US 2815943 A
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M. A. LAMB DIFFUSER TUBE Dec. 10, 1957 5 Sheets-Sheet 1 Filed Jan. 16. 1951 M. A. LAMB DIFFUSER TUBE Dec. 10, 1957 5 Sheets-Sheet 2 n N lnga made/$5 pwafiw,"
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M. A. LAMB DIFFUSER TUBE Dec. 10, 1957 Filed Jan. 16. 1951 M. A. LAMB DIFFUSER TUBE Dec. 10, 1957 5 Sheets-Sheet 4 Filed Jan. 16. 1951 M. A. LAMB DIFFUSER TUBE QWT QQ QH v F, L v
Dec. 10, 1957 Filed Jan. 16, 1951 DIFFUSER TUBE Miles A. Lamb, (Zhicago, Ill., assignor to Chicago Pump Company, a corporation of Delaware Application January 16, 1951, Serial No. 206,237
Claims. (Cl. 261-122) This invention relates to a diffuser tube used for the aeration of liquid, or for the dispersion of gases or vapors therein, and more particularly to diffuser tubes of collapsible, foraminated fabric into which the air or gas is supplied under pressure and through the interstices of which the air or gas passes in fine bubbles into the liquid in which the diffuser tube is immersed.
nited States Patent 0 Diffusers of the type with which the present invention is concerned are employed in the activated sludge process of treating sewage, ore flotation processes, treatment of industrial wastes, various fermentation processes, and other chemical processes where gas-liquid contact is essential.
In the past such diffusers have in the main been made of porous carbon and ceramic material or by wrapping a cord about a hollow foraminated core so that air was permitted to pass through openings provided between adjacent convolutions of the cord. These diffusers were costly. In addition they became clogged more or less readily and had to be taken off the air main to be cleaned. This made the maintenance cost rather costly.
Another type of known diffuser comprises a hose having attached thereto a fabric bag porous enough to permit air to flow therethrough into the surrounding liquid. One such diffuser is disclosed in the Kraut Patent No.
1,849,146, issued March 15, 1932. This type of diffuser has several serious disadvantages. It has been found impossible to control the flow of air through the bag to provide uniform aeration of the liquid in which the bag is held because the bag is free to swing around in the liquid and cause the air bubbles escaping from the bag to coalesce into larger bubbles of varying size. Another disadvantage of this type of diffuser is the fact that the bag can not be deflated and inflated quickly enough to dislodge the solid matter deposited by the liquid in the pores of the bag. The deflation of the bag is so slow that the liquid in which the bag is immersed percolates through the fabric, bringing in solid matter which clogs the pores, and makes frequent cleaning necessary. An additional disadvantage of this type of diffuser is that the size of the bag that can be used is limited, and the volume of liquid that can be aerated by each bag is likewise limited.
The diffuser tubes of the present invention comprise a I rigid, non-porous anchoring member and a flexible, porous member secured thereto. Air or gas (aeriform body) is passed to the anchoring member and it passes therefrom to the porous member and from the porous member to the surrounding medium.
The porous member may be made of flexible, porous, woven fabric, suitably of a plastic material. Thus it may be made from a synthetic linear polyamide such as nylon, from a copolymer of vinyl. chloride and vinylidene chloride of the type known commercially as Saran from Orlon or other synthetic plastic material, from canvas or other suitable textile material, from metal or other suitable fabric strong enough to withstand the action of sewageand the pressure of the liquid in which it is imice mersed, and yet be flexible enough to be collapsed quickly when the air or gas supply is shut off. The interstices of the fabric through which the air or gas flows may be varied as desired but preferably are small enough to cause the air or gas to pass through in fine bubbles to provide more eflicient aeration or gasification.
Hereafter, in the description of the invention, reference will be made only to air, but with the understanding that by this term applicant contemplates gas or other aeriform body.
The porous member of the diffuser tube may be made in any desirable length, and each such member is anchored at a plurality of points to a rigid pipe from which air is supplied to the member. The anchoring of each air diffuser member to a rigid pipe at a plurality of points prevents the member from swinging around in the liquid, and causes each of the finely divided bubbles to flow in a well defined path that prevents coalescence of the bubbles and results in uniform aeration of the liquid.
