Inlet and distribution device

<img file="NL1024149C2_D0001.tif" />

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Netherlands © 1024149 © C PATENT²⁰ © Patent application: 1024149

Submitted: 22.08.2003 © lnt.CI.⁷

B01D50 / 00, B01D45 / 16

<td>© Registered:</td><td>© Patent holder (s):</td>

<td> 23.02.2005</td><td>Flash Technologies NV in Willemstad, Netherlands Antilles (AN).</td>

<td>© Date:</td><td>FMC Technologies CV in Chicago, Illinois,</td>

<td> 23.02.2005</td><td>United States of America (US).</td>

<td>© Published:</td><td>© Inventor (s):</td>

<td>02.05.2005 IE 2005/05</td><td>Per-Reidar Larnholm in Moss (NO) © Authorized representative: Ir. BJ 't Jong et al. At 2502 EN The Hague.</td>

Inlet and distribution device.

Separating device for separating a liquid / gas mixture into a heavy fraction containing mainly liquid and a light fraction containing mainly gas, comprising:

- a separating vessel, which comprises at least one inlet opening, at least a first outlet opening for discharging the heavy fraction and at least a second outlet opening for discharging the light fraction,

separating means for separating the mixture into the heavy and light fraction;

- a vane-shaped inlet device connected to the inlet opening for admitting the gas / liquid mixture into the vessel and for distributing the admissible gas / liquid mixture in the vessel, the inlet device comprising:

- an extended carrier construction;

- a plurality of curved guide vanes arranged one behind the other, which are attached to the carrier construction, the guide vanes being arranged such that they intercept and laterally deflect the permitted gas / liquid mixture;

agglomeration means arranged close to the guide vanes for collecting the liquid in the gas / liquid mixture.

NL C 1024149

The content of this patent differs from the original filed description with claim (s) and possible drawing (s). The documents originally filed can be viewed at the Netherlands Patent Office. The Netherlands Patent Office is the Office for Industrial Property, an agency of the Ministry of Economic Affairs

INTAKE AND DISTRIBUTION SYSTEM

The present invention relates to an inlet and distribution device for the pre-treatment of a gas / liquid mixture to be separated in a separation device. The present invention also relates to the separation device itself and to a method for treating a gas / liquid mixture in a separation vessel.

Separators are known in the oil and gas industry for separating the incoming mixture of liquid (oil and / or water) and gas into a stream of mainly gas and a stream of mainly liquid. Various separating devices are known for separating solid gas / liquid mixtures.

In one type of separation device, a separation vessel is provided, in which a number of cyclones are arranged. The separation vessel usually includes an inlet opening for admitting the liquid / gas mixture, a first outlet opening for the discharge of a separated heavy fraction of the mixture, ie a fraction of the mixture consisting mainly of the relatively heavy liquid, and an outlet opening for the discharge of the light fraction of the mixture, ie the fraction of the liquid mainly containing gas. Separation is accomplished by driving the liquid / gas mixture through the cyclones.

WO 00/25931 discloses a separating vessel, in which a number of so-called axial recycling cyclones are arranged in a compartment at the top of the vessel. The liquid / gas mixture enters a compartment at the bottom of the vessel and is then driven through the cyclones. The mixture entering an axial cyclone is rotated, swinging the heavy fraction against the outer wall of the cyclone while the light fraction remains in the center of the cyclone. The heavy fraction is then discharged through the openings in the outer wall to a so-called down pipe, leading the heavy fraction to the compartment at the bottom of the vessel. The separated light fraction is discharged through an outlet in the upper compartment of the vessel.

The liquid / gas mixture will be subjected to a pretreatment immediately after entering the separation vessel to improve the overall separation efficiency of the separation device. Pretreatment is also advisable to quickly achieve good separation of the mixture from the vessel, otherwise the mixture will hit the wall of the vessel, which is opposite the inlet opening, with significant force, resulting in that liquid particles are carried to the top compartment.

For the pre-treatment of the liquid / gas mixture, inlet devices are known in which the mixture entering the vessel is distributed in such a way that a more uniform distribution over the effective cross-section of the vessel is guaranteed. In a device known in the art as the Evenflow vane-type inlet device, a row of vanes is arranged within the vessel in line with the centerline of the inlet opening, the vanes being arranged so that they collect incoming mixture and deflect sideways.

