US3508704A - Centrifugal separator control - Google Patents

Description

A ril 28, 1970 H. HEMFORT 3,508,704

CENTRIFUGAL SEPARATOR CONTROL Filed Feb. 6, 1968 INVENTOR HEINRICH HEMFORT United States Patent 3,508,704 CENTRIFUGAL SEPARATOR CONTROL Heinrich Hemfort, Oelde, Westphalia, Germany, assignor to Westfalia Separator A.G., Oelde, Westphalia, Germany, a corporation of Germany Filed Feb. 6, 1968, Ser. No. 703,364 Claims priority, application Germany, Feb. 8, 1967, W 43,319 Int. Cl. B04b 11/04 U.S. Cl. 233-20 7 Claims ABSTRACT OF THE DISCLOSURE In controlling the desludging cycle of a centrifugal bowl of the self-opening type by sensing the level of liquid flowing through a holdup chamber which rotates with the bowl and is in communication with the sludge chamber of the bowl, false signals caused by foam are avoided by dividing the chamber into two compartments by a radially extending partition. The liquid is introduced into the first compartment and passes from the bottom the first compartment to the second compartment. The height of the first compartment is less than the height of the second compartment and accordingly foam overflows from the first compartment and does not get into the second compartment.

US. Patent 3,301,476 relates to an apparatus for emitting a signal or a controlling pulse when a specifically heavier component gathering in the sludge chamber at the periphery of the separating chamber of a centrifugal bowl, reaches a predetermined level. The instant invention is an improvement on the apparatus of said patent.

This prior-art apparatus is characterized by an element which is disposed in a central chamber located intermediate the separating chamber and the skimming chamber, and emits a signal Whenever the element comes in contact with the free level of the sensing liquid fed to the sludge chamber from the central chamber. This occurs when the sludge separated from the liquid being processed has reached a previously determined amount, thereby changing the pressure and fiow conditions in the passages for the feed of the sensing liquid.

It has now developed that, in the centrifugal treatment of foam-forming liquids, a sensitive transducer will respond as soon as it comes in contact with the foam floating on the liquid. The desludging operation is then started before the specifically heavier component of the material being processed reaches the openings of the passages conducting the sensing liquid into the sludge chamber. In the case of particularly heavily foaming liquids, the emission of an impulse may even take place before any appreciable quantity of a specifically heavier component has collected in the sludge chamber. Under certain circumstances this considerably shortens the spinning periods between desludging cycles and increases the losses of the liquid being centrifuged, because a large amount of liquid is always ejected with the solids through the openings in the drum mantle.

One element that causes such misfunctioning on account of its sensitivity is, for example, an electrical sensing means which is set at a higher electrical potential than the mass of the drum and starts the desludging cycle when a conductive connection is produced between the sensing means and the mass of the drum. Foam or splashing liquid may cause such an element to respond faultily.

The invention is aimed at eliminating these disadvantages and designing the apparatus for the emission of the controlling impulse in such a manner that premature operation by foam or by splashing is prevented.

The invention is characterized by the combination of the following features:

3,508,704 Patented Apr. 28, 1970 (l) The central chamber is divided into two chambers by a partition provided with holes in the outer part.

(2) The sensing liquid feed passageway empties into the upper chamber.

(3) The lower chamber communicates with the sludge chamber through passages.

(4) The upper chamber is separated from the chamber for collecting the purified liquid by a battle Whose distance from the axis of rotation is greater than that of the partition between the two portions of the central chamber.

The foam collecting on the liquid in the upper chamber then passes over the battle located at the greater distance from the axis of rotation, into the chamber for collecting the purified liquid, and is thereby kept away from the lower chamber in which the sensing means is disposed.

In the case of particularly heavily foaming liquids it is desirable to place the overflow of the collecting chamber for purified liquid at a still greater distance from the axis of rotation so that the foam can be discharged into a catcher surrounding the drum before it reaches the inner margin of the partition between the two portions of the central chamber.

Another feature of the invention thus consists in the fact that the overflow of the collecting chamber for the purified liquid is located farther from the axis of rotation than the bafile separating this gathering chamber from the chamber for the sensing liquid.

Thus the invention is directed to an improvement in centrifugal separators of the self-opening type having a drum with a sludge collection chamber at the periphery of the separating chamber for receiving specifically heavier material centrifuged out of the liquid. The drum is mounted for rotation about an axis and includes a holdup chamber for holdup of a sensing liquid. The holdup chamber is disposed adjacent the axis for rotation, and has an inlet and an outlet, the latter being communicated with the sludge collection chamber for transfer of sensing liquid from the holdup chamber to the sludge collection chamber. A transducer is disposed in the holdup chamber for actuation by the sensing liquid when this liquid reaches a preselected level. The level of the sensing liquid is shifted inward, when the discharge openings are clogged by specifically heavier material collecting in the sludge chamber of the drum. Actuation of the transducer causes control means to operate for control of the centrifuging. According to the invention, a radially extending partition is disposed in the holdup chamber, dividing that chamber into a first compartment which includes the inlet of the holdup chamber, and a second compartment which includes the outlet of the holdup chamber. The partition has an opening disposed outwardly of the inner end thereof and communicating the two compartments. The transducer is disposed in the second compartment, and the height of the first compartment is less than the height of the second compartment. By reason of this construction, foam will overflow from the first compartment and will not get into the second compartment.

