Hydrodynamics and mass transfer investigations in a biphasic plasma reactor

2021 ◽  
Vol 19 (4) ◽  
pp. 369-381
Author(s):  
Mohammed Fouad Ferhat ◽  
Mouffok Redouane Ghezzar ◽  
Ahmed Addou
Keyword(s):  
Mass Transfer ◽  
Chemical Engineering ◽  
Removal Rate ◽  
Plasma Reactor ◽  
Radical Mechanism ◽  
Spray Tower ◽  
Degradation Rates ◽  
Kinetic Mechanisms ◽  
Low Mass ◽  
Plasma Reactions

Abstract This work aims to investigate the radical mechanism responsible for the degradation of a highly soluble pollutant in water. The AG25 dye was chosen as substrate and the GAD-Spray as biphasic reactor to treat it remotely. The study is conducted through experiments and simulations using Comsol Multiphysics-chemical engineering module. The Hydrodynamics coupled with the plasma-reaction has demonstrated that a low mass transfer in the droplet favorites the removal of the pollutant. It indicates that the plasma-reactions take place at the stagnant liquid film are far from the bulk of the droplet. Numerical modeling fitted by the conversion rate of the reagent has shown that the peroxynitrous acid HOONO (PON) is responsible for the degradation of AG25 in water. Consequently, and according different kinetic mechanisms, a radical mechanism has been predicted based on this deduction. The removal and the degradation rates were of 88 and 83% respectively during 90 min after the plasma exposure. The results of simulations showed a significant agreement between the calculated and the real removal rate of AG25. Through this study, it can be confirmed that GAD-spray-tower plasma reactor is efficient to eliminate and degrade remotely a very soluble pollutant through the HOONO (PON) plasma long-lived species.

Biodegradation rates of aromatic contaminants in biofilm reactors

1995 ◽  
Vol 31 (1) ◽  
pp. 117-128 ◽  
Author(s):  
Jean-Pierre Arcangeli ◽  
Erik Arvin
Keyword(s):  
Aromatic Hydrocarbons ◽  
Competitive Inhibition ◽  
Removal Rate ◽  
First Order ◽  
Biofilm Reactors ◽  
First Order Kinetics ◽  
Reducing Conditions ◽  
Low Concentrations ◽  
Degradation Rates ◽  
Order Surface

This study has shown that microorganisms can adapt to degrade mixtures of aromatic pollutants at relatively high rates in the μg/l concentration range. The biodegradation rates of the following compounds were investigated in biofilm systems: aromatic hydrocarbons, phenol, methylphenols, chlorophenols, nitrophenol, chlorobenzenes and aromatic nitrogen-, sulphur- or oxygen-containing heterocyclic compounds (NSO-compounds). Furthermore, a comparison with degradation rates observed for easily degradable organics is also presented. At concentrations below 20-100 μg/l the degradation of the aromatic compounds was typically controlled by first order kinetics. The first-order surface removal rate constants were surprisingly similar, ranging from 2 to 4 m/d. It appears that NSO-compounds inhibit the degradation of aromatic hydrocarbons, even at very low concentrations of NSO-compounds. Under nitrate-reducing conditions, toluene was easily biodegraded. The xylenes and ethylbenzene were degraded cometabolically if toluene was used as a primary carbon source; their removal was influenced by competitive inhibition with toluene. These interaction phenomena are discussed in this paper and a kinetic model taking into account cometabolism and competitive inhibition is proposed.

Certain problems with the application of stochastic diffusion processes for description of chemical engineering phenomena; Kolmogorov and classic diffusion equations

1988 ◽  
Vol 53 (6) ◽  
pp. 1181-1197
Author(s):  
Vladimír Kudrna
Keyword(s):  
Mass Transfer ◽  
Partial Differential Equations ◽  
Differential Equations ◽  
Chemical Engineering ◽  
Diffusion Processes ◽  
Parabolic Type ◽  
Diffusion Equations ◽  
Stochastic Motion ◽  
Energy Component ◽  
Classic Form

The paper presents alternative forms of partial differential equations of the parabolic type used in chemical engineering for description of heat and mass transfer. It points at the substantial difference between the classic form of the equations, following from the differential balances of mass and enthalpy, and the form following from the concept of stochastic motion of particles of mass or energy component. Examples are presented of the processes that may be described by the latter method. The paper also reviews the cases when the two approaches become identical.

Capillary Equilibrium in Porous Materials

1965 ◽  
Vol 5 (01) ◽  
pp. 15-24 ◽  
Author(s):  
Norman R. Morrow ◽  
Colin C. Harris
Keyword(s):  
Mass Transfer ◽  
Fluid Flow ◽  
Porous Materials ◽  
Capillary Pressure ◽  
Chemical Engineering ◽  
Fluid Distribution ◽  
Bulk Fluid ◽  
Fluid Saturation ◽  
Capillary Pressure Curves ◽  
The Relationship

