SYSTEM FOR HYDROCARBON RECOVERY

Abstract

A filtration device, used to filter a cooling gas in an integrated compressor unit. A gas is circulated in two directions between two concentric cylindrical walls forming a duct. The walls are part of a removable inner cartridge and the motor housing of the integrated motor compressor unit, on which the cartridge is mounted. The gas enters the duct through an inlet, divides into two streams flowing downwards and meets again from two opposite directions at the bottom of the duct. It creates a turbulent zone in front of a first outlet, where some of the larger particles are trapped and fall into the first outlet via gravity. The filtered particles fill the duct and pass through upper second outlets which are provided at an intermediate location in the duct. The filtered gas passes through the second outlets and reaches an inner passage leading to bearings that require cooling.

Claims

1. A filtration device configured for filtering a cooling gas associated with an integrated compressor unit, wherein the filtration device comprises: an outer housing having an inner cylindrical wall, an inner cartridge having an outer cylindrical wall and an inner passage for a filtered gas, the inner cartridge being mounted in the outer housing and defining therewith a duct located between an inlet for the cooling gas and a first outlet for trapped particles, the inner cartridge having an assembly of at least one second filtering outlet extending between the duct and the inner passage and between the inlet and the first outlet.

2. The filtration device according to claim 1, wherein each second outlet comprises an axis extending upstream, from the point of view of a cooling gas flow.

3. The filtration device according to claim 1, wherein the filtration device comprises a pair of opposite second outlets.

4. The filtration device according to claim 1, wherein the direction of the second outlet is between 135° and 170° with respect to the downstream direction of the cooling gas flow from the inlet.

5. The filtration device according to claim 1, wherein each second outlet comprises a filter cartridge.

6. The filtration device according to claim 1, wherein the filtration device further comprises a container connected to the first outlet and adapted to collect the trapped particles.

7. The filtration device according to claim 1, wherein the filtration device further comprises a means for controlling the opening of the first outlet.

8. The filtration device according to claim 1, wherein the inner wall has a flat portion facing the first outlet.

9. The filtration device according to claim 1, wherein the filtration device forms a support for an active magnetic bearing.

10. An integrated compressor unit, comprising: a motor housing, a compression stage passing through the motor housing and adapted to compress a gas from an inlet to an outlet, the gas having a first particle with a first size and a second particle with a second size which is greater than the first size of the first particle, the compression stage comprising: a compressor, a rotary electric motor coupled to the compressor and comprising a rotary shaft assembled into the integrated motor compressor unit, by means of active magnetic bearings, a cooling circuit configured for cooling the active magnetic bearings using the outlet gas delivered by the outlet of the compression stage, the integrated compressor unit further comprising a filtration device according to claim 1, which is removably mounted on the motor housing.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Other objects, features and advantages of embodiments of the present invention will be better understood from a detailed study of the following description, which is provided solely by way of non-limiting example, and with reference to the accompanying drawings in which

[0028] FIG. 1 schematically shows a cartridge filtration according to the current state of the art;

[0029] FIG. 2 schematically shows a cross-section of the filter device according to a first embodiment of the present invention;

[0030] FIG. 3 schematically shows a cross-section of the filter device of FIG. 2, further comprising optional cartridge filters;

[0031] FIG. 4 is a perspective view of the inner cartridge alone of the filter device, according to the embodiment of FIG. 2; and

[0032] FIG. 5 schematically shows an integrated motor compressor unit comprising the filtration device of FIG. 2.

DETAILED DESCRIPTION

[0033] FIGS. 2, 3 and 4 schematically show a filtration device 1 in which a cooling gas is circulated and subjected to filtration. In the illustrated embodiment, the filtration device 1 is intended to be placed before the arrival of the cooling gas on the active magnetic bearings (“AMB”), in order to protect them. However, a filtration device of this type can be used to filter the cooling gases of any type of rotary element of an integrated motor compressor unit (“IMC unit”). The cooling gas may, for example, be natural gas or a mixture of gases such as air, composed of undesirable particles or comprising such particles. In these gases, polluting particles of different kinds can be dispersed. For example, impurities such as metal particles, rust particles, condensation, water droplets or oil droplets may float in the gas due to corrosion or mechanical deterioration of the components of the IMC unit during its normal operation. The filtration device makes it possible to trap the largest of these undesirable particles, for example having sizes of between 3 microns and 10 microns. When the gas has an excessive quantity of these undesirable large polluting solid particles, the operation of the AMB bearings can be disturbed. It is because they rotate and are sensitive to clogging, blockage or even scratches that AMB bearings are threatened when the gas circulates to cool them.

