Removable baffles for mixing vessel

A mixing vessel may include a container having a bottom with a removable plate fixed to the bottom. The removable plate may include one or more slots for inserting baffles therein. A flexible baffle insert may include a retaining band having inner and outer opposing surfaces. A plurality of baffles may extend inwardly from the inner surface of the retaining band.

FIELD OF THE INVENTION

The invention relates, in general, to mixing vessels, and, in particular, to mixing vessels with easily interchangeable baffles.

BACKGROUND OF THE INVENTION

Mixing vessels may be used in a variety of commercial and industrial processes. A variety of materials may be mixed in a mixing vessel. Different materials and different processes may require different amounts of shear and flow patterns to properly mix the ingredients, maintain the ingredients in suspension, and circulate the ingredients within the vessel. The size, shape, location, orientation, and rotational speed of the mixing vessel impeller may be factors in producing specific flow patterns tailored for a particular product.

A mixing vessel without baffles may not produce enough shear or turbulence to mix the ingredients. Therefore, many mixing vessels may include fixed baffles that may influence the mixing action and flow patterns. The number, size, location and geometry of baffles may vary widely, generating both localized high shear between the baffle and impeller blades, and generating circulating currents that may promote the homogeneity and suspension of ingredients. A configuration of impeller and baffles that may be optimized to produce one product may be unsuitable for a different product.

The flow patterns and circulating currents may also be influenced by the shape of the vessel itself. Typically, a vessel having a concave bottom may produce better vertical dispersion because the liquid may be slung out radially from the impeller and may be gently turned upward when the liquid moves toward the vessel wall. Flat-bottomed mixing vessels may not do this function nearly as well, and may have very poor flow patterns. Acceptable flow patterns and methods of mixing a material may be discovered by adding and experimenting with various types of baffles.

In the past, new mixing vessels with optimized geometry were constructed for, and exclusively dedicated to, a specific process or product. As an alternative, existing plain mixing vessels that were, at first, completely unsuitable for a particular process, were retrofitted by adding permanently welded baffles. In such mixing vessels, it may be relatively easy and common practice to make small variations in the mixing action and fine tune it to slightly different processes by changing the impeller or its rotational speed. Changing the baffling may have a much larger effect, but it may be costly to construct a new mixing vessel each time one wishes to alter a baffle arrangement. It may also be costly to remove welded baffles and reweld new baffles in a mixing vessel.

In a manufacturing scenario where more than one product is made, for instance, the manufacturer may set up a single production line, and simply switch baffles in the mixing vessels. In a research and development scenario, the effect that each element of geometry has on the mixing process itself, or the effect that each element of geometry has on the quality of the product being produced, may be explored using many physical variations. Baffles that are easily removed and replaced in a mixing vessel may save time, money, and storage space (for multiple variations of mixing vessels), and simplify cleaning and repair of baffles. Thus, a need exists for mixing vessels having easily interchangeable baffles.

In some cases, such as laboratory bench top and glassware size vessels, a mixing vessel having the desired baffle arrangement may not be available commercially. Formulations and mixing procedures for products may be developed and tested in both small and medium scale laboratory mixers before transitioning to high rate production in full size mixing vessels. A manufacturing plant that uses 3000 gallon baffled mixers may have a laboratory where procedures are developed in quart or gallon sized mixers. Thus, there is a need to be able to adapt standard laboratory glassware mixing vessels, for instance, into scale models of larger mixing vessels, by adding baffle kits.

SUMMARY OF THE INVENTION

An aspect of the invention may be a mixing vessel including a container having a bottom. The bottom may include a removable plate fixed thereto. The removable plate may include at least one slot formed therein. A baffle may be inserted in at least one slot.

Another aspect of the invention may be a flexible baffle insert including a retaining band having inner and outer opposing surfaces, and a plurality of baffles extending inwardly from the inner surface of the retaining band. Each baffle may include first and second edges proximate the inner surface of the retaining band. The first proximate edge may form a support joint with the inner surface of the retaining band and the second proximate edge may be displaced inwardly from the first proximate edge.

A further aspect of the invention may be a mixing vessel including a container having a bottom and a generally circular side wall, and a flexible baffle insert disposed in the container.

