A vessel

Abstract

The present disclosure relates to a vessel having inner and outer walls that are constructed of concrete materials, in which the outer wall is arranged about the inner wall so as to define a contact chamber therebetween. The contact chamber has multiple contact beds arranged one above the other. The vessel includes a distribution device located in an upper section of each contact bed that supplies solvent solution to the upper section of the contact beds and a gas stream follows upwardly in the beds in counter current. The vessel also includes a drainage device in at least one of the contact beds has from which all or part of the solvent solution and, if present a solid precipitant phase, can be discharged from the vessel.

Description

A VESSELRELATED APPLICATION

[0001] The present application claims priority to Australian provisional application number 2023901980 filed on 23 June 2023, the full of which are hereby incorporated into the present specification.FIELD OF THE PRESENT INVENTION

[0002] The present invention relates to a vessel having an absorber section in which a solvent solution is contacted with a gas stream to absorb an acid gas such as carbon dioxide and producing a solvent solution rich in the acid gas. The gas stream may be, but is by no means limited to, a flue gas stream of a fired powered station.

[0003] Optionally, according to one embodiment, the vessel may have a desorber section in which the acid gas is desorbed from the solvent solution to produce a pure acid gas stream and a recirculating solvent stream lean in the acid gas in a closed solvent loop.BACKGROUND OF THE INVENTION

[0004] The capture of acid gas such as carbon dioxide from flue gas streams is important in reducing greenhouse gas emissions to mitigate global climate change. However, devising equipment and building equipment for removing carbon dioxide from flue gas streams, particularly power plant flue gas streams that produce in the order of 3000 t / day of carbon dioxide is a technical and economic challenge. The main reasons attributable to this are: technical and economic costs associated with scaling up conventional absorption columns (often called absorbers) and desorption columns (often called desorbers, strippers or regenerators) that are conventionally constructed in stainless steel; limited equipment parameters including: diameters, available shell and plate sizes for heat exchangers such as reboilers and condensers; and maldistribution of fluid mediums in the absorption and desorption columns.

[0005] The present invention is aimed at providing an alternative vessel.SUMMARY OF THE INVENTION

[0006] An embodiment of the present invention relates to a vessel having an absorber section in which a solvent solution is contacted with a gas stream to absorb an acid gas from the gas stream, the vessel includes:an inner side wall having a first cross-sectional dimension and an outer side wall having a second cross-sectional dimension, the outer side wall being arranged about the inner side wall so as to define a contact chamber of the absorber section between the inner side wall and the outer side wall, the contact chamber has multiple contact beds arranged one above the other, wherein the inner side wall and the outer side wall have a concrete materials construction; each contact bed has a distribution device located in an upper section of each contact bed that supplies solvent solution to the upper section of the beds, wherein the distribution device extends in a direction between the outer side wall and the inner side wall, the distributor device includes apertures that discharge the solvent solution about the upper section of the contact beds; and at least one of the contact beds has a drainage device from which all or part of the solvent solution and, if present a solid precipitant phase, can be discharged from at least one of the contact beds, the drainage device has a surface extending between the inner side wall and the outer side wall, wherein the surface has convolutes defined by crests and valleys so that the solvent solution and the solid precipitant phase, if the solid precipitant phase is present, can flow from the valleys to a discharge outlet for discharging from the absorber section.

[0007] Throughout this specification the term "concrete materials construction", or variations thereof, includes structural ceramic materials, geo-polymer materials such as aluminosilicate materials, mineral polymer materials, ceramic and refractory materials, and cement containing materials.

[0008] The concrete materials constructions of the inner side wall and the outer side wall may have steel reinforcement bars embedded therein. The concrete materials constructions of the inner side wall and the outer side wall may have steel reinforcement externally of concrete materials.

[0009] It is possible that the inner and outer side walls may have any geometric horizontal crosssection including rectangular, square and circular shapes including circles and elliptical shapes that have a dimension, diameter or width.

[0010] The inner and outer side walls may be cylindrical so that the contact chamber is a ring between the inner and outer side walls.

[0011] The inner and outer side walls may be concentric and the contact chamber may have an annular cross-section.

[0012] The diameters of the inner and outer wall will be such to create a minimum space between the outside diameter of the inner wall and the inside diameter of the outer wall of sufficient size to allow for maintenance access. For example, the spacing may be from 0.5 to lm. A minimum spacing of at least lm is preferred for maintenance. Suitably the inner side wall may have an outside diameter of at least 2m, and suitably and outer side wall may have an inside diameter greater than 4m to 35m, or optionally 4m to 25m.

[0013] Suitably the outer side wall may have an inside diameter that is in the range of 2 to 25m larger than the outside diameter of the inner side wall. For example, when the inner side wall has an outer diameter of approximately 3.5m, the inner diameter of the outer side wall may be in the range of 5.5 to 28.5m. In another example, when the inner side wall has an outer diameter in the range of 3.5 to 8m, the inner diameter of the outer side wall may be in the range of 5.5 to 33m creating a distance between the inner and outer walls of between 0.5m to 14.75m, or suitably lm to 14.75 m.

[0014] The distributor device includes a distributor pipe extending a direction from the outer side wall toward the inner side wall, and branch pipes extending laterally from the distributor pipes, the distributor pipes conveys solvent solution to the branch pipes, and the branch pipes and / or the distributor pipes may include the apertures for discharging the solvent solution about the upper section of the contact beds. In another example, only the branch pipes may have the apertures.

[0015] The distributor pipe may be a manifold for supplying the solvent solution to the branch pipes.

[0016] The distributor pipe may extend in a direction from the outer side wall toward the inner side wall.

[0017] In one example, the distributor pipe may extend through the outer side wall at an upper region of each bed. In one example in which the distributor pipes extend through an aperture in the outer side wall, and a fluid tight sealing member is located between the distributor pipe and the outer side wall. In another example, the distributor pipe extends through an aperture in the outer side wall, and a fluid tight sealing member is located about the distributor pipe and connected to the outer side wall.

[0018] The sealing member may have a close-fitting sleeve through which the distributor pipe extends and a flange extending outwardly from the sleeve that can abut against the outer side wall to provide a seal. In one example, one of the sealing members may be positioned on the outside of the outer side wall. In another example, one of the sealing members may be positioned on theinside of the outer side wall. In yet another example, one of the sealing members may be positioned on the outside of the outer side wall and another sealing member may be positioned on the inside of the outer side wall.

[0019] The sealing member may be constructed of any suitable material, such as rubber, plastic, silicone or any suitable gasketing material. Ideally the sealing member is a rubber.

[0020] The branch pipes make extend laterally in opposite directions away of the distributor pipe.

[0021] In one example, the branch pipes may be linear. In another example the branch pipes may be curved. In the situation in which the contact chamber has an annular cross-section, the curvature of the branch pipes may match the curvature of the annular cross-section.

