GB2598106A

GB2598106A - Cooling and gas-liquid separation system

Info

Publication number: GB2598106A
Application number: GB2012821.1A
Authority: GB
Inventors: Matias Dupuy Pablo; Olav Fredheim Arne; Johannessen Eivind; Arild Maråk Knut; Rekaa Nilssen Oddbjørn
Original assignee: Equinor Energy AS
Current assignee: Equinor Energy AS
Priority date: 2020-08-17
Filing date: 2020-08-17
Publication date: 2022-02-23
Also published as: GB202012821D0

Abstract

An apparatus 200 for combined cooling and separation of a fluid stream, the apparatus comprises an inertial separator 201 configured to receive the fluid stream 214 and to separate the fluid stream into a gas phase stream 220 and a liquid phase stream 222. The inertial separator is also configured to exchange heat between the gas-liquid stream and a cooling medium to cool the gas-liquid stream as the gas-liquid stream flows through the inertial separator. The inertial separator may be a vane pack or cyclone and can be formed as a portion of a cooling passage in a cooler comprising a plurality of cooling passages. Also disclosed is an apparatus for combined cooling and gas-liquid separation of a fluid stream, comprising a cooling portion 102 comprising a plurality of cooling pipes configured to receive the gas-liquid stream and to exchange heat between the fluid stream and a cooling medium to cool the fluid stream; and a separation portion (112, 118, Fig 4) comprising a plurality of inertial separators configured to separate the cooled fluid stream into a gas phase stream and a liquid phase stream; and wherein each of the plurality of cooling pipes includes an outlet which is connected directly to a channel of one of the inertial separators. The apparatus can perform simultaneous cooling and gas-liquid separation of a fluid stream, removing the need for a separate cooler and gas-liquid separator.

Description

COOLING AND GAS-LIQUID SEPARATION SYSTEM

The present invention relates to cooling and separation of a fluid stream, and particularly a multiphase natural hydrocarbon gas stream.

Gas-liquid separation is a common process in which a fluid stream containing a mixture of gas and liquid is separated into a gas phase stream and a liquid phase stream.

Gas-liquid separation is used in a variety of industries such as oil and gas processing, where natural hydrocarbon well streams often contain a mixture of gas hydrocarbons and liquid hydrocarbons. The gas phase hydrocarbons and the liquid phase hydrocarbons have different processing and transportation requirements, so gas-liquid separation is often performed as part of the standard processing of the well stream. In one example of typical hydrocarbon fluid stream processing, a well stream passes through a compressor scrubber or separator where it is separated into three components: oil, water and gas. Each component exits the scrubber/separator through a different pipe. From there, the components are typically sent to oil stabilization, water re-injection, and gas dehydration/compression respectively, before being transported elsewhere for further processing.

Liquid that remains in the gas phase stream can cause damage to other components during further processing, such as compressors, or clogging of pipes due to hydrate formation, and so it is important to remove as much liquid from the gas phase stream as possible.

In some systems the fluid stream is cooled prior to gas-liquid separation, e.g. using a heat exchanger. In a typical shell-and-tube type heat exchanger, tens or hundreds of cooling pipes contain the fluid stream while a cooling medium such as water is circulated around the pipes so as to cool the fluid inside the cooling pipes. Cooling the fluid stream usually causes liquids, such as water or heavier hydrocarbons, to condense out of the fluid stream. The fluid stream containing the condensed liquids is subsequently transported to the gas-liquid separation equipment, e.g. a separator or a scrubber, in order to separate the fluid stream into a gas phase stream and one or more liquid phase stream.

In some instances the liquid that has condensed out of the gas stream during the cooling process can become entrained in the gas stream and can remain in the gas stream in droplet form. Some types of conventional gas-liquid separator -2 -that are designed to remove bulk liquids, e.g. gravitational separators, are generally unable to remove all the entrained droplets, particularly if the droplets are too small. Some of this entrained liquid can therefore be passed through a separator which reduces its separation efficiency.

A need exists for an improved system for gas-liquid separation of a fluid after cooling of the fluid.

Viewed from a first aspect, the present invention provides an apparatus for combined cooling and gas-liquid separation of a fluid stream, comprising: a cooler comprising a plurality of cooling passages, the cooling passages being configured to receive the fluid stream and to exchange heat between the fluid stream and a cooling medium outside of the cooling passages; wherein at least a portion of each of the cooling passages is arranged to form an inertial separator to thereby separate the fluid stream into a gas phase stream and a liquid phase stream.

The apparatus performs both a cooling process and a gas-liquid separation process, avoiding the need for a separate cooler unit and gas-liquid separator unit as required in prior systems. By integrating the cooling and gas-liquid separation into a single unit, deck space and weight can be saved as it is no longer necessary to provide a separate heat exchanger and separator. Furthermore, the entire unit can be retrieved and replaced in one piece, which is particularly advantageous in the context of unmanned installations where complete unit replacement is preferred.

Furthermore, the inventors have found that inside the cooling pipes of conventional heat exchangers the condensed liquid can take the form of a liquid film, e.g. on the internal surface of the cooling pipes. In a conventional heat exchanger, when the fluid in the cooling pipes is recombined, the turbulent mixing of the fluid streams causes the liquid films inside the cooling pipes to separate into droplets which become entrained in the gas. It is more difficult to separate the entrained droplets, particularly when the liquid content of the fluid stream is low. Therefore, by configuring each individual cooling passage to form an inertial separator, the gas-liquid separation occurs before the individual cooling passages recombine into a single passage. Therefore the condensed liquid can be separated from the gas before it has become entrained in the gas, making it easier to separate the liquid.