[0034] As shown in FIGS. 2, 3 and 4, the filtration device 1 comprises an inner cartridge 2 forming an inner AMB bearing support ring, namely an AMB support ring, assembled in an outer housing 3 corresponding to at least a portion of the IMC unit, for example the motor housing of the IMC unit. The inner cartridge 2 may be designed to fit one or more other portions of the IMC unit, for example, the bearing supports. For example, the inner cartridge 2 can be screwed onto the housing of the IMC. The inner cartridge 2 has an outer cylindrical wall W0 and an inner passage 4 for the filtered cooling gas. The AMB bearings to be cooled are connected to the inner passage 4 which is located in the central region of the filtration device 1.

[0035] The outer housing 3 comprises a cylindrical inner wall W1. The outer cylindrical wall W0 is enclosed in the cylindrical inner wall W1. The inner and outer cylindrical walls extend along the same longitudinal axis X, defining a duct 5 between them, in which the gas can circulate.

[0036] The duct 5 is located between an inlet 6 for the cooling gas and a first outlet 7 for the trapped particles. The duct 5 may correspond substantially to a tubular space. In the embodiment of FIG. 2, this tubular space has approximately an ovoid shape, brought to a cross-sectional plane, with a longer axis corresponding to a vertical ascending axis Z. With respect to the vertical ascending axis 3, the duct 5 has a maximum height (a top) and a minimum height (a bottom) as shown in FIG. 2.

[0037] The duct 5 is hermetic with respect to the gas particles, so that the gas in the duct 5 can flow only in the duct 5.

[0038] The inlet 6 comprises at least one hole which passes through the outer housing 3 to allow the cooling gas to enter the duct 5. The inlet 6 may, for example, be equipped with a nozzle, a tube and/or a valve to allow the gas to enter, for example, by means of a compressor.

[0039] The first outlet 7 comprises at least one hole passing through the outer housing 3 from the duct 5.

[0040] Advantageously, the inlet 6 is located as close as possible to the top of the duct 5. The fact of providing an inlet 6 high up makes it possible to lengthen the trajectory of the particles in the duct 5 in which they are filtered. An inlet 6 located at a higher position also facilitates the trapping of large particles by virtue of gravity, since this makes it possible to obtain a longer path of gas in the duct 5. Likewise, it is thus possible to obtain a filtration device 1 with vertical symmetry.

[0041] It is advantageous that the first outlet 7 is located substantially around the bottom of the duct 5 where the turbulence of the flow is formed and where the undesirable particles are trapped.

[0042] Advantageously, the inner cartridge 2 comprises a set of at least one second filtering outlet 8a, 8b. Each second outlet 8a, 8b is provided to pass through the inner cartridge 2, allowing the gas contained in the duct 5 to reach the inner passage 4. The gas can circulate only from the inlet 6 to the first outlet 7 or as far as at the second outlet 8a, 8b, at least one, through the duct 5.

[0043] According to a first embodiment, the filtration effect acts in the duct 5 filled with gas, before the gas passes through the second outlet 8a, 8b. The objective is to ensure that a maximum of undesirable particles fall under the effect of gravity towards the first outlet 7 and to trap them therein, in particular by creating a zone of turbulence of the gas flow, just above the first outlet 7, which prevents the particles from rising again to the second outlet 8a, 8b.

[0044] Each second outlet 8a, 8b is arranged at an intermediate location between the inlet 6 and the first outlet 7 of the duct 5 and constitutes a singularity which causes a point pressure drop in the gas flow, due to the narrowing of the second outlet 8a, 8b with respect to the diameter of the duct 5. The flow in the second outlet 8a, 8b may be lower than in the duct 5, in order to reduce to a minimum the suction of the undesirable particles in the gas flow entering the second outlet 8a, 8b.

[0045] The gas velocity at the inlet 6 and the locations of the second outlet 8a, 8b are chosen so that most of the undesirable particles pass in front of the second outlet 8a, 8b, without entering it, that is to say, with a speed high enough to withstand the local pressure drop, and go down in the duct 5 until reaching the first outlet 7 where the particle trap is located.

[0046] As shown in FIG. 2, the second outlet 8a, 8b passes through the inner cartridge 2, from a through hole having an inlet on the outer cylindrical wall W0 and an outlet on the inner passage 4. Advantageously, the outlet is arranged at a greater height than the inlet with respect to the vertical ascending axis Z. In other words, the gas flow turns off at the second outlet 8a, 8b, and a portion of the gas rises, i.e. it flows upstream, through the second outlet 8a, 8b. The angle O1, O2 between the axis of the through hole and the vertical axis must be chosen to be at least greater than 90°, if possible, with an acute angle of between 135° and 170°, to maximize the pressure drop and thus prevent large particles from entering the second outlet 8a, 8b.

