US2293183A - Mixing turbine - Google Patents

Description

g- 8,; 9 .1; D. WALKER 2,293,133

' MIXING TURBINE Filed April 5, 1939 3 Sheets-Sheet 1 Aug. 18, 1942. J. DIWALKER MIXING TURBINE 3 Sheets-Sheet 2 Filed April 5, 1939 Patented Aug. 18, 1942 'UNITED STATES PATENT OFFICE 2,293. 8; MIXING TURBINE James nvvum, Aurora, m, m to m Amerlcan'Well Works, Aurora. III. a corporation of Illinois Application April a, 1939, Serial No. new forum. (Cl. 261-93) This invention relates to mixing turbines and has for its principal object to provide a simple and eilicient device for mixing chemicals or gas with liquor; and, generally speaking, that object is attained by combining a suitable impeller into minute particles and diffuses them evenly through the liquor.

Further objects and advantages of the invention will appear as the descriptionis read in connection with the accompanying drawings ilius trating the preferred embodiment of the invention, and, in which Fig. 1 is a vertical section through a mixing well, equipped with a mixing turbine;

Figs. 2 and 3 are transverse sections taken on the lines 2-2 and 3-3 of Fig. 1;

Fig. 4 is a transverse section of a blade of the impeller taken on the line 4-4 of Fig. 3;

Fig. 5 is a sectional view through the delivery end of one of the air tubes;

Fig. 6 is an outside elevation of the corresponding end of that air tube;

Fig. 7 is a sectional view taken on the line 1-4 of Fig. 1;

Fig. 8 is a transverse section of one arm of the diffuser taken on the line 8-4 of Fig. 7;

' Fig. 9 is a plan view of a modified form of mixing well equipped with a mixing turbine; and

Fig. 10 is a vertical sectional view through the mixing well shown in Fig. 9.

But these specific illustrations and the corresponding description are intended for the purpose of disclosure only and are not to be interpleted as placing unnecessary limitations on the claims.

In Fig. 1, It indicates the wall of a mixing well having an outlet II at one side above an inlet I! at the other side. Across the top of the well is a bridge I: uponwhich the turbine is carried. The turbine unit or apparatus includes a base l4 carrying the driving motor I! having a shaft l6 connected with impeller shaft II by a coupling II. .The bottom of the base I4 is equipped with a broad flange is below which is a tubular nipple II for connection with a hollow column II that depends into the well and carries the suspended mechanism.

The lower end of the column 2! telescopes over ing head 23 provided with four inlet openings 24 defined by its outer wall 25 and spokes or arms II.

A cylindrical casing 21 is flanged to the head at 28 and is equipped with a discharge bell 28 directly or through the intermediary of a downdraft tube 3. according to the conditions. In all cases where a downdraft tube will improve the y r ulics, it will be used, otherwise it will be omitted.

The casing is braced to the wall of the well by guys ll, the number and nature of which will depend upon the conditions.

The impeller shaft l'l extends through a hearing sleeve 32 in the casing head 22 and is journailed in ball-bearings I3 concentric with the casing 11. Just below the ball bearings the shaft is equipped with an impeller 34 which may vary in construction but preferably has vanes. 35 (Fig. 3), the leading edges 38 of which recede from corresponding radii 31 in order to make the impeller self-cleaning. This is especially important where the liquor is to be circulated and dicated in Fig. 8; the exact shape will depend upon the hydraulic conditions for the difluser serves to straighten out the flow of the liquor, and thus has to be designed in appropriate relation to the impeller.

As will be seen from Fig. 1, the liquor 40 is ordinarily level above the head of the casing 22, thus placing the liquor inlets 24 below the surface. When the impeller is in operation, it produces what is technically known as cavita tion in an area above that varies with the speed and the design and other conditions into this cavitation there is placed one or more air pipes 4| supported on brackets 42 and having their lower ends flattened and curved inwardly, as shown at 43 in Figs. 5 and 6. The upper ends of the pipes 4| are equipped with valves 44 here shown as of the familiar conical type having an elongated passage 45 that may be adjusted by rotating the conical body of the valve.

and is secured to a cylindrical boss 22 on a case In operation the impeller is driven by the motor l5 and sets the liquor in circulation through the casing 21 entering at the inlets 24 and leaving through the outlet or discharge bell 29. The'action of the impeller produces a cavitation above it and the tubes 4| deliver to that cavitation. When it is desired to add air or gas, such as CO2, or chlorine, or such other fluid as it may be desired to mix with the liquor 40, suitable connections are made and the valves 44, or one of them, adjusted to make the feed suited to the conditions. In the case of air, for example, the atmospheric pressure will supply air through the tubes 4| to vent the cavitation and thus deliver it into the liquor just above the impeller which will promptly break it up into very minute particles and disperse it uniformly throughout the stream of liquor passing from the impeller.

