EP2818820A1 - Schalen- und Rohrausrüstung mit einer Ablenkstruktur zum Tragen von Rohren - Google Patents

Schalen- und Rohrausrüstung mit einer Ablenkstruktur zum Tragen von Rohren Download PDF

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Publication number
EP2818820A1
EP2818820A1 EP13174267.8A EP13174267A EP2818820A1 EP 2818820 A1 EP2818820 A1 EP 2818820A1 EP 13174267 A EP13174267 A EP 13174267A EP 2818820 A1 EP2818820 A1 EP 2818820A1
Authority
EP
European Patent Office
Prior art keywords
tubes
slots
baffles
baffle
slot
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP13174267.8A
Other languages
English (en)
French (fr)
Inventor
Enrico Rizzi
Ermanno Filippi
Fabiano Montini
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Casale SA
Original Assignee
Ammonia Casale SA
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Ammonia Casale SA filed Critical Ammonia Casale SA
Priority to EP13174267.8A priority Critical patent/EP2818820A1/de
Priority to PCT/EP2014/063336 priority patent/WO2014207013A1/en
Publication of EP2818820A1 publication Critical patent/EP2818820A1/de
Withdrawn legal-status Critical Current

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Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F28—HEAT EXCHANGE IN GENERAL
    • F28D—HEAT-EXCHANGE APPARATUS, NOT PROVIDED FOR IN ANOTHER SUBCLASS, IN WHICH THE HEAT-EXCHANGE MEDIA DO NOT COME INTO DIRECT CONTACT
    • F28D7/00—Heat-exchange apparatus having stationary tubular conduit assemblies for both heat-exchange media, the media being in contact with different sides of a conduit wall
    • F28D7/16—Heat-exchange apparatus having stationary tubular conduit assemblies for both heat-exchange media, the media being in contact with different sides of a conduit wall the conduits being arranged in parallel spaced relation
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F28—HEAT EXCHANGE IN GENERAL
    • F28F—DETAILS OF HEAT-EXCHANGE AND HEAT-TRANSFER APPARATUS, OF GENERAL APPLICATION
    • F28F9/00—Casings; Header boxes; Auxiliary supports for elements; Auxiliary members within casings
    • F28F9/007—Auxiliary supports for elements
    • F28F9/013—Auxiliary supports for elements for tubes or tube-assemblies
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F28—HEAT EXCHANGE IN GENERAL
    • F28F—DETAILS OF HEAT-EXCHANGE AND HEAT-TRANSFER APPARATUS, OF GENERAL APPLICATION
    • F28F2265/00—Safety or protection arrangements; Arrangements for preventing malfunction
    • F28F2265/30—Safety or protection arrangements; Arrangements for preventing malfunction for preventing vibrations

