US3115122A

US3115122A - Vapor generating unit

Info

Publication number: US3115122A
Application number: US93173A
Authority: US
Inventors: Hubert G Stallkamp
Original assignee: Babcock and Wilcox Co
Current assignee: Babcock and Wilcox Co
Priority date: 1961-03-03
Filing date: 1961-03-03
Publication date: 1963-12-24
Anticipated expiration: 1980-12-24

Description

Dec. 24, 1963 H. a. STALLKAMP VAPOR cznsmmc uurr 3 Sheets-Sheet 1 Filed March 5, 1961 FIGJ mmvron Huber? G. Stallkamp ATTORNEY Dec. 24, 1963 H. G. STALLKAMP VAPOR GENERATING UNIT 3 Sheets-Sheet 2 Filed March 3, 1961 FIG? IHI I'l INVENTOR? Hubert G. Sia'l'l jkamp ATTORNEY Dec. 24, 1963 H. a. STALLKAMP VAPOR GENERATING UNIT med March a, 1961 s Sheets-Sheet :s

mmvron. Hubert G. Srallkamp 6 AT TORNEY United States Patent 3,115,122 VAIPQR GENERA'HNG UNIT Hubert G. Stallkamp, Akron, Ohio, assigner to The Babcock & Wilcox Company, New York, N.Y., a corporation of New Jersey Filed Mar. 3, 1961, @r. No. 93,173 3 Claims. (Cl. 122-235) The present invention relates to the construction of fluid heating units and more particularly relates to an improvement in the fluid flow system of a vapor generator of the type disclosed in US. Patent 2,840,049.

When vapor generating units are operated under combustion conditions where the gases of combustion are maintained at high pressures, it is of considerable structural advantage to construct the unit with a circular crosssection. A circular section combustion chamber and convection gas pass of such a vapor generator can readily withstand high furnace pressure operation due to the inherent structural strength of a construction involving such circular sections.

In the present invention, a vapor generating unit is provided wherein the furnace and the convection gas passes of the unit are enclosed in a cylindrical setting. The confining walls of the unit are lined with vapor generating tubes for the absorption of heat and the protection of walls. Advantageously, the downcomer tubes of the vapor generator flow circuit are bent out of alignment with the walls of the furnace so as to form a bustle or annular chamber surrounding the furnace walls. The bustle or annular chamber advantageously provides a housing for the introduction of gaseous fuels and air.

More specifically, in the present invention the riser or steam generating tubes lining the furnace and convection gas pass portions of the unit are positively provided with make-up fluid to insure adequate thermosiphonic circulation in the unit over the entire load range. This is accomplished in the present invention by the provision of separate downflow fluid flow paths feeding separate portions of the furnace and the convection gas pass. The construction is particularly economical to construct and assemble and efliciently insures adequate natural circulation of fluid through the unit.

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

Of the drawings:

FIG. 1 is a sectional elevation of a vapor generating unit constructed in accordance with the present invention;

FIGS. 2, 3 and 4 are sectional views taken on the

lines

22, 33 and 4-4 respectively of FIG. 1; and

FIG. 5 is an enlarged partial section taken on the lines 5-5 of FIG. 1.

The vapor generating or fluid heating unit illustrated in FIG. 1 is arranged for a gaseous fluid flow over and along the heating surfaces of the unit substantially as shown in US. Patent 2,840,049. As disclosed in said patent, and shown in FIG. 1, means are provided in the lower portion of the cylindrical setting for the combustion of a fuel. Specifically, the lower portion or furnace 11 includes vertically spaced rows of burner ports 12 for the introduction of a high heat Value fuel through burners 13 with a row of low heat value fuel inlet ports 14 positioned intermediate the level of the two high heat value fuel burner ports 12. A second row of low heat value fuel inlet ports 15 is spaced below the lower level of the high heat value fuel burner ports 12. As shown in FIGS. 4 and 5, the high heat value fuel burners 13 are arranged with their longitudinal axes substantially radial with respect to the furnace 11, while the low heat value

fuel inlet ports

14 and 15 are arranged to discharge fuel into the furnace with tangential components of movement. As shown, the burners 13 are constructed for the use of fuel oil, although other high heat value fuels, such as natural gas or the like, may be used with suitable changes in the burners. The low heat value fuel inlet ports may be used for the introduction of CO containing gases obtained from the regeneration of the catalyst used in a hydrocarbon reforming process.

