US1776839A - Reheat superheater - Google Patents

Description

` Sept. 30, 1930. w. s. MQNROE ET AL v 1,776,839 l A REHEAT SUPERHEATER Filed Feb. 1, 192s 2 sheets-sheet 1 Patentedv Sept. 30,l 1930 UNITED s'rATss PATENT orrice WILLIAM S. MONROE AND HERMANv C. IHEACLOIT, 0F CHICAGO, ILLINOIS, AND DAVIDS. JAGOBUS, F MON'ICLAIR, NEW JERSEY, ASSIGNORS TO THE BABCOCK & WILCOX COMPANY,` OF BAYONNE, NEW JERSEY., A CORPORATION OF NEW JERSEY f REHEAT 'SUPEBIIEATER Application l-ed February l, 1926. Serial No. 85,090.

Our present invention relates to steam rel` heaters and will best be understood from the following descri tion and'the annexed drawings, in which ig. lis a vertical section of an illustrative embodiment of our invention with the .well understood lower portion of, the steam generator broken away; Fig. 2 is a transverse section of a portion of Fig. 1; Fig'. 3 is an enlarged side view of one of the details; Fig. l4 is a section take-n along the line 4-4 of Fig; 1; Figs. 5 6, and 7 are enlarged side views of details.

In .the drawings, the upper portion of av known type of steam generator is shown, having horizontally inclined water tubes 10 connected tol uptake headers 11 which, in turn, are connected through steam and water circula-tors 12 with a steam and water drum 13, this latter being connected by downtake nipples 14 with the -downtake headers to lwhich the lower ends'of the tubes'lO are connected.

A superheater 15 is shown above the tubes 10 through which thesteam generated by the heater is passed and superheated. The steam from the superheater 15 is led to the main steam line which' supplies steam to the steam turbine. The waste gases from the steam generator, after passing over the tubes 10 and the superheater 15, flow upward through a vertical flue 16, separated by a wall 17 from Ia second vertical flue 18 which'carries the gases down over tubes 12 and .between the nipples 14 to the boiler gas exit. The front wall -17a is provided with openings 17b across the vertical flue 16 to permit cold air to.

mingle with the hot gases for the purpose of controlling the temperature of thereheated steam in the reheater tubes and preventing it from rising above a predetermined point. rl1`he rear wall 19 is inclined so as to produce a progressively narrowing pass as the gases iiowdownward through the Hue 18, and this wall is provided with doors 19B, 19" and 19c for purpose to be described more fully hereinafter. l l

Adjacent the lower portion of they fiue 18 and near the wall 19 isyan inlet manifold 20, to which an inlet steam pipe 21 is connected. Similarly, at'the upper portion of the flue 1S is a steam outlet manifold 22,v to which a steam outlet pipe 23 is connected. Between.

the manifolds 20 and manifold 24.

All of the steam from an intermediate stage of the steam turbine Hows through the inlet steam pipe 21 and thencethrough the tubes of the reheater and after the tem-v perature of the steam is raised thedesired amount through the reheating, it` passes outward through the steam outlet pipe 23 to the next succeeding stage of the steam turbine. It is essential that in passing the steam from the steam turbine and returning it thereto that there be a minimum drop in the pressure on account of the friction of the steam fiowing through the piping and the reheater, otherwise the thermodynamic gain due to the 'reheating of the steam may be entirely oiiset by the loss in power generated by the steam turbine. In the reheater of this sort it is, therefore, very advantageous for the steam to pass through it with 'a minimum amount of resistance.

The manifolds 20, 22 and 24 are connected by tubes, so that steam entering the manifold 20 will flow in a generally upward direction to the outlet manifold 22 while the heating gases are flowing downward. It is important to have t-he steam How upwardly through the heating tubes in order to secure an even dis- 22 is a supplemental tiibution of the steam between the 'different tubes of the reheater with a minimum resistance to flow. Should the steam from the steam turbine beled into the uppermost header and be discharged from the lowerJ most header of the re-heater soras tov cause the steam to flow downwardly, there would be a tendency to stagnatethe How of the ste-. 1n through some oi' the tubes which would reduce the efficiency of the reheater and might result in the burning out of the tubes. `With a downward flow should one` or more tubes become hotter than the others the density of the steam in these tubes would become less than that in the remaining tubesl and the statical head produced through the change in density would tend to retard the flow of the steam through'the tubes which are overheated. Wit-h an upward flow any overheating of the tubes would tend to inlili` crease the How of steam through the tubes through this saine cause and would tend to prevent overheating.

