US2681641A

US2681641A - Vapor generating and superheating installation

Info

Publication number: US2681641A
Application number: US87998A
Authority: US
Inventors: Jr James D Andrew; Will H Rowand
Original assignee: Babcock and Wilcox Co
Current assignee: Babcock and Wilcox Co
Priority date: 1949-04-16
Filing date: 1949-04-16
Publication date: 1954-06-22
Anticipated expiration: 1971-06-22

Description

June 22, 1954 J. D. ANDREW, JR., ETAL 2,331,641

VAPOR GENERATING AND SUPERHEATING INSTALLATION Filed April 16, 1949 4 Shegts-Sheet l 50 INVENTORS JAMES a Ala/025W, 11?.

F/@ I BY 8 W/LL H. Row/W0 ATTORNEY J. D. ANDREW, JR., ETAL 4 VAPOR GENERATING AND SUPERHEATING INSTALLATION June 22, 1954 4 Sheets-Sheet 2 Filed April 16, 1949 INVENTORS JAMES D. AA/aenzJ/e.

, ATTORNEY J1me 1954 J. D. ANDREW, JR., ETAL 2,681,641

VAPOR GENERATING AND SUPERHEATING INSTALLATION Filed April 16, 1949 4 Shets-She'bta :.\i\ l! u I! II I! 1334 152 14/ I! H 88 /43 H4 l86 ,3!

O0 00 00 000 OOOOOOOOOOOOOOOOOOO 0 OOOOOQ V 1 76, 82 v 82 INVENTORS '2 JAMES B. xl/voyem fe.

FIG 3 BY 8 Wm H ROW/1ND m ATTORNEY Patented June 22, 1954 'VAP'OR GENERATING AND SUPERHEATIN G INSTALLATION James D. Andrew, Jr., Essex Fells, and Will H.

Rowand, Madison, N. J assignors to The Babcock & Wilcox Company, New York, N. Y., a corporation of New Jersey .ApplicationApril 16, 1949, Serial No. 87,998

8 Claims.

This invention relates to vapor generating units incorporating a high temperature superheater, and more particularly to the construction and .arrangement of a steam superheater in its relation to other components of a water tube steam boiler.

In modern high capacity steam generating units operating to deliver superheat steam-at high pressures, and at temperatures above 900 F., a high degree of heat is absorbed from the furnace gases by extensive-steam generating surface before the gases contact the convection superheater. Nevertheless, the temperature of the furnacegasescontacting the superheater will be of high value and will approach the maximum temperature which thesuperheatertubes are designed to withstand. The high steamgenerating capacity and high superheat temperatures for Which such units are designed require a large amount of convection heated steam superheating surface in a high temperature heating zone, and the problems of constructing and maintaining the elements of such a superheater in their operative relationships present substantial difficulties on account of the high temperatures involved.

The main object of the invention is the provision of an improved construction and arrangement of a superheaterin a vapor generating unit of the character described.

In accomplishing this object the invention involves an upright superheater gas pass having all of its walls and other boundary surfaces defined by superheater supply tubes which are pendently supported, with the saturated steam from the vapor generating tubes flowing into these wall tubes, and then to the superheater which includes a bank of tubes arranged transversely of the superheater gas pass. This arrangement eliminates various unsatisfactoryprovisions for expansion joints between vertically adjacent sections of the walls ofvsuch a gas pass, as in the case where suspended refractory walls have been used with the vertically adjacentsections subject to different temperatures. This arrangement also eliminates the necessity of providing a .multiplicity of headers and other tubular connections for the circulation, "as when water tubes connected into the vapor generating circulation system are employed to form the walls of the superheater gas pass. Furthermore, the illustrative arrangement whereby the superheater gas pass walls are all defined by superheater wall tubes eliminates the wall cooling difficulties which have been experienced, due

to the sluggish circulation of the wall cooling units when water tubes have been employed. Such sluggish circulation has provided inadequate wall cooling, and this resulted from the lower gas temperatures of the pertinent zone, .as compared to the gas temperatures of the combustion chamber wherein the main body of the vapor generating tubes are heated. It also eliminates the use of suspended type refractory walls, which do not expand uniformly in tight condition, with the pressure parts, and are difficult if not impossible to maintain.

