US2109278A - Steam boiler - Google Patents

Description

Feb, 22, 1938.. K. c. SCHMIDT 2,109,278

STEAM BOILER Filed Sept. 25, 1936 5 Sheets-Sheet 1 Fig] 4% LIQL UL 1 65 INVENTOR.

ATTORNEY.

K. C. SCHMIDT Feb.22, 1938.

STEAM BOILER 5$het kg e Filed Sept. 25, 1956 INVENTOR CO m. J@

K. C. SCHMIDT Feb. 22, 1938.

STEAM BOILER Filed Sept. 25, 1936 5 Sheets-Sheet 3 Q4 &

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Feb. 22, 1938. K. c, SCHMIDT 2,109,278

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Kar] G. Schmidi Feb. 22, 1938. I K. c. SCHMIDT STEAM BOILER Filed Sept. 25 1956 5 Sheets-Sheet 5 INVENTOR. Karl C 501721112125 KR WY.

Patented Feb. 22, .1938 i UNITED STATES PATENT OFFICE STEAM BOILER Karl C. Schmidt, Western Springs, Ill., assignor to The Babcock & Wilcox Company, Newark, N. J., a corporation of New Jersey Application September 25, 1936, Serial No. 102,492

11 Claims. (01. 122336) I My present invention relates to the construc- 18. The side wall 12 preferably includes hollow tion and operation of steam boilers of the water tile l2 arranged to form air passages open attube type and more particularly to steam boilers their lower ends. Extending upwardly along the adapted for installations having limited head opposite side walls are structural steel columns I9 room and floor space available. In my prior which support girders 20 extending across and application, Serial No. 16,115, filed April13, 1935, I above the top of the setting.

a steam boiler adapted for such use is disclosed The interior of the setting is' divided as herehaving a relatively large amount of convection inafter described into a relatively wide combusand radiant heat absorbing surface, furnace voltion lane or furnace chamber 2|. and a relatively ume, and length of heating gas travel in propornarrow laterally adjoining heating lane or tube tion to the spaceoccupied and head room rechamber 22. A pair of longitudinally disposed quired. parallel upper and lower drums 23 and 24 re- The main object of my present invention is spectively extend longitudinally and throughout the provision of an improved furnace constructhe lengthof the heating lane and are connected tion for a steam boiler of the general type dethroughout their length by a bank of vertically l6 scribed in my prior application for adapting the disposed tubes 25 straight for most of their length same for stoker firing at relatively high efiland having bent ends for radial connection into ciencies. A further object is the provision of the drums at both sides of the central vertical means for effecting an improved flow of heating planes thereof. The upper or steam and water gases over the convection heating surface. drum 23 is inwardly oflset slightly from the lower The various features of novelty which charor water drum 24. The upper drum 23 is supacterize my invention are pointed out with parported from the structural steel members 20, inticularity in the claims annexed to and forming dicated in Fig. 1 as carried by the members is, a part of this specification. For a better underand in turn supports the lower drum 24 through standing of the invention, its operating advanthe tube bank 25. tages and specific objects attained by its use, The heating lane 22 is separated from the adreference should be had to the-accompanying joining combustion lane 2| except at the rear end drawingsand descriptive matter in which I have thereof by a vertically disposed refractory partiillustrated and described preferred embodiments tion 26 which extends between the drums and terof my invention. minates at its rear end a substantial distance 30 Of the drawings: from the rear wall II. The lower drum is ade- Fig. 1 is a transverse vertical section of a steam quately protected along its inner side by a reboiler constructed in accordance with my invenfractory curb 21 on the floor l5 and by the tion taken on the line i-l of Fig. 2; thickened lower section of the partition 26. The Fig. 2 is a longitudinal vertical section taken on spaces between the outer side of the drums 23 and the line 2-2 of Fig. 1; 24 and the side wall i3 are closed by refractory Fig. 3 is'a horizontal section taken on the line material so that heating gases entering the rear 33 of Fig. 2; end of the heating lane will be confined in the Fig. 4 is a view similar to Fig. 2 of a modified space therein between the drums. A heating construction; I as outlet or stack connection 28 controlled by 40 i Fig. 5 is a view similar to Fig, 3 of the modi-. a damper 28 is provided at the front end of the flcation shown in Fig. 4; heating lane. With this arrangement heating- Fig. 6 is a view similar to Fig. 1 of the modigases generated in the combustion lane will flow flcation shown in Figs. 4 and 5; and longitudinally thereof, entering. the rear end of Fig. '7 is a view similar to Fig. 6 of a second the heating lane and passing forwardly therein modification. to the stack connection 28..

