US3147221A

US3147221A - Influent distribution means for tanks

Info

Publication number: US3147221A
Application number: US82837A
Authority: US
Inventors: William F Johnston
Original assignee: Chain Belt Co
Current assignee: Chain Belt Co
Priority date: 1961-01-16
Filing date: 1961-01-16
Publication date: 1964-09-01
Anticipated expiration: 1981-09-01

Description

p 1, 1964 w. F. JOHNSTON NFLUENT DISTRIBUTION MEANS FOR TANKS Filed Jan. 16, 1961 FIG. I.

United States Patent 3,147,221 INFLUENT DISTRIBUTION MEANS FOR TANKS William F. Johnston, Milwaukee, Wis., assignor to Chain Belt Company, Milwaukee, Wis., a corporation of Wisconsin Filed Jan. 16, 1961, Ser. No. 82,837 1 Claim. (Cl. 210-519) This invention relates to influent distribution means for the introduction of a suspension into a tank for settling or flotation separation of the suspended material. The feed is directed against one or more dished baflles to be spread over the influent end Wall of the tank within artificial boundaries for each of the jets to prevent their interaction. The boundaries and the equalization of the flow eflected within the boundaries of each jet provide a very significant improvement in the flow and distribution pattern so that the flow moves from said wall and the length of the tank with a uniform velocity front for maximum separation efliciency.

Each dished battle is in effect set in a square recess formed by the boundaries and the end wall of the tank. Due to the mechanical proper-ties of the water, e.g. its viscosity and mass, a practical limit of about seven feet square has been found for the size of each recess and a depth of only six inches is generally adequate. That is, the required bafiie means providing the boundaries need be only about six inches wide and need only project that distance into the tank.

The collector mechanism for the separation tank generally comprises drive chains along each side wall which support and move flights or plows which extend the width of the tank. Accordingly, it is or may be uneconomical to build such tanks less than about fourteen feet wide. Since the flights must be relatively rigid, light weight and replaceable, certain woods such as cedar or redwood are usually used but their maximum unsupported length is generally limited to about twenty feet. Such flights and other economic factors have generally limited the practical width of the tanks to that distance. Accordingly, the present invention contemplates between two and four recesses for the usual tank.

Each recess should be about square so that a small tank of fourteen foot width with two recesses would have a flow-through zone between six and seven feet deep. This may be too great for this size of tank and may be readily reduced by using three recesses which might be up to five and one-half feet high. Other dimensions of such a tank and others are shown in the following table of typical tank sizes.

In the above cases the dished baflles have a diameter about one inch larger than that of the inlet pipes and, as shown, each recess is formed by baflle means projecting from the inlet wall of the tank although the recesses can also be readily formed directly in the wall of the tank, particularly if the tank wall is of concrete.

A single header or distribution channel (trough) is connected to the several pipes ahead of each battle to provide the initial distribution of the flow.

The principal object of the invention is to provide an economical eflicient and clog-free inlet structure. The present invention is intended for A.P.I. (American Petroleum Institute) oil-water separation tanks and also sewage 3,147,221 Patented Sept. 1, 1964 treatment tanks which require a distribution means which is easy to maintain, requires no cleaning or infrequent cleaning, and does not require several inches of hydraulic head to operate.

The drawings furnished herewith illustrate the best mode of carrying out the invention as presently contemplated and set forth hereinafter.

In the drawings:

FIGURE 1 is vertical longitudinal cross-section of a tank intended for the separation of oil and water which may also include some sand or other settleable material requiring removal. The tank and apparatus are illustrated diagrammatically;

FIG. 2 is a section taken on line 22 of FIGURE 1 and shows the recesses and battles in front elevation;

FIG. 3 is a plan view of the inlet end of the tank shown in FIGURE 1; and

FIG. 4 is an enlarged cross-section taken through the center-line of one of the inlet pipes. The section shows the wall of the tank and other parts as they would be made of steel.

The tank 1 shown in the drawings includes the side walls 2 and

end walls

3 and 4. The top of end wall 3 forms a weir 5 over which the clear water flows into the box 6 to which the discharge pipe 7 is connected. Weir 5 serves to maintain a given liquid level in the tank.

Tank 1 also includes the trough 8 located adjacent to end wall 4 and the flat floor 9 having a slope downwardly to trough 8. The collector mechanism operating over floor 9 includes the chain 10 which carries the series of flight or scrapers 11 extending the width of the tank. Chain 10 operates over the

sprockets

12 and 13 and the upper drive is driven by the motor unit 15 disposed above the tank and connected to sprocket 14- by the chain drive 16.

The oil collection mechanism includes the chain 19 which carries the series of flights or scrapers 20 so that the oil is pushed toward and up the beach 21 and into the receiving trough 22 located near the end wall 3 of tank 1. Chain 19 operates over the

sprockets

23 and 24 which latter is driven by the motor drive unit 25 and drive chain 26.

Trough 22 and the baflle 27 extending downwardly from the trough are spaced from end wall 3 and floor 9 of the tank to provide a submerged outlet from the lower separation zone 31 of the tank.

The present invention provides a submerged inlet by which the water and oil suspension is introduced into the tank to flow with a uniform velocity front through the lower separation zone 30 and beneath the upper clarification zone 31 of the tank. The two zones referred to may be of different depths or of generally the same depth as shown by the broken line 32 denoting their common boundary.

