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Impellers Bulletin

Impellers Bulletin
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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 sens, 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 shatow 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 per鮭formance has many meanings in the Chemical process industries, agitator design has been quantified for most typical applications. The ChemScale ' design procdure, 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 exp魩rience 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 crtes 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. Diff颩rent agitator horsepower and speed combinations are capable of providing similar process performance with any one type of impeller in most applications. When diffrent types of impellers are considered, even more equipment combinations will produce similar results.

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The agilalor slections tor two diffrent process situations are shown in the tables. Four diff驩rent agitators. capable of similar process performance using standard P-4 turbines, arecompared with four agitators using HE-3 high-efficiency impeflers for each situation. A smaller Chemineer HT Agitator Drive size is required for the same process results. Similar or lower horsepower motors can be used with the larger-diameter HE-3 impellers. The benefits of a more efficient impeller delivering quivalent process performance are available for both new and existing applications. Many agitators can...

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