US2918044A - Vapor generators - Google Patents

Description

Dec. 22, 1959 Filed Jan. 27, 1958 R. C. HUSTON VAPOR GENERATORS 7 Sheets- Sheet 1 INVENTOR.

Ralph C. H'usion ATTORNEY R. C. HUSTON VAPOR GENERATORS Dec. 22, 1959 '7 Sheets-Sheet 2 Filed Jan. 27, 1958 INVENTOR.

Ralph C. Husi'on LO q mwN

SN N? Em mm 9m 2m 3 2 ATTORNEY ea. 22, 1959 R. c. HUSTON 2,913,044

VAPOR GENERATORS Filed Jan. 27, 1958 7 Sheets-Sheet 3 INVENTOR.

Ralph C. Huslon ATTORNEY Dec. 22, 1959 R. c. HUSTON 2,913,044

VAPOR GENERATORS Filed Jan. 2'7, 1958 7 Sheets-Sheet 4 WWW w INVENTOR.

Ralph C. Husfon BY ATTORNEY Dec. 22, 1959 R. c. HUSTON 2,918,044

VAPOR GENERATORS Filed Jan. 27, 1958 7 Sheets-Sheet 5 BY WW ATTORNEY Filed Jan. 27. 1958 7 Sheets- Sheet 6 no 000000 DD 0000 open no on \I h I I I l I I I 1 I i I I A co m l l l ll ode O00 000 0000 00000000000 ooooo oowooocooooooo. 0800 800m 0000 2.00 0

co? l I l ll ll ob| t o n |l INVENTOR,

Ralph C. Husron ATTORNEY Dec. 22, 1959 R. c. HUSTON 2,918,044

VAPOR GENERATORS Filed Jan. 27, 1958 7 Sheets-Sheet 7 31A 28A J FIG.9

INVENTOR.

Ralph C. Husion ATTORNEY ttes sateen. i aiented Dec, 22, 1959 I ice VAPQR GENERATQRS Ralph Q. Huston, Wadsworth, Ohio, assignor to The Babcock & Wilcox Qompany, New York, N.Y., a corporation of New .lersey Application January 27, 1958, Serial No. 711,202

4 Claims. (Cl. 122-351) vapor generator comprising a horizontal, elongated setting defining a furnace section disposed in tandem with a convection section, in which the latter section includes a plurality of tube banks or convection heat absorbing units disposed in side by side relationship, and which have a common source of liquid supply, each unit including an upper liquid-vapor separating drum, a lower liquid drum disposed thereunder and a bank of tubes connecting the respective upper and lower drums for parallel fluid flow therethrough, the upper drum of only one of the tube bank units being extended longitudinally along the top of the furnace section which is defined by walls including fluid circulatory tubes that extend between the longitudinally extended portion of the upper drum and lower wall liquid headers, a portion of the circulatory tubes functioning as downcomer tubes receive liquid from the drum to supply the headers, and others exposed to furnace radiation serve as riser tubes and discharge a liquid-vapor mixture into the longitudinally extended portion of the upper drum, a part of the riser tubes forming a shield to protect the extended drum from the radiant heat of the furnace gases.

Another object of this invention is to provide in a steam generator of the type described a furnacecsection and a convection heat absorbing section in which the latter includes twoside by side tube bank units arranged for parallel fluid ilowtherethrough and connected in a manner such that the water l ev el in one of the tube bank units is maintained by controlling the water level of the other unit.

A feature of this invention resides in the provision of a novel baflle arrangement for directing the heating gases through the convection section in a laterally diverging and converging gas flow path that is substantially wholly in cross-flow heat transfer relationship to the fluid flow in the tubes of the generating banks.

Another feature resides in the provision of extending the furnace wall tubes inwardly along the top of the furnace to form a screen for shielding the bottom of the extended drum from the radiant heat of the furnace gases.

Other features and advantages will bereadily apparent when considered in view of thedrawings and the description in which:

Fig. 1 is a sectional side view taken along line 1-1 of Fig. 4 of the improved steam generator in accordance with the present invention.

Fig. 2 is a sectional plan View of the generating unit taken along line =2-2 of Fig. 1.

Fig.3. is .a vertical sectionalview taken through the furnace section along line 33 of Fig. 1 and illustrates the arrangement of the front wall tubes.