While the size, proportions and arrangements will necessarily be a matter of selection and design according to the conditions, the following will indicate satisfactory specifications. A casing 21, twelve inches inside diameter; air pipes 4|, one and one-half inches in diameter; and terminating about three inches from the top of the impeller. Other parts are in proportion. These specifications, however, are not intended to suggest limits. Where the speed and design of the impeller, for example, produces a high cavitation, the ends of the air tubes can be raised accordingly without materially altering the operation.

The scheme of operation is to be distinguished from prior devices which cause a high head loss and require a great deal of power to operate, the feed of the air or such like being made by just venting the cavitation formed by the vortex. No appreciable head loss should be necessary, and, therefore, no corresponding increase of power is required, even when air is fed up to one-fourth the capacity of the unit.

Of course, the turbine can be used for a great many mixing and agitating purposes when the air valves are entirely closed. It can be used for aeration and scrubbing alone, for violent agitation and mixing alone, or for a combination of both aeration and mixing. A tremendous amount of circulation per horsepower load is effected because of the low pumping head; and, if desired, the unit can pump or lift the liquor a foot or so.

The turbine can also be used to great advantage in a system where it is desired to have the efl'luent from a mixing well or the like discharged at a slightly higher level than the influent. This is illustrated in Figs. 9 and 10, Sheet 3, Where the well is indicated generally by 50 with the infiuent at 5! and the eflluent at 52, and in Fig. it will be seenthat the latter is at a somewhat higher level than the former.

The influent and eiiluent are separated by what amounts to an influent chamber, defined generally by a wall 53 (Fig. 9) and a bottom 54 (Fig. 10). The wall 53 has a curved portion 55 extending downwardly from the bridge 56 upon which the turbine unit is mounted. The bottom 54 has an opening 51 through which the casing 2! extends into the main body of the well 50.

This arrangement is largely diagrammatical but is sufficient to indicate how the turbine can be used to do all the mixing, etc., heretofore described and also to raise the effluent to a somewhat higher level and still keep the power of consumption well down.

When the influent is less than the capacity of the turbine it is well to provide means to prevent the latter from pumping air. In this instance that result is accomplished by putting a recirculation gate 58 in the curved wall 55 and controlling it with suitable apparatus indicated at 59. By opening the recirculation gate, a suitable amount of flow through the turbine can be kept up to capacity by more or less recirculation determined by the amount of the influent and the opening of the gate.

I claim:

1. In a mixing turbine, a tubular support member, a shaft rotating within the support member, an impeller on the shaft, a casing surrounding the impeller and including an inlet head carrying the casing and carried by the support mem- .ber; said impeller being positioned close to said head and said head being substantially open to offer a minimum resistance to the flow of the liquor therethrough to the impeller; and a tube having an inlet exposed to the atmosphere and an outlet positioned to be in the liquor flowing to the impeller on the suction side of the impeller. and so close to the impeller as to cause the pressure to be rendered sub-atmospheric solely by direct action of the impeller.

2. Apparatus for pumping liquor supplied substantially continuously and mixing air therewith, including an inflow chamber to which the liquor is initially supplied, an outflow chamber, a mixing turbine therebetween including an impeller and adapted to draw liquor from'the inflow chamber and discharge it into the outflow chamber with sufficient force to raise the level in the outflow chamber higher than the level in the inflow chamber, an air tube open to the atmosphere at one end and delivering within the liquor on the suction side of the turbine and close enough to the impeller to be subjected to the direct suction thereof, and means for permitting a regulated gravitational flow from the outflow chamber back to the inflow chamber to cause a re-circulation of the liquor.

3. Apparatus for pumping liquor supplied substantially continuously and for aerating the same, including an inflow chamber to which the liquor is initially supplied, an outflow chamber, a mixing turbine therebetween including an impeller and drawing liquor from the inflow chamber and expelling it in the outflow chamber with sufiicient force to raise the level in the outflow chamber above that in the inflow chamber, and an open passage between the outflow chamber, and the inflow chamber through which liquor will flow back from the outflow chamber to the inflow chamber under influence of the difference in levels in the two chambers, and means associated with the mixing turbine and rendered effective thereby for introducing air into the liquor on the inflow side of the turbine substantially as it enters the turbine.

