US1768865A

US1768865A - Heating-element-mounting construction

Info

Publication number: US1768865A
Application number: US279810A
Authority: US
Inventors: Edwin L Smalley
Original assignee: Hevi Duty Electric Co
Current assignee: Hevi Duty Electric Co
Priority date: 1928-05-22
Filing date: 1928-05-22
Publication date: 1930-07-01
Anticipated expiration: 1947-07-01

Description

3 Sheets-Sheet l E. L. SMALLEY Filed May 22, 1928 ATTORNEY mf, L

July l, 1930.

HEATING ELEMENT MOUNTING CONSTRUCTION July 1, 1930. y E. L. SMALLEY 1,768,865

HEATING ELEMENT MOUNTING CONSTRUCTION Filed May 22, 1928 3 Sheets-Shea?I 2 IN V EN TOR.

A TTORNEY July l, 1930. E. L, sMALLEY HEATING ELEMENT MOUNTING CONSTRUCTION Filed May 22 1928 3 Sheets-Sheet 5 u n n INVENTOR. Edwin )1522251 Q/ yBY A TTORNEY Patented July 1, 1930 UNITED- STATES PATENT OFFICE EDWIN L. SMALLEY, OF WHITEFIS BAY, WISCONSIN', ASSIGNOR TO HEVI DUTY ELECTRIC COMPANY, OF MILWAUKEE, WISCONSIN, A CORPORATION OF WISCONSIN' HEATING-ELEMENT-MOUNTING CONSTRUCTION Application led lay 22',

an electric furnace structure.

Another object of my invention is to provide a construction of lightweight ceramic material for installation within a furnace chamber for mounting heater elements therein in a manner whereby the speed of heating from cold to operating temperature ma be increased.

nother object of my invention is to provide, a construction of heater .element support which will prevent foreign particles such as iron oxide from lodging back of the projecting flanges on the head of the heater element support in an electric furnace chamber construction.

Still another object of my invention is to rovide a preformed ceramic refractory or installation in a cylindrical vertical electric furnace in a manner whereby the coils and reflecting plates are held in self-supporting positlon.

A further object of my invention is to provide a means of supporting a heating coil with its corrugated reflecting plate against a flat faced wall which permits of the use of heat insulating material in moldl ed shapes and avoids the usual fire-brick lining.

A still further object of my invention is to provide a construction of heater element mounting for maintaining a heater element adjacent the interior walls of a furnace chamber in a manner in. which direct radiation of heat from the turns of the heater element is not impeded.v

My invention will be more fully understood by referring to the following specification and the accompanying drawings in which; y

Figure 1 illustrates a fragmentary crosssectional view taken through an electric fur- 1928. Serial No. 279,810.

nace embodying the principles of my invention; Fi 2 is an enlarged elevational view looking 1n the direction of line 2-2 in Figure l, showin the resistors and the mounting thereof wlthin an electric furnace in accordance with my invention; Fig. 3 is a cross-sectional view through the furnace wall showing one method of mounting the heating elements with respect thereto; Fig. 4 is a front View of the heating elements illustrated in Fig. 3; Fig. 5 is a front view of one section of the refractory which serves to support the heating elements with respect to the furnace wall; Fig. 6 shows a crosssectional view through the refractory in line 6-6 of Fig. 5; Fig. 7 ilustrates a cross-sectional view through the refractory on line 7-7 of Fig. 5; Fig. 8 illustrates the arrangement of the heating elements within a circular furnace chamber where the heating elements are formed in accordance with the principles of my invention and Fig. 9 illustrates one of the refractories which serves to support the heating elements in the arrangement shown in Fig. 8.

The elimination of the fire-brick lining decreases, to a remarkable extent, the amount of time required in bringing the furnace from cold to operating temperature. For example, a furnace constructed in accordance with my invention has reached an operating temperature of 1600o F. in one hour and a quarter starting with the furnace cold, while with the same kw. input per hour in the same size furnace having a firebrick lining, it has required a period of three hours for the furnace to reach its operating temperature.

The elimination of the fire brick lining reduces the overall size of the furnace, thereby using less floor space, and at the same time decreases the number of square feet of outside area of the furnace shell, and results in a remarkably lower radiation loss from the furnace.

Referring to Fig. l of the drawings, reference character 1 designates a form of steel shell enclosing heat insulating material 2 and fire-brick arch 3, all forming furnace chamber 4. By means of special shaped refractories 27 having iuted heads 28`and square headed bolts 32 and nuts 8, corrugated refiector plates 18 having coils 19 are retained in the position shown against the side walls of the furnace chamber 4.A Another shape of the special ceramic refractory 27, having a iluted head 28 retains similar corrugated reflector plates and coils in the arch of the furnace. In certain other forms of refractory construction, I have successfully used the bolted form of ceramic refractor mounted on a flat arch of a furnace, andr in the latter case I do away with the fire-clay arch shown in Fig. 1.

Fig. 2 is a typical illustration of a furnace wall 23 showing the method of mounting a heating element consisting of a return bend coil 19 lodged in corrugated reflecting and radiating plates 18. he refractory member has a body portion 26 and a base portion 27 with a spaced relationship between projecting base 27 and ilutings 28, so that a corrugated reflector plate 18 and heating coil 19 can be held in osition shown by outline 33 in Fig. 6 as agalnst a ilat wall of a furnace; or a similar corrugated refractory 18 and coil 19 can be supported in an angular position, or in a horizontal or vertical position which makes the assembly suitable for a self-supporting assembly, as shown in Fig. 8.

