US3496881A - Variable delivery jet agitator - Google Patents

Description

Feb. 24, 1970 s. BYLSMA 4 3,496,881

VARIABLE DELIVERY JET AGITATOR Filed April 18, 1968 3 Sheets-Sheet 2 VARIABLE DELIVERY' JET AGITATOR Fned'Aprizl 1a, wssv s sheets-sheet s Milli Z-*ZZ/Q'nor.' Simon tylsfma 3,496,881 VARIABLE DELIVERY JET AGITATOR Simon Bylsma, Des Moines, Iowa, assignor to Deiavan Manufacturing Company, a corporation of Iowa Filed Apr. 18, 1968, Ser. No. 722,371 Int. Ci. Ftdf /10, 5/52 U.S. Cl. S-262 8 Claims ABSTRACT OF THE DISCLOSURE A venturi type of variable delivery jet agitator for mixing liquids and li quid-solid mixtures. The jet agitator comprises a valve housing communicating with a source of pressurized fiuid, a valve outlet port for discharging said fluid, an adjustable biasing means seated within said housing, a valve member attached to said biasing means and urge'd by said biasing means to normally close said outlet port and to open said valve at a predetermined pressure in said fiuid, a venturi device having a throat end and a discharge end attached to the exterior of the valve housing and communicating with said outlet port of said valve housing at said throat end, an opening on said venturi device at the throat end whereby when pressurized fluid causes the valve to open, the pressurized discharge creates a low pressure area about the throat of the venturi to cause fluid outside the venturi to enter the opening.

This invention relates to mixing apparatus for liquids and liquid-solid mixtures. More particularly, the present invention relates to a variable delivery jet agitator for agitating and mixing liquids and liquid-solid mixtures.

In many instances, it is desired to thoroughly mix liquids or liquid-solid mixtures. A particularly important example of the need for substantially uniform mixtures of liquid-solid combinations is in the agricultural field where herbicides, insecticides, etc., are extensively used. The large bulk of liquid-solid mixtures to be handled and the large areas to be covered in agricultural applications make spraying the most practical and economical method of spreading the mixtures. The effectiveness of such a spraying operation would depend to a large extent on the uniformity of the mixture sprayed. In agricultural operations, frequently the chemicals to be used are in the form of wettable powders which do not usually go into complete solution. Such chemicals are then sprayed as slurries or suspensions of solids in liquids. In such a situation, it is important to agitate the solid-liquid mixture constantly to prevent the solid particles from precipitating or settling to the bottom of the container or supply tank. The agitation must be sufiicient to maintain a substantially homogeneous distribution throughout the supply tank to assure uniformity in composition of the materials withdrawn from the tank over a given period of time.

In applying agricultural chemicals by spraying, the agitation necessary to maintain a substantially homogeneous distribution of materials within the supply tank is usually obtained by returning a portion of the solution pumped out of the supply tank through an agitator. A variety of agitating devices are available for this purpose. The present invention is concerned with the so-called jet agitators, which do not depend on the movement of parts of the agitating device for the mixing action desired.

Several different design for jet agitators are known. Thus, U.S. Patent 2,692,798 discloses a jet agitator having a spring loaded release valve design. However, the discharge from such a device could not be directed `for optimum placement to achieve the maximum stirring effect in the container. The design also has the disadvantage in that it cannot be combined with a venturi-type of mixer to obtain the benefits of the venturi mixing effect because Cil 3,496,881 Patented Feb. 24, 1970 the previously known forms of venturi tubes required that they be activated by a round and concentric axially directed jet for their operation.

Another known form of jet agitator design is disclosed in U.S. Patent 3,166,020. In this design, a stream of the returning solution is passed through a venturi mixer nozzle which has a fixed orifice to restrict the discharge through the orifice to produce a pressurized discharge therefrom. The disadvantages associated with such a fixed orifice venturi-type mixer can be understood from the following considerations.

The energy or momentum available for agitation purpose is not proportional to mass fiow rate alone but is the product of mass and velocity. The velocity of a liquid discharged through an orifice is approximately expressed by the equation:

wherein V is the velocity in feet per second, G is the local acceleration of gravity in feet per second squared, and H is the pressure head in feet. Thus, optimum agitation is obtained with maximum conversion to momentum of available mass flow rate and pressure. For reasons of economy, a single pump is commonly used for delivering both the agricultural spray and the recycled portion used to obtain the mixing effect. Usually, such a pump is of a size sufficient to deliver just enough excess liquid for recycling purpose. Since the available amount of liquid iiow is thus limited by the capacity of the pump, the momentum available for agitation purposes is to a large extent dependent on the maintenance of optimum pressure for conversion to momentum.

