US3268078A - Push-type centrifuge - Google Patents

Description

Aug. 23, 1966 G. MUGGLl PUSH-TYPE CENTRIFUGE 2 Sheets-Sheet 1 Filed Oct. 28. 1963 INVENTOR GUNTHER Mueau ATTORNEYS Aug. 23, 1966 G. MUGGLI 3, 7

PUSH-TYPE CENTR IFUGE Filed Oct. 28, 1963 2 Sheets-Sheet 2 INVENTOR GUNTHER Muqqu ATTORNE Y5 United States Patent 3,268,078 PUSH-TYPE CENTRIFUGE Giinther Muggli, Zurich, Switzerland, assignor to Escher Wyss Airtiengesellschaft, Zurich, Switzerland, a corporation of Switzerland Filed Oct. 28, 1963, Ser. No. 319,136 Claims priority, application Switzerland, Nov. 14, 1962, 13,307/ 62 1 Claim. (Cl. 210-149) This invention relates to a push-type centrifuge for the separation of liquid from a liquid-solid mixture, having a centrifuging chamber in which a revolving centrifugal drum, a collecting chamber for the centrifuged solid matter and a collecting chamber for the separated liquid are provided.

For push-type centrifuges, it has already been proposed to heat the drum with the layer of centrifuged material lying on it by supplying heat from the inside of the drum, for example by supplying hot air steam. Since, however, in addition to the heat supply, the ordinary ventilation gas, generally air, flows through the drum and through the material lying on it, the temperature of the centrifuged material in the known process fluctuates over such a wide range that heat-sensitive substances can no longer be centrifuged by this process. In addition, a large part of the heat expended escapes with the exhaust air of the centrifuge.

It is the aim of this invention to avoid these disadvantages. In a push-type centrifuge of the hereinbefore described kind, for this purpose according to the invention, the centrifuging chamber is separated approximately gas-tight from the surroundings, and a passage is provided for returning to the interior of the centrifugal drum the ventilation gas issuing into the collecting chamber for the liquid, and finally, the ventilation gas is maintained at least approximately at a predetermined temperature.

The invention is based on the knowledge that the temperature of the centrifuged material inside a push-type centrifuge is determined primarily by the ventilation gas, that is to say, by the gas current set up by rotation of the centrifugal drum and feed hopper, and passing round and through the centrifuged material, while the other factors, such as for example thermal radiation from or to the housing walls, or the thermal conduction of the centrifuging drum are no longer of importance once the equilibrium condition has been reached. It is thus possible, by the simple steps according to the invention, to keep the temperature of the centrifuged material on its entire path through the ush-type centrifuge at a constant predetermined temperature, more particularly at the same temperature as that of the material fed to the centrifuge.

In this way, the push-type centrifuge can also be used for the separation of heat-sensitive materials. More particularly, however, it is now possible to centrifuge in a push-type centrifuge substances, in which the constituents to be separated have different states of aggregation only within a very narrow temperature range (for example, as is the case in the separation of ice crystals from concentrated fruit juice).

A constructional example of the subject of the invention is shown in the drawing in simplified manner.

FIGURE 1 shows a view of a centrifuge equipped according to the invention, viewed in the axial direction, and

FIGURE 2 shows a view in the direction of the arrow Z in FIGURE 1, the centrifuge itself being shown in section.

The housing of the push-type centrifuge 1 shown encloses a centrifuging chamber 2, in which are arranged a revolving foraminons centrifugal drum 3, a collecting chamber 4 for the centrifuged solid matter and a collecting chamber 5 for the separated liquid. The material to be centrifuged, i.e. the liquid-solid mixture, is fed to the centrifuge through a feed pipe 6, and led to the supply end of the revolving centrifugal drum 3. The material is then pushed in the axial direction toward the discharge end of the drum 3. whereby liquid is separated from the mixture by centrifugal action. The liquid collecting chamber 5 encircles the drum 3 and the solid matter collecting chamber 4 adjoins the discharge end of the drum 3. The separated liquid leaves the centrifuge through a discharge pipe 7, while the centrifuged solid matter is discharged through a discharge pipe 8.