The cooling passages may each define a channel which is arranged to permit a portion of the fluid stream to flow therethrough. Each cooling passage may -3 -comprise a distinct and continuous channel, e.g. separate from the other cooling passages.

The cooler may be arranged to receive a cooling medium and to bring the cooling medium into thermal contact with the fluid stream flowing within the cooling passages. The cooling medium may be fluidly isolated from and in thermal contact with the fluid stream. The cooling medium may comprise any known fluid that is suitable for receiving heat from the fluid stream, such as water. The cooling medium may flow within channels such as pipes or tubes, or the cooling medium may flow freely within a space through which the cooling passages extend, e.g. in a shell of a shell-and-tube heat exchanger. The cooler may be configured to exchange heat between the fluid stream and the ambient environment, e.g. the cooling medium may be ambient air or water. For instance the apparatus may be configured for use subsea and the cooling medium may be seawater.

Each inertial separator may be configured to separate the incoming fluid stream into a gas phase stream and a liquid phase stream. Inertial gas-liquid separators effect gas-liquid separation by utilising inertial principles such as the action of centrifugal forces on the fluid (e.g. cyclones) or causing a sharp directional changes in the fluid flow (e.g. a vane pack), thus causing the liquid droplets to be removed from the gas. Inertial separators are more efficient at removing small droplets of liquid than, for example, gravitational separators.

At least one, and optionally each of the internal separators, may comprise a cyclone separator. The cyclone separator may be an axial porous cyclone separator. Inside a cyclone separator, e.g. an axial porous cyclone, the fluid stream is set to spin and the liquid (e.g. liquid condensed out of the fluid stream by the cooling portion) is forced to the outer wall of the cyclone. The cyclone may include slits in the outer wall which remove the liquid, while the gas continues through the cyclone channel. Thereby the gas and liquid are separated. In addition to or instead of slits, the cyclone separator can have porous walls for liquid separation. Porous cyclone separators may be particularly beneficial when used in situations in which the fluid stream does not contain much or any solid particulate matter which could clog the porous walls.

At least one, and optionally each of the internal separators, may comprise a vane pack separator. In a vane pack separator, the fluid stream is passed through paths with multiple sharp turns forcing the fluid stream to change direction. The walls or vanes of the vane pack may have a "zig-zag" configuration so as to provide -4 -the sharp turns in the path. The liquid tends to become captured in small pockets or channels which are found along the vanes, the liquid then being drained vertically due to gravity. The walls or vanes may include hooks (e.g. protrusions extending into the channel from the walls) to aid liquid capture. The gas tends to follow the path straight through the vanes. Thereby the gas and liquid are separated. Examples include single-pocket vanes, horizontal-flow double-pocket vanes and vertical-flow double-pocket vanes.

At least a portion of each of the cooling passages may be arranged to form an inertial separator, e.g. an inertial separator as described above. The portion of the cooling passage may have a physical shape that causes the fluid stream to be separated into a gas phase and a liquid phase by inertial principles when it passes through the shaped portion. For example the portion of the cooling passage may be shaped to form a channel of a vane pack, e.g. the cooling passage may have one or more walls which are shaped in a "zig-zag" configuration to form a vane of a vane pack separator. Each channel may comprise a plurality hooks arranged on the walls of the channel. The hooks may be protrusions that extend into the channel from the wall. Thus, when the fluid stream flows through the channel, the fluid stream is forced to turn sharply due to the "zig-zag" shape, causing the liquid to collect on the walls e.g. by the hooks, while the gas to continue through the channel.

In some examples only a portion of each cooling passage forms an inertial separator. There may be a cooling portion of the cooling passage that is configured to perform cooling of the fluid stream, and another separating portion (e.g. a different portion) of the cooling passage that is configured to perform gas-liquid separation. The cooling portion may not be configured to perform gas-liquid separation, and the inertial separation portion may not be configured to perform cooling. The separating portion is preferably downstream of the cooling portion.

In other examples the entire cooling passage may form the inertial separator, e.g. the whole extent of each cooling passage may be configured to cool the fluid stream and perform gas-liquid separation simultaneously. These examples will be described in more detail later.

The plurality of cooling passages may be housed within a common housing. The housing may comprise an inlet for receiving the fluid stream. The housing may include an inlet plenum configured to receive the input fluid stream and to distribute the fluid stream into the cooling passages. The housing may comprise an outlet -5 -plenum configured to receive the separated gas phase stream from each cooling passage. The housing may comprise a first outlet configured to output the gas phase stream and a second outlet configured to output the liquid phase stream. Each cooling passage may comprise an inlet for receiving a fluid stream, a first outlet for outputting the gas phase stream and a second outlet for outputting the liquid phase stream.

As discussed above, in some examples the cooling passages may be configured to perform cooling and then subsequently perform gas-liquid separation of the fluid stream. For instance each cooling passage may comprise a first passage portion which is a heat exchanging or cooling portion (e.g. a cooling pipe), and a second passage portion which is a separation portion (e.g. an inertial separator) located downstream of the first passage portion. Thus each cooling passage may comprise a cooling portion that exchanges heat between the fluid stream and a cooling medium to cool the fluid stream, the cooling portion having an outlet that connects directly to a separation portion of the cooling passage that separates the cooled fluid stream into a gas phase stream and a liquid phase stream.

The individual cooling portions of each of the plurality of cooling passages may together define a cooling portion of the apparatus. Similarly, the individual separation portions of each of the plurality of cooling passages may together define a separation portion of the apparatus.

