Title:
SCROLL WASHER FOR CENTRIFUGAL FANS
United States Patent 3796509
Abstract:
This invention relates to a centrifugal fan having a rotating fan wheel and means for removing centrifuged particulate matter from the interior wall of the fan scroll. A conduit, capable of carrying a fluid under pressure, is provided with a plurality of perforations so that jets of water may be applied to the inside surface of the scroll to dislodge and maintain the particulate matter in a fluidized state to enable the matter to be removed from the scroll by a suitable drain. The conduit is disposed adjacent the inner surface of the scroll and aligned substantially transversely with respect to the direction of rotation of the fan wheel.
US Patent References:
Fan
Freed - August 1936 - 2050523
Gas purifying turbine plant
Noack - July 1942 - 2288734
Flushing means for centrifugal pumps
White - March 1945 - 2372538
Wet separator for purifying a particle laden gas current
Blomen - May 1952 - 2598032
Means for preventing the accumulation of ice or other solids in ducts
Stanton - April 1961 - 2978169
Fan
Freed - August 1936 - 2050523
Gas purifying turbine plant
Noack - July 1942 - 2288734
Flushing means for centrifugal pumps
White - March 1945 - 2372538
Wet separator for purifying a particle laden gas current
Blomen - May 1952 - 2598032
Means for preventing the accumulation of ice or other solids in ducts
Stanton - April 1961 - 2978169
Application Number:
05/251995
Publication Date:
03/12/1974
Filing Date:
05/10/1972
View Patent Images:
Export Citation:
Assignee:
Westinghouse Electric Corporation (Pittsburgh, PA)
Primary Class:
Other Classes:
134/104.400, 96/324, 134/169R, 415/121.200, 415/169.200, 134/104.100
International Classes:
F04D29/70; F04D29/00; F04D31/00
Field of Search:
415/116,121A,121R 55/DIG.40,240,241,223,238,242 134/104,115R,166R,169R
US Patent References:
Primary Examiner:
Husar C. J.
Attorney, Agent or Firm:
Blake F. E.
Claims:
1. A centrifugal fan having a scroll member against the interior surface of which particulate matter may be centrifuged, said scroll having a finite width defined along a length, a fan wheel supported for rotation by a shaft, said shaft extending axially in the direction of said scroll width, and a conduit capable of transporting a fluid under pressure, said conduit disposed adjacent the inner surface of said scroll and having means whereby said fluid may be jetted in the direction of rotation of said fan wheel with sufficient force against said interior surface to dislodge the centrifuged particulate matter therefrom and to thereby maintain said matter in a fluidized state, said conduit being aligned generally in the same direction as said fan wheel shaft and substantially transversely with
2. The invention of claim 1, wherein the scroll of said fan has a cut-off
3. The invention of claim 1, wherein said conduit is a pipe cut-off for
4. The invention of claim 1, wherein said fluid carrying conduit is extended axially and completely through said fan scroll in the direction of said scroll width.
2. The invention of claim 1, wherein the scroll of said fan has a cut-off
3. The invention of claim 1, wherein said conduit is a pipe cut-off for
4. The invention of claim 1, wherein said fluid carrying conduit is extended axially and completely through said fan scroll in the direction of said scroll width.
Description:
CROSS REFERENCES TO RELATED APPLICATIONS
So far as known, this invention is not related to any pending patent application.
BACKGROUND OF THE INVENTION
A major problem with centrifugal fans, such as a dust collector scrubber fan, has been in preventing the buildup of particulate matter on the fan scroll. A gas passing through the fan scroll can be subjected to a centrifugal force many times the force of gravity which may cause dust and other particles to be separated out of the gas and centrifuged to the inside wall of the fan scroll. If such material is not removed, it may tend to cake and fall off into the rotating fan wheel resulting in possible damage.
It would therefore be desirable to employ conduit means for introducing a fluid under pressure into the gas passage formed by a centrifugal fan scroll in order to apply the fluid to the interior surface of the scroll with a sufficient jetting action to dislodge the centrifuged matter from the scroll and maintain the matter in a fluidized state to allow the sludge to be drained therefrom. It would also be desirable to dispose the conduit means adjacent the interior surface of the scroll and in a position whereby the fluid under pressure may be delivered to the interior scroll surface in the same general direction as that of the gases passing through the interior of the scroll.
