US 3269537 A
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Description (OCR text may contain errors)
g- 1966 F. KAISER 3,259,537
RADIAL FLOW SOLIDS SEPARATOR WITH SEAL Filed July 9, 1962 PRIOR ART IN VEN T OR. FAITZ KAI-SE? AWKNEfS United States Patent C 3,269,537 RADHAL FLGW SOLHDE; SEPARATUR WETH EaEAlL Fritz Kaiser, Hammel, near Augsburg, Germany, assignor to Alpine Alrtiengesellschaft Masehinenfahrik und Eisengiesserei, a German company Filed .iuly 9, 1962, Ser. No. 2%,323 Claims priority, application Germany, July 12, 1961, A $7,358 l Claims. (Cl. 209-444) The invention is concerned with a flow separator for the separation of a mixture of particles into two parts according to size relative to a given datum and relates to separators of the type in which the division takes place in a rotating wheel through which the fine particles move in a radially inward direction.
The invention deals with an important individual construction part, namely the seal of a so-called movement clearance which exists between the rotating wheel and the housing of the separator. Briefly, the invention involves the provision of an additional separation chamber, with such additional separation chamber including as one part of its flow path for the fluid medium and the material being separated, the clearance between the rotor of the first separation chamber and its outlet pipe. The arrangement and dimensions of parts in the additional separation chamber is such that the fine particles separated out are of such small size as compared to those which constitute the fines of the main separation chamber that they readily pass through the aforesaid clearance which is included in the flow path of the additional separation chamber.
It is among the objects of the invention to provide a simple yet effective seal.
In the drawings the figures represent:
FIG. 1, a schematic illustration of a separator wheel according to prior art.
FIG. 2, a schematic longitudinal section through an embodiment of a separator having the seal for the clearance according to the invention.
FIG. 3, an elevation of the separator wheel alone substantially from the right according to FIG. 2.
Separators in which the separation takes place in a wheel through which the fine material passes radially inwardly as a result of the inward fiow of the flow medium, are known in many embodiments. FIGURE 1 of the accompanying drawings shows a system common to all embodiments. The rotating wheel or separator wheel it can have on its circumference a separating chamber 2, such chamber for example, being free of internal obstructions or, alternatively being provided with blades or louvre type members. The material flow 3 can be purely radial or it may have an axial component. Any type of apparatus 4 admits the feed material to the circumference of the rotating wheel, and the fine material or fines is drawn off through a central discharge pipe 5.
Since the passage of the flow medium through the rotating wheel against the centrifugal force causes a considerable loss of pressure, there is always the danger that a part of the material fed, while passing round the wheel, is sucked (arrow 6) round the front wall 7 of the separator outlet pipe through the necessary clearance between the rotating front wall of the separator 7 and the stationary discharge pipe 5, and thus pollute the fines.
In order to avoid this ditficulty, it is necessary to provide a seal between the circumference of the rotating Patented August 30, 1966 separator wheel and the stationary outlet for the fines. That is to say, a seal must be provided in the region of the movement clearance such as will preclude passage of material therethrough. Many constructions are known for this purpose:
It is not practical to utilize a stufiing box seal due to the high speed of operation and pollution by dust.
In order to overcome the problem, it. is not unusual to omit the front wall 7 of the wheel and to provide a stationary wall which extends between the feed organ 4 and the discharge pipe 5. Unfortunately, this alternative, while avoiding the problem of ingress of feed material detracts from the effectiveness of .separation since the boundary layer of the coarse flow material creeps or slides inwardly on this stationary wall. The knowledge of this embodiment is however, important to understand the invention.
It is also known to mount the rotating wheel very accurately and to make the movement clearance narrower than the finest particle the passage of which is to be prevented. The disadvantage in this expedient, especially with very fine separating-is that a very high degree of accuracy is required and furthermore there is a tendency towards blocking the clearance by slipping and sticking material; such blockage leads to danger of fire.
It is further known to have two clearances behind one another and to blow therebetween clean flow medium. The movement clearance is scavenged by clean flow medium. The high expense of two clearances and the arranging for the supply of clean flow medium and the production of pressure is disadvantageous.