Definitions

  • the invention relates to the field of shell-and-tube equipment comprising a vessel and a tube bundle, for example shell-and-tube heat exchangers or shell-and-tube chemical reactors.
  • the invention relates in particular to a baffle structure to support the tubes within the bundle.
  • the rod baffle design provides a precise guidance and support of tubes.
  • a disadvantage is the need to weld a large number of rod elements and related support rings.
  • Another disadvantage is that the conventional rod-baffle design calls for tubes with a square pitch, being unsuitable for a triangular layout pattern of tubes.
  • Another drawback of this prior art concerns the pressure drop of the shell side. In most cases, the shell side of the equipment is traversed by a heat exchange medium, such as condensing steam or a gas. It has been observed that the support means of the rod baffles induce a disturbance to the flow of said medium, affecting the overall coefficient of heat exchange.
  • US 2008/0245515 discloses a shell-and-tube device comprising slotted baffles having elongated parallel slots formed therein.
  • the elongated slots are sized to receive a certain number of aligned tubes.
  • Said slotted baffles can be made in a relatively cheap way, by cutting a metal sheet for example.
  • this embodiment has a disadvantage in that the thin strips of metal formed between the slots are prone to vibration and instability, especially under the severe stress occurring during a transitory, for example during a startup when hot gases cause a relevant thermal stress.
  • the thickness of the baffle is generally smaller than the width of said strips, making them unstable under mechanical stress (especially a compression stress) and unable to provide a firm support to the tubes.
  • the thickness of the metal sheet may be increased, which however increases also cost and weight and makes the cutting more difficult.
  • additional support means such as tie bars or reinforcing rings, which however require additional works inside the vessel, make the manufacturing process more difficult and more expensive and introduce a further source of disturbance for a gaseous medium traversing the shell side.
  • DE 10 2011 107 122 discloses a grid baffle layout where each one of the tubes passes through a respective four-sided window. Accordingly, the bundle is supported and guided in an effective manner, however a very precise construction and alignment of the baffles is necessary since each single tube must meet a corresponding small window of the baffle. Hence, assembly may result difficult or impossible due to tolerances of the tube bundle, especially when tubes have a considerable length, e.g. of some meters. Furthermore, this design causes a relevant pressure drop of the shell side, since the design of the baffles leaves a small passage area for the medium flowing in the shell side.
  • the problem underlying the invention is to provide a supporting structure for a bundle of tubes which overcomes the above drawbacks of the prior art, and in particular: provides a secure support against vibrations of tubes; allows using also a triangular layout of tubes; avoids an expensive realization, reduces to a minimum the negative influence on a gaseous medium flowing in the shell side of the equipment.
  • a shell-and-tube equipment comprising:
  • Said corner regions are to be intended as sharp corners or rounded (beveled) corner regions.
  • the slots have beveled corners to avoid their overlapping, for example with triangular slots.
  • slots designed to receive tubes with a triangular pitch have beveled corners, so that they actually have 6 sides, including three long sides and three short sides (chamfers) opposite to the long sides. Nevertheless, they are referred to as triangular slots, since they appear substantially as triangles.
  • the baffles are arranged according to a repetition of a pattern along a longitudinal direction of the bundle.
  • the slots of a generic baffle, according to said pattern are staggered relative to the slots of the adjoining baffles.
  • Said pattern hence comprises at least a first baffle and a second baffle, and the slots of the second baffle are staggered relative to the slots of the first baffle.
  • the baffles arranged according to said pattern provide a complementary support for each tube of the bundle.
  • a tube is prevented against a lateral displacement in a given direction X by the first baffle of the pattern, and is prevented against a displacement in another direction Y by the second or another baffle of the pattern.
  • a displacement of a tube in a certain direction is always prevented by at least one, or more, of the baffles forming the pattern.
  • the slots of a baffle of the pattern are staggered relative to the slots of the previous or next baffle in the pattern by a distance which is equal to the pitch of the tubes in the tube bundle.
  • the slots of adjoining baffles may be staggered relative to each other in one direction or in two directions.
  • An embodiment of the invention provides that the tubes are arranged according to a square pitch, and said baffles have square slots or, more generally, four-sided slots.
  • Each slot receives four tubes located at the four corner regions of the slot, and said pattern of the baffles is formed by a first baffle and a second baffle, which means that first baffles and second baffles are alternated.
  • the slots of the second baffles are staggered relative to the slots of the first baffle, by a distance equal to the pitch of the tubes, according to a first direction and a second direction in a plane perpendicular to the tubes.
  • the tubes have a triangular pitch
  • said baffles have triangular slots.
  • Each slot receives three tubes at the corner regions.
  • Preferably said slots are equilateral triangles.
  • the tubes have a triangular pitch
  • said baffles have hexagonal slots, each slot receiving six tubes at corner regions of the slot plus a seventh tube in the middle.
  • said equipment is a gas-gas heat exchanger.
  • the exchanger may also contain a catalyst in the tubes or in the shell side, if required.
  • a more preferred application of the invention relates to a reactor for the synthesis of ammonia.
  • An aspect of the invention is also a structure for supporting a tube bundle of a shell-and-tube equipment, according to the attached claims.
  • the tubes are guided and supported against vibrations in a way similar to a rod-baffle cage, but avoiding the drawbacks of the conventional rod-baffle design, including the large number of welded joints.
  • the slotted baffles of the invention may be prepared from metal sheets and with a technique such as cutting, laser cutting, water cutting or equivalent, reducing the number of the welded junctions.
  • Another advantage of the invention is that a pattern of only two different baffles can support the tubes in all directions, thanks to the tubes being received at the corner regions of the slots.