The various features of novelty as characterized in our invention are pointed out with particularity in the claims annexed to and forming a part of this specification, and for a better understanding of the invention, its operating advantages .and the specific results attained by its use, reference should be had to the accompanying drawings and descriptive matter in which there has been illustrated and described a preferred embodiment of the invention.

In the drawings:

Fig. 1 .is a vertical section through the illustrative vapor generating unit;

beams underneath the banks of economizer tubes may be held in operative position by the upright saturated steam, or superheater, tubes, defining walls of the convection section gas passes.

The vapor generating and superheating unit shown in the drawings includes a furnace with a vertically elongated combustion chamber Hi. This combustion chamber is of rectangularcross section with its walls including vapor generating tubes connected to the vapor and liquid drum 12 at their upper ends, and connected with appropriate headers such as the headers l4, I6, I8 and 2.0, at their lower ends. The front wall .22 includes the wall tubes '24 connecting the header I4 to the drum i2 and at the lower part of this wall there are pulverized coal burners '26-28 for firing thefurnace. The lower header [8 is provided -for'one of the side walls and the combustion chamber wall tubes extending upwardly from that header have their upper ends connected to the upper side wall header 30. Ap-

propriate tubular connections such as 3| connect the header 30 with the drum I2, and the opposite side wall is of similar construction. The lower side wall header I8 has downcomers such as 34 and 36 connecting it into the fluid circulation of the vapor generating system by connection with the water space of the drum l2, and similar downcomer and header arrangements are provided for the other furnace walls.

The vapor generating wall tubes for the rear wall 38 of the combustion chamber extend upwardly from the lower header 20.. Upper parts of some of these tubes extend inwardly to define the arch 40 beneath the secondary superheater section 42 which is disposed within a lateral gas outlet 44 of the furnace. Some of the wall tubes of the rear wall 38 also extend vertically from the nose of the arch 40, as indicated at 46, across the gas flow to the secondary superheater section 42, and then extend along the furnace roof 4'! to the drum I2. Others of these tubes, including some of the tubes forming the arch 40, form a screen 48 rearwardly of the superheater section 42. Above this screen these tubes also extend along the roof 47 to the drum I2.

Particles of the non-combustible residue of the pulverized fuel fired by the burners 2628 are cooled by the radiant transmission of heat therefrom to the vapor generating tubes of the combustion chamber, and these particles separated out by gravity, in a dry condition, fall into the dry ash hopper 50 at the bottom of the furnace.

Gases leaving the combustion chamber through the outlet 44 flow horizontally into the upper end of an upright gas pass 52, as indicated by arrows '4 and 56. This gas pass is of rectangular cross section, with all of its walls defined by saturated steam tubes, or superheater supply tubes, the inlets of which are in communication with the steam space of the drum I2. For example, the rear wall 60 of the gas pass is defined by sections of upright steam tubes such as 62 and 64. Tubes having the sections 64 have upper portions 66 connected to a superheater inlet header 68 which, in turn, receives steam from the drum I2 through the tubes I0. The vertical tubular sections 62 are parts of tubes also having the forwardly inclined roof sections I2 which extend forwardly toward the roof 41 of the combustion chamber and thence upwardly andrearwardly, as indicated at I4, to the superheater inlet header 68. The roof over the tube sections I2 also involves refractory material I6, in a manner similar to the other gas pass and furnace walls of the installation.

The superheater wall tube sections 62-64 extend downwardly to the superheater header l8, and the opposite wall of the gas pass 52 is formed by a row of superheater tubes having the vertical sections 80 leading downwardly from header 68. These sections are in communication with the header I8 by the horizontal tubular sections 82 near the bottom of the gas pass 52.

The lower superheater header I8 is U-shaped with its intermediate section connecting two sides, or legs, one of which is exemplified by the side header portion 84. These header portions are directly connected to parallel upper headers 86 by'a row of superheater wall tubes 88. Headers 88 receive steam from the drum I2 through tubular connections such as 90. It will be understood that the remaining side wall of the gas pass 52 as well as that of the superheaterbypass 92 is formed by superheater wall tubes connected 4 into the superheater system in the same manner as that just described.