An example of the embodiment of the invention is represented in the drawing, in which:

FIG. 1 shows the upper portion of a self-cleaning clarifying centrifuge with the apparatus according to the invention and a skimming disc as the clarified liquid removing means; and

FIG. 2 shows the central portion on a larger scale.

The liquid containing solids is fed continually to the drum through conduit 1 and infeed tube 2. The specifically heavier contaminants separated from the liquid, collect in the sludge chamber 3. The clarified liquid passes from the central portion of the separating chamber through passages 4 in to the skimming chamber 5 and is pumped out under pressure by skimming disc 6 through conduit 7.

A small portion of the clarified liquid is carried back into sludge chamber 3 through passages 8 and 8a in order to serve as the sensing liquid. Passages 8 emerge from a central chamber or holdup chamber which, according to the invention is bipartite. The upper compartment 9 receives the sensing liquid brought in through passage 10. It communicates with the lower compartment 12 through outer holes 11, and with the skimming chamber through the annular gap 13. The electrical sensing means 14, which is surrounded by insulating material 15, extends into chamber 12, and is disposed outwardly of the inner end of partition 19.

During the centrifuging, the same liquid level establishes itself in compartments 9 and 12 on account of the communicating connection between them, as indicated by the dash-dotted line 16. The foam floating on the liquid in compartment 9 cannot pass through holes 11 into compartment 12. Due to the fact that the baffle 18 is farther away from the axis of rotation than wall 19 separating compartments 9 and 12 from one another, the height of compartment 9 is less than the height of compartment 12, and therefore the foam passes out of compartment 9 over bafile 18 into the skimming chamber -5. In the case of especially high-foaming liquids, it is desirable to construct the cover 17 of the collecting chamber 5 in such a manner that the overflow of this chamber will be at a greater distance from the axis of rotation than bafiie 18, i.e., so that the height of chamber 5 is less than the height of compartment 9.

When the solids deposited in sludge chamber 3 prevent the emergence of the sensing liquid from passage 8a, then the free liquid level in the intercommunicating chambers 9 and 12 shifts. As soon as the liquid contacts the sensing means 14, a circuit is closed. The electric current that is thus made to flow can, for example, cause a relay in a switch box 20 (FIG. 1) to respond, which imparts the pulse to controller 21 to start the desludging cycle, e.g., to lower the gate 22 to permit flow through the discharge openings 23.

While the invention has been described with respect to particular embodiments thereof, these embodiments are merely representative and do not serve to set forth the limits of the invention.

What is claimed is:

1. In a centrifugal separator comprising:

(a) a drum with a sludge collection chamber at its periphery for receiving specifically heavier material centrifuged out of a liquid, the drum being mounted for rotation about an axis for the centrifuging;

(b) a holdup chamber for holdup of a sensing liquid, the holdup chamber being disposed adjacent said axis for rotation with the drum;

(c) said holdup chamber having an inlet and an outlet, the latter being communicated with the sludge collection chamber for transfer of a sensing liquid from the holdup chamber to the sludge collection chamber, whereby the liquid level in the holdup chamber is shifted inward, when the discharge openings are clogged by specifically heavier material collecting in the sludge chamber;

(d) a transducer disposed in the holdup chamber for actuation by the liquid when the liquid reaches a preselected level;

(e) control means for response to actuation of the transducer and control of operation of the centrifuge;

the improvement which comprises:

(f) a radially extending partition in the holdup chamber dividing the holdup chamber into a first compartment including said inlet and a second compartment including said outlet, said partition having an opening disposed outwardly of the inner end of the partition, communicating the two compartments, the transducer benig disposed in said second compartment, the height of the first compartment being less than the height of the second compartment.

2. Centrifuge according to claim 1, wherein the transducer is disposed outwardly of the inner end of the partition.

3. Centrifuge according to claim 2, wherein said outlet of the holdup chamber is disposed adjacent the outer end of the chamber in the second compartment and communicates with the sludge collection chamber.

4. Centrifuge according to claim 3, the compartment in which the transducer is located being disposed beneath the other compartment.

5. Centrifuge according to claim 2, and a skimming chamber communicating with the first compartment so that overflow from the first compartment, enters into the skimming chamber, the height of the skimming chamber being less than the height of said first compartment.

6. Centrifuge according to claim 3, and a skimming chamber communicating with the first compartment so that overflow from the first compartment, enters into the skimming chamber, the height of the skimming chamber being less than the height of said first compartment.

7. Centrifuge according to claim 4, and a skimming chamber communicating with the first compartment so that overflow from the first compartment, enters into the skimming chamber, the height of the skimming chamber being less than the height of said first compartment.

References Cited UNITED STATES PATENTS 3,135,691 6/1964 Hemfort 233-19 3,167,509 1/1965 Steinackcr 233-20 3,301,476 1/ 1967 Hernfort 233-20 3,396,910 8/1968 Steinacker 233-20 WILLIAM I. PRICE, Primary Examiner

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