Injection impeller for agricultural chemicals
BACKGROUND OF THE INVENTION 
     This invention is addressed to use of irrigation and watering systems in the farming industry, as well as sprinkling systems in smaller applications such as residential watering systems and to other applications which may require mixing in a short reach of conduit of an injectate in an effluent flow. Particularly, in the irrigation of large fields in farming, water obtained from a well or surface water source is distributed to the fields through medium pressure pipes with branch lines which feed lateral sprinkler lines equipped with sprinkler heads. It is often desirable to make applications of fertilizers or pesticides concurrently with the irrigation process, and such application is typically effectuated by injection of the additive in liquid form into irrigation water at some point along the length of the conduit pipe leading to the branch lines of the system. Injection has been accomplished by any number of means ranging from mere injection of the liquid additive through an aperture in the conduit pipe, allowing the additive to blend with the irrigation water as it may, to injection systems which are an integral part of the conduit pipe and which disperse the additive into the main flow at a calculated rate. These integral systems, as disclosed in the prior art, accomplish integration of the additive into the system, but do so without attention to relative uniform concentrations of additive being dispersed. In other words, the currently used systems do not achieve mixture of equal concentrations of water and additive within the main conduit, and do not achieve equal concentrations prior to any branching of the main conduit into the lateral irrigation lines. The mixing of two nonmiscible fluids is dependent upon the turbulence of water in the conduit pipe and the pipe length prior to bifurcation or branching to lateral lines. A pipe length roughly 20 times the diameter of the pipe is needed to produce adequate mixing of the liquids. Frequently, geometrical constraints and varying irrigation systems do not provide the length of pipe necessary to accommodate thorough mixing of the liquids. The failure of proper mixing and distribution results in over-application of additive in some areas of the field while other areas suffer from an application of too little additive. The present invention has been designed to accomplish injection and thorough mixing of liquid additives into irrigation systems in the shortest possible distance. Calculation of optimum dispersal distances and utilization of monitored flow rates of additive into the flow of water assures maximum mixture and optimal application of the additive. The advantageous use of the present invention over prior art inventions is more fully appreciable below. 
     SUMMARY OF THE INVENTION 
     A rotor with a plurality of outwardly extended injection tubes is centrally located within the main conduit pipe, oriented transversely to the flow of water. The invention is located at an annular position at the center of discharge, this location and length of discharge tubes being determined as follows: 
     U=water velocity at a point in a pipe 
     r=radius to a point at velocity, U 
     R=radius of a conduit 
     A=area of a conduit 
     Q=discharge of water through a conduit 
     q=center half of discharge 
     U is proportional to (R 2  -r 2 ) 
     (Parabolic velocity distribution) 
     Where pipe diameter is unity 
     U=(1-R 2 ) × coefficient of proportionality ##EQU1## To find the annular center of discharge let: ##EQU2## 
     Therefore, the radius of rotation of the tips of the injection tubes relative to the conduit pipe is theoretically optimally 0.541 of the radius of the conduit pipe, and the invention can be manufactured in any size complimentary to the size of conduit pipe being used by merely varying the length of the injection tubes. 
     The injection tubes of the invention have impeller blades which, when struck by the flow of water down the conduit pipe, cause the rotor to turn. Since the only resistance to rotation is bearing friction, the head loss to operate the invention is minimal, and negligible in sprinkler irrigation systems. Liquid additive is injected into the delivery port of the invention at medium pressure. The liquid travels through a descending L-shaped hollow spindle upon which is located the rotating hub of the rotor. The liquid fills an inner cavity of the hub, and continues through the injection tubes and out into the flow of water. The additive may be injected into the stream of water at a rate proportional to the calculated flow of water in the conduit. 
     Tests comparing the efficiency of mixture and distribution of various injection systems have been completed on a 240 acre field which employs typical farming irrigation systems consisting of well water pumped through a 10 inch conduit which bifurcates 4.3 feet from the point of injection into 8 inch main lines from which 8 sprinkler lines branch to cover the 240 acre field. The injection systems tested were the existing injection system which consists of an injection port 10 inches upstream from the bifurcation; a standard injection system which consists of an injection port 4.3 feet upstream from the bifurcation point through which additive is injected directly into the stream; and the present invention, placed within the main conduit pipe 4.3 feet upstream from the bifurcation. Uran, a common nitrogen fertilizer, was injected into each system at a concentration of 5000 parts per million (ppm). Water samples were taken at the south and west branches of the sprinkler main, and were analyzed for concentration of ammonium and nitrate ions. The results were as follows: 
     
                       TABLE 1                                                     
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Effect of mixing device on fertilizer distribution in                     
sprinkler irrigation system (ppm ammoninum and NO.sub.3)                  
Injection Port                                                            
Location   Standard                                                       
                   Rotamixer   Existing                                   
                                      Ave                                 
______________________________________                                    
South Br  1066     924         1343   1111                                
West Br    970     950         119    680                                 
Ave       1018     937         731    895                                 
______________________________________                                    
 
    
     It can be seen therefore that use of the invention assures more accurate distribution of the additive through distribution into the main line and branches of an irrigation sprinkler system. 
     It is therefore an objective of this invention to provide a means for injecting liquid additives, such as fertilizers and insecticides, into irrigation sprinkler systems in a manner which will optimize dispersal of the additive into the system. 
