US2845049A - Vapor generating and superheating unit with an integral superheater having radiant and convection sections - Google Patents

Description

July 29, 1958 H. NUNNINGHOFF 2,845,049

VAPOR GENERATING AND SUPERHEATING UNIT WITH AN INTEGRAL SUPERHEATER HAVING RADIANT AND CONVECTION SECTIONS Filed Sept. 1, 1955 4 Sheets-Sheet 1 INVENTOR ATTORNEY H. NUNNINGHOFF July 29, 1958 2,845,049 VAPOR GENERATING AND SUPERHEATING UNIT WITH AN INTEGRAL SUPERHEATER HAVING RADIANT AND CONVECTION SECTIONS Filed Sept. 1, 1955 4 Sheets-Sheet 2 0000 GOOD INVENTOR Heinrich Nuflfll'n ghoff BY ATTORNEY FIG 2 H. NUNNINGHOFF July 29,, 1958 INTEGRAL SUPERHEATER HAVING RADIANT AND CONVECTION SECTIONS Filed Sept. 1. 1955 4 Sheets-Sheet 3 4 6 8 F 6 6 M H r r .WOOOWCOCOCCGGOA c c moomoooo 4 0 0 u 00000000 8 0 000000000 4/ n u 000000000 a 0 00000000 008000 0 0 000000000 0 0 000000000 0 0 00000000 80088 H n 0 0000000007 0 \u 000000000 J 0 00000000 8888 0 000000000 mk M, 0 U V D 00000000 0 0 00000000 80R?! RM 4! n 0 000000000 o 0 000000000 0 00000000 0880 000000009 0 0 2 0 000000000 0 00000000 08880 n 9 000000000 0 U 00000000 7 7 0 000000000 w w 88080 Y 30 D 7 pl A A 0 2 00000000? 2 00000000 8888 9m 0 000000000 A o 0 000000000 Om 0 00000000 8838 0 000000000 I M 0 \u 00000000 II n 0 00000000 QBRWB DM 0 0 000000000 n n u 000000000 A n 0 00000000 00988 QM 000000000 M 8 n w 000000000 0000000 0 M m m 8888 \u 000000000 o 0 00000000 0 00000000 05088 H n 0 00000000.. A, 0 000000000 00000000 5 PM M 00000000 9 n L 0 0 000000000 0000000 A 6 n 4! u cccowoow M T 000000900000 300000000 00000:: \fi 4! 8 1 1 FIG 3 RHEATING UNIT HAVING RADIANT 2,845,049 WITH AN AND y 9, 1958 'H. NUNNINGHOFF VAPOR GENERATING AND SUPE INTEGRAL SUPERHEATER CONVECTION SECTIONS Filed Sept. 1. 1955 4 Sheets-Sheet 4 FIG 4- FIG 6 FIG 5 INVENTOR ATTORNEY United States Patent VAPOR GENERATING AND SUPERHEATIN G UNIT WITH AN INTEGRAL SUPERHEATER HAVING RADIANT AND CONVECTION SECTIONS Heinrich Nunningholl, Oberhausen, Germany, assignor to The Babcock & Wilcox Company, New York, N. Y., a corporation of New Jersey Application September 1, 1955, Serial No. 531,943

7 Claims. (Cl. 122-478) This invention relates to improvements in steam generating and superheating units. It is more particularly related to improvements in a water tube type of vapor generating and superheating unit operating at high fluid pressures, high capacities and high temperatures.

The type of unit with which the invention is more particularly related involves an enclosure for high temperature heating gases usually received from fuel burning means. This enclosure includes a high temperature heating chamber, the walls of which include vapor generating tubes. It also includes a gas pass receiving gases from the chamber.

In the above indicated combination, the invention is particularly concerned with fluid heat exchange means herein represented as a vapor superheater having a multiplicity of tubes connected to a vapor inlet means and receiving the generated vapor. These tubes lead from a common inlet position to a common outlet means and the superheater tubes are so constructed and arranged as to substantially reduce the cost of the original installation of the unit by material reduction in the number of headers required for adequate and effective superheat-ing. This is accomplished while maintaining effective heat transfer conditions in the various zones in which successive parts of the superheater tubes are disposed. It is also accomplished while maintaining the advantages of a combination of a radiant superheater and a convection superheater, these two types of superheaters having compensating tendencies as to the changes in vapor temperature over a wide range of rate of vapor generation.

