CA1072166A - Electrically-heated melting furnace with a cooling trough - Google Patents
Electrically-heated melting furnace with a cooling troughInfo
- Publication number
- CA1072166A CA1072166A CA308,287A CA308287A CA1072166A CA 1072166 A CA1072166 A CA 1072166A CA 308287 A CA308287 A CA 308287A CA 1072166 A CA1072166 A CA 1072166A
- Authority
- CA
- Canada
- Prior art keywords
- trough
- furnace
- cooling
- tank
- electrodes
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P40/00—Technologies relating to the processing of minerals
- Y02P40/50—Glass production, e.g. reusing waste heat during processing or shaping
- Y02P40/57—Improving the yield, e-g- reduction of reject rates
Landscapes
- Glass Melting And Manufacturing (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE
An electrically-heated, glass melting furnace with a cooling trough and with cooling means for the trough is provided.
The furnace is heated by means of electrodes immersed in molten glass in the furnace; particularly as the throughput of the furnace increases, the molten glass becomes hotter. To overcome this, the cooling trough is provided in a portion of the furnace bottom, extending beyond a throat to a riser, with the bottom and the side walls of the trough being exposed to ambient temperatures below the furnace. The resulting heat loss aids in cooling the glass flowing out of the furnace to overcome the inherent heat rise at high throughputs. Cooling means are also provided extending along the trough, with the rate of cooling achieved thereby being capable of selective control. Specifically, an air duct extends along the cooling trough and has outlets spaced therealong directed at the trough bottom to supply cooling air in heat exchange relationship with the bottom. Electrodes also can extend upwardly through the trough bottom into the trough, the electrodes serving to further cool the trough by providing heat conductive paths from the trough to the ambient conditions below the furnace. The trough electrodes, if desired, can also be heated by an emergency power supply to prevent glass from solidifying in the trough in the event that a major power failure should occur and power to the main heating electrodes is off.
An electrically-heated, glass melting furnace with a cooling trough and with cooling means for the trough is provided.
The furnace is heated by means of electrodes immersed in molten glass in the furnace; particularly as the throughput of the furnace increases, the molten glass becomes hotter. To overcome this, the cooling trough is provided in a portion of the furnace bottom, extending beyond a throat to a riser, with the bottom and the side walls of the trough being exposed to ambient temperatures below the furnace. The resulting heat loss aids in cooling the glass flowing out of the furnace to overcome the inherent heat rise at high throughputs. Cooling means are also provided extending along the trough, with the rate of cooling achieved thereby being capable of selective control. Specifically, an air duct extends along the cooling trough and has outlets spaced therealong directed at the trough bottom to supply cooling air in heat exchange relationship with the bottom. Electrodes also can extend upwardly through the trough bottom into the trough, the electrodes serving to further cool the trough by providing heat conductive paths from the trough to the ambient conditions below the furnace. The trough electrodes, if desired, can also be heated by an emergency power supply to prevent glass from solidifying in the trough in the event that a major power failure should occur and power to the main heating electrodes is off.
Description
iO72166 .
This invention relates to an electrically-heated, melting furnace having a cooling trough located in the bottom thereof.
Electrically-heated, glass melting furnaces have been known in the art to a limited extent since the early 1900's.
One problem with the earlier furnaces was the lack of effective electrodes by means of which the electric heating could be ; accomplished. More recently, satisfactory electrodes have been developed. At the same time, electric heating of glass melting furnaces has become more desirable since the electrically-heated furnaces have a particular advantage in substantially eliminating pollution at the glass melting site. An additional - advantage results when the electric power is generated by coal or nuclear fuel, in contrast to burners in conventional glass melting furnaces utilizing relatively scarce gas or oil as the ; fuel. However, the electric heat also has other advantages, including making it possible to obtain higher quality glass and a high degree of melting efficiency. Better control over the final glass composition can also be achieved, especially when there are more volatiles in the glass batch.
