Submersible water circulation system for enclosed tanks

A submersible, water circulation system for enclosed tanks such as used by municipalities, fire districts, and industries. The system includes a driving unit having a shell extending along an axis with a pump supported within the shell. The shell has at least one inlet and at least one outlet and is positionable on the floor of the tank with the outlet facing upwardly. In operation, the pump continuously draws an incoming flow of water from outside of the driving unit adjacent the tank floor through the inlet of the driving unit and preferably drives all of the continuously incoming flow out through the upwardly facing outlet. The upwardly facing outlet is preferably a thin, elongated slot that creates a thin, substantially planar discharge of water therethrough that presents a very large surface area for its volume and induces water adjacent the shell to move upwardly with it.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to the field of circulation systems for water tanks and more particularly to the field of circulation systems for enclosed tanks such as used for municipalities, fire protection, and industrial purposes.

2. Discussion of the Background

Municipalities, fire districts, and industries commonly use enclosed water tanks. Such tanks typically hold about 300,000-500,000 gallons with some larger ones more on the order of 2 to 3 million gallons and are about 50-75 feet wide and 30 or more feet high. The water in these tanks is preferably kept mixed by an internal circulation system to maintain its freshness, particularly in municipal water tanks, and to avoid water quality problems such as bacteria growth and nitrite development.

A physical problem with many such tanks is that they normally have only a relatively small access opening (e.g., 18-24 inches wide) which is designed primarily just to permit an individual worker to pass through to inspect or repair the tank. Consequently, many circulation systems if they are going to be used in the tank must be passed through the access opening in nearly completely disassembled or at least partially disassembled condition. One or more workers must then enter the tank to assemble the system. This often requires special, elaborate, and costly training and following strict regulatory and other safety procedures. Special equipment must also often be used such as winches to lower the workers, tethered tools, safety lines, air monitors, inflatable rafts, and even diving gear as well as rescue personnel standing by. Additionally, it can require that the tank be taken off line or out of service and even drained. Alternate sources must often then be arranged to temporarily supply water to customers and for fire protection. Any unexpected or prolonged delays in bringing the tank back on line can thereafter be quite costly and in some cases present safety concerns to the community. The same problems are presented if the circulation system placed in the tank subsequently breaks down and workers must enter the tank to repair it.

With these and other concerns in mind, the present invention was developed. In it, a submersible circulation system is provided that can easily fit through the relatively small access opening of the tank in a completely assembled condition. Additionally, the circulation system is designed to be lowered to the tank floor to automatically assume the desired operating orientation without the need for any workers to enter the tank. The system can also be raised out of the tank through the access opening without the necessity of any workers having to enter the tank.

SUMMARY OF THE INVENTION

This invention involves a submersible, water circulation system for enclosed tanks such as used by municipalities, fire districts, and industries. The system includes a driving unit having a shell extending along an axis with a pump supported within the shell. The shell has at least one inlet and at least one outlet and is positionable on the floor of the tank with the outlet facing upwardly.

In operation, the pump continuously draws an incoming flow of water from outside of the driving unit adjacent the tank floor through the inlet of the driving unit. In the preferred embodiment, all of the continuously incoming flow is then driven by the pump out of the driving unit through the upwardly facing outlet. The upwardly facing outlet is preferably a thin, elongated slot extending along the shell of the driving unit and creates a thin, substantially planar discharge of water therethrough that is directed upwardly toward the surface of the body of water. The substantially planar discharge induces water adjacent the outside of the shell of the driving unit to move upwardly with it toward the surface of the body of water.

The substantially planar discharge presents a very large surface area for its volume to the adjacent water and induces a very large volume of tank water to flow with it. The discharge from the submerged driving unit is substantially laminar and travels upwardly to the surface of the water and substantially radially outwardly to the sides of the tank. It then flows downwardly to the tank floor and substantially radially inwardly along the tank floor to the submerged driving unit. In doing so, this primary circulation pattern in turn induces secondary flow patterns within the body of water to thereby thoroughly mix the water in the entire tank and to do so in a substantially laminar manner.

