US1669175A - Refractory furnace grate - Google Patents

Description

1,669,175 R. s. RILEY REFRACTORY FURNACE GRATE May 8, 1928,

Filed May 17, 192

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HTTO NEY MTNESJE-S C a? Patented May s, 1923.

UNITED STATES PATENT OFFICE.

ROBERT SANFORD RILEY, OF WORCESTER, MASSACHUSETTS, ASSIGNOR TO RILEY" STOKER CORPORATION, OF WORCESTER, MASSACHUSETTS, A CORPORATION OF MASSACHUSETTS.

nnrnac'ronv FURNACE cairn.

Application filed May 17, 1924. Serial No. 713,988.

of March 17, 1914, the coal enters the fur nace through retorts or channels, between which are arranged tuyere walls. The coal is fed rearwardly and upwardly through the retorts and piled up above the tuyere walls so that the walls are protected from the intense heat of the furnace by the presence of the green coal which covers them.

If the stoker is improperly operated and the coal bed is permitted to become too shallow in depth or if clinkers form, there may be a localized development of intense heat adjacent the tuyeres and a consequent tendency for the grate parts to burn out or to be otherwise injured by chemical action. The same conditions prevail in an overfeed stoker, or in the overfeed section of an underfeed stroker, so that it is often necessary to replace the grate bars and make repairs to the furnace at frequent intervals. Because of such, difliculties, a stoker has had to be made of a large number of small parts so constructed and arranged that they may be easily removed and re-. placed by new parts, and this necessity for frequently stopping the furnace and replacing burned out parts has involved considerable expense as well as great annoyance to the operator.

It is onepurpose of my invention to overcome this main disadvantage and to provide a stoker construction which. may be easily manufactured and assembled and which will have a long life and not require frequent renewal of burned out parts.

A further object of my invention isto provide a grate block for use in 'overfeed' or underfeed furnaces, which has its nose ortion protected from direct heat radiation y a refractory pla e capa le of withstanding the ordinary temperature conditions of the furnace.

It is a still further object of my invention to provide a combination grate block and tuyere section having a refractory fuel supporting portion which may substituted for parts heretofore used in stoker furnaces of the usual construction and which may be assembled with like blocks to form a grate or a tuyere wall without necessitating any change in the design of the stoker.

With these and other objects in view as will be apparent to one skilled in the art,

my invention resides in the combination of parts described and claimed herein.

Referring to the drawings embodying one phase of my invention and in which like reference numerals indicate like parts:

Fig. 1 is a perspective view of a grate block capable of use in an underfeed stoker;

'Fig. 2 is a cross section on the line 2-2 of Fig. 1; A

Fig. 3 is a sectional view, corresponding with Fig. 2, of a slight modification;

Fig. 4 is a cross sectional view, taken on the line 4-4 of Fig. 1;

Fig. 5 is a cross sectional view corresponding with the view in Fig. 4, of the modification shown in Fig. 3;

Fig. 6 is a fragmentary side elevation showing the side bar with grate blocks an grids mounted thereon;

Fig. 7 is a fragmentary perspective view of a modification of the grate block with the refractory plate removed; and

Fig. 8 is a fragmentary side elevation of high side wall grate blocks embodying my invention.

In accordance with my invention, I propose to provide the grate blocks and tuyere sections of a furnace with a layer of a superrefractory material which will resist high temperatures and oxidation or other detrimental conditions arising from improper firing of the furnace, and for such purpose I may utilize super-refractory materials, such as crystalline aluminum or magnesium oxides or silicon carbide suitably bonded in accordance with well known methods, and in some instances the lesserrefractorv materials utilized in making refractory bricks may be employed. As one embodiment of my invention, I may form a grate block or tuyere section of a metal casting which is protected from the furnace heat by a 1efractory block of ceramic bonded alumina suitably fastened to the casting.

