Correction to: Influence of Orifice Position Deviations on Distribution Performance of Gravity-Type Liquid Distributor Analyzed Through Mathematical Pathway

The spatial variations of liquid distribution and local mass transfer coefficient in a 0.30-m column of 25.4-m Pall rings were investigated. The data of liquid distribution was collected with a 39-cell liquid collector and a wall-flow tube from a doubled-wall section in the column at the packing-support level. The local mass transfer coefficients were measured via the electrochemical technique by individual cathodic nickel-coated Pall rings placed at various spatial positions. Both measurements were conducted at various fluid flow rates with three liquid distributor designs at different bed heights. Liquid distribution and local mass transfer coefficients observed were far from uniform in the column. The wall flow developed along the packed bed until a fully developed flow pattern was reached. With more uniform initial liquid distribution, the less packing height needed to reach the fully developed flow pattern along with higher the mass transfer efficiency in the column. Ladder-type liquid distributor (LLD) showed less angular effect in measurements. Increasing the liquid flow rate slightly improved the uniformity of liquid distribution and enhanced the mass transfer. No influence of gas flow rate on liquid distribution and mass transfer coefficient was found at the range of gas flow rates used. These gas flow rates were much lower than the loading point. Liquid maldistribution factor and mass transfer maldistribution factor decreased with increases in the uniformity of the initial liquid distribution. These values were 0.21(0.48). 0.16(0.26) and 0.14(0.22) for single-point liquid distributor (SPLD), cross-type liquid distributor (CLD) and LLD, respectively. By comparison, a good agreement was observed on the relation of liquid maldistribution factor and mass transfer maldistribution factor.

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Liquid distribution and its effect on local mass transfer in a packed column of Pall rings

10.32920/ryerson.14645031.v1 ◽

2021 ◽

Author(s):

Yongjia Zhu

Keyword(s):

Mass Transfer ◽

Gas Flow ◽

Transfer Coefficients ◽

Liquid Distribution ◽

Fully Developed Flow ◽

Flow Rates ◽

Local Mass ◽

Local Mass Transfer ◽

Liquid Distributor ◽

Wall Flow

The spatial variations of liquid distribution and local mass transfer coefficient in a 0.30-m column of 25.4-m Pall rings were investigated. The data of liquid distribution was collected with a 39-cell liquid collector and a wall-flow tube from a doubled-wall section in the column at the packing-support level. The local mass transfer coefficients were measured via the electrochemical technique by individual cathodic nickel-coated Pall rings placed at various spatial positions. Both measurements were conducted at various fluid flow rates with three liquid distributor designs at different bed heights. Liquid distribution and local mass transfer coefficients observed were far from uniform in the column. The wall flow developed along the packed bed until a fully developed flow pattern was reached. With more uniform initial liquid distribution, the less packing height needed to reach the fully developed flow pattern along with higher the mass transfer efficiency in the column. Ladder-type liquid distributor (LLD) showed less angular effect in measurements. Increasing the liquid flow rate slightly improved the uniformity of liquid distribution and enhanced the mass transfer. No influence of gas flow rate on liquid distribution and mass transfer coefficient was found at the range of gas flow rates used. These gas flow rates were much lower than the loading point. Liquid maldistribution factor and mass transfer maldistribution factor decreased with increases in the uniformity of the initial liquid distribution. These values were 0.21(0.48). 0.16(0.26) and 0.14(0.22) for single-point liquid distributor (SPLD), cross-type liquid distributor (CLD) and LLD, respectively. By comparison, a good agreement was observed on the relation of liquid maldistribution factor and mass transfer maldistribution factor.

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A Closed-Loop Optimized System with CFD Data for Liquid Maldistribution Model

Processes ◽

10.3390/pr8111332 ◽

2020 ◽

Vol 8 (11) ◽

pp. 1332

Author(s):

Wei Zhang ◽

Liyi Li ◽

Baoping Zhang ◽

Xin Xu ◽

Jian Zhai ◽

...

Keyword(s):

Closed Loop ◽

Cfd Simulation ◽

Fluid Dynamic ◽

Structural Parameters ◽

Computational Cost ◽

Pso Algorithm ◽

Oil Refining ◽

Support Vector ◽

Cfd Validation ◽

Liquid Distributor

For the simulation of a trickle-bed reactor (TBR) in coal and oil refining, modeling the liquid maldistribution of the gas-liquid distributor incurs enormous pre-processing work and bears a huge computational cost. A closed-loop optimized system with computational fluid dynamic (CFD) data is therefore proposed for the first time in this paper. A fast prediction model based on support vector regression (SVR) is developed to simplify the modeling of the liquid flow rate in TBRs. The model uses CFD simulation results to determine an optimized set of structural parameters for the gas-liquid distributor in TBRs. In order to obtain an accurate SVR model quickly, the particle swarm optimization (PSO) algorithm is employed to optimize the SVR parameters. Then, the structural parameters corresponding to the minimum liquid maldistribution factor are calculated using the response surface methodology (RSM) based on the hybrid PSO-SVR model. The CFD validation results show a good agreement with the values predicted by RSM, with liquid maldistribution factors of 0.159 and 0.162, respectively.

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