US1739035A - Furnace for pulverulent fuel - Google Patents

Description

Dec. 10, 1929. w. KLElNow ET AL FURNACE FOR PULVERULENT FUEL Filed March 24, 1927 2 Sheets-Sheet Dec. l0, 1929. W. KLElNoW ET AL 1,739,035

FURNACE FOR PULVERULENT FUEL Filed March 24, 1927 2 Sheets-Sheet 2 Patented Dec. 10, 1929 UNITED STATES PATENT OFFlCE WALTER KLEINOW', 0F HENNIGEDORF, NEAR BERLIN; ALBERT MORGENRGTH, OF NIEDERNEUENDORF; FRIEDRICH REINHARDT, OF HENNIGSDORF, NEAR BERLIN; AND WILHELM BRUER, OF VELTEN. G'ERMANY, ASSIGNORS T0 THE FIRM ALLGE- MEINE ELEKTRICITATS-GESELLSCHAFT, 0F BERLIN, GERMANY FURNACE FOR PULVERULENT FUEL Application filed March 24. 1927, Serial No. 178,073, and in. Germany May 1, 1925.

The present invention relates to furnaces for pulverulent fuel and has for its object to provide 'an improved construction and arrangement in a furnace of this type. The invention is especially well-adapted for use in connection with furnaces for locomotives and in the following specification and in the drawing, it is specifically described and illustrat-ed as applied to this use. lt is to be under-smoel, however, that. the invention is not limited thereto necessarily.

For a consideration of what we believe to be novel and our invention, attention is directed to the following specilication and the claims appended thereto.

ln the drawing, Fig. l is a. sectional view, partly broken away, illustrating the general arrangement of the furnace and showing the tire-hox of a locomotive. its combustion chamber and the frontend of its tender; Fig. L is a lmagitudinal `sectional view through the combustion chamber and one of the burners, the section being taken on line 2 2, Fig. o; Fie'. Il is n face riew, partly broken away, of the burner structure illustrated in Fig. 2; Fig. :l is a transverse, sectional view of the burner shown in 7Figs. 2 and 25; Fig'. 5 is a perspective view of a portion of the burner; Fig. (i is a transverse, `sectional view through the combustion chaniber showing the arrangement of the burner therein. and Fig. i is a transverse. sectional view of the front end of the furnace, the section being, taken on line 7*?. Fig. l.

ReferringT to the drawino, 1 indicates the outer shell of the boiler, a portion of the boiler only beingr illustrated; 2 indicates the lire-box and 3 indicates the back tube plate. The usual tubes in the back tube plate are indicated at 4. The tube plate 3 is provided with a downward extension which forms the front water legir 7. 8 indicates the crown slieet'of the boiler. and 9 indicates the tiredoor ring at the back of the lire-box. Below tho lire box 2 is a combustion chamber 10, the ,walls l1 of which are supported by the ash tray 12 and extend vertically upward partly into the fire-box 2, as is indicated. at 13.

The locomotive illustrated in Fig. 1 is provided with a separate tender but obviously the invention is not limited to locomotives of this type.

14 indicates the fuel tank of the. tender and 15 `indicates the Water tank. Arranged in the fuel tank is a screw conveyer 16, which serves to supply fuel to a nozzle fed with compressed air by a fan 17 which may be operated by any suitable prime mover such as, for example, a steam turbine. 18 indicates a reciprocating engine which operates the screw eonveyer 16. 19 is a pipe line through which mixture of fuel and prin'iary air is supplied tothe primary burners of the furnaces and 20 is an auxiliary pipe line through which mixture-of fuel and primary air is supplied to an auxiliary burner.

Extending along cach side of the combustion chamber 10 is a primary burner 2l shown in detail in Figs. 2 to 5 inclusive. The two burners 21 are arranged opposite each other, as shown in Fig. G and their inner faces, that is, their opposed faces, are provided with a great number of comparatively narrow slots 22 which are preferably rectangular and vertical, but may be of any other 'configuran tion. if found desirable.