Thus, viewed from a second aspect, the present invention provides an apparatus for combined cooling and gas-liquid separation of a fluid stream, comprising: a cooling portion comprising a plurality of cooling pipes configured to receive the fluid stream and to exchange heat between the fluid stream and a cooling medium to cool the fluid stream; and a separation portion comprising a plurality of inertial separators configured to separate the cooled fluid stream into a gas phase stream and a liquid phase stream; and wherein each of the plurality of cooling pipes includes an outlet which is connected directly to a channel of one of the inertial separators.

The cooling portion may be a heat exchanger, e.g. a shell and tube heat exchanger. The cooling pipes may be cooling tubes, e.g. tubes of a shell and tube heat exchanger. Each cooling pipe may comprise an inlet configured to receive the fluid stream and an outlet configured to output the cooled fluid stream. The cooling -6 -medium may be located outside of the cooling pipes, for example in the shell of a shell and tube heat exchanger.

The outlet of each cooling pipe may be connected directly to a channel of an inertial separator. The outlet of each cooling pipe may be in direct physical contact with a channel of an inertial separator to form a single continuous channel between the inlet of the cooling pipe and an outlet of the inertial separator. The cooled fluid stream, which may contain some condensed liquid e.g. in the form of a film, will therefore flow directly/immediately from each cooling pipe into a respective inertial separator. Thus, unlike prior systems, the fluid streams in each of the cooling pipes are not recombined into a single stream prior to gas-liquid separation. Therefore the entrainment of liquid droplets in the gas is avoided, and the efficiency of separation of the liquid from the fluid stream is enhanced.

Each of the inertial separators may comprise a cyclone separator. There may be a one-to-one correspondence between cooling pipes and cyclones, i.e. each cooling pipe may be connected to a different cyclone. Alternatively each of the inertial separators may comprise a channel of a vane pack, and the plurality of inertial separators may together comprise a vane pack. Each cooling pipe may be connected directly to a channel of a vane pack, e.g. to a channel between adjacent vanes. Multiple cooling pipes may be directly connected to the same vane pack channel. In further embodiments, any other type of inertial gas-liquid separator may be used.

The plurality of inertial separators may comprise more than one type of inertial separator. For instance the outlet of each cooling pipe may be directly connected to a cyclone and the outlet of each cyclone may be directly connected to a channel of a vane pack so that separation is performed first by the cyclone and subsequently by the vane pack. Alternatively the outlet of each cooling pipe may be connected directly to a channel of a vane pack and the outlet of each channel of the vane pack may be directly connected to one of a plurality of cyclones so that separation is performed first by the vane pack and subsequently by the cyclones.

Other combinations of types of inertial separator are also possible. This improves the separation efficiency so that more liquid is removed from the gas stream.

The apparatus may be configured such that, after separation by the inertial separators, the gas phase streams from each inertial separator recombine into a single gas phase stream and/or the liquid phase streams from each inertial separator recombine into a single liquid phase stream. The single gas phase -7 -stream may exit the apparatus via an outlet pipe and the single liquid phase stream may exit the apparatus via a different outlet pipe. The gas phase stream may undergo further separation. For example there may be a mesh pad located downstream of the inertial separator so as to perform further separation of liquid that may remain in the gas phase stream.

The cooling portion and the separation portion may be arranged within a common housing. The housing may include an inlet for receiving the input fluid stream. The housing may include a first outlet for outputting the gas phase stream and a second outlet for outputting the liquid phase stream. The cooling portion and the separation portion may be separated within the housing by a plate, e.g. a tube plate. The cooling pipes may pass through the plate. The inlet of each cooling pipe may be located on a first side (e.g. a cooling side) of the plate and the outlet of each cooling pipe may be located on a second side (e.g. a separation side) of the plate. The plate may be located adjacent to the outlets of the cooling pipes. Thus the plate may divide the housing into the cooling portion and the separation portion.

The cooling portion may be arranged to circulate the cooling medium around the cooling pipes on the first side of the plate. The plate may be arranged so that the gas phase stream output from the inertial separators is contained to the second side of the plate. The plate may separate the cooling medium on the first side from the separated gas on the second side. In other words the plate may form a seal between the cooling portion and the separation portion. The separation portion may be located in a plenum (e.g. an outlet plenum) of the housing.

As mentioned previously, in an alternative example, the cooling passages may be configured to perform simultaneous cooling and separation.

Thus, viewed from a third aspect, the present invention provides an apparatus for combined cooling and separation of a fluid stream, comprising: an inertial separator configured to receive the fluid stream and to separate the fluid stream into a gas phase stream and a liquid phase stream; wherein the inertial separator is also configured to exchange heat between the gas-liquid stream and a cooling medium to cool the gas-liquid stream as the gas-liquid stream flows through the inertial separator.

The inertial separator may include one or more channels which are arranged to permit a portion of the fluid stream to flow therethrough. The inertial separator may be arranged so that the fluid stream is in thermal contact with a cooling medium as it flows through the channel(s). For example the cooling -8 -medium may flow within one or more passages located adjacent to the channel(s), e.g. in the walls of the channel(s).The inertial separator may be a vane pack. The vane pack may include a plurality of internal walls (e.g. vanes) which divide the vane pack into channels. As in conventional vane packs, the internal walls may be shaped (e.g. in a "zig zag" shape) to include sharp turns so as to cause the fluid stream to turn sharply as it flows through the separator. Each channel may comprise a plurality hooks arranged on the walls of the channel, e.g. protrusions that extend into the channel from the wall. Thus, when the fluid stream flows through the channel, the fluid stream is forced to turn sharply due to sharp turns, causing the liquid to collect on the walls e.g. by the hooks, while the gas continues through the channel.