Referring to Figs. 1, 2, 4 and. 6, I have there illustrated one form which this invention may take in which the side bar 10, (Fig. 6.), mounted for reciprocation as described in the patent to Riley, is arranged to carry a plurality of grate blocks thereon. These grate blocks 12 are preferably arranged to overlap one another in a step-hire formation to aid in holding them securely in place, and, as illustrated, comprise essentially a metallic base 12 of suitable shape and construction, to which is fastened a superrefractory plate 14. The base 12 shown in the drawings is made hollow at the rear for the passage of air and comprises walls 15 and 16 connected together by struts 17 and 18 arranged to provide an opening 19 therebetween. A flanged portion 20 extends partway across the top of the opening 19. As shown particularly in Fig. 1, this flange 20 has a depressed portion 21 arranged for the passage of air laterally of the block, and a shoulder 22 is formed with a top in the same plane with the upper part of the flange 20 and the top of the wall 15, in order to form a support for the block above.

As shown in Fig.6,the rear portion is covered by parts arranged above it, and need not be made of refractory material. The forward end of the grate block which would otherwise be exposed to a high temperature is constructed to carry the protecting plate 14 thereon, and preferably is provided with means to lock it in place. One simple way is to dove-tail the parts together, and to this end I may provide the tapered extension or nose 25 of'the iron body, as shown in Fig. 2. with a dove-tailed groove 26 arranged to interlock with a correspondingly formed depending portion 27 on the under side of plate 14 which may he slid into position from the rear. The plate may be suitably shaped, but preferably comprises a portion 28 which has a plane top in the same plane with other plates in the series.

As will be understood, these blocks may be built up into walls located between undert'eed retorts and provision made for permitting air to issue laterally therefrom. In the type of Stoker shown in the Riley patent, the blocks are mounted on the reciprocating side bars 10, and grid sections 30, as shown in Fig. 6. may be employed for tuyere openings. These consist of plates having flanges 31 projecting both upwardly and downward i v therefrom. thereby forming grooves 32. The grid section is arranged to rest on the flanged portion 20, and as will be apparent from an inspection of the drawings, the air groove 26 I provide grooves 34 which form continuations of the passage 33 to the end of the casting, whereby air may issue at the end ofthe plate 14 and thence upwardly between the ends of two adjacent plates which are slightly spaced apart for this purpose. If desired, these grooves 34 may be omitted as indicated in Fig. 1.

If it is considered more practicable to fasten a plurality of refractory plates on a single grate block, then I may utilize the construction shown in Figs. 3 and 5 in which the separate refractory plates 36 are each provided with a dove-tailed portion inter-fitting with the respective grooves 37 in the casting. The grooves 38 may also be provided, as shown in Fig. 5, to serve the same as grooves 34 shown in Fig. 4 for directing air to a position adjacent the ends of the refractory plates.

If it is desired that air issue both laterally and at the ends of the refractory plates, I

may employ the construction shown in Fig. 7 according to which the casting 12 is provided with a depressed portion 40 adjacent the nose end, which communicates with the opening 19 at the rear of the block. The plate 14 is arranged to rest on the raised rim 41 which surrounds three sides of the depression 40, and may be suitably fastened to the casting. Grooves 42 are provided through the nose and the side portions of this rim so that air may pass beneath the refractory plate 14 and issue therethrough into the combustion zone.

In the modification shown in Fig. 8, I have shown the invention as applied to the high side wall of an underfeed stoker, but this construction is of general applicability, as well. The casting 47, which conforms generally to the shape in commercial usage, is made hollow at its rear portion in order to provide an air passage intended to connect with a grid 43 constructed as above described. The forward end of the block 47 is tapered to provide a wedge-shaped portion 44 having an upwardly projecting lug 45. The refractory block or nose plate 46 may beshaped as shown in the drawings, to provide a substantially plane surface 48 which is in the same plane with and serves as a continuation of the similar surfaces of the other plates. These plates are provided with terlock with the projecting lugs 45 on the grooves 49 arranged to fit over and incasting 47, thus holding theni securely in place. The refractory plate may also be fastened positively to its associated casting by a dove-tailed construction such as shown in Fig. 2, or by other suitable means, The rear portion of the plate 46 is bevelled to fit the corresponding surface 44 of the casting so as to liesnugly thereon, and the forward portion of the refractory plate is provided with an upwardly project-ing portion 50 forming a shoulder which aidsiin holding the plates in position.