The driving unit of the circulation system is additionally designed to be received through the relatively small access opening of the tank in a completely assembled conditioned. It can thereafter be lowered to the tank floor by a flexible line to automatically assume the desired operating orientation without the need for any workers to enter the tank. The driving unit can also be raised out of the tank through the access opening without the necessity of any workers having to enter the tank.

DETAILED DESCRIPTION OF THE INVENTION

As shown inFIGS. 1-3, the circulation system1of the present invention is primarily intended for use to circulate water (FIGS. 2-3) in an enclosed water tank2. Such tanks2are commonly used to contain water for municipalities, fire prevention, and industrial purposes. The tanks2(FIG. 1) typically have side and top walls4,6and a floor8. The tank size can vary but typically holds about 300,000-500,000 gallons with some larger ones more on the order of 2 to 3 million gallons and are about 50-75 feet wide and 30 or more feet high. The tanks2also usually have a fairly small access opening at10(e.g., 18-24 inches wide) in the top wall6that is primarily designed to permit a single worker to pass through to inspect or repair the interior of the tank2. In some cases, the access opening10may have safety bars or other restrictions and its width may be only 12 inches or less and not even permit any entry by a worker. The present circulation system1ofFIGS. 1-3in this last regard as explained in more detail below has been specifically designed to fit through such small access openings10in a completely assembled condition. Additionally, the circulation system1as also explained in more detail below has been designed so it can be lowered to the tank floor8to automatically assume the desired operating orientation ofFIGS. 1-3without the need for any workers to enter the tank2. Conversely, the circulation system1of the present invention can be removed from the tank2through the access opening10without the necessity of any workers having to enter the tank2.

Referring again toFIGS. 1-3, the circulation system1has a submersible driving unit3(FIG. 1) positionable on the floor8of the tank2. The driving unit1as illustrated inFIGS. 2-3creates an upwardly directed flow12,12′,12″ immediately above the drive unit3that establishes an overall circulation pattern14,16,18in the body of water20in the tank2. In this regard, the overall circulation pattern extends upwardly at12,12′,12″ from the submerged driving unit3to the surface22of the body of water20at22′. The pattern then flows substantially radially outwardly at14(seeFIGS. 2 and 4) along the surface22of the body of water20to the side walls4of the tank2(see againFIG. 2), downwardly at16along the tank walls4, and substantially radially horizontally inwardly at18along the tank floor8toward the driving unit3. Aiding the set up of this overall circulation pattern and in particular its radial surface spreading ofFIG. 4is that the upwardly directed flow12,12′,12″ from the drive unit3preferably does not break or at least does not significantly break the surface22. Rather, the upward flow creates a small mounding or crowning effect at22′ inFIGS. 2-3(e.g., less than an inch and preferably a relatively small fraction such as ¼ to ½ of an inch). This mounding or crowning at22′ cyclically rises and collapses creating the substantially uniform, radial surface spreading ofFIG. 4. Additionally, the overall circulation pattern of12,12′,12″ and14,16,18in the tank2in turn induces secondary flow patterns within the body of water20such as at24inFIG. 2to then thoroughly mix the water in the entire tank2.

The driving unit3itself as shown inFIGS. 5-7has an outer shell7that extends along an axis9between first and second end portions11,11′. The shell7has at least one inlet at13and at least a first outlet at15. The shell7is positionable on the floor8of the tank2(FIG. 1) with the outlet15facing upwardly (see alsoFIGS. 5-7). The upwardly facing outlet15in the preferred embodiment ofFIG. 5is a very thin, elongated slot (e.g., ¼ inch or less wide and 36 inches or so long) that extends substantially along the axis9of the shell7substantially the entire distance between the end portions11,11′ of the shell7. The width of the discharge12is then less than 5% of its length and preferably more on the order of less than 1%-2% of its length.