Steam flows from the superheater header I8 through a row of wall tube sections 94 to the inlets of the superheater tubes forming the banks of tubes I00-I02 of the superheater section I04. These banks of tubes are formed by series connected U-bend tubes arranged in vertical platens and connected for series flow of steam flow through the successive banks of tubes. The steam flow then continues through the upright superheater tube sections IIO to the superheater header H2 from which groups of tubular connections H4 and I! 6 lead to the inlet header I20 of the secondary superheater section 42. This is shown as consisting of two horizontally spaced banks of U-tubes, series connected for steam flow from the header I20 to the outlet header I22. Steam flow from the outlet header I22 continues through a series of conduits, such as I24, to a point of use.

The superheating effect may be modified by inserting any desired number of upright returnbend tubes I II (Fig. 1) between the header H2 and the top tube sections of the upper super-' heater bank I00.

The banks of tubes I00-I02 of the superheater section I04 are supported from the superheater tube sections 62 and of opposite gas pass walls by lugs such as I25 and I2! welded to the U-bends of successive tubes and resting upon coacting lugs such as I29 and I35 welded to the

tubular sections

80 and 62. Beneath the superheater I04 is an economizer section I30, including three banks of tubes I3I-I33 formed of series connected tube end sections in much the same manner as the banks of superheater tubes. It will be noted, however, that the economizer tubes extend at to the direction of the superheater tubes.

F'ig. 2 of the drawings shows the upper bank of economizer tubes I3l as supported by a beam I36 which, in turn, is supported at one end by the superheater supply tube sections 62 and at its other end by the upright superheater supply tubes 80, defining the wall between the bypass 92 and the main convection gas pass 52. There are a plurality of such beams beneath the bank of tubes I3I, one of the additional beams being indicated at I38 in Fig. 3. At substantially the same level as the beams I36 and I38, there are other beams such as I40 extending beneath the bank of economizer tubes I96 in the bypass 92. The particular manner in which these beams are supported from the wall tubes for the superheater space will be described below.

The remaining banks of economizer tubes I32 and I33 in the main gas pass are similarly supported by beams such as those indicated at I4I-'I44 in Fig. 3, the beams I38, I42, and I44, disposed underneath the tube sections of the economizer tube banks I3II33 extending through upright metallic spacer support plates such as I-45I 41. These plates are directly above the beams I38, I42, and I44 as indicated, and the spacer support plates are provided with openings through which the economizer tubes extend. This arrangement provides support for the pertinent parts of the economizer tubes and main- .tains them in operative relationship. The spacer support plates may be formed by narrow upright strips or bars such as those indicated at I48 in Fig. 4, or similar bars or strips having semi-circular notches in their vertical edges so that the strips may be inserted between the upright rows of tubes and then turned ;90 on their upright axes to :bring their notched portions into engagement with the successive tubes.

The banks of economizer tubes"If95-I:9'8 in the bypass 92 are supported by :beams such as the beam I 40, a plurality of these beams :being'provid'ed for 'the supp ort of each bank'of economizer tubes, and the beams being supported from the superheater supply tubes 80 and the steam generating tubes such as M -and '49 (-Fig; -2). The structure by which the-ends of these beams are supported from these wall tubes will "be similar to that subsequently described for supporting the ends -of the beams extending across the main gas pass in which the economize!" tube banks I3"I--I 33-aredisposed While the steam generat-- ing tubes such =as-48 and 49 are connected into the circulation of thevapor generatorand are at saturated temperature, that temperature is close to the temperature of the'fiuid-in the tubes 80 which receives saturated "steam from the header '68.

iAs indicated in Fig.3, the banks of economizer tubes I3I I33 extend to a position about halfway across the gas pass 52. At this position, or in this vertical plane, the tubes are supported by studs such as I49'which arewelded tothe return bends. These studs are placed in appropriately "spaced openings in upright metallic spacer support plates such as I'50--I-52 raised upon and supported by the beams I36, I, I43. oppositely disposed banks =I3IA, I32A, and I33A, of economiz'er tubes are "similarly supported by the spacer support plates! JO-I52.