[0022] Each bed may have multiple distributor pipes. The distributor pipes may be arranged to extend toward a centre of the vessel. In the situation in which the contact chamber has an annular cross-section, the distributor pipes may be arranged radially to extend toward a centre of the vessel.

[0023] In another example, the distributor pipe may extend upwardly from the base of the vessel, being on the inside of the vessel, to the upper region of each contact bed. In this instance, it may not be necessary for the distributor pipe to extend through the outer side wall.

[0024] An outwardly facing surface of the inner side wall and an inwardly facing surface of the outer side wall may include a liquid impermeable membrane. The liquid impermeable membrane may be any one or a combination of: paint such polyester paint, a polymeric membrane, or a rubber membrane including synthetic or natural rubber materials.

[0025] In one example, the inner and outer side walls may be constructed using any technique. In one example, falsework scaffolding may be assembled in one or more stages to define the inner and outer side wall and steel reinforcement, typically ribbed rebar may be assembled within the boundaries of the walls and pre-welded if necessary. A concrete mix is then poured into the falsework which is removed once the wall becomes self-supporting. Once constructed the surfaces of the wall are solely or predominately concrete. That is to say, the inner and outer walls can be constructed of concrete materials.

[0026] In another example, the inner and outer side walls may include precast slabs that have been assembled one top on top of the other in a height direction and adjacently disposed about the perimeter of the inner and outer side walls. Steel beams may interconnect the precast slabs at predetermined levels that align with the upper and bottom sections of each bed.

[0027] The longitudinal axes of the crests and valleys may extend in a direction between the inner side walls and the outer side wall.

[0028] The valleys may be interconnected by a gutter so that the solvent solution and the solid precipitant phase, if the solid precipitant phase is present, can flow from the valleys into the gutter, and the gutter is connected to a discharge outlet for discharging from the absorber section.

[0029] All of the contact beds, except for the lowermost contact bed may have the drainage device including the convolute surface extending between the inner side wall side wall. The lowermost bed may have a sump arranged under the bed from which the solvent solution and the solid precipitant phase, if the latter is present, can be discharged from the vessel.

[0030] The valleys may be interconnected so that the solvent solution and the solid precipitant phase, if the latter is present, can flow from a plurality of the valleys and be discharged from the vessel via one of the discharge outlets.

[0031] The crests and valleys of the convolute surface may be arranged in a radial direction from the centre of the vessel. Suitably, the inner and outer side walls are arranged concentrically, and the crests and valleys are arranged radially from a centre of the vessel.

[0032] In one example, the base of the valleys may slope downwardly in a direction toward the outer side wall and the discharge outlet may be arranged through the outer side wall. In the situation in which the gutter interconnects the valleys, the gutter may be located adjacent to the outer side wall, such as an inner surface of the outer side wall.

[0033] In another example, the base of the valleys may slope downwardly in a direction toward the inner side wall and the discharge outlet may extend downwardly on an inner face of the inner side wall. In the situation in which a gutter interconnects the valleys, the gutter may be located adjacent to an outer surface of the inner side wall.

[0034] The drainage device may also include a planar surface that is arranged adjacently to the convolute surface. In one example, the height of the convolutes, from the base of the valleys to the peak of the crests may be of any suitable height depending, for example, on the size and density of the precipitants. In one example, the height of the convolutes, from the base of the valleys to the peak of the crests may be up to 0.5m, and suitably in the range of 0.1m to 0.5m, and even more suitably in the range of 0.2 to 0.4m. The length of a cycle of the convolutes, such that distance between the peaks of adjacent crests will vary. In one example, the length of the cycle adjacent to the inner wall may be in the range of 0.3m to 5.0m, and suitably 0.3m to 2.5m, and even more suitably 0.3m to 1.5., and even more suitably 0.3m to 1.2m. The length of the cycle adjacent to theouter wall may be in the range of 0.5m to 12.5m, suitably 1.2m to 12.5m and even more suitably 1.5m to 12.3m.

[0035] In one example, the crests and valleys of the convolute surface may reduce in size in a direction toward the planar surface. That is to say, the height of the crests and valleys may reduce in amplitude to create a nominally planar surface. Such cases are suitably applied where no solids are present in the solvent being used in the process.

[0036] The drainage device may include gas ducts or chimneys extending above the convolute surface and / or the planar surface. The gas dusts or chimneys may be located on the crests of the convolute surface that allow the gas stream to enter the beds. In one example the chimneys 21 may have a height in the range of 0.1m to 0.5m and suitably 0.2 to 0.4m.

[0037] The drainage device may have openings that allow the solvent solution to pass directly to the bed below. The openings may be located in the valleys and / or the gutter of the plate. In other words, not all of the solvent solution needs to be discharge from discharge outlet in order to pass to the bed below.

[0038] At least one of the beds may be segmented by at least one partition extending in an upright plane between the inner side wall and the outer side wall which divide the contact chamber into separate compartments. The compartments may be of equal or unequal size.

[0039] In one example, two or more of the beds may be segmented by 2 or more partitions to divide each compartment into multiple compartments.

[0040] In another example, the beds are segmented by four partitions to divide each bed into four compartments. All of the beds may be segmented by four partitions. In other examples, the beds may be segmented by three, five, six, seven or eight partitions to divide each bed into a corresponding number of the compartments.

[0041] The segmentation of the beds allows for one or more compartments to be isolated from the gas stream and so accommodate lower than nominal gas stream flow rates while maintaining the appropriate ratio of solvent solution flow rate to feed gas flow rate. Providing two of the partitions creating two equal sized compartments will allow for a reduction of gas feed of 50% if one compartments was isolated from the other. If four of the partitions were used to create four equal sized compartments this would allow for a stepwise reduction in gas feed rate of 25%, 50% or 75% depending on whether one, two or three compartments are isolated at any time. Creating more than four compartments would allow for increased granularity in the selection of lower gas feed rate. The use of three of the partitions creating three equal sized compartments would allow for areduction in feed gas rate of 33% or 66% depending on whether one or two compartments are isolated.

[0042] Ideally, the partitions extend the effective height of the vessel so that the compartments of the beds arranged one above the other are aligned.

[0043] The vessel may have a first controller that controls the flow of the gas stream to the compartments of the lowest bed. The first controller may operate valves and other flow mechanisms to adjust the flow rate. In the instance where the available flow of the gas stream reduces below a threshold, the first controller may stop the flow rate of the gas stream to one or more of the compartments.

[0044] The beds may contain fluidizable objects. The objects may be hollow plastic, spherical or irregularly shaped plastic balls. Examples of suitable fluidizable objects, pressure drops and so forth are described in International patent application PCT / AU2016 / 051103 (WO2017 / 083917) filed 16 November 2016, which is hereby incorporated by express reference.