In attaining the above indicated results the superheater tubes directly connecting inlet means at a common inlet position and a common outlet means, have successive parts disposed in successively lower gas temperature zones. The first parts, disposed in the highest gas temperature zone, include the parts of the superheater tubes arranged as widely spaced platens or panels, preferably disposed within the high temperature gas chamber, each platen or panel consisting of a plurality of parallel and closely arranged superheater tube sections joined together, preferably by metallic means, including welds, which completely fill the spaces between the parallel superheater tube plat-en sections.

From the above indicated first platens the same superheater tubes continue through second sections or parts which are transversely related to the tubular sections of the first parts, preferably near the upper parts of the first platens. These second sections, or groups, extend between successive and spaced upright vapor generating tubes with which they are so associated as to afford pendent supports for the first panels or platens, and to afford pendent support for some of the remaining platens.

Beyond the above indicated second sections of the superheater tubes, the tubes continue through a lower tem perature zone, preferably disposed in or near the gas out let of the heating gas chamber. These third sections of the tubes are arranged, preferably in parallelism and they are formed in third groups which constitute third panels ICC or platens. Each of these third platens has a number of tubes which is less than the number of tubes of the first platens and is, preferably, half the number of tubes in each of the first platens. The number of second platens is greater than the number of the first platens and, preferably, twice thereof; also, the sid-e-to-s'ide spacing of the second platens is less than the side-to-side spacing in the first platens and is, preferably, one-half thereof.

Beyond the lower temperature zone in which the second platens are disposed, the superheater tubes continue in other spaced groups with these groups preferably having the same spacing as the second platens. However, these last mentioned groups of superheater tubes are so arranged as to make this section of the superheater predominantly convection heated, as compared to the platens of the first sect-ion of the superheater which are predominantly radiantly heated. To attain this result the successive front to-rear spacing of the tube sections of the last mentioned groups of superheater tube sections is substantial. The successive superheater tube sections in the last' mentioned group are not rigidly united as are the successive sections in the first platens, and the gases may therefore flow entirely around the tube sections of this last mentioned group. This group may be referred to as the fourth group of superheater tube sections.

At the tops of the superheater tube sections of the fourth group, the tubes continue in fifth groups of superheater tube sections, preferably directed transversely to the tube sections of the fourth group, with the number of the fifth groups being twice the number of the fourth groups of the superheater tube sections and the number of tube sections in each of the fifth groups being one-half the number of superheater tube sections in each fourth group. The superheater tube sections of the fifth group extend between horizontally spaced upright and successive vapor generating tubes and are, preferably, soassociated with these vapor generating tubes that part of the total pendent support for associated parts of the superheater is afforded. Such supporting means may involve metallic studs or projections welded to the vapor generating tubes and disposed beneath the successive superheater tube sections of each fifth group.

Beyond the fifth group of super-heater tube sections above referred to, the superheater tubes continue downwardly in a lower temperature zone. These downwardly extending sections are formed into sixth groups of superheater tube sections and continue through return bends at their lower parts and then through upwardly extending seventh groups of superheater tube sections, the sixth and seventh groups forming a number of spaced rows of tubes transversely of the unit, with the number of rows being twice the number of rows of the fourth group. The superheater tubes continue through the seventh group of sections to a common outlet, preferably in the form of header means disposed externally of the heating gas enclosure.

Preferably a number of the upright tubular sections of each of-the first platens is connected in a load-supporting manner with metallic hangers depending from the supporting steelwork of the unit to afford further pendent support for the superheater tubes, and, in a similar manner, some of the upright tubes of the fourth group are similarly associated with other similar hangers.

The invention will be clearly and concisely set forth in the claims, but for a more complete understanding of the invention, its advantages and its uses, reference should be had to the accompanying description which refers to the unit illustrated in the accompanying drawings.