A drawback of the known inlet device is that in practice, in particular in the case that the

10241493 gas distribution in the pipes of the inlet opening is poor or in the case where the arrangement of the pipes is not optimal, the distribution of the mixture coming out of the device is not evenly distributed. This will have a negative effect on the separation properties of the separator.

Another drawback is that the incoming flow will be subject to additional frictional forces, which means that the risk of liquid friction increases.

Liquid friction should be avoided as it reduces the size of the liquid droplets to be separated in the separator. In general, the smaller the droplets are, the more difficult it will be to get a good separation inside the vessel.

Another drawback is that with the known separating devices the risk of re-entraining from the liquid surface is relatively high. If the vane-shaped inlet device does not show good inlet distribution, the outlet distribution of the gas from the inlet device may be poor, leading to high local velocities. Therefore, high velocities can be observed on the liquid surface (the liquid surface is located under the vane-shaped inlet device in the liquid reservoir). When high gas velocities are seen on the liquid surface, the gas can be entrained or absorb liquid from the liquid surface and transport the liquid up into the vessel. This results in increasing the fluid load on the downstream devices and therefore in reducing the efficiency of the separator.

US 4 297 116 describes a separating vessel provided with an inlet on which a diffuser is mounted. Diffuser consists of a conical pipe with openings.

102414Ö4

The mixture entering via the conduit is led into the separating vessel via the openings in the conical pipe. A coalescer is mounted at some distance above the diffuser. Because the coalescer is arranged above the diffuser, in this known separating vessel there is also a great chance that, due to the high gas velocities, liquid can be entrained or picked up from the liquid surface, which deteriorates the separation efficiency.

It is an object of the present invention to improve the separation properties of the known separation devices in general.

Another object of the present invention is to provide an improved gas distribution on the downstream side of the inlet device.

Yet another object of the present invention is to provide a separating device in general or an inlet device in particular with a reduced risk of the liquid being entrained from the liquid surface again.

According to a first aspect of the present invention, this object is achieved in a separator for separating a liquid / gas mixture into a heavy fraction containing mainly liquid, and a light fraction containing mainly gas, comprising:

- a separating vessel comprising at least one inlet opening, at least a first outlet opening for discharging the heavy fraction and at least a second outlet opening for discharging the light fraction,

- an inlet device connected to the inlet opening for the entry of the gas / liquid mixture into the vessel and for the distribution of the gas / liquid mixture entered into the vessel,

1024149*

separating means for further separating the mixture into the heavy and the light fraction;

agglomerating means for collecting the liquid in the gas / liquid mixture, the agglomerating means being arranged downstream from the inlet opening in and / or below the inlet device.

The agglomeration means ensure the collection of the liquid, ie the accumulation or accumulation of the liquid in relatively large liquid droplets. The liquid droplets will fall back into the bottom compartment under gravity and fall into the liquid already present there, thereby increasing the overall separation efficiency of the vessel.

According to a preferred embodiment, the inlet device is a vane-shaped inlet device comprising an elongated support structure and a plurality of curved guide vanes arranged one behind the other and secured to the support structure, with guide vanes arranged to intercept the let-in gas / liquid mixture and deflecting sideways, the agglomeration means being arranged between the guide vanes, whereby a sufficient reduction of the pressure of the incoming mixture is ensured and the mixture can be distributed by itself.

According to another preferred embodiment, the agglomeration means are arranged downstream from the guide vanes. In particular for large vessels (with large diameters), the agglomeration means (such as the wire net) are likely to be fitted to the front of the outlet vanes of the guide vanes. The agglomeration means can also be placed between the guide vanes as well as downstream from the guide vanes.

The agglomeration means within the vane inlet device or at the outlet opening of the vane inlet device will subject the gas to a pressure drop. A pressure drop will help the gas to self-distribute, either before or just after exiting the vane inlet device.

The local high velocities seen during the non-optimal inlet distribution are tempered due to the pressure drop. Depending on the applied pressure reduction, which depends on the type of agglomeration agents used, an improved gas distribution from the inlet device can be seen. The distribution of the gas supplied to the inlet device may be poor, but the distribution downstream of the agglomeration means will be almost uniform. With a more uniform distribution from the inlet device, a better distribution across the downstream device, which may be, for example, a further wire net, blade array and / or a number of cyclones, will be ensured.

