US2330240A - Steam generator - Google Patents

Description

Sept. 28, 194-3. RAYNOR 2,330,24U

STEAM GENERATOR Filed June 14, 1941 a Shee ts-Sheet 1 INVEINTOR. ArzlzurE fag nor Attorney Sept. 28, 1943. 5 RAYNOR 2,330,240

STEAM GENERATOR Filed June 14, 1941 6 Sheets-Sheet 2 Fig. 2

I INVENTOR. bu r EBay/702 A tzfiorn ey pt, 2%, 143. A. E. RAYNOR 2,33%0

STEAM GENERATOR Filed June 14, 1941 6 sheetssheet 3 Fig.3

m2 82 lfO 739 INVENTOR.

I Ar/fiuriflayzmr /37 P Aorney Sept 28, 19430 A. E, RAYNOR I STEAM GENERATOR Filed June 14, 1.941. 6 Sheets-Sheet 4 INVENTOR. fl/Z/YUI E Pay/701" I A iiorney Sept. 28, 1943. A. E. RAYNOR STEAM GENERATOR 6 Sheets-Sheet 5 Filed June 14, 1941' J I Z62 m m Z I a n I n IIIIIIIIIIIIIIIIIIIII BY l lri/zurf/Pay/zo} Afiorneg Sept. 28, 1943. A. E. RAYNOR 2,330,240

STEAM GENERATOR Filed June 14, 1941 6 Sheets-Sheet 6 Q \i Q a INVENTOR. Arf/ZZUE 1? ayriof A it, orney Patented Sept. 28, 1943 STEAM GENERATOR Arthur E. Raynor, Rockville Centre, N. Y., as-

signor to The Babcock & Wilcox Company. Newark, N. J., a corporation of New Jersey Application June 14, 1941, Serial No. 397,997

9 Claims.

This invention relates to steam generation, an object of the invention being to accomplish economical and eflicient generation of steam throughout a wide range of boiler load requirements, without sacrifice of combustion efficiency.

The invention also relates to the construction and operation of vapor generators and more particularly to steam generating units characterized by low construction cost, low maintenance, and low floor space requirements.

Another object of the invention is the provision of a vapor generator which is further characterized by simplicity of construction, high operating efflciency, and ease of accessibility to all portions of the unit.

A further object of the invention is the provision of a vapor generator including a fluid cooled furnace fired by pulverized ash bearing fuel, theposition of the fuel introduced and the position of the exit of the products of combustion being such that ash particles released by combustion are cooled in their downward flow and are deposited in a subjacent space.

A more specific object of the invention is the provision of a pulverized fired steam generator in combination with an air heater for combustion air, the combination involving an advantageous arrangement of fuel burners and air heater. In this combination the fuel burners are arranged closely adjacent the airheater so that the air ducts therebetween are of minimum length, the

combination thus materially contributing to improved efiiciency' and low construction cost.

' bustion space or as a subjacent ash cooling zone.

In the drawings:

Fig. 1 is a view in the nature of a vert cal sec-v tion-at a position indicated by section line il ofl=ig.'2;

Fig.'2 is aver-tical section along a plane at right angles to theplane of Fig; l and indicated by section line 2-2 of Fig. l;

Fig. 3 is-a vertical section on the line 3-3 of Fig.1:

Fig. 4 is a horizontal section on the line 4-4 of Fig. l;

Fig. 5 is a horizontal section on the line 5-5 of Fig. 1; and

Fig.6 isa plan, or horizontal section on the section line 6-6 of Fig. 1, showing the relative arrangement of the drum, fuel burners, air heater and the casing through which secondary air passes to the burners.

The divided furnace construction illustrated in Fig. 1 of the drawings contributes to fiexibility of operation under variable loading by reason of selective control of combustion in the separate combustion chambers I0 and I2. By such selective firing regulation heat liberation per unit of wall cooling surface can be varied in accordance with the load requirements. 7

Fig. 1 illustrates sets of pulverized fuel burn- 4' ers l4 and I6, arranged at the tops of the combustion chambers in and I2'. When both sets of'burners are in operation, furnace gases flow from the combustion chamber 1 0 through the gas outlets 20-28 (see Fig. 2) to thelower part of the combustion chamber l2 where they-are joined by the furnace gases from the latter. The combined gases then flow upwardly over the tubular elements of the convections'ection and thence tr:

a flue or duct 31] leading to'th'e air heater 32. Ir Fig. 1, this flow of the gasesis indicated by the arrows 34-43.

