US2045145A - Superheater boiler - Google Patents

Description

June 23, 1936. D. s. JACOBUS ET AL SUPERHEATER BOILER Filed Dec. 1, 1925 4 Sheets-Sheet 1 M 1; w M

BY I

hwmvzm v June 23, 1936- D; s. JACOBUS ET AL 2,045,145

SUPERHEATER BOILER Filed Dec. 1, 1925 4 Sheets-Sheet 2 11v VENTORS ATTORNEYS June 23, 1936. D. s. JACOBUS ET AL 2,045,145

SUPERHEATER BOILER I Filed Dec. 1, 1925 4 Sheets-Sheet 3 ATTORNEYS June 1936. D. s. JACOBUS ET AL 2,045,145

S UPERHEATER BOILER 4 Shets-Sheet 4 Filed Dec. 1, 1925 ig'E- Fig 7 Fig 8- Fig-'5.

INVENTORJ wall Fig 5- M A TTORNE y:

Patented June 23, 1936 UNITED STATES PATENT OFFICE SUPERHEATER BOILER Application December 1, 1925, Serial No. 72,423

40 Claims. (01. 122-403) This invention relates to a steam boiler which has superheaters or reheaters, and will be undersection on an enlarged scale showing the upper portion of Fig. 1; Fig. 3 is a plan view, partly in section, of a part of Fig. 2, showing the water circulators and their connections to the headers and the steam and water drum; Fig. 4 is a front elevation of Fig. 3, partly in section, showing the secondary superheater; Fig.' 5 is an enlarged view in elevation showing how the secondary superheater headers are supported; Fig. 6 is a side elevation, on an enlarged scale, showing the secondary superheater tube supports; Fig. 7 is an end view of Fig. 6; Fig. 8 is a plan view of the same; Fig. 9 is a side view showing a part of one 01 the details; Fig. 10 is a side view of a metal plate for holding the tile of one of the'b'aflles shown in Fig. l, and Fig. 11 is a section along the line I l-l l of Fig. 10.

Like reference characters indicate like parts in the vdiilerent views. p

In the drawings, reference character In indicates the furnace of a boiler in which an underfeed stoker II is located. A bank of inclined tubes l2'oi. the boiler proper is connected to headers l4 and I5 and a second bank of inclined tubes H of the boiler is connected to headers l6 and H, the headers l4 and I6 being connected by nipples l8 and the headers I5 and I! being connected by nipples l9. Nipples 2| connect the headers I6 to the steam and water drum 23, the upper ends of alternate nipples being bent in one direction, and the remainder in the opposite direction, to enter the drum 23 in two parallel rows, as indicated. Nipples 22 connect the headers H to the headers 24. A feed water inlet 25 for the drum 23 is shown and a steam outlet 26 from the drum leads to the header 21 of the primary superheater 28. The tubes 01' this superheater have a reverse bend and are connected to the outlet header 29.

A baflle 3| is placed near the lower end of the bank of tubes l2 along the upper side of the bank and a plurality of supports 32 for the superheater 23 is mounted upon these tubes. A baflle 33 prevents contact of the hot gases with the header 2! and a similar baffle 34 prevents contact of the gases from the first upward pass with the header A flat suspended arch of tile 44 extends above part of the length 01" the superheater tubes 28,

the tile being supported on a pluraity of metal plates 35, each having one end supported on clips on nipples I8 and the other bolted to a fin integral with header 29. An upwardly extending fln 30' on the header 29 is similarly bolted to the plates forming the transverse baiile 48, these plates having notches along their edges engaging tubes l3 in the same manner that plates 80 engage tubes 60, as hereinafter described.

Each metal plate 35 (Figs. 1, 10 and 11-) for holding tile 44 is provided with a flange 36 at one end thereof and a similar flange 31 near the opposite end. Strengthening ribs 38 are provided on the topside of the plate 35 for the rib 31 and a longitudinal strengthening rib 39 extends along the middle of the topside of the plate 351mm the flange 36 to the flange 3I. A transverse flange 40 extends across the lower side of the plate 35'and a strengthening rib 4| is provided therefor. A bulbed rib 42 extends longitudinally of the plate 35 on the lower side thereof from the flange 40 to the end of the plate. This bulbed rib is provided with a beaded edge 43 engaging grooves inthe tile 44 to hold the same in position in the wellknown way. The arch, is inclined and the horizontal thrust of the rows of tile II is against the flanges 49.

