US2097268A - Steam generator - Google Patents

Description

Get, 26, W37. 5. 6. BEST STEAM GENERATOR Filed Nov. 19, 1935 10 Sheets-Sheet 'l mm N R lllllll llk INVENT OR.

WITNESS.

ATTORNEYS.

Get 26, 1937. s. c. BEST 2,097,268

STEAM GENERATOR Filed Nov. 19, 1935 10 Sheets-Sheet 2 J/ o/v C. 5567.

INVENTOR.

' f: ATTORNEYS.

S. C. BEST STEAM GENERATOR Get. 2%, 1937.

Filed Nov. 19, 1935 10 Sheets-Sheet 3 J/Mo/v 6. 55.52

INVENTOR. BY t WITNESS.

ATTORNEYS S. C. BEST STEAM GENERATOR @c&. 26, 1937.

Filed Nov. 19, 1935 10 Sheets-Sheet 4 J/MO/V CI 55577 1N VENTOR. 0

ATTORNEYS.

WITNESS.

S. C. BEST STEAM GENERATOR Filed NOV. 19, 1935 10 Sheets-Sheet 5 INVENTOR J/MOA/ C 5557. 0

IIIII IIIIIIIIIIIIIIIII ATTORNEYS.

Oct. 26, 1937. s. c. BEST STEAM GENERATOR Filed Nov. 19. 1935 10 Sheets-Sheet 6 INVENTOR. o/ v ATTORNEYS.

NI TNE 561' S. C. BEST STEAM GENERATOR Oct. 26, 1937.

Filed Nov. 19, 1955' NN NN J/Mo/v C. 55:7.-

INVENTOR.

a n W w ATTORNEYS.

Oct. 26, 1937. s 3, BEST 2,097,268

STEAM GENERATOR 4 Filed Nov. 19, 1935 10 Sheets-Sheet 9 FIG. 22

J/Mo/v C. 55.57:

INVENTOR.

ATTORNEYS.

IV/ TNESS.

S. C. BEST STEAM GENERATOR Fil N v. 9. 1935 10 Sheets-Sheet 10' PIC; 24

FIG:

FIG? 25 R O m. M/ a m v m o n A Patented Oct. 26, 1937 UNITED STATES,

PATENT OFFICE STEAM GENERATOR Application November 19, 1935, Serial No. 50,534

19 Claims.

This invention relates to improvements in steam generators of the type which is adaptable to the utilization of combustible fuels in solid, liquid, or gaseous form, the burning of which produces heat to generate steam from water, which has a rapid,

positive, and natural circulation.

Whereas the objects of the invention are numerous, one of the more important objects resides in a steam generator consisting of a single compact structure in which the radiant heat and air infiltration losses are reduced to a minimum, space is saved, the initial cost of a masonry brick enclosing structure is eliminated, and the maintenance of furnace refractories is greatly reduced,

'15 thus making more practical and economical for supply of relatively cooler water and by reason of the fact that all circulating tubes are sub- 30 stantially vertical; to provide a steam generator unit containing a maximum of steam generating surfaces in a minimum of space; and to provide a water line which is relatively low and which is steady at all ratings because of the balanced ring 35 flow circulation.

Another object .of the invention consists of a steam generator wherein the combustion space of the integral boiler and furnace is formed by means of water cooled furnace side walls, a re- 1 40 fractory or water cooled bridge wall, and a refractory or water cooled front wall, the water wall cooling tubes forming secondary but highly efficient steam generating elements which constitute an integralpartbf the boiler and are so connect'd therewith through headers as to promote natural ring flow circulation of the water.

A further object of the invention is the provision of alsteam generator wherein all water cooling tubes as well as the water wall headers and 50 connecting tube circulators are contained entirely within the casing or setting and are swept constantly by the hot gases of combustion. I

A further object resides in a steam generator in which allconnections between integral parts 55 are expanded metal to metal joints, thereby eliminating gaskets and bolted or screw joints, and wherein the various parts are so arranged as to be readily accessible for repair orreplacement purposes.

A further object of the invention resides in a 5 steam generator having the above features which may have incorporated therein an economizer, or superheater, or both, without changes in construction; or rearrangement of the parts.

A still further object is to provide a steam 10 generator of such design as to preclude the accumulation of any material amount of ,soot and dirt, and which retards the adhesion of fused particles of ash. Furthermore, the novel construction and arrangement of parts facilitates the cleaning of the heating surfaces of the generator by a lesser number of soot blower elements than is required for the cleaning of corresponding size generators heretofore designed.

With these and other objects in view, the invention resides in the novel construction, combination and arrangement of parts, the essential features of which are hereinafter fully described in the following specification, are set forth in the appended claims, and are illustrated in the accompanying drawings, in which:

Figure 1 is a front elevational view of my improved steam generator.

Figure 2 is a rear elevational view of the same.

Figure 3 is a vertical longitudinal sectional view.

Figure 4 is a horizontal sectional view taken on a plane just above the soot blower shown in Figure 3.

Figure 5 is a horizontal sectional view taken on the plane just below the bottom of the lower V drum. I

Figure .6 is a vertical transverse sectional view, the left half of this view'being taken forward of the bridge wall, and the right half taken rear- 40 wardly of the bridge wall.

