US3347740A - Method and apparatus for purging travelling felts - Google Patents

Description

Oct. 17, 1967 G. I. GOUMENIOUK METHOD AND APPARATUS FORPURGING TRAVELLING FELTS 2 Sheets-Sheet 2 Filed Oct. 14, 1963 INVENTOR.

l. GOUMENIOUK GLEB United States Fatent G 3,347,740 METHOD AND APPARATUS FOR PURGING TRAVELLING FELTS Gleb I. Gourneniouk, West Vancouver, British Columbia,

Canada, assignor to Rice Barton Corporation, Worcester, Mass.

Filed Oct. 14,1963, Ser. No. 316,044 10 Claims. (Cl. 162199) This invention relates to for purging travelling making industry.

The main object of the present invention is the provision of method and apparatus for cleaning and drying felts used in transferring, pressing and drying paper webs as they are dewatered and dried on a paper machine, in a simple and economical manner without interfering with the normal operation of the machine.

lthough the principles of the invention may be used wherever centrifugal force and the supply of purging or cleaning fluid may be used to alter and improve the condition of a rapidly moving web, the application of the principles has been specifically developed for the cleaning, conditioning and dewatering of the felts used in the manufacture of pulp and paper sheets, and is so described herein.

In the paper making industry, dewatering and transporting felts become loaded with excess water and other foreign substances, such as particles of pulp, and it is necessary, for the proper functioning of the machinery, to remove said excess water and other foreign substances as rapidly as possible. These felts normally have water in them to the extent of from roughly 20 to 50% of the weight of the felt, but during operation they absorb an excess of water which must be continuously removed a method of and apparatus felts, such as are used in the paper to enable the felts to function satisfactorily.

According to the present invention, the felt of a ma chine is moved around a curved member or surface of sufiiciently small radius at the operating speed of the machine to cause foreign substance, such as water and particles, to be flung under the action of centrifugal force from the felt during its passage around the small-radiused curve. If the radius is too large relative to the operating speed, the centrifugal action is not sufiicient to separate much or any of the foreign substance from the felt, since the tendency of such substance is to remain in the felt and to move with it. The smaller the radius, the better the action, but this is limited by practical considerations.

. If the radius of the curve is too small, the felt will be subjected to undue wear and strain. It has been found in practice that the radius can be made much smaller than would ordinarily be expected, as a result of supplying air under pressure to lift the felt off the Curved surface.

If the felt is travelling at high speed, say, for example, something of the order-of 3,000 feet per minute, the above-mentioned step without any admission of air produces appreciable results. However, this step is improved by simultaneously permitting air to enter the felt from the underside as the foreign substance is flung therefrom.

The latter step is essential for comparativelyslow-moving felts. It has been found that the foreign substance shows a reluctance to leave the felt under the action of centrifugal force alone because of the voids generated by their departure as the felt moves angularly over an unperforated curved surface. At high speeds, centrifugal force is sufficient to remove a fair percentage of the water and particles, whereas at slower speeds, it is necessary to provide means which enables air to enter the felt at the surface opposite the surface from which thewater 1 and particles are flung. In some circumstances, the method is improved by supplying air under pressure to the felt at the curved surface. This pressure is comparatively low,

but it may be increased effectively only to the point where the felt lifts off the curved surface, thereby reducing wear and strain on the felt. However, this pressure must not be sufiicient to cause the felt to swim or shift back and forth over the curved surface.

When air is made available to the underside of the moving felt, it must be at the area of the felt where the water is being flung therefrom in order that the air will take the place of the water, thereby eliminating the suction effect. In high speed operations, it is desirable to supply the air under sufficient pressure or supplied under pressure to just lift the felt off the contacting surface or surfaces of the device, in order to reduce the friction forces acting on the felt to a minimum. This prolongs the life of the felt, and reduces the horsepower required for a given operational speed.

