Mass transfer columns and methods of construction

Abstract

A mass transfer column is provided in which a shell is formed from one or more sidewalls having an exoskeleton. The exoskeleton includes a plurality of vertical trusses joined together by intersecting rails. An inner skin is supported by the vertical trusses and rails and, together with the top and bottom of the shell, defines an open interior region in which the open interior region can be pressurized and in which a mass transfer process can be carried out. Horizontally extending beams, which may be in the form of trusses, span the open interior region and are supported by the exoskeleton. An interior structure, such as structured packing, can be supported on the horizontally extending beams.

Description

[Technical Field]

[0001] (Related Applications) This application claims priority to U.S. Provisional Patent Application No. 63 / 210,513, filed June 15, 2021, which is incorporated herein by reference in its entirety. [Background technology]

[0002] FIELD OF THE DISCLOSURE The present disclosure relates generally to mass transfer columns and methods for constructing mass transfer columns.

[0003] Mass transfer columns are used to separate a fluid into two or more product streams of specific compositions and / or temperatures. As used herein, the term "mass transfer column" is intended to encompass absorbers, separators, distillation columns, divided wall columns, liquid-liquid extractors, scrubbers, and evaporators, which facilitate heat and / or mass transfer between two or more fluid phases. Some mass transfer columns, such as those used in multicomponent absorption and distillation, are configured to contact a vapor phase and a liquid phase, while other mass transfer columns, such as extractors, are configured to contact two liquid phases of different densities.

[0004] Mass transfer columns are typically constructed from any of a variety of metals or metal alloys and have a cylindrically shaped shell defining an open interior region where the mass transfer process occurs. Various internals, such as trays, structured packing, random packing, or other mass transfer structures, support grids, downcomers, feed inlet devices, fluid collectors, and fluid distributors, may be present in the open interior region. These internals are typically supported directly or indirectly by the shell using support rings, bolting rods, and similar devices welded to the inner surface of the shell. Larger mass transfer columns often include beams that support the internals and are attached to seats that are welded to the inner surface of the shell.

[0005] The shell thickness must be selected to provide the strength necessary to withstand the various loads exerted on the shell by the internal structures, flowing fluids, and internal operating pressures. As the height and / or diameter of a mass transfer column increase, the loads exerted on the shell increase, requiring other methods to withstand these loads than simply increasing the thickness of the metal shell. For example, absorbers used to separate carbon dioxide from flue gases produced by fossil-fuel-based power plants can be 50 to 80 feet or larger in diameter. In some instances, the shells of such absorbers have been constructed using metal-reinforced concrete to provide the strength necessary to withstand the loads they experience. While metal-reinforced concrete can form high-strength shells, it poses challenges in providing a metal surface to which support rings, bolting rods, and beam seats can be welded. As a result, there remains a need for a method of fabricating shells that have suitable strength for use in mass transfer columns, especially those with large diameters, while allowing for easy attachment of support structures for the internal structures. Summary of the Invention

[0006] In one aspect, the disclosure relates to a mass transfer column comprising a shell having at least one sidewall and a top and a bottom joined to the sidewall. The sidewall of the shell comprises a plurality of spaced apart upright trusses having opposing inner and outer surfaces, rails extending between and joined to adjacent ones of the upright trusses and having opposing inner and outer surfaces, and a skin supported by the upright trusses and the rails and defining, together with the top and bottom, an open interior region, wherein the open interior region is pressurizable and capable of carrying out a mass transfer process, the skin having inner and outer surfaces. The mass transfer column further comprises a plurality of horizontally extending beams spanning the open interior region, each horizontally extending beam having opposing end segments, and a seat supported by the shell and supporting the opposing end segments of the horizontally extending beams.

[0007] In another aspect of the disclosure, the horizontally extending beam is a truss, and the mass transfer apparatus further comprises seats supported by the shell and supporting opposite end segments of the horizontally extending truss, and nozzles extending through the skin of the shell for introducing fluid into and expelling fluid from the open interior region.

