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A control system and method for controlling a temperature and molten metal height in a gas-fired metal melting furnace whereby metal height and temperature may be more reliably maintained. The control system includes a controller that receives information on metal temperature and metal height. The c

A control system and method for controlling a temperature and molten metal height in a gas-fired metal melting furnace whereby metal height and temperature may be more reliably maintained. The control system includes a controller that receives information on metal temperature and metal height. The controller controls metal melting burners so as to operate at different settings between a high output and a low output based upon sensed metal height.

대표청구항 ▼

What is claimed is: 1. A control system for maintaining molten metal height in a gas fired metal melting furnace, comprising: a sensor arrangement that is operable to sense a plurality of metal heights; a melting burner air valve assembly comprising an air valve and a servo-motor that is operable t

What is claimed is: 1. A control system for maintaining molten metal height in a gas fired metal melting furnace, comprising: a sensor arrangement that is operable to sense a plurality of metal heights; a melting burner air valve assembly comprising an air valve and a servo-motor that is operable to adjust the air valve between a high position and a low position; a melting burner gas valve that is opened an amount in dependence upon the opening amount of the air valve; a melting burner that receives air output from said air valve and gas output from said gas valve; and, a controller that receives signals from the sensor arrangement indicative of the metal height, and is operable to actuate the servo-motors to move the air valve into any one of a plurality of positions based upon said sensed metal heights, said plurality of positions including a high position and a position between the high position and a low position. 2. The control system according to claim 1, wherein said sensor arrangement includes a plurality of level sensing probes, said probes being adapted to measure a particular metal height. 3. The control system according to claim 1, wherein said sensor arrangement includes a laser sensor that is adapted to measure metal height. 4. The control system according to claim 2, wherein said plurality of level sensing probes includes a high probe, which is adapted to sense a high metal level, and a low probe, which is adapted to sense a low metal level. 5. The control system according to claim 4, wherein said plurality of level sensing probes includes an additional probe that is adapted to sense a metal level between the high metal level and the low metal level. 6. The control system according to claim 3, wherein the controller includes a program correlating ranges of metal heights with air valve opening amounts, and wherein the sensed height is used to select an associated air valve opening amount. 7. A method for controlling an air valve for a melting burner of a gas-fired metal melting furnace, comprising the steps of: providing a sensor arrangement that is operable to sense a molten metal height between a high metal level and a low metal level; providing a controller that is adapted to receive a metal height signal from said sensor arrangement and generate control instructions based thereon; providing an air valve assembly including the air valve and a servo-motor, said air valve being movable between a high position and a low position, said servo-motor being actuated by said controller so as to move said air valve into a desired opening position, wherein said desired opening position is in a range of positions including the high position and a position between the high position and the low position; moving said air valve assembly into a position between said high and low positions based upon sensed metal height. 8. The method according to claim 7, wherein said controller correlates ranges of metal heights with air valve opening amounts, and comprising the further steps of: communicating sensed metal height to said controller; using said sensed metal height to select the desired air valve opening amount corresponding to a range of metal heights that said sensed metal height is a member of; and, moving said air valve into the position corresponding to the range of metal heights. 9. A control system for maintaining molten metal height in a gas fired metal melting furnace and for maintaining molten metal temperature within prescribed limits, comprising: a sensor arrangement that is operable to sense a plurality of metal heights; a temperature sensor for sensing a temperature of the molten metal; a melting burner air valve assembly comprising a melting burner air valve and a melting burner servo-motor that is operable to adjust the melting burner air valve between a high position and a low position; a melting burner gas valve that is opened an amount in dependence upon the opening amount of the melting burner air valve; a melting burner that receives air output from said melting burner air valve and gas output from said melting burner gas valve; a holding burner air valve assembly comprising a holding burner air valve and a holding burner air valve servo-motor that is operable to adjust the holding burner air valve between a high position and a low position; a holding burner gas valve that is opened an amount in dependence upon the opening amount of the holding burner air valve; a holding burner that receives air output from said holding burner air valve and gas output from said holding burner gas valve; and, a controller that receives signals from the sensor arrangement indicative of the metal height and signals from the temperature sensor indicative of metal temperature, and is operable to actuate the melting burner air valve servo-motor to move the melting burner air valve into any one of a plurality of positions based upon said sensed metal heights, and is operable to actuate the holding burner air valve servo-motor to move the holding burner air valve into any one of a plurality of positions based upon said sensed temperature, said plurality of positions including a high position and a position between the high position and a low position. 10. The control system according to claim 9, wherein said sensor arrangement includes a plurality of level sensing probes, said probes being adapted to measure a particular metal height. 11. The control system according to claim 9, wherein said sensor arrangement includes a laser sensor that is adapted to measure metal height. 12. The control system according to claim 10, wherein said plurality of level sensing probes includes a high probe, which is adapted to sense a high metal level, and a low probe, which is adapted to sense a low metal level. 13. The control system according to claim 12, wherein said plurality of level sensing probes includes an additional probe that is adapted to sense a metal level between the high metal level and the low metal level. 14. The control system according to claim 11, wherein the controller includes a program correlating ranges of metal heights with melting burner air valve opening amounts and correlating metal temperature with holding burner air valve opening amounts, and wherein the sensed height is used to select an associated melting burner air valve opening amount and wherein the sensed temperature is used to select an associated holding burner air valve opening amount. 15. The controls system according to claim 5, wherein a normal metal height range is a range in which normal operation of the gas fired metal melting furnace is conducted, wherein said high metal level is a highest metal height within the normal metal height range, and said low metal height is a lowest metal height within the normal metal height range. 16. The controls system according to claim 13, wherein a normal metal height range is a range in which normal operation of the gas fired metal melting furnace is conducted, wherein said high metal level is a highest metal height within the normal metal height range, and said low metal height is a lowest metal height within the normal metal height range.