In view of the above, it can be seen that the fixed orifice type of venturi mixer nozzle, as that disclosed in U.S. Patent 3,166,020, has a number of disadvantages. First, such a fixed orifice cannot respond to iiuctuating line pressure to maintain optimum pressure for mixing purposes. Thus, the fixed orifice may be slightly too large to maintain optimum pressure at a particular time and the resulting drop in pressure reduces drastically the amount of energy available for agitation. Although the orifice of such a venturi mixer can be changed to introduce a different sized orifice, such a change requires the taking apart of the venturi device and the availability of a number of orifice plates having different diameters. Aside from the inconvenience and expenditures involved in physically changing the orifice plate, such a process is not satisfactory since a change of the orifice plate must necessarily result in a step-wise change in size and cannot insure optimum pressure for agitation of the liquid.

It is, therefore, an object of the present invention to provide an improved jet agitator.

It is another object of this invention to provide a variable delivery jet agitator which is adaptable to variations in line pressures to obtain optimum performance.

It is still another object of' the invention to provide a venturi-type variable delivery jet agitator having adjustable valve outlet ports with a configuration corresponding to the shape of the venturi throat to provide optimum agitation with maximum conversion to momentum of available mass flow rate and pressure.

Further objects of the present invention will be clear to a person skilled in the art from a reading of the following description.

In accordance with the foregoing objects, a variable delivery jet agitator is provided which is responsive to variations in the line pressure to produce maximum energy for agitation and at the same time to take advantage of the mixing and flow increasing effects of a venturi type of mixer. The improved jet agitator of the present invention is illustrated in a specific embodiment in the accompanying drawings, in which:

FIGURE 1 is a schematic view of a typical spraying system employing the jet agitator of the present invention;

FIGURE 2 is a schematic View showing the effect of the present jet agitator on a iluid body;

FIGURE 3 is a perspective view of an embodiment of the jet agitator of the present invention;

FIGURE 4 is a sectional view, along line 4-4 of FIGURE 3;

FIGURE 5 is a bottom view of the jet agitator of FIGURE 3; and

FIGURE 6 is a section view similar to FIGURE 4 showing one method for mounting a venturi tube onto the valve housing.

In FIGURE 1, there is shown a liquid container 10, partly in section, having therein a suction strainer 12 which is connected via a suction line 11 to the inlet side of a pump 13. The suction strainer 12 is employed for the purpose of preventing large aggregates of solid materials from clogging the line and from being pumped and sprayed. The strainer is not necessary when only liquids are being mixed and sprayed. The outlet side of pump 13 is connected to a pressure line V14 which leads to a boom 17 and a plurality of spraying nozzles 18` for spraying the liquid mixture. The pressure line 14 has therein a pressure gauge 15 and a valve 16. A by-pass or balance line 20 having therein a pressure regulator 19 is connected to pressure line 14 for relieving the line of excessive pressures. An agitator line 21 is also connected to pressure line A14 for returning a portion of the iiuid being pumped to the container for the operation of jet agitator 22. Container 10 is provided with a vent 60 for communication with the atmosphere.

In FIGURE 2, the agitator line or pressure hose 21 is seen leading into the container 10l having a body of uid 23. The pressure hose 21 is connected to the jet agitator 22. Two air inlet hoses or conduits 24 leading from outside of container 10 to the jet agitator 22 are also provided. The upper openings of air inlet hoses 24 are vented to the atmosphere and the function of the air inlet hoses is more fully explained below. A number of air bubbles 25 are shown rising through the body of liquid 23 and escaping therefrom. The vent 60` allows the air to escape from the container. The motion of the liquid caused by the jet agitator is illustrated by lines 26.

Referring to FIGUR-E 3, an embodiment of the jet agitator of the present invention is shown in perspective view. The agitator line or pressure hose 21 is connected through a fastening means or iitting 31 to the agitator or valve housing 27. A valve member 28 is located on the lower end of housing 27 and is held to the housing by a biasing means to be described below. rllwo parallel vertical walls 32 abut and project downwardly from the lower end of valve housing 27 to prevent the escape of fluids from the valve housing laterally when the valve member is in opening position. Two venturi devices 29 are attached to housing 27 by a clip-on means also to be described below. The two air inlet hoses 24 are shown attached to the venturi devices and communicating with the interiors thereof through air-inlet openings 30.