Fig. 4 is a vertical sectional view taken through the furnace section along line 4-4 of Fig. 1.

Fig. 5 is a modified form of the front Wall tube arrangement applicable in the form of the invention illustrated in Fig. 1.

Fig. 6 is a sectional side view of a modified form of the steam generator in accordance with the present invention.

Fig. 7 is a sectional plan view taken along line 7--7 of Fig. 6 with portions thereof broken away.

Fig. 8 is a vertical sectional view taken through the generating section along line 8-8 and is common to both forms of the invention illustrated by Figs. 1 and 6.

Fig. 9 is a vertical sectional view taken through the furnace section along line 9-9 of Fig. 6.

Referring to the drawings and particularly to Figs 1 to 2 there is shown in accordance with this invention a vapor or steam generator comprising essentially a setting 10 having rectangularly disposed front, rear and opposed side walls ll, 12, 13 and 14- and a top wall or roof 15 defining a convection section 16 which has disposed therein a pair of side by side tube banks or convection heat absorbing units 17, 18 and a forwardly positioned furnace or combustion chamber 19 common to each of the tube bank units 17, 18. Separating the furnace section 19 and the convection section 16 is a refractory bridge wall 20 which extends upwardly a short distance and which in' conjunction With the side walls and roof defines an openingor gas flow area 21 by which the furnace section 19 is in open communication with the con vection section 16.

In this form of the invention the furnace section 19 is arranged for burning a solid fuel, as for example coal or the like, which is fed from a suitable hopper 22 onto a traveling grate stoker 23. Overfired air is supplied through a plurality of jet nozzles 24 positioned in the front Wall 11 of the furnace, the noizles 24 directing the air so as to adequately mix with the combustible gases above the moving fuel bed. The heating gases thus generated in the furnace rise and flow over the bridge Wall 20 through flow area 21 into a convection section 16, the gases being directed through the convection section in an alternately diverging and converging flow path as will be hereinafter described. A flue opening 25 in the rear wall provides means whereby the cooled gases may exit upon passing through the convection section.

The tube bank unit 17 disposed in the convection section, Fig. 8, includes a main steam and water separating drum 26 which extends longitudinally and substantially co-extensively of the setting along the top thereof and is laterally disposed to one side of the setting. In vertical alignment with drum 26 and disposed thereunder adjacent the bottom of the convection section is a relatively shorter water drum 27 which extends from the bridge wall 20 to the rear wall 12. Connecting the rear portion of the main drum 26 to the lower water drum 27 is a bank 28 of boiler circulatory tubes arranged for parallel fluid flow therethrough.

The other tube bank unit 18, disposed alongside the foregoing described unit 17, consists of a short upper steam separating drum 29 and a lower Water drum 30 disposed in a substantial common vertical plane. These drums 25 and 30 extend longitudinally of the generating section 17 only and are connected with one another by a second bank 31 of boiler circulatory tubes which are likewise connected for parallel fluid flow. With this arrangement, a maximum amount of heating surfaces is available for the given volume. Conduits 27A interconnect the water space of the lower water drums 27 and 30 into communication with one another.

Asseen in Fig. 8, the water space ofthe main drum 26 of unit 17 is interconnected into communication with the lower drum 30 of unit 18 by a column of S shaped tubes 32 disposed between the tube banks 28 and 31. One or more steam pipes 33 connect the steam space of the upper separating drum 29 of unit 18 with the main drum 26 of unit 17, the latter being provided with one or more suitable steam outlets 34 to which there is connected suitable piping (not shown) for delivering the steam to a point of use. With this arrangement the two units 17 and 18 are tied together so that the water level existing in the upper drum of each unit 17, 18 is controlled by simply regulating the amount of feed water introduced through the feed water inlet 35 into the main drum.

The arrangement of the tube banks 28 and 31 is such that the outermost column of tubes 28A and 31A of each bank 28, 31 respectively, extends vertically along the refractory side wall portion of the generating section and function as wall cooling tubes. As shown in Figs. 1 and 2 the tubes in banks 28 and 31 are transversely aligned in rows which are grouped in pairs with the spaces formed between adjacent pairs of rows being greater than the diameter of the tubes. This specific arrangement is advantageous in that it permits ready access to any of the boiler tubes in the event thev require repair or replacement. This is readily accomplished by cutting the tube at the respective drums and taking the cut tube out through the space provided between tube groups. Thus outage time. expense and labor cost in making tube replacements is reduced to a minimum by the eae and speed afforded by the described tube arrangement in that only the defective tube need be removed.