Another aspect of the invention may be a method of making a flexible baffle insert. The method may include providing a thin, flexible material having a retaining band and a plurality of baffles, where the retaining band and the baffles are substantially coplanar. The related method may include bending the baffles along an edge such that the baffles are angled with respect to the retaining band.

The invention will be better understood, and further objects, features, and advantages thereof will become more apparent from the following description of the exemplary embodiments, taken in conjunction with the accompanying drawings.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1is a side view of a mixing vessel10andFIG. 2is a top view of the mixing vessel10shown inFIG. 1. Mixing vessel10may be one piece or it may be an assembly including, for example, a container12having a bottom14, side walls18, and a generally open interior16. The bottom of the mixing vessel may have any contour or it may be flat as shown inFIG. 1. The shape and location of the impeller15may be varied to suit a particular process.

FIGS. 3A and 3Bare top and side views, respectively, of one exemplary embodiment of a removable plate20. Plate20may include at least one fastener opening26formed therein. Plate20may include at least one slot22formed therein for receiving a baffle. A periphery of plate20may include a beveled edge42. The shape of the plate20and the location of the fastener openings26may be varied to suit a particular process.

FIG. 4is a top view of the mixing vessel10ofFIG. 2showing fastener openings28that may be formed in bottom14. Fastener openings26in plate20may correspond to fastener openings28in bottom14.

FIGS. 5A and 5Bare side and end views, respectively, of an embodiment of a baffle30. Baffles30may have any shape that is needed for a particular process. Baffle30may include a tab portion32and a body portion34. Tab portion32may be inserted into slot22in plate20. Tab portion32and slot22may form, for example, a press fit, and may be permanently joined by welding, brazing, or any other joining process. Tab portion32and body portion34may be substantially planar.

FIGS. 6A and 6Bare side and end views, respectively, of another exemplary embodiment of a baffle36. Baffle36may include a tab portion40and a body portion38. Tab portion40may be inserted into slot22in plate20. Tab portion40and slot22may form, for example, a press fit, and may be permanently joined by welding, brazing, or any other joining process. Body portion38may be angled with respect to tab portion40by angle A. Angle A may be any angle that is needed for a particular process. In the embodiment ofFIG. 6B, angle A is about 15 degrees.

FIG. 7Ais an embodiment of an independent baffle42. Baffle42may include a tab portion43and a body portion44. Tab portion43may include a fastener opening46that corresponds to fastener openings28on bottom14of the mixing vessel ofFIG. 4. Baffles42may have any shape that is needed for a particular process.

FIG. 7Bshows perspective views of a fastener24, a washer47, and a spacer48of thickness49. The washer47and the spacer48may include fastener openings similar to the fastener opening46in tab43of baffle42.

FIG. 7Cis a perspective view of a baffle assembly45including a spacer48, a baffle44, a washer47and a fastener24, prior to disposition on bottom14of the mixing vessel ofFIG. 4.

For clarity, inFIGS. 8,9, and10, the side walls18of container12are not shown.FIG. 8is a perspective view of a container bottom14having a removable plate20with baffles30as shown inFIGS. 5A and 5B.FIG. 9is a perspective view of a container bottom14having a removable plate20with baffles36as shown inFIGS. 6A and 6B. Removable plate20may be fixed to bottom14with fasteners24.

FIG. 10is a perspective view of a container bottom14having baffle assemblies45, as shown inFIG. 7C, disposed therein. The baffle assemblies45may not require a removable plate20, and may be disposed anywhere inside the mixing vessel where suitable fastener openings28are located. Baffles assemblies45may be rotated to any angle about the axes of fasteners24as needed to suit a particular process. The spacer thickness49may create a gap between the bottom of the assembly45and the surface having the fastener opening28, which may be varied as needed to suit a particular process. The washer47and spacer48shown inFIG. 7Cmay form a seal for the fastener openings28in bottom14, shown inFIG. 4.

Any number of baffles may be used as needed for a particular process. InFIGS. 8,9, and10, eight baffles are shown.

FIGS. 11A and 11Bare side and top views, respectively, of the mixing vessel10ofFIG. 2including one exemplary embodiment of a removable baffle assembly19. Assembly19includes removable plate20and baffles30, retained by fasteners24.