The steam boiler unit illustrated in Figs. 1 to The steam boiler illustrated is especially de- 3 comprises a setting or housing substantially signed for the burning of solid fuel in a bed in rectangular in horizontal. and vertical crossthe forward end of the combustion lane. Asingle sections, and formed by a vertical front wall It, retort underfeed stoker 30 is conventionally iiIusrear wall ll, side walls l2 and I3, inclined top trated in the forward half of the combustion wall or roof I, and'bottom wall or floor 15. lane. The stoker is mounted on laterally, spaced The vertical walls of the setting are formed in walls 3| defining the sides of an air-chamber 32 general by an outer steel casing It, a layer of which is supplied by an external forced draft fan insulating material I1, and a refractory lining 33. Solid fuel from a magazine 34 is fed by a suitable feeding mechanism 35 into the stoker retort 36 from which it is forced outwardly over the stoker grates 31. Dumping grates 38 along the sides of the stoker permit the fuel residue to be dropped into ash pits 39 along the sides of the air chamber 32 and from which. it is removed through suitable cleanout doors in the lower part of the front wall Ill.

The gas flow' area of the combustion lane is substantially restricted at the rear end of the stoker by a transverse refractory dividing structure 40 formed by a bridge wall 4|, wing walls 42, and an arch 43, which unite to define a restricted throat or gas outlet 44 between the front and rear sections of the combustion lane. With this structure the combustible gas from the fuel bed and air as iyet uncombined will be intimately mixed by the high degree of turbulence on passing through the throat into the rear section of the combustion lane and complete combustion in the combustion lane will be insured.

This throat divides the combustion lane into two parts, a forward part having the bed of solid fuel with which the air reacts to form complete and incomplete gaseous products of combustion with excess air, and a rearward .part in which the combustible gas combines with some of the excess air. The first stage of combustion in which the solid fuel reacts with air to form gaseous products requires a temperature as high as possible consistent with ash clinkering limits, and

'the correct temperature is assured by a suitable ratio of hot to cold portions of its boundary walls. The second stage of combustion in which the last traces of combustible gas are burned in as little excess air as possible may be advantageously carried out within walls that have a larger ratio of cold to hot boundary wall surface and the throat divides this section from the forward one.

A relatively large proportion of the heating surface of the unit is formed by tubes receiving radiant heat from the combustion lane. In the stoker section in front of the throat a row of tubes 50 extends upwardly from the drum 24 at the combustion lane side of the partition 26. Spaced tubes 50 are connected directly to the upper drum 23, while the intermediate tubes 50 are L- shaped and have outwardly inclined legs 0 extending across the upper part of the combustion lane to a header 5| at the junction of the side wall I2 and top wall l4. The header 5| extends the full length of the unit andis advantageously supported by longitudinally spaced hangers 52 from the structural steel members 20. The header 5| is connected to the upper drum 23 by a row of roof tubes 53, which as shown, correspond in number to the tubes 50 and 50 The outer side wall l2 of the stoker section is made of refractory with its outer face air cooled by the hollow tile ducts I2. By proper selection of the spacing of the water tubes 50 on one side wall, the tubes 50 over the furnace and 53 along the roof, and of the area of the outer side and front walls, the temperature of the stoker section in front of the throat may be made as high as desirable.

At the rear side of the throat the header 5| is connected to the lower drum by L-shaped tubes 54 having outwardly inclined legs extending across the lower part of the combustion lane above the floor thereof and vertical legs extending along the outer side wall l2. Roof tubes 53 connect the rear portion of the header to the upper drum. A cleanout door 55 is provided in the rear wall II for removing ash deposited on the floor of the combustion lane rear section. The ash deposited on this floor is protected against fusion by the horizontal legs of the tubes ward of the throat, and the ratio of cold to hot area is larger than in the section forward of the throat, and the value of the ratio may be selected by the spacing of the enclosing tubes.

The inner side of the rear section of the combustion lane is defined by a rear section 26 of the partition 26 which extends rearwardly from the inner wing wall 42 at a point offset towards the side wall l2. Additional rows of water tubes 25 are provided in the rear section at opposite sides of the partition section 25. These rows of tubes extend beyond the rear end of the partition section and form a screen across the entrance to the heating lane. The heating lane side of the innenwing wall- 42 and partition is cut away at an angle as indicated at 56 to facilitate gas flow from the wide to the narrow part of the forwardly tapering heating lane; This construction substantially' contributes to the maintenance of a .higher heat transfer rate as the gases become cooler by increasing the mass velocity toward the outlet of the heating lane.

