CA1137302A - Ladle heating system - Google Patents
Ladle heating systemInfo
- Publication number
- CA1137302A CA1137302A CA000348173A CA348173A CA1137302A CA 1137302 A CA1137302 A CA 1137302A CA 000348173 A CA000348173 A CA 000348173A CA 348173 A CA348173 A CA 348173A CA 1137302 A CA1137302 A CA 1137302A
- Authority
- CA
- Canada
- Prior art keywords
- ladle
- heat exchanger
- air
- rim
- fuel
- 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
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
- B22D41/00—Casting melt-holding vessels, e.g. ladles, tundishes, cups or the like
- B22D41/005—Casting melt-holding vessels, e.g. ladles, tundishes, cups or the like with heating or cooling means
- B22D41/01—Heating means
- B22D41/015—Heating means with external heating, i.e. the heat source not being a part of the ladle
Abstract
LADLE HEATING SYSTEM
Abstract of the Disclosure Prior to the receipt of a charge of molten metal, a ladle is heated by a direct flame, by applying a seal to the rim of the ladle and directing air through a heat exchanger and to the ladle, mixing fuel with the air and igniting the mixture and directing the flame in to the ladle chamber, and exhausting the gases of combustion from the ladle chamber back through the heat exchanger. The seal applied to the rim of the ladle comprises a network of refractory fibers mounted in a common plane. In one embodiment the fibers are formed in modules and the modules each comprise a rectangular block formed in an accordion folded arrangement, and the modules are mounted with their folded edges exposed, and with the folds of each module extending at right angles with respect to the folds of the adjacent modules.
Abstract of the Disclosure Prior to the receipt of a charge of molten metal, a ladle is heated by a direct flame, by applying a seal to the rim of the ladle and directing air through a heat exchanger and to the ladle, mixing fuel with the air and igniting the mixture and directing the flame in to the ladle chamber, and exhausting the gases of combustion from the ladle chamber back through the heat exchanger. The seal applied to the rim of the ladle comprises a network of refractory fibers mounted in a common plane. In one embodiment the fibers are formed in modules and the modules each comprise a rectangular block formed in an accordion folded arrangement, and the modules are mounted with their folded edges exposed, and with the folds of each module extending at right angles with respect to the folds of the adjacent modules.
Description
LADLE ~EATING SYSTEM
Technical Field This invention relates to a ladle heating system wherein a flame is directed into the chamber of a ladle and the hot gases are exhausted from the ladle through a heat exchanger which heats the oncoming air and fuel that forms the flame.
Background Art In the ferrous and nonferrous molten metals industries, ladles and similar metal receivers such as holding vessels and vacuum furnace chambers, receive a charge of molten metal. The receivers usually are lined with a refractory material, and it is desirable to preheat the receiver before molten metal is received in the receiver in order to avoid interface solidification of the metal upon contact between the metal and the cold interior surface of the receiver, and also to avoid thermal shock to the refractory liner of the receiver, thus avoiding deterioration of the liner.
A preheated ladle also minimizes the heat loss from the molten metal as the metal is transported in the ladle from the furnace to the pouring position, thereby assisting in maintaining the molten metal at a high enough temperature for use in a casting machine or mold.
A common prior art method for heating ladles and other molten metal receivers prior to charging them with molten metal is to direct an open natural gas flame into the open chamber of the ladle. The open flame heating method permits combustion gases from within the ladle chamber to escape to the surrounding atmosphere.
This permits a substantial amount of the heat energy to escape with-out effective use thereof, thus wasting an excessive amount of gas.
Moreover, it is difficult to uniformly heat a ladle with an open flame, in that the ladle may be overheated in some areas and not heated sufficiently in other areas. Additionally, after a ladle has been initially heated, it is sometimes desirable to maintain the ladle in its heated condition if the ladle achieves its desired temperature before it is time to introduce the molten metal to the ladle. In this situation the open flame hea~ing procedure continues to waste energy and hot spots are more likely to be formed in the ladle.
, , '~
11373(~2 Summary of the Invention In one aspect the invention comprehends a method of heating ladles and similar molten metal receivers comprising engaging the rim of the ladle with a seal of refractory fiber modules positioned substantially in a common plane with sufficient force to cause the rim of the ladle to be pressed into the seal and compress the fibers of the modules it e~gages, directing air through a heat exchanger and through the seal into the ladle, mixing fuel with the air and igniting the mixture as the mixture passes through the seal and into the ladle, and exhausting the gases from the ladle through the seal and through the heat exchanger.
Another aspect of the invention pertains to apparatus for heating ladles and similar molten metal receivers wherein a seal assembly is provided for movement into sealing abutment with the rim of the ladle, the seal assembly comprising a support frame and a layer of compressible refractory fiber material supported by the support frame and arranged in a configuration to engage the rim of the ladle and form a seal about the rim of the ladle.
The invention also comprehends an apparatus for heating a ladle having an open end, inc'uding seal means comprising ceramic fiber compaction material sized and shaped to engage the ladle about its open end and defining an opening therethrough. A ceramic heat exchanger defines an air inlet path and an exhaust outlet path for communicating through the opening of the seal means with the interior of the ladle. A fuel burner means is connected to the air inlet path for directing hot combustion gases through the opening of the seal means into the open end of the ladle. Variable fuel supply means provide for mixing fuel with air from the air inlet path and for supplying the mixture to the fuel burner means. Blower means move air along the air inlet path to the burner means. Thus, the seal means forms resilient contact with the open end of the ladle and air from the blower means moves through the heat exchanger, past the fuel supply means, through the fuel burner and through the opening of the seal means and forms a flame to heat the inside sur-faces of the ladle and the hot gases from inside the ladle move backthrough the seal means and through the heat exchanger to preheat the air moving from the blower means through the heat exchanger.
1137~Z
Still another aspect of the invention comprehends a method of heating a ladle having an open end including the steps of enclosing the open end of the ladle with a heat exchanger, the heat exchanger defining an exhaust outlet path communicating with the interior of the ladle and an air inlet path and heating air travel-ing along the air inlet path by mixing the air with fuel and burning the mixture in a fuel burner. The method further includes directing the heated air into the ladle, further heating the air traveling along the air inlet path with hot gases travelir.g in the exhaust outlet path in the heat exchanger prior to mixing the air with the fuel, measuring the amount of oxygen in the hot gases traveling along the exhaust outlet path, and in response to the amount of oxygen in the exhaust outlet path, regulating the fuel-air mixture provided to the fuel burner to maintain the amount of oxygen in the exhaust outlet path at a predetermined value. The invention also comprehends the apparatus for carrying out the method.
The invention in still a further aspect pertains to an apparatus for heating a ladle having an open end including a heat exchanger defining an air inlet path and an exhaust outlet path, and further defining an open end for matingly receiving and enclosing the open end of the ladle, the exhaust outlet path and the air inlet path communicating through the open end of the heat exchanger with the interior of the ladle. A fuel burner means is in communication with the air inlet path for directing hot combustion gases through the open end of the heat exchanger into the ladle and variable fuel supply means provide for mixing fuel with air from the air inlet path and for supplying the mixture to the fuel burner means. Blower means move air along the air inlet path to the burner means. The heat exchanger comprises a ceramic heat exchange means for receiving the hot combustion gases directly from the interior of the ladle.
A stainless steel heat exchange means communicates with the ceramic heat exchange means for receiving the hot combustion gases from the ceramic heat exchange means, and a carbon steel heat exchange means communicates with the stainless steel heat exchange means for receiv-ing the hot combustion gases from the stainless steel heat exchangemeans.' The air inlet path extends from the blower through the car-bon steel heat exchange means, then through the stainless steel heat ~r ^ - t, ~tr,~
exchange means, and then through the ceramic heat exchange means to the fuel burner means.
The invention also comprehends apparatus for heating ladles and similar molten metal receivers having a lid assembly for move-ment with respect to the ladle into sealing abutment with the rimof the ladle. The lid assembly comprises a support frame and a layer of compressible refractory fiber material supported by the support frame of a breadth greater than the rim of the ladle and substantially covering the face of the lid. Conduit means extend through the compressible refractory fiber material for exhausting gases from the ladle, and a burner extends through the compressible refractory fiber material for directing a flame into the ladle.
Thus, the lid assembly and the ladle are urged together with a force sufficient to cause the rim of the ladle to indent the compressible refractory fiber material and form a seal at the rim of the ladle.
A flame is directed from the burner into the ladle and gases are exhausted from the ladle through the conduit means, the compressible refractory fiber material shielding the lid assembly from the flame.
More particularly, the invention disclosed comprises an improved system for preheating ladles and similar molten metal receivers wherein a seal is applied to the rim of the ladle and air is directed through a heat exchanger and through the seal and mixed with a fuel to form a flame in the ladle chamber, and the gases from the flame are exhausted back through the seal and through the heat exchanger. The heat in the exhaust gases are partially recouperated in the heat exchanger by being transferred to the oncoming air, and the flame formed in the ladle chamber is controlled so as to wash the inner surfaces of the chamber with heat in a manner that tends to avoid hot and cold spots in the ladle. The exhaust gases are directed through an exhaust opening in the seal which is approximate-ly concentric with the ladle rim, thus further controlling the heat applied to the ladle. In one embodiment of the invention the seal formed against the ladle rim comprises a network of refractory fiber modules each formed from a web of refractory fibers, with the webs formed in an accordian fold, and the modules are arranged in a com-mon plane with the folds of each module arranged at a right angle with repect to the folds of the adjacent modules. The refractory 11373~1z fiber modules are maintained in compression by the seal support frame, and when the seal is pressed into abutment with the rim of the ladle, the modules tend to conform to the shape of the ladle rim and form a seal about the rim. The ability of the seal to be compressed tends to compensate for irregularities of the ladle rim as might be caused by a build up of slag or by chips or rough sur-faces present on the ladle rim.
In one embodiment of the invention the heat exchanger is shielded from direct radiation from the flame in the ladle chamber, and the heat exchanger comprises a multiple stage heat exchanger with the first exchanger that receives the hottest gases being fab-ricated of a material with a superior heat resistance than the sub-sequent ones of the heat exchangers.
The system of the invention further includes a means for sensing the temperature of the ladle and a means responsive to the temperature sensing means for adjusting the output of the fuel burner to maintain the ladle at a predetermined temperature. The system also includes a means for sensing the amount of oxygen pass-ing through the exhaust outlet path and a means responsive to the oxygen sensing means for adjusting the composition of the fuel-air mixture provided to the fuel burner by the variable fuel supply means to minimize the amount of unburned oxygen in the exhaust out-let path in order to maximi2e the efficiency of the combustion.
Such adjustments responsive to the temperature of the ladle and the amount of un-burned oxygen are interrelated in the system according to the invention so that the adjustment responsive to the unburned oxygen is made at whatever intensity the operation of the burner has been caused to assume by the adjustment means that is responsive to the ladle temperature. The ladle heating system according to the present invention thus has the advantages of energy efficiency re-sulting from careful control of fuel consumption, recovery of waste heat, and the ability to maintain a ladle at a desired elevated temperature with a minimum of energy consumption.
Other aspects, features and advantages of the present inven-tion will become apparent upon reading the following specification,when taken in conjunction with the accompanying drawings.
Brief Description of the Drawings Fig. 1 is a perspective illustration of a ladle and the ladle heater, with portions removed to illustrate the inside of the ladle and the ladle heater, illustrating the first embodiment of the `-` 11373~2 invention.
Fiq. 2 is a back view of the ladle heater of Fig. 1, with the carriage removed.
Fig. 3 is a side elevational view of the ladle heater of Fig. 1, with the carriage removed.
Fig. 4 is a front elevational view of the ladle heater of Fig. 1, with the carriage removed, showing the face of the seal assembly.
Fig. S is a detailed exploded perspective illustration of several of the refractory fiber modules and the upright seal support plate of the ladle heater of Fig. 1. appearing with Figure 3.
Pi~. 6 is a perspective illustration, similar to Fig. 1, but illustrating a second lS embodiment of the ladle heater.
Fig. 7 is a perspective illustration of a third embodiment of the ladle heater~ appearing with Fig. 4.
Fig. 8 is a schematic illustration of the control svstem for controlling the operation of the ladle heater of Figs. 1-7 Fig. 9 is a side elevational view, with portions illustrated in cross section, of a fourth embodiment of the ladle heater.
Fig. 10 is a side elevational view of a fifth embodiment of the ladle heater.
Fig. 11 is a schematic representation of the control system for controlling the operation of the ladle heaters of Figs. 9 and 10.
Detailed ~escription Referring now in more detail to the drawings, in which like numerals indicate like parts throughout the several views, Fia. 1 illustrates the ladle heater 10 for heating ladles such as ladle 11.