[0045] The objects may be maintained in a fluidised state by the gas stream being conveying upward in the bed at a gas flow rate (G) and the solvent solution flow downward in the bed at a liquid flow rate (L).

[0046] The beds are ideally maintained in a fluidised state, and ideally the beds are maintained in a turbulent state.

[0047] The vessel may include a recirculating pipe in which the discharge outlet from the drainage device of the bed is flow connected to the distributor device of the same bed. That is to say, the recirculating pipe conveys a recirculating stream of solvent solution from the discharge outlet to the distributor device of the same bed without regeneration of the solvent solution.

[0048] In the situation in which the bed is segmented into the compartments, the recirculating pipe for each compartment interconnects the discharge outlet and the distributor device of the same compartments of the same bed.

[0049] The vessel may also include a down-flow pipe that flow connects the discharge outlet of one of the beds above to the distributor device of one of the beds below, suitably the bed immediately below. In other words, the down-flow pipe provides a inter bed solvent stream from the bed above to the bed below, or respective compartments of the beds.

[0050] The vessel may also include a second controller that controls flow from the solvent solution in the recirculating pipe and the down-flow pipe of each bed, or each compartment of each bed.

[0051] The L / G ratio of each bed, or each compartment, is the total liquid flow being a sum of the recirculating stream of the bed and the down-flow supplied to the bed from above, to the total gas flow through the bed.

[0052] The drainage device of the bottom bed in the vessel may have a main discharge outlet that discharges a loaded solvent from the vessel.

[0053] The vessel may include a cooling device within one or more of the contact beds to negate the heats of absorption and heat of precipitation, if the latter is present. In one example, the cooling device may include tubes arranged in the contact chamber, with a liquid coolant circulating inside. In one example the tubes may be arranged vertically. In another example, the cooling device may include welded plates with a cold fluid circulating between pairs of the plates. In yet another example, the cooling device may include a heat exchanger comprising spirally wound plates in which a cold fluid is circulated on one side of the plate. In each style of exchanger, the fluidizable objects are on the outside of the tubes or plates and said tubes or plates are configured so as not to restrict the turbulent action of the fluidizable objects.

[0054] The recirculating stream may be cooled by an external cooling device. Use of external cooling device may be carried out in conjunction with, or as an alternative to the cooling device of the vessel.

[0055] The vessel may include multiple gas inlets in the lower section of the vessel for supplying the gas stream. The vessel may have ducting that is progressively shaped from the largest cross- sectional area at the discharge of the fan or blower to a smaller cross-sectional area at the furthest- most point of entry to the vessel.

[0056] In one example, the duct may have a single toroid from the outlet of the fan or blower and wrap fully around the whole perimeter of the vessel.

[0057] In another example, the duct may have two toroidal shaped ducts extending about the vessel in opposite directions. A benefit in using two ducts is that the pressure drop in the ducts is reduced and the power required to operate the fan or blower is reduced.

[0058] The inner side wall of the vessel may define a desorber section that is arranged inwardly of the inner wall.

[0059] The desorber section may include: (i) an upper inlet that is arranged below an upper section of the desorber section, the upper inlet supplying loaded solvent solution into the desorber section, (ii) a lower outlet in a bottom section of the desorber section that discharges a stream of leansolvent solution, (iii) an upper outlet in the upper section of the desorber section that discharges a stream of recovered acid gases from the desorber section, (iv) a reboiler in the bottom section of the desorber section, the reboiler providing energy that volatilises acid gas from the solvent solution, and (v) a condenser in the upper section that condenses solvent solution and / or water.

[0060] In one example, the condenser may have a number of tubes arranged vertically through which a cold fluid is circulated or a pack of welded plates, wherein a cold fluid circulates inside pairs of plates.

[0061] In another example, the condenser may have spirally wound or flat plates in which a cold fluid is circulated on one side of the plate and the vapours are condensed or partially condensed on the other side of the plates.

[0062] The reboiler may have plate construction in which a hot fluid, preferably steam, is circulated between pairs of plates or an exchanger comprised of spirally wound or flat plates in which the hot fluid is circulated on one side of the plate heating of the liquid solvent takes place on the other side.

[0063] An embodiment of the present invention relates to a vessel having an absorber section in which a solvent solution is contacted with a gas stream to absorb an acid gas from the gas stream, the absorber section includes: an inner side wall having a first cross-sectional dimension and an outer side wall having a second cross-sectional dimension, the outer side wall being arranged about the inner side wall so as to define a contact chamber between the inner side wall and the outer side wall, the contact chamber has multiple contact beds arranged one above the other, wherein the inner side wall and the outer side wall are constructed from concrete materials; each contact bed has an upper liquid distribution device that supplies solvent solution across the upper section of the beds, wherein the distribution device has a distributor pipe extending in a direction between the outer side wall and the inner side wall and branch pipes extending laterally from the distributor pipe, the distributor pipe conveys solvent solution to the branch pipes and at least the branch pipes have apertures that discharge the solvent solution about the upper section of the contact beds; and at least one of the contact beds has a lower drainage device from which all or part of the solvent solution and, if present a solid precipitant phase, can be discharged from a bottom section of at least one of the contact beds, the drainage device has a plate extending between the inner side wall and the outer side wall, wherein the plate has convolutes defined by crests and valleys that have a length extending in a direction between the inner side wall and theouter side wall, and the valleys are interconnected by a gutter so that the solvent solution and the solid precipitant phase, if present, can flow from the valleys into the gutter, and the gutter is connected to a discharge outlet for discharging from the absorber section

[0064] An embodiment of the present invention relates to a method of operating the vessel described herein, in which the method includes the steps of:(a) supplying the gas stream to a gas feed inlet below the lowest bed in the absorber section and conveying the gas stream upwardly through the beds;(b) supplying the solvent solution across the upper region of the beds using the liquid distribution device;(c) discharging a partially loaded solvent from the contact beds, and using at least a portion of the partially loaded solvent as the solvent solution in step (b) to a bed below; and(d) discharging a gas stream relatively leaner in the acid gas from above the upper region of the absorber section.

[0065] The method may also include recirculating part of the (partially loaded) solvent stream, herein referred to as the circulating stream, back to the liquid distribution device of the same bed from which the solvent has been discharged.

[0066] The method may include controlling the flow rate of the gas stream supplied to the compartment of the beds, and in turn, control the gas flow rate through each bed. The gas flow rate can differ for each bed for various reasons including, absorption of the acid gas into the solvent solution in the bed, changes in water vapour pressure in the gas stream and so forth.

[0067] The method may include controlling the flow rate of the solvent solution supplied to each bed from the bed above, and in the case of the upper bed, a regenerated solvent solution.