With conventional glass melting furnaces employing combustion burners firing over the molten glass, as the through-put of the furnace increases, the temperature of the glass tends ` to decrease. With electrically-heated furnaces, however, with the electrodes immersed in the molten glass, an increase in the throughput has been found to result in an increase in the temperature of the molten glass exiting from the furnace.
- This invention seeks to provide an electrically-heated glass melting furnace which facilitates achieving a more uniform temperature of the exiting glass even under oonditions of varying throughput.
- 1 - ~p ' ' ' 107~166 According to this invention there is provided a furnace for melting a heat~softenable material, the fur-nace comprising a tank for holding molten material, means extending into the molten material below the surface there-of for supplying heat to the molten material, wall means forming a cooling trough located in the bottom of the tank and extending therebeyond to discharge molten material from the tank, the wall means being exposed to ambient conditions below the bottom of the tank and structured to facilitate dissipation of heat from molten material in the trough through the wall means and cooling means extending along the trough and.effective to supply a cooling medium in heat exchange relationship with an external surface of the wall means.
The furnace preferably comprises a plurality of electrodes extending into said trough and being capable of conducting heat away from molten material in said trough to ambient conditions below said tank bottom.
A furance in accordance with an embodiment of the invention has a cooling trough centrally located in the bottom of the furnace.
,~.i, .
10~ 6 tank and extending beyond a discharge end wall of the furnace to a riser. The cooling trough is designed so as to project below the main bottom of the tank, whereby both the sides and bottom of the trough are exposed to ambient conditions below the glass melting furnace. The cooling trough thereby presents a substantial surface area from which heat can be dissipated. The cooling trough preferably has a width not exceeding about one-fourth the width of the furnace bottom, and preferably has a depth at least equal to the width to assure substantial protru-sion of the trough below the bottom of the tank and a corres-pondingly substantial degree of heat loss. The trough preferably extends not more than about one-half the distance between the end walls of the tank since the glass near the forward end of the tank has a minimal convection current, and a cooling trough at this portion of the tank would be less effective. The extra length of such a trough would increase the cost of the tank and increase general heat loss without having any real benefit on the cooling of the exiting glass through the trough at the dis-charge end of the tank.
Coolihg means also extend along the cooling trough and provide a cooling medium in heat exchange relationship with the outer surfaces of the trough. More specifically, the cool-ing means can be in the form of an air duct extending along the trough and having a plurality of outlets directing air into con-tact with an outer surface of the cooling trough. The volume of air then can be controlled to control the extent of cooling of the trough. Temperature-sensing means can be located down-stream in the trough to sense the temperature of the glass 0~166 flowing therethrough, with a control unit controlling the air volume in response to the temperature. Hence, as the throughput increases and the glass temperature rises, the volume of the cool-ing medium can be increased to correspondingly increase the amount of heat dissipated from the surfacesof the trough.
Short electrodes can also be provided for the cooling trough with these electrodes extending through a wall of the trough, preferably the bottom, and having exposed portions below the furnace. The electrodes, being heat conducting, can thereby conduct heat from the molten glass in the trough to the ambient conditions below the furnace. The extent to which the electrodes protrude into the trough can also be controlled, with the degree of cooling by the electrodes thereby regulated. If desired, a power supply, preferably an emergency power supply, can be pro-vided for the trough electrodes. In the event of a main power failure, power can then be supplied to the electrodes to heat the glass in the trough and prevent solidification.
The invention, its objects, and its advantages will be further understood from the following detailed description of a preferred embodiment thereof, reference being made to the accom-panying drawings, in which:
Fig. l is a schematic, fragmentary view in longitudinal cross section of a furnace embodying the invention;
Fig. 2 is a schematic, fragmentary, plan view of the furnace of Fig. l, without glass in the furnace;
Fig. 3 is a schematic view in transverse cross section taken through the furnace of Figs. l and 2; and Fig. 4 is a greatly enlarged view of a portion of the furnace of Fig. 3, and showing certain additional details.