Although various forms of apparatus may be used for carrying out the present method, special'apparatus has been designed for carrying out the method in an economical and satisfactory manner, and different embodiments of this invention are illustrated in the accompanying drawings, in which:

FIGURE 1 diagrammatically presents one use of the present purging apparatus, and illustrates one form of the invention,

FIGURE 2 is an enlarged vertical section through the purging apparatus of FIGURE 1,

FIGURE 3 is a horizontal sectional view taken substantially on theline 33 of FIGURE 2, with the felt omitted,

FIGURE 4 is a view similar to FIGURE 2 illustrating an alternative form of apparatus,

FIGURE 5 is another view similar to FIGURE 4 illustrating still another alternative form of apparatus,

FIGURE 6 is a diagrammatical vertical section through a further modification of the purging apparatus,

FIGURE 7 is a vertical section through yet another modification of the apparatus, and

FIGURE 8 is an enlarged horizontal sectional view taken on the line 8-8 of FIGURE 7, with the felt removed.

Referring to FIGURE 1 of the drawings, awet web 10 of paper passes together with an endless felt 12 betweenpress rolls 14, which squeeze water and other foreign substances, such as particles of pulp, from the paper web into the felt. The felt then passes around purgingapparatus 15 where water and other foreign substances are flung outwardly therefrom under the action of centrifugal force, with or without the assistance of air supplied to the undersurface of the felt.

The purgingapparatus 15 is illustrated in more detail in FIGURES 2 and 3, and the theory of operation is described in connection with these figures.Apparatus 15 is formed with acurved surface 17 around which felt 12 travels. In this example,apparatus 15 is in the form of atubular member 18 carried by supportingmembers 20 projecting from asuitable beam 21 which is preferably of box form so that it is strong in bending and in torsion. Thecurved surface 17 is formed with a plurality of perforations orholes 24 which extend longitudinally ofmember 18 throughout the portion thereof over which felt 12 travels. It will be noted in FIGURE 2 thatholes 24 extend circumferentially throughout the portion ofsurface 17 well around the bend with reference to the direction of travel of the felt, as indicated by arrow. 26; In other words, the holes start just above the horizontal plane and extends over thecurved surface 17. This coveris made of any suitable material, such as tetrafluoroethane plastic.Cover 28 is anchored at oneedge 29 tobeam 21, and it extends from this point aroundsurface 17 and is secured at itsopposite edge 30 to the beam. If desired, suitable means, not shown, may be provided at either or both of theedges 29 and 30 to maintaincover 28 under adjustable tension. This cover extends over the area ofsurface 17 over which felt 12 travels. The cover is formed with a plurality of perforations orholes 33 which partially or completely register withholes 24 in surface 17- During operation, felt 12 travels at comparatively high speed around thecurved surface 17 of purgingapparatus 15. As the felt travels around said surface, water and other foreign substances are flung under the action of centrifugal force in the direction ofarrows 37 into aneffluent pan 38. If felt 12 is travelling at extremely high speeds, say, for example, 3,000 f.p.m., considerable Water and other substances are flung therefrom even ifcurved surface 17 is solid. However, it is desirable to supply air to the undersurface of the felt so as to prevent the formation of voids therein as the water is flung outwardly therefrom. Therefore, it is preferable to provideholes 24 insurface 17, andholes 33 incover 28, if the latter is used. Improved results are attained if the air supplied to the undersurface of the felt is under pressure. In this case,tubular member 18 is closed byends 40, andpipes 41 open through said ends from apump 42, see FIGURES 1 and 3. In order to ensure a good distribution of the air withintubular member 18, it is preferable to extend theends 44 ofpipes 41 some distance intomember 18.

The pressure of the air supplied throughpipes 41 tomember 18 can be just suflicient to replace the water and other foreign substances which are flung from the felt passing overcurved surface 17. However, in order to help reduce the wear and strain on felt 12, it is preferable to supply the air under suflicient pressure to just lift the portion of felt 12 passing oversurface 17 off said surface. In this way, the felt actually travels over an air cushion as it passes oversurface 17. However, care must be taken that the pressure is not increased to the point where the felt tends to swim or shift laterally on the curved surface. The pressure required for proper operation is function of the speed of the felt, the radius of the curved surface and the wetness of the felt.

