ARC furnace with DC arc and AC joule heating
OwnerCharles H. Titusinventor
Life of this patent
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Abstract
An arc furnace that utilizes a combined DC arc system and an AC joule heating system to melt the waste disposed therein and to keep the waste material in a molten condition. The DC arc system utilizes the AC joule heating electrodes as part of the DC current path, thereby eliminating the need for a counter DC electrode. Furthermore, the AC joule heating system provides for peripheral and radial AC current flow to neighboring AC joule heating electrodes, thereby creating a stirring effect in the molten waste. This design greatly simplifies the arc furnace control system while providing a more effective thermal control of the molten waste.
Claims32
An apparatus for waste conversion said apparatus comprising:
- a tank for receiving the waste;
- a single electrode for supporting a DC arc to melt the waste in the tank, said single electrode being coupled to a source of DC power;
- a plurality of AC joule heating electrodes, inductively-coupled to a source of AC power, submerged in the melted waste, that maintain the melted waste in a molten state while simultaneously acting as DC counter electrodes, said plurality of AC joule heating electrodes being coupled to said DC power source.
A method for converting waste, said method comprising the steps of:
- (a) disposing the waste in a tank for treatment;
- (b) applying a DC arc to melt the waste through a single electrode by coupling said single electrode to a DC power source and adjusting the position of one end of said single electrode with respect to the waste to support said DC arc;
- (c) applying AC joule heating to maintain the waste in a molten condition through a plurality of AC joule heating electrodes submerged in the waste;
- and
- (d) utilizing said plurality of AC joule heating electrodes as DC counter electrodes of said DC arc by:
- (1) providing a plurality of transformers, each having a primary winding, a pair of secondary windings and a magnetic core, said primary windings being coupled in series to an AC power source and wherein each pair of secondary windings is magnetically coupled to a respective primary winding;
- (2) winding each pair of secondary windings around said magnetic core with the same number of turns and the same size conductor but winding each one of the pair of secondary windings in a direction for cancelling a DC magnetic flux in said magnetic core when DC current flows in each pair of secondary windings;
- and
- (3) connecting a first end of each one of said pair of secondary windings to said DC power source and connecting a second end of each one of said pair of secondary windings to a respective AC joule heating electrode.
Dependencies are inferred from the claim text.