Impellers Bulletin - Chemineer - #1

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^Chemineer Bulletin 713 HE-3 High-Efficiency Impeller The Chemineer High-Efficiency (HE-3) Impeller provides ail of the benefits of more efficient agitation with very tew design limitations. Improved agitation efficiency and greater process flexibility are now available with a practical. fabricated impeller. What is high-efficiency agitation? In an engineering sensé, high-efficiency agitation means that the same process results are achieved with reduced me-chanical or energy requirements. On the business side, high-efficiency agitation means reduced capital and operating costs. The Chemineer High-Efficiency Impeller is a resuit of extensive testing. and is supported by new technology for proper process application. The HE-3 impeller has three specially designed btades. mounted at a shatîow angle, to provide a high degree of axial flow with minimal power requirements. Thus. the HE-3 high-efficiency impeller is able to create more liquid motion with less energy. Process Performance Any successful agitator design must provide some required level of process performance. Although process per­formance has many meanings in the Chemical process industries, agitator design has been quantified for most typical applications. The ChemScale ' design procédure, developed by Chemineer. is one of the best methods for relating agitation intensity to process performance. The development of a high-efficiency impeller does not change the concept of ChemScale; only thesize of agitator required for a given process resuit changes. Although bulk fluid velocity. as defined in ChemScale. is a convenient means of characterizing agitation intensity. it is just an indirect measure of process per­formance. Both the magnitude and the direction of fluid velocities are important in agitation, and must be correctly related to process performance. Thus in addition to basic hydrodynamic mea-surements. extensive expérience and testing with a variety of blending and solids suspension problems are behind each application of an HE-3 impeller. The effects of flow patterns are also important in determining impeller efficiency. The HE-3 impeller créâtes axial flow with less radial and rotational flow than a standard pitched-blade (P-4) turbine. The discharge from the high-efficiency impeller spreads less rapidly. ihus allowing the impeller to be successfully placed farther from the bottom of the tank. Consequently. tank geometry is less of a factor in designs using an HE-3 impeller because the strong axial ftow will control a wider range of liquid levels. Différent agitator horsepower and speed combinations are capable of providing similar process performance with any one type of impeller in most applications. When différent types of impellers are considered, even more equipment com­binations will produce similar results.