US3324838A - Vapor generating apparatus - Google Patents

Vapor generating apparatus Download PDF

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US3324838A
US3324838A US472287A US47228765A US3324838A US 3324838 A US3324838 A US 3324838A US 472287 A US472287 A US 472287A US 47228765 A US47228765 A US 47228765A US 3324838 A US3324838 A US 3324838A
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tubes
wall
walls
passageway
return bends
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US472287A
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Eilers Fritz
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Babcock International Ltd
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Babcock and Wilcox Ltd
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    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F22STEAM GENERATION
    • F22BMETHODS OF STEAM GENERATION; STEAM BOILERS
    • F22B37/00Component parts or details of steam boilers
    • F22B37/02Component parts or details of steam boilers applicable to more than one kind or type of steam boiler
    • F22B37/10Water tubes; Accessories therefor
    • F22B37/20Supporting arrangements, e.g. for securing water-tube sets
    • F22B37/202Suspension and securing arrangements for contact heating surfaces

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  • This invention relates to vapor generating apparatus, and more particularly to a construction thereof providing support for tubular walls separating flue gas passageways.
  • a disadvantage of such a division or partition wall is that, due to its large dirneusions and the pressure difference between fiues, it must withstand large pressure forces at temperatures in the range of l300- F., all of which tends to produce excess bending of the division wall and possible deterioration of the lateral wall-labyrinth packings.
  • the problem is further complicated by the requirement that any supporting structure for the division wall should not block the tube lanes so as to interfere with the effective operation of soot blowers employed for removing accumulations of soot and sintered particles from the tube surfaces.
  • the principal object of the present invention is to provide a simple, economical, and effective means for supporting or bracing such tubular division walls under the conditions set forth.
  • the parallel tubes comprising the heat exchangers in the downstream flue are arranged normal to the partition or division wall to be braced.
  • Groups of these tubes are connected together by rigid transverse structure, to be described, so that one or more of them will not fail due to buckling as a result of axial or endwise compression when bracing the division wall against the rear wall, or other suitable bearing surface.
  • a slidable connection with the transverse structure permits each of the grouped tubes to undergo longitudinal thermal expansion independent of the transverse connecting structure.
  • the division wall is not rigidly connected to the bracing structure, with the result that it has freedom to undergo expansion and contraction over its entire width and height.
  • bracing structure for a division wall can be provided at a very low cost and with a very small amount of additional material, since existing heat exchanger tubes form a major part of the bracing structure. This has the further advantage of consuming very little additional space, with the result that the tube lanes are left clear for effective operation of the soot blowers and the flow of flue gas.
  • FIG. 1 is a schematic illustration of vapor generating apparatus embodying the invention
  • FIG. 2 is an enlarged sectional view of a fragment of the apparatus of FIG. 1, taken from the downstream or third flue and showing the structural support for the division wall in detail;
  • FIG. 3 is a transverse sectional view through the supporting structure of the present invention.
  • the invention is applied to a vapor generating apparatus including a fuel firing component, such as a cyclone furnace 9, and also a flue gas passageway.
  • a fuel firing component such as a cyclone furnace 9
  • the latter conducts flue gas in the direction of the arrows in FIG. 1 and comprises a first flue or furnace chamber 10 leading to an open gas pass or second flue 11, and then to a convection pass or third flue 12.
  • the flues 11 and 12 extend vertically and are separated from each other by a depending, upright partition or division wall 13.
  • the division wall 13 is formed of upright, heat transfer tubes arranged side by side and joined together by welding to close the spaces between them and provide a rigid structure.
  • tubulous walls made up of heat transfer tubes lining the flues to provide radiation heating surfaces.
  • the third or downstream flue 12 contains a number of heat exchangers 14, i.e., superheaters, intermediate superheaters, etc. These heat exchangers 14 are disposed between the division wall 13 and a rear wall 15 to provide contact heating surfaces within the flue 12 for generating steam by convection heating.
  • heat exchangers 14 are disposed between the division wall 13 and a rear wall 15 to provide contact heating surfaces within the flue 12 for generating steam by convection heating.