In the drawings:

Fig. 1 is a diagrammatic view in the nature of a vertical section illustrating the general arrangement of the pertinent parts of the vapor generating and superheating unit;

Fig. 2 is a vertical section of the Fig. 1 unit on the section line 22 of Fig. 1, and looking in the direction of the arrows;

Fig. 3 is a two-level plan section on the horizontal planes of the section line 3-3 of Fig. 1 and looking in the direction of the arrows;

Fig. 4 is a fragmentary transverse section of a number of the tubes of the first platens at such a position as that indicated by section line 4 of Fig. 1;

Fig. 5 is a fragmentary elevation of the superheater support arrangement provided by the upper parts of the vapor generating tubes extending across the flow of gases in the gas pass leading from the high temperature heating chamber or secondary furnace chamber of the unit; and

Fig. 6 is partially an elevation and partially a vertical section taken at 90 to the direction from which Fig. 5 is taken.

The illustrative vapor generating and superheating unit shown in the drawings has a high temperature gas chamber 10, preferably of rectangular cross-section, as indicated in Fig. 3. This chamber may be referred to as part of the entire gas enclosure of the unit and it is formed by wall means, including the side walls 12 and 14 with their associated vapor generating tubes 16 and 18 (Fig. 3), and front and rear walls 20 and 22 with their associated vapor generating tubes 24 and 26. All of the vapor generating tubes are preferably connected into a fluid circuit by appropriate headers and tubular connections, such as the upper headers 28 and 30 of Fig. 2, from which the circulators, such as 32 and 34, communicate with the vapor and liquid mixture receiving chamber 36 of the vapor and liquid drum 38. Fig. 1 shows the vapor generating wall tubes 24 connected at their upper ends to the header 40 from which the roof tubes 42 extend along the roof 44 of the furnace chamber 10 and through a part of the gas pass leading from the chamber. These tubes are indicated as extending through the roof of the gas enclosure at 46 from which position they extend through the horizontal circulators 48 to communication with the mixturereceiving chamber 36 of the drum 38.

Fig. 1 also indicates that the intermediate parts of some of the wall tubes 50 at the rear wall 52 of the chamber 10 have rearwardly and upwardly inclined sections 54 extending along the floor 56 of the transverse superheater gas pass 58. At the upper end of this floor, and at a position where this floor is joined by the left hand wall 60 of the downfiow of gas pass 62 there are screen extensions of the vapor generating tube sections 54. These extensions, indicated at 64 and 66, are widely horizontally spaced to provide for gas flow through that part of the gas fiow path. These sections extend through the roof portion 68 of the superheater gas pass as clearly indicated in Fig. 1 and thereafter continue through the horizontal circulator sections 70 to communication with the vapor and liquid mixture chamber 36 of the drum 38.

Others of the vapor generating wall tubes 50 have upper parts disposed as widely spaced screen sections 72 and 74, extending across the fiow of gases at the gas outlet of the furnace chamber 10. These screen sections extend through the roof portion 44 and between the roof tubes 42 to a level adjacent the drum level whence they continue through the horizontal circulator sections 76 to communication with the mixture chamber 36.

The vapor generating tubes having the upright parts 26 disposed along the rear wall 22 of the unit continue at the level of the roof portion 68 through roof tube sections 78 to communication with the mixture chamber 36 as clearly indicated in Fig. 1.

The mixture chamber 36 preferably has mixture outlets at its upper parts communicating with such cyclone steam and water separators as are indicated in the patent to Rowand et al. 2,289,970, of July 14, 1942. These devices separate the steam and water from the mixtures with the separated water discharging into the liquid space 80 of the drum 38, the separated steam discharging upwardly into the steam or vapor space 82 of the drum. The normal water level separating the liquid space and the vapor space is indicated at 84. From the drum liquid space 80 the separated liquid flows downwardly through appropriate downcomers, part of one of which is indicated at 86. The lower ends of such downcomers are appropriately connected, preferably by tubes and headers, to the lower or inlet ends of the various vapor generating tubes in a manner well konwn in the art.

The various vapor generating tubes above described, vapor and liquid drum 38, and the other components of the unit to be later described, are preferably pendently supported from steelwork, including such columns as are indicated at 88, and 92 in Figs. 1 and 2. This steelwork includes top girders such as indicated in Figs. 1 and 2 at 94 and 96, from which appropriate hangers 105 depend to their connections with associated tubular pressure elements.