The combustion chambers-l0 and I2 of the Fig. 1 unit are defined by long straight upright walls including wall tubes connected into the I boiler circulation. With' this arrangement of flow elements, high rates of heat absorption are possible. By the selective -operation of the bumers. there may be a wide variation in the ratio of heat l beration to heat absorption by the combustion chamber walls. i l r The combustion chambers) and ii! are separated by a partition wall 46-formed by wall tubes directly connected at'their" upper ends to the water space of the steam and'water drum 48. The tubesof the partitionwall 46 are connected at their lower ends to a submerged drum 54 disposed beneath the combustion chambers IO and [2. The large diameter downcomers 50 and 52 (see Fig. 2) connect the ends of the steam and water drum 48 with thesubmerged drum 54.

The steam generatingwall'tubes defining the remainingwalls of thecoinbustion chambers l0.

and i2 have their lower'ends connected to. the

submerged drum 54. -'For example, the sidewalls and 62] (see-Fig. 2) I include the-upright wall tubes64 and 66, the lowerends'of which are supplied with water from" the submerged drum hopper, and are bent under the lower parts thereof so as to communicate with the headers I2 and I4.

Steam and water rising in the side wall tubes 64 and 66 passes to the upper headers 80 and 82 and thence through the tubular connections 85-88 to the drum 48.

For the front wall 90 (Fig. 1) water flows from i the submerged drum 54 through the conduit 82 to the lower wall header 94. From this header it flows upwardly into the steam generating wall tubes 96 to the upper header 98, and thence with the generated steam through the roof tubes I to the drum 48.

The lower water wall header I02 at the rear wall of the setting receives water from the drum 48 our. acts as an agency through which that watei s supplied to the rear wall tubes I86 along the wall I08. At the position IIO these tubes are bent so as to present horizontally inclined sections forming the screen II2 extending across the gas entrance to the convection section. Beyond this screen the tubes extend vertically to define the wall II4 separating the convection section from the furnace I2. Steam generated in these tubes passes to the upper rear wall header I20 and thence through the roof tubes I22 to the drum 4B in the manner indicated in Fig. l of the drawings.

The wall 46 separating the furnaces I8 and I2 includes wall tubes I30 and I32, the latter of which communicate with the drum 54 at one side thereof and the former at the opposite side thereof, as indicated at the bottom'of Fig. 1. These opposite rows of tubes are bent toward each other at a position above the drum- 54 so that they present the horizontally and downwardly inclinedsections I34 and I36. To prevent the accumulation of ash particles upon the drum 54 and other tubular connections associated therewith, the inclined tube sections I34 and I36 are covered by cast-ironblocks I38-I40. From this zone the tubes I 30I'32 extend upwardly in single row alignment to the zone of the gas outlets 20-28. These outlets are formed by bending some of the tubes out of their single row-arrange- I ment and into the furnace I2 while some of the remaining tubes are similarly bent into the furnace I0. Such formations of the tubes to provide the gas outlets are indicated-particularly in Figs. 1 and 5.

From an inspection of Fig. 2, it will be observed that the gasoutlets 2028of the combustion chamber I0 are located partially in the ash disposal zone. Thus, furnace gases and their suspended products in the combustion chamber I0 travel downwardly in a relatively long path throughout which they are subjected to the cooling effect of the furnace walls. Furthermore, the

gases passing through the outlets 2028 make their turn at a position near the lower'end of the combustion chamber, both sets .of circumstances promoting the separation of thealshpar- V ticles which, cooled by the hopper andwalltubes, are disposed in theashpit I 33.v z

The water cooled hopper bottom construction illustrated in Fig. 2, extends from the combus tion chamber I0, past the partition wall 46, across the bottom of the combustion chamber I2, and

below the convection section; The 1riODper-bottom construction and the ash pit thus may be said to be continuous across the lower part of the unit, except for its interruption.- by the submerged drum 54 and the tubes of the partition wall '46.

In Figs. 2 and 3 the ash pit I33 is shown as having a. floor I35 inclined downwardly to a slulceway I31. Normally, the ash pit is closed by the doors I38 which may be opened to provide for the periodic removal 01 the ash to the sluiceway I31.

From an inspection of Fig. 5 of the drawings, it would be noted that there is a gap between each vertical edge of the partition wall 46 and the side walls 60 and 62. This arrangement serves as a means for equalization of pressures between the combustion chambers I0 and I2 when the burners for one of them are not operating. This provision is also of importance in taking care of abrupt changes in pressure conditions in the combustion chambers.

