Patent Application
20100187701
The present inventions relate to mixers. More particularly, the present inventions relate to mixers that are equipped with gas injection devices and/or baffle plates to improve mixing in a variety of applications, including but not limited to water and wastewater treatment applications.
There are numerous available mixers for water and wastewater treatment applications. Of particular applicability to the present inventions are floating vertical shaft downflow mixers. Typical devices are shown and described in U.S. Pat. Nos. 4,723,848; 4,442,771 and 2,991,983 (all incorporated herein by reference). In general, such mixers include an annular float to support the mixer on the body of fluid to be mixed. A drive motor is mounted on the top of the float above the surface of the fluid. A propeller or drive shaft is connected to the drive motor and extends downwardly therefrom below the float and into the fluid. A propeller or impeller is attached to the drive shaft. A draft tube is typically mounted to the underside of the float extending downward from the float which encases the propeller. The draft tube is also provided with an intake at its upper end which is near the bottom of the float and a lower end that forms a discharge. When in use, operation of the propeller causes the fluid to be drawn into the intake in a pumping action. The fluid is then forced through the draft tube discharge end to mix the bulk fluid contents.
Other types of mixers are also known, including those that inject oxygen or other gases into the fluid body. Some such devices are shown and described in U.S. Pat. No. 6,145,815; 6,135,430 and EP0252903. Such known devices that inject gas as part of the mixing process typically include hoods and other mechanical arrangements that are more complicated and expensive than typical downflow mixers.
There is a need to improve the performance of typical downflow mixers, as well as to incorporate gas injection capabilities into such mixers. The present inventions are directed to such needs. In fact, the present inventions have led to unexpected results in their various combinations.
The present inventions preserve the advantages of known downflow and other mixers and also provide new features, advantages and results.
Therefore, it is an object of the present invention to provide a downflow mixer that improves mixing performance using a baffle plate.
Another object of the present invention is to incorporate a gas injection device on a downflow mixer to improve mixing performance.
Still another object of the present invention is to provide a downflow mixer with a gas injection device and a baffle to increase mixing performance.
A further object of the present invention is to provide a gas injection device that may be easily turned on or off as desired.
An additional object of the present invention is to provide a gas injected downflow mixer wherein the injection of gas does not decrease the pumping efficiency of the mixer and provides increased mixing capabilities.
Accordingly, the present inventions provide a gas injected downflow mixer having a draft tube with a lower discharge end and a gas source. A gas injection device is also provided which is attached to the lower discharge end of the draft tube. The gas injection device includes an injector body having injection ports, a gas distribution manifold attached to the injector body to distribute the gas to the injection ports, and at least one gas inlet port to provide a gas supply to the gas distribution manifold. A baffle plate may also be attached to a lower end of the injector body to keep gas bubbles from short circuiting the mixer intake. In addition, baffles or preferably v-shaped baffles may be placed on the inside of the injector body above one or more of the injection ports to create low or negative pressure around the injection ports. Flow disruptors may also be located on the interior of the injector body to increase shear.
The present inventions also provide a downflow mixer having a draft tube with a lower end defining a discharge end and a baffle plate attached to said discharge end which extends horizontally from said discharge end to prevent gas bubbles from interfering with pumping or mixing efficiency and to induce proper mixing flow.
The present inventions further provide a floating fluid mixer having a draft tube with a lower end submerged in the fluid to be mixed and a gas injection device with a discharge end attached to the lower end of the draft tube. The gas injection device includes an injector body having an interior and an exterior, injection ports in the injector body to distribute the gas and a gas distribution manifold attached to the injector body to distribute the gas to the injection ports. The interior of the injector body is provided with baffles over one or more of the injection ports. And, a baffle plate may be attached to the discharge end of the gas injection device. Flow disruptors may also be provided on the interior of the injector body.
The terms used in the claims of this patent are intended to have their broadest meaning consistent with the requirements of law. Where alternative meanings are possible, the broadest meaning is intended. All words used in the claims are intended to be used in the normal, customary usage of grammar and the English language.
The stated and unstated objects, features and advantages of the present inventions (sometimes used in the singular, but not excluding the plural) will become apparent from the following descriptions and drawings, wherein like reference numerals represent like elements in the various views, and in which:
Set forth below is a description of what is currently believed to be the preferred embodiments or best representative examples of the inventions claimed. Future and present alternatives and modifications to the embodiments and preferred embodiments are contemplated. Any alternatives or modifications which make insubstantial changes in function, purpose, structure or result are intended to be covered by the claims of this patent.