[0008] In a further aspect, the present disclosure relates to an absorber for removing carbon dioxide from flue gas. The absorber includes a shell having at least one sidewall and a top and a bottom joined to the sidewall. The sidewall includes a plurality of upright trusses spaced apart from one another and having opposing inner and outer surfaces, rails extending between and joined to adjacent ones of the upright trusses and having opposing inner and outer surfaces, and a skin supported by the upright trusses and the rails, the skin defining, together with the top and bottom, an open interior region, the open interior region capable of being pressurized and undergoing a mass transfer process, the skin having an inner surface and an outer surface. The absorber further includes a plurality of horizontally extending trusses spanning the open interior region, each horizontally extending truss having opposing end segments, seats supported by the shell and supporting the opposing end segments of the horizontally extending trusses, nozzles extending through the skin of the shell for introducing fluid into and expelling fluid from the open interior region, and an interior structure supported on the horizontally extending trusses. [Brief explanation of the drawings]

[0009] The accompanying drawings form part of the specification, and like reference numerals are used to designate like elements in the various figures.

[0010] [Figure 1] FIG. 1 is a side perspective view of a mass transfer column constructed in accordance with an embodiment of the present disclosure. [Figure 2] FIG. 2 is a side perspective view of the mass transfer column shown in FIG. 1, with an exterior portion removed to show the internal details of the mass transfer column. [Figure 3] FIG. 3 is a side perspective view of the mass transfer column shown in FIGS. 1 and 2, but with more exterior portions removed than in the view shown in FIG. [Figure 4] FIG. 4 is a side elevation view of the mass transfer column shown in FIGS. 1-3, taken at a vertical cross section. [Figure 5] FIG. 5 is an enlarged side elevation view of a fragmentary portion of the mass transfer column of FIGS. 1-4, showing one embodiment of a seat for supporting the shell and horizontal beams in the form of a truss of the mass transfer column. [Figure 6] FIG. 6 is an enlarged side elevation view similar to that shown in FIG. 5, but showing a second embodiment of a seat for supporting the shell and horizontal beam of a mass transfer column. [Figure 7] FIG. 7 is an enlarged side elevation view similar to that shown in FIGS. 5 and 6, but showing a third embodiment of a seat for supporting the shell and horizontal beam of a mass transfer column. [Figure 8] 8 is an enlarged side elevation view similar to that shown in FIGS. 5-7, but showing a fourth embodiment of a seat for supporting the shell and horizontal beam of a mass transfer column. FIG. [Figure 9] FIG. 10 is a side elevation view of a support column that may be positioned within the open interior region of a mass transfer column and is shown supporting adjacent ends of aligned beam segments of a beam spanning the open interior region. [Figure 10] FIG. 10 is a side elevation view of a support column that may be positioned within the open interior region of a mass transfer column and is shown supporting adjacent ends of aligned beam segments of a beam spanning the open interior region. DETAILED DESCRIPTION OF THE INVENTION

[0011] Referring now more particularly to the drawings, and initially to Figures 1-4, a mass transfer column suitable for use in various mass transfer, heat exchange, and / or reaction processes is indicated generally by the numeral 10. Mass transfer column 10 may be located in any suitable type of processing facility, including, but not limited to, fossil fuel-based power plants, chemical processing plants, oil refineries, chemical manufacturing facilities, light hydrocarbon separation facilities, and the like.

[0012] The mass transfer column 10 can be any type of column for processing fluid streams, typically liquid and vapor streams, or two or more liquid streams having different densities, to obtain fractionation products or otherwise effect mass transfer and / or heat exchange between fluid phases. Examples of suitable types of mass transfer columns 10 include, but are not limited to, absorption columns, separators, distillation columns, liquid-liquid extraction columns, wash columns, and evaporation columns. The mass transfer column 10 can be one in which crude oil atmospheric fractionation, lube oil or crude oil vacuum fractionation, catalytic or thermal cracking fractionation, coker or visbreaker fractionation, coker or cracker scrubbing, nuclear off-gas scrubbing, gas quenching, edible oil deodorization, anti-pollution scrubbing, reactive distillation, or other types of processes occur.

