Inline Fluid Mixing Device

Abstract

A device for installation in a flow conduit for mixing fluids flowing through the conduit. The device consists of an elongated body member containing a plurality of longitudinally spaced apertured mixing elements, the mixing elements being comprised of solid plugs having lengths equal to at least one quarter of their diameter and having a plurality of angularly disposed apertures therethrough. The angle of the apertures can be reversed in adjacent mixing elements to improve fluid mixing.

Parent Case Text

This application is a continuation-in-part of application Ser. No. 701,617, filed June 30, 1968, now abandoned.

Description

This invention is directed to fluid mixing, and more particularly to an improved inline mixing device for installation in a flow conduit that is adapted for mixing fluids flowing through the conduit.

It is often desired to mix two or more fluids in a flow conduit so as to obtain a uniformly admixed fluid mixture. In the simplest mode of accomplishing this mixing, the fluids can be introduced into the conduit and passed through a length of the conduit. However, the effectiveness of the mixing obtained by this technique is largely dependent upon the fluid properties and flow velocities involved. Often, particularly with fluids which are not readily miscible, the conduit must be unreasonably long to assure uniform mixing. Accordingly, various devices have been proposed for installation in the flow conduit to improve the efficiency of mixing. However, the heretofore known inline mixing devices have not provided satisfactory mixing in all applications and need exists for an improved inline mixing device that is relatively simple and economical to construct, that is compact and easy to disassemble for cleaning, and that provides good mixing performance. A further need for an improved inline mixing device arises for admixing a small quantity of fluid material, such as an inhibitor, catalyst, or dye, into a relatively large volume of fluid flowing through a conduit.

Accordingly, it is a primary object of this invention to provide a device for installation in a flow conduit that effects mixing of two or more fluids flowing through the conduit. Another object is to provide an inline fluid mixing device that is relatively simple and economical to construct. Still another object is to provide a compact fluid mixing device. A yet further object is to provide an efficient inline mixing device that is easily disassembled for cleaning. A still further object is to provide an inline mixing device particularly adapted for mixing a small amount of a fluid into a relatively large volume of fluid flowing through a conduit. Other objects and advantages of the invention will be apparent from the following description and appendant drawings, of which:

FIG. 1 is a sectional view taken longitudinally through one embodiment of the device of this invention.

FIG. 2 is an end view of the device of FIG. 1.

FIG. 3 is a sectional view taken longitudinally through another embodiment of the device of this invention.

FIG. 4 is an end view of the apertured mixing element.

FIG. 5 is a perspective view of the apertured mixing element showing the approximate configuration of apertures.

Referring to FIGS. 1 and 2 wherein there is illustrated one embodiment of the invention comprising elongated body member or housing 10 provided with end flanges 12 and 14 adapted to mate with a flanged conduit, such as a conventional flanged piping system. While it is to be recognized that the body 10 can be constructed with any cross-sectional shape, in one convenient configuration the body 10 is of tubular construction and has a circular cross section. Thus, body 10 can comprise a relatively short flanged pipe spool. The flanges 12 and 14 are respectively provided with a number of holes 16 and 18 arranged about their circumferences to accommodate the bolting of flanges 12 and 14 to the mating flanges of the piping system. The flanges 12 and 14 can also be provided with raised faces 20 and 22, respectively, to afford a gasket surface. The gasket, not shown, is installed between the mating flanges on assembly to afford a fluid-tight connection of the body member 10 to the piping system.

The assembled mixing device has a plurality of apertured mixing elements 30 positioned within the body 10, two such elements being shown in the device illustrated in FIG. 1. The angularly disposed apertures in the mixing elements impart rotational motion to the fluids passing therethrough. Accordingly, improved mixing can be effected by reversing the angle of rotation in adjacent mixing elements so that the direction of rotation of the fluids is reversed in passing through each of the mixing elements. The apertured mixing elements 30 are maintained in a relatively fixed, longitudinally spaced position within body 10 by means of spacers 32 placed between the elements and the threaded retainers 34, and by similar spacers 32 placed between adjacent elements. Spacers 32 can comprise any form of structure that maintains the elements in a fixed longitudinal position within the body 10 and that allows fluid to flow through body 10. In one form, these spacers can conveniently comprise short tubular sections having an outside diameter slightly smaller than the inside diameter of the body 10 so that the spacers are easily assembled therewithin, and having an unobstructed center flow passage to readily accommodate the passage of fluid through the device.

