Gas-liquid separation device with a zone for directing liquid at the outlet end, especially for a three-phase fluidized bed reactor

Abstract

The present invention relates to a gas-liquid separation device, in particular for use in the recirculation zone of a three-phase fluidized bed reactor. The gas-liquid separation device comprises a plurality of separation elements, each having an inlet duct (70) and at least two consecutive bends (71, 72), the first bend (71) being located in a plane (zy), the axis of the first bend (71) forming an orientation angle α: 45°-315° relative to the vertical axis z, and the second bend (72) forming a second orientation angle β: 1°-135° with the first bend (71). The two first consecutive bends (71, 72) are spaced apart by a distance D1 of D / 2-4D, D being the diameter of the inlet duct (70). Each separation element comprises a liquid guider (73), which is arranged at the outlet end of the second bend (72) and has an open cross section.

Description

[Technical field]

[0001] The present invention resides in improving the design of gas-liquid separators used especially in H-Oil® processes to obtain better gas-liquid separation in the upper zone of the reactor (often referred to as the liquid recycle zone, or more simply the recycle zone).

[0002] The H-Oil® process is a process for the hydroconversion of heavy hydrocarbon fractions of the type of residual or vacuum gas oil, which therefore brings together a liquid hydrocarbon phase, a hydrogen gas phase dispersed in the form of bubbles, and the catalyst itself dispersed in the form of solid particles whose particle size is typically between 0.2 and 2 millimeters.

[0003] The H-Oil® process is therefore a three-phase flow process using a dedicated reactor equipped with a gas-liquid separation device located at the top of the reactor, allowing the recycling of liquid, which after separation is returned to the reaction zone of the reactor. One of the significant features of H-Oil® type reactors is their high liquid recycling ratio, defined as the ratio of the flow rate of the recycled liquid to the flow rate of the incoming liquid feedstock, which is generally in the range of 1-10.

[0004] The present invention may be defined as an improved gas-liquid separation device, in particular for H-Oil® type reactors, which allows the majority of the liquid to be reintroduced into the reaction zone without the gas, while the gas (and also part of the liquid) is removed from the reactor, limiting turbulence and foaming effects at the gas-liquid interface.

[0005] However, the gas-liquid separation device may be used in other applications. [Background technology]

[0006] A patent application (Patent Document 1) is known, which describes the concept of a "spiralizer" (or "cyclone separator") for gas-liquid separation in the H-Oil® process by the number of rotations of the spiral and the angle relative to the horizontal position.

[0007] The "recycle cup" described in that patent application corresponds to the upper part of the reactor, which allows, after separation of gas and liquid, the liquid to be returned to the reaction zone of the reactor and the gas to be removed by a dedicated pipe.

[0008] In the remainder of the text the expression upper liquor recycle zone, or more simply, recycle zone, will be used.

[0009] The '161 patent also describes an upper recycle zone arrangement with a gas-liquid removal pipe at the top of the reactor.

[0010] Figure 1 is a representative diagram showing the key elements of a prior art H-Oil® reactor, such as that in US Pat. No. 5,399,366. The diagram shows a reaction zone (22), which corresponds to a three-phase fluidized bed containing the catalyst, a zone located above the catalyst zone, referred to as a gas-liquid separation zone (39), which allows liquid to be recycled to the lower part of the reactor by means of a recirculation pump (20).

[0011] The gas-liquid separation device is represented by separation elements (27) and (28), some elements having their lower ends located in the gas-liquid separation zone (39) and other elements having their lower ends located on the surface of the "recycle cup" (30).

[0012] The three-phase fluidized bed reactor (10) is specially designed with suitable materials which enable it to process reactive liquids, liquid / solid "slurries" (i.e. suspensions, i.e. liquids containing fine solid particles dispersed therein), solids and gases at high temperatures and pressures, and finds suitable application in the hydrogen treatment of liquid hydrocarbon fractions at high temperatures and pressures, i.e. pressures of 2 MPa to 35 MPa, preferably 5 MPa to 25 MPa, more preferably 6 MPa to 20 MPa absolute, and temperatures of 300°C to 550°C, preferably 350°C to 500°C, more preferably 370°C to 460°C, with the favoured temperature range being 380°C to 440°C.

[0013] A three-phase fluidized bed reactor (10) of the H-Oil® type is designed, which has suitable inlet pipes (12) for injecting the heavy hydrocarbon feedstock (11) and the gas containing hydrogen (13). The outlet pipe is located at the top of the reactor (10). The outlet pipe (40) is designed to withdraw vapors which may contain a certain amount of liquid, and, as an alternative, the pipe (24) allows mainly the liquid to be withdrawn. The reactor also contains a system allowing the catalyst particles to be introduced and withdrawn, which system corresponds generally to the pipe (15) for introducing fresh catalyst (16) and the pipe (17) for withdrawing the spent catalyst (14).

[0014] A heavy hydrocarbon feedstock is introduced through pipe (11) while a hydrogen-containing gas is introduced through pipe (13). The mixture of feedstock and gaseous hydrogen is then introduced into the reactor (10) through pipe (12) at the bottom of the reactor.

[0015] The incoming fluid passes through a plate (18) which contains an appropriate distributor.

[0016] In this diagram, a "foam cap" type distributor (19) is shown, but it should be understood that any distributor known to those skilled in the art that allows the fluid coming from the pipe (12) to be distributed over the entire surface of the reactor (10) and as evenly as possible can be used.

[0017] The gas-liquid mixture flows upward and the catalyst particles are entrained in the ebullated bed motion by the gas and liquid flows induced by a recirculation pump (20) which may be internal or external to the reactor (10).

[0018] The upward flow of liquid delivered by pump (20) is sufficient to expand the volume of the catalyst bed or catalyst beds (22) in the reaction zone by a minimum of 10%, preferably 20-100%, relative to the static volume of the catalyst bed (i.e., the volume at rest), thus allowing gas and liquid to flow through the reactor (10) as indicated by directional arrows (21).

[0019] Due to the balance between the frictional forces generated by the upward flow of liquid and gas and the downward force of gravity, the bed of catalyst particles reaches an upper level of expansion, while the liquid and gas (which are lighter) continue beyond this solids level towards the top of the reactor (10). In the diagram, the level of maximum expansion of the catalyst corresponds to the interface (23). Below this interface (23) is the catalytic reaction zone (22), which thus extends from the plate (18) to the level (23) and contains the catalyst.

[0020] Above the interface 23 is a zone 39 containing only gas and liquid. The catalyst particles within the catalytic reaction zone 22 move randomly in a fluidized state, which is why the catalytic reaction zone 22 qualifies as a three-phase fluidized zone.

[0021] The zone (29) containing a low concentration of catalyst above the level of the interface (23) is filled with liquid and entrained gas. The gas is separated from the liquid in the upper part of the reactor, called the "recycle zone" (39), which collects and recycles most of the liquid through a central outlet duct (25) at the bottom of a recycle cup (30). The shape of the recycle cup (30) (as a funnel) allows the liquid to be collected after the separation between gas and liquid and conveyed to the central outlet duct (25). In order to avoid the phenomenon of cavitation in the pump (20), it is important that the liquid recycled through the central outlet duct (25) contains as little gas as possible, or even no gas at all.

