PLASMA FURNACE AND A METHOD OF OPERATING THE SAME

摘要

The flow of waste gas is directed downwardly by means of a refractory guide chute so as to follow the down flow of molten slag at the downstream end of a slag outlet. Thus the sensible heat of the high-temperature waste gas forcedly heats the molten slag and the downstream end portion of the slag outlet. Consequently, it becomes less possible for the slag outlet to be choked up. Assuming that the upstream end of the slag outlet is disposed at a horizontal distance of L from the downstream end of a waste inlet, a pivot, about which a plasma torch is tilted, is disposed at a horizontal distance of 0.2L to 0.45L from the downstream end of the waste inlet. Because of this arrangement, heat from a plasma arc is adapted to be radiated to the downstream end of the waste inlet and its vicinity so as to quickly melt the waste. When there are signs that the slag outlet is being choked up, the plasma torch is slightly tilted to the upstream end of the slag outlet so as to stabilize the discharge of the molten slag. A housing or jacket is disposed circumferentially around an incineration residue feed pipe, inserted through the incineration residue inlet, and adapted to allow an annular gas curtain to issue therefrom. A driving device for changing the inclination of the jacket is provided, this driving device being associated with a tilting device for changing the inclination of the plasma torch so that, when the inclination of the plasma torch is changed by the tilting device, the inclination of the jacket may also be changed by the driving device. Gas, e.g. air, is delivered from the jacket and directed toward a reservoir of the molten slag in such a manner that the direction of radiation from the plasma torch and the direction of gas delivery from the jacket intersect substantially on the surface of the slag reservoir. Thus the incineration residue is allowed to fall onto a high-temperature area of the surface of the slag reservoir. Fuel injection against the waste gas in the furnace body is particularly suitable for decreasing the amount of NO x. Valuable matter is efficiently recovered from the waste gas without causing a waste gas channel in a waste gas purifying plant to be choked up with the particles of valuable matter. A device for detecting the leakage of cooling water caused by the deterioration of the plasma torch is also provided.