The radius ofcurved surface 17 must be comparatively small. It must be small enough that at the operating speed of the machinery with which the purging apparatus is used to cause the foreign substance, water and particles, to'be flung from the felt under the action of centrifugal force. When air is supplied under pressure to the undersurface of the felt so as to cause it to ride over an air cushion as it passes around the curved surface, the radius of said 1 surface may be made smaller without subjecting the felt to undue wear and strain than would otherwise be possible.

As is customary in travelling felt machines, ashower pipe 48 may be mounted onbeam 21 in a position to direct water on to the underside offelt 12 as it approaches thecurved surface 17 ofapparatus 15. Similarly, anothershower pipe 49 may be provided after the purging apparatus, with reference to the direction of movement of the felt, in order to direct afelt-conditioning shower thereon.

FIGURE 4 illustrates an alternative form of purging apparatus'SS. This includes atubular member 58 mounted on asuitable beam 59. A plurality of supportingmembers 64 and 65 are mounted on and radiate outwardly frommember 58. Supportingmembers 64 have small-radiusedcurved surfaces 68 and supportingmembers 65 have similarcurved surfaces 70 over which a felt 73 travels. The curved surfaces 68 and 70 combine to form a curved surface of comparatively short radius over which felt 73 travels. The supportingmembers 64 and 65 form channels orgrooves 74 therebetween which make available'or supply air to the undersurface offelt 73 as it travels over the small-radiusedsurfaces 68 and 70. It is preferable to providetubular member 58 with perforations or holes 76 which bring the interior of said member into communica units arranged in series,

tion with the channels orgrooves 74. Air is supplied under pressure to the interior ofmember 58 through one or more entrances 79.

The theory of operation of purgingapparatus 55 is the same as that described above. The contact of the undersurface offelt 73 with the curved surfaces of supportingmembers 64 and 65 is kept to a minimum, while a large percentage of said undersurface is exposed to th air inchannels 74. Air may be supplied at a pressure just sufficient to lift the felt otfcurved surfaces 68 and 70.

FIGURE 5 illustrates another alternative form of purgingapparatus 84. This apparatus includes a thin shell roll ormember 86 having perforations or holes 88 therein.Roll 86 is backed by a C-shapedbeam 89 which supplies air to the interior ofroll 86 throughperforations 88. The ends ofbeam 89 are closed and air pumped into this beam, in the manner described above in connection withtubular members 18 and 58.

FIGURE 6 illustrates purgingapparatus 94 which includes twoflinger members 96 and 97 in series and having small-radiusedcurved surfaces 98 and 99 over which a felt'100 travels. This felt travels aroundsurface 98, a relativelylarge turning roll 104 and then over small-radiusedsurface 99. As the felt travels oversurfaces 98 and 99, foreign substances, water and particles, are flung under the action of centrifugal force in the direction ofarrows 106 and 107 into aneffluent pan 108 which is shaped and positioned to catch the foreign substances from both small-radiused surfaces.Members 96 and 97 haveunperforated surfaces 98 and 99 so that no air is supplied to the undersurface of the felt. Appreciable results are attained with this apparatus if the felt travels at high speed, for example, something of the order of 3,000 f.p.m. This embodiment of the invention illustrates multiple purging and it will be understood thatsurfaces 98, 99 can be perforated and that air under pressure may or may not be supplied to the undersurface of the felt in these units. In other words, any of the illustrated purging units may be arranged in series as diagrammatically illustrated in FIGURE 6.

FIGURES 7 and 8 illustrate yet another alternative form of purgingapparatus 115. This apparatus includes a plurality of small-radiusedrolls 118 located in end-toend relationship and rotatably mounted on ashaft 119 which is carried bysuitable supports 121 extending outwardly from abeam 122. Each roll consists of a length ofmetal tubing 124 having ends 125 formed of suitable plastic or Micarta, and which are journalled onshaft 119. A felt 126 extends around the curved surfaces ofrolls 118 in the same manner as in the previously described forms of the invention.Beam 122 may be in the form of anair duct 127, in which case, a plurality ofholes 128 are formed in the beam so as to direct air against the undersurface offelt 126 as it approaches the curved surfaces ofrolls 118. Foreign substances are thrown under the action of centrifugal force outwardly and downwardly in the direction ofarrows 130.Rolls 118 in effect provide a rolling surface of small radius forfelt 126. It is preferable to supply air to the undersurface of this felt in order to prevent the formation of voids in the felts as the water and particles are flung therefrom.