The vane pack may include an inlet at one end of each channel configured to receive the fluid stream, and an outlet at the other end of each channel configured to output the gas phase stream. Each channel of the vane pack may include another outlet to output the liquid phase stream, e.g. at the bottom of the channel so that liquid can drain vertically from the channel walls by the act of gravity. In addition, the vane pack may be configured such that a cooling medium flows within the internal walls or vanes, e.g. between adjacent channels. The internal walls or vanes may include one or more inlets for receiving the cooling medium and one or more outlets for outputting the cooling medium. The internal walls may be arranged to exchange heat between the cooling medium and the fluid stream. The walls or vanes may comprise a thermally conductive material. The inertial separator may thereby cool the fluid stream at the same time as performing gas-liquid separation of the fluid stream.

The inertial separator, e.g. the vane pack, may be arranged to exchange heat between the cooling medium and the fluid stream using the principles of a plate heat exchanger. Typical plate heat exchangers comprise a series of plates (usually metal plates) arranged in parallel which form a series of channels between which fluids flow in an alternating hot and cold arrangement. The large surface area of the plates enables fast thermal exchange between the fluids. Thus the channels of the inertial separator through which the fluid stream and the cooling medium flow may be arranged to form channels of a plate heat exchanger.

The simultaneous cooling may facilitate condensation of the liquid as the fluid stream is separated into gas phase and liquid phase components, thereby increasing the amount of liquid that can be removed from the gas phase stream. In -9 -addition, because the cooling medium is arranged to cool the fluid stream as the fluid stream travels through the channels of the separator, the integrated gas-liquid separator and heat exchanger may be made compact and no separate heat exchanger may be required. This allows for space and weight savings in fluid stream processing.

A method for performing cooling and gas-liquid separation of a fluid stream may comprise using the apparatus of the first aspect. The apparatus may include any features as described above in accordance with the first aspect.

The method may include: receiving a fluid stream at a cooler; inputting a portion of the fluid stream into each of a plurality of cooling passages of the cooler; cooling the fluid stream in the cooling passages; while the fluid stream is in the cooling passages, separating the fluid stream into a gas phase stream and a liquid phase stream using an inertial separator; and outputting the gas phase stream and a liquid phase stream.

A method for performing cooling and gas-liquid separation of a fluid stream may comprise using the apparatus of the second aspect. The apparatus may include any features as described above in accordance with the second aspect.

The method may include: receiving a fluid stream at a cooler; inputting a portion of the fluid stream into each of a plurality of cooling pipes of the cooler; cooling the fluid stream; outputting each portion of the fluid stream from the cooling pipes directly into a respective channel of an inertial separator; separating the fluid stream into a gas phase stream and a liquid phase stream using the inertial separator; and outputting the gas phase stream and a liquid phase stream.

A method for performing cooling and gas-liquid separation of a fluid stream may comprise using the apparatus of the third aspect. The apparatus may include any features as described above in accordance with the third aspect.

The method may include: receiving a fluid stream at an inertial separator; inputting a portion of the fluid stream into each of a plurality of channels of the inertial separator; separating the fluid stream into a gas phase stream and a liquid phase stream using the inertial separator; while the fluid stream flows through the inertial separator, cooling the fluid stream; and outputting the gas phase stream and a liquid phase stream.

Certain preferred embodiments of the present invention will now be described, by way of example only, with reference to the following drawings, in which: -10 -Figure 1 is a schematic diagram of a conventional heat exchanger and separator arrangement; Figure 2 is a diagram of a first integrated heat exchanger and gas-liquid separator; Figure 3 is a diagram of a second integrated heat exchanger and gas-liquid separator; Figure 4 is a diagram of a third integrated heat exchanger and gas-liquid separator; Figure 5 is a schematic diagram of the integrated heat exchanger and gas-liquid separator of Figure 2; Figure 6 is a schematic diagram of the integrated heat exchanger and gas-liquid separator of Figure 3; Figure 7 is a diagram of a vane pack separator with single-pocket vanes; Figure 8 is a diagram of a vane pack separator with horizontal-flow double-pocket vanes; Figure 9 is a diagram of a vane pack separator with vertical-flow double-pocket vanes; Figure 10 is a top view of another vane pack separator with integrated cooling; Figure 11 is a perspective view of the vane pack separator of Figure 10; and Figure 12 is a diagram of a fourth integrated heat exchanger and gas-liquid separator including the vane pack separator of Figures 10 and 11.

Figure 1 shows a conventional system 1 for cooling and subsequent gas-liquid separation of a fluid stream. The system 1 comprises a heat exchanger 2 and a gas-liquid separator 4.