The present inventions have particular applicability to vertical shaft downflow mixers, including unidirectional and multidirectional mixing devices. It will be understood by those of skill in the art that the present inventions may be used with different types of mixers, including those with and without floats. For discussion purposes, the present inventions are described when used in conjunction with an AquaDDM® direct drive mixer/blender available from Aqua-Aerobic Systems, Inc. of Rockford, Ill. USA, which is preferred. In addition, the preferred gas supply system for the gas injection device is the Vacuum Swing Absorption (“VSA”) unit manufactured and sold by Air Products and Chemicals, Inc. of Allentown, Pa. USA. It will also be understood that other gas supply systems may be used in the present inventions.
In
Preferred and exemplary embodiments of the present inventions may best be seen by reference to
A preferred gas injection device 30 is shown in
Injector body 31 is provided with a series of injection ports 35 spaced around its circumference. In the preferred embodiment, the injection ports 35 are placed between one-half and two-thirds of the way down from the top 32 of injector body 31. It has been found that if the injection ports 35 are too close to the propeller or impeller, the gas bubbles injected will rise to the propeller and will interfere with the proper pumping performance and efficiency. At the preferred placement along the length of injector body 31, the flow of pumped fluid is sufficient to carry away the gas bubbles. In fact, those of skill in the art may find it counter-intuitive to add a gas injector to a pump/mixer because of the potential loss of pumping or mixing power potentially caused by the gas bubbles. Injection ports 35 are designed and sized to permit the passage of oxygen or other gas into the fluid stream. It will be understood by those of ordinary skill in the art that the diameter of injection ports 35 will vary based upon the capability of the oxygen or other gas delivery system such as the preferred VSA unit. In the preferred embodiment, the maximum diameter of injection port 35 was one-eight inch, which helps prevent backflow into the gas injection device 30. Injector body 31 may be tapered or otherwise modified depending upon the flow characteristics desired. It is preferred, however, that injector body 31 not be tapered.
Covering and in fluid communication with injection ports 35 is a gas distribution manifold 36 mounted to or on the exterior 41 of the injector body 31. In the preferred embodiment, manifold 36 is generally a u-shaped channel that is welded or otherwise secured to the exterior 41 of injector body 31 and covers injection ports 35. In the preferred embodiment, manifold 36 is in two pieces to essentially ring the entire circumference of injection ports 35 around injector body 31. As a result, end caps 37 are provided to make manifold 36 air tight. It will be understood by those of ordinary skill in the art that manifold 36 may take a variety of shapes sufficient to distribute the gas to be injected through injection ports 35 in a uniform manner. In a preferred embodiment, a gas inlet port 38 is provided for each half of manifold 36. Gas inlet port 38 is in fluid communication with the interior of manifold 36. Gas inlet port 38 is then connected to gas line 40 (
Also in a preferred embodiment, a series of v-shaped baffles 42 is provided over each injection port 35 on the interior 39 of injector body 31. In a preferred embodiment, baffles 42 are fabricated from structural angles and secured by well known means such as welding to the interior 39 of injector body 31 to overhang injection ports 35. As shown in
One purpose of baffles 42 is to increase turbulence around injection ports 35 that aids in proper bubble formation. Another purpose is to create low or negative pressure at or around injection ports 35. It has been found that the highest area low pressure is at the apex or top 45 of baffle 42 (see
In addition, baffles 42 help induce gas flow so that the delivery system does not have to overcome entry pressure upon start-up and operates more efficiently. Thus, the present inventions obviate the need for complicated and expensive valve systems and the like. Finally, a series of flow disruptors 44 may also be provided at the lower end 33 on the interior 39 of injector body 31. The optional flow disruptors 44 help increase shear and break-up the gas bubbles for better mixing.
By reference to
The above description is not intended to limit the meaning of the words used in or the scope of the following claims that define the invention. Rather, it is contemplated that future modifications in structure, function or result will exist that are not substantial changes and that all such insubstantial changes in what is claimed are intended to be covered by the claims. Thus, while preferred embodiments of the present inventions have been illustrated and described, it will be understood that changes and modifications can be made without departing from the claimed invention. In addition, although the term “claimed invention” or “present invention” is sometimes used herein in the singular, it will be understood that there are a plurality of inventions as described and claimed.
Various features of the present inventions are set forth in the following claims.
