WO2013154436A1 - Dispositif d'entrée pour des tours de déshydratation - Google Patents

Dispositif d'entrée pour des tours de déshydratation Download PDF

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Publication number
WO2013154436A1
WO2013154436A1 PCT/NO2013/050064 NO2013050064W WO2013154436A1 WO 2013154436 A1 WO2013154436 A1 WO 2013154436A1 NO 2013050064 W NO2013050064 W NO 2013050064W WO 2013154436 A1 WO2013154436 A1 WO 2013154436A1
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Prior art keywords
liquid
gas
inlet
cyclone
section
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PCT/NO2013/050064
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English (en)
Inventor
Dag Kvamsdal
Knut Sveberg
Mauritz Talseth
Fredrik CARLSON
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Cameron Systems As
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Publication of WO2013154436A1 publication Critical patent/WO2013154436A1/fr

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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
    • B01D53/26—Drying gases or vapours
    • B01D53/263—Drying gases or vapours by absorption
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D19/00—Degasification of liquids
    • B01D19/0042—Degasification of liquids modifying the liquid flow
    • B01D19/0052—Degasification of liquids modifying the liquid flow in rotating vessels, vessels containing movable parts or in which centrifugal movement is caused
    • B01D19/0057—Degasification of liquids modifying the liquid flow in rotating vessels, vessels containing movable parts or in which centrifugal movement is caused the centrifugal movement being caused by a vortex, e.g. using a cyclone, or by a tangential inlet
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D45/00—Separating dispersed particles from gases or vapours by gravity, inertia, or centrifugal forces
    • B01D45/12—Separating dispersed particles from gases or vapours by gravity, inertia, or centrifugal forces by centrifugal forces
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B04—CENTRIFUGAL APPARATUS OR MACHINES FOR CARRYING-OUT PHYSICAL OR CHEMICAL PROCESSES
    • B04C—APPARATUS USING FREE VORTEX FLOW, e.g. CYCLONES
    • B04C3/00—Apparatus in which the axial direction of the vortex flow following a screw-thread type line remains unchanged ; Devices in which one of the two discharge ducts returns centrally through the vortex chamber, a reverse-flow vortex being prevented by bulkheads in the central discharge duct
    • B04C2003/006—Construction of elements by which the vortex flow is generated or degenerated

Definitions

  • the present invention relates to separation of liquid from a gas stream, particularly in production of oil and gas. More precisely, the present invention relates to an inlet device intended for use in dehydration towers designed typically for the removal and drain of liquid from a the gas stream entering the dehydration tower.
  • the well stream will normally contain oil, gas, water and some solid particles.
  • a dedicated process system for the well stream is constructed.
  • the natural gas needs to go through several process steps before entering the supply network.
  • the separation is made in several stages, where the "bulk separation" of the various phases is carried out by gravity forces alone where the immiscible fluids are separated based on difference in densities, and the "fine separation” or purification is often done utilizing centrifugal forces and inertial forces together with the gravity force.
  • a challenge appearing in many separation stages is to remove liquid droplets from a gas stream where the liquid content in the gas is low, typically less than 3 vol% of the total volumetric flow. It is of outmost importance to remove most of this liquid in order to protect downstream equipment such as compressors and dewatering equipment where only traces of liquid may create operational problems.
  • separators dedicated to separate gas/liquid mixtures containing less than said 3 vol% liquid is denoted gas scrubbers.
  • the natural gas is processed during several steps of re-compression, heating and scrubbing before it is ready for transport.
  • This process controls the hydrocarbon dew point of the gas, assuring the correct heating value for the gas before transport.
  • Another important criterion for the rich gas is the water content, or more precisely the water dew-point. This specification shall assure that absolutely no free water is formed whatever operation is performed.
  • the typical dew point specification is -18°C at 70 bara. Free water can cause both hydrate plugging and corrosion problems.
  • the water removal starts already in the well, due to the temperature and pressure reduction. Water is further removed in the separators, which as mentioned remove the bulk liquid.
  • the final water removal is usually done through two techniques: Absorption into a glycol or adsorption into a solid material (typically molecular sieve or silica gel).
  • the absorption process is usually done in a vertically oriented vessel, often called a contactor tower.
  • a contactor tower consists of a spraying mechanism that shall evenly spray the gas with glycol.
  • Triethylene glycol, TEG is normally used in the Norwegian Sea.
  • the wet gas is fed into the bottom of the contactor through a scrubber section.
  • This section shall remove solids and liquids which can contaminate the glycol.
  • the scrubber section and the absorption section is separated from each other by a plate consisting of so called chimney trays that allow the solid- and liquid- free gas to enter the absorption section.
  • the lean in water glycol enter at the top of the absorption tray and run downwards due to gravity, while the gas at the same time is flowing upwards.
  • a mass transfer is taking place due to the affinity glycol have to water molecules and the water content inside the gas is reduced upwards in the column.
  • there are several trays or some kind of packing inside the absorption section that shall mix gas and glycol so that the mass transfer of water increases.