  • the rod-baffle design on the contrary, needs the repetition of a pattern of four different baffles, in order to achieve the same effect, since each set of the conventional rods acts in one direction only.
  • a further and important advantage is that the invention allows using a triangular pitch, while the rod-baffle design requires a square pitch. Tubes in a triangular pitch are closer each other, thus providing a better use of the available volume compared to the square pitch layout. For example when tubes are filled with a catalyst the triangular pitch provides more room for said catalyst. Hence, the heat exchanger is more compact and less expensive for a given duty.
  • the invention does not use elongated slots which may suffer vibrations or instability under stress. There is no need to increase the thickness of the sheet in order to keep the baffles from the above problems, or provide expensive additional support means.
  • the baffle structure according to the invention leaves a large passage area in the shell side, reducing the pressure drop. Furthermore, the applicant has noted the following advantage: the staggered slots avoid the formation of preferred "lanes" for the gaseous medium traversing the shell side. For example a gaseous flow line, after a passage through a slot of a generic baffle, impinges on the surface of the next baffle and is divided into a plurality of flow lines, passing through the slots of said next baffle. This effect provides for a certain mixing and, hence, a good heat exchange coefficient but, on the other hand, does not cause a high pressure drop. The applicant has found that the prior art solutions tend to generate helical flows or linear flows with contractions and expansions which are less preferable, since they increase the pressure drop and do not provide optimum heat exchange.
  • Another advantage of the invention is that the free space between the boundary of the bundle and the vessel is reduced to a minimum. This space does not contribute to the heat exchange; accordingly, the reduction of this free space means that the available internal volume of the equipment is best exploited.
  • each baffle provides a support for a tube according to two directions, leaving the tube free to flex to a certain extent in the other directions, to compensate for working tolerance.
  • the shell-and-tube equipment may comprise a central duct, e.g. to collect a medium flowing in the shell side, or for another purpose.
  • the tube bundle is arranged in the annular space between the central duct and the outer vessel, and the baffles are ring-shaped as a consequence.
  • the invention provides additional advantages.
  • a conventional rod-baffle design would need an inner ring as a support means for the rods.
  • the invention does not need this inner support ring, since the slotted baffle can be prepared, as above, by cutting a metal sheet of the desired shape, including a central aperture for the duct. Hence, the realization is simpler and less expensive.
  • Fig. 1 illustrates a shell-and-tube equipment 1 comprising a vessel 2, a bundle of tubes 3, a plurality of support baffles 4, 4a for supporting said tubes 3.
  • the tubes 3 are fixed to tubesheets 6.
  • the baffles are spaced each other by a suitable distance d.
  • the equipment 1 processes a first fluid flowing in the tubes 3 and a second fluid flowing in the shell side, which means around the tube bundle.
  • the first fluid (tube side) enters at 10 and leaves at 11, while the second fluid (shell side) enters for example at 12 and leaves at 13.
  • said first fluid and second fluid are gaseous, i.e. the equipment 1 is a gas-gas heat exchanger.
  • the equipment 1 may carry out a chemical reaction and to this purpose, it may contain a suitable catalyst.
  • the equipment 1 is a reactor for the synthesis of ammonia, where synthesis of ammonia takes place in the tube side.
  • Said support baffles 4, 4a are made of a metal sheet of a suitable thickness.
  • a number of slots are formed in the baffles, which are sized to receive a plurality of tubes 3 therethrough.
  • Fig. 2 shows an embodiment where tubes 3 are arranged according to a square pitch p, said pitch being the distance between centers of adjacent tubes (see Fig. 2 ) and the slots 5 are four-sided, e.g. square. Four tubes 3 are received at corner regions of each slot 5.
  • Fig. 2 also shows the slots 5' of a second baffle 4', next to said baffle 4 (see Fig. 1 ). Said slots 5' of the second baffle 4' are depicted with dotted lines and Fig. 2 shows they are staggered relative to the slots 5 of the first baffle 4.
  • baffles are arranged according to a pattern where first baffles 4 and second baffles 4' alternate, as shown in Fig. 1 . Hence, slots 5 and 5' of adjoining baffles are always staggered.
  • any generic tube such as tube 3* of Fig. 2
  • tube 3* of Fig. 2 is embraced by an upper corner of a slot 5 and a lower corner of an adjoining slot 5, and so on according to the pattern of alternate baffles 4, 4'.
  • a generic slot keep the tube from displacement in two directions, e.g. left and down, while the next slot keep the tube from displacement in the other two, e.g. right and up. Accordingly, the tube is secured against vibrations in all directions of plane X-Y.
  • Said slots 5 or 5' can be obtained by cutting, laser cutting or another technique, starting from a metal sheet of a suitable thickness.
  • Fig. 3 relates to an embodiment where tubes are arranged according to a triangular pitch.
  • the baffles 4, 4' have substantially triangular slots 5, 5', each slot 5 or 5' receiving three tubes 3 at the corners.
  • the slots 5, 5' in this embodiment appear to have six sides, namely three long sides 8 and three short sides 9; said short sides 9 however are formed by the beveled corners.
  • Each long side 8 is opposite to a short side 9, so that the shape of the slot globally resembles to a triangle. Accordingly, the slot is considered three-sided.
  • a pattern of only two different baffles 4, 4' can effectively support the tubes 3 in all directions, thanks to the fact that the tubes are received at the corner regions of the slots 5, 5'.
  • the conventional rod-baffle design on the contrary, needs the repetition of a pattern of four different baffles, in order to achieve the same effect, since each set of the conventional rods acts in one direction only.
  • Fig. 4 relates to an embodiment where the shell-and-tube equipment comprises a central duct 10 coaxial to the shell 2.
  • the tubes 3 are arranged in the annular region between the duct 10 and the outer shell 2, and the baffles 4, 4' are ring-shaped as a consequence.
  • Fig. 4 shows tubes with a square pitch but the same embodiment with central duct 10 may use triangular pitch as in Fig. 3 .
  • the invention is advantageous in that it does not need an inner ring for supporting the baffles.
  • the baffles have a sufficient thickness, also an outer ring may not be necessary.