Steam, generated by the furnace wall tubes, is separated from the water in the drum 48, and passes through conduits I40 and I42 to the superheaterheader I44. This header is disposed at one side of the gas pass of the convection section and it communicates, by means of the tubular sections I46, .with the tubular coils of the superheater sections I48 and I50. Steam flowing through these coils passes to the superheater outlet header I52, and thence through the conduits I54 and I56 to one side of the attemperator I 58. From the, other side of the attemperator, the steam, conditioned as to temperature, passes through the tconduits I60 and I62 to the inlet header I64 of the superheater section I66. From the outlet header I68 of this section, steam passes through a conduit I'I0 to the point of use.

Feed water passes through the valve I to the conduit I82 and thence to the economizer inlet header I84. From this header the water passes through the coils of the counterflow economizer section I86 to the intermediate header I90 which also'might be considered as an inlet header for the coils of the parallel flow economizer section I92. The feed water, together with the steam generated therefrom, passes from the coils of the economizer section I92 to the economizer outlet header I94, and thence through the conduits I96 to the drum 48.

In the attemperator I58 the steam is subject to a controlled amount of cooling by reason of the fiow of water to the attemperator through the conduits 203 which communicate with the drum 54. Circulation of water through the attemperator is completed by the risers 2I0-2I2 which connect the upper part of the attemperator shell with the drum 48.

The drum 48 and the upper water wall headers are supported by straps or hangers 220-223, from the elements 226-429 of the setting steel work, and all of the pressure parts associated with the furnace walls are thus supported so as to be free to expand downwardly.

The space between the furnace roof tubes I00 and I22 and the drum 48 is enclosed by the walls 240-244 (Fig. 1) which are associated with other walls 245263 (Fig. 6) to form a casing and ductwork through which secondary air may pass from the air heater 32 to the sets of burners I iand I6, the illustrative arrangements of air heater, burners, and the casing for the secondary air being such that a minimum of casing or ductwork is required.

Fig.6 particularly illustrates the relative ,arrangement of the drum 48, the sets of fuel ;burn-. ersI4 and I6, air heater 32,.and the 'casingor ductwork through which secondary air passes from the air heater to the burners. The .air heater is of a tubular type with furnace gases passing through upright tubes. Air-passes around these tubes and then through the short lateral ducts 210 and 212. It then passes to the casing at the top of the furnaces as indicated bythe arrows in Fig. 6. The secondary air ports for the burners l6 are enclosed by the casings 180-283 which have associated therewith sets of flow regulators 290-493. Similarly, the sets of burners M on the other side of the drum 48 have their air ports within casings 300-303 controlled by sets of air regulators 3l0-3l3.

lihe compact arrangement of, the fuel burners and the air heater relative to the associated parts of the unit not only minimizes installation costs by reducing ductwork to a minimum, but it also minimizes heat losses and otherwise promotes high emciency. It will be noted that the air heater is in substantially the same horizontal zone as the burners and that it is disposed closely adjacent thereto. Furthermore, the secondary air leaving the air heater elements passes around the furnace gas flue and then into an enclosure which constitutes a casing for the top of the furnaces and ductwork for supplying secondaryair to the burners. .What is claimed is: I i

-1. In a vapor generator, an upper elongated steamand water drum, a subjacent pulverized fuel furnace, means forming a convection heat absorbing pass receiving furnace gases from the furnace, means forming hopper bottom surfaces for the furnace, fluid. cooled furnace wall tubes parts of which extendalong the hopper bottom surfaces and co-operate with said means to provide, an elongated'ash discharge throat extending transversely ofthe'drum and below the entrance to the convectionpass,means forming an ash pit below the ash discharge throat and extending therealong, -a partition wall dividing the furnace into, two combustion chambers, the partition wall including vertically extending tubes arranged in flzlOW parallel to the axis of said drum, some of; said partition wall tubes having portions near the hopper bottom bent out of the plane of the wall to provide gas outlets from onecombustion chamber to the other, pulverized fuel burners at the upper portions of the combustion chambers for independently firing them,

and means including large diameter downcomadditional steam generating. wall tubes arranged as a partition wall separating the furnaces, said additional tubes being bent out of their wall arrangementat a position toward the lower part of the furnaces so as to provide a furnace gas outlet for the first furnace, means for independently firing th 'furnaces at positions above said outlets, and a convection section including spaced tubes beyond the second furnace, the'tubes of said convection section being exposed to.the

gases fromboth of'saidfurnaces.

