US2859737A - Tube supporting provisions for a vapor generating unit - Google Patents

Description

Nov. 11, 1958 J. J. BANKER 2,859,737

'vTUBE SUPPORTING PROVISIONS FOR A VAPOR GENERATING UNIT Filed Aug. 14, 1953 3 Sheets-Sheet 1 OOOOOOOOOOOOOOOODOOOOOO 00000,

lllllll/llllhvll/1111111001110 Wmv/111110111111111; ffl- INVENTOR M ATTORNEY Nov. 11, 1958 l J. J. BANKER TUBE SUPPORTING PROVISIONS FOR A VAPOR GENERATING UNIT Filed Aug. 14, 1955 3 Sheets-Sheet 2 INVENTOR jo/527 J an/cez I BY v MPM-

ATTORNEY J. J. BANKER Nov. ll, 1958 TUBE SUPPORTING PRovTsToNs PoR A vAPoR GENERATTNG UNIT Filed Aug. 14 1955 3 Sheets-Sheet 5.

INVENTOR fo/m Janker ATTORNEY l United States Patent O "ice TUBE SUPPGRTING PRVESENS FR A VAPOR GENERA'HNG UNIT .lohn J. Banker, Cranford, N. J., assigner to The Babcock e Wilcox Company, New York, N. Y., a corporation of New Jersey Application August i4, 1953, Serial No. 374,301

Claims. (Cl. 122-510) The present invention relates to the construction and operation of vapor generating and superheating units, and more particularly, to water tube steam boilers of the two drum type in whichL the steam superheating surface is formed by a group of horizontally extending looped tubes located within a cavity deiined by an upright bank of steam generating tubes connecting the vertically spaced horizontally arranged drums.

In steam boilers of the character described, the steam superheating tubes are usually horizontally arranged U-shaped tubes with the tube ends connected to vertical headers and the leg and loop portions of the tubes supported from supporting members attached to one or more large diameter steam generating tubes located between the tube legs in the superheater cavity. These large diameter steam generating tubes and superheater tubes have previously been arranged in the cavity in locations which have not permitted access to the tubes or tube supports within the cavity. Under the designed operating conditions for steam boilers of this type, the superheater tubes, and the supporting elements for these tubes are subjected to high velocity, high temperature heating gases which contain corrosive constituents which tend to damage these parts. When such superheater tubes require replacement, the tubes are cut away at their header ends and withdrawn throughopenings at the opposite end of the boiler normally closed by removable casing panels. Because of the congested condition of the superheater cavity, it is usually necessary in replacing damaged superheater parts to also remove adjoining parts which otherwise would not require removal.

The main object of my invention is the provision of a vapor generating and superheating unit of the character described with an improved construction of the supporting provisions for vapor superheating tubes within a superheater cavity in a vapor generating tube bank whereby the superheating tubes and the supports therefor are accessible and readily replaceable.

A further and more specific object is the provision of a two drum marine steam boiier of the character described with an improved construction of the supporting provisions for steam superheating tubes extending horizontally in a superheater cavity of an upright steam generating tube bank whereby all the superheating tubes and the supports therefor are accessible for cleaning or replacement and whereby individual tubes may be readily replaced without damage to the remaining tubes or supports.

A still further object is the provision of a marine steam boiler of the character described with an improved construction, arrangement' and support of looped steam v superheater tubes in a tube bank cavity permitting the use of superheater headers of circular cross-section externally of said cavity with a radial connection of all of the superheater tubes to the headers, and atiording cornplete access to the portions of the headers surrounding the tube ends. l

The various features of novelty which characterize the Patented Nov. 11, s

invention are pointed out with particularity in the claims annexed to and forming a part of this speciiication. For a better understanding of the invention, its operating advantages and specific objects attained by its use, reference should be had to the accompanying drawings vand descriptive matter in which I have illustrated and described a preferred embodiment of my invention.