[0022] The liquid product remaining after gas-liquid separation can be withdrawn through pipe 24. Pipe 40 is used to withdraw the gas.

[0023] The enlarged section at the upper end of the pipe (25) forms the liquid recycle zone. A plurality of vertically oriented separation elements (27) and (28) create the connection between the gas-liquid zone (29) and the recycle zone (39).

[0024] The gas-liquid mixture flows upwards through the pipes of the separation elements (27) and (28). Some of the separated liquid is then directed through the central outlet duct (25) in the direction of arrow (31) to the recirculation pump (20) and is thus recycled to the lower part of the reactor (10) below the plate (18).

[0025] The gas separated from the liquid flows towards the top of the reactor (10) and is withdrawn through the top pipe (40). The withdrawn gas (40a) is then treated in a conventional manner to recover as much hydrogen as possible, which is recycled to the reactor through pipe (13).

[0026] A patent application (US Pat. No. 5,399,633) is also known, which relates to an improved gas-liquid separation device for three-phase fluidized bed reactors of the H-Oil® type, which ends in two successive bends, as in Figures 2 and 3, improving the separation of the liquid and gas phases.

[0027] FIG. 2 is a more accurate diagram of the recycle zone (39) of the '611 patent in a reactor such as the reactor in FIG.

[0028] Figure 2 shows a liquid recycle zone, which ends in a central outlet duct (25) which, after gas-liquid separation, returns the liquid to the lower part of the reactor via a recirculation pump. Gas-liquid separation elements (27) and (28) are installed along the conical surface (30) of the recycle zone. The gas-liquid mixture is admitted via an inlet pipe (70). The gas-liquid separation takes place in the separation devices (55). Each separation device (55) therefore consists of a tubular inlet element (70) for admitting the gas-liquid mixture, and ends in two successive bends located in two different planes, as illustrated in Figure 3: - the first plane, denoted (yz), is perpendicular to the x-axis; - The second plane, denoted (xy), is perpendicular to the z-axis.

[0029] The transition between two successive bends has no vertical height. The vertical measurement (along the z-axis) of the first bend and the vertical measurement (along the z-axis) of the second bend are substantially the same. "Substantially" is understood to mean a vertical offset that does not exceed the value D of the diameter of the gas-liquid mixture inlet pipe (70).

[0030] The liquid flowing after leaving the separation elements along the conical wall (30) is collected by a central outlet duct (25) and the gas is removed by an outlet in the second bend of each separation element (27) and (28). The gas thus occupies the upper zone (39v) of the separation zone (39) located above the gas-liquid interface (24) and leaves the reactor via the outlet pipe (67).

[0031] The gas and liquid flow upwards, as indicated by the directional arrows (41) in FIG. 2, and are introduced through the inlet pipe (70), where they experience a change of direction of in each case about 90° at a first bend and a second bend terminating in the separation elements (27) and (28).

[0032] The gas-liquid interface level (24) separates an upper portion (39v) containing mainly separated gas from a lower portion (39L) containing mainly recycled liquid. The various separated liquids (45) leaving the second bends of the separation elements (27) and (28) flow downwards through the conical wall (30) and are collected by the central outlet duct (25) and recovered by a recirculation pump (not shown).

[0033] The majority of the liquid (31) is therefore recycled to the recirculation pump through a central outlet duct (25). The gas and a small amount of liquid (67) are extracted through a pipe (40), which generally has a slot (65) at its lower end, which makes it possible to fix the height of the liquid-gas interface (24).

[0034] FIG. 3 shows the geometry of a gas-liquid separation device according to US Pat. No. 5,399,323 and indicates key geometrical dimensions for illustrating the dimensions of this device.

[0035] The diameter of the inlet pipe (70) of each separation element is generally 0.02 m to 0.5 m, preferably 0.05 m to 0.4 m, and preferably 0.1 m to 0.3 m.

[0036] The superficial velocity of the upward flowing liquid, represented by the directional arrow (41) in FIG. 1, is generally between 0.1 m / s and 20 m / s, preferably between 0.2 m / s and 15 m / s, preferably between 0.3 m / s and 10 m / s.

[0037] The first bend, lying in the plane (yz), has its orientation defined by its angle α, which has a value between 45° and 315°, preferably between 60° and 300°, and preferably between 80° and 200°.

[0038] The second bend, lying in the plane (xy), has its orientation defined by its angle β, the value of which is between 0° and 135°, preferably between 10° and 110°, preferably between 30° and 100°.

[0039] The height H1 between the gas-liquid interface (24) and the second bend in the plane (xy) is between D and 10D, preferably between 2D and 5D, where D is the diameter of the pipe (70).

[0040] The distance D1 separating two successive bends is between D / 2 and 4D, preferably between D / 2 and D, where D is the diameter of the pipe (70).

[0041] Although the separation device in Figures 2 and 3 has many advantages, it can also generate turbulence and bubbles which should be avoided.

[0042] The invention therefore consists in limiting the turbulence generated by the gas-liquid separation device and minimizing the generation of bubbles, thus minimizing the risk of entrainment of gas bubbles with the liquid recycled to the pump for reintroduction into the reactor, these bubbles being prone to generate cavitation within the pump, which can damage it and limit its useful life.

[0043] To this end, the present invention relates to a gas-liquid separation device, in particular a device for installation in the recycle zone of a three-phase fluidized bed reactor used in a method for hydroconversion of heavy hydrocarbon cuts under high pressure in the presence of hydrogen, the recycle zone being made up from the upper hemisphere of the reactor and bounded at its lower part by a surface configured to allow the separated liquid to return to the catalytic zone. The gas-liquid separation device according to the invention comprises a plurality of separation elements operating in parallel and vertically, preferably installed from or passing through a surface configured to allow the separated liquid to return to the catalytic zone, when the device is installed in the recycle zone of a three-phase fluidized bed reactor, each separation element having a (individual) inlet pipe for admitting the gas-liquid mixture. Preferably, when the gas-liquid separation device is installed in the recycle zone of a three-phase fluidized bed reactor, each separation element can open into a (for example conical or hemispherical) surface configured to allow the separated liquid to return (i.e. be recycled) to the catalytic zone, each separation element rising to a height H in the separation zone.