There may be a single diffuser tube or a plurality of such tubes ganged together. When ganged together the tubes are preferably arranged in parallel relationship and are positioned adjacent one wall of the tank to provide a wide band of air bubbles that will follow a circulatory path through the liquid to provide uniform aeration throughout the liquid. All of the rigid pipes in the ganged system are interconnected at both ends, thus insuring uniform pressure in each diffuser tube and throughout the system. The uniformity of the air pressure is essential to assure uniform aeration. When the air pressure is not uniform throughout the system some areas do not receive enough pressure to overcome the static head and, in consequence, little or no diffusion takes place in such areas.
The present system includes a quick acting valve so that the air supply may be instantaneously cut off from the diffuser tubes, thereby causing a quick and complete collapse of the tubes. The valve also permits quick inflation of the tubes and the sudden collapse and subsequent prompt inflation of the tubes causes the solid matter to be broken away from the surface of the tubes. If any solid matter is lodged in the pores of any tube it will be blown out by the pressure of the air when the tube is inflated. The deflation is so rapid as to prevent infiltration of the surrounding liquid. The diffuser tubes are kept fairly clean at all times by merely turning the valve controlling the air in order to deflate and then reinfiate the tubes, with the result that the maintenance expense of the present system is relatively low. If a more thorough cleaning is necessary, or if any repairs are required, the diffuser tubes may be readily removed.
Another advantage of the present invention is the ease and low cost of manufacturing the diffuser tubes. These tubes may be fabricated like hose in continuous lengths, and cut off to provide any suitable length of diffuser tubes. The open ends of the tubes are quickly and easily sealed to provide an efficient closure at each end of the tube. It is not necessary to make the pipes of stainless steel, or similar expensive material, because they do not have a multiplicity of small orifices as in the case where the pipe itself serves as the diffuser and must be protected against corrosion so that its orifices do not become clogged. The only openings in the pipe in the present construction are of comparatively large cross-section, and are connected to the manifold or to the diffuser by couplings which prevent access to the openings by the liquid in which the diffuser tubes are immersed.
The structure of the present invention by means of which the above and other advantages are attained will be described in detail in the following specification, taken, in conjunction with the accompanying drawings,
showingv preferred illustrative embodiments of the invention, in which:
Figure 1 is a cross sectional view showing a sewage tank with a diffusing, unit embodying the invention immersed therein;
Fig. 2 is a section along the line 22 of Fig. 3, with parts in elevation, showing the hollow stanchion through which air is forced and details of the air release valve;
Fig. 3 is a side elevation of the stanchion shown in Fig. 2;
Fig. 4 is a top elevation of a diffuser unit showing a plurality of diffuser tubes secured to air supply pipes;
Fig. 5 is an enlarged fragmentary side elevation showing the means for anchoring the tube to the air supply pipe and for supplying air to the tube;
Fig. 6 is a cross sectional View, taken along the line 6-6- of Fig. 5, and. showing, in dotted lines, the cross sectional shape assumed by the diffuser tube when the air is passing therethrough;
Fig. 7 is an enlarged cross. sectional view showing the connection between the diffuser tube and the air supply p p Fig. 8 is a detail perspective view of the closure means being applied to one end of a diffuser tube;
Fig; 9 is a fragmentary top elevation of a diffuser unit in which a different form of diffuser tube is used;
Fig. 10 is an enlarged top elevation of one of the diffuser tubes of Fig. 9 and the air supply pipe to which it is secured;
Fig. 11 is an enlarged side elevation of the diffuser tube shown in Fig. 10;
Fig. 12 is an enlarged cross sectional view, taken along the line 12-12 of Fig. 11;
Fig. 13 is a fragmentary longitudinal sectional view showing the means for securing the longitudinal edge of the fabric of the diffuser tube to the air supply pipe;
Fig. 14 is a fragmentary longitudinal sectional view showing the means for securing the end of the fabric to the air supply pipe;
Fig. 15 is an exploded perspective view of the component parts of the diffuser tubeand air supply pipe before they are assembled together;
Fig. 16 is a top elevation of another embodiment of diffuser tube and its air supply pipe;
Fig. 17 is a side elevation of the diffuser tube shown in Fig. 16;
Fig. 18 is a fragmentary top elevation of the air supply pipe for use with the diffuser tube of Figs. 16 and 17;
Fig. 19 is an enlarged fragmentary cross sectional view showing the means for securing the diffuser tube to the air supply pipe of Figs. 16 to 18; and
Fig. 20 is a fragmentary perspective view of the diffuser tube of Figs. 16 and 17.
