Patent Application
20090096117
None.
This invention relates generally to the application of gas to liquid and deals more particularly with a gas diffuser module constructed in a truss configuration for enhanced structural characteristics.
Applications involving the diffusion of gas into liquid include the aeration/mixing of water and wastewater in basins, lagoons, ponds and other containment structures. In the aeration/mixing of wastewater, multiple diffuser modules have been used with considerable success. A typical system includes floating or submerged air laterals which receive air from a blower or fan and apply the air through flexible air lines extending to submerged diffuser modules which may be arranged in a grid or other configuration. The diffuser modules may be of various types, one of which is a construction having a header pipe supporting elongated diffuser pipes that extend from its opposite sides. The diffusers may be flexible membrane tube diffusers having flexible membranes sleeved over the diffuser pipes, flexible membrane disk diffusers mounted on the diffuser pipes, or any other suitable type of diffuser. The modules may be arranged in a grid pattern throughout the basin to provide thorough and uniform mixing/aeration of the waste water.
Although systems using diffuser modules of this type have been successful, they are not wholly without problems. Maintenance and repair of the diffusers can be particularly difficult because of their submerged location. The diffusers must either be maintained or repaired in place, or, more commonly, the entire module containing one or more worn or defective diffusers must be lifted to the surface using a large crane or other heavy equipment. In large installations, it may be difficult if not impossible for a crane to reach units in the center or near a remote side or end of the basin, even if the crane is equipped with a lengthy boom. The need for heavy ballast to hold the modules down in normal operation adds to the difficulty involved in raising and maintaining the modules.
After maintenance and repair operations have been completed, the module must be replaced in the basins, again requiring the use of a crane or other heavy equipment and again complicated by the heavy ballast. Replacing the module involves the risk of damage, particularly if the module is tilted appreciably or is otherwise handled improperly as it is being lowered in the basin. If one or more of the diffusers are damaged during replacement, additional repair work is necessary and additional downtime of the entire system may result.
Handling the modules in this fashion exerts considerable stress on the piping. Consequently, the module size has been restricted due to structural considerations. Even then, the piping can be easily broken or otherwise damaged during maintenance operations.
In accordance with the invention, a diffuser module is constructed in the form of a truss which substantially enhances its structural strength and rigidity. Consequently, the module can be handled during maintenance operations without breaking or otherwise being damaged. Equally important, the enhanced structural strength allows the module to be constructed in a manner to provide more diffusers and thus more aeration/mixing capability with resulting efficiencies and economies.
The truss may include a header pipe which supplies gas to diffusers and a truss pipe connected to the header pipe by purlins. In one embodiment, the truss pipe may be open at its opposite ends to allow liquid to enter when the module is submerged, thereby providing ballast. The truss pipe may also serve as a buoyancy device in one embodiment of the invention. A gas line may supply gas to the truss pipe to make the diffuser module buoyant so that it can be retrieved to the surface for maintenance work.
The diffuser modules may be suspended from floating air laterals or may be floor mounted units. The air supply may be provided from virtually any convenient location. Various types of diffusers may be used on the module. Of particular benefit when the chamber in the truss pipe is used as a ballast chamber is the ability to minimize the need for additional ballast. This facilitates retrieval of the diffuser modules as well as handling and placement of the modules back in the basin or lagoon. Also, because the header pipe is not supplied with heavy ballast, the pipes can be constructed of plastic rather than metal, and advantage is taken of the benefits of plastic, including reduced cost.
In the accompanying drawings, which form a part of the specification and are to be read in conjunction therewith and in which like reference numerals are used to indicate like or similar parts in the various views:
Referring now to the drawings in more detail and initially to
The system 10 includes a plurality of diffuser modules generally identified by numeral 18. The diffuser modules 18 may be supplied with air from a plurality of floating supply pipes or air laterals 20 which may be plastic pipes floating on the surface of the wastewater (see
One construction of the diffuser modules 18 is shown in
The diffuser pipes 32 may be equipped with conventional flexible membranes sleeved over the pipes in order to diffuse air into the wastewater from the pipes 32 in the form of fine bubbles for high efficiency aeration. Alternatively, disk diffusers (not shown) may be mounted along the length of each diffuser pipe 32 and equipped with disk membranes which apply the air through the membranes in the form of fine bubbles. Other types of diffusers may be used as well.
A ballast chamber is formed within a pipe 36 which may be substantially parallel to pipe 28. Pipe 36 is shown as being a short distance above pipe 28, but it can also be located below pipe 28. Pipe 36 can be of any desired size and length as necessary for the particular application of the diffuser module. A plurality of short pipes 38 form purlins extending rigidly between pipes 28 and 36 to form a truss structure. Mounting saddles 40 are secured to pipe 28 to connect pipes 38 to pipe 28 at one end, and additional saddles 42 are secured to pipe 36 to connect the opposite ends of pipes 38 to pipe 36.
Pipes 28 are equipped with ballast which may take the form of ballast blocks 44 suitably secured to pipes 28. Cables or ropes 46 are secured to pipes 28 to allow the diffuser modules 18 to be lifted to the surface for maintenance work including repair of the diffuser membranes and/or replacement of diffusers. The upper ends of the ropes 46 may be connected with floats (not shown) or tied to the floating air laterals 20 for convenient access.
Pipe 36 serves as a beam and is part of the truss structure which also includes pipe 28 and purlins 38. With heavy ballast such as ballast blocks 44 applied to pipe 28, a substantial structural load is encountered that can result in undue bending and even breaking of pipe 28 when it is a stand-alone unit. The truss construction enhances the structural strength considerably and resists bending of the piping during lift out and other situations where the module must be handled. Pipes 36 are filled with liquid when modules 18 are submerged, and the insides of pipes 36 thus provide ballast chambers which reduce the need for other ballast. The external ballast chambers provided by pipes 36 are beneficial in this respect and are also a significant structural benefit due to the strength of the truss structure of which they are a part.
In a case where pipe 136 acts as a buoyancy chamber, the inside of pipe 136 can be filled with air applied through hose 145 to purge water from pipe 136. The added buoyancy of pipe 136 is able to overcome the ballast 44 so that the diffuser module 118 can be raised to the surface buoyantly for service. Following completion of the maintenance work, air can be vented from pipe 136 so that it is then filled with water causing the diffuser module to sink to its submerged operating position. Pipe 136 serves as a beam and like pipe 36 is part of a truss structure which also includes pipe 28 and purlins 38. Also, it can be used as a ballast chamber or as a buoyancy chamber as indicated.
From the foregoing it will be seen that this invention is one well adapted to attain all ends and objects hereinabove set forth together with the other advantages which are obvious and which are inherent to the structure.
It will be understood that certain features and subcombinations are of utility and may be employed without reference to other features and subcombinations. This is contemplated by and is within the scope of the claims.
Since many possible embodiments may be made of the invention without departing from the scope thereof, it is to be understood that all matter herein set forth or shown in the accompanying drawings is to be interpreted as illustrative, and not in a limiting sense.