The centrifuging hamber 2 is separated approximately gas-tight from the surroundings. Gas exchange between the interior of the centrifuge housing and the surroundings is prevented by means of sluices 9 and 10 incorporated respectively in the feed pipe 6 and discharge pipe 8. Furthermore the discharge pipe 7 dips below the level of the liquid in a vessel 11, and the shaft 12 of the centrifugal drum 3 is provided with a stuffing box 13. A duct 14 serves for the return of the ventilation gas, in particular air, issuing into the collecting chamber 5 for the liquid, to the interior of the centrifugal drum 3. The circulated ventilation air is kept at a predetermined temperature.

For this purpose, a heat exchanger 15 is incorporated in the duct 14. A temperature sensitive element, namely a pick-up 16, measuring the temperature of the ventilation air issuing from the centrifugal drum 3, controls a regulating device 17 which, when the temperature of the ventilation air differs from the predetermined value, alters the supply of heat to the ventilation air in heat exchanger 15 by adjusting the opening of a valve 18 in such a manner that the predetermined temperature is reached again. If the temperature of the ventilation air falls below a predetermined value, the valve 18 is opened to a greater extent and the supply of heat is increased, if on the other hand the temperature of the ventilation air surpasses a predetermined value, the valve 18 is closed to a greater extent and the supply of heat to the ventilation air in heat exchanger 15 is thus reduced.

Incorporated in the duct 14 is a fan 19, by means whereof the rate of circulation of the ventilation air can be increased. A liquid separator 20 with a discharge 21 and a washing liquid feed 22 are likewise incorporated in the duct 14.

In the case where there is a considerable temperature difference between the ventilation air and the surroundings, the walls of the duct 14 are advantageously provided with an insulation. The walls of the centrifuging chamber 2 may also be provided with an insulation.

If the centrifuged material has to be kept at a tempera ture below the temperature of the surroundings, a coolant is supplied to the heat exchanger 15 and heat is extracted from the ventilation air.

As a pick-up for the temperature regulating device 17, it is also possible to use a device which measures the temperature of the separated liquid.

Motors 23, 24 rotate the sluices 9 and 10, respectively, a motor 25 drives the fan 19. Deflecting plates 26 prevent separated liquid from entering the duct 14.

In the constructional example shown, the duct 14 extends immediately up to the outlet end of the centrifugal drum 3. It may, however, merely connect together the parts of the centrifuging chamber which receive the liquid and solid matter.

What is claimed is:

A push type centrifuge for the separation of liquid from a liquid-solid mixture comprising a housing; a foraminous centrifuge drum mounted for rotation in said housing; said drum having a supply end for the liquidsolid mixture and a discharge end for the solid mixture, said housing defining a collecting chamber for the separated liquid which encircles said drum and a collecting chamber for the solid mixture adjoining the discharge end of said drum; duct means extending between said liquidcollecting chamber and the interior of the drum; a blower in said duct serving .to withdraw ventilation gas from the liquid-collecting chamber and deliver it to said interior of the drum; a heat exchanger in said duct means in heatexchanging relation with said ventilating gas; sealing means for preventing gas exchange between the interior of the housing and its surroundings; control means regulating said heat exchanger to maintain said ventilation gas at least approximately at a predetermined temperature and a liquid separator in said duct means between said blower and said liquid-collecting chamber.

References Cited by the Examiner UNITED STATES PATENTS' 12/1915 Boland 210-178 9/1943 Barnebl et a1 210-68 X 7/1945 Schutte 210-68 X 12/1958 Dickens et al. 210-149 X 10/1959 Newsorn 210-178 X 6/1963 Irving 210-376 FOREIGN PATENTS 8/1956 Germany.

REUBEN FRIEDMAN, Primary Examiner.

J DECESARE, Assistant Examiner.

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