In the illustrative embodiment, the manifolds 22 and 24 are connected by aplurality of U-tubes 25, such tubes extending transversely of the flue 18 and preferably being long enough so .that they will be supported on the top of the wall 17 and will also extend into the flue 16.

The manifolds 2 0 and 24, in the illustrative embodiment, are connected by a plurality of U-tubes 26 which are given a number of reverse bends with the substantially horizontal leg portions 'of `the tubes transverse ot' the flue 18 and of progressively shorter length.

By making the lengt-l1 of thetransverse portions of the superheater tubes as illustrated, we not only are able to form the flue 18 so that it will give amass flow increase to improve heat transfer rate per degree difference in temperature as the gases flow through the flow, but also we are able to provide the greatest amount of superheating surface at the point where the gases are hottest and just before the steam leaves the superheater.

The wall 19 is provided with a door 19'L large enough to permit the insertion and withdrawal of the tubes 25 land the corresponding door 19"- permits the insertion and Withdrawal of the tubes 26.

A transverse supporting girder 28 extends through the boiler from side to side of the setting. This girder is made hollow', to prof vide air Ventilation for cooling it. The girder is shown as made up of I- beams 29 and 29 to form the side walls and cross pieces 3() and 30 to form the top and bottom thereof.

A Z-bar 31 and an angle-bar 32 may be at tached to one side of the girdcr, and metal plates 33 (Figs. 1 and 5) may be suspended by means ot hooks 34 from these Z- and anglebars. The plates 33 are made up of vertical portions 35 and sloping portions 35', one side of these plates being provided with bulbed ribs 36 for holding tile in the well-known manner, by providing grooi'es in the tile which slip over the bulbed portions of the.-v

ribs. The slopingportions 35 are provided with strengthening ribs 37, and ledges 38 extend outwardly from the other side near the lower ends of the plates, upon which ledges tile guided by the bulbed ribs 36 may rest. A transverse plate 39 extends across and is attached to the lower ends nof the plates 33, as by bolts or rivets., and is provided with recessed rounded portions to receive the upper row of tubes 12. A plate 4() withslots along its edges to receive the tubes 12 is attached .along one edge to the plate 39, and along the other edge to the angle iron 41 which is, in turn, attached to the plates 42 that are provided with horizontal extensions 42 for sustaining wall tile, and a vertical portion 43 which extends acrossthe tubes 15 arrasa@ tothe upper edge ofthe battle 44, which battle is provided with a by-pass door 45 for short circuiting the hot gases to the stack. The bypass door 45 is operated as a safety measure when the steam turbines are shut down to prevent burning of the reheater tubes 25 due to lack of steam passing therethrough.

Suspension rodsv 48 provided with turn buckles 49 are attached to the girder 28 and are fastened to lugs provided on the header 50 of the superheater 15, so as to support this header.

A Z-bar 51 and an angle-bar 52 are attached to the girder 28, and plates 53 are suspended therefrom by means of hooks 54. These plates 5 3 are provided with channeled ribs 55 (Figs. 1 and 7), the upper endsof which are connected by means of angle irons 56 to the bar 57, upon which the bottom row of tubes 26 rests', so thatthese tubes are supported by the channel 28. Plates 58 (Figs. 1 and 6) provided .with inturned ends 59 mav be attached by these inturned ends to the plates 53, and the lower ends of these plates may be attached to the upper edge of the plate 39 on the side opposite the plates 35.

A metal cross bar 61 (Figs. 1, 3 and 4) extends across the lower side of the tubes 26, parallel with the bar 57, and a similar bar 62 extends across the topmost sides of the lowest horizontal portions of the tubes 26. rIhe bars 61 and 62 are connected by metal members 63 and 64 which cross each other (Fig. 3), and are provided with recesses 65 to accommodate the tubes 26. The bar 62 is conA nected by means of metal plates 66 to a similar bar 61 extending across the lower side of the next horizontal portions of the tubes. In this way a Wall of considerable compressive strength is built up entirely across the planes, so as to permit gas to pass between the two at this spaced section. Another similar wall may beA made across the tubes 25 above and resting upon the wall 17 by means of the liars 61, 62 and plates 63, 64H and 66 so as to direct the gasesacross the bends of these tubes and also help support the tubes. The supporting girder 28 not only supports the walls 17 and metal plates 33 and 42 with their tile but also the header 50: as well as the plates 53 which, in turn, support the tubes 26 as abovedescribed.