Referring to the drawings, and particularly to ~igs. l and 2, an overall melting furnace embodying the invention is indicated at 10. The furnace is illustrated in connection with glass melting operations, although the furnace according to the invention can also be used to advantage in the melting of other materials. The furnace supplies molten glass to a riser 12, located beyond the discharge end, and to a conditioning chamber 14 and a forehearth 16. From the forehearth, the molten glass can be supplied thxough openings 18 to suitable fiber-forming devices 20 located therebelow. Of course, the furnace according to the invention is not limited to supplying glass for fiber-forming operations.
The furnace 10 includes a glass melting tank 22 formedby side walls 24, a forward end wall 28, a rear or dis-charge end wall 30, and a main bottom 32. A suitable roof (not shown) can be supported above the tank 22. Heating means for melting glass or other batch in the furnace 10 include a plural-ity of electrodes 34 extending upwardly into the tank 22 from a lower level through the bottom 32. The electrodes 34 are - preferably positioned in a symmetrical manner with respect to a -~ center line extending longitudinally through the tank 22, with electrodes toward the forward half of the tank being substan-tially uniformly spaced apart, and with those toward the dis-charge half of the tank being spaced farther apart at the center of the tank than at the sides. The portions of the electrodes 34 exposed below the tank bottom 32 can be protected by suitable sleeves containing an inert gas, and the electrodes can also be water cooled, as is well known in the art. Power is supplied to the electrodes 34 through suitable leads from a suitable power source (not shown).
10~ 66 The portions of the electrodes 34 within the tank 22 are totally immersed in a pool of molten glass 36, with the upper ends of the electrodes typically being about ten inches below the surface of the molten glass 36. Additional glass batch is con-tinually supplied over the molten glass 36 to form a batch layer 38 thereon which also serves as an effective insulating layer on the molten glass. The batch can be supplied from a batch car-riage 40 which extends across the entire width of the tank 22 between the side walls 24 and is reciprocated back and forth substantially over the length of the tank. A carriage of this nature is disclosed more fully in U.~. patent No.3,877,917 issued April 15, 1975 in the name of Charles M. Hohman. The car-riage can include one or more vibratory feeders to regulate the rate of feed of the batch from the carriage 40 to the layer 38.
When the output of the fiber-forming units 20 or other glass forming devices is increased, the throughput of the furnace 10 also must be increased. To accomplish this, more electrical power is supplied to the electrodes 34 and a larger quantity of batch is fed from the carriage 40. Since the heating means or electrodes are entirely immersed within the molten glass 36, the increased throughput with the increased power to the electrodes 34 results in a higher temperature in the molten glass supplied to the forehearth 16. This can be detrimental to the fiber-forming operation or other operation, particularly where the forehearth glass temperature is critical, as is true of fiber-forming operations. To achieve a more uni-form glass temperature in the forehearth 16, in spite of increased glass pull or throughput, a cooling trough 42 in accordance with the invention is provided in the bottom of the lOq'~1~6 tank 22. The trough 42 is formed by wall means indicated at 44 protruding below the bottom 32 of the tank 22, the wall means 44 constituting two side walls 46 and 48 (see Figs. 3 and 4) and a bottom wall 50. These walls present three surfaces exposed to ambient conditions below the tank 22 to provide substantial heat loss to the ambient from the trough 42. The width of the trough 42 preferably is from one-sixth to one-fourth the width of the tank 22, with the depth of the trough preferably being at least equal to the width to provide adequate heat loss through the walls 46 and 48 and the bottom 50. The trough 42 is of a length sufficient to extend to the riser 12 past a throat 52 located between the tank and the riser. At the other end, the trough 42 preferably extends no more than about half the distance between the discharge end wall 30 and the forward end wall 28. Any shorter distance does not enable sufficient cooling to occur in the trough 42. If the trough extended further toward the forward end wall 28, it would not have any substantial beneficial cooling effect, particularly since convection currents in the molten glass toward the forward end are minimal. Consequently, the coolest glass would not necessarily collect in the trough to any noticeable extent toward the forward end. Thus, an extra length of the trough toward the forward end wall would only generally increase heat loss and result in higher construction costs for the furnace. Toward the discharge end of the tank 22, convection currents are more pronounced (Fig. 3) with the coolest glass collecting in the trough 42, thus reducing the cooling requirements for the glass flowing in a stream through the trough 42.