Slots 22 are arranged so as to discharge jets issuing,r along parallel lines so that the flames from the two burners will mpinge at the center of the combustion chamber. By this arrangement, the formation of [iame tongues is prevented and intense whirling is elfected by which the combustion of the fuel is accelerated. t is desirable that the velocity at which the mixture of fuel and air is flowing in the burners `shouldbe substantially uniform throughout the length of the burners, for if the velocity tends to decrease toward the end of the burner, there may resulta dropping of the fuel from the air and clogging of the slots at the end of the burner. Besides, with jets issuing at reduced velocity backward ignition and rapid destruction of the burner may occur. To effect this uniform velocity thebcross sectional area of the burner conduits indicated at 28 is reduced `gradually from their rear ends toward their front ends as is clearly shown in Fig. 2. This forms a gradually tapering conduit into which the fuel and air mixture is fed and by reason of the taper effects the desired uniform velocity. The edges of the -webs intermediate the slots 22 which face the flow are Asharpened as is indicated at 23a and project inwardly and forwardly somewhat, so that the webs constitute sort of forwardly-facing guide varies which catch the mixture and ejectit with considerahle whirling. This serves to assist in giving a uniform mixture before the mixture is ignited' in the combustion chamber.

In order to prevent backward ignition at slow or moderate velocities of the mixture of the fuel and air from the burners, a cooling means is provided in connection with each burner. Such cooler means comprises preferably a cooling medium such as water, which is circulated in the vicinity of the inner face of the burner. In thepresent instance, the cooler is shown as comprising two parallel headers 24 and 25 which extend along the upper and loweredges of the front face of the burner adjacent to the slots 22. Headers 24 and 25 may befastened to the walls of conduit 23 in any suitable manner, such as by means of the bolts 26 as shown in Fig. 4. Preferably, the slots 22 are formed in a separate plate 27 which maybe made with advantage from a metal having superior heat-contacting properties, such as copper, for example, the plate 27 being` held in place hy headers 24 and 25, as is indicated particularly in Fig. 5.

Projecting 'from headers 24 and 25 and located between the slots 22 are ribs 28, the ends of the ribs nearly engaging each other. By

this arrangement,.it will be seen that the ribs 28 define vertical slots or passages 29 which register with the slots 22 and through .which the mixture of fuel and air is discharged from the burner. The ribs 28 do not extend quite as far as the center line in order to allow for heat-expansion. Preferably, ribs 28 are formed integral with headers 24 and 25. The cooling headers are preferably made substantially triangular in cross-section and are arranged with the apex of the triangle directed toward the combustion chamber. Also, the headers are embedded in the brickwork ll as far as their edges. By this arrangement only the small edge of the cooler is exposed to the combustion chamber so that the projection of the area exposed to radiation is as small as possible. This is best illustrated in Fig. 6. By this arrangement, the quantity of heat absorbed by the coolers from the furnace is reduced to .a comparatively small amount whileat the same time the required cooling of the burners is effected.

The cooling medium for the headers (usually water) may be taken from any suitable source of supply. Preferably, however, there is utilized in the headers, some of the Water of the boiler. In the present instance, the one end of the headers is shown as being connected through pipes 30 to-wash-out plugs 31 in the back water leg of the fire-box. The water, after flowing through the two headers in parallel, is discharged through pipes which are connected inthe holes 33 in the back plate of the tire-box, the holes 33 being at a higher level than are the plugs 31. lWith this arrangement it will be seen that pipes 30 ar'e connected to the boiler at a point where the water is comparatively cool while pipes 32 are connected to the boiler at a higher level and a. point where the water is at a higher temperature. Also, it will be noted that the pipes 32 are exposed directly to the heat of the furnace. By this arrangement a rapid circulation of water through the coolers is effected by convection and effective cooling of the burners is obtained. The heat extracted by the cooling is put directly into the boiler water.

Located in the lire-box is an arch 34: which in the present instance, is shown as being partially supported on the pipes 32, the pipes heilig partially embedded in the arch wall. l'Vith this arrangement the pipes' serve no t only as a partial support for the arch but also, the water flowing through the pipes serves as a cooling medium for the arch, the water being at the same time heated.