[0013] As one specific example, the mass transfer column 10 may be an absorber used to remove carbon dioxide from flue gas generated by a fossil-fuel-based power plant. In such applications, the mass transfer column 10 may be used as part of a system that may include another mass transfer column that receives the flue gas after it has undergone a NOx removal process and cools the ascending flue gas by countercurrent flow with descending water through a mass transfer structure, such as structured packing. The cooled flue gas is then introduced as a side stream into the mass transfer column 10, which acts as an absorber. The ascending cooled flue gas flows countercurrently through the absorber with the descending carbon dioxide absorption solvent. The rich solvent is discharged as bottoms and introduced to one or more other mass transfer columns that act as strippers to separate carbon dioxide from the rich solvent stream and regenerate the solvent.

[0014] As shown in Figures 1-4, mass transfer column 10 includes a shell 12 having a square cross-sectional shape. Shell 12 may be oriented vertically, as shown in Figures 1-4, or horizontally (i.e., elongated). Other cross-sectional shapes, such as rectangular or other polygonal shapes, or circular shapes, are possible and may be used in place of the square cross-sectional shape shown in Figures 1-4. Shell 12 may be of any suitable dimensions, particularly adapted for use in large mass transfer columns 10. For example, in one embodiment, shell 12 may have a width in the range of 40 to 100 feet and a height in the range of 50 to 300 feet.

[0015] The shell 12 of the mass transfer column 10 defines an open interior region 14 in which desired mass transfer, heat exchange, and / or reaction between fluid phases occurs. In one embodiment, the fluid phases in the mass transfer column 10 can include ascending vapor and descending liquid, for example, when the mass transfer column 10 is acting as an absorber in a process for separating carbon monoxide from flue gas. In other embodiments, the fluid phases in the mass transfer column 10 can include virtually any combination of ascending or descending liquid and ascending or descending vapor. In some embodiments, the fluid phases in the mass transfer column 10 can include ascending or descending liquids having different densities. The fluid phases in the mass transfer column 10 can proceed in a cocurrent manner, such that the vapor and liquid phases, or both liquid phases, proceed in the same direction along the longitudinal axis of the mass transfer column 10, or the fluid flow in the mass transfer column 10 can proceed in a countercurrent manner, such that the vapor or liquid phase proceeds in the opposite direction to the other phase in the mass transfer column 10.

[0016] One or more fluid streams may be introduced into mass transfer column 10 through one or more feed lines, such as through feed line nozzles 16 and 18 shown in Figures 1-4. In some embodiments, mass transfer column 10 may include additional feed line nozzles (not shown) for introducing other fluid streams at one or more other locations. If the fluid streams to be contacted in mass transfer column 10 include a vapor stream or vapor phase, vapor may be introduced into mass transfer column 10 through feed line nozzle 16 (or another separate feed line nozzle), and / or all or a portion of the vapor phase may be generated within mass transfer column 10 during operation.

[0017] 1 , one or more fluid streams may be withdrawn from mass transfer column 10 through one or more withdrawal nozzles, shown as top (or overhead) withdrawal nozzle 20 and bottom (or bottom) withdrawal nozzle 22. In some embodiments, a vapor stream may exit mass transfer column 10 through top withdrawal nozzle 20, and a liquid stream may exit mass transfer column 10 through bottom withdrawal nozzle 22. For example, if mass transfer column 10 is operating as an absorber to remove carbon dioxide from flue gas, the treated flue gas with absorbed carbon dioxide is discharged through top withdrawal nozzle 20, and rich solvent containing carbon dioxide is discharged through bottom withdrawal nozzle 22.

[0018] Mass transfer column 10 may also include typical components such as one or more heat exchangers for heating and / or cooling fluid streams introduced into and / or withdrawn from mass transfer column 10, a condenser for cooling an overhead vapor stream withdrawn from mass transfer column 10 via upper withdrawal nozzle 20, and a reboiler for heating a bottoms liquid stream withdrawn from mass transfer column 10 via lower withdrawal nozzle 22. These components are not shown due to their conventional nature.