:lOqZ166 Cooling means are provided for the trough 42 to enable the cooling effect on the glass flowing through the trough to change as the throughput changes. In a preferred form, the cooling means in accordance with the invention are indicated at 54 and include a main duct 56 extending longitudinally of the trough 42 and a plurality of branch outlets 58 communicating therewith and directing a cooling medium, specifically air, toward the bottom 50 of the wall means 44. The cooling medium or air can be supplied by a suitable blower 60 (Fig. 1), with the volume of the air controlled by a damper or valve 62. The flow-control damper 62 can be opened more as the throughput of the furnace 10 increases and the glass discharged therefrom tends to increase in temperature. A higher volume of the air is then directed through the outlets 58 toward the bottom 50 of the trough thereby to increase the dissipation of heat from the trough and produce a greater cooling effect on the molten glass flowing therethrough.
The damper 62 can be automatically controlled, if desired. For this purpose, a temperature-sensing device or thermocouple 64 is located in the trough 42 toward the down-stream end thereof with the device 64 being connected to a temperature controller 66. This, in turn, operates a control motor 68 which is operatively connected to the damper 62 so as to tend to close the damper 62 as the temperature sensed by the thermocouple 64 decreases and to open the damper 62 as the temperature sensed by the thermocouple 64 increases. The com-ponents 64, 66 and 68 are commercially-available devices and are not discussed in detail.
-, lOqZ166 Also, in accordance with the invention, a plurality of short electrodes 70 can be located in the trough 42, extending upwardly through the bottom 50 of the wall means 44. By them-selves, the electrodes 70 are heat-conducting elements which can serve to cool the glass by conducting heat in the glass in the trough 42 to ambient conditions below the tank 22. If desired, each of the electrodes 70 can be provided with a gear drive 72 (Fig. 4) and a motor 74, by means of which the electrodes 70 can be raised so as to protrude further into the trough 42, or lowered so as to have a shorter length immersed in the trough.
With this arrangement, the extent of the cooling effect of the electrodes 70 can be controlled. As the extent of protrusion of the electrodes into the trough increases, the cooling effect of the electrodes on the glass flowing through the trough also increases, as long as a sufficient portion of the length remains exposed so as to dissipate heat adequately. The streams of cooling air supplied by the outlets 58 can be directed at the exposed portions of the electrodes 70 below the bottom 50, if desired, to increase the Eate of conduction of heat away from the glass in the trough by means of the electrodes.
If desired, the electrodes 70 can also be connected to a power supply as indicated in Fig. 4, preferably an emer-gency power supply. In the event of a main power failure for the electrodes 34, the emergency power supply can be used to heat the electrodes 70 and thereby maintain the glass in the trough 42 in a molten condition under emergency conditions.
g _
This invention relates to an electrically-heated, melting furnace having a cooling trough located in the bottom thereof.
Electrically-heated, glass melting furnaces have been known in the art to a limited extent since the early 1900's.
One problem with the earlier furnaces was the lack of effective electrodes by means of which the electric heating could be ; accomplished. More recently, satisfactory electrodes have been developed. At the same time, electric heating of glass melting furnaces has become more desirable since the electrically-heated furnaces have a particular advantage in substantially eliminating pollution at the glass melting site. An additional - advantage results when the electric power is generated by coal or nuclear fuel, in contrast to burners in conventional glass melting furnaces utilizing relatively scarce gas or oil as the ; fuel. However, the electric heat also has other advantages, including making it possible to obtain higher quality glass and a high degree of melting efficiency. Better control over the final glass composition can also be achieved, especially when there are more volatiles in the glass batch.