Turning now to Figs. 4, 5, and 6 Which disclose an illustrative structure by which the 'economizer beams'may besupported, it is to be assumed that the beam shown in "these figures is the beam I 38 above referred to. Welded to "the righthand end of this beam is a heavy upright plate I53, extending inthedirection of a normal to the longitudinail axis of the beam, and this structure is further strengthenedby the'welding of lateral gussetuplates "such as I54 and -I55 "to'the web of the beam and 'tothe upright plate I53.

Welded to the opposite side of theupright'plate I53 there are pairs of upright triangular plates such as I56I59. 'These plates extend at right angles to the heavy plate I 53, asshownyand'th'ey are arranged in pairs with the spaced plates I56 and I51 disposed so as to extend between the

tubes

62 and 62A. The other triangular plates I58 and I 59 similarly extend between wall tubes such as62B and"B2"C.

Secured to the lower ends of the plates I56-I59 are horizontal plates I60 and 'IGI perforated to receive the lower ends of tension bolts I62 and I63. These bolts are provided'withsuitable securing devices at their ends to take the load at a beam end and transmit thatlo'ad to the upright superheater wall tubes such as 62.

"The structure by which the upper ends of the tension bolts I62 and IE3 are secured in position, includes the metallic support or bearing pads I64-I61 as shown in'Fig. 5. "These pads are welded to the tubes, with their upper ends at the same level, aslshown, and it is to 'be understood that similar pads are secured to the diametrically opposite sides of the tubes. One of these is indicated at 6-8 in' Fig. '4.

Resting uponthe pads Nil-4'61 is a heavy horizontal plate I6 9, 'witha similariplate "I10 at'the opposite sides of the tubes 62 and "52A. These plates may be welded to the tubes or securedin their-operative positions by welding toa heavier bar section, or collar 111, which is disposed be-- tween the two'platesections I69 and I 10 and be I tween the adjoining tubes 62 and 52A.

The securing devices at the ends of the bolt I62 include a perforated element I12 having an upwardly convex face I13 as indicated 'in Fig. 4. The beam structure, and more particularly the platecomponent I 60, rests upon this face. Below the element 'I 1-2 is the nut screw-threaded upon the bolt I 62. Similar elements I14 and I15 are disposedat the top of the bolt I62, but the lower face I16 of the element I14 is downwardly 'convex at its position of contact with the supporting element I1 I. This particular construction "involving "the convex faces minimizes stresses imposed onthe tube due to any slight relative movement or the beams and their supporting tubes.

Itwill be understood that the supporting structure indicated at the right hand end of theplate scribed 'but disposed within the super'heater 'bypas's92. The upper ends of these tubes are connected to 'a header 250 which is in communication with the drum iI2 by

tubular connections

253 and 255.

The 'front wall of "the superheater gas pass '52, formed by the superheater tube sections 80, constitutes a division wall between the bypass 92 of the gas pass 52, and the separation of "the by- "pass and the gas pass is continued below the tubular sections '80 by an upright metallic wall 252 and a similar horizontal wall section 254 to the groups of dampers'255 and 258 which control the division of the furnace gases between the by- -pass'9'2 and the gas pass 52 and thus exert controlling influence upon the heat absorption in pass'5'2 and thereby influence the final superheat These dampers may be automatitemperature. cally controlled for the purpose ofmaintaining a predetermined superheat temperature, by a control system'which regulates the dampers in accordance with the variations in steam flow from the superheater outlets I24 and also in response to variations in the superheat temperature from r a predetermined value.

Th ffurnace gases pass from the outlets of the gasvpass 52 and the bypass 92 to the heating gas inlet of an air heater 26! which operates to heat The heated air combustion air for the burners. flows through the duct work 262 from the air heater to the air enclosure 26 4, disposed about the burners.

The wall tubes of the combustion chamber I0 and of the gas pass 52 are pendently supported from superposed steel work at the top of the installation and the supports for headers 30, 68-, 86 and the upper ends of tube sections 641 are at I substantially the same level as the supports for the drum so that troublesome differential expansion is avoided and so that the closely related walls may be adequately sealed between passes and the atmosphere.

The expression superheater supply tubes or similar expressions, as are used in the specific'ation or the claims, are intended as a reference From this header the fluid to tubes receiving steam at substantially saturated temperature.