  • a demisting section is usually placed at the top of the dehydration tower so that the carry-
  • the well stream enters the inlet separator, where the gas and liquid is separated.
  • the gas leaves at the top of the separator, and flows further to the first scrubber.
  • the gas is further treated in a sour gas absorber, where typically H 2 S and C0 2 are removed.
  • a scrubber before the dehydration tower.
  • the dehydration tower there are very often scrubber in the bottom of the dehydration tower to remove all liquid condensated during the piping.
  • the scrubber in the lower section of the contactor tower usually contains an inlet device together with a mesh pad. The contactor height and diameter is mainly controlled by the mass transfer between the glycol and the water.
  • the separation typically takes place in several stages.
  • the gas enters through an inlet nozzle, which - for vertical oriented scrubbers.
  • a momentum breaker plate, a vane diffuser or any device can be located in order to d istribute fluids across the scrubber cross-sectional area.
  • the largest drops are separated and falling down onto the liquid reservoir in the lower part of the vessel.
  • the gas will flow upwards into a calm zone, or deposition zone, where further droplets due to gravity falls down onto the liquid surface below, alternatively deposits on the separator wall and drain downwards along this.
  • the gas is forced to pass through tubes that connect the lower section scrubber to the dehydration section, so-called Chimney trays.
  • Chimney trays There are mainly three categories of droplet separation equipment; mesh pad, vane pack and parallel arranged axial flow cyclones. Because of the pressure drop across the droplet separation equipment, the separated liquid is normally drained down to the liquid reservoir through a said drainpipe, whose lower end is submerged in the liquid reservoir.
  • separator inlet device is correctly designed relatively to the separator cross sectional area in order to remove as much liquid as possible to minimize the amount of liquid fed to the demisting equipment. This is particularly important for vertical scrubbers and contactor columns to remove aqueous vapor from a gas stream.
  • a bad performing inlet device in the scrubber can cause liquid carry-over into the hydration section, leading to contaminated glycol and incorrect water dew point of the natural gas. Which might in the worst case cause hydrate formation during pipeline transport.
  • Most inlet devices of known technology uses gravity forces alone to separate liquid in the scrubber inlet compartment, giving stringent limits to the gas velocities before considerable amounts of liquid is following the gas to the demisting equipment.
  • the objective of the present invention is to provide a more compact but still efficient scrubber section in the lower scrubber inside the contactor tower by connecting the inlet device together with the so called chimney trays.
  • the present invention is a.
  • the above mentioned object is fulfilled with the present invention, which is an inlet device as defined by claim 1.
  • Preferred embodiments of the invention are disclosed by the dependent claims.
  • the scrubber vessel will typically be a vertical section of a glycol contactor tower typically compromising:
  • a vessel that has an upper gas filled compartment and a lower liquid filled compartment • an inlet section usually designed to reduce the inlet momentum from the pipe into the vessel and assure a good flow distribution in the vessel, there are inlet sections that aim to do pre separation of liquid from gas in addition and the present invention represent such a device.
  • an agglomorator unit placed between the inlet section and the last treating section used to increase the droplet size and improve the gas and liquid distribution into the last treating stage in the vessel.
  • the new invention will be the inlet section in the lower scrubber section and includes a demisting stage that is able to remove the major part of the liquid.
  • the inventive design allows removal of more than 97% but typically 99% or more of the liquid before the gas is introduced into the dehydration section of the tower. By removing the major part of the liquid the gas quality out from the vessel will be improved.
  • the new inlet section will treat the inlet mixture using centrifugal forces and will typically compromise:
  • the distribution chamber that will distribute the mixture entering the vessel through the inlet nozzle into one or more treating devices for the fluid.
  • the distribution chamber will also usually have an outlet that allows any liquid separated inside the distribution chamber to flow out into the vertical vessel.
  • the distribution chamber comprises at least a bottom wall, a top wall and one or more side walls in addition to inlet and outlets.
  • the vertical gravity vessel will contain an internal vessel that distributes the gas into a set of cyclones where the inlet fluid is set in rotation by means of a swirl-inducing device being outward delimited by the cyclone body so that the incoming fluid is exposed to a centrifugal force in addition to the gravity force.
  • Most of the liquid will, because of the centrifugal force, be separated immediately towards the cyclone walls and follow the wall until it exits the laterally arranged openings.
  • gas may be allowed to follow the liquid through the liquid openings as well.
  • the mixture with predominately gas will exit the cyclone tube at the opposite end of the entrance with the swirl inducing element.
  • the separator device as such is according to known technology, normally denoted as axial flow cyclones or demisting cyclones.
  • the axial cyclones are well suited for a multiphase mixture that will consist of mainly gas.
  • the gas will pass the tube in a single pass from the inlet to the outlet. This is unlike a reversible cyclone for gas where the gas exits at the top of the cyclone and exit at the top of the cyclone.
  • the gas which is typically more than 97% of the volume in the feed will need to turn inside the cyclone before exiting the cyclone.