[0044] Furthermore, each separation element comprises at least two bends in succession, which are arranged (fixed) (in the direction of fluid flow) at the outlet of the inlet pipe, the first bend being located in a plane (zy) defined by a substantially vertical z-axis and a y-axis belonging to a plane (xy) perpendicular to the z-axis, the axis of the first bend being defined by a first orientation angle α: 45°-315°, preferably 60°-300°, preferably 80°-200° with respect to the vertical z-axis, the axis of the second bend forming with the axis of the first bend a second orientation angle β: 1°-135°, preferably 10°-110°, preferably 30°-100°, and the two bends in succession (hence the first bend and the second bend) being separated by a distance D1 between D / 2 and 4D, preferably between D / 2 and 2D, where D is the diameter of the inlet pipe. Further, each separation element comprises a liquid guiding device, which is arranged at the outlet end of the last bend of the series of at least two bends, and when the system is on a vertical axis (i.e. when the inlet pipe is vertical) and the outlet cross-section of the liquid guiding device is arranged vertically below the inlet cross-section of the liquid guiding device, the liquid guiding device is open at the top throughout the entire liquid guiding device from the inlet cross-section to the outlet cross-section. [Prior art documents] [Patent documents]

[0045] [Patent Document 1] U.S. Pat. No. 4,886,644 [Patent Document 2] US Patent Application Publication No. 2019 / 270941 Summary of the Invention [Means for solving the problem]

[0046] (Summary of the invention) The present invention relates to a gas-liquid separation device, comprising a plurality of separation elements, operating in parallel and arranged vertically, each separation element having an inlet pipe for admitting a gas-liquid mixture and at least two bends in series, the first bend being located in a plane (zy) defined by a substantially vertical z-axis and a y-axis belonging to a plane (xy) perpendicular to the z-axis, the axis of the first bend being oriented in a plane (zy) perpendicular to the vertical z-axis. The axis of the second bend forms with the axis of the first bend a second orientation angle α: 45°-315°, preferably 60°-300°, preferably 80°-200°, the axis of the second bend forms with the axis of the first bend a second orientation angle β: 1°-135°, preferably 10°-110°, preferably 30°-100°, the first and second bends are separated by a distance D1 between D / 2 and 4D, preferably between D / 2 and 2D, D being the diameter of the inlet pipe. Furthermore, each separation element comprises a liquid guiding device, which is arranged at the outlet end of the last bend of the series of at least two bends, which is open over its entire length from its inlet cross section to its outlet cross section (widely along the device for distributing a fluid) in the direction of the flow of the fluid in this device for distributing a fluid, and the outlet cross section of the liquid guiding device is arranged vertically below the inlet cross section of the liquid guiding device.

[0047] Preferably, the gas-liquid separation device is configured to be installed in the recycle zone of a three-phase fluidized bed reactor used in a process for hydroconversion of a heavy hydrocarbon fraction under high pressure in the presence of hydrogen, the recycle zone being assembled from the upper hemisphere of the reactor and bounded at its lower part by a surface configured to allow the separated liquid to return to the catalytic zone, the distance separating the outlet end of the last bend from the gas-liquid interface in the recycle zone being between D and 10D, preferably between 2D and 5D.

[0048] Advantageously, the angle formed by the second bend with respect to the plane (zy) is between 1° and 90°, preferably between 1° and 45°, and more preferably between 1° and 20°.

[0049] According to one configuration of the invention, the liquid directing device comprises at least one deflector and / or at least one slot.

[0050] Preferably, the liquid guiding device (pipe part of the liquid guiding device) opens with an opening angle of 60° to 179°, preferably 90° to 150°, more preferably 100° to 130° relative to the median line. In other words, each cross section of the liquid guiding device forms an opening angle of 60° to 179°, preferably 90° to 150°, more preferably 100° to 130° along the liquid guiding device, from its inlet cross section to its outlet cross section, between the end point of this cross section (which is open by definition, the guiding device opens to the top) and the center of the median axis of this cross section: 60° to 179°, preferably 90° to 150°, more preferably 100° to 130°.

[0051] Advantageously, the vertical height of the liquid conducting device is between D / 2 and 8D, preferably between 2D and 5D.

[0052] According to one embodiment of the invention, the inlet cross section of the liquid guiding device and the outlet cross section of the liquid guiding device form an angle of rotation in the plane (x,y), said angle of rotation being between 45° and 200°, preferably between 90° and 180°.

[0053] Preferably, the outlet cross section of the liquid directing device has an elliptical profile, an inverted elliptical profile or a flattened profile (the outlet cross section forms a straight line segment).

[0054] The invention also relates to a three-phase fluidized bed reactor for the hydroconversion of heavy hydrocarbon cuts under high pressure in the presence of hydrogen, said reactor comprising a recycle zone assembled from the upper hemisphere of the reactor and bounded in its lower part by a surface configured to allow the separated liquid to return to the catalytic zone, said recycle zone comprising a gas-liquid separation device as described above.

[0055] The present invention also relates to a process for three-phase fluidized bed hydroconversion of heavy hydrocarbon fractions using a gas-liquid separation device, in which the operating conditions are as follows: - absolute pressure: 2 MPa to 35 MPa, preferably 5 MPa to 25 MPa, more preferably 6 MPa to 20 MPa, and Temperature: 300°C to 550°C, preferably 350°C to 500°C, more preferably 370°C to 430°C; the favourable temperature range is 380°C to 430°C.

[0056] Advantageously, the superficial velocity of the upward flow in each inlet pipe is between 0.1 m / s and 20 m / s, preferably between 0.2 m / s and 15 m / s, more preferably between 0.3 m / s and 10 m / s.

[0057] Preferably, the volume fraction of the liquid in the inlet pipe is between 0.05 and 0.95, preferably between 0.1 and 0.8, more preferably between 0.3 and 0.6.

[0058] Other features and advantages of the separation device, reactor and method according to the invention will become apparent on reading the following description of non-limiting exemplary embodiments, with reference to the accompanying drawings, which are described below. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0059] (List of Drawings) FIG. 1 shows a three-phase fluidized bed reactor with a gas-liquid separation device according to the prior art.

[0060] FIG. 2 shows a gas-liquid separation device in a three-phase fluidized bed reactor with two bends in series according to the prior art.

[0061] FIG. 3 shows a gas-liquid separation device having two bends according to the prior art.

[0062] FIG. 4 shows a gas-liquid separation device having a liquid directing device according to the invention.

[0063] FIG. 5 shows a first example of a liquid directing device of a separation element of a gas-liquid separation device according to the invention.

[0064] FIG. 6 illustrates different variants of the liquid directing device of the separation element of the gas-liquid separation device according to the invention.

[0065] FIG. 7 shows an inlet cross section of a liquid directing device of a separation element of a gas-liquid separation device according to the invention.

[0066] FIG. 8 shows a first example of a semi-elliptical outlet cross-section of a liquid directing device of a separation element of a gas-liquid separation device according to the invention.

[0067] FIG. 9 shows a second example of an inverted semi-elliptical outlet cross section of a liquid directing device of a separation element of a gas-liquid separation device according to the invention.

[0068] FIG. 10 shows a third example of a flat outlet cross section of a liquid directing device of a separation element of a gas-liquid separation device according to the invention.

[0069] FIG. 11 shows a comparison of the profiles of the liquid volume fraction at the gas-liquid interface between a gas-liquid separation device ending in two bends according to the prior art a) and a gas-liquid separation device having a liquid directing device according to the invention b).

[0070] (Description of the embodiment) The present invention relates to a gas-liquid separation device, in particular to be installed in the recycle zone of a three-phase fluidized bed reactor used in the process for hydroconversion of heavy hydrocarbon cuts under high pressure in the presence of hydrogen, said process being known under the name H-Oil®.

[0071] The device may be used in any type of installation that has a need for gas-liquid separation.

