US2079696A - Stoker furnace - Google Patents

Description

, STOKER FURNACE Filed Dec. 18, 1931 4 Sheets-Sheet l May 11, 1937. H. E. PRESTON STOKER FURNACE Filed Dec. 18, 1931 4 Sheets-Sheet 4 Patented May 11, 1937 PATENT OFFICE STOKER FURNACE Herbert E. Preston,

Philadelphia, Pa., assignor to American Engineering Company, Philadelphia, Pa., a corporation of'Pennsylvania Application December 18, 1931, Serial No. 581,948

5 Claims.

This invention relates to improvements in stoker furnaces, and has a particular application to furnaces employing multiple retort underfeed stokers of the class disclosed in U. S. Patent No. 1,443,202. r

A principal object of the invention is to provide novel and improved means for maintaining the furnace wall surface, and particularly the surfaces abutted by or adjacent to the fuel-bed, relatively free from adhesions of fused particles of refuse either originating in the fuel-bed or flowing down the wall from above the fuel-bed in the form of slag.

A more specific object of the invention is to provide means for maintaining between the fuelbed and the adjacent wall surfaces and in the areas of maximum clinker formation a, screen of air or other gas tending to prevent clinker adhesion or so modifying the physical characteristics of the clinkers as to render them readily removable by the abrasive action of the moving fuel over the wall surface.

The invention further contemplates the provision ina furnace side wall of a novel nozzle construction highly effective for the aforesaid purposes. l

The'invention further residesin certain novel structural details and arrangements hereinafter set forth and illustrated in the attached drawings, in which: 7

Figure 1 is a side elevational and partial sectional view showing the side wall of a Stoker furnace of the type set forth embodying my invention; I

Fig. 2 is a section on the line 2-2, Fig. 1;

Fig. 3 is an enlarged fragmentary sectional view corresponding to Fig. 2 illustrating certain details of the construction;

Fig. 4 is a section on the line 4-4, Fig. 1;

Fig. 5 is a section on the line 5-5, Fig. 1;

Figs. 6 and 7 are perspective views respectively showing the reverse sides of one of the nozzle elements;

Fig. 8 is a sectional view of a portion of the nozzle assembly taken on the line 8-8, Fig. 1;

Fig. 9 is a front elevational view of the upper terminal section of the box;

Fig. 10 is a lower end elevation of the structure shown in Fig. 9;

Fig. 11 is a section onthe line I I--I I, Fig. 9;

Figs. 12 and 13 are respectively front and end elevational views of the terminal nozzle; and

Fig. 14 is a section on the line I l-44, Fig. 12.

With reference to Fig. 1 of the drawings, l is the side wall of, a multiple retort underfeed stoker furnace, the tuyere line of the furnace defining the stoker grate being indicated at 2 in broken lines. A wind-box, the lower portion of which is shown at 3, is provided below the stoker grate, from which box air passes to and through the tuyeres to the fuel-bed in well known manner.

In accordance with my invention, I provide the side wall l of the furnace with a passage or duct 5, this passage at its upper end and as shown in Fig. 1 extending substantially the full length of the stoker grate structure, the terminal walls of the passage 5, shown in Fig. 1 in broken lines, being indicated by the reference numeral 6. As therein illustrated, the passage 5 extends upwardly in the wall to a point in the present instance somewhat above the line of the tuyres 2. The end walls 6 of the passage 5 converge downwardly, and the lower end of said passage communicates with an opening I in the inner portlon of the wall i, this opening as shown in Fig. 4 being connected with the interior of the windbox through a suitable duct 8. This duct has a branch 9, the function of which will be hereinafter described. A valve It in the duct 8 controls the opening I, and valves I2 and I3 control the branch 9 and that portionof the duct 8 which extends to the wind-box. As shown in Fig. 5, the portions ofthe wall forming the opposite faces of the passage 5 may be united by tie plates or anchors 5a.