PRIOR ART
The following patents show the general arrangement of a centrifugal air handling apparatus and conduit means to inject a fluid through the apparatus casing for the purpose of dislodging centrifuged matter from portions of the inside surface of the casing:
Nutting 2,195,707
Gilliam 2,688,376
Bullock 2,804,163
Percevaut 2,983,333
However, none of the above shows a centrifugal fan having fluid carrying conduit means disposed adjacent the inner surface of the fan scroll while being aligned generally in the direction of the scroll width and substantially transversely with respect to the direction of rotation of the fan wheel.
SUMMARY OF THE INVENTION
A centrifugal fan is disclosed having a scroll member and a fan wheel supported for rotation by a shaft. A conduit, capable of transporting a fluid under pressure, is disposed adjacent the inner surface of the scroll. In the preferred embodiment, the fluid carrying conduit is disposed at the existing pipe cut-off and may in fact, after a suitable modification thereto, be the existing pipe cut-off already present within the fan housing.
The fluid transporting conduit is axially aligned to be generally in the same direction as that of the shaft of the fan wheel and substantially transversely with respect to the direction of rotation of the fan wheel. The conduit may be modified, as in the preferred embodiment, to extend axially and completely through the area defined by the fan scroll and in the direction of the fan wheel shaft to enable fluid under pressure to be supplied to portions of the inner surface of the scroll from either end of the conduit.
A plurality of perforations are arranged laterally in the conduit so that fluid may be jetted with sufficient force against those portions of the interior surface of the scroll member likely to have a buildup of sludge thereby dislodging the particulate matter which has separated out of the air passing through the scroll and has been centrifuged thereon. The particulate matter may be maintained in a fluidized state and eventually drained from the scroll member by a suitable drain placed therein.
BRIEF DESCRIPTION OF DRAWINGS
FIG. 1 is an isometric, partially broke-away view of a centrifugal fan employing the present invention;
FIG. 2 is a partial section taken along lines II--II of FIG. 1; and
FIG. 3 is a fragmentary front elevation of FIG. 1.
DESCRIPTION OF PREFERRED EMBODIMENT
Referring to FIG. 1 of the drawings, a centrifugal fan 1 is shown. Fan 1 is adapted to receive a gas through an inlet opening 2 extending axially and in the direction of arrow W. A fan wheel, shown generally at 4, having a plurality of conventional fan blades 6 is supported for rotation by means of shaft 8. Shaft 8, also extending in an axial direction as defined by the direction of inlet opening 2 and arrow W, is supported by hub 9 and from any suitable support means 30 as shown by FIG. 3. Fan 1 is provided with a scroll plate member 10. Scroll 10 has a finite width (in the direction of arrow W) defined along a length and forms a curved involute gas flow path 11 through which a gas being passed may be subjected to centrifugal forces several times the force of gravity. Discharge conduit 14 is arranged to provide a tangential outlet for the gases after they have been circulated through flow path 11.
As may frequently be the case in centrifugal fans, such as those of the dust scrubber type for example, dust and other particulate matter contained within the gas subjected to the high centrifugal forces, may separate out from the gas passing through curved flow path 11 and become centrifuged against the inner surface 12 of scroll plate 10. If this formation of particulate matter is allowed to continue to exist around the inner scroll surface 12, sludge may cake up thereon and subsequently fall into the moving fan wheel 4 resulting in possible damage.
To eliminate the possibility of particulate matter buildup on the inner scroll surface 12, a conduit 16, capable of carrying a fluid under pressure, is introduced into the scroll flow path 11. In accordance with the instant invention, fluid carrying conduit 16, is disposed through flow path 11 at a point adjacent to the scroll interior wall 12 and in the direction of the scroll width W. In the preferred form of the invention, conduit 16 is located as the existing pipe cut-off 19, already present in the fan housing. Also in the preferred form, conduit 16 extends completely through flow path 11 in the same general direction as both the scroll member width and the axially projecting fan shaft 8. Thus, conduit 16 can be aligned substantially transversely with respect to the direction of rotation of fan wheel 4, the advantages of which will be explained hereinafter. By extending conduit 16 completely through flow path 11, fluid can be supplied through the conduit from either end with control means provided by any suitable valve arrangement 20.