The roof 70 above the two lues 17 and 18 may be of any desired construction. In the arrangement shown, they refractory bricks 71 are suspended from the beams 72 by bolt hangers 73, so that the bricks 71 may be free to expand without injury.

The structure which we have disclosed may be used either as a superheater for superheating steam-from the boiler or it may be used, as in the illustrative arrangement, forv reheatingsteam between stages of a multistage prime mover, and it will be 'understood that when we use theterm superheater in the appended claims, lwe mean either a primary superheater or a superheater for resuperheating exhaust steam.

n lt will also be understood that our invention maybe embodied in various forms and that the arrangement which We have shown is merely illustratige.

The reheat superlieater described in this specification is especially adapted for use 'in connection with steam turbinesthat are connected intandem or in which interstage reheating bfsteanL-isaccomplished after it heat superheater is suitable'for use in conproper, indicated in the lower portion of ordinary boiler` superheaters.

@passes throughone turbine or stage and be- 20- fore it enters the next succeeding turbine or stage. vlt is to be understood that this re-k nection with other-boilers that supply steam to the 'first turbine which maybe supplelnented by steamsupplied by the steam generating and superheating tubes or boiler Fig.. l. rlhe 'requirements for such reheat superheaters differ materially from those for Such reheat superheaters should receive a very large fraction of the heat from the boiler furnace because the primary object. of a boiler equipped .with such reheat superheaters is not to produce steam but to,l superheat steam already produced. To keep the superheat high and constant enough for advantageous use, .it is necessary to control the fire for superheat and not for steam making. ln a boiler equipped witha reheatsuperheater the ratio of steam superhea-ted to steam generated is always much greater than unity, whereas in ordinary boilers with superheaters, the ratio is i the. boiler proper and 13% by the boiler superheater. Another difference in a reheat superheater is with respect to the relative amounts of hot gases used per pound of steam compared to that used in a regular boiler. ln

. ,a standard boiler about 1.5 to 1.8 pounds of gas is requiredper pound of steam generated, V and in 'a reheater boiler about 2.5 to 3 pounds of gas are required per pound Ofysteam. In

our reheat superheater about one-half a pound of hot gases is required per pound of steam, although this may vary somewhat depending upon the quality of the steam which varies with the turbine load, so that there shouldnot be a large drop in pressure on account of the friction of the steam flowing through, as above mentioned. This is especially important fas larger quantities of steam flow through-the reheat superheater than would normally be generated by a single boiler. f

Also, by permitting the steam to enter the superhater at the bottom and rise through a plurality of tubes of large aggregate crosssectional area that are heated through a considerable distance, as described, the draft' effect ofthe rising steam is suflicient to compensate m large measure for inequalities and cause'greater uniformity of distribution of l steam through the tube, and the tem erature increase as the steam rises aids the 0W and tends to neutralize the friction.

VThe height of an ordinary superheater is i not' sufficient to produce any appreciable amount of draft caused by so-called stack effect, but with our device we find that the upward draft -of the steam produced in the reheat superheater tubes is sufficient to over* come a considerable amount of steam frietion4 in the tubes. This is especiall noticeable at small loads, as the friction varies inversely as the square of the load. The friction at small loads is too small to be relied upon to produce uniform distribution of steam through the tubes. The draft Aeffect due to the great vertical height of our superheater is, therefore, especially advantageous inaiding steam distribution through the' tubes at loads Where friction is not sufficient for'this purpose.

l. ln a steam boiler, a first vertical Hue disposed above the boiler heating surfaces and leading u Wardly therefrom, a second vertical flue adjacent the first flue and having its upper portion connected tothe upper portion of the first flue with a gasexit at the 'lili bottom ofthe second Hue, a wallI dividing n.

