Mass Transfer Performance in Karr Reciprocating Plate Extraction Columns

Abstract

A study of the hydrodynamic and mass transfer performance for Karr reciprocating plate extraction columns has been presented for a range of operating conditions and column diameters of 50, 100, and 450 mm. Although the use of Karr columns has been widespread for many years for a range of important applications, the need for more reliable methods for predicting the performance and scale-up of such columns continues to be a matter of significant importance. The present study has examined the hydrodynamic performance in terms of the dispersed phase hold up and droplet size distribution and mass transfer performance which has incorporated the effects of backmixing in the continuous phase. Work was initially carried out in a 50 mm diameter laboratory scale Karr column using the system 10 v/v% tributyl phosphate/kerosene (continuous)-phenol-water (dispersed) where hydrodynamic and mass transfer performance was analyzed for both directions of mass transfer. Using these data, models were investigated and developed to predict performance over a range of operating conditions. An alternative system consisting of an organic solvent (continuous)-phenolic alkaloid-aqueous caustic (dispersed) was also studied, using both 100 and 450 mm diameter Karr columns. These data were used to validate the hydrodynamic and mass transfer performance models developed for the phenol system in the 50 mm diameter column. Dispersed phase holdup data were found to fit the correlation presented by Kumar and Hartland [Ind. Eng. Chem. Res. 1995, 34, 3925-3940], and the drop size distribution also agreed with the relationship presented by Kumar and Hartland [Ind. Eng. Chem. Res. 1996, 35, 2682-2695 within reasonable accuracy. The mass transfer performance results indicated that the continuous phase controlled the mass transfer rate, and thus, column design was simplified by assuming that the overall mass transfer coefficient can be obtained using a standard mass transfer correlation for the continuous phase. The current mass transfer results were found to be best predicted by a refitted form of the overall mass transfer coefficient correlation developed by Harikrishnan et al. [Chem.

Phenol recovery with tributyl phosphate in a hollow fiber membrane contactor: Experimental and model analysis

“…The use of tributyl phosphate (TBP) as an extractant is the focus of the present work. Compared to other solvents, TBP shows good extraction performance, has low solubility in water, a high flash point which lowers the flammability potential and is relatively inexpensive [5,6]. Phenol forms a complex with TBP as a solvating reagent as follows [6]:…”

Improved gas holdup in novel bubble column

“…Although both oscillatory techniques achieve the same objective of creating an oscillatory velocity vector between the plates and the phases, the latter involves accelerating and decelerating the entire liquid mass, which could result in larger pressure fluctuations and energy demand (Gomaa et al, 1991; Gomaa and Al Taweel, 2005). The latter has been widely studied using the pulsed perforated plate column, while the alternative, RPC has also received much attention (Stella et al, 2008) since its development by Karr (1959).…”

“…Though the studies on RPC and its application are quite abundant as a gas–liquid contactor (Veljkovic and Skala, 1986; Yang et al, 1986a,b; Baird and Rama Rao, 1988, 1998; Rama Rao and Baird, 1988; Skala and Veljkovic, 1988; Veljkovic and Skala, 1988; Sundaresan and Varma, 1990a,b; Gomaa et al, 1991; Lounes and Thibault, 1993, 1996; Harikrishnan et al, 1994; Gagnon et al, 1998; Verma, 2002; Rama Rao and Baird, 2003; Gomaa and Al Taweel, 2005; Stella et al, 2006, 2008), there has been a greater interest in studying the effects of rotary and reciprocatary flow dynamics in gas–liquid mass transfer.…”

Distribuição Do Diâmetro Médio Das Gotas Em Uma Coluna De Extração Pulsada Com Recheio

“…O diagrama esquemático e as propriedades físicas do sistema líquido estudado são mostrados na Figura 1 e na Tabela 1, respectivamente. Para a determinação do diâmetro médio das gotas, foi utilizado o método fotográfico e quantificado com o auxílio de um software de processamento de imagens, conforme a metodologia proposta por Stella et al (2008). As gotas foram fotografadas no intervalo de 10 em 10 minutos, variando-se as vazões das fases (0,25 -1,8 L/h para a fase dispersa e 0,6 -3,1 L/h para a fase contínua) e a frequência de pulsação (1,0 -2,6 Hz).…”