A baiile 48 is provided with a seat 49 along its upper edge for the lower movable batlle plate that is to be-described.later. Another bame 59 extends across the bank of tubes l3, from. the upper edge of which a bafllle wall 5| extends to the lower side of a bank of circulating tubes 53. A baiile 52 extends across the bank of circulating tubes to the roof 53, and a gas outlet is shown at 54. The bank of circulating tubes 55 connects the steam and water drum 23 to the headers 24. These tubes 55 enter the drum 23 radially along circumferential lines, the lowest tubes being straight and the others being slightly bent at the ends where they enter the drum 23. The other ends of these tubes 55 are offset longitudinally of the drum 23, as shown in Fig.3, so that the alternate ones in a vertical row enter adjacent headers 24 and 24'. By the" arrangement illustrated, each header is connected to the drum by a pair of tubes and yet the tube holes are spaced along the drum so as to give a greater ligament strength than it. the tubes were arranged with the spacing of the tubes longitudinally of the drum the same as the spacing of the headers. It will be understood that a continuous water box may be used instead of the separate headers lllustrated, such a set of headers or a continuous water box constituting an uptake water chamber.

It will be understood therefore, that when I refer in the claims to a row of water chambers arranged in a row extending longitudinally of the drum, I intend to cover continuous water boxes.

A heat transfer device which, in the embodithe other side of the boiler and located in a higher plane than the header 58. Tubes 68 are connected to the upper side of the header 58 along and on both sides of the central longitudinal line thereof, and extend to the lower side of the header 6| to which they are connected in a manner similar to the way they are connected to the upper side of header 58. These tubes are bent in vertical planes near their ends, so that the medial portions thereof will be horizontal, each tube being somewhat S-shaped. A steam pipe 62 connects the header 6| to the header 63, which is located at the same level as the header 58, and is displaced longitudinally of the headers 58 and 6|, asshown in Fig. 5. A bank of tubes 64 similar to the bank of tubes 68 connects the header 63 to the header 65, similar to the way headers 58 and 6| are connected. The header 65 header 65. Beams 68 extend above the top of the boiler from front to rear, and I-beams I8 and channel bars H are laid transversely across the same. Straps I2, 13, 14 and 15 extend from the channel bars 1| around the headers 65, 63, 6| and 58 respectively, and support the same, nuts being screwed on to the threaded upper ends of these straps to adjust the headers to the proper positions. Supporting rods 18 extend from the I- beams 18 and are connected to metal bars 19 (Figs. 2, 6, 7 and'8) to which metal supports 88 for tubes 68 and 64 are fastened on opposite sides thereof by means of bolts 8| in staggered relation. The supports 88 are provided with recesses 82 along the edges thereof, large enough for the tubes to enter. Bars 83 similar to bars IQ-are connected to the supports 88 by bolts 8|.

' rowly spaced tubes, and each of the supports 88 Preferably, the tubes in each horizontal row are spaced, as shown, with alternately wide and narrow spaces, so that the wide spaces will permit the passage of a tube in withdrawing and replacing the same, the distance between the tubes atthe wide spacing being slightly larger than the diameter of a tube. spondingly arranged to support the tubes as thus spaced, each of the supports 88 on one side of the metal bars I9 coming between a pair of naron the other side between a pair of widely spaced tubes.

By having supports 88 alternately on opposite sides of bars 19, they may be more readily attached to bars 19 and may more readily be turned into and out of position between a pair of vertical rows of tubes.

The upper and lower bars 19 and 83 with their connected supports 88 constitute a relatively stiff support for the tubes. of,the secondary superheater and yet one which can be readily con- I structed after the tubes are in place, each of the 68 and 64.

that the steam entering reheater header 58 and passing first through the set of tubes and later The supports 88 are corre-- supports for the headers.

between a pair of vertical rows of tubes and then turned into position with each of its recesses 82 surrounding a tube, and the support is then bolted in place to the bars 19 and'83.

A movable baflle 85 (Figs. 1, 2 and 4) is located 5 parallel with and between the two sets of tubes This baflle is provided with notches or recesses 86 along its upper edge to permit it to be raised among the tubes 55, as most clearly shown in Fig. 4. The lower ends of the lifting rods 81 are attached to the baflie 85 and pass through the roof 53 of the boiler setting, and are connected to the elevating mechanism 88 which is supported on channel irons 89 that rest upon the beams 69. A shaft 88 driven from any convenient source operates the mechanism for-raising and lower the rods 81.