[0072] The gas-liquid separation device can also be used in other systems in which separation between gas and liquid is necessary, for example in separators of the ISS (Internal Stage Separator) type or the HHPS (Hot and High Pressure Separator) type, which separators are used in processes for the hydroconversion of heavy hydrocarbon fractions.

[0073] When the device is installed in the recycle zone of a three-phase fluidized bed reactor, the fluid flow scheme shown in Figure 1 is not modified in the present invention with respect to the prior art as described above. The only thing that is modified is the geometry of the separation elements (27) and (28) in Figure 1.

[0074] The expression "three-phase fluidized bed process" is understood to mean a process in which three phases are present in the reaction zone: a liquid phase, generally constituting the feedstock to be treated; a gas phase, generally hydrogen, which is under high pressure; and a solid phase, which corresponds to the catalyst divided into solid particles and has a diameter usually between 0.2 mm and 2 mm, preferably between 0.7 mm and 1.5 mm.

[0075] The three-phase fluidized bed reactor in which the gas-liquid separation device can be installed comprises a recycle zone, which is assembled from the upper hemisphere of the reactor and bounded in its lower part by a surface configured to allow the separated liquid to return to the catalytic zone, for example via a central outlet duct allowing the separated liquid to be collected. The surface configured to allow the separated liquid to return to the catalytic zone may for example be conical or hemispherical.

[0076] The recycle zone of a three-phase fluidized bed reactor is therefore divided into an upper part containing gas and a lower part containing liquid. In an operating reactor, these two zones are separated by a gas-liquid interface.

[0077] The gas-liquid separation device comprises a plurality of separation elements, which are operated in parallel and are arranged vertically (preferably from a surface configured to allow the separated liquid to return to the catalytic zone or through this surface if the device is installed in the recycle zone of a three-phase fluidized bed reactor), each separation element having an inlet pipe for admitting the gas-liquid mixture arranged for a downward flow of the gas-liquid mixture (preferably opening at a surface configured to allow the separated liquid to return to the catalytic zone and rising to a height H inside the separation zone if the device is installed in the recycle zone of a three-phase fluidized bed reactor) and at least two bends in the series, which are fixed to each other. The inlet pipe is substantially vertical. The bends in the series are arranged and fixed at the outlet of the inlet pipe in the direction of flow of the gas-liquid mixture in the separation element. The terms "first", "second", "third", "fourth", "next", "previous" or "last", when they are associated with "bends", are understood in the direction of flow of the fluids in the at least two bends in the series. The first bend is therefore the one that is first passed by the fluid in the direction of flow of the fluid (gas-liquid mixture). The series of at least two bends is arranged at the outlet of the inlet pipe so as to force the fluid leaving the inlet pipe to pass through the series of bends. The passage through the series of at least two bends allows an effective separation of the liquid and the gas.

[0078] A "concave" surface is understood to mean a surface that forms a hollow, i.e. a shape that is rounded towards the inside. A "convex" surface is understood to mean a curved surface, i.e. a shape that is rounded towards the outside.

[0079] The terms "vertical", "horizontal", "up", "down", "upper", "lower", "top" and "bottom" are understood in relation to the gas-liquid separation device in its operational condition (in its operational condition).

[0080] In this description, the vertical axis is considered to point upwards; the angles considered in this description are therefore given with respect to this upward orientation of the vertical axis.

[0081] The first bend lies in a plane (zy) defined by a substantially vertical z-axis and a y-axis belonging to a plane (xy) perpendicular to the z-axis. In other words, the plane (zy) is a substantially vertical plane and the plane (xy) is a substantially horizontal plane. The axis of the first bend is defined by a first orientation angle α to the vertical z-axis (which substantially corresponds to the axis of the inlet pipe): 45°-315°, preferably 60°-300°, preferably 80°-200°. The first bend is fixed at the outlet of the inlet pipe.

[0082] The second bend is fixed to the first bend (at the end opposite to that fixed to the inlet pipe). In other words, it is in the continuation of the first bend. The axis of the second bend forms a second orientation angle β with the axis of the first bend. The second orientation angle β is between 1° and 135°, preferably between 10° and 110°, preferably between 30° and 100°. Preferably, the second bend is in a plane that forms a non-zero angle with the plane (zy), for example, the second bend may be in a substantially horizontal plane (xy). Therefore, the first and second bends are not coplanar. By using these two successive bends (i.e. the first and second bends) in two planes that intersect each other, the separation of the liquid and the gas is promoted. Furthermore, these two successive bends are separated by a distance D1 between D / 2 and 4D, preferably between D / 2 and 2D, where D is the diameter of the inlet pipe.

[0083] According to one embodiment of the present invention, the gas-liquid separation device of the present invention may contain 10-50 separation elements, preferably 20-40 separation elements, improving the capacity for separating liquid and gas. The number of separation elements depends, inter alia, on the flow rate to be treated.

[0084] Furthermore, each separation element includes a liquid guiding device, which may take the form of a chute. The purpose of this liquid guiding device is to gently convey the liquid towards the outlet (for example the central outlet duct of a three-phase fluidized bed reactor). The liquid guiding device is arranged (in the direction of flow of the gas-liquid mixture) at the outlet end of the last bend of at least two bends in the series. The bends are fixed to each other in series and the guiding device is fixed to the outlet end of the last bend. For example, if at least two bends in the series include four bends fixed to each other, the liquid guiding device is fixed to the fourth bend; if at least two bends in the series include two bends fixed to each other, the liquid guiding device is fixed to the second bend. The liquid guiding device is open at the top, allowing the gas to escape upwards and directing the liquid downwards. Thus, the open part (particularly of the pipe section) of the liquid guiding device is arranged at the top, allowing the gas to escape, while the lower part (particularly of the pipe section) of the liquid guiding device guides the liquid.

[0085] The liquid directing device may be assembled from pipe sections extending from an inlet cross section to an outlet cross section.

[0086] Furthermore, the liquid guiding device is open at the top (the pipe section of the liquid guiding device is open) and distributes the fluid widely (over its entire length) along the liquid guiding device in the direction of the flow of the fluid in said liquid guiding device from the inlet cross section to the outlet cross section. The pipe section is open over the entire length of the liquid guiding device, the length being measured along the neutral axis of the liquid guiding device from the inlet cross section to the outlet cross section. The term "pipe section" refers to a section in the form of a pipe whose cross section is open over its entire length.

[0087] Thanks to this liquid directing device, which is open over its entire length, the liquid can be directed by the cross section of the device, while the gas can escape thanks to the opening at the top. Separation between these two fluids is then facilitated.

[0088] Moreover, the outlet cross section of the liquid directing device is located vertically below the inlet cross section of the liquid directing device. Therefore, by the effect of gravity applied to the liquid, the device directs the liquid downwards in the desired direction. The directing device simultaneously directs the liquid in the desired direction (e.g., towards the outlet duct for recirculation to the pump of the three-phase fluidized bed reactor) by gently conveying it in this direction, thus limiting the phenomena of turbulence and foaming.

