TITLE

"A FLOW THROTTLING APPARATUS"

FIELD OF THE INVENTION

The present invention relates to a flow throttling apparatus

BACKGROUND OF THE INVENTION

During the production of various chemicals, it is possible to react agents to produce separate immiscible liquid phases, in a single flow stream. In order to control the flow of the product flow stream, it may be necessary to throttle the flow stream. When using known methods to throttle the flow stream, the immiscible liquid phases may

combine to form an emulsion. The emulsion may be difficult or impossible to separate thus reducing the recovery of the separate phases.

The present invention attempts to provide an apparatus for throttling flow which is particularly intended to promote stratification and reduce the degree of emulsification of the liquid phases, and thus improve the recoverability of the separate phases. The flow

throttling apparatus of the present invention is of general applicability and can be used in other applications.

SUMMARY OF THE PRESENT INVENTION

In accordance with one aspect of the present invention there is provided a flow throttling

apparatus characterized in that it comprises a first member having a bore therein, and a

second member which is located at least partially within the bore, at least one of the bore

and the second member having a substantially helical groove, such that the first and

second members define a substantially helical flow path, the substantially helical flow

path having a first end and a second end, wherein the first end of the flow path is arranged to receive a liquid at relatively high pressure and the second end of the flow path is arranged to discharge liquid at relatively low pressure, such that a liquid containing at

least two phases flowing along the substantially helical flow path has a reduced tendency to emulsify.

BRIEF DESCRIPTION OF THE DRAWING The present invention will now be described, by way of example, with reference to the accompanying drawing, which is a cross sectional view through a flow throttling

apparatus in accordance with the present invention.

DESCRIPTION OF PREFERRED EMBODIMENT(S) Referring to the drawing, there is shown a flow throttling apparatus 10. The apparatus 10

includes a substantially cylindrical first member 12 having a longitudinal axis 14, and a

bore 16 extending within the first member 12 along the longitudinal axis 14. The first

member 12 has a first axial end 18 and a second axial end 19.

Further, the bore 16 comprises a substantially cylindrical first portion 24 extending in an axial direction from the axial end 18; a substantially cylindrical second portion 26

extending in an axial direction from the first portion 24 and a seal 28 axially adjacent the second portion 26 at the second axial end 19.

Each of the first portion 24 and the second portion 26 extend along a portion of the total

length of the first member 12. The first portion 24 is larger in diameter than the second

portion 26.

The seal 28 comprises a packing 34 arranged to support a shaft 42 of smaller diameter

than the second portion 26 which forms part of a second member 40 to be described.

The flow throttling apparatus 10 further comprises a second member 40, comprising the

shaft 42. The shaft 42 is nominally of the same diameter as the packing 34.

The shaft 42 comprises a first portion 46 and a second portion 48 adjacent the first portion 46.

The first portion 46 is surrounded by a substantially helical groove 47. The first portion

46 is of the same diameter as the second portion 26 of the bore 16, so as to be engaged within the second portion 26 of the bore in a sliding fit.

The engagement of the first portion 46 of the second member 40 in the second portion 26 of the bore 16 thus causes the helical groove 47 to define a helical fluid flow path within the second portion 26 of the bore 16. The helical flow path is bounded by the first portion

46 of the second member 40 and the second portion 26 of the bore 16. The helical flow path has a first end 52 at the junction of the first and second portions 24 and 26 of the

bore 16. The helical flow path has a second end 54 at the end of the first portion 46 adjacent the second portion 48

The second portion 48 of the second member 40 is of the same diameter as the packing 34, and is arranged to be supported by the packing 34.

The flow throttling apparatus 10 further comprises an inlet 62 and an outlet 64. The inlet

62 extends radially through the first member 12 to a location within the second portion 26

adjacent the packing 34. The outlet 64 is located at the first axial end 18 of the cylindrical

portion 24 described hereinabove. The second end 54 of the helical flow path opens adjacent the inlet 62.

In use, a two-phase fluid such as biodiesel and glycerine is introduced at high pressure

though the fluid inlet 62. The fluid flows at high pressure through the second portion 26 of the bore to the second end 54 of the helical flow path 47, thus providing a high pressure at the second end 54 of the helical flow path 47. The fluid flows along the helical flow path 47 to the first end 52. The second end 54 is

exposed to a relatively high pressure. As a result, a pressure gradient is established along

the helical flow path, and the pressure of fluid flowing along the flow path reduces from relatively high pressure at the second end 54 to relatively low pressure at the first end 52,

such as about atmospheric. The pressure gradient resists the flow of the fluid, resulting in the throttling effect described above.

At the same time, the fluid is subjected to centrifugal effects which force the higher density glycerine phase towards the outside of the helical flow path, with the lower density biodiesel phase towards the inside. As a result, there is limited mixing of the two phases, and the tendency for them to emulsify is reduced.

The fluid recovered from the first end 52 is thus separated into two distinct phases. The length of the helical flow path can be altered by moving the second member 40 in an

axial direction to vary its position relative to the first member 12 so that it is more in or out. This serves to vary the flow restriction and hence pressure difference between the first end 52 and the second end 54

Modifications and variations as would be apparent to a skilled addressee are deemed to be within the scope of the present invention