Abstract The experimental points which describe capillary pressure curves are determined at apparent equilibria which are observed after hydrodynamic flow has ceased. For most systems, the time required to obtain equalization of pressure throughout the discontinuous part of a phase is prohibitive. To permit experimental points to be described as equilibria, a model of capillary behavior is proposed where mass transfer is restricted to bulk fluid flow. Model capillary pressure curves follow if the path described by such points is independent of the rate at which the saturation was changed to attain a capillary pressure point. A modified suction potential technique is used to study cyclic relationships between capillary pressure and moisture content for a porous mass. The time taken to complete an experiment was greatly reduced by using small samples. Introduction Capillary retention of liquid by porous materials has been investigated in the fields of hydrology, soil science, oil reservoir engineering, chemical engineering, soil mechanics, textiles, paper making and building materials. In studies of the immiscible displacement of one fluid by another within a porous bed, drainage columns and suction potential techniques have been used to obtain relationships between pressure deficiency and saturation (Fig. 1). Except where there is no hysteresis of contact angle and the solid is of simple geometry, such as a tube of uniform cross section, there is hysteresis in the relationship between capillary pressure and saturation. The relationship which has received most attention is displacement of fluid from an initially saturated bed (Fig. 1, Curve Ro), the final condition being an irreducible minimum fluid saturation Swr. Imbibition (Fig. 1, Curve A), further desaturation (Fig. 1, Curve R), and intermediate scanning curves have been studied to a lesser but increasing extent. This paper first considers the nature of the experimental points tracing the capillary pressure curves with respect to the modes and rates of mass transfer which are operative during the course of measurement. There are clear indications that the experimental points which describe these curves are obtained at apparent equilibria which are observed when viscous fluid flow has ceased; and any further changes in the fluid distribution are the result of much slower mass transfer processes, such as diffusion. Unless stated otherwise, this discussion applies to a stable packing of equal, smooth, hydrophilic spheres supported by a suction plate with water as the wetting phase and air as the nonwetting phase. SPEJ P. 15ˆ

scholarly journals Effect of Gas-Liquid Contact Intensification on Heat and Mass Transfer in Deflector and Rod Bank Desulfurization Spray Tower

Processes ◽  
2021 ◽  
Vol 9 (8) ◽  
pp. 1269
Author(s):  
Yuzhen Jin ◽  
Weida Zhao ◽  
Zeqing Li
Keyword(s):  
Mass Transfer ◽  
Pressure Drop ◽  
Heat And Mass Transfer ◽  
Temperature Difference ◽  
Flue Gas ◽  
Flue Gas Desulfurization ◽  
Spray Tower ◽  
Porous Media Model ◽  
Desulfurization Efficiency ◽  
Optimization Mechanism

The deflector and the rod bank are commonly used to optimize flue gas distribution in the original spray tower (OST) of a wet flue gas desulfurization system (WFGD). In this paper, the internal optimization mechanism of the deflector desulfurization spray tower (DST) and the rod bank desulfurization spray tower (RBST) are studied. Based on the Euler–Lagrange method, the standard k-ε turbulence model, an SO2 absorption model and a porous media model, the numerical simulation of the desulfurization spray tower is carried out with the verification of the model rationality. The results show that there are gas-liquid contact intensification effects in DST and RBST. Compared with OST, gas-liquid contact intensification enhances the heat and mass transfer effects of DST and RBST. The temperature difference between inlet and outlet of flue gas increased by 3.3 K and the desulfurization efficiency of DST increased by 1.8%; the pressure drop decreased by 37 Pa. In RBST, the temperature difference between the flue gas inlet and outlet increased by 5.3 K and the desulfurization efficiency increased by 3.6%; the pressure drop increased by 33 Pa.

scholarly journals Overall Mass Transfer Coefficient of CO2 Absorption in a Diameter-varying Spray Tower

2017 ◽  
Vol 114 ◽  
pp. 1665-1670 ◽  
Author(s):  
Xiaomei Wu ◽  
Min He ◽  
Yunsong Yu ◽  
Zhen Qin ◽  
Zaoxiao Zhang
Keyword(s):  
Mass Transfer ◽  
Transfer Coefficient ◽  
Mass Transfer Coefficient ◽  
Co2 Absorption ◽  
Spray Tower ◽  
Overall Mass Transfer Coefficient

scholarly journals Circulating Jet for Enhancing the Mass Transfer in a Gas-liquid Stirred Tank Reactor

2021 ◽  
Author(s):  
Lei Wang ◽  
Xiao Xu ◽  
Hualin Wang ◽  
HongLai Liu ◽  
Qiang Yang
Keyword(s):  
Mass Transfer ◽  
Scale Up ◽  
Input Power ◽  
Stirred Tank ◽  
Exhaust Gas ◽  
Stirred Tank Reactor ◽  
Tank Reactor ◽  
Mass Transfer Efficiency ◽  
Low Mass ◽  
Liquid Mass Transfer

A gas-liquid stirred tank reactor (STR) has some problems, such as low mass transfer efficiency, high exhaust gas oxygen concentration, and low product conversion rate, due to limitations of stirring speed and input power. This article proposes a method to enhance the gas-liquid mass transfer in a STR using circulating jet internals. When a circulating jet is added, the average bubble size in the reactor is reduced to 1.26 mm, and the overall gas holdup is increased to 8.23%, which is an increase of 3.62 times of the original STR. The gas-liquid volumetric mass transfer coefficient is increased to 0.05556 s-1, which is 4.84 times of the original STR. The unit volume power is increased by only 1.4 times. These data provide references for the design and scale-up of new jet STRs.

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