US2397852A - Glassmaking furnace - Google Patents

Description

April 2, 1946. E. GENTu.

GL'ASSMAKING FURNACE Original Filed April 10, 1942 l /l/ /l ,/f/

INVENTOR BY M ATTORNEY Patented Apr. 2, 1946 GLASSMAKING FURNACE Eugene Gentil, New York, N. Y., assig'nor to Societe Anonyme des Manufactures des Glaces & Produits Chimiques de Saint-Gobain,

Chauny & Cirey, Paris, France, a corporation of France Continuation of application Serial No. 438,370, April 10, 1942. This application December 23, 1944, Serial No, 569,606

Claims.

5 This invention relates to glass-making furnaces and more particularly to furnaces of the so-called day tank type, which are operated in a continuous or semi-continuous manner, li. e., so that rened glass may be continuously or intermittently withdrawn from one end of* the furnace at the same time that raw glass-making materials are being supplied to the other end thereof.

This application is a continuation of my application Serial No. 438,370, filed April l0, 1942, for Glass-making furnace.

In accordance with well-known practices, glass has long been produced in furnaces wherein the melting and refining of the glass-making materials are accomplished by surface heating the same, such as by burning gases above the surface of the mass of materials in the furnace. Heat energy thus generated is transferred to and through the glass mass by radiation and convection, and the amount of heat energy developed and thus effectively transmitted to the glass mass naturally depends to a large extent upon the temperatures of the products of combustion. Such furnaces 'are constructed of refractory materials and are accordingly limited in their production capacities by the maximum temperatures to which the refractory roofs and walls of the furnaces may be subjected without causing too rapid deterioration thereof.

It is a recognized fact that in oilor gas-fired furnaces of the above character, approximately 85% of the total heat energy. generated is lost in the form of radiation vand stack losses when the furnace is operating at normal or most efcient capacity. It is also recognized that the normal melting capacity of a furnace employing surface heating is a function of the surface area of the glass mass in the furnace. The capacity may, o f course, be increased to above normal for a furnace containing a treated mass of given surface area by the use of increased temperatures, but only at the expense of an appreciable andl rapid decrease in the operating eificiency. Additionally, any such increase in output capacity for a given furnace of the above type is necessarily limited, as pointed out above, by the maximum temperatures which may be practically employed.

It is accordingly one of the objects of the present invention to provide a novel glass-making furnace, the output capacity of which is considerably more flexible than is the output capacityv of any furnace heretofore known.

Another object of the invention is to provide a novel furnace adapted for the continuous production of glass from raw materials continuously ill fed thereto which loperates at high efiiciency throughout a wide range of production capacities.

Still another` object is to provide a glass-making furnace wherein electric heating means within the mass of treated materials are novelly combined with other or surface heating means, such as a gas flame.

A further object is to provide a furnace of the glass-making type which incorporates novel means for effectively and eihciently varying the amount of heat energy supplied to the materials beingprocessed therein without sensibly varying the radiation and stack losses.

Another object is to provide a novelly constructed glass-making furnace wherein heat losses during furnace operation at any of a wide range of output capacities are relatively small in comparison to the losses in similar furnaces heretofore provided.

A still further object is to provide a novel lfurnace which is so constructed that a comparatively high rate of continuous or semi-continuous production of glass may be obtained in a furnace of relatively small size to thereby meet varying market demands.

The above and further objects and novel features of the invention will more fully appear from the following detailed description when the same is read in connection with the accompanying drawing. It is to be expressly understood, however, that the drawing is for the purpose of illustration only and is not intended as a definition of the limits of the invention, reference for this latter purpose being had primarily to the appended claims.

In the drawing, wherein like reference `characters refer t0 like parts throughout the sjveral views,

Fig. 1 is a somewhat diagrammatic top view, partly in section and with parts broken away, showing one form of furnace embodying the present invention, the section being taken substan-V tially on line l--I of Fig. 2;

Fig. 2 is a similar side elevation, partly in section and with parts broken away, of said furnace, the section being taken substantially on line 2-2 of Fig. 1;

Fig. 3 is a detail sectional view taken substantially on line 3-3 of Fig. 1; and,

Fig. 4 is a sectional elevation, similar to Fig. 2 but on a smaller scale, showing a modified doghouse which may be incorporated in the embodiment of Figs. 1 to 3.

