US2828021A

US2828021A - Push-type centrifuge

Info

Publication number: US2828021A
Application number: US661857A
Authority: US
Inventors: Ruegg Ernst
Original assignee: Escher Wyss AG
Current assignee: Sulzer Escher Wyss AG
Priority date: 1956-06-07
Filing date: 1957-05-27
Publication date: 1958-03-25
Anticipated expiration: 1975-03-25
Also published as: GB800319A; BE557785A; DE1087978B; CH340770A; FR1176436A

Description

PUSH-'rinus CENIRIFUGE Ernst Ruegg, Kusnacht, Switzerland, ass'ignor to'Escher Wyss Aktiengesellschaft, Zurich, Switzerland, acorporation of' Switzerland Application May 27, 1957, Serial No. 661,857

Claims priority, application Switzerland June 7,11956 3 Claims.- (Cl.210-`37,6)

This invention relates to a =push-type centrifuge in which a sieve drum and a diverging feed drum .built therein and rotating therewith for feedingmaterial with which it is charged to the sieve drum, are `axiallynnovable relatively` to one another.

In hitherto known ,constructions of such lpush-type centrifuges, the funnel-shaped vfeed drumis usually connected to a push-button bymeans of stays, which bottom serves to convey the charge withinthe sieve drum which, together with this bottom, bounds an entrance chamberfor the material to be centrifuged. Charging of the material into the feed funnel usually takes place from the delivery side of the centrifuge .and ,the feed funnel diverges away lfrom the `delivery side of the centrifuge. The outer `end of the feed funnel or a hring mounted on the outer side ofthe feed funnel limits vthe thickness of the layer of material disposed-in 4the sieve drum.

Constructions are `also known in `which chargingof the material to `be centrifuged takes place ,from `the side `opposite to the delivery end of the centrifuge. -In this case the feed `funnel diverges in ithefdelivery direction and is provided with a sieve cover which permits `predehydration of the charge.

then in the form of a `ring ywhich is fastened directly `to the outer end of the feed funnel Aand is connected `to a boss by means of stays, the boss carrying the pusher ring and the feed `funnel .l and being laxially displaceable relative to the sieve ydrum. The feed funnel ,and the `boss together define a chamber which 4is vopen toward the sieve drum and here again a ring `mounted :on the boss serves as a layer limitinggrnembcr ,for :thevmaterial which is moving alongfthesieve drum.

In both constructions ,acceleration ,of `.the charge 'mae `terial to the peripheral :speed of the sieve 'drum takes place at least partly in the :chamber "formed by the feed `drum and the push bottom `or :the feed :drum andthe boss carrying the pusher member. Thesextwo .parts are `necessarily vjoined to one .another by ribs .which cross the path of the charge material in Y,this chamber. .Even if one ensures that these ribs are :arranged fas Jnear to the rotational axis as possible 1in order to lkeep their peripheral velocity to a minimum, damage ofthe solid material by virtue of impacts on the material can `not be entirely avoided. In this connectionitis to "be remembered that, for example, at a speed of 1200 revolutions per minute of the ,centrifugalirunnen four fastening ribs effect as many as 80 strokes through the material per second.

lt is true that the layer limiting members which have hitherto always been used maintain an even thickness of layer on the sieve drum. ever that these layer limiting members also cause destruction of the solid particles of the material by scraping the material at the delivery points from within the feed drum onto the sieve drum. Since, in View of the high centrifugal force in the sieve drum, the charge ma- The ipusher member is nited States Patent O It has been found how- Y a bearing `for this shaft.

lCe

terial is considerably compressed in the sieve drum, scraping requires a substantial expenditure of `energy and, apart from the fact that this has a destructive effecton the solid particles of the material, this expendi ture of energy also necessitates a higher power input to 'the centrifuge.

'When thepropertiesof the producttovbe centrifuged are variable a layer `limiting member could, in some cases, even be detrimental in so far that the perform- ,ance ofthe centrifugeislimited to a value which could easily have been exceeded for the particular product.