Supported within the shell7of the driving unit3is a pump21(seeFIG. 8). The pump21has first and second end portions23,23′ with the second end portion23′ of pump21being preferably spaced from the second end portion11′ of the outer shell7in this embodiment. A baffle plate25is preferably positioned as illustrated inFIG. 8to extend within the shell7from just above the second end portion23′ of the pump21to the second end portion11′ of the shell7. A small volume of water26(e.g., 16 ounces) is then defined between the end portions23′,11′ of the pump21and shell7. The baffle plate25as shown inFIG. 9has holes or cutouts25′ to permit water to flow by it to the areas28,28′ inFIG. 8just below the slot of the outlet15. The baffle plate25in this embodiment has been found to help to evenly distribute the pressurized water (e.g., 5-10 psi above ambient) along the entire length of the slot of outlet15in the areas28,28′ between the end portions11,11′ of the shell7.

In operation, the pump21continuously draws an incoming flow of water30(seeFIG. 2) from outside the driving unit3adjacent the tank floor8. The incoming water30flows axially through the inlet13(see alsoFIG. 8) of the shell7at its first end portion11. The water is drawn passed the outside of the pump casing21′ inFIG. 8between the pump casing21′ and an outer tube27into the pump inlets29just short of the closed wall31. The drawn water cools the pump21on its path to the inlets29and then passes through the pump impeller33out into the volume of water at26under the baffle plate25. In this manner, the pump21draws and then drives the continuously incoming flow30through the shell7of the driving unit3and out of the driving unit3(FIG. 2) through the slot of the upwardly facing outlet15in the shell7(see alsoFIG. 5). The slot of the outlet15as indicated above is very thin (e.g., ¼ inch or less) and elongated (e.g., 36 inches or more) and creates a very thin (seeFIG. 3at12), substantially planar (seeFIGS. 2-3in conjunction with each other at12) discharge of water through the slot of the outlet15. The thin, substantially planar discharge12as shown inFIGS. 2-3is directed upwardly toward the surface22of the body of water20. As indicated above, the upwardly directed discharge at12in turn induces water at18′ inFIG. 3adjacent the longitudinal or axial outside of the shell7of the driving unit3to move upwardly with it toward the surface22of the body of water20. The pump21is relatively light weight (e.g., 70-80 pounds) and is preferably a relatively small, electric one (e.g., 48 VAC and 500 watts). The pump21as shown inFIGS. 1 and 8has a power line such as32dropping down to it from the tank top6(FIG. 1) that is adjacent the disinfectant line35and lowering chain41discussed below.

For its volume, the thin, substantially planar discharge at12(FIG. 3) presents a very large surface area along its longitudinal sides to the adjacent water and induces a large amount of adjacent water to travel upwardly with it. In doing so, it is believed that as the initial discharge12travels upwardly inFIG. 3, the discharge12due to the surrounding water it induces as schematically shown inFIG. 10begins to narrow or close in from its edges and increase in volume from essentially a plane to more of a substantially oval shape at12′ (FIG. 10). Thereafter, it is believed that the upwardly flow12′ continues to narrow or close in from its edges, increase in volume, and thicken more into a substantially cylindrical shape at12″ before reaching the surface22of the body of water20and crowning at22′ inFIGS. 2-3.

It has been empirically measured that the thin, substantially planar initial discharge12(e.g., at 150-200 gallons per minute) will induce an overall flow or movement of water in the tank2on the order of 10:1 (e.g., 1500-2000 gallons per minute). This is in comparison to a single nozzle at the same discharge rate and volume inducing or moving flow in the tank2at more of a 5:1 ratio. Again, it is believed that the greatly increased surface area of the thin, substantially planar discharge12(versus for example the external surface area of a single nozzle creating a substantially cylindrical discharge) contacts and induces the significant difference in overall flow or movement of water in the tank2. Further, this is accomplished as illustrated inFIGS. 2-3without sacrificing the desired surface mounding or crowning at22′ and resulting, radial surface spreading of the water as illustrated inFIG. 4.

