US2114224A - Steam boiler - Google Patents

Description

April 12, 1938- D. s. JACOBUS 2,114,224

STEAM BOILER Original Filed Jan. 2, 1955 v n Daxigcl SJacobus Aiioney Fatenteel Apr. E2, 193% STEAM BOILER David S. Jacobus, Montclair, N. J., assignor to The Babcock & Wilcox Company, Newark,

N. J., a corporation of New Jersey Original application January 2, 1935, Serial No. 121. Divided and this application May 21, 1936, Serial No. 80,963

16 Claims.

My present invention relates in general to the construction and operation of high capacity steam generating units, and more particularly to generating unitshaving one or more water tube steam boilers of the bent tube type including steam heating surface and steam and water separating provisions.

One object of my invention is the provision of improved steam heating provisions characterized by an effective arrangement of the superheater tubes relative to gas flow, low pressure drop in the superheater, and an improved supporting arrangement in a boiler; of the character described.

A further object is an improved arrangement of the circulators for furnace wall heating surface in a steam generator having two or more steam boilers receiving heating gases from a common furnace, one of the boilers including steam heating surface.

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 drawing and descriptive matter in which I have illustrated and described a preferred embodiment of my invention.

The figure shown is a partly diagrammatic sectional elevation illustrating one embodiment of my invention.

The steam generating unit illustrated comprises a pair of water tube boiler units above and at opposite sides of a common furnace 55. Each of the boiler units comprises a pair of "upper steam drums 55 and -51 and a lower or mud drum 55. The drums 51 and 55 are connected by a substantially vertical bank of tubes 59, while the drums 55 and 55- are connected by a. divided bank of tubes 55 arranged in three sections 55, 55 and 55. Most of the rows of tubes 50 and 50 are eliminated in the left hand boiler unit and the space occupied by a. return bend superheater hereinafter described. Vertical baffles 5|, 52, 53 and 54 are arranged along the tube banks to provide a plurality of serially connected passes for heating gases from the furnace 55. The drums 55 and 51 are connected by only steam circulators 55, and each drum 51 is elevated above the corresponding drum 55. The elevated position of the rear drums 51 provides an adequate space for washing and dryvisions for this purpose are incorporated in the upper part of each drum 51. A steam and water separator 40 consisting of a twin. arrangement of inclined corrugated plate separator sections extends longitudinally of the drum 51 at opposite sides of the. vertical axial plane thereof and between the discharge of the circulators and one or more steam outlets 11. The steam and water separator illustrated is similar to that disclosed in a patent of James Fletcher No. 2,007,966, granted July 16, 1935. Steam washing nozzles are arranged in front of each separator section along the length thereof to provide a sheet of feed water across the inlets of the separator sections.

The furnace 55 is heated by a pair of oppo sitel'y arranged underfeed stokers 55 at opposite sides of a central ash pit 51. The furnace is desirably completely water cooled, rows of vertical. tubes 55 extending along its sides directly below the boiler units-with the tube row at each side supported from the corresponding drum 55 and connected into the corresponding boiler circulation by having its upper ends connected to the corresponding drum 55 above the normal water level therein and its lower ends connecting to the corresponding drum 55 through pipes 59. The portions of the tubes 55 in front of the tubes 50" are bent and spaced to provide a slag screen.

The two remaining sides of the furnace are also provided with water wall sections consisting of interconnected bottom headers 19 and top headers 11 connected by block-covered tubes 12. In accordance with my invention the headers 15 are connected only to the left hand boiler through downcomers 13 from the mud drum 58 and the headers 1| by riser tubes 14 to the steam drum 55 above the normal water level therein.

