reactor. [ABSTRACT FROM AUTHOR]

Different flow regimes are known to occur in the interaction of multiphase gas–liquid flows over packed beds of solid particles, such as those observed in trickle bed reactors (TBRs). There are four major flow regimes that are known to occur in downward cocurrent flow in TBRs, namely: trickle, pulse, bubble, and mist flow regimes. In this work, the focus is on macro-scale experimental visualizations and investigations of the flow regimes in a two-dimensional TBR. Experimental observations are made to investigate the development and transition of these flow regimes over a wide range of liquid and gas velocities. Cylindrical particles are placed between two glass plates that are sealed on the sides, and water and air are injected over them using an injection manifold to simulate multiphase flow in a TBR. A diffused light emitting device (LED) light table is used to illuminate the experimental window, while real time images are obtained using a high-speed camera. Flow maps are reported depicting all four regimes and the transition regions between them. Transition regions occur where the characteristics of more than one flow regime coexist. The 2D experimental results are then compared with the existing literature data of three dimensional results and found to be in good agreement. Emphasis is placed on the transition between the trickle and pulse regimes, since that is the most important mode of operation in industrial TBRs. It is observed that the change in diameters of the cylindrical particles in a two-dimensional TBR has little effect on the transition between the flow regimes when the porosity of the bed is kept constant. [ABSTRACT FROM AUTHOR]

Continuous oxidation by oxygen gas of 2-propyl mercaptan and n-butyl mercaptan present in naphtha are implanted in a trickle bed using a locally prepared catalyst. Incipient Wetness Impregnation method is used to load cobalt on activated carbon (2% Co/AC). Characterization tests, Scanning Electron Microscopy, X-ray diffraction, CO2-Temperature Programmed Desorption, Temperature Programmed Reduction, and BET surface area showed that the prepared catalyst has an efficient catalyst characteristics. Also, they indicates that Incipient Wetness Impregnation method is good for impregnating cobalt on activated carbon. A catalyst evaluation has been done in a fixed bed reactor and the operating conditions of mercaptans oxidation process varies within a range for each parameter: temperature range (20°C to 80°C), liquid hour space velocity range (2.5 hr-1 to 10 hr-1), initial concentration of 2-propylmercaptan range (75 ppm to 300 ppm), and initial concentration of n-butyl mercaptan range (100 ppm to 400 ppm). Oxygen pressure is kept constant at 2 bar gauge pressure while the oxygen/mercaptans molar stoichiometric ratio was 10. [ABSTRACT FROM AUTHOR]

A phenol-oxidizing Ralstonia eutropha was examined for its potentiality to degrade p-nitrophenol (PNP) and phenol in a cometabolic fashion in a trickle bed reactor (TBR) using Kissiris as a packing material. In explaining the kinetic behavior of the cells, responses of the freely suspended cells were also recorded. The kinetic parameters pertinent to growth, cell decay, product toxicity, competitive inhibition between substrates, and enhancement in cometabolic transformation as a result of the presence of the growth substrate, which are all inherent to the cell behavior, were determined experimentally, analyzed quantitatively, and modeled mathematically. By considering the total degradation time, including the length of lag phase period, phenol degradation was under adverse effect of PNP presence in the system, while phenol had an enhancing effect on the formation of biomass and degradation of PNP when it was used along with variable levels of PNP. The inhibition coefficient of PNP on phenol degradation (Kic) and that of phenol on PNP transformation (Kis) were determined to be 2.36 mgc L–1 and 86.02 mgs L–1, respectively. This indicates that PNP imposed much larger competitive inhibition to phenol utilization by the cells than the converse. Predicted values of the proposed model for simultaneous utilization of PNP and phenol by the test bacterium were in good agreement with the experimental data. Cell immobilization could increase cell tolerance to higher concentrations of both substrates. However, the values of specific degradation rates of the substrates were lower in TBR as a result of excessively higher biomass formed as compared with the content of the cells in shake flasks studies. [ABSTRACT FROM AUTHOR]