said flues, a support for said wall disposed above said surfaces, anda steam superheater having tubes extending across-the second flue witlrthe steam inlet'at the bottom and the steamou'tl'et at the top of the second lflue, with the superheater tubes arranged` to lead the steam back and forth across the second flue to" and leading upwardly. therefrom, a second.y

vertical due adjacent the first flue and having its upper portion connected to the upper portion of 'the first flue with a gas exit at the o o bottom ofthe second flue, a wall dividing said Hues,'a support for said wall disposed above said surfaces, and a steam superheaterhaving tubes extending across the second Hue with the steam inlet atcthe bottom and the steam outlet at the top of the second Hue. with the super-heater tubes arranged to lead the steam back and forth across the second Hue to the above said surfaces, a superheater inlet mani-'- fold atthe bottom of the second Hue and a superheater outlet manifold at the top of the second Hue, said manifolds being positioned adjacent the wall of said second Hue remote from said first Hue, and U-tubes con-' necting said manifolds and having their legs extending transversely of said second Hue.

4. En a steam boiler, a first vertical Hue disposed above the boiler heating surfaces and leading upwardly therefrom, a second vertical Hue adjacent the first flue and having its upper portion connectedv to the upper portion of the first Hue with a gas exit at the bottom of the second Hue, a Wall dividing said Hues, a supportl for said wall disposed above said surfaces, a'superheater inlet manifold at the bottom of the second Hue and a superheater outlet-manifold at the top of the second Hue, saidmanifolds being positioned adjacent the wall of said second Hue remote from said first Hue. and U-tubes c0n necting said manifolds and having their legs extending transversely of said second Hue and the length of said legs decreasing from the top tothe bottom of said second Hue.

5. ln a steam boiler, a first vertical Hue disposed above the boiler' heating surfaces and leading upwardly therefrom, a second vertical Hue adjacent the HrstHue and having its upper portion connected to the upper p0rtion of the first Hue with a gas exit at the bottom of the second Hue, a Wall dividing said Hues, a support 'for said wall disposed above said surfaces, a superheater inlet manifold at the bottom of the second Hue and a 'superheater outlet manifold at the top of the second'flue, a siipplemental manifold between said inlet and said outlet manifold, said manifolds being positioned adjacent the wall of said second Hue remote from said first Hue, a first set of` U-tubes connecting the 'outlet manifoldand the supplemental manifold and a second set of U-tubes connecting the supplemental `manifold and the inlet manifold,`said tubes extending transversely of the second Hue.

, f6. In a steam boiler, a first vertical flue disposed` above the boiler heating surfaces and its upper portionA connected to the upper por-- tion of the first Hue with a gas exit at the bottom of the second flue, a Wall dividing said Hues, a support for said wall disposed above said surfaces, a superheater inlet manifold at the bottom of the second Hue and a superheater outlet manifold at the top of the second Hue, a supplemental manifold between said inlet and said outlet manifolds, said manifolds being positioned adjacent the wall of said second Hue remote from said first flue, a first set of U-tubes connecting the outlet manifold and the supplemental manifold and a second set of U-tubes connecting the supplemental manifold and the inlet manifold and having a plurality of reverse bends, said tubes extending transversely of the second Hue.

7. Ina steam boiler', a first vertical Hue disposed above vthe boiler heating surfaces and leading upwardly therefrom, a second `vertical Hue adjacent the first Hue and having its upper portion connected to the upper portion of the first Hue with a gas exit at the bottom of the second-Hue, a wall di Viding said Hues, a support for said wall disposed above said surfaces, a superheater inlet manifold at the bottom of the second Hue and a superheater outlet manifold at the top of the second flue, a supplemental manifold between said'inlet and said outlet manifolds, said manifolds being positioned adjacent the wall of said second Hue remote from said first Hue, a first set of U-tubcs connecting the outlet manifold and the sup plemental manifold and a second set of U- tubes connecting the supplemental manifold and the inlet manifold and having a plurality of reverse bends, said tubes extending transversely of the second Hue, the legs of thesecond set of U-tubes being shorter than the legs of the first set of U-tnbes.

8. In a steam boiler, a first vertical Hue leading from they gas exit from the boiler heating surfaces, a second vertical Hue ad jacent the first Hue and having its upper jiortionronnected to the upper portion of the first Hue with a gas exit at the bottom of the second Hue, a superheater inlet manifold at tbe bottom of the second Hue and a superheater outlet manifold at the top of the second Hue. a supplemental manifold between said inlet and said outlet manifolds` said manifolds being positioned adjacent the wall of said second Hue remote fronrsaid first'Hue, a first set of U-tubes connecting the outlet manifold and the supplemental manifold and a second set of U-tubcs connecting the supplemental manifold and the inlet manifold and having a plurality of reverse bends, said 'tubes extending transversely of the. secondHue, the legs of the second set of U-tubes being shortefthan the legs'of the first set of U-tubes and the first set of U-tubes extending into and transversely of the first Hue.