It is sometimes desirable as against a flat surface wall to bolt these I shaped refractories 26 to the outside furnace shell b means of bolts 32, as shown in Figs. 1 an 6, and shown in assemblyas tied 1n by nuts 8 in n Figs. 1, 2, 5 and 6 a square headed bolt 32 is shown lodged in hole 30, having square countersunk rece 31. Groove 35 at one end of refractory offers a reception means for lug 36 of an adjacent refractory, where a multiple number of such refractories are used. The combination of tongue 36 in grooves 35 keeps successive numbers of refractories in ali nment.

n Fig.'3, 25'I is shown as a modified form of the special shaped ceramic refractory, whereby the base portion 25 lodges in an undercut groove 24 of a furnace wall 23, such furnace Wall being formed of any suitable material, such as fire-clay. These refractories 25 have ilutings 22 projecting over return bends 20 of coils 19, and also overlap a portion of reflector plates 18, thereby retaining coil 19 in corrugated reflector 18. The ceramic refractories 25 are slidably arranged in the grooves of the furnace wall 23. These ilutin 22, of head portion 17, and flutings 28 o Figs. 5 and 6, provide spaces between the projections forming openings as 29 in Fig. 5. This affords direct radiation of the heat released from the return bends of coil 19 and causes a lower temperature in the return bend than results with a solid of head. When these ial shaped re acteries extend horizontal y, as in the side coil of furnace shown in Fig. 3, the openings 29'between thev fluti 22 prevent the accumulation of fine partic es, such .as iron oxide from accumulatl ing back of the free to flow throng Fi 5.

n Fig. 8 a transverse section of a vertical cylindrical or ot type furnace is shown, having cylindrlcal steel shell 10, enclosing heat insulating material 11, such as kieselguhr, forming furnace chamber 12. The inner surface of insulating wall' 11 may be c lindrical in form. By means of the speclal shaped ceramic refractory of Fig. 7, shown as 42 in Fig. 8, reflector plates 14 having coils 15 coiled thereon are self-supporting against the furnace walls. These refractories are self-bracing and are sustained by reason of 'their ownpositioning around the interior of the furnace walls. This eliminates the necessit of bolts, such as shown in Fi s. 1, 2, 5 an 6.

I have foun by actual practice and test that the tem rature of the return bends of coils lodged ack of fluted heads such as 28 is 50 to 75 F. cooler than similar bends lodged back of flanges of solid type T shaped supports, such as shown in the structure of my Letters Patent No. 1,614,321, dated January 11, 1927 While I have described a referred embodiment of my invention, I esire it to be understood that modifications may be made by those skilled in the art within the scope of the appended claims without departing from the rinciples of my invention.

What claim as new and desire to secure 22, as the scale is openings 29 as 'in by Letters Patent of the United States is as follows:

1. Means for mounting resistance elements within a furnace structure comprising a plurality of refractory members extending from a furnace wa l, said refractory member having a plurality of laterally extending fluted portions, a heat reflecting member secured between the luted portions of adjacent refractory members, said heat reflecting member havin a plurality of corrugations along the sur ace thereof, a resistor element having a dplurality of turns, said turns being dispose in said corru ations in said heat reflecting member, and portions thereof extending beneath the fluted edges of said refractories, whereby said turns are maintained in position with respect to said heat reflecting member.

2. Means for mounting a resistor comprising a plurality of refractory members spaced one from the other, said refractory members each having an overlapping flange portion, each flange portion being luted along the edge thereo a heat reflecting member loaving cated between said overlapping lian e portions, said heat reflecting member aving a corrugated surface, a resistor in the form of a wire member wound in parallel extendinfr turns in the corrugations of said heat re'flectinv. member with the turns thereof extexrdingtbeneath adjacent 'luted portions of the flange portions of said refractories, the fluted edge portions of each of said refractories being aligned with the corrugations of said heat reflecting member and pro truding over the return'ends of the wire turns in said corrugations.

3. In an electric furnace structure a supporting member for a heater element comprising a refractory having a laterally extending corrugated surface for receiving the turns of a heating element, a web portion protruding substantially perpendicular to said surface, said laterall extending surface having a plurality ofyserrations along the edge thereof, said serrations serving to en e portions of the heating element for malntaining the heating element in an operative osition. y

4. an electric furnace structure, a set of refractories extending parallel one to the other and protruding perpendicular to the wall 0f the furnace, said refractories having laterally extending surfaces thereon, a heat radiating surface constituted by a plate located intermediate said refractories, a multiplicity of corrugations in said plate extending perpendicular to the axes of said refractories, and a heater element positioned between the corrugations in said heat radiating surface and the laterally extendin surfaces of said refractories, the lateral y extending surfaces of said refractories being serrated for maintaining said heater element 1n position between said corrugations on said plate.

5. In an electric furnace structure, a set of refractories spaced one from another and protruding from a furnace wall, each of said refractories including a web portion and a laterally extending cap portion, each cap portion being serrated along the edges with the serrated portions of each set of refractories directed toward each other, a heat reflecting plate disposed between the web portions of said refractories, and a heating element carried by said heat reflecting plate and secured between the serrated portions of said refractories.

6. In an electric furnace structure, a set of parallel extending refractories protruding from the furnace wall, each of said refractories including a web portion and a top portion, the refractories of each set being interlocked end to end and havin a laterally extendin portion integral wit said to i portion an serrated at the edges thereo a heat reflecting plate having a corrugated surface thereon, said plate being disposed be- In testimony whereof I aix m si naturea,70

EDWIN L. S L EY.