Gas separation: processes – Deflecting – Centrifugal force
Reexamination Certificate
1999-07-27
2001-05-15
Simmons, David A. (Department: 1724)
Gas separation: processes
Deflecting
Centrifugal force
C055S426000, C055S429000, C055S433000, C055S459100, C055SDIG003
Reexamination Certificate
active
06231645
ABSTRACT:
The present invention relates generally to cyclonic separators. In one particular application, the invention relates to the cyclonic separation of particulate material from an air flow.
BACKGROUND OF THE INVENTION
The use of a cyclone, or multiple cyclones connected in parallel or series, has long been known to be advantageous in the separation of particulate matter from a fluid stream. Typically, a relatively high speed fluid stream is introduced tangentially to a generally cylindrical or frusto-conical container, wherein the dirty air stream is accelerated around the inner periphery of the container. The centrifugal acceleration caused by the travel of the fluid in a cyclonic stream through the cyclone causes the particulate matter to be disentrained from the fluid flow and, eg., to collect at the bottom of the container. A fluid outlet is provided for the extraction of the fluid from the centre of the top of the cyclone container, as is well known in the art.
A typical flow path in a cyclone separator is as follows. Fluid to be treated is introduced tangentially at a fluid inlet located at an upper end of the cyclone container. The fluid stream rotates around the inner surface of the cyclone container, and spirals generally downwardly around the inner surface of the container (if the cyclone container is vertically disposed). At a bottom end of the cyclone container the fluid stream travels radially inwardly, generally along the bottom of the container and then turns upwardly and proceeds vertically up and out of the cyclone container. The particulate matter separating action of the cyclonic flow occurs substantially around the inner surface of the container. Once the fluid moves inwardly to the centre of the container, and upwardly there through, there is little or no dirt separation achieved.
The difficulty experienced with prior art cyclonic separators is the reentrainment of the deposited particles back into the outgoing fluid flow. Deposited particles exposed to a high speed cyclonic flow thereover have a tendency to be reentrained. This is particularly problematic when the container has a solid bottom portion in which the dirt collects. However, there is a potential reentrainment problem even if the bottom of the container has a passageway provided in the bottom thereof to convey the separated particulate material away from the container.
If a high degree of separation is required, it is known to connect a plurality of cyclones in series. While using several cyclones in series can provide the required separation efficiency, it has several problems. First, if the separators are to be used in industry, they generally need to accommodate a high flow rate (eg. if they are to be used to treat flue gas). The use of a plurality of cyclones increases the capital cost and the time required to manufacture and install the separators. Further, the use of a plurality of cyclones increases the space requirements to house the cyclones. Accordingly, there is a need for an improved anti-reentrainment means for cyclonic separators.
SUMMARY OF THE INVENTION
In has now been discovered that a single cyclone having improved efficiency (eg. up to 99% efficiency) may be manufactured by positioning in the cyclone chamber a particle separation member for creating a dead air space beneath the cyclonic flow region of the cyclone chamber wherein the dead air space is in communication with the cyclonic flow region by a plurality of openings in the particle separation member. Baffles or the like may be provided in the dead air space to prevent cyclonic flow therein. This construction effectively traps separated material beneath the cyclonic flow region and inhibits the reentrainment of the separated material. Thus, a single cyclone may be used in place of a plurality of cyclones to achieve the same separation efficiency. The cyclone has an access member associated with the particle separation member whereby the particulate matter that accumulates on top of the particle separation member and the material that accumulates in the dead air space may be simultaneously emptied by inverting the cyclone chamber a sufficient amount so that the top of the cyclone chamber faces downwardly.
In accordance with the instant invention, there is provided a separator for separating entrained particles from a fluid flow, the separator comprising, a cyclone chamber having a cyclonic flow region, a fluid inlet for introducing a fluid flow to the cyclonic flow region wherein the fluid flows cyclonicly, a fluid outlet for removing the fluid flow from the cyclone chamber, a particle separation member positioned beneath the cyclonic flow region, a particle receiving chamber disposed beneath the particle separation member for receiving particles separated from the fluid flow, and, an access member associated with the separator, the access member moveable between a closed position and an open position in which the access member is displaced to provide an opening for emptying the particle receiving chamber.
In one embodiment, the access member forms part of the particle separation member and, when in the open position, provides an opening between the particle receiving chamber and the cyclone chamber. The access member is preferably freely moveable between its open and closed positions whereby the access member moves to its open position when the chamber is inverted.
In another embodiment, the access member has a connecting portion which is pivotally connected to the particle separation member. A weighted member may be connected to the access member at a position spaced from the connecting portion.
In another embodiment, the access member and the particle separation member form a surface that underlies all of the cyclonic flow region. The particle separation member is preferably a disc shaped and comprises a main body portion and the access member. The access member preferably comprises a chord section of the particle separation member.
The separator may be used in an upright vacuum cleaner. Accordingly, the separator may further comprise a cleaner head adapted for movement over a floor and having a fluid nozzle positionable adjacent the floor, the nozzle in fluid flow communication via a passageway with the separator fluid inlet, a handle for moving the cleaner head over the floor, and a casing for housing the cyclone chamber. The casing is preferably pivotally mounted to the cleaner head. The separator may be used in a canister or a central vacuum cleaner. Accordingly, the passageway may further comprise a flexible portion that is positioned external of the cleaner head and the casing and the handle is affixed to the cleaner head.
In another embodiment, the access member is pivotally mounted to the particle separation member about a pivot axis and the pivot axis is at an angle to the casing rotation axis when the casing rotation axis is projected to lie in a plane defined by the particle separation member adjacent the pivot axis. The angle may vary between 10° and 50° and is preferably 30°.
In another embodiment, the cleaner head has a forward portion and a rearward portion and the cyclone chamber has a central portion and a substantial portion of the access member is disposed rearward of the central portion. Preferably essentially all of the access member is disposed rearward of the central portion.
In accordance with the instant invention, there is also provided a separator for separating entrained particles from a fluid flow, the separator comprising a cyclone chamber for containing a cyclonic flow in a cyclonic flow region, means for introducing a fluid flow to the cyclonic flow region for cyclonic rotation therein, means for removing the fluid flow from the cyclone chamber, particle receiving means disposed beneath the cyclone chamber for receiving particles separated from the fluid flow, separation means for dividing the particle receiving means from the cyclone chamber, transporting means associated with the separation means for connecting the particle receiving means in flow communication with the cyclonic flow reg
Conrad Wayne Ernest
Petersen Dave
G.B.D. Corp.
Hopkins Robert A.
Reed Smith Hazel & Thomas LLP
Simmons David A.
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