The ladle 11 is illustrated as resting on lts side on -` 1137302 support blocks 12 and shims 13, with its rim 14 facing to the side. The ladle 11 includes a chamber 15 lined with fire brick or other suitable heat resistant material. The rim 14 typically is circular in shape but can include a pouring spout or other non circular shapes. In some instances a build up of slag is present on the rim 14 of the ladle, or the ladle rim may be chipped or cracked or otherwise im~erfect in shape.
Ladle heater 10 includes a carriage 18 mounted on wheels 19 and the wheels are movable alonq tracks 20. Seal assembly 21 is mounted on carriage 18, a heat exchanger 22 is also mounted on carriage 18, blower 24 is mounted on carriage 18, and air conduit means 25 incl~des blower exhaust duct 26 which extends upwardly from blower 24, heat exchanger tubes 29, a second heat exchanger header 30 positioned on the other side of the heat exchange tubes 29, and branch conduit 31 and 32 extending downwardly ~from heater 29 and turning inwardly through seal assembly 21. Burners 35 and 36 communicate with the air conduit means 25 at the intersection of the branch conduits 31 and 32 with the seal assembly 21. A filter 34 is mounted on the inlet of blower 24.
An exhaust gas conduit means 38 defines an opening 39 through seal assembly 21 between burners 35 and 36 and duct work 40 that extends first in a horizontal leg 41 from opening 39 and then in a vertical leg 42 upwardly to heat exchanger 22, and then an exhaust duct 44 extends upwardly from the heat exchanger and directs the exhaust gases away from the lade heater. A damper 45 is located in exhaust duct 44 and is arranged to selectively block 1137;~Z
or restrict the movement of gases throuqh the exhaust gas con2uit means. It will be noted that the heat exchanger 22 is remotely located from opening 39 of exhaust gas conduit means 38 whereby the flames in the chamber 15 of ladle 11 do not directly radiate heat to the heat exchanger. Also, the duct work 40 of the exhaust gas conduit means is heat insulated.
The framework 46 is mounted on carriage 18 and includes various upright, horizontal and diagonal support beams for supporting the seal assembly 21, heat exchanger 22 and air conduit means and exhaust gas conduit means and their related components.
As illustrated in Figs. 2 and 3, seal assembly 21 comprises a support frame 48 that includes upright side frame elements 49 and 50, upper horizontal frame element 51 and lower horizontal frame element 52. Upriaht steel support plate S4 has its edges in abutment with frame elements 49-52.
Frame elements 49-52 are channel members, each have one flange in abutment with the upright steel plate 54 and the outer flanges thereof located in a common plane and forming a frame rim. A network of refractory fiber modules or insulating blocks 55 are mounted in support frame 48, forming a surface of refractory fibers inside the frame elements. The refractory fiber modules 55 that are adjacent frame elements 49-52 are partially confined in the flanges of the channel shaped beams 49-52, and each module 55 is attached to upright steel support plate 54.
Each refractory fiber module or batt 55 (Fiq. 5) is formed from a weh or blanket of refractory fibers, and the webs are in the form of elongated sheets. The sheets are folded in a zig-zag or an accordion arrangement so as to include a series ~1373(~2 _ of layers 56 with exposed side edges 58 and folds 59 on a front surface and similar folds 60 on the back surface of the modules. The modules 55 are rectangular in shape and are each maintained in their accordion folded configuration by bands wrapped around the module until the modules are mounted in the support frame 48, whereupon the bands are removed. The bands tend to hold the modules in compression until the bands are removed. The modules each include support rods 61 extending between the layers 56 at the folds 60 at the back surface of the module with connecting tabs 62 extending therefrom and projecting through the blanket at a fold 60. A
channel-shaped connector bracket 63 defines slots therethrough for receiving the tabs 62 of the support rods and when the tabs are inserted through an opening they are bent so that the bracket 63 is secured to the module. The channel of the channel-shaped bracket is then attached to a p{ojection 64 mounted on the upright support plate 54 to secure the module to the support frame 48. A more detailed descriPtion of a similar insulating block is found in U.S. Patent 4,001,996.
The modules 55 are pac~ed within the confines of the support frame. After they have been properly positioned and packed in the support frame, their straps (not shown) are removed, and the modules tend to remain in compression due to their abutment with one another. It will be noted that the folds 59 of each module 55 are oriented at a right angle with respect to the folds of the next adjacent modules.
Thus, a parket or alternating fold effect is created across the network of the seal assembly. The layers 56 are each approximately cube-shaped and are, in the ~1373C~Z
o _ disclosed embodiment, approximately one foot square.
However, other dimensions and other shapes can be utilized if desired.
When the ladle heater 10 and a ladle 11 are moved into engagement with each other as shown in Fig. 1, the rim 14 of the ladle moves into abutment with the seal assembly 21. Since the seal assembly 21 includes a network of refractory fiber modules 55 each formed in an accordion arrangement as illustrated in Fig. 5, the rim 14 tends to penetrate or move into the surface of the seal assembly formed by the folds 59 of the refractory fiber webs. As the rim is forced against the modules 55, an indentation is made in the refractory fibers. The rim and seal assemhly are moved together with a force in excess of
Technical Field This invention relates to a ladle heating system wherein a flame is directed into the chamber of a ladle and the hot gases are exhausted from the ladle through a heat exchanger which heats the oncoming air and fuel that forms the flame.
Background Art In the ferrous and nonferrous molten metals industries, ladles and similar metal receivers such as holding vessels and vacuum furnace chambers, receive a charge of molten metal. The receivers usually are lined with a refractory material, and it is desirable to preheat the receiver before molten metal is received in the receiver in order to avoid interface solidification of the metal upon contact between the metal and the cold interior surface of the receiver, and also to avoid thermal shock to the refractory liner of the receiver, thus avoiding deterioration of the liner.
A preheated ladle also minimizes the heat loss from the molten metal as the metal is transported in the ladle from the furnace to the pouring position, thereby assisting in maintaining the molten metal at a high enough temperature for use in a casting machine or mold.
A common prior art method for heating ladles and other molten metal receivers prior to charging them with molten metal is to direct an open natural gas flame into the open chamber of the ladle. The open flame heating method permits combustion gases from within the ladle chamber to escape to the surrounding atmosphere.
This permits a substantial amount of the heat energy to escape with-out effective use thereof, thus wasting an excessive amount of gas.
Moreover, it is difficult to uniformly heat a ladle with an open flame, in that the ladle may be overheated in some areas and not heated sufficiently in other areas. Additionally, after a ladle has been initially heated, it is sometimes desirable to maintain the ladle in its heated condition if the ladle achieves its desired temperature before it is time to introduce the molten metal to the ladle. In this situation the open flame hea~ing procedure continues to waste energy and hot spots are more likely to be formed in the ladle.
, , '~
11373(~2 Summary of the Invention In one aspect the invention comprehends a method of heating ladles and similar molten metal receivers comprising engaging the rim of the ladle with a seal of refractory fiber modules positioned substantially in a common plane with sufficient force to cause the rim of the ladle to be pressed into the seal and compress the fibers of the modules it e~gages, directing air through a heat exchanger and through the seal into the ladle, mixing fuel with the air and igniting the mixture as the mixture passes through the seal and into the ladle, and exhausting the gases from the ladle through the seal and through the heat exchanger.
Another aspect of the invention pertains to apparatus for heating ladles and similar molten metal receivers wherein a seal assembly is provided for movement into sealing abutment with the rim of the ladle, the seal assembly comprising a support frame and a layer of compressible refractory fiber material supported by the support frame and arranged in a configuration to engage the rim of the ladle and form a seal about the rim of the ladle.
The invention also comprehends an apparatus for heating a ladle having an open end, inc'uding seal means comprising ceramic fiber compaction material sized and shaped to engage the ladle about its open end and defining an opening therethrough. A ceramic heat exchanger defines an air inlet path and an exhaust outlet path for communicating through the opening of the seal means with the interior of the ladle. A fuel burner means is connected to the air inlet path for directing hot combustion gases through the opening of the seal means into the open end of the ladle. Variable fuel supply means provide for mixing fuel with air from the air inlet path and for supplying the mixture to the fuel burner means. Blower means move air along the air inlet path to the burner means. Thus, the seal means forms resilient contact with the open end of the ladle and air from the blower means moves through the heat exchanger, past the fuel supply means, through the fuel burner and through the opening of the seal means and forms a flame to heat the inside sur-faces of the ladle and the hot gases from inside the ladle move backthrough the seal means and through the heat exchanger to preheat the air moving from the blower means through the heat exchanger.
1137~Z
Still another aspect of the invention comprehends a method of heating a ladle having an open end including the steps of enclosing the open end of the ladle with a heat exchanger, the heat exchanger defining an exhaust outlet path communicating with the interior of the ladle and an air inlet path and heating air travel-ing along the air inlet path by mixing the air with fuel and burning the mixture in a fuel burner. The method further includes directing the heated air into the ladle, further heating the air traveling along the air inlet path with hot gases travelir.g in the exhaust outlet path in the heat exchanger prior to mixing the air with the fuel, measuring the amount of oxygen in the hot gases traveling along the exhaust outlet path, and in response to the amount of oxygen in the exhaust outlet path, regulating the fuel-air mixture provided to the fuel burner to maintain the amount of oxygen in the exhaust outlet path at a predetermined value. The invention also comprehends the apparatus for carrying out the method.
The invention in still a further aspect pertains to an apparatus for heating a ladle having an open end including a heat exchanger defining an air inlet path and an exhaust outlet path, and further defining an open end for matingly receiving and enclosing the open end of the ladle, the exhaust outlet path and the air inlet path communicating through the open end of the heat exchanger with the interior of the ladle. A fuel burner means is in communication with the air inlet path for directing hot combustion gases through the open end of the heat exchanger into the ladle and variable fuel supply means provide for mixing fuel with air from the air inlet path and for supplying the mixture to the fuel burner means. Blower means move air along the air inlet path to the burner means. The heat exchanger comprises a ceramic heat exchange means for receiving the hot combustion gases directly from the interior of the ladle.
A stainless steel heat exchange means communicates with the ceramic heat exchange means for receiving the hot combustion gases from the ceramic heat exchange means, and a carbon steel heat exchange means communicates with the stainless steel heat exchange means for receiv-ing the hot combustion gases from the stainless steel heat exchangemeans.' The air inlet path extends from the blower through the car-bon steel heat exchange means, then through the stainless steel heat ~r ^ - t, ~tr,~
exchange means, and then through the ceramic heat exchange means to the fuel burner means.
The invention also comprehends apparatus for heating ladles and similar molten metal receivers having a lid assembly for move-ment with respect to the ladle into sealing abutment with the rimof the ladle. The lid assembly comprises a support frame and a layer of compressible refractory fiber material supported by the support frame of a breadth greater than the rim of the ladle and substantially covering the face of the lid. Conduit means extend through the compressible refractory fiber material for exhausting gases from the ladle, and a burner extends through the compressible refractory fiber material for directing a flame into the ladle.
Thus, the lid assembly and the ladle are urged together with a force sufficient to cause the rim of the ladle to indent the compressible refractory fiber material and form a seal at the rim of the ladle.
A flame is directed from the burner into the ladle and gases are exhausted from the ladle through the conduit means, the compressible refractory fiber material shielding the lid assembly from the flame.
More particularly, the invention disclosed comprises an improved system for preheating ladles and similar molten metal receivers wherein a seal is applied to the rim of the ladle and air is directed through a heat exchanger and through the seal and mixed with a fuel to form a flame in the ladle chamber, and the gases from the flame are exhausted back through the seal and through the heat exchanger. The heat in the exhaust gases are partially recouperated in the heat exchanger by being transferred to the oncoming air, and the flame formed in the ladle chamber is controlled so as to wash the inner surfaces of the chamber with heat in a manner that tends to avoid hot and cold spots in the ladle. The exhaust gases are directed through an exhaust opening in the seal which is approximate-ly concentric with the ladle rim, thus further controlling the heat applied to the ladle. In one embodiment of the invention the seal formed against the ladle rim comprises a network of refractory fiber modules each formed from a web of refractory fibers, with the webs formed in an accordian fold, and the modules are arranged in a com-mon plane with the folds of each module arranged at a right angle with repect to the folds of the adjacent modules. The refractory 11373~1z fiber modules are maintained in compression by the seal support frame, and when the seal is pressed into abutment with the rim of the ladle, the modules tend to conform to the shape of the ladle rim and form a seal about the rim. The ability of the seal to be compressed tends to compensate for irregularities of the ladle rim as might be caused by a build up of slag or by chips or rough sur-faces present on the ladle rim.
