Effect of hydrodynamic multiplicity on trickle bed reactor performance

Merwe, Willem van der; Nicol, Willie; Al‐Dahhan, Muthanna H.

doi:10.1002/aic.11360

Cited by 9 publications

(17 citation statements)

References 30 publications

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“…Previously, multiplicity of liquid–solid mass transfer in trickle beds has been explained as a combined liquid holdup–wetting efficiency effect 26. At a specific superficial liquid velocity, a low liquid holdup should enhance mass transfer because of higher interstitial liquid velocities.…”

Section: Resultsmentioning

confidence: 99%

“…The rest of the start‐up procedure is the same as for upflow. For most hydrodynamic parameters, Levec prewetting represent the lower boundary of multiplicity in prewetted beds 26 Extensively prewetted trickle flow .…”

Section: Methodsmentioning

confidence: 99%

“…Few studies exist that attempt to quantify the effect of flow history or prewetting on wetting efficiency24 and liquid–solid mass transfer 25. Moreover, direct studies of the effect of multiplicity on reactor performance are scarce 26. In this investigation, two of the prewetting methods as summarized by van der Merwe and Nicol27 are used to explore the boundaries of multiplicity behavior.…”

Section: Introductionmentioning

confidence: 99%

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Parallel hydrogenation for the quantification of wetting efficiency and liquid–solid mass transfer in a trickle‐bed reactor

Houwelingen

Nicol

2011

AIChE Journal

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A novel method for the measurement of wetting efficiency in a trickle-bed reactor under reaction conditions is introduced. The method exploits reaction rate differences of two first-order liquid-limited reactions occurring in parallel, to infer wetting efficiencies without any other knowledge of the reaction kinetics or external mass transfer characteristics. Using the hydrogenation of linear-and isooctenes, wetting efficiency is measured in a 50-mm internal diameter, high-pressure trickle-bed reactor. Liquidsolid mass transfer coefficients are also estimated from the experimental conversion data. Measurements were performed for upflow operation and two literature-defined boundaries of hydrodynamic multiplicity in trickle flow. Hydrodynamic multiplicity in trickle flow gave rise to as much as 10% variation in wetting efficiency, and 10-20% variation in the specific liquid-solid mass transfer coefficient. Conversions for upflow operation were significantly higher in trickle-flow operation, because of complete wetting and better liquid-solid mass transfer characteristics.

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Section: Resultsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Parallel hydrogenation for the quantification of wetting efficiency and liquid–solid mass transfer in a trickle‐bed reactor

Houwelingen

Nicol

2011

AIChE Journal

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“…15 Information about liquid-solid mass transfer (LSMT) is scarce, and only the limited study by Sims et al 16 reports a hysteresis loop on liquid-solid mass transfer using an unconventional packing. The results from Sims et al 16 are in direct conflict with the suggestion by Van der Merwe et al 7 that LSMT in the Levec prewetting mode might exceed that of the Kan liquid mode owing to the higher average interstitial velocity in the Levec bed.…”

Section: Introductionmentioning

confidence: 83%

Multiplicity Behavior of Trickle Flow Liquid−Solid Mass Transfer

Joubert

Nicol

2009

Ind. Eng. Chem. Res.

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Dissolution as well as electrochemical techniques confirmed the existence of multiplicity. The commonly accepted upper multiplicity branch (achieved by Kan liquid prewetting) outperformed the lower branch (achieved by Levec prewetting) by as much as 1.6 times in Sherwood numbers. Although similar trends were observed for the two measurement techniques, the dissolution measurements were significantly lower than the electrochemical measurements. It was further shown that the multiplicity behavior of liquid-solid mass transfer is not linked solely to liquid hold-up and wetting efficiency variations, indicating major differences in flow structures between the multiplicity modes employed. In addition, a decrease in Sherwood numbers with bed depth was observed for both multiplicity modes.

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“…8 In another study, the analysis of TBR hydrodynamics was conducted under gas-and liquidlimited reactions, for α-methylstyrene hydrogenation reaction system. 9 The fluctuations in the liquid flow rate had a great effect on the reaction conversion. Moreover, in the liquidlimited and gas-limited reactions, the liquid−solid and gas− liquid mass transfer rates were the limiting step, respectively.…”

Section: Introductionmentioning

confidence: 99%

Dynamic Modeling Strategy To Assess Impacts of Hydrodynamic Parameters on Industrial Hydropurification Process by Considering Catalyst Deactivation

Azarpour

Rezaei

Zendehboudi

2018

Ind. Eng. Chem. Res.

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In this study, modeling and simulation of the dynamic behavior of an industrial-scale trickle bed reactor (TBR) with application to a hydropurification process for production of purified terephthalic acid (PTA) are carried out. The impacts of hydrodynamic parameters such as reactor bed porosity, liquid hourly space velocity (LHSV), and liquid–solid and gas–liquid mass transfer coefficients on the industrial hydropurification TBR performance (in particular, on the catalyst lifetime) are analyzed. As the palladium supported on carbon (Pd/C) catalyst deactivates with time, the concentration of impurities in the product, especially 4-carboxybenzaldehyde (4-CBA) as the main impurity of PTA, increases. The three-phase dynamic mathematical model developed in this research work is validated against the plant data, and an average relative error of 2.2% is obtained for the concentration of 4-CBA. The lifetime of the catalyst based on plant data is 348.2 ± 5.0 days; this value is estimated to be 365.1 days from the simulation results, showing a 4.8% error. According to the sensitivity analysis on the model parameters, the effects of LHSV and bed porosity are in the same direction and magnitude, while the effects of the liquid–solid and gas–liquid mass transfer coefficients are in the opposite direction, and their impacts are also less significant. These parameters are disturbed in a range of up to ±15%, compared to the normal operating conditions that results in an absolute catalyst lifetime change of 2.9%–14.2%. The maximum and minimum variations in the catalyst lifetime are obtained when LHSV is disturbed by ±10%, exhibiting a catalyst lifetime change of 14.2% at a −10% disturbance (416.9 days) and −6.5% at a +10% disturbance (341.3 days). A +15% disturbance in the liquid–solid mass transfer coefficient increases the catalyst lifetime by 2.9% (375.8 days), and a −15% disturbance decreases this vital parameter by 3.7% (351.8 days). Eventually, the findings of this study might be applied to the relevant industrial sectors, providing the required close and meticulous control of the process.

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Effect of hydrodynamic multiplicity on trickle bed reactor performance

Cited by 9 publications

References 30 publications

Parallel hydrogenation for the quantification of wetting efficiency and liquid–solid mass transfer in a trickle‐bed reactor

Parallel hydrogenation for the quantification of wetting efficiency and liquid–solid mass transfer in a trickle‐bed reactor

Multiplicity Behavior of Trickle Flow Liquid−Solid Mass Transfer

Dynamic Modeling Strategy To Assess Impacts of Hydrodynamic Parameters on Industrial Hydropurification Process by Considering Catalyst Deactivation

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