Gas separation: processes – Deflecting – Centrifugal force
Reexamination Certificate
1999-07-27
2001-04-24
Simmons, David A. (Department: 1724)
Gas separation: processes
Deflecting
Centrifugal force
C055S426000, C055S429000, C055S433000, C055S459100, C055SDIG003
Reexamination Certificate
active
06221134
ABSTRACT:
FIELD OF THE INVENTION
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 therethrough, 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 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 member. The openings are provided on the radial outer portion, the radial inner portion or both the radial outer portion and the radial inner portion of the member. 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.
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 an outer wall and a cyclonic flow region, the cyclonic flow region having a radial width, an outer peripheral portion, a medial portion disposed interior of the peripheral portion and an inner portion disposed interior of the medial portion, a fluid inlet for introducing a cyclonic fluid flow to the cyclonic flow region, a fluid outlet for removing the fluid flow from the cyclone chamber, a particle separating member positioned in the cyclone chamber beneath at least a portion of the cyclonic flow region, the particle separating member having a plurality of apertures, and a particle receiving chamber disposed beneath the particle separating member for receiving particles passing into the particle receiving chamber through the apertures wherein the apertures are disposed on the particle separating member such that the medial portion of the cyclonic flow region is substantially free from said apertures.
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 one embodiment, the apertures are sized to inhibit elongate particles from passing there through, whereby elongate particles collect on top of the particle separating member.
In another embodiment, the apertures are shaped to aerodynamically direct particles from the cyclonic flow region into the particle receiving chamber.
The particle separating member may extend under all of the cyclonic flow region to define bottom surface of the cyclonic flow region. Alternately, it may extend only under that portion of the cyclonic flow region in which the apertures are to be provided. For example, the particle separating member may extend essentially under only the outer peripheral portion, the inner portion or both the peripheral and inner portions of the cyclonic flow region.
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, the cyclonic flow region having a radial width, an outer peripheral portion, a medial portion disposed interior of the peripheral portion and an inner portion disposed interior of the medial portion, means for introducing a fluid flow to the cyclone flow region for cyclonic rotation therein, means for removing the fluid flow from the cyclone chamber, particle receiving means disposed beneath the cyclone flow region for receiving particles separated from the fluid flow, separation means for dividing the particle receiving means from the cyclone chamber, and transporting means associated with the separation means for connecting the particle receiving means in flow communication with the cyclonic flow region such that, in operation, particles pass through the transporting means to the particle receiving means wherein said transporting means are positioned outside the medial portion of the cyclonic flow region.
In one embodiment, the particle receiving means comprises a sealed chamber except for the transporting means and the separator further comprises emptying means for emptying the particle receiving means.
In another embodiment, the separator further comprises means for connecting the particle receiving means in flow communication with a conduit for transporting separated particles downstream from the particle receiving means.
In another embodiment, the separator further comprises
Conrad Wayne Ernest
Petersen Dave
G.B.D. Corp.
Hopkins Robert A.
Reed Smith Hazel & Thomas LLP
Simmons David A.
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