It is also known to bring the flow medium, loaded with the fines, after it leaves the opening 5, to a pressure higher than that which exists at the circumference of the separator wheel, in an apparatus connected with the separator wheel and then to scavenge the movement clearance with flow medium loaded with fined material towards the feed apparatus. The production of pressure mentioned takes place either through the built-in fan for the whole flow medium or by return blades outside the front wall of the separator wheel for a partial flow. In this case, too, the blocking of the clearance by slipping or sticking material, and above all, the fact that to produce the requisite pressure ventilators of considerably larger diameter than the separator wheel are necessary which naturally cause constructional difficulties, are disadvantageous. In contrast to the teaching of the invention, the known principle is that the return blades or ventilator blow through from the inside to the outside of the main separation chamber through the clearance 12.
The invention, in contradistinction, lies: in the fact that (see FIG. 2), at the place wherein the last-named known embodiment the return blades provide for, from the inside to the outside, an additional separation chamber 111: provides for flow from the outside to the inside of the main separation chamber through the clearance 12.
The movement clearance 12. is so dimensioned that the flow medium flowing through it flows first through the separation chamber 11a defined in part by blades 11b affixed to the outer surface of rotor wall 21 and, in part, by the opposing stationary wall 14 of the housing 16. This additional separation chamber 11a which holds back all particles which are larger than the fines produced by the main Wheel, consequently, the principle is to interpose before the clearance 12 a special separation chamber so that only fines which are still finer than the fines of the main separation chamber can get into the clearance.
To achieve this, the amount of flow medium flowing through, and therefore the radial components in the additional separation chamber 11a, are held so small by corresponding selection of clearance 12 that in spite of coarse separation even in a primitive additional separation chamber lla no over-size particles pass through. The required measurement of clearance 12 can be easily and empirically ascertained; it will always work out right if the Width of the additional separation chamber 11a is more than ten times the clearance width 12. By width is meant the maximum amount by which any one of the blades 11b extends parallel to the rotational axis and outwardly from the outer surface of rotor wall 21.
In order to prevent too coarse particles sliding inwardly on the stationary wall 14 of the additional separation chamber 11a, one or more ledges 15 can be formed in this wall along whose outerside all material slipping past is forced outwardly by centrifugal force. Thus, only the finer particles can traverse the defined path and enter into the discharge stream via the movement clearance 12.
The additional separation chamber 11a can be built onto separator wheels of any known type.
A shape that has proved to be especially suitable is one in which the separation chamber 11a is fitted with spiral, backwardly slanted blades 1112 which, as shown in FIG- URE 3, may be mounted upon the outward surface 21 of the main separation rotor. The inclination of the spiral is so chosen that no material remains lying thereon (about 60 to the circumference).
The seal according to the invention can be employed in both dry and wet separation.
In FIG. 2, the numeral 16 indicates the housing of a wind separator in which the separator wheel or rotor 13 is journalled in a conventional manner.
Any desired type of blade, in this case unimportant, is built into separating chamber 17 (symbolised by the diagonal cross).
The profile of the separator wheel can also be of any desired form. Stationary members 18 are mounted in housing 16 adjacent the circumference of the separator wheel to feed the flow medium and the material to be separated and also to exhaust the coarse material. The actual type of members 18 symbolised here by a diagonal cross are again of no great importance.
The flow medium passes through the separator wheel 13 in the direction of arrow 19 from the outside to the inside and takes the fine material with it. A partial flow 20 of the flow medium encircling the separator wheel 13 flows through the movement clearance 12 and mixes with the flow medium 19 carrying the fined material so that no feed material is drawn inwards from the periphery 18 of separating chamber 11.
An additional separation chamber 11a is provided outside the main separator wheel 13. This separation chamber 11a is bounded on one side by the outer surface of rotor wall 21 and on the other side by the stationary inner wall 14 of the housing 16 and includes blades 11b which may be formed on or affixed to the outer surface of rotor wall 21.
In order that no coarse particles can slide into the boundary layer from this wall 14, the said wall is provided with two ledges 15. Coarse particles which arrive therein are taken by centrifugal force from the outer side of these ledges 15 outwardly into the area of the blades 11 and passed outwardly.
