Static Material Mixing Apparatus

The present invention relates to static material mixers and, more particularly to a static material mixer which permits passage of solids.

Static material mixers are well known as a means for mixing a plurality of materials into a single mass without a need for a rotary mixer, such as a motor. See for example Federighi et al, U.S. Pat. No. 4,511,258 entitled "Static Material Mixing Apparatus". However when mixing liquids which contain solids, such prior art static material mixers are prone to clogging when the solids pass through. This clogging requires repeated maintenance which is expensive and can be quite distasteful, such as when the static material mixer is utilized to mix raw sewage.

The invention is provided to eliminate some or all of the above problems.

It is an object of the invention to provide a static material-mixing apparatus.

In accordance with the invention, the static material-mixing apparatus comprises a conduit having an axis and defining a chamber extending longitudinally therethrough opening on first and second ends of the conduit and a mixing element including two continuous segments in the chamber between the first and second ends, each of said segments having a generally sinuous cross-section between the first and second ends, the segments being disposed in radially spaced relationship with each other.

The conduit and the chamber are circular in cross section and each of the segments includes a plurality of angularly-related plates interconnected at opposite ends.

Adjacent plates of the respective segments are angularly related in opposite directions and the plates define angles of the order of thirty-five degrees to forty-five degrees with respect to the axis. The spaced relationship provides a gap between the two segments of approximately five to eighty percent of the diameter of the chamber.

Other features and advantages of the invention will be apparent from the following specification taken in conjunction with the accompanying drawings.

FIG. 1 is an exploded perspective view of the static mixing apparatus according to the invention;

FIG. 2 is a side elevational view partly in section as viewed along line 2--2 of FIG. 1;

FIG. 3 is a plan view as viewed along line 3--3 of FIG. 2; and

FIG. 4 is a cross sectional view as viewed along line 4--4 of FIG. 2.

The following specification incorporates by reference the specification of Federighi et al, U.S. Pat. No. 4,511,258 entitled "Static Material Mixing Apparatus".

While this invention is susceptible of embodiment in many different forms, there is shown in the drawings and will herein be described in detail a preferred embodiment of the invention with the understanding that the present disclosure is to be considered as an exemplification of the principles of the invention and is not intended to limit the broad aspect of the invention to the embodiment illustrated herein.

FIG. 1 of the drawings discloses a static mixing device, generally designated 10, consisting of a conduit 12, and a mixing element 14 that is adapted to be inserted into the conduit 12 to define tortuous flow paths for a plurality of fluids so that the fluids are mixed into a homogeneous mass. The conduit 12 may be constructed of plastic, metal or other suitable materials. Preferably, the conduit 12 is circular in cross-section and defines an internal chamber 16 which is open at opposite ends 18 and 20. The diameter of the conduit 12 may be of any dimension, though diameters of 1/2" to 60" are typical. The opposite ends 18 and 20 may have suitable fittings thereon for connection to sources of materials that are to be mixed, and these have been deleted from the drawings for purposes of clarity.

The mixing element 14 comprises two segments, 14a, 14b of a specific configuration which each can be formed from flat sheets of stock material. After the two segments 14a, 14b have been formed, they are inserted into the conduit 12 in a radially spaced relationship, providing a gap 21 there-between (FIGS. 3 and 4) and are secured therein to the conduit 12, as by an adhesive if the conduit 12 is plastic or by welding if the conduit 12 is metal. The two segments 14a, 14b each essentially consist of identical segments that have what may be termed as a "sinuous cross-section" between opposite ends.

As illustrated in greater detail in FIG. 4, each of the two segments 14a, 14b occupies less than one-half of the cross-sectional area of the conduit 12, or internal chamber 16, thereby providing the gap 21 permitting passage of solids.

More specifically, with reference to FIG. 1, each of the segments 14a, 14b consist of a plurality of identical, generally flat plates 30 that are joined to each other at opposite ends 32. Each of the plates has a substantially planar inner surface or edge 34 (FIG. 4) and an outer edge 36 that conforms generally to the peripheral configuration of chamber 16, which is defined by the inner surface of conduit 12. The two substantially identical segments 14a, 14b are preferably axially-staggered with respect to each other, as illustrated in FIGS. 1 and 2, and the plates 30 define an angle A with respect to a central axis or central line CL of the conduit 12 The greater the angle, the greater the mixing capability of the mixing device 10 per unit length: however, a greater angle also results in a greater back-pressure and, hence, a greater pressure drop across the mixing device 10. The angle A can be of the order of about 25.degree. to about 50.degree., or preferably about 30.degree. to about 45.degree., for the preferred form of the present invention.

Referring to FIG. 2, the plates 30 of the respective segments 24 define substantially equal angles with respect to center line CL, but the angles extend in opposite directions from the center line to define a plurality of what may be termed generally diamond-shaped cavities or mixing chambers, generally designated by reference numeral 48.

Once inserted into the conduit 12, the mixing element 14 defines a tortious path for a plurality of materials that are intended to be mixed. For example, a first fluid could be connected by a conduit to one side of the center of the inlet 20 and a second fluid could be connected to the inlet 20 adjacent the opposite side of the center. Thus, the first fluid would flow generally downwardly along a first plate or baffle 30a (FIG. 1), while the second fluid would flow generally upwardly along baffle 30b. Both fluids are therefore forced towards the first mixing chamber from opposite sides of the center of the conduit 12 and the mixing process is commenced. As the two fluids are entering the first mixing chamber 48, the fluids are spinning, which produces a swirling action. The partially mixed fluids will be split again by the edges of the plates 30 as they leave the first mixing chamber 48 and are directed to the next mixing chamber 48.

Of course, the respective fluids which are then partially mixed are again moved to the next succeeding mixing chamber 48 by pressure of the fluid on the inlet, but enter again from opposite sides of the center of the conduit 12 for further mixing of the fluids. The process is continued alternately in each of the mixing chambers 48 along the entire length of the mixing element 14 within the conduit 12 until a totally homogeneous mass is produced, which flows out of the outlet 18.

A primary benefit of the invention is that solids suspended within the fluids can pass through the internal chamber 16 via the gap 21 without clogging. The gap 21 can be of the order of 5-80% of the radial width of the internal chamber 16, depending on the particular solids involved, though 33% has been found generally acceptable.

In certain circumstances, the presence of the gap 21 can reduce the per unit length mixing efficiency of the static mixing device 10 as compared to the device disclosed in the Federighi et al. '258 patent. However, this can be accommodated if necessary by simply increasing the length of the static mixing device 10.

The selection of material for producing the static mixing device 10 will depend upon the particular application, and the static mixing device 10 can be formed from metal or various plastic materials.