4. In a mixing turbine, a tubular support member, a power-driven shaft rotating within the support member and journaled near the bottom thereof, an axial flow impeller on the shaft adjacent the bottom of the support member, adapted to move large volumes of liquor efliciently and uniformly but positioned sufficiently deep in the liquor to prevent the formation of a vortex, and air flow conduit means having an inlet open to the atmosphere, and outlets substantially spaced from the support member and the shaft, symmetrically disposed about the shaft, opening directly into the main stream of liquor flowing toward the impeller, positioned close enough to the impeller on the suction side thereof so that air will be drawn from the outlet by the suction of the impeller producing the main flow of liquor, and each having a sumciently small and localized cross section so that the stream of air flowing therefrom will be entrained within the main stream of liquor with substantial uniformity as to point of entrainment and drawn with it substantially uniformly to the impeller while substantially surrounded by liquor and separated by the liquor from the other air streams and while being kept away from the support member and shaft.

5. In a mixing turbine, a tubular support member, a power-driven shaft rotating within the support member and journaled near the bottom thereof, an axial flow impeller on the shaft adjacent the bottom of the support member, adapted to move large volumes of liquor efficiently and uniformly but positioned sufliciently deep in the liquor to prevent the formation of a vortex, a casing surrounding the impeller, having an outlet on the discharge side of the impeller, and an outwardly flaring inlet on the suction side of the impeller, and which is substantially at least as large in diameter at all points between the inlet and the impeller as at the impeller, and air flow conduit means having an inlet open to the atmosphere and outlets substantially spaced from the support member and the shaft, symmetrically disposed about the shaft, opening directly into the main stream of liquor flowing toward the impeller, positioned close enough to the impeller on the suction side thereof so that air will be drawn from the outlets by the suction of the impeller producing the main flow of liquor, and each having a sufficiently small and localized cross section so that the stream of air flowing therefrom will be entrained within the main stream of liquor with substantial uniformity as to point of entrainment and drawn with it substantially uniformly to the impeller while substantially surrounded by liquor and separated by the liquor from the other air streams and while being kept away a from the support member and shaft.

6. In a mixing turbine, a tubular support member, a power-driven shaft rotating within the support member and iournaled near the bottom thereof, an axial flow impeller on the shaft adjacent the bottom of the support member, adapted to move large volumes of liquor efliciently and uniformly but positioned suifle ciently deep in the liquor to prevent the formation of a vortex, a casing surrounding the impeller, having an outlet on the discharge side of the impeller, and an outwardly flaring inlet on the suction side of the impeller, and which is substantially at least as large in diameter at all points between the inlet and the impeller as at the impeller, and air flow conduit means having an inlet open to the atmosphere and outlets symmetrically disposed about the shaft, opening directly into the main stream of liquor flowing toward the impeller, positioned close enough to the impeller on the suction side thereof so that air will be drawn from the outlets by the suction of the impeller producing the main flow of liquor, and each having a sufficiently small and localized cross section so that the stream of air flowing therefrom will be entrained within the main stream of liquor with substantial uniformity as to point of entrainment and drawn with it substantially uniformly to the impeller while substantially surrounded by liquor and separated by the liquor from the other air streams.

7. In a mixing turbine, a tubular support member, a power-driven shaft rotating within the support member and joumaled near the bottom thereof, an axial flow impeller on the shaft adjacent the bottom of the support member, adapted to move large volumes of liquor efficiently and uniformly but positioned sufficiently deep in the liquor to prevent the formation of a vortex, a casing surrounding the impeller, having an outlet on the discharge side of the impeller, and an outwardly flaring inlet on the suction side of the impeller, and which is substantially at least as large in diameter at all points between the inlet and the impeller as at theimpeller, and gas flow conduit means having an inlet open to a body of gas and outlets substantially spaced from the support member and the shaft, symmetrically disposed about the shaft, opening directly into the main stream of liquor flowing toward the impeller, positioned close enough to the impeller on the suction side thereof so that gas will be drawn from the outlets by the suction of the impeller producing the main flow of liquor, and each having a sufficiently small and localized cross section so that the stream of gas flowing therefrom will be entrained within the main stream of liquor with substantial uniformity as to point of entrainment and drawn with it substantially uniformlyto the impeller while substantially surrounded by liquor and separated by the liquor from the other gas streams and while being kept away from the support member and shaft.

JAMES D. WALKER.

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