[0019] The shell 12 of the mass transfer column 10 has at least one sidewall 24 and a top 26 and a bottom 28 joined to the sidewall 24. The number of sidewalls 24 depends on the cross-sectional shape desired for the shell 12. For example, if the shell 12 has a circular cross-section, a single sidewall 24 may be used. If the shell 12 has a square or rectangular cross-section, four sidewalls 24 are used. Each sidewall 24 includes an exoskeleton 30 supporting an outer skin 32. In one embodiment, the exoskeleton 30 includes a plurality of spaced-apart upright trusses 34 and rails 36 connecting adjacent ones of the upright trusses 34 together. The upright trusses 34 and the rails 36 each have opposing inner and outer surfaces.

[0020] The upright trusses 34 may extend vertically in parallel relationship to one another. Each upright truss 34 may be formed by inner and outer chords 38, 40 spaced apart and interconnected by web members 42. The inner and outer chords 38, 40 within each upright truss 34 may extend in parallel relationship to one another, or, as shown in FIGS. 1-4 , the inner chords 38 may extend vertically and the outer core 40 may be angled upward toward the inner chord 38 because the load carried by the upright truss 34 decreases in the upright direction. The web members 42 may be arranged in any suitable manner to provide the strength necessary to withstand the load carried by the upright truss 34. In the illustrated embodiment, the web members 42 are arranged in a triangular configuration.

[0021] The skin 32 is supported by upright trusses 34 and rails 36 and, together with the top 26 and bottom 28, defines the open interior region 14 which may be pressurized and in which the mass transfer process occurs. The skin 32 has opposite inner and outer surfaces, and the side feed line nozzles 16 and 18 extend through the skin 32. The upper and lower withdrawal nozzles 20 and 22 typically extend through the top 26 and bottom 28 of the shell 12, respectively.

[0022] 2-4 , a plurality of horizontally extending beams 44 span the open interior region 14 and may be used to support various internal structures, such as the illustrated structured packing 46. The horizontally extending beams 44 may be trusses, as shown, each of which may include spaced apart upper and lower chords 48, 50, respectively, and interconnecting web members 52. The web members 52 may be arranged to form a triangular structure or other geometric structures capable of supporting the intended load. The horizontally extending beams 44 have opposing end segments 54 and 56 that, in one embodiment, are supported by seats 58, which in turn are supported by the shell 12 of the mass transfer column 10.

[0023] 5-8, different constructions of the sidewalls 24 are shown. In FIG. 5, the rails 36 are positioned so that their inner surfaces are in the same plane as the inner surfaces of the upright trusses 34, specifically the inner surfaces of the inner chords 38. The skin panels 32 are applied to the inner surfaces of the rails 36 and upright trusses 34, and the seats 58 are bonded to the inner surfaces of the skin panels 32. The seats 58 are positioned so that the horizontally extending beams 44 are supported on the top surfaces of the seats 58 and, in one embodiment, can roll along the top surfaces of the seats in response to thermal expansion and contraction of the horizontally extending beams 44. The seats 58 can be aligned with the upright trusses 34 or the rails 36, or can be positioned out of alignment with either the upright trusses 34 or the rails 36, providing greater flexibility in positioning the horizontally extending beams 44 within the open interior region 14. The rails 36 can be joined to the upright trusses 34 by bolting, welding, or other suitable means. Similarly, the skin 32 may be joined to the upright trusses 34 and / or rails 36, and the seats may be joined to the skin 32 by welding, bolting, or other means.

[0024] 6, the inner surfaces of the rails 36 are positioned inwardly from the inner surfaces of the upright trusses 34, and the skin plates 32 are applied to the inner surfaces of the rails 36. The seats 58 are joined to the rails 36 or the upright trusses 34, rather than to the skin plates 32, as shown in FIG. 5. Cutouts are provided in the skin plates 32 to accommodate each rail 36, and a seal weld is applied around each cutout to join the skin plates 32 to each seat 58.