[0047] An advantageous embodiment provides two second outlets 8a, 8b which both lead to the inner passage 4, through the inner cartridge 2 and from the duct 5, each of the outlets being located substantially in symmetry with each other, with respect to the vertical ascending axis Z. Advantageously, the second outlets 8a, 8b are substantially identical and arranged symmetrically at the same height between the duct 5 and the inner passage 4 and between the inlet 6 and the first outlet 7. It is advantageous that the second outlets 8a, 8b are oriented similarly upwards, with an axis extending upstream, with angles O1, O2 symmetrical with respect to the vertical axis Z. Advantageously, the cooling gas stream arriving from the inlet 6 is divided into two streams, as shown in FIGS. 2 and 3, towards each of the second outlets 8a, 8b. In each stream, the gas particles travel substantially half of the total length of the duct 5, because the two opposite streams meet when they reach the bottom of the duct 5, arriving from two opposite directions. Each of the two opposite streams prevents the other from going much further than half of the duct 5 and then back up to the second opposite outlet 8a, 8b. The presence of two symmetrical flows creates a turbulence point at the bottom of the duct 5, above the first outlet 7. This prevents undesirable particles from bouncing back up to one of the second outlets 8a, 8b. Each second outlet 8a, 8b may be placed as close as possible to the inlet 6 to prevent the return of the undesirable particles, especially in the case of inlet flow at high speed. However, because of their direction necessarily oriented upward, each second outlet 8a, 8b is positioned by taking into consideration the curvature of the inner cylindrical wall W1.

[0048] According to another embodiment, the outer cylindrical wall W0 comprises a flat portion 9 which faces the first outlet. As shown in FIGS. 2, 3 and 4, this flat portion 9 may, for example, be provided substantially horizontally on the outer cylindrical wall W0 and just above the first outlet 7. The flat portion 9 has two sharp edges 9a, 9b constituting discontinuities inside the duct 5, on the outer cylindrical wall W0 along which the gas flows. As shown in FIG. 2, the flat portion 9 also creates a widening of the duct 5. The streams of gas that meet in front of this widening and between the two sharp edges 9a, 9b of the flat portion will naturally create a turbulent flow. It is in this turbulent flow that the larger particles quickly lose their kinetic energy and eventually fall down under the effect of gravity. For this reason, the flat portion 9 is arranged as an obstacle to the vertical ascent of the particles and retains the largest particles.

[0049] Thanks to the filtration device 1 which is shown, described and claimed here, the undesirable particles can then be trapped by modulating several parameters which may, by way of non-limiting example, be the speed of the inlet gas flow, the angles O1, O2 of the second outlets, the length of the flat portion 9 and the sharpness of the edges 9a, 9b of the flat portion.

[0050] According to another embodiment shown in FIG. 3, a filter cartridge 10 is inserted into each second outlet 8a, 8b. Such a filter cartridge 10 may also, for example, be inserted into the duct 5, along the inner cylindrical wall or the outer wall W0. This filter may, for example, be a coalescing filter cartridge 10 adapted to naturally trap particles of the desired size, for example greater than 3 microns.

[0051] According to another embodiment, there is provided a container 11 which is connected to the first outlet 7. This container 11 makes it possible to collect the trapped particles which may accumulate in an underlying layer, at the bottom of the duct 5, under the effect of gravity, and eventually form a layer of sediment around the lower part of the duct 5 where they concentrate.

[0052] Control means 12 for opening the first outlet 7 may further be provided to facilitate the evacuation of the trapped particles, for example during a maintenance period. The control means 12 may, for example, comprise a valve and a tube for connecting the duct 5, for example, to the container 11 or to separate it from it.

[0053] In addition, the inner and outer cylindrical walls may, for example, be designed with specific shapes that are adapted to increase the cross section of the duct 5, along a circumference of the outer cylindrical wall W0 and from the inlet 6 to the first outlet 7. In other words, the inner and outer walls may have specific shapes, adapted so that the distance between them increases downward. For example, the diameter of the duct 5 may increase from the top to the bottom of the duct 5. This would allow the gas to expand gradually towards the outlets 7, 8a, 8b and, at the same time, the particles to slow down slightly. This widening of the duct 5, as well as the presence of the first outlet 7 and the flat portion 9, tend to divert and slow the flow of the fluid and to facilitate the fall of the larger particles downward, under the effect of gravity, to thereby improve the trapping of undesirable particles through the first outlet 7.

[0054] Reference will now be made to FIG. 5, which schematically represents a motor compressor unit equipped with the filtration device 1 disclosed above. As shown, the motor compressor unit designated by the reference 13 comprises an electric motor 14 and a compressor 15 having at least one compression stage 15 mounted on a shaft driven by a motor rotor. The driven shaft and the rotor are each supported by a pair of AMB bearings 16.

[0055] The AMB bearings 16 and the motor are cooled by means of a cooling loop 17 in which the cooling gas is taken from the flow of the process, in the first compression stage 15. Most of the cooling gas circulates in the electric rotary motor 14, and the rest of the gas flows in the direction of the AMB 16. At least one filtration device 1, as described above, can be assembled on the motor housing 18 of the motor compressor unit 13 and be placed in front of each arrival of the cooling gas on an AMB 16. A filtration device 1 of this type is then sized for a minor portion of the cooling gas flow.