[0089] The liquid directing device (particularly the pipe section) may, inter alia, include a change of direction, which is preferably continuous and has no gradient breaks in the direction of fluid flow within the device from the inlet cross section to the outlet cross section.

[0090] Preferably, the cross section of the liquid guiding device may be constant along the liquid guiding device (over the entire length of the liquid guiding device) from the inlet cross section to the outlet cross section. Alternatively, the cross section of the liquid guiding device may vary continuously and seamlessly along the liquid guiding device (over the entire length of the liquid guiding device) from the inlet cross section to the outlet cross section.

[0091] The liquid directing device therefore forms a chute from the inlet cross section to the outlet cross section: the pipe section is open at the top, the lower part of the pipe section directs the liquid by gravity and the gas can escape from the top, at the top of the pipe section, by means of an opening.

[0092] Preferably, the distance H1 separating the outlet end of the last bend of the series of at least two bends from the gas-liquid interface, for example in the recycle zone of a three-phase fluidized bed reactor, may be between D and 10D, preferably between 2D and 5D, allowing an effective separation of gas and liquid.

[0093] Advantageously, the second bend may form an angle with the plane (zy) between 1° and 90°, preferably between 1° and 45°, more preferably between 1° and 20°. The second bend is therefore not in a plane that is coplanar with the plane of the first bend. By using these two successive bends (i.e. the first and the second bend) in two mutually intersecting planes that in particular form the above mentioned angle, the separation of the liquid and the gas is promoted.

[0094] Advantageously, the liquid directing device may comprise at least one deflector (preferably several deflectors) and / or at least one slot (preferably several slots).

[0095] The use of a deflector improves the distribution of the liquid over the cross section of the guide device by preventing the liquid from concentrating at the bottom, and therefore makes it possible to limit the acceleration of the liquid.

[0096] The use of slots also slows the liquid and gently conveys it towards the outlet, improving liquid distribution.

[0097] By limiting the liquid velocity it is possible to reduce the amount of liquid movement and therefore limit its effects on the gas-liquid interface (turbulence, foaming).

[0098] According to an advantageous embodiment of the invention, the liquid directing device (in particular the pipe section) may open at an opening angle of 60° to 179°, preferably 90° to 150°, more preferably 100° to 130°, relative to the neutral line (for example the axis of the pipe section). This opening angle makes it possible to have a sufficiently large cross section for facilitating the removal of gas and for effectively directing the liquid.

[0099] Preferably, the vertical height of the liquid guiding device may be between D / 2 and 8D, preferably between 2D and 5D. The outlet cross section of the liquid guiding device is therefore above the gas-liquid interface and the height of the liquid guiding device is sufficient for it to act like a chute for the liquid to guide it towards the outlet.

[0100] Advantageously, the angle of rotation formed between the inlet cross section of the liquid guiding device and the outlet cross section of the liquid guiding device may be between 45° and 200°, preferably between 160° and 190°, in a substantially horizontal plane (xy). It is therefore possible to effectively direct the liquid towards the central outlet duct of the three-phase fluidized bed reactor. Furthermore, the liquid guiding device comprises a continuous and unbroken surface from the inlet cross section to the outlet cross section, so as to gradually guide the liquid arriving from the inlet cross section towards the outlet cross section. The guiding device thus forms a rounded (or curved) profile.

[0101] According to one variant of the invention, the outlet cross section of the liquid guiding device may be larger than the inlet cross section of the liquid guiding device. This enlargement of the cross section therefore makes it possible to increase the contact surface between the liquid and the liquid guiding device. It is therefore possible to limit the velocity of the liquid at the outlet of the guiding device. For example, if the inlet cross section of the liquid guiding device is a semicircular shape (or semicircular ring) with a diameter DD, the outlet cross section of the liquid guiding device may be a semicircular shape with a diameter between 1.2DD and 2DD.

[0102] According to an advantageous embodiment of the invention, the outlet cross section of the liquid guide device may be concave or convex or flat. If it is concave, it may have a circular (or toroidal) or elliptical profile. If it is convex, it may have an inverted elliptical or flat profile (i.e. forming a rectilinear cross section).

[0103] A concave cross section facilitates the guiding of the liquid by forcing it to be guided in the center of this cross section. A circular profile is simple to manufacture. An elliptical profile, in comparison with a circular profile, makes it possible to limit the local concentration of liquid in the center of the profile. The area in which the liquid is conveyed is therefore enlarged and therefore it is possible to limit the liquid velocity and its inertia, in particular with regard to its effect on the gas-liquid interface. A concave cross section also allows for an effective distribution of the liquid widely around the guiding device.

[0104] A convex cross section allows the liquid to be distributed widely and effectively around the liquid directing device. By enlarging the distribution zone, the concentration of liquid in a certain zone (compared to the central zone of a concave zone) is avoided and it is also possible to reduce the liquid velocity and its displacement. An inverted elliptical or triangular profile allows, inter alia, the liquid to be distributed effectively over the entire liquid directing device.

[0105] The flat profile (straight cross section) allows for a simple implementation while still distributing the liquid effectively.

[0106] The invention also relates to a three-phase fluidized bed reactor for hydroconversion of heavy hydrocarbon fractions under high pressure in the presence of hydrogen, the reactor comprising a recycle zone, assembled from the upper hemisphere of the reactor and bounded at its lower part by a surface (for example a conical or hemispherical surface) configured to allow the separated liquid to return to the catalytic zone, for example via a central outlet duct for conveying the liquid towards a pump to recycle the liquid. Furthermore, the recycle zone comprises a gas-liquid separation device as described above. The reactor corresponds to the reactor in FIG. 1, only the gas-liquid separation device is modified, as described above.

[0107] Furthermore, the present invention also relates to a process for the three-phase fluidized bed hydroconversion of heavy hydrocarbon cuts using a gas-liquid separation device as described above, preferably using a three-phase fluidized bed reactor as described above comprising a gas-liquid separation device according to the invention, the operating conditions being as follows: the absolute pressure is between 2 MPa and 35 MPa, preferably between 5 MPa and 25 MPa, more preferably between 6 MPa and 20 MPa, and The temperature is between 300°C and 550°C, preferably between 350°C and 500°C, more preferably between 370°C and 430°C, with the favourable temperature range being between 380°C and 430°C.

[0108] These pressures and temperatures allow for efficient processing for the hydroconversion of heavy hydrocarbon fractions in the presence of hydrogen.

[0109] Advantageously, the superficial velocity of the upward flow inside each inlet pipe may be between 0.1 m / s and 20 m / s, preferably between 0.2 m / s and 15 m / s, more preferably between 0.3 m / s and 10 m / s.

[0110] Preferably, the liquid volume fraction in the inlet pipe may be between 0.05 and 0.95, preferably between 0.1 and 0.8, more preferably between 0.3 and 0.6. The system is therefore suitable for a wide range of liquid volume fractions, where the liquid volume fraction represents the liquid volume relative to the total volume of the gas-liquid mixture reaching the inlet pipe.

[0111] FIG. 4 illustrates diagrammatically and non-limitingly a gas-liquid separation device according to the invention.