In the drawings, the reference numeral 2 indicates a sewage tank having an inlet 3 and an outlet 4. A hollow stanchion 5 connects an air main 6 to an elbow 7. Air is forced through main 6 by any suitable pump or blower (not shown) and into elbow 7. A valve 8, operated by handle 9, is positioned in elbow 7 and opens to the atmosphere so that when it is in open position the air from main 6 flows directly to the atmosphere. When valve 8 is closed the air flows through elbow 7 into a pipe 10. It will be noted that valve 8 is a quick acting valve that may be opened very rapidly so as to cut off the air supply to pipe 10 practically instantaneously by diverting the flow of air from main 6 to the atmosphere. A pipe 11, having its upper end offset laterally from the lower end of pipe 10 is pivotally connected thereto, as indicated at 12. Elbow 7 is pivoted to stanchion 5, as indicated at 13, to permitpipes 10 and 11 to be swung out of the sewage tank 2, in the manner described in the Lannert Patent No.. 2,328,655, granted September 7, 1943, for cleaning, orfor repairs of. any of the mechanism normally immersed in the sewage: 14. A bumper guard" 15 is secured to: pipe 11, as indicated at 16, to
keep the mechanism properly spaced from the wall of tank 2.
At the lower end of pipe 11 a coupling 17 is connected to a pair of manifolds 18 and 19, as shown in Fig. 4. Manifold 19 is L-shaped to provide space between it and manifold 18 so that when the mechanism is swung out of the tank, manifolds 18 and 19 straddle pipe 10 to make the mechanism readily accessible to a man standing on a catwalk 20 which extends from a point adjacent valve 8 to the adjacent wall of the tank. Manifolds 18 and 19 are each provided with a plurality of couplings 21 each of which is connected to a rigid air supply pipe 22. Pipes 22 are arranged parallel to each other and extend in opposite directions from manifolds 18 and 19. The pipes may be of any suitable length, depending upon the size of the sewage tank in which they are positioned. It is preferred to have them as long as possible for reasons that will hereinafter appear. The opposite ends of all air supply pipes 22 in each set of pipes are interconnected throughpipes 23 to insure uniform air pressure in all pipes throughout the length of each pipe.
Each air supply pipe 22 has a flexible porous diffuser tube 24 of substantially the same length as the pipe secured thereto at a plurality of spaced points by tubular hollow members 25. It is desirable to have the diffuser tubes of considerable length because the length of the tubes determines the Width of the diffusion band. The air supply pipes 22 and diffuser tubes 24 may be arranged adjacent the wall of the tank opposite inlet 3, as shown, or adjacent any other wall, as desired. The liquid flowing through the inlet into the tank causes a circulatory movement of the sewage in the tank. Accordingly, air bubbles which are forced through the interstices of the diffuser tubes by pressure of the air flowing from pipes 22 through hollow members 25, are carried by the circulatory motion of the sewage in a well defined path as long as the diffuser tubes remain in fixed position relative to the tank. This arrangement of the diffuser tubes keeps the bubbles from coalescing to form large bubbles. The fine bubbles uniformly aerate the liquid through which they circulate.
The diffuser tubes may be made of any suitable flexible, porous material as pointed out above, preferably of a closely woven fabric which is strong enough to withstand thepressure of the sewage and the corrosive action of the sewage, and yet is flexible enough to cause the diffuser tubes to collapse immediately under the pressure of the sewage when the supply of air is cut off. Valve 8 is opened to cause complete collapse of diffuser tubes 24, and is immediately closed to reinflate the diffuser tubes before the pressure of the liquid causes the sewage to pereolate through the fabric of the tubes.
The diffuser tubes may be formed from flat sections and stitched longitudinally to form tubular members, or may be fabricated as endless tubular members. Regardless of how the tubular member is formed, its ends are preferably folded over, as indicated at 26, Fig. 8, and then secured together by a resilient U-shaped clamp 27 which seals the ends in closed position.
The tubular hollow members 25 which connect diffuser tubes 24 with pipes 22 each are provided on one end with a flange 28 positioned within tube 24 and seated against a grommet 29 protecting the edges of the tube around the opening 30 through which member 25 projects. A washer 31 of rubber or similar material is positioned against the underside of grommet 29 and is clamped thereagainst by a nut 32 threaded on member 25, to hold the flanged end of member 25 rigidly secured to. diffuser tube 24. Pipe 22 is provided with a tapered threaded opening 33 into which the lower end of member 25 loosely fits. A tapered nut 34 threaded into opening 33 is tightened to wedge itself against the lower end of member 25 to hold member 25 securely in place. Members 25 provide passageways 35 for air to pass freely from pipes 22 to diffuser tubes 24.
