Abstract:
An aeration element for gasification or aeration of liquids includes an essentially flattened, rigid support element having a substantially oval cross-section and corrugated outer surfaces, the corrugated outer surfaces including ridges defining grooves therebetween; a threaded opening for receiving a cooperating fitting for connection to an air supply; and a flexible membrane of elastomeric material disposed around the support element, The membrane has a plurality of slits, and wherein compressed gas is introduced between the support element and the membrane, the gas can escape via these slits into the surrounding liquid. A retaining clamp holds the membrane around at least one end of the support element. A check valve assembly prevents backflow of liquid, particles, sludge or debris into the interior of the support element.

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates to an aeration element that is utilized in an aeration element for the gasification of liquids, especially for the aeration of water. 
     Such apparatus are used, for example, in clarification plants. A plurality of aeration elements are disposed on a distribution conduit, whereby the distribution conduit on the one hand serves for the supply of air or gas to the aeration elements, and on the other hand also serves for the securement of the aeration elements. A plurality of distribution conduits can in turn be combined to form a system. 
     U.S. Pat. No. 5,015,421 to Messner describes a diffusion device that uses a flexible membrane on a rigid, plate-like aeration support element. Due to the structure of the rigid plate that serves as a substrate for the flexible membrane, when the aerating gas bubbles are released through openings provided in the membrane, or when the flow of aerating gas is stopped, the membrane can crease or wrinkle at specific points along the supporting plate, thus causing fatigue and wear at these points and reduced longevity of the aeration element. 
     An elongated aeration element is disclosed in DE 33 19 161A1. In addition, DE 36 00 234 discloses an apparatus for the aeration of water, according to which individual aeration elements are connected with the distribution conduit via fittings that during assembly are pressed into a bore in the distribution conduit accompanied by elastic deformation, thereby forming a positive connection. However, the aeration elements are plate-shaped elements. Such a connection is not suitable for elongated aeration elements, which can have an aeration length of up to and greater than one meter. When the apparatus moves or if there are flows in the liquid that is to be aerated, the long aeration elements act like lever arms, so that the forces that occur at the connection locations are much greater than is the case with plate-shaped aeration elements. 
     U.S. Pat. No. 7,497,421 (U.S. &#39;421) by the same inventor describes an apparatus for gasification of liquids, the disclosure of which is incorporated herein by reference. U.S. &#39;421 describes a device in which compressed gas is introduced into a tubular aeration element made up of rigid support tube with a lengthwise, rounded groove and a flexible membrane disposed around the tube. The gas escapes via slits in the membrane. A specialized fitting is provided for attaching the aeration element to a distribution conduit. The tubular aeration element, however, is limited in its aerating efficiency, due to the limited cross sectional area provided for releasing the aerating gas and bubbles into the surrounding volume of liquid. 
     None of the above art provides an elongated, flattened aeration element with an oval cross section and increased surface area efficiency, which is specifically designed to allow a flexible membrane placed around a support member to expand and collapse during operation without fatigue, wear, and a shortened longevity of the aeration element components. 
     Further, none of the above cited art provides a means for preventing sludge or other particles from entering the interior of the aeration element during use, which can impair or completely inhibit functioning. This can occur if there is a breach of the membrane by an external impact of a sharp object or debris in the surrounding liquid. A backflow of particles or sludge is inhibited by the fine slits of the perforated membrane, acting as check valves in a deflated state of the membrane. 
     It is therefore an object of the present invention to provide a more efficient aeration element that has a greater cross sectional area available, that offers greater longevity and resilience, and which is capable of being mounted in new or existing aeration systems in a variety of configurations. 
     SUMMARY OF THE INVENTION 
     The object of the present invention is realized with a flattened, elongated aeration element having support member with a substantially oval cross-section, an elastomeric and flexible tubular membrane having air slits provided only on a top surface of the aeration element when the membrane is placed around the aeration element, and an air inlet with a threaded connection to connection the aeration element to a distribution conduit that serves for the supply of gas or air. 
     The support member of the aeration element is made up of a rigid, hard plastic material having a corrugated, hollow profiled and with corrugated outer surfaces, such that a plurality of grooves are formed between the ridges of the corrugated surfaces, both on the inner and outer surfaces of the support member. 
