Chemical Processing - April 2008 - (Page 31)

>> Test rig Figure 2. High shear in-line test rig at Cranfield includes transducers for torque and differential pressure. Source: British Hydromechanics Research Group. attention to the subject — namely the University of Maryland, College Park, Md., with its High Shear Mixing Research Program, and the British Hydromechanics Research Group at Cranfield University, Cranfield, U.K. (Figure 2). Because this research has been carried out by consortia that includes equipment manufacturers, much of the data remain within their control. Again, results from these studies are being utilized to streamline development processes and as an aid to scale-up but little of the research has found its way into the public domain. To some extent this is understandable because the market for high shear mixing equipment is relatively small and highly competitive. The ability to accurately scale-up when specifying mixing equipment for a given application is one of the suppliers’ competitive advantages; the application of new techniques in combination with many years of research and development is a vital part of this advantage. Scale-up calculations Where scale-up is concerned, different manufacturers cite certain criteria as the basis for calculations but, as we’ve noted, the complexity of devices such as rotor/stator mixers makes it more realistic to combine a number of these factors. With the benefit of practical experience, the right combination can give an accurate scale-up recommendation. Traditionally geometric similarity and tank turnover/throughput formed the basis for many calculations. In light of recent research, additional parameters generally considered to provide reliable results include energy dissipation (that is, power per unit volume or power draw), rotor tip speed and shear frequency (residence time, also linked to open area or mixer geometry). Energy dissipation. In a situation where vessel and mixer geometry are similar across a range of sizes, energy dissipation is considered to be constant and, therefore, a useful tool in scale-up calculations. Power has to be monitored while mixing to determine the effects of the fluid’s physical properties on power draw. The most reliable way of doing this is to incorporate a torque transducer onto the mixer’s shaft to www.chemicalprocessing.com Readco Kurimoto and Melfi Technologies have combined to make processing a whole lot easier. With Readco’s continuous processing mixers and touch screen control produced by Melfi Technologies, life just became a lot less puzzling. Now you can process anything and change parameters with the touch of a button. This combined technology gives so many advantages over traditional batch mixing: • • • • • • • • • Reduced Cycle Time Combined Processes Reduced Clean-up and Waste Less Labor Batch to Batch Consistency Ease of use No Operator Error Reduced Costs Touch Screen Control Process anything with touch screen control. Actual Screen Shot Call us today to learn more. www.melfitechnologies.com 905-760-9080 800-395-4959 www.readco.com Visit Us at Booth #4405 at the PTXi Show and See A Live Demonstration! http://www.melfitechnologies.com http://www.readco.com http://www.chemicalprocessing.com

Table of Contents Feed for the Digital Edition of Chemical Processing - April 2008

Chemical Processing - April 2008 Contents From the Editor ChemicalProcessing.com Field Notes In Process Energy Saver Compliance Advisor Is It a Tragedy or Comedy for Engineers? Better Understanding Boosts Mixer Scale-up Don't Err With Air Compressors Control Performance Supervision Enhances Revamp Process Puzzler Plant InSites Equipment & Services Product Spotlight/Classifieds Ad Index End Point

Chemical Processing - April 2008

For optimal viewing of this digital publication, please enable JavaScript and then refresh the page. If you would like to try to load the digital publication without using Flash Player detection, please click here.