Also, because less local high velocities are seen, the gas will mainly flow upward rather than downward toward the surface of the liquid and therefore the risk of liquid entrainment is reduced. Another positive effect is that the agglomeration agents will act as a coalescer, ie as the gas and liquid droplets flow through the agglomeration means (preferably a wire net), the liquid droplets will increase in size, resulting in improved overall separation capability due to increased gravity separation and due to increased downstream efficiency design.

10241497

According to another preferred embodiment, the agglomeration means project a predefined distance from the rear of the guide vanes. Tests have shown that the predefined distance between 0-500 mm produces particularly good results.

According to another preferred embodiment, the separation vessel comprises a bottom section for collecting the heavy fraction and the agglomeration means are arranged between the inlet device and the bottom section. In this embodiment, the chance of entraining from the liquid surface is also reduced. The liquid trapped in the agglomeration means, preferably a wire net, will seep through the wire net and fall into the liquid in the bottom portion of the vessel. In this embodiment, various types of inlet devices can be used, for example the aforementioned vane-shaped inlet device or an inlet device based on the cyclone technique. Cyclone-type inlet devices are known per se in this technological art.

According to a further preferred embodiment, the agglomeration means are arranged over largely the entire effective cross-section of the separating vessel. According to another preferred embodiment, the agglomeration means are arranged over only a part of the effective cross-section of the separation vessel. This depends, among other things, on the degree of skew of the distribution seen in the inlet device.

Preferably, the agglomeration means are arranged only along those portions of the vessel wall, which are located to the side of the inlet device. In case, for example, a vane-shaped inlet device is used, the agglomeration means (preferably a wire net) will only have to be arranged along the wall of

10241498 the vessel perpendicular to the front of the outlet of the device, while the agglomeration means along the other parts of the vessel wall can be dispensed with. In the case where a cyclone-type inlet device is used, it is usually necessary to arrange the agglomeration means along the entire circumference of the vessel.

As mentioned above, the agglomeration means are preferably formed in a network, preferably in the form of a number of layers of metal mesh or metal wires. The liquid droplets in the mixture passed through the mesh pad collide with the threads and grow into a liquid layer therein, which increases the separation efficiency of the separator. However, other types of agglomerating agents may also be used, such as one or more layers of structured or randomly packed or of vanes or packages of vanes, as described, for example, in Perry's Chemical Engineer's Handbook, 7^theedition, page 14-40, figures 14-45a and 14-45b. Any porous medium with a dead fraction of 50 - 99.9% is in fact suitable.

Preferably, the vane inlet device should deflect the incoming fluid in the horizontal direction. If diverted vertically upwards, poor gas distribution can be seen on downstream device in vertical vessels. In horizontal vessels, the entrainment of liquid from the liquid surface can occur because the gas leaving the inlet device hits the top of the vessel and is diverted down to the liquid surface. If the gas / liquid is deflected vertically downwards in both vertical and horizontal vessels, there may be high velocities on the liquid surface with the associated high risk of liquid entrainment from the surface.

According to another aspect of the present invention, an inlet device is provided, preferably the inlet device as specified above, for the pretreatment of a gas / liquid mixture to be separated in a separation vessel, the separation vessel having at least one inlet opening for admitting the gas / liquid mixture at a bottom part of the vessel, means for separating the gas / liquid mixture into a heavy fraction containing mainly liquid and a light fraction containing mainly gas, comprising a first outlet opening for discharging the heavy fraction and a second outlet opening for discharging the light fraction , the inlet device comprising:

- an elongated carrier construction to be connected to the inlet opening, wherein the elongated carrier construction is provided with at least a partially open side;

a plurality of curved guide vanes arranged one behind the other and at least partially arranged inside the support structure, the guide vanes being arranged to intercept and deflect the permitted gas / liquid mixture towards the bottom portion of the separation vessel;

agglomeration means arranged close to the guide vanes for collecting the liquid in the gas / liquid mixture.

According to another preferred embodiment, the agglomeration means are attached to a separate support arranged in the vessel. In particular in renewal situations, the use of a separate carrier allows a relatively simple and cost effective implementation.

According to another aspect of the present invention, there is provided a method of treating a gas / liquid mixture in the above-defined separation vessel, the method comprising the following steps:

- passing the gas / liquid mixture through a wire net to the bottom compartment of the vessel;

- guiding part of the mixture through one or more cyclone distributors in the upper part of the vessel and passing the separated liquid back to the lower compartment and passing the separated gas part to the second outlet opening;

- discharging the mixture from the bottom compartment from the first outlet opening; and

- discharging the mixture from the top compartment from the second outlet opening.