A plurality of laterally arranged perforations 18 is cut into the fluid carrying conduit 16. These perforations 18, provide means whereby the fluid, by a jetting action and with a sufficient force, may be directed against a portion of the interior surface 12 of scroll plate member 10 so as to dislodge the centrifuged particulate matter therefrom and maintain the matter in a fluidized state for evenutal removal from within the scroll member by means of any suitable drain, shown generally at 22 of FIG. 3. By aligning conduit 16 substantially transversely with respect to the direction of rotation of the fan wheel 4, sludge will be forced around the scroll in the same general direction as the gas flow, and the kinetic energy of the water jets will tend to add to the acceleration of the gas (shown in greatest detail by FIG. 2).
Although in the preferred embodiment, the fluid carrying conduit is disposed at the existing pipe cut-off or may in fact be the existing pipe cut-off to extend into the fan scroll in the same direction as the fan wheel shaft, it is also within the scope of the invention to dispose the fluid carrying conduit at locations other than at the fan cut-off. Any position within the fan scroll in which the fluid carrying conduit is disposed adjacent the inner surface of the scroll member while in a general alignment with the axial direction of the fan wheel shaft and in a substantially transverse direction to the direction of rotation of the fan wheel is considered a modification within the scope of the instant invention. In the preferred embodiment, the fluid carrying conduit extends axially and completely through the fan scroll in the direction of the scroll width enabling fluid to be supplied through either end of the conduit. It is also considered within the scope of this invention to extend the conduit only partially through the fan scroll and in the direction of the scroll width. Other modifications will occur to those skilled in the art.
So far as known, this invention is not related to any pending patent application.
BACKGROUND OF THE INVENTION
A major problem with centrifugal fans, such as a dust collector scrubber fan, has been in preventing the buildup of particulate matter on the fan scroll. A gas passing through the fan scroll can be subjected to a centrifugal force many times the force of gravity which may cause dust and other particles to be separated out of the gas and centrifuged to the inside wall of the fan scroll. If such material is not removed, it may tend to cake and fall off into the rotating fan wheel resulting in possible damage.
It would therefore be desirable to employ conduit means for introducing a fluid under pressure into the gas passage formed by a centrifugal fan scroll in order to apply the fluid to the interior surface of the scroll with a sufficient jetting action to dislodge the centrifuged matter from the scroll and maintain the matter in a fluidized state to allow the sludge to be drained therefrom. It would also be desirable to dispose the conduit means adjacent the interior surface of the scroll and in a position whereby the fluid under pressure may be delivered to the interior scroll surface in the same general direction as that of the gases passing through the interior of the scroll.
PRIOR ART
The following patents show the general arrangement of a centrifugal air handling apparatus and conduit means to inject a fluid through the apparatus casing for the purpose of dislodging centrifuged matter from portions of the inside surface of the casing:
Nutting 2,195,707
Gilliam 2,688,376
Bullock 2,804,163
Percevaut 2,983,333
However, none of the above shows a centrifugal fan having fluid carrying conduit means disposed adjacent the inner surface of the fan scroll while being aligned generally in the direction of the scroll width and substantially transversely with respect to the direction of rotation of the fan wheel.
SUMMARY OF THE INVENTION
A centrifugal fan is disclosed having a scroll member and a fan wheel supported for rotation by a shaft. A conduit, capable of transporting a fluid under pressure, is disposed adjacent the inner surface of the scroll. In the preferred embodiment, the fluid carrying conduit is disposed at the existing pipe cut-off and may in fact, after a suitable modification thereto, be the existing pipe cut-off already present within the fan housing.
The fluid transporting conduit is axially aligned to be generally in the same direction as that of the shaft of the fan wheel and substantially transversely with respect to the direction of rotation of the fan wheel. The conduit may be modified, as in the preferred embodiment, to extend axially and completely through the area defined by the fan scroll and in the direction of the fan wheel shaft to enable fluid under pressure to be supplied to portions of the inner surface of the scroll from either end of the conduit.
A plurality of perforations are arranged laterally in the conduit so that fluid may be jetted with sufficient force against those portions of the interior surface of the scroll member likely to have a buildup of sludge thereby dislodging the particulate matter which has separated out of the air passing through the scroll and has been centrifuged thereon. The particulate matter may be maintained in a fluidized state and eventually drained from the scroll member by a suitable drain placed therein.