FIGURE 4 is a section view along line 4-4 of FIG- URE 3 and it shows the jet agitator of the present invention in detail. As shown in FIGURE 4, the jet agitator device comprises a generally cylindrical valve housing 27 open at both ends. The upper end of valve housing 27 is internally threaded at 33 to receive a tting 31 on the end of the pressure hose 21. A spider 34 having a central opening is disposed in the housing near the lower or discharge end thereof. Spider 34 is attached to the internal wall of valve housing 27 through web members 35. A rod or stem 36 is slidably mounted in the spider opening and carries on its lower end a valve member 28. Valve member 28 is normally seated against the bottom of the valve housing 27 to shut oft flow through the valve of the agitator device. A nut 37 threaded onto the lower end of ste-m 36 secures the valve member 28 to the stem. A coil spring 38 encircles the upper end of the stem 36 and is compressed by washer 39 and nut 40, threaded onto the top of stem 36, against the top of the spider 34. Thus, the valve member 28 is normally urged by compressed spring 38 into closed position.

A venturi tube 29 is detachably mounted on one side of valve housing 27 so that the interior of the Venturi tube communicates with the outlet port 41 of the valve. Venturi tube 29 has an opening 42, on one side thereof adjacent the valve at the venturi throat 43, which communicates exteriorly of said venturi device and said valve housing. A nipple 44 extends upwardly from the venturi tube opposite the opening 42, which nipple is connected to the air inlet tube 24. Liquid or slurry and air owing through the venturi are discharged at the enlarged end `45. Venturi tube 29 has an upwardly extending arm 46 immediately adjacent the valve housing 27. Arm 46 has a slot therein for receiving lug 47 on the exterior of the valve housing, as more clearly seen in FIGURES 5 and 6. A rib 48 between arm `46 and the venturi tube reinforces the structure.

FIGURE 5 is a bottom view of the valve housing with one venturi -tube attached thereto and another venturi ready to be attached to the opposite side of the valve housing. In FIGURE 5, the valve housing 27 is shown to have a dove-tail conguration for easy clip-on engagement with the venturi devices. Housing 27 has dove-tail members 49 for sliding engagement with corresponding dove-tail members 53 on arms 46 of the venturi devices. Arm 46 has a slot 50 for receiving a lug 47 on the housing. At the opening 42 of the venturi device, the vertical side walls I51 of the venturi device curve away from each other to present a large opening towards the valve housing.

Looking at the bottom of the valve housing in FIG- URE 5, it is seen that vertical walls 32 extending from the lower end of the valve housing serve to keep the sides of valve 28 substantially closed at all times. In this manner, the discharge from the valve is directed towards the venturi devices.

It will be appreciated that although in the specic embodiment illustrated in the drawings the valve outlet port and the throat of the venturi device have a generally rectangular cross-sectional configuration, other shapes may be used for the outlet port and for the venturi throat. For example, these areas may have the shape of a crescent, a polygon or an ellipse. It is preferred, however, that the cross-section of the valve outlet port and that of the venturi throat have substanially he same con- ;iiguration so that the momentum available for agitation would not be partly wasted.

FIGURE 6 is similar to FIGURE 4 and shows one method of mounting a venturi tube onto the valve housing. A venturi tube 29 may be mounted onto housing 27 by sliding the dove-tail members 53 on arm 46 into engagement with corresponding dove-tailed members 49 on housing 27 either from the top of the valve housing or from below. When the venturi tube is mounted by sliding upwardly from the bottom of the valve housing, as shown in FIGURE 6, lug 47 is engaged into slot 50 by applying a sharp force to push member S2 of arm 46 past the inclined lower exterior surface of the lug. Although the valve housing and the venturi devices may be made of metal, such as steel, it is preferred that they be constructed of synthetic materials such as high density polyethylene or nylon. When high density polyethylene or nylon is used, the clipping-on of the venturi tube 29 is facilitated in that the synthetic materials are more yielding than metal and parts made therefrom are more easily slid into engagement.

