Method and device for treating of a gas/liquid admixture

Method and device for treating a gas/liquid mixture, the device comprising: an inlet for infeed of the mixture; a flow element placed in the line of the inlet and having one or more swirling members to cause turbulence of the mixture; an outlet placed in the line of the flow element for outfeed of the gas flow having liquid at least partially removed; one or more feedback lines for discharge of the separated liquid and a part of the gas flow, wherein the feedback lines are connected onto a channel arranged centrally in the flow element; and anti-creep flow means for preventing creep flow along the flow element.

BACKGROUND OF THE INVENTION
 1. Field of the Invention
 The present invention is directed to a compact gas/liquid separator having
 a creep flow interrupter.
 2. Description of the Related Art
 Gas/liquid separators generally take a bulky form in order to make certain
 that the separation efficiency required in determined conditions is
 ensured. In practice however, problems occur in difficult conditions, such
 as high operating pressures, high viscosity of the liquid or in conditions
 where the space is limited, such as occur for instance in offshore oil
 fields. Poor gas/liquid separators can considerably impair the production
 yields of oil fields.
 SUMMARY OF THE INVENTION
 The present invention provides a device for treating a gas/liquid mixture,
 comprising:
 an inlet for infeed of the mixture;
 a flow element placed in the line of the inlet and having one or more
 swirling members to cause turbulence of the mixture;
 an outlet placed in the line of the flow element for outfeed of the gas
 flow having liquid at least partially removed;
 one or more feedback lines for discharge of the separated liquid and a part
 of the gas flow,
 wherein the discharge line is connected onto a channel arranged
 substantially centrally in the flow element and wherein close to the end
 of the channel an anti-creep flow element is arranged for preventing creep
 flow of liquid.
 In contrast to existing separating devices wherein a mixture flows through
 a set of parallel plates or through a layer of net-like wires or wherein
 use is made of a traditional cyclone wherein liquid is introduced therein
 radially, the present device has extremely compact dimensions, achieves a
 high separation efficiency which does not depend (or depends little) on
 liquid viscosity, has an extremely low pressure drop and/or a
 wide-ranging-option of decreasing the flow rate (turn down ratio).
 The anti-creep flow means are preferably formed by an anti-creep flow
 element close to the end of the channel. It is however also conceivable to
 arrange such anti-creep flow means at another location in the device
 according to the present invention or to have them formed by a determined
 dimensioning of the flow element and/or the swirling members and/or by
 preselected values of the flow speed of the mixture and/or the pressure
 ratios in the device according to the present invention.
 The present invention further provides a method for treating a gas/liquid
 mixture, wherein a device according to any of the foregoing claims is
 applied. The present invention likewise relates to a system for treating a
 gas/liquid mixture from a bored well in the earth's crust, comprising:
 an outer pipeline which is lowered into the bored well;
 an inner pipeline which is arranged in the outer pipeline while leaving
 clear and suitably arranged to form a radial space; and
 a plurality of parallel placed gas/liquid separating devices which are
 arranged in the radial space and which each comprise an inlet for infeed
 of the mixture, a flow element placed in the line of the inlet and having
 one or more swirling members to cause turbulence of the mixture, the
 outlet placed in the line of the flow element for outfeed of the gas flow
 having liquid at least partially removed and one or more feedback lines
 for discharge of the separated liquid and a part of the gas flow.
 Partly due to the extremely compact dimensions, devices according to the
 present invention can herein be disposed in considerable numbers in a
 circular arc between the casing and the tubing in a borehole, whereby
 so-called decks are formed, while a plurality of such decks can likewise
 be placed in series for separation of for instance 99.5% of the liquid and
 the gas.
 In the sub-claims further steps are designated for an extremely compact
 embodiment of the device according to the present invention, in addition
 to the method wherein use is made of one or more such devices.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
 A device 1 (FIG. 1) comprises a substantially cylindrical wall 2 having an
 upstream end and a downstream end which bounds a flow space 3. Placed in
 flow space 3 is a flow body 4 which is provided on its outer periphery
 with curved swirling blades 5 and in the interior of which is arranged a
 channel 6. A creep interrupter 7 is arranged on the top (downstream) end
 of channel 6. Under an outlet opening 8 the device 1 is provided with
 elongate slots openings 9.
 During operation of the device or cyclone 1 according to the present
 invention a mist of gas and liquid (droplets) is supplied through an inlet
 in the direction of arrow A into the flow space 3, whereafter this liquid
 flow acquires a cyclone-like flow pattern due to swirling blades 5. Due to
 the centrifugal force the liquid particles are moved at least to a
 considerable extent radially out of the gas flow via the longitudinal
 slots 9 in the direction of arrows B, together with for instance 20% of
 the quantity of gas, while the remaining gas flow with at least a large
 part of the liquid removed leaves the device in the direction of arrow C
 via outlet opening 8. Gas flows B are fed back, as indicated with broken
 lines D, to a secondary inlet 11 which fluidly connects onto a channel 12
 to the internal channel 6 in the flow body 4.
 This secondary gas flow in the direction of arrows B and E serves to
 increase the efficiency of discharge of solid particles such as dust
 particles, and thus also contributes toward cleaning of the gas flow.
 Owing to the cyclone action of the swirling blades a relatively low
 pressure is present at the outlet of internal channel 6, whereby the
 secondary, fed back gas flow is drawn in by the main flow.
 It has been found in practice that close to the transition of the outlet
 channel of flow body 4 and space 3 creep flow of liquid can take place
 along the surface thereof due to the relatively low pressure there, which
 would mean that this liquid would be carried along by the fed back gas
 flow and would enter the outfeed flow C. In order to prevent this
 undesired effect a creep flow interrupter 7 is arranged in the device
 according to the present invention which deflects the liquid flow outward
 along the flow element 4 so that the liquid can be carried along by the
 turbulence current on the outer side of the flow body.
 In the shown preferred embodiment of FIG. 1 the creep interrupter takes the
 form of a hollow truncated cone, while in the embodiment of FIG. 2 a creep
 interrupter element 17 takes the form of a substantially flat dish.
 The extremely compact device according to the present invention causes only
 a very small pressure drop in the flow of the mixture of for instance 30
 mBar, brings about a high separating efficiency and is not susceptible to
 great changes in operating conditions. Manufacturing costs for a device
 according to the present invention can be extremely low.
 The present invention is not limited to the above described preferred
 embodiments thereof; the rights applied for are defined by the following
 claims.