In operation, hot gases from the furnace l8 (see Fig. 1) pass upwardly into contact with the lower bank l2 of inclined water tubes and across the 20 same into contact with the long ends of the superheater tubes 28, being prevented from contacting with the header 2! of said superheater by means I of the baflies 3| and 33. The baifle 44 deflects the gases so that they pass across the short ends of 25 the superheater tubes 28, being prevented from contacting with the header 29 by means of the baflle 34. The gases then pass across the bank of tubes |3 between the baffle 48 and the headers |'I, thence, when the bafile 85 is in its lowermost 30 position, across the set of reheater tubes 84, thence longitudinally along the circulating tubes 55 over the top edge of the baflie 85, thence downwardly across the set of reheater tubes 68 and across the bank of tubes i3, under the lower 35 edge of the baiile 58, across the ends of the circulating tubes 55 and to the outlet 54. When the bailie 85 is raised to leave a space between its lower edge and the upper edge of the baflie 48, a portion of the gases passes through this space without contacting with the tubes 64 or 68. The

- higher the baiiie 85 is raised, the more of the gases on the seat 49, battle 85 in the position of Fig. 1-

forming a continuation of baflle 48. It is noted through the set 64 of tubes flows in a generally countercurrent direction with respect to the hot gases. The side walls 9| and 92 of the flue (Fig.

4) are located between the headers of the super- 55 heater so that the hot gases do not contact with these headers.

By providing the two sets of tubes 68 and 64 with the separate headers therefor, great flexibility is obtained, which is desirable because of different amounts of expansion which may occur in the two sets of tubes due to the difference in temperature of the gases to which they are subjected. The pipe 62 is made of such a character that it willpermit the headers 6| and 63 to have the necessary amount of relative movement. By arranging the headers-in different planes, as illustrated, the sets of tubes 68 and 64 may be brought close together and yet the respective headers may be made long enough to provide space for the various pipe connections and the If the two banks 68 and 64 were alike, headers 6| and 63, for instance, would be in axial alinement and the presence of the necessary rounded ends of the headers would then necessitate the spacing of the two sets of tubes 80 and 64 relatively widely apart, which the arrangement illustrated avoids;

By providing the separate supports for the headers and the tubes of the secondary superheater or reheater, a maximum freedom of motion for the various parts is permitted-while, at the same time, providing adequate support for each part,. Each header is free to move independently of the other headers and the tubes are free to expand and contract by movement through the recesses 82 of supports 80, the bending of the tubes at each end also permitting difference in expansion in the several tubes without placing undue strain on the connections between the ends of the tubes and the headers.

We claim;

1. In a boiler, ahorizontal cylindrical drum,a plurality of vertically disposed headers in a row extending longitudinally of the drum and spaced therefrom, and tubes connecting said headers and said drum, said tubes being arranged in a plurality of horizontal rows, the ends of a pair of tubes, one each from a pair of adjacent horizontal rows, entering the drum on substantially the same drum circumference and the other end of each of said pair of tubes entering respectively one of an adjacent pair of headers, the tubes of each pair entering headers at different elevations.

2. In a boiler, a horizontal cylindrical drum, a plurality of vertically disposed headers in a row extending longitudinally of the drum and spaced therefrom, and tubes connecting said headers and said drum, said tubes being arranged in a plurality of horizontal rows, the ends 'of a pair of tubes, one each from a pair of adjacent horizontal rows, entering the drum radially on substantially the same drum circumference and the other end of each of said pair of tubes entering respectively one of an adjacent pair of headers, the entrance points in said adjacent pair of headers being at different elevations.

3. In a boiler, a horizontal cylindrical drum, a plurality of vertically disposed headers in a row located longitudinally of the drum and spaced therefrom, and tubes connecting said headers and said drum, said tubes being arranged in a plurality of horizontal rows, the ends of a pair of tubes, one of which is a tube of one of said horizontal rows and another is a tube of an adjacent row of' said horizontal rows, entering the drum on substantially the same drum circumference and the other end of each of said pair of tubes entering respectively one of an adjacent pair of headers and each header having at least two of said tubes entered therein.