In one embodiment of the invention the heat exchanger is shielded from direct radiation from the flame in the ladle chamber, and the heat exchanger comprises a multiple stage heat exchanger with the first exchanger that receives the hottest gases being fab-ricated of a material with a superior heat resistance than the sub-sequent ones of the heat exchangers.
The system of the invention further includes a means for sensing the temperature of the ladle and a means responsive to the temperature sensing means for adjusting the output of the fuel burner to maintain the ladle at a predetermined temperature. The system also includes a means for sensing the amount of oxygen pass-ing through the exhaust outlet path and a means responsive to the oxygen sensing means for adjusting the composition of the fuel-air mixture provided to the fuel burner by the variable fuel supply means to minimize the amount of unburned oxygen in the exhaust out-let path in order to maximi2e the efficiency of the combustion.
Such adjustments responsive to the temperature of the ladle and the amount of un-burned oxygen are interrelated in the system according to the invention so that the adjustment responsive to the unburned oxygen is made at whatever intensity the operation of the burner has been caused to assume by the adjustment means that is responsive to the ladle temperature. The ladle heating system according to the present invention thus has the advantages of energy efficiency re-sulting from careful control of fuel consumption, recovery of waste heat, and the ability to maintain a ladle at a desired elevated temperature with a minimum of energy consumption.
Other aspects, features and advantages of the present inven-tion will become apparent upon reading the following specification,when taken in conjunction with the accompanying drawings.
Brief Description of the Drawings Fig. 1 is a perspective illustration of a ladle and the ladle heater, with portions removed to illustrate the inside of the ladle and the ladle heater, illustrating the first embodiment of the `-` 11373~2 invention.
Fiq. 2 is a back view of the ladle heater of Fig. 1, with the carriage removed.
Fig. 3 is a side elevational view of the ladle heater of Fig. 1, with the carriage removed.
Fig. 4 is a front elevational view of the ladle heater of Fig. 1, with the carriage removed, showing the face of the seal assembly.
Fig. S is a detailed exploded perspective illustration of several of the refractory fiber modules and the upright seal support plate of the ladle heater of Fig. 1. appearing with Figure 3.
Pi~. 6 is a perspective illustration, similar to Fig. 1, but illustrating a second lS embodiment of the ladle heater.
Fig. 7 is a perspective illustration of a third embodiment of the ladle heater~ appearing with Fig. 4.
Fig. 8 is a schematic illustration of the control svstem for controlling the operation of the ladle heater of Figs. 1-7 Fig. 9 is a side elevational view, with portions illustrated in cross section, of a fourth embodiment of the ladle heater.
Fig. 10 is a side elevational view of a fifth embodiment of the ladle heater.
Fig. 11 is a schematic representation of the control system for controlling the operation of the ladle heaters of Figs. 9 and 10.
Detailed ~escription Referring now in more detail to the drawings, in which like numerals indicate like parts throughout the several views, Fia. 1 illustrates the ladle heater 10 for heating ladles such as ladle 11.
The ladle 11 is illustrated as resting on lts side on -` 1137302 support blocks 12 and shims 13, with its rim 14 facing to the side. The ladle 11 includes a chamber 15 lined with fire brick or other suitable heat resistant material. The rim 14 typically is circular in shape but can include a pouring spout or other non circular shapes. In some instances a build up of slag is present on the rim 14 of the ladle, or the ladle rim may be chipped or cracked or otherwise im~erfect in shape.
Ladle heater 10 includes a carriage 18 mounted on wheels 19 and the wheels are movable alonq tracks 20. Seal assembly 21 is mounted on carriage 18, a heat exchanger 22 is also mounted on carriage 18, blower 24 is mounted on carriage 18, and air conduit means 25 incl~des blower exhaust duct 26 which extends upwardly from blower 24, heat exchanger tubes 29, a second heat exchanger header 30 positioned on the other side of the heat exchange tubes 29, and branch conduit 31 and 32 extending downwardly ~from heater 29 and turning inwardly through seal assembly 21. Burners 35 and 36 communicate with the air conduit means 25 at the intersection of the branch conduits 31 and 32 with the seal assembly 21. A filter 34 is mounted on the inlet of blower 24.
An exhaust gas conduit means 38 defines an opening 39 through seal assembly 21 between burners 35 and 36 and duct work 40 that extends first in a horizontal leg 41 from opening 39 and then in a vertical leg 42 upwardly to heat exchanger 22, and then an exhaust duct 44 extends upwardly from the heat exchanger and directs the exhaust gases away from the lade heater. A damper 45 is located in exhaust duct 44 and is arranged to selectively block 1137;~Z
or restrict the movement of gases throuqh the exhaust gas con2uit means. It will be noted that the heat exchanger 22 is remotely located from opening 39 of exhaust gas conduit means 38 whereby the flames in the chamber 15 of ladle 11 do not directly radiate heat to the heat exchanger. Also, the duct work 40 of the exhaust gas conduit means is heat insulated.
The framework 46 is mounted on carriage 18 and includes various upright, horizontal and diagonal support beams for supporting the seal assembly 21, heat exchanger 22 and air conduit means and exhaust gas conduit means and their related components.
As illustrated in Figs. 2 and 3, seal assembly 21 comprises a support frame 48 that includes upright side frame elements 49 and 50, upper horizontal frame element 51 and lower horizontal frame element 52. Upriaht steel support plate S4 has its edges in abutment with frame elements 49-52.
Frame elements 49-52 are channel members, each have one flange in abutment with the upright steel plate 54 and the outer flanges thereof located in a common plane and forming a frame rim. A network of refractory fiber modules or insulating blocks 55 are mounted in support frame 48, forming a surface of refractory fibers inside the frame elements. The refractory fiber modules 55 that are adjacent frame elements 49-52 are partially confined in the flanges of the channel shaped beams 49-52, and each module 55 is attached to upright steel support plate 54.
Each refractory fiber module or batt 55 (Fiq. 5) is formed from a weh or blanket of refractory fibers, and the webs are in the form of elongated sheets. The sheets are folded in a zig-zag or an accordion arrangement so as to include a series ~1373(~2 _ of layers 56 with exposed side edges 58 and folds 59 on a front surface and similar folds 60 on the back surface of the modules. The modules 55 are rectangular in shape and are each maintained in their accordion folded configuration by bands wrapped around the module until the modules are mounted in the support frame 48, whereupon the bands are removed. The bands tend to hold the modules in compression until the bands are removed. The modules each include support rods 61 extending between the layers 56 at the folds 60 at the back surface of the module with connecting tabs 62 extending therefrom and projecting through the blanket at a fold 60. A
channel-shaped connector bracket 63 defines slots therethrough for receiving the tabs 62 of the support rods and when the tabs are inserted through an opening they are bent so that the bracket 63 is secured to the module. The channel of the channel-shaped bracket is then attached to a p{ojection 64 mounted on the upright support plate 54 to secure the module to the support frame 48. A more detailed descriPtion of a similar insulating block is found in U.S. Patent 4,001,996.
The modules 55 are pac~ed within the confines of the support frame. After they have been properly positioned and packed in the support frame, their straps (not shown) are removed, and the modules tend to remain in compression due to their abutment with one another. It will be noted that the folds 59 of each module 55 are oriented at a right angle with respect to the folds of the next adjacent modules.
Thus, a parket or alternating fold effect is created across the network of the seal assembly. The layers 56 are each approximately cube-shaped and are, in the ~1373C~Z
o _ disclosed embodiment, approximately one foot square.
However, other dimensions and other shapes can be utilized if desired.
When the ladle heater 10 and a ladle 11 are moved into engagement with each other as shown in Fig. 1, the rim 14 of the ladle moves into abutment with the seal assembly 21. Since the seal assembly 21 includes a network of refractory fiber modules 55 each formed in an accordion arrangement as illustrated in Fig. 5, the rim 14 tends to penetrate or move into the surface of the seal assembly formed by the folds 59 of the refractory fiber webs. As the rim is forced against the modules 55, an indentation is made in the refractory fibers. The rim and seal assemhly are moved together with a force in excess of
2 pounds per square inch, preferably with a force between 4 and 10 pounds per s~uare inch, so that the rim tends to penetrate the surface of the seal asembly and a good seal is made about the ladle rim.
The desired depth of indentation in the seal assembly is about three inches. The density of the refractory fiber modules is approximately 8 pounds per square inch. Thus, a firm seal is made about the ladle rim 14 and a substantial thickness of the refractory fiber material remains between the ladle rim and the upright steel plate 54 which supports the fiber modules 55.
~hose modules 55 that are not directly engaged by the rim o~ the ladle remain uncompressed
The desired depth of indentation in the seal assembly is about three inches. The density of the refractory fiber modules is approximately 8 pounds per square inch. Thus, a firm seal is made about the ladle rim 14 and a substantial thickness of the refractory fiber material remains between the ladle rim and the upright steel plate 54 which supports the fiber modules 55.
~hose modules 55 that are not directly engaged by the rim o~ the ladle remain uncompressed
3~ by the rim and tend to retain all of their heat resistance characteristics, thus closing off the ladle opening inside the rim of the ladle, so that the seal assembly functions as a lid or closure wall with respect to the chamber 15 of the ladle except -" 11373C~Z
_ for exhaust opening 39, and the openings through which the burners 35 and 36 are temperature probes or other elements project. By this arrangement the refractory fiber web material of the modules 55 shields the other components of the ladle heater from direct heat radiation from the flame inside the ladle.
Preferably, the ladle 11 and the seal assembly 21 will be positioned so that the opening 39 of the exhaust gas conduit means 38 is coaxially positioned with respect to the rim 14, thereby directing the exhaust gases out of the chamber 15 of the ladle through the middle of the opening formed by the ladle rim 14. Since the burners 35 and 36 are located on opposite sides of opening 39, the flames will be projected into the chamber on opposite sides of the exhaust opening 39. Preferably the burners 35 and 36 are constructed and arranged to direct the flames toward the central portion of the bottom of the ladle chamber 15, with the flames merging with each other at the bottom wall of the ladle, thus tending to completely wash the bottom surface of the ladle with flame. This tends to apply the hottest heat to the thicker bottom wall of the ladle, and the flame and gases of combustion tend to wash-back along the annular side wall of- the ladle and ultimately exit through the exhaust opening 39 and on through the exhaust gas conduit means 38. This tends to uniformly heat the ladle and the heat not transferred from the flame and gases to the ladle is moved with the gases through exhaust opening 39.
Reversible motor 53 is mounted on carriage 18 and is in driving relationship with respect to the wheels 19 of the platform and thus functions as a _ means for urging the seal assembly and the rim of the ladle in compressive relationshiP wtih respect to each other.
Heat exchan9er 22 is located at the upper portion of the ladle heater 10 where it is accessible for inspection and repair. This location of the heat exchanger also places it in a remote location with respect to the flame applied within the chamber 15 of the ladle 11, so that the heat exchanger is not in direct heat radiation with respect to the flame in the chamber. This protects the heat exchanger from the additional heat of radiation, while the heat exchanger is fully exposed to the heat of convection from the exhaust gases moving through the exhaust gas conduit means. The heat exchanger 22 is fabricated from ceramic materials so that it is capable of withstanding temperatures in excess of 2000F.
When the heating of the ladle has been accomplished by the ladle heater 10, the usual 2~ procedure is to extinguish the flame within the chamber 15 of the ladle by terminating the flow of fuel and air to the burners 35 and 36, to close damper 45 in the exhaust duct 44 and to move the ladle 11 and ladle heater 10 apart, whereupon the ladle can be turned to an upright attitude and transported to a position for filling with molten metal, etc. ~hen the damper 45 is closed, atmospheric air is substantially prevented from flowing through exhaust gas conduit means 3~ and through heat exchanger 22. This avoids rapid cooling of the heat exchanger 22, and thereby reduces the hazard of damage to the heat exchanger due to rapid contraction. Also, if the ladle heater 10 is to be used again within a short period, the heat exchanger -` 113730Z
22 will retain a substantial amount of its heat for its next cycle of operation.
As illustrated in Fig. 6, wherein a second embodiment of the invention is disclosed, the heat exchanger can be formed as a multiple stage heat exchanger wherein a first stage 65 is located relatively low in the exhaust gas conduit means 38 and one or more additional heat exchangers are located in sequence therewith. In the embodiment illustrated, an intermediate or second stage heat exchanger 66 is located above the first staqe heat exchanger, and an upper or third stage heater exchanger 67 is located above second staqe heat exchanger 66. The exhaust gases are directed in lS sequence through the first, second and third heat exchangers, with the first stage 65 receiving the hottest gases of combustion. The air from blower 24 passes first through the upper or third stage heat exchanger 67, then through duct 68 to the second stage heat exchanger 66, then through duct 69 through-the first stage heat exchanger 65, and then through branch conduits 31 and 32 to the burners 35 and 36.