Set into the wall I and in the present instance co-cxtensive with the upper end of the passage 5 is a metallic or other suitable box I5, this box having in its bottom wall a longitudinal opening I6 communicating directly with the passage 5. The inner side of the box I5 is open to the interior of the furnace, the box thereby forming a recess in the side wall I which extends longitudinally of the grate structure of the stoker and somewhat above the upper surface of the latter. The box I5 in the present instance is so formed and so arranged within the wall I that the recess in said wall formed thereby lies somewhat below the upper surface of the fuel-bed and conforms to the fuel-bed contour. Preferably, the box is made in longitudinal sections, and in the embodiment illustrated in Fig. 1, two such sections are shown, the upper being curved and the lower adjoining section being straight. This provides for standardization of the boxeswhile meeting the requirements of furnaces of different sizes. For installations of greater length, the box may be terminated at its lower end by a curved section (see broken lines Fig. 1) which may correspond to the upper curved section in Cal the reverse position; and if still greater length is required an additional straight section, or sections, may be inserted.

At its inner edges and as best shown in Fig. 3, the box It is provided with depending and upstanding flanges, I! and 18 respectively, which constitute retaining means for a series of nozzle elements I9. A preferred form of these elements is illustrated in Figs. 6, 7 and 8. As therein illustrated, each comprises a pair of rearwardly extending arms 2| and 22, the outer ends of which are offset to provide shoulders which interlock with the flanges I1 and N3 of the box [5 to retain the elements in the latter. Joining the inner ends of the arms 2| and 22 is an arcuate body portion 23, which portion is dished or formed at an angle to the plane of the said arms. At the upper end and at one side of the body portion 23 is 2, lug 24, and at the opposite end is a corresponding and somewhat larger lug 25. These lugs in effect form spacing elements for the body portions of the adjoining elements and define between their inner faces the nozzle apertures through which the boxes l5 are in communication with the interior of the furnace. The upper face of each of the lugs 25 forming the bottom of the nozzle aperture is in the present instance sub stantially horizontal; while that face of the lug 24 forming the top of the aperture is beveled upwardly and outwardly. In the present instance, the nozzles are positioned in the box with the side thereof containing the lugs 24 and 25 toward the rear wall 26 of the furnace, and the formation of the body portion 23 of the nozzle elements and of the lugs 24 and 25 is such that air 01 other gas passing from the box into the interior of the furnace is projected fan-like upwardly and rearwardly along the surface of the wall I, the jets of air from the various nozzle openings forming in effect a screen of gas between the wall surface and the fuel-bed and over the adjoining wall areas. The relative arrangement and form of the nozzle openings are well illustrated in Fig. 8.

The nozzle elements l8 are readily inserted in the boxes by passing the arms 2| and 22 inwardly through the opening between the flanges I! and I8, and thereafter turning the elements angula-rly to bring the arms into interlocking engagement with the said flanges, as illustrated in Fig. 3.

Since a full complement of nozzle elements could not thus be inserted in the boxes, I provide a terminal nozzle of special design illustrated in Figs. 12 and 13. At one end surface the body portion of this nozzle 3| is shaped correspondingly With the other nozzle elements, but the body portion is elongated and is held in the box not by means of interlocking shoulders but by a bolt 30 which passes through an elongated opening 32 in the nozzle and through a suitable lug 33 formed in the box. Preferably the head of the bolt is confined within a recess 34 in the said lug to prevent the bolt from turning. The elongated opening 32 provides for movement of the block 3| in expansion and contraction of the series of nozzle elements, and it will be noted that in the present instance the said opening 32 is formed in the bottom of a recess 35 which provides for packing a refractory material around the nut to protect the latter.

e ably, as illustrated in Fig. 9, the box 55 is provided with partitions [5 which divide said box into separate compartments, which provides for zoning or limiting the supply of air or gas to different groups of nozzles. For this purpose and as illustrated in Fig. 3, I may provide suitable steel or other plates 36 which may be secured in the bottom of the box so as to block off any desired portion of the bottom opening I6 of the individual compartments.

To facilitate the installation of the box IS in the Wall of the furnace where, as in the illustrated embodiment, the said box extends at an angle to the horizontal, I may provide the top and bottom Walls of the box with a. series of brackets 38 which may be secured to the box by bolts or in any other convenient manner, these brackets providing horizontal and vertical surfaces for abutment with the bricks of the said wall. The brackets 38 obviously may be formed as integral parts of the box structure.

In Fig. 4, I have illustrated means whereby the passage or duct 5 may be connected to the wind-box 3 of the stoker, this connection providing for diversion of a portion of the combustion air to the box 15. As previously set forth, I also provide an independent duct 9 for directing to the box l5 air or gas from other sources, such, for example, as inert flue gases of the fur nace or oxygen. Use of the stack gases has the effect of cooling without materially increasing the rate of combustion of the fuel adjoining the side walls; and it has been found that oxygen projected through the nozzles from the box 15, by increasing the rate of combustion in the affected areas, tends to burn or melt the clinker, which then drips into the fuel bed to be carried off with the ash.

