Gas separation – Mounted or supported for continuous motion – Differentially deflected system fluid constituents
Reexamination Certificate
2001-12-21
2003-11-18
Hopkins, Robert A. (Department: 1724)
Gas separation
Mounted or supported for continuous motion
Differentially deflected system fluid constituents
C055S423000, C055S438000
Reexamination Certificate
active
06648935
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates generally to extracting blowers that separate liquid and particulate matter from carrier air. Specifically, this invention relates to extracting blowers that incorporate a dual stage air cleaning system wherein a first stage extracts heavy entrained particles/fluid from the carrier air and a second stage extracts lighter entrained particles/fluid from the carrier air.
2. Description of the Related Art
Air blowers are used in a variety of industries to provide cooling air to personnel, structures and equipment. Oftentimes, the air supply for these air blowers is contaminated with solids (e.g., dirt, grease, metallic and non-metallic dust) and/or liquids (e.g., water, organic and inorganic chemical vapors). When carried in the air passing through a blower, these contaminants can damage equipment by compromising electrical circuits, reducing the efficiency of rotating equipment and decreasing the life of the equipment due to increased friction, corrosion and abrasion between moving parts. Thus, it is common to combine these blowers with devices that can remove or “clean” environmental air contaminants, such as airborne dust, water and other liquid vapors, and other light matter from the blower air. Of course, in addition to causing harm to the environment into and equipment onto which air is blown, contaminants passing through a blower may become trapped in the blower itself, creating a build-up or sludge, which diminishes the effectiveness and useful life of the blower.
Prior art includes several designs for blowers that scrub blown air. Many of these blowers rely on gravity to assist in the separation of the contaminants from the air, and therefore are only effective in removing larger contaminant particles. Other blowers use a complex system of baffles, filters, secondary pressure pumps or fully enclosed housings, which are difficult to maintain, clean and operate.
One type of blower for cooling and ventilation that is well known in the industry is the extraction blower. A well know type of extracting blower is the rotary type blower that cleans contaminated air by drawing the air across the blades of an impeller and using the centrifugal effect of the blades to separate the lighter air from the heavier contaminants. Specifically, the rotation of an impeller within a fan housing creates a low pressure area within the housing that causes air to be axially drawn into the housing. As air enters the housing, it is contacted by the impeller blades and is forced generally outward along the blade by the rotation of the blades. Centrifugal forces cause the lighter air to be forced out to the leading edges of the impeller blades quickly, while forward momentum causes the heavier contaminants within the air to move toward the back of the blade and strike a backplate attached to the back or trailing edge of the impeller blades. Upon striking the backplate, the contaminants migrate outward along the backplate to the plates outward edge, where the contaminants are channeled off.
“In many prior art extracting blower configurations, the fan housing is separated into a front chamber that collects and bleeds off the lighter, clean air and a rearward chamber in which the contaminants are collected. In such configurations, the impeller blade is positioned so as to extend into both chambers. The leading edge of the impeller blade, from which clean air is ejected, is positioned to be in the front chamber and the trailing edge of the impeller, attached to the backplate, is positioned to be in the reward chamber.”
Various configurations to this type of fan have been utilized extensively in the prior art, such as for example, the old and well known technique of notching the impeller blades to fit around the wall separating the front and reward chambers, thereby insuring that only a minimal amount of air is lost with the exhaust in the reward chamber. One drawback to prior art extracting blowers of this type is that this tighter “seal”, between the front and reward chambers is that a greater quantity of contaminants might remain entrained in the “clean” air as it is bled off. More generally, this is also a drawback to other types of extracting blowers. In environments where the blower air needs to be as clean as possible, it would therefore be desirable to provide an extracting blower where the air is subject to at least two separate cleaning stages.
“As discussed above, often times the contaminants passing through the blower can cause damage to the blower itself. One prior art configuration that has proven particularly susceptible to such damage utilizes a wiper that is welded onto each fan blade. While the wiper is intended to guide particulate matter moving across the fan blade to the reward chamber, it has been found that the solid contaminants in the air tend to strike the weld with sufficient velocity and repetitiveness so as to cause pitting and abrasion to the weld line. This problem is exacerbated as the liquid contaminants begin to erode the weld, especially at the points were the weld has already been weakened by the solid contaminants. Thus, it would further be desirable to provide an extracting blower with fan blades that can guide contaminants to the reward chamber without subjecting the fan blades to damage from the contaminants moving across their surface.”
BRIEF SUMMARY OF THE INVENTION
The present invention provides a method and apparatus that addresses these drawbacks of the prior art. Specifically, a blower fan is provided wherein the fan is provided with a dual air cleaning system. The blower fan is comprised of a fan circular housing.
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“Installation Operation and Maintenance, Roto-Clone Dynamic Precipitator Type D”, Service Bulletin DC-139D, American Air Filter Company, Inc., Louisville, KY with a copy of “Industrial Ventilation 20th Edition: A Manual of Recommended Practice,” 1988, Committee on Industrial Ventilation, Lansing, Michigan.
Bracewell & Patterson LLP
Hopkins Robert A.
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