Of the drawings:

Fig. l is a sectional elevation of a marine two-drum water tube steam boiler constructed in accordance with my invention;

Fig. 2 is a sectional plan view taken on the line 2--2 of Fig. l;

Fig. 3 is a detailed fragmentary elevation partly in section showing the superheater tube supporting provisions at positions A, B and C in Fig. 1;

Fig. 4 is a horizontal sectional View taken on the line 4 4 of Fig. l;

Fig. 4A is a horizontal sectional view taken on the line 4a-4a`of Fig. l;

Fig. 5 is an isometric View showing the upper portion of the spacer and support casting;

Fig. 5A is an isometric view showing the lower portion of the casting of Fig. 5;

Fig. 6 is an isometric View showing the upper portion of the lattice or bridge support casting;

Fig. 7 is a vertical section taken on the line 7-7 of Fig. 3;

Fig. 8 is a vertical section taken on the line 8 8 of Fig. 3;

Fig. 9 is a vertical section taken on the line 9-9 of Fig. 3; and

Fig. l0 is `a fragmentary end view showing the superheater tubes in a sprung position prior to placement in the supporting brackets. g

The marine steam generating unit illustrated comprises a double-walled casing 2t) having an outer front Wall 21, an outer rear wall 22, side walls 23, 24 and a roof 25. Within the casing 2d are inner front and rear walls 25 and 27, which with an inner side wall 26 and a oor 34 aid in deiining a furnace chamber 29. The unit is tired by a plurality of Huid fuel burners 32 arranged to discharge through burner ports 33 in the inner front wall 25.

The iluid heating section of the unit comprises an upper steam and water drum 35 and a laterally `oifset lower water drum 36, both of which are horizontally arranged. The steam and water drum is arranged closer to the furnace chamber wall 20 than the lower drum, The entire unit is bottom supported, as indicated in Fig. l, the upper drum being supported on therlower drum through a bank of inclined steam generating tubes 37 having their opposite ends bent and radially, connected to the corresponding drums. Two rows of larger diameter staggered water tubes 37a nea-rest the furnace chamber 29 are bent laterally to form a Water tube screen separating the furnace chamber 29 from a vertically elongated superheater cavity 30 which extends the full length of the tube bank. The steam generating surface of the unit also includes tubes 46 extending from a lower header 45 along the side wall 26 and an inner roof 44 to the drum 35; and rear wall tubes 47 extending between upper and lower rearl wall headers 4.3 and 48 which in turn are connected to the drums 35 and 36 respectively. Downcomer tubes 57, 58 and 6l connect the water spaces in the upper and lower drums 35 and 36; downcomer tubes 59 connect the water space in the drum 35 to the rear wall header 48; and downcomer tubes 52 and 60 connect lthe water space in the drum 35 to the side wall header 45. The do'wiicomers are all disposed in the spaces between the end walls and the casing.

In the gas outlet flue at the outer side of 'and above'the tube bank 37 is arranged an economizer formed by laterall as shown in Fig. 1. inner surface shaped to fit the support tubes to which they ly spaced vertical platens of multi-looped horizontally arranged tubes 41 having their upper ends connected to an inlet header 31 and their lower ends connected to a outlet header 40. e

In accordance with my invention, the steam superheatng section of the unit comprises inclined rows of horizontally extending nested U-shaped tubes 42 positioned in the superheater cavity 3i) between the main bank of steam generating tubes 37 and the screen tubes 37a. In the embodiment shown, each superheater tube row consists of three nested U-shaped tubes with the legs of the innermost tube 42a spaced apart suiciently, for example 13%, to permit a man to walk therebetween for inspection or repairs. A middle tube 42h is arranged around the inner loop and an outer tube 42C is arranged around the middle tube. The looped ends of the outer tubes 42e are slightly spaced from the front wall 25. The ends of all -of the tubes 42 are bent laterally and outwardly for connection into cylindrical headers 49, 50 and 51. The header 49 is arranged in end-to-end relation with the header 50 and the header 51 laterally spaced therefrom. These headers are arranged at an angle from the vertical and spaced from the outer side of rear wall 27. As indicated in Fig. 2, the tube end and header arrangement is such that each tube end can be radially connected to the corresponding cylindrical header and yet leave suicient accessible header area between the tube ends to permit the tube ends to be readily inspected, repaired or replaced. Steam to be superheated enters through an inlet 55 in the upper header 49 and ows through the connected tubes 42 to the header 51 and thence back through the remaining tubes 42 to the lower header 50, discharging through the superheated steam outlet 56.

