US1792638A - Metallurgical furnace - Google Patents

Description

Feb. 17, 1931.

J. HARRINGTON METALLURGICAL FURNACE Filed March 2, 1928 4 Sheets-Sheet 1 Feb. 17, 1931. J. HARRINGTON METALLURGICAL FURNACE Filed March 2, 1928 4 Sheets-Sheet 2 I 1:1II :IIIII Z:I.I

Feb. 17, 1931. J. HARRINGTON 1,792,638

7 METALLURGICAL FURNACE Filed March 2. 1928 4 Sheets-Sheet s Feb. 17, 1931. J. HARRINGTON 1,792,638

- METALLURGICAL FURNACE FiledMarch 2. 1928 4 SheetsSheet 4 with an apparatus for annealing metallic slabs or sheets (Z. This apparatus consists of a furnace A which heats an oven B containing the slabs. The furnace A is fed with fuel by a mechanical stoker C and comprises a back wall a, side walls a and a and a top wall a These walls are made of firebrick and together form a combustion chamber a over the grate bars of the stoker. An ignition arch is formed at the front of the furnace by a longitudinal series of arcuate members a which have their ends disposed and supporter in pockets or sockets a formed in the side walls. A vertical series of tiles a forms a bridge wall or battle device at the rear of the furnace. These tiles are staggered or offset with respect to each other and are supported by an I-beam a which rests upon an integral part of the back walla. The floor upon which the furnace is supported is recessed to form an ash pit a". A passageway (1 is cut in the side wall a adjacent the combustion cham her a. and conducts the products of combustion from the furnace to the annealing oven B. The latter is arranged at one side of the furnace and comprises a back wall 6, a side wall 6, a top wall 6 and a front wall 6 which are made of firebrick and together form a heating chamber 6*. The front wall is'provided with an opening I) through which the slabs or sheets d are inserted into the oven and the back wall Z) has a discharge opening 6. These openings are normally closed by doors 6 Rails Z2 are secured to the floor 5 of the oven and permit the slabs to be slid through the heating chamber by the use of a hydraulically operated mechanism, as well understood in the art. The side wall a of the furnace forms the inner side of the oven. The top wall a embodies an arcuate section a which extends over the rear end of the stoker C and is shaped to direct the products of combustion laterally and into the passageway o. The annealing oven extends rearwardly from said passageway and is provi ded with a valve controlled chimney or outlet duct (not shown).

The stoker C is in the form of a unit which fits into the front end of the furnace and comprises a pair of sides 0, c which are rigidly connected together and are held in spaced relation by cross bars 0 An inclined member 0 extends between the front ends of the sides and forms a hopper. Beneath this member is a horizontally movable plate 0 which feeds the fuel from the hopper to a stepped grate mechanism consisting of a pair of horizontally movable sections 0 and 0 and a pair of sta tionary sections 0 and c which alternate with the movable ones. The sections are each made up of a plurality of grate bars 0 which are suitably spaced apart to form the necessary draft openings therebetween. The plate a has its side margins bent downwardly to form supporting strips 0 which rest upon flanged rollers 0 The latter are individually supported by tracks 0 which are connected to the sides of the stoker and have stop lugs 0 at the ends thereof. The rear end of the plate a is connected to the contiguous end of the section a so that the fuel will be fed directly and said section will be reciprocated by the mechanism that is employed in connection with the plate. The stationary section a is supported at its front end by a block c which is formed of tile or firebrick and is suitably secured to the sides 0 and c. The rear end of section 0 rests upon a girder 0 which is in the form of a cylinder and is secured in place similarly to the block 0 The rear end of the section 0 rests and slides uponthe front end of section 0 while the front end is connected to a transversely extending bar 0 which is secured to the distal ends of a pair of operatinglinks 0 The latter are movably supported upon a pair of flanged rollers 0 which travel on tracks 0 The fixed or stationary section a is supported at its rear end upon the front end of section 0 and at its front end by a bracket 0 which extends between and is secured to the sides of the stoker. The reciprocating action of the movable sections causes the fuel which is usuallycoal to work rearwardly to the end of section a where it falls as ash to a plate 0 The latter is movably supported upon flange rollers 0 and is shifted back and forth so as to cause the ashes to work forwardly and drop into the pit a". The movement of the plate 0 is Very slow so as to permit the ashes to give oif all of their heat. The rollers 0 travel upon tracks 0 which are secured to the sides 0 and 0.

