US2209762A - Insulated enclosure - Google Patents

Description

S. BRACKEN July 30, 1940.

l t e e h S s t e e h S in M8 3 W9 01 9 m m u J Md e FURNACE INVENTO STANLEY BRAIEKEN A ORNEY.

July 30, 1 s. BRACKEN INSULATED ENCLOSURE Filed June 9, 1938 2 Sheets-Sheet 2 l I l III I 5 Q 5 mm INVENTOR. STANLEY BRACKEN A RNEY.

Patented July 30, 1940 UNITED STATES PATENT OFFLCE INSULATED ENCLOSURE of Delaware Application June 9, 1938, Serial No. 212,671

3 Claims.

The present invention relates to protective enclosures and more particularly to insulated enclosures for use with heat treating furnaces.

Heat treating baths may contain cyanide salts heated to a temperature of between 1500 to- 1650 degrees F. at which the salts are in a molten state producing fumes which, though non-poisonous, may constitute nevertheless a health hazard because of the possible irritation which they may cause to the nasal and throat membranes. In addition, molten baths of the indicated temperatures are exceedingly dangerous when parts to be treated contain even slight quantities of moisture. The sudden transformation of the moisture into steam is accompanied by explosion causing the molten salts to be ejected forcibly sometimes to considerable distances from the furnace.

Heated gases emanating from heat treating or carburizing furnaces are lighter than the surrounding atmosphere and therefore tend to rise so that accordingly it has frequently been the custom to employ overhead exhausting fiues. As a result, the overhead atmosphere became unduly heated, while in rooms occupied by a plurality of furnaces the overhead area was congested by the presence of main and branch exhausting flues.

To overcome the noted objectionable features incident to the operation of heat treating furnaces, it is the main object of the present invention to provide a practical and most efficient unitary enclosure housing for affording maximum protection.

Another object of this invention is to provide in such a unitary enclosure, means for drawing off heated fumes under conditions so as to maintain at a minimum any tendencies either through conduction or radiation toward heating of the surrounding atmosphere.

The present invention contemplates a unitary enclosure which envelops the furnaces and is provided with apertures only sufficiently large to afford accessibility to each furnace and for such other purposes as are essential to their maintenance and operation. Important practical and safety advantages have been obtained from this practice which have been found to reside not only in the provision of a single unit space within which all of the heated gases emanating from the furnaces may be confined, but also by making the enclosure in accordance with certain principles the heated gases are drawn off in a rearward and downward direction obtaining thereby a very efficient confinement of the excessive temperatures which heretofore by radiation or conduction have permitted the surrounding area to become intensely and objectionably heated.

Specifically, the invention proposes a single '5 housing of sheet metal lined with refractory and heat insulating material whose front wall is made up of sectional panels fitted to abut the front Walls of an aligned plurality of heat treating furnaces. Above each furnace there is provided an opening large enough to permit an attendant to load and remove charges. The rear wall has openings to admit copper electrode bus bars and to afford accessibility to the terminal bolts for replacement or repair purposes. An exhaust tube extends longitudinally of the furnace and in it are openings, one over each furnace. A main conduit communicating with the tube extends downwardly and rearwardly connecting with an exhaust fan or other suitable outlet.

For a more comprehensive understanding of the present invention reference may be had to the accompanying drawings and to the specification following in which like reference characters designate corresponding parts through- 25 out and in which:

Fig. 1 is a perspective view of an insulated enclosure adapted to be used with three conventional types of heat treating furnaces,

Fig. 2 is a transverse sectional view through a structure corresponding to that illustrated in Fig. 1 and taken on line 2-2 of Fig. 3 having a portion of the downwardly and outwardly extending fines broken away,

Fig. 3 is a plan sectional view taken approximately on line 33 of Fig. 2, and,

Fig. l is a detailed perspective view of a portion of the wall section indicating a manner in which the insulation may be built up and supporting material therefor.