Exhaust blower 24A is located above third stage heat exchangers 67 and induces a flow of hot gases from the ladle across the heat exchangers.
Preferably, first stage heat exchanger 65 is fabricated from ceramic materials which are capable of withstanding temperatures in excess of 2000F. The second and third heat exchangers 66 and 67 are fabricated from stainless steel and carbon steel respectively which are mateirals which are not capable of withstanding the high temperatures that the ceramic materials can withstand. For example, the ceramic heat exchanger is fabricated to withstand li37302 _ temperatures up to 2600-F, the stainless stee~ heat exchanger is fabricated to withstand temperatureS up to 1800F and the carbon steel heat exchanger is fabricated to withstand temperatures up to 1000F.
It is anticipated that the temperature of the gases exhausted from the third stage heat exchanger will be approximately 600F. The air moved from blower 24-is expected to be received in third stage heat exchanger 67 at a temperature of approximately lOO~F, will exit from the third stage heat exchanger and enter the second stage heat exchanger 66 at a temperature of approximately 5~0-F, and will exit from the second stage exchanger 66 and enter the first stage heat exchanger 55 at a temperature at approximately 1300F. The temperature of the air as it leaves the first stage heat exchanger 65 and approaches the burners will be approximately 2000F. While specific materials are disclosed from which the best exchangers can be fabricated, other materials can be used and different sizes, types and numbers of heat exchangers can be utilized, if desired.
As illustrated in Fig. 7, the seal assembly of the ladle heater can be reoriented from a vertical attitude to a horizontal attitude to engage the rim of an upright ladle. seal assembly 70 comprises a support ~rame 71 and a network of refactory fiber modules (not shown) similar to those illustrated in Figs. 4 and 5 are supported in the horizontal support frame. The support frame is movably mounted on upright threaded jack screws 72 and 73 and the exhaust gas conduit means 75 comp~ises duct work 76 that extends from the opening (not shown) in the seal assembly 70 to the heat exchanger 74, and exhaust duct 78 directs the exhaust gases from the heat .
''` 11373~Z
_ exchanqer 74 away from the ladle heater. Blower 7g directs air through conduit 80 to the upper header 81 of the heat exchanger, and the air is then directed down through the heat exchanger 74, lower header 82 and then through branch conduits such as conduit 84 to burners such as burner 85. The ladle heater of ~ig. 7 is mounted on a carriage 86 and carriage 86 is mounted on wheels 88 for movement along a track or the like. The reversible motor 89 is mounted on platform 18 and is arranged to drive the wheels of the ladle heater so that the ladle heater can be moved along the tracks 20 toward or away from a ladle. In the alternative, the ladle heater of Fig.
7 can be mounted in a stationar~ position if desired.
The jack screws function as a means for urging the seal assembly and the rim of the ladle in compressive relationship with respect to each other.
As illustrated in Fig. 8, a control system is provided for controlling the operation of the ladle heater illustrated in Figs. 1-4. Similar control systems are provided for ladle heaters of the type illustrated in Figs. 6 and 7. Air is directed from blower 24 through the air conduit means 25, through heat exchanger 22 and to burners 35 and 3~
and through seal assembly 21 to the ladle 11. Air control valve 90 regulates the flow of air from blower 24 through the air conduit means, and position controller 91 controls the position valve 90.
Position controller 91 is actuated by thermocouple 92 which detects the temperature of the exhaust gases moving through exhaust gas conduit means 38. Thus, when the temperature of the exhaust gases is higher than desired, position controller 91 and air control valve 90 function to reduce the amount of air movin~
11373(~2 to the ladle.
Fuel is directed through f~el line 94 from a supply under pressure and passes through high temperature shutoff valve 95 and flame out safety shut off solenoid valves 96 and 97 to burners 35 and 36. Ther~ocouple 99 senses the temperature of the exhaust gases flowing throu~h exhaust gas conduit means 38 and regulates shutoff valve 95. For example, when the temperature of exhaust gases is too hi~h, v21ve 95 is closed and the flames from both burners 35 and 36 are extinguished. Fuel regulator valve 100 is also positioned in fuel line 94. Fuel/
air regular 101 regulates the fuel valve 100, and its sensing conduit 102 communicates with air supply conduit means 25. Sensing conduit 102 includes a bleed line 104, and valve 105 regulates the bleed through bleed line 104. Position controller 106 - regulates bleed valve 105, and position controller 106 is regulated by oxygen sensor 108 and by oxygen transmitter 109. When an excessive amount of oxygen is detected in exhaust gas conduit means 38, oxygen ~ransmitter 109 causes position controller 106 to close valve 105, causing fuel air regulator 101 to further open fuel valve 100.- - This supplies additional fuel to burners 35 and 36, thus tending to provide sufficient fuel to complete the combustion of the oxygen supplied by the air to the ladle.
When the seal assembly 21 and ladle 11 are separated, differential pressure sensor 112 detects a change in pressure in exhaust gas conduit means 38, and differential pressure transmitter 114 activates position controller 115 to close exhaust damper 45, to prevent atmospheric air from passing through heat exchan~er 22.
_ Ultraviolet sensors 118 and 119 are mounted on each burner 35 and 36 and each functions to acuate its solenoid valve 120 or 121 in response to a flame out in its burner, thus immediately terminating the flow of fuel to its burner.
Referring now to Fig. 9, wherein another embodiment is illustrated, ladle 212 is placed on a support stand 218 with the ladle tippled 90 from its normal vertical orientation such that the open end 216 of the ladle opens in a horizontal direction. The ladle 212 can be a conventional ladle which includes a steel outer wall 214 and a refractory inner lining 215, which can be in the form of bricks.
The ladle heating system 210 according to this embodiment of the invention includes a heat exchanger and burner assembly 220 also having a refractory or otherwise heat-resistant inner lining 221. The heat exchanger and burner assem~ly 220 has an open end 222 defined by a mouth 224 opening in a horizontal direction at the side of the heat exchanger. The mouth 224 defines a mating opening for receiving the open end 216 of the ladle 212, and holds a circular seal 225 comprising a ceramic fiber compaction material. The material of the seal 225 gives somewhat when engaged by the open end 216 of the ladle 212 to prevent excessive leakage between the interior of the ladle and the outside atmosphere.
Ambient air is directed along an air inlet duct 228 by means of a blower 230 into the assembly 220. The air inlet duct 228 splits into two branches before entering the assembly 220, and the volume of air delivered by the blower 23n is reg~lated by a variable orifice valve 231 located prior to the branchinq of the duct 228. After entering the heat exchanger and burner assembly 220, the branches of the air inlet duct 228 are connected to a pair of heat exchange units 228 within the heat assembly 220, only one of which is visible in Fig. 9. ~ach heat exchange unit 229 includes an air inlet path and an exhaust outlet path. The air inlet path is connected to one of a pair of fuel burners 233 which are located within the assembly 220 and oriented to project a flame and combustion gases into the ladle 212 to uniformly heat the refractory lininq 215 of the ladle 212. The exhaust outlet path defined within each heat exchange unit 22g is open at 232 to the interior of the ladle 212. Within the openig 232 are located a conventional temperature probe 234, such as a thermocouple, and a conventional oxygen probe 235 which detects the amount of oxygen in the gases surrounding the probe by measuring the change in the electrical resistance of the gases. The exhaust outlet path defined within the heat exchange units 229 is also connected to an insulated exhaust duct 36 which communicates with the surrounding atmosphere either directly or through a filter or other pollution control device.
The boundaries between the air inlet path and the exhaust outlet path of the heat exchange units 229 must be constructed of material sufficient to withstand the heat of the com~ustion gases produced by the burners 233, which can be in excess of ~000F. A suitable heat recuperator for this purpose is a single pass cross-flow shell and tube heat exchanger with the interior components constructed of ceramic materials. A suitable burner for use in all the embodiments of the present 1~37~C~Z
invention is manufactured by Hague International, Inc. under the product designation "HI 'TRANSJET' Model 300", usina natural gas as a fuel and capable of a heat output of 5.8 x 16BTU/Hr. The burners 233 are supplied with natural gas from a gas supply 238 (shown diagramatically in Fig. 11) through a fuel supply line 239 which includes a main fuel control valve 240 and an oxygen responsive control valve 241 downstream from the main valve 240.
A schematic diaqram of the ladle heating system of the invention including the control system utilized to operate the ladle heating system 210 of the present invention is shown in Fig. 11. Signals are received from the temperature probe 234 at a temperature controller circuit 248. The construction of a controller circuit 248 to perform the functions required is within the capability of those skilled in the art, and is commercially available. The circuit 248 monitors the temperature signal from the temperature probe 234 and compares it to a predetermined temperature. The predetermined temperature is arriaved at by correlating empirical measurements of the actual temperature of the ladle 212 and the temperature measured by the probe 234 at the opening 232 to the exhaust outlet path of the heat exchan~e unit 229, so that the predetermined temperature represents a ladle temperature e~ual to the temperature to which it is desired to heat the ladle prior to being char~ed with molten metal. The desired ladle temperature can range from 1600-2600F
depending on the type of molten metal to be placed in the ladle. When the temperature measured by the probe 234 exceeds the predetermined temperature, the controller circuit 248 initiates a starter 256 to 11373~2 operate a motor 257 for a short ?eriod of time. The motor 257 is mechanically linked bv a linkage 258 to both the air inlet valve 231 and the main fuel valve 240, and thus causes the valve 231 to decrease the amount of air traveling in the air inlet duct 228 and also causes the valve 240 in the fuel line 239 to decrease the amount of fuel being delivered to the burners 233. The temperature of the burner output is thereby decreased. Similarly, when the temperature measured by the temperature ~robe drops below the predetermined temperature, the control circuit 250 causes the valves 231 and 240 to increase the supply of air and fuel to the burners 233 by operating the motor 257 in a reverse direction.
The oxygen probe 235 located in the opening 232 of a heat exchange unit 299 sends a signal to an oxy~en controller circuit 249, which is operable to adjust the oxygen responsive valve 241 in the fuel line 231 in response to the oxygen probe 235. The oxygen controller circuit 249 is also within the capability of those skilled in the art, and is commercially available from ~aque International, Inc.
under the product desiqnation "OxSenn. Whenever the amount of oxygen in the combustion gases as measured by the oxygen probe 235 rises above a predetermined valve representina efficient combustion, the controller circuit 249 causes a starter 254 to operate a motor 255 for a short period of time. The motor 255 is connected via a mechanical linkage 259 to the valve 241 which is thereby mechanically opened somewhat to slightly increase the amount of fuel being delivered along the fuel supply line 239 to be mixed with air from the air inlet duct 288 and burned in the burners 233. Likewise, if the oxygen measured 11373~Z
by the probe 235 indicates that the fuel-air mixture is too rich relative to the predetermined value of oxygen content, the controller circuit 249 causes the valve 241 to decrease the amount of fuel supplied to the burners 233 by operating the motor 255 in a reverse direction.
The heat exchanger and burner assembly 220 also includes a flame out safety fuel shutdown system. An ultraviolet sensor 237, shown diagrammatically in Fig. 11, is located within the assembly 220 in suitable position to monitor the radiation emitted by the burners 233 when in operation. If for any reason the burner flame is extinguished while fuel is being supplied, the absence of radiation is sensed by the ultraviolet sensor 237 and a signal is received from the sensor 237 at a solenoid controller circuit 250. The circuit 250 is operatively connected to a solenoid operated valve 242 in the fuel supply line 239 and closes the valve 242 in response to the flame out signal from the sensor 237. The controller circuit 250 is of conventional construction and is commercially available.
The assembled heat exchanger and burner assembly 220, blower 230 and ducts 288 and 236 are mounted on a motorized transporter 244 which runs on wheels 245 along rails 246. The assembly 220 is selectively moved horizontally along the rails 246 by a propulsion means (not shown) of any conventional type known to those skilled in the art. Travel of ~he transporter 244 along the rails 246 is limited by an end stop 247.
In operation of the ladle heating system 210, a ladle 212 is first placed on its side on the stand 218 at the end of the rails 246 by any conventional means such as an overhead crane. The transporter 244, initially located in spaced relation from the end stop 247, is then moved horizontally until the transporter 244 rests against the end stop 247 and the seal 225 within the mouth 224 of the heat exchanger and burner assembly 220 is enqaged with the open end 216 of the ladle 212. At such time the ~operation of the blower 230 is initiated to deliver air along the inlet duct 228. After traveling through the inlet air path of the heat exchange units 229, the air is mixed with fuel from the fuel line 239 and the mixture is ignited in the burner. Flame and combustion gases from the burners 233 heat the refractory lining 215 of the ladle 212. The hot combustion gases escape from the interior of the ladle 212 through the opening 232 of the heat exchange units 229 into the exhaust outlet path of the heat exchange units 229.