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  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Thermal Sciences (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Heat-Exchange Devices With Radiators And Conduit Assemblies (AREA)
EP13174267.8A 2013-06-28 2013-06-28 Schalen- und Rohrausrüstung mit einer Ablenkstruktur zum Tragen von Rohren Withdrawn EP2818820A1 (de)

Priority Applications (2)

Application Number Priority Date Filing Date Title
EP13174267.8A EP2818820A1 (de) 2013-06-28 2013-06-28 Schalen- und Rohrausrüstung mit einer Ablenkstruktur zum Tragen von Rohren
PCT/EP2014/063336 WO2014207013A1 (en) 2013-06-28 2014-06-25 A shell and tube equipment with a baffle structure for supporting the tubes

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
EP13174267.8A EP2818820A1 (de) 2013-06-28 2013-06-28 Schalen- und Rohrausrüstung mit einer Ablenkstruktur zum Tragen von Rohren

Publications (1)

Publication Number Publication Date
EP2818820A1 true EP2818820A1 (de) 2014-12-31

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EP13174267.8A Withdrawn EP2818820A1 (de) 2013-06-28 2013-06-28 Schalen- und Rohrausrüstung mit einer Ablenkstruktur zum Tragen von Rohren

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EP (1) EP2818820A1 (de)
WO (1) WO2014207013A1 (de)

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP3115734A1 (de) * 2015-07-06 2017-01-11 Casale SA Rohrbündelausrüstung mit schwingungsdämpfenden sperren und zugehöriges montageverfahren

Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2393217A1 (fr) * 1977-03-15 1978-12-29 Westinghouse Electric Corp Systeme support de tubes
US4286366A (en) * 1977-12-23 1981-09-01 Phillips Petroleum Company Method for the construction of a baffled heat exchanger
US4342360A (en) 1980-10-31 1982-08-03 Phillips Petroleum Company Rod baffled heat exchanger
WO2003067170A1 (en) * 2002-02-05 2003-08-14 Shell Internationale Research Maatschappij B.V. Tube bundle
WO2005015108A2 (en) * 2003-08-06 2005-02-17 Shell Internationale Research Maatschappij B.V. Expanded metal
US20080245515A1 (en) 2006-10-06 2008-10-09 Exxonmobil Research And Engineering Company Reduced vibration tube bundle device having slotted baffles
DE102011107122A1 (de) 2011-07-12 2013-01-17 OHL Heat Technology & Services GmbH Unterstützung für Rohre in einem Rohrbündelwärmetauscher sowie Verfahren zur Herstellung einer solchen Unterstützung

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2393217A1 (fr) * 1977-03-15 1978-12-29 Westinghouse Electric Corp Systeme support de tubes
US4286366A (en) * 1977-12-23 1981-09-01 Phillips Petroleum Company Method for the construction of a baffled heat exchanger
US4342360A (en) 1980-10-31 1982-08-03 Phillips Petroleum Company Rod baffled heat exchanger
WO2003067170A1 (en) * 2002-02-05 2003-08-14 Shell Internationale Research Maatschappij B.V. Tube bundle
WO2005015108A2 (en) * 2003-08-06 2005-02-17 Shell Internationale Research Maatschappij B.V. Expanded metal
US20080245515A1 (en) 2006-10-06 2008-10-09 Exxonmobil Research And Engineering Company Reduced vibration tube bundle device having slotted baffles
DE102011107122A1 (de) 2011-07-12 2013-01-17 OHL Heat Technology & Services GmbH Unterstützung für Rohre in einem Rohrbündelwärmetauscher sowie Verfahren zur Herstellung einer solchen Unterstützung

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WO2014207013A1 (en) 2014-12-31

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