Flanges 12 and 14 are internally threaded to receive the similarly threaded annular retainers 34. The use of standard Acme threads in this service allows the retainers to be readily removed to permit dismantling of the mixing assembly for cleaning and replacement of the mixing elements. The interior opening of the threaded retainers can be constructed with a hexagonal or other polygonical shape to permit insertion of an appropriate tool for engaging and disengaging the threaded retainers. Alternatively, instead of employing a threaded retainer 34 at each end of the device, one flange can be provided with an internal shoulder, or other fixed retainer means, and the other of the flanges provided with a threaded retainer.

In this embodiment of the invention, two or more fluids are introduced into a fluid conduit upstream of the mixing device and the fluids mixed upon passing through the device. The number of mixing elements, and the size and configuration of the apertures can be varied, depending upon the physical properties of the fluids, to effect optimum mixing of the fluids. Alternatively, the device can be provided with one or more additional fluid inlets, as will be hereinafter more fully described, so that additional fluids can be introduced into the device and admixed with the main fluid stream passing therethrough.

Another embodiment of the invention, illustrated in FIG. 3, that is particularly suited for smaller size installations, comprises a mixing device having an elongated body member 60, such as a relatively short section of pipe or other conduit internally threaded at 62 and 64 adjacent either end to receive similarly threaded annular retainers 66. Retainers 66 are provided with hexagonal or other polygonical shaped heads 68 to facilitate assembly and disassembly of the device, and are internally threaded at 70 for attachment of a conduit, such as a threaded pipe. Since it is preferred that the threads 62 and 64 are of the Acme type to facilitate insertion and removal of the retainers, retainer 66 is provided with circumferential groove 72 adapted to receive O-ring 74 to provide a fluid-tight joint. Also, the internal diameter of the body 60 can be increased in diameter in the threaded sections 62 and 64 to facilitate insertion of the mixing elements and spacers.

As in the hereinbefore described embodiment of the invention, a plurality of perforate mixing elements 30 are positioned within body 60, the device illustrated in FIG. 3 having three such elements 30 maintained in a relatively fixed, spaced longitudinal relationship by spacers 32 as hereinbefore described.

Also, the mixing device shown in FIG. 3 illustrates means for introducing a second fluid directly into the mixing device. In this embodiment, body member 60 is provided with lateral inlet connection 76 at a point on the inlet side, or upstream, of the first mixing element. The main fluid enters axially onto the body member 60 and passes longitudinally therethrough, and a second fluid enters body member 60 through side connection 76, these fluids being admixed in passage through the downstream mixing elements. The spacer 32 juxtaposed to the inlet 76 is apertured at 78 to permit entry of the fluid. Alternatively, fluid inlet 76 can be located between two of the mixing elements 30 so that the second fluid is admixed at an intermediate point. Also, other lateral inlet connections can be provided in the body member 60 to permit the introduction of additional fluids at intermediate points in the device.

The mixing elements 30 are preferably constructed of a solid plug of metal, or of a plastic, such as Teflon, having a cross-sectional size and configuration adapted to provide a slip fit in the body member. Thus, for use with the preferred tubular body members, mixing element 30 is constructed of a solid cylindrical plug. The mixing performance of the device depends at least in part on the respective configuration of the individual mixing elements, it having been found that superior performance is obtained with a device employing elements that have a length at least about one-fourth of their width, i.e., the longitudinal dimension of the mixing element as assembled in the device is at least about one-fourth of the transverse dimension. While the element 30 can be of any length in excess of this critical dimension, it is preferred that the element be no less than about one-fourth of its width or diameter and no greater than about equal to this dimension. In an even more preferred embodiment, the length of the element 30 is maintained at about one-half of its width or diameter. Thus, in a device employing a tubular housing, the individual mixing elements each comprise short solid cylinders having a length of from about one-fourth of its diameter to about equal to its diameter, and preferably having a length equal to about one-half of its diameter.