[0112] In the left figure it is possible to see the gas-liquid separation element, which includes an inlet pipe (70) and two turns (71) and (72) in series (although the turn in series could include more than two turns). The liquid directing device is not shown to facilitate understanding on the part of the reader.

[0113] In the right image it is possible to see the gas-liquid separation element equipped with a liquid directing device (73).

[0114] The gas-liquid separation elements in FIG. 4 may replace the separation elements (27) and (28) in FIGS. 1 and 2, and the gas-liquid separation device comprises several gas-liquid separation elements.

[0115] Each separation element comprises an inlet pipe (70) followed by two successive bends (71) and (72): - the first bend (71) is arranged in a plane indicated by (yz) which is perpendicular to the horizontal x-axis, the z-axis substantially corresponding to the vertical axis; - the second bend (72) is disposed in a plane that forms a non-zero angle with the plane (yz) of the first bend (71). The axis of the second bend forms an angle θ with a horizontal plane (xy). For example, the second bend (72) may be located in a substantially horizontal plane, denoted (xy), perpendicular to the z-axis; in this case the angle θ is zero.

[0116] Therefore, the two bends (71) and (72) lie in two non-coplanar planes, which intersect with each other.

[0117] Here, the continuous bend is comprised of two bends, however, the continuous bend may include more than two bends.

[0118] At the outlet (74) of the second bend (72) (in the direction of flow of the liquid in the gas-liquid separation element), the gas-liquid separation element comprises a liquid guiding device (73) in which the gas separated from the liquid can be removed from the top, the liquid guiding device (73) comprising an open cross section allowing the gas to escape upwards (e.g. towards the top of the reactor).

[0119] The openings in the pipe section of the liquid directing device (73) allow the liquid to be conveyed in the desired direction, and the surface of the liquid directing device (73) serves to direct the liquid. For example, the liquid directing device (73) may be configured in such a way that the liquid is directed towards the central outlet duct of the recycle cup of the reactor, as indicated by reference number (25) in Figure 1.

[0120] The inlet cross section of the liquid guiding device (73) (cross section fixed at the outlet (74) of the second and last bend) is arranged vertically above the outlet cross section of the liquid guiding device (73). The difference in axial height between the inlet and outlet cross sections of the liquid guiding device (73) corresponds to a height H. This makes it possible to guide the liquid under the effect of its own gravity.

[0121] Furthermore, the liquid directing device (73) may preferably be a 3D element, i.e. extending in the three axes x, y and z of an orthogonal coordinate system, which is not located in one plane (i.e. it is not 2D), and which includes a change in direction, in order to facilitate the directing of the liquid towards the outlet. This change in direction is preferably continuous, without any bevel breaks, and gradually directs the liquid. In other words, the surface of the liquid directing device forms a continuous change in direction, without any bevel breaks.

[0122] The liquid guide device (73) opens at an opening angle ω measured relative to the axis of the inlet cross section (corresponding to the neutral line or neutral axis of the inlet cross section). The inlet cross section of the liquid guide device (73) is semicircular because it is connected to the circular outlet cross section (74) of the second and final bend (72). It is called "semicircular" because it is open.

[0123] The exit cross section (75) of the liquid directing device (73) is also semicircular, although other shapes are possible. The exit cross section (75) of the liquid directing device (73) is larger than its entrance cross section; here the diameter of the exit cross section (75) is larger than the diameter of the entrance cross section. By enlarging the cross section of the liquid directing device in the direction of the flow of the fluid, it is possible to slow down said fluid and increase the surface over which it slides, which reduces the inertia of the liquid and therefore its effect on the gas-liquid interface.

[0124] The liquid directing device (73) therefore forms a chute for the liquid.

[0125] The liquid flowing after leaving the liquid directing device (73) reaches, for example, here along the conical wall of the three-phase fluidized bed reactor and is collected by a central outlet duct. The gas is removed via the outlet of the second and last bend through the open part of the liquid directing device (73). The gas thus occupies the upper end of the separation zone located above the gas-liquid interface and may leave the reactor, for example, via an outlet pipe (for example pipe (40) in Figures 1 and 2).

[0126] FIG. 7 illustrates diagrammatically and non-limitingly an inlet cross section of a liquid directing device.

[0127] The inlet cross section of the induction device is semicircular with diameter D equal to the diameter of the last bend, shown in the figure by a continuous black line, and opens at an opening angle ω measured relative to the axis of the inlet cross section (corresponding to the center of the circle with diameter D and indicated by point O corresponding to the neutral line or neutral axis of the inlet cross section) between the ends (80) and (81) of the inlet cross section.

[0128] In this figure, the z-axis corresponds to the vertical axis. It can be seen that ends (80) and (81) are not symmetrical about the vertical z-axis. This asymmetry allows for more effective guidance of the fluid despite the centrifugal forces to which the fluid is subjected as the fluid-guiding device changes direction through the angle of rotation.

[0129] FIG. 5 illustrates, diagrammatically and non-limitingly, a 3D view of a gas-liquid separation element according to the invention (left diagram) and a top view of the same gas-liquid separation element (right diagram).

[0130] The gas-liquid separation element comprises an inlet pipe (70), continued by two successive bends (71) and (72) in two mutually intersecting planes (but the successive bends may comprise more than two bends), the two planes being preferably perpendicular to each other. A liquid directing device (73) is fixed at the outlet of the second and last bend (72) and has an open part (open pipe section).

[0131] The inlet pipe (70) and the two bends (71) and (72) are of circular cross section with a diameter D. The semicircular inlet cross section Se of the liquid guiding device (73) also has a diameter equal to D. The outlet cross section So of the liquid guiding device (73) is also semicircular and has a diameter L equal to or greater than the diameter D of the inlet cross section.

[0132] Furthermore, a rotation occurs from its inlet cross section Se to its outlet cross section So as a result of the liquid guide device (73). The angle formed between the inlet cross section Se and the outlet cross section So is represented by an angle of rotation Υ between 45° and 200°, preferably between 90° and 180°.

[0133] FIG. 6 illustrates, in a schematic and non-limiting manner, different profiles of the outlet cross section of the liquid directing device of a gas-liquid separation element.

[0134] In this figure, the gas-liquid separation elements may, inter alia, be installed in place of the gas-liquid separation elements (27) and (28) in FIGS.

[0135] Diagrams a) to d) differ only in the liquid conducting device.

[0136] In diagram a) the profile of the outlet cross section is substantially a semi-triangle (76) with the apex of the triangle directed upwards. "Substantially semi-triangle" is understood to mean that the apex of the triangle may have a curvature and the third side of the triangle does not form part of the profile; in other words, this semi-triangle profile is in the shape of an inverted V. The liquid is therefore split into two streams with two directions on the two sides with respect to the apex of the triangle. Preferably, the triangle is isosceles or equilateral with respect to the apex, generating two streams with similar flow rates.

[0137] In diagram b), the profile of the outlet cross section is flat (77) (or linear). In other words, it is formed by straight line segments. The liquid can therefore flow over the entire surface without generating concentration zones, it is widely distributed around the outlet cross section. The inertia of the liquid is therefore distributed.

[0138] In diagrams c) and d) the outlet cross-sectional profile is semicircular.