This novel study is experimental and modeling. In experimental section a pilot package including trickle bed reactor, automatic dosing pump, measuring instruments, gas chromatograph apparatus and five sample points along the reactor were employed to investigate the performance of propylene hydrogenation through structured catalyst bed under concurrent and countercurrent flow patterns. The experimental setup was configured in two different modes providing countercurrent and concurrent pattern for liquid phase and gas phase flow. First liquid propane containing propylene impurity flew from top of the reactor and hydrogen was injected from bottom as a gas phase counter-currently thereafter liquid and gas contacting phases both flew from bottom side of the reactor concurrently. Propylene content of liquid propane was hydrogenated through structured catalyst bed filling the pilot reactor and sampling has been done after establishing steady state conditions. In modeling a set of 12 partial differential equations (PDEs) were developed for dynamic modeling of current process including mass transfer and momentum transfer equations in liquid and gas phase. Afterward orthogonal collocation method was utilized to solve developed PDEs. Finally the results of mathematical modeling showed good consistency with experimental data. Furthermore, the sample analysis showed nil concentration of propylene in countercurrent flow in several operating condition, however nil concentration of propylene was not reported in concurrent flow pattern even by increasing the liquid flowrate. [ABSTRACT FROM AUTHOR]

A Trickle Bed Reactor equipped with a non-ideal distribution tray is investigated. First, a non-ideal co-current trickling flow of nitrogen and heptane, induced by a partially plugged tray, is characterized experimentally using the γ-tomography technique. Resulting liquid saturation data are used to validate the Euler-Euler CFD model developed in previous work of Solomenko et al.[16] on a 3D realistic flow. The resulting 3D CFD model is then coupled with simple isothermal kinetics of heteroatom removal of heavy petroleum cuts, and the effect of maldistribution on reactor performance is discussed. The problem of CFD model reduction to a 1D reactor model is finally addressed based on transport of internal ages distribution theory. Different 1D models are compared based on reactor effluent throughput. It is shown that a 1D-Multi Exit reactor model that respects both the age variance at the system outlet as well as the degree of mixing inside the reactor gives the best prediction of the reactor performance. [ABSTRACT FROM AUTHOR]

Trickle beds are among the most used reactors in different sectors of chemical industries. In this work the aim was to develop a general heterogeneous multiscale model for continuous trickle bed reactors, which enables the calculation of instantaneous concentration and temperature changes as well as the stationary behaviour of the reactor. The model development was based on solving simultaneously both the energy and mass balances for the continuous gas and liquid phases and for the stagnant catalyst particles. Mass transfer coefficients and pressure drop equations from well-established correlations were used. The developed model is aimed to be as general as possible in order to be used as a framework for other kind of bed reactors and arbitrary reaction schemes. The model can be simplified taking into consideration only one or two phases, and in this case it was applied to catalytic sugar oxidation to sugar acid and the effect of catalyst shape and size was investigated. Simulation results revealed that complete sugar conversion was achieved only for small catalyst particles, also the length of the reactor affects the conversion of arabinose more than the residence time or the bed radius: in fact for much bigger particles the conversion can also be achieved for longer reactor beds. [Display omitted] • Development of 3 phases dynamic trickle bed reactor model. • Developed model was used to study the arabinose oxidation. • Effect of shape and size of catalyst was studied numerically. • Model was successfully implemented in gProms. [ABSTRACT FROM AUTHOR]

Two-phase flow dynamics and hydrodesulfurization (HDS) performance were numerically analyzed for vertical, inclined, and oscillating trickle beds with a prospect of assessing the potential of implementing HDS operations on marine floating platforms. An unsteady-state three-dimensional model based on the macroscopic volume-averaged mass, momentum, energy and species balance equations coupled with simultaneous diffusion and chemical reaction within sulfide CoMo/alumina catalyst was developed for the purpose of comparative analyses using H 2 /dibenzothiophene/ n -hexadecane model system. Angular uniform and sinusoidal oscillatory motion of the reactor between two angled symmetrical positions and between vertical and an inclined position was considered. As in the case of cold-flow passive conditions, in chemical reaction environment two-phase downflow deviates considerably from axial symmetry at higher reactor inclinations with noticeable liquid accumulation in the bottommost reactor cross-sectional area on the tilting side. Also, externally-induced reactor periodic oscillation generates complex reverse secondary flow in radial and circumferential directions and oscillatory patterns of flow field with the amplitude and propagation frequency affected by the type (uniform or sinusoidal), amplitude and period of angular motion of reactor. Inclined, symmetric and asymmetric oscillating trickle-bed reactors underperform the vertical configuration and the decline of symmetric oscillating trickle-bed reactor hydrodesulfurization performance is lower under uniform oscillatory motion conditions. Oscillating trickle-bed reactors generate an oscillatory hydrodesulfurization performance which is affected by the parameters of angular motion of reactor. The inhibiting effect induced by H 2 S on the hydrogenolysis is considerable at higher packed bed inclinations and in symmetric oscillating trickle-bed reactors. [ABSTRACT FROM AUTHOR]