The mechanism for reciprocating the feed plate 0 and the sections 0 and 0 comprises an electric motor 0 which is suitably sup ported in a recess formed at one side of the stoker front; a worm gear 0 which is fixed to the armature shaft of the motor and drives a worm wheel 0 a pinion c fixed to the shaft for the worm wheel; speed reducing gears 0 and 0 which are driven one from the other by an intermediate pinion 0 a crank 0 which is formed on the outer end of the shaft for the gear a; a link 0 which extends between and mechanically connects the crank and the distal end of an arm a; and a rock shaft to which the arm is fixed. The shaft is journalled in bearings 0 and imparts reciprocatory movement to the movable plate and sections through a pair of arms which are fixed thereon. These arms are pivotally secured to the links 0" and are connected to the plate 0* by a pair of links 0 and brackets 0 The gearing is all contained in a housing 0 which is secured to the front end of side a. The ash plate is recipro cated by a rock shaft 0 which is operated by means of a link 0 and an arm 0. The link 0 extends between the crank 0 and the distal able vertically so as to vary the width of the opening through which the fuel passes from the hopper. The gate is suspended by chains 0* which are wrapped around and anchored to a drum 0 This drum is rotated by any suitable means to vary the height of the gate and the latter is protected from the bulk of the fuel by a deflector 0 To increase the capacity of the hopper andadapt it to be loaded from an overhead crane, the front ends of the sides 0, c haveplates 0 bolted thereto and a sheet 0 is provided which operates as a continuation of the inclined member 0 The lower end of this sheet 0 laps the top margin of the inclined member and the upper end is secured to the free ends of a pair of inclined I-beams 0 The latter are connected to a pair of vertically extending I- beams 0 by brackets c. The beams 0 are disposed at the sides of the stoker and fit against the side walls a and aPof the furnace. The lower ends of beams o are embedded in the floor While a cross bar 0 joins together the upper ends. Inclined braces c extend between the I-beams 0 and I the vertical beams and are connected thereto by brackets 0 l The front of the stoker is formed by three vertically aligned cross members 0 0 and 0 which are spaced apart and form a draft opening 0 and an opening 0 through which the ashes may be remo-v d from the pit a These openings are closed respectively by a pair of doors 0 and a. A partition plate 0 divides the space below the grate sections into a draft chamber 0 and an ash chamber 0 This partition is connected at its rear end to the cylindrical girder 0 and at its front end to the cross member 0 A pair of draft openings 0 and 0 are formed in the side 0 of the stoker. These openings are disposed beneath the grate sections a and 0 respectively and are controlled by dampers a. A draft is created in the furnace by forcing air under pressure into the draft chamber 0. This is accomplished by means of a fan 10 and a conduit 0 which extends between the exhaust opening 11 of the fan and the openings 0 and 07 The conduit is supported from the side 0 by brackets 0 and is partly confined in a seen-cylindrical socket e which is formed in the side wall a. The fan is driven by an electric motor 12 and'comprises aplurahty of radially extending blades 13 and a casing 14. The space between the sides ofthe stoker and the side walls a and a is filled with plastic firebrick to prevent the hot gases from escaping into the room in which the furnace is disposed.

As previously pointed out, it is essential in the operation .of'furnaces of this character to exclude air from the heating chamber Z) in which the slabs (Z are disposed because such air entering'through the charging and discharge openings and b instantly becomes highly heated and when'circulated or wafted into contact with the slabs causes a scaling or oxidation of the metal and results in injury to the product and considerable waste.

