Abstract: The present invention provides an improved aeration impeller for use in a mixing assembly having an axis of rotation. The aeration impeller includes a hub and a first and second blades that are connected to the hub. Each blade has a first portion positioned at an angle to the axis of rotation and a second portion positioned at an angle to the first portion. The first portion of each blade has an opening that at least partially extends the width of the first portion.

Abstract: A radial disc impeller for use with a liquid or liquid suspension mixing assembly, having an axis of rotation. The radial disc has a hub and at least one disc extending radially away from the axis of rotation. The disc is connected to the hub at first axial location. The disc impeller includes a first blade connected to the disc. The first blade has an extension that extends radially away from the axis of rotation. The disc impeller also includes a second blade connected to the disc. The second blade has an extension that extends radially away from the axis of rotation.

Abstract: A more efficient process and method for dispersing gas or other fluids into a liquid which may have solid suspension. More particularly, the process includes maximizing the transfer of oxygen by an impeller by selecting a Froude Number value and/or Surface Power Density value and analyzing these two relative to the desired Standard Aeration Efficiency value desired for the impeller.

Abstract: The present invention provides an improved surface aeration impeller for use in a mixing assembly. The improved surface aeration impeller includes a hub and a first blade that is connected to the hub. The blade has a substantially straight first portion and a substantially curved second portion. The impeller also has a second blade connected to the hub that has a substantially straight first portion and a substantially curved second portion.

Abstract: A radial disc impeller for use with a liquid or liquid suspension mixing assembly, having an axis of rotation. The radial disc has a hub and at least one disc extending radially away from the axis of rotation. The disc is connected to the hub at first axial location. The disc impeller includes a first blade connected to the disc. The first blade has an extension that extends radially away from the axis of rotation. The disc impeller also includes a second blade connected to the disc. The second blade has an extension that extends radially away from the axis of rotation.

Abstract: The present invention provides an apparatus and method for mass transfer of gas or other fluids into a liquid and/or liquid suspension. The present invention is preferably used in conjunction with waste treatment processes and/or fermentation processes that are commonly carried out in a mixing vessel. In such an arrangement, the mass transfer process is utilized to contact air to liquid in a mixing vessel or aeration basin.

Abstract: An improved mixing apparatus and method for dispersing gas or other fluids into a liquid which may have solid suspension. The improved mixing apparatus includes a mixing vessel having at least one side wall and a bottom wall. The apparatus also has upper and/or lower reflectors attached to the side wall, positioned at an angle to the side wall. The apparatus may additionally include a shaft with a first impeller having a first diameter attached thereto and a second impeller having a second diameter attached thereto. The first impeller and second impeller are positioned a distance apart.

Abstract: The present invention provides an improved aeration impeller for use in a mixing assembly having an axis of rotation. The aeration impeller includes a hub and a first and second blades that are connected to the hub. Each blade has a first portion positioned at an angle to the axis of rotation and a second portion positioned at an angle to the first portion. The first portion of each blade has an opening that at least partially extends the width of the first portion.

Abstract: An improved mixing apparatus and method for dispersing gas or other fluids into a liquid which may have solid suspension. The improved mixing apparatus includes a mixing vessel having at least one side wall and a bottom wall. The apparatus also has upper and/or lower reflectors attached to the side wall, positioned at an angle to the side wall. The apparatus may additionally include a shaft with a first impeller having a first diameter attached thereto and a second impeller having a second diameter attached thereto. The first impeller and second impeller are positioned a distance apart.

Abstract: The present invention provides an improved surface aeration impeller for use in a mixing assembly. The improved surface aeration impeller includes a hub and a first blade that is connected to the hub. The blade has a substantially straight first portion and a substantially curved second portion. The impeller also has a second blade connected to the hub that has a substantially straight first portion and a substantially curved second portion.

Abstract: The present invention provides an apparatus and method for mass transfer of gas or other fluids into a liquid and/or liquid suspension. The present invention is preferably used in conjunction with waste treatment processes and/or fermentation processes that are commonly carried out in a mixing vessel. In such an arrangement, the mass transfer process is utilized to contact air to liquid in a mixing vessel or aeration basin.

Abstract: A more efficient process and method for dispersing gas or other fluids into a liquid which may have solid suspension. More particularly, the process includes maximizing the transfer of oxygen by an impeller by selecting a Froude Number value and/or Surface Power Density value and analyzing these two relative to the desired Standard Aeration Efficiency value desired for the impeller.