The reference characters II, it, and I3 respectively, denote the side walls and back walls of a metallic enclosure which are fitted together and on which is applied a curved top M, Fig. 2, by means of welding or riveting as is conventional in sheet metal practice. The front of the enclosure is fabricated from a plurality of sections indicated l5, l6, H, and [8. Other panels I9, 25, and 22 serve also as supports for the timing or controlling apparatus which include clock indexes 723 and control switch panels 24. The front panels if and I6 are preferably removable and are therefore reinforced by means of the perimetrically applied angles 25. Other sections of the housing front are made up of the front Sides 26 of the furnace units themselves.

The openings 21, 28, and 29 through which there is afforded accessibility to each of the furnace units respectively are so proportioned with respect to height and width as to provide ample freedom to the individual attendants, while protecting adjacent attendants or other from the possible hazards incident to the work. The upper portion of each of these openings is covered by an apron 30 which confines to a proper extent the ceiling gases beneath the arched roof I4. Consequently, none of the fumes is permitted to escape the influence of the exhausting duct 33 to be described later.

To illustrate certain of the difficulties which have been overcome by the present improvement, attention is directed to Fig. 2 where the reference character 3| denotes in solid and broken lines, respectively, the positions which may :be assumed by any one of the furnace covers. In the full line'position, a cover 3| is illustrated as overlying the furnace opening or hearth but in the dotted outline position (Fig. 2) the same cover is moved back into a, position which it occupies during the time when a furnace is in use. Furnace covers such as these are deemed necessary for economy and safety in operation, and in developing the present unitary enclosure, special features have been incorporated to make the manipulation of the furnace covers 3| from the front openings 27, 28, and 29, a function of ease and convenience and one not involving additional hazard by reason of the interposition of the protective housing.

Each furnace cover 3| is preferably supported at its sides upon. a pair of rails 52 upon which rest the guide rollers 5| secured to the side wings 53 of the covers 3|. Also, each cover is provided with a handle and eyelets or loops 50 into which may be inserted a hook for operating, i. e. moving, the cover between its respective positions.

v The depth of the enclosure, which corresponds to the width of either of the side walls H .or I2, is sufficient to accommodate the furnace with its cover 3| in the receded (dotted outline Fig. 2) position. Also, the front panel sections 9, 2|, and 22 are undercut as at 32 affording to each of these panel sections adequate protection by way of fire and heat resistant material so as to safeguard the timing devices 23, while permitting the covers 3| to be moved forward as far as is necessary to cover their respective furnace units 26.

' At the upper left-hand corner of the enclosure as viewed in Fig. 2 and extending longitudinally above the spaces occupied by said covers 3| when in their receded position (dotted) is an exhaust duct 33. In substantial alignment with the center of each furnace, the duct 33 is provided with flared openings 34 through which the heated gases rising above each furnace may be withdrawn. The duct 33 communicates with a vertical section 35, Figs. 2 and 3, which extends down- Wardly at the rear of the enclosure and between two of the furnaces to an elbow portion 36, then horizontally through a section 31 which in turn may communicate with any suitable exhaust outlet, such as a draft chimney or fan driven exhaust means, depending upon the particular requirement of volume displacement.

The exterior surface of duct 33 is preferably covered with insulating material 44 and 4'! as will be more fully described later, while that portion of the fiue which extends outside the housing, for example, section 31, has its interior surface correspondingly lined. The covering is to protect the metallic structure, while thelatter, in addition, also assists in maintaining at a minimum the temperature of the flue housing 38 which protrudes from the unit.

Heat treating furnaces of the type herein contemplated are preferably operated electrically, and in the instant embodiment the bath salts are heated electrothermally by the use of low voltage supplied through electrodes which are immersed in the bath and to which the current is conducted by means of heavy copper bus bars 4| as may be seen in Figs. 2 and 3. Consistent with this practice the housing rear wall l3 is provided with framed apertures 39 having sufficient clearance not only for admitting the bus bars 4| but also to permit a substantial quantity of lowerlevel, and therefore cooler, air to enter into the housing chamber for effectively cooling the bus bars 4|.

