US1958842A - Furnace tuyere - Google Patents

Description

y 5, 1934. J. s. BENNETT 1,958,842

FURNACE TUYERE Filed May 27, 193?. 3 Sheets-Sheet l [NVENTOR JOSEPH 6T BENNETT BY Wm M ATTORNEY May 15, 1934.

Filed May 27. 1932 J. S. BENNETT FURNACE TUYERE 3 Sheets-Sheet 2 [NVENTOR JOSEPH 5'. BENNETT A TTORNE Y Patented May 15, 1934 UNITED STATES PATENT OFFICE Application May 27, 1932, Serial No. 614,127

12 Claims.

This invention relates to stoker fired furnaces, and more particularly to the tuyeres employed in such devices.

In modern power plants there is a growing tendency to install larger boiler units and to 0pcrate these units at extremely high ratings. The furnaces employed in connection with such boilers must necessarily be capable of delivering the maximum amount of heat per unit area of grate surface in order to supply the necessary heat thereto. For that reason every precaution is taken to eliminate the heat losses of the furnace. One of the important losses lay in the heat .absorbed from the furnace by the incoming draft air and to reduce this loss as much as possible the air is preheated before it enters the furnace. In some plants this air has been heated to a temperature of over 700 deg. F. It has been found that many of the older types of furnace tuyres when subjected to these high temperatures deteriorate rapidly making it necessary to take the boileroff the line at frequent intervals so that the damaged parts may be replaced. The user of such units has therefore been subjected to considerable losses, especially when a unit must be taken off the line during peak loads. The losses in time and fuel, and also the cost of maintenance may become very great and the efficiency of the unit is thus materially reduced.

One object of the present invention is to reduce such losses to a great extent by constructing the grates of the furnace in such a manner that they will be capable of withstanding the severe conditions of modern furnace operation without material deterioration, and thus permit operation of the furnace for long periods of time.

Another object of the invention is to provide a tuyere block of a double deck construction, each surface of which being cooled by the draft air passing therethrough.

A further object of the invention is to provide a tuyere block in which the portions thereof subjected to the heat of the burning fuel are readily renewable and which make point contact with the body portion of the tuyere so as to 'protect the latter against the heat conducted through said renewable elements.

A further object of the invention is to provide a tuyre block having a base portion of metal and fractory material, and to provide a plurality of air passages between the refractory elements and the base portion.

A further object is to provide a composite tuyere block having a base portion of ferrous material and superimposed elements of a highly refractory material attached thereto in such a manner that the stresses set up by one portion due to expansion and contraction thereof will not affect the other. 6

A further object of the present invention is to provide a tuyre block having a base portion of metal and a series of renewable fuel supporting refractory elements arranged in spaced relation with the body portion, the latter of which having a series of air channels therein, and the refractory elements being so constructed as to extend slightly beyond the extremities of the body portion to prevent slag from interfering with the flow of air through said passages.

A further object is to provide a tuyere block composed of a body portion of ferrous material and a number of superimposed elements of a highly refractory material, said tuyre blockbeing so constructed that the ferrous material will bear the load of the fuel and the refractory elements substantially only the compressive stresses imposed by said fuel.

A further object of the invention is to provide a tuyre block having a body portion of ferrous material and superimposed portions of a highly refractory material, said parts being so arranged that no part of the ferrous material will be in contact with the burning fuel. a

A further object of the invention is to construct 90 a tuyre block in such a manner as to eliminate the passage of fuelsiftings therethrough.

A further object is to provide a tuyre block with a series of air passage defining ribs projecting from both the upper and lower surfaces thereof and which terminate inwardly of the outer end of said block to prevent clogging of the passages by slag which may form during the operation of the furnace.

A further object is to provide a tuyere block having base portion comprised of ferrous material and a number of superimposed elements of a highly refractory material, the refractory elements being supported at spaced points on said body portion in such a manner that in case 5 cracking of the refractory material should occur during operation of the furnace they would still be retained in place without interfering with the proper operation of the tuyere'block.

'Other and further objects of the invention will torts.