To insure the exclusion of air, the fan 10 is of such a character as to create a draft which is sufficient in magnitude to build up the necessary pressure within the furnace and oven to prevent :itl eventry of the surrounding air. when the doors 6 are opened for the insertion and removal of the slabsi In practice the fan is rotated and the dampers 0 are arranged sothat the draft will create a pressure in the heating chamber 6 which is substantiall greater than that of the surrounding atmosphere. Thus when the doors 6 are opened there is an actual escape of the gases and flame from the oven instead of an infiltration of the surrounding air. Because there is a restriction to the passage of the 'ases through the passageway a, it is manirest that the'pressure of the gases in, the combustion chamber a will be greater than that of the gases in the heating chamber 5 This comparatively high pressure operates to force the hot and deleterious gases from the combustion chamber through the interstices of the brickwork, the fuel hopper, and the unclosed parts of the draft opening 0 with the result that the operating mechanism for the grate sections and the tile or outer brickwork are injured by the hot gases, and the air 111 which the operatives work is poisoned and polluted.

To prevent the infiltration or escape of these obnoxious and deleterious furnace gases the front portions of the furnace and the stoker are enclosed in an air tight structure comprising a front 15, side walls 16 and 17, and a top 18 which are formed of sheet metal sections. The contiguous margins of the sections that form each of the sides are secured to the web of a vertically extending channel iron beam 19. The beams 19 have their lower ends embedded in the floor and operate to strengthen and support the sides. The rear margins of the rearmost of the side sections are securedby angle iron brackets 20 to a pair of vertically extending I-beams 21 which are arranged adjacent the sides of the beams 0 in the floor. The sheet metal sections which form the front 15 are joined with the foremost sections of the sides by angle iron beams 22 and are spaced apart to form an opening 23 whereby the operatives may gain entrance to the enclosing structure. This opening is closed by asheet metal air-tight door 24: which is supported by hinges at one side thereof. The upper parts 25 of the rearmost side sections are extended and shaped to fit against the I-beams 0 and the latter have a sheet metal plate 26 extending thereacross. This plate has an opening 27 formed therein through which the fuel may be dumped into the hopper and its extension. The opening 27 is normally closed by an air tight door 28 which is hinged at its rear end so that it may be lifted into its open position. A sheet metal section 29 closes the space between the standards or I-beams 21 and the upper margin thereof is connected in any suitable manner to the contiguous margin of the plate 26 so as to completely enclose the exposed parts of the stoker and the front of the furnace. The joints between the sections of the supporting elements are hermetically sealedv in any suitable manner to render the structure air-tight.

The fan 10 is housed within the enclosing structure and the inlet 30 therefor projects through an opening 31 in one of the sheet metal sections of the side wall 16 so as to be supplied with air from the room. The fan casing let is provided with an additional exhaust opening 32 which delivers air under pressure into the structure. Since the openings c and e are restricted because of the dampers there is a back pressure in the conduit 0 which causes the air delivered into the structure to create a pressure in excess of that of the gases in the furnace. As a result of this arrangement there is a tend ency for the air to pass inwardly or into the furnace and thus the poisonous and deleterious gases are prevented from escaping into the room and into contact with the stoker operating mechanism. In actual practice it has been found that when the pressure built up within the enclosing structure is equal to about one-half inch of water column, the best results are obtainable. A slide valve 33 is 1 .ovide to control the exhaust opening 32. This valve together with the dampers 0 permits the external and internal pressures to be built up in accordance with actual requirements. While the air pressure in the enclosing structure is reduced when either the fuel door 28 or the door 24; is opened, the fan 10 is preferably of such a capacity as to restore quickly the proper or original pressure.

Since the enclosing structure is made up of sheet metal sections and angle and channel beams it may be fabricated at the factory and shipped in knock-down form to the place of installation where it may be quickly and readily assembled.

The invention is not to be understood as restricted to the details set forth, since these may be modified within the scope of the ap pended claims, Without departing from the spirit and scope of the invention.