As shown in Figs. 1 and 2. the forwardmost row of tubes 28B and 31B of tube banks 28 and 31 are inclined forwardly adiacent the lower end thereof to form the water co led bridge wall 20. the lower ends of t" e tubes 28B, 31B being connected into the ends of their respec- Along each of the side walls 13 and 14 defining the furnace section and adjacent the bottom thereof, there are disposed lower side wall headers 36 and 37 which extend substantially the length of the furnace section 19 as shown in Fig. 1. Circulatory tubes connect the forwardly extending portion of the main drum 26 to headers 36, 37. These circulatory tubes include respectively a row of downcomer tubes and a row of juxtaposed riser tubes, the latter being disposed on the furnace side of the downcomer tube rows. Referring to Fig. 4 one row of downcomer tubes 38 extends outwardly from a bottom sector of drum 26 and continues along the roof 15 to side wall 13 and thence downwardly along wall 13 to the header 36. Another row of downcomer tubes 39 extends outwardly from the bottom of drum 26 to wall 14 and thence downwardly therealong to header 37. It will be noted that the downcomer tube rows 38 and 39 connect into the drum 26 on opposite sides of the vertical axial plane thereof. With this construction the overall height of the unit may be maintained within the tolerable limits permitted by present day railroad clearances as indicated by the dot-dash lines of Fig. 8.

Extending upwardly from header 36 adjacent the row of downcomer tubes 38 and on the furnace side thereof is a row of riser tubes 40 which continue inwardly to form the furnace roof 15 and then connect into the lower left sector of the drum 26 at a position above the connections of the downcomer tubes 38. Rising upwardly from header 37 along the side wall 14 is a riser tube row 41. This row 41 of riser tubes extends along wall 14 and continues inwardly thereof to extend below the drum 26 and connect into the left sector thereof. With this construction the roof extensions 41A of the tubes in row 41 form a screen which shields the drum 26 from the radiant heat of the furnace gases. If desired the riser tubes, which cool the side walls may be studded with fiat studs extending radially in the spaces between tubes as shown at 42.

In the Stoker fired furnace, the front wall 11 is likewise lined with circulatory tubes. As seen in Figs. 2 and 3 these tubes include a row of downcomer tubes 43 shown in dash lines in Fig. 3 to supply the lower front wall header 44 with water from the main drum. A row of riser tubes 45 extending upwardly along the front wall on the furnace side, as shown, connects the header 44 to the drum 26 to complete the front wall circuit. Conduits 44A connect each end of the front wall header 44 to the respective side wall headers as shown at one end in Fig. 2. g

In Fig. 5, a modified front wall tube arrangement 111 is illustrated. In this form the riser tubes extending upwardly from header 144 in the left portion of wall 111 extend vertically and connect into an upper collecting header 146 which in turn is connected to the main drum 126 by suitable discharge tubes 147. With this arrangement the number of front wall tube bends is greatly reduced. The downcomer tubes in the front wall 111, not shown, are similarly arranged to those in wall 11 as hereinbefore described.

Figs. 6, 7 and 9 illustrate a modified form of the invention which is essentially similar to the invention as hereinbefore described with the exception that the front wall 211 and furnace floor 212 have been adapted for firing either oil or gaseous fuels. As shown the front wall 211 and floor 212 are lined with refractory and the front wall 211 is provided with burner ports 213 for receiving the burners 214.

In each form of the invention shown the entire unit is enclosed by an outer metal casing 215 to protect the insulation 216 and brick work 217. the metal casing 215 minimizing air infiltration to the unit.