BRIEF DESCRIPTION OF DRAWINGS
FIG. 1 is an isometric, partially broke-away view of a centrifugal fan employing the present invention;
FIG. 2 is a partial section taken along lines II--II of FIG. 1; and
FIG. 3 is a fragmentary front elevation of FIG. 1.
DESCRIPTION OF PREFERRED EMBODIMENT
Referring to FIG. 1 of the drawings, a centrifugal fan 1 is shown. Fan 1 is adapted to receive a gas through an inlet opening 2 extending axially and in the direction of arrow W. A fan wheel, shown generally at 4, having a plurality of conventional fan blades 6 is supported for rotation by means of shaft 8. Shaft 8, also extending in an axial direction as defined by the direction of inlet opening 2 and arrow W, is supported by hub 9 and from any suitable support means 30 as shown by FIG. 3. Fan 1 is provided with a scroll plate member 10. Scroll 10 has a finite width (in the direction of arrow W) defined along a length and forms a curved involute gas flow path 11 through which a gas being passed may be subjected to centrifugal forces several times the force of gravity. Discharge conduit 14 is arranged to provide a tangential outlet for the gases after they have been circulated through flow path 11.
As may frequently be the case in centrifugal fans, such as those of the dust scrubber type for example, dust and other particulate matter contained within the gas subjected to the high centrifugal forces, may separate out from the gas passing through curved flow path 11 and become centrifuged against the inner surface 12 of scroll plate 10. If this formation of particulate matter is allowed to continue to exist around the inner scroll surface 12, sludge may cake up thereon and subsequently fall into the moving fan wheel 4 resulting in possible damage.
To eliminate the possibility of particulate matter buildup on the inner scroll surface 12, a conduit 16, capable of carrying a fluid under pressure, is introduced into the scroll flow path 11. In accordance with the instant invention, fluid carrying conduit 16, is disposed through flow path 11 at a point adjacent to the scroll interior wall 12 and in the direction of the scroll width W. In the preferred form of the invention, conduit 16 is located as the existing pipe cut-off 19, already present in the fan housing. Also in the preferred form, conduit 16 extends completely through flow path 11 in the same general direction as both the scroll member width and the axially projecting fan shaft 8. Thus, conduit 16 can be aligned substantially transversely with respect to the direction of rotation of fan wheel 4, the advantages of which will be explained hereinafter. By extending conduit 16 completely through flow path 11, fluid can be supplied through the conduit from either end with control means provided by any suitable valve arrangement 20.
A plurality of laterally arranged perforations 18 is cut into the fluid carrying conduit 16. These perforations 18, provide means whereby the fluid, by a jetting action and with a sufficient force, may be directed against a portion of the interior surface 12 of scroll plate member 10 so as to dislodge the centrifuged particulate matter therefrom and maintain the matter in a fluidized state for evenutal removal from within the scroll member by means of any suitable drain, shown generally at 22 of FIG. 3. By aligning conduit 16 substantially transversely with respect to the direction of rotation of the fan wheel 4, sludge will be forced around the scroll in the same general direction as the gas flow, and the kinetic energy of the water jets will tend to add to the acceleration of the gas (shown in greatest detail by FIG. 2).
Although in the preferred embodiment, the fluid carrying conduit is disposed at the existing pipe cut-off or may in fact be the existing pipe cut-off to extend into the fan scroll in the same direction as the fan wheel shaft, it is also within the scope of the invention to dispose the fluid carrying conduit at locations other than at the fan cut-off. Any position within the fan scroll in which the fluid carrying conduit is disposed adjacent the inner surface of the scroll member while in a general alignment with the axial direction of the fan wheel shaft and in a substantially transverse direction to the direction of rotation of the fan wheel is considered a modification within the scope of the instant invention. In the preferred embodiment, the fluid carrying conduit extends axially and completely through the fan scroll in the direction of the scroll width enabling fluid to be supplied through either end of the conduit. It is also considered within the scope of this invention to extend the conduit only partially through the fan scroll and in the direction of the scroll width. Other modifications will occur to those skilled in the art.