What I claim as my invention is:

1. The method of removing foreign substance, such as water and particles, from dewatering and transporting felts used in paper making and other machines, which comprises moving the felt around a curved surface of sufficiently small radius at the operating speed of the machine to fling the foreign substance from the felt under the action of centrifugal force, and simultaneously supplying air to the underside of the felt toassist the flinging of the foreign substance by preventing the creation of a low pressure in the felt thereby reducing the suction action resulting from the removal of the foreign substance.

2 The method ofclaim 1 in which: said' pressure is kept below the point where it will cause the felt to swim on the surface.

3. Apparatus for removing foreign substance, such as water and particles, from dewatering and transporting felt used in paper making and other machines, comprising at least one member providing a curved surface of small radius, means for moving the felt angularly over at least a portion of said surface, the radius of the curved surface being sufiiciently small to cause at the operating speed of the machine the foreign substance to be flung under the action of centrifugal force from the felt during passage of the latter around the small-radiused curves, and means simultaneously making air available to the underside of the felt at said curved surface to replace the foreign substance flung therefrom.

4. Apparatus as claimed inclaim 3 in which the curved surface is stationary.

5. Apparatus as claimed inclaim 3 in which the curved surface is movable.

6. Apparatus as claimed inclaim 3 in which the curved surface is provided by a plurality of spaced members providing individually curved surfaces consecutively arranged in the path of movement of the felt.

7. Apparatus as claimed inclaim 6 including means for directing air into spaces between said individually curved surfaces.

8. Apparatus as claimed inclaim 3 in which said member is perforated, and the air is made available to the felt through the perforations of the surface thereof.

9. Apparatus as claimed inclaim 3 in which the curved surface is provided by a plurality of rolls mounted end to end on a supporting shaft.

10. Apparatus as claimed inclaim 3 in which said member is cylindrical and is provided with perforations in the portion of its surface over which the felt moves, said member having closed ends, and the means making the air available comprises at least one pipe extending a substantial distance into the cylindrical member through an end thereof.

References Cited UNITED STATES PATENTS 1,395,219 10/1921 Bennett 162-275 3,011,544 12/1961 Lippke 162-359 X 3,093,535 6/1963 Brauns 162-199 3,097,971 7/1963 Carlisle 34156 X 3,127,080 3/1964 Allander 34156 X S. LEON BASHORE, Acting Primary Examiner. HOWARD R. CAINE, Examiner.

Claims (2)

1. THE METHOD OF REMOVING FOREIGN SUBSTANCE, SUCH AS WATER AND PARTICLES, FROM DEWATERING AND TRANSPORTING FELTS USED IN PAPER MAKING AND OTHER MACHINES, WHICH COMPRISES MOVING THE FELT AROUND A CURVED SURFACE OF SUFFICIENTLY SMALL RADIUS AT THE OPERATING SPEED OF THE MACHINE TO FLING THE FOREIGN SUBSTANCE FROM THE FELT UNDER THE ACTION OF CENTRIFUGAL FORCE, AND SIMULTANEOUSLY SUPPLYING AIR TO THE UNDERSIDE OF THE FELT TO ASSIST THE FLINGING OF THE FOREIGN SUBSTANCE BY PREVENTING THE CREATION OF A LOW PRESSURE IN THE FELT THEREBY REDUCING THE SUCTION ACTION RESULTING FROM THE REMOVAL OF THE FOREIGN SUBSTANCE.

3. APPARATUS FOR REMOVING FOREIGN SUBSTANCES, SUCH AS WATER AND PARTICLES, FROM DEWATERING AND TRANSPORTING FELT USED IN PAPER MAKING AND OTHER MACHINES, COMPRISING AT LEAST ONE MEMBER PROVIDING A CURVED SURFACE OF SMALL RADIUS, MEANS FOR MOVING THE FELT ANGULARLY OVER AT LEAST A PORTION OF SAID SURFACE, THE RADIUS OF THE CURVED SUR-

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