The upper end portion of the furnace 11 is provided with an orifice baffie 16 which aids in mixing the products of combustion resulting from the burning of both the low and high heat value fuels. An annular air chamber 17 extends from an upper position adjacent the orifice baflle 16, on the exterior side of the furnace 11 to the bottom of the furnace. Above the orifice baffle, the gases of combustion are deflected toward one side of the unit by a wing or nose baflle 261 which extends transversely across the unit at a position upwardly adjacent the level of the orifice baffle 16.

The portion of the setting between the orifice b-aflle and the wing baflle constitutes a radiant heat exchange chamber or Zone 21 wherein the gases of combustion are partially cooled and in passing upwardly through the gas flow passageway 22 between the nose baffle 20 and the opposite wall are directed into a convection gas pass 23. The convection gas pass is provided with rows of generally upright tubes 24 extending between and opening into horizontally disposed upper and lower drums 25 and 26, respectively. The upper drum is located adjacent the roof 27 of the setting, while the lower drum 26 is positioned immediately above and is protected by the nose baflle 20. The gas outlet 30 from the setting is adjacent the upper drum 25 andin general vertical alignment with the wing baffle 20 so that the gases of combustion flow in a generally horizontal direction across the bank of convection heating tubes 24 to subsequently discharge upwardly through the outlet 30. Natural circulation occurs through the tubes 24 between drums 25 and 26, with the cooler tubes adjacent the gas outlet 30 serving as downcomers to supply fluid to the lower drum 26.

Thus, with the construction described, the flow of the heating gases through the unit is substantially the same as that disclosed in said US. patent. The construction is such as to provide a simple and effective heat trap for the products of combustion generated in the furnace 11 in the lower portion of the setting, and the generation of steam.

In accordance with the present invention, a lower header 31 supplies water to the lower or inlet end of the circumferential row of tubes 3-2 defining the circular wall of the furnace 11, the radiant heating portion 21 and the convection heating portion 22 of the unit. The header 31 is circular and is divided into two

separate sections

31A and 31B by means of diaphragms 33 positioned in the header. The tubes 32 in the wall of the furnace 11 extend upwardly to the level of the orifice baflle 16 whereat alternate tubes 32A are bent inwardly toward the center of axial centerline of the cylindrical setting 10 and we thereafter bent towards the circumferential row of wall tubes to return to the wall configuration. This construction is illustrated in FIGS. 1 and 3 of the drawings wherein the wall tubes are indicated beneath the protective covering of refractory materials 33. Alternate tubes 3213 in the furnace row extend in a vertical direction for wall support and to maintain the cylindrical configuration of the structure.

The circumferential row of wall tubes 32 representing approximately /3 of the tubes in the setting are extended upwardly through the radiant heating zone 21 and the passageway 22 of the unit to open into an arcuate collecting header 34 positioned downwardly adjacent the upper drum 25. The steam and water mixture delivered by the wall tubes 32 to the upper header is discharged into the drum through roof tubes 35. A portion of the wall tubes 32 identified as 32C in FIGS. 1 and 2 extending upwardly from the lower header 31 toward the lower drum 26 open into the lower drum with an aligned group of tubes thereafter passed upwardly in the sa ine wall row alignment from the lower drum to open directly into the upper drum 25. All of the above described tubes open at their lower end to the header section 31A.

The remaining wall tubes 32. extended upwardly from the lower header section 31B and forming the upwardly aligned portion of the orifice bafile 16 are all bent inwardly of the furnace to form the nose bathe 20. Above the orifice baffle 16, these tubes are designated as 36 and the tube arrangement is shown particularly in FIGS. 1 and 2. The tubes 36 extend upwardly through zone 21, bend forwardly and upwardly along the hot face of the nose baffle 29, extend upwardly across the nose 37 of the bafile and then bend in a rcanwa-rd direction to open into the lower drum 26. Thus, the riser tubes of the unit described completely enclose the furnace 11 including the orifice bailie 16, and the radiation zone 21 including the surface of the wing bafile 20. In addition, the riser tubes enclose a major segment of the gas passageway 22 including wall tubes connecting the drums 25 and 26. As hereinafter described, the remaining rear segment of the wall of the convection zone 23, above the nose battle 20, which is the coolest wall portion of the unit, is lined by downcomer tubes 4% to complete the tube rows associated with the walls of the cylindrical setting 19.