It will now be understood that with suitable modifications, one may provide the grate blocks and tuyere sections used in various types of furnace with super-refractory nosings or protective coverings in localities exposed to high temperatures or oxidizing conditions and that provision may be made as desired to permit the passage of air upwardly through or around these refractory blocks.

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A suitable composition for such a refractory *block may comprise crystalline alumina grains of suitable size bonded by vitrified clay materials. The refractory ,grains are mixed with a bond of plastic.

vitrifiable ceramic material, such as ball clay, slip clay, flint, and feldspar brought to the desired plasticity with water, and then molded to the desired shape and dried, after which it is fired in a ceramic kiln at Seger Gone 13 or other suitable temperature, which is higher than that to which the ..blocks will ordinarily be subjected in the stoker furnace, to form a vitrified or vitreous mass of the ceramic bond and unite the refractory grains into an integral structure. This method, and the composition of the block, may be varied in accordance with knowledge well known in the ceramic art, and it is to be understod that the refractory granular material may be bonded by other than ceramic material within the scope 'of my invention, and the claims specifying a ceramic bond are to be so interpreted.

It will be obvious that the shapes of the grate blocks and tuyere sections, and the manner of fastening the parts in place, may be changed within wide limits, to meet the particular needs of a furnace construction, without departing from the scope of my invention. \Vhat I have rovided by this invention is a grate blocfi of suitable shape for use in an underfeed or overfeed stoker which is made up of'a base portion of metal protected by a top of super-refractory ma- Having thus described, my invention, what I claim as new and desire to secure by Letters Patent, is:

1. A grate block for a stoker comprising a metal base having a rear portion provided with an air passage therethrough and a forwardly projecting nose having air conduct-. ing grooves therein, and a plate of ceramic bonded refractory granules mounted on said nose and over said grooves to protect the nose from direct heat radiation, said grooves connecting with the air passage and forming tuyere openings.

2. A grate block comprising a substantially step-shaped metal base having a ver tical opening through its rear portion and longitudinal air passages in the nose portion connected with said opening and a plane topped plate of ceramic bonded granular refractory material superimposed on and connected to the nose by interfitting parts which is arranged to protect the nose from direct heat radiation, said block bein shaped and arranged to be piledin a series with like blocks with the plates forming the fuel bed support.

3. A stoker comprising a side bar and a series of grate blocks mounted thereon, each block having ametal base portion removably mounted on the side bar, an imperforate prosage for conducting air from beneath the block to the fuel above.

4. A grate block for a stoker comprising a metal base so constructed that it may be mounted with like blocks on a stoker side bar, a protective'plate of bonded refractory granular material adapted to cover the nose of the base, and means for fastening the plate on the base, said parts being so shaped as to provide an air passage between the base and the plate which terminates in a. tuyere opening for cooling the plate and admitting air to a fuel bed supported on the block.

5. A grate block for a stoker comprising a metal base so constructed that it may be mounted in a series with like blocks on a stoker sidebar, and an imperforate plate of bonded super-refractory material covering the nose of the metal base, said parts haw-ing inter-fitting portions holding the plate in position and a passage which admits air to a fuelbed supported'on the block. 7

6. A grate block for a stoker comprising a metal base having an opening therethrough, an imperforate plate of bonded super-refractory material arranged to protect the base when the blocks are assembled I ed y 1,0 9,175

a tuyere opening to the supported fuel which block to a fuel bed thereon, and said parts communicates with the dpening through the being so constructed and arranged that the 10 base. 7 block may be piled with others in a step- 7. A grate block for a stoker comprising a like formation and the tops of the plates 5 metal base, a plate of bonded refractory' will be substantially in ali nment.

material mounted on and shaped to protect Signed at Vorcester, Massachusetts, this the nose of the base, said block having a 15th day of May, 1924.

passage for admitting air from beneath the ROBERT SANFORD RILEY.

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