`Finally ,the known construction has the further disadvantage that the .arrangement of the washing pipes or sprinklers which are always provided for the charge material is difficult inthat these cannot be inserted in the centrifugal drum to the desired depth.

The invention `airns to overcome these disadvantages. In a push-type centrifuge in which a sieve drum and a feed drum, .diverging inthe delivery direction of the centrifuge, and being built into the sieve drum and rotating therewith for feeding material with which it is charged to the sieve drum, are axially movable relatively to -oneanother and ,in which a pusher ring for conveying the charge material within the sieve drum axially thereof, is connected directly to the outer end of the `feed `drum and sieve drum. Further, no solid confining walls areprovided which are formed by ribs, blades vor the like transversely of the charge material. The ,entrant charge material ows along the surface of the feed drum and is accelerated only by friction at the in- .ner face of the drum. Thus, all impacts on the charge are avoided. On the inside the charge material moving over the feed drum and the sieve drum has a free surface and thus any rubbing of a fixed part on the charge material pressed within the sieve drum is avoided.

An example of the invention is illustrated in simplified form in the drawing in which:

Figure l is an axial section of the centrifuge and Figure 2 is a section along the line II--II in Figure 1. -In fa housing 1, a sieve drum 2 is connected with one end `to the4 outer circumference of a boss 3 which is mounted to overhang on a hollow shaft 4. 5 indicates A conical disc 8 is mounted `on the freerprojecting end of a central shaft 6 arranged within the hollow shaft i coaxially therewith, the shaft A 6 being forced to rotate together with the shaft 4 by meansof a key 7 but vbeing displaceable axially thereof.

The conical Vdisc is disposed within the sieve drum 2. At its outer marginal portion there `is detachably connected a feed drum 9 which diverges in the delivery direction-of the centrifuge, i. e. toward the free open end .of the sievedrum 2, which is remotefrom the shaft. The

`feed'drum has a frusto-.conical shape. `A pusher ring lll), having its outer circumference in close proximity tothe `inner surface :of the sieve drum, is connected directly to ,theouter endof thefeed .drum 9, the, pusher ring serving Y open end thereof. Its discharge opening is directed toward the inner surface of the feed drum 9; It lies near 3 the inner end thereof and is arranged approximately tangentially of the drum 9 as shown in Figure 2. By virtue of the friction between the charge material and the feed drum 9, the material which leaves the conduit 11 is carried along by the rotating feed drum. The material rapidly moves outwards along the inner face of the feed drum which diverges toward the sieve drum and then reaches the inner face of the sieve drum to form a layer l2 (Figure l) on the sieve cover thereof. For the sake of illustrating the pusher ring liti clearly, the layer of material is not shown in Figure 2.

Upon axial reciprocatory movement of the central shaft 6 and the feed drum 9 and the pusher ring 10 in relation to the sieve drum 2 the layer of material deposited o-n the latter is gradually moved toward the delivery side and is finally delivered to a collecting chamber i3 of the housing. A delivery pipe 14 is provided to supply washing liquor into the sieve drum 2.

No solid walls are provided inside of the feed drum 9 andthe sieve drum 2 with which the layer of material moving within these drums could come into contact. A free space of suflicient width is left adjacent the inner surfaces of the feed drum 9 and the sieve drum 2 so as to allow the material to move within said drums while having a free surface toward the inside. The disc boss S which supports and drives the rotary feed device comprising feed drum 9 and pusher ring it) is connected with said feed device in a region outside the surface of the feed drum and pusher ring over which the material to be centrifuged travels,.so'that no stays or blades cross the layer of material which could'have an impact eifect on the material which is accelerated during rotation of the feed drum. The solid particles are therefore considerably protected during treatment in this centrifuge.