The superheater included in the left hand boiler occupies the space between the baflles 5| and 53 and will be protected to a large extent from the radiant heat of the furnace by the ballle 5| and intervening tubes. The superheater com- 1 prises anexternal inlet header 15 receiving steam from the drum 51 through conduits 11. The header 15 is supported as shown by tension members 15 from the setting and aids in supporting the superheater. The superheater tubes 19 extend downwardly from the header 15 in two longitudinal rows at opposite sides of and supporting the baffle 52. At their lower ends adjacent thev baflle 53 the tubes 19 are bent rearwardly and extend upwardly into the space between the baffles 52 and 53 in a return bend nested formation providing a double flow path through each coil in the rear section of the superheater. Each pair of nested tubes is connected adjacent the drum 56 by a Y-fltting 80 into a single tube 8| which extends downwardly along the baiiie 63 to a point adjacent the mud drum 58 and thence upwardly along the bafile Si in successive rearward bends in the space between the baffles SI and 62, terminating in an external outlet header 82 mounted on the right hand drum 56. The tubes in each section of the superheater are thus arranged in a series of parallel flat coils with a double flow through each coil in the rear section and a single flow through each coil in the front'section. The superheating surface is thus divided into two groups, with the total steam flow area in the group nearer the furnace with respect to heating gas flow less than in the other group. With the described steam flow through the superheater, the pressure drop will be substantially lower than if a single flow throughout each coil were employed, and yet a high velocity steam flow will be maintained through the superheater tubes adjacent the furnace.

The tube legs in each coil and corresponding coils in the front and rear sections are united in a unitary self-supporting formation by lugs 83 connecting the otherwise unconnected ends of adjoining tube legs. The unitary coil structures so formed are supported at their upper ends by'the header l6 and connections 84 between brackets on the first upper looped portion of the tube at and the-underside of the drum 56 and at their lower ends by lugs 85 laterally supported by lugs 86 mounted on the upper side of the mud drum 58. With this arrangement the superheater coils will be free to expand downwardly relative to the mud drum.

Each of the boiler units is provided with a top heating gas outlet flue 8B controlled by dampers 89, the position of which may be varied to regulate the heating gas flow through the corresponding boiler unit and thereby control the degree of steam superheat. In this construction the boiler, superheater and furnace wall heating surface is arranged and proportioned in such a way that by regulating the flow of heating gases through the two boilers a uniform temperature of superheated steam may be obtained over a wide range of load conditions, with substantially the same draft losses at full load through the boilers and the same heating gas exit temperatures at approximately half-load.

In the type of steam generator shown the dampers for the boiler which includes the superheater are normally moved to their closed posi tion in starting up to avoid overheating of the superheater tubes. With the present construction however, there is little danger of overheating of the superheater tubes, as the connection of most of the furnace wall heating surface into the superheater boiler circulation will accelerate the circulation in that boiler and cause it to heat up rapidly.

This application is a division of my prior application, Serial No. 121, filed Jan.2, 1935.

While in accordance with the provisions of the statutes I have illustrated and described herein the best form of my 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.

amazes ranged to connect a major portion of said furnace wall water heating surface into the circulation system of said generating unit including steam heating surface.

2. A steam generator comprising a furnace, a pair of steam generating units having separate water circulation systems and arranged at opposite sides of and receiving" heating gases from said furnace, one of said generating units including only water heating surface and the other generating unit including both water heating and steam heating surfaces, plurality of water wall sections lining the walls of said furnace, and conduits arranged to connect the majority of said water wall sections into the circulation system of said generating unit including steam heating surface.

3. A steam generator including a steam superheater comprising a series of vertically extending return bend tubes divided into front and rear sections with respect to the heating gas flow path, the return bend tubes in said rear section being arranged in parallel nested rows and the return bend tubes in said front section being of the same flow area as the tubes in said rear section and arranged in a single row and each directly connected to a plurality of tubes in said rear section by a Y-fittlng, and means for passing steam to be superheated first through said rear section.

4. A steam generator including a steam superheater comprising a series of vertically extending return bend tubes divided into front and rear sections, the return bend tubes in said rear section being arranged in parallel nested rows and the return bend tubes in said front section being arranged in a single row and each connected to a plurality of tubes'in said rear section, and a baflle extending substantially between said front and rear superheater sections and locating said front section in a downflow gas pass and said rear section in an upflow gas pass serially connected to said downflow gas pass.

5. A steam generator including a pair of vertically spaced drums, a bank of steam generating tubes connecting said drums and bent to provide a substantial space between adjacent rows thereof, and a steam superheater comprising a series of return bend tubes positioned in said space and divided into'front and rear sections, the return bend tubes in said rear section being arranged in parallel nested rows and the return bend tubes in said front section being arranged in a single row and each connected to a plurality of tubes in said rear section.