Figure '7 is an enlarged detail horizontal sectional view on the line 'I-'=-'l of Figure 3.

Figure 8 isa detail inside el evational view of the water wall armor with portioris broken away and shown in section. Figure 9 is a detail horizontal sectional view on the line 9-9 of Figure 8.

line |2-i2 of Figure 11 with one end of the dry pan broken away and shown in section.

Figure 13 is a vertical longitudinal sectional view of the modified form of steam generator.

Figure 14 is a detail vertical sectional view showing a-modified form of water wall header for use in generators equipped with an inclined multiple retort underfeed stoker.

Figure 15 is a fragmentary vertical transverse sectional view of a modified form of superheater.

Figure 16 is a detail vertical sectional view of a modified form of water cooled front wall and .fire arch.

Figure 17 is a vertical transverse sectional view taken on the line l'I'--il of Figure 16.

Figure 18 is a detail vertical longitudinal sectional view of a modified form of water cooler bridge wall.

Figure 19 is a vertical transverse sectional view on the line i9i 9 of Figure 18.

Figure 20 is a detail vertical longitudinal sectional view of a further modified form of water cooled bridge wall.

Figure 21 is a vertical transverse sectional view on the line 2l2l of Figure 20.

Figure 22 is a front elevational view with parts broken away in section of a modified form of superheater.

Figure 23 is a vertical longitudinal sectional view on the line 23-23 of Figure 22.

Figure 24 is a vertical longitudinal sectional view of a further modified form of steam generator.

tional view on the line 25-25 of Figure 24.

Figure 26 is a detail vertical transverse sectional view on the line 26--26 of Figure 24.

Figure 27 is a still further modified form of steam generator.

Figure 28.1s a detail vertical sectional view of a modified form of front water wall header.

Referring to the drawings by reference characters, the numeral i .designates a foundation on which the steam generator is set and which gen erator includes a four side wall and top wall structure or setting consisting of a solid refractory front wall Ii, refractory side walls |2|2, an insulated rear wall i3, and a refractory roof or top wall 14. The front, side, and top walls are covered by a thickness of insulation. i5, and these walls are enclosed in an outer steel casing l6.

Rising upwardly within the walled structure and extending transversely thereof is a refractory .tion chamber [9 may be fired by. any of the conventional methods, but in the drawings I have shown an automatic coal stoker 2 I.

Extending the length of the wall structure and supported independently thereof at the front and rear by steel frames, is a top water and steam collectingdrum 22. The drum 22 is disposed centrally of the wall structure at the top thereof, and the exposed portions of the drum are covered by insulatingmaterial and the outer steel casing. Extending inwardly from the front end of the 'drum 22 is a water feed pipe 23, the same terminating adjacent the rear end thereof, which Figure 25 is a detail vertical transverse secrear end is the coolest portion of the drum by reason of the fact that the heated gases from the .furnace or combustion chamber escape from the generator at the top rear through, the smoke outlet 24.

Mounted within and adjacent the bottom of the compartment 20 and extending from a point adjacent the bridge wall I! to and through the rear wall i3 is a bottom water drum 25, the same being disposed in vertical alinement with the top drum 22. Boiler circulating tubes 26 which may be termed primary heating elements connect the water and steam drum 22 and the water drum 25. The tubes 26 are arranged in rows and are staggeredwith respect to the general direction of the gas fiow as shown in Figure 4 and which will be more fully explained hereinafter. Certain of the outermost tubes or primary heating elements designated 26' extend downwardly along the refractory side walls and although they connect with the lower drum 25, they act as water wall cooling tubes.

In the form of my steam generator shown in Figures 1 to 12 inclusive, I employ three spaced baffles 21, in the compartment 20, the end two of which extend downward from the roof while the intermediate baifle extends upward from the floor. Therend baiiles terminate short of the top of the drum 25 and the intermediate baffle terminates short of the top drum 22 and coact to a provide an undulant passage for the smoke in its passagefrom the combustion chamber I9 to the smoke outlet 24. The three lapping baiiles extend transversely of the compartment 20 and pro- .vide the generator unit with a four pass boiler, the circulation path' of the heated gases being shown by arrows in Figure 3 of the drawings. In

' a modification shown hereinafter in Figure 13,

the generator unit includes but two bailles which provide a three pass boiler with the escape of smoke and gases at the bottom rear of the structure and which arrangement may be desirable under various conditions.

Water wall tube headers 28 extend substantially the length of the side walls i2|2 on substantially the same horizontal level as the grate line of the furnace. Water circulating tubes 2! connect the bottom water drum 25 with the water wall headers'at the rear end thereof, the saidv tubes 29 extending from the drum 25 as best seen in Figure 6. The rows of tubes 26 disposed rearwardly of the plane of the end baflie 21 are termed downcomers and constitute a rear group A of primary heating elements'while those rows of tubes 26 forward of the intermediate baiiie 21- constitute a group B of upcomers or primary heating elements.

