Turbulent flow in a stirred tank with permeable impeller blades

This paper presents results from the experimental investigation of single-phase flow in a prototype stirred tank reactor, which uses monolith catalyst blocks as impeller. These monolith catalyst supports have been used for a dual role: (i) as stirrer blades for agitation and (ii) to bring reactants in contact with the catalyst in a way that eliminates the need for product filtration. The reactors are under investigation as replacement for the standard slurry stirred tank reactors used in the catalytic processes in chemical industry. The flow field in the reactor with this novel impeller, was determined using LDA. Mean and fluctuating velocity data were measured for different monolith blocks and impeller speeds. Results show the normalized flow in the bulk of the tank to be independent of impeller speed and monolith type. Flow velocities through the monolith channels, which are crucial to bring the reactants in contact with the catalyst impregnated in the monolith walls, were measured with LDA. These velocities were found to be of the order of 30-70% of the impeller tip velocity, dependent on the impeller speed and monolith type.