The downcomer tubes 4t) forming the rear portion of the wall above the wing baffle receives water from the water space of the upper steam and water drum through connectors 39 and an arcuate header 41. The header is horizontally disposed substantially at the elevation of the header 34 and forms a segment of a circle of substantially the same radius as the header 34 and the cylindrical wall of the setting It). The upright downcomer tubes 40 extend downwardly parallel to and behind the riser tubes 36 in the zone 21. This construction is shown in FIG. 3, where the tubes 40 are embedded in plastic refractory material 42 and are protected by the tubes 36 from direct radiation of the hot gases passing through the zone 21. The tubes 40 are bent out of wall alignment toward the exterior of the unit at an elevation adjacent the upper edge of the orifice baffle 16 to define the outer wall 43 of the annular chamber 17 surrounding the furnace, and open into the lower header 318.

As shown particularly in FIG. 1, the make-up water delivered to the forward portion 31A of the lower header 31 originates in the lower drum 26. This water flows downwardly through exterior downcomers 44 to a header 45 positioned upwardly adjacent but on the exterior side of the orifice baffle 16. The header 4'5 for-ms the segment of a circle having a radius greater than that of the wall defined by the tubes 32. The downcomer tubes 46 leading downwardly from the header 45 are bent outwardly of the cylindrical casing to define approximately /3 of the outer circumferential wall 43 of the annular chamber 17 enclosing the furnace portion of the unit. The lower ends of the tubes 46 open into the portion 3 1A of the lower header 31.

In the illustrated embodiment of the invention, the furnace 11 is arranged for the combustion of a low heat content gas having a relatively high sensible heat and a minor proportion of combustible CO gases therein. The low heat value fuel can be burned only in a furnace maintained at a temperature in excess of approximately 4 1500 F. This temperature is attained by the combustion of a high heat value fuel, such as fuel oil, introduced through the fuel burners 13.

The construction and arrangement of the high heat value fuel burners is illustrated in FIG. 4 wherein the tubes 32 in the wall of the furnace 11 are covered by refractory material 47 and the tubes are displaced out of the plane of the wall in the vicinity of the burner ports 12. When fuel oil is burned as a supplemental high heat content fuel, the oil burner 13 is inserted in the burner ports 12 for the introduction of the high heat value fuel. The air necessary for proper combustion of the high heat value fuel is introduced through the usual louvre equipped registers 43, supplied through upright chambers 50 formed by vertically disposed dividing partitions 51 extending from the lower end of the annular chamber 11 to a location above the upper row of burners 13. The partitions are spaced on opposite sides of each of the burner ports 12 to provide the separate flow paths for combustion air leading to each of the vertical rows of high heat content fuel burners 13. Between the partitions which define the upright chambers 59 are passageways 52 for the introduction of the CO contain ing gases to and through the low heat content burner ports 1'4 shown in phantom on FIG. 4 and in enlarged detail in FIG. 5.

He combination air enters the channels or chambers 50 from a plenum chamber 60 located below the floor 61 of the furnace -11 being supplied with superatmospheric pressure air from a forced draft fun (not shown) through a connecting duct 62. Only the chambers 50 open to the plenum chamber 69, and each chamber 50 is closed at the top by a horizontally disposed plate 63, spaced above the uppermost row of burners 13 and which extends between the partitions '51 only above each chamber 53.

The

ports

14 and 15 open to the passageways 52 which are supplied with low heat value gas from a duct 64 which enters the annular chamber 17 above the plates 63. With this construction, the annular chamber 17 forms an annular plenum above the plates 63 for distributed How to each of the passageways 52 and thence through the

ports

14 and 15.

In the embodiment illustrated in FIGS. 1 and 4, the high heat value fuel is discharged by the burners 13 into the furnace 11 in a radial direction. As shown in phantom in FIG. 4 and in FIGS. 1 and 5, the low heat value

fuel inlet ports

14 and 15 are constructed to introduce the gases into the furnace at an angle of approximately 45 as indicated in FIG. 4 and with a tangential component of motion. The projected axial centerlines 56 of such low heat value fuel inlet ports intersect an imaginary circle 57 spaced inwardly of but closely adjacent to the refractory lining of the furnace walls. With this construction, the low heat content fuel sets up a violent swirling motion for intimate mixing of the gases of combustion resulting from the conversion of the CO gases to CO as encouraged by the temperature level maintained in the furnace. The high heat value fuel introduced by the burners will form a central core of high temperature flames from the combustion thereof. The central core will rapidly mix with and encourage the combustion of the low heat value fuel. The orifice baffle 16 will further insure complete and intimate mixing between the products of combustion of the two fuels passing upwardly through the unit.