With conventional glass melting furnaces employing combustion burners firing over the molten glass, as the through-put of the furnace increases, the temperature of the glass tends ` to decrease. With electrically-heated furnaces, however, with the electrodes immersed in the molten glass, an increase in the throughput has been found to result in an increase in the temperature of the molten glass exiting from the furnace.
- This invention seeks to provide an electrically-heated glass melting furnace which facilitates achieving a more uniform temperature of the exiting glass even under oonditions of varying throughput.
- 1 - ~p ' ' ' 107~166 According to this invention there is provided a furnace for melting a heat~softenable material, the fur-nace comprising a tank for holding molten material, means extending into the molten material below the surface there-of for supplying heat to the molten material, wall means forming a cooling trough located in the bottom of the tank and extending therebeyond to discharge molten material from the tank, the wall means being exposed to ambient conditions below the bottom of the tank and structured to facilitate dissipation of heat from molten material in the trough through the wall means and cooling means extending along the trough and.effective to supply a cooling medium in heat exchange relationship with an external surface of the wall means.
The furnace preferably comprises a plurality of electrodes extending into said trough and being capable of conducting heat away from molten material in said trough to ambient conditions below said tank bottom.
A furance in accordance with an embodiment of the invention has a cooling trough centrally located in the bottom of the furnace.
,~.i, .
10~ 6 tank and extending beyond a discharge end wall of the furnace to a riser. The cooling trough is designed so as to project below the main bottom of the tank, whereby both the sides and bottom of the trough are exposed to ambient conditions below the glass melting furnace. The cooling trough thereby presents a substantial surface area from which heat can be dissipated. The cooling trough preferably has a width not exceeding about one-fourth the width of the furnace bottom, and preferably has a depth at least equal to the width to assure substantial protru-sion of the trough below the bottom of the tank and a corres-pondingly substantial degree of heat loss. The trough preferably extends not more than about one-half the distance between the end walls of the tank since the glass near the forward end of the tank has a minimal convection current, and a cooling trough at this portion of the tank would be less effective. The extra length of such a trough would increase the cost of the tank and increase general heat loss without having any real benefit on the cooling of the exiting glass through the trough at the dis-charge end of the tank.
Coolihg means also extend along the cooling trough and provide a cooling medium in heat exchange relationship with the outer surfaces of the trough. More specifically, the cool-ing means can be in the form of an air duct extending along the trough and having a plurality of outlets directing air into con-tact with an outer surface of the cooling trough. The volume of air then can be controlled to control the extent of cooling of the trough. Temperature-sensing means can be located down-stream in the trough to sense the temperature of the glass 0~166 flowing therethrough, with a control unit controlling the air volume in response to the temperature. Hence, as the throughput increases and the glass temperature rises, the volume of the cool-ing medium can be increased to correspondingly increase the amount of heat dissipated from the surfacesof the trough.
Short electrodes can also be provided for the cooling trough with these electrodes extending through a wall of the trough, preferably the bottom, and having exposed portions below the furnace. The electrodes, being heat conducting, can thereby conduct heat from the molten glass in the trough to the ambient conditions below the furnace. The extent to which the electrodes protrude into the trough can also be controlled, with the degree of cooling by the electrodes thereby regulated. If desired, a power supply, preferably an emergency power supply, can be pro-vided for the trough electrodes. In the event of a main power failure, power can then be supplied to the electrodes to heat the glass in the trough and prevent solidification.
The invention, its objects, and its advantages will be further understood from the following detailed description of a preferred embodiment thereof, reference being made to the accom-panying drawings, in which:
Fig. l is a schematic, fragmentary view in longitudinal cross section of a furnace embodying the invention;
Fig. 2 is a schematic, fragmentary, plan view of the furnace of Fig. l, without glass in the furnace;
Fig. 3 is a schematic view in transverse cross section taken through the furnace of Figs. l and 2; and Fig. 4 is a greatly enlarged view of a portion of the furnace of Fig. 3, and showing certain additional details.