'While in accordance with the provisions of the statutes we have illustrated and described herein the best form of our invention now known to us, 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 our claims, and that certain features of our invention may sometimes be used to advantage without a corresponding use of other features, a

What is claimed is:

1. In a high pressure vapor generating and superheating installation, a large volume combustion chamber the walls of which include top hung upright vapor generating tubes, means including similar top hung vapor generating tubes forming a lateral gas outlet for the combustion chamber, upright superheater supply wall tubes defining the walls or an upright gas pass receiving furnace gases from said combustion chamber outlet, the superheater supply tubes being pendently supported from a position corresponding'to the support of the vapor generating tubes, an auxiliary fluid heater including a bank of series connected horizontal tubes disposed within said gas pass and extending transversely of the flow of gases therein, a superheater section including a bank of series connected tubes disposed within said gas pass above the tubes of said auxiliary fluid heater, and means secured to the upright superheater supply tubes for supporting the tubes of said superheater section and the tubes of the auxiliary heater from the superheater supply tubes forming opposite walls of said gas pass, all of the upright walls of the gas pass including fluid heating tubes maintaining the pertinent walls at temperatures of the same order.

2. In a high pressure vapor generating and superheating installation, a lar e volume combustion chamber the walls of which include top hung upright vapor generating tubes, means forming a lateral gas outlet for the upper part of the combustion chamber, upright superheater supply wall tubes defining the walls of an upright gas pass receiving furnace gases from said combustion chamber outlet the superheater supply tubes receiving vapor at saturated temperature 1 therein, a superheater section including a bank I of series connected tubes disposed within said gas pass above the tubes of said auxiliary fluid heater, and means secured to the upright superheater tubes for supporting the tubes of said superheater section and the tubes of the auxiliary heater from 1 the superheater tubes forming opposite walls of said gas pass, said last named means including beams supported at their ends by the superheater supply wall tubes and disposed beneath said auxiliary heater, all of the upright walls of the gas pass including fluid heating tubes maintaining the pertinent walls at temperatures of the same order.

3. In a high pressure steam generator, a furnace, means for firing the furnace, top hung steam generating wall tubes exposed to the heat of the furnace, top hung upright superheater supply tubes defining the four walls of an upright main gas pass receiving gases from the 'furnace, the superheater supply tubes receiving steam at saturated temperature, and a convection superheater section including a bank of tubes disposed in said gas pass and supported by said superheater supply tubes, some of said steam generating tubes defining a wall of a superheater gas bypass arranged in parallel with the main as pass, an economizer including a bank of spaced tubes disposed in the bypass and supported at one side of the bypass by said last mentioned wall and at the opposite side of the bypass by one of said four walls of the main gas pass,-and means controlling the variable division of the furnace gases between the main gas pass and the bypass, all of the upright walls of the gas pass and the bypass including fluid heating tubes maintaining the pertinent walls at temperatures of the same order.

4. In a high pressure vapor and generating superheating installation, a combustion chamber the walls of which include vapor generating tubes, a vapor and liquid drum to which said tubes deliver the generated vapor, upright superheater supply tubes receiving vapor from said drum and defining the four walls of an uprightmain gas pass receiving gases from said combustion chamber, the vapor generating tubes and the superheater supply tubes being pendently supported from a position at the top of the installation, an economizer including a first bank of tubes arranged transversely of said gas pass and supported by said superheater wall tubes, a convection superheater section including a bank of series connected tubes extending transversely of the gas flow within said gas pass, said superheater bank of tubes being disposed forwardly of the tubes of the economizer in a gas flow sense, some of said vapor generating tubes forming a wall of a superheater gas bypass opposite a bypass wall defined by some of said superheater supply tubes, a second bank of economizer tubes within said bypass, means connecting said first and second bank of economizer tubes in series for the supply of heated liquid to said drum, means secured to some of the tubes of said last mentioned walls and another wall of the main gas pass for supporting the banks of economizer tubes and the convection superheater section, and

means for variably controlling the division of furnace gases between said gas pass and the bypass, all of the upright walls of the gas pass and the bypass including fluid heating tubes maintaining the pertinent walls at temperatures of the same order.

