US2653755A - Erosion resisting fan wheel - Google Patents

Description

Sept. 29, 1953 E, KRUHM|N EROSION RESISTING FAN WHEEL Filed June 26, 1952 Patented Sept. 29, 1953 2,653,755 n EROSION RESISTING FAN WHEEL Ernest Kruhmin, Hyde Park, Mass., assigner to Westinghouse Electric Corporation, East Pittsburgh, Pa., a corporation of Pennsylvania Application June 26, 1952, Serial No. 295,665

(Cl. 23o-134) 3 Claims.

This invention relates to centrifugal fans of the induced draft type which handle gases containing abrasive particles.

In steam power plants, induced draft fans handle large volumes of ilue gases travelling at high velocities. Such iiue gases contain cinders and fly ash which are abrasives and which erode the fan blades. For limiting such erosion it has been the practice to cut out portions of the center plates of the wheels of double inlet fans adjacent the advancing sides of the fan blades. and to provide liners on the fan blades which can be removed after a period of use, as disclosed in the T. B. Allardice Patent No. 2,287,853.

Such a construction has been successful in protecting the main surfaces of the fan blades, but experience has shown that severe erosion occurs in the fan blades where they are attached to the center plates, and in the liners adjacent the same areas. The blades have flanges, sec tions of which extend perpendicular to corresponding sections of the main blade portions, and which are riveted to the center plates. Small crevices occur between the center plates and the flanges where the latter extend outwardly from the center plates, along the total length of the flanges. Such crevices extend throughout their lengths in the same general direction as the abrasive laden gas passing through the fan wheels so that the abrasives enter the crevices and progressively widen them by eroding the adjacent portions of the center plates and the blade ilanges, until the blades have to be replaced. This same action occurs where the liners pass over the center plates and the blade anges since there are small clearance spaces between the liners, the center plates and the blade flanges, into which the abrasive material can enter. The heads of the rivets which attach the blade flanges to the center plate are also eroded.

This invention prevents such erosion by providing slots in the center plates inwardly of the inner ends of the blade flanges, and by providing in such slots wearing plates which extend across the path of the gas which would otherwise enter such crevices and clearance spaces, and which otherwise would pass over the heads of the rivets which attach the blade flanges to the center plate.

An object of this invention is to prevent abradouble inlet fan having a center plate to which the fan blades are attached, from eroding the blades and the center plate at the center plate.

Another objechof the invention is to prevent in a double inlet fan wheel having a center plate to which the fan blades are attached, and having protective liners on the blades which pass across the center plate, abrasive particles carried by a gas through the wheel, from eroding the center plate, the blades and the liners adjacent where the blades are attached to the center plate.

The invention will now be described with reference to the drawing, of which:

Fig. 1 is a side elevation, with a portion broken away, of a fan wheel embodying the invention;

Fig. 2 is a sectional view along the lines 2-2 of Fig. 1;

Fig. 3 is an enlarged fragmental view of the center plate of Figs. l and 2, with one blade, one liner and one protective plate shown, and

Fig. 4 is a sectional view along the lines 4-4 of Fig. 3.

The hub 9 on the shaft IQ has attached thereto by spot welding, the center plate I 2 and its braces I3 and I4. The center plate is cut away in front of the advancing side of each blade for providing the substantially V-shaped openings II which permit the oppositely directed streams of gas from the two inlets of the wheel, to impinge upon each other except where the blades are attached to the center plate. The blades I5 have the flanges I6 which are riveted at I1 to portions of the center plate between the openings II, and which are riveted at I 8 to the inlet plates I9, the latter being welded at 20 to the inlet rings 2 I.

The Wheel illustrated is designed to rotate in a counterclockwise direction with reference to Figs. l and 3 of the drawings, the blades I5 being of the backwardly inclined, forwardly curved type. The liners 22 are riveted at 23 to the advancing sides of the blades, and are shown at the center of the wheel where erosion of the main working surfaces of the blades is most severe, but could be used to cover all of the main working surfaces. The liners 22 have the portions 24 which are bent over across the inner edgesy of the blades I5 which aid in supporting the blades against the strains developed by centrifugal force. The liner portions 24 are notched at 25 to clear the center plate and the blade anges I6.