. and 3.

become apparent hereinafter as the description of the invention progresses.

Of the drawings:

Fig. 1 is a side elevational. view taken through one of the retorts of an underfeed stoker, showing the arrangement of the tuyere blocks.

Fig. 2 is a plan view of one of the tuyere blocks comprising the present invention.

Fig. 3 is a side View of the tuyere block shown in Fig. 2.

Fig. 4 is a View taken on line 44 of Fig. 1.

Fig. 5 is a view taken on line 5-5 of Fig. 1.

Fig. 6 is a plan View with some of the parts thereof removed to show the construction of the body portion of the tuyere block.

Fig. '7 is a side view of the device shown in Fig. 6.

Fig. 8 is a view showing the construction of the lower surface of the removable elements of the tuyre block.

Fig. 9 is an end view of the elements shown in Fig. 8.

The accompanying drawings illustrate the tuyre blocks comprising the present invention as applied to an underfeed stoker of the inclined grate multiple retort type. The illustrated embodiment, however, is subject to modification and change without departing from the invention so as to be adapted for use in connection with other types of stokers as well.

Referring to the drawings, 1 indicates the front wall, and 2 one of the side walls of a furnace equipped with a multiple retort underfeed stoker 3, comprised of alternately disposed retorts 4 and tuyere rows 5 extending lengthwise of the stoker and inclining downwardly from front to rear thereof. In the drawings but one retort 4 and row of tuyere blocks 5 is shown, it being apparent that any number may be employed. Fuel is supplied to the retorts of the stoker from hoppers 6 which communicate with cylinders '7, each having a fuel feeding ram 8 provided therein. A series of pushers 9 are provided in the bottom of each retort 4 forunderfeeding the fuel along the re- Extension grates 10 provided at the rear of the stoker feed the consumed fuel into an ash pit 11. The fuel feeding rams are actuated by any suitable power mechanism indicated at 12'. The pushers and extension grates are also actuated by the power mechanism 12 through the connections indicated generally at 13.

The specific construction of the operating mechanism for the rams and pushers forms no part of the present invention, and therefore, a

, detailed description of this mechanism is unnecessary.

The tuyere blocks 5 are supported upon the upper edge of the walls 14 of adjacent retorts and span the space therebetween as shown in Figs. 1 The chamber beneath the tuyere blocks defined by adjacent walls 14 communicates with a chamber 15 common to each series of tuyere blocks and into which draft air is supplied by any suitable blower mechanism (not shown). tuyere block comprises a body portion 16 composed of any suitable material, and superimposed elements 1'7 and 18 removably attached thereto. While both the body portion 16 and elements 17 and 18 may be constructed either of metal or of some highly refractory material such as silicon carbide, it is preferable to construct the former of cast iron and the latter of silicon carbide.

The body portion 16 of each tuyere block comprises two relatively thin flat sections 19 and 20 arranged in spaced parallel relation which Each extension 23 intermediate the side edges thereof for receiving hooks 31 depending from the lower side of section 19 of the next adjacent tuyre block 5. Section 20 is also provided with a substantially circular aperture 32in longitudinal alignment with aperture for receiving a lug 33 also depending from the lower surface of section 19 of the next adjacent tuyere block. In assembling the tuyere blocks in the stoker itis only necessary to insert the hooks 31 into aperture 30 and to move the upper tuyere block for-- wardly until the vertical portion of the hooks engage the front wall of the aperture and then lower the rear end thereof so that lug 33 engages in aperture 32. The hooks 31 engage the lower surface of extension 23 and thus prevent vertical movement of the tuyre blocks. Hooks 31 and lug 33 in assembly, also prevent lateral movement of the tuyere blocks.

It will be noted that the lower edge of side members 21 and 22 incline upwardly from front to rear of the tuyere as shown at 34, Figs. 3 and 7, the inclination of which corresponding with that of side walls 14 of the stoker. These edges of each tuyre block rest upon the upper edge of adjacent side walls 14 and the rearmost end of section 20 extends between said walls. Thus, when the tuyere blocks are assembled in the stoker, sections 19 and 20 will assume a substantially horizontal position and through the interlocking connections just described will be held securely in position. The side edges of section 19 of each tuyere block converge as shown in Fig. 6, forming a reduced nose portion at the forward end thereof.