  • the present invention employs, from the heat exchangers 14, selected banks or groups of long slender heat exchanger tubes 21 extending between the division wall 13 and the rear wall 15, at an attitude normal thereto, for bracing the division wall 13 against the rear wall 15 to thereby provide distributed resistance to the applied pressure forces, since the selected tubes 21 are at spaced locations on the Wall 13.
  • FIGS. 2 and 3 the bracing structure employing the heat exchanger tubes 21, as proposed by the invention, will now be described in detail. It will be noted that there is only a small clearance, amounting to a fraction of an inch, between the ends of the heat exchanger tubes 21 and the walls 13 and 15. As shown in FIG. 3, several tubes 21, preferably three or more, are connected together in spaced relationship by connecting members 16 and upright spacers 18 of flat steel which are welded to tube shackles or collars 17, as shown, are for the purpose of making the tubes so connected rigidly resistant to bending when placed in endWise compression.
  • a greater number than three tubes may be connected together, for example five, as is also shown in FIG. 3. Only tubes from adjoining rows should be connected together so that the temperature difference between tubes in a given group will be minimal. It is preferred that the shackles 17 be fitted to their respective tubes with sufficient looseness to permit longitudinal thermal expansion or differential movement of the tubes, for example, due to changes and differences in temperature between tubes in a group, while simultaneously preventing lateral outward bending. This provision is better than rigidly joining tubes together in a group by welding directly to the tube surfaces, since such construction could impose high stresses on the weld in the event of differential longitudinal movement of adjoining tubes.
  • hearing members 19 comprising channel members and/or bearing plates extending across the width of the flue 12 are interposed between each of the walls 13 and 15 and the ends of the tubes 21 to transmit the pressure force from division wall 13, through the members 19 at one end of the tubs 21, through the tubes 21 and the members 19 at the other end thereof, to the rear wall 15.
  • flat iron pieces 20 are inserted between nested neighboring tubes 21 at the laterally extending turns or return bends in the 'tubebank, at both ends of the tube bank to prevent unequal deflection at the tube turns which would result in an unequal distribution of the forces applied to the tube bank by the division wall 13. Clamps can be used instead of the flat pieces with equal effect. And, with the bearing members 19 and the flat iron pieces 20 unattached to the walls 13 and 15, the division wall 13 and the rear wall 15 are free to undergo thermal expansion without restraint.
  • Vapor generating apparatus comprising:
  • a tube bank in said second passageway comprising a multiplicity of elongated heat transfer tubes arranged means applying a pressure force to said partition wall in the direction of said bearing surface.
  • means including rigid members interposed between adjacent return bends and also interposed between said wall and the return bend at one end of said tube bank and between the return bend at the other end of said tube bank and said bearing surface for transmitting the pressure force on said partition wall through said tubes to said bearing surface whereby said tubes are placed in endwise compression,
  • Vapor generating apparatus comprising:
  • a furnace including a furnace chamber and a fuel firing component; wall structure defining vertically extending first and second passageways communicating with said furnace chamber and including an upright, depending partition Wall between said passageways and an upright bearing wall mutually facing said partition wall across said second passageway;
  • heat exchangers in said second passageway including a tube bank comprising a multiplicity of slender, fluid conducting tubes arranged normal to said partition wall and thence laterally at their ends to provide nested return bends with spaces therebetween; means for directing flue gas from said furnace chamber first through said first passageway and then through said second passageway whereby a greater gas pressure exists in said first passageway than said second passageway and a pressure force is applied to said partition wall in the direction of said bearing wall;
  • means including rigid members between adjacent return bends and also between said walls and the endmost return bends of said tube bank for transmitting the pressure force on said partition wall through said tubes to said bearing wall whereby said tubes are placed in endwise compression;
  • bracing structure for resisting buckling of said tubes comprising metal annuli on said tubes slidably fitted thereto, and
  • Vapor generating apparatus according to claim 3 wherein said fluid conducting tubes of said tube bank are free of attachment to said partition wall so that the latter is free to expand or contract over its width and height relative to said tubes.

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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)