The construction described so far with reference to the drawings, is conventional and is essentially that disclosed in said Allardice patent.

It will be noted with reference to Fig. 4 of the drawings, that there are crevices 26 between the 3 anges I6 and the center plate I2 where the blades are bent outwardly perpendicular to these anges, such crevices being unavoidable in quantity production because of the tendency of bent sheet metal to have rounded bends. It will also be noted that there are clearances 21 between the liner 22 and the center plate where the liner is notched. SuchA crevicesand clearances are in the path of abrasives in thegas moved by theblades, which abrasives work their way into the crevices and clearance spaces and by erosion, enlarge the crevices until sucient of the blades and. center plate is eroded away to require replacement. The' heads of the rivets l1 are in the-gas streamand.

are subject to erosion.

This invention prevents such. erosion by pro-- viding the slots 28 in the center. plate I2. at the apices of the V-shaped openings' l'l`, one side of each slot being a continuation* of a straight back edge 29 of an opening Il, and the other side of the. slot being parallel to said.. one side thereof, at the inlet edge or" the associated fan blade. A wearing, plate 35. having arr outer portion 3| turned-over the follow the outlinevof, and. to lie against, the inner portion of a. liner 22 is placed in each of the. slots 23. Eachi plate is welded at 32 to a liner 22, and at 33. to an edgeofa slot 23'.

Such wearing plates extend across the inner or inletends of the crevices 2 and Z6 and provide barriers preventing entry of any abrasive material into. the crevices and clearance spaces, and from contacting the heads of the rivets Il..

By eliminating the erosion of the center plates of fan wheelaof the fan blades where they are attached to the center plates andof the rivets which attach the blades to the center plates, the lives of fan wheels handling gases containing brasive particles, are greatly extended.

While one embodiment of the invention has been described for the purposeof illustration,. it' should be understood that the invention is. not limited to the exact apparatus and arrangement of' apparatus described, since modiiications thereof may be suggested by4 those skilled' in the art without departure from the essence of. the invention.

What I claim as my invention, is:

i'. A fan wheel for a double inlet centrifugal' fan comprising a center plate; said wheel having gas. inlet passages on opposite sides of the ,enter platea plurality. of fan'olades around. said inlet passages; each blade' having two sections with main working portions extending in alignment axially outwardly from opposite sides` of.

said center plate, and with flanged inner portions attached to said center plate behind the main working portions; said center plate having portions removed at the front sides ci said blades for providing openings for permitting the oppositely flowing streams of gas moved by said blades to impinge, said center plate having slots extending from said openings past the edges of said blades' nearest said passages, and protective plates having portions in said slots and having portions extending from said slots into said openings past Said blade edges for preventing abrasiveparticles'in the gas from said passages from entering the spaces between said center plate and; said blades where said main working portions join said flanged portions.

2. A fan wheel for a double inlet centrifugal fan comprising' a center plate; said wheel having gasf inlet passages on opposite sides of the center plate, a plurality of fan blades around said. inlet passages; suchblade having two sections with. main working portions extending in alignment axially outwardly from opposite sides of said center plateand with iianged inner portions. attached to said center plate behind the main working portions; said center plate having, portions removed at the front sides of said blades for providing openings for permitting the oppositelyv flowing streams of gas moved by said blades to impinge; protective liners on the front sides of said blades common to both blade sections andv extending across said center plate adjacent where said hanged blade portions are attached to. said center plate; said center plate having slots extending from said openings past the edges of said blades nearest said passages, and protective plates having portions in said slots and having portions extending from said slots into said. openings past said blade edges and said liners for preventing abrasive particles in the gas from said passages from entering the spaces bet-Weensaid center plate and said blades where. said main working portions join said il'anged portions, and from entering the spaces between said center plate and said liners where saidv liners cross said center plate.

3;.A fanwheel as claimed in claim 2 in which the, portions of said protective plates extending. from said slots into said openings past said blade edges and said liners, have portions bent over against said liners.

ERNEST KRUHMIN.

No references cited.

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