Structured Packing PerformanceExperimental Evaluation of Two Predictive Models

Fair, James R.; Seibert, A. Frank; Behrens, M.; Saraber, and P. P.; Olujić, Žarko

doi:10.1021/ie990910t

Cited by 108 publications

(75 citation statements)

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“…Freguia and Rochelle [4] analyzed the sensitivity of process variables in a system consisting of a packed absorber, a stripper and a cross heat exchanger, with the aim to find operating conditions at low energy consumption based on a RateFrac absorber model. Current absorption processes usually involve absorption towers and packed or plate columns [22][23][24][25], which have huge volumes and relatively low efficiencies in mass transfer. Hence, there is a need to develop new technologies that can miniaturize reaction and unit operation elements and integrate these process devices in order to save space and energy.…”

Section: Introductionmentioning

confidence: 99%

Process Characteristics of CO2 Absorption by Aqueous Monoethanolamine in a Microchannel Reactor

Chen

Yuan

2012

Chinese Journal of Chemical Engineering

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Process characteristics of CO 2 absorption using aqueous monoethanolamine (MEA) in a microchannel reactor were investigated experimentally in this work. A T-type rectangular microchannel with a hydraulic diameter of 408 μm was used. Operating parameters, i.e. temperature, pressure and molar ratio of MEA to CO 2 were studied. Under 3 MPa pressure, the mole fraction of CO 2 in gas phase could decrease from 32.3% to 300×10 −6 at least when gas hourly space velocity ranged from 14400 to 68600 h −1 and molar ratio of MEA to CO 2 was kept at 2.2. In particular, the effects of temperature on CO 2 absorption flux, mass transfer driving force, gas-liquid contact time and enhancement factor were analyzed in detail and found that mass transfer enhancement by chemical reaction was a crucial factor for the process of CO 2 absorption.

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Section: Introductionmentioning

confidence: 99%

Process Characteristics of CO2 Absorption by Aqueous Monoethanolamine in a Microchannel Reactor

Chen

Yuan

2012

Chinese Journal of Chemical Engineering

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“…In our case, using the correlations to estimate pressure drop in QVF column, the result is underestimated, which can be a source of error in the liquid holdup evaluation of Rocha, Bravo and Fair's model (1993). Also, Fair et al (2000) suggest a pressure drop of 10.25mbar/m of packing, in flooding conditions, but QVF column is already flooding at 6mbar/m of pressure. Therefore, instead of using the values obtained from the models, the experimental conditions shown in Table 7 were used in Rocha, Bravo and Fair's model (1993) for liquid holdup calculation.…”

Section: Resultsmentioning

confidence: 90%

HETP evaluation of structured packing distillation column

Orlando

Medina

Mendes

et al. 2009

Braz. J. Chem. Eng.

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-Several tests with a hydrocarbon mixture of known composition (C 8 -C 14 ), obtained from DETEN Chemistry S.A., have been performed in a laboratory distillation column, having 40mm of nominal diameter and 2.2m high, with internals of Sulzer DX gauze stainless steel structured packing. The main purpose of this work was to evaluate HETP of a structured packing laboratory scale distillation column, operating continuously. Six HETP correlations available in the literature were compared in order to find out which is the most appropriate for structured packing columns working with medium distillates. Prior to the experimental tests, simulation studies using commercial software PRO/II ® were performed in order to establish the optimum operational conditions for the distillation, especially concerning operating pressure, top and bottom temperatures, feed location and reflux ratio. The results of PRO/II ® were very similar to the analysis of the products obtained during continuous operation, therefore permitting the use of the properties calculated by that software on the theoretical models investigated. The theoretical models chosen for HETP evaluation were: Bravo, Rocha and Fair (1985); Fair (1993, 1996); Brunazzi and Pagliant (1997); Carlo, Olujić and Pagliant (2006); Olujić et al., (2004). Modifications concerning calculation of specific areas were performed on the correlations in order to fit them for gauze packing HETP evaluation. As the laboratory distillation column was operated continuously, different HETP values were found by the models investigated for each section of the column. The low liquid flow rates in the top section of the column are a source of error for HETP evaluation by the models; therefore, more reliable HETP values were found in the bottom section, in which liquid flow rates were much greater. Among the theoretical models, Olujić et al. (2004) has shown good results relative to the experimental tests. In addition, the former model by Bravo, Rocha and Fair (1985) underestimates HETP values; however, with the modifications proposed in this work, it has achieved more realistic performance prediction, remaining a good choice for gauze packing HETP evaluation. Having the advantage of avoiding the calculation of effective area and mass transfer coefficients, an empirical model proposed by Carrillo and coworkers (2000) was also investigated, showing low deviations compared to the theoretical models tested.