     The aeration element is provided with a clamp for retaining in place the membrane and further, the support includes a machine bead to prevent the clamp from slipping and to maintain the membrane under an axial, lengthwise tension, thereby preventing the membrane from slipping off the support member during use. 
     The aeration element can be provided with a check valve in the form of an opening in the upper surface of support member which works in cooperating with a flexible, elastomeric membrane or flap to perform a back flow or check valve function that presents sludge and other materials, in the event the membrane was accidentally breached, or cut by an hard object floating in the sludge or during assembly of the system or operators servicing the system. However, liquid from condensation, or backflow through the membrane is prevented from entering into the air supply system when the air is shut off during a intermitted cycle for de-nitrification and/or an anaerobic phase of the operating batch cycle of the biological processes sequence. 
     The aeration element further is provided with a mounting or support bracket for supporting or fixing in position the end(s) of the elongated aeration element when in use in an aeration system in a clarification tank or pool/pond, for example, by securing the mounting or support bracket to a floor or other surface of the tank or pool. 
     Pursuant to a particularly advantageous embodiment of the invention, aeration elements are respectively disposed in pairs on opposite locations on the distribution conduit, whereby in a given cross-sectional plane, the distribution conduit is provided at two oppositely disposed locations with bores through which a single bolt passes that connects the two aeration elements with one another. In this way, the support of the bolt relative to the wall of the distribution conduit is effected by the respective other aeration element. The aeration elements thus reciprocally support one another, and the apparatus can make do with a minimum number of parts. 
     Further specific features of the invention will be described in detail subsequently. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       This object, and other objects and advantages of the present invention, will appear more clearly from the following specification in conjunction with the accompanying schematic drawings, in which: 
         FIG. 1  shows a plan view of the inventive aeration element; 
         FIG. 2  is a plan view of the aeration element with a cutaway of the outer membrane; 
         FIG. 3  is a lengthwise cross-section of the aeration element of  FIG. 1  with the flexible membrane disposed around it in an inflated state; 
         FIG. 3A  is a lengthwise cross-section of the aeration element of  FIG. 1  with the flexible membrane disposed around it in a deflated state; 
         FIG. 4  is an top view of aeration element showing the retaining clamp and check valve with flexible band in place; 
         FIG. 5  is a view of the connecting end of the aeration element with the flexible membrane in a cutaway view to expose the check valve band and corrugated surface of the aeration element of  FIG. 1 ; 
         FIG. 6  shows a further view of the connecting end of the aeration element with the check valve band/flap cut away to expose the check valve opening; 
         FIG. 6A  shows a further view of the connecting end of the aeration element with the check valve band/flap completed removed. 
         FIG. 7  is a further view of the connecting end of the aeration element with the check valve band/flap and outer membrane shown cut away to expose the air supply hole connected with the threaded air port connection; 
         FIGS. 8 and 8A  are detail views of the bead and grip ridges formed on the support member to prevent slippage of the clamp and membrane; 
         FIG. 9  is a plan view of two inventive aeration elements connected on opposite sides of a distribution conduit; 
         FIGS. 9A-9D  are cross sectional and top views of the two aeration elements of  FIG. 9  showing their connection and positioning relative to the distribution conduit, as well as an arrangement of a plurality of such pairs of aeration elements along a common distribution conduit; 
         FIGS. 10-10B  are plan views illustrating various embodiments for arranging a plurality of inventive aeration elements relative to a distribution conduit or other air supply device; 
         FIG. 11  is a plan view of an inventive aeration element positioned in a mounting assembly; 
         FIGS. 11A-11C  are side, top, and cross sectional view, respectively, of the mounting assembly of  FIG. 11 ; 
         FIG. 12  is a further cross sectional view of the mounting assembly of  FIG. 11 ; 
         FIGS. 12A-12B  are plan view of the mounting assembly of  FIG. 11  and showing the threaded hose coupling and flexible hose connected thereto; 
         FIG. 13  is a plan view of a further embodiment of a mounting bracket assembly; 
         FIGS. 13A-13C  shows further details of the mounting bracket assembly of  FIG. 13 ; 
         FIG. 14  shows a further plan view of the mounting bracket assembly with a threaded hose coupling; and 
         FIGS. 14A-14B  show further views of the mounting bracket assembly and hose coupling of  FIG. 14 . 