Having thus described the invention, what I claim as new and desire to secure by Letters Patent, is:

1. In combination, a furnace substantially surrounded by air under atmospheric pressure and provided with a fuel opening in the front thereof and a combustion chamber communicating with the opening and adapted to have pressure developed therein,a housing structure built onto and connected directly to the front of the furnace and forming an airtight chamber around the fuel opening, and means for supplying air to said last mentioned chamber under sufficient pressure to prevent'the escape of gases from the combustion chamber through said opening.

2. In combination, a furnace provided with an opening and embodying a combustion chamber adapted to have pressure developed therein; a mechanical stoker device for automatically feeding coal to the furnace, said device extending through the opening and having operating parts disposed outside of the furnace, a structure forming a substantially air-tight chamber adjacent the opening and around the exterior parts of the stoker device, an d means for supplying air to said last mentioned chamber under suificient pressure to prevent the escape of gases from the combustion chamber through said opening and around the said exterior stoker parts.

3. In combination, an annealing oven having a heating chamber therein and surrounded by air under atmospheric pressure, a furnace provided with a fuel opening and embodying a combustion chamber communicating with the annealing oven, means for supplying air under pressure to the combustion chamber of the furnace in such quantity that pressure is developed in the heating chamber sufiicient to exclude the surrounding air when the oven is opened for charging or discharging purposes, means forming a substantially air-tight chamber around the fuel opening, and means for supplying air under pressure to said last mentioned chamber under suiiicient pressure to prevent the escape of gases from the combustion chamber of the furnace through the fuel opening.

t. In combination, a furnace provided at he front end thereof with means forming an opening through which fuel may be fed, an annealing oven associated with the furnace, means forming a conduit between the heating chamber of the oven and the combustion chamber of the furnace, means for developing a pressure in said chambers greater than that of the surrounding air, a structure enclosing the front end of the furnace only and forming an airtight chamber adjacent the portion of the furnace having the fuel opening, and means for supplying air to said last mentioned chamber under sufficient pressure to prevent the escape of gases from the combustion chamber tl'irough said opening,

5. In combination, a furnace provided with an opening and embodying a combustion chamber adapted to have pressure developed therein, a device for mechanically feeding fuel to the furnace extending through said opening and comprising a grate system and a hopper for feeding fuel to said system, the hopper being disposed on the outside of the furnace, a structure forming a substantially air-tight chamber around the hopper, and means for supplying air to said last mentioned chamber under sufficient pressure to prevent the escape of gases from the combus tion chamber through the hopper.

6. In combination, a furnace provided with an opening and embodying a combustion chamber adapted to have pressure developed therein, a device for mechanically feeding fuel to the furnace extending through the opening and comprising a grate system and a hopper for feeding fuel to the system, said hopper being disposed on the outside of the furnace, a structure forming an air-tight chamber around the hopper, and means for supplying air to said last mentioned chamber under sufficient pressure to prevent the escape of gases from the combustion chamber through the hopper, said structure having a door therein adjacentsaid hopper.

7. In combination, a furnace provided with fuel and ash openings in the front thereof and embodying a combustion chamber, a grate system in the furnace arranged to form an ash chamber therebelow, a fan disposed on the outside of the furnace and connected to deliver air under pressure to the ash chamher so as to develop a pressure in the combustion chamber, a structure built onto and connected to the furnace forming a substantially air-tight chamber around the fuel and ash openings, and means for supplying air to said last mentioned chamber under suflicient pres sure to prevent the escape of gases from the combustion chamber through said openings.

to prevent the escape of gases from the combustion chamber through said opening.

Signed at Chicago, Illinois, this 25th day of February, 1928. p

, JOSEPH HARRINGTON.

8. In combination, a furnace provided with fuel and ash openings and embodying a combustion chamber, a grate system in the furnace arranged to form an ash chambertherebelow, a fan disposed on the outside of the furnace and connected to deliver air under pressure to the ash chamber so as to develop a pressure in the combustion chamber, and a structure forming a substantially air-tight chamber around the fuel and ash openings, said fan having a manually controlled outlet for supplying air under pressure to said air- 7 tight chamber.

9. In combination, a'furnace provided with

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