US2140317A - Stoker - Google Patents

Description

13, 1938. i c. E. HARRISON vsToKER Filed Jan. 1e, 1955 Inventor Chiffon] Hdrrilson www que@ Patented Dec. 13, 1938 UNITED STATES PATENT oFFioE STOKER Application January 16, 1935, Serial No. 2,033

5 Claims.

This invention relates to an improved grate construction for stoker furnaces, which enables eiiicient burning of all grades of fuel.

In the prior art constructions air is emitted to the fuel bed through a series of superimposed tuyres having air passages provided around the sides and rearwardly disposed ends thereof. In such constructions a large quantity of the incoming draft air is directed along the longitudinal center line of the tuyre rows with the result that those portions become extremely active. A furrow thus forms along the center line of each tuyre row and the portions of the fuel bed adjacent these furrows become the most active parts of the fuel bed.

One object of the present invention is to provide an improved tuyre which functions in operation to increase the number of such active areas in the fuel bed and thus increase the burning rate of the Stoker.

Another object is to provide a tuyre block which in operation is maintained at an extremely high temperature to prevent slag adherence thereto and which is so constructed as to deflect any slag coming into contact therewith into the adjacent retorts or toward the rear of the Stoker.

Such a tuyre block construction is highly desirable, especially when fuels are rburned having an ash content which fuses at relatively low temperatures. In the prior art constructions the molten ash flowing through the fuel bed congeals or solidies when coming in contact with the relatively cold incoming air or the tuyre blocks, forming clinkers which not only clog the air openings therein, but which grow to such an extent as to impair the operation of the stoker. Such clinkers also cause considerable damage to the stoker parts. The present invention contemplates an improved construction which eliminates these undesirable conditions.

Other and further objects of the invention will become apparent as the description of the invention progresses.

Of the drawings:

Fig. l is a longitudinal sectional view taken through one of the retorts of an underfeed Fig. 5 is a plan View of the tuyre block shown in Fig. 4 in inverted position.

Fig. 6 is a side View partly in section, showing the manner in which the tuyre blocks are assembled.

Fig. 7 is a fragmentary plan view of a modified tuyre block construction. g

Referring to the drawings, the numeral I designates generally a furnace including in the present instance, a multiple retort underfeed stoker 2, comprising alternately disposed retorts 3 and tuyre rows 4. Fuel is fed to the retorts 3 from hoppers 5 by any suitable fuel feeding mechanism designated at 6, and a series of pushers l mounted in the bottom of the retort underfeed the fuel to extension grates 8, which in turn overfeed the residue to an ash pocket 9, extending transversely of the Stoker between the lower end thereof and a bridge wall shown at l0. 'Ihe individual tuyre blocks 4 may be composed of a highly refractory heat resistive material such as silicon carbide, or of any other suitable material. When the terms front and rear are employed in the description of the invention it is to be understood that the term front indicates those portions of the parts extending toward the front or fuel feeding mechanism 6 of the Stoker, and rear indicates those portions extending toward the rear or bridge wall Il) of the furnace.`

Referring to Figs. 4 to 6, it will be noted that each tuyre block 4 is of extremely rugged construction, and thus capable of withstanding the severe conditions of furnace operation. The top surface II of each tuyre block 4 has provided therein a depression I2, the side and rear walls I3 of which incline downwardly, and inwardly, as shown more particularly in Fig. 4. A series of slots I4 extend from depression I2 to the side edges I5 of each tuyre block through which draft air may pass. These slots are inclined slightly from front to rear of the block so that the air is directed into the fuel bed at a slight angle. These passages may be disposed normal to the direction of fuel movement but it has been found that better results are obtained by arranging the passages as herein shown. The nose portion I'I of each tuyre block inclines downwardly from front to rear thereof and is of substantially sinuous construction having a central groove I8 and outwardly and downwardly inclining side portions I9 and 20.

The under side 22 of each tuyre block 4 is also provided with a depression 23, the side and end walls 24 of which also incline downwardly and inwardly, as shown in Fig` 5, and a series of slots 25 also extend from the depression 23 to the outer side edges I5 of the block through which draft air also may pass.

As shown in Figs. 5 and 6, each tuyre block is also provided with a pair of inclined side edges 21 and 28 which in assembly rest upon the retort side plates 29. Also, when assembled on the stoker the substantially flat surface 22 of each tuyre block rests upon the upper flat surface I I of the next lower tuyre of the series. A spacing element 30 provided intermediate the side edges I 5 of each tuyre block 4 in assembly is adapted to abut against the forward edge 3l of the next lower tuyre block of the series, as shown in Fig. 6.

Referring to Fig. 6, it will also be noted that the slots I4 and 25 are arranged in staggered relation, thereby causing a better distribution of the air emitted therethrough to the fuel bed. Depressions I2 and 23 provided in the `upper and lower surfaces respectively of each tuyre block 4 are open at their front ends, thus forming inlet passages for draft air entering the tuyres from the plenum chamber 32 provided beneath the stoker. By this arrangement of air passages in the tuyre blocks no air is permitted to pass through the nose portion thereof and as a result it will become intensely hot during the operation of the furnace. In order to prevent damage to the side plates 29 upon which the tuyre blocks 4 are supported, the inclined portions 2T and 28 of each tuyre block are provided with insulat ing portions 33, as shown in Fig. 3. Thus the heat absorbed by the tuyre blocks is retained and not readily conducted to the metallic side walls 29 supporting the same.

