US3029069A

US3029069A - Mixer

Info

Publication number: US3029069A
Application number: US26494A
Authority: US
Inventors: William L Cummings
Original assignee: Wilevco Inc
Current assignee: Wilevco Inc
Priority date: 1960-05-03
Filing date: 1960-05-03
Publication date: 1962-04-10
Anticipated expiration: 1979-04-10

Description

W. L. CUMMINGS MIXER April 10, 1962 Filed May 3, 1960 nite States Patent MIXER am C mm n B ekl ne Mas assigner a Wilevco, Inc., Newton Center, Mass, a corporation of Massachusetts Filed May 3, 1960, Ser. No. 26,494

Z'Claims. (Cl. 2594) This invention relates to mixing devices and more particularly to a novel device especially adapted for mixing a liquid with a flowable material such as a powder, another liquid, or the like. I

Heretofore, in the art of mixing dry powders and solvent liquids, for example, the uniform mixing with a fluid with many materials has'beerr a serious problem. With many powders to be mixed with a'liquid' such as water, for example, the powder might require an appreciable time to be wet out or otherwise assimilated with the Water until it formed a uniform mixture without lumps, or the like. Until such was accomplished, the powder not only tended to stick to itself to form lumps which did not wet out readily, but also tended to stick to the walls of the mixing vessel and build up substantial deposits which tended to cause clogging and other difficulties.

As a result, many complicated mixers have been devised to cope with this situation, such as the well-known inter-rotating mechanically operated heaters, and the like. However, though such devices certainly aid the mixing process, they by no means solve the problem of build-up of sticky deposits. This is particularly so in the early stages of the mixing process before the powder or the like has been sufficiently wet out so that it still is highly sticky.

Accordingly, it is an object of the present invention to overcome these problems of the prior art by the provision of an extraordinarily effective simple mixing device which is uniquely effective in the mixing of a potentially sticky powder or the like with a liquid. Furthermore, the unique results of the present invention have been accomplished by extraordinarily uncomplicated means, entirely free of conventional beaters or similar complicated and expensive mechanical devices.

More specifically, the unique and novel mixing device of the invention utilizes for mixing the retroverted flow of a stream of liquid which first flows upwardly generally uniformly throughout an annular cross-sectioned stream and then reverses itself to flow downwardly through the center of the annular stream. The powder or other material to be mixed with the fluid stream is deposited at a desired rate by any suitable means spaced upwardly from the fluid surface generally centrally of the reversely flowing stream. The retroverted mixing stream characteristic of the invention may be created by uncompli cated structures, such as, for example, a pair of vertically arranged concentric cylinders, the inner at its upper end terminating short of the outer. Suitable means such as a pump are provided for feeding the liquid to be mixed into the annular volume between the concentric cylinders and causing its upward flow therebetween so that it overflows the top of the inner cylinder and fiows radially inwardly and then downwardly therethrough together with the powder or other material to be mixed therewith which is deposited at a predetermined rate generally centrally of the inner cylinder. With such a structure, with the inner cylinder entirely covered by a flowing stream of liquid, the powder to be mixed never touches any wall of the mixing device until sufficient time has elapsed for it to be wet out beyond the sticky state. The powder dispenser, being spaced above the liquid surface, is not affected thereby to cause powder to stick to it. A suitable length for the inner cylinder allows sufficient time for the wetting out of a given powder.

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Reference is now made to the following detailed descri'ptiori'of a preferred embodiment of the inven ti'on, to-

gether with the accompanying drawings','wherein:

FIG. 1 is'a vertical cross-section of the novel mixing device of the invention, and

FIG. 2' is a cross-section of the mixing device of FIG. 1 taken on the line 22 thereof.

