Induction heating

An apparatus for melting glass via induction melting comprising:

• a current conducting melting vessel;
• the melting vessel includes an inlet formed by a neck region and at least one outlet arranged respectively for receiving glass frit and draining the molten contents of the melting vessel to a location below the vessel during a draining operation
• at least two induction heating coils provided at selected locations proximate to the melting vessel;
• a plurality of power supply circuits each being associated with a respective one of the heating coils and being arranged for selectively supplying power to a respective coil to thereby energise that respective coil;
• wherein
• each power supply circuit includes:
• a first portion comprising a supply leg and a return leg connected to a power supply and a transformer element connected between the supply leg and the return leg;
• and
• a second portion connected to a supply node in the supply leg and a return node in the return leg, the second portion comprising the respective coil;
• and
• a switching element arranged to selectively prevent and permit a mutual induction of current in a respective heating coil when an adjacent heating coil is energised according to a selected on or off status of the switching element, and wherein the switching element is switchable between an off status in which mutual inductance of current is prevented in the respective heating coil and an on status in which mutual inductance of current is permitted.

A method for reprocessing waste material comprising:

• locating the waste material together with glass forming material in a current conducting melting vessel;
• the melting vessel includes an inlet formed by a neck region and at least one outlet arranged respectively for receiving glass frit and draining the contents of the vessel to a location below the vessel during a draining operation;
• the melting vessel further comprising at least two induction heating coils at selected locations proximate to the melting vessel and a plurality of power supply circuits each being associated with a respective one of the heating coils and being arranged for selectively supplying power to the respective coil to thereby energise that respective coil;
• applying power to at least one of the induction heating coils located proximate to the vessel to thereby heat the glass forming material;
• and
• subsequently pouring a molten mixture of glass and waste material from the vessel into a storage container;
• wherein
• during the power applying step, at least one of the heating coils is energised and mutual induction of current in a heating coil adjacent the energised coil is prevented or permitted by selecting an on or off status of a switching element in a respective one of the power supply associated with the adjacent heating coil, wherein the switching element is switchable between an off status in which mutual inductance of current is prevented in the adjacent heating coil and an on status in which mutual inductance of current is permitted in the adjacent heating coil, and wherein the power supply circuitry associated with each heating coil includes:
• a first portion comprising;
• a supply leg and a return leg connected to a power supply;
• and a transformer element connected between the supply leg and the return leg;
• and
• a second portion connected to a supply node in the supply leg and a return node in the return leg, the second portion comprising the heating coil and the switching element.