The embodiment of the invention illustrated in Figs. 1 to 3. of the drawing, by way of example,

' suitable known manner from refractory materials, said tank comprising a bottom wall t, side walls l, end walls 9 and lll, and an arched roof Ila. The interior of said tank or container may be, if desired, longitudinally divided into melting and rening chamber li and a working chamber I2 by a. partition Id fabricated from blocks of refractory materials. As shown, the partition extends across the entire Width of container e and only a short distance above the surfaceyof the molten mass I5, the level of which is maintained substantially constant. Partition It is provided Vwith a passage it, which is preferably submerged and through which refined glass may pass from chamber il to working chamber l2.

Glass-making materials lha, commonly known as batch, are fed to chamber lr! through one or more melting compartments or doghouses il and I8 built out from end wall ti and doghouses l@ built out from walls d adjacent to wall 9. Each of these doghouses may be open at the top and each is preferably in continuous communication with chamber il through a passage 2@ in wall il or wall l, as the case may be. The upper edges of passages 2li are preferably above the highest level of the molten mass l5, as shown in Fig. 2, but any one or all of said pasages may be completely submerged, if desired.

A novel combination of heating means is provided for melting and refining the materials fed through the doghouses to chamber l l whereby the productive capacity of the furnace may be quickly and readily varied within relatively wide limits without any material variation in operating ehiv ciency and without appreciably aifecting the quality of the final product. In the form shown, the molten mass of materials l5 being processed within chamber li is primarily heated by one or a series of gas flames created above the surface thereof by gas burners 2l which may be of any suitable, construction well-known in the glassmaking'furnace art. The furnace and said burners are preferably so designed and the furnace is constructed of suitable refractory materials so that a relatively high operating efficiency is obtained when burners ZI or other suitable surface heating means are used as. the sole heating means. When the furnace is operated in this manner, the raw materials are preferably fed` through doghouse I1, although the same may be fed through any of the other doghouses or simultaneously through several of them.

In order to make it possible to increase the maximum production rate of the furnace without materially reducing the operating efficiency and without adversely affecting the refractory materials of which the furnace is made, the gas burners or other surface heating means may be supplemented in a novel manner with electric heating means whereby the temperature of the glass mass may be raised advantageously without increasing the temperature of the gas flame, which latter temperature is limited in a practical sense by the refractory materials in the roof and walls of the furnace. In the form shown, the supplementary heating means comprises electrodes in doghouses I8 and I9 by means of which an electrical current may be caused to flow through they two electrodes 22a and 23a are similarly mounted directly below electrodes 22 and 23, respectively. Electrodes 22, 22a may be electrically connected with one pole of a source of electrical energy 24 and electrodes 23, 23a may be connected with the otsiher pole of said source through suitable switches 2 Y The electrodes in doghouses I9 may he mounted in the same manner as in doghouses l, but in the illustrated embodiment two horizontal verticallyspaced electrodes 26, 26a extend through the side walls of said doghouses and are connected to one terminal of source 2li or other suitable source of electrical energy while two verticallyspaced electrodes all, Zla are similarly disposed at a greater distance from furnace wall l and are connected to the other terminal of said source through switches 2d, which may be opened or closed at the will of the operator.

The electrodes above described, made of any suitable conducting material, such as carbon for example, which will not be adversely attacked to any substantial degree by the molten glass-making materials i5. Said electrodes preferably have a small surface area in contact with said materials, as compared to the cross-sectional area of the molten mass between cooperating electrodes, so that the zones of highest temperatures will be created in the immediate vicinity of the electrodes. If the electrodes are thus properly chosen, in a manner well understood in the art, it `will be possible to raise the temperature of the materials in the doghouses i8 and i9 to such a degree that rapidmelting thereof is obtained. It will be seen that the electrodes ln all or in one, two or three of the doghouses Iii and I9 may be cut-in by closing the appropriate switches 25 and 2B. A master switchin the circuit at a point adjacent source 24 may be provided for simultaneously disconnecting all of the electrodes from said source. If desired, supplementary heating means in the form of electrodes connected to source 24 may also be placed in doghouse Il in either of the two arrangements illustrated or any other suitable arrangement. When the electrodes in doghouses I8 and I9 are not active, i. e., when switches 25 and 28 are in open position and no raw materials are fed through said doghouses to chamber II, there will be very little, if any, flow from said doghouses into said chamber. At the same time, the mass accumulated in the inactive doghouses will be relatively cool and in a relatively solid state so that there will not be any appreciable loss of heat therethrough, It will be understood that electrodes mounted differently and electrodes not wholly submerged in the molten mass may be employed in lieu of the preferred form illustrated.