[0068] The method may include dividing the solvent solution of the discharge outlet of each bed into the recirculating stream and the down-flow stream, and in turn control the total liquid flow in each bed, being a sum of the recirculating stream supplied to the bed and the down-flow supplied to the same bed from the bed above. The method includes controlling the liquid to gas ratio (L / G) of each of the beds.

[0069] The method may include cooling at least one of the recirculating streams using an external cooling device.

[0070] The method may include operating a cooling device in the absorber section to negate heat of absorption and precipitation.

[0071] In the situation in when the inner side wall also defines a desorber section, the method may include supplying steam to a reboiler located in a bottom section of a desorber section.

[0072] In addition, the method may also include supplying a cooling medium to a condenser located in an upper section of the desorber section.

[0073] The method may include any one or a combination of the features of the absorber section and the desorber section described herein. Similarly, the absorber section and the desorber section may include any one or a combination of the features of the method described herein.BRIEF DESCRIPTION OF THE DRAWINGS

[0074] A preferred embodiment of the present invention will now be described with reference to the company figures which may be summarised as follows.

[0075] Figure 1 is a schematic cross-sectional view in a vertical plane through the centre of a vessel comprising an inner side wall and an outer side wall arranged, in which the inner and outer side walls have a cylindrical formation and form an absorber section having an annular contact chamber therebetween. The annular contact chamber has three fluidised beds arranged one above the other.

[0076] Figure 2 is a schematic plan view of a liquid distribution device positioned at the top of a fluidised bed in a compartment that is a quarter of the annular chamber shown in Figure 1.

[0077] Figure 3A is a schematic plan view of a drainage device positioned at the bottom of at least the top and middle turbulent beds shown in Figure 1. Figure 3B is cross-sectional view of the drainage device along the line represented by the arrows in Figure 3A. The drainage device being arranged to discharge solvent solution, and if present a solid precipitant phase, from the lower region of the beds.

[0078] Figures 4B and 4B are schematic cross-sectional views of part of the outer side wall shown in Figures 2 and 3 having piping extending through the side wall. The piping in Figures 4A and 4B have a circular and square cross-section respectively, and may represent a distributor pipe of the liquid distribution device in Figure 2, or a discharge outlet of the drainage device of Figure 3.

[0079] Figure 5 is a schematic cross-section view along the line X-X of the vessel shown in Figure 1 illustrating the inner and outer side walls and partition walls extending between the inner and outer side walls. All other features of the vessel have been omitted for clarity.

[0080] Figure 6 is a schematic cross-sectional view in a vertical plane through the centre of a vessel with an absorber section and a desorber section arranged concentrically. The vessel may have any of the features shown in Figures 2 to 5. The desorber section receives the loaded solvent solution and has a steam reboiler and condenser within the structure of the desorber section.DETAILED DESCRIPTION

[0081] A preferred embodiment will now be described in the following text which includes reference numerals that correspond to features illustrated in the accompanying Figures. Where possible, the same reference numeral has been used to identify the same features in the Figures. However, to maintain the clarity of the Figures all reference numerals are not included in each Figure.

[0082] Figure 1 illustrates a vessel 9 having an absorber section 10 in which a solvent solution is contacted with a feed gas stream 41 to absorb an acid gas such as carbon dioxide producing a load solvent 43 rich in acid gas. Figure 6 illustrates the vessel 9 as also having a desorber section 11 in which the acid gas is desorbed from the solvent 43 to produce a recovered high purity acid gas 44 and a recirculating solvent 42 lean in the acid gas in a closed solvent loop. The vessel 9 is predominantly fabricated using cement materials and has wetted parts coated in a coating that protect the cement materials from attack by any solvent used in the process. Typical coatings may include an appropriate selection of thin metal or plastics coatings and linings i.e., paint such as polyester paint, a polymeric membrane, or a rubber membrane including synthetic or natural rubber materials.

[0083] In Figure 1 the gas stream and solvent solution flow in counter current in the absorber section 10. Specifically, a feed gas stream 41 containing an acid gas species is fed into the bottom of the absorber section 10 and flows upwardly, whilst a lean solvent 42 is fed to the top of the absorber section 10 and flows downwardly under gravity. A product gas 40 that is lean in acid gas can be vented from the top of the absorber vessel 9 and, ideally, the absorber vessel 9 is operated at atmospheric pressure and has an open top so that the product gas 40 can be vented directly to atmosphere. A loaded solvent 43 is discharged from the bottom of the absorber vessel 9 and regenerated in the desorber section 11, as shown in Figure 6.

[0084] The vessel 9 has an inner cylindrical side wall 12 and an outer cylindrical side wall 13 that are concentrically arranged and define an annular contact chamber 33 therebetween that is defined in the absorber section 10. The inner and outer side walls 12 and 13 are constructed of concrete materials with internal steel rebar reinforcement. The annular contact chamber 33 has a bottomwall that interconnects the inner side wall 12 and the outer side wall 13. The inner side wall 12 may also define a desorber section 11 on the inside of the side wall 12, further details of which are described with reference to Figure 6 below.

[0085] Although not shown in Figure 1, the vessel 9 may be mounted on supports, skirts, plinths or pedestals above the ground to allow access to a bottom wall and to allow a bottom section of the desorption section 11 to extend below the absorber section 10 as shown in Figure 1.

[0086] The diameter of the inner side wall 12 is a function of several variables including flowrate of the solvent 42 and feed gas 41. The diameter of the inner side wall 12 may be any suitable diameter, for instance, equal to or greater than 2m and have a height of equal to or greater than 15m. In some examples, the diameter of the inner side wall may be in the range of 2 to 20m and have an internal height may be in the range of 40 to 50m. The outer side wall 13 may have an inside diameter ranging from 4m to 35m, or optionally 4m to 25m. Suitably the outer side wall 13 may have an inside diameter ranging from 2 to 25m larger than the outside diameter of the inner side wall 12.

[0087] Likewise, the diameter of the outer side wall 13 is a function of several variables including the flowrate and acid gas concentration of the gas stream from any industrial emissions, such as, but not limited to, a flue gas stream of a fired power station, and the flowrate of the solvent solution. The flue gas flow rate of a 500 MW power station is typically in the range of 2000 and 3000 t / hr, and has a content of, for example, 71% (by mass) of nitrogen gas and 22% (by mass) of carbon dioxide, and smaller amounts of water vapour and un-combusted oxygen. An example of a solvent solution is a potassium carbonate at a content of 30 w / w% with a lean loading ~ 0.225 ([HCO3-] / [K+] ) would be used in the absorber section 10. The required mass flow rate of liquid absorbent to scrub the flue gas of a 500MW a power station is in the order of 15,000 to 16,000 t / hr. In addition, the diameter of the outer side wall 13 is selected to control the residence time of the solvent solution and the gas stream in the contact chamber 33, and achieve turbulence flow within the contact chamber 33.