Referring to the drawings, and particularly to ~igs. l and 2, an overall melting furnace embodying the invention is indicated at 10. The furnace is illustrated in connection with glass melting operations, although the furnace according to the invention can also be used to advantage in the melting of other materials. The furnace supplies molten glass to a riser 12, located beyond the discharge end, and to a conditioning chamber 14 and a forehearth 16. From the forehearth, the molten glass can be supplied thxough openings 18 to suitable fiber-forming devices 20 located therebelow. Of course, the furnace according to the invention is not limited to supplying glass for fiber-forming operations.
The furnace 10 includes a glass melting tank 22 formedby side walls 24, a forward end wall 28, a rear or dis-charge end wall 30, and a main bottom 32. A suitable roof (not shown) can be supported above the tank 22. Heating means for melting glass or other batch in the furnace 10 include a plural-ity of electrodes 34 extending upwardly into the tank 22 from a lower level through the bottom 32. The electrodes 34 are - preferably positioned in a symmetrical manner with respect to a -~ center line extending longitudinally through the tank 22, with electrodes toward the forward half of the tank being substan-tially uniformly spaced apart, and with those toward the dis-charge half of the tank being spaced farther apart at the center of the tank than at the sides. The portions of the electrodes 34 exposed below the tank bottom 32 can be protected by suitable sleeves containing an inert gas, and the electrodes can also be water cooled, as is well known in the art. Power is supplied to the electrodes 34 through suitable leads from a suitable power source (not shown).
10~ 66 The portions of the electrodes 34 within the tank 22 are totally immersed in a pool of molten glass 36, with the upper ends of the electrodes typically being about ten inches below the surface of the molten glass 36. Additional glass batch is con-tinually supplied over the molten glass 36 to form a batch layer 38 thereon which also serves as an effective insulating layer on the molten glass. The batch can be supplied from a batch car-riage 40 which extends across the entire width of the tank 22 between the side walls 24 and is reciprocated back and forth substantially over the length of the tank. A carriage of this nature is disclosed more fully in U.~. patent No.3,877,917 issued April 15, 1975 in the name of Charles M. Hohman. The car-riage can include one or more vibratory feeders to regulate the rate of feed of the batch from the carriage 40 to the layer 38.
When the output of the fiber-forming units 20 or other glass forming devices is increased, the throughput of the furnace 10 also must be increased. To accomplish this, more electrical power is supplied to the electrodes 34 and a larger quantity of batch is fed from the carriage 40. Since the heating means or electrodes are entirely immersed within the molten glass 36, the increased throughput with the increased power to the electrodes 34 results in a higher temperature in the molten glass supplied to the forehearth 16. This can be detrimental to the fiber-forming operation or other operation, particularly where the forehearth glass temperature is critical, as is true of fiber-forming operations. To achieve a more uni-form glass temperature in the forehearth 16, in spite of increased glass pull or throughput, a cooling trough 42 in accordance with the invention is provided in the bottom of the lOq'~1~6 tank 22. The trough 42 is formed by wall means indicated at 44 protruding below the bottom 32 of the tank 22, the wall means 44 constituting two side walls 46 and 48 (see Figs. 3 and 4) and a bottom wall 50. These walls present three surfaces exposed to ambient conditions below the tank 22 to provide substantial heat loss to the ambient from the trough 42. The width of the trough 42 preferably is from one-sixth to one-fourth the width of the tank 22, with the depth of the trough preferably being at least equal to the width to provide adequate heat loss through the walls 46 and 48 and the bottom 50. The trough 42 is of a length sufficient to extend to the riser 12 past a throat 52 located between the tank and the riser. At the other end, the trough 42 preferably extends no more than about half the distance between the discharge end wall 30 and the forward end wall 28. Any shorter distance does not enable sufficient cooling to occur in the trough 42. If the trough extended further toward the forward end wall 28, it would not have any substantial beneficial cooling effect, particularly since convection currents in the molten glass toward the forward end are minimal. Consequently, the coolest glass would not necessarily collect in the trough to any noticeable extent toward the forward end. Thus, an extra length of the trough toward the forward end wall would only generally increase heat loss and result in higher construction costs for the furnace. Toward the discharge end of the tank 22, convection currents are more pronounced (Fig. 3) with the coolest glass collecting in the trough 42, thus reducing the cooling requirements for the glass flowing in a stream through the trough 42.