The heat exchanger 2 is configured to receive the fluid stream at an inlet 3 and pass the fluid stream into an inlet plenum 5. The inlet plenum 5 distributes the fluid stream into a plurality of cooling pipes 6 which cool the fluid stream as it flows through the heat exchanger 2. Some liquids condense out of the fluid stream as a result of the cooling. Condensation may occur at the internal walls of the cooling pipes 6. The fluid stream within the cooling pipes 6 then recombines in an outlet plenum 8 and exits the heat exchanger 2 via an outlet 10.The cooled fluid stream is then transported to the gas-liquid separator 4. The gas-liquid separator 4 is configured to receive the cooled fluid stream and to perform gas-liquid separation to separate the fluid stream into a gas phase stream and a liquid phase stream. The liquid phase stream is output from the gas-liquid separator via a liquid outlet 12, and the gas phase stream is output from the gas-liquid separator via a gas outlet 14. When the fluid streams in the cooling pipes 6 recombine to form a single stream, such as at the transition between the cooling pipes 6 and the outlet plenum 8, turbulent flow of the mixing streams can cause entrainment of liquid within the gas. Additionally, within the cooler, the fluid flow rate is slowed, and when the fluid stream re-enters a single pipe (e.g. at outlet 10) after cooling, the flow accelerates again. This also causes liquid entrainment. The gas-liquid separator 4 is a gravitational gas-liquid separator which can comprise mesh pads located inside a separation chamber or other internal components. As the fluid stream flows through the separator, the liquid tends to condense on or be caught by the mesh, whereas the gas continues through the mesh pad and out of a gas outlet of the separator. The liquid that is caught by the mesh pad then drains downwards by the action of gravity and exits the separator through a liquid outlet.

Figures 2, 3 and 4 each show a schematic diagram of an apparatus for cooling and gas-liquid separation of a fluid stream according to respective embodiments of the present invention. Each apparatus operates in a similar manner, and like reference numbers modified by a prime symbol represent like components.

In Figure 2, an apparatus 100 according to a first embodiment comprises a cooling portion 102 and a separation portion 104 which are housed in a common housing 106. The housing 106 comprises an inlet 108 configured to receive the fluid stream and pass the fluid stream to an inlet plenum 103 of the housing 106. The cooling portion 102 comprises a plurality of cooling pipes 110 which are configured to receive the fluid stream from the inlet plenum 103 and to cool the fluid stream. The separation portion 104 comprises a plurality of inertial separators 112, which in this example are cyclone separators 112 configured to perform gas-liquid separation on the fluid stream. Each cooling pipe 110 includes an outlet which is directly connected to one of the cyclones 112. The outlets of the cyclone separators 112 are connected to an outlet plenum 113 of the housing 106. The housing 106 further comprises a liquid outlet 114 for outputting the liquid phase stream, and a gas outlet 116 for outputting the gas phase stream. The apparatus 100 will be described in more detail later with reference to Figure 5.

In operation, a fluid stream is received at the inlet 108 of the housing 106 and collects in the inlet plenum 103. A portion of the fluid stream flows from the -12 -inlet plenum 103 through each of the cooling pipes 110 and is cooled. The cooled fluid stream then flows directly from each cooling pipe 110 into a respective cyclone separator 112, where it undergoes gas-liquid separation. A liquid phase stream is output from each of the cyclones 112 and recombines to form a single liquid phase stream, which is output from the housing 106 via liquid outlet 114. A gas phase stream is output from each of the cyclones 112 and recombines in the outlet plenum 113 to form a single gas phase stream, which is output from the housing 106 via gas outlet 116. The apparatus 100 thereby performs both cooling and gas-liquid separation in an integrated unit.

Because each of the cyclones 112 is positioned directly at the outlet of one of the cooling pipes 110, the gas-liquid separation is performed before the liquid becomes atomized and entrained in the gas stream. Therefore separation efficiency can be enhanced. Moreover, in conventional cyclones (e.g. demisting cyclones) the length of the cyclones is preferably long enough to enable a liquid film to form inside the cyclone. In the present embodiment a liquid film is already formed inside the cooling pipe and is passed directly into the cyclone separators, and hence the length of the cyclones can be shorter than conventional cyclones. Additionally, because the cooling and gas-liquid separation processes are integrated into a single unit, deck space and weight savings are provided.

Furthermore, the entire unit can be retrieved and changed in one piece, which is particularly advantageous in the context of unmanned installations.

An apparatus 100' according to a second embodiment is shown in Figure 3 and is similar to apparatus 100 of Figure 2, except that a vane pack 118' is used in place of the cyclone separators 112. The cooling portion 102' of apparatus 100' is identical to the cooling portion 102 of apparatus 100 and will not be described in detail. The apparatus 100' is configured so that the cooled fluid stream exits each cooling pipe 110' and flows directly into a channel of the vane pack 118'. Multiple cooling pipes 110' may be connected to a single channel (i.e. the same channel) of the vane pack 118'. Gas-liquid separation is thereby performed using the vane pack 118' as an inertial separator. This configuration will be described in more detail later with reference to Figure 6 and 7.

An apparatus 100" according to a third embodiment is shown in Figure 4 and is similar to apparatus 100 and 100' of Figures 2 and 3 respectively, except that a combination of a vane pack 118" and cyclone separators 112" is used as the separation portion 104". The apparatus 100" is configured so that the cooled fluid -13 -stream exits the cooling pipes 110", flows directly into the vane pack 118", and is then output from the vane pack 118" directly into cyclone separators 112". Two-stage separation is thereby performed, increasing the separation efficiency. Although not shown in the Figures, the order of the separators 118" and 112" can be altered, e.g. the cyclone separators 112" may be upstream of the vane pack 118".

Figure 5 shows the apparatus 100 of Figure 2 in more detail. The apparatus 100 comprises the cooling portion 102 and the separation portion 104 housed within the housing 106. The housing 106 includes the fluid stream inlet (not shown here), the inlet plenum (not shown), a purge chamber 115, the outlet plenum 113, the liquid outlet 114 and the gas outlet 116. The cooling portion 102 comprises the plurality of cooling pipes 110. The apparatus 100 is configured to circulate a cooling medium 120 around the cooling pipes. An outlet 122 of each cooling pipe 110 is connected directly to a respective cyclone separator 112 to form a continuous channel from an inlet of each cooling pipe 110 to an outlet of the respective cyclone separator 112.

