US1719416A - Refractory arch for furnaces and method of producing the same - Google Patents

Description

2, 1929. BAlLEY 1.719.416

REFRACTORY ARCH FOR FURNACES AND METHOD OF PRODUCING THE SAME Filed Jan. 17 1922 2 Sheets-Sheet 1 y 1929- E. G. BAILEY 1.719.416

REFRACTORY ARCH FOR FURNACES AND METHOD OF PRODUCING THE SAME Filed Jan. 1'7, 1922 2 Sheets-Sheet 2 1232/5222??? 5m 3 firm-my Patented July 2, 1929.

UNITED STATES PATENT OFFICE.

ERVIN G. BAILEY, OF CLEVELAND HEIGHTS, OHIO, ASSIGNOR, BY ASSIGN- MENTS, TO FULLER LEHIGH COMPANY, A CORPORATION OF DELAWARE.

REFRACTORY ARCH FOR FURNACES AND METHOD OE PRODUCING THE SAME.

Application filed January 17, 1922. Serial No. 529,846.REISSUE This invention relates to a refractory arch or deflecting wall for furnaces, the object being to produce an effective refractory arch at much less cost than that of the arches heretofore used for like purposes, said arch having other advanta es than economy of production which will he readily recognized.

In some types of furnace it is necessary for effective operation that there should be refractory arches to reflect the heat, and thus to intensify the heat at the fuel bed in order to ignite the coal effectively and properly to maintain the ignition.

Such arches as heretofore made have been located in a more or less inclined position above the fuel bed, and have commonly been made of refractory masonry which becomes highly heated and radiates or reflects the heatback upon the fuel bed, but the material of which such arches have been made has but little durability, so that after a relatively short period of service the arches have to be renewed at considerable expense.

It has also-been found that in the operation of tertain types of boilers having water tubes extending'over the top of the combustion chamber and across the path of the gases and products of combustion, there is an ac cumulation of solid refractory material upon the tubes, which comes from the ash or solid residue carried with the gases and in some cases will build thick coatings of ma terial upon the tubes, thus checking the draft and in time involving a stoppage of the service of the boiler until such accumulation can be removed.

I have discovered a method by which the deposit of material from the gases instead of being detrimental and causing costly delays and expenditure of labor for its removal, may be made serviceable, and 1n accordance with the present invention. I provide in the combustion chamber a series of water circulating tubes substantially parallel to one another and extending from the side or end walls of the combustion chamber in the direction required for a refractory arch.

Then when the furnace is set in operation the products of combustion flowing along these tubes will deposit thereon a coating of refractory material which will quickly accumulate and fill the spaces between the tubes so that the coatings on the several tubes will merge into a continuous layer which will become of proper thickness to have the portion facing the fuel bed become highly beau? or incandescent so as to perform the usual function of a refractory arch in maintaining sufficiently high temperature at the fuel bed to promote the ignition of the fuel.

The deposit and the rapidity with which it accumulates varies with coal of different characters and it may be necessary in some cases to use coal of a desired character for a sufficient period to cause the refractory part of the arch to be formed, after which other fuels may be used, or it may in some cases be necessary from time to time to introduce with the coal certain materials of a greater or less fiuxing nature in order to control the char- 7o acter and thickness of the deposit on the tubes.

Fig. 1 shows in longitudinal section a boiler furnace provided with arches which embody the construction, and have been produced by the method, forming the subject of this invention and Fig. 2 is a horizontal section of the same on line X--X Fig. 1.

The boiler proper may be of any suitable or usual construction, it being shown in this instance as comprising a number of water tubes 2 extending from front to rear legs or headers 3, 4, said tubes being in the upper part of the combustion chamber so that the products of combustion rising from the fuel bed on the grate 5 flow through the spaces between said tubes on their way to the uptake 6.

The grate 5 may also be of usual construction, being herein shown as a chain grate upon one end of which the fuel is supplied through a feed chute 7, the fuel being carried along upon the upper stretch of the grate, and the ash being discharged over the rear end of the grate into an ash pit at 8.

It is necessary for efficient operation that a high temperature should be maintained at the end of the grate upon which the fuel is delivered from the chute 7 in order to effect the proper ignition of the fuel as it enters 100 the combustion chamber and for this purpose I it has been customary to build refractory arches in the fire box usually inclining rearward and upward from the front wall of the fire box just above the point of introduction 105 of the fuel, or forward and upward from the rear wall, or both.

