US2002954A - Centrifugal separator - Google Patents

Description

or discharge pipes or collecting chambers.

. such centrifuges the bowl is often provided with Patented May 28, 1935 UNITED STATES PATENT OFFICE signor, by mesne assignments, to The DeLaval Separator Company, New York, N. Y., a corporation of New Jersey Application September 18, 1931, Serial No. 563,540 In Sweden December 15, 1930 1 Claim.

Some types of centrifuges are arranged in such a way that liquid can be conveyed into or from the interior of the centrifugal bowl through channels which are tightly connected to fixed supply In two concentrically arranged systems of channels, both of which may be intended for discharge of liquid, or one of them may be intended for supply of liquid. Between the systems of channels are tightening devices, for instance packing boxes, having for their purpose to prevent liquid from leaking from one system of channels to the other, which may take place owing to the fact that the difference of pressure between the liquids in the two systems may be rather great. As tightening devices of the usual type cannot, however, wholly prevent leakage by overflow, they have been provided with collecting chambers intended to catch the liquid that may leak over. It is known, also, to connect the collecting chamber with the outer atmosphere by means of a cock.

The present invention is based on the experience that tightening devices in the form of collar packings, such as disclosed in my application Serial No. 563,539, filed September 18, 1931, are very-suitable in closed centrifuges. Such packings, however, make a tight joint only in one direction of the shaft, whereas pressure from a liquid in the opposite direction tends-to open the collar. If an effective tight joint against pressure in both directions is required, two collars mounted in opposite directions must be used.

The present invention relates to an improvement on the tightening devices set forth in my said patent application, when such tightening devices are arranged in a centrifuge with systems of channels for liquids, extending one outside the other and usually concentrically. The systems of channels are tightly connected to fixed chambers or pipes at the tightening devices, and the invention is characterized by the fact that each of the tightening devices separates two systems of channels for different liquids and comprises a collecting chamber, separated from the systems of channels by collar packings, which are preferably of the type stated in said patent application; the pressure in the collecting chamber during work being maintained lower than in those portions of the channel systems which are adjacent to the tightening device.

The figureflof the attached drawing is a sectional elevation of. a centrifuge to which is applied one preferred embodiment of the invention. In this embodiment the spindle I, which carries the centrifugal bowl 2, is provided with a longitudinal boring through which liquid to be separated is fed into the bowl. The bowl is provided with a central channel 3 for the discharge of the lighter of the liquid components (in this instance two) which are separated in the bowl.

For the discharge of the heavier separated com-' Collar packings are provided between the tube 1, which'rotates with the bowl and embraces the channel 3, and another tube 8 embracing the tube 1 and being rigidly connected with, for instance, the frame 20 surrounding the bowl. An upper collar 9 is squeezed fast between the upper side of an inwardly projecting flange ID on the inner side of the tube 8 anda sleeve nut II threaded into the tube 8. This sleeve nut may be a portion of the discharge pipe for the lighter separated liquid. The free end of the collar 9, which is in contact with the tube 1, extends upwards. Liquid contained in the chamber 5 under pressure therefore presses the collar against the tube 1, which rotates during the work. One end of a collar I2 is also squeezed fast against the lower side of the flange ID by a sleeve nut l3. The

free end of the collar I2 is in contact with the tube 1 and extends downwards. The chamber 6 makes a tight joint downwards in some suitable manner, for instance by means of a collar l4. Liquid under pressure contained in the chamber 6 presses the collar against the tube 1.

The flange l0 does not extend inward so .far that it comes into contact with the outer wall of the tube 1, but enclosed by the flange II], the collars 9 and I2 and the tube 1, is a ring-shaped chamber l5. If, owing to'pressure in either of the chambers 5 or 6, liquid should leak past the tightening surfaces of the collars 9 and I2, notwithstanding the good tighteningeifect of the collar packings, it would stream past the next tightening surface and penetrate into and become mixed with another separated liquid, if special steps were not taken. This would occur by reason of the fact that the collar does not make a tight joint against pressure having the same direction as direction of extension of the free.

presses the free ends of the collars against'the tube I soon disappears unless means were provided to preserve such difference in pressure, and the tightening effect'would thus also --disappear. In connection with collar packings, the collecting chamber I5 is therefore arranged in such manner, according to, the present invention, that the pressure in it during work is constantly kept lower than in those portions of the channel systems which are adjacent to the tightening device, e. g., lower than in either of the chambers 5 and 6. 'The simplest .way to bring about this is to put the chamber I5 into connection with the atmosphere, for instance, by means of a hole IS in the flange ID, a discharge pipe I! suitably being connected to the said hole "5. By the above named arrangement there is obtained the double advantage that the collar ismaintained more tightly pressed on the tightening surface and that the liquid which may nevertheless leak past is removed and cannot increase the pressure in the collecting chamber.

If it be found suitable to put the collecting chamber l5 under a pressure between the atmospheric pressure and the pressure in one of the chambers 5 or 6, a regulating valve may be arranged in the outlet [6 which owns outwards only when a certain fixed pressure is reached in the chamber l5. Y

It will be understood that the scope of the invention is'not limited to the embodiment thereof hereinbefore described. It is-possible to arrange tightening devices according to the invention' between several-mainly concentrically situated systems of liquid channels. The systems of channels, consisting of supply or discharge channels, or both, may be arranged at another place in the centrifuge than at the top of the bowl, for instance at its lower part, or at the lower end of the bowl spindle. When using the tigh ening devices, which press rather strongly against the revolving part, not only the said tightening devices, but also the revolving part, become Worn. In order to prevent or minimize such wear, all or a part of the tightening surfaces on the revolving parts which are embraced by packings may be treated so that they become hard and thus resistive to wean. They may be secured by chromium plating.

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

In a centrifugal machine, a rotatable tubular element through which a fluid is adapted to flow,

two non-rotatable tubular elements surrounding the rotatable tubular element, one of which forms-a channel through which another fluid is adapted to flow and the other of which forms a channel communicating with said rotatable tubular element, elastic collars each comprising a free tubular end surrounding the rotatable tubular element and an outwardly projecting end, a-

flange projecting inwardly from one of said nonrotatable tubular elements, an internal ,sleeve adjustable lengthwise of the last named nonrotatable tubular element, the other of said nonrotatable tubular elements extending within and adjustable lengthwise of the internally flanged tubular element, the adjustable non-rotatable tubular element and said adjustable sleeve confining betweenthem and said flange, on opposite sides of the flange, the outwardly projecting ends of the respective elastic collars, thereby forming a collecting chamber enclosed by the rotatable tubular element, said flange and the elastic collars, said collecting chamber having an opening adapted to be connected with a source of absolute pressure belowv the pressures in the respective channels.

HANS OLOF LINDGREN.

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