  • the gas will utilize the full cross section flowing from the inlet at one side towards the outlet at the other side and will hence be better suited for a flow that mainly contain gas.
  • the gas outlets of the inlet device will be connected directly into the chimney trays that divide the scrubber and the dehydration section inside a contactor tower, or the axial flow cyclones might be arranged inside the chimney trays to reduce the needed space for the lower scrubber section of the dehydration tower.
  • the inlet pipe into the vessel is connected to the inlet distribution chamber that distributes the gas and liquid into the vertically oriented cyclones tubes. Any liquid separated by gravity in the inlet chamber upstream the cyclone will be drained in a separate pipe from the inlet chamber.
  • the cyclone tubes are designed as cyclones where the gas is set into rotation in a spin element at the entrance end and exits at the outlet of the other end of the cyclone. The gas flow will hence never be reversed as in reversible gas cyclones and this allows higher gas velocity in the axial flow cyclones. Liquid that hits the inner wall of the cyclone is drained through slits in the cyclone wall into outer liquid collector chambers.
  • the liquid is then drained from the liquid collector boxes underneath the inlet section.
  • the invention is further described with references in the following.
  • the invention will separate gas from liquid using axial flow cyclones.
  • the liquid and the gas will then be introduced as a predominately gas containing stream and a predominately liquid containing stream into the scrubber section at a common pressure. This is unlike other inlet types where the gas and liquid exits the vessel into different chambers with different pressure.
  • the present invention is aiming to utilize the best elements from each of the previously described separation technologies in order to achieve an efficient scrubber at higher gas flow rates.
  • the invention is for a two stage separator where the separation occurs in two separate stages.
  • the gas will hence pass two scrubbing stages where the first one removes the bulk of the liquid typically 98 % or more and the second cleans out the liquid that remains in the gas typically more than 98% of the remaining liquid assuring a high efficiency.
  • the present invention will address the issues with currently known technology and aim to be compact, have low pressure drop and will be able to combine the liquid streams from the 1 st and 2 nd treating stages inside the vessel.
  • the pressure differences are all balanced out using downcomers and height differences between the individual elements.
  • the invention uses axial flow cyclones where the gas and liquid mixture enters the cyclone at one side and the gas leaves at the other side of the tube.
  • the liquid will be extracted through the wall of the cyclone through openings designed to extract liquid from the gas stream.
  • the advantage of using axial flow cyclones for scrubbing where the gas content typically is between 95% and 100% volumetric is that unlike reverse cyclones often used the gas will utilize the full body of the cyclone for separation and only make one pass through the cyclone.
  • the gas flow will first be downward in the cyclone before turning and exit the cyclone at the same end as the inlet.
  • the present inlet device is meant for single stage scrubbers where the liquid is separated from the gas in one stage before entering the dehydration section.
  • the usual scrubber design will have an inlet that does no separation. Then there is a vessel volume that does the bulk separation where a large part of the liquid is separated.
  • the gas will pass a coalescing and flow distribution section that usually is either a mesh pad or a vane pack before the demister.
  • the demister may be another mesh pad or it could be a vane pack or demisting cyclones that cause some pressure drop.
  • a pipe or so called downcomer is used in order to transport the liquid from the demister down into the liquid pad.
  • the downcomer extends from the demister section down into the liquid pad. The difference in pressure between the liquid collection chamber in the downcomer and the liquid pad in the vessel will be compensated by liquid being pulled up in the downcomer.
  • Figure 1 is a schematic view of an embodiment of the present invention.
  • Figure 2 is a cross-sectional view of prior art gas scrubber equipped with a vane diffuser inlet device, demisting equipment and internal drainpipe.
  • Figures 3 a, b, c, d, and e show the functional principle of axial flow cyclones that are used for separating in the new inlet section.
  • Figures 4 a and b show cross sectional views of prior art gas scrubber equipped with a cyclonic inlet device, demisting equipment and internal drainpipe.
  • Figure 5 shows a cross sectional view of a prior art single-stage cyclonic scrubber.
  • Figure 6 shows a cross sectional view of a prior art single stage inline scrubber.
  • Figures 7 a, b, and c show cross sectional views of prior art multi cyclone scrubber inlets arranged in a vertical scrubber vessel.
  • Figure 8 shows cross-sectional views of scrubbers using the extension of the inlet pipe as a cyclone.
  • the present invention is an inlet device 17 that will separate liquid from the gas prior to the gas entering the dehydration tower.
  • the invention as installed in a dehydration vessel is showed in Figurel.
  • the gas and liquid enter the vessel through the inlet nozzle 1.
  • To the right the inlet device 17 is shown enlarged with two different degrees of magnification.
  • the flow then enters distribution chamber 2 that is used to distribute gas and liquid evenly into the chimney trays 3 mounted on top of the section plate 4 dividing the vessel into a the lower scrubber section 5 and dehydration section 6.
  • the section plate 4 is in one embodiment constituted by the top plate of the distribution chamber, thereby allowing a particularly compact structure of the inlet device of the present invention.
  • a liquid remove device is mounted inside or partly inside the chimney trays to separate liquid.