Another set of openings 42 is located one above each of the aforedescribed bus :bar openings 39. The openings 42, however, are primarily for affording accessibility upon occasions of cleaning or repair. Under all other circumstances, therefore, these openings 42 are closed by the individual closure doors 43, suitable means being provided for holding the doors 43 securely sealed.

The entire inner surface of the housing as well as that of the protruding portion of the flue 31 is lined with a heat insulating covering as indicated in Fig. 4, built up of block sections 44 of a high efficiency cellular insulating material. The blocks 44 may be cemented together, and in addition, secured, as by means of stay bolts 45, to the metallic wall section. To the inner surface of the built up wall section is then applied a wire mesh anchor material such as poultry netting 46. This may be secured to the stay bolts 45 to afford a key or lathing for refractory finishing cement or fire clay 4'! which is troweled on to cover the entire surface including the poultry netting and the stay bolts 45.

Behind each furnace unit and resting on the floor is an individual step-down transformer unit 43, Fig. 3, by which available current is transformed to meet the furnace requirements. Each furnace including its transformer is individually accessible for purposes of 'periodic check and repair. The removal of an entire furnace unit, or repair of its transformer or bus bars 4| is easily and conveniently obtained without interference by or to any of the remaining units. It will be observed that each of the furnaces Z6 rests on the floor level and that its movement forward is restrained only by one or the other of the panels I! or l8. Accordingly, to remove one of the furnaces 26 it is proposed that an adjacent panel either H or l8 be first removed by unbolting or unscrewing from its adjacent panels and floor securement following which the front plate of the corresponding furnace may be removed, affording a clearance for inserting thereunder suitable hoisting or lifting jacks.

By maintaining in readiness a utility furnace to replace the one which is removed, it has been found that the changeover including the removal of a furnace to be repaired and the reinstallation of a utility furnace may, by means of the present design, be completed within a much shorter time than was heretofore found necessary in other types of unitary enclosures.

While the present invention has been described with contemplation of a specific embodiment it is to be understood that numerous changes and variations may be made Within the spirit or scope thereof. The invention is not to be confined except as indicated by the hereunto appended claims.

What isclaimed is:

1. A unitary enclosure for multiple furnaces comprising, in combination, a rectangular housing having integral side, top, and back wall elements, the front wall comprised of the front faces of said multiple furnaces arranged in parallel alignment, removable panel sections intervening the front faces of said furnaces, rigid sectional elements defining openings for aifording accessibility to each of said furnaces and in contiguous abutment with the faces of said furnaces and said removable panels, and means for exhausting the area within said enclosure including a flue extending rearwardly therefrom.

2. In a unitary housing for enveloping multiples of heat generating devices, rigid rear and side wall sections secured at right angular abutments, an arched top Wall section secured to said side and rear walls rigidly, and a composite front wall section comprised of the front face portions of a plurality of heat generating devices arranged in a plane alignment, vertical abutting sectional panels connecting said heating devices and of height equal to said devices, instrument supporting panels rigidly secured above said vertical panels, said panels defining an opening for accessibility above each of said heat generating devices, a bafiie apron extending over each of said openings for barring the escape of ceiling gases thereat, an exhaust duct contained in said housing at the rear thereof in communication with said heat generating devices, and means for conducting gases from said duct.

3. A furnace enveloping structure including, in combination, a rectangular housing having an arched roof section, a front wall having openings for receiving therein rectangular heating devices the front walls of which supplement the front wall of the housing and close the lower portions of said openings, leaving sufiicient clearance above each heating device to afford accessibility thereto, a rear wall having openings therein with certain of said openings disposed at a relatively lower and therefore cooler plane and through which extend electric current conducting buses to said devices and other openings with removable closure members therefore for affording accessibility for the repair and maintenance of said current conducting buses and devices, a vapor conducting duct adjacent to said rear wall and in communication with the atmosphere above each of said heating devices, and vapor exhausting means connected to said duct.

STANLEY BRACKEN.

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