With the described construction and arrangement, fuel is automatically delivered to and burned on the stoker at a rate suitable for the .load and air supplied by the forced draft fan.

The gases generated flow rearwardly through the throat 44 into the rear section where combustion is completed. The products of complete combustion or heating gases pass around the rear end of the partition section 26 and forwardly through the heating lane at a substantially increasing mass velocity to the stack connection 28. To avoid by-passing of the lower portions of the water tubes at the front end of the heating lane, baffle means are installed in that portion of the heating lane to cause'the heating gases to pass downwardly before leaving the heating lane. As shown in Figs. 1 and 3, a two-section bafile is used having a stationary upper section 60 and a vertically adjustable lower section 6|. The lower section is carried by a guided rack 62 which can be raised or lowered by a pinion 43 on a manually operable shaft 64.

Feed water is supplied to the front end of the upper drum or at any other suitable point and flows downwardly through the forward portion of the tube bank to the lower drum. Most of the steam is generated inthe tubes receiving radiant heat from the combustion lane and inthe tubes in the rear portion of the heating lane. A steam outlet 65 is indicated at the forward end of the upper drum.

In the modification shown in Figs. 4 to 6, the furnace chamber 2| and heating lane 22 are transposed so that the tube bank 25 is at theleft side of the unit. The construction is otherwise the same as the form shown in Figs. 1 to 3, except for \an alternate form of fuel burning stoker. In the modified unit, a horizontally arranged perforated plate grate 10 receives solid external fo'rced draft fan (not shown) through a 75 The transverse duct 14 in the bottom part of the bridge wall 4| and separate inlet openings I5 controlled by dampers 16. The air becomes preheated during its passage through the bridge wall duct, air chamber tubes and tuyeres, and passes upwardly into the fuel bed on the grate in a multiplicity of small jets. The operation otherwise is the same as in the construction shown in Figs. 1 to 3.

In Fig. 7 I have illustrated a four-drum boiler unit of the type disclosed and claimed in my said prior application. The steam generating water tube surface is mainly concentrated in two spaced 'vertical banks 25 and 25' respectively connected to upper and lower drums 23, 24 and 23', 24. The furnace chamber in this form has its opposite sides and roof partly defined by oppositely arranged rows of L-shaped tubes 50 having their upper ends connected to the adjacent upper drum 23 or 23'. The fuel burning provisions shown in Figs. 4 to 6 are incorporated in the modification shown in Fig. 7 as well as the bridge wall and partition elements thereof. In Fig. 7 the heating gases generated divide at the rear end of the boiler between the two heating lanes at opposite sides thereof.

The steam boiler constructions illustrated are especially adapted for the low capacity field heretofore substantially monopolized by horizontal return tubular boilers. Although incorporating many features of modern central station design contributing to a high boiler efliciency, they can be used to advantage without a corresponding use of other features.

I claim:

1. A steam boiler having upper and lower drums, a bank of vertically disposed water tubes extending between and connected to said drums, means forming a longitudinally extending combustion lane anda heating lane laterally azfloining said combustion lane and containing said tube bank and communicating with said combustion lane at one end thereof, a stoker at the opposite end of said combustion lane for burning solid fuel thereon and generating heating gases flowing longitudinally through c said combustion lane and thence through said heating lane, and a dividing wall structure including transversely spaced refractory winged walls arranged to provide a restricted outlet for the heating gases to the remaining portion of said combustion lane.

2. A steam boiler having upper and lower drums, a bank of vertically disposed water tubes extending between and connected to said drums, means forming a longitudinally extending combustion lane and a heating lane laterally adjoining said combustion lane and containing said tube bank and communicating with said combustion lane at the rear end thereof, a stoker at the front end of said combustion lane for burning solid fuel thereon and generating heating gases flowing rearwardly through said combustion'lane and thence through said heating lane,

and a dividing wall structure at the rear of said stoker including transversely spaced refractory wing walls and a connecting arch constructed to provide a restricted outlet for the heating gases to the rear portion of said combustion lane.

3. A steam boiler having upper and lower drums, a bank of vertically disposed water tubes extending between and connected to said drums, means forming a longitudinalh extending'combustion lane and a heating lane laterally adjoining said combustion lane and containing said tube bank and communicating with said combustion lane at the'rearend thereof, a stoker at the front end of said combustion lane for burning solid fuel' thereon and generating heating gases flowing rearwardly through said combustion lane and thence. through said heating lane, and a dividing wall structure at the rear of said stoker including a bridge wall, spacedwing walls and an arch arranged to provide a central restricted outlet for the heating gases to the rear portion of said combustion lane.