The essentially non-turbulent discharge12,12′,12″ and surface crowning at22′ inFIGS. 2-3additionally ensures that the overall circulation pattern with14,16,18and induced secondary patterns such as24inFIGS. 2-3are all desirably created in a nearly laminar manner for thorough and uniform mixing of all of the water in the entire tank2. Further and because of the thoroughness of the mixing, it is possible to inject disinfectant (e.g., chlorine) as needed at the driving unit3via a line such as35inFIGS. 1 and 8and have the disinfectant be uniformly, reliably, and relatively quickly (e.g., a matter of a few hours) spread throughout all of the water in the tank2. The disinfectant line35in this regard preferably discharges the concentrated disinfectant into the outflow from the pump impeller33as shown inFIG. 8in order to avoid having the concentrated disinfectant pass through the pump21itself. Because of the thorough and complete mixing of the water by the circulation system ofFIGS. 1-3, the disinfectant is equally mixes throughout the entire tank2not only to uniformly disinfect the water but also to contact and disinfect virtually all of the surfaces of the tank2below the water line22. An additional advantage of the uniform mixing of the water is that any sampling of the tank water to monitor the need to add disinfectant or to draw a sample for testing that sufficient disinfectant is present can be reliably done at virtually any location in the tank2.

As mentioned above, the driving unit3of the present invention has been specifically designed to fit through the access opening10of the tank2(FIGS. 11-13) even when the opening10is on the order of 12 inches or less. In this regard and even though the driving unit3preferably has an overall length L inFIG. 11on the order of 36 inches or more to create the desired, elongated, discharge slot at the outlet15, the height H and width W (FIG. 12) of the driving unit3are more on the order of 9.5 and 9.0 inches respectively. As also mentioned above, the driving unit3with the attached chain or other flexible line41inFIGS. 11-13has been specially designed so the driving unit3can be lowered through the access opening10to the tank floor8(FIG. 13) to automatically assume the desired operating orientation or position with the slot of the outlet15facing upwardly. The lowering can be done manually as the driving unit3preferably weighs on the order of only 70-80 pounds or a winch can be used if desired. Regardless, the driving unit3will drop down to the tank floor8with the leading legs or edge portions43′ (FIG. 13) of the second end portion11′ striking the tank floor8first. The driving unit3will then pivot substantially about the legs or edge portions43′ to assume the predetermined and desired operating orientation with the slot of the outlet15facing upwardly.

This last feature is accomplished by securing the lowering chain or other line41to the driving unit3(e.g., at the first end portion11of the shell7inFIG. 11) above the center of gravity45of the driving unit3with the driving unit3in its operating position ofFIG. 11with the axis9of the shell7extending substantially horizontally. The chain or other line41is also spaced as shown inFIG. 11laterally to the side of a vertical plane47passing through the center of gravity45and extending substantially perpendicular to the shell axis9. The chain41is also preferably attached in a second vertical plane substantially perpendicular to the plane47and containing the center of gravity45. Consequently, when the driving unit3is lowered as inFIG. 13with the second end portion11′ of the driving unit3preceding the first end portion11through the access opening10, the driving unit3will tilt or swing slightly clockwise inFIG. 13to vertically align the projected axis41′ of the chain41and center of gravity45. In doing so, it will actually move or swing the legs or edge portions43′ of the driving unit3slightly to the left inFIG. 13of the projected axis41′ of the vertically extending chain41. The legs or edge portions43′ as illustrated inFIG. 13will then lead the driving unit3downwardly to strike the tank floor8first. Thereafter, the center of gravity45as positioned to the right of the landing legs or edge portions43′ inFIG. 13will cause the driving unit3to pivot substantially about the legs or edge portions43′ (i.e., to the right or clockwise inFIG. 13) to assume the desired operating orientation or position on the tank floor8inFIG. 13. It is noted that the legs or edges portions43′ could be a single member if desired. Further, the preferred legs or edge portions43′ are shown as providing relatively sharp edges for the pivoting action but they could be more rounded (e.g., a rounded surface) and could be a single edge portion as discussed above as long as an axially extending edge portion (e.g., sharp or rounded) was preferably provided to facilitate the pivoting action.