In the operation of the unit of the type described, the waste gases containing CO may contain sufficient oxygen therein for the conversion of the CO to CO under the temperature conditions prevailing within the furnace. Under these conditions, the combustion air admitted through the high heat value inlet ports 12 will be generally suflicient to insure the combustion of such fuel, for example, of the theoretic air requirements for this fuel. Sometimes, the CO containing gases will not contain suflicient oxygen for the conversion of the CO -to CO Under these conditions, it will be necessary to add sufli'cient excess air through the high heat value inlet ports to provide the oxygen necessary for the combustion of the CO gases. Thus, the air delivered to the high heat value burners will be regulated in accordance with the requirements of the particular installation.

The unit described has a furnace diameter of 17 feet, and is supplied by 6 high heat value burners and 12 low heat value burner ports. Such a unit is capable of burning 355,000 c.f.m. of CO bearing gases having an incoming gas temperature of 1050 F. With a CO content of approximately 7.5% by volume, and burning sufficient high heat value fuel to maintain a furnace temperature of approximately 1800 F., the unit will generate 200,000 pounds of steam per hour at 625 psi. (pounds per square inch gage). Larger or smaller units may be constructed with a greater or lesser number of burners, and a correspondingly changed steam generated capacity. Within the ability of the furnace described to burn CO containing gas, the natural circulation fluid flow system of the invention will be entirely adequate.

While in accordance with the provisions of the statutes I have illustrated and described herein the best form and mode of operation of the invention now known to me, those skilled in the art will understand that changes may be made in the form of the apparatus disclosed without departing from the spirit of the invention covered by my claims, and that certain features of my invention may sometimes be used to advantage without a corresponding use of other features.

What is claimed is:

l. A fluid heater having an upwardly elongated setting of circular horizontal cross-section defined by walls having a circumferential row of substantially upright tubes therein, spaced upper and lower horizontally disposed drums connected by substantially upright banks of tubes extending transversely across and positioned in the upper portion of said heater setting, means defining a gas outlet from said setting behind said upper drum and between the drum and the adjacent wall, means in the lower portion of said heater setting for generating hot combustion gases, wing baflie means extending from said wall and positioned beneath said lower drum in general vertical alignment with said gas outlet, the segmental portion of the circumferential row of upright wall tubes directly beneath said wing portion forming riser tubes and being bent inwardly out of wall alignment along said wing baflle to open into said lower drum, the segmental portion of the circumferential row of upright wall tubes directly above said wing portion opening to said upper drum and forming downcomers and being off-set outwardly of the wall and supplying fluid to the lower end of said riser tubes, and means including external downcomers for fluid flow from said lower drum to the lower end of the remaining segmental portion of the circumferential row of tubes in said wall, said last named tubes forming riser tubes extending upwardly along the corresponding segmental portion of the walls of said setting to discharge into said upper drum.

2. A fluid heater having an upwardly elongated setting of circular horizontal cross-section defined by walls having a circumferential row of substantially upright tubes therein, spaced upper and lower horizontally disposed drums connected by substantially upright banks of tubes extending transversely across and positioned in the upper portion of said heater setting, arcuate upper headers connected with tubes in the walls of said heater and with said upper drum, means defining a gas outlet from said setting between said upper drum and an adjacent wall of said setting, means in the lower portion of said heater setting for generating hot combustion gases, wing baffle means extending from said wall and positioned beneath said lower drum in general vertical alignment with said gas outlet, the inner end of said wing baflle cooperating with a segmental portion of said wall to define a restricted gas flow path therebetween, a segmented annular lower header connected with the lower ends of the tubes in said circumferential row of tubes, the segmental portion of the circumferential row of upright wall tubes directly beneath said wing portion forming riser tubes and being bent inwardly of said setting out of wall alignment along said wing baflie to open into said lower drum, the segmental portion of the circumferential row of upright 'Wall tubes directly above said wing portion opening to one of said upper arcuate headers and forming downcomers and being off-set outwardly of the wall and supplying fluid to a segmental portion of said lower annular header, and means including external downcomers for fluid flow from said lower drum to another segmental portion of said annular header to supply fluid to the remaining segmental portion of the circumferential row of tubes in said Wall, said last named tubes forming riser tubes extending upwardly along the walls of said setting with a major portion of said tubes discharging into the other of said arcuate upper headers and the remainder discharging directly into said drums.