Each cyclone separator 112 comprises an outlet 124 from which the gas phase exits the cyclone separator 112 into the outlet plenum 113, and another outlet 126 from which the liquid exits the cyclone separator 112 into the purge chamber 115. The liquid outlet 126 may comprise slits in the wall of the cyclone separator 112. Some gas, known as purge gas, may also exit the cyclone separator 112 via the liquid outlet 126. Enabling a small amount of gas to be purged out of the cyclones together with the liquid has been shown to increase the liquid removal efficiency of the cyclone separator.

The apparatus 100 comprises a first tube plate 128 through which the cooling pipes 110 extend. The first tube plate 128 is located adjacent to the outlets 122 of the cooling pipes 110. The first tube plate 128 divides the housing 106 into the cooling portion 102 and the separation portion 104. The first tube plate 128 is arranged so that the gas phase stream and purge gas output from the cyclones 112 is contained to the separation side of the first tube plate 128, and the cooling medium 120 circulating around the cooling pipes 110 is contained to the cooling side of the first tube plate 128. The first tube plate 128 thereby forms a seal between the cooling portion 102 and the separation portion 104.

A second tube plate 130 is arranged in the separation portion 104 and is offset axially (relative to the axis of the cooling pipes 110) from the first tube plate -14 - 128. The second tube plate 130 divides the separation portion 104 into the purge chamber 115 and the outlet plenum 113, which acts as a gas collection chamber. The second tube plate 130 does not extend across the entire cross-section of the housing 106. A passage is thereby formed between one edge of the second tube plate 130 and the housing 106, i.e. connecting the purge chamber 115 and the outlet plenum 113. A mesh pad 132 is arranged to extend across the passage. The mesh pad 132 is configured to allow gas that exits the cyclones 112 through the liquid outlet 126 (i.e. purge gas) to travel to the gas outlet 116, whist preventing liquid from passing through. As the mesh pad can be designed to treat only the purge gas, its operation efficiency can be increased.

The apparatus 100 also includes a third tube plate (not shown) arranged to separate the inlet plenum from the cooling portion, the third tube plate being arranged so as to contain the fluid stream within the inlet plenum and the cooling medium within the cooling portion. The cooling pipes 110 are arranged to extend through the third tube plate.

In operation, the apparatus 100 performs as follows. A fluid stream enters the housing 106 through an inlet (not shown) and collects in the inlet plenum. A portion of the fluid stream enters each of the cooling pipes 110. The cooling medium 120 flows freely around the cooling pipes 110, while the fluid stream flows within the cooling pipes 110, fluidly isolated from but in thermal contact with the cooling medium 120. Heat is thereby exchanged between the fluid stream and the cooling medium 120, thus cooling the fluid stream and causing some liquids to condense out of the fluid stream.

The cooled fluid stream flows directly from each cooling pipe 110 into a respective cyclone separator 112. The cyclone separators 112 can be configured to induce cyclonic motion in the fluid stream, i.e. a rotational motion about a central axis, which causes the gas phase and the liquid phase to separate. The liquid phase exits the cyclone separators 112 through slits 126 in the walls of the cyclones 112 (aided by the purge gas) and drains downward by the action of gravity. In addition to or instead of slits 126, porous walls can be used. An exemplary porous cyclone separator is described in EP 2907560 B1. The drained liquid recombines to form a single liquid phase stream and is output from the housing via liquid outlet 114. The liquid phase may contain water, liquid glycol, liquid hydrocarbons, etc. In this example the separated liquid phase stream is stored in a compartment 134; however the liquid phase stream could be output to -15 -other locations such as to other components for further processing, e.g. to separate the liquid phase into its components e.g. glycol, water, liquid hydrocarbons etc. The majority of the gas phase (i.e. except the purge gas) continues through the cyclones 112 and is recombined into a single gas phase stream in the outlet plenum 113 of the housing 106 downstream of the cyclones 112. The single gas phase stream then exits the housing via the gas outlet 116 and may be transported elsewhere for further processing.

Some gas may exit the cyclones 112 via the slits 126 in the cyclones 112. This gas will travel through the mesh pad 128 and recombine with the single gas phase stream. Liquids remaining in this gas will be removed by the mesh pad 128 and will drain out of the liquid outlet 114 with the remainder of the liquid phase stream.

Figure 6 shows the apparatus 100' of Figure 3 in more detail, in which the cyclone separators are replaced with a vane pack.

The apparatus 100' comprises the cooling portion 102' and the separation portion 104' housed within the housing 106'. The cooling portion 102' is a shelland-tube type heat exchanger comprising a shell 138' and a plurality of tubes 110' (i.e. the cooling pipes 110'). The housing includes the fluid stream inlet 108', the inlet plenum 103', the outlet plenum 113', the liquid outlet 114' and the gas outlet 116'.

The cooling medium enters the shell 138' at a cooling medium inlet 140', and exits the shell 138' at a cooling medium outlet 142'. The cooling portion 102' comprises a plurality of baffles 144' arranged within the shell 138'. While circulating within the shell 138', the cooling medium flows around the baffles 144' to increase contact between the cooling pipes 110' and the cooling medium, and thereby increase the cooling effect.