From the vapor space 82 of the drum 38, the vapor flows through a secondary separator and then through the superheater supply tubes 112 and 114 to the superheater inlet headers 116 at opposite sides of the unit.

From the superheater inlet headers 116 steam flows downwardly through the superheater wall tubes 118 which are exposed to heat from the high temperature gases along the opposite walls of the superheater gas pass 58. These tubes communicate at their lower ends with the left hand part of the headers 120 one of which is indicated in Fig. 1 as disposed at a level below the level of the superheater gas pass 56. From the right hand parts of these headers, the steam flows upwardly through the superheater gas pass wall tubes 122 to the headers 124 likewise disposed at opposite sides of the unit. From these headers, the steam flows through a plurality of tubes or conduits 126 and 128 to the header 130 disposed at the top of the gas turning space 132 rearwardly of the superheater gas pass 58 and above the downflow gas pass 62. This header has two diverging rows of tubes 132 and 134 leading therefrom. They continue through the upright sections 136 and 138 as rows of quarter-point superheater support tubes disposed and horizontally spaced within the downflow gas pass 62 and having metallic elements secured thereto for support of the horizontal rows of the groups of horizontally disposed tubular sections 140150 of the return bend tubes of the primary superheater. These re turn bend tubes have their inlet ends connected to the header 152 which is supplied with superheated steam by the tubes or tubular sections 136 and 138.

The return bend tubes of the primary superheater have upper sections 154 extending through the gas turning space 133 and communicating with the header 156 for delivery of superheated steam thereto. From this header 156 the superheated steam flows through a plurality of conduits or tubes 158 to an attemperator 160, which may be of the type indicated in the patent to Fletcher and Huge, 2,550,683, of May 1, 1951. From the attemperator 160 steam flows through one or more lines 162 to a plurality of widely spaced upright secondary superheater inlet headers 164 which may be collectively considered as common inlet means for the multiplicity of tubes of the secondary superheater. These tubes extend as separate conduits continuously from the headers 164 to common outlet means which may be the header 166 from which the superheated steam passes to a steam turbine of a power plant or to another appropriate point of use.

Between their common inlet means, represented by inlet headers 164, and the common outlet means, represented by the header 166, the superheater tubes have successive parts arranged in different particular forms in successive zones of successively lower gas temperatures, to provide effective superheat control over a wide range of rate of vapor generation, to provide optimum heat transfer conditions under the different temperatures and solids accumulations conditions in the various temperature zones, and to provide the temperature compensating tendencies of a radiant superheater and a convection superheater in the entire flow of vapor through the superheater tubes, while, at the same time, reducing, by their particular forms, the number of costly header components which would be required in other units not having such an arrangement of superheater tubes.

The above indicated arrangements of the secondary superheater tubes may be considered as involving several groups of succeeding tubular sections. The first of these groups may be considered as group A, consisting of widely spaced platens or panels 168 distributed across the gas space of the chamber 10, as indicated in Figs. 2 and 3. The second group may be considered as the group B, including tubular sections extending in a direction transversely related to the direction of the tubular sections of the platens or panels 168, the group B being successively disposed between successive pairs of screen tube sections 72 and 74 at the top of the gas outlet of chamber 10.

The third group of tubular sections of the secondary superheater may be referred to as the group C. They are arranged as the contiguous or closely spaced tubular sections of the platens or panels 170.

The fourth group of tubular sections of the secondary superheater may be regarded as group D. These tubular sections constitute the rows of tubes 172 (Fig. 3). The spacing of the rows of tubes 172 is shown the same as the side-to-side spacing of the platens 170 of the group C and the number of upright tube sections in each row of group D is the same as the number of tubular sections in each platen or panel of group C. However, both Fig. 1 and Fig. 3 show the tubular sections of each of the rows of tubes 172 of the group D as having substantial inter-tube spaces, making the superheater section of the group D predominantly a convection superheater section, as contrasted with the predominantly radiantly heated superheater sec tion of the group A or the group C.