The header end portions of the tubes 42 pass through sections of the rear wall 27 formed by removable insulation 27a, between which is positioned a door or removable panel 53 for access to the superheater cavity. A corresponding removable panel 53a is located in the casing rear Wall, 22. The front wall 25, over a portion corresponding to the width of the outer superheater tube loops, is formed by a heat insulated panel or door 54. The casing front wall 21 has a still wider removable panel 54a. The inclined headers 49, 50 and 51 in the rear of the unit and the fuel burners 32 in the front wall 25 are enclosed by the outer paneled casing 20. Combustion air is passed downwardly under pressure through the double walls of the unit to the burner ports 33. As indicated in Fig. 1, the headers 49 and 50 and the header 51 and associated tubes 42 are substantially coextensive with the height of the cavity 30.

In accordance with my invention, the superheater tubes are supported so as to remain in their designed nested and spaced relation during operation and yet can be readily removed when replacement is necessary. For this purpose, four pairs of large diameter laterally spaced water tubes 38a, 38b, 39a, 39h disposed between the drums 35 and 36 are arranged at staggered spaced intervals in the superheater cavity 30 to provide means for attaching thereto supporting provisions for the superheater tubes. These water tubes are arranged in pairs so that one leg portion of each U-shaped superheater tube 42 will tit in between the pairs of tubes 38a and 38b, and the opposite leg portion between the pairs of tubes 39a and 39h. The number of pairs of water tubes used depends on the size and length of superheater tubes to be supported. In the unit illustrated four pairs of support tubes are suicient.

Referring to Figs. 310, the superheater tube supporting provisions include a plurality of brackets 62 which are secured to the inwardly facing side of corresponding tubes 38a and 38b at corresponding vertically spaced intervals along their height from positions C up to A The brackets 62 have a concave 4 are preferably attached by means of seam welds 63. The brackets are symmetrically arranged relative to the tube axis and have a width less than the tube diameter. The brackets are of U-shaped transverse cross-section and corresponding brackets on each pair of tubes 38a and 38b or 39a and 39b are arranged to face each other. With the back portion fitting the tube vertically, as shown in Fig. l0, each of the U-shaped bracket portions has an inner edge contour consisting of a lower vertical portion 62a, a supcrjacent curved recessed portion 6211, curved like a superheater tube wall, an inclined straight portion 62C which extends out to the plane of the vertical portion 62a and is tangent to the curved portion 62h, a vertical portion 62d above the tangential portion 62C, and a top curved recessed portion 62e above the portion 62d. The brackets are arranged on the water tubes so that the bracket recesses 6211 and 62e of opposite tubes 38a and b, or 39a and 3911, are laterally aligned.

The supporting provisions also include metallic spacer or support castings 64 and lattice or bridge castings 65, as shown in Figs. 5, 5u, and 6. Each support casting 64 is of rectangular shape and low height with rounded opposite end portions 64d shaped to t into corresponding bracket recesses 62b or 62e on opposite support tubes'. The upper surface has a rectangular recessed portion 64a extending between the rounded ends to receive and hold a bridge casting 65 therein, and has spaced bolt holes 64b and 64e at one side of said recess. The bottom of each casting 64 also has a rectangular recessed portion 64e extending to one side edge and deep enough to receive the projecting portions of the bridge casting 65. Each bridge casting 65 is of a width permitting it to t in between the U-shaped portions of corresponding brackets 62 of opposite support tubes and has semi-circular recessed portions 65a and 65b centrally located in its top and bottom respectively and outwardly tapering tube wedging portions 65C and 65d on the top and bottom respectively of each end.