In accordance with the present invention, the front and rear water legs 3, 4 of the boiler proper are connected with water boxes or 110 v manifolds 10, 12 near the front and rear ends of the lower part of the combustion chamber,

the said rear water box 12 being connected with the rear legs 4 by a number of pipes 14 through which the cooler water descends in vthe circulatory movement.

shown in'this instance with the front water box 10 by pipes 16 on the outside of the furnace walls.

Said front water box 10 is connected by a series of tubes 20 with the front water legs 3, the said tubes being parallel and quite close together and being inclined rearward and upward from their point of connection with the front water box 10 so that they occupy the position in the fire box desired for a refractory arch to co-operate with the fuel especially near the end at which the fuel is introduced.

From such arch forming part the said tubes extend forwardly and then upwardly to the front water leg 3 and the relation of the several water passages to the furnace is such that the circulation will be downward throu h the pipes 14 and upward through the tu cs 20.

, As shown in this instance another series of arch forming tubes 22 extend from the rear water box 12 to the rear water legs 4, said tubes 22 being more exposed to the heat than the pipes 14 so that an upward circulation will be maintained through the said tubes 22.

These sets of tubes 20, 22 with suitable circulating connections are all that is required in the erection of the apparatus for the production of the arches, which for the rest are produced automatically by the operation of the furnace itself.

The products of combustion rising from the fire carry more or less ash and solid material which upon encountering the sets of tubes 20, 22 will adhere thereto, and as the action continues the material will accumulate until the, accumulation on each tube reaches and merges into the accumulation on the next tube, thus forming a continuous layer which will increase in thickness until there is a sufficient body between the relatively cool tubes and the portion exposed to the fire to cause the latter portion to become highly heated and practically incandescent, so as to produce-the desired effect of promoting the ignition of the fuel as it enters, and maintaining the ignition in the fuel bed.

The character of the refractory coating or layer and the time required for its production will vary somewhat with different kinds of fuel and in some cases it may be necessary to add clay or some other fluxing material, such for example as lime or lime and silica, to the fuel for a time in order to hasten the deposit of the material of the arch.

In some cases it may be necessary at the outset to coat the tubes with a lime wash or some other suitable substance which will insure a more prompt deposit and firmer adherence to the tubes of the solid deposit from the products of combustion.

In case the coal being used has an ash with a low fusing temperature there will be a tendency of the accumulated coating to fuse and flow away, making the material of the arch too thin. In such case it may be desirable to introduce a less fusible material, such for example as fire clay, fragments of fire brick, or alumina, with the coal until the material of the arch accumulates to a suflicient thickncss.

On the other hand, if the refractory layer has an excessively high fusing temperature, it might build to an excessive thickness thus diminishing the space for the passage of the products of combustion to too great an extent. In such event a material fluxing at a lower temperature, such for example as ordinary sand or lime, may be introduced from time to time with the fuel.

.It is obvious that the form and location of the arches may be varied as desired and will naturally be varied according to the judgment of the constructor to meet the requirements of various types of furnaces.

As the products of combustion do not have to pass through the spaces between the arch tubes 20 or 22, said tubes may be located as near together as is found desirable, and with close spacing the coatings starting on the individual tubes will very soon merge into a. continuous layer practically interlocked with the tubes and securely supported thereby.

What I claim is:

1. That improvement in the art or method of making refractory arches for furnaces which consists in installinga series of water circulating tubes in the location desired for the arch, and causing to be deposited thereon a layer of refractory material derived from the solid residue carried by the gaseous products of combustion from the fire.

2. That improvement in the art or method of making refractory arches for furnaces which consists in installing a series of arallel closely spaced water circulating tu es in the location desired for the arch and causing a layer of refractory material to be deposited thereon from the gaseous products of combastion of the fuel and introducing a fiuxing material with the fuel to modify and-control the deposit on the tubes.

3. That improvement in the art ormethod of making refractory arches for furnaces which consists in installing a series of water circulating tubes in the location desired for the arch; coating said tubes with an adhering fluxing material; and accumulating on the tubes a layer of refractory material deposited from the ash of the fuel carried by the gaseous products of combustion of the furnace.

4. The combination with the boiler and furnace of a steam generator, of a refractory defleeting Wall composed of a number of closely spaced parallel Water circulating tubes l0 them, said material being refractory and of the same character as refractory products that are deposited from products of combustion during the operation of said furnace, said material lying for the most part on the side of the plane of said tubes toward the combustion space.

ERVIN G. BAILEY.

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