US2269520A - Fan wheel - Google Patents

Description

J. CRITES Jan. 13, 1942.

FAN WHEEL Filed Dec 18, 1939 2 Sheets-Sheet l 9 [his Jan. 13, 1942. v c s I 2,269,520

F @f E'1: D) K "o a Imlen'rr "\l KMRM Patented Jan. 13, 1942 FAN WHEEL Joe Crites, Evanston, Ill., assignor to Combustion Engineering Company, Inc., New York, N. Y., a corporation of Delaware Application December 18, 1939, Serial No. 3093865 Claims.

This invention is directed to new and useful improvements in fan wheels of the impeller or blower type used in directing finely pulverized material from one point toanother by means of an air stream.

Usually such material is received by the blower directly from a grinding mill through an appropriate conduit leading to the center of the blower. Thereupon the material impinges upon the leading faces of the rotating blower blades and is directed thereby to the outer portion of the casing of the fan and from there is carried generally tangentially by the air stream to the desired point of delivery. The constant contact of the material against the fan blades causes an appreciable amount of erosion necessitating replacement of the blades at frequent intervals which is expensive and troublesome.

It is the primary object of this invention to provide a fan wheel of the type mentioned fitted with auxiliary protective members removably positioned on the blades of the blower which will absorb the wear caused by the material impinging upon the leading faces of the blower blades.

A further object of this invention is to provide such supplement protective members that will cause the material to be delivered to the outer portion of the fan casing with less force than if delivered by the main fan blades and with less power required, thus effecting a material saving in operation and maintenance.

Further objects and advantages will become apparent from the following detailed description.

In the drawings:

Fig. l is a section view taken from one side of a fan embodying this invention.

Fig. 2 is a section view taken along line 2-Z of Fig. 1.

Fig. 3 is an enlarged cross section view taken along line 3-3 of Fig. 1.

Fig. 4 is a side section of another embodiment of this invention.

Fig. 5 is a section view taken along line 5-5 of Fig. 4.

Fig. 6 is a perspective view of supplemental cone and protective members shown in Figs. 4 and 5.

In detail, I indicates an elbow of a conduit leading from a source of pulverized material suspended in air (not shown) to entrance 2 of fan casing 3 in which is positioned the fan wheel comprising open blades 4 (as opposed to blades enclosed by annular plates secured to their edges) secured to hub 5 by means of arms an outlet 6, shown in Fig. 2, which leads to the desired point of delivery. Secured to the leading faces of fan blades 4 and adjacent the material receiving edges of said blades are replaceable protective members 1. Each such member comprises a face 8 positioned on the leading face of a blade and parallel thereto and a face 9 extending in the direction of rotation of the wheel and at substantially a right angle to face 8. Rivets 10 positioned through an extension ll, of face 9 removably secure the members 1 to the blades 4. The type of angle member 1 shown in Figs. 1 and 2 comprises a substantially inverted T piece. one arm of the T being face 8, the other'arm I l, afi'ording means through which the member is secured. to the blade. Obviously other forms could be used such as an L-angle, in which case the securing means would extend through the face of the angle: abutting and paralleling the leading face of the blade. The blades 4 are shaped to provide ear portions l-2 to which the auxiliary blades 1 are secured so that the outer ends of blades 4 are spaced from the outer ends of the auxiliary replaceablemembers.

Another embodiment of this invention is i1- lustrated in Figs. 4,. 5- and 6. Instead of the auxiliary blade members I as hereinabove described there is substituted a. cone-shaped plate member T3 of slightly greater diameter than the diameter of the entrance 2 to the fan casing, which cone member is secured to the edges of the fan wheel blades 4 and is provided with a central air opening. This cone-shaped plate member I3 provides a gentle curve from a point adjacent the outer edge of entrance 2 inwardly and radially. Removably secured to cone l3 are supplemental fan blades I 4 that terminate adjacent the outer edge of cone member l3, and short of the outer ends of fan blades 4. Cone [3 may be secured to the blade edges in any desired manner such, for example, as welding or riveting by means of angle pieces.

In operation the material is carried suspended in an air stream to elbow I, Fig. 1. The heavier material, due to centrifugal force, hugs the outer side of the elbow and is directed into the fan casing where the outer portion of the elbow joins it. The fan wheel is rotating rapidly in the direction indicated by the arrow. The faces 9 of auxiliary members I thus present an opposing surface upon which the material will impinge at first. Because of the rotating blades the material is forced against faces 8 and then the centrifugal force causes the material to Ed and bolts 5b. The casing 3 is provided with move radially toward the ends of the auxiliary members, from which it is delivered to the easing. The rapidly rotating blades 4 then blow the material from the casing to the desired point. In this manner it can be clearly seen that the main blower blades 4 are protected from wear and that whenever the auxiliary members become worn they may be readily and inexpensively replaced.

Furthermore, it can be seen that because of the shape of the main blades 4 in providing ear portions 12 to which the auxiliary members are attached and from which the remaining parts of the blades are spaced the material is delivered to the outer portion of easing 3 at a speed less than if delivered by main blades 4 because the distance from the center of rotation to the outer ends of blades 1 is less than the distance from the center of rotation to the outer ends of main blades 4. Thus the wear on casing 3 is diminished and less power is required to move the material although the speed of the fan wheel is the same.

The operation of structure shown in Figs. 4, 5 and 6 is similar excepting only that material directed into fan casing from'elbow I impinges directly upon the face of cone member l3 from which it is directed to the outer portion of the casing by supplemental blades M, the outer ends of which are likewise spaced from the main blower blades.

I claim:

1. A fan wheel assembly for receiving ground material in air delivered to it axially and for delivering the material under pressure comprising open main blades, a material receiving plate having a central air opening secured to the material receiving edges of the blades and adapted to impede the axial movement of the delivered material, supplemental blade members secured to the said plate the outer ends of which terminate short of the outer ends of the main blades, and a common housing for both main blades and supplemental members having a single inlet for air and material adjacent and coaxial with said receiving plate.

2. A fan wheel assembly for receiving ground material in air delivered axially comprising open main blades, a casing having a single air and material entrance adjacent the axis of the fan, a cone member secured to the edges of the blades adjacent the entrance and provided with a central air inlet, supplemental blades secured to the cone member the outer ends of which terminate short of the outer ends of the main blades, said casing enclosing said assembly.

3. A fan wheel assembly for receiving material suspended in air axially and delivering it under pressure comprising a hub, open blades secured to the hub, a casing surrounding the blades and provided with an entrance adjacent the hub, an elbow conduit leading to the entrance, and a blade protective plate provided with a central opening positioned to rotate with the blades adjacent and opposite the zone where the outer surface of the elbow joins the casing to present a material im peding surface, and supplemental blades shorter than the main blades mounted on said surface of said plate.

4. A fan wheel assembly for receiving ground material in air under pressure delivered to it axially and for delivering such material under pressure comprising open main blades, protective means for the blades secured to the blades adjacent the material receiving side of the fan, said means comprising a plate with a material receiving surface and a central air inlet, supplemental blades extending from said surface and terminating short of the outer ends of the main blades, a common housing for the whole assembly provided with a common inlet through which material is delivered and from which the fan wheel receives its air supply through the central inlet of said plate.

5. A fan wheel assembly for receiving ground 1 material and air delivered to it axially and for blades nearest the said entrance to rotate with the main blades opposite the entrance and presenting a material receiving surface adapted to impede the axial movement of the delivered material, replaceable supplemental blades carried by said member and terminating short of the outer ends of the main blades, a common outlet for said wheel assembly, said entrance providing the air for the fan and the inlet for the material.

JOE CRITES.

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