In a stoker furnace of the type set forth, the point of inception of clinker formations on the walls is slightly below the top of the fuel-bed, and clinkers forming and growing in this area unchecked interfere materially with the normal fuel-feeding function and consequently with the efficiency of the stoker and the furnace as a whole. By maintaining a screen of a fluid medium over the wall surface embracing the said points of inception, the formation of clinkers may be prevented or minimized, and by confining the fluid to the wall surface and to the stated areas, the desired result may be accomplished with little or no interference with the normal combustion process. The aforedescribed construction accomplishes the desired result, the fluid being directed upwardly and laterally from a point corresponding with or slightly below the clinker-inception area but well above the bottom of the fuel bed. A single row of nozzles placed as described above somewhat below the upper surface of the fuelbed and adapted to project the fluid upwardly and preferably toward the rear wall of the furnace and over the surface of the side wall has been found entirely effective.

It will be apparent that there may be considerable modification without departure from the underlying principles of the invention.

I claim:

1. In a device of the character described, the combination with a furnace wall having a relatively narrow passage therein extending below the points of maximum clinker formation, and terminating in the inner surface of said wall, of a plurality of nozzle elements detachably mounted in said terminal end in side-by-side relation, and lugs on the sides of said nozzle elements to retain them in spaced relation, said nozzles having their oppositely arranged faces beveled and forming therebetween nozzle openings inclined to the face of the wall through which a gaseous medium may be ejected from the passage over the inner surface of said wall embracing the points of maximum clinker formation.

2. A nozzle element adapted for assembly in side-by-side relation with similar elements to form a nozzle structure, said element having a body portion substantially in the form of a dished segment, a lug at the top and bottom of said body portion respectively, said lugs constituting spacers which in assembly form the upper and lower edges of nozzle openings between the sides of the adjoining elements, the said bottom lug having an upper surface extending in assembly in a substantially horizontal direction, and the upper lug having an upwardly and outwardly beveled face defining the upper edge of said nozzle opening whereby a gas ejected through said openings is directed transversely and upwardly from the forward face of the nozzle assembly.

3. A nozzle element adapted for assembly in side-by-side relation with similar elements to form an elongated nozzle structure, said element having a body portion in the form substantially of a dished segment, nozzle-retaining elements projecting from the rear edge of said body portion, lugs projecting from a side surface of said body portion at top and. bottom of the latter and in assembly defining the upper and lower edges of nozzle openings formed between said elements, that surface of at least one of said lugs which defines the edge of said opening being beveled and diverging outwardly from the opening-defining surface of the other lug.

4. In a device of the character described, the combination with a furnace wall having a relatively narrow passage terminating in the inner surface thereof, the terminal end of said passage being formed on a line having adjoining straight and curved portions so arranged that they conform substantially with the normal fuel bed contour, of a box mounted in said wall and defining the terminal end of said passage, said box having straight and curved sections corresponding to the straight and curved sections of the passage, a plurality of nozzle elements detachably mounted in said box at the terminal end of said passage in side by side relation, and lugs on the sides of said nozzle elements to retain them in spaced relation, said nozzles having their oppositely arranged faces beveled and forming therebetween nozzle openings inclined to the face of the wall through which a gaseous medium may be ejected from the passage over the inner surface of said wall embracing the points of maximum clinker formation.

5. In a device of the character described, the combination with a furnace wall having a relatively narrow passage therein extending below the points of maximum clinker formation and terminating in the inner surface of said wall, of a plurality of nozzle elements mounted in side by side relation in the terminal end of said passage, lugs on the sides of said nozzle elements to retain them in spaced relation, said nozzle elements having their oppositely arranged faces beveled and forming therebetween nozzle openings, for directing a cooling medium, such as air, over the inner surface of the wall embracing said points of maximum clinker formation, interlocking means in said passage and on said nozzle elements for securing the latter in said passage by an angular movement of the nozzle elements following insertion thereof in the end of the passage, a terminal nozzle, and independent fastening means for said terminal nozzle adapted for manipulation following insertion of said nozzle in the end of said passage to secure the nozzle in position.

HERBERT E. PRESTON.

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