Further advantages, features and details of the present invention will follow from the description of the preferred embodiments thereof. Reference is made in the description to the figures, in which:

Figure 1 shows a partly cut-away perspective view of a separating device for separating a mixture of gas and liquid;

Figure 2 shows a perspective view of a first preferred embodiment of a vane-shaped inlet device;

Figure 3 shows a partly cut-away perspective view of a second embodiment of a vane-shaped inlet device;

Figure 4 shows a cross section of the vane-shaped inlet device, as shown in Figure 2;

102414911

Figure 5 shows a cross-section of another preferred embodiment of a vane-shaped inlet device;

Figure 6 shows a partly cut-away perspective view of a separating device, which is provided with another embodiment of an inlet device according to the present invention, in which the wire net. is located at a position between the inlet opening and the liquid surface;

Figure 7 shows a schematic cross section of a preferred embodiment of a vessel with vertically arranged wire net pads;

Figure 8 shows a schematic cross section of a preferred embodiment of a vessel with inclined wire net pads;

Figure 9 shows a schematic cross-section of a preferred embodiment of a vessel fitted with a cyclone-type inlet device; and

Figure 10 shows a cross section of the embodiment of Figure 9.

Figure 1 shows an upright separation vessel 1 for separating a stream of a gas / liquid mixture under pressure, such as a natural gas mixed with (salt sea) water, in a mainly gas-containing fraction, also called a light fraction, and a mainly fraction consisting of liquid (water and / or oil), also known as heavy fraction. Vessel 1 includes a connecting pipe end 2 for introducing the gas / liquid mixture, a connecting pipe end for a liquid discharge pipeline 4 for discharging the heavy fraction, and a connecting pipe end 5 for discharging the light fraction.

The gas / liquid flow entering vessel 1 (Pi)

102414912 is introduced by means of a pre-treatment unit 3 to a bottom compartment A of vessel 1. In the embodiment shown, the pre-treatment unit is formed by a number of curved blades or vanes that evenly absorb the moment of the incoming gas / liquid mixture. The vanes successively direct the gas / liquid flow sideways (P_a) in the bottom compartment of the separation vessel. As a result of this controlled entry of the gas / liquid mixture, a first portion of the liquid (F) will already be separated and will accumulate at the bottom of the vessel 1 (P₃) .

The separated portion of the mixture which, although it contains less liquid than the mixture supplied from the outside, still contains a significant amount of liquid, is then moved upwards (P₄). The liquid still present in relatively large droplets is further separated by a number of cyclones 6. The cyclones are arranged in a plurality of blocks in the upper compartment B of the vessel 1. Downstream thereof, the connecting pipe end 5 is provided for draining the light fraction (mainly gas), which has dried considerably. The cyclones are connected to one or more down pipes 7 communicating with liquid F at the bottom of the vessel for draining liquid from each of the cyclones.

Preferably, the cyclones are axially recycling cyclones as described in the aforementioned document WO 00/25931. A general description of the separation as performed by axial recycling cyclones is incorporated herein by reference.

Figure 2 shows a vane-shaped inlet device 10, which comprises a bottom plate 11 and a top plate 12. Between the

102414913 plates, a number of partially straight, partially curved guide vanes 9 are arranged. The guide vanes are designed to guide the incoming flow sideways.

A liquid / gas stream flowing through the inlet device (P₇) is intercepted by the leading edge 21 of a guide vane 9 and diverted laterally (P₈). A wire net 13 is arranged downstream of the rear side 20 of the guide vanes 9. The wire net 13 can be attached to the inlet device itself, for example to the carrier plates 11 and 12, or it can be connected to a separate frame, which is directly attached to the separation vessel 1 itself. The wire net pad is a layer of tightly packed wires, with the layer arranged vertically downstream of the guide vanes.

Figure 3 shows another embodiment of the present invention. In this embodiment, a vane-shaped inlet device of a different design is used, also known as the Evenflow inlet device. The

Evenflow inlet device differs in a number of aspects from the device shown in Figure 2, the main ones being that the guide vanes are bent over their entire length, the guide vanes are held between the edges of the top and bottom plates

11, 12 and that the spacing between successive guide vanes increases toward the mixture flow (P₈). However, the basic principle of intercepting the mixture flow and deflecting the flow towards the vessel wall is the same.