The heat units created in the glass mass I5 by the flow of electrical current between any of the cooperating electrodes supplements the heat units supplied by the gas ame or other heating means in chamber I I so that the materials will be melted and rened more rapidly without any appreciable deleterious effects on the furnace walls and roof. The finished product may, accordingly, be drawn olf faster and raw materials may be added at a correspondingly higher rate, thereby increasing the output capacity of the furnace without altering the size thereof or the surface area of the molten mass subjected to the heat of the gas flame or other appropriate primary heating means. The refined glass from chamber II flows through passage I6 in partition I4 into working chamber IZ- where it cools to a suitable. working .houses.

temperature. Finished glass may be continuously or intermittently drawn off through one or more outlets 2! in wall I in any suitable manner well-known in the art. Preferably, raw materials |5a are inserted and refined glass is drawn off at substantially the same rates so that the level .of molten mass I5 remains substantially constant. However, refined glass may at times be drawn off at a faster rate than materials are added to v satisfy production demands, such as during the day.

In Fig. 4 there is illustrated a portion of a furnace, as above described, but embodying a modied form of doghouse or melting compartment. As shown, the novel doghouse I8' has the walls 9' and 30 thereof inclined to the vertical so as to lconverge toward the electrodes 3l, 3Ia and 32,

32a, which may be suitably connected to a source of electrical energy in a manner heretofore described. If desired, the other two walls (not shown) of doghouse I8' may also converge toward the base of the furnace or the upper level of the glass massa This novel construction, which may be applied to any or all of the doghouses of Fig. l, prevents the batch I5a from sliding down too rapidly and thus avoids the possibility of overcharging the furnace with raw materials. The converging Wall structure also assists in maintaining the batch in the position illustrated in the doghouse so that the same will better serve as insulation to prevent heat losses by way of the dog- The shape of the surface of the molten materials in the doghouse may also be varied in this 'manner to best suit the type of electrodes employed.

There is thus provided a furnace adapted for the continuous or semi-continuous production of glass wherein electric heating by Joule effect for melting the glass-making materials is employed in a novel manner to supplement surface heating of the molten glass mass, such as by a gas flame or other appropriate heating means,A in order to 'make it possible to effectively vary the production rate of a given furnace without appreciably affecting the operating efficiency thereof. Additionally, a novel furnace is provided which has the advantage of being adapted to eiiiciently produce high quality glass at a desired maximum rate and also adapted to continuously and efciently produce glass of like quality at a much slower rate, thereby making it unnecessary to stop and start the furnace when only small production is desirable. Furthermore, a novel furnace is provided which has the capability Ofeiiiciently producing high quality glass at a desired rate with the cheapest kind of fuel available and is yet capable of efficiently producing glass of like quality at a higher rate, thereby making it unnecessary to build and start a new furnace when only a small increase in production is required. If the electric energy used for increasing the production by the simple and inexpensive construction comprehended by the invention is somewhat more expensive than the fuel normally used for standard production, this increased cost will be more than offset by the fact that only one furnace is required. The invention is such that it may be readily and inexpensively adapted to existing furnaces to render the same capable of meeting variations in production which depend on variations in the market. The novel furnace provided also lends itself to simple and inexpensive construction as well as to proper operation by relatively unskilled artisans.

Although only two embodiments of the invention are illustrated and described in detail, it is to be expressly understood that the invention is not limited thereto and that various changes may be made therein without departing from the spirit and scope of the invention. For example, the type and arrangement of electrodes in each doghouse or melting compartment may be varied somewhat, as can also the precise position and shape of the several doghouses. Various other changes including those mentioned in the specilication and variations in the design and arrangement of parts illustrated may also be made as will now be apparent to those skilled in the art. For a definition of the limits of the invention, reference is had primarily to the appended claims.

