Patent GB-1114096-A (GB)
Title: Centrifuge
Inventor: DAHLBERG BENGT INGMAR
IPC: B04B1/08
Filed: 1966-09-13
Abstract: 1,114,096. Centrifugal separators. ALFALAVAL AKTIEBOLAG. 13 Sept., 1966, No. 40797/66. Heading B2P. In a centrifuge for separating two liquids from each other and comprising a liquid inlet 4 and two liquid outlets 8, 20, Fig. 1. in order to maintain the interface 18 between the liquids in the separating chamber 17 within a limited zone despite variations in the specific gravity of one of the liquids, the liquid outlet 20 is controlled by a movable throttling member, e.g. a piston 21, one side of which is exposed to the pressure, generated by centrifugal force, of a head of said one liquid, and the other side to the pressure of a different head of the same liquid or ot a mixture in which the said one liquid predominates, the arrangement being such that movement of the throttling member due to changes in the specific gravity of the said one liquid varies the throttling of the outlet 20 in such a manner as to maintain the interface 18 within the required limited zone. When treating a mixture of oil and water the water is discharged via the overflow outlet 8 while the oil flows inwardly of separating discs 7 and discharges via the outlet 20 and a channel 19 into a chamber 10 from which it is removed by means of a stationary paring member 13. The throttling piston 21 is acted on its upper side by oil which enters a chamber 11 via a pipe 15 which branches off from the channel 14 of the paring member 13. The oil accumulates to a level 22 in the chamber 11 and fills up a pipe 16 which opens into the separating chamber 17 beyond the interface 18, the oil flowing out into the chamber 17 travelling inwards towards the discs 7. The underside of the piston 21 is acted upon by oil which accumulates to a level 23 and by a compression spring 24. Alternatively, a tension spring may be provided above the piston. In operation, the head of oil, measured radially of the centrifuge between the level 22 and the outer end of the pipe 16, balances the constant head of water between the outlet 8 and the outer end of the pipe 16. The pressure of the head of oil acts downwardly on the piston 21 and is opposed by the action of spring 24 together with the pressure of the head of oil between the levels 18 and 23 which latter head of oil balances the head of water between the level 18 and outlet 8. If the specific gravity of the oil in the mixture fed to the centrifuge increases, the oil level 22 moves radially outwards as a smaller head is required to balance the head of water. The pressure on top of the piston 21 is reduced and the spring 24 and the oil pressure moves the piston upwards increasing the area of the orifice 20 and the oil level 23 travels outwardly so that the head of oil between levels 18 and 23 becomes shorter. This results in a displacement of the level 18 which is small compared to that encountered in conventional centrifuges. In a modification, a mixture containing a small proportion of the heavier liquid is supplied through the space 11 and the pipe 16 to the chamber 17 so that the upper side of the piston is subjected to a mixture in which the lighter liquid predominates and on its underside to the lighter liquid. In a further modification, Fig. 2, the spring 24 is omitted and the opposite sides 21b, 21c of the piston 21a are of different effective area.