6. A steam generator including a pair of vertically spaced drums, a bank of steam generating tubes connecting said drums and bent to provide a substantial space between adjacent rows thereof, a baflle dividing said space into front and rear vertical gas passes, and a steam superheater comprising a series of return bend tubes positioned in said front and rear gas passes, the return bend tubes in said rear gas pass being arranged in parallel nested rows and the return bend tubes in said front gas pass being arranged Y in a single row and each connected to a plurality of tubes in said rear gas pass.-

7. A steam generator including a pair of vertically spaced drums, a bank of steam generating tubes connecting said drums and bent to provide a substantial space between adjacent rows there- 8. A steam generator including upper and lower drums, a bank of steam generating tubes connecting said drums and bent to provide asubstantial space between adjacent rows thereof, a steam superheater comprising a series of return bend tubes positioned in said space and arranged in parallel flat coils, means connecting the tube legs in each coil into a self-supporting unitary structure, and means for supporting the unitary structures so formed from said upper and lower drums.

9. A steam generator including upper and lower drums, a bank of steam generating tubes connecting said drums and bent to provide a substantial space between adjacent rows thereof, a steam superheater comprising a series of return bend tubes positioned in said space and arranged in parallel flat coils, means connecting the tube legs ineach coil into a self-supporting unitary structure, and means for supporting each unitary structure comprising a pivotal supporting connection between said structure and the upper drum and a supporting connection between said structure and the lower drum constructed to permit downward expansion of said structure relative to said lower drum;

10. A steam generator including upper and lower drums, a bank of steam generating tubes connecting said drums and bent to provide a substantial space between adjacent rows thereof, a steam superheater comprising a series of return bend tubes positioned in said space and divided into front and rear sections, the return bend 'tubes in said rear section being arranged in par- 11. A steam generator including upper and lower drums, a bank of steam generating tubes connecting said drums and bent to provide a substantial space between adjacent rows thereof, a steam superheater comprising a series of return bend tubes positioned in said space and divided into front and rear sections, the return bend tubes in said rear in parallel flat coils with nested tubes in each coil and the return bend tubes in said front section being arranged in parallel flat coils with a single tube in each coil and each connected to a plurality of tubes in a corresponding coilin said rear section, a header positioned above and connected to said coil sections, a tension support for said header, means connecting corresponding section being arranged front and rear coils into a self-supporting unitary structure, and means for supporting each unitary structure comprising a pivotal supporting connection between said structure and the upper drum and a supporting connection between said structure and the lower drum constructed to permit downward expansion of said structure relative to said lower drum.

12. In a steam boiler receiving heating gases from a furnace, a steam superheater comprising a plurality of return bend coils in the flow path of said heating gases, each of said coils having a plurality of tube'portions, the portion nearest the furnace being formed of a single tube having a bifurcation at one end and a portion farther from said furnace being serially connected to said first portion and formed of a pair of tubes joined to the bifurcated end of the first mentioned tube, and means for passing steam to be superheated first through the tube portion farther from said furnace,

13. In a steam boiler receiving heating gases from a furnace, a steam superheater comprising a plurality of flat return bend coils in the flow path of said heating gases, each of said coils having a plurality of tube portions, the portion nearest the furnace being formed of a single tube from a furnace, a steam superheater comprising a plurality of return bend coils in the flow path of said heating gases, each of said coils having a plurality of tube portions, the portion nearest the furnace being formed of a single tube having a bifurcation at one end and a portion farther from said furnace being serially connected to said first portion and formed of a pair of tubes joined to the bifurcated end of the first mentioned tube, and a baiiie extending between said tube portions and locating said portions in different passes of the heating gas flow path.

15.'A steam generator including a pair 'of vertically spaced drums, a bank of generating tubes connecting said drums, a steam superheater including a group of return bend superheating tubes extending having portions adjacent said upper and lower drums, and means for supporting said steam superheating tubes from said upper and lower drums.

16. A steam generator including a-pair of vertically spaced drums, a bank of generating tubes connecting said drums, a steam superheater including a group of vertically disposed return bend superheating tubes extending adjacent said tube bank, means for supporting said superheater tubes at their upper ends, and means for supporting the lower ends of said superheater tubes from said lower drum, said last named means being constructed to permit thermal expansion and contraction of said superheater tubes relaadjacent said tubef-bank and Y

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