[0088] With reference to Figure 1 the contact chamber 33 comprises three turbulent fluidised beds 26 that are arranged one above the other, each having an annular configuration between the inner and outer side walls 12 and 13. The beds 26 may contain any suitable form of packing to enhance the contact area between the solvent solution and the gas stream. The packing will be retained in the beds 26 and the solvent solution, including a precipitate if present, will flow through beds 26 to fluidise the packing and create turbulent contact. In the case of the preferred embodiment, the packing comprises mobile or fluidisable objects which may have some buoyant properties. The objects may be hollow plastic, spherical or irregularly shaped plastic balls. The primary objects mayhave any suitable size, for example, a diameter in the range of 5 to 50mm, and suitably 10 to 50mm, or even more suitably from 30 to 50mm. The diameter may be an equivalent diameter determined by the square root of the surface area (SA) of the primary objects divided by "pi" according the formula ^SA / TI . The primary objects may have a density in the range of 40 to 500 kg / m3, and suitably in the range of the range of 50 to 300 kg / m3.

[0089] Figure 1 illustrates the turbulent beds 26 in an inoperative mode with no gas stream flow and no solvent solution flow, as shown by the mottled pattern, which represents the primary objects collapsed on top of each other. Figure 1 also illustrates the fluidised beds 26 in an operative mode in which the primary objects are randomly dispersed over the height of the beds 26, which is represented by the three separate X-indica.

[0090] The annular contact chamber 33 of the absorber section 10 is segmented by partitions 14 extending from the inner side wall 12 to the outer side wall 13, See Figures 1, 2, 3A and 5. In the case of Figure 5, four partitions 14 divide the absorber section 10 into quadrants of equally sized compartments 15. It will be appreciated that any number of the partitions 14 can be arranged to divide the annular contact chamber 33 into multiple compartments 15 of equal or unequal proportions. In any event, ideally the partitions 14 extend the height of the absorber section 10, or at least over the height of the turbulent beds 26 so that the compartments 15 of the fluidised beds 26 align one above the other. Figure 5 is a cross-section of the vessel 9 shown in Figure 1 on the line X-X, and other than the inner and outer side walls 12, 13 and the partitions 14, all other features have been omitted for clarity.

[0091] Figure 2 is a plan view of a liquid distribution device 16 above the expanded height of one of the compartments 15 of the turbulent fluidised beds 26. The liquid distribution device 16 may have the same arrangement above each compartment 15. All other features have been omitted for clarity. The liquid distribution device 16 supplies solvent solution across the upper sections of the beds 26 and has a distributor pipe 17 extending through the outer side wall 13 toward the inner side wall 12. Ideally the distributor pipe 17 is arranged on a radius of a centre of the inner side wall 12. Branch pipes 18 extend laterally from the distributor pipe 17 to increase coverage across the top section of the segments of the beds 26. The distributor pipe 17 and branch pipes 18 have downwardly facing apertures (not shown in Figure 2), for instance in the form of circular holes or slots for distributing the solvent solution. If required, a spray nozzle may be fitted to the apertures to further increase the coverage of the liquid distribution device 16.

[0092] Figure 2 illustrates three distributor pipes 17 in one compartment 15 that covers one quarter of the contact chamber 33. Depending on the size of the compartments 15 any number ofdistributor pipes 17 can be provided. Although not illustrated in Figures, the liquid distribution device 16 about the beds 26 can be interconnected to a common supply of solvent solution. For instance, a supply of regenerated or lean solvent solution can be supplied to the liquid distribution device 16 of the compartments 15 of the uppermost turbulent bed. The liquid distribution device 16 of the fluidised bed beneath the uppermost fluidised bed, namely a middle bed can receive a supply of solvent solution from a discharge outlet of the upper most turbulent bed 26 by a first down-flow pipe 29. Similarly, the liquid distribution device 16 of the bottom turbulent bed 26 can receive a supply of solvent solution from a discharge outlet 25 of the middle bed 26 by a second down-flow pipe 29.

[0093] Figures 3A is a plan view of a drainage device 19 located in the bottom section of the compartments 15 of each of the turbulent beds 26, except for the bottom turbulent bed 26, and Figure 3B is a cross-sectional view of the drainage device along the line of the arrows shown in Figure 3A. The drainage device 19 comprises an arch-shaped surface comprising a plate 20 having an outer radius and an inner radius that conforms to the curvature of the inner surface of the outer side wall 13 and the outer surface of the inner side wall 12 respectively. The surface of the plate 20 has convolutes defined by crests 22 and valleys 23 that extend from the inner side wall 12 toward the outer side wall 13 and a gutter formation 24 that interconnects the valley formations 23. The gutter formation 24 is disposed adjacent to the inner surface of the outer side wall 13 and an outlet discharge pipe 25 extends from a sump of the gutter formation 24 through the outer side wall 13. The drainage device 19 may have openings 50, see Figure 3B, that allow the solvent solution to pass directly to the bed below. The openings 50 may be located in the valleys 23 and / or the gutter formation 24 of the plate 20. The height of the convolutes, from the base of the valleys to the peak of the crests may be of any suitable height depending, for example, on the size and density of the precipitants. In one example, the height of the convolutes, from the base of the valleys to the peak of the crests may be up to 0.5m, and suitably in the range of 0.1m to 0.5m, and even more suitably in the range of 0.2 to 0.4m. The length of a cycle of the convolutes, such that distance between the peaks of adjacent crests will vary, and when the desorber section 11 is an annulus that is concentrically arranged, the length of the cycle may increase as the radius from a centre of the concentric arrangement increases. In one example, the length of the cycle adjacent to the inner wall may be in the range of 0.3m to 5.0m, and suitably 0.3m to 2.5m, and even more suitably 0.3m to 1.5., and even more suitably 0.3m to 1.2m. The length of the cycle adjacent to the outer wall may be in the range of 0.5m to 12.5m, suitably 1.2m to 12.5m and even more suitably 1.5m to 12.3m.

[0094] The lines of gas vapour chimneys 21 are arranged on the crests 22 which allow the passage of the gas stream from below the turbulent bed 26 to enter the bed 26 and bubble upwardly. Thegas stream from one compartment 15 of the turbulent bed 26 below can pass upwardly and through the chimneys 21 of the plate 20 of the turbulent bed 26 located above in the direction of flow of the gas stream. The height of the chimneys 21 will depend on factors such as the degree of the mixing in the turbulent beds 26. In one example the chimneys 21 may have a height in the range of 0.1m to 0.5m and suitably 0.2 to 0.4m.