In this embodiment, a number of thread pads 14 are arranged between the guide vanes 9 '. The thread pads 14, as shown in Figure 3, are arranged close to the back of the blades. However, they can also be arranged close to the front of the blades or along the entire surface of the blades.

Figure 5 shows another preferred embodiment of a vane-shaped inlet device according to the design of the Evenflow inlet device. In this embodiment, the thread pad 15 is arranged not only between the guide vanes 9 ', but also downstream of the guide vanes. In fact, the thread pad 15 protrudes a distance (a) of 0-500 millimeters from the rear of the respective guide vanes.

Figure 6 shows another preferred embodiment of the separating device according to the invention. The figure shows a separating vessel 1 which is provided with a blade-shaped inlet device 3 as discussed above. Instead of a vane-shaped inlet device, other inlet devices are feasible, such as a cyclone-type inlet device or a similar device. Shown is a wire net 30 placed at a position between the inlet opening 2 of the separator 1 and the surface of the liquid f which is accumulated on the bottom of the vessel. A special embodiment is shown, in which the wire net is divided into two wire net parts 30,

30 ', which are arranged next to the wall 31 of the vessel. A space is left open between the wire net parts 30, 30 '.

The incoming mixture will be diverted sideways and driven through the two wire net parts 30, 30 '. Both wire net parts will retain a small portion of the liquid contained in the gas and this liquid will fall down into the liquid F already present there. The remainder of the mixture will be driven upwards mainly through the space between the two wire net parts 30, 30 '. The space is provided to the upward

102414015 improve flow of the mixture (which mainly contains gas).

The space has an elongated shape, but may be shaped differently depending on the specific kind of separation used, the characteristics of the incoming mixture, and so on. In certain cases where there are large oblique distributions and the inlet devices are heavily loaded (ie high gas loads), the wire mesh pad must be enlarged and therefore the space is chosen to be smaller.

The wire net may alternatively be formed to cover the entire workable cross-section of the vessel 1. In many circumstances, this embodiment is preferred because it will provide an even distribution of the mixture.

Figure 7 shows a further preferred embodiment of the invention, in which the inlet device, ie a blade-shaped inlet device, is schematically shown and the wire net is arranged vertically in the vessel 1. The wire net in this embodiment is attached to a support structure 31, which comprises a fixed plate or, preferably, a further wire net, a perforated plate or a structured / random gasket. The mixture flowing sideways from the inlet device 3 will be more evenly distributed in the vessel by the arrangement of the wire net 32 ​​shown.

Figure 8 shows the embodiment of Figure 3, wherein the wire net 33 is at an angle α (10 ° &lt;α &lt;170 °) relative to the vessel wall and extends up and down. The wire net 33 is directly attached to the wall of the vessel 38.

Figures 9 and 10 show cross sections of a further preferred embodiment of the present invention. In this embodiment, a cyclone-type inlet device 34 is used. The inlet device 34 includes a horizontal pipe 35 connected to two cyclones 36, 36 '. Each cyclone includes a tangential inlet opening which forces the mixture exiting from the pipe 35 to rotate (P₁₀). Under the influence of the rotating movement of the mixture inside the cyclones 36, 36 ', a heavy fraction of the mixture is discharged downwards (P_n), while draining a light fraction of the mixture upward (P₁₂). For a further description of a cyclone-type inlet device, reference is made to International Publication No. WO 00/74815 A2. present applicant, which is incorporated herein by reference.

Figures 9 and 10 show that the wire net pad in this embodiment is arranged along the entire circumference of the wall of the vessel 38. The width W of the wire net 37 will differ from case to case. Instead of the wire net being just a strip along the barrel wall, as shown in Figure 10, the wire net can cover the entire surface (except for the area occupied by the inlet cyclones 36, 36 'itself) or only several strips on parts of the wall of the vessel 38.

As mentioned above, the dimensions and shape of the space between the two wire net pads will in practice depend on the specific separation requirements and / or the quality of the incoming mixture. Other configurations or designs of wire mesh pads within the separation vessel can also be advantageous.

The present invention is not limited to the above-described embodiments; the requested rights are defined by the following claims, within the

102414917 to which many modifications can be envisaged.

Although an upright separating vessel is shown in the above description of the preferred embodiments of the present invention, it will be understood that the invention also applies to horizontal or oblique disposed separating vessels.

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