US1832371A - Burner for furnaces - Google Patents

Description

Patented Nov. 17, 1931 UNITED STATES lPATENT OFFICE t JOHN D. EVANS AND ELMER E. MCVEY, OF YOUNGSTOWN, AND THOMAS E. MCALLISTER,

OF GIRARD, OHIO, ASSIGNORS T0 SURFACE COMBUSTION CORPORATION, 0F TOLEDO,

OHIO, A CORPORATION OF NEW YORK BURNER. non FURNACEs Application filed August 15, 1929. ,Serial No. 386,135.

Our invention relates to new and useful improvements in burner for metallurgical and other furnaces, such, for example, as the normalizing furnaces, annealing furnaces and the like ordinarily used in the iron and steel industries.

As will be understood by those familiar with the art, such furnaces are ordinarily constructed of brick and provided with a plurality of tunnels at spaced intervals in their walls through which suitably disposed burners inject highly combustible mixtures of air and the desired fuel, such as gas, oil and the like which is supplied to the burners by pipesextending along the furnace or in any other suitable way. rlhe burners are ordinarily maintained in registry with the tunnels by being bolted to steel plates fastened to the outer walls of the furnace in such manner as to exclude air from the tunnels except as admitted through the burners, and the tunnels are lined with a special refractory tunnel cement which is built up in the tunnel from the inside of the furnace after the burner is installed so as to make an air-tight joint between the tunnel and the nozzle of the burner and form a substantially cylindrical passageway to conduct the combustiblemixture from the burner into theifurnace. Inasmuch as the tunnel lining is thus in direct contact with both the burner and the brick wall of the furnace, it is obvious that any relative Inovement between the latter and the burner will result ina strain upon the tunnel lining. In practice, therefore, as the expansion and contraction of the furnace wall, tunnel lining and steel plate supporting the burner are frequently unequal in a furnace constructed as described, a fracture of the tunnel lining often occurs with the result that air is admitted into the' tunnel otherwise than through the burner with consequent back firing or combustion of the fuel within the tunnel` which subjects the burner to excessive heat which frequently burns out or otherwise injures it. Moreover, the air so admitted. impairs -the effectiveness of the fuel in heating the interior of the furnace, increases the' difficulty of maintaining a constant temperature therein and brings about undersirable oxidation of the charge in the furnace.

Another-disadvantage of furn aces equipped with burner tunnels o f the ordinary type resides in the fact that when replacement of a burner is required for any reason, the furnace must be shut down and allowed to cool sufficiently to permit a workman to enter it and build up the tunnel lining with fresh cement against the burner nozzle after the new burner has been placed in position adjacent the outer end of the tunnel. Thus repair of the tunnel or replacement of the burner results in keeping the furnace out of operation for many hours with consequent loss of productive time and frequently of heat and fuel. Additionally, both the burners and the tunnel cement are very expensive so that damage to the one from the airleakage,to whichwe have referred, and expenditure of large amounts of the other in repairing and rebuilding the tunnels also contribute materially to the cost of furnace operation.

To overcome these and other disadvantages of burners of the class described, our invention contempla-tes the provision of a burner comprising a rigid metallic casing, within which the tunnel cement lining may be built up, adapted both to support the burner and to fit snugly within an aperture provided therefor in the wall of the furnace; thus the liningis protected from cracking resulting from the expansion or contraction of the furnace, for inasmuch as our tunnel housing -supports both the lining yand the burner and maintains them in proper engagement, relative movement between the burner and th lining is substantially prevented.

Other purposes, objects, advantages and novel features of construction and arrangement comprehended by our invention will appear from the following description of a preferred embodiment thereof as shown in the accompanying drawings in which Fig. l is a' vertical section through the tunnel operatively disposed in a furnace wall, a burner of the ordinarytype being shown partially in side elevation and partially broken away into section in association therewith; Fig. 2 is an end elevation of the tunnel removed v which is desirably of iron or steel or an' alloy thereof or other suitable metal; this housin is adapted to seat in a suitableaperture extending through the furnace wall W, the fit between the housin and the wall of the aperture being desira ly rather close although an absolutely air-tight fit is not essential as the admission of a small quantity of air into the furnace between the housing and the aperture wall does not appreciably affect the o eration of the furnace. The

housing is esirably of rectangular crosssection as we have found this form more especiall adapted to installation in furnaces built o rectangular brick which readily lends itself to the formation of the apertures 25 A of similar cross section so that the housing can be conveniently built into the furnace wall during the construction of the latter;`

it will nevertheless be understood that the housing may be of any other desired cross sectional form such as cylindrical or otherwise if preferred.

The outer end of the housing is closed by an end plate 2 save at its center where the plate is provided with an opening 3 for the reception of the air nozzle 5 of the burner, generally, desi ated as B, this nozzle as shown bein o the customary conical form and provi ed with an integral ian e 6 adapted to seat against the outer face o the housin end plate to which it is removably secure by ca screws 7 extendingthrough the flan e an through internally threaded holes 8 1n the end plate. To afford an adequate bearing for the ends of the screws and enhance the rigidity of the burner structure as a whole, relnforcing lugs 9 are desirably provided in the corners of the tunnel housing adjacent, the inner face of the end plate, as most clearly shown in Fig. 2, and the holes 8 extended thereinto.