[0095] In the situation in which the solvent solution comprises an alkali carbonate absorbent, the solvent solution will absorb carbon dioxide and form bicarbonate. The bicarbonate can remain dissolved or precipitate under specific conditions. The convolutes of the surface of the plate 20 are configured to assist in directing the precipitate, if present, and solvent solution at the bottom of the turbulent bed 26 downwardly into the valleys 23 and then into the gutter 24. The height of the crests and valleys may reduce to zero for some applications where potential concerns about solids deposition are not present.

[0096] The solvent solution discharged from uppermost and middle fluidised beds 26 may be subject to a liquid / solid separation step (not illustrated) in the event that precipitates are formed.

[0097] A portion of the liquid solvent solution from the discharge outlet 25 of each of the turbulent beds 26 can be recirculated back to the liquid distribution device 16 of the same bed 26 by a recirculation pipe 28 as shown in Figure 1 and a recirculation pump (not shown).

[0098] Figures 4A and 4B are detailed cross-sectional views of two possible configurations of the outer side wall 13 having the distributor pipe 17 or the discharge outlet pipe 25 extending therethrough. As can be seen, the outer side wall 13 has a liquid impermeable membrane 27, such as a rubber membrane that covers the inner surfaces of the contact chamber 33 and extends through openings formed in the outer side wall 13 for the pipes 17, 25. In addition, the liquid impermeable membrane 27 extends about outer surfaces outer side wall 13. A grommet 32 comprising a sleeve and flange is positioned about the pipe and a band clamp (not illustrated) can be fitted about the sleeve to form a liquid tight seal around the pipe. In addition, fasteners can be used to attach the flange of the grommet to the outer side wall 13. Although Figures 4A and 4B illustrate a gap between the flange of the grommet and the impermeable membrane 27, this gap would be closed and a liquid tight seal would be formed when the fastener is installed. A suitable clearance, for instance 5 to 10 mm, can be provided between the pipes and the liquid impermeable membrane extending through the openings to minimise abrasion. Figure 4A represents a circular pipe extending through the outer side wall 13, whereas Figure 4B represents a rectangular or square pipe extending through the outer side wall 13.

[0099] Although Figures 4A and 4B illustrate pipes 17 and 25 extending through the outer side wall 13, it will be appreciated that similar constructions can be used for other pipes extending through other walls of the vessel 9 including the bottom wall, the inner side wall 12, and a top wall if required.

[0100] The feed gas stream 41 is supplied to a bottom section of the absorber section 10. As described above, the contact chamber 33 can be segmented into multiple compartments 15 and it is desired that the gas stream be evenly distributed amongst the compartments 15. Alternatively, the flow rate of the gas stream and the solvent solution can be adjusted for each compartment 15.

[0101] The feed gas stream 41 is drawn from a source, and a fan or blower (not illustrated) is used to pressurise the feed gas stream 41 so that the gas stream flows upward through the absorber section 10 and the pressure drop imposed by the fluidised turbulent beds 26 and other internal appurtenances is overcome.

[0102] Ideally the absorber section 10 has a gas distributor device 48 for feeding the gas stream to the, or each compartment 15, of the contact chamber 33. The gas distributor device 48 comprises ducting or piping from the fan or blower in the shape of a toroid around the outside of the perimeter of the vessel 9 and supplied to multiple gas inlets to a bottom of the absorber section 10 below the lowest fluidised bed 26.

[0103] The ducting or piping is progressively shaped from the largest cross-sectional area at the discharge of the fan or blower to a smaller area at the furthest-most point of entry to the absorber section 10 as it is shaped around the perimeter of the absorber section 10.

[0104] The feed gas duct or pipe may comprise a single toroid from the outlet of the fan or blower and wrap fully around the whole perimeter of the vessel 9, but preferably will comprise a split system whereby the duct or pipe will be split at or near the fan or blower and two toroidal shaped ducts or pipes will be formed around the vessel 9 in opposite directions, for example on clockwise and anticlockwise directions. This split arrangement reduces the pressure drop in the duct or pipe thereby reducing the power required for the fan or blower.

[0105] As can be seen in Figures 1 and 6 the absorber section 10 may include a recirculating pipe 28 that interconnects the discharge outlet 25 to the distributor pipe 17 of the same bed. The recirculating pipe 28 conveys a recirculating stream of solvent solution from the discharge outlet 25 to the distributor pipe 17 without regeneration of the solvent solution.

[0106] In the situation in which the bed is segmented into the compartments 15, the drainage device 19 of each compartment 15 may be separate, and the liquid distribution device 16 of eachcompartment 15 may also be separate. The recirculating pipe 28 for each compartment 15 interconnects the discharge outlet 25 and the distributor pipe 17 of the respective compartments 15 of the bed 26.

[0107] The vessel 9 also has a down-flow pipe 29 the provides a solvent solution stream from the bed above to the bed below. In particular, the down-flow pipe 29 flow connects the discharge outlet 25 of the bed 26 above to the distributor pipe 17 of one of the beds 26 below. In addition, the vessel may have outlet pipes 49 for conveying a partially loaded solvent from one or more of the turbulent beds to the rich solvent 43.

[0108] The vessel 9 may also include a second controller that controls flow from the solvent solution in the recirculating pipe 28 and the down-flow pipe 29 of each bed, or each compartment 15 of each bed 26.

[0109] The L / G ratio of each bed 26, or each compartment 15 of the beds 26, is the total liquid flow being a sum of the recirculating stream flowing in recirculating pipe 28 of the bed and the down-flow supplied to same bed from above, to the total gas flow through the bed.

[0110] As illustrated in Figure 6, the inner side wall 12 of the vessel 9 may define a desorber section 11 in which the load solvent 43 can be regenerated by volatilising acid gases such as carbon dioxide from the solvent 43. The desorber section 11 may include: (i) an upper inlet toward an upper section of the desorber section 11 for supplying loaded solvent solution, (ii) a lower outlet in a bottom section of the desorber section 11 that discharges a stream of lean solvent 42, (iii) an upper outlet in the upper section of the desorber section 11 that discharges a stream of recovered acid gases 44 from the desorber section 11. The desorber section 11 may also include a reboiler 30 in the bottom section of the desorber section 11, the reboiler 30 providing energy that volatilises acid gas from the desorption solution, and (v) a condenser 31 that condenses desorption solution and / or water.

[0111] The reboiler 30 may have a tube or plate construction in which a hot fluid, preferably steam, is circulated through tubes or between pairs of plates or an exchanger comprised of spirally wound plates. A hot stream 46 of steam is supplied to reboiler 30 and a discharge stream 47 of steam is discharged.

[0112] The condenser 31 may have a number of tubes arranged vertically through which a cold fluid is circulated or a pack of welded plates in multiple configurations wherein a cold fluid, such as rich / loaded solvent 48 circulates inside said pairs of plates and is discharged as a warm rich / loaded solvent 45.