The apparatus 100' comprises a first tube plate 136' through which the cooling pipes 110' extend. The inlet of each cooling pipe 110' is located on a first side of the first tube plate 136' and the outlet of each cooling pipe 110' is located on a second side of the first tube plate 136'. The first tube plate 136' is located adjacent to the inlets of the cooling pipes 110'. The first tube plate 136' separates the inlet plenum 103' from the cooling portion 102'. The first tube plate 136' is arranged so that the fluid stream in the inlet plenum 103' is contained to the first side of the first tube plate 136', and the cooling medium circulating around the cooling pipes 110' is contained to the second side of the first tube plate 136'.

-16 -The cooling pipes 110' are connected directly to the vane pack 118'. The structure of a vane pack 118' will be described in more detail later with reference to Figures 7, 8 and 9.

The apparatus 100' comprises a second tube plate 128' through which the cooling pipes 110' extend. The inlet of each cooling pipe 110' is located on a first side of the second tube plate 128' and the outlet of each cooling pipe 110' is located on a second side of the second tube plate 128'. The second tube plate 128' is located adjacent to the outlets of the cooling pipes 110'. The second tube plate 128' divides the housing 106' into the cooling portion 102' and the separation portion 104'. The second tube plate 128' is arranged so that the gas phase stream output from the vane pack 118' is contained to the second side of the second tube plate 128', and the cooling medium circulating around the cooling pipes 110' is contained to the first side of the second tube plate 128'. The second tube plate 128' thereby forms a seal between the cooling portion 102' and the separation portion 104'.

In operation, the apparatus 100' performs as follows. A fluid stream enters the housing through the fluid stream inlet 108' and collects in the inlet plenum 103'. A portion of the fluid stream enters each of the cooling pipes 110'. The cooling medium enters the shell 138' through the cooling medium inlet 140', flows across the cooling pipes 110' and around the baffles 144', and exits the shell 138' via the cooling medium outlet 142'. Heat is exchanged between the fluid stream and the cooling medium, thus cooling the fluid stream and causing some liquids to condense out of the fluid stream.

The cooled fluid stream flows directly from each cooling pipe 110' into a channel of the vane pack 118'. Multiple cooling pipes 110' may lead into a single (i.e. the same) channel of the vane pack 118'. The fluid stream is forced to make sharp turns as it flows through the vane pack 118'. The liquid phase is captured by walls or vanes of the vane pack 118', and drains downward by the action of gravity. The drained liquid recombines to form a single liquid phase stream and is output from the housing 106' via liquid outlet 114'.

The gas phase continues through the vane pack 118' and is recombined into a single gas phase stream in the outlet plenum 113'. The single gas phase stream then exits the housing 106' via the gas outlet 116' and may be transported elsewhere for further processing.

-17 -The apparatus 100 may comprise a shell-and-tube type heat exchanger and/or other features as described in respect of apparatus 100'. The primary difference between apparatus 100 and apparatus 100' is that apparatus 100 utilises cyclone separators 112 as the plurality of inertial separators, whereas apparatus 100' utilises a vane pack 118'. Most or all other features may be common between the two embodiments.

Figures 7, 8 and 9 show examples of the configuration and operation of vane packs. Each Figure shows two adjacent walls or vanes 146 of the vane pack 118 which form a channel 152 therebetween. The cooled fluid stream is configured to flow through the channel 152. Figure 7 shows a vane pack 118 with single-pocket vanes, Figure 8 shows a vane pack 118 with horizontal-flow double-pocket vanes, and Figure 9 shows a vane pack 118 with vertical-flow double-pocket vanes.

The vanes 146 of the vane pack 118 are shaped to include sharp bends which cause the fluid stream to turn sharply as it flows through the vane pack 118.

The liquid in the fluid stream will collect in hooks or pockets 148 arranged on the vanes 146, whereas the gas will follow the "zig-zag" path through the channel 152 between the vanes 146. The liquid will then drain downwards due to the action of gravity.

In Figures 7 and 8, the vanes are arranged to form "horizontal-flow" vanes in which the gas phase travels substantially horizontally and the liquid drains vertically downwards. In Figure 9, the vanes are arranged to form "vertical-flow" vanes in which the gas phase travels substantially vertically upwards and the liquid phase travels substantially vertically downwards.

In vane packs with double-pocket vanes as shown in Figures 8 and 9, each vane 146 includes two substantially parallel and closely positioned walls 150 which form a pocket therebetween, through which the liquid can travel as it drains downwards.

The vane packs described herein can be used as the inertial separator in apparatus 100' and/or apparatus 100" as described previously.

Figures 10, 11 and 12 show an apparatus 200 according to a fourth embodiment of the invention. The apparatus 200 comprises a vane pack separator 201 including multiple double-walled or double-pocket vanes 202. Each vane 202 comprises two walls 204 which are substantially parallel and closely positioned to form a pocket 206 therebetween.

-18 -The vane pack separator 201 comprises multiple channels 208, each configured to receive a portion of the fluid stream. The vanes 202 are arranged in a "zig-zag" configuration so as to force the fluid stream to take sharp turns as it flows through the channel 208. The pockets 206 will catch liquid in the fluid stream as it passes through the vane pack separator, whereas gas in the fluid stream will continue through the channel 208. The vanes 202 may also include hooks to aid liquid capture as in conventional vane pack separators, although these are not shown in the figures for simplicity.

The vane pack separator 201 also comprises multiple cooling tubes 210 positioned within the vanes 202, between the vane double walls 204. The cooling tubes 210 are configured to receive a cooling medium and to bring the cooling medium into thermal contact with the fluid stream as the fluid stream flows through the channels 208. The cooling medium may also pass between walls. As the fluid stream cools, some liquids will condense out of the fluid stream and be captured by the pockets 206 and hooks (not shown). The liquid will then drain downwards due to gravity.

