EP3624952B1 - Multiphase fluid dispenser - Google Patents

Description

Background of the invention

The present invention relates to the general field of multiphase fluid distributors making it possible to divide in equal parts a fluid flow composed of several different phases into several fluid flows having the same flow rate and the same composition. at a longitudinal end of inlet ports and at an opposite longitudinal end of outlet ports is described in the document WO 2010/131958 A1 .

A particular field of application of the invention relates to underwater effluent treatment equipment used in the production of hydrocarbons, for example oil and gas, from subsea production wells.

The underwater treatment of hydrocarbons from subsea production wells is becoming a real need to make it possible to optimize production, in particular at great depths. Among the various means implemented for the underwater treatment of hydrocarbons, it is known to use underwater gravity separators of the gas / liquid type, called multi-pipe separators or condensate traps, which make it possible to optimize protection of wells as well as managing production stoppages and restarting by depressurizing production lines. It is also known to resort to submarine gravity separators of the liquid / liquid type (namely here oil / water) which are used to increase the recovery of oil and to reinject the water recovered in the production wells.

These various submarine gravity separators are advantageously segmented for applications at great depth, that is to say they are composed of several cylindrical enclosures of small diameter working in parallel; they require the implementation of the same principle consisting in distributing the multiphase fluid (namely a fluid having a gas phase and a liquid phase) in a plurality of identical multiphase fluid flow rates and of the same composition. This function is typically performed by a distributor whose inlet receives the multiphase fluid and separates it at its outlet into several multiphase fluid flows having the same flow rate.

Another particular field of application of the invention relates to the equitable distribution of a multiphase hydrocarbon production fluid in the multiple branches of a heat exchanger or in multiple exchangers which operate in parallel, for the purpose of cooling. or to heat this production fluid.

Yet another particular field of application of the invention relates to the equitable distribution of a production gas in the multiple branches of a condenser or in multiple condensers which operate in parallel, for the purpose of dewatering or condensing the gases. light phases of the gas, in order to condition it prior to transport along a pipeline at low temperature.

The distributors known from the prior art generally comprise a cylindrical inlet, of a size close to that of the supply pipe, at the bottom of which opens a succession of small orifices arranged axisymmetrically. So that this distribution is insensitive to the flow regime, the distributor is generally arranged vertically, with the inlet at the bottom and the outlet openings at the top, in order to cancel out the effects that gravity could have on the location of the phases. just before the distribution. Furthermore, the feed pipe will advantageously be positioned vertically and of a length greater than ten times its diameter so that the multiphase flow presents an axisymmetric facies (at least on average over a period of a few seconds), a guarantee of fairness. of distribution.

Depending on the desired application, these dispensers may have certain limitations.

The height of several meters of these distributors makes them bulky, which can be problematic for the architecture of the subsea installation, particularly when the installations downstream of the distribution are at a relatively low altitude.

Moreover, due to the application of the distribution function to the entire inlet flow, these distributors do not make it possible to separate the gas from the liquid. However, for reasons of optimization of the size of the downstream equipment, or for reasons of efficiency, it may be necessary to extract the gas phase in order to distribute only the liquid phases to the downstream treatment installations. It will indeed be very advantageous to extract the gas phase at the level of the distributor to bypass the liquid / liquid separators (water / oil for example) or the heat exchangers or other equipment, to reinject it downstream of the treatment, since the efficiency and the size of this equipment are clearly affected by the amount of gas passing through them.

Purpose and summary of the invention

The main aim of the present invention is therefore to provide a multiphase fluid distributor which does not have the aforementioned drawbacks.

According to the invention, this object is achieved by means of a multiphase fluid distributor according to claim 1.