3. A fluid heater having an upwardly elongated setting of circular horizontal cross-section defined by walls having a circumferential row of substantially upright tubes therein, spaced upper and lower horizontally disposed drums connected by substantially upright banks of tubes extending transversely across and positioned in the upper portion of said heater setting, means defining a gas outlet from said setting between said upper drum and an adjacent wall of the setting, means in the lower portion of said heater setting for generating hot combustion gases, wing baffle means extending from said wall and positioned beneath said lower drum in general vertical alignment with said gas outlet, the segmental portion of the circumferential row of upright wall tubes directly beneath said wing portion forming riser tubes and being bent inwardly out of wall alignment along said wing baffle to open into said lower drum, the segmental portion of the circumferential row of upright wall tubes directly above said wing portion opening to said upper drum and forming downcomers and being oflY-set outwardly of said setting walls at an elevation spaced below said wing baflle and extending downwardly to supply fluid to a separate header opening to lower ends of said riser tubes, and means including external downcomers and an upright row of circumferentially spaced downcomer tubes off-set outwardly of the walls of said setting connected with a separate header opening to the lower ends of the remaining segmental portion of the tubes in said wall, said last named tubes forming riser tubes extending upwardly along the walls of said setting, said ofi-set downcomer tubes being radially spaced from said setting walls to form an annular chamber surrounding the lower portion of said fluid heater.

References Cited in the file of this patent UNITED STATES PATENTS 1,892,661 Hulsart Dec. 27, 1932 1,935,272 Kuhner Nov. 4, 1933 4,943,539 Kerr Jan. 16, 1934 2,840,049 Durham June 24, 1958

Claims

1. A FLUID HEATER HAVING AN UPWARDLY ELONGATED SETTING OF CIRCULAR HORIZONTAL CROSS-SECTION DEFINED BY WALLS HAVING A CIRCUMFERENTIAL ROW OF SUBSTANTIALLY UPRIGHT TUBES THEREIN, SPACED UPPER AND LOWER HORIZONTALLY DISPOSED DRUMS CONNECTED BY SUBSTANTIALLY UPRIGHT BANKS OF TUBES EXTENDING TRANSVERSELY ACROSS AND POSITIONED IN THE UPPER PORTION OF SAID HEATER SETTING, MEANS DEFINING A GAS OUTLET FROM SAID SETTING BEHIND SAID UPPER DRUM AND BETWEEN THE DRUM AND THE ADJACENT WALL, MEANS IN THE LOWER PORTION OF SAID HEATER SETTING FOR GENERATING HOT COMBUSTION GASES, WING BAFFLE MEANS EXTENDING FROM SAID WALL AND POSITIONED BENEATH SAID LOWER DRUM IN GENERAL VERTICAL ALIGNMENT WITH SAID GAS OUTLET, THE SEGMENTAL PORTION OF THE CIRCUMFERENTIAL ROW OF UPRIGHT WALL TUBES DIRECTLY BENEATH SAID WING PORTION FORMING RISER TUBES AND BEING BENT INWARDLY OUT OF WALL ALIGNMENT ALONG SAID WING BAFFLE TO OPEN INTO SAID LOWER DRUM, THE SEGMENTAL PORTION OF THE CIRCUMFERENTIAL ROW OF UPRIGHT WALL TUBES DIRECTLY ABOVE SAID WING PORTION OPENING TO SAID UPPER DRUM AND FORMING DOWNCOMERS AND BEING OFF-SET OUTWARDLY OF THE WALL AND SUPPLYING FLUID TO THE LOWER END OF SAID RISER TUBES, AND MEANS INCLUDING EXTERNAL DOWNCOMERS FOR FLUID FLOW FROM SAID LOWER DRUM TO THE LOWER END OF THE REMAINING SEGMENTAL PORTION OF THE CIRCUMFERENTIAL ROW OF TUBES IN SAID WALL, SAID LAST NAMED TUBES FORMING RISER TUBES EXTENDING UPWARDLY ALONG THE CORRESPONDING SEGMENTAL PORTION OF THE WALLS OF SAID SETTING TO DISCHARGE INTO SAID UPPER DRUM.