Gas Absorption in Slurries Containing Fine Particles:  Review of Models and Recent Advances

Abstract

Gas absorption in slurries that contain fine particles is frequently encountered in a variety of situations in the chemical industry. Research on the modeling of these systems was first started almost 40 years ago by Professor Sharma's group and the pioneering first paper in the field originated from the Bombay UDCT. The enhancement in gas absorption was shown when the particle size is smaller than the film thickness for mass transfer. Many developments have occurred in this field since then, both on the modeling of such systems and application of the concept of the “micro-phase” enhancement to practical systems. It is the objective of this paper to take stock of these developments and provide a review on the modeling of these systems. The systems are classified into three main categories: (i) reacting particles, (ii) adsorbing particles, and (iii) catalytic particles. The modeling aspects of each class is discussed in detail and critically evaluated. Systems where the products form as a microphase are also discussed briefly.

Gas–liquid mass transfer enhancement by catalyst particles, a modelling study

“…In these publications a number of modeling approaches have been followed to describe the enhancement of gas absorption. Ramachandran (2007) gives an overview of the various methodologies applied. All of these models, in one way or another, describe the enhancement of the absorption by concentration depletion within the film layer.…”

“…It is known that the rate of gas-liquid mass transfer can be significantly influenced by the presence of small particles in the liquid, either being gas-absorbing or reactive particles (Ramachandran, 2007;Ruthiya et al, 2004;Wimmers et al, 1984Wimmers et al, , 1988Wimmers and Fortuin, 1988b;Holstvoogd et al, 1988;Holstvoogd and Van Swaaij, 1990). The presence of the small particles near the gas-liquid interface can increase the liquid side concentration gradient of the transferred component, thereby increasing the mass transfer rate.…”

“…The enhancement of mass transfer due to the presence of catalyst particles near the gasliquid surface has been investigated in a couple of earlier papers, see e.g. Ruthiya et al (2004Ruthiya et al ( , 2005, Ramachandran (2007). Especially Ramachandran (2007) presents a thorough review on the modelling approaches followed.…”

“…Ruthiya et al (2004Ruthiya et al ( , 2005, Ramachandran (2007). Especially Ramachandran (2007) presents a thorough review on the modelling approaches followed. Typically a continuum approach is adopted where the steady state diffusion-reaction equation is solved.…”

Three−Phase Mass Transfer: Application of the Pseudo−Homogeneous and Heterogeneous Models

“…Recently Ramachandran [1], Kaur et al [2] as well as Dumont and Delmas [3] survey the gas absorption in presence of dispersed phase. Ramachadran focuses his survey to show the effect of solid, reacted or catalytic particles on the absorption rate applying different physical models taken from the literature mostly utilizing the shuttle mechanism [3][4][5][6][7][8][9][10] to describe the effects of particles on the mass transfer enhancement.…”