Furnace water wall tubes 30 connect the top, water and steam drum 22 with the headers 26,,and are disposed adjacentthe inside of the refractory side walls. The outside rear boiler tubes are distinguished from the other boiler tubes 26 and 26' by the numeral 36a and they function as downcomers or circulating tubes which connect the rear ends of the side wall headers 28 with the upper water and steam drum 22. These tubes 3.0 and 30a connect the headers with the.drum 22 forward and rearward respectively of the group of outerlintermediate circulating tubes 26'. The tubes 30 serve as heating elements and convey the water from the headers back up to the water and steam drum 22. The top ends of the water wall tubes 30, the outside rear boiler tubes 30a and the outer circulating tubes 26' are curved inwardly and join the drum 22 on a plane arm of its horizontalaxis while the outermost group of tubes 26' connect at or on a plane of said horizontal axis.

In this construction of the steam generator and the modifications to follow, all joints between integral parts are expanded metal to metal, thereby eliminating gaskets, and bolted or screw joints.

The bottom ends of the water wall tubes 30 which are-disposed in the furnace compartment l9 and their points of connection with the headers 28 are protecmd by an armor wall 3| which is cooled by the circulating water in the furnace water -wal1 tubes and headers, all of which constitute an effective clinker chill just above the plane of the grate l8.

The armor wall 3| is constructed of pairs of coacting armor wedge blocks 32 and shown in detail in Figure 10. Each armor block is constructed of cast iron or super-refractory'mateterial and has its outer side provided with a concavity 34 which extends the length thereof to snugly fit around approximately one-half the circumference of a water wall tube 30. The inner face of each armor block is inclined as at 35, and when a pair of coacting armor blocks are inserted between a pair of adjacent tubes 30 with their coacting inclined surfaces together, they are wedged into engagement with respective adjacent tubes 30. The wedge,blocks rest upon the headers 28 when fully seated in position and by placing them between successive tubes 30, a substantially continuous armor wall 3| is obtained which is easily replaced or renewed from the furnace side.

In operation of the steam generator so far described, it will be understood that any of the conventional firing methods may be employed for providing the necessary heat within the combustion chamber or furnace IS. The generator is supplied with water by the feed pipe 23 which water initially enters the top drum 22 and gravitates to the bottom water drum 25, headers 28 and other elements forming part of the circulating system. The heated gases evolved by combustion within the furnace or combustion chamber I 9, radiate heat to the forward group of s de water wall cooling tubes 30, and the-water cooled surfaces forming the roof-of the combustion chamber-19, all of which induces effective steam generation within the secondary heating elements. The gases from the combustion chamber 19 pass therefrom through the passage between the top of the bridge wall l1 and roof into the compartment 20 and act upon the primary heating elements or tubes 26 As previously mentioned the tubes 26 are arranged in rows, staggered with respect to the general direction of the gas flow from the combustion chamber to the gas outlet 24 which is considered a distinctive feature in the general design of curved tube boilers. As the gases pass over, around and between the tubes 26, on their way to the gas outlet 24,,the d rection of flow is reversed by the gas baffles 21, caus ng cross.flow as well as parallel flow, thus obtaining better diffusion of the gases with resulting better heat absorption by the tubes 26. The baffles 21 cause the gas flow to travel in an undulant path from the combustion chamber l9 to the outlet 24.

The bailies 21 concentrate the hot gases on the heating surfaces, and avoid short circuiting of the same. They do not unnecessarily impede the free fiow of heated gases evolved by combustion, for these gases freely pass over and around and across the tubes, reversing their direction of flow and becoming thoroughly diffused, thus inducing maximum heat transfer. The heated gases sweep the bottom of the top drum 22 and the 'top of the lower drum 25 and diminish in temperature as they'travel toward the outlet 24.

It is the heat subjected to the primary heating,

tubes 26 by thehot gases as they pass over the bridge wall that causes the water to rise in the upcomer group B. The forward group of tubes 26 receive the'hottest gases, causing the gener-' ation of steam therein, and a decrease in the density of the water, thereby inducing upward.

circulation.

' The circulation of water in the system after heated in the above mentioned manner is forward through the headers 28, upward through the secondary heating elements 26' and furnace water wall tubes 30 to the top drum 22, upward through the front rows of primary heating elemerits or tubes 26 (group B) to the top drum 22,,

and downward through the rear rows of tubes 26 (group A) and 30a. to the lower drum 25, back to the headers 28 by way of the tubes 29. The rear group of tubes 30a act as downcomers or circulators to assist in providing a direct constant supply of circulating water-for water cooling the furnace side walls and thereby inducing a backward and downward circulation in and from the upper drum 22. As previously mentioned, the other or intermediate group of outside tubes 26' connect with the lower drum and the forward tubes of the said group may act as upcomers or steam generating tubes while the rear tubes of said group may function as downcomers or cir-' culating tubes. This system produces in effect, a double ring-flow circulation of water which is positive and rapid, which increases heat absorption, and which maintains a steady water line. With the steam outlet 35 located adjacent the rear of the top water and steam drum 22, the necessity of internal and steam water baflles usually provided within the water and steam drum is eliminated.