In operation with the two tube bank units 17 and 18 with water in the drum at the proper level and the furnace suitably fired, the heated gases generated therein radiate heat to the furnace wall cooling tubes 41, 42, and 45 to produce steam. The gases from the furnace enter the convection pass 16 flowing in heat transfer relationship across the banks 28 and 31 of the convection heat absorbing units 17 and 18. As shown in Figs. 1 and 2, bafile means are disposed within the convection section 16 for deflecting the gases in a horizontally converging and diverging flow path. As shown, laterally aligned baffle members 46, 47 extend inwardly from the opposite side walls to provide a central restricted opening or flow area 48 through which the gases entering section 16 are directed. Positioned downstream gas flow-wise and in line with the restricted opening 48 formed by the foregoing baffle members 46, 47 there is disposed a second baflle member 49 which has its ends 49A, 49B spaced from the side walls 13, 14. This baffle member 49 functions as a deflector causing the gas flow to diverge outwardly around the ends thereof through the flow areas 50, 51 defined by the outer edge of the baffle member 49A, 49B and the adjacent side walls 13 and 14. To insure that the gases flow in a substantially horizontal stratum throughout the generating section 16 and hence in a substantially wholly crossflow heat transfer relationship with respect to the tube banks 17 and 18, the baffle members 46, 47 and 49 extend vertically substantially throughout the entire height of the generating section. With this arrangement optimum heat transfer is attained with a minimum draft loss across the unit.

In the described arrangement, the heating gases entering the convection section diminish in temperature as they flow therethrough. Thus the forward portion of the tubes in banks 28 and 31 are heated by the high temperature gases and cause the generation of steam agate-p44 resulting in a decrease in the density of water therein to thereby induce an -upward circulation. The tubes at the rear of the gas pass are acted upon by the cooler gases and are thus heated to a lesser extent causing the water therein to be greater in density and thereby inducing a downward circulation therein. With the described arrangement adequate circulation is established in each of the circuits with the ultimate result being the attainment of maximum steam generating with a minimum of given space. Thus high operating efficiency is attained with economy of space and simplicity of design.

' While theinstant invention has been disclosed with reference to a particular embodiment thereof, it is to be appreciated that the invention is not to be taken as limited to all of the details thereof as modifications and variations thereof may be made without departing from the spirit or scope of the invention.

What is claimed is:

l. A steam generator comprising a setting defining a furnace section and convection section in tandem therewith, means for generating heating gases in said furnace section, a pair of upper steam and water separating drums extending longitudinally of the convection section along the top thereof, said separating drums being disposed in side by side relationship on either side of the longitudinal vertical axial plane of said convection section, each of said upper drums having a steam space and a water space, a pair of lower water drums, one under each of said separating drums, a first bank of tubes connecting one of said upper drums to one of said lower drums, a second bank of tubes disposed in side by side relationship to said first bank of tubes connecting said other separating drum to said other lower drum, conduit means for directly interconnecting said lower pair of drums into communication with one another, a row of tubes disposed between said first and second tube banks connecting the water space of said one upper drum to said other lower drum, and means connecting the steam space of one of said separating drums into communication with the steam space of said other separating drum, said latter drum having means forming a steam outlet.

2. A steam generator comprising a horizontal elongated setting having front, rear and side walls defining a furnace section and a convection section in tandem therewith, said convection section having a flue opening in the rear wall thereof, means for generating heating gases in said furnace section, a pair of upper steam and water separating drums extending longitudinally of the setting along the top thereof and each of said separating drums being disposed on either side of the longitudinal vertical axial plane of the setting, said pair of separating drums including a first drum extending substantially the whole length of the setting and a second separating drum extending the length of the convection section only, a pair of water headers, each of said headers extending longitudinally along each side wall of the furnace section at the bottom thereof, a row of downcomer tubes connecting said first separating drum to each of said headers, each row of downcomer tubes extending outwardly from the bottom of said first drum to define a roof portion of said furnace section and thence downwardly along the adjacent side wall to said header, means for shielding said downcomer tube rows from the heating gases generated in the furnace section, said shielding means including a row of riser tubes connecting each of said headers to said first drum, each riser tube row extending upwardly in juxtaposed position relative to said downcomer tubes on the furnace side thereof from its respective header and thence inwardly along the roof of said furnace section, the furnace roof portion formed by one of said riser tube rows extending below the drum to shield the same from the hot gases generated in the furnace, said riser tubes in each of the rows having their G end portions connecting intosaidtifirst separating drum on the same side of ,a longitudinal vertical axial plane of the drum at a position above the downcomer connections in the bottom of said first drum, a pair of lower water drums extending along the bottom of said convection section only, one under each of said uppersepparating drums, two banks of heating tubes disposed in side by side relationship in the convection section, each bank directly connecting one of said upper separating drums to the respective lower water drum disposed thereunder, and baiile means disposed in said convection section, said bafile means including opposed-baffies extending from top to bottom of said convection section and inwardly from the side walls thereof, said opposed bafiles having their inner edge portions defining a restriction through which the heating gases flow, and a second bafile spaced from said side walls, said second baffie being disposed downstream from said opposed baflles in line with said restriction formed therebetween and forwardly of said flue opening, said bafi les defining a gas pass in which the gas flow therethrough is directed in laterally converging and diverging paths.