The upper surface of section 19 is provided with a series of radially extending projections 35 arranged in spaced relation around the nose thereof which, as will be apparent hereinafter, define air passages through which air from chamber 15 passes to the fuel bed. The lower surface of section 19 is likewise provided with a series of radially extending projections 36 which also define air passages through which some of the draft air passes to the fuel bed. Projections 36 extend downwardly from points located between projections 35 so that the mass of the metal constituting this portion of the tuyere is equally distributed. A pair of studs 37 are also provided on the upper surface of section 19 near the side edges thereof and to the rear of the terminal projections 35 the purpose of which will also presently appear.

It will alsobe observed that the lower surface of section 19 is provided with a pair of depending bearing portions 47. These portions, when the 131.12% blocks are assembled in the Stoker; rest upon the next adjacent tuyere blocks and thus define a passage 38 (Fig. 5) through which air from chamber 15 flows to the passages defined by the projections 36.

Referring to Figs. 2, 3, 8 and 9, it will be seen that elements 17 and. 18 are supported upon the l body portion of the tuyre block in spaced relation with section 19 thereof, and that the side edges thereof also converge in conformity with the nose portion of section 19. The outer edges of elements 17 and 18 extend slightly beyond the outer edge of section 19 thereby forming an overhanging ledge. By this construction any slag that may form upon said elements will be diverted away from the body portion of the tuyere block so as not to interfere with the flow of air through the passages 35, and 36 provided therein. The rear portion of elements 17 and 18 are so constructed as to fit snugly against the forward edges of section 20 and extension 23 thereof, as shown more particularly in Fig. 2. The abutting edges 39 and 40 of elements 17 and 18, respectively, are grooved so as to form a lap joint to prevent fuel siftings from passing between said elements. The elements 17 and 18 are of substantially uniform thickness and in assembly the upper surface thereof is flush with the upper surface of section 20 and extension 23. The rearmost portions 41 and 42 of elements 17 and 18, respectively, extend downwardly beyond the lower surface of said elements and in assembly rest upon the upper surface of section 19. Cylindrical bores 43 and 44 are provided in portions 41 and 42 which extend substantially midway through the same and in assembly are fitted over the studs 37 to secure said elements against lateral movement.

Referring to Figs. 8 and 9, it is seen that the curved portions 45 and 46 of elements 17 and 18 are beveled as shown at 49 and 50. A pair of recesses 51 and 52 are provided in these beveled surfaces which in assembly receive lugs 28 and 29 extending outwardly from the lower side of extension 23. The lower surface of elements 17 and 18 is also provided with a series of radially extending recesses 53, the depth of which being substantially equal to one-half the depth of projections 35. These recesses are patterned after the construction of projections 35 and are fitted over the latter when the elements 17 and 18 are assembled on the body portion 16 of the tuyere block. The recesses 43, 44, 51, 52 and 53 are slightly enlarged so that independent expansion and contraction of elements 17 and 18 and body portion 16 can take place.

In assembly element 17 obviously is first placed on body portion 16 of the tuyere so that projections 28, 35 and 37 engage in recesses 51, 53 and 43 respectively. Element 18 is then likewise assembled on the body portion 16 by so positioning the same that projections 29, 35 and 37 will engage in the corresponding recesses of said el ment. When the parts are thus assembled it is seen that elements 17 and 18, with the exception of portions 41 and 42 thereof, are spaced from the upper surface of section 19 and that the lower surface of said elements and the top surface of section 19 form with the projections 35 a series of separate air passages through which draft air may pass to the fuel bed from chamber 15. When the tuyere blocks are assembled in the stoker the projections 36 rest upon the top surfaces of elements 17 and 18 of the next lower tuyere block of the series and the bearing portions 47 rest upon the upper surfaces of portions 40 and 41 thus defining, as described hereinbefore, a chamber 38 through which air may pass from chamber 15 to the passages defined by projections 36.