By constructing a steam generator unit in the manner hereinbefore set forth wherein all tubes are substantially upright and the gas bailles are vertical, the accumulation of any material amount of soot and dirt thereon is eliminatedand the adhesion thereto of fused'particles of ash is soot-blower element small size generator unitsand facilitates the cleaning of larger units by a lesser number of mechanical soot blower elements than now used in connection with other. corresponding size generator units. In the drawings, one mechanical soot blower element 31 is shown, which extends inwardly through the rear wall l3 and terminates adjacent the bridge wall l1. The soot blower element 31 passes centrally through the right and left banks of tubes 26 as best seen in Figure 6 of the drawings, and through the baffles 21. The soot blower element is supported by bearings which are attached to the inner tubes of certain rows of primary steam generating tubes or elements 25 at several points throughout the length of the element, as required. The soot blower element is provided with nozzles which direct jets of steam between adjacent rows of tubes, radially from and at right angles to the element as it is rotated. The mechanical soot blower element such asshown at 31 is old in the art so that a detailed description of the same not believed necessary.

A blow off pipe 38 extends from the bottom rear of the water drum 25 and connects with a pipe line 39, and arranged in the pipe 38 is a blow off valve 40. Blow oif pipes 4| also extend from the bottom rear of the two headers 28 and are joined with the blow off pipe line 39, .exteriorly of the generator unit casing. Blow of! valves 42 are arranged in the blow off pipes 4|. All of the valves 40 and 42 are exteriorly disposed relative to the generator casing. A blow-off valve 43 is also arranged inthe pipe line 39. One or both ends of thewater wall headers 28 may be provided with master manhole openings.

Extending from the top of the top drum 22 adjacent the outlet 24 and rearward of the safety valve outlet nozzle 36 is a steam outlet nozzle or coupling 44. Suspended within the top drum 22 above the water level thereof is a dry steam pan or pipe 45, the same being supported at its ends by brackets 46 extending downwardly from the top of the drum. The dry steam pan or pipe 45 consists of a metal cylinder having perforations 41 along the top thereof and a stack 48 rising upwardly into the nozzle or coupling 44. The dry steam pan or pipe is suspended in a slightly inclined position so that the stack end is higher than the other end. The lower end has two drain openings 49 in the bottom thereof. The dry steam pan or pipe extends to the rear end of the top drum which is swept by the heated gases as they pass to the chimney outlet 24. Dry steam from the drum 22 enters the dry pan through the openings 41 from where it passes out through the stack 46 to the superheater now to be explained.

Connected to the nozzle or connector 44 is one end of a pipe'50, the same extending downwardly adjacent the exterior of one of the side walls l2 and terminating approximately midway thereof and to which a short horizontally disposed pipe or manifold 5| is connected by means of an elbow 52. The free end of the pipe section 5| is closed and joined to this pipe section 5| are one end of superheater tubes or elements 53. The tubes or elements 53 extend transversely within the compartment 20 just rearward of the bridge wall and are looped and extended outward beyond the same side wall from which they enter the compartment. A coupling pipe section or manifold 54 receives the return ends of the superheater tubes or elements and to which a pipe line may be connected to carry the superheated steam to any device intended to receive the same. To accommodate the superheater tubes or elements 53 within the compartment 26, adjacent rows of the group of tubes 30 and circulating tubes 26 are spread apart as seen by reference to Figure 3 of the drawings. The superheater tubes or elements 53 are subjected to the intense heat of the heated gases after passing over the bridge wall l1, and the heat therefrom transforms the dry steam from the steam drum 22 into superheated steam. N

In Figure 13 of the drawings, there is shown a modified construction of' steam generator wherein the principle of operation is the same as that previously described, but which I term a three pass boiler with the heated gases expelled from the rear bottom instead of at the rear top. The'settingis substantially the same as that previously described and a description of the same is not believed necessary, thus similar reference characters hereinbefore referred to will designate like parts in Figure 13.

In Figure 13, the numeral 54 designates the top water and steam drum, 55 the lowerwater drum, and 56 the circulating tubes or primary heating elements connecting the drums 54 and 55. The tubes 56 are divided into three groups by a pair of spaced baflles 51, one extending downwardly and the other extending upwardly. The groups are identified as a rear upcomer group C, an intermediate downcomer group D, and a front upcomer group E. The heated gases of combustion take the path indicated by the arrows, and are exhausted through an outlet conduit 58 at the bottom rear of the setting. Feed water enters .the lower drum 55 at the rear through a feed pipe 59.

The interior of the drum 55 is divided into two separate compartments by a transverse partition 60, the C group of tubes 56 entering the rear compartment of the drum 55 and the groups D and E of said tubes entering the forward compartment thereof. The group C and rear compartment of the drum 55 constitutes an integral economizer by which feed water entering the generator may be preheated by the gases of combustion before rising to the water and steam drum 54 through the upcomer group of tubes C.

The side wall headers 6| in Figure 13 extend rearwardly from the front wall of the setting but terminate short of the rear thereof, and water wall tubes 62 connect them with the water and steam drum 54. Water wall circulating tubes 63 connect'the front end of the lower drum 55 with the side wall headers 6|.