It is also noted that the pump21and shell7of the embodiment ofFIGS. 5-8are set forth as different parts. However, their designs could be combined or integrated with common end portions and a common inlet13and/or outlet15as long as the slot of the discharge outlet15remained thin and elongated. The word shell in this regard is used to refer to the outer element and could be hollow or substantially solid. The single, elongated slot of the outlet15of the preferred embodiment ofFIGS. 1-13could also be a series or plurality of immediately adjacent, thin, elongated slots at outlets15,15′,15″ as inFIG. 14. As shown, the slots of the outlets15,15′,15″ ofFIG. 14extend along the shell axis9and would preferably have the same relative dimensions as that of the outlet15in the embodiment ofFIGS. 1-13(i.e., width to length of less than 5% and preferably less than 1%-2%). The combined lengths of the slots of outlets15,15′,15″ would also extend substantially the same distance as the shell7does between its end portions11,11′. Although a single, elongated slot is preferred as in the embodiment ofFIGS. 1-13, the closely adjacent and substantially collinear ones of15,15′,15″ inFIG. 14will essentially merge just outside of the shell7into a single, planar discharge like12of the embodiment ofFIGS. 1-13.

The outer, tubular shell7whether separate from or integral with the pump21is also preferably substantially cylindrical along and about the axis9as illustrated. This is preferred to provide the maximum, cross-sectional area for its volume so the shell7can be as compact as possible and fit through the smaller access openings10. Additionally, the circulation system of the present invention has been described and illustrated in use in an enclosed, elevated tank but it is equally applicable for use in tanks for ground or underground storage and with other contained bodies of water such as in reservoirs.

It is further noted that although the discharge arrangements such as the plurality of spaced nozzles51ofFIG. 15aand the single nozzles51′ ofFIGS. 15band15care less preferred than the elongated slots ofFIGS. 1-14, these less preferred arrangements can still be used in the lowering technique ofFIG. 13. In such cases, the driving unit3will still automatically assume the desired operating orientation or position with the discharge nozzles facing upwardly. As in the preferred embodiment ofFIGS. 1-13, the tank water is still preferably drawn in axially along the axis9of the shell7and discharged radially outwardly of the axis9. The center of gravity45in the embodiment ofFIGS. 1-13is positioned as shown inFIGS. 11-13due primarily to the heaviest component (i.e., the pump21) being located as illustrated inFIG. 8. However, this location of the center of gravity45could be accomplished by simply weighting the shell7(whether it is a separate component from the pump21or integrated with it) in any fashion to position the center of gravity45as illustrated inFIGS. 11-13. The desired lowering technique ofFIG. 13can still be accomplished.

In this last regard, the chain or other flexible line41inFIGS. 11-13could be attached to the shell7adjacent to or at the opposite end portion11′ or other locations spaced above the center of gravity45(FIG. 11) and from the vertical plane47but is preferably attached as shown to the end portion11. With such an attachment, a large moment arm is created tending to more forcefully pivot the landed driving unit3ofFIG. 13about the legs or edge portions43′ to the final, substantially horizontal operating position. The legs or edge potions43′ as discussed above could also be a single member as long as at least one pivoting edge or surface is created.

The above disclosure sets forth a number of embodiments of the present invention described in detail with respect to the accompanying drawings. Those skilled in this art will appreciate that various changes, modifications, other structural arrangements, and other embodiments could be practiced under the teachings of the present invention without departing from the scope of this invention as set forth in the following claims. In particular, it is noted that the word substantially is utilized herein to represent the inherent degree of uncertainty that may be attributed to any quantitative comparison, value, measurement or other representation. This term is also utilized herein to represent the degree by which a quantitative representation may vary from a stated reference without resulting in a change in the basic function of the subject matter involved.