  • the liquid removal device is shown as axial cyclones 28, but can be any kind of liquid removal device.
  • the axial cyclones 28 are mounted together in liquid collection chambers 8.
  • the number of axial flow cyclones 28 in these chambers 8 varies.
  • This liquid that separates in the distribution chamber 2 is transported out and below the inlet section th rough a liquid drain pipe 29. This will be a stream that contains liquid part of the liquid and the outlet of this pipe is extended underneath the distribution chamber 2 into the scrubber section 5.
  • the main bulk of gas will be transported through the axial flow cyclones 28 where the liquid is separated from the gas using centrifugal force.
  • One of the benefits of the current invention is the use of parallel elements for the separation. These elements will be small in dimension compared to the size of the vertical vessel. For large scrubbers with high gas load the adding of more cyclones in parallel for higher capacities will maintain the high efficiency that represents a challenge for separators relying on centrifugal force aiding separation when used in larger separator vessels.
  • the cyclone will separate the inlet mixture into a part that contains the major part of the liquid that will have an exit 30 underneath the inlet section. Since there is higher pressure in the cyclone liquid collection chamber 8 than in the vessel some gas might follow the liquid in the downcomer 30. There will be some gas associated with the liquid in liquid drain pipe 29 and downcomer 30. The amount of gas will typically be less than 20% of the total gas and the gas loading underneath the inlet section will be low. The small amount of gas following the liquid underneath the inlet section will be polished in the mesh pad 31. The amount of liquid separated in the cyclones and transported underneath the inlet section will typically be more than 99% of the total liquid in the feed.
  • the inlet section there will be a gas liquid mixture that typically contains less than 20% of the gas and 99% or more of the liquid in the inlet nozzle.
  • the liquid will then be separated in the zone underneath the inlet section both by gravity and in the mesh pad 31 and fall down into the liquid pad 7 of the gravity separator before the liquid exits the vessel through the liquid outlet nozzle 20.
  • the gas following the liquid underneath the inlet section will flow upwards past the inlet section and through at least one or more of the Chimney trays 25 not connected directly to the inlet device though the inlet distribution chamber 2, where it will be mixed with the major part of the gas that comes out through the top of the remaining chimney trays 27 and into the dehydration zone 6, the dehydration zone will most likely contain an arrangement that increases the mass transfer of water to the glycol, typically a structured or unstructured packing 26.
  • the gas flow that follows the liquid underneath the inlet section will typically contain 99% or more of the liquid while the amount of gas will typical represent less than 20% of the total gas flow.
  • the liquid has to be separated from this slip stream of gas before being recombined with the gas exiting the top of the Chimney trays 27.
  • the liquid that follows the gas on the underside of the inlet section will be separated in the space underneath the inlet section.
  • the separation will be partly due to gravity.
  • the gas loading underneath the inlet section will be much lower than upstream of the inlet section since only typically 20% or less of the gas will exit through the downcomer 30.
  • the low gas loading underneath the inlet section will reduce liquid entrainment.
  • the low gas loading will make this volume well suited for use of a traditional demister section to further clean up of the gas.
  • This will typically be a mesh pad 31 but the demister might also be a vane pack or a axial flow cyclone.
  • the cyclone might be located in the chimney tray 25 not embodied by the inlet device.
  • the demister will assure that the gas that has followed the liquid underneath the inlet section is clean.
  • the inlet section will typically be designed to achieve 99% or more separation efficiency.
  • the liquid that is separated out in the cyclones 28 is drained through the inlet device using downcomers 30.
  • the downcomers 30 that extend through the inlet device will also act as mechanical support of the inlet device, but the downcomers 30 might also be piped outside the inlet device if this is more installation friendly.
  • the arrangement of the downcomers 30 underneath the inlet section may be arranged so that each of the downcomers 30 is extended underneath the inlet device.
  • the piping from the cyclones may also be gathered in manifolds from where one or more pipes are extended further down from such manifolds.
  • each downcomer should preferably use a diffuser 13 on the end of each downcomer.
  • the diffuser will reduce the momentum of the gas out from the pipes.
  • the diffuser should be designed so that the gas flow is directed horizontally in the vessel and not downwards. The gas velocity out from the downcomer tube should not be directed directly towards the liquid pad in the vessel to minimize liquid re entrainment from the vessel.
  • An alternative to the described piping underneath the inlet chamber for the liquid rich stream out of the cyclones is one in which the liquid is allowed to flow freely out of the liquid collection chamber 8 through holes in the liquid collection chamber 8 out into the lower section scrubber 5 . Because of the higher pressure in the liquid collection chamber 8 the liquid will contain some gas when entering the lower section scrubber 5. The liq uid rich mixture from the liquid collection chamber 8 will then typically be drained to the top of the distribution chamber 2 rather than guided underneath the liquid section using the downcomers 30. The flow out of the top of cyclones 9 will be mainly gas with traces of liquid.