     
    
    
     DESCRIPTION OF PREFERRED EMBODIMENTS 
     Referring now to the drawings in detail, in particular  FIGS. 1 and 2 , the elongated, flattened diffuser aeration element  1  of the present invention has an essentially flattened, rigid support element  2  with an essentially oval cross-section. As can be seen in  FIG. 2 , the support element  2  with the oval cross-section has a hard, rigid corrugated hollow profile  11 , such that opposite surfaces  3 ,  4  (upper and lower surfaces, respectively as shown in  FIGS. 1 and 2 ) of the support element provided corrugated surfaces with raised portions or ridges  20  and channels or grooves  21  disposed therebetween. 
     A sleeve  5 , or flexible membrane, is disposed about the support element  2  and secured around at least one end of the support element  2  by a clamp  6  made of stainless steel or another material, which is positioned to hold the sleeve  5  in place in an airtight manner against the support element  2 . The sleeve  5  includes perforations in the form of slits  7  which are positioned only on the upper surface  3  of the support element  2  when the sleeve  5  is in place around the support element  5 . The sleeve  5  preferably is made of a material such as EPDM, silicone, polyurethane, polymeric thermoset, and thermoplastic elastomers. 
     The aeration element  1  further includes a threaded air port connection  8  for attachment to an air supply with a cooperating fitting, such as an air distribution conduit, as will be described below. Radial ribs  9  extend outwardly from the connection  9  to define opening channels and structural support for the open end of the support element  2 . As shown in  FIG. 7 , the threaded air port connection  8  is connected to an air supply hole  10  in the support element  2 , through which air supplied into the aeration element  1  flows into the support element  2 . As shown in  FIGS. 3 and 3A , the air supply flows between the corrugated profile  11  and the sleeve  5 , causing the sleeve  5  to inflate; the air is released from the sleeve  5  into the surrounding liquid via the slits  7  formed in the sleeve  5  on the top or upper surface of the support element  2 . 
       FIG. 3A  shows the sleeve  5  in a deflated or collapsed state, in which the sleeve  5  falls onto the corrugated profile  11 ; this allows for a controlled radius or folding of the sleeve  5 . Further, the ridges  20  and grooves  21  prevent the sleeve  5  from forming creases in the de-pressurized state thereby extending the life expectancy of the unit. During operation, the center or interior of the support element  2  is filled with water and/or sludge when the aeration element  1  is submerged. The inventive structure of the aeration element  1  provides for a reduced buoyancy of the aeration element in this submerged state. When the sleeve  5  is inflated, it expands to a cylindrical form such that corrugated profile (i.e., the ridges  20  and grooves  21 ) may not be evident. It has been found, surprisingly, that the invention works best when the inside circumference of sleeve  5  is equal to the outside circumference of the surface of support element  2 , whether the sleeve  5  is in its inflated or non-inflated state. 
     As shown in  FIG. 4 , the support element  2  includes profiled transitions or stepping  14  such that the inner diameter circumference of the sleeve  5  is equivalent to the outer diameter circumference of the corrugated profile  11  of the support element  2 . 
       FIG. 5  shows the aeration element  1  with the outer sleeve  5  cut away to reveal the support element  2  and its corrugated profile  11 . The aeration element  1 , in a preferred embodiment, includes a check or backflow valve assembly  15 . The check valve assembly  15  includes an opening  16  and flexible, elastomeric band  17  positioned around the support element  2  to cover the opening  16  during operation of the aeration element  1 . The band  17  preferably includes cut-out portions to assist in distribution air flow into the interior of the support element  2 . The band or flap  17  is positioned to cover the opening  16  to prevent the debris from entering the interior of the aeration element  1  and impairing its operation, if a backflow of sludge or other debris should occur when the membrane sleeve  5  is breached or cut by external impact of debris floating in the sludge, or when the sleeve  5  is damaged externally during installation or servicing of the aeration system. To accommodate the band  17  and retain a uniform outer circumference of the support element  2 , a portion of the material of the support  2  is removed from the support element  2  to form a recessed area  18  for the band  17 , as can be seen from  FIGS. 6 and 6A . 