lhe arch is designed with particular consideration of the tendency to form slag nests at the rear face of the tube plat-c 3. 'lo this end the arch is made longer than the normal arch and its inclination is less steep. 'lhe arrangement is such that the area (indicated by the arrows :r-) between the haelt plate and the rear edge of the arch is smaller than the area between its rear edge and the crown sheet 8 (indicated by the arrows 3f-y). Heretofore, the velocit-y of the gases attained their maximum after they passed through this area and assumed the horizontal direction of flow indicated by the arrow e, but, with the relative areas as designated in the present instance, the velocity of the gases will be a maximum when flowing through the area :z2-w (indicated by the arrow z') and will decrease when the gases are deflected horizontally. With this arrangement, comparatively heavy particles of slag do uotfollow the change of direction of the gases but move on in the direction of the arrow a and are. hurled against the crown sheet S where they are granulated so that the gases arriving at tube plate 3-are free from slag in plastic condition and therefore nests will not form on the tube wall. Preferably, however, especially in cases where the `percentage of slag-.in the coal is comparatively high and as an adg ditional precaution for absolutely preventing the formation of nests of slag on the tube plat-e 3, we provide a granulating grid comprising substantially vertical pipes 36' which are located just in front of and spaced 'from the rear face of tube plate 3 and are connected lili) at their lower ends with a header 37 to which water from the boiler is` supplied through a pipe or pipes 38. The upper ends of the tubes 6 are inserted in holes in the crown sheet 8. Water from the boiler flows to the header 37 and returns through the vertical grid tubes 36 to the water space at the top of the crown sheet 8. In order to increase the cooling action of the vertical grid tubes 36, they may be provided with fins 39 which in the pres! ent. instance, are shown as being arranged at right angles to the direction of the flowing gases, although they may be arranged in any other suitable way. 40 1s a scraper provided with an operating rod 41 and adapted to be moved along the tubes 36 to clean the tubes and also the tube plate 3. It may be arranged to be operated in any suitable manner. Any molten slag reaching the grid and striking against it is cooled and granulated.

Secondary air and a suitable arrangement for supplying it to the furnace is a very important factor in the combustion of the fuel. In the present instance, the secondary air is supplied through a conduit 42 defined by a wall 43 which forms an extension of tube plate 3 and the front wall 11 of the combustion chamber. The air is thus supplied to the furnace beneath the arch 34 and in flowing under the arch serves as a cooling medium for it. 44 is a damper hinged to the ash tray wall 12 and extending over the entire width of the furnace. The damper opens against the direction in which the locomotive is ordinarily running, a suitable means (not shown) being provided for adjusting the damper to give 1t the desired degree of opening. The combined action of the air resistance and the reduction of pressure in the firebox draws in secondary alr through the vertical passage 42 which air enters below the arch 34 through the assage 45 between the arch and the to of the front wall extension 13 of the com ustion chamber and moves along the lower face of the arch 34. In this manner, the arch is cooled and in addition, the secondary air is heated by convection from the hot arch and its volume is increased considerably. The expansion of the air in an upward direction is limited b the arch and therefore it will tend to flow ownwards and rearwards, whirling and mixing with the ames issuing from the slots 22 of the burners 21 and getting into thorough contact with thegases and the glowing particles of fuel and completing their com ustion.

Fire-clay arches' warrant a more complete combustion of the fuel or the gases, but they are liable to failure on account of the high temperatures to which they are subjected. This is especially serious in pulverulent fuel furnaces. By our arrangement wherein the secondary air flows beneath the arch, we provide a very simple and effective cooling means for the arch whereby its life is extended and at the same time the secondary air is heated by convection from the arch so that the temperature in the furnace is increased and comustion is effected under the most favorable conditions. Q

Preferably, secondary air is supplied also to the back of the combustion chamber below the back water leg. To this end, passages 46 are formed in the back wall of the combustion chamber just below a deflector 47. 48 is a header extending over the entire width of the combustion chamber along its rear wall and communicating with passages 46. At the ends of header 48 are walls 49 which provide forwardly-facing passages connected with header 48. In such passages are suitable ad'ustable dempers indicated at 49. Air is orced into the passages formed by walls 49 and the header 48 by the same causes by which air enters the passage 42 and flows into the furnace through passages 46. The dellector 47 serves to prevent tongues of flame from striking the back plate and the fire-door ring 9.

Pipe 20 conveys fuel and air mixture to an auxiliary burner 50 over the outlet end of which is arranged an ignition and deilecting arch 51. The auxiliary burner serves for maintaining a certain steam pressure in the boiler when the main burners 21 are not operated and also for igniting the mixture issuing from the slots 22 of the burners 21. The auxilia burner serves also to prevent too rapid coo in and consequent heat stresses at the tube bea s which might causeleakage when the burners 21 are shut off. In addition, with the auxiliary burner the steam may be kept up when the locomotive is not operated through comparatively long periods and when the burners are turned on the fuel is ignited without the necessity of providing a wood-lire or slow match.