  • the gas that exits through the top of the cyclones and the chimney trays will be mixed with the gas that exits with the liquid coming up around the inlet section by allowing this slip stream of gas to leave the scrubber section through one or more of the total amount of chimney trays.
  • the gas will then be clean when entering the dehydration section.
  • the advantage of the new inlet 17 is that it improves the gas quality in the vessel by removing the liquid already in the inlet section with the possibility of reducing vessel size by avoiding the liquid seal on the downcomers.
  • the liquid drain for the inlet device may be replaced by any pressure-resisting device, or axial flow cyclones that are located at the underside of the inlet chamber instead of the liquid drain pipe 29 from the distribution chamber 2.
  • the cyclones replacing the drain pipe 4 may be similar to the cyclones directed upwards. Any liquid separated in the distribution chamber 2 by gravity will drain out through the cyclones on the underside of the chamber.
  • the amount of gas treated by the cyclones that has a gas outlet in the underside of the inlet chamber will typically be less than for the cyclones that is directed upwards, but typically less than 20% of the total gas flow into inlet 1.
  • the gas that is treated underneath the inlet chamber will have to pass the inlet section again on the way upwards increasing the gas load when the gas flow past the inlet section since the inlet section itself will displace some of the flow area available.
  • the inlet distribution chamber 2 is designed to assure that the inlet feed is evenly distributed to the multiple cyclones 28 mounted on the inlet chamber.
  • the cyclones might be arranged inside or partly inside the Chimney trays.
  • the design of the inlet distribution chamber 2 reflects this where the inlet distribution chamber has a larger cross sectional flow area close to the inlet nozzle than further away from the inlet nozzle typically achieved by a sloped underside of the inlet distribution chamber, so that the inlet chamber is highest close to the inlet nozzle and has the lowest height at the opposite end of the inlet section.
  • vanes at the inlet may be arranged vanes at the inlet to help spread the inlet fluid across the full cross section of the inlet distribution chamber to improve the flow distribution in the inlet chamber further.
  • the design of the inlet distribution chamber 2 may also take into account the drainage of solids from the chamber.
  • the design of the inlet distribution chamber 2 should be designed inclined bottom to assure no solids accumulation at the bottom of the inlet chambers.
  • the plates should typically be tilted 45 Q or more towards the drain pipe 4 of the inlet distribution chamber to assure that solids will not accumulate in the bottom of the distribution chamber 2 but rather slide down through the drain pipe 4 helped by gravity.
  • Figure 2 shows a separator for removal of a mist of droplets according to known technology, comprising a vane diffuser inlet device 102 receiving the inlet gas from the inlet nozzle 101 as gentle as possible and distributing the gas and liquid mixture into the separation zone 109 evenly to utilize the vessel volume.
  • the zone 109 represents the 1 st stage of separation where the liquid is separated from gas due to gravity.
  • the separation efficiency will be a function of the amount of gas.
  • the size of the vessel will then be decided to assure the scrubber efficiency by controlling the gas load in the vessel.
  • Vane diffuser inlet devices are currently the preferred inlet device technology in gas scrubbers.
  • Gas passing through the separation zone 109 will typically contain many small and some medium size droplets entering the demisting equipment 111, here illustrated as axial flow cyclones installed within the Chimney trays 117, where further amounts of liquid is separated. Liquid separated by the demisting equipment 111 is collected in a chamber 113, and then drained through the downcomer 115. As earlier explained, the pressure on the downstream side of the axial flow cyclones will be lower than the pressure upstream the axial flow cyclones, and therefore the downcomer 115 has to be submerged in the liquid pad 107 to avoid gas flowing counter current with the liquid in the downcomer 115 due to the pressure difference.
  • the liquid column pulled up in the downcomer 115 balances this pressure difference between chamber 113 and gravity separator zone 109.
  • the liquid level 116 in the downcomer 115 will therefore be higher than level of the liquid pad 107 in the scrubber.
  • the available height above the liquid level 116 is a design parameter with respect to dimensioning the gas scrubber. At too high gas flow rates relatively to the scrubber height, liquid will be sucked up into the chamber 113 and further into the gas outlet 112 which is critical for the operation.
  • Axial flow cyclones will be an integrated part of the current invention and several types of axial flow cyclones are known.
  • Fig. 3a shows an example of an axial flowing cyclone of known category, i.a described in patent applications PCT/NL97/00350, PCT/NL99/00677 and NL20001016114.
  • the notion "axial cyclone” is due to fact that the main gas transport is in the longitudinal direction of the cyclone where the flow inlet is oriented at the opposite end of the gas outlet. There will be minimum one swirl-inducing element oriented towards the inlet side of the cyclone.
  • the cyclone will have slots or perforations in parts of the cyclone tube to allow the liquid phase to exit the cyclone laterally.