The operation of the distributor according to the invention is as follows: the multiphase fluid enters the interior of the enclosure through the inlet orifice, being injected tangentially thereto. Thanks to the centrifugal force, the liquid phase of a gas / liquid fluid will press against the internal wall of the enclosure to form a liquid film flowing in a helical gyratory movement, while the gaseous part of the gas / fluid liquid will form a central gas flow flowing longitudinally from bottom to top at the center of the liquid film. The multiphase fluid entering the interior of the enclosure is directed towards the opposite end of the enclosure, so that the particles of the liquid film thus created follow upward helical paths. On reaching the opposite end of the enclosure, the liquid film is ejected under the effect of centrifugal force from the enclosure through the outlet orifices. As for the gaseous phase of the multiphase fluid, it will accumulate in the center of the upper part of the enclosure and will be able to flow through the upper part of the outlet orifices. If the liquid film however occupies the entire section of these orifices, this gaseous phase will see its pressure increase until it escapes periodically through the outlet orifices in passing through the liquid film when its pressure becomes greater than that of the outlet orifices (phenomenon of rapid pulsations).

The equidistribution of different phases of the multiphase fluid thus results from the axial symmetry of the distributor and the axial symmetry of the flow within the enclosure. Furthermore, it has been observed that the multiphase fluid is evacuated fairly through the various outlet orifices, provided that the speed of centrifugation of the fluid is sufficient and that the pulsation of the intermittent expulsion of the gas phase of the multiphase fluid takes place. also fairly.

For this purpose, a minimum tangential speed of 0.8m / s as well as a minimum axial speed of 0.1m / s for all the combined phases are necessary in the enclosure. These speeds are obtained by the appropriate sizing of the enclosure and its internal elements as a function of the fluid flow rates to be considered. As for the pulsation of the expulsion of the gaseous phase through the liquid film in front of the outlet orifices, this is carried out equitably provided that the pressures prevailing in each of the outlet orifices are substantially balanced.

The distributor further comprises fluid guiding means for imparting a helical movement to the fluid flowing inside the enclosure from the inlet port to the outlet ports.

The fluid guide means can advantageously comprise a guide ramp having the shape of a helix centered on the longitudinal axis of the enclosure. In this case, the guide ramp can be carried by a cylinder centered on the longitudinal axis of the enclosure or by an internal wall of the enclosure. When carried by a cylinder, the latter also advantageously carries a deflector positioned opposite the inlet orifice to help the fluid to take the guide ramp.

Furthermore, the inlet orifice advantageously opens inside the enclosure forming an inclined angle in the direction of the outlet orifices. The inlet orifice may form an angle with a transverse axis of the enclosure which is substantially equal to an angle of the helix of the guide ramp. Preferably, the angle of the inlet port and the helix of the guide ramp with the transverse axis of the enclosure is between 5 ° and 30 °.

The dispenser may further comprise a ring of erosion-resistant material centered on the longitudinal axis of the enclosure and positioned inside the latter, said ring being provided with a plurality of fluid passage slots. each positioned opposite an outlet orifice.

For certain applications such as liquid / liquid separators or heat exchangers for example, the enclosure may further include a gas exhaust port centered on the longitudinal axis of the enclosure and located at the longitudinal end of the enclosure. enclosure at which the outlet openings are positioned. This exhaust orifice makes it possible to extract as much gas as possible upstream of the distribution so as to minimize the gas content of the distributed fluid.

The enclosure may be formed by the sealed assembly between a box and a cover, the inlet port being formed in the box and the outlet ports being formed in the lid.

Preferably, the fluid guide means are configured to allow the fluid to make two turns around the longitudinal axis of the enclosure from the inlet orifice to the outlet orifices. This characteristic makes it possible to obtain an enclosure of great compactness by reducing the travel distance between the inlet orifice and the outlet orifices.

Brief description of the drawings

• la figure 1 est une vue en perspective d'un distributeur selon un mode de réalisation de l'invention ;
• la figure 2 est une vue de côté du distributeur de la figure 1 ;
• les figures 3 à 5 sont des vues en coupe de la figure 2, respectivement selon III-III, IV-IV et V-V ;
• la figure 6 est une vue de côté d'un distributeur selon un autre mode de réalisation de l'invention ;
• la figure 7 est une vue en coupe selon VII-VII du distributeur de la figure 7 ;
• la figure 8 est une vue en coupe transversale du distributeur montrant ses orifices de sortie ; et
• la figure 9 est une en perspective montrant une rampe de guidage pouvant équiper les distributeurs des figures 1 et 6.