:lOqZ166 Cooling means are provided for the trough 42 to enable the cooling effect on the glass flowing through the trough to change as the throughput changes. In a preferred form, the cooling means in accordance with the invention are indicated at 54 and include a main duct 56 extending longitudinally of the trough 42 and a plurality of branch outlets 58 communicating therewith and directing a cooling medium, specifically air, toward the bottom 50 of the wall means 44. The cooling medium or air can be supplied by a suitable blower 60 (Fig. 1), with the volume of the air controlled by a damper or valve 62. The flow-control damper 62 can be opened more as the throughput of the furnace 10 increases and the glass discharged therefrom tends to increase in temperature. A higher volume of the air is then directed through the outlets 58 toward the bottom 50 of the trough thereby to increase the dissipation of heat from the trough and produce a greater cooling effect on the molten glass flowing therethrough.
The damper 62 can be automatically controlled, if desired. For this purpose, a temperature-sensing device or thermocouple 64 is located in the trough 42 toward the down-stream end thereof with the device 64 being connected to a temperature controller 66. This, in turn, operates a control motor 68 which is operatively connected to the damper 62 so as to tend to close the damper 62 as the temperature sensed by the thermocouple 64 decreases and to open the damper 62 as the temperature sensed by the thermocouple 64 increases. The com-ponents 64, 66 and 68 are commercially-available devices and are not discussed in detail.
-, lOqZ166 Also, in accordance with the invention, a plurality of short electrodes 70 can be located in the trough 42, extending upwardly through the bottom 50 of the wall means 44. By them-selves, the electrodes 70 are heat-conducting elements which can serve to cool the glass by conducting heat in the glass in the trough 42 to ambient conditions below the tank 22. If desired, each of the electrodes 70 can be provided with a gear drive 72 (Fig. 4) and a motor 74, by means of which the electrodes 70 can be raised so as to protrude further into the trough 42, or lowered so as to have a shorter length immersed in the trough.
With this arrangement, the extent of the cooling effect of the electrodes 70 can be controlled. As the extent of protrusion of the electrodes into the trough increases, the cooling effect of the electrodes on the glass flowing through the trough also increases, as long as a sufficient portion of the length remains exposed so as to dissipate heat adequately. The streams of cooling air supplied by the outlets 58 can be directed at the exposed portions of the electrodes 70 below the bottom 50, if desired, to increase the Eate of conduction of heat away from the glass in the trough by means of the electrodes.
If desired, the electrodes 70 can also be connected to a power supply as indicated in Fig. 4, preferably an emer-gency power supply. In the event of a main power failure for the electrodes 34, the emergency power supply can be used to heat the electrodes 70 and thereby maintain the glass in the trough 42 in a molten condition under emergency conditions.
g _
Claims (6)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:-
1. A furnace for melting a heat-softenable material, said furnace comprising a tank for holding molten material, means extending into the molten material below the surface thereof for supplying heat to the molten material, wall means forming a cool-ing trough located in the bottom of the tank and extending therebeyond to discharge molten material from the tank, said wall means being exposed to ambient conditions below the bottom of said tank and structured to facilitate dissipation of heat from molten material in said trough through said wall means and cooling means extending along said trough and effective to supply a cooling medium in heat exchange relationship with an external surface of said wall means.
2. A furnace for melting a heat-softenable material accord-ing to claim 1 including a plurality of electrodes extending in-to said trough and being capable of conducting heat away from molten material in said trough to ambient conditions below said tank bottom.