[0139] In diagram c), the liquid guiding device comprises a deflector (78) which divides the liquid guiding device into several compartments, thus making it possible to prevent the liquid from concentrating in a single zone (for example a central zone). To do this, the deflector (78) preferably extends from the inlet cross section to the outlet cross section of the liquid guiding device, which results in a variation in the cross-sectional profile. The deflector may be used regardless of the profile of the outlet cross section.

[0140] In diagram d), the liquid directing device comprises a slot (or opening) that allows the liquid to escape upwards. It is therefore possible to gradually distribute the liquid downwards. The slot may be used regardless of the profile of the outlet cross section.

[0141] The variation in cross section of the induction device, regardless of its profile, from the semicircular inlet cross section to the outlet cross section, is gradual and continuous and has no bevel breaks.

[0142] Combinations of deflectors and slots are also possible, regardless of the exit cross-sectional profile.

[0143] FIG. 8 illustrates, in a schematic and non-limiting manner, a first example of a concave outlet profile of a liquid directing device.

[0144] The outlet cross section of the guiding device is semi-elliptical and is indicated in the figure by a continuous black line. The circle with diameter D indicated by a dashed line indicates the outlet cross section of the last bend (where the inlet cross section of the liquid guiding device begins) projected onto the plane of the outlet cross section. The z-axis represents the vertical axis and the x''-axis represents the horizontal axis.

[0145] With the aid of this figure it can be seen that the outlet cross section of the liquid guide device is larger than the inlet cross section.

[0146] Furthermore, the elliptical profile of the exit cross section is defined by an ellipse having a center c, a semi-major axis along axis X″ of length E, and a semi-minor axis along z-axis of length F. Axes X″ and z are defined by a circular profile at the exit of the bend having diameter D. The elliptical profile opens at an opening defined by angle ψ. The center c of the ellipse is spaced a length G from the X″ axis and a length H from the z axis, where H is equal to zero in the figures. The length E is between D / 4 and 5D, preferably between D / 2 and 3D. The length F is between D / 4 and 5D, preferably between D / 2 and 3D. The angle ψ is between 10° and 350°, and preferably between 90° and 180°. The length G is between 0.1F and F, preferably between 0 and F / 2. The length H is between -E and E, preferably between -E / 2 and E / 2.

[0147] In this figure, it can be seen that the ends (82) and (83) of the outlet cross section are symmetrical about the vertical z-axis. This symmetry on the outlet cross section allows for an effective distribution of the liquid, but this symmetry is not essential.

[0148] An elliptical profile has the advantage over a circular profile of increasing the surface over which the liquid is carried, and therefore makes it possible to reduce the velocity of the liquid and therefore limit its displacement.

[0149] FIG. 9 illustrates, in a schematic and non-limiting manner, a second example of a convex outlet profile of a liquid directing device.

[0150] The outlet cross section of the guiding device is of the shape of an inverted semi-ellipse (with respect to FIG. 8) and is indicated in the figure by a continuous black line. The circle with diameter D indicated in dashed lines indicates the outlet cross section of the last bend (where the inlet cross section of the liquid guiding device begins) and is projected onto the plane of the outlet cross section. The z-axis represents the vertical axis and the X″-axis represents the horizontal axis.

[0151] With the aid of this figure it can be seen that the outlet cross section of the liquid guide device is larger than the inlet cross section.

[0152] Furthermore, the inverted elliptical profile of the outlet cross section of the liquid directing device is defined by an inverted ellipse with a center C', a semi-major axis along the X'' axis of length E1 and a semi-minor axis along the z axis of length F1. The axes X'' and z are defined by a circular profile at the outlet of the last bend with a diameter D. The elliptical profile opens at an opening defined by an angle ψ1. The center C' of the ellipse is separated from the X'' axis by a length Gbis and from the z axis by a length H1, which in the diagram is zero: The length E1 is between D / 4 and 5D, preferably between D / 2 and 3D. The length F1 is between D / 4 and 5D, preferably between D / 2 and 3D. The angle ψ1 is between 10° and 350°, and preferably between 90° and 180°. The length Gbis is between 1.1F and 2F, preferably between F and 1.5F. The length H1 is between -E and E, preferably between -E / 2 and E / 2.

[0153] The advantages of this profile are quite similar to those of the triangular profile of diagram a) in Figure 6: it makes it possible to split the liquid flow in two on either side of the apex of the ellipse S1, which is the vertical uppermost point of the inverted semi-elliptical cross section.

[0154] In this figure, it can be seen that the ends (84) and (85) of the outlet cross section are symmetrical about the vertical z-axis. This symmetry on the outlet cross section allows for an effective distribution of the liquid, but this symmetry is not essential.

[0155] FIG. 10 illustrates, in a schematic and non-limiting manner, a third example of an outlet profile of a liquid directing device.

[0156] The outlet cross section of the guiding device is formed by a straight line segment, flat (or straight) and is shown in the figure by a continuous black line. The outlet cross section is formed by a straight line segment of length L1. The dashed circle with diameter D shows the outlet cross section of the last bend (where the inlet cross section of the liquid guiding device starts) projected onto the plane of the outlet cross section. The z-axis represents the vertical axis and the X''-axis represents the horizontal axis.

[0157] With the aid of this figure it can be seen that the outlet cross section of the liquid guide device is greater than the inlet cross section and that the length L1 is greater than D.

[0158] Furthermore, a flat profile forming a straight section of the outlet cross section of the liquid guider device is defined by a section of center cter and length L1. The center cter (corresponding to the middle of the section of length L1) is at a length Gter from the X'' axis and a length Hter from the z axis, which length Hter is zero in the diagram. The section of length L1 forms an angle δ with the vertical axis: The length L1 is between D / 4 and 5D, preferably between D / 2 and 3D. The length Gter is between 0.1D and 4D, preferably between D and 2D. The length Hter is between -2D and 2D, preferably between -D and D. The angle δ is between 60° and 120°, and preferably between 80° and 100°.

[0159] This profile distributes the liquid effectively and avoids liquid concentration zones.

[0160] In this figure, it can be seen that the section of length L1 is perpendicular to the vertical axis (angle δ equal to 90°) and that the centre cter is located on the vertical axis, therefore the section of length L1 is symmetrical with respect to the vertical z-axis.

[0161] (Example) FIG. 11 is an example of a comparison of the effect of the liquid leaving the gas-liquid separation element (27) of a system according to prior art application US 2019 / 270941 and a gas-liquid separation element (27) with a chute-type liquid directing device according to the present invention.

[0162] Diagrams a) and b) illustrate the level of turbulence generated by the influence of the liquid on the surface of the gas-liquid interface (24). The diagrams are derived by CFD (Computational Fluid Dynamics) numerical simulations. Diagram a) corresponds to the prior art of application US 2019 / 270941 and diagram b) corresponds to the configuration of FIG. 4 according to the invention.

[0163] The variation in grey level, indicating the liquid volume fraction, is zero for the clearest grey level (high purity gas), shown as black when the fluid is completely liquid.

[0164] Table [Table 1] gives the geometric parameters used in the numerical simulations.

