GB1221630A - Improvements in or relating to sludge centrifuges - Google Patents

Abstract

1,221,630. Centrifugal separators. ALFALAVAL A.B. 20 Jan., 1970 [22 Jan., 1969], No. 2717/70. Heading B2P. In a sludge centrifuge, the level of sludge 10 in the sludge space of the rotor 1 is indicated by means of an indicating channel 19 which extends inwardly from the sludge space towards the centre of the rotor and is connected to means for sensing clogging of the outer end of the channel by sludge, the channel wall having an opening 24 (or 25, 25a or 32) into the separating space 8 of the rotor which opening is closer to the axis of rotation than the outer end of the channel. In Fig. 1 separated liquid flows from the inner edge of a disc set 9 into a paring chamber 16 and out through an outlet 18 via a stationary paring disc 17. The channel 19, which may consist of one or more pipes or of a disc interspace divided by radially extending ribs, opens into a paring chamber 20 in which is located a stationary paring disc 21 connected to a pipeline 22 fitted with a pressure gauge 23. In operation, liquid to be purified fills the space 8 and the channel 19. Since liquid flow is small in the part of the channel situated radially outside the opening 24 and is nil in the part situated radially inside, the sludge in the indicating liquid is rapidly separated out and consequently the indicating liquid is lighter than the liquid in the space 8. Owing to this the level 27 of the indicating liquid in chamber 20 will be closer to the axis of rotation than the level 26 of the separated liquid in the chamber 16. The indicating liquid has the same pressure as the separation liquid at the mouth of the channel 19 but a higher pressure at the level of opening 24, so that indicating liquid flows out through the opening 24, into the space 8 and a corresponding amount of separation liquid flows into the channel through its mouth. When sludge has accumulated at the mouth, liquid flow in channel 19 is interrupted. The indicating liquid pressure and the separation liquid pressure will therefore be the same on both sides of the opening 24. Thus indicating liquid will flow through the radially inner part of channel 19 out into the space 8 through the opening 24 so that level 27 will be displaced and this displacement is indicated by the gauge 23. In Fig. 2 the pipeline 18 is hermetically connected to the rotor through a seal 29. The inner channel end has the form of a central space 30 into which the pipeline 22, fitted with a venting hole 31 and a pressure gauge 23, opens through a seal 29. A reduction of pressure in the space 30 is caused where sludge accumlates at the outer end of the channel 19.