4. A steam boiler having upper and lower drums, a bank of vertically disposed water tubes extending between and connected to said drums, means forming a longitudinally extending combustion lane and a heating lane laterally adjoining said combustion lane and containing said tube bank and communicating with said combustion lane at the rear end thereof, a stoker at the front end of said combustion lane for e lane and having their upper ends connected to said upper drum.

5. A steam boiler having upper and lower drums, a bank of vertically disposed water tubes extending between and connected to said drums, means forming a lon tudinally extending combustion lane and a. hea ing lane laterally adjoining said combustion lane and containing said tube bank and communicating with said combustion lane at the rear endthereof, a'stoker at the front end of said combustion lane for burning solid fuel thereon and generating heating gases flowing rearwardly through said combustion lane and thence through said heating lane, a dividing wall structure at the rear end of said stoker constructed to provide-a restricted outlet for the heating gases to the rear portion of said combustion lane, a row of L-shaped water tubes extending upwardly along the inner sideof and across the upper portion of the front end of said combustion lane, a longitudinal header connected to said L-shaped tubes, and a row of roof tubes connecting said header to said upper drum.

6. A steam boiler "having upper and lower drums, a bank of vertically disposed water tubes extending between and connected to said drums, means forming a longitudinally extending combustion lane and a heating lane laterally adjoining said combustion lane and containing said tube bank and communicating with said combustion lane at the rear end thereof, said means including a vertically disposed longitudinally extending partitition separating said combustion and heating lanes and arranged to form a forwardly tapering heating lane, means for burning fuel in said combustion lane and generating heating gases flowing serially through said combusu tion and heating lanes, and a heating gas outlet at the front end of said heating lane.

7. A steam boiler having upper and lower drums, a bank of vertically disposed water tubes extending between and connected to said drums, means forming a longitudinally extending combustion lane and a heating lane laterally adjoining said combustion lane and containing said tube bank and communciating with said combustion lane at the rear end thereof, said means including a vertically disposed longitudinally extending partition separating said combustion and heating lanes and having a rear section laterally ofiset relative to the forward section to form a forwardly tapering heating lane, means at the front end of said combustion lane for burning fuel and generating heating gases flowing rearwardly through said combustion lane and thence through said heating lane, and a heating gas outlet at the front end of said heating lane.

8. A steam boiler having upper and lower drums, a bank of vertically disposed water tubes extending between and connected to said drums, means forming a longitudinally extending combustion lane and a heating lane laterally adjoining said combustion lane and containing said tube bank and communicating with said combustion lane at the rear end thereof, means for burning fuel in said combustion lane and generating heating gases flowing serially through said combustion and heating lanes, a heating gas outlet at the front end of said heating lane, and vertically adjustable baiiie means arranged to effect a downward flow of the heating. gases adjacent said outlet.

9. A steam boiler' having upper and lower drums, a bank of vertically disposed water tubes extending between and connected to said drums, means forming a longitudinally extending combustion lane and a heating lane laterally adjoining said combustion lane and containing said tube bank and communicating with said combustion lane at the rear end thereof, said means including a vertically disposed longitudinally extending partition separating said combustion and heating lanes and arranged to form a forwardly tapering heating lane, means at the front end of said combustion lane for burning fuel and generating heating gases flowing rearwardly through said combustion lane and thence through said heating lane, a heating gas outlet at the front end of said heating lane, and vertically adJustable baffle means arranged to effect a downward flow of the heating gases adjacent said outlet.

10. A steam boiler having upper and lower drums, a bank of vertically disposed water tubes extending between and connected to said drums, means forming a longitudinally extending combustion lane and a heating lane laterally adjoining said combustion lane and containing said tube bank and communicating with said combustion lane, a stoker at one end of said combustion lane for burning solid fuel thereon and generating heating gases flowing longitudinally through said combustion lane and thence through said heating lane, a bridge wall structure at one end of said stoker constructed to provide a restricted outlet for the heating gases to the remaining portion of said combustion lane, separate air chambers below said stoker, a transverse passage through said. bridge wall, and damper-controlled openings separately connecting said-bridge wall passage to said air chamber.

11. A steam boiler having laterally spaced I pairs of upper and lower drums, a bank of vertically disposed water tubes extending between and connected to each pair of said drums, means forming a longitudinally extending central com-I bustion lane and a pair of heating lanes laterallyadjoining and at opposite sides of said combustion lane, each heating lane containing one of said tube banks and communicating with said combustion lane at the rear end thereof, a stoker at the front end of said combustion lane for burning solid fuel thereon and generating heat-.

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