-What we claim as new and desire to secure by Letters Patent of the United States is 1. A furnace for pulverulent fuel comprising a combustion chamber in the lower portion of said furnace, a burner in said combustion chamber rovided with a plurality of slots for the ischarge of a mixture of fuel and primary air, and cooling means arranged adjacent to the face of said slots for cooling the burner.

2. A furnace for ulverulent fuel comprising a combustion c amber in the lower portion of said furnace, a burner in said combustion chamber rovided with a plurality of slots for the disc arge of a mixture of fuel and primary air, coolin means arranged adjacent to the face of said slots for cooling the burner and ribs extending from said cooler intermediate said slots.

3. A furnace for pulverulent fuel comprising a combustion chamber in the lower portion of said furnace, a burner in said combustion chamber, provided with a plurality of slots for the discharge of a mixture of fuel and primary air, headers extending along said burner above and below said slots, means for supplying said headers with cooling medium, and ribs extending from said headers intermediate said slots. A

4. A furnace for pulverulent fuel comprising a combustion chamber in the lower ortion of said furnace, a burner in said com ustion chamber provided with a plurality of slots for the discharge of a mixture of fuel and primary air, headers extending valong said burner above and below said slots, means for supplying said headers with cooling medium, and ribs extending from said headers intermediate said slots, the cross-sectional area of said headers being reduced on one side, and their reduced sides being arranged so as to face the interior of said combustion chamber.

5. A furnace for pulverulent fuel comprising a combustion chamber in the lower portion of said furnace and a burner in said combustion chamber provided with a plurality of slots for the discharge of a mixture of fuel and primary air, and means providing ribs which form extensions of the webs between said slots and define continuations of said slots through which the fuel and air mixture is discharged.

6. A furnace for pulverulent fuel comprising a combustion chamber in the lower portion of said furnace, and a burner in said combustion chamber comprising a wall provided with a plurality of slots for the discharge of a mixture of fuel and primary air, the webs between said slots being provided with forwardly-projecting sharpened edges on the inside of said burner wall which are directed against the flow of the mixture in said burner, and means providing ribs which form extensions of the webs between said slots and define continuations of said slots through which the fuel and air mixture is discharged.

7. A furnace for pulverulent fuel comprising a combustion chamber in the lower portion of said furnace, a burner arranged in said combustion chamber, said burner comprising a plate provided with a plurality of slots arranged to face said combustion chamber, the webs between said slots forming guide vanes, and a cooler attached to Said plate.

8. A boiler having a furnace for pulverulent fuel comprising a combustion chamber in the lower ortion of said furnace, a burner in said com ustion chamber comprising a wall provided with a plurality of slots for the discharge of a mixture of fuel and primary air, a cooler arranged adjacent to said slots, and means for supplying said cooler with water destined to be evaporated in said boiler.

9. A boiler having a furnace forY pulverulent fuel comprising a combustion chamber in the lower portion of said furnace, a burner in said combustion chamber comprising a wall provided with a plurality of slots for the discharge of a mixture of fuel and primary air, a cooling water conduit arranged adjacent to said wall, a pipe for supplying water to one end of said conduit, and a pipe connecting the other end of said conduit to the boiler.

10. -A boiler having a furnace for pulverulent fuel comprising a fire-box, an arch projecting into the fire-box, a combustion chamber located in the lower portion of the furnace, a burner in the combustion chamber, said burner comprising a cooling conduit and a cooling water pipe connected to said conduit, said cooling Water pipe extending beneath and forming a supporting means for said arch.

11. A boiler comprising a combustion chamber for pulverulent fuel, a burner arranged in the combustion chamber, said burner havin a plurality of slots for the discharge o a fuel and air mixture, a water cooling means for said burner, and a pipe line extending through said furnace and including said cooling means, said pipe line being so connected to the water space of the boiler that its inlet end is at a lower level than its outlet end.

In testimony whereof we aiix our signatures.

VALTER KLEINOV. ALBERT MORGENROTH. FRIEDRICH REINHARDT. WILHELM BRUER.

Images