  • the axial flow cyclone 29 comprises a cylindrical pipe in which the gas is passing through. Inside the pipe a swirl inducing element 21 is arranged that comprises an axis symmetric concentric body with stationary vanes 22 that sets the gas stream in rotation into the separation chamber 23. Because of the gas rotational motion, liquid droplets will due to the density difference be thrown towards the wall of the cyclone tube 29. The liquid hitting the wall of the cyclone will form a thin liquid film that will be removed from the gas stream through the wall of the cyclone tube 29 through slots 24 arranged in the outlet end of the cyclone. The liquid will be collected in a drainage chamber 25 where the liquid is collected and drained through the downcomer 26 to the liquid section of the separator.
  • the cyclone is arranged as a recirculation type cyclone where a small flow of gas leaves the cyclone through the slots 24 before being re-introduced in the cyclone through the center of the swirl inducing element 21. This is done in order to aid the liquid passing though the slots 24
  • the gas purge stream is normally established to give a net flux of gas out from the slots in same direction as the liquid. This is obtained by connecting the drainage chamber 25 to the low-pressure area in centre of the cyclone tube 29, through a channel 27 connected to the central hollow flow passage 28 in the swirl element or vane cascade 21.
  • This purge gas is typically 2-10% of the total gas flow.
  • the purge gas represents a loop from the separation chamber 23 out to the drainage chamber 25 and back to the separation chamber 23.
  • the purge stream will also blow off liquid that follows the swirl inducing element 21 as a film.
  • Figure 3c shows another variation of an axial flow cyclone used for that has no recirculation of gas from the liquid drainage chamber 25.
  • the main gas flow enters the cyclone through the opening 20 and is set into rotation by swirl inducing element 21.
  • the heavier liquid is thrown towards the wall of the cyclone tube 29 by centrifugal acceleration and forms a film on the inside of the cyclone.
  • the liquid film is then removed from the cyclone wall by the slots 24 and is collected in the liquid drainage chamber 25.
  • This is similar two the cyclones previously discussed and shown in Fig. 3a and Fig. 3b.
  • this version has a channel 30 through the swirl inducing element 21 where a small part of the gas in the inlet will pass.
  • the channel 30 is preferably equipped with tangential inlets or guiding vanes to also put this stream in rotation.
  • the small amount of gas that passes through the channel 30 is used to blow any liquid that follows the swirl inducing element 21 into the separation chamber 23.
  • the cyclones in Figure 3 a, b, c may further be equipped with double curved vanes.
  • the double curved vanes as described in patent application WO 03039755 will give improved separation since the creep flow of liquid along the vanes will be forced towards the outer side of the vanes by their geometry.
  • the double curved vanes will be configured to achieve higher tangential velocity close to the center of the cyclone than at the wall and thereby give a tangential velocity in the vessel that are similar to the free vortex set up by free rotating fluid streams governed by the conservation of angular momentum.
  • FIG 3d and Figure 3e alternative swirl inducing elements are shown.
  • a set of tangential guiding vanes 32 are used to set the flow in rotation.
  • tangential port are used to set the flow in rotation.
  • the functionality of the cyclones as shown in Figure 3d and Figure 3e is similar to the cyclones shown in Figures a, b, c downstream of the swirl inducing element.
  • Figure 4a shows a cross sectional view of a former known gas scrubber equipped with a cyclonic inlet device, demisting equipment and an internal drainpipe as described in UK patent application GB2329857. This configuration is characterized by the connection between the inlet nozzle 51 and one or more cyclones through a distribution chamber 52.
  • the cyclone tube has a swirl-inducing element 53 in order to turn the incoming fluid in rotation inside the cyclone tube 54.
  • the swirl- inducing element is shown as a vane cascade but the swirl could also be induced using one or tangential inlets on the cyclone.
  • Most of the liquid is separated in the cyclone tube 54 by means of centrifugal forces downstream of the swirl inducing element 53, after which the rotational gas exits the cyclone tube 54 through a gas outlet pipe 55. Further droplet removal is done by axial flow cyclones 56 upstream the scrubber gas outlet 57.
  • the liquid level 61 in the separator is normally controlled by a valve on the separator liquid outlet
  • a substantial disadvantage utilizing this kind of cyclonic inlets is the risk of gas breakthrough in the cyclone tube liquid outlet 59. Because of the pressure drop from outlet of the swirl inducing element 53 to the top of the gas outlet pipe or vortex finder 55, the pressure at the liquid surface 63 inside the cyclone will be higher than the pressure at the liquid surface 61 at the separators deposition zone 62. If the pressure drop is too high, the liquid surface 63 inside the cyclone tube 54 will be forced down to the cyclone tube liquid outlet 59, and gas will be blown out of the liquid outlet, causing foaming and subsequently liquid entrainment to the scrubber gas outlet nozzle and gas-contaminated liquid in the liquid outlet. From this situation, the whole scrubber may "collapse".
  • the pressure drop across the gas outlet is caused by the velocity increase when the gas passes swirl inducing element or vane cascade 53 outlet to the gas outlet 55.
  • the velocity increase has two reasons; i) the gas gets a high axial velocity when it is forced through the gas outlet pipe 55) and ii) the rotational component of the gas will, due to conservation of rotational momentum increase because the gas is forced into a smaller diameter. The latter effect explains why the "ice-ballerina" increases her rotational velocity when she pulls her arms towards her body. According to the law of conservation of momentum (Bernoulli's equation), the total velocity increase will thus require a drop in the pressure (pressure in deposition zone 62 is lower than the pressure inside the cyclone tube 54.
