US1935117A - Centrifugal separating bowl - Google Patents

Description

Nov. 14, 1933. o. E. FRODING CENTRIFUGAL SEPARATING BOWL Filed Aug. 8, 1930 Wmvnss:

W/fZZZi/d Patented Nov. 14, 1933 "UNITED sTATEs 1,935,117. I v CENTRIFUGAL SEPARATING BOWL Olof Einar Friiding, Stockholm, Sweden, assignor to The De Laval Separator Company, New; York, N. IL, a corporation of New Jersey Application August 8, 1930, Serial No. 473,867,

and in Sweden August 29, 1929 3 Claims. (01. 233-46) When separating, by means of continuously operating centrifuges, liquids which are more or less intimately mixed and which contain solid matters in suspension, a greater'or smaller part 5 of. the solid matters is deposited in the centrifugalbowl, and when the -deposition. has grown to acertain pointthemachine can no longer operate in the way intended, but must be stopped 10 for cleaning. To avoid this objectiona number been tried. a V

In one common type of centrifugal bowl, which is rotated by means of e a vertical spindle, the peripheral wall is concentric with the axis and the mixture is fed through a central tube and thence outward to the lower peripheral part of the bowl. The bowl is usually equipped with a superposed pile of spaced-apart conical sheet iron discs, spaced from the bowl wall, to facilitate the separation of the mixed liquids. If, for example, this mixture is an oilcontaminated with water and solids, a greater or smaller portion of the impurities are separated. The separated water collects between the bowl wall and the outer edges of the discs until so much has accumulated that it begins to outflow continuously through channels between the top disc and the bowl top. With correct adjustment of the central distance of the outlets for'water and oil respectively, static equilibrium'is reached so that the pressure of the, water is equal to the,

pressure of the oil, analogous to what takes place between two columns of liquid exposed to the influence of the force of gravity in communijcating vessels. This principle was known and applied in the earliest constructions of milk separators. Y

Part of the solid impurities, especially those which have about the same specific gravity as the water, flow out together with the water through said channels and are thus removed continuously. Some of the impurities have, however, a higher specific gravity than the water and these are separated out and deposited on 4 the bowl wall. The result W111 then finally be that the annular chamber between the pile of discs and the wall of the bowl entirely fills with solid matters so that the bowl can no longer operate.

051 In bowls of this construction or similar constructions it has been attempted to counteract said deposition of solids by providing for astrong fiow of the heavier separated liquid or other heavy liquid continuously or intermittently through the bowl and especially through its of different constructions and methods haveperipheral portion. In this way a certain quan tity of the solid matters can be flushed out through the outflow channels, but experiencehas shown that the method isnot effective in most cases because, in spite of the strong flow of liquid upwardly along the wall of the bowl, the heaviest matters cannot be moved upward owing to the centrifugal force; but stickto the bowl. wall. The method is also undependable in'that' the large quantity of fiushingfliqu'id'. easily may cause an emulsion withthe lighter liquid, the result of which is an incomplete separation. Moreover, a separation of solid matters occurs in the outflow channels, which, in constructions of this type, are approximately. parallel with the generating lines of the conical discs, so that said channels become clogged.

The problem or continuously removing the separated solids has also been attempted to be solved by providing another type of centrifugal bowl, which differs from the'bowl first described in that the bowl wall extends at an angle to the, axis, of rotation with openings or nozzles arranged around the periphery along a line most distantfromthe axis. .The, separation of the liquids and the discharge of the lighter liquid take place as inthe bowl first described, b'utthe separated heavier liquid, together with the solid matters, travels outward toward said peripheral openings, the dimensions of whichare such that, with the pressure of liquid prevailing at them; the quantity of heavier liquid separated per time unit is discharged through them. The separated solid matters slide along the bowl wall to said openings, where they are flushed out with the heavier liquid. In continuous separation aperipheral part of the bowl is thus filled with heavier liquid, whereas the central part is filled with lighter liquid, as is also the case with the construction first described.