The fifth group of superheater tube sections of the secondary superheater may be referred to as group E. The tubular sections of each of these groups E are shown in Fig. l as extending horizontally to the right past the screen tube sections 64 and 66. These tube sections of group B preferably are arranged with the tubes in each group disposed between successive spaced pairs of screen tubes 64 and 66. These groups E include upward extensions 178 and 180 of certain tubes 174 and 176 of the group D, these extensions passing through roof portion 68 and connected in supporting relationship to the hangers 101 and 102 for afi'ording pendent support for the pertinent part of the superheater. From the positions of these connections the superheater tubes continue through the horizontal sections 182 and 184 to positions where they turn downwardly to become sections of the group F. At this position of turning, they are connected by appropriate pendent support connections with the hangers 100.

Other pendent supports for the horizontally disposed tube sections of the group B may be afforded by tube supports joined to the screen tube sections 64 and 66 and constituting arrangements such as those indicated in Figs. 5 and 6 of the drawings.

From a close inspection of Fig. 1 it will be seen that there are eight tubular sections in each row of tubes 172 of the group D. Four of these tubes in each row 172 continue as a separate row of the horizontally extending sections of the group E, thus afiording twice as many rows of tubular sections in the group B as the number of rows 172 in group D. The downflow tubular sections of the group F are individually continued through the return bends 186 and thence upwardly through the tubular sections of the group G leading to the superheater outlet header 166.

From an inspection of Figs. 1 and 3 it is not only to be noted that the number of rows of tubes in groups F and G is twice the number of rows of tubes in the group D, but also that the back spacing of the tubes in the groups F and G is substantial.

With the above indicated arrangement of the tubular sections of the groups P and G, these combined groups form a predominantly convection heated superheater section having a drooping curve temperature characteristic as the rate of vapor generation decreases. These tubular sections of the groups F and G also may be regarded as a bank of tubes with narrower intertube spaces than the spaces between the rows 172 of the group D, having an ultimate heating effect compensatory with reference to the lower temperature of the gases passing over the tubular sections of the groups F and G, as compared with the temperature of the gases passing over the tubular sections of the rows of tubes 172, the above indicated drooping curve characteristic of the groups of tubes D, E and F being compensatory, relative to the rising curve characteristic of the predominantly radiantly heated superheater sections afforded by the tube sections of platens A and C.

The tubular sections of each platen or panel 168 of the group A may be rigidly joined throughout the height of these platens, as indicated in Fig. 4. Here represen tative tubes 200202 of a platen 168 have steel rods 204 disposed there-between in the manner indicated with each rod being integrally joined to its adjoining tube metal by continuous welds (continuous throughout the height of the platen) 206. This arrangement may have such modifications that the right hand half of the total number of tubular sections in each platen of group A are united as indicated in Fig. 4 as a unit separate from the remainder of the tubular sections in the same platen. The first separate unit may have one of its tubular sections 208 extended through the roof 44 of the chamber 10 to a position 210 (see Fig. 1) where it is connected for pendent support to one of the hangers 104. Thence this tubular section continues through the upwardly inclined section 212 at the right hand end of the roof section 44 where it has connection with one of the hangers- 103. Thence it continues downwardly from the roof 44 and becomes one of the tubular sections of one of the platens of the group C. Similarly, another unit of the same platen of the group A has an upward extension 214 to the roof 44 where it is joined to the hanger 105. Thence it continues from the upwardly inclined section 216 to a position indicated at 218 Where it is joined to one of the hangers 103. Thence it continues downwardly as a part of one of the platens 170 of group C.

Figs. 5 and 6 indicate an arrangement of elements whereby the inclined tubular superheater sections of group B are supported by screen tubes 72 and 74. The tube 72 in Figs. 5 and 6 has inclined studs 220 welded thereto, each stud having a recess to receive one of the tubes 222 of the group of tubular sections B, each tube having welded to its lower side a bar section 224 which abuts against the lower part of the stud 220 as indicated in Fig. 5 to prevent the tubular sections of group B from sliding with respect to the studs 220.

Whereas the invention has been described with reference to the details of structures indicating preferred embodiments of the invention, it is to be appreciated that the invention is not limited to all of the details described. It is rather to be considered as commensurate with the scope of the subjoined claims.