3. A furnace according to claim 2 wherein said cooling means is effective to supply a cooling medium in heat exchange rela-tionship with exposed portions of the electrodes below the tank bottom.
4. A furnace according to claim 1, 2 or 3 and comprising means for varying the quantity of the cooling medium supplied by said cooling means.
5. A furnace according to claim 1, 2 or 3 wherein said trough is located centrally in the bottom of the tank.
6. A furnace for melting a heat-softenable material, said furnace comprising a tank for holding molten material, means extending into the molten material below the surface thereof for supplying heat to the molten material, wall means forming a cooling trough located in the bottom of the tank and extending therebeyond to discharge molten material from the tank, said trough being located centrally in the bottom of the tank, and extending not more than about one-half of the length of the tank bottom, said wall means being exposed on the sides and the bottom to ambient conditions below the bottom of said tank to dissipate heat from molten material in said trough, cooling means extending along said trough and effective to supply a cooling medium in heat exchange relationship with an external surface of said wall means, and means for varying the quantity of the cooling medium carried by said cooling means.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA308,287A CA1072166A (en) | 1974-02-22 | 1978-07-27 | Electrically-heated melting furnace with a cooling trough |
Applications Claiming Priority (4)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US445037A US3897234A (en) | 1974-02-22 | 1974-02-22 | Method and apparatus for cooling electrically-heated melting furnace |
| US445036A US3891422A (en) | 1974-02-22 | 1974-02-22 | Electrically-heated melting furnace with melt cooling means |
| CA75218380A CA1048273A (en) | 1974-02-22 | 1975-01-21 | Electrically-heated melting furnace with a cooling trough |
| CA308,287A CA1072166A (en) | 1974-02-22 | 1978-07-27 | Electrically-heated melting furnace with a cooling trough |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1072166A true CA1072166A (en) | 1980-02-19 |
Family
ID=27425817
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA308,287A Expired CA1072166A (en) | 1974-02-22 | 1978-07-27 | Electrically-heated melting furnace with a cooling trough |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1072166A (en) |
-
1978
- 1978-07-27 CA CA308,287A patent/CA1072166A/en not_active Expired
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| RU2695731C1 (en) | Glass melting furnace | |
| FI76777B (en) | FOERFARANDE FOER UPPVAERMNING AV SMAELT GLAS SAMT ELEKTRISKT UPPVAERMBAR GLASUPPVAERMNINGSAPPARAT. | |
| JPS6327295B2 (en) | ||
| CN1040569A (en) | Make the method and apparatus of mineral wool | |
| AU577714B2 (en) | Electric heating of glass forehearth | |
| US3897234A (en) | Method and apparatus for cooling electrically-heated melting furnace | |
| JP2010513183A (en) | Apparatus and method for controlling temperature of glass molding material in fore furnace | |
| US2280101A (en) | Electric furnace and melting method | |
| CA1263537A (en) | Flow control system for a glass melter | |
| US1820248A (en) | Glass making furnace and method | |
| US2225616A (en) | Electric furnace for melting glass | |
| US5062118A (en) | Electric melting furnace for vitrifying waste | |
| US3891422A (en) | Electrically-heated melting furnace with melt cooling means | |
| CA1072166A (en) | Electrically-heated melting furnace with a cooling trough | |
| CA1048273A (en) | Electrically-heated melting furnace with a cooling trough | |
| US2277679A (en) | Electric furnace for melting glass | |
| JPS63185831A (en) | Electric melting apparatus | |
| US3979197A (en) | Method of operating glass melting furnace | |
| CA1063353A (en) | Method and apparatus for making molten glass | |
| US4514851A (en) | Arc circuit electrodes for arc glass-melting furnace | |
| US4224460A (en) | Electrode heating device for use in glass melting furnaces | |
| CA1060658A (en) | Refining molten glass | |
| CA1049078A (en) | Apparatus for processing high temperature batch material | |
| KR102172552B1 (en) | Direct heating type melting device using heat exchange system | |
| CA1065610A (en) | Method and apparatus for making molten glass |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |