US2042006A - Apparatus for treating liquids - Google Patents

Description

May 26, 1936. w. H. JACKSON APPARATUS FOR TREATING LIQUIDS Filed Jan. 21, 1953 W IN'VEWR i e 5 fl'w ATTORNEY Patented May 26, 1936 UNl-TED STATES PATENT 6 Claims.

This invention relates to the treatment of liquids, being especially adapted to accomplish the effective mixing or agitating of the contents of a tank containing a liquid or liquids or a mixture of liquids with a solid, which is either soluble or suspensible therein, as well as for the purpose of accomplishing the efficient heat-exchange between two liquids or the washing of solids with a liquid, besides having other advantages as herein- 10 after set forth.

The principal objects of the invention are the provision of a tank, equipped with propelling mechanism that is adapted by virtue of its unique contour to cause particles of the liquid or solids contained therein to gravitate towards the propelling means and which will effect a vigorous and efiicient agitative treatment throughout the entire volume of the contents of the tank, such tank being free from baiiles, vanes, dead spots or 29 pockets for the lodgment of stagnant materials or sediments.

Among the further objects of the invention is the provision of a tank that can be readily cleansed with a minimum amount of labor or cleansing material being required therefor and which tank can be fabricated from a minimum number of thin metal sheets, substantially all of which are of uniform thickness and the contour of which tank provides a sturdy offset mounting 30 for a propeller shaft which admits of the propeller blades being located at or near the center of the tank, thus avoiding the necessity for a long overhanging shaft and an independent bearing therefor, besides permitting of the driving motor of such propeller being partially housed, externally of the tank, within such mounting portion with a, consequent reduction in the floor space required for the apparatus below that now prevailing in the case of other mixing tanks. Furthermore, such mounting portion serves to automatically correct the direction of flow of undesirable currents within the tank.

, Heretcfore, as I am aware, it has been proposed to provide a type of tank of what might be termed truncated spherical contour (see British Patent No. 21,912 of Dec. 3, 1900), the said tank being equipped with a propeller mounted on a horizontal shaft projecting through the bottom of the tank and the blades of said propeller being positioned in an aperture in a vertical foraminous partition extending upwardly through the tank and inwhich tank the particles of material are agitated so as to travel in substantially concentric paths. Another type of tank is disclosed in Patent No. 1,542,034, which tank is of general cylindrical contour and in which the contents are adapted to be agitated by means of a propeller mounted centrally on the tank on a vertical shaft and in such construction the particles of material are also adapted to travel in substantially con- 5 centric horizontal paths. Again, as disclosed in Patent No. 1,399,699, it has been proposed to provide a standard bottom head, the radius of which is substantially'equal to the tank diameter and the same being equipped with a propeller mounted 10 in close proximity to the vertical side walls of the tank. Still another type of tank, namely one with a, conical bottom head, as distinguished from the essentially spherical or fiat heads disclosed in the foregoing patents, is shown in Patent No. 15 1,430,729, such tank being provided with a propeller, the blades of which arein close proximity to the bottom walls. In this construction, due to the obstruction afforded by the downwardly converging conical bottom walls, the particles of liq- 20 uid entering the zone of the blades will be deflected downwardly from the blades substantially perpendicular to the shaft, with the consequence that there is an abrupt, substantially right-angle change of direction required to be made before 25 the currents commence to ascend. In none of these constructions, however, is the tank so designed as to afford unobstructed entrance for the circulating particles to the influence of the propeller blades, as well as being free from objectlonable obstructions or abrupt changes of direction of the bottom and adjacent walls so as to be capable of effecting the propelling of liquids within the tank with a minimum loss of velocity, while at the same time preventing the particles from 35 travelling in circles and essentially in their own individual atmospheres, i. e. essentially in the region of the fluid which is in immediate proximity to such particles such as would be the case were they to flow in essentially circular paths. Furthermore, the aforesaid disclosures of the prior art do not possess the other advantages of my improved construction as herein described.

In .the accompanying drawing, I have illustrated a preferred form of my improved appara- 5 tus and in which my improved process is adapted to be carried out. Referring to this drawing Figure 1 is a vertical section, partially in olevation, showing my improved apparatus;

Fig. 2 is a diagrammatic view showing by 50 means of contour lines the shape of the indented mounting portion and adjacent tank walls;

Fig. 3 is a fragmentary side elevation serving to show the contour of the indented mounting portion; and 5 Fig. 4 is a fragmentary sectional view partly in elevation of a modified form of apparatus, in which the mounting portion is substantially arcuate in vertical section in two different planes at right angles to each other.

Referring to the drawing and the construction shown therein, (see Figs. 1-3), the reference numeral I designates the body or waist portion proper of a tank and 2 the bottom head thereof, said tank being provided withan open top that is adapted to receive a cover (not shown). Said tank is provided with an outlet 3 controlled by a valve cock 4. The said bottom head has an external cavity or detent a which is formed by striking up a sheet so as to form the walls of said cavity integral with the bottom head, or the walls of said cavity may comprise separate sheets secured to the bottom head and to each other at their respective adjacent edges.

The reference numeral 5 designates one wall of said cavity, the same being of general clam shell-like contour, as illustrated by the contour lines A, B, C, D, E, F and G (Fig. 2) said lines being in the planes indicated by the corresponding letters in Fig. l.' The other wall 6 of said cavity is of substantially U-shaped configuration (see Fig. 3), the lower edge thereof being either integral with the bottom head 2 of the tank or welded or otherwise secured thereto. This latter wall serves as a support for the propelling unit comprising a shaft 1 which projects through said wall, a conical housing shell or shaft support 8, which is rigidly secured to said wall 6, a propeller element 9, a motor III, the shaft ll of which is connected to said shaft 1, and a spider or supporting frame I2 for said motor II).

By employing a bottom head of arcuate shape conforming to segment of a hollow sphere, whose radius is between 50% and 60% of the diameter of the waist of the tank and desirably between 50% and 53% of such diameter, it is possible to construct a self-sustaining bottom with less material than required for other types of bottoms and furthermore, such a head will have an angular curvature especially if it does not exceed about 53% of the diameter of the waist of the tank as above noted, which will merge quite gradually, as distinguished from abruptly with the bottom edge of the cylindrical waist of the tank.

In the construction shown in Fig. 4, the cavity a constitutes a depression conforming substantially in configuration to a segment of a, sphere, such a cavity being more expedient to form by a stamping operation and affording a more natural mounting for the circular base for the shaft support 8' which will have a natural fit therewith.

In operating the foregoing apparatus, as a liquid mixer, the propeller, upon rotation thereof, will cause currents of liquid to move across the concave bottom of the tank in paths substantially concentric therewith and during such movement, due to the combined force of gravity and the centrifugal force exerted thereon, the liquid particles in such currents will be caused to rub out or pound their atmosphere against the bottom of the tank, following which they are gradually deflected without the velocity of flow thereof being substantially retarded by any interposed partitions or obstructions within the tank, and then move upwardly along one of the side walls of the tank to a point in proximity to the normal liquid level of the tank. Thence the particles of liquid in the currents, under the urge of gravity, will tumble downwardly in a sloping direction toward the opposite side of the tank and again enter the propeller when the cycle of movements will be repeated. As a consequence of such movement,

any tendency for the propelling element to create and for the tank to sustain vortices within the 5 body of the liquid, will be substantially repeatedly dampened and consequently the currents created by the propelling element will, upon re-entry into the tank, be substantially without rotary motion on the axes and thereby an efficient and controlled mixing of the contained particles of the liquid is accomplished. During the upward passage of the current on one side of the tank and the downwardly movement of the same along the other side of the tank, the two oppositely moving zones of liquid will have their adjacent particles brought into frictional contact which will cause a vigorous mixing or attrition therebetween and will further disrupt the immediate atmosphere around them. The importance of high velocity, or technically, high momentum of the particles is of particular value in the treatment of viscous liquid, since as the viscosity increases, there will be a corresponding increase in the skin-friction between the liquid and any partitions or obstructions within a" tank provided therewith, and consequently 'when a certain degree of the viscosity is obtained, such bailies or obstructions, if present in a tank, would cause almost a complete cessation of flow. of the liquid. 3 For example, in dissolving sugar, it has been found to be almost as difficult in ordinary mixing apparatus, to effect the incorporation of the last five percent of the sugar crystals into the solution as to incorporate the entire 95% balance 35 thereinto.

It is of the utmost importance that the propeller blades be positioned well out to the side of the bottom head and in proximity to the center of such head in order that the area of ad- 40 mission of the liquid to the blades will be substantially greater than that of the projected area of the propeller itself, this factor being of greater importance in the case of small propellers than in the case of large ones. For example, for mod- 45 erate size tanks, up to say 2 ft. in diameter, the v central zone comprising one-fifth of the tank diameter is a desirable location for the propeller, while in tanks of 4 ft. in diameter and upwards, the central comprising one-third of the diam- 50 eter of the tank will give satisfactory results, if the propeller is located therein. Furthermore, the lowest point of the propeller blades should be as close to the bottom of the tank in their travel as possible while permitting of the free clearance 55 by the propeller blades of the largest solid particles obtained within the liquid when the same are resting on the bottom head.

It is preferable that the propeller shaft extend at a slight angle, about 10 to 20 with respect to 69 the horizontal; except in the case of very small units, as any increase in inclination above this angle tends to increase the tendency for rotary currents to form without any increase in benefit therefrom. Furthermore, such an angular po- 65 sition of the shaft tends to prevent the spray thrown from a partially submerged propeller from being projected through the top of an open tank, and also such angular position of the shaft permits of the propeller shaft being efi'ectively 70 shortened and of the employment of a propeller of larger diameter. Also such inclination of the shaft tends to increase the agitation of the upper portion of the liquid where normally, due to its remoteness from the propeller, such agitation would be at a minimum. Moreover the angle of mounting of a propeller shaft, such as above specified, permits of the motor being more completely shrouded within its housing without correspondingly increasing the size of the external cavity in the tank.

If desired, the entire tank can be jacketed with a steam jacket or suitable heating coils can be provided for heating the same and furthermore, suitable strainers can be temporariLv inserted within the tank during the preliminary solution of solids in the liquids contained in such tanks in order to prevent the impurities contained in the solids contaminating the contents of the tank. For example, a small basket strainer can be positioned at the bottom of the waist of the tank adjacent the top wall of the external cavity, or a large strainer basket, slightly smaller in diameter than the diameter of the waist of the tank and substantially the height of such waist, can be suitably supported within the tank and'preferably the bottom of such strainer basket is provided with an aperture slightly larger than the diameter of the propeller and a pipe is supported in such aperture which projects upwardly through the strainer to a portion adjacent the top thereof and projects below the bottom of the strainer in an arcuate curve to a point in proximity to the nose of the propeller. Preferably the upper portion of the pipe, which extends vertically above the bottom of the strainer is of perforate metal and the elbow below the bottom, is formed of imperforate metal. Such a strainer will effect repeated circulation of the liquid through the elbow up through the perforated pipe, thence into the basket, through the sides thereof and back to the propeller and is to be removed after complete solution of the solids which it is desired to dissolve in the liquid has occurred. If desired, a relatively small basket strainer of substantially cup shape and slightly larger than the propeller hub can be fitted over and secured to the nose of the hub, so that upon rotation of the propeller, a large portion of the liquid will traverse such strainer and serve to deposit therein any nails or other tramp particles contained in the liquid.

Various changes within the scope of the appended claims may be made without departing from the spirit of my invention.

Having thus described my invention, what I claim and desire to obtain by United States Patent is:

1. In an agitating apparatus, the combination comprising a tank having a substantially cylindrical waist portion, a bottom portion of substantially arcuate cross-section, the radius of such are being from to 60% of the diameter of the waist portion of the tank and said bottom portion being indented laterally thereof to form a support which extends, in proximity to the center of the bottom of the tank. for a propeller shaft and also to form a partial housing externally thereof for a motor, an electric motor mounted on said tank bottom externally thereof and partially housed within said indented portion of said tank, a propeller shaft operatively connected to said motor and projecting through such support and a propeller carried on the free end of said shaft and disposed in proximity to the center of the tank adjacent the bottom thereof.

2. In an agitating apparatus, the combination comprising a tank having at waist portion and a bottom portion, the latter being curvilinear in cross-section and having an internally dished indentation forming a clam shell-like protuberance on one side of said bottom portion which is adapted to serve as asupport for a propeller shaft and a partial housing externally of said bottom portion for an electric motor, a propeller shaft projecting through said protuberance, a propeller mounted on the inner end of said shaft, a motor connected to the other end of said shaft and partially housed within said housing, said tank being free from intermediate obstructions and bearings intermediate said propeller and the innermost portion of said protuberance.

3. In an agitating apparatus, the combination comprising a tank having a. waist portion and a bottom portion, the waist portion being substantially cylindrical and the bottom head substantially conforming to a segment of a hollow sphere of a radius of 50% to of the diameter of the waist portion, said bottom portion having one side thereof dished inwardly to form a clam shell-like protuberance within the tank and an external recess, a propeller shaft mount- ,ed on said protuberance and extending at an angle to the horizontal, a propeller carried on the inner end of said shaft and disposed in the central zone of said bottom portion and an electric motor secured to the opposite end of said shaft.

4. An agitating apparatuscomprising, in combination, a tank having a cylindrical waist portion and an internally concave bottom of substantially spherical contour; an inwardly dished indentation formed in one side of the curved bottom to provide a shaft support; a shaft bearing mounted in the innermost wall of said indentation and projecting into the tank; a propeller shaft extending through said bearing; and a propeller mounted on the inner end of said shaft and disposed in proximity to the axis of the tank djacent to the bottom thereof.

5. An agitating device of the character described comprising, in combination, a cylindrical tank having a concave bottom of spherical contour: a shaft bearing mounted in said bottom portion at one side of the tank and extending upwardly at an inclination into the tank: a shaft in the bearing terminating in proximity to the axis of the tank; an agitating propeller on the end of the shaft; and a motor supported by the tank connected to drive the propeller.

6. An agitating device of the character described comprising, in combination, a cylindrical tank having a concave bottom of spherical contour; a shaft extending through the curved bottom at one side of the tank and projecting upwardly at an inclination to the horizontal therein, terminating in proximity to the axis of the tank connected to the outer end of said shaft.

WILLIAM H. JACKSON.

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