[0025] In FIG. 7 , the rails 36 may be applied to the inner surfaces of the upright trusses 34 and span multiple trusses of the upright trusses 34. The skin 32 is applied to the inner surfaces of the rails 36 and is spaced from the inner surfaces of the upright trusses 34 by the thickness of the rails 36. The top surface of some or all of the rails 36 may serve as a seat 58 for the horizontally extending beam 44, such that the seat 58 includes a portion of the rail 36. In this embodiment, the horizontally extending beam extends through a cutout provided in the skin 32. Suitable means may be provided for sealing the skin 32 to the horizontally extending beam 44 while allowing for thermal expansion and contraction of the horizontally extending beam 44. In one embodiment, the skin 32 is seal-welded to the horizontally extending beam 44 using a more flexible material to accommodate thermal axial movement of the horizontally extending beam 44.

[0026] 8, horizontally extending beams 44 extend through skin 32 similar to the arrangement shown in FIG. 7, except that end segments of horizontally extending beams 44 may overlap and be joined to upright trusses 34. The remainder of the construction may be as described with reference to FIG. 8.

[0027] 9 and 10, one or more support columns 60 may be positioned within the open interior region 14 to provide support for the horizontally extending beam 44. Seats 62 are provided on the support columns 60 to support adjacent ends of the two beam segments 44a and 44b that form the horizontally extending beam 44. The support columns 60 may be of modular construction to facilitate insertion into the mass transfer column 10. In one embodiment, the support columns 60 are formed from segments that are bolted together using bolting flanges 64.

[0028] Thus, the use of exoskeleton 30 in the construction of sidewalls 24 provides shell 12 with increased strength capable of withstanding heavy loads, which proves particularly beneficial when mass transfer column 10 is used in applications where shell 12 has widths ranging from 40 to 100 feet and heights ranging from 50 to 300 feet. Fabricating skin 32, as well as vertical trusses 34 and rails 36, from metal or metal alloy provides great flexibility for positioning and attaching seats 58 for horizontally extending beams 44 within open interior region 14. Fabricating horizontally extending beams 44 as trusses allows horizontally extending beams 44 to span long distances and support various internal structures, such as structured packing 46, that may be used within mass transfer column 10.

[0029] From the foregoing, it will be seen that the present disclosure is one well adapted to attain all of the aims and objectives hereinabove set forth together with other advantages inherent therein.

[0030] It will be understood that certain features and subcombinations are of utility and may be employed without reference to other features and subcombinations, which is contemplated by the claims and is within the scope of the present invention.

[0031] Since many possible embodiments may be made from the present disclosure without departing from the scope of the present invention, it is to be understood that all matter set forth in this specification or shown in the accompanying drawings is to be interpreted as illustrative and not in a limiting sense.

Claims

1. A mass transfer column that is a packed tower, comprising: A shell including at least one sidewall, a top and a bottom joined to said sidewall, at least one feed line nozzle, at least one upper outlet nozzle, and at least one lower outlet nozzle, said sidewall comprising: a plurality of upright trusses spaced apart from one another and having opposing inner and outer surfaces; a rail extending between and joined to adjacent ones of the upright trusses, the rail having opposing inner and outer surfaces; and a shell including: a skin supported by connections to the upright trusses and the rails, the skin defining an open interior region together with the top and bottom, and having an interior surface and an exterior surface; a plurality of horizontally extending beams spanning the open interior region, each of the horizontally extending beams having opposing end segments; a seat supported by a joint to the shell and supporting the opposing end segments of the horizontally extending beam without joints; and an internal structure including structured packing supported on the plurality of horizontally extending beams; The open interior region is capable of carrying out a mass transfer process under normal or elevated pressure, in which a substance introduced into the interior through the feed line nozzle passes through the structured packing and is discharged from the upper and lower outlet nozzles.

2. the supply line nozzle extends through the skin of the shell to introduce fluid into the open interior region; 10. The mass transfer column of claim 1, wherein the upper and lower withdrawal nozzles are provided for discharging fluid from the open interior region.

3. 10. The mass transfer column of claim 1, wherein the horizontally extending beam is a truss.

4. 10. The mass transfer column of claim 1, wherein the seat is bonded to the outer skin of the shell.

5. 10. The mass transfer column of claim 1, wherein the seat is a portion of the rail.

