A simple mechanical support can be implemented to prevent such mechanical failure in submerged membrane systems. The mechanical support, which can be in a variety of forms, is attached to the membrane so it protrudes out into the space between adjacent membranes. The mechanical supports of adjacent membrane plates may come into contact with one another or have some minimal gap between them, so long as bending is limited sufficiently to prevent membrane breakage. During operation, the mechanical supports prevent the membrane from bending too far, thus reducing the mechanical stress on the membrane. By doing so, the plate can withstand significantly higher loads before mechanical failure compared to a plate in the bent position. When employed in an array of flat plates membranes, the supports prevent the plates from bending, or from significant bending that would threaten integrity of the plate.
The mechanical supports can come in a variety of shapes and materials. In one example, as illustrated in the accompanying drawings, the mechanical supports are U-shaped clips that are attached to the edge or edges of the membrane, maintaining spacing and plate shape as shown. In another example, adhesive or epoxy is applied between the membranes, onto the adjacent membranes. The support can come as a single piece that attaches to only a single membrane, or as an array of supports that simultaneously attach to an array of membranes. The integral array of supports is preferable, for ease of installation and to prevent outward bending of outermost membranes.
Location of the mechanical supports may vary, as they can be placed in the middle section or offset from the middle of the membranes. The mechanical supports can be placed on the top, bottom, middle, or any combination thereof to provide the membranes with a mechanical support. The number of rows may also vary but most systems will employ a single row of mechanical supports.
An object of the invention is to protect ceramic membrane plates with a simple, effective and easily installed device. These and other objects, advantages and features of the invention will be apparent from the following description of preferred embodiments, considered along with the accompanying drawings.
As shown in
Each array of clips 10 can be assembled of individual clips 10 such as shown in
In a specific embodiment the array 18 of clips 10 can be formed with a larger number of clips, equal to or greater than the expected maximum number of membrane plates that will be ganged together. At the point of divisions between the clips 10, a frangible line (as at 20) can be included, such as perforations or a weakened, thinner line of connection, so that unneeded excess clips can be easily broken off for a particular installation having fewer than the maximum number of plates.
In a ceramic membrane plate of, for example, about one meter length, a limit to bending can be about 0.50 inch (13 mm) deflection at the middle of the plate, without damage of failure or breakage.
Other variations are possible for the spacing devices. In
The above described preferred embodiments are intended to illustrate the principles of the invention, but not to limit its scope. Other embodiments and variations to these preferred embodiments will be apparent to those skilled in the art and may be made without departing from the spirit and scope of the invention as defined in the following claims.
This application claims benefit of provisional application Ser. No. 63/135,446, filed Jan. 8, 2021. The invention concerns membrane filtration, particularly with ceramic membranes, which may be employed in a wastewater treatment system. Membranes experience various mechanical stresses during operation that can lead to premature mechanical failure. In particular, submerged flat plate and flat sheet ceramic membranes can experience severe mechanical stress in various wastewater applications. For example, membrane bioreactors are prone to a phenomenon called dewatering where solids build up between plates due to a variety of reasons. The amount of solids accumulation can be significant to the extent that the outward force from the mass of solids causes the plate to bend, in horizontal bowing movement. With the plate bent, one side is now under tension and susceptible to breaking under movement from the air scour process. Air is bubbled up through the assembly of membranes for the purpose of removing solids from the membrane surfaces. The flow of bubbles over the membrane surface causes the membrane to move back and forth due to changes in pressure. Normally this movement does not present any significant mechanical stress, but if it occurs in the presence of dewatering, the movement can be great enough to cause a membrane to fail, or break.
Number | Date | Country | |
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63135446 | Jan 2021 | US |