Description

Filed July 15, 1965 FIQI INVENTOR. Friiz Eii'ers ATTORNEY United States Patent 3,324,838 VAPOR GENERATING AFPARATUS Fritz Eilers, Oberhausen Sterkrade, Nordrhein-Westfalen,
Germany, assignor to Babcock & Wilcox Limited, London, England, a corporation of Great Britain Filed July 15, 1965, Ser. No. 472,287 Claims priority, application Germany, July 17, 1964, D 44, 3 4 Claims. (Cl. 122-510) This invention relates to vapor generating apparatus, and more particularly to a construction thereof providing support for tubular walls separating flue gas passageways.
In modern large-scale vapor generators, sheet metal casings and tubular walls have displaced masonry walls. The walls inside a vapor generator are now made up of fluid-conducting tubes which are arranged side by side and joined together by welding to serve not only as walls or baffles but also as heat exchangers which participate in the vapor generation process. Of principal concern is the problem of bracing a depending tubular wall when it is employed to partition adjoining flues.
A disadvantage of such a division or partition wall is that, due to its large dirneusions and the pressure difference between fiues, it must withstand large pressure forces at temperatures in the range of l300- F., all of which tends to produce excess bending of the division wall and possible deterioration of the lateral wall-labyrinth packings. The problem is further complicated by the requirement that any supporting structure for the division wall should not block the tube lanes so as to interfere with the effective operation of soot blowers employed for removing accumulations of soot and sintered particles from the tube surfaces.
Thus, the principal object of the present invention is to provide a simple, economical, and effective means for supporting or bracing such tubular division walls under the conditions set forth.
According to the present invention, the parallel tubes comprising the heat exchangers in the downstream flue are arranged normal to the partition or division wall to be braced. Groups of these tubes are connected together by rigid transverse structure, to be described, so that one or more of them will not fail due to buckling as a result of axial or endwise compression when bracing the division wall against the rear wall, or other suitable bearing surface. A slidable connection with the transverse structure permits each of the grouped tubes to undergo longitudinal thermal expansion independent of the transverse connecting structure. Likewise, the division wall is not rigidly connected to the bracing structure, with the result that it has freedom to undergo expansion and contraction over its entire width and height.
It is a feature of the present invention that bracing structure for a division wall can be provided at a very low cost and with a very small amount of additional material, since existing heat exchanger tubes form a major part of the bracing structure. This has the further advantage of consuming very little additional space, with the result that the tube lanes are left clear for effective operation of the soot blowers and the flow of flue gas.
The various objects, features, and advantages of the invention will appear more fully from the detailed description which follows, taken in connection with the accompanying drawings forming a part of the present invention and in which:
FIG. 1 is a schematic illustration of vapor generating apparatus embodying the invention;
FIG. 2 is an enlarged sectional view of a fragment of the apparatus of FIG. 1, taken from the downstream or third flue and showing the structural support for the division wall in detail; and
FIG. 3 is a transverse sectional view through the supporting structure of the present invention.
The invention, as shown in the drawings, with particular reference to FIG. 1, is applied to a vapor generating apparatus including a fuel firing component, such as a cyclone furnace 9, and also a flue gas passageway. The latter conducts flue gas in the direction of the arrows in FIG. 1 and comprises a first flue or furnace chamber 10 leading to an open gas pass or second flue 11, and then to a convection pass or third flue 12. The flues 11 and 12 extend vertically and are separated from each other by a depending, upright partition or division wall 13. Preferably, the division wall 13 is formed of upright, heat transfer tubes arranged side by side and joined together by welding to close the spaces between them and provide a rigid structure. Also, there are tubulous walls made up of heat transfer tubes lining the flues to provide radiation heating surfaces.
The third or downstream flue 12 contains a number of heat exchangers 14, i.e., superheaters, intermediate superheaters, etc. These heat exchangers 14 are disposed between the division wall 13 and a rear wall 15 to provide contact heating surfaces within the flue 12 for generating steam by convection heating.
There is usually a pressure difference between the second flue 11 and the third fine 12, with the greater pressure being in the second flue 11. Consequently, a pressure force is applied to the division wall 13 in the direction of the rear wall 15, tending to impose large bending forces on the tubes and welded joints of the wall 13 in a region where the temperature of the flue gas is about 1300 F.
The present invention employs, from the heat exchangers 14, selected banks or groups of long slender heat exchanger tubes 21 extending between the division wall 13 and the rear wall 15, at an attitude normal thereto, for bracing the division wall 13 against the rear wall 15 to thereby provide distributed resistance to the applied pressure forces, since the selected tubes 21 are at spaced locations on the Wall 13.
Referring now especially to FIGS. 2 and 3, the bracing structure employing the heat exchanger tubes 21, as proposed by the invention, will now be described in detail. It will be noted that there is only a small clearance, amounting to a fraction of an inch, between the ends of the heat exchanger tubes 21 and the walls 13 and 15. As shown in FIG. 3, several tubes 21, preferably three or more, are connected together in spaced relationship by connecting members 16 and upright spacers 18 of flat steel which are welded to tube shackles or collars 17, as shown, are for the purpose of making the tubes so connected rigidly resistant to bending when placed in endWise compression.
A greater number than three tubes may be connected together, for example five, as is also shown in FIG. 3. Only tubes from adjoining rows should be connected together so that the temperature difference between tubes in a given group will be minimal. It is preferred that the shackles 17 be fitted to their respective tubes with sufficient looseness to permit longitudinal thermal expansion or differential movement of the tubes, for example, due to changes and differences in temperature between tubes in a group, while simultaneously preventing lateral outward bending. This provision is better than rigidly joining tubes together in a group by welding directly to the tube surfaces, since such construction could impose high stresses on the weld in the event of differential longitudinal movement of adjoining tubes.