As' shown at position C in Figs. 1 and 3, the superheater tubes 42 are installed by iirst sliding a support casting 64 into the recessed portions 62b of corresponding brackets 62. Fig. 3 shows in detail the superheater tube supporting arrangement for the support tubes 38a and 38b at positions A, B and C in Fig, 1. A similar arrangement is used on support tubes 39a and 39h except for no spacing such as that at position B. After the support casting is in place, the bridge casting 65 is then placed between the U-shaped portions of the bracket and into the recessed portion 64a of the casting 64. Next the superheater tubes are sprung or pressed together, in a row of three tubes or in groups of six, as shown in Fig. l0, so that their bent ends can pass between the corresponding pairs of support tubes, and then lowered into position between the tubes 38 until in contact with the bridge casting 65. The superheater tubes are then relaxed which causes the outer tubes to move down along the bracket tangent portions 62C into the recesses 62h, and the middle tube to fall in place in the recess 65a of the casting 65. The tube ends are then expanded into the corresponding header openings or welded to corresponding stub tubes on the headers. With the bottom row in position, `bridge castings are placed on the installed row, with the middle tube ttting into the casting recesses 65b. The next tube row is then lowered and allowed to relax into position in the brackets and connected to the corresponding headers.

Groups of the tubes are thus fitted into place on each bracket except where support castings 64 are used in lieu of a tube group. The described tube positioning 0peration is repeated until the position B, shown in Figs. 1 and 3, is reached on tubes 38a and 38b opposite the abutting ends of the headers 49, 50. At this point, a tubeless space is left along the tubes 38a and 38b and adjacent the ends of the headers 49 and 50, but the structure of alternating tube rows and bridge castings-is continued for the fulllength of tubes 39a and 39b. To accomplish the spacing, twoof the'spacer castings 64 are arrangedhbetween opposite brackets 62 on tubesiSSa and 38h where superheater tubes would ordinarily be placed. Referring to Figs. 3 and 9, -a bridge casting 65 is rst placed over the top row of tubes as described, and a first support casting 64 is reversed and placed over it so that recess 64a fits over the casting 65. A second bridge casting 65 ts' into the recessed portion 64e of the iirst support casting 64. A second support casting 64 is placed on the second bridge casting 65 in reversed upright position so that the bottom recessed portion 64e rests on the second bridge casting 65. A third bridge casting 65 is then placed in the top recess 64a of the second support casting 64. This arrangement provides an interlocking of the intervening support castings and the desired spacing between tube rows along tubes 38a and 3817.

Above thefposition B the superheater tubes are installed as before and when the last tube row is in place, a bridge casting 65 is placed over the top row in between bracket U-shaped portions. A support casting 64 isv then pushed into the recesses 62b sliding over the projections on the bridge casting 65fas shown by position A in Figs. 3 and 7. Referring to Figs. 5A and 7, bolts 66 are inserted throughthe holes 64b`and 64C. A cotter pin is then pushed through a hole 67 in the bolt shank thereby locking the whole series of tube rows in place.

In order to hold the tubes 38a and 38b and the tubes 39a and 3% in a spaced relationship, collars are assembled at the top and bottom portions of corresponding tube pairs adjacent positions A and C. As shown in Figs. 4 and 4A, these collars comprise U-shaped curved pieces 63 which t around the outside of adjacent tubes and straight connecting side pieces 69 which are welded to the curved pieces'. On the vfurnace chamber side of each collar piece 68 on tubes 38b and 39h, rods 70 are welded to provide anchoring means for a high temperature refractory covering 71, such as an initially plastic chrome ore. This chrome ore refractory protects the collar parts and is applied at each collar around the curved collar pieces 63 of the tubes 38h, as shown in Fig. 4, and also between the screen tubes 37a and around the curved collar'pieces 68 on the tubes 39b, as shown in Fig. 4A.

i When the unit is shut down for inspection or repairs, the panels or doors 53 and 53a are opened to permit a workman to enter the space 30 and inspect the superheater tubes and associated supporting elements. Such a workman is also aitorded complete accessibility to all parts of the headers 49, 50, 51. The tube support brackets 62, being welded on the inside faces of the supporting tubes out of thedirect path of the oncoming hot gases, arecooled-by the heat absorbing action of the associated supporting tubes so that they usually do not require replacement in ordinary operation. However, the castings 64 and 65, which'are relatively inexpensive, are usually :subject to more rapid deterioration from the high temperatures and corrosive action of the furnace heating gases and may require replacement. If any of the tubes 42 require removal, they are cut away at their connections tothe headers 49 or 50 and 51, removed from their supports and takenr out through the door panels 54 and 54a in the front wall 25 and casing wall 2l. To do this, the top casting 64 and locking bolts 66 are irst removed. The subjacent tu-bes are then sprung together and raised row by row by a block and fall, and each succeeding bridge casting 65 is removed, until the affected tube row is reached. Although the affected tube must be pulled out through the front end of the unit, either or both of the inner tubes 42a and 42b of the superheater can be removed without rst removing tube 42C. This is accomplished by lifting the tube 42a or 42h out of the nested position after it has been cut away from the header, springing the tube legs together at the .ings used` to interlock the tubes are inexpensive and can easily be replaced if damaged by the action of the hot furnace gases. The arrangement of the superheater tubes and associated headers also affords suiiicient space in the unit to permit the bending of the tubes so that they may enter the headers radially resulting in the maximum possible tube seat depth for a given header thickness. These bends in the tubes at the header connections do not interfere with the withdrawal of the tubes since the bent ends may be sprung together a suflicient amount to clear vthe tubes 38a, Sb and 39a, 39b.