By this construction the incoming air will fiow in the direction of the arrows shown in Figs. 1

and 3 through the passage 48 defined'by sections 19 and 20 and side members 21 and 22, and through the various passages defined by projections 35. Air will also flow through the passage 38 to the passages defined by projections 36. Thus, both the upper and lower surfaces of ele-' ments 17 and 18 and sections 19 and '20 are exposed to the incoming air and will be sufficiently cooled to prevent deterioration thereof. Owing to the length of sections 19 and 20 the passage of fuel siftings between the tuyere blocks to the chamber 15 therebeneath is practically eliminated.

As pointed out before, the outer edges of elements 17 and 18 overhang the outer edge of section 19 so that any molten slag which may form upon these elements during operation of the furnace will be deflected away from the metallic body portion of the tuyere block. Also, by so con structing the projections 35 and 36 as to terminate inwardly of the outer edge of section 19, clogging of the passages defined thereby is practically eliminated. If by any chance the flow of air through some of these passages is obstructed. it would still pass around the outer edge of said projection and into the fuel bed at a point adjacent thereto. However, even in such cases all parts of the tuyre blocks will be in direct contact with the incoming air and thus are cooled sufiiciently to withstand the heat of the furnace.

It Will also be observed that the elements 17 and 18 are so positioned on the tuyere blocks that when the latter are assembled in the stoker the metallic body portion thereof will be out of contact with the burning fuel. The elements 17 and 18 may be formed of a highly refractory material which is capable of withstanding the extreme temperatures existing in modern furnaces with-' out material deterioration. By the present method of attaching the elements 17 and 18 to the body portion 16 of the tuyere block, the heat from the furnace conducted through these elements.

simply affects the spaces points of contact and not a substantial portion of the main surface.

thereof. These points of contact are constantly exposed to the incoming air and thus are maintained suificiently cool to prevent damage thereto.

The interlocking connections between elements 17 and 18 and body portion 16 of the tuyere blocks effectively secures said elements in position, and even in case cracking thereof should occur, they will still remain intact and not be distorted by the action of the moving fuel.

It is alsoseen that by the present construction the metallic body portion of each tuyre block, which is preferably constructed of cast iron, carries the greater part of the load imposed by the fuel and that the refractory elements 17 and 18 are simply placed in compression by the'fuel supported thereby. Inasmuch as the body portions of the tuyere blocks are protected from any contact with the burning fuel, and are constantly cooled on both the upper and lower surfaces thereof by the incoming draft air, they will undergo but little deterioration even when subjected to the severest conditions of furnace operation. The superimposed refractory elements are designed to withstand the high temperatures of furnace operation and inasmuch as they are not subjected to any tensile stresses they also will undergo but little deterioration. A furnace employing these tuyere blocks may thus be operated at high capacities for long periods of time and'the losses incident to taking a boiler off the line for repairs and also the cost of maintenance is reduced to a minimum.

While the tuyere blocks comprising the present invention are admirably adapted for use in connection with underfeed stokers, it is obvious that they may be modified slightly so as to be used in other types. of stokers, blast furnaces, or in any device wherein the air emitting nozzles are subjected to high temperatures. The invention is therefore not to be limited to tuyere blocks of the specific type shown herein, but only by the scope of the claims which follow;

What is claimed is:

l. A tuyere block comprising a body portion having a pair of spaced parallel sections/one of said sections extending forwardly of the other, and a plurality of fuel supporting elements removably supported at spaced points on said forwardly extending section a substantial portion of said elements being spaced from said forwardly extending section, and the outer edges of said removable elements extending slightly beyond the outer edge of said forwardly disposed section.

2. A furnace tuyere block of the class delscribed, comprising a body portion having an upper section and a lower section spaced therefrom and extending forwardly thereof, said lower section being provided with a series of air passage defining projections on both the upper and lower surfaces thereof, and a plurality of removable fuel supporting elements supported on said projections in spaced relation with the upper surfaceof said lower section.