6. 10. The mass transfer column of claim 1, wherein the seat is joined to the inner surface of the upright truss.

7. 2. The mass transfer column of claim 1, wherein the end segments of the horizontally extending beams are joined to the upright trusses.

8. Further comprising a support column; 2. The mass transfer column of claim 1, wherein each of the horizontally extending beams comprises a beam segment supported by the support column positioned within the open interior region such that two adjacent ends of the beam segment are aligned end-to-end.

9. A mass transfer column that is a packed column, comprising: A shell including at least one sidewall, a top and a bottom joined to said sidewall, at least one feed line nozzle, at least one upper outlet nozzle, and at least one lower outlet nozzle, said sidewall comprising: a plurality of upright trusses spaced apart from one another and having opposing inner and outer surfaces; a rail extending between and joined to adjacent ones of the upright trusses, the rail having opposing inner and outer surfaces; and a shell including: a skin supported by connections to the upright trusses and the rails, the skin defining an open interior region together with the top and bottom, and having an interior surface and an exterior surface; a plurality of horizontally extending trusses spanning the open interior region, each of the horizontally extending trusses having opposing end segments; a seat supported by a joint to the shell and supporting the opposing end segments of the horizontally extending truss without joints; and an internal structure including structured packing supported on the plurality of horizontally extending beams; The open interior region is capable of carrying out a mass transfer process under normal or elevated pressure, in which a substance introduced into the open interior region through the supply line nozzle is moved through the structured packing and discharged from the upper and lower outlet nozzles; the supply line nozzle extends through the skin of the shell to introduce fluid into the open interior region; A mass transfer column, wherein the upper and lower withdrawal nozzles are configured to discharge fluid from the open interior region.

10. 10. The mass transfer column of claim 9, wherein the seat is bonded to the outer skin of the shell.

11. 10. The mass transfer column of claim 9, wherein the seat is a portion of the rail.

12. 10. The mass transfer column of claim 9, wherein the seat is joined to the inner surface of the upright truss.

13. 10. The mass transfer column of claim 9, wherein the end segments of the horizontally extending trusses are joined to the upright trusses.

14. Further comprising a support column; 10. The mass transfer column of claim 9, wherein each of the horizontally extending trusses comprises a segment whose two adjacent ends are supported end-to-end by the support column positioned within the open interior region.

15. 1. An absorber for removing carbon dioxide from a flue gas, the absorber being a packed tower, the absorber comprising: A shell including at least one sidewall, a top and a bottom joined to said sidewall, at least one feed line nozzle, at least one upper outlet nozzle, and at least one lower outlet nozzle, said sidewall comprising: a plurality of upright trusses spaced apart from one another and having opposing inner and outer surfaces; a rail extending between and joined to adjacent ones of the upright trusses, the rail having opposing inner and outer surfaces; and a shell including: a skin supported by connections to the upright trusses and the rails, the skin defining an open interior region together with the top and bottom, and having an interior surface and an exterior surface; a plurality of horizontally extending trusses spanning the open interior region, each of the horizontally extending trusses having opposing end segments; a seat supported by a joint to the shell and supporting the opposing end segments of the horizontally extending truss without joints; and an interior structure supported on the plurality of horizontally extending trusses; The open internal region is capable of carrying out a material transfer process under normal pressure or pressure, in which a material introduced into the open internal region through the supply line nozzle is moved through the internal structure and discharged from the upper and lower outlet nozzles; the feed line nozzle extends through the skin of the shell to introduce the flue gas and carbon dioxide absorption solvent into the open interior region; an absorber, wherein the upper outlet nozzle is provided for discharging treated flue gas having carbon dioxide absorbed therein from the open interior region, and the lower outlet nozzle is provided for discharging rich solvent containing carbon dioxide from the open interior region.

16. 16. The absorber of claim 15, wherein the internals comprise structured packing.

17. 16. The absorber of claim 15, wherein said shell comprises four of said side walls joined together to form a square or rectangular configuration.

18. The absorber of claim 15 , wherein the horizontally extending trusses overlap the upright trusses.

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