The difierence in the way the bowls operate is, however, that in the second described construction the equilibrium between said layers of liquid is not static but dynamic. If, for instancathe content of heavier liquid in the mixture of liquids sinks to nil during the separating process, the quantity. of heavier liquid contained in the bowl will at first go out through the peripheral openings and then the lighter liquid will discharge the same way. Even before the content of heavier liquid has dropped to this point, there is risk that the same thing will happen, and such a construction of the bowl is thus in many cases not suitable and has not been universally employed.

The present invention comprises a centrifugal bowl of such construction that the separated solid matters are continuously removed by the separated heavier liquid, static equilibrium also prevailing between the separated liquids contained in the bowl.

The drawing is a vertical sectional-view of such a centrifugal bowl. The body or hood a is held on the bottom 13 by the lock ring c. The central feed tube carries the mixture to be separated into the bottom channel or channels 01 whence the mixture flows into the bowl, is distributed through the discs e, and is separated as in the bowls hereinbefore described, the lighter liquid discharging through the openings f.- The heavier liquid is carried into the peripheral part of the bowl and discharges continuously through the channels h arranged in the bottom b.

Such shape has been given to the body a that the solid impurities, which are separated from the lighterv liquid and move out towards it under the influence of the centrifugal force, slide down to the openings g of the channels h. These channels,'which are used as outlets for the heavier liquid, extend approximately in radial direction from the centre line of the bowl as well as approximately horizontally, i. e;, in nearly the direction of the centrifugal force, so that no separation of solid matters on the walls of the chair- .nels takes place owing to the centrifugal force.

By locating'the openings 1 i at proper rela tive distances from the axis of rotation, static equilibrium between the two bulks of separated liquids is secured, and if, therefore, for instance,

the content of heavier liquid in the mixture of liquids sinks to nil, the'static equilibrium between the two bulks of liquids will be maintained.

The invention is susceptible of embodiment in a greater number of different forms. It is, for

instance, possible to mount the bowl in such manner on the spindle that the top of its cone-shaped hood is turned downwards, it is also possible to arrange the bowl for rotation around a horizontal axis. h

It is also possible to supply the mixture of liquids to the bowl in such manner that the distribution of the liquid in the pile of discs takes place from that side of the pile of discs which touches the conical hood.

The .discharge of the separated liquids from the bowl can also be varied in known ways. In a bowl rotating on a vertical axis, for instance,

both outlets can be placed on the upper side of the bowl, or both on the lower side, or they may be arranged on opposite sides.

When treating certain liquids which can be comparatively easily separated it is not necessary to use a pile of discs, the invention being capable of embodiment in the so-called open bowl.

The invention does not exclude the use, in cases where it is found advantageous, of a strong flow of the heavier separated liquid, or other heavy liquid, for better flushing of the bowl, as hereinbefore described. When used, it is most suitable to introduce the extra flow of liquid through a separate system of channels provided in the bowl in such manner that such flow does not reduce the eiiiciency of the bowl, as, for example, is disclosed in the British Patent No. 10,314, of 1908.

Having now fully described my invention, what I claim and desire to protect'by Letters Patent is:

l. A centrifugal bowl provided with a straight discharge passage extending from the peripheral part of the bowl approximately radially inward toward and at substantial right angles to the bowls axis of rotation and integral with the bowl so as to have no movement of'rotation independently thereof, said pass-age :having free, continuous communication with the interior of the bowl. i r a L. A centrifugal bowl provided with a straight discharge passage extending-from the peripheral part of the bowl toward its axis of rotation in a direction substantially parallel to the lines of centrifugal force and integralw-ith the bowl so cross-section, each- 0f the channels extending in- 1 wardly from said pocket towards and at substantially a'right angle'to theaxis ofrotation of the bowland opening at both ends at'a right angle to said axis of rotation, said c'hannels'having free, continuous communication with'the pocket.

OLOF EINAR FRODING.

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