The air nozzle of the burner projects some what within the housing when secured in position thereon as'above described and is provided with a central opening 10 through which the air and gas are introduced into the' tunnel. The lining 12 of the latter may be Constructed of fire bricks faced with tunnel cement or entirely of tunnel cement and may be built ullwithin the housing either prior to or after t e latter. is positioned in' the furnace wall. The lining is closely acked within the housin and at its outer en takes the form of thead] acent burner nozzle so that 'intimate contact is effected between the latter and the lining, while from the opening 10 Aof the gases during their passage therethrough from the burner to the furnace.

It will thusbe apparent that the outer extremity of the tunnel passage 13 is formed in correspondence with the shape of the air nozzle so as to effect a snug fit between these parts and while we have shown said nozzle of substantially conical form it will be understood that nozzles of other forms may be used if desired and the tunnel lining correspondingly shaped for intimate engagement therewith.

After the tunnel is assembled in the furnace wall and the burner operatively secured in position on its end plate as above described, it will be apparent that the flange or face plate of the air nozzle is maintained in intimate engagement with the housing and the nozzle proper in like engagement with the tunnel lining so that a substantially air-tight connection between the parts Ais effected to prevent admission of air to theitunnel exceptthrough the burner itself; it is therefore unnecessary that tunnel cement or other materials be employed to pack' or seal the joint between the nozzle Han e and the tunnel housing or between the nozz e and the lining itself while inasmuch as the gas and air suplply means is supported on t e `structure which carries the tunnel lining, any expan sion or contraction of the furnace walls cannot effect relative movement between the various parts of the burner apparatus; moreover, as the housing is of suiiicient stren h and rigidity to protect the lining from ot er causes of fracture, such as transverse expansion of the' wall, for example, the tunnel lining will ordinarily-require replacement only when it becomes Worn out as a result of the passage of the fuel stream therethrough. As substantially no airis admitted to the burner tunnel from without the furnace except through the burner itself, it is obvious that back firing from infiltrated air in the tunnel is prevented and thus the burner i's protected from excessive. heat and its life therefore greatl increased, while undesirable oxidation o the charge is obviated.

As the cap screws which normally hold the burner in position on the tunnel may be readily reached from the outside of the furnace, a defective burner may be easily removed and replaced with a new one at any time and even while the furnace is in operation with- 13o out seriously aflecting the interna-l temperature of the latter'since the amount of air which can enter the furnace through the opening in the end plate of the tunnel while theburner is being changed has but relatively little effect upon the fsurnace temperature, or, at most, an effect which may be readily compensated for by suitable adjustment 0f the fuel and air supply from the other burners. Set to discharge through the opening 10 in the air nozzle 5 is a gas nozzle 15 to which gas is supplied by a gas supply pipe 16 of which the nozzle 15 forms in e'ect a. continuation. Air for mixing with the gas dischargedfrom nozzle 15 is admitted into the air nozzle 5 by a suitable shutter 17.

As hitherto pointed out it is entirely unnecessary for any one to enter the furnace in connection with a change or replacement of the burner or to replace or repair the tunnel lining under ordinary conditions of operation throughout its normal life, so that by the use of our invention the delays incident to repair and replacement of cracked tunnel linings or for building up new linings after a change of burners with consequent necessity for cooling the furnace to enable an operator to enter thelsame for the purpose are entirely avoided. Moreover, through the elimination of cracked tunnel linings with resultant admission of infiltrated air to ythe tunnels and consequent injury to the burners, the life of the latter is materially prolonged by the use of our invention, so that the expense for burners is correspondingly lessened as well as that for the costly tunnel cement itself, while in most instances the expense of installing our improved burn-ers in furnaces is less than that of building up the tunnel linings therein in the manner hitherto practiced as the housings of our improved furnace tunnels may be readily lined before being placed in position and integrally built into the walls of the furnace after which they tunnel arranged for operative combination with various .forms of burners without departing from the spirit and scope of the invention as defined in the appended claim.

Having -thus described our invention, we claim and desire to protect by Letters Patent of the United States:

Apparatus for forming and burning an explosive gaseous mixture comprising a refractory tunnel internally restricted opposite its discharge end to form a mixing throat, a metal housing for the tunnel coextensive in length therewith and provided at one end with an inwardly projecting apertured wall against which one end of the tunnel abuts, an air nozzle extending through the aperture in said Wall and provided with a flange for abutting said Wall, a gas nozzle set to discharge into said tunnel through said air nozzle, the nozzles being in concentrically spaced relation, and means for controlling the admission of air into said air nozzle.

In witness whereof we have hereunto set our hands this 13th day of August, 1929.

JOHN'D, EVANS. ELMER E. MCVEY. THOMAS E. MCALLISTER.

usually require no further attention during their normal life.

We have thus provided a burner which is generally cheaper to install and to maintain and which has a longer life than the forms of burner heretofore employed; which increases the life of the burners through elimination of back ring and overheating, and which avoids the. necessity of shutting down and cooling off the furnace when burner replacenient is required, so that by the use of our invention operation costs are reduced and production materially increased over those of furnaces of equal capacity employing burners heretofore in common use.

While we have herein described a preferred form of our invention with considerable particularity, we do not thereby desire or intend to specifically confine ourselves thereto as changes and modifications may be made in the design and construction thereof and the

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