While in accordance with the provisions of the statutes I have illustrated and described herein the best form of the invention now known to me, those skilled in the art will understand that changes may be made in the form of the apparatus disclosed Without departing from the spirit 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 other features.

What is claimed is:

l. A vapor generating and superheating unit comprising walls defining a setting, an upper horizontally extending liquid and vapor drum, a lower horizontally extending liquid drum, a bank of vapor generating tubes connecting said drums, one o-r more rows of vapor generating screen tubes having their ends connected to said drums and spaced laterally from said tube bank to form a superheater cavity therebetween, a plurality of laterally spaced vertically extending headers at one end of said unit externally of said walls, access means in said walls permitting access to said cavity, a vertical bank of nested looped vapor superheater tubes horizontally arranged in n said cavity, said superheater tubes having their opposite ends connected to said headers, a plurality of superheater support tubes arranged in pairs on opposite sides of corresponding superheater tube leg portions, a plurality of brackets attached to the inner side of each pair of said support tubes, said brackets having recessed edge portions arranged to receive said superheater tube leg portions, a support casting shaped to fit into said recessed edge portions of brackets on adjacent pairs of said support tubes, and a bridge casting shaped to t into corresponding brackets on said support tubes above said support casting and to bias the outside superheater tube leg portions into said bracket recessed edge portions for Support therefrom, and having curved cavities arranged to receive intermediate tube leg portions.

2. An apparatus for supporting horizontally disposed nested U-shaped superheater tubes between vertically arranged pairs of vapor generating tubes comprising oppositely arranged U-shaped brackets for vertically spaced attachment to the adjacent sides of each said generating tubes in a pair having curved back portions that iit around corresponding generating tubes and parallel projecting portions each having an edge contour comprising horizontally aligned vertically spaced curved recesses thereon, a bridge member shaped to span the space between U- shaped inner portions of oppo-sitely facing brackets on each of said generating tubes of a pair, said bridge member having wedge shaped upper and lower portions near each end shaped to bias the outer tubes of said nested superheater tubes in said bracket recesses, and having one or more curved recesses shaped to position the inner tubes of the nested superheater tubes therein.

3. As a new article of manufacture, a vapor superheater tube support bridge member having a horizontally elongated body portion of substantially rectangular transverse vertical cross-section, symmetrically arranged end portions of lesser height having substantially flat imperforate top and bottom surfaces and curved end surfaces, one or more inclined portions connecting each end portion to said body portion adapted to space and support the tubes and one or more curved tube receiving recessed portions in said body portion.

4. As a new article of manufacture, a vapor superheater tube support bridge member having a horizontally elongated body portion of substantially rectangular transverse vertical cross-section, symmetrically arranged end portio-ns of lesser height having at imperforate top and bottom surfaces and curved end surfaces, outwardly sloping inclined portions connecting each end portion to said body portion adapted to space and support the tubes and one or more curved tube receiving recessed portions in the top and bottom surfaces of said body portion.