With a pressure force applied to the division wall 13 in the direction of the rear or hearing wall 15, hearing members 19 comprising channel members and/or bearing plates extending across the width of the flue 12 are interposed between each of the walls 13 and 15 and the ends of the tubes 21 to transmit the pressure force from division wall 13, through the members 19 at one end of the tubs 21, through the tubes 21 and the members 19 at the other end thereof, to the rear wall 15. Also, flat iron pieces 20 are inserted between nested neighboring tubes 21 at the laterally extending turns or return bends in the 'tubebank, at both ends of the tube bank to prevent unequal deflection at the tube turns which would result in an unequal distribution of the forces applied to the tube bank by the division wall 13. Clamps can be used instead of the flat pieces with equal effect. And, with the bearing members 19 and the flat iron pieces 20 unattached to the walls 13 and 15, the division wall 13 and the rear wall 15 are free to undergo thermal expansion without restraint.
With the present arrangement, pressure forces from the division wall 13 are distributed and transmitted to the tubes 21 in the tube bank so as to place them in endwise compression, while the connecting pieces 16, spacers 18 and shackles 17 help to prevent buckling of the tubes 21. A group of slender tubes rigidly shackled together with elongated shackles 17 at spaced locations along their length can withstand a greater aggregate endwise compressive load without buckling than if the same tubes were completely free of attachment from one another, and the resulting structure has improved dimensional stability. If the load from the wall 13 is unevenly distributed on the tubes 21 the more highly compressed tubes will be braced against buckling by the transverse connection to the other tubes in the group; and in this way buckling forces are distributed to all tubes in the group.
While in accordance with the provisions of the statutes there is illustrated and described herein a specific embodiment of the invention, those skilled in the art will understand that changes may be made in the form of the invention covered by the claims, and that certain features of the invention may sometimes be used to advantage without a corresponding use of the other features.
What is claimed is:
1. In vapor generating apparatus, the combination with first and second flue gas passageways,
a first wall providing a partition between said passageways,
a second wall in mutually facing relationship with said first wall on opposite sides of said second passageway, and
a plurality of elongated, fluid conducting tubes in said second passageway and extending substantially normal to said walls and thence laterally at their ends to provide nested return bends with spaces therebetween,
of means for bracing said first wall against deflection toward said second wall, comprising:
rigid members between the endmost return bends of said tubes and said walls and in the spaces between adjacent return bends for transmitting deflection forces on said first wall longitudinally through said tubes to said second wall, and
means providing transverse structural rigidity to groups of said tubes comprising rigid elements connected between adjacent tubes of said group intermediate the ends thereof.
2. Vapor generating apparatus comprising:
a furnace chamber,
first and second passageways communicating with said furnace chamber,
an upright, depending partition wall between said passageways constructed of heat transfer elements,
an upright bearing surface mutually facing said partition wall across said second passageway,
a tube bank in said second passageway comprising a multiplicity of elongated heat transfer tubes arranged means applying a pressure force to said partition wall in the direction of said bearing surface.
means including rigid members interposed between adjacent return bends and also interposed between said wall and the return bend at one end of said tube bank and between the return bend at the other end of said tube bank and said bearing surface for transmitting the pressure force on said partition wall through said tubes to said bearing surface whereby said tubes are placed in endwise compression,
shackles for the respective tubes mounted thereon and movable longitudinally thereof, and
rigid elements extending transversely between adjacent shackles and joined thereto to provide transverse rigidity to said group of tubes for resisting buckling when subjected to compressive loading.
3. Vapor generating apparatus comprising:
a furnace including a furnace chamber and a fuel firing component; wall structure defining vertically extending first and second passageways communicating with said furnace chamber and including an upright, depending partition Wall between said passageways and an upright bearing wall mutually facing said partition wall across said second passageway;
heat exchangers in said second passageway including a tube bank comprising a multiplicity of slender, fluid conducting tubes arranged normal to said partition wall and thence laterally at their ends to provide nested return bends with spaces therebetween; means for directing flue gas from said furnace chamber first through said first passageway and then through said second passageway whereby a greater gas pressure exists in said first passageway than said second passageway and a pressure force is applied to said partition wall in the direction of said bearing wall;
means including rigid members between adjacent return bends and also between said walls and the endmost return bends of said tube bank for transmitting the pressure force on said partition wall through said tubes to said bearing wall whereby said tubes are placed in endwise compression;
and bracing structure for resisting buckling of said tubes comprising metal annuli on said tubes slidably fitted thereto, and
rigid metal connectors extending transversely between annuli associated in a group of said tubes and joined thereto to provide a rigid transverse connection between tubes in said group;
the construction and arrangement being such that when an endwise compressive load is applied to said tubes buckling is resisted by said tubes as a group.
4. Vapor generating apparatus according to claim 3 wherein said fluid conducting tubes of said tube bank are free of attachment to said partition wall so that the latter is free to expand or contract over its width and height relative to said tubes.
References Cited UNITED STATES PATENTS 1,894,692 l/l933 Kerr et al. 122-510 X 2,345,257 3/1944 Hensel et al. 122-510 2,714,877 8/1955 Andrew 122-510 X 3,055,348 9/196'2 Brash l22.51O 3,055,349 9/1962 Hamilton et al l225l0 CHARLES J. MYHRE, Primary Examiner.