The circulation within the steam generator shown in Figure 13 is as follows: Feed water enters the rear of the bottom drum through the feed pipe 59 then upward through C group of tubes 56 to the water and steam drum. From the water and steam drum 54, downwardly through group D of connecting tubes 56 to lower drum 55, through tubes 63 to headers 6|, forwardly through the headers, thence upwardly through water wall tubes 62. The front group E of tubes 56 act to convey heated water from the front end of the drum 55 to the top drum 54, for all these 'tubes are swept by the heated gases immediately after the gases pass over the bridge wall In Figure 14 there is shown a modified form of water wall header 64,'the forward end of which is downwardly and rearwardly inclined to follow the drop of an inclined multiple retort underfeed stoker 65. The lower ends of the water wall tubes 66 extend at right angle to the angle of inclination of the header 64 but said lower ends are provided with bends so that the major length of the tubes 66 may be vertically disposed.

In Figure 15, there is illustrated a modified form of integral superheater which includes superheated tubes 61 which extend radially from the top of the water and steam drum 54', and downwardly through the roof covering into the boiler proper where they are extended hori- 'zontally and transversely as at 68, then looped as at 69, andextended horizontally and'transversely as at HI. The portions III of the superheater tubes extend through a side'wall of the setting and radially connect with a superheater header II. The superheater tubes may be located between adjacent rows of primary circulating tubes 56' where they w'ill'be swept by the hot gases from the combustion chamber, or they may be located forward of the front row of tubes 56' adjacent the bridge wall and thus exposed to the" radiant heat of the furnace. By the construction shown, it will be seen that a minimum amount of steam conveying pipes requiring insulation are exposed. All joints in the superheater are expanded metal to metal thereby eliminating all pipe joints.

In Figures 16 and 17, the numeral I2 designates a front furnace wall having fire door openings I3 therein. Supported by the setting of the front wall and extending transversely thereof directly above the fire door openings, is a front Water wall header I4, one or both ends of which can be provided with a master hand hole cover I5 for access thereto. Opposite ends of the front water wall header are connected with the side water wall headers I6 by vertical pipes or tubes 11. Extending upwardly from the front water wall header I4 are front water wall tubes I8 which radially connect with the lower periphery the drum I9 in the same manner as described in the preceding forms of the invention.

From the construction shown in Figures 16 and 1'7, it will be seen that the front water wall header I4 and front water wall tubes I8 are arranged in the boiler circulation for they are supplied with water from the side wall headers. Also, the front water wall header I4 not only provides a water circulating medium for the front water wall tubes I8, but it also forms water cooled fire door arches I which eliminate the maintenance of the usual rea header 82, the ends of which terminate in spaced relation to the side wall headers 8| to enable lengthwise expansion of the header 82. The header 82 is connected to the front end of the lower water drum- 83 by tube nipple connections 84 for supplying water to the header 82. Extending upwardly from the header 82 and passing through the baflie 88, are bridge wall water cooling tubes 85, the same connecting at their top ends to the bottom periphery of the upper water and steam drum 88. By this construction of bridge wall, the baflie 88 deflects the radiant heat of the furnace and hot gases of combustion around and away from the front end of the lower drum 83, and the highly heated refractory material will also serve to aid ignition and complete combustion of the furnace fuel. The header 84 and water cooled bridge wall also provide a non-clinker forming back for a solid fuel bed. Cast iron water wall armor may be used at the bottom of the refractory bridge wall baflle on top of header 82 the same as previously described so as. to form a clinker chill. Furthermore, the water cooled bridge wall is an integral part of the boiler and adds efiective steam generation surface thereto while protecting the front head of the lower drum 83 and making the head readily accessible for cleaning purposes and periodic inspection through openings 81 in a transverse partition 88 which'closes the space between the floor of the setting and the header 82. The openings 81 are normally closed by doors 89.

Figures 20 and 21 illustrate a modified form of water cooled bridge wall, and those parts which I are identical with corresponding parts shown in Figures 18 and 19 are identified by like reference characters. However, in this form, the refractory partition is designated 88' and extends upwardly and forwardly into the furnace or combustion chamber 98. The bridge wall water cooling tubes 85 pass through the upwardly and forwardly curved partition and continue forwardly tions, the water cooling tubes 85' constitute a water cooling arch for the furnace 98, for they carry the water from the header 82 upwardly and forwardly. The refractory arch 88' aids in lgniting and effecting complete combustion of the fuel, while the heated gases pass through the spaces-between the arch cooling tubes 85 which in this instancealsoact as a slag screen.

In Figures 22 and 23 there' is shown a steam generator similar to that shown in Figures 1 to 7 12 with the exception of a modified water cooled bridge wall, arch, slag screen, superheater, and to show how the side wall headers may be dropped to a plane below the bottom water drum. The refractory bridge wall in this form is designated 92 and after rising vertically a suflicient distance to shield the bottom drum and deflect gases the same extends forwardly and upwardly, and terminates in an angularly upwardly extension 93. a A header 94 extends transversely beneath the lower drum and connects therewith through tubes 95. Water cooling tubes 98, extend from the header 94 and follow the contour of the bridge wall, thence forwardly through the front wall of the setting where they connect with a header 91, which in turn is connected by tubes I 98 tothe top water and steam drum. The water cooling tubes 98 serve the same purposes as the bridge wall water cooling tubes 85 and 85 hereinbefore described.