4. In a boiler, a horizontal cylindrical drum,

'water chambers arranged in a row extending longitudinally of the drum and spaced therefrom and a plurality of rows of tubes connecting said chambers and said drum, the ends of a pair of tubes each in a pair of adjacent horizontal rows entering the drum in substantially the same drum circumference and the other ends of said pair of tubes being bent in opposite directions and entering said water chambers through openings which are out of either vertical or horizontal alinement. 5. In a water tube boiler, a heat transfer device having a bank of horizontally extending tubes arranged in a plurality of horizontal rows, headers connected to the ends of said tubes, a fixed support above the tubes, and suspension devices for the portion of the tubes between the headers, comprising a plurality of vertically disposed plates extending across said bank and having recesses along their edges, with one of said tubes in each recess, a top and a bottom horivice having a bank of horizontally extending tubes arranged in a plurality of horizontal rows, headers connected to the ends,of said tubes, a fixed support above the tubes, and suspension devices for the portion of the tubes between the headers, comprising a plurality of vertically disposed plates extending across said bank and having recesses along their edges, with one of said tubes in each recess, said plates being arranged in a row extending across the'bank, with alternate plates out of alinement with the plates at either side and overlapping the edges thereof, whereby each tube is positioned in the oppositely extending recesses of a pair of adjacent plates, and suspension members connecting the tops of said plates with said support.

7. In a water tube boiler, a heat transfer device having a bank of horizontally extending tubes arranged in a plurality of horizontal rows, headers connected to the ends of said tubes, a fixed support above the tubes, and suspension devices for the portion of the tubes between the headers, comprising a plurality of vertically disposed plates extending across-said bank and having recesses along their edges, with one of said tubes in each recess, said plates being arranged in a row extending across the bank, with alternate plates out of alinement with the plates at either side" and overlapping the edges thereof, whereby each tube is positioned in the oppositely extending recesses of a pair of adjacent plates, a top and a bottom horizontal bar respectively above and below said bank and connected respectively to the top and the bottom of said plates, and a plurality of suspension members connecting said top horizontal bar with said support.

8. In a water tube boiler, horizontally inclined water tubes, uptake and downtake water chambers connecting the ends of said tubes, a steam and water drum connected to said chamber, cross baiiies to direct the furnace gases back and forth across the water tubes, a heat transfer device above-the water tubes and having two banks of tubes side by side and extending across the water tubes in the path of the furnace gases and a header for each end of each of said banks of tubes of said device and connected to the ends of the tubes in a bank, said headers being'structurally independent of each other, a fluid outlet and a fluid inlet respectively in the headers of said device at one side of; the boiler and a connection between the headers at the other side of the boiler, said inlet, outlet and connection being arranged to cause the fluid to flow in said device first through the tubes contacted by'the cooler furnace gases and then through the tubes contacted by the hotter furnace gases, and a vertically disposed and vertically movable bai'fle between said banks to regulate the flow of gases thereover.

9. In a water tube boiler, horizontally inclined water tubes, uptake and downtake water chambers connecting the ends of said tubes, a transverse steam and water drum above the downtake water chambers, substantially horizontal water circulating tubes extending from said drum to said uptake water chambers, cross bailies to direct the furnace gases back and forth across the water tubes, 2. heat transfer device having two banks of tubes side by side and extending transversely of the water tubes and between the water tubes and said circulating tubes in the path of the furnace gases, a header for each end of each of said banks of tubes of said device and connected to the ends of the tubes in a bank, said headers being structurally independent, and a vertically disposed and vertically movable baflle between said banks to regulate the flow of gases thereover, said vertically movable baflle being arranged, when in its lowermost position, to direct the gases up over the tubes of one of said banks, through the space through which said circulating tubes extend and then down over the tubes of said second bank.

10. In a water tube boiler, horizontally inclined water tubes, uptake and downtake water chambers connecting the ends of said tubes, a transverse steam and water drum above the downtake water chambers, substantially horizontal water circulating tubes extending from said drum to said uptake water chambers, cross baflies to direct the furnace gases back and forth across the water tubes, a heat transfer device having two banks of tubes side by side and extending transversely of the water tubes and between the water tubes and said circulating tubes in the path of the furnace gases, a header for each end of each of said banks of tubes of said device and connected to the ends of the tubes in a bank, said headers being structurally independent, and a vertically disposed and vertically movable baflle between said banks to regulate the flow of gases thereover, said vertically movable baflle being arranged, when in its lowermost position, to direct the gases up over the tubes. of one of said banks, through the space through which said circulating tubes extend and then down over the tubes of said second bank, said vertically movable baflie having recesses in its upper edge to receive said circulating tubes when it is moved to its uppermost position to permit the gases to flow through a portion of one bank directly into a portion of the other bank.