3. In a device of the class described, the combination of a series of furnace tuyre blocks arranged in stepped relation, interlocking elementsv provided on each tuyere block for securing the same to the next adjacent tuyere block of the series, each tuyere block comprising a body portion having an upper section and a lower section spaced therefrom and extending forward-- ly thereof, a plurality of fuel supporting elements removably supported on said lower section, said lower section being provided with series of projections on both the upper and lower surfaces thereof, the projections provided on the upper surface thereof defining passages between said surface and the lower surface of said removable elements and the projections provided on the '1 lower surface thereof defining air passages between the lower surface of said section and the upper surface of the removable elements of the next lower tuyre block of the series.

4. A furnace tuyere block of the class de scribed, comprising a body portion having an upper section and a lower section spaced therefrom and extending forwardly thereof, said lower section being provided with a series of projections on both the upper and lower surfaces of a forwardly extending portion defining outwardly extending channels thereon, the outer ends of said projections terminating inwardly of the outer edge of said section and a plurality of fuel supporting elements removably supported on the projections provided on the upper surface of said lower section.

5. A furnace tuyere block, comprising a load sustaining body portion of metal having a substantially flat upper section and a substantially flat lower section spaced therefrom and extending forwardly thereof, projections provided on both the upper and lower surfaces of said lower section, and a plurality of highly refractory protective elements supported upon the projections provided on the upper surface of said lower section in spaced relation with said upper surface.

6. A furnace tuyere block of the class described, comprising a body portion having an upper section, and a lower section spaced there-v from, and extending forwardly thereof, a series of projections provided on the upper surface of the forwardly extending portion of said lower section, and a plurality of fuel supporting elements removably supported on said projections in spaced relation with the upper surface of said lower section, said elements having recesses provided in the lower surface thereof into which said projections extend, whereby said elements are held against lateral movement.

7. In a device of the class described, the combination of a row of superimposed tuyere blocks arranged in stepped relation, each tuyere comprising a body portion formed of metal having an upper section and a lower section spaced therefrom, and extending forwardly thereof, and superimposed protective elements formed of a highly refractory material supported upon said lower section, means provided between said elements and said lower section defining passages through which draft air may pass, the upper surface of said elements lying in the same plane as the upper surface of said upper section whereby a smooth surface is provided for supporting the next upper tuyere block of the series and means provided between said surface and the next upper tuyere block of the series defining passages through which air may also pass.

8. In a device of the class described, the combination with a series of .tuyere blocks arranged in stepped relation, each tuyere block having a load sustaining body portion of metal comprising an upper section and a lower section spaced therefrom, said lower section extending forwardly a substantial distance beyond said upper section, means provided in said upper section for receiving locking means provided on the lower surface of the tuyere block next above to retain said tuyere blocks in position, the extended portion of the lower section of each tuyre block having means thereon defining air passages on both the upper and lower surface thereof, and a plurality of protective elements supported on said air passage defining means on the upper surface of said lower section, the upper surface of said protective elements contacting the air passage defining means provided on the lower surface of said lower section of the tuyere block next above for supporting the same.

9. A furnace tuyre block, comprising a body portion of metal, said body portion having a forwardly extending nose portion, a series of projectiom provided on the upper surface of said nose portion, and one or more fuel supporting elements removably supported on said projections in'spaced relation with the upper surface of said nose portion, said elements having means pro-- vided in the lower surfaces thereof for engaging said projections whereby said elements are held against lateral movement.

10. A furnace tuyere block, comprising a bodyportion of metal, said body portion having a forwardly extending nose portion, a series of projections provided on both the upper and lower surfaces of said nose portion, one or more fuel supporting elements removably supported on the projections provided on said upper surface in spaced relation with the latter, said elements having means provided in the lower surfacesthereof for engaging said projections, whereby said elements are held against lateral movement.

12. A tuyre block comprising, a body portion having a pair of spaced parallel sections, one of said sections extending forwardly of the other, and a plurality of removable fuel supporting elements supported at spaced points on said forwardly extending section, a substantial portion of said elements being spaced from said forwardly extending section, and means disposed between said forwardly extending section and said elements defining passages for draft air.

JOSEPH S. BENNETT.

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