The superheater tubes 89 extend inwardly of the furnace from the headers I88 and I8] disposed exteriorly of the front wall and are in-' terposed between the roof of the setting and the arched portion of the water cooling bridge wall tubes 98. The steam inlet header I88 is connected to a pipe I82 which leads to the steam 'outlet nozzle on the top of the top water and The heated gases of combustion before described is illustrated but the structural design is somewhat different. This type of steain generatorhas been designed for operation by the use of pulverized fuel and includes a low refractory end wall I84 having a burner opening I85 therein, while a water cooled bridge wall I86 extends inwardly and upwardly therefrom. The bottom water drum I8'I is disposed directly above the wall I84 and connects with the top drum I88 by the primary circulating tubes I89, swept by the heated gases by reason of the circuitous path created by the spaced stag- -er ends of the tubes partment H2 at an inclined angle as at H5 to' connect with the header on the sideopposite to which the said tubes rise as best seen in Figure 26. A smoke outlet H6 is provided in the top of the front end wall. The circulation is the same as that described in the previous designs of boilers, but in this design the water'wall cooling tubes III also form a water cooled floor for the combustion chamber H2. The crossing portions H5 of these tubes are inclined to promote circulation and for ease in removing soot and dirt accumulation within the combustion chamber.

In Figure 27 a still further modified design of generator has been illustrated and which is *quite similar to the design shown in the preceding form with the exception that in this instance, the side wall headers are on the plane with thebottom drum and the front wall H6 of the setting is provided with vertical water cooling tubes II], the upper ends of which connect with the top water and steam drum in the same manner as previously described. The low- H'I extend outwardly through the front wall at a down angle and connect with a front water wall header H8 disposed exteriorly of the front wall H6. A header H9 extends. transversely of the exterior of the rear wall I28 and is disposed on a plane below that of the header H8. Tubes I 2| connect the headers H8 and H9 and the said tubes extend in a rearwardly inclined direction to provide a water cooled floor for the combustion chamber I22. Vertical tubes I23 connect the' header H9'with the bottom water drum and the circulation of water is from the bottom drum, down through the tubes I23, header H9, tubes I2I, header H8, tubes III to the'top drum. The side walls below the side water wall headers may be air cooled, the circulating air providing pre-heated air for combustion.

In Figure 28, a modified form of front wall header H8 is shown and is connected by the 7 lower ends of straight vertical tubes H1 and with the front ends of circulating tubes I 2I. The front wall is recessed or stepped in as at I24 to receive the header H8. This construction eliminates the angular bend in the front water wall tubes shown in Figure,-27.

From the foregoing description taken in connection with the accompanying drawings, it will be understood that this design of boiler or generator provides a double ring-flow water circulation with only two drums. One of the principal paths of circulation cools the furnace while at the same time steam is effectively generated. The steam bubbles generated and ascending through the water in the furnace water wall tubes produce a movement in the direction they travel; Also, throughout the several modified designs of steam boilers or generators herein shown and described, all Water wall and boiler tubes are vertical substantially throughout their lengths to promote rapid circulation, for it is well recognized that the path promoting the greatest velocity of wateris in a directly vertical path.

Whereas, the boiler construction herein shown and described embodies single top and bottom drums, Ido not wish to be restricted thereto, for more than one of such drums may be provided if desired without departing from the spirit of the invention. v

While I have shown and described several modifications of the invention, I wish It to be understood that such other designs, alterations and changes as come within the scope of the'appended claims may be resorted to if desired.

Having thus described the invention, what I claim as new and desire to secure by Letters Patent of the United States, is:- I

1. In a steam boiler, a setting having side walls, an upper water and steam drum, a lower water drum, headers extending horizontally along said side walls, tubes connecting said lower water drum and said headers, rows of tubes constituting primary heating elements extending downwardly from said upper drum, the rows of tubes being staggered relative to each other, the outermost tubes extending downwardly adjacent said side walls, certain of said outermost tubes being connected to said headers and constituting water circulating tubes to assist in providing a constant supply of circulating water for water cooling said side walls andthereby inducing a water circulation in and from the upper drum, while the other outermost tubes and remaining primary heating tubes are connected to said lower drum and constitute steam generating tubes.

2. In a steam boiler, a setting having side walls, an upper water and steam drum, 2. lower Water drum, headers extending horizontally along said side walls, tubes connecting said lower water drum and said headers, rows of tubes co'nstituting primary heating elements extending downwardly from said upper drum, the rows of tubes being staggered relative to each other, the outermost tubes extending downwardly adjacent said side walls, certain of said outermost tubes being connected to said headers and constituting water circulating tubes to assist in providing a constant supply of circulating water for water cooling said side walls and thereby inducing a water circulation in and from the upper drum, while the other outermost tubes and remaining primary heating tubes are connected to said lower drum and constitute steam generating tubes, a combustion chamber within said setting forward of said rows of tubes, said headers extending into said combustion chamber, and upcomer tubes connected to said headers and rising upwardly within said combustion chamber along the side walls thereof and'conmeeting with said upper water and steam drum.