When valve 8 is closed the air from air main 6 passes through stanchion 5, elbow 7 pipes 10 and 11, manifolds 18 and 19, and pipes 22 into diffuser tubes 24. The air is then forced through the interstices of the walls of tubes 24 in fine bubbles which aerate the sewage in which the tubes are immersed in a very eflicient manner. Although the tendency of the air passing through the walls of the diffuser tubes is to keep the pores of said walls clean by blowing away the solid matter contained in the sewage, some solid matter does accumulate on the walls, and in time such solid matter would clog the pores of the tube. This possibility of clogging the pores of the diffuser tube is obviated by merely opening and then closing valve 8 without any appreciable interruption of the aerating process.
As soon as valve 8 is opened the air which would otherwise be forced through pipe 10 is blown out to the atmosphere. The pressure of the sewage adjacent the diffuser tubes is much greater than atmospheric pressure. Accordingly, the pressure of the sewage causes tubes 24 to collapse immediately, and the air that was in the tubes is forced through members 25 and backwards through the system. The rapid collapse of tubes 24 causes the solid matter which may have accumulated against the walls of tubes 24 to break away therefrom. The deflation is so rapid, because of the pressure of the sewage on the outside of the diffuser tubes, that the liquid sewage can not percolate into the walls of the diffuser tubes. The quick inflation of the tubes after their deflation dislodges any solid matter which is not broken away by the deflation, either by the distention of the walls or by the air forced through the pores of the walls when the valve is closed. This rapid opening and closing of valve 8 keeps the walls of the dilfuser tubes fairly clean at all times, and, as a consequence thereof, the diffuser tubes stay in the sewage for long periods of time, because inspection, cleaning, and repairing of the tubes is not required as often as with diffuser tubes previously used. The capability of the diffuser tubes to remain in the sewage without frequent inspection, outside cleaning, or repairs, results in increased efiiciency in the aeration of sewage and in comparatively low maintenance costs.
In the embodiment of the invention illustrated in Figs. 9 to 15, the system is a duplication of that hereinabove described, except in the specific structure of the diffuser tubes and the pipes to which the tubes are connected. Accordingly, the same reference numerals will be used to designate the parts that are duplicates of the previously described embodiment.
The pipes 36, which take the place of pipes 22, are semi-cylindrical, and the open side of each pipe is closed by a flat plate 37 welded thereto, as indicated at 38 (Fig. 12). Plate 37 extends beyond the sides of pipe 36, as indicated at 39 and 40. The end of pipe 36 adjacent coupling 21 is left in its cylindrical form, as indicated at 41, and the cut-away upper portion is closed by a plate 42 Welded to the pipe and the end of plate 37. The opposite end of pipe 36 is closed by a plate 43 welded to the end of the pipe and to the underside of plate 37. Plate 37 is provided with a plurality of openings 44 through which the air passes from pipe 36 into diffuser tubes 45.
Diffuser tubes 45 are fabricated of the same material as diffuser tubes 24, but are shaped differently, as shown in Fig. 15. Flaps 46 extend laterally from each longitudinal edge of tube 45 and extend around the extensions 39 and 40. Channel shaped members 47 fit around extensions 39 and 40, and bolts 48 extending through channel members 47, flaps 46 and extensions 39 and 40 have nuts 49 threaded thereon to clamp flaps 46 in place. The ends of tube 45 are also provided with flaps 50 and 51. Flap 50 is clamped in place by a channel member 52 in the same manner as flaps 46 are secured. The end of plate 37 adjacent plate 42 is notched, as indicated at 53, and flap 51 is secured to said end by a plate 54 having legs 55 fitting into notches 53, and held by bolts 56 passing through apertures 57 in plate 54 and threaded.
into apertures 58 in the end of plate 37.
In the embodiment of the invention illustrated in Figs. 16 to 20, a pipe 59, similar to pipe 36, is closed by means of a plate 60 which has an upstanding boss 61 extending longitudinally thereof. The boss may be integral with plate 60, or may be rigidly secured thereto in any suitable manner, as by welding. Air holes 62 extend through boss 61 at spaced intervals, to allow air to pass from pipe 59 to the diffuser tube 63. The diffuser tube is fabricated of the same material as in the previously described embodiments, but difiers therefrom in shape. It is of elongated tubular shape and has a longitudinally extending opening 64 surrounded by a collar 65. The ends of the tube are closed by resilient 'U-shaped clamps 27.