11. In a boiler, upper and lower banks of horizontally inclined water tubes spaced apart to form a superheater chamber therebetween, uptake and downtake water chambers connected to the ends of said water tubes, a superheater in said chamber having headers extending transversely of the water tubes and U-tubes connecting said headers and extending parallel to the water tubes, the legs of said U-tubes being unequal in length with the upper legs the shorter and the header connected to the long legs adjacent one of the water chambers and the header connected to the short legs remotetherefrom, and a baffle entirely within said chamber and extending from said water chamber to and supported on the header connected to the short leg of the superheater tubes, said bafile comprising a plurality of metal supports and tile connected to the lower side thereof.

12. In a boiler, upper and lower banks of horizontally inclined water tubes spaced apart to form a superheater chamber therebetween. uptake and downtake water chambers connected to the ends of said water tubes, cross baffles in the upper bank to direct the furnace gases from the superheater chamber back and forth across the water tubes of the upper bank, a superheater in said chamber having an upper transverse header positioned adjacent the lower edge of the cross bame separating the first up-pass from the first down-pass across the upper bank of water tubes, 9. lower transverse header adjacent one of said wa-. ter chambers, U-tubes with legs of unequal length connecting said headers, and a baflle extending from said upper superheater header to said downtake water chambers, beneath said first downward pass and separated from the upper bank of water tubes and also separated from the longer legs of said U-tubes.

13. In a boiler, upper and lower banks of horizontally inclined water tubes spaced apart to form a superheater chamber therebetween, uptake and downtake water chambers connected to the ends of said water tubes, cross baiiies in the upper bank to direct the furnace gases from the superheater chamber back and forth across the water tubes of the upper bank, a superheater in said chamber having an upper transverse header positioned adjacent the lower edge of the cross baflle separating the first up-pass from the first down-pass across the upper bank of water tubes, a lower transverse header adjacent one of said water chambers, U-tubes with legs of unequal length connecting said headers, and a bailie extending from said upper superheater header to said downtake water chambers beneath said first downward pass and separated from the upper bank of water tubes, said baflle being also separated from the longer legs of said U-tubes and having one end supported on said upper header and said upper header being connected to and supported by the cross baflie above it.-

M. In a boiler, a cylindrical drum, a plurality of headers arranged in a row extending longitudinally of the'drum and spaced therefrom, and tubes arranged throughout their entire lengths in a plurality of rows extending longitudinally of the drum and connecting said headers and said drum, the tubes entering the drum along circumferential lines which are farther apart than the center line distances between the headers, the ends of said tubes being staggered where ,they enter the headers.

15. In a boiler, a cylindrical drum, a plurality of headers arranged in a row extending longitudinally of the drum and spaced therefrom, and tubes arranged throughout their entire lengths in a plurality of rows extending longitudinally of the drum and connecting said headers and said drum, the tubes entering the drum radially along circumferential lines which are farther apart than the center line distances between the headers, the ends of said tubes being staggered where they enter the headers.

16. In a boiler, a cylindrical drum, a plurality of headers arranged in a row extending longitudinally of the drum and spaced therefrom, and tubes arranged throughout their entire lengths in a plurality of rows extending longitudinally of the drum and connecting said headers and said drum, the tubes entering the drum along circumferential lines which are twice as far apart as the center line distances between the headers, the ends of said tubes being staggered where they enter the headers.

1'7. Ina water tube boiler and its furnace, a heat transfer device having tubes extending across the boiler tubes, said tubes being divided vertically into two banks across which the gases from said furnace flow, headers connected to the ends of the tubes of said heat transfer device with a header at a first side of said boiler connected through tubes of one bank to a header at the second side of the boiler located at a different elevation than said first header and through which the fiuid flows, thence through a connection to a header at said second side of the boiler located at substantially the same elevation as said first mentioned header, and thence through the second bank of tubes to the other header located at said first side of the boiler.

18. In a water tube boiler and its furnace, a heat transfer device having tubes extending across the boiler tubes, said tubes being divided vertically into two banks located at substantially the same elevation and across which the gases from said furnace fiow, headers connected to the ends of the tubes of said heat transfer device with a header at a first side of said boiler connected through tubes of one bank to a header at the second side of the boiler located at a different elevation than said first header, thence through a connection to a header at said second side of the boiler located at substantially the same elevation as said first mentioned header, and thence through the second bank of tubes to the other header located at said first side of the boiler.