3. In a steam boiler, a setting having a smoke outlet at the rear thereof, an upper water and steam drum extending the length of said setting, a bridge wall extending transversely of said setting and dividing the interior thereof into a front furnace compartment and a rear primary heating compartment, a lower water drum within said primary heating compartment, side wall headers extending into said furnace compartment and said heating compartment, tubes connecting said lower drum and said side wall headers, water wall tubes rising upwardly from said headers and connected with said upper drum, rows of tubes constituting primary heating elements connecting said upper and lower drums, the primary heating tubes of one row being'staggered with respect to the tubes of the next adjacent row, and means for directing heated. gases originating in said furnace compartment through said primary heating compartment in an undulated path to said smoke outlet whereby the heated gases pass over and through the staggered rows of tubes to effect a breaking up and diffusion of the same.

4. In a steam generator, a setting having fire door openings in the front thereof, awater heating circulating and steam generating system including an upper water and steam drum, side water wall headers, and water wall tubes connecting said upper drum and said side wall headers, a front water wall header extending transversely of the front wall of said setting on' the plane of the top of said fire door openings and providing water cooled fire door arches for said fire door openings, tubes connecting the front ends of said side water wall headers with opposite ends of said front wall header, and front water wall tubes rising upwardly from said front water wall header and connected to said upper water and steam drum.

5. In a steam generator, a setting, an upper water and steam drum, 9, lower water drum, tubes connecting said upper and lower drums, a refractory bridge wall extending transversely of said setting forward of said lower drum, a bridge wall header extending transversely of said setting, tubes connecting said header with said lower water drum, and bridge wall water cooling tubes rising upwardly from said header and being connected to said upper water and steam drum.

6. In a steam generator, a setting, a forwardly curved upwardly extending bridge wall disposed transversely of said setting and dividing the same into a forward combustion chamber and a rear heating chamber, an upper water and steam drum extending the length of said setting, a, lower water drum rearward of said bridge wall and connected to said upper drum by tubes, a. bridge wall header extending beneath said bridge wall transversely of said setting, tubes connecting said header with said lower drum, and bridge wall water cooling tubes extending through said forwardly curved bridge wall and disposed substantially parallel thereto, said tubes being extended free of said bridge wall and rising upwardly over said combustion chamber and connecting with the forward end of the upper drum.

7. In a. steam generator, a setting having a combustion chamber, an upper water and steam drum, a lower water drum, tubes connecting said upper and lower drums, side water wall headers water cooling tubes on the respective sides of said combustion chamber extending across said chamber and being connected with the headers on the opposite sides of said chamber to provide an integral furnace hearth within said chamber, the other water wall cooling tubes respectively connected to the headers on the sides along which the said water wall cooling. tubes depend.

8. A steam generator comprising an insulated setting having a smoke outlet at the rear top thereof, an upper water and steam drum extending the length of said setting, a bridge wall extending transversely of said setting and dividing the interior thereof into a forward combustion chamber and, a. rear primary heating compartment, a lower water drum within said heating compartment and disposed behind said bridge wall, rows of boiler tubes connecting said upper drum and said lower drum, the tubes of one row being staggered relative to the tubes of the next adjacent row, water wall headers extending along the inside of the side walls of said setting and disposed within said.- combustion chamber and primary heating compartment, side water wall tubes connecting said headers with said upper drum, laterally extending tubes connecting the rear portions of said headers with said lower drum, the rearwardly disposed side water wall tion, a setting, a. furnace within said setting, an

upper water and steam drum extending the length of said setting, a lower water drum rearward of said furnace, water circulating headers extending along the side walls of said setting substantially the length thereof, the front ends of which are disposed within said furnace while the rear ends of said headers extend rearward of said furnace, means for circulating feed water from the rear of said upper drum to said lower drum and back to the front of said upper drum through said water circulating headers, and means for returning a portion of the water supplied to said lower drum from the front portion thereof directly to said upper drum, whereby to provide a double ring-like flow of circulating water from said upper drum and return.

10. In a steam boiler, a setting having side walls, an upper water and steam drum, a lower water drum, headers extending forwardly and rearwardly along said side walls, tubes connecting said lower water drum and said headers, rows of tubes constituting primary heating elements extending downwardly from said upper drum, the outermost tubes extending downwardly adjacent said side walls, certain of said outermost tubes being connected to said headers and constituting water circulating tubes to assist in providing a constant supply of circulating water for water cooling said side walls and thereby inducing a water circulation in and from the upper drum. while the other outermost tubes and remaining primary heating tubes are connected to said lower drum and constitute water heating and/or steam generating tubes.

11. In a steam boiler, a setting having side walls, an upper water and steam drum, a lower water drum, headers extending'forwardly and rearwardly along said side walls, tubes connecting said lower water drum and said headers, rows of tubes constituting primary heating elements extending downwardly from said upper drum, the outermost tubes extending downwardly adjacent said side walls, certain of said outermost tubes being connected to said headers and constituting water circulating tubes to assist in providing a constant supply of circulating water for water cooling said side walls and thereby inducing a water circulation in and from the upper drum, while the other outermost tubes and remaining primary heating tubes are connected to said lower drum and constitute water heating and/or steam generating tubes, a combustion chamber,

within said setting forward of said rows of tubes, said headers extending into said combustion chamber, and upcomer steam generating tubes connected to said headers and rising upwardly within said combustion chamber along the side walls thereof and connecting with said upper water and steam drum.

