GB2031750A

GB2031750A - Liquid/liquid contactors

Info

Publication number: GB2031750A
Application number: GB7841219A
Authority: GB
Original assignee: RTL Contactor Holding SA
Current assignee: RTL Contactor Holding SA
Priority date: 1978-10-19
Filing date: 1978-10-19
Publication date: 1980-04-30
Also published as: GB2031750B

Abstract

A contactor for effecting continuous contacting of two liquid streams, which may contain solids, comprises a drum within which rotates a rotor, discs rotating with the rotor and separating the drum into compartments, buckets in at least some of the compartments to create phase intermingling and at least one port intermediate the ends of the drum for introduction or withdrawal of material to or from the contactor. At least the cylindrical portion of the drum can be adjusted to bring at least one port into register with the phase interface.

Description

SPECIFICATION Contactors This invention relates to contactors of the type described in U.S. Patent No. 3,649,209 and U.K Patent Application No. 23633/78 for effecting continuous contacting of a first liquid stream with a second liquid stream; either or both of the streams may carry solids. Such a contactor has a rotor which is mounted within a stationary drum and which includes a series of axially apaced discs separating the drum into a series of compartments and buckets in at least some of the compartments to create intermingling of the phases in those compartments.

In such a contactor, the two liquids are immiscible and form separate phases with a stable interface which is caused to pass approximately through the drum axis by control of the rates of flow. The interface is not horizontal; the pressure drop from end to end of the contactor results in the interface being inclined to the horizontal in the axial direction, the contactor axis being usually so tilted that the interface passes through the axis. In addition, the rotation of the rotor within the drum causes the interface to be tilted from the horizontal radially of the rotor i.e. at each point along the rotor axis the interface lies approximately on a diameter which is inclined to the horizontal by an angle dependent on the speed of the rotor.

Usually the tilting of the interface in the radial plane is of little significance since the phases are customarily entered into and discharged from the contactor through the drum ends. In some applications however it is necessary or desirable to extract a constituent from the contactor at or adjacent the interface or similarly to enter a side stream into the contactor. An example of such an application is described in U.K. Patent Specification No.

33125/78 where an interfacial layer is formed and is desirably removed through ports in the drum at intervals along the axis and where a reagent is to be introduced adjacent the interface; U.K. Specification No.

35906/78 describes a further example. More generally, where the process carried out in the contactor gives rise to the formation of crud or scum at the interface, it is desirable to remove it intermediate the contactor ends.

Because the location of the interface between the phases relative to the drum periphery is dependent on a number of factors of which the speed of rotation is the most significent, it is difficult to remove an interfacial layer through a port at a given peripheral position in the drum wall; unless the port is located close to the interface, quantities of one or other of the liquid phases will be extracted with the interfacial layer.

In the present invention, at least the cylindrical shell of the drum is adjustable about its axis so that a port in the shell can be brought exactly to the interface between the phases.

Thus the entire drum may be mounted so that it can be turned through a requisite angle or the shell may be carried in fixed drum ends by rotary seals enabling the shell to be angularly adjusted relative to the drum ends.

Preferably, at each axial position at which material is to be removed at the interface, the drum shell has a number of ports spaced about the drum periphery. It is then necessary to adjust the shell through at most half the spacing of the ports. When one of the ports has been thus brought to the interface that port is connected to discharge piping, the other ports remaining closed off. For example, the shell may have twelve ports at each compartment at which discharge is to take place, e.g. at every third or fourth compartment along the contactor; the maximum angle through which the shell is to be adjusted is then 15 .

Where a reagent is to be entered intermediate the drum ends as in U.K. Specification No. 33125/78, it may be injected through another of the ports and preferably at the port next after the selected discharge port in the direction of rotation of the rotor.

In order to enable the discharge port to be located exactly at the interface, there is preferably provided a detector for indicating the level of the interface relative to the drum shell. That detector may respond to the change in electrical conductivity of the liquids at the interface or may use gamma-ray screening.

1. A contactor for effecting continuous contacting of a first liquid phase with a second liquid phase, one or both of said streams optionally containing solids, comprising a rotor mounted for rotation in a drum, a plurality of axially spaced discs rotatable with the rotor and separating the drum into a plurality of interconnected compartments, the discs carrying buckets in at least some of the compartments to create intermingling of the phases and at least one port in the cylindrical portion of the drum intermediate its ends for introducing or discharging material into or from one or more compartments of the contactor, at least the cylindrical portion of the drum being adjustable about its axis so that at least one port can be brought in register with the interface between the phases in the contactor.