The radial component of the side flow 21 is so small due ot the choking by the narrow clearance 12 that the margin of division in the separation chamber 11a is so low that, in spite of coarse separation, no particles move inwardly which are so large that they would affect the main separation of separator 17.
As sharp separation by the separation chamber 11a is not required the shape of blades 11b is not of importance and those whose configuration is as shown in FIG. 3 have proved satisfactory.
What is claimed is:
1. In a separator for finely-divided solid materials, a first fluid flow separation chamber comprising a separation rotor rotating within .a stationary housing, inlet means for admitting the material to be separated and the fluid medium to the periphery of said separation rotor, a stationary outlet pipe communicating with said separation chamber substantially at the axis of said rotor and defining a predetermined circumferential clearance therebetween, and an additional separation chamber including a second rotor and defined at least in part by said separa tion rotor and said stationary housing, said additional chamber communicating substantially at the periphery of said rotor with said inlet means and communicating with said outlet pipe substantially only through said clearance between said outlet pipe and the first-mentioned rotor to thereby define a flow path for said fluid medium from said inlet means through said additional separation chamber and said clearance into said outlet pipe, said second rotor including blades which are so disposed on said rotor relative to its direction of rotation to permit only particles of said materials which are finer than a predetermined size to travel along said fiow path with said fluid medium, said additional separation chamber including means for so restricting the flow of said fluid medium therethrough that those particles traveling under the influence of said fluid medium to the center of said second rotor and through said clearance into said outlet pipe are smaller than the particles which pass into said outlet pipe from said first separation chamber.
2. The separator as defined in claim 1 wherein said first separation chamber includes a disc-like rotating end wall forming a part of said rotor in said first separation chamber and said additional separation chamber is defined at least in part by said end Wall and also by an inner wall of said stationary housing, said second rotor comprising spiral blades on said end wall.
3. The separator as defined in claim 1 wherein said first separation chamber includes a disc-like rotating end wall forming a part of said rotor in said first separation chamber and said additional separation chamber is defined at least in part by said end wall and also by an inner wall of said stationary housing, said inner wall of said stationary housing defining a plurality of ledge-shaped portions each being substantially parallel to the axis of rotation of said rotor and with the remaining inner surface of said stationary housing which in part defines said second separation chamber being inclined inwardly toward the plane of rotation of said second rotor with increasing radial distance from the axis of said second rotor.
4. Apparatus for use with a fluid flow separator for finely-divided solid materials of the type having in combination, a first rotor revolving in a stationary housing and including a means for admitting both the material to be defined and the fluid medium into said housing adjacent the periphery of said first rotor and also an outlet pipe which communicates with the axis of said first rotor but with a predetermined clearance between said pipe and said first rotor, said predetermined clearance being selected to be sufliciently small so that the fines separated out in said first rotor cannot pass therethrough and instead substantially all enter said outlet pipe, the improvement which comprises a sealing means to prevent said material from being drawn through said clearance from outside said housing and thereby clogging said clearance, said sealing means including in combination a second separation chamber defined in part by said housing and in part by rotor means, said second separation chamber communicating substantially at the periphery of said second rotor with said inlet means, said second separation chamber communicating with said outlet pipe through said clearance to thereby define a flow path for said fluid medium from said inlet means through said additional separation chamber and said clearance into said outlet pipe, said rotor means including blades which are so disposed relative to the direction of rotation of said rotor means to permit only particles which are smaller than a predetermined size to travel along said flow path with said fluid medium, and means for restricting the flow of fluid mediumth'rough said second separation chamber, said last-named means in combina- 10 tion with said second rotor being jointly operable to separate out particles in said second separation chamber which are smaller than those separated out in said first separation chamber, whereby said smaller particles readily pass through said clearance and into said outlet pipe.
References Cited by the Examiner UNITED STATES PATENTS 2,207,317 9/1940 Gear 103115 2,361,758 10/1944 De Fligue 209144 3,089,595 5/1963 Kaiser 209-144 FRANK W. LUTTER, Primary Examiner.