9. In a steam boiler, a first verticalHue leading from tliegas exit from theboiler heating surfaces, a second vertical Hue adjacent the first Hue and havingits upper portion connected tothe upper portion of the first Hue with a gas exit at the bottom of the second Hue, asuperheater inlet manifold at the bottom of the second Hue and a superheater outlet manifold at the top of the second Hue, a supplemental manifold between said inlet and said' outletv manifolds, said manifolds lbeing positioned adjacent the wall of said second Hue remote from said first Hue, a first set of U-tubes connecting the outlet manifold and the supplemental manifold and a second set of U-tubes connect-ing the supplemental manifold and the inlet manifold and having a plurality of reverse bends, said tubes extending transversely of the secondHue, the legs of the second set of U-tubes beingshorter than the legs of the first set of U-tubes, and the first set of U-tubes extending into and transversely of the first Hue and resting on the top 'of the wall between'the Hues.

.10. In a steam boiler, a first vertical Hue disposed above the boiler heating surfaces and leading upwardly therefrom, a second vertical Hue adjacent the first'Hue and having its upper portion connected to the upper portion of the Hrst Hue with a gas exit at the bottom of the second Hue, a wall dividing said Hues, a support for said wall disposed above said surfaces, a superlieater inlet manifold at the bottom of the second Hue and a superheater outlet manifold at the top of the second Hue, a supplemental manifold between said inlet and said. outlet manifolds, said manifolds being positioned adjacent the wall of said second Hueremote from said first Hue, a first set of U-tubes connecting the outlet manifold and the supplemental manifold and a second set o f U- tubes connecting the supplemental manifold and the inlet manifold, said-tubes extending transversely of the second Hue, the outer walls of the second Hue being provided with Y doors, whereby the U-tubes may be-withdiawn from and inserted into operativeposition. f Y

1l. In a steam boiler, a vertical Hue connected to cause a downward How of hot gases therethrough and disposed above the boiler heating surfaces, a' superheater havl ing tubes extending transversely of said Hue and connected'to cause a generally upward How of the steam to be 'superheated, said super-heater comprising an inlet, ,an outlet anda supplemental manifold at the side of the Hue, U-tubes connectingv the 'inlet manifold and the supplemental manifold and U-tubes connecting the outlet manifold and the supplemental manifold.

12. In a steam boiler, a vertical Hue connected to cause a downward flow of hot gases therethrough and disposed above the' boiler heating surfaces, a superheater having tubes extending transversely of said Hue and'connected to cause a generally upward How of thesteain to be superheated, said superlieater comprising an inlet, an outlet and a supplemental manifold at the side of the Hue, U- tubes connecting the inlet manifold and the supplemental manifold and U-tubes 4connecting the outlet manifold and the supplemental manifold and doors in the wall between'adjacent manifolds toprovide access to the U- tubes connecting said manifolds. v

13.*In a steam boiler, a first vertical Hue disposed above the boiler heating surfaces, a second vertical Hue adjacent the first flue and having its upper portion connected to the upy ond Hue, a wall dividing said Hues, and a liol- 9 low air-cooled girder supporting said wall.4

14. In a steam boiler, a first vertical Hue disposed above theboiler heating surfaces, a second vertical Hue adjacent the first Hue and having its upper portion connected to the upper portion of the first Hue with a gas exit at the bottom of the second Hue, a steam superlieater having tubes extending across the second Hue with the steam inlet at the bottom and the steam outlet at the top of the second flue, with the superlieater tubes arranged to lead the steam back and forth across the second Hue, a wall dividing said Hues, and a hollow air-cooled girder supporting said superheater tubes and said wall.

15. In a steam boiler, a first vertical Hue disposed above the boiler heating surfacesv and leading upwardly therefrom, a' second khaving tubes eiiteifidingl across the second flue,

said first named Hue being provided with openings for introducing cold air therein.