[0113] The condenser 30 can be supported by beams on the inside of the desorber section 11. In one example, the beams may span between, and extend into, the inner side wall 12. In another example, the beams may span between, and flush mounted to the inner side wall 12.

[0114] As the desorber section 11 may be operated under elevated pressure and at least a portion of the desorber section 11 below the condenser may be operated under elevated temperature conditions. An inside surface of the inner side wall 12 may be lined with heat and corrosion resistant material, such as stainless steel. If the operating temperature allows, the inside of the inner side wall may be lined with the polymeric materials or paint such as polyester paint, a polymeric membrane, or a rubber membrane including synthetic or natural rubber materials.

[0115] The term "stream" as used herein embraces both continuous streams, discontinuous stream, or discrete samples.

[0116] In the claims which follow, and in the preceding description, except where the context requires otherwise due to express language or necessary implication, the word "comprise" and variations such as "comprises" or "comprising" are used in an inclusive sense, i.e. to specify the presence of the stated features but not to preclude the presence or addition of further features in various embodiments of the apparatus and method as disclosed herein.

[0117] In the foregoing description of preferred embodiments, specific terminology has been resorted to for the sake of clarity. However, the invention is not intended to be limited to the specific terms so selected, and it is to be understood that each specific term includes all technical equivalents which operate in a similar manner to accomplish a similar technical purpose. Terms such as "front" and "rear", "inner" and "outer", "above", "below", "upper" and "lower" and the like are used as words of convenience to provide reference points and are not to be construed as limiting terms. The terms "vertical" and "horizontal" in the specification, including the claims, refer to orientations relative to the normal operating orientation.

[0118] Furthermore, invention has been described in connection with what are presently considered to be the most practical and preferred embodiments, it is to be understood that the invention is not to be limited to the disclosed embodiments, but on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the invention. Also, the various embodiments described above may be implemented in conjunction with other embodiments, for example, aspects of one embodiment may be combined with aspects of another embodiment to realize yet other embodiments. Further, each independent feature or component of any given assembly may constitute an additional embodiment.

[0119] For example, although not shown in the Figures the absorber section 10 may have a first cooling device within the beds 26 to negate the heat of absorption and any heat of precipitation, if the latter is present. In another example, a second cooling device may be arranged to cool the recirculating streams or the solvent solution stream fed to each of the liquid distribution device(s) 16.REFERENCE NUMERAL TABLE

Claims

CLAIMS1. A vessel having an absorber section in which a solvent solution is contacted with a gas stream to absorb an acid gas from the gas stream, the vessel includes: an inner side wall having a first cross-sectional dimension and an outer side wall having a second cross-sectional dimension, the outer side wall being arranged about the inner side wall so as to define a contact chamber of the absorber section between the inner side wall and the outer side wall, the contact chamber has multiple contact beds arranged one above the other, wherein the inner side wall and the outer side wall have a concrete materials construction; each contact bed has a distribution device located in an upper section of each contact bed that supplies solvent solution to the upper section of the contact beds, wherein the distribution device extends in a direction between the outer side wall and the inner side wall, the distributor device includes apertures that discharge the solvent solution about the upper section of the contact beds; and at least one of the contact beds has a drainage device from which all or part of the solvent solution and, if present a solid precipitant phase, can be discharged from at least one of the contact beds, the drainage device has a surface extending between the inner side wall and the outer side wall, wherein the surface has convolutes defined by crests and valleys so that a loaded solvent solution and the solid precipitant phase, if the solid precipitant phase is present, can flow from the valleys to a discharge outlet for discharging from the absorber section.

2. The vessel according to claim 1, wherein the inner side wall and the outer side wall are constructed from concrete materials and include steel reinforcement bars.

3. The vessel according to claim 1 and 2, wherein the inner and outer side walls are cylindrical so that the contact chamber is a ring between the inner and outer side walls.

4. The vessel according to any one of the preceding claims, wherein the inner and outer side walls are arranged concentrically and the contact chamber has an annular cross-section.

5. The vessel according to any one of the preceding claims, wherein the inner side wall has an outside diameter of at least 2m, and the outer side wall has an inside diameter greater than 4m to 35m, or optionally 4m to 25m.

6. The vessel according to any one of the preceding claims, wherein the outer side wall has an inside diameter that is in the range of 2 to 25m larger than the outside diameter of the inner side wall.

7. The vessel according to claim 6, wherein the inner side wall has an outer diameter in the range of 3.5 to 8m, and the inner diameter of the outer side wall is in the range of 5.5 to 33m, and creating a distance between the inner and walls of between 1 to 14.75m.

8. The vessel according to any one of the preceding claims, wherein the distributor device includes a distributor pipe extending a direction from the outer side wall toward the inner side wall, and branch pipes extending laterally from the distributor pipes, the distributor pipes conveys solvent solution to the branch pipes, and the branch pipes and / or the distributor pipes have the apertures for discharging the solvent solution about the upper section of the contact beds.

9. The vessel according to claim 8, wherein the distributor pipe extends through the outer side wall at an upper region of each bed.

10. The vessel according to claims 8 or 9, wherein the distributor pipe extends through an aperture in the outer side wall, and a fluid tight sealing member is located about the distributor pipe and connected to the outer side wall.

11. The vessel according to claim 10, wherein the sealing member has a close-fitting sleeve through which the distributor pipe extends and a flange extending outwardly from the sleeve that can abut against the outer side wall to provide a seal.

12. The vessel according to claim 11, wherein either, one of the sealing members is positioned on the outside of the outer side wall, one of the sealing members is positioned on the inside of the outer side wall, or one of the sealing members is positioned on the outside of the outer side wall and another sealing member is positioned on the inside of the outer side wall.

13. The vessel according to any one of the preceding claims, wherein an outwardly facing surface of the inner side wall and an inwardly facing surface of the outer side wall include a liquid impermeable membrane.

14. The vessel according to any one of the preceding claims, wherein the inner and outer side walls may be constructed using falsework scaffolding that define in one or more stages to define the inner and outer side wall and steel reinforcement, a concrete mix is then poured into the falsework which is removed once the wall becomes self-supporting.

15. The vessel according to any one of the preceding claims, wherein the inner and outer side walls include precast slabs that have been assembled one top on top of the other in a height direction and adjacently disposed about the perimeter of the inner and outer side walls.

16. The vessel according to any one of the preceding claims, wherein all of the contact beds, except for the lowermost contact bed, have the drainage device.

17. The vessel according to any one of the preceding claims, wherein the valleys of the convolutes of the drainage device are interconnected so that the solvent solution and the solid precipitant phase, if the latter is present, can flow from a plurality of the valleys and be discharged from the vessel via one of the discharge outlets.