FIG. 12is a top view of a portion of a flexible baffle insert52. Insert52may include a retaining band56having inner and outer opposing surfaces60,62, respectively. A plurality of baffles58may extend inwardly from the inner surface60of the retaining band56. Baffles58optionally may be spaced substantially equally on the retaining band56. The total number of baffles58and their shape may be varied as needed for a particular process. A pair of tabs68may be disposed on opposite ends of the retaining band56and angled inwardly.

As best seen inFIGS. 12,15A, and15B, each baffle58may include a first edge64proximate the inner surface60of the retaining band56and a second edge66proximate the inner surface60of the retaining band56. First edge64may be more proximate inner surface60than second edge66. First (proximate) edge64may form a support joint with the inner surface60of the retaining band56. Second (proximate) edge66may be displaced inwardly from the first (proximate) edge64. The displacement of the second (proximate) edge66away from the first (proximate) edge64may provide a gap or open area80between a portion of baffle58and the side wall76of container74. Gap80may be helpful in some mixing processes.

Each baffle58may include an upper edge70that forms an angle B (FIG. 12) with respect to the inner surface60of the retaining band56. InFIG. 12, the angle B is about 90 degrees, for example. However, angle B may be other than ninety degrees. Each baffle58may include a lower edge72(seeFIG. 14, also) that forms an angle D between the lower edge72of the baffle58and the inner surface60of the retaining band56. When angles B and D are the same, the baffle58will be vertically oriented.

In the exemplary embodiment shown inFIGS. 12,15A, and15B, angle D is larger than angle B, such that baffle58is “slanted.” In the Figs., in an exemplary embodiment, angle B is about 90 degrees and angle D is about 110 degrees. Other exemplary values for angles B and D may be used.FIG. 13is a view along the line13-13ofFIG. 12showing the slant of baffle58in a different perspective. Angle C inFIG. 13is about 80 degrees, for example. Other exemplary values for angle C may be used.

FIG. 14is a side view of a flexible baffle insert52, prior to preforming. InFIG. 14, baffles58are substantially coplanar with retaining band56. Baffles58and retaining band56may be formed from a single sheet of material such as, for example, spring-temper brass shim stock. The shim stock may be, for example, about 0.015 inches thick. After stamping the shim stock to produce the configuration shown inFIG. 14, baffles58may be bent along edges64such that the baffles58are angled with respect to the retaining band56. As noted above, baffles58may be bent so that upper edge70forms an angle B with retaining band56. InFIG. 12, angle B is about 90 degrees, but other angles may be used. After bending baffles58, each baffle58includes an edge66proximate the retaining band56, but displaced away from the retaining band56, that is, edge64is more proximate the retaining band56than edge66.

If one desires a baffle insert52with baffles58that are not vertical, then one may further bend the baffles58. One may further bend baffle58such that upper edge70of the baffle58forms an angle B with respect to the retaining band56that is different than an angle D of a lower edge72of the baffle58with respect to the retaining band56.FIGS. 12,13,15A, and15B show an embodiment where angle D is larger than angle B.

The retaining band may be bent into a curve approximately as shown inFIG. 12. This curve may have a radius that is larger than the radius of the interior of the mixing vessel50. The retaining band56may be flexed into a circular shape by squeezing together the pair of tabs68disposed on opposite ends of the retaining band56. Insert52may be inserted into a mixing vessel50, and the pair of tabs68released. As the retaining band56expands, it grips the side wall76as shown inFIGS. 15A and 15B. In an iterative process, the insert52may be removed, its curvature may be adjusted, and it may be reinserted into vessel50, until no gaps are visible between the retaining band56and the side wall76.

FIGS. 15A and 15Bare side and top views, respectively, of a mixing vessel50with a flexible baffle insert52disposed therein. Mixing vessel50may include a container74having a bottom78and a generally circular side wall76. Mixing vessel50may have an impeller54disposed therein. Container74may be any type of container.FIGS. 15A and 15Bshow a standard, plain Groen jacketed container, by way of example, with a flexible baffle insert52therein.

Finally, any numerical parameters set forth in the specification and attached claims are approximations (for example, by using the term “about”) that may vary depending upon the desired properties sought to be obtained by the present invention. At the very least, and not as an attempt to limit the application of the doctrine of equivalents to the scope of the claims, each numerical parameter should at least be construed in light of the number of significant digits and by applying ordinary rounding.