Other characteristics and advantages of the present invention will emerge from the description given below, with reference to the appended drawings which illustrate exemplary embodiments thereof without any limiting nature. In the figures:

• the figure 1 is a perspective view of a dispenser according to one embodiment of the invention;
• the figure 2 is a side view of the distributor of the figure 1 ;
• the figures 3 to 5 are sectional views of the figure 2 , respectively according to III-III, IV-IV and VV;
• the figure 6 is a side view of a dispenser according to another embodiment of the invention;
• the figure 7 is a sectional view along VII-VII of the distributor of the figure 7 ;
• the figure 8 is a cross-sectional view of the dispenser showing its outlets; and
• the figure 9 is a perspective view showing a guide ramp that can be fitted to the distributors of figures 1 and 6 .

Detailed description of the invention

The invention relates to a multiphase fluid distributor fitted to subsea effluent treatment equipment, in particular segmented gravity separators which are used in the production of hydrocarbons in deep offshore.

By “multiphase fluid” is meant here a fluid comprising at least two different phases, for example a liquid phase and a gas phase.

The figures 1 to 5 show a distributor 2 according to a first embodiment of the invention.

The distributor 2 comprises in particular a cylindrical enclosure 4 of longitudinal axis X-X positioned vertically. At its lower longitudinal end, the enclosure 4 comprises an inlet orifice 6 for the multiphase fluid. At its upper longitudinal end opposite the lower end, the enclosure has a plurality of cylindrical outlet openings 8.

More precisely, the inlet orifice 6 opens inside the enclosure 4, on the one hand in a direction substantially tangential to the latter, and on the other hand by forming an angle α with an axis transverse YY of the enclosure which is inclined in the direction of the outlet openings 8. This angle α is preferably between 5 ° and 30 °.

In this way, the multiphase fluid enters the enclosure of the distributor in its lower part while being driven in an upward helical movement around the longitudinal axis XX of the enclosure. The tangential orientation of the inlet orifice makes it possible in particular to limit the impact of the multiphase fluid jet against the internal wall of the enclosure and facilitates the rapid formation of a liquid film in helical rotation, pressed against the internal wall. distributor body 4.

As for the outlet orifices 8, they are on the exemplary embodiment of figures 1 to 5 eight in number and are regularly distributed around the longitudinal axis XX of the enclosure.

In addition, the outlet orifices 8 each have a cylindrical shape with a respective longitudinal axis 8a, these longitudinal axes 8a all being situated in the same transverse plane P of the enclosure 4. The cross section (of circular shape) of the orifices of outlet is identical for all the outlet orifices and they open inside the enclosure in a direction substantially tangential thereto.

Moreover, as shown in the figure 5 , the respective longitudinal axes 8a of two adjacent outlet orifices 8 form between them an angle β which is preferably less than 30 °, this angle β being the same for all the outlet orifices.

Thus, the distribution of the outlet orifices 8 has axial symmetry with respect to the longitudinal axis X-X. It follows that when the liquid pressed against the internal wall of the enclosure and driven in an upward helical movement around the longitudinal axis XX of the enclosure reaches the level of the transverse plane P, it is ejected, under the effect of centrifugal force, in all of the outlet orifices, the flow rate ejected of fluid through each outlet orifice being substantially the same for all of the outlet orifices due to the regularity of the thickness of the liquid film and of its ascending helical motion.

The distributor according to the invention further comprises fluid guiding means for imparting a helical movement to the fluid flowing inside the enclosure from the inlet orifice to the outlet orifices.

For this purpose, a guide ramp 10 having the shape of a helix centered on the longitudinal axis XX of the enclosure 4 of the distributor is positioned inside the enclosure between the inlet orifice 6 and the orifices output 8.

As shown on figures 3 and 4 , this helix-shaped guide ramp 10 can be more precisely carried by a cylinder 12 which is centered on the longitudinal axis XX of the enclosure. Alternatively, this guide ramp could be carried by the internal wall of the enclosure.