While passing through the heat exchange units 229, the hot exhaust gases transfer heat to the inlet air passing through the inlet air path of the heat exchange units 229. Preheating of the inlet air before mixture with fuel for combustion makes the operation of the burners 233 more efficient. After passing through the exhaust outlet path of the heat exchange units 229, the hot combustion qases are exhausted through the exhaust conduit 236.
As the combustion gases pass over the oxygen Drobe 23~, the amount of oxygen in the combustion gases is monitored by the probe, and a signal providing such information is transmitted from the oxygen probe 239 to the oxygen controller circuit 249. I~ the amount of oxygen measured by the probe `- 113~ 2 235 is higher than a predetermined value, the controller circuit 249 causes the oxygen responsive valve 241 to allow more fuel to be mixed with the inlet air in order to more fully burn the oxygen in the inlet air. If the amount of oxygen measured by the probe 235 becomes too small, the fuel-air ratio is decreased to maintain optimum combustion condition in the burners 233.
The hot combustion gases also pass over the temperature probe 235 which monitors the temperature of the gases as they enter the heat exchange units 229. In response to the measured temperature rising above a predetermined value, the temperature controller circuit 248 lowers the output of the burners 233 by simultaneously gradually closing the blower valve 231 and the main fuel valve 240 in the fuel line 239. Thus, when the burners are initially ignited, they can run at full capacity and the relatively cool ladle 12 will rapidly absorb the heat of the combustion gases. As the ladle becomes heated, it will less readily absorb heat and the temperature probe 234 will rise. For example, an unheated 55 ton ladle would accept heat initially at a rate of about eleven million BTU/Hr, but would eventually reach a stabilized condition. In such a condition only about two million BTU/Hr are required to maintain the elevated temperature of the ladle.
By maintaining the temperature of the combustion gases at the predetermined value, the control system of the present invention heats the ladle 212 at the maximum rate possible, while maintaining energy efficiency by operating the burners 233 to provide the maximum level of heat which ~he ladle 212 can absorb at any particular time 1137~0Z
_ during the heating of the ladle. The intensity of the burners it thus gradually throttled down from maximum output to minimum output, during the course of a typical ladle heating operation. If, during a holding period after the ladle has been heated to the required temperature for receipt of molten metal, the temperature of the combustion aases drops below the predtermined value, the controller circuit 248 causes the valve 231 and 240 to increase the intensity of the burner and thereby maintain the ladle in its heated state.
It will be seen that the control system is designed so that the fine tuning of the fuel-air ratio provided by the oxygen controller 249 operates effectively at whatever `level of intensity the burners 233 assume in response to the temperature of the combustion gases as measured by the temperature probe 235 and regulated by the temperature controller 248.
When the ladle has reached the desired temperature and is needed to receive a charge of molten metal, the transporter 244 is moved horizontally along the rails 246 to remove the heat exchanger 220 from engagement with the open end 216 of the ladle 212. The ladle 212 may then be removed from the stand 218 and delivered to a station for receiving molten metal from a furnace. It should be understood that the ladle heating system 210 could alternatively be fixed in position, and that the transporter would be located to convey the ladle 212 between the position shown in Fig. 9 engaging the heat exchanger, and a position spaced apart from the fixed system for enaagement by an overhead crane or the like. Moreovert the ladle heating system 210 can 11373(~Z
alternatively be oriented vertically so as to receive a ladle in upright position; suitable manipulating apparatus would be required to move the system and/or the ladle into and out of contact.
Another embodiment of the present invention is shown in Fig. 10, which depicts a ladle heating apparatus 260. The ladle heating apparatus 260 is similar in all respects to the apparatus shown in Fig. 9, ~ith the exception that two additional heat exchangers, a stainless steel heat exchanger 252 and a carbon steel heat exchanger 253, are included in the system. Thus, the blower 230 delivers air through an inlet conduit 228a to an inlet air path within the heat exchanger 253, through a connecting inlet duct 228b to an inlet air path within the heat exchanger 252, and thereafter through an inlet air duct 228c to the ceramic heat exchanger and burner assembly 220 which includes the burners 233 and engages the ladle 212. After heating inlet gases in the assembly 220, the hot combustion gases pass through an exhaust duct 236a to the exhaust path of the stainless steel heat exchanger 252, through exhaust ducts 236b and 236c to the exhaust path within the carbon steel heat exchanger 253, and thereafter are exhausted to atmopshere through a duct 262. The three heat exchangers of the embodiment shown in Fig. 10 cooperate to recuperate as much waste heat as possible from the combustion gases leaving the ladle 212. The ceramic heat exchanger and burner assembly 220 is constucted of materials capable of withstanding the combustion gas temperatures, which are in excess of 2000F, and transfers heat ~rom such gases to the inlet air stream. The stainless steel heat exchanger is capable of withstandinq the exhaust gases of intermediate temperature after heat has been extracted therefrom by the ceramic heat exchanger.
Similarly, the carbon steel heat exchanger 253 is efficient in transferring heat from the relatively low temperature exhaust gases prior to exhausting said gases to the atmosphere. Operation of the embodiment of the invention shown in Fig. 10 is essentially similar to that described for the embodiment shown in Fig. 9.
Now that the ladle heating system according to the invention has been described in detail, it will be understood by those skilled in the art that the principles of waste heat recuperation and heating control may be applied to systems utilizing heat sources other than natural gas flame burners.
Although the foregoing description realtes to apparatus and methods of heating ladles, it should be understood that various other objects can be heated with the disclosed apparatus and method. It should ~e understood, of course, that the foregoing relates only to preferred embodiments of the present invention and that numerous modifications or alterations may be made therein without departing from the spirit and scope of the invention as set forth in the appended claims.
_ for exhaust opening 39, and the openings through which the burners 35 and 36 are temperature probes or other elements project. By this arrangement the refractory fiber web material of the modules 55 shields the other components of the ladle heater from direct heat radiation from the flame inside the ladle.
Preferably, the ladle 11 and the seal assembly 21 will be positioned so that the opening 39 of the exhaust gas conduit means 38 is coaxially positioned with respect to the rim 14, thereby directing the exhaust gases out of the chamber 15 of the ladle through the middle of the opening formed by the ladle rim 14. Since the burners 35 and 36 are located on opposite sides of opening 39, the flames will be projected into the chamber on opposite sides of the exhaust opening 39. Preferably the burners 35 and 36 are constructed and arranged to direct the flames toward the central portion of the bottom of the ladle chamber 15, with the flames merging with each other at the bottom wall of the ladle, thus tending to completely wash the bottom surface of the ladle with flame. This tends to apply the hottest heat to the thicker bottom wall of the ladle, and the flame and gases of combustion tend to wash-back along the annular side wall of- the ladle and ultimately exit through the exhaust opening 39 and on through the exhaust gas conduit means 38. This tends to uniformly heat the ladle and the heat not transferred from the flame and gases to the ladle is moved with the gases through exhaust opening 39.
Reversible motor 53 is mounted on carriage 18 and is in driving relationship with respect to the wheels 19 of the platform and thus functions as a _ means for urging the seal assembly and the rim of the ladle in compressive relationshiP wtih respect to each other.
Heat exchan9er 22 is located at the upper portion of the ladle heater 10 where it is accessible for inspection and repair. This location of the heat exchanger also places it in a remote location with respect to the flame applied within the chamber 15 of the ladle 11, so that the heat exchanger is not in direct heat radiation with respect to the flame in the chamber. This protects the heat exchanger from the additional heat of radiation, while the heat exchanger is fully exposed to the heat of convection from the exhaust gases moving through the exhaust gas conduit means. The heat exchanger 22 is fabricated from ceramic materials so that it is capable of withstanding temperatures in excess of 2000F.
When the heating of the ladle has been accomplished by the ladle heater 10, the usual 2~ procedure is to extinguish the flame within the chamber 15 of the ladle by terminating the flow of fuel and air to the burners 35 and 36, to close damper 45 in the exhaust duct 44 and to move the ladle 11 and ladle heater 10 apart, whereupon the ladle can be turned to an upright attitude and transported to a position for filling with molten metal, etc. ~hen the damper 45 is closed, atmospheric air is substantially prevented from flowing through exhaust gas conduit means 3~ and through heat exchanger 22. This avoids rapid cooling of the heat exchanger 22, and thereby reduces the hazard of damage to the heat exchanger due to rapid contraction. Also, if the ladle heater 10 is to be used again within a short period, the heat exchanger -` 113730Z
22 will retain a substantial amount of its heat for its next cycle of operation.
As illustrated in Fig. 6, wherein a second embodiment of the invention is disclosed, the heat exchanger can be formed as a multiple stage heat exchanger wherein a first stage 65 is located relatively low in the exhaust gas conduit means 38 and one or more additional heat exchangers are located in sequence therewith. In the embodiment illustrated, an intermediate or second stage heat exchanger 66 is located above the first staqe heat exchanger, and an upper or third stage heater exchanger 67 is located above second staqe heat exchanger 66. The exhaust gases are directed in lS sequence through the first, second and third heat exchangers, with the first stage 65 receiving the hottest gases of combustion. The air from blower 24 passes first through the upper or third stage heat exchanger 67, then through duct 68 to the second stage heat exchanger 66, then through duct 69 through-the first stage heat exchanger 65, and then through branch conduits 31 and 32 to the burners 35 and 36.
Exhaust blower 24A is located above third stage heat exchangers 67 and induces a flow of hot gases from the ladle across the heat exchangers.
Preferably, first stage heat exchanger 65 is fabricated from ceramic materials which are capable of withstanding temperatures in excess of 2000F. The second and third heat exchangers 66 and 67 are fabricated from stainless steel and carbon steel respectively which are mateirals which are not capable of withstanding the high temperatures that the ceramic materials can withstand. For example, the ceramic heat exchanger is fabricated to withstand li37302 _ temperatures up to 2600-F, the stainless stee~ heat exchanger is fabricated to withstand temperatureS up to 1800F and the carbon steel heat exchanger is fabricated to withstand temperatures up to 1000F.
It is anticipated that the temperature of the gases exhausted from the third stage heat exchanger will be approximately 600F. The air moved from blower 24-is expected to be received in third stage heat exchanger 67 at a temperature of approximately lOO~F, will exit from the third stage heat exchanger and enter the second stage heat exchanger 66 at a temperature of approximately 5~0-F, and will exit from the second stage exchanger 66 and enter the first stage heat exchanger 55 at a temperature at approximately 1300F. The temperature of the air as it leaves the first stage heat exchanger 65 and approaches the burners will be approximately 2000F. While specific materials are disclosed from which the best exchangers can be fabricated, other materials can be used and different sizes, types and numbers of heat exchangers can be utilized, if desired.
As illustrated in Fig. 7, the seal assembly of the ladle heater can be reoriented from a vertical attitude to a horizontal attitude to engage the rim of an upright ladle. seal assembly 70 comprises a support ~rame 71 and a network of refactory fiber modules (not shown) similar to those illustrated in Figs. 4 and 5 are supported in the horizontal support frame. The support frame is movably mounted on upright threaded jack screws 72 and 73 and the exhaust gas conduit means 75 comp~ises duct work 76 that extends from the opening (not shown) in the seal assembly 70 to the heat exchanger 74, and exhaust duct 78 directs the exhaust gases from the heat .
''` 11373~Z
_ exchanqer 74 away from the ladle heater. Blower 7g directs air through conduit 80 to the upper header 81 of the heat exchanger, and the air is then directed down through the heat exchanger 74, lower header 82 and then through branch conduits such as conduit 84 to burners such as burner 85. The ladle heater of ~ig. 7 is mounted on a carriage 86 and carriage 86 is mounted on wheels 88 for movement along a track or the like. The reversible motor 89 is mounted on platform 18 and is arranged to drive the wheels of the ladle heater so that the ladle heater can be moved along the tracks 20 toward or away from a ladle. In the alternative, the ladle heater of Fig.
7 can be mounted in a stationar~ position if desired.
The jack screws function as a means for urging the seal assembly and the rim of the ladle in compressive relationship with respect to each other.
As illustrated in Fig. 8, a control system is provided for controlling the operation of the ladle heater illustrated in Figs. 1-4. Similar control systems are provided for ladle heaters of the type illustrated in Figs. 6 and 7. Air is directed from blower 24 through the air conduit means 25, through heat exchanger 22 and to burners 35 and 3~
and through seal assembly 21 to the ladle 11. Air control valve 90 regulates the flow of air from blower 24 through the air conduit means, and position controller 91 controls the position valve 90.