2. A contactor according to claim 1, wherein the drum has a plurality of ports in its cylindrical portion for the or each compartments into which or from which material is introduced or withdrawn, the ports being spaced around the drum periphery.

3. A contactor according to claim 2, wherein twelve peripherally spaced ports are

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION Contactors This invention relates to contactors of the type described in U.S. Patent No. 3,649,209 and U.K Patent Application No. 23633/78 for effecting continuous contacting of a first liquid stream with a second liquid stream; either or both of the streams may carry solids. Such a contactor has a rotor which is mounted within a stationary drum and which includes a series of axially apaced discs separating the drum into a series of compartments and buckets in at least some of the compartments to create intermingling of the phases in those compartments. In such a contactor, the two liquids are immiscible and form separate phases with a stable interface which is caused to pass approximately through the drum axis by control of the rates of flow. The interface is not horizontal; the pressure drop from end to end of the contactor results in the interface being inclined to the horizontal in the axial direction, the contactor axis being usually so tilted that the interface passes through the axis. In addition, the rotation of the rotor within the drum causes the interface to be tilted from the horizontal radially of the rotor i.e. at each point along the rotor axis the interface lies approximately on a diameter which is inclined to the horizontal by an angle dependent on the speed of the rotor. Usually the tilting of the interface in the radial plane is of little significance since the phases are customarily entered into and discharged from the contactor through the drum ends. In some applications however it is necessary or desirable to extract a constituent from the contactor at or adjacent the interface or similarly to enter a side stream into the contactor. An example of such an application is described in U.K. Patent Specification No. 33125/78 where an interfacial layer is formed and is desirably removed through ports in the drum at intervals along the axis and where a reagent is to be introduced adjacent the interface; U.K. Specification No. 35906/78 describes a further example. More generally, where the process carried out in the contactor gives rise to the formation of crud or scum at the interface, it is desirable to remove it intermediate the contactor ends. Because the location of the interface between the phases relative to the drum periphery is dependent on a number of factors of which the speed of rotation is the most significent, it is difficult to remove an interfacial layer through a port at a given peripheral position in the drum wall; unless the port is located close to the interface, quantities of one or other of the liquid phases will be extracted with the interfacial layer. In the present invention, at least the cylindrical shell of the drum is adjustable about its axis so that a port in the shell can be brought exactly to the interface between the phases. Thus the entire drum may be mounted so that it can be turned through a requisite angle or the shell may be carried in fixed drum ends by rotary seals enabling the shell to be angularly adjusted relative to the drum ends. Preferably, at each axial position at which material is to be removed at the interface, the drum shell has a number of ports spaced about the drum periphery. It is then necessary to adjust the shell through at most half the spacing of the ports. When one of the ports has been thus brought to the interface that port is connected to discharge piping, the other ports remaining closed off. For example, the shell may have twelve ports at each compartment at which discharge is to take place, e.g. at every third or fourth compartment along the contactor; the maximum angle through which the shell is to be adjusted is then 15 . Where a reagent is to be entered intermediate the drum ends as in U.K. Specification No. 33125/78, it may be injected through another of the ports and preferably at the port next after the selected discharge port in the direction of rotation of the rotor. In order to enable the discharge port to be located exactly at the interface, there is preferably provided a detector for indicating the level of the interface relative to the drum shell. That detector may respond to the change in electrical conductivity of the liquids at the interface or may use gamma-ray screening. CLAIMS

3. A contactor according to claim 2, wherein twelve peripherally spaced ports are provided and at least the cylindrical portion of the drum is rotatable through an angle of 1 5,.

4. A contactor according to any one of claims 1 to 3, wherein the entire drum is rotatable about its axis by an angle sufficiently large to permit at least one port to be brought into register with the interface between the phases in the contactor.

5. A contactor according to any one of claims 1 to 3, wherein the cylindrical portion of the drum is rotatable about its axis by an angle sufficiently large to permit at least one port to be brought into register with the interface between the phases in the contactor, the cylindrical portion being carried in fixed drum ends by rotary seals.

6. A contactor according to any one of the preceding claims comprising a detector for indicating the level of the interface relative to the cylindrical portion of the drum in the compartment or compartments where material is to be introduced or withdrawn from the contactor.

7. A contactor according to claim 1, substantially as described herein.