[0165] [Table 1]

[0166] For these simulations, the gas-liquid interface is located 0.6 m from the axis of the exit cross section of the liquid directing device.

[0167] The following data are used in the numerical model: - the model is of Euler-Euler type with continuous liquid and gas dispersed bubbles, the bubble diameter is set equal to 1 mm; - Gas-liquid interaction follows the Schiller-Naumann drag law; - Turbulence follows a realizable k-ε model; - The bulk density of the liquid is 738.6 kg / m 3 and the viscosity is 0.48 cP (cP corresponds to the unit centipoise; 1 cP = 0.001 Pa s); - The bulk density of gas is 50.89 kg / m 3 and the viscosity is 0.024 cP (cP corresponds to the unit centipoise; 1 cP = 0.001 Pa s); - The flow rates at the inlet of the separation element are 7.886 kg / s for liquid and 0.394 kg / s for gas.

[0168] In the prior art diagram a) it is possible to see the generation of significant waves at the gas-liquid interface (24) (indicated by the grey fluctuations in the diagram which are evidence of a gas-liquid mixture in this zone), which therefore generates significant turbulence at the gas-liquid interface (24) under the influence of the liquid. This turbulence may be the cause of foaming.

[0169] In the diagram b) of the invention it is possible to see that the gas-liquid interface (24) (grey variations) is not disturbed. The level of turbulence is therefore significantly reduced thanks to the device of the invention. As a result it is also possible to reduce the risk of foaming.

[0170] The invention therefore makes it possible to limit turbulence and the risk of foaming at the gas-liquid interface. [Brief description of the drawings]

[0171] [Figure 1] 1 shows a three-phase fluidized bed reactor having a gas-liquid separation device according to the prior art. [Diagram 2] 1 shows a gas-liquid separation device in a three-phase fluidized bed reactor having two bends in series according to the prior art. [Diagram 3] 1 shows a gas-liquid separation device having two bends according to the prior art. [Figure 4] 1 shows a gas-liquid separation device with a liquid directing device according to the invention. [Diagram 5] 1 shows a first example of a liquid directing device of a separation element of a gas-liquid separation device according to the invention; [Figure 6] 2A-2C show different variants of the liquid directing device of the separation element of the gas-liquid separation device according to the invention. [Figure 7] 3 shows an inlet cross section of a liquid directing device of a separation element of a gas-liquid separation device according to the invention; [Figure 8] 2 shows a first example of a semi-elliptical outlet cross-section of a liquid directing device of a separation element of a gas-liquid separation device according to the invention; [Figure 9] 2 shows a second example of an inverted semi-elliptical outlet cross section of a liquid directing device of a separation element of a gas-liquid separation device according to the invention. [Figure 10] 3 shows a third example of a flat outlet cross section of a liquid directing device of a separation element of a gas-liquid separation device according to the invention. [Figure 11] FIG. 2 shows a comparison of the profiles of the liquid volume fraction at the gas-liquid interface between a gas-liquid separation device ending in two bends according to the prior art a) and a gas-liquid separation device with a liquid directing device according to the invention b).

Claims

1. A gas-liquid separation device comprising a plurality of separation elements (27) and (28), which are operated in parallel and are vertically arranged, each separation element (27, 28) having an inlet pipe (70) for admitting a gas-liquid mixture and at least two successive bends (71, 72), the first bend (71) being located in a plane (zy) defined by a substantially vertical z-axis and a y-axis belonging to a plane (xy) perpendicular to the z-axis, the axis of the first bend (71) being defined by a first orientation angle α of 45° to 315°, preferably 60° to 300°, preferably 80° to 200°, with respect to the vertical z-axis, the axis of the second bend (72) being defined by a second orientation angle β of 1° to 135°, preferably 10° to 1 1. A gas-liquid separation device, comprising: a first bend (71) and a second bend (72) each forming an angle of 10°, preferably 30° to 100°; the first bend (71) and the second bend (72) being separated by a distance D1 between D / 2 and 4D, preferably between D / 2 and 2D, D being the diameter of the inlet pipe (70); each separation element (27, 28) comprising a liquid guide device (73) arranged at the outlet end of the last bend of the series of at least two bends; the liquid guide device (73) being wide along the liquid guide device and opening from an inlet cross section (Se) to an outlet cross section (So) in the direction of fluid flow within the liquid guide device; the outlet cross section (So) of the liquid guide device (73) being arranged vertically below the inlet cross section (Se) of the liquid guide device (73).

2. 2. The device according to claim 1, wherein the angle formed by the second bend (72) with the plane (zy) is between 1° and 90°, preferably between 1° and 45°, more preferably between 1° and 20°.

3. 2. The device according to claim 1, wherein the liquid guide device (73) comprises at least one deflector (78) and / or at least one slot (79).

4. 2. The device according to claim 1, wherein the liquid guide device (73) opens at an opening angle (ω) of 60° to 179°, preferably 90° to 150°, more preferably 100° to 130° relative to the neutral line of the liquid guide device.

5. 2. A device according to claim 1, wherein the vertical height (H) of the liquid guide device (73) is between D / 2 and 8D, preferably between 2D and 5D.

6. 2. The device according to claim 1, wherein the inlet cross section (Se) of the liquid guide device (73) and the outlet cross section (So) of the liquid guide device (73) form an angle of rotation (Y) in the plane (x, y), said angle of rotation (Y) being between 45° and 200°, preferably between 90° and 180°.

7. 2. A device according to claim 1, wherein the outlet cross section (So) of the liquid guide device (73) has an elliptical profile or a flat profile forming a straight line segment.

8. 8. A three-phase fluidized bed reactor for the hydroconversion of heavy hydrocarbon fractions under high pressure in the presence of hydrogen, the reactor comprising a recycle zone (39) assembled from the upper hemisphere of the reactor and bounded at its lower part by a surface configured to allow the separated liquid to return to the catalytic zone, the recycle zone (39) comprising a gas-liquid separation device according to any one of claims 1 to 7.

9. A process for three-phase fluidized bed hydroconversion of heavy hydrocarbon fractions using a gas-liquid separation device according to any one of claims 1 to 7, wherein the operating conditions are as follows: the absolute pressure is between 2 MPa and 35 MPa, preferably between 5 MPa and 25 MPa, more preferably between 6 MPa and 20 MPa; and The temperature is between 300°C and 550°C, preferably between 350°C and 500°C, more preferably between 370°C and 430°C, with the favoured temperature range being between 380°C and 430°C.

10. 10. A process for three-phase fluidized bed hydroconversion of heavy hydrocarbon cuts according to claim 9, wherein the superficial velocity of the upward flow considered inside each inlet pipe (70) is between 0.1 m / s and 20 m / s, preferably between 0.2 m / s and 15 m / s, more preferably between 0.3 m / s and 10 m / s.

11. 10. A process for three-phase fluidized bed hydroconversion of heavy hydrocarbon fractions according to claim 9, wherein the volume fraction of the liquid in the inlet pipe is between 0.05 and 0.95, preferably between 0.1 and 0.8, more preferably between 0.3 and 0.6.

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