Abstract: An axial flow mixer impeller which is high in efficiency in terms of flow is made more effective, when used in a sparging system for dispersion and for mass transfer of a liquid phase or a gaseous phase into a liquid which is being mixed or agitated, by forming a shear field which breaks the phase being dispersed into fine bubbles which are dispersed by the impeller. This is accomplished without a major effect on the high flow efficiency of the axial flow impeller. To this end a structure which forms a Venturi is located on the side or sides of the blade where the phase (bubbles of fluid of different density or viscosity which are to be mixed or dispersed by the impeller) occurs, in the high velocity region near the tip of the blade. This Venturi creates a high shear field which breaks up the bubbles and disperses them as fine bubbles as they leave the impeller. The structure may be provided by a pair of proplets in the vicinity of the tip end of the blade which form a wedge shaped flow path therebetween.

Abstract: An axial flow mixing impeller system for efficient mass transfer by control of size of the bubbles of the fluid which is being dispersed, especially gases and liquids with viscosities greater than the liquid into which dispersion occurs, is obtained by creating passageways through the impeller blades for flow between the suction and pressure sides of the blades which disrupts the flow over the suction sides of the blades thereby reducing the tendency for bubbles to grow or coalesce into large bubbles which instead of being dispersed, rise to the surface without effective mass transfer to the liquid which is pumped by the impeller. The blades of the impeller may be slotted inwardly from the tips thereof to provide the passageways or may be formed from segments, gaps between which provide the flow passageways.

Abstract: Mixer apparatus having an impeller on a shaft, which circulates a body of liquid the surface of which can clear the impeller, especially when the liquid is in a tank, and the tank is drained, is protected against excessive by use of a flexural member, which may be in the form of radially opposed pairs of resilient plates, which extend from the shaft and are attached thereto by a collar. As the liquid surface drops below the impeller, the members present surfaces to the liquid in the tank on which forces are opposing the oscillation are developed by interaction of the surfaces with the liquid in the tank. Restoring forces on the shaft due to the flexing of the resilient plates also reduce the shaft oscillation. The stiffness of the plates is selected to optimize the restoring forces for the mixing apparatus which is stabilized.

Abstract: 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.

Abstract: A rotatably driveable enhanced-flow impeller system has a radial flow impeller with a first impeller face disposed proximate the bottom of the tank and proximate or extending into an inlet port for liquids in the tank bottom. The radial flow impeller has a plurality of blades with radially outermost blade tips terminating along a blade terminating circle. The blades and inlet port are contoured to reduce shear stress on the liquids. Disposed adjacent a second opposing face of the radial flow impeller is a radial flow extension plate which preferably extends radially outwardly along the second face by a radial distance beyond the blade terminating circle. The radial flow extension plate may be fixedly attached to the second impeller face.

Abstract: In order to extend the life of mixing impellers which circulate materials, and particularly which suspend solids, in the form of particles which erode the blades of the impellers and place a practical limit on impeller speed and/or angle of attack due to increased erosion at high flow velocity (erosion being a function of the cube of the velocity), the blades are constructed from blades into an airfoil configuration which does not limit the thickness of the plates and thereby allows the use of thick plates having extended life. An erosion resistant layer is located at least over the leading edge region of the blade and the shape of the blade reduces velocity of flow over the leading edge; the camber of the blade being maximized midway between the leading and trailing edge. The suction surface of the blade in the region subject to erosion is continuous thereby avoiding discontinuities which form vortices which enhance erosion.

Abstract: Impellers and impeller systems are described which enable liquids and liquid suspensions to be mixed and blended where the size of the impeller and the viscosity of the liquid may require operation in the turbulent and laminar flow regimes, as well as in the transitional flow regime therebetween. The impellers have a plurality of fluidfoil blades and have camber and twist. The angle at the tip of two diametrically disposed blades of a four blade impeller may have a different blade angle at the tip than the other pair of blades. A pair of impellers may be used. These impellers may be of different diameter and disposed in close proximity so that they are in dependent relationship (preferably spaced apart by less than the diameter of the larger impeller).

Abstract: Impellers and impeller systems are described which enable liquids and liquid suspensions to be mixed and blended where the size of the impeller and the viscosity of the liquid may require operation in the turbulent and laminar flow regimes, as well as in the transitional flow regime therebetween. The impellers have a plurality of fluidfoil blades and have camber and twist. The geometric pitch or blade angle increases from the tip of the blade towards their axis of rotation in a manner to provide an over pitched condition so that the pitch ratio of the blades at 40% of the blade radius from the axis is greater than the pitch ratio at the tip. The blades are preferably smoothly tapered and increased in width from the tip towards the axis. The impeller blades are mounted on a hub connected to a drive shaft. The blades may decrease in width where they connect to the hub. The pitch angle at the tip is in the range of 18.degree. to 30.degree. (preferably about 20.degree.).