By maintaining the nose portion of each tuyre block in this heated condition, it is apparent that any molten ash coming in contact therewith will not congeal but instead will remain in its molten state and as a result will flow down the central channel I8 toward the rear of the stoker or be deflected into the adjoining retorts by the inclined portions I9 and 20, depending upon what portion of the blocks the slag comes in contact with. Thus clinkers can not form on the tuyre blocks and grow to such an extent as to impair the operation of the stoker. In the older constructions, especially when low grade coals are burned thereon, the molten ash congeals or solidies when coming in contact with the relatively cold incoming draft air or the tuyres and as a result clinkers form, which in many instances grow to such an extent as to impair the operation of the stoker. Considerable damage also results to the stoker parts, which necessitates frequent delays in or der that the damaged parts may be renewed. These undesirable occurrences are reduced to a minimum in the present construction. In order to divert any molten slag away from the air openings I4 and 25, and thus prevent clogging thereof, a slag ledge 38 is provided at the sides of each tuyre block intermediate said openings.

The arrangement of air passages in the tuyre blocks as hereinbefore described, also results in the production of a more active fuel bed than is the case in the older constructions. As shown in Fig. 3, by emitting draft air to the fuel bed from the sides of the tuyres only, the portion thereof adjacent the longitudinal center line of said tuyres receives but little air and consequently builds up. As a result the air iiows upwardly as indicated by the arrows, and causes furrows in the fuel bed to form longitudinally thereof substantially along the side edges of the tuyre rows. Thus two such furrows for each retort are formed rather than a single one along the longitudinal center line of each tuyre row as is the case in the older constructions, and inasmuch as the portion of the fuel bed defining these furrows is constantly subjected to the incoming draft air a very active fuel bed results.

Under certain conditions it may be desirable to permit a small quantity of air to pass through a portion of the nose end of each of the tuyre blocks. This may be desirable tocontrol the temperature of the nose end. In this way the viscosity of the slag may be controlled. To this end slots 35 and 35 are provided in the upper surface of the nose portion, as shown in the modified tuyre block 4' in Fig. 7.

From the foregoing description it is believed to be apparent that the present invention not only produces a more active fuel bed, thereby insuring better efficiency, but involves a construction which insures longevity of service. The highly refractory material of `which the tuyre blocks are composed is well able to withstand the furnace temperatures and the blocks are so constructed as to effectively dispose of any molten ash coming in contact therewith, thereby insuring efficient operation of the stoker at all times.

The individual tuyre blocks also present a novel construction which generally improves the op eration of the Stoker as a whole.

While the embodiments herein shown and described are admirably adapted to fulfill the objects primarily stated, it is to be understood that the invention is not to be limited to those l particular embodiments, since it may be einbodied in other forms, all coming within the scope of the claims which follow.

What is claimed is:

l. A furnace tuyre block of approximately rectangular form, having when in operated position substantially fiat vertical side surfaces, and substantially horizontal top and bottom surfaces, and being provided with passages for draft air extending along said top and bottom surfaces and inwardly from said side surfaces, a slag ledge projecting outwardly from each of said side surfaces and intermediate said top and bottom surfaces for diverting slag away from said passages extending along said bottom surface, and said tuyre block having a nose portion of substantially sinuous construction.

2. In a stoker furnace, the combination with alternately disposed fuel retorts and rows of tuyre blocks, of a rugged heat absorbing nose portion on each of said tuyre blocks, the upper and lower surfaces of said nose portions, being substantially fiat and in assembly, lying in abutting relation with adjacent tuyre blocks and presenting unbroken supporting surfaces to prevent the passage of air between said nose portions, and said tuyre blocks being provided with passages for draft air extending along the top and bottom surfaces thereof, and inwardly of said side surfaces, said passages being disposed forwardly of said nose portions, and each of said lnose portions having a central downwardly inclined groove forming with the grooves of adjacent tuyre blocks a channel extending over the length of the tuyre row for conducting molten slag toward the rear of said Stoker, and laterally extending and downwardly inclined slag diverting means provided at each side of said groove to divert the slag coming in` contact therewith into said retorts.

Lli)

3. A furnace tuyre block adapted for assembly with similar tuyre blocks in superimposed relation, said tuyre block comprising an approximately rectangular body portion having substantially at top and bottom surfaces and vertical side surfaces and terminating at one end thereof in a rugged solid nose portion, said body portion being provided with passages for draft air extending along said top and bottom surfaces and inwardly from said side surfaces, said passages being disposed forwardly of said nose portion to prevent draft air from coming in contact therewith whereby said nose portion is maintained extremely hot during operation of the furnace, and slag diverting means provided on said nose portion, said slag diverting means comprising a central groove and downwardly inclined portions extending laterally of said groove.

4. A furnace tuyre block adapted for assembly with similar tuyre blocks in superimposed relation, said tuyre block comprising a body portion having substantially at top and bottom surfaces and vertical side surfaces, and a rugged solid nose portion, and being provided with passages for draft air extending along said top and bottom surfaces and inwardly from said side surfaces, said passages being disposed forwardly of said nose portion to prevent draft air from coming in contact therewith, whereby said nose portion is maintained extremely hot during operation of the furnace, slag diverting means provided in said nose portion comprising a downwardly inclined central groove, and transverse, downwardly extending portions on either side of said groove, andA a slag ledge extending laterally from each of said side surfaces for diverting slag away from said passages extending along said bottom surface.

5. A furnace tuyre block of approximately re'ctangular form, having, when in operative position, substantially flat top and bottom surfaces and vertical side surfaces, and being provided with passages for draft air extending along said bottom surface and inwardly from said side surfaces, and means disposed above said passages and extending laterally of said side surfaces for diverting any slag away from said passages to prevent clogging thereof.

CLIFFORD E. HARRISON.

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