.3. Ina steam generator, two independently fired furnaces arranged in series as to gas fiow and separated by a partition wall including steam generating Wall tubes disposed in wall forming alignment, said partition wall having its lateral edges spaced from the side walls of the furnaces so as to provide free inter-furnace communication to prevent damage to said wall by differential pressures between the furnaces,

the partition wall also being of such construction over at least the major part of its face that no substantial gas flow takes place between its adjoining wall tubes. v

4. In a steam generating installation, a steam and water drum disposed at the top of a boiler setting, steam generating furnace wall tubes forming two vertically elongated furnaces below said drum, some of said tubes being disposed in a partition wall alignment between said furnaces and directly below said drum, furnace roof tubes extending from opposite furnace walls toward said partition wall and thence to positions at which they are connected to the drum, downshot pulverized fuel burners disposed at the tops of said furnace so as to project the elements of combustion between the furnace wall tubes into the furnaces, a vertically elongated convection section including a gas pass extending along the side of one of the furnaces and having its inlet above an ofiset of one the furnaces, the tubes of the partition wall being bent so as to provide a gas outlet from the other of said furnaces for the passage of gases to the inlet of the convection section, an air heater adjacent the top of the convection section, and means forming ductwork and a casin for the passageof preheated combustion air from the air heater to the burner positions at either side of said drum, said last named means including the drum and walls at both sides thereof.

5. In a steam generating installation, fluid conducting tubes defining the walls of two vertical elongated pulverized fuel fired furnaces, means for firing said furnaces from the tops thereof, said wall tubes including the partition wall separating the furnaces and formed with openings near the bottom of the furnaces for furnaces gases to pass from one furnace to the other, means including some of said wall tubes.

for defining a vertical elongated convection section arranged alongside one of the furnaces and having its furnace gas inlet directly above a lateral offset of one of the furnaces, the last mentioned wall tubes having parts thereof bent so as to form a furnace gas screen extending across the inlet of the convection section, means including fluid cooled tubes defining a hopper bottom extending across the lower portions of both furnaces and underneath the convection section.

6. In a steam generating installation, means forming furnaces, sets of burners for firing the furnaces, a steam and water drum disposed between said sets of burners, a convection section to which the gases pass from the furnaces; an air heater disposed at subtantially the same level as the burners and closely adjacent thereto, said air heater being adapted to be heated by the furnace gases after they have passed through the convection section, and a combined furnace casing and duct work leading from the air outlet of the air heater to the secondary air ports of the burners, said casing enclosing the space between the roof of the furnace and said drum.

'7. In a steam generator, a first furnace the walls of which are defined by steam generating tubes, a. second furnace including steam generating ,wall tubes connected into boiler circulation,

ently firing the furnaces at positions above said outlet, said additional tubes being closely spaced over the predominating part of the face of the partition wall so as to limit diffusion of gases from one furnace to the other, and a convection section including spaced tubes beyond the second furnace, .the tubes of said convection section being exposed to the gases from both of said furnaces.

8.v In a steam generator, a first furnace the walls of which are defined by steam generating tubes, a second furnace including steam generating wall tubes connected into boiler circulation, additional steam generating wall tubes arranged as a partition wall separating the furnaces, said additional tubes being bent out of their wall arrangement at a position toward the lower part of the furnaces so as to provide a furnace gas outlet for the first furnace, burners for independently firing the furnaces at positions above said outlets, said adidtional tubes being closely spaced from the burner zone downwardly to the level of said outlet to limit diffusion of gases from one furnace to the other when the furnaces are fired differently, and a convection section including spaced tubes beyond the second furnace, the tubes of said convection section being exposed to the gases from both of said furnaces.

9. In a steam generator, a first furnace the walls of which are defined by steam generating tubes, a second furnace including steam generating wall tubes connected into boiler circulation, additional steam generating wall tubes arranged asa partition wall separating the furnaces, said additional tubes being bent out of their wall arrangement at a position toward the lower part of the furnaces so as to provide a furnace gas outlet for the first furnace, means for independently firing the furnaces at positions above said outlets, said additional tubes being closely spaced from the burner zone downwardly to the zone of said outlet to limit diffusion of gases from one furnace to the other, and a convection section including spaced tubes beyond the second furnace, the convection section having a gas inlet communicating with the second furnace and disposed opposite said gas outlet, the tubes of said convection section being exposed to the gases from both of said furnaces.

ARTHUR E. RAYNOR.

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