       FIGS. 6 and 6A  show further details of the check or backflow valve assembly  16 . In  FIG. 6 , the band  17  is shown partially cut away to expose the opening  16 , while  FIG. 6A  shows the band  17  completely removed. 
       FIG. 8  shows a detail of the clamp  6 , which is made of stainless steel or another material, and which is positioned near the ends of the aeration element  1  to hold the sleeve  5  in place. Preferably, the support element  2  is provided with a bead  22  that cooperates with a recess  26  on the clamp  6  to prevent the clamp  6  from slipping and to keep the sleeve  5  under an axial and longitudinal tension, thereby preventing the sleeve  5  from slipping off the support element  2 . Further, the support element  2  can be provided with grips or grooves  23  to improve the air seal function of the clamp  6 , which further compresses the sleeve  5  onto the support element  2  (see also  FIG. 8A ). 
       FIG. 9  shows two aeration elements  1  connected via the thread air port connection  8  to an air supply, shown here as distribution conduit  27 . The air port connection  8  is configured to cooperate with a fitting to form a sealed connection to the distribution conduit  27 , for example, a fitting like that disclosed in U.S. Pat. No. 7,497,421 to the same inventor, the subject matter of this patent being incorporated herein by reference. The aeration elements  1  extend perpendicular to the distribution conduit  27 . The distribution conduit  27  can be equipped with a plurality of such pairs of aeration elements  1 . The support element  2  is open at its ends, so that the water or other liquid that surround the aeration element has access to the interior of the support element  2 . Sleeve  5 , as discussed above is an elastic material, especially rubber or a rubber-like polymeric material that stretches around the surface of the flattened support element  2 . When sleeve  5  is not inflated, hence when aeration is not occurring, sleeve  5  deforms to the curvatures of the surface of the flattened support element  2 , but the corrugated, outside surface of support element  2  prevents crease formation in sleeve  5 . 
     As a consequence of the above manner of construction, during operation only a small portion of the support element  2  is filled with air, and the buoyancy of the aeration element is therefore low, which is of particular advantage for very long aeration elements  1 . The length of the aeration element  1  can be varied according to the application, that is, the size and volume of the area being aerated. With very long aeration elements, mounting assemblies may be utilized to fix the aeration elements to a bottom surface of the tank, pool, or other container to prevent vertical and lateral movement or buckling of the aeration elements  2  in the liquid. 
       FIGS. 9A and 9B  illustrate two aeration elements  2  connected to a distribution conduit  27  in cross sectional view, while  FIG. 9C  shows a top view of the aeration element  2  connected to the distribution conduit  27 . As can be seen in  FIGS. 9 and 9C , the slits  7  are evenly distributed over the entire top surface  3  of the sleeve  5 , although the figures show slits  7  positioned only on a portion of the top surface  3  of the sleeve  5 . Air fed into the air port connection  8  can flow through the air supply hole  10  and escapes through the slits  7  as fine bubbles into the surrounding water or liquid. 
       FIG. 9D  shows a plurality of aeration elements  1  connected in the paired relationship of  FIG. 9  along a common distribution channel  27 . The aeration elements  1  can be spaced from one another, as shown in  FIG. 9D , or arranged to be adjacent to one anther, as shown for example in  FIG. 10 . 
     Preferably, the connection of the aeration element  1  to an air distribution conduit  27  or other air supply or manifold is affected by connecting a cooperating, threaded fitting to form a sealed connection between the air port connection  8  and the air distribution manner by a fitting arrangement shown by way of example in  FIGS. 9A through 9C . 
       FIGS. 10 through 10D  show a variety of contemplated configurations for arranging a plurality of the aeration elements  1  depending on the volume of liquid to be aerated and the other parameters of the specific application. As shown in  FIG. 10 , the aeration elements  1  can be arranged side to side on a base frame  41  or support structure and supplied with air via a common conduit  42 , that in turn, is supplied with air via a supply tube, pipe or hose. 
       FIG. 10A  shows another, possible configuration of the aeration elements  1 , again, arranged side-by-side but connected to a distribution conduit  27  as shown in  FIG. 9 . 
       FIG. 10B  shows a further configuration for the aeration elements  1 , in which the elements  1  are arranged in a spaced relation on a framework or tracks  43 , and with each aeration element having an individual air supply  44 . 