As will be apparent from the drawings, the novel mixing device of the invention may consist of a'vertically arranged outer cylinder 12 and a concentric inner cylinder 14 forming an annular volume 16 therebetweenanda cylindricalvolurne 18 within the inner' cylinder. The top edge 20 of the inner cylinder terminates short of the top edge 22 of the outer cylinder. A radial b'ottomwall 24 connects the twocyliiidersat the lower edge of the outer cylinder. A liquid inlet in theforr'n of a pipe 26 is provided adjacent the bottom wall'24, and a pump 28 is connected thereto for supplying liquid at a suitable predetermined rate. The inner cylinder 14 extends through the bottom wall 24 and is of any suitable length for accomplishing the desired wetting-out of a specific powder to be mixed with the liquid. The mixture may thereafter be piped or otherwise directed to a reservoir, or the like (not shown).

For depositing the powder or the like at a predetermined rate generally centrally of and preferably within the extent of inner cylinder 14, suitable means are provided positioned thereabove, well above the liquid surface. For example, a hopper 30 having a distributor impeller 32 rotatably mounted in the bottom opening thereof and driven by any suitable means, not shown, may be used. Other devices, such as vibrator operated means, or suitable orifices if another liquid is to be mixed with that fed into the mixing device of the invention, may also be used as appropriate.

In operation, as has been described hereabove, a retroverted flow of liquid is provided by pump 28 or otherwise at a predetermined rate upwardly through the annular volume 16, to overfiow the top edge 20 of inner cylinder 14 and then downwardly through the cylindrical volume of inner cylinder 14. Because of the radially inward flow of the liquid for a substantial depth over edge 20, as at 20a, particles 34 of the powder or other material to be mixed with the liquid provided at a predetermined rate from hopper 30 upon the area adjacent the upper edge of the inner cylinder, particularly if the powder particles tend to float, are carried away from both of the cylinders in a direction toward their common axis, as shown. Thus, sticky wet powder particles cannot reach and stick to any part of the mixing device of the invention, but rather are kept in the center of the downwardly flowing stream within inner cylinder 14 until they have suflicient opportunity to be thoroughly wet out and uniformly mixed with the liquid free of lumps, or the like, to provide a mixture of predetermined ratio.

It will be apparent to those skilled in this art that there may exist various modifications thereof within the spirit of the invention and the scope of the appended claims.

I claim:

1. A liquid mixer comprising a vertically arranged outer tubular member and an inner tubular member having walls spaced inwardly from said outer tubular member and having its upper edge terminating short of the upper edge of said outer tubular member with a lower wall portion connecting said inner and outer tubular members, means for establishing a retroverted liquid stream having an upwardly flowing portion of annular section through the annular volume between said inner and outer members and a downwardly flowing portion of tubular section within said inner member, with said portions connected by a radially inwardly flowing portion passing over the periphery of the upper edge of said inner member and defining an annular liquid surface within said outer tubular member, including means for feeding liquid into the volume between said inner and outer members and means for removing liquid from the lower end of said inner tubular member below said lower wall, and means spaced above said inner member upper edge and said liquid surface for depositing a material to be mixed with said liquid upon the area adjacent the upper edge of said inner tubular member.

2. A liquid mixer comprising a vertically arranged outer tubular member, an inner tubular member, said inner tubular member being substantially coextensive with and positioned within said outer tubular member, said inner tubular member having walls spaced inwardly from said outer tubular member and having its upper edge terminating short of the upper edge of said outer tubular member, a wall connecting said inner and outer tubular members, means for establishing a retroverted liquid stream having an upwardly flowing portion between walls of said inner and outer members and a downwardly flowing portion of tubular section within said inner member, with said portions connected by an inwardly flowing portion passing over a major portion of the periphery of the upper edge of said inner member and defining a liquid surface Within said outer tubular member, including means for feeding liquid into the volume between said inner and outer members and means for removing liquid from the lower end of said inner tubular member, and means spaced above said inner member upper edge and said liquid surface for depositing a material to be mixed with said liquid upon the area adjacent the upper edge of said inner tubular member.

References Cited in the file of this patent UNITED STATES PATENTS Revallier Nov. 22, 1955 Caldwell et a1. May 5, 1959