16. In a steam boiler, a first vertical Hue disposed above the boiler heating surfaces and leading upwardly therefrom, a second vertical flue vad jacent the first Hue and having its upper portion connected to the upperportion of the first flue withv a gas exit at thebottom of the second Hue, a wall dividing said Hues, a support for said wall disposed above said' surfaces, a steam superheater having tubes extending across the second flue, and a by-pass for gases between said flues` below said superheater.

17. In a steam boiler, a vertical flue connected to cause a downward flow of' hot gases therethrough, and a su erheater having tubes extending transverse y of said fine and connected to cause a generally upward flowv of the steam to be superheated, said tubes extendingin a vertical plane a sufficient distance to produce an upward draft of steam in said tubes equivalent to a substantial part of the flow resistance of the steam, thereby to promote a flow of' steam in the tubes.

18. In a steam boiler, a vertical flue connected to cause a downward flow of hot gases therethrough, and a superheater having tubes extending transversely of said fiue and connected to cause'a generally upward flow of the steam to be superheated, said tubes being of sufficient cross sectional area and extending a sufficient distance vertically to produce an' upward draft in said tubes equivalent to a substantial art of the flow resistance of the steam, thereby to promote a flow of steam in the tubes.

19. In a steam boiler, a first vertical flue leading from the gas exit from the boiler heating surfaces, a second vertical kflue adjacent the first fiue and having its upper portion connected to the upper portion of the first fiue, with a gas exit at the bottom of the second flue, and a steam superheater having tubes extending across the second flue with the steam inlet at the bottom and the steam outlet at the top'of the second flue, with the superheater tubes arranged to lead `the steam back and forth across the "second flue, some of said tubes extending partially across said first flue.

20. In a steam boiler, a first vertical flue conducting gases upwardly therein,.a second vertical f iue adjacent the first flue and having its upper portion connected to the upper portion of the frstfiue, with a gas exit at the bottom of the second fiue, and a Steam superheater having tubes extending across the second flue with the steam inlet at the bottom and the steam outlet at thc to of the second flue, .with the superheatcr tu es arranged to lead the steam back and forth across the second flue,` some of said .tubes extending partially across said first flue.

21. In a steam boiler, a first vertical fine conducting gases upwardlyv therein, a second Vertical flue adjacent the first flue and having its upper portion connected to the upper ortion of the 4first flue, with a gas exit at the bottom of the second flue, a steam superheater having. tubes extending across the second flue with the steam inlet at the bottom and the steam outlet at the top of the second flue, with the superheater tubes arranged. to lead the steam back and forth across the second flue, some of said tubes' extending partially across said first flue, and a wall disposed between said flues and supporting the tubes extending into said first flue.

2Q. In a steamboiler, a first vertical flue conducting. gases upwardly therein, a second vertical flue adjacent the first fluev and having its upper portion connected to the upper .portion of the first flue with a gas exit at the bottom of the second flue, a wall separating said flues, an air cooled girder disposed beneath said wall and. supporting the salne, a steam superheater havmg tubes` extending across the second flue and adapted to lead the steam back and forth thereacross, some of said tubes extending partially into vsaid first flue and supported on top of' said wall, and means supporting the rest of' said tubes from said girder.

23. In a steam boiler, a first vertical fine conducting gases upwardly therein. a second vertical flue adjacent the first flue and having its upper portion connected to thc upper portion of the first flue, with a gas exit at the bottom of the second flue, a steam superheater having tubes extending across the second flue( with the steam inlet at the bottom andthe steam outlet at the top of' the second flue, with the superheater tubes arranged to lead the steam back and forth across the second fiue, some of said tubes extending partially across said first flue, and a partition separating said flues and supporting saidlast-named tubes.

24. In a steam boiler, a first vertical flue conducting gases upwardly therein` a second vertical flue adjacent the first fine and having itsupper portion connected to the upper portion of the first flue, with a gas exit at the bottom of' the second flue` a steam superheater having tubes extending across the second fine with the steam inlet atI the bottomandthe steam outlet at the top of f the second iflue, with the superheater tubes arranged to lead the steam back and forth across the second fine, and a partition of refractory material disposed between said flues, said. tubes being arranged at right angles to lsaid partition and some of them extending over thetop of said partition into said first flue, said partition acting as a support for said last-namedl tubes.

WILLIAM S. MONROE. HERMAN C. HEATON. DAVID S. JACOBUS.

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