     Due to the elongated nature of the aeration element  1  and in particular, when the application requires extremely long aeration elements  1 , a mounting assembly may be provided to secure the aeration element(s) to a bottom surface of the container, pool, pond, etc. containing the water to be aerated. As noted above, the mounting device or bracket prevents vertical or lateral movement of the aeration element(s)  1  during use. 
       FIG. 11  shows an embodiment of a mounting assembly  50  for securing the aeration element  1  to the floor or bottom of the container or body of water to be aerated. The mounting assembly  50  includes flanges  51 ,  52  and respective cooperating bolts  53 ,  54  that received in a cooperating groove of a profiled bar  55 . The aeration element  1  is positioned and clamped between the flanges  51 ,  52 , and the profiled bar  55 , in turn is attached via a pin or bolt  56  to the bottom surface  60  or floor of the container/body of water to be aerated. 
       FIG. 11A  shows a side view of the mounting assembly  50 , profiled bar  55 , and securing bolt and nut assembly  56 .  FIG. 11B  shows a top view of the mounting assembly  50  and aeration element  50 , and  FIG. 11C  shows a cross sectional view mounting assembly  50  in place to hold the aeration element  1  in position as described above. Again, depending on the length of the aeration element(s)  1  and/or depth at which the aeration elements  1  are position, according to the specific application, one or more of such mounting assemblies  50  may be utilized to stabilize and secure the aeration elements  1 . 
       FIGS. 12, 12A and 12B  show the mounting bracket assembly of  FIG. 11 . In this embodiment, a first type of coupling for connecting the aerator element  1  to an air supply is shown by way of example. A threaded adapter or coupling  61  for connecting any type of material hose using a band clamp is utilized in a commonly known manner, with the coupling  61  being received in the air port connection  8 .  FIGS. 13, 13A, 13B, and 13C  show an embodiment of an adjustable mounting bracket  66  for securing one or both ends of the aeration element to the bottom or floor  60  of the tank containing the liquid to be aerated. The adjustable mounting bracket  66  can be cemented and secured by bolts  68  onto a concrete floor, for example. The bracket  66  includes a recess for accommodating a further bolt  69  that enables the height/position of the bracket  66  to be adjustable in order to level the aerator element  1 .  FIG. 13A  shows a threaded hose coupling  62  as a second type of coupling that can be used to connect the aerator element  1  to an air supply, along with a flexible hose  64  that is connected to a cooperating threaded coupling received in the air port connection  9 .  FIG. 13B  shows the end of the aeration element  1  (opposite the end of the aeration element  1  to which the hose  64  is connectable), likewise secured by the mounting bracket  66  to a bottom or floor  60  of the tank. 
       FIG. 13C  shows a side view of the aeration element  1  with mounting brackets  66  securing it to the floor  60  at opposite ends and with a threaded hose coupling  62  and flexible hose  64  attached. 
     Finally,  FIGS. 14 through 14B  show the adjustable mounting bracket  66  again securing opposite ends of the aeration element  1  to the floor or bottom  60  of a tank, but illustrates also the threaded adapter or connection  61  provided to receive a threaded hose coupling  62  and flexible hose  64  for supply air to the device. 
     The above-described features of the inventive aerator element  1  provide for an improved and stable distribution of air bubbles to the liquid to be aerated at a low air flow rate, thus enhancing energy efficiency. 
     Further, the inventive structure of the aerating element as an essentially flattened element with an oval cross section provides a greater surface area efficiency than known aeration devices that utilized round or tubular aeration elements, as discussed above. Further, the inventive corrugated profile of the support element in conjunction with the flexible sleeve provides increased longevity of the sleeve, preventing folds and creases in the sleeve that lead to fatigue and/or tearing of the elastomeric sleeve material, which can cause operating failure and damage to the aerating assembly. 
     The specification incorporates by reference the disclosure of German priority document DE 101 50 180.3 filed Oct. 12, 2001, U.S. Pat. No. 7,497,421, and U.S. Pat. No. 6,769,673. 
     The present invention is, of course, in no way restricted to the specific disclosure of the specification and drawings, but also encompasses any modifications within the scope of the appended claims.