  • Increased gas flow rates thus gives increased total velocity and consequently increased pressure drop.
  • Another disadvantage is the utilization of the flow volume in the cyclone. Because of the geometrical layout of the cyclone where the gas outlet is located at the same end as the inlet of the cyclone the gas has to flow downward in the cyclone tube 54 where the gas liquid separation occurs. After separation of liquid from the gas the clean gas flows opposite direction though the gas outlet pipe 55. If the gas outlet pipe 55 represents 50% of the flow area in the cyclone the area outside the gas outlet will be the other 50%. Hence the gas velocity in the cyclone will be at least twice of the axial cyclone as shown in Figure 3 a-e where the inlet and outlet is located at each side of the cyclone tube. The increased gas velocities inside the cyclone will give increased pressure drop and reduced separation performance.
  • FIG. 4a Another disadvantage by utilizing the cyclonic inlet device as shown in Figure 4a is the difficulty of establishing a practical arrangement of the distribution chamber 52, particularly in cases where the separator internals have to be replaceable. In those cases a bolted connection has to be made between the distribution channel, the separator wall and the cyclone tubes, causing limitations to the cyclone tube diameter and/or numbers of cyclone tubes that can fit into the vessel. If the cyclone tube does not have to be replaceable, the distribution chamber 52, which then should be cylindrical, is welded to the separator wall.
  • Figure 4b shows a variant of this technology where the liquid outlet 59 of the cyclone is not submerged.
  • the advantage is that this cyclone will not give gas carry-under into the liquid pad inside the vessel.
  • the disadvantage is that the liquid outlet will contain gas that has to be treated in the lower part of the vessel.
  • the other disadvantage is the relatively long distance needed beneath the inlet for the cyclone which requires a tall vessel.
  • Fig. 5 shows a cross sectional view of former known single-stage cyclone-separator, which for instance is described in Norwegian patent N0175569. Such configuration is characterized by that the liquid separation takes place in one single stage, and that the pressure vessel represents the cyclone tube.
  • the cyclone separator shown in Figure 5 is similar to the inlet cyclone shown in Figure 4a, but here the gravity vessel wall 74 is used as the cyclone body.
  • the separator has a swirl-inducing element 73 setting the incoming fluid in swirling motion. The liquid is separated in the cyclone separator by centrifugal forces downstream of the swirl inducing element 73.
  • the clean gas then turns and flows through the gas outlet 75, which is connected to the gas outlet nozzle 77 of the separator. No further droplet removal is made and this is hence a single stage scrubber vessel. Liquid separated in the cyclone separator is drained along the cyclone separators inner wall 74 and carried out through the cyclone separators liquid outlet nozzle 70.
  • the advantage with such an arrangement compared to inlet cyclones is the elimination of problems related to gas carry-under because liquid level 72 in the cyclone separator is directly measured and controlled.
  • the disadvantage with the arrangement is less separation efficiency because downstream droplet removal equipment is not present.
  • the patent describes a single cyclone that will have a diameter similar to the vessel diameter.
  • FIG. 6 shows an example of a formerly known cyclone described in GB1233347A.
  • the gas enters the cyclone at the end and is set into rotation in the swirl inducing device.
  • the swirl inducing element consists of a hollow hub 81 and vanes 82 that extend between the said hub 81 and the cyclone wall 89.
  • the rotational velocity of the gas moving inside the cyclone creates a centrifugal field that forces the heavier liquid particles out towa rds the cyclone wall.
  • the liquid that hits the outer wall will be gathered and form a film.
  • At the end of the cyclone tube their is a gap 84 where this liquid film is allowed to flow out into the annulus between the vessel wall 86 and the cyclone wall 89.
  • a small percentage of the gas is also allowed to follow the liquid out and will be recirculated in the center of the cyclone through the center of the swirl inducing hub 81 through the gap 84.
  • the gas is introduced into the center of the cyclone where the pressure is low due to the rotational flow.
  • the liquid will flow in the annulus and be collected in the liquid collection chamber.
  • the gas leaves the cyclone through an inserted pipe section 87 often referred to as a vortex finder.
  • the layout as shown in Figure 6 is often referred to as a single stage scrubber since the gas is separated in one single stage.
  • FIG. 7 shows an example of formerly known multi cyclone inlet i.a described in US2372514.
  • the inlet fluid containing gas, fluids and possible solids enters the vessel through inlet nozzle 91 into the distribution chamber 92.
  • the gas is separated from the liquid and solids in the multi cyclones 93 and the gas is gathered in the gas compartment 99 above the cyclones before exiting through the gas outlet nozzle 97.
  • the liquid and solids falls down into the liquid compartment 94 of the vessel where the liquid and solids are removed through nozzle 90.
  • the solids may be removed in separate flushing lines if it settles in the bottom of the vessel.
