초록 ▼

A mixing process may be carried out in a tank of a certain diameter. The process may also be constrained to the use of an impeller of certain diameter in order to obtain the flow pattern desired to carry out the process. The power consumption of the system which may be expressed in terms of flow per

A mixing process may be carried out in a tank of a certain diameter. The process may also be constrained to the use of an impeller of certain diameter in order to obtain the flow pattern desired to carry out the process. The power consumption of the system which may be expressed in terms of flow per unit (Q/P) is optimized for the impeller diameter to tank diameter (D/T) constraint by utilizing an axial flow blade, preferably having camber and a tip chord angle at the tip and an angle near the attachment to the shaft (the hub) which rotates the impeller, where the tip chord angle and the twist the difference between the blade angle (between the chord and a plane perpendicular to the axis of rotation of the shaft between the tip and hub) are varied in opposite senses; for example, increasing the tip chord angle to provide a more D/T for a more optimum Q/P to which the process is constrained and then reducing the twist to maintain the power efficiency at the higher tip chord angle. The freedom to increase the tip chord angle and reduce the twist provides flexibility enabling the use of a limited number, say three, of hubs, thereby reducing the cost of the impeller system. The efficiency of the impeller is further increased by reducing tip vortices using slots in the tip which have an effect on the flow pattern similar to the effect of proplets but at reduced cost of fabrication. Where additional turbulence is required so as to establish shear forces in the fluid or fluid suspension being mixed, the blade segments which define the slots may be twisted at angles different from the tip chord angle. These twisted segments increase turbulence and shear the material being mixed.

대표청구항 ▼

[ What is claimed is:] [1.] An axial flow impeller rotatable by a shaft in a tank of certain diameter, said impeller having blades, opposite ends of said blades respectively, defining tips and attachments to said shaft, the blades having a certain diameter defined by said tips, said blades having a

[ What is claimed is:] [1.] An axial flow impeller rotatable by a shaft in a tank of certain diameter, said impeller having blades, opposite ends of said blades respectively, defining tips and attachments to said shaft, the blades having a certain diameter defined by said tips, said blades having a blade angle at said tips (TCA) and having a blade angle at said attachments, said blades having twist which is the difference between the blade angle at said opposite ends, said impeller being characterized in that the flow efficiency (Q) for applied shaft rotating power (P) is optimized by having said blade angle at said tips (TCA) inversely related to the twist of said impeller.