1 2. In a steam boiler, a setting having side walls, an upper water and steam drum, a lower water drum, headers extending along said side walls, tubes connecting said lower water drum and said headers, rows of tubes constituting primary heating elements extending downwardly from said upper drum, certain of the outermost tubes of said rows of tubes being connected to said headers and constituting water circulating tubes to assist in providing a constantsupply of circulating water in and from the upper drum, to and through the headers while the other tubes are connected with the lower drum and constitute water heating and/or steam generating tubes.

13. In a steam generator, a setting having a smoke outlet at the rear thereof, an upper water and steam drum extending the length of said setting, a bridge wall extending transversely of said setting and dividing the interior thereof into a forward combustion chamber and a rear primary heating compartment, a lower water drum within said heating compartment and disposed behind said bridge wall, rows of boiler tubes connecting said upper drum and said lower drum, water wall headers extending along the inside of the side walls of said setting and disposed within said combustion chamber and primary heating compartment, side water wall tubes connecting said headers with said upper drum, and tubes connecting the headers with the lower drum, the rearwardly disposed side water wall tubes connecting said headers and upper drum and the rear rows of boiler tubes constituting downcomers, while the forward water wall tubes and forward rows of boiler tubes constitute upcomers.

14. In a steam generator, a setting, a furnace chamber within said setting having a grate, a water heating and circulating and steam generating system contained entirely within said setting including an upper water and steam drum, opposed water circulating headers extending along the respective side walls of said setting and extending forwardly into said furnace chamher at the grate line .thereof and rearwardly of the plane of the front of said lower drum, tubes connecting the lower water drum with the rear portions of saidheaders, furnace. cooling tubes having their lower ends joined to said headers by expanded joints and extending upwardly from said headers with their other ends connected to said upper drum forwardly thereof whereby said headers primarily serve to supply water to the furnace cooling tubes and to secondarily provide a clinker chill at said'grate, and a relatively low armor wall disposed inwardly of the side wall of the furnace chamber wall and resting upon that portion of said headers disposed within said furnace chamber and enclosing the lower ends of the furnace cooling tubes to provide a non-clinkering surface.

'15. In a steam generator, a setting, a refractory bridge wall extending transversely of said setting to divide the same into a forward combustion chamber and a rear primary heating compartment, an upper water and steam drum extending the length of said setting, a lower water drum disposed within said primary heating compartment, tubes connecting said upper and lower drums, a header extending transversely of said setting adjacent said lower drum, tubes connecting' said header with said lower drum, and bridge wall cooling tubes closely associated with said bridge wall and rising upwardly from said header and being connected to said upper water and steam drum, those portions of the bridge wall cooling tubes disposed'above the plane of the top of said bridge wall being exposed to the heated gases of combustion as they pass over said bridge wall into said primary heating compartment.

16. In a steam generator, a setting, an upper water and steam drum, alower water drum, an upstanding refractory bridge wall extending transversely of said setting forward of said lower water drum, and tubes for circulating water from said upper water and steam drum to said lower drum and return, certain of said tubes contacting said refractory bridge wall for a substantial portion of their lengths for water cooling said refractorybridge wall by subjecting the same to the cooling effect of water from said lower water drum during its return to said upper water and steam drum.

17. In a. steam generator, a setting, a furnace within said setting forward thereof, a refractory bridge wall at the rear of said furnace and rising from the bottom of said setting, a water heating circulation and steam generating system including an upper water and steam drum, 9. lower water drum rearwardly of said bridge wall, circulating tubes connecting said upper and lower drums, water circulating headers along opposite sides of said setting extending rearwardly beyond the plane of the front end of said lower water drum, tubes directly connectingopposite sides of said lower drum with said water wall headers rearward of the plane of said bridge wall, superheater tubes extending through said setting and disposed at the rear side of said bridge wall whereby the superheater tubes will be directly swept by the gases of combustion passing rearward from said furnace over the top of said bridge wall and subjected to the heat radiated from said bridge wall, and means connecting the inlet ends of said superheater tubes with the top of said upper drum.

18. In a steam generator, 8. setting having a forward combustion chamber and a rear heating compartment, a smoke outlet at the rear of said heating compartment, a longitudinal upper water and steam drum, a longitudinal. lower water drum within said heating compartment, spaced rows of boiler tubes connecting said upper drum and said lower drum, water wall headers extending along the side walls of said setting and disposed forward and rearward of the plane of the front end of said lower water drum, tubes connecting the rear portions of said headers with opposite sides of said lower drum, means for circulating water from the forward portions of said water wall headers through said combustion chamber to said upper water and steam drum, and spaced overlapping baiiies arranged between certain of said rows of boiler tubes for causing the heated gases from said combustion chamber to travel in an undulated path to saidsmoke outlet.

19. In a steam generator, a setting having a front furnace compartment and a rear heating compartment, an upper longitudinal water and steam drum, a lower longitudinal water drum within said heating compartment, tubes con necting said upper and lower drums, headers disposed along-the side walls of said furnace compartment and extending rearwardly beyond the plane of the front end of said lower drum,

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