The collar 65 is-held in place against the edges of boss 61 by clampingplates 66 which have transversely elongated openings 67. Bolts 68 extend through openings 67 and are threaded into openings 69. Clamping members 66 are moved laterally into engagement with the edges of boss 61 and then bolts 68 are tightened to hold tube 63 securely in position.
. In each of the embodiments of the invention described above, a diffuser tube made of flexible porous fabric capable of withstanding the pressure and action of sewage is connected to an air supply pipe in such a manner that cutting off the air supply to the pipe causes an immediate collapse of the diffuser tube. Such collapse is followed immediately by inflation of the tube, with the result that substantially all the solid matter accumulated adjacent the wall of the diffuser tube is dislodged therefrom.
The air diffuser system may include a single air diffuser tube assembly or two such assemblies or more than the three shown in the preferred illustrative embodiments described herein.
Although I have described preferred embodiments of my invention in considerable detail, it will be understood that the description thereof is intended to be illustrative, rather than restrictive, as many details may be modified or changed without departing from the spirit or scope of the invention. Accordingly, I do not desire to be restricted to the exact structure described.
1. A diffuser unit comprising a plurality of rigid nonporous pipes connected to a source of air under pressure and interconnected to each other at each end whereby the air pressure in all of said pipes remains uniform throughout the length of each pipe, a flexible, substantially completely collapsible porous tube anchored to each of said pipes at a plurality of longitudinally spaced points, and a tubular hollow member leading from each of said pipes to the porous tube anchored thereto.
2. A diffuser unit comprising a manifold connected to an air main, a plurality of rigid non-porous pipes connected to said manifold and interconnected to each other whereby air flows through each of said pipes at uniform pressure, a flexible, substantially completely collapsible porous tube connected to each of said pipes at a plurality of longitudinally spaced points, tubular hollow members extending from each of said pipes to the porous tube connected therewith, and a quick acting valve controlling the flow of air into said manifold, said valve being effective to inflate and deflate said flexible tubes quickly and simultaneously.
3. A diffuser unit comprising a plurality of interconnected air supply pipes arranged in parallel relationship, and a plurality of flexible diffuser tubes arranged parallel to said pipes, each of said tubes being substantially completely collapsible along its entire length and being rigidly secured to one of said pipes at a plurality of spaced points intermediate the length of said tube, and intercommunicating means comprising tubular hollow members forming passageways for air to flow from said air supply pipes simultaneously into; said diffuser tubes to inflate said tubes uniformly along substantially their entire length, the Walls of said diffuser tubes being porous to permit air to flow therethrough.
4. A diffuser unit comprising atplurality of interconnected air supply pipes arranged in parallel relationship, and a plurality of flexible diffuser tubes arranged parallel' to said pipes, each of said tubes being substantially completely collapsible along its entire length and being rigidly secured to one of said pipes at a plurality of spaced points intermediate the length of said tube, intercommunicating means comprising tubular hollow members forming passageways for air to flow from said air supply pipes into said diffuser tubes simultaneously to rapidly inflate said tubes uniformly along substantially the entire length of each of said tubes, the wallsof said diffuser tubes being porous to permit air to flow therethrough, and a quick acting valve controlling the flow of air to said air supply pipes.
5. A diffuser comprising a rigid, hollow, non-porous anchoring member, a flexible, substantially completely collapsible porous diffuser tube, said anchoring member and said tube being provided with a pair of aligned apertures, a tubular hollow member provided with a flange at one end, said flange being positioned within said diffuser tube and rigidly held adjacent the edge of said tube surrounding the aperture in said tube, the other end of said tubular hollow member fitting within the aperture in said anchoringmember, and a tapered nut threaded into said last mentioned aperture to wedge the end; of said hollow member against separation from said anchoring member.
ReferencesCited in the file of this patent UNITED STATES PATENTS 306,485 Hartfeldt Oct. 14, 1884 972,183 Guntrum Oct. 11, 1910 1,633,561 Drew June 21,1927 1,717,713 Logan June 18, 1929 1,759,983 Houston May 27, 1930 1,792,286 Curry et al Feb. 10, 1931 1,849,146 Kraut Mar. 15, 1932 2,047,735 Hunsdorf July 14, 1936 2,294,973 Ford Sept. 8, 1942 2,328,655 Lannert Sept. 7, 1943 2,383,946 Tietig Sept. 4, 1945 FOREIGN PATENTS 972,808 France Sept. 6, 1950