What is claimed is: f

1. A glass-making' furnace of the tank type comprising a refractory container for molten glass-making materials, at least one doghouse connected to said container and having a wall in common therewith, said wall having a passage therein extending across substantially the entire width of said doghouse and from the bottom of the latter to approximately the level of the molten mass in said container, whereby unmelted glass-making materials may be fed to said container from the doghouse, heating means for applying heat to the surface of said materials in said container for melting and refining the materials entering the container from 'said doghouse to effect the production of refined glass at one rate, and electrical heating means selectively operable at the lwill of an operator for applying heat to the materials in said doghouse below the surface of said materials for selectively increasing said productive rate, said last-named means comprising a plurality of electrodes in said doghouse, a source of electrical energy and means for connecting said electrodes to different terminals of said source.

2. A glass-making furnace wherein glass-making materials may be supplied adjacent one end of the furnace and refined glass lmay be removed adjacent the other end thereof with substantial continuity, said furnace comprising a refractory container for the molten glass-making materials, at least one doghouse directly connected to said container adjacent the input end of the latter and having one wall in common therewith, said wall having an opening therein through which unmelted glass-making materials may be supplied to said container, heating means for applying heat to the surface of` said materials in the container and adapted to melt and refine the materials entering the container from said doghouse, and means selectively operable at the will of an operator for increasing the production rate of said furnace; without increasing the intensity of said surface heating means, said selectively operable means comprising a plurality of electrodes in said doghouse, a source of electrical energy and means connecting said electrodes to different terminals of said source whereby electrical -current is caused to ow through the materials in the doghouse to heat the same.

3. A glass-making furnace comprising a con-4 tainerfor molten glass-making materials having an input end and an output end, a plurality of doghouses adjacent the input end of said container, each of said doghouses having a wall in common with said container and being in continuous direct communication with said container through a passage in said common wall whereby raw unmelted glass-making materials may be fedfto the container through said doghouses, heating means for applying sumcient heat to the surface of the materials entering said container from said doghouses to melt and refine the same when the rate of flow through the furnace does not exceed .a predetermined maximum, and additional heating means selectively operable at the will of an operator for increasing the melting and refining capacity of the furnace, said additional heating means comprising a plurality of electrodes in at least one of said doghouses and means for causing electrical current to iiow through-the-glass-making materials between said electrodes.

4. A glass-making furnace of the continuous ow type wherein glass-making materials are fed in adjacent one end thereof and refined glass is removed adjacent the other end with substantial continuity and wherein the level of the treated glass is maintained substantially constant, said furnace comprising a refractory container for a mass of molten glass-making materials, at

least one doghouse adjacent the input end of said container and having one wall in common therewith, said common Wall extending downwardly only to approximately the level of the treated glass to thereby provide a passage connecting said doghouse vand said-contalner whereby unmelted glass-making materials may be fed to the container through said doghouse during normal operation of the furnace, heating means for applying heat to the surface of the materials entering said container from said doghouse to melt and rene the same, said heating means constituting the sole heating means within said container, and supplemental heating means adapted to be rendered operable at the will of an operator for selectively increasing the output rate and comprising a plurality of electrodes in said doghouse, a. sourceof-'electrical current and means for connecting said electrodes to dierent terminals of said source whereby electric current is caused to flow through said materials between electrodes of different polarities.

5. A glass-making furnace of the tank type wherein glass-making materials are fed in adjacent one end thereof and rened glass is removed from the other end thereof, said furnace comprising a refractory container for a mass of molten glass-making materials, at least one doghouseat the input end of said container and having one wall in common therewith, said doghouse having continuous communication with the con-v tainer through an opening in said wall, said opening being so positioned and of sufficient size as to permit unmelted glass-making materials to be fed to the container through said doghouse, heating means for applying sumcient heat to the surface of the materials entering said container from said doghouse to melt and refine the same to effect one rate of output of-reiined glass, at least one additional doghouse adjacent the input end of said container having direct continuous communication with the container through a submerged opening in the wall of the latter, and electrical heating means selectively operable at the will of an operator for heating glass-making materials in said additional doghouse to thereby -selectively increase the output rate dft the furnace, said electrical heating means comprising a source of electrical energy, a 4plurality of electrodes in said additional doghouse, and means for

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