As more specifically illustrated in FIGS. 4 and 5, mixing element 30 is provided with a plurality of longitudinal apertures 80 circumferentially disposed about the element and extending its length, the apertures being disposed at an angle from the center axis of the element. The apertures 80 can be conveniently formed by drilling through the plug at an angle with the longitudinal axis, the apertures preferably being disposed at an angle of about 30.degree. to about 60.degree., and even more preferably at an angle of about 45 degrees. Accordingly, the apertures 80 originate at one face of mixing element 30 and extend the length of the element, preferably terminating at the opposite face at a point an equal radial distance from the longitudinal axis as the origin, but angularly displaced therefrom. The apertures 80 are arranged so that flow is not blocked by the spacers 32. Rotational flow direction is imparted to the fluids passing through the angularly disposed apertures. Improved mixing is achieved by reversing the angular displacement of the apertures in adjacent mixing elements, thereby causing the rotational direction of flow of the fluids to be reversed on passing through each mixing element.

Two or more fluids, introduced into and passing through the above-described mixing device are admixed sufficiently that the fluid discharged from the device is substantially uniformly mixed. While the mixing device of the invention can be used to admix any fluid materials, it is particularly adapted for admixing a small amount of a second fluid into a main fluid stream flowing through a conduit. The device of this application has particular application in adding small volumes, such as one percent, or less, of an inhibitor, catalyst, dye, or other fluid agent into a main fluid stream passing through a conduit.

The improved mixing obtained with the device of this invention and the effect of the dimensions of the mixing plugs on mixer performance is demonstrated by a comparative mixing test in which kerosene and water are admixed with the mixing device of this invention and with a similar mixing device employing plug elements having lengths less than the critical length, i.e., having lengths less than one-fourth of its diameters. The mixing device is assembled substantially as illustrated in FIGS. 3, 4 and 5 of the drawings. Outer housing 60 and tubular spacers 32 are constructed of transparent plastic tubing so that the mixing action at various locations within the device can be viewed during the test. Three plug elements 32 are mounted in longitudinally spaced relationship within the housing 60 so as to define an inlet chamber upstream of the first plug element, an intermediate chamber between the first and second plug elements, a second intermediate chamber between the second and third plug elements, and an exit chamber downstream of the last plug element.

In this test, kerosene and water are contained in separate closed reservoirs. The kerosene is dyed green and the water is dyed red to facilitate observation of the mixing action within the mixing device. Air under regulated pressure is introduced from a common air conduit into the top of each reservoir above the liquid surface to force the kerosene and water, respectively, from the reservoirs and through separate conduits to the mixing device. The liquids are introduced separately into the inlet chamber of the mixing device, are contacted as they pass through the device, and the admixed liquid effluent is collected in a graduated cylinder and the collected volume measured at various time periods. The liquid flow rate through the mixing device is controlled by adjusting the pressure maintained in the liquid reservoirs. Since air is supplied to the reservoir from a common source, each reservoir is maintained at the same pressure, and the relative proportion of kerosene and water admixed is substantially constant throughout the test.

A first series of test runs are made at different flow rates employing a mixing device in which the three mixing elements 30 are constructed of flat plates having a diameter of 1 inch and a thickness of one-sixteenth inch. Thus, the length of the plug elements employed in these test runs is one-sixteenth of the diameter, which is less than the critical value of one-fourth of the diameter. Each plug element has five small longitudinal apertures uniformly disposed at an angle of about 45.degree. from the center longitudinal axis substantially as illustrated in FIGS. 4 and 5 of the drawings. The angular displacement of the apertures is reversed in adjacent plug elements to reverse the direction of rotation of the liquids passing through successive plug elements. Test runs are made at reservoir pressures of 10, 20, 40 and 60 p.s.i.g. to determine mixing performance at various flow rates. The appearance of the liquid in both of the intermediate chambers and in the exit chamber of the device is noted at each flow rate and compared with a standard to establish the degree of mixing obtained in each mixing stage. The admixed liquid exiting the mixing device readily separates into two phases in the collection vessel.