  • the cyclone body 96 will often have a conical section towards the liquid outlet 100.
  • the conical shape of the liquid outlet will help transport liquid out of the cyclone.
  • the rotational field inside the cyclone creates a centrifugal acceleration usually several decades higher than gravity acceleration.
  • the high centrifugal field will set up pressure gradients that are oriented radially with respect to the cyclone axis. Any liquid film on the inside of the cyclone in the conical section will then be transported by the pressure gradients towards the center of the cyclone and the liquid outlet 100.
  • the main challenge using the multi cyclone inlets are the high pressure drop.
  • the high pressure drop is caused by the layout of the cyclone itself being a reversed cyclone.
  • the pressure drop in the cyclone will occur when the gas is accelerating through the small vortex finder 97. There will both be an acceleration axially but also tangentially due to conservation of angular momentum.
  • the high pressure drop will be handled by physically separating the separator into three volumes.
  • the pressure in the inlet section 92 will be higher than the pressure in the liquid compartment 94 that will be higher than the pressure in the gas compartment 99.
  • the high pressure drop will also represent a challenge with respect to the separation performance. Separation efficiency will be a balance between the separation due to centrifugal acceleration and re entrainment and droplet break up due to viscous drag.
  • the high pressure drop indicates high viscous drag and reduced efficiency.
  • FIG 8 shows an example of a formerly known inlet section that uses the inlet pipe as cyclone as described in i.e Norwegian patent No. 321170.
  • the inlet section is mounted as an extension of the inlet pipe.
  • the number of cyclones and orientation will hence be limited by the piping layout.
  • the cyclone performance will be a balance between necessary centrifugal accelerations to assure droplet separation and the pressure drop you can accept across the device. An high pressure drop across the unit will reduce the efficiency due to increased shear on the liquid film inside the cyclone.
  • the inlet section is a static swirl element that sets the incoming gas in rotation and the tangential velocity will be directly proportional to the axial velocity.

Abstract

L'invention concerne un dispositif d'entrée (17) pour un séparateur à gravité (18) pour séparer un mélange fluide comprenant un gaz et un liquide. Le dispositif d'entrée (17) comprend une buse d'entrée (1) pour le mélange fluide, une chambre de distribution (2) reliée à ladite buse d'entrée pour distribuer le mélange fluide à des plateaux à film (27) montés sur la partie supérieure d'une plaque de division (4) divisant le récipient en une section d'épuration inférieure (5) et une section de déshydratation (6), la plaque de division (4) constituant une partie intégrante du dispositif d'entrée (17) en étant reliée à la chambre de distribution.
PCT/NO2013/050064 2012-04-08 2013-04-05 Dispositif d'entrée pour des tours de déshydratation WO2013154436A1 (fr)

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NO20120414A NO335198B1 (no) 2012-04-08 2012-04-08 Innløpsinnretning for vannfjerningstårn for gass
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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2015105608A1 (fr) * 2014-01-08 2015-07-16 Exxonmobil Upstream Research Company Système et procédés de retrait de liquides entraînés
CN106085532A (zh) * 2016-07-22 2016-11-09 天津良华新能源科技有限公司 一种高效天然气净化装置

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN108970249A (zh) * 2018-08-27 2018-12-11 中国石油大学(华东) 一种基于轴流式旋风管的天然气气液分离装置及工艺方法

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2003074156A1 (fr) * 2002-03-05 2003-09-12 Statoil Asa Dispositif et procede permettant de traiter un melange gaz/liquide
WO2006132527A1 (fr) * 2005-06-10 2006-12-14 Fmc Technologies C. V. Système et dispositif d’entrée permettant de séparer un mélange

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2003074156A1 (fr) * 2002-03-05 2003-09-12 Statoil Asa Dispositif et procede permettant de traiter un melange gaz/liquide
WO2006132527A1 (fr) * 2005-06-10 2006-12-14 Fmc Technologies C. V. Système et dispositif d’entrée permettant de séparer un mélange

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2015105608A1 (fr) * 2014-01-08 2015-07-16 Exxonmobil Upstream Research Company Système et procédés de retrait de liquides entraînés
CN105899276A (zh) * 2014-01-08 2016-08-24 埃克森美孚上游研究公司 除去夹带液的系统和方法
US9597622B2 (en) 2014-01-08 2017-03-21 Exxonmobil Upstream Research Company System and methods for removing entrained liquids
AU2014376224B2 (en) * 2014-01-08 2017-04-13 Exxonmobil Upstream Research Company System and methods for removing entrained liquids
JP2017512121A (ja) * 2014-01-08 2017-05-18 エクソンモービル アップストリーム リサーチ カンパニー 同伴液体を除去するためのシステム及び方法
RU2627864C1 (ru) * 2014-01-08 2017-08-14 Эксонмобил Апстрим Рисерч Компани Система и способы удаления захваченной жидкости
CN106085532A (zh) * 2016-07-22 2016-11-09 天津良华新能源科技有限公司 一种高效天然气净化装置

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