I claim:

1. In a vapor generating and superheating unit having roof and wall means defining a vertically elongated radiation chamber having a gas outlet at one side of the upper part thereof and a laterally extending gas pass connected to said gas outlet, a combination radiant and convection vapor superheater comprising a predominantly radiant section formed by a first group of vertical tube panels relatively widely spaced transversely of said radiation chamber and extending in front of said gas outlet, each of said panels being formed by a row of closely spaced vertically extending tubes having their upper end portions bent laterally and arranged in two diverging tube groups extending into said gas pass below said roof, a second group of vertical tube panels in said gas pass having a transverse spacing substantially one-half that of the first group of tube panels, each of said second group tube panels being formed by a row of closely spaced vertically extending tubes connected at their upper ends to and forming a continuation of the tubes of a corresponding diverging tube group and having their lower ends bent laterally within said gas pass, a predominantly convection superheater section comprising a third group of vertical tube panels in said gas pass downstream of said second group and having a transverse spacing similar to the spacing of said second group, each of said third group tube panels being formed by a row of vertical tubes having their lower ends connected to and forming a continuation of the bent lower ends of corresponding tubes in said second group panels, said third group tube panel rows having a substantially greater tube-to-tube spacing than the tubes in the first and second group panels, whereby a plurality of parallel continuous uninterupted vapor flow passages are provided through said first, second and third groups of tube panels, means for pendently supporting the first group of tube panels and means for pendently supporting said third group of tube panels.

2. In a vapor generating and superheating unit having roof and wall means defining a vertically elongated radiation chamber having a gas outlet at one side of the upper part thereof and a laterally extending gas pass connected to said gas outlet, a transverse row of vertical vapor generating tubes extending across said gas outlet, a combination radiant and convection vapor superheater comprising a predominantly radiant section formed by a first group of vertical tube panel relatively widely spaced transversely of said radiation chamber and extending in front of said gas outlet, each of said panels being formed by a row of closely spaced vertically extending tubes having their upper end portions bent laterally below said roof and arranged in two diverging tube groups extending between said vapor generating tubes, a second group of vertical tube panels in said gas pass having a transverse spacing substantially one-half that of the first group of tube panels, each of said second group tube panels being formed by a row of closely spaced vertically extending tubes connected at their upper ends to and forming a continuation of the tubes of a corresponding diverging tube group and having their lower ends bent laterally within said gas pass, a predominantly convection superheater section comprising a third group of vertical tube panels in said gas pass downstream of said second group and having a transverse spacing similar to the spacing of said second group, each of said third group tube panels being formed by a row of vertical tubes having their lower ends connected to and forming a continuation of the bent lower ends of corresponding tubes in said second groups panels, said third group tube panel rows having a substantially greater tube-to-tube spacing than the tubes in the first and second group panels, whereby a plurality of parallel continuous uninterrupted vapor flow passages are provided through said first, second and third groups of tube panels, means for pendently supporting the first group of tube panels, means for supporting said diverging tube groups from adjacent vapor generating tubes, and means for pendently supporting said third group of tube panels.

3. In a vapor generating and superheating unit having roof and wall means defining a vertically elongated radiation chamber having a gas outlet at one side of the upper part thereof and a laterally extending gas pass connected to said gas outlet, a transverse row of vertical vapor generating tubes extending across said gas outlet, a radiant vapor superheater formed by a first group of vertical tube panels spaced transversely of said radiation chamber and extending in front of said gas outlet, each of said panels being formed by a row of vertically extending tubes having their upper end portions bent laterally below said roof and arranged in two diverging tube groups extending between said vapor generating tubes, a second group of vertical tube panels in said gas pass, each of said second group tube panels being formed by a row of vertically extending tubes connected at their upper ends to the tubes of a corresponding diverging tube group, means for pendently supporting the first group of tube panels comprising spaced tubes of each panel of said first group projecting through and extending along said roof and thence downwardly along corresponding second group tube panels, and suspension means engaging the projecting portions of said tubes.