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“…At the inlet, the velocity is set to u x = u y = 0, u z = u in , and for the standard k-e equations, k = 0.003 u in 2 [24] and e = 0.1643 k 1.5 /d eq , where d eq is the hydraulic diameter of the liquid phase, estimated as d eq = 0.4 d [25]. The mixing behavior was estimated by simulating the tracer injection process experiment.…”

Section: Initial and Inlet Conditionsmentioning

confidence: 99%

Prediction of Axial Mixing for a Structured Packed Column Using a Two‐equation Model

et al. 2008

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A theoretical model based on the recently developed c 2 À e c two-equation method is proposed to predict the axial mixing behavior in a structured packed column. By solving the proposed model, the process of tracer injection experiments for determining the axial back-mixing coefficient of structured packing can be simulated. Consequently, the axial Bodenstein number and dispersion coefficient under liquid single-phase or gas-liquid two-phase flow conditions can be calculated. The validation of the proposed method is tested by simulating the twophase fluid flow behavior in Flexipac 2 structured packing. The simulated results are compared with the experimental data and satisfactory agreement is found between the simulation and the experiments. IntroductionAxial mixing, or axial dispersion, is an important nonideal flow behavior occurring in packed beds [1]. With regard to experimental investigations of axial mixing behavior in packed beds, much effort has been focused on random packing and only a few studies have been devoted to structured packing. Among them, the work of Mak et al. [2] is an early reported study of structured packing columns. The authors measured the axial dispersion coefficient of single-phase flow in a pulsed packed column. Ricardo et al. [1,3] investigated the axial mixing behavior in a large scale packed column for four different packings under single and two-phase flow conditions.The axial mixing behavior in a structured packed column is usually measured by tracer injection experiments [1][2][3][4][5]. Since this kind of experiment is usually known to be expensive and laborious, and can only be performed in laboratories, the use of virtual experiments involving a computational fluid dynamics (CFD) method is a good alternative.During recent decades, many theoretical research works have been undertaken on structured packing using computational fluid dynamics (CFD) techniques [6][7][8][9][10][11][12][13]. However, most of them were devoted to the computation of velocity distribution and pressure drop. In order to simulate the hydrodynamics of liquid-phase flow in structured packing filled with catalyst pellets, Gulijk [10] presented a Toblerone model, which simplified the problem of multiphase flow to a single phase in the channels, and facilitated the calculation of the transversal dispersion in the structured packing using the CFX code. Krishna et al. [11][12][13] carried out a series of experimental and theoretical studies to investigate the flow and mass transfer behavior within a KATAPAK-S structured packing containing a catalyst. In their work, the liquid-phase residence time distribution [11], radial and axial dispersion [12], gas and liquid-phase mass transfer [13] were investigated by the CFD method. A similar numerical study was also reported by Chen [14]. However, the simulated dispersion coefficients in these works were considerably underestimated in comparison to the experimental values. This is mainly due to the lack of proper theoretical models to describe the tracer transport pr...

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Structured Packing PerformanceExperimental Evaluation of Two Predictive Models

Cited by 108 publications

References 10 publications

Process Characteristics of CO2 Absorption by Aqueous Monoethanolamine in a Microchannel Reactor

Process Characteristics of CO2 Absorption by Aqueous Monoethanolamine in a Microchannel Reactor

HETP evaluation of structured packing distillation column

Prediction of Axial Mixing for a Structured Packed Column Using a Two‐equation Model

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