Furthermore, the orientation and the angle formed by the helix of the guide ramp 10 with a transverse axis YY of the enclosure are identical to the orientation and the angle α formed by the inlet orifice. 6 with this transverse axis.

The operation of the distributor 2 follows from the above. The multiphase fluid enters from below into the enclosure 4 of the distributor tangentially thereto and is directed towards the top of the distributor at an angle of between 5 ° and 30 ° with respect to the horizontal. Under the effect of the centrifugal force, the liquid phase of the multiphase fluid will develop a liquid film pressed against the internal wall of the enclosure, this liquid film, where appropriate, borrowing the guide ramp 10 to be directed towards the upper part of the chamber. the enclosure where the outlet orifices 8 are positioned. As for the gaseous phase of the multiphase fluid, it will concentrate in the center of the enclosure to rise to the top of the enclosure.

Arrived at the level of the upper part of the enclosure, the liquid film flowing helically around the longitudinal axis XX is ejected under the effect of centrifugal force out of the enclosure into each outlet orifice 8 in being evenly distributed for all outlets. As for the gaseous phase of the multiphase fluid, it will accumulate in the center of the upper part of the enclosure and will be able to flow through the upper part of the outlet orifices. If the liquid film however occupies the entire section of these orifices, this gas phase will see its pressure increase until it escapes periodically through the outlet orifices 8 when its pressure exceeds that of the outlet orifices (phenomenon of pulsation).

In the embodiment of figures 1 to 4 , it will be noted that the distributor 2 further comprises a ring 14 which is centered on the longitudinal axis XX of the enclosure and which is positioned inside the latter, this ring being provided with a plurality of slits of fluid passage 16 which are each positioned opposite an outlet port 8.

The presence of this ring 14 with its fluid passage slots 16 upstream of the outlet orifices 8 has the advantage of allowing the use of materials resistant to erosion, such as ceramic, tungsten carbides, etc. in areas with sharp edges to be protected from erosion that can be induced by high flow velocities and solid particles possibly entrained by the fluid, while retaining for the other parts of the distributor the use of more conventional materials, less expensive and easier to machine, such as carbon steel, iron-nickel alloys, etc.

Still in the embodiment of figures 1 to 4 , it will also be noted that the enclosure 4 is formed by the assembly between a box 18 and a cover 20, the inlet orifice 6 being formed in the box 18 and the outlet orifices 8 being formed in the cover. This assembly is sealed by means of an annular weld joint 22 between these two elements.

In conjunction with figures 6 to 8 , we will now describe a dispenser according to a second embodiment of the invention. In this second embodiment, the distributor is for example used in an underwater gravity separator of the oil / water type, or a multitube heat exchanger.

With this type of treatment and according to the specifications of the particular application case (size, weight, efficiency), it may be necessary to extract as much gas as possible from the multiphase fluid upstream of the distribution so as to minimize the content of gas from the fluids at the outlet of the distributor, therefore at the inlet of the treatment equipment.

To this end, and with respect to the first embodiment described above, the enclosure 4 'of the distributor 2' of this second embodiment further comprises a gas exhaust port 24 which is centered on the longitudinal axis XX of the enclosure and which is located at the longitudinal end of the enclosure at which the outlet openings 8 'are positioned. In addition, a buffer zone 26 is arranged within the enclosure 4 'between the outlet orifices 8' and the gas exhaust orifice 24.

The operation of this distributor 2 ′ is as follows. The multiphase fluid enters the enclosure 4 ′ of the distributor tangentially thereto and is directed towards the top of the distributor at an angle of between 5 ° and 30 ° with respect to the horizontal. Under the effect of centrifugal force, the liquid phase of the fluid will develop a liquid film pressed against the internal wall of the enclosure, this liquid film, where appropriate, borrowing the guide ramp 10 'to be directed towards the upper part of the chamber. the enclosure where the outlet openings 8 'are positioned. As for the phase gaseous from the multiphase fluid, it will concentrate in the center of the chamber to rise to the top of the chamber.