Claims (1)

1. IN VAPOR GENERATING APPARATUS, THE COMBINATION WITH FIRST AND SECOND FLUE GAS PASSAGEWAYS, A FIRST WALL PROVIDING A PARTITION BETWEEN SAID PASSAGEWAYS, A SECOND WALL IN MUTUALLY FACING RELATIONSHIP WITH SAID FIRST WALL ON OPPOSITE SIDES OF SAID SECOND PASSAGEWAY, AND A PLURALITY OF ELONGATED, FLUID CONDUCTING TUBES IN SAID SECOND PASSAGEWAY AND EXTENDING SUBSTANTIALLY NORMAL TO SAID WALLS AND THENCE LATERALLY AT THEIR ENDS TO PROVIDE NESTED RETURN BENDS WITH SPACED THEREBETWEEN, OF MEANS FOR BRACING SAID FIRST WAL AGAINST DEFLECTION TOWARD SAID SECOND WALL, COMPRISING: RIGID MEMBERS BETWEEN THE ENDMOST RETURN BENDS OF SAID TUBES AND SAID WALLS AND IN THE SPACED BETWEEN ADJACENT RETURN BENDS FOR TRANSMITTING DEFLECTION FORCES ON SAID FIRST WALL LONGITUDINALLY THROUGH SAID TUBES TO SAID SECOND WALL, AND MEANS PROVIDING TRANSVERSE STRUCTURAL RIDIGITY TO GROUPS OF SAID TUBES COMPRISING RIGID ELEMENTS CONNECTED BETWEEN ADJACENT TUBES OF SAID GROUP INTERMEDIATE THE ENDS THEREOF.
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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4276930A (en) * 1978-07-12 1981-07-07 Sulzer Brothers Limited Tube nest for a heat exchanger

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1894692A (en) * 1931-02-18 1933-01-17 Babcock & Wilcox Co Tube support
US2345257A (en) * 1941-11-29 1944-03-28 Universal Oil Prod Co Tube support
US2714877A (en) * 1950-09-01 1955-08-09 Babcock & Wilcox Co High pressure primary air heater
US3055348A (en) * 1959-04-10 1962-09-25 Babcock & Wilcox Co Fluid heater tube platen supports
US3055349A (en) * 1959-05-11 1962-09-25 Babcock & Wilcox Co Tubular fluid heater and support therefor

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1894692A (en) * 1931-02-18 1933-01-17 Babcock & Wilcox Co Tube support
US2345257A (en) * 1941-11-29 1944-03-28 Universal Oil Prod Co Tube support
US2714877A (en) * 1950-09-01 1955-08-09 Babcock & Wilcox Co High pressure primary air heater
US3055348A (en) * 1959-04-10 1962-09-25 Babcock & Wilcox Co Fluid heater tube platen supports
US3055349A (en) * 1959-05-11 1962-09-25 Babcock & Wilcox Co Tubular fluid heater and support therefor

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4276930A (en) * 1978-07-12 1981-07-07 Sulzer Brothers Limited Tube nest for a heat exchanger

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