Position controller 91 is actuated by thermocouple 92 which detects the temperature of the exhaust gases moving through exhaust gas conduit means 38. Thus, when the temperature of the exhaust gases is higher than desired, position controller 91 and air control valve 90 function to reduce the amount of air movin~
11373(~2 to the ladle.
Fuel is directed through f~el line 94 from a supply under pressure and passes through high temperature shutoff valve 95 and flame out safety shut off solenoid valves 96 and 97 to burners 35 and 36. Ther~ocouple 99 senses the temperature of the exhaust gases flowing throu~h exhaust gas conduit means 38 and regulates shutoff valve 95. For example, when the temperature of exhaust gases is too hi~h, v21ve 95 is closed and the flames from both burners 35 and 36 are extinguished. Fuel regulator valve 100 is also positioned in fuel line 94. Fuel/
air regular 101 regulates the fuel valve 100, and its sensing conduit 102 communicates with air supply conduit means 25. Sensing conduit 102 includes a bleed line 104, and valve 105 regulates the bleed through bleed line 104. Position controller 106 - regulates bleed valve 105, and position controller 106 is regulated by oxygen sensor 108 and by oxygen transmitter 109. When an excessive amount of oxygen is detected in exhaust gas conduit means 38, oxygen ~ransmitter 109 causes position controller 106 to close valve 105, causing fuel air regulator 101 to further open fuel valve 100.- - This supplies additional fuel to burners 35 and 36, thus tending to provide sufficient fuel to complete the combustion of the oxygen supplied by the air to the ladle.
When the seal assembly 21 and ladle 11 are separated, differential pressure sensor 112 detects a change in pressure in exhaust gas conduit means 38, and differential pressure transmitter 114 activates position controller 115 to close exhaust damper 45, to prevent atmospheric air from passing through heat exchan~er 22.
_ Ultraviolet sensors 118 and 119 are mounted on each burner 35 and 36 and each functions to acuate its solenoid valve 120 or 121 in response to a flame out in its burner, thus immediately terminating the flow of fuel to its burner.
Referring now to Fig. 9, wherein another embodiment is illustrated, ladle 212 is placed on a support stand 218 with the ladle tippled 90 from its normal vertical orientation such that the open end 216 of the ladle opens in a horizontal direction. The ladle 212 can be a conventional ladle which includes a steel outer wall 214 and a refractory inner lining 215, which can be in the form of bricks.
The ladle heating system 210 according to this embodiment of the invention includes a heat exchanger and burner assembly 220 also having a refractory or otherwise heat-resistant inner lining 221. The heat exchanger and burner assem~ly 220 has an open end 222 defined by a mouth 224 opening in a horizontal direction at the side of the heat exchanger. The mouth 224 defines a mating opening for receiving the open end 216 of the ladle 212, and holds a circular seal 225 comprising a ceramic fiber compaction material. The material of the seal 225 gives somewhat when engaged by the open end 216 of the ladle 212 to prevent excessive leakage between the interior of the ladle and the outside atmosphere.
Ambient air is directed along an air inlet duct 228 by means of a blower 230 into the assembly 220. The air inlet duct 228 splits into two branches before entering the assembly 220, and the volume of air delivered by the blower 23n is reg~lated by a variable orifice valve 231 located prior to the branchinq of the duct 228. After entering the heat exchanger and burner assembly 220, the branches of the air inlet duct 228 are connected to a pair of heat exchange units 228 within the heat assembly 220, only one of which is visible in Fig. 9. ~ach heat exchange unit 229 includes an air inlet path and an exhaust outlet path. The air inlet path is connected to one of a pair of fuel burners 233 which are located within the assembly 220 and oriented to project a flame and combustion gases into the ladle 212 to uniformly heat the refractory lininq 215 of the ladle 212. The exhaust outlet path defined within each heat exchange unit 22g is open at 232 to the interior of the ladle 212. Within the openig 232 are located a conventional temperature probe 234, such as a thermocouple, and a conventional oxygen probe 235 which detects the amount of oxygen in the gases surrounding the probe by measuring the change in the electrical resistance of the gases. The exhaust outlet path defined within the heat exchange units 229 is also connected to an insulated exhaust duct 36 which communicates with the surrounding atmosphere either directly or through a filter or other pollution control device.
The boundaries between the air inlet path and the exhaust outlet path of the heat exchange units 229 must be constructed of material sufficient to withstand the heat of the com~ustion gases produced by the burners 233, which can be in excess of ~000F. A suitable heat recuperator for this purpose is a single pass cross-flow shell and tube heat exchanger with the interior components constructed of ceramic materials. A suitable burner for use in all the embodiments of the present 1~37~C~Z
invention is manufactured by Hague International, Inc. under the product designation "HI 'TRANSJET' Model 300", usina natural gas as a fuel and capable of a heat output of 5.8 x 16BTU/Hr. The burners 233 are supplied with natural gas from a gas supply 238 (shown diagramatically in Fig. 11) through a fuel supply line 239 which includes a main fuel control valve 240 and an oxygen responsive control valve 241 downstream from the main valve 240.
A schematic diaqram of the ladle heating system of the invention including the control system utilized to operate the ladle heating system 210 of the present invention is shown in Fig. 11. Signals are received from the temperature probe 234 at a temperature controller circuit 248. The construction of a controller circuit 248 to perform the functions required is within the capability of those skilled in the art, and is commercially available. The circuit 248 monitors the temperature signal from the temperature probe 234 and compares it to a predetermined temperature. The predetermined temperature is arriaved at by correlating empirical measurements of the actual temperature of the ladle 212 and the temperature measured by the probe 234 at the opening 232 to the exhaust outlet path of the heat exchan~e unit 229, so that the predetermined temperature represents a ladle temperature e~ual to the temperature to which it is desired to heat the ladle prior to being char~ed with molten metal. The desired ladle temperature can range from 1600-2600F
depending on the type of molten metal to be placed in the ladle. When the temperature measured by the probe 234 exceeds the predetermined temperature, the controller circuit 248 initiates a starter 256 to 11373~2 operate a motor 257 for a short ?eriod of time. The motor 257 is mechanically linked bv a linkage 258 to both the air inlet valve 231 and the main fuel valve 240, and thus causes the valve 231 to decrease the amount of air traveling in the air inlet duct 228 and also causes the valve 240 in the fuel line 239 to decrease the amount of fuel being delivered to the burners 233. The temperature of the burner output is thereby decreased. Similarly, when the temperature measured by the temperature ~robe drops below the predetermined temperature, the control circuit 250 causes the valves 231 and 240 to increase the supply of air and fuel to the burners 233 by operating the motor 257 in a reverse direction.
The oxygen probe 235 located in the opening 232 of a heat exchange unit 299 sends a signal to an oxy~en controller circuit 249, which is operable to adjust the oxygen responsive valve 241 in the fuel line 231 in response to the oxygen probe 235. The oxygen controller circuit 249 is also within the capability of those skilled in the art, and is commercially available from ~aque International, Inc.
under the product desiqnation "OxSenn. Whenever the amount of oxygen in the combustion gases as measured by the oxygen probe 235 rises above a predetermined valve representina efficient combustion, the controller circuit 249 causes a starter 254 to operate a motor 255 for a short period of time. The motor 255 is connected via a mechanical linkage 259 to the valve 241 which is thereby mechanically opened somewhat to slightly increase the amount of fuel being delivered along the fuel supply line 239 to be mixed with air from the air inlet duct 288 and burned in the burners 233. Likewise, if the oxygen measured 11373~Z
by the probe 235 indicates that the fuel-air mixture is too rich relative to the predetermined value of oxygen content, the controller circuit 249 causes the valve 241 to decrease the amount of fuel supplied to the burners 233 by operating the motor 255 in a reverse direction.
The heat exchanger and burner assembly 220 also includes a flame out safety fuel shutdown system. An ultraviolet sensor 237, shown diagrammatically in Fig. 11, is located within the assembly 220 in suitable position to monitor the radiation emitted by the burners 233 when in operation. If for any reason the burner flame is extinguished while fuel is being supplied, the absence of radiation is sensed by the ultraviolet sensor 237 and a signal is received from the sensor 237 at a solenoid controller circuit 250. The circuit 250 is operatively connected to a solenoid operated valve 242 in the fuel supply line 239 and closes the valve 242 in response to the flame out signal from the sensor 237. The controller circuit 250 is of conventional construction and is commercially available.
The assembled heat exchanger and burner assembly 220, blower 230 and ducts 288 and 236 are mounted on a motorized transporter 244 which runs on wheels 245 along rails 246. The assembly 220 is selectively moved horizontally along the rails 246 by a propulsion means (not shown) of any conventional type known to those skilled in the art. Travel of ~he transporter 244 along the rails 246 is limited by an end stop 247.
In operation of the ladle heating system 210, a ladle 212 is first placed on its side on the stand 218 at the end of the rails 246 by any conventional means such as an overhead crane. The transporter 244, initially located in spaced relation from the end stop 247, is then moved horizontally until the transporter 244 rests against the end stop 247 and the seal 225 within the mouth 224 of the heat exchanger and burner assembly 220 is enqaged with the open end 216 of the ladle 212. At such time the ~operation of the blower 230 is initiated to deliver air along the inlet duct 228. After traveling through the inlet air path of the heat exchange units 229, the air is mixed with fuel from the fuel line 239 and the mixture is ignited in the burner. Flame and combustion gases from the burners 233 heat the refractory lining 215 of the ladle 212. The hot combustion gases escape from the interior of the ladle 212 through the opening 232 of the heat exchange units 229 into the exhaust outlet path of the heat exchange units 229.
While passing through the heat exchange units 229, the hot exhaust gases transfer heat to the inlet air passing through the inlet air path of the heat exchange units 229. Preheating of the inlet air before mixture with fuel for combustion makes the operation of the burners 233 more efficient. After passing through the exhaust outlet path of the heat exchange units 229, the hot combustion qases are exhausted through the exhaust conduit 236.
As the combustion gases pass over the oxygen Drobe 23~, the amount of oxygen in the combustion gases is monitored by the probe, and a signal providing such information is transmitted from the oxygen probe 239 to the oxygen controller circuit 249. I~ the amount of oxygen measured by the probe `- 113~ 2 235 is higher than a predetermined value, the controller circuit 249 causes the oxygen responsive valve 241 to allow more fuel to be mixed with the inlet air in order to more fully burn the oxygen in the inlet air. If the amount of oxygen measured by the probe 235 becomes too small, the fuel-air ratio is decreased to maintain optimum combustion condition in the burners 233.
The hot combustion gases also pass over the temperature probe 235 which monitors the temperature of the gases as they enter the heat exchange units 229. In response to the measured temperature rising above a predetermined value, the temperature controller circuit 248 lowers the output of the burners 233 by simultaneously gradually closing the blower valve 231 and the main fuel valve 240 in the fuel line 239. Thus, when the burners are initially ignited, they can run at full capacity and the relatively cool ladle 12 will rapidly absorb the heat of the combustion gases. As the ladle becomes heated, it will less readily absorb heat and the temperature probe 234 will rise. For example, an unheated 55 ton ladle would accept heat initially at a rate of about eleven million BTU/Hr, but would eventually reach a stabilized condition. In such a condition only about two million BTU/Hr are required to maintain the elevated temperature of the ladle.
By maintaining the temperature of the combustion gases at the predetermined value, the control system of the present invention heats the ladle 212 at the maximum rate possible, while maintaining energy efficiency by operating the burners 233 to provide the maximum level of heat which ~he ladle 212 can absorb at any particular time 1137~0Z
_ during the heating of the ladle. The intensity of the burners it thus gradually throttled down from maximum output to minimum output, during the course of a typical ladle heating operation. If, during a holding period after the ladle has been heated to the required temperature for receipt of molten metal, the temperature of the combustion aases drops below the predtermined value, the controller circuit 248 causes the valve 231 and 240 to increase the intensity of the burner and thereby maintain the ladle in its heated state.
It will be seen that the control system is designed so that the fine tuning of the fuel-air ratio provided by the oxygen controller 249 operates effectively at whatever `level of intensity the burners 233 assume in response to the temperature of the combustion gases as measured by the temperature probe 235 and regulated by the temperature controller 248.