4. In a vapor generating and superheating unit having roof and wall means defining a vertically elongated radiation chamber having a gas outlet at one side of the upper part thereof and a laterally extending gas pass connected to said gas outlet, a radiant vapor superheater formed by a first group of vertical tube panels relatively widely spaced transversely of said radiation chamber and extending in front of said gas outlet, each of said panels being formed by a row of vertically extending tubes having their upper end portions bent laterally below said roof and arranged in two diverging tube groups extending into said gas pass below said roof, a second group of vertical tube panels in said gas pass having a transverse spacing substantially one-half that of the first group of tube panels, each of said second group tube panels being formed by a row of vertically extending tubes connected at their upper ends to the tubes of a corresponding diverging tube group, means for pendently supporting the first group of tube panels comprising spaced tubes of each panel of said first group projecting through and extending along said roof and thence downwardly along corresponding second group tube panels, and suspension means engaging the projecting portions of said tubes.

5. In a vapor generating and superheating unit having roof and wall means defining a vertically elongated radiation chamber having a gas outlet at one side of the upper part thereof and a laterally extending gas pass connected to said gas outlet, a transverse row of vertical vapor generating tubes extending across said gas outlet, a radiant vapor superheater formed by a first group of vertical tube panels relatively widely spaced transversely of said radiation chamber and extending in front of said gas outlet, each of said panels being formed by a row of vertically extending tubes having their upper end portions bent laterally below said roof and arranged in two diverging tube groups extending between said vapor generating tubes, a second group of vertical tube panels in said gas pass having a transverse spacing substantially one-half that of the first group of tube panels, each of said second group tube panels being formed by a row of vertically extending tubes connected at their upper ends to the tubes of a corresponding diverging tube group, means for pendently supporting the first group of tube panels comprising spaced tubes of each panel of said first group projecting through and extending along said roof and thence downwardly along corresponding second group tube panels, suspension means engaging the projecting portions of said tubes, and means for supporting said diverging tube groups from adjacent vapor generating tubes.

6. In a vapor generating and superheating unit having roof and wall means defining a vertically elongated radiation chamber having a gas outlet at one side of the upper part thereof and a laterally extending gas pass connected to said gas outlet, a radiant vapor superheater formed by a first group of vertical tube panels relatively widely spaced transversely of said radiation chamber and extending in front of said gas outlet, each of said panels being formed by a row of closely spaced vertically extending tubes having their upper end portions bent laterally and arranged in two diverging tube groups extending below and along said roof, a second group of vertical tube panels in said gas pass having a transverse spacing substantially one-half that of the first group of tube panels, each of said second group tube panels being formed by a row of closely spaced vertically extending tubes connected at their upper ends to the tubes of a corresponding diverging tube group, means laterally connecting tubes in each of said first group tube panels in a substantially rigid construction, andmeans for pendently supporting the first group of tube panels comprising laterally spaced tubes of each panel of said first group projecting through and extending along said roof and thence downwardly to and along corresponding second group tube panels, suspension means engaging the projecting portions of said tubes.

7. In a vapor generating and superheating unit having roof and wall means defining a vertically elongated radiation chamber having a gas outlet at one side of the upper part thereof and a laterally extending gas pass connected to said gas outlet, a transverse row of vertical vapor generating tubes extending across said gas outlet, a radiant vapor superheater formed by a first group of vertical tube panels relatively widely spaced transversely of said radiation chamber and extending in front of said gas outlet, each of said panels being formed by a row of vertically extending tubes having their upper end por- 16' tions bent laterally below said roof and arranged in we diverging tube groups extending between said vapor generating tubes, a second group of vertical tube panels in said gas pass having a transverse spacing substantially one-half that of the first group of tube panels, each of said second group tube panels being formed by a row of vertically extending tubes connected at their upper ends to the tubes of a corresponding diverging tube group, means laterally connecting tubes in each of said first group tube panels in a substantially rigid construction, means for pendently supporting the first group of tube panels comprising laterally spaced tubes of each panel of said first group projecting through and extending along said roof and thence downwardly to and along corresponding second group tube panels, suspension means engaging the projecting portions of said tubes, and means for supporting said diverging tube groups from adjacent vapor generating tubes.

References Cited in the file of this patent UNITED STATES PATENTS 1,959,866 Jacobus May 22, 1934 2,308,762 Krug et al Jan. 19, 1943 2,685,279 Caracristi Aug. 3, 1954 FOREIGN PATENTS 709,317 Great Britain May 19, 1954 1,065,655 7 France Jan. 13, 1954

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