19. In a water tube boiler, a bank of inclined tubes, spaced 'apartupper circulating tubes, a superheater located between said bank and said circulating tubes, means to pass hot gases over said superheater and steam through said superheater in countercurrent directions, and means to by-pass different portions of said hot gases under different conditions of operation to cause only the remaining portion of said gases to cross said superheater tubes.

20. In a water tube boiler, a bank of inclined tubes, spaced apart upper circulating tubes, a multiple pass superheater located between said bank and said circulating tubes, means to pass hot gases over said superheater and steam through said superheater in countercurrent direction, and means to by-pass portions of said hot gases under different conditions of operation to cause only the remaining portion of said gases to cross said superheater tubes.

21. In a water tube boiler, a bank of inclined tubes, spaced apart upper circulating tubes, a superheater located between said bank and said circulating tubes, means to pass hot gases over said superheater and inclined tubes in a plurality of passes and into contact with said circulating tubes between said passes, and means to by-pass different portions of said hot gases under difierent conditions of operation to cause only the remaining portion of said gases to cross said superheater tubes. e

22 In a water tube boiler, a bank of inclined tubes, spaced apart upper circulating tubes, a superheater located between said bank and said circulating tubes, means to pass hot gases over said superheater and steam through said superheater in countercurrent directions, and means to by-pass a portion of said hot gases so as to cross only a portion of said superheater tubes, said last named means comprising a vertically movable bafiie.

23. In a water tube boiler, a bank of inclined tubes, spaced apart upper circulating tubes, a superheater located between said bank and said circulating tubes, means to pass hot gases over said superheater and steam through said superheater in countercurrent directions, and means to by-pass a portion of said hot gases, said last named means comprising a battle located near the middle ofjsaid superheater and adapted to be moved across said circulating tubes.

24. In a water tube boiler, a bank of inclined tubes, spaced apart upper circulating tubes, a superheater located between said-bank and said 6 circulating tubes, means to pass hot gases over said superheater and steam through said superheater in countercurrent directions, and means to by-pass difierent portions of said hot gases under different conditions of operation to cause only the remaining portion of said gases to cross said superheater tubes, the tubes of said superheater extending substantially at right angles to said bank of tubes.

25. In a water tube boiler, a bank of inclined 15 tubes, spaced apart upper circulating tubes, a superheater located between said bank and said upper circulating tubes, means to pass hot gases over said superheater and inclined tubes in a plurality of passes, and means to by-pass different 20 portions of said hot gases under difierent condi-- tions of operation to cause only the remaining portion of said gases to cross said superheater tubes.

26. In a water tube boiler, a steam and water 25 drum, horizontally disposed water circulating tubes connected to said drum, a heat transfer device below said tubes having tubes extending transversely of said circulating tubes, a baflie extending between tubes of said heat transfer device, and means for moving said bafile across tubes of said circulating tubes.

27. In a water tube boiler, a steam and water drum, horizontally disposed water circulating tubes connected to said drum, a heat transfer 35 device below said tubes having tubes extending transversely of said circulating tubes, a baflle extending between tubes of said heat transfer device, said baiile having notches therein, and means for moving said baflie across tubes of said 40 circulating tubes.

28. A heat transfer device comprising two adjacent banks of tubes, a header to which the tubes of the first of said banks of tubes are connected, said header being located at one end of said banks of tubes outside of the planes bounding the main portions of said tubes, a second header to which the other ends of the tubes of the first bank are connected, said second header being located at the other end of said banks of tubes on the other 50 side of said bounding planes from said firstnamed header, a third header to which the tubes of the second bank of tubes are connected, said third header being located at the same end of said banks as said second header and on the opposite side of said bounding planes from it, and a fourth header to which the other ends of the tubes of the second bank of tubes are connected, said fourth header being located at the same end 60 of said banks as said first header and on the opposite side of said bounding planes from it, and means to cause fluid to enter said first header and leave said fourth header.

29. In a heat transfer device, a plurality of 65 banks of tubes having their ends bent in opposite directions, headers to which said tubes are connected so located that there is a pair of headers at each end of said banks, and a pair of headers at -each side of said banks, the headers 7 at each end of said banks being displaced longitudinally with respect to each other, the tubes of one bank being connected to a header at each end and a header at each side of said banks, and

the tubes of another bank being connected to 75 headers alternating with the headers of thefirst bank.