A second series of test runs at similar flow rates is made employing a mixing device in which the three mixing elements 30 are constructed of cylinders having a diameter of about 1 inch and a length of one-half inch. The length of the plug elements employed in these test runs is one-half of the diameter, which is in accordance with the configuration of this invention. Each plug element has five small longitudinal apertures uniformly disposed at an angle of about 45.degree. from the center longitudinal axis substantially as illustrated in FIGS. 4 and 5. The angular displacement of the apertures in adjacent plug elements is reversed. The degree of mixing of the liquids after passage through each plug element is determined, as before. It is observed that the degree of mixing of the liquids obtained with the mixing device of this invention is superior at all flow rates tested than that obtained with the mixing device employing mixing elements having a length less than one-fourth of their diameter. The results of this comparative mixing test are reported in table 1. ##SPC1##

Various embodiments and modifications of this invention have been disclosed in the foregoing description and the attendant drawings, and further modifications and revisions will be apparent to those skilled in the art. Such modifications and changes are included within the scope of this invention as defined by the following claims.

Claims

Having now described my invention, I claim:

1. A fluid mixing device for installation in a fluid-carrying conduit, which comprises:

an elongated housing having an inlet end and an outlet end;

connecting means at either end of said housing for fluid-tightly connecting the device to a fluid conduit;

a plurality of apertured mixing elements positioned in longitudinally spaced relationship within said housing, each of said mixing elements comprising a solid body having a cross-sectional configuration substantially conforming to the interior shape of said housing, a length of at least about one-fourth of its width, and having a plurality of angularly disposed longitudinal apertures extending its length; and

means for maintaining said mixing elements in fixed longitudinal positions within said housing.

2. The device defined in claim 1 including a fluid conduit connection in the side of said elongated housing for connecting an additional fluid conduit laterally into said housing.

3. The device defined in claim 2 wherein said side connection is located intermediate the inlet end of said housing and said mixing elements.

4. The device defined in claim 1 wherein said apertures in said mixing elements are disposed at an angle of from about 30.degree. to 75.degree. from the center longitudinal axis.

5. The device defined in claim 1 wherein said apertures in said mixing elements are substantially uniformly disposed in said elements.

6. The device defined in claim 1 wherein the apertures in adjacent mixing elements are angularly displaced in opposite directions to cause a reversal in the rotational direction of flow of fluids passing therethrough.

7. A fluid mixing device for installation in a fluid-carrying conduit, which comprises:

an elongated tubular housing having an inlet end and an outlet end;

connecting means at either end of said housing for fluid-tightly connecting the device to a fluid conduit;

a fluid conduit connection in the side of said elongated housing for connecting an additional fluid conduit laterally into said housing;

a plurality of apertured mixing elements positioned in longitudinally spaced relationship within said housing, each of said mixing elements comprising a solid cylinder adopted to fit within said housing and having a length from about one-fourth of its diameter to about equal to its diameter, said cylinder having a plurality of uniformly disposed longitudinal apertures extending the length thereof, said apertures being disposed at an angle of from about 30.degree. to about 75.degree. from the center longitudinal axis; and

means for maintaining said mixing elements in fixed longitudinal positions within said housing.

8. The device defined in claim 7 wherein the apertures in adjacent mixing elements are angularly displaced in opposite directions to cause a reversal in the rotational direction of flow of the fluids passing therethrough.

9. The device defined in claim 8 wherein each of said mixing elements are of a length equal to about one-half of their diameter and wherein said apertures are disposed at an angle of about 45.degree. from the center longitudinal axis.

10. A fluid mixing device for installation in a fluid-carrying conduit, which comprises:

an elongated tubular housing having an inlet end and an outlet end;

connecting means at either end of said housing for fluid-tightly connecting the device to a fluid conduit;

a fluid conduit connection in the side of said elongated housing for connecting an additional fluid conduit laterally into said housing;

a plurality of apertured mixing elements positioned in longitudinally spaced relationship within said housing, each of said mixing elements comprising a solid cylinder adapted to fit within said housing and having a length equal to about one-half of its diameter, and having a plurality of longitudinal apertures, extending the length of said cylinders, said apertures being uniformly disposed at an angle of about 45.degree. from the center longitudinal axis, and the apertures in adjacent mixing elements being angularly displaced in opposite directions to cause a reversal in the direction of rotation of the fluids flowing therethrough; and

tubular spacers adapted to fit within said housing and placed between said mixing elements to maintain said elements spaced apart in said housing.