When the ladle has reached the desired temperature and is needed to receive a charge of molten metal, the transporter 244 is moved horizontally along the rails 246 to remove the heat exchanger 220 from engagement with the open end 216 of the ladle 212. The ladle 212 may then be removed from the stand 218 and delivered to a station for receiving molten metal from a furnace. It should be understood that the ladle heating system 210 could alternatively be fixed in position, and that the transporter would be located to convey the ladle 212 between the position shown in Fig. 9 engaging the heat exchanger, and a position spaced apart from the fixed system for enaagement by an overhead crane or the like. Moreovert the ladle heating system 210 can 11373(~Z
alternatively be oriented vertically so as to receive a ladle in upright position; suitable manipulating apparatus would be required to move the system and/or the ladle into and out of contact.
Another embodiment of the present invention is shown in Fig. 10, which depicts a ladle heating apparatus 260. The ladle heating apparatus 260 is similar in all respects to the apparatus shown in Fig. 9, ~ith the exception that two additional heat exchangers, a stainless steel heat exchanger 252 and a carbon steel heat exchanger 253, are included in the system. Thus, the blower 230 delivers air through an inlet conduit 228a to an inlet air path within the heat exchanger 253, through a connecting inlet duct 228b to an inlet air path within the heat exchanger 252, and thereafter through an inlet air duct 228c to the ceramic heat exchanger and burner assembly 220 which includes the burners 233 and engages the ladle 212. After heating inlet gases in the assembly 220, the hot combustion gases pass through an exhaust duct 236a to the exhaust path of the stainless steel heat exchanger 252, through exhaust ducts 236b and 236c to the exhaust path within the carbon steel heat exchanger 253, and thereafter are exhausted to atmopshere through a duct 262. The three heat exchangers of the embodiment shown in Fig. 10 cooperate to recuperate as much waste heat as possible from the combustion gases leaving the ladle 212. The ceramic heat exchanger and burner assembly 220 is constucted of materials capable of withstanding the combustion gas temperatures, which are in excess of 2000F, and transfers heat ~rom such gases to the inlet air stream. The stainless steel heat exchanger is capable of withstandinq the exhaust gases of intermediate temperature after heat has been extracted therefrom by the ceramic heat exchanger.
Similarly, the carbon steel heat exchanger 253 is efficient in transferring heat from the relatively low temperature exhaust gases prior to exhausting said gases to the atmosphere. Operation of the embodiment of the invention shown in Fig. 10 is essentially similar to that described for the embodiment shown in Fig. 9.
Now that the ladle heating system according to the invention has been described in detail, it will be understood by those skilled in the art that the principles of waste heat recuperation and heating control may be applied to systems utilizing heat sources other than natural gas flame burners.
Although the foregoing description realtes to apparatus and methods of heating ladles, it should be understood that various other objects can be heated with the disclosed apparatus and method. It should ~e understood, of course, that the foregoing relates only to preferred embodiments of the present invention and that numerous modifications or alterations may be made therein without departing from the spirit and scope of the invention as set forth in the appended claims.
Claims (33)
1. Apparatus for heating a ladle and similar molten metal receivers which includes a chamber with an opening and a rim about the opening, said apparatus comprising a seal assembly for sealing engagement with the rim of the ladle, said seal assembly comprising a support frame of greater breadth than the rim of the ladle, a plurality of refractory fiber modules mounted on said support frame approximately in a common plane, each said module being compressible and held in lateral compression by said frame and by lateral engage-ment with one another and said plurality of modules positioned on said support frame to sealingly engage the rim of the ladle, a heat exchanger mounted adjacent said seal assembly, air conduit means extending through said heat exchanger and through said seal assembly for directing air through the heat exchanger, through said seal assembly and into the ladle in sealing engagement with the seal assembly, an exhaust gas conduit means extending through said seal assembly and through said heat exchanger for directing exhaust gases from the ladle in sealing engagement with said seal assembly through said seal assembly and through said heat exchanger, blower means for inducing a stream of air through said conduit means and a stream of exhaust gases through said exhaust gas conduit means, burner means for supplying fuel to said air conduit means and for directing a flame into the ladle in sealing engagement with said seal assembly.
2. The apparatus of Claim 1 and wherein said exhaust gas conduit means includes a single opening through said seal assembly, and wherein said air conduit means comprises openings through said seal assembly on opposite sides of the exhaust gas opening, and burner means for supplying fuel at each air conduit opening.
3. The apparatus of Claim 2 and wherein said air conduit openings and said burner means are constructed and arranged to direct flames into the ladle chamber toward the surface of the ladle opposite to the rim of the ladle.
4. The apparatus of Claim 1 and wherein said seal assembly, said exhaust gas conduit means and said heat exchanger are constructed and arranged so that the flames present in the chamber of the ladle are substantially shielded from direct radiation to said heat exchanger.
5. The apparatus of Claim 1 and wherein said refractory fiber modules each comprises a web of material with the web formed in a zig-zag arrangement with parallel overlying layers, with the layers of each module extending generally toward the position of the ladle so that the rim of the ladle can compress the layers along their lengths.
6. The apparatus of Claim 5 and wherein the layers of the modules are oriented at right angles with respect to the layers of the next adjacent module.
7. The apparatus of Claim 1 and further including means for urging said seal assembly and the rim of the ladle into compressive engagement with each other.
8. The apparatus of Claim 1 and wherein said support frame includes an outer support flange surrounding said refractory fiber modules for supporting said fiber modules in compression against one another.
9. The apparatus of Claim 1 and wherein said heat exchanger comprises a plurality of heat exchangers, and wherein said air conduit means extends in series through said heat exchangers, and wherein said exhaust gas conduit extends in series through said heat exchangers.
10. The apparatus of Claim 9 and wherein the heat exchanger to which the exhaust gases are first directed is a ceramic heat exchanger.
11. The apparatus of Claim 1 and wherein the refractory fiber modules of said seal assembly are supported by said support frame in an approximately upright plane, and further comprising means for moving said seal assembly toward and away from the rim of a ladle.
12. The apparatus of Claim 1 and wherein the refractory fiber modules of said seal assembly are supported by said support frame in an approximately horizontal attitude, and further comprising means for raising and lowering said seal assembly toward and away from the rim of a ladle.
13. The apparatus of Claim 1 and further in-cluding a damper means in said exhaust gas conduit means for restricting the movement of gas through said exhaust gas conduit means.
14. A method of heating ladles and similar molten metal receivers comprising engaging the rim of the ladle with a seal of refractory fiber modules positioned substantially in a common plane with sufficient force to cause the rim of the ladle to be pressed into the seal and compress the fibers of the modules it engages, directing air through a heat exchanger and through the seal into the ladle, mixing fuel with the air and igniting the mixture as the mixture passes through the seal and into the ladle, and exhausting the gases from the ladle through the seal and through the heat exchanger.
15. The method of Claim 14 and wherein the step of exhausting the gases from the ladle through the seal and through the heat exchanger comprises exhausting the gases through a plurality of heat exchangers arranged in series.
16. The method of Claim 14 and wherein the step of exhausting the gases of the ladle through the seal and through the heat exchanger comprises exhausting the gases through a heat exchanger out of direct radiation with respect to the flame in the ladle.
17. The method of Claim 14 and after a ladle has been heated further including the steps of blockinq the exhaust of gases through the heat exchanger and disengaging the rim of the ladle and the seal.
18. The method of Claim 14 and wherein the step of engaging the rim of the ladle with a seal of refractory fiber modules comprises substantially closing the opening of the ladle formed by the rim of the ladle.
19. In combination with apparatus for heat-ing ladles and similar molten metal receivers, a seal assembly for sealing abutment with the rim of a ladle, said seal assembly comprising a support frame, a net-work of refractory fiber modules supported by said support frame in a common plane, each of said modules being held by the others of the modules and by said support frame in compression across the common plane.
20. The combination of Claim 19 and wherein each refractory fiber module comprises a web of refractory fibers formed in a flat elongated sheet with the sheet arranged in overlying zig-zag folds in a block of folds with the folds of the block exposed at opposite sides of the block, and wherein said support frame supports the modules with the folds on one side thereof in substantially a common plane and with the folds of each module extending at a right angle with respect to the folds of the next adjacent module.
21. In combination with apparatus for heat-ing ladles and similar molten metal receivers, a seal assembly for movement into sealing abutment with the rim of the ladle, said seal assembly comprising a support frame and a layer of compressible refractory fiber material supported by said support frame and arranged in a configuration to engage the rim of the ladle and form a seal about the rim of the ladle.
22. The combination of Claim 21 and wherein said layer of compressible refractory material comprises a blanket of material folded in an accordian arrangement with the folds of the blanket exposed to engage the rim of the ladle.
23. An apparatus for heating a ladle having an open end comprising:
seal means comprising ceramic fiber compaction material sized and shaped to engage the ladle about its open end and defining an opening therethrough;
a ceramic heat exchanger defining an air inlet path and an exhaust outlet path for communicating through the opening of said seal means with the interior of the ladle;
a fuel burner means connected to said air inlet path for directing hot combustion gases through the opening of said seal means into the open end of the ladle;
variable fuel supply means for mixing fuel with air from said air inlet path and supplying said mixture to said fuel burner means; and blower means for moving air along said air inlet path to said burner means;
whereby the seal means forms resilient contact with the open end of the ladle and air from said blower means moves through the heat exchanger, past the fuel supply means, through the fuel burner and through the opening of the seal means and forms a flame to heat the inside surfaces of the ladle and the hot gases from inside the ladle move back through the seal means and through the heat exchanger to preheat the air moving from the blower means through the heat exchanger.
seal means comprising ceramic fiber compaction material sized and shaped to engage the ladle about its open end and defining an opening therethrough;
a ceramic heat exchanger defining an air inlet path and an exhaust outlet path for communicating through the opening of said seal means with the interior of the ladle;
a fuel burner means connected to said air inlet path for directing hot combustion gases through the opening of said seal means into the open end of the ladle;
variable fuel supply means for mixing fuel with air from said air inlet path and supplying said mixture to said fuel burner means; and blower means for moving air along said air inlet path to said burner means;
whereby the seal means forms resilient contact with the open end of the ladle and air from said blower means moves through the heat exchanger, past the fuel supply means, through the fuel burner and through the opening of the seal means and forms a flame to heat the inside surfaces of the ladle and the hot gases from inside the ladle move back through the seal means and through the heat exchanger to preheat the air moving from the blower means through the heat exchanger.
24. The apparatus of Claim 1 and 23 further comprising:
means for sensing the temperature of said ladle; and means responsive to said temperature sensing means for adjusting the output of said fuel burner means to maintain said ladle at a predetermined temperature.
means for sensing the temperature of said ladle; and means responsive to said temperature sensing means for adjusting the output of said fuel burner means to maintain said ladle at a predetermined temperature.
25. The apparatus of Claim 1 wherein said heat exchanger comprises:
a ceramic heat exchange means for receiving said hot combustion gases directly from the interior of said ladle;
a stainless steel heat exchange means connected to said ceramic heat exchange means for receiving said hot combustion gases from said ceramic heat exchange means; and a carbon steel heat exchange means connected to said stainless steel heat exchange means for receiving said hot combustion gases from said stainless steel heat exchange means, said air inlet path extending from said blower through said carbon steel heat exchange means, then through said stainless steel heat exchange means, and then through said ceramic heat exchange means to said fuel burner means.
a ceramic heat exchange means for receiving said hot combustion gases directly from the interior of said ladle;
a stainless steel heat exchange means connected to said ceramic heat exchange means for receiving said hot combustion gases from said ceramic heat exchange means; and a carbon steel heat exchange means connected to said stainless steel heat exchange means for receiving said hot combustion gases from said stainless steel heat exchange means, said air inlet path extending from said blower through said carbon steel heat exchange means, then through said stainless steel heat exchange means, and then through said ceramic heat exchange means to said fuel burner means.
26. The apparatus of Claim 23 and wherein said ceramic heat exchanger includes a multiple stage heat exchanger with a first stage fabricated from ceramic materials for receiving the hottest gases from the ladle and at least one more heat exchanger fabricated from other materials for receiving the hot gases in sequence from said ceramic heat exchanger.
27. A method of heating a ladle having an open end comprising the steps of:
enclosing said open end of said ladle with a heat exchanger, said heat exchanger defining an exhaust outlet path communicating with the interior of said ladle and an air inlet path;
heating air traveling along said air inlet path by mixing said air with fuel and burning said mixture in a fuel burner;
directing said heated air into said ladle;
further heating said air traveling along said air inlet path with hot gases traveling in said exhaust outlet path in said heat exchanger prior to mixing said air with said fuel;
measuring the amount of oxygen in said hot gases traveling along said exhaust outlet path;
and in response to the amount of oxygen in said exhaust outlet path, regulating the fuel-air mixture provided to said fuel burner to maintain the amount of oxygen in said exhaust outlet path at a predetermined value.
enclosing said open end of said ladle with a heat exchanger, said heat exchanger defining an exhaust outlet path communicating with the interior of said ladle and an air inlet path;
heating air traveling along said air inlet path by mixing said air with fuel and burning said mixture in a fuel burner;
directing said heated air into said ladle;
further heating said air traveling along said air inlet path with hot gases traveling in said exhaust outlet path in said heat exchanger prior to mixing said air with said fuel;
measuring the amount of oxygen in said hot gases traveling along said exhaust outlet path;
and in response to the amount of oxygen in said exhaust outlet path, regulating the fuel-air mixture provided to said fuel burner to maintain the amount of oxygen in said exhaust outlet path at a predetermined value.