The cross-header 33 at the inlet end of the tank is provided with the central flanged fitting 34 by which the header is connected to delivery pipe 35. Header 33 also includes the series of fittings 36 connecting the header with the corresponding fittings of each of the inlet pipes 37.

Each inlet pipe 37 extends through wall 4 of tank 1 and may project into the tank a small distance or none at all as shown. Generally, each pipe 37 should be straight and depending on the size of header 33, of suflicient length so that the flow from the orifice or open end of the pipe is in the form of a uniform, straight jet of a circular flow pattern. The open end of each pipe should also be between one and one and one-half diameters from the corresponding dished baflie 38.

The baflies 38 may be supported by a single cross bar 39, secured at opposite ends to wall 2 of the tank as shown, or individually suported as by brackets, not shown, attached a to the wall 4 of the tank above pipe 37 and joined to the bafille on the convex side or rear of the bafiile.

As previously described, the bafiies 38 serve to spread the jets from the corresponding pipes 37, but do not assure the desired uniform velocity front. According to the present invention, the desired uniform flow section or velocity front is provided by the horizontal and

vertical bafles

40 and 41 in combination with pipes 37 and bafiles 38. As shown,

bafiles

40 and 41 project from wall 4 to form a series of square recesses extending across the width of the tank and symmetrically arranged about pipes 37 and baffies 38 so that each pipe 37 and baffle 38 is at the geometric center of a recess. The side walls 2 may be included with

baffle

40 and 41 or separate wall or bafi le means, not shown, may be provided to define the ends of the series of squares at each side of the tank.

As will be seen in the drawings, the recesses are only approximately of equal height and width so that their dimensions correspond with that of the fiow through section and particularly the tank Width which is generally selected for the space available or other considerations. In that regard, also, the use of the squares greatly reduces the number of inlet pipes required for effective inlet control. This means that each pipe may be larger to improve the distribution of the flow in header 33 to each of such fewer and larger pipes.

Each recess defines the limit of spread of each jet over the wall of the tank so that the flow upon leaving the wall 4 of the tank has What might be considered a waffie pattern enclosing a series of voids at the back side of or behind each baffle 33. However, according to dye tests the voids are filled as the flow moves forward and from somewhere within two feet of baffles 38, the flow then continues with remarkable uniformity over the length of the tank.

The invention may also be used in sewage treatment tanks as well where a well controlled and defined fiowthrough pattern is desired for the flotation or settling or material having a specific gravity very nearly that of water. Particularly in tanks of concrete construction, the rectangular or square recesses may be formed directly in the inlet Wall and setting each pipe 37 and baffle 38 at the center of a recess.

The several recesses are arranged and dimensioned to provide the desired total cross-section of the flow through the tank and the bafiles are generally not required at the side Walls of the tank. Where the flow is to move directly over the floor of the tank, as in a tank for flotation separation only, no lower bafile means would be required. Also, if the flow-through zone is to extend to the water surface no upper baffle means would ordinarily be required.

The invention is, of course, not to be considered limited to tanks within the range of sizes mentioned. Similarly, the depth of the flow-through zone for thickeners might be less than four feet in many cases.

Various modes of carrying out the invention are contemplated as within the scope of the following claim particularly pointing out and distinctly claiming the subject matter which is regarded as the invention.

I claim:

In a rectangular tank for the flotation of suspended solids in the upper zone of the tank and requiring introduction and passage of the feed into and through a lower flow through zone of the tank with a minimum of head loss and no disturbing eddy currents, said tank including a floor, inlet and outlet end walls and adjacent side Walls and having a bafile spaced from the outlet end wall and floor of the tank and defining an outlet approximately corresponding to the cross-section of said lower flow through Zone; baffle means comprising relatively thin, flat plates projecting from the inlet end wall and toward the outlet end wall and with the side walls of the tank defining a series of rectangular, shallow recesses having their openings facing said tank outlet and together corresponding to the cross-section of said lower flow through zone, a distribution header outside of the tank and having a plurality of pipes extending through the inlet end Wall of the tank such that one pipe extends into each recess at the geomertic center of the recess and has its open end within the recess and facing the outlet of the tank, and a dished bafile within each recess supported by the tank and spaced from the end of the pipe within the respective recess and having its concave side facing the end of the pipe whereby the feed entering the tank from each said pipe flows radially of each said pipes over the inlet wall within the recess to the surrounding bafile means, the plates between dished bafiles preventing any interaction of such flow from adjacent pipes and the several bafile means being disposed such that the borders of the jets from the pipes are fully expanded to the dimensions of the flow through zone crosssection prior to flowing toward the outlet end of the tank and as described providing the same with a substantially uniform velocity front corresponding to the cross-section of said lower flow through zone.

References Cited in the file of this patent UNITED STATES PATENTS 1,374,625 Allen Apr. 12, 1921 1,931,988 Hromadka Oct. 24, 1933 2,059,844 Boosey Nov. 3, 1936 2,525,936 Owen Oct. 17, 1950 2,702,124 Stengel Feb. 15, 1955 2,708,520 Dallas May 17, 1955 2,973,866 Genter et a1. Mar. 7, 1961