     It is further an objective of this invention to provide a means for assuring thorough and even distribution of injected additives into irrigation sprinkler systems or other fluid systems within the least distance of the main conduit pipe between the point of injection and any bifurcation of the pipe system to feed branch lines. 
     It is yet another objective of this invention to provide a means for even dispersal of liquid additives throughout irrigation sprinkler systems to avoid over-or under-application of the additives to crops. These and further objectives are explained more fully below. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a perspective view of the invention illustrating its placement relative to the pumping system and main conduit pipe; 
     FIG. 2 is a plan view of the invention illustrating its placement relative to the pumping system and main conduit pipe, and further illustrating the bifurcation of the main conduit into the main branch line; 
     FIG. 3 is a perspective view of the invention, partially cut away to reveal the placement of the rotor relative to the flow of water which is illustrated by the arrows; 
     FIG. 4 is a cross-sectional view of the invention (taken at line A--A of FIG. 5); 
     FIG. 5 is a plan view of one embodiment of the injection tubes and impeller blades; 
     FIG. 6 is a plan view of another embodiment of the injection tubes and impeller blades; 
     FIG. 7 is a plan view of another embodiment of the injection tubes and impeller blades; and 
     FIG. 8 is a plan view of yet another embodiment of the injection tubes and impeller blades. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     FIG. 1 illustrates the general means of distribution of water in an irrigation sprinkling system where a motorized deep-well turbine powered by electric motor 10 dredges well water from below into a main conduit 11. The invention, generally at 12, consists externally of a saddle clamp 13 which joins the pipe 11 emerging from the pump housing to the conduit line 14 leading to the branch lines. The fluid additive is injected into the internal mechanism through a hose 15 which transports the liquid from a nearby tank (not shown). The hose is joined to one-way check valve 16 which connects to the upward extending end of the spindle (not shown) which will be further demonstrated below. 
     FIG. 2 is a plan view illustrating the location of the saddle clamp 20 down stream from the pump housing 21, and relative to the bifurcation 22 of the main conduit 23 into the branch lines 24. An arrow indicates the direction of injected additive through the injection hose 25. Further, arrows indicate the direction of flow of water and additive once it enters the branch lines 24. 
     In FIG. 3, the saddle clamp 30 is shown partially cut away to reveal the internal mechanism of the invention which is comprised of an L-shaped hollow spindle 31 which has about its horizontal arm a cylindrical hollowed hub 32, tapered at either end, which rotates around the spindle. The hub is held in place on the spindle by a threaded nut 33. Projecting from the hub are a plurality of hollow injection tubes 34, and along the length of each injection tube is a substantially semi-circular blade 35 oriented obliquely to the flow of the water, the direction of that flow being demonstrated by the arrows. The coupling means 36 by which the injection hose (not shown) may be joined to the spindle is illustrated as extending through the upper half of the saddle clamp. The saddle clamp encircles a section of hollow pipe 37 which substantially conforms to the diameter of the conduit pipe to which the saddle clamp will be connected. 
     FIG. 4 illustrates a cross-sectional view of the spindle 40 and hub 41 mechanism. The spindle extends downwardly through an aperture in the saddle clamp 42, and at the upper end, forms the coupling means 43 for attachment of the injection hose (not shown). Encircling the horizontal arm of the spindle is a cylindrical hollowed hub 41 which freely rotates thereupon. Free articulation of the two members is enhanced by placement of bearings 44 at either end of the hub, the bearings being formed of a suitable material such as polyethelene or other thermoplastic. The hub is held in place on the horizontal arm of the spindle by a threaded nut 45. Extending perpendicularly to and through the hub are a plurality of hollow injection tubes 46. To each injection tube there is connected along its length a substantially semi-circular blade 47. It may be seen that fluid additive injected into the hollow spindle from an injection hose would follow a path through the hollowed bore 48 of the spindle, exiting the inner bore through an aperture 51, into an inner cavity 49 formed around the horizontal arm of the spindle by the hollowed hub, and from that cavity the pressurized liquid would be forced through the hollowed injection tubes and out into the conduit pipe via the aperture 50 at the end of each injection tube. 
     FIG. 5 illustrates one possible embodiment of the impeller system in which there are three injection tubes 52 evenly spaced about the hub 53, each injection tube having an impeller blade 54 extending from the upper end of the injection tube to approximately two-thirds the length of the tube. 
     FIG. 6 illustrates another possible embodiment of the impeller system in which there are three injection tubes 60 evenly spaced about the hub 61, each injection tube having an impeller blade 62 extending the entire length of the injection tube. Additionally, the blade attached to each injection tube is attached to the forward portion of the injection tube relative to the nut of the hub 63 and extends transversely to the hub so as to maximize the effect of rushing water contacting the face of the blade thereby causing the hub to turn. 
     FIG. 7 illustrates another possible embodiment of the impeller system in which there are six injection tubes 70 equally spaces about the hub 71, each injection tube having an impeller blade 72 extending from the upper end of the injection tube to approximately two-thirds the length of the tube. 
     FIG. 8 illustrates yet another possible embodiment of the impeller system which utilizes a variation of the other configurations in which there are six injection tubes equally spaced about the hub 81, one triad of which is formed of injection tubes 80 which are greater in length and have an impeller blade 82 extending from the upper end of the tube to approximately two-thirds its length. The opposing triad of injection tubes 83 are shorter in length and have an impeller blade 84 extending its full length.