5. A vapor generating and superheating unit comprising walls including a pair of oppositely arranged walls defining a furnace chamber section and an adjacent vapor generating and vapor heating section, a lower horizontally extending liquid drum, an upper horizontally extending liquid and vapor drum, a bank of vapor generating tubes including one or more rows of screen tubes connecting said drums, fuel burning means for said furnace chamber, a heating gas outlet at the opposite side of said tube bank from said furnace chamber, a superheater cavity arranged in between said screen and vapor generating tubes of said tube bank and defined by said upper and lower drums and said pair of oppositely arranged walls, a plurality of laterally spaced superheater headers at one end of said unit externally of one of said pair of walls, access means in at least one of said pair of walls permitting access to said superheater cavity, a vertical bank of rows of nested U-shaped vapor superheater tubes horizontally arranged in said superheater cavity and having the inside tube legs of each tube row spaced sufficiently to form a manway therebetween, said superheater tubes having their opposite ends connected to said headers, a plurality of superheater support tubes arranged in pairs on opposite sides of corresponding superheater tube leg portions o-f each tube row, and means for supporting the corresponding leg portions of said U-shaped superheater tubes between pairs of said support tubes.

6. A vapor generating and superheating unit comprising an upper horizontally extending liquid and vapor drum, a lower horizontally extending liquid drum, a

bank of Vapor generating tubes connecting said drums, walls including a pair of oppositely arranged walls defning a furnace chamber section and a vapor generating and vapor heating section adjacent thereto, one or more rows of vapor generating screen tubes having their ends connected to said drums and extending laterally at their intervening portions into said furnace chamber section, fuel burning means at one end of said furnace chamber, a heating gas outlet at the opposite side of said tube bank from said furnace chamber, a plurality of laterally spaced upwardly extending headers at one end of said unit externally of one of said pair of walls, a superheater cavity defined by said generating tubes and said generating screen tubes, said upper and lower drum, and said pair of oppositely arranged walls, access means in each of said pair of Walls at a position between said generating tubes and said generating screen tubes permitting access to said cavity, a vertical bank of nested looped vapor superheater tubes horizontally arranged in said cavity, said superheater tubes having their opposite ends connected to said headers, a plurality of vapor generating support tubes arranged in pairs on opposite sides of corresponding superheater tube leg portions, and means for supporting said superheater tubes between pairs of support tubes.

7. An apparatus for supporting horizontally arranged rows of nested superheater tubes between vertically arranged pairs of support vapor generating tubes comprising U-shaped brackets attached to adjacent inner sides of each of said support tubes having curved back portions fitting the support tubes and projecting portions each having a plurality of curved recesses thereon arranged to maintain superheater tubes vertically spaced, and av bridge member between projecting portions of corresponding brackets having wedge-shaped upper and lower portions near each end shaped to bias the outer tubes of said nested tubes in said bracket recesses, and having curved recesses shaped to position the inner tubes of the nested superheater tubes therein.

8. As a new article of manufacture, a member for use as a component of an assembly for supporting a vapor superheater tube, said member being of rectangular shape and shallow depth and having at least one pair of opposite convexly curved side edges of a diameter of the superheater tube and at least one large face having a substantially rectangular recess formed in the surface thereof.

9. As a new article of manufacture, a member for use as a component of an assembly for supporting a vapor superheater tube, said member being of rectangular shape and shallow depth and having at least one pair of opposite convexly curved side edges of a diameter of the superheater tube and top and bottom faces having substantially rectangular recesses formed in the surfaces thereof.

10. As a new article of manufacture, a member for use as a component of an assembly for supporting a vapor superheater tube, said member being of rectangular shape and shallow depth and having a pair of opposite convexly curved side edges of a diameter of the superheater tube and the top and bottom faces having substantially rectangular recesses formed in the surfaces thereof and at least one of said recesses extending out to one of the remaining edges.

References Cited in the file of this patent UNITED STATES PATENTS 770,278 Fletcher V Sept. 20, 1904 1,133,976 Kraus Mar. 30, 1915 1,355,326 Galbraith Oct. l2, 1920 1,475,924 Nelis NOV. 27, 1923 1,905,596 Lewis Apr. 25, 1933 2,420,647 Boland May 20, 1947 2,501,147 Tolan Mar. 21, 1950 FOREIGN PATENTS 771,052 France Sept. 29, 1934 893,994 France Dec. 11, 1944 443,503 Great Britain Mar. 2, 1936 609,674 Great Britain Oct. 5, 1948 104,090 Sweden of 1942

Images