30. In a boiler having two vertically spaced banks of horizontal tubes, the combination with said banks, of a baffle between and parallel to them and spaced from both of them, and supports for said baffle hung from tubes in the upper bank.

31. In a boiler, in combination, a bank of horisontal water tubes, a bar transverse to the water tubes and below'them, means supporting said bar and engaging and supported by some of the water tubes, an aligned series of bars parallel to the water tubes and suspended from the first named bar, and fire-resisting blocks suspended from said second-named bars contacting with each other and forming a continuous baiile.

32. The combination set forth in claim 31, said secondmamed bars having longitudinal horizontal opposite flanges along their lower edges, and said blocks being suitably slotted to slip on and hang from said flanges.

33. In a boiler, the combination of two spaced banks of horizontal tubes, rods extending through the upper bank, means to support said rods, said means engaging the top tubes of the upper bank, a bar transverse to the water tubes suspended from the rods in the inter-bank space, a set of aligned bars parallel to the tubes suspended from said first named bar, said second bars having an inverted T-shaped cross section, and fire bricks contacting with each other to form a continuous baffle, said bricks beingslotted so as to slip on and hang from said second bars.

34. In a water tube boiler, spaced banks of tubes with a tubular heater therebetween, a furnace on the opposite side of one of said banks from said heater, a baflle extending across said banks and said heater to form a pass for gases from the furnace, said baflle being of less extent lengthwise of the pass than the total distance across said banks and heater and spaces therebetween whereby said gases may flow out of the pass transversely thereof, and means for moving a part of said banle to vary'the'loeation at which said transverse flow out of the pass may take place.

35. In a water tube boiler, spaced banks of tubes with a tubular heater therebetween, a furnace on the opposite side of one of said banks from said heater, a baflle extending across said banks and said heater to form a pass for gases from the furnace, said baiiie being of less extent lengthwise of the pass than the total distance acrosssaid banks and heater and spaces therebetween whereby said gases may flow out of the pass transversely thereof, and means for moving a part of said baiile in its plane to vary the location at. which said transverse flow out of the pass may take place.

38. In a water tube boiler, spaced banks of tubes with a tubular heater therebetween, a furnace on the opposite side of one said banks from said heater, a baille extending across said lastnamed bank of tubes and into said heater to form a pass for gases from said furnace extending towards the other bank of tubes, whereby said gases may flow over part of the tubes in said other bank, means to move a portion of said battle to form an opening in the bame between the heater and the bank of tubes nearest the furnace.

37. In a water tube bofler, spaced banks of tubes with a tubular heater therebetween, a furnace on the opposite side of one of said banks from said heater, a baille extending across said last-named bank of tubes and into said heater to form a pass for gases from said furnace extending towards the other bank of tubes, whereby said gases may flow over part of the tubes in said other bank, means to move a portion of said baille to form an opening in the baille between said banks of tubes.

38. In a steam boiler, spaced banks of boiler tubes, a primary superheater interposed between said banks, a reheater above said banks, means I for passing the gases over said primary superheater and said reheater, means comprising a bailie movable across said reheater for increasing or decreasing the temperature of said reheater without materially aifecting the temperature of said superheater, and means for causing the gases to engage all of the superheater tubes across the boiler substantially uniformly under every condition of operation.

39. In a steam boiler, spaced banks of boiler tubes, a primary superheater interposed between said banks, a reheater above said banks, means for passing the gases over said primary superheater and said reheater, means comprising a baflle movable across said reheater for increasing or decreasing the heat applied to said reheater without materially varying the heat applied to said superheater, and means for causing the gases to engage all of the superheater tubes across the boiler substantially uniformly under every condition of operation.

40. In a steam boiler, spaced banks of horizontally extending boiler tubes, a primary superheater interposed between said banks, a reheater above said banks, means for passing the gases over said primary superheater and said reheater, means comprising a baille movable acrosssaid reheater for increasing or decreasing the temperature of said reheater by varying the flow of gases thereover without materially changing the flow of gases over said superheater, and means for causing the gases to engage all of the superheater tubes across the boiler substantially uniformly under every condition of operation.

DAVID s. JAcoBUs. WILLIAM a. JONES.

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