Assuming that the pusher ring and feed drum are moved to and fro relative to the sieve drum by a distance a, that is to say from a position as illustrated to one indicated by the chain -dotted lines, in the centrifuge as described above an even layer of Ymaterial is no longer formed even if the material enters continuously. Instead, the inner upper face of the layer in the sieve drum will have a wave shape with a wave length a because during each forward movement of the pusher ring the material is heaped up. During the return movement of the pusher ring the crest and trough of the wave is somewhat balanced by virtue of the centrifugal force. Experience has shown that despite ythe omission of a layer limiting member the differences in the thickness of the layer remain within relatively small limits so that this causes no disadvantages. On the other hand the heaping up of the material in the inlet chamber is no longer limited as in the case of hitherto known constructions s'o that the centrifuge can always be charged with an amount Y determined by the efticient centrifuging of the solid particles. The constructionaccording to the invention has the further advantage that liquid extracted duringrentry does not reach material'which is already located on the sieve face of the sieve drum as could be the case in known constructions where the liquid always separates on the delivery sided bounding surfaces of the feed chamber.

Instead of a frusto-.conical feed drum 9 as illustrated it can have the shape of a hollow body of revolution with an inner face having anarched meridian curve, either the concave Vor convex side of the meridian curve facing the axis of rotation.

In order also to protect the material as much as preferably has a smooth inner face.

What is claimed is: l. A push-type centrifuge comprising a sieve drum having an open end and being mounted with its opposite Yend to rotate about an axis, in which sieve drum material'is centrifuged while beingconveyed in the axial direction toward said open end; a rotary feed device arranged within saidsieve drum coaxially therewith; said rotary feed device comprising a feed drum of generally frusto-conical shape diverging in the direction toward the open end of said sieve drum and a pusher ring rigidly connected to the peripheral end of said feed drum and having its outer circumference in close proximity to the inner surface of said sieve drum; a stationary feed device for leading material to be centrifuged into said feed drum, the material thereby being caused to rotate and to travel along the inner surface of the feed drum and the pusher ring toward the inner surface of the sieve drum; and supporting and driving means for said rotary feed device causing said rotary feed device to rotate with the sieve drum while allowing axial reciprocatory displacement in relation to kone another, said supporting and driving means being connected with said rotary feed device in a region outside the surface of the feed drum and pusher ring over which the material to be centrifuged travels; and inside of the feed drum and the sieve drum an adjacent free space of sufficient width being left, so as to allow the material to move therein while having a free surface toward the inside.

2. The push-type centrifuge defined in claim 1 in which the feed drum has a smooth inner surface in the region over which the material to be centrifuged travels. Y

3. A push-type centrifuge comprising a hollow rotary shaft, a boss mounted overhung on a free end of said hollowshaft; a sieve drum being connected with one end to the outer circumference of said boss and having an open free end remote from said shaft; a central shaft arranged within said hollow shaft coaxially therewith and having an end projeting from said free end of the hollow shaft; means drivingly interconnecting said hollow shaft and said central shaft while allowing axial reciprocatory movement in relation to one another; a

' disc boss mounted on the projecting end of said central shaft within said sieve drum; a feed drum of generally frusto-conical shape arranged coaxially with said central shaft and having its inner end fastened on the peripheral end of said disc boss and diverging toward the open end of the sieve drum; a pusher ring rigidly connected to the outer end of said feed drum and having its outer circumferencein' close proximity to the inner surface of the sieve drum, so that, with an axial reciprocating movement of the central shaft in relation to the hollow shaft, material to be centrifuged lying in said sieve drum is gradually pushed byV said pusher ring toward the open end of the sieve drum; and a stationary feed conduit leading into the interior of the sieve drum through the open end thereof and havinga discharge opening directed toward Vthepinner surface of said feed drum, so that material discharging from said feed conduit is caused to rotate with the feed drum and travels over the inner Vsurface thereof toward the sieve drum; and inside of the -to move therein while having a free surface `toward the inside. Y

No references cited.V