Arrived at the level of the upper part of the enclosure, the liquid film flowing helically around the longitudinal axis XX of the enclosure 4 'is ejected under the effect of centrifugal force outside the enclosure in each outlet port 8 'being distributed equally for all the outlet ports.

As for the gas phase of the multiphase fluid, it will accumulate at the level of the buffer zone 26 in the upper part of the enclosure 4 '. In this buffer zone, the gas will get rid of the last drops of liquid which are entrained radially by centrifugal force and vertically by their own weight to join the liquid film and be evacuated through the outlet orifices 8 '. When the gas pressure in this buffer zone exceeds that of the gas exhaust port 24, the gaseous phase of the multiphase fluid will be evacuated by the gas exhaust port but also by the outlet ports, provided that the pressure which y reign remains strictly less than that reigning in the outlet orifices 8 '.
Provision may be made to position a coalescing system (mesh network or other) at the inlet of the gaseous exhaust orifice in order to filter the liquid particles or to position diaphragms at different heights above the outlet orifices 8 '.

According to an advantageous arrangement of the invention common to the two embodiments previously described and illustrated on figure 9 , the cylinder 12, 12 'which carries the guide ramp 10, 10' also carries a deflector 28 which is positioned opposite the inlet orifice. This deflector helps the fluid to take the guide ramp.

Claims (11)

1. A multiphase fluid dispenser (2; 2') comprising a cylindrical enclosure (4; 4') having, at one longitudinal end, an inlet orifice (6; 6') and, at an opposite longitudinal end, a plurality of cylindrical outlet orifices (8; 8') of the same right section that are regularly distributed around a longitudinal axis (X-X) of the enclosure and that are aligned in a common plane (P) extending transversely to the enclosure, each of the inlet and outlet orifices opening inside the enclosure along a direction that is substantially tangential to the enclosure, the dispenser further comprising fluid guide means (10; 10') for imparting helical motion to the fluid flowing inside the enclosure from the inlet orifice towards the outlet orifices.
2. A dispenser according to claim 1, wherein the fluid guide means comprise a guide ramp (10; 10') in the form of a helix centered on the longitudinal axis of the enclosure.
3. A dispenser according to claim 2, wherein the guide ramp (10; 10') is carried by a cylinder (12; 12') centered on the longitudinal axis of the enclosure, or by an inside wall of the enclosure.
4. A dispenser according to claim 3, wherein the cylinder further carries a deflector (28) positioned facing the inlet orifice (6; 6') to assist the fluid in being guided by the guide ramp.
5. A dispenser according to any one of claims 2 to 4, wherein the inlet orifice (6; 6') opens inside the enclosure with an angle (α) sloping towards the outlet orifices (8; 8').
6. A dispenser according to claim 5, wherein the inlet orifice (6; 6') forms an angle (α) with a transverse axis (Y-Y) of the enclosure that is substantially equal to the helix angle of the guide ramp.
7. A dispenser according to claim 6, wherein the angle formed by the inlet orifice and by the helix of the guide ramp relative to the transverse axis of the enclosure lies in the range of 5° to 30°.
8. A dispenser according to any one of claims 1 to 7, further comprising a ring (14) of erosion-resistant material centered on the longitudinal axis of the enclosure and positioned inside it, said ring being provided with a plurality of fluid-passing slots (16), each positioned in register with a respective outlet orifice.
9. A dispenser according to any one of claims 1 to 8, wherein the enclosure (4') further comprises a gas exhaust orifice (24) centered on the longitudinal axis of the enclosure and situated at the longitudinal end of the enclosure where the outlet orifices (8') are positioned.
10. A dispenser according to any one of claims 1 to 9, wherein the enclosure is formed by a sealed assembly of a vessel (18) and a lid (20), the inlet orifice being formed in the vessel and the outlet orifices being formed in the lid.
11. A dispenser according to any one of claims 1 to 10, wherein the fluid guide means (10; 10') are configured to enable the fluid to make two turns around the longitudinal axis of the enclosure on going from the inlet orifice to the outlet orifices.

Images