5. In a high pressure vapor generating and superheating installation, a vertically elongated large volume combustion chamber the walls of which include top hung upright vapor generating tubes, a vapor and liquid drum to which said tubes deliver their vapor, means forming a lateral ing transversely of the flow of gases therein, a

convection superheater section including a bank of series connected horizontal tubes disposed within said gas pass above the tubes of said economizer, some of said superheater supply tubes and some of the vapor generating tubes defining the upright walls of a superheater gas bypass arranged in parallel with said main gas pass, other banks of economizer tubes within the bypass, mean including beams extending across said bypass and main gas pass and secured to the superheater supply tubes and the bypass vapor generating tubes for supporting the banks of economizer tubes within the main gas pass and the bypass, and means for variably controlling the division of furnace gases between the bypass and the main gas pass for superheat control, all of the upright walls of the gas pass and the bypass including fluid heating tubes maintaining the pertinent Walls at temperatures of the same order.

6. In a high pressure vapor generating and superheating unit, a vertically elongated furnace, supporting steelwork at the top of the unit, upright vapor generating tubes defining the furnace walls and top supported from the steelwork, and a convection superheater including a bank of spaced tubes disposed across gas flow in an upright gas pass adjacent the furnace and receiving gases therefrom, the side walls of the gas pass being defined by rows of upright superheater supply tubes functioning as a part of means cnducting vapor from the vapor generating tubes to the superheater, the upright superheater supply tubes of the gas pass walls also being top supported from the steelwork, all of the upright walls of the gas pass including fluid heating tubes maintaining the pertinent walls at temperatures of the same order.

7. In a high pressure vapor generating and superheating unit, a furnace, top hung upright vapor generating tubes defining the furnace walls, and a convection superheater including a bank of spaced tubes disposed across gas flow in an upright gas pass adjacent the furnace, at least three of the walls of the gas pass including top hung upright superheater supply tubes as a part of means conducting vapor from the vapor generating tubes to the superheater, said means including a U-shaped header disposed at a lower part of the gas pass and having the superheater supply tubes of a plurality of gas pass walls directly communicating therewith, all of the upright walls of the gas pass including fluid heating tubes maintaining the pertinent walls at tem peratures 0f the same order.

8. In a high temperature vapor generating and superheating unit, rows of top hung contiguously arranged vapor generating wall tubes defining the walls of a furnace of rectangular cross section, said furnace having furnace gas outlet at the upper portion thereof, means firing the furnace, a vapor and liquid drum at the upper part of the unit for the reception of the vapor and liquid mixtures from the furnace wall tubes and for the separation of vapor and liquid, wall means forming a convection gas pass of rectangular cross section extending alongside one of the furnace walls and receiving gases from said furnace gas outlet, said wall means including rows of upright contiguous superheater supply tubes along at least the side walls and the rear wall of the gas pass, said wall means also including thermal insulating material arranged exteriorly of the superheater supply wall tubes, a convection superheater arranged within the gas pass, said superheater supply wall tubes constituting parts of a tubular system conducting vapor directly from said drum to the inlet of the convection superheater, and thermal insulating material covering the walls of the furnace exteriorly of the furnace wall tubes, all of the upright walls of the gas pass including fluid heating tubes maintaining the pertinent walls at temperatures of the same order.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 736,793 Sewall Aug. 18, 1903 2,014,197 Armacost Sept. 10, 1935 2,015,362 Jacobus et a1 Sept. 24, 1935 2,107,440 Gordon Feb. 8, 1938 2,134,713 Gilg Nov. 1, 1938 2,196,889 Bailey Apr, 9, 1940 2,217,512 Donley Oct. 8, 1940 ,258,776 Pourchot Jan. 6, 1942 2,287,798 Hardgrove et al. June 30, 1942 2,308,762 Krug et al. Jan. 19, 1943 2,328,039 Toomey et al. Aug. 31, 1943 2,357,300 Bailey Sept. 5, 1944 2,366,719 Frisch Jan. 9, 1945 2,553,492 Wool1e May 15, 1951 2,553,493 Woolley May 15, 1951 FOREIGN PATENTS Number Country Date 435,883 Great Britain Oct. 1, 1935