In operation, the nut 37 on the lower end of stem 36 holding the valve 28 closed against the valve housing may be adjusted, even when the other parts of the jet agitator are in their operating position, to change the amount of pressure on the coiled spring 38. In this manner, the amount of iiuid pressure required to open the valve may be accurately adjusted to a predetermined level. Referring again to FIGURE 4, it is seen that when the fluid pressure in hose 21 exceeds the biasing force exerted by spring 38 on valve member 28, the valve would open and fluid would escape through outlet port 41 into the throat of the venturi device. At the vicinity of throat 43 of the venturi tube a low pressure area is produced by the high velocity jet escaping from the valve, in accordance with the well known Bernoulli effect. The low pressure so created at throat 43 in turn causes atmosphereic air to enter into the venturi device through nipple 44 and causes the fluid immediately outside of opening 42 to enter the venturi device. Thus, the amount of fluid fiowing through the venturi device is much greater than the amount discharged from the valve and the total mixing effect greatly magnied. By the use of a suitable means, such as a projecting lip 54, violent localized turbulence is produced, by the high velocity liquid stream which is sheared by the edge of the lip, to break up the entering air into small bubbles. The small bubbles 25 increase the effectiveness of the air in producing a stirring action and in preventing the settling of solid particles.

It will be appreciated from the above that the jet agitator of the present invention may have more or less than two valve outlet ports and two venturi devices attached thereto. Moreover, the venturi devices of the present jet agitator are constructed for easy attachment and disassembly. Since the venturi devices are easily clipped onto the housing, this may be done within the fluid container if the opening on the container is small and does not permit the assembled jet agitator to pass through. Although the efficiency of the jet agitator depends to a great extent on the use of the venturi devices, nevertheless a particular Situation may require that the venturi devices be not used and under such circumstances it can be seen that the jet issuing from valve outlet ports 41 would cause some mixing. Thus, the jet agitator of the present invention is extremely versatile.

The invention has been described in detail with particular reference to a preferred embodiment thereof, but it will be understood that variations and modifications can be effected within the spirit and scope of the invention as described hereinabove and as deiined in the appended claims.

I claim:

1. An agitator device for mixing fluids and fluid-solid mixtures comprising: a valve housing, an inlet port in said housing communicating with a source of pressurized fluid, an outlet port in said housing for discharging said pressurized uid, adjustable biasing means disposed within said housing and seated therein, a valve member attached to said biasing means for normally closing said outlet port and for opening said port responsive to a predetermined pressure in said pressurized iiuid, and a venturi device having a throat end and a discharge end attached to said housing and communicating directly with said outlet port at said throat end there being no obstruction of any kind therebetween, said throat end diverging into said discharge end, said venturi device having an opening at said throat end communicating exteriorly of said housing and said Venturi device, whereby when said pressurized fluid causes the valve to open at a predetermined pressure, the pressurized discharge from the valve is discharged directly into the throat of the venturi device without substantial change in direction of flow of the discharged Huid, and said discharge creates a low pressure area about the throat of the venturi device to cause fluid outside the venturi to enter said opening at said throat end.

2. The agitator device of claim 1 wherein the crosssectional configuration of said outlet port and the crosssectional conguration of said venturi throat are substantially the same.

3. The agitator device of claim 2 wherein there are two outlet ports on said housing and two venturi devices attached to said housing, both of said outlet ports are closed and opened by said valve member, and one of said venturi devices communicating with one of said outlet ports and the other venturi device communicating with the other outlet port.

4. The agitator device of claim 2 wherein said adjustable biasing means comprises a nut and a bolt means attached to a receiving means within said housing, a spring means resting on a seating means in said housing and urging against said nut and bolt means, said valve member being attached to said nut and bolt means whereby said valve member is urged against said housing by said spring means.

5. The agitator device of claim 2 wherein said valve outlet port and said venturi throat having a rectangular cross-section configuration.

6. The agitator device of claim 2 wherein said valve outlet port and said venturi throat having a generally elliptical cross-section configuration.

7. The agitator device of claim 2 wherein Said venturi device further having an air-inlet opening near said throat for admitting atmospheric air into said venturi device whereby the settling of solid particles in said mixture is further prevented.

8. The agitator device of claim 7 wherein said air-inlet opening having thereat a means for dividing incoming air into small bubbles.

References Cited UNITED STATES PATENTS 592,000 10/ 1897 Curtis. 2,008,853 7/1935 Dietzel 103-278 XR 2,246,678 6/ 1941 Harris 103-272 XR 2,457,388 12/1948 Lung 103-272 )Gt 2,692,798 10/1954 Hicks 137-108 XR 2,855,861 10/1958 Miles et al. 103-272 XR 3,003,325 10/1961 Poethig et al. 103--272 XR 3,142,273 7/1964 Dilts 103--262 XR 3,371,618 3/1968 Chambers 10S-263 XR DONLEY J. STOCKING, Primary Examiner W. I. KRAUSS, Assistant Examiner U.S. Cl. X.R. 10S-271, 278

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