3. A steam generator comprising a horizontal elongated setting having front, rear and side walls defining a furnace section and a convection section in tandem therewith, said convection section having a fine opening in the rear wall thereof, means for generating heating gases in said furnace section, a pair of upper steam and water separating drums extending longitudinally of the setting along the top thereof and each of said separating drums being disposed on either side of the vertical longitudinal axial plane of the setting, said pair of separating drums including a first drum extending substantially the whole length of the setting and a second separating drum extending substantially the length of the convection section only, a pair of water headers, each of said headers extending longitudinally along each side wall of the furnace section at the bottom thereof, a row of downcomer tubes connecting said first separating drum to each of said headers, each row of downcomer tubes extending outwardly from the bottom of said first drum to define a roof portion of said furnace section and thence downwardly along the adjacent side wall to said respective header, means for shielding said downcomer tubes from the heating gases generated in the furnace section, said shielding means including a row of riser tubes connecting each of said headers to said first drum, each riser tube row extending upwardly in juxtaposed position relative to said downcomer tube rows on the furnace side thereof from its respective header and thence inwardly along the roof of said furnace section, the furnace roof portion formed by one of said riser tube rows extending below the first drum to shield the same from the hot gases generated in the furnace, said riser tubes in each of the rows having their end portions connecting the said first drum on the same side of a longitudinal vertical axial plane thereof at a position above the downcomer connections in the bottom of said first drum, a pair of lower water drums extending along the bottom of said convection section only, one under each of said upper separating drums, two banks of heating tubes disposed in side by side relationship in the convection section, each tube bank directly connecting one of said upper separating drums to its respective lower water drum disposed thereunder, each tube bank including a plurality of spaced tube groups in which the spacing between adjacent tube groups is greater than the diameter of the tubes in said groups, and baffle means disposed in said connection section, said bafile means including opposed baffies extending from top to bottom of said convection section and inwardly from the side walls thereof, said baffles having their inner edge portions defining a restriction through which the heating gases flow, and a second battle spaced from said side walls, said second baffie being disposed downstream from said opposed bafiies in line with said 7 restriction formed therebetween and forwardly of said flue opening, said bafiledefining a gas pass in which the gas flow. therethroughis directed in laterally converging and divergingpaths.

4. In a vapor generator having a setting including front, rear and connecting side walls defining a furnace section and a convection'section adapted to form a compact unit having its outer dimensions within tolerable railroad clearances, the improvement of a vapor and liquid separating drum extending longitudinally and substantially co-extensive of the setting along the top thereof and laterally disposed to one side thereof, a liquid header extending longitudinally and substantially co-extensive along each side wall of the furnace section at the bottom thereof, a row of downcomber tubes extending co-extensively along each side wall of the furnace for connecting the bottom sector of the drum with each of said headers, one row of downcomer tubes being connected into the bottom section of the drum on each side of the vertical axial plane of the drum, each row of downcomer tubes extending outwardly in opposite directions and toward the furnace side walls from the bottom sector of the drum to define a roof portion of said furnace section and thence downwardly along the adjacent side wall to said headers, a pair of high duty riser tube rows, each row of riser tubes being substantially co-extensive and juxtapositioned to the respective downcomer tube rows, each row of riser tubes connecting one of said headers to said drumand each of said riser tube rows extending upwardly along the side wall from its respective header and inwardly along the roof thereof in shielding relationship with the respective downcomer tube rows, the riser tubes of both rows having their respective end portions connected into drum sectors located on the same side of the vertical axial plane of the drum at a position above the downcomer tube connections to said drum, only oneof said riser tube rows forming a furnace roof portion which extends below the drum for shielding said drum from the heating gases generated in the furnace.

References Cited in the file of this patent UNITED STATES PATENTS 1,746,240 Cain Feb. 11, 1930 2,550,066 Hardgrove Apr. 24, 1951 2,551,945 Harvey May 8, 1951 2,606,535 Sandstrom Aug. 12, 1952

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