18. The vessel according to any one of the preceding claims, wherein longitudinal axes of the crests and valleys extend in a direction between the inner side walls and the outer side wall, and the valleys are interconnected by a gutter so that the solvent solution and the solid precipitant phase, if the solid precipitant phase is present, can flow from the valleys into the gutter, and the gutter is connected to the discharge outlet for discharging from the absorber section.

19. The vessel according to any one of the preceding claims, wherein the crests and valleys of the convolute surface are arranged in a radial direction from the centre of the vessel.

20. The vessel according to any one of the preceding claims, wherein the valleys slope downwardly in a direction toward the outer side wall and the discharge outlet extends through the outer side wall.

21. The vessel according to any one of claims 1 to 19, wherein the valleys slope downwardly in a direction toward the inner side wall and the discharge outlet extends downwardly on an inner face of the inner side wall.

22. The vessel according to any one of the preceding claims, wherein the drainage device includes a planar surface that is arranged adjacently to the convolute surface.

23. The vessel according to any one of the preceding claims, wherein the drainage device includes gas ducts or chimneys extending above the convolute surface, in which the gas dusts or chimneys are located on the crests of the convolute surface that allow the gas stream to enter the beds.

24. The vessel according to any one of the preceding claims, wherein the drainage device includes openings that allow the solvent solution to pass directly to the bed below.

25. The vessel according to claim 24, wherein the openings are located in the valleys of the convolute surface.

26. The vessel according to any one of the preceding claims, wherein at least one of the beds is segmented by at least one partition extending in an upright plane between the inner side wall and the outer side wall which divides the contact chamber into separate compartments.

27. The vessel according to claim 26, wherein two or more of the beds are segmented by 2 or more partitions to divide each compartment into multiple compartments.

28. The vessel according to claim 26 or 27, wherein the beds are segments by four partitions to divide each bed into four compartments.

29. The vessel according to any one of claims 26 to 28, wherein the partitions extend the effective height of the vessel so that the compartments of the beds are arranged one above the other.

30. The vessel according to any one of claims 26 to 29, wherein the vessel includes a first controller that controls the flow of the gas stream to the compartments of the lowest bed, that is the first bed in the direction of flow of the gas stream, and when available flow of the gas stream reduces below a threshold, the first controller can stop the flow rate of the gas stream to one or more of the compartments.

31. The vessel according to any one of the preceding claims, wherein the beds include fluidizable objects.

32. The vessel according to any one of the preceding claims, wherein the vessel includes one or more recirculating pipes in which the discharge outlet from the drainage device of the bed is flow connected to the distributor device of the same bed, in which the recirculating pipe conveys a recirculating stream of solvent solution from the discharge outlet to the distributor device of the same bed without regeneration of the solvent solution.

33. The vessel according to claim 32 when appended to any one of claims 26 to 29, wherein the bed is segmented into the compartments, the recirculating pipe for each compartment interconnects the discharge outlet and the distributor device of the same compartments of the same bed.

34. The vessel according to any one of the preceding claims, wherein the vessel includes a down-flow pipe that flow connects the discharge outlet of one of the beds above to the distributordevice of one of the beds below, suitably the bed immediately below, in which the down-flow pipe provides a inter bed solvent stream from the bed above to the bed below.

35. The vessel according to claim 34 when appended to claim 32, wherein the vessel includes a second controller that controls flow of the solvent solution in the recirculating pipe and the downflow pipe of each bed.

36. The vessel according to any one of the preceding claims, wherein the drainage device of the bottom bed in the vessel has a main discharge outlet that discharges a loaded solvent stream from the vessel.

37. The vessel according to any one of the preceding claims, wherein the vessel includes a cooling device within one or more of the contact beds to negate the heats of absorption and, if present, heat of precipitation.

38. The vessel according to claim 32 or 33, wherein the vessel has an external cooling device for cooling the recirculating stream in the circulating pipe.

39. The vessel according to any one of the preceding claims, wherein the vessel includes multiple gas inlets in the lower section of the vessel for supplying the gas stream, and the vessel includes ducting connected to the multiple gas inlets, and the ducting is progressively shaped from the largest cross-sectional area at a supply end of the ducting to a smaller cross-sectional area at the furthest-most point of entry to the vessel.

40. The vessel according to any one of the preceding claims, wherein the inner side wall of the vessel defines a desorber section that is arranged inwardly of the inner wall.

41. The vessel according to claim 40, wherein the desorber section includes:(i) an upper inlet that is arranged below an upper section of the desorber section, the upper inlet supplying the loaded solvent solution into the desorber section,(ii) a lower outlet in a bottom section of the desorber section that discharges a lean solvent solution,(iii) an upper outlet in the upper section of the desorber section that discharges a recovered acid gases stream from the desorber section,(iv) a reboiler in the bottom section of the desorber section, the reboiler providing energy that volatilises acid gas from the solvent solution, and(v) a condenser in the upper section that condenses solvent solution and / or water.

42. A method of operating the vessel according to any one of the preceding claims, wherein the method includes the steps of:(e) supplying the gas stream to a gas feed inlet below the lowest bed in the absorber section and conveying the gas stream upwardly through the beds;(f) supplying the solvent solution across the upper region of the beds using the liquid distribution device;(g) discharging a partially loaded solvent from the contact beds, and using at least a portion of the partially loaded solvent as the solvent solution in step (b) to a bed below; and(h) discharging a gas stream relatively leaner in the acid gas from above the upper region of the absorber section.

43. The method according to claim 42, wherein the method includes recirculating part of the (partially loaded) solvent , herein referred to as the circulating stream, back to the liquid distribution device of the bed from which the solvent has been discharged.

44. The method according to claim 42 or 43, wherein the method includes controlling the flow rate of the gas stream supplied the beds, and in turn, control the gas flow rate through each bed.

45. The method according to any one of claims 42 to 44, wherein the method includes controlling the flow rate of the solvent solution supplied to each bed from the bed above, and in the case of the upper bed, a regenerated solvent solution supplied to the upper bed.

46. The method according to any one of claim 42 to 45, wherein the method includes dividing the solvent solution of the discharge outlet of each bed into the recirculating stream and the downflow stream, and in turn control the total liquid flow in each bed, being a sum of the recirculating stream supplied to the bed and the down-flow supplied to the same bed from the bed above.

47. The method according to any one of claims 42 to 46, wherein the method includes controlling the liquid to gas ratio (L / G) of each of the beds by controlling the flow rate of the gas stream supplied the beds, and in turn, control the gas flow rate through each bed, and by controlling the total liquid flow in each bed, being a sum of the recirculating stream supplied to the bed and the down-flow supplied to the same bed from the bed above.

48. The method according to any one of claims 42 to 47, wherein the method includes cooling at least one of the recirculating streams using an external cooling device.

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