Centrifugal separator having ring with outlet flow restrictions

Patent metadata

Field	Value
Publication number	US-12528091-B2
Application number	US-202017641524-A
Country	US
Kind code	B2
Filing date	Sep 10, 2020
Priority date	Sep 25, 2019
Publication date	Jan 20, 2026
Grant date	Jan 20, 2026

Abstract

A centrifugal separator for clarification of a liquid mixture into a heavy phase and a light phase, having a centrifugal separator bowl rotatable around an axis and encasing a separation space, and a sludge space radially outward of said separation space. The centrifugal separator bowl includes a hermetic inlet for feeding a liquid mixture to said separation space; a first hermetic outlet for a separated clarified light phase; and a second hermetic outlet for a separated heavy phase; a plurality of outlet conduits extending from an outer position in said sludge space to said second hermetic outlet. Each of the outlet conduits has a flow restriction in the form of a nozzle or vortex diode. A method to control such a centrifugal separator, in order to provide a stable flow through said outlet conduits, is also disclosed.

First claim

The invention claimed is:

1 . A centrifugal separator for clarification of a liquid mixture into a heavy phase and a light phase, comprising:
a centrifugal separator bowl rotatable around an axis and encasing a separation space, and a sludge space radially outward of said separation space; a hermetic inlet for feeding a liquid mixture to said separation space; a first hermetic outlet for a separated clarified light phase; a second hermetic outlet for a separated heavy phase; a plurality of outlet conduits extending from an outer position in said sludge space to said second hermetic outlet; and a ring having a bottom surface contacting a top surface of the centrifugal separator bowl and forming a plurality of flow restrictions extending from the bottom surface of the ring to a top surface of the ring, the plurality of flow restrictions communicating with the plurality of outlet conduits, wherein a diameter of the plurality of flow restrictions varies between the bottom surface of the ring and the top surface of the ring.

2 . The centrifugal separator according to claim 1 , wherein the plurality of outlet conduits are at least partly shaped as pipes.

3 . The centrifugal separator according to claim 2 , wherein a cross-section of the plurality of outlet conduits is circular.

4 . The centrifugal separator according to claim 2 , wherein the plurality of flow restrictions are in the form of exchangeable pieces.

5 . The centrifugal separator according to claim 2 , wherein the second hermetic outlet for heavy phase has a mechanical seal of larger diameter than a mechanical seal on the first hermetic outlet for light phase.

6 . The centrifugal separator according to claim 1 , wherein a cross-section of the plurality of outlet conduits is circular.

7 . The centrifugal separator according to claim 1 , wherein the plurality of flow restrictions are in the form of exchangeable pieces.

8 . The centrifugal separator to claim 1 , wherein the second hermetic outlet for heavy phase has a mechanical seal of larger diameter than a mechanical seal on the first hermetic outlet for light phase.

9 . The centrifugal separator according to claim 8 , wherein a ratio between a radius of the mechanical seal of the second hermetic outlet for heavy phase and an outer radius of a disc stack is larger than 20%.

10 . The centrifugal separator according to claim 1 , wherein the centrifugal separator bowl has a third outlet for intermittent discharge at a periphery of the centrifugal separator bowl thereof.

11 . The centrifugal separator according to claim 1 , wherein a control valve is arranged in the second hermetic outlet.

12 . The centrifugal separator according to claim 11 , wherein a control valve is arranged in the first hermetic outlet.

13 . The centrifugal separator according to claim 11 , wherein at least one measuring device is arranged in the second hermetic outlet measuring density and flow rate, the at least one measuring device being connected to a programmable logic controller (PLC) and being adapted to send data representing density and flow rate respectively, the programmable logic controller (PLC) being adapted to process the data to determine if the combination of values of flow rate and density lies within a predetermined scope of values corresponding to a stable flow through the plurality of outlet conduits or not, and wherein an actuator is adapted to manipulate one or both of said control valves in the first and second hermetic outlets in response to a correction signal sent by said programmable logic controller (PLC), if said combination of values of flow rate and density does not lie within said predetermined scope.

14 . A method to control the centrifugal separator according to claim 1 , in order to provide a stable flow through the plurality of outlet conduits, combinations of values of flow rate and density of the heavy phase is established where a stable flow through the plurality of outlet conduits are maintained, the flow rate and density of the heavy phase in said second hermetic outlet are measured continuously or intermittently and compared to said combinations of values by a programmable logic controller (PLC), the flow rate in said second hermetic outlet and/or said first hermetic outlet is regulated so a stable flow is maintained.

15 . The method according to claim 14 , wherein the programmable logic controller (PLC) is set to follow a curve corresponding to combinations of flow rate and density in said second hermetic outlet, with a margin to a stability limit curve, under which stability limit curve the plurality of conduits may clog.

16 . The centrifugal separator according to claim 1 , wherein the ring fits within a recess in the top surface of the centrifugal separator bowl.

17 . The centrifugal separator according to claim 1 , wherein the outlet conduits extend to the top surface of the centrifugal separator bowl, and
wherein the plurality of flow restrictions align with the plurality of outlet conduits.

18 . A centrifugal separator for clarification of a liquid mixture into a heavy phase and a light phase, having a centrifugal separator bowl rotatable around an axis and encasing a separation space, and a sludge space radially outward of said separation space, comprising:
a hermetic inlet for feeding a liquid mixture to said separation space; a first hermetic outlet for a separated clarified light phase; a second hermetic outlet for a separated heavy phase; a plurality of outlet conduits extending from an outer position in said sludge space to said second hermetic outlet; and a ring forming a plurality of flow restrictions, the plurality of flow restrictions communicating with the plurality of outlet conduits, wherein the ring is formed by a ring piece having a plurality of inlets and an exchangeable ring having a plurality of outlets.

19 . The centrifugal separator according to claim 18 , wherein a plurality of vortex chambers are formed in the ring piece.

20 . The centrifugal separator according to claim 19 , wherein diameters of the plurality of outlets are less than diameters of the plurality of vortex chambers.

Assignees

• Alfa Laval Corp Ab

Inventors

• Borgström Leonard
• Törnblom Olle

Classifications

• B04B2005/0464

  with hollow or massive core in centrifuge bowl · CPC title

• B04B13/00

  Control arrangements specially designed for centrifuges; Program control of centrifuges (control arrangements for feed, charge or discharge B04B11/00) · CPC title

• B04B11/02 Primary

  Continuous feeding or discharging; Control arrangements therefor · CPC title

• B04B1/08

  of conical shape · CPC title

• B04B5/0442 Primary

  with means for adding or withdrawing liquid substances during the centrifugation, e.g. continuous centrifugation · CPC title