Reactor Performance and Scale-Up

Ranade, Vivek V.; Chaudhari, Raghunath V.; Gunjal, Prashant R.

doi:10.1016/b978-0-444-52738-7.10005-1

Cited by 4 publications

(6 citation statements)

References 66 publications

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“…Hydrogen or oxygen need to penetrate through the liquid film, diffuse, and be adsorbed onto the active sites on the solid phase to participate in the reaction . Consequently, the liquid film thickness, surface renewal rate, and other relevant hydrodynamic parameters are crucial factors for the above process . The liquid superficial mass velocity in the TBRs is relatively slow (0.01–2 kg/(m 2 ·s)) to ensure adequate conversion of reactants; therefore, the wetting efficiency is insufficient and the intraparticle diffusion rate in the TBR is comparatively slow .…”

Section: Introductionmentioning

confidence: 84%

Liquid holdup and wetting efficiency in a rotating trickle‐bed reactor

et al. 2019

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Section: Introductionmentioning

confidence: 84%

Liquid holdup and wetting efficiency in a rotating trickle‐bed reactor

et al. 2019

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“…7,10,34 These dimensionless numbers or groups of variables form the basis for scaling up from one size to another. 11,23,35 Two different methods can be followed in the context of the physical approach: 16,32 (i) similarity criteria, which include (a) geometrical, (b) mechanical, (c) thermal, and (d) chemical similarities, 23,34 and (ii) dimensional analysis, which includes (a) Buckingham π-theorem based method and (b) inspectional analysis that uses a dimensionless form of the governing equations. 7,11,35 The second is the experimental approach, in which designer knowledge about a particular process is used for carrying out its scaleup.…”

Section: Scaleup Of Batch Processesmentioning

confidence: 99%

“…It is possible to distinguish three basic approaches in the scaleup procedure. ,,,, The first is known as the physical approach. This approach involves the use of dimensionless numbers, variables, and relationships to relate the same process at different scales. ,, These dimensionless numbers or groups of variables form the basis for scaling up from one size to another. ,, Two different methods can be followed in the context of the physical approach: , (i) similarity criteria, which include (a) geometrical, (b) mechanical, (c) thermal, and (d) chemical similarities, , and (ii) dimensional analysis, which includes (a) Buckingham π-theorem based method and (b) inspectional analysis that uses a dimensionless form of the governing equations. ,, …”

Section: Scaleup Of Batch Processesmentioning

confidence: 99%

“…9−14 Industrial scaleup is dominated by empirical scaleup rules, requiring geometrical similarity with criteria such as equal tip speed or equal mass-transfer coefficients, leading to drawbacks from keeping a single parameter constant. 5,12,15,16 Here, given that some parameters are fixed, the rest could change substantially in unforeseen ways, 8,17 resulting in an erroneous commercial unit design requiring additional costs and time to be corrected. 9,18 Although there is no particular literature on the scaleup of BPs, the same methods are used for both batch and continuous processes.…”

Section: Introductionmentioning

confidence: 99%

“…Neither particular nor generalizable progress has been reported in the field of the scaleup of chemical processes. Such processes are still scaled up using traditional methods that have not changed significantly since the 1960s. − Industrial scaleup is dominated by empirical scaleup rules, requiring geometrical similarity with criteria such as equal tip speed or equal mass-transfer coefficients, leading to drawbacks from keeping a single parameter constant. ,,, Here, given that some parameters are fixed, the rest could change substantially in unforeseen ways, , resulting in an erroneous commercial unit design requiring additional costs and time to be corrected. , …”

Section: Introductionmentioning

confidence: 99%

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Scaleup of Batch Reactors Using Phenomenological-Based Models

Monsalve-Bravo

Moscoso-Vasquez

Álvarez

2014

Ind. Eng. Chem. Res.

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This work presents a methodology for scaling up batch processes (BPs). First, the most popular scaleup methods differentiating batch from continuous processing are reviewed, revealing that traditional scaleup approaches do not consider BP characteristics and that many particular successful cases are reported, but no formal procedure has been developed for scaling up these processes. Considering these facts, a novel scaleup procedure is presented, in which a process phenomenological-based semiphysical model (PBSM) and its Hankel matrix are used for computing the state impactability index (SII) that allow the designer to determine (i) the main process dynamics at each stage of the batch and (ii) the critical point of the operating trajectory (OT) at which the batch must be scaled up. Finally, the methodology is applied to a batch suspension polymerization reactor, comparing the scaled unit design using this approximation and a traditional method.

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Two-Phase Flow Countercurrent Operation of a Trickle Bed Reactor: Hold-up and Mixing Behavior over Raschig Rings Fixed Bed and Structured Bale Packing

Safinski

Adesina

2011

Ind. Eng. Chem. Res.

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The hydrodynamics of countercurrent gas and liquid flows through a trickle bed reactor with unstructured (8 mm Raschig rings) and structured (Bale) packing has been investigated using the residence time distribution (RTD) approach. The operation was carried out with gas and liquid Reynolds number over the range 0 < Re G < 150 and 0 < Re L < 1500, respectively. Gas phase Peclet number, Pe G , was generally higher in the randomly packed Raschig rings than in the structured Bale packing but increased with Re G . However, gas phase mixing decreased with increasing liquid flow rate. Specifically, the dependency on Re G and Re L was given by,The gas phase hold-up, H 0G also increased with gas flow rate but decreased with the liquid flow rate. Owing to the statistical nature of the gas flow through beds, a Snedecor F-distribution was used to describe the gas phase RTD data and hence, the dynamics of the macroscopic flow pattern within the bed was determined from the intensity function, I(t). This indicated initial gas recirculation in stagnant zones within the bed with the flow pattern subsequently evolving into predominantly a channelling and bypassing type. Interestingly, the liquid phase mixing behavior appeared to be independent of Re G and thus, Pe L,Raschig = A L Re L b L for the unstructured bed, but flow through the more open Bale packing revealed two types of mixing regimes, with a crossover from the region of decreasing Pe L to increasing Pe L with an increased liquid flow rate at Re L of about 750 and accordingly, Pe L,Bale = A 0 + A 1 Re L A 2 Re L 2 . Liquid hold-up, H 0L , could be decoupled into a static component, H SL , and dynamic contribution, H DL , with the latter being proportional to the liquid flow rate. The Bale packing has a higher static hold-up (0.225) than the randomly packed Raschig rings (0.100) due to its more open structure. On the whole, it seemed that liquid phase back-mixing was generally lower in the unstructured packed bed than in the structured Bale packing. The associated higher static hold-up and reduced sensitivity with increasing liquid flow rate makes the latter the preferred choice for catalytic distillation for operations bounded by the loading and flooding envelopes.

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Reactor Performance and Scale-Up

Cited by 4 publications

References 66 publications

Liquid holdup and wetting efficiency in a rotating trickle‐bed reactor

Liquid holdup and wetting efficiency in a rotating trickle‐bed reactor

Scaleup of Batch Reactors Using Phenomenological-Based Models

Two-Phase Flow Countercurrent Operation of a Trickle Bed Reactor: Hold-up and Mixing Behavior over Raschig Rings Fixed Bed and Structured Bale Packing

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