Promotion of heat, mass transfer and energy utilization efficiency in a stirred tank reactor by closely spaced turbulence promoters

ABSTRACT

The present study attempts to obviate the drawbacks of the stirred slurry catalytic reactor by using the wall of a square stirred tank reactor as catalyst support where a diffusion-controlled reaction occurs. The electrochemical technique was used to measure the rate of mass and heat transfer (by analogy) at the reactor wall which was fitted with closely-spaced semicylindrical turbulence promoters. The effect of various geometrical and hydrodynamic parameters on the mass transfer coefficient was quantified by dimensionless correlations. The promoters increased the wall mass transfer coefficients up to 80% and the volumetric mass transfer coefficients by an amount varying from 57 to 190% depending on the working conditions. Power consumption measurements reported that the turbulence promoters enhanced the reactormechanical energy utilization up to 303% depending on the working conditions. The additional roles of turbulence promoters in increasing the reaction surface area and cooling the reactor where exothermic diffusion-limited reactions may occur were indicated. Merits of the present reactor over the stirred slurry biochemical reactor such as protecting the catalyst against shear and thermal degradation were highlighted.

KEYWORDS:

• energy efficiency
• heat transfer
• mass transfer
• stirred tank reactors
• turbulence promoters
• immobilized enzyme

Symbols used

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Disclosure statement

No potential conflict of interest was reported by the author(s).