Figure 12 shows the vane pack separator 201 positioned in the integrated cooling and gas-liquid separation apparatus 200. The vane pack separator 201 is housed in a housing 212. The housing 212 comprises a fluid stream inlet 214, an inlet plenum 216, an outlet plenum 218, a gas phase outlet 220 and a liquid phase outlet 222. The vane pack separator 201 includes a cooling medium inlet 224 and a cooling medium outlet 226.

In operation, the apparatus 200 performs as follows. A fluid stream enters the fluid stream inlet 214 and collects in the inlet plenum 216. The fluid stream enters the channels 208 of the vane pack separator 201. A cooling medium enters the vane pack separator 201 through cooling medium inlet 224, circulates through the cooling tubes 210 positioned within the vanes 202, and exits the vane pack separator 201 via cooling medium outlet 226. As the fluid stream passes through the vane pack separator 201, it is simultaneously cooled by the cooling medium and separated into a gas phase stream and a liquid phase stream by the configuration of the vanes 202. The gas phase stream exits the channels 208, recombines in the outlet plenum 218, and is output from the housing 212 via gas outlet 220. The liquid phase stream captured by the vanes 202 drains downwards due to the act of gravity and exits the housing via liquid outlet 222.

-19 -The apparatus therefore performs simultaneous cooling and gas-liquid separation of the fluid stream, removing the need for a separate cooler and gas-liquid separator.

Claims

-20 -CLAIMS: 1. An apparatus for combined cooling and gas-liquid separation of a fluid stream, comprising: a cooler comprising a plurality of cooling passages, the cooling passages being configured to receive the fluid stream and to exchange heat between the fluid stream and a cooling medium outside of the cooling passages; wherein at least a portion of each of the cooling passages is arranged to form an inertial separator to thereby separate the fluid stream into a gas phase stream and a liquid phase stream.
2. An apparatus as claimed in claim 1, wherein one or more of the inertial separators comprises a cyclone separator.
3. An apparatus as claimed in claim 1 or 2, wherein one or more of the inertial separators comprise respective channels of a vane pack separator.
4. An apparatus as claimed in claim 1, 2 or 3, wherein the plurality of cooling passages are housed within a common housing
5. An apparatus as claimed in claim 4, wherein the housing comprises an inlet for receiving the fluid stream, a first outlet configured to output the gas phase stream and a second outlet configured to output the liquid phase stream.
6. An apparatus for combined cooling and gas-liquid separation of a fluid stream, comprising: a cooling portion comprising a plurality of cooling pipes configured to receive the gas-liquid stream and to exchange heat between the fluid stream and a cooling medium to cool the fluid stream; and a separation portion comprising a plurality of inertial separators configured to separate the cooled fluid stream into a gas phase stream and a liquid phase stream; and wherein each of the plurality of cooling pipes includes an outlet which is connected directly to a channel of one of the inertial separators.-21 -
7. An apparatus as claimed in claim 6, wherein the cooling portion and the separation portion are housed within a common housing.
8. An apparatus as claimed in claim 7, wherein the housing comprises an inlet for receiving the fluid stream, a first outlet configured to output the gas phase stream and a second outlet configured to output the liquid phase stream.
9. An apparatus as claimed in claim 7 or 8, wherein the cooling portion and the separation portion are separated within the housing by a first plate, wherein the cooling pipes are arranged to pass through the first plate, and wherein the plate is arranged to prevent the passage of fluid between the separation portion and the cooling portion except through the cooling pipes.
10. An apparatus as claimed in any of claims 6 to 9, wherein one or more of the inertial separators comprises a cyclone separator.
11. An apparatus as claimed in claim 10, wherein the separation portion comprises a second plate offset from the first plate in an axial direction of the apparatus, wherein the second plate is arranged to divide the separation portion into a purge chamber in which a liquid phase stream outlet of each cyclone separator is located and an outlet plenum in which a gas phase stream outlet of each cyclone separator is located.
12. An apparatus as claimed in claim 11, wherein the purge chamber and the outlet plenum are in fluid communication via a passage which is separate from the cyclone separators.
13. An apparatus as claimed in claim 12, wherein a mesh pad is arranged across the passage.
14. An apparatus as claimed in any of claims 6 to 9, wherein one or more of the inertial separators comprise respective channels of a vane pack separator.-22 -
15. An apparatus as claimed in claim 14, wherein one or more of the cooling pipes is connected directly to a channel between adjacent vanes of the vane pack separator.
16. An apparatus as claimed in any of claims 6 to 15, wherein the cooling portion comprises a shell and tube heat exchanger.
17. An apparatus for combined cooling and separation of a fluid stream, comprising: an inertial separator configured to receive the fluid stream and to separate the fluid stream into a gas phase stream and a liquid phase stream; wherein the inertial separator is also configured to exchange heat between the gas-liquid stream and a cooling medium to cool the gas-liquid stream as the gas-liquid stream flows through the inertial separator.
18. An apparatus as claimed in claim 17, wherein the inertial separator includes one or more channels which are arranged to permit a portion of the fluid stream to flow therethrough, and wherein the inertial separator is arranged so that the fluid stream is in thermal contact with a cooling medium as it flows through the one or more channels.
19. An apparatus as claimed in claim 17 or 18, wherein the inertial separator comprises a vane pack separator comprising a plurality of vanes.
20. An apparatus as claimed in claim 19, wherein the vane pack separator comprises one or more cooling tubes arranged inside the vane pack separator, the cooling tubes being configured to receive a cooling medium and to circulate the cooling medium within the vane pack separator.