GB1164464A - Centrifugal Separators - Google Patents

Abstract

1,164,464. Centrifugal separators. WESTFALIA SEPARATOR A.G. 9 Sept., 1966 [17 Sept., 1965], No. 40423/66. Addition to 984738. Heading B2P. In a centrifugal separator for clarifying liquids automatic partial desludging through apertures in the wall of the separator drum is carried out by arranging a pressure-operated electric switch in a probe liquid line which leads into the drum so that, when the opening of this line into the drum is closed by centrifuged sludge or by a centrifuged liquid component heavier than the other constituents of the liquid being clarified, the switch is actuated to operate a valve in a line through which pressure fluid is directed to a member in the drum controlling the opening and closing of the sludge discharge apertures. The operation of the control member for the apertures may be dependent upon the increase or decrease of pressure in the pressure fluid line, i.e. upon the opening or closing of the valve. The control member may be in the form of a piston. As shown, liquid to be clarified is fed to the drum of a centrifuge 1 through a line 2, and the clarified liquid is continuously discharged through a line 3. The sludge is discharged intermittently into an outlet 5 via apertures into the wall of the separator drum which are opened and closed by a sliding piston operated by pressure fluid supplied through a line 4 which incorporates a solenoid control valve 11. Probe liquid is fed via a line 6 which incorporates a float-operated switch 7-10 and which opens into the sludge chamber within the separator drum. During centrifugation, as soon as the opening of the line 6 within the sludge chamber is covered by accummulated sludge, the probe liquid level in the float chamber 7 of the switch rises until the float 8 makes electrical contact with pins 9, 10. This completes an electric circuit whereby the normally closed valve 11 opens and admits pressure fluid through the line 4 to the piston causing it to open the sludge discharge apertures until the receding ring of sludge uncovers the opening of the probe liquid line. The liquid level in the float chamber 7 then drops causing the float 8 to break contact with the pins 9, 10 to interrupt current to the valve 11 which is thereby closed so that the piston closes the sludge apertures. To control the time during which the sludge discharge apertures remain open the pins 9, 10 may be in the form of resiliently biased pins so that the amount of time the pins are in contact with the float 8 may be varied. An adjustable delay element 12 may also be included in the circuit which, on closure of contacts 9, 10, activates a switch 13 bridging the contacts 9, 10, and thus keeps the valve 11 open for a set time after the float 8 has broken contact with the pins 9, 10.