28. The method of Claim 27 further comprising the steps of:
sensing the temperature of said ladle;
and responsive to the temperature of said ladle being other than a predetermined value, adjusting the heating of said air traveling in said air inlet path with said fuel burner to maintain said predetermined temperature.
sensing the temperature of said ladle;
and responsive to the temperature of said ladle being other than a predetermined value, adjusting the heating of said air traveling in said air inlet path with said fuel burner to maintain said predetermined temperature.
29. An apparatus for heating a ladle having an open end comprising:
a heat exchanger defining an air inlet path and an exhaust outlet path, and further defining an open end at the side of said heat exchanger for matingly receiving and enclosing the open end of said ladle, said exhaust outlet path communicating with the interior of said ladle;
a fuel burner means communicating with said air inlet path for directing hot combustion gases through said open end of said heat exchanger into said ladle;
variable fuel supply means for mixing fuel with air from said air inlet path and supplying said mixture to said fuel burner means;
blower means for moving air along said air inlet path to said burner means;
means for sensing the temperature of the ladle;
means responsive to said temperature sensing means for adjusting the output of said fuel burner means to maintain the ladle at a predetermined temperature;
means for sensing the amount of oxygen passing through said exhaust outlet path; and means responsive to said oxygen sensing means for adjusting the composition of said fuel-air mixture provided to said fuel burner means by said variable fuel supply means to maintain the amount of oxygen passing through said exhaust outlet path at a predetermined value.
a heat exchanger defining an air inlet path and an exhaust outlet path, and further defining an open end at the side of said heat exchanger for matingly receiving and enclosing the open end of said ladle, said exhaust outlet path communicating with the interior of said ladle;
a fuel burner means communicating with said air inlet path for directing hot combustion gases through said open end of said heat exchanger into said ladle;
variable fuel supply means for mixing fuel with air from said air inlet path and supplying said mixture to said fuel burner means;
blower means for moving air along said air inlet path to said burner means;
means for sensing the temperature of the ladle;
means responsive to said temperature sensing means for adjusting the output of said fuel burner means to maintain the ladle at a predetermined temperature;
means for sensing the amount of oxygen passing through said exhaust outlet path; and means responsive to said oxygen sensing means for adjusting the composition of said fuel-air mixture provided to said fuel burner means by said variable fuel supply means to maintain the amount of oxygen passing through said exhaust outlet path at a predetermined value.
30. The apparatus of Claim 29 wherein said means for adjusting the amount of fuel provided to said fuel burner means to maintain the amount of oxygen passing through said exhaust outlet path at a predetermined value operates at any particular output level of said fuel burner means determined by said means for adjusting the output of said fuel burner means to maintain said ladle at a predetermined temperature.
31. The apparatus of Claim 30 further comprising a safety fuel cut-off means for terminating operation of said variable fuel supply means in response to said burner being extinguished.
32. An apparatus for heating a ladle having an open end comprising:
a heat exchanger defining an air inlet path and an exhaust outlet path, and further defining an open end for matingly receiving and enclosing said open end of the ladle, said exhaust outlet path and said air inlet path communicating through said open end of said heat exchanger with the interior of said ladle;
a fuel burner means in communication with said air inlet path for directing hot combustion gases through said open end of said heat exchanger into the ladle;
variable fuel supply means for mixing fuel with air from said air inlet path and supplying said mixture to said fuel burner means;
blower means for moving air along said air inlet path to said burner means;
said heat exchanger comprising a ceramic heat exchange means for receiving said hot combustion gases directly from the interior of said ladle, a stainless steel heat exchange means communiating with said ceramic heat exchange means for receiving said hot combustion gases from said ceramic heat exchange means, and a carbon steel heat exchange means communicating with said stainless steel heat exchange means for receiving said hot combustion gases from said stainless steel heat exchange means; and said air inlet path extending from said blower through said carbon steel heat exchange means, then through said stainless steel heat exchange means, and then through said ceramic heat exchange means to said fuel burner means.
a heat exchanger defining an air inlet path and an exhaust outlet path, and further defining an open end for matingly receiving and enclosing said open end of the ladle, said exhaust outlet path and said air inlet path communicating through said open end of said heat exchanger with the interior of said ladle;
a fuel burner means in communication with said air inlet path for directing hot combustion gases through said open end of said heat exchanger into the ladle;
variable fuel supply means for mixing fuel with air from said air inlet path and supplying said mixture to said fuel burner means;
blower means for moving air along said air inlet path to said burner means;
said heat exchanger comprising a ceramic heat exchange means for receiving said hot combustion gases directly from the interior of said ladle, a stainless steel heat exchange means communiating with said ceramic heat exchange means for receiving said hot combustion gases from said ceramic heat exchange means, and a carbon steel heat exchange means communicating with said stainless steel heat exchange means for receiving said hot combustion gases from said stainless steel heat exchange means; and said air inlet path extending from said blower through said carbon steel heat exchange means, then through said stainless steel heat exchange means, and then through said ceramic heat exchange means to said fuel burner means.
33. In combination with apparatus for heating ladles and similar molten metal receivers, a lid assembly for movement with respect to the ladle into sealing abutment with the rim of the ladle, said lid assembly comprising a support frame and a layer of compressible refractory fiber material supported by said support frame of a breadth greater than the rim of the ladle and sub-stantially covering the face of the lid, conduit means extending through said compressible refractory fiber material for exhausting gases from the ladle, and a burner extending through said compressible refractory fiber material for directing a flame into the ladle, whereby the lid assembly and the ladle are urged together with a force sufficient to cause the rim of the ladle to indent the compressible refractory fiber material and form a seal at the rim of the ladle, a flame is directed from the burner into the ladle and gases are exhausted from the ladle through the conduit means, and the compressible refractory fiber material shields the lid assembly from the flame.
Applications Claiming Priority (4)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US06/022,687 US4223873A (en) | 1979-03-21 | 1979-03-21 | Direct flame ladle heating method and apparatus |
| US022,687 | 1979-03-21 | ||
| US092,374 | 1979-11-08 | ||
| US06/092,374 US4229211A (en) | 1979-11-08 | 1979-11-08 | Ladle heating system |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1137302A true CA1137302A (en) | 1982-12-14 |
Family
ID=26696243
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000348173A Expired CA1137302A (en) | 1979-03-21 | 1980-03-21 | Ladle heating system |
Country Status (11)
| Country | Link |
|---|---|
| JP (1) | JPS5952020B2 (en) |
| BE (1) | BE882345A (en) |
| BR (1) | BR8007866A (en) |
| CA (1) | CA1137302A (en) |
| DE (1) | DE3038761C1 (en) |
| ES (1) | ES8101956A1 (en) |
| FR (1) | FR2452077A1 (en) |
| GB (1) | GB2057654B (en) |
| IT (1) | IT1194629B (en) |
| MX (1) | MX153242A (en) |
| WO (1) | WO1980002063A1 (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2023215928A1 (en) * | 2022-05-10 | 2023-11-16 | Fill Gesellschaft M.B.H. | Preheating station for preheating a melt transportation device |
Families Citing this family (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4529176A (en) * | 1983-10-24 | 1985-07-16 | Allegheny Ludlum Steel Corporation | Replaceable seals for ladle heaters |
| US4492382A (en) * | 1983-12-21 | 1985-01-08 | J. T. Thorpe Company | Refractory fiber ladle preheater sealing rings |
| CN110508795A (en) * | 2019-08-01 | 2019-11-29 | 安庆帝伯格茨活塞环有限公司 | A kind of ladle dryer and its baking packet method for casting ladle |
| JP7267330B2 (en) * | 2021-02-18 | 2023-05-01 | マフテック株式会社 | Refractory unit for regenerative burner and manufacturing method thereof |
Family Cites Families (14)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE464328C (en) * | 1928-08-15 | Ludwig Graven | Device for heating ladles by gas firing | |
| US792642A (en) * | 1903-06-20 | 1905-06-20 | William Erastus Williams | Melting-furnace. |
| US1057905A (en) * | 1911-12-05 | 1913-04-01 | Edgar Widekind | Apparatus for drying and heating ladles, &c. |
| DE463090C (en) * | 1925-11-14 | 1928-07-21 | Heinrich Kueppers Dipl Ing | Gas heating device to be introduced into the pouring ladle from above |
| US2294168A (en) * | 1941-03-25 | 1942-08-25 | Charles B Francis | Gas burner for heating the interior of circular vessels |
| GB976426A (en) * | 1962-02-14 | 1964-11-25 | Stewarts & Lloyds Ltd | Apparatus for heating ladles |
| DE2247274C3 (en) * | 1972-09-27 | 1975-10-09 | Eisenwerk-Gesellschaft Maximilianshuette Mbh, 8458 Sulzbach-Rosenberg | Method and device for pouring steel in continuous casting |
| SE375924B (en) * | 1973-09-17 | 1975-05-05 | Stal Laval Apparat Ab | |
| US4001996A (en) * | 1974-06-03 | 1977-01-11 | J. T. Thorpe Company | Prefabricated insulating blocks for furnace lining |
| US4014532A (en) * | 1976-01-02 | 1977-03-29 | Holley Carl A | Ladle refractory lining preheater |
| DE2623545C3 (en) * | 1976-05-26 | 1980-08-28 | Northwestern Steel And Wire Co., Sterling, Ill. (V.St.A.) | Exhaust hood for a ladle and pouring device |
| FR2377595A1 (en) * | 1977-01-13 | 1978-08-11 | Sertec Sa | Refractory lined chamber for molten material - e.g. converter or electric furnace, with improved arrangement for heating the refractory lining |
| SE408276B (en) * | 1977-10-06 | 1979-06-05 | Stal Laval Apparat Ab | COASTAL HEATER |
| SE408277B (en) * | 1977-10-06 | 1979-06-05 | Stal Laval Apparat Ab | PREHEATING DEVICE FOR COASTING, CONVERTING OR SUITABLE |
-
1980
- 1980-03-18 DE DE3038761A patent/DE3038761C1/en not_active Expired
- 1980-03-18 GB GB8035089A patent/GB2057654B/en not_active Expired
- 1980-03-18 JP JP55500798A patent/JPS5952020B2/en not_active Expired
- 1980-03-18 BR BR8007866A patent/BR8007866A/en unknown
- 1980-03-18 WO PCT/US1980/000279 patent/WO1980002063A1/en active Application Filing
- 1980-03-19 MX MX181646A patent/MX153242A/en unknown
- 1980-03-20 BE BE0/199883A patent/BE882345A/en not_active IP Right Cessation
- 1980-03-21 IT IT20832/80A patent/IT1194629B/en active
- 1980-03-21 FR FR8006412A patent/FR2452077A1/en active Granted
- 1980-03-21 CA CA000348173A patent/CA1137302A/en not_active Expired
- 1980-03-21 ES ES489799A patent/ES8101956A1/en not_active Expired
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2023215928A1 (en) * | 2022-05-10 | 2023-11-16 | Fill Gesellschaft M.B.H. | Preheating station for preheating a melt transportation device |
Also Published As
| Publication number | Publication date |
|---|---|
| DE3038761A1 (en) | 1981-04-23 |
| ES489799A0 (en) | 1980-12-16 |
| FR2452077B1 (en) | 1985-04-19 |
| MX153242A (en) | 1986-09-02 |
| BE882345A (en) | 1980-07-16 |
| JPS5952020B2 (en) | 1984-12-17 |
| WO1980002063A1 (en) | 1980-10-02 |
| ES8101956A1 (en) | 1980-12-16 |
| GB2057654A (en) | 1981-04-01 |
| DE3038761C1 (en) | 1985-02-21 |
| JPS56500328A (en) | 1981-03-19 |
| GB2057654B (en) | 1983-08-03 |
| BR8007866A (en) | 1981-02-03 |
| IT1194629B (en) | 1988-09-22 |
| IT8020832A0 (en) | 1980-03-21 |
| FR2452077A1 (en) | 1980-10-17 |
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Legal Events
| Date | Code | Title | Description |
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| MKEX | Expiry |