Gas and liquid contact apparatus – Contact devices – Liquid tank
Reexamination Certificate
2000-08-16
2001-06-12
Bushey, C. Scott (Department: 1724)
Gas and liquid contact apparatus
Contact devices
Liquid tank
C261SDIG007
Reexamination Certificate
active
06244574
ABSTRACT:
This invention relates to a dual diffuser assembly, and more particularly to a dual diffuser assembly for use in aerating wastewater within a wastewater treatment tank.
BACKGROUND OF INVENTION
Diffusers are used in wastewater treatment tanks to introduce oxygen into the wastewater. The wastewater is typically contained in treatment tanks, and air is forced through diffusers to produce fine bubbles that flow through the wastewater. Diffusing a high volume of air or oxygen into the wastewater in the form of fine bubbles facilitates biological growth during the waste treatment process. Supplying air into the treatment tank also serves to prevent sedimentation of the wastewater within the treatment tank. The treatment tank usually includes a network of air distribution piping for transferring air to the diffusers. The network of air distribution piping typically includes a drop pipe extending from an air supply to a manifold that is submerged within the wastewater. The submerged manifold is connected to a plurality of submerged distribution pipes that are also submerged within the wastewater and generally arranged in a parallel configuration along the bottom of the treatment tank. Each distribution pipe typically supports a number of diffusers such that the diffusers are also submerged within the wastewater along the bottom of the tank.
After a period of operation diffusers may become clogged and less efficient such that the diffusers must be cleaned and/or replaced. Cleaning and/or replacing the diffusers is burdensome because the treatment tank must be emptied to perform maintenance on the diffusers.
Conventional diffusers are bolted either directly, or mounted via a base plate, to one of the air distribution pipes. The construction of the diffuser assemblies makes it difficult to perform maintenance on the diffuser assembly. First, the distribution pipe may require machining in order for the diffuser assembly to be mounted thereto. Second, the diffuser assembly may be damaged when torque is applied to the diffuser assembly as the diffuser assembly is being assembled/disassembled. Applying,a torque can be especially problematic because diffuser assemblies are usually attached at a single central location and have a limited ability to withstand excessive torque. Finally, common diffuser assemblies are often mounted either underneath or on the sides of the distribution pipe making it more difficult for an individual to access critical portions of the diffuser assembly during maintenance.
A typical diffuser arrangement is disclosed in U.S. Pat. No. 3,083,953. The gas diffusion apparatus includes two diffusers that are located laterally adjacent to a conduit portion. The conduit portion is mounted end-to-end within an air distribution pipe such that some of the air passes through the conduit portion.
Another diffuser is disclosed in U.S. Pat. No. 3,396,950. This patent discloses a diffuser for sewage treatment. The diffuser includes external threads that are used to mount the diffuser to the top of an air distribution pipe.
Another known diffuser is disclosed in U.S. Pat. No. 3,954,922. This patent discloses a diffuser having a header that is mounted underneath a distribution pipe. The header is mounted to the distribution pipe by a hose-type clamp. The header includes an opening that supplies air into a medium through a pair of angular flanges. The flanges extend from underneath the distribution pipe on opposite sides of the distribution pipe.
Another such diffuser is disclosed in U.S. Pat. No. 4,046,845. The disclosed diffuser is secured into the top of an air supply pipe through a base member that has an externally threaded section.
SUMMARY OF THE INVENTION
The present invention is directed to a dual diffuser assembly used for aerating a liquid. The diffuser assembly provides an improved design for attaching the diffuser assembly to an air distribution pipe. A plurality of these diffuser assemblies are able to aerate a large quantity of the medium when the medium is contained within one or more storage tanks. One example of a fluid that could be aerated is wastewater located in a sewage treatment facility.
The dual diffuser assembly includes a first diffuser body and a second diffuser body. Both of the diffuser bodies are mounted in fluid communication with an air distribution pipe. A first diffuser is supported by the first diffuser body and a second diffuser is supported by the second diffuser body. The dual diffuser assembly further includes a saddle that connects the first and second diffuser bodies to the distribution pipe.
During operation of the diffuser assembly air under pressure is forced from the distribution pipe into the diffuser assembly. The air enters the first and second diffuser bodies where the air flows through the first and second diffusers before passing into the medium to be aerated. As the air passes through the first and second diffusers it is formed into fine bubbles and the flow of fine bubbles of air through the medium facilitates aeration of the medium.
The saddle is preferably integral with the first and second diffuser bodies and includes a contoured surface that matches the upper half of the outer surface on the distribution pipe. The saddle of the diffuser assembly extends across the top of the distribution pipe and downwardly along both sides of the distribution pipe approximately to the mid-portion, or widest portion, of the pipe. Thus, the saddle surrounds the entire upper half of the pipe. This configuration provides a large contact area between the saddle and the distribution pipe. A larger contact area between the saddle and the distribution pipe creates a stronger connection when the saddle is secured to the distribution pipe, especially via solvent welding.
In a preferred form of the invention the first diffuser body and the second diffuser body extend outwardly, transversely and upwardly from the distribution pipe. Positioning the diffusers substantially above and away from the distribution pipe provides easy access to the diffuser assembly during service and eliminates interference from the distribution pipe with the fine bubbles that are emitted as the air passes through the diffusers into the medium to be aerated.
In another aspect, the present invention relates to a system for aerating wastewater that comprises an air distribution pipe and a plurality of diffuser assemblies mounted along the air distribution pipe. The diffuser assemblies are adapted to receive air from one or more openings in air distribution pipe.
An object of this invention is to provide a diffuser assembly that is readily mounted onto a distribution pipe. Providing a diffuser assembly that is readily mounted to the distribution pipe minimizes the cost associated with installing, cleaning and/or replacing the diffuser assembly.
Another object of this invention is to provide a diffuser assembly that is capable of being securely connected to a distribution pipe that provides air to the diffuser assembly. A secure connection between the diffuser assembly and the distribution pipe reduces the possibility of damage that may arise when a force, or torque, is applied to the diffuser assembly during maintenance or installation.
Another objective is to provide a diffuser assembly that can be mounted anywhere along the length of a distribution pipe. Increasing the flexibility associated with mounting the diffuser assembly to the distribution pipe simplifies the task of mounting numerous diffuser assemblies along the length of a distribution pipe that is submerged in a treatment tank.
Still another object of the invention is to provide a diffuser assembly that is readily mounted to existing air distribution pipes such that the network of distribution pipes within an existing storage tank can be retro-fitted with new diffuser assemblies.
Other features and advantages of the invention will become apparent to those skilled in the art upon review of the following detailed description, claims and drawings.
REFERENCES:
patent: 3083953 (1963-04-01), Langdon et al.
patent: 3644231
Bushey C. Scott
Michael & Best & Friedrich LLP
United States Filter Corporation
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