Method for the melting, combustion or incineration of materials and apparatus therefor

A plasma arc melter for melting materials comprising at least two transferred arc plasma torches of opposite polarities, one of said torches being a cathode torch comprising a cathode electrode and a nozzle for emitting a cathode plasma jet, and one of said torches being an anode torch comprising an anode electrode and a nozzle for emitting an anode plasma jet;

• means for locating a discharge end of the cathode nozzle and a discharge end of the anode nozzle relative to each other for the transfer of current between the torches through a coupling zone to heat the materials and means for supplying current to the torches;
• a rotatable, generally cylindrical melter shell for holding the materials, said melter shell having a vertical, longitudinal axis, said melter shell having a bottom wall, a sidewall and an open top;
• a non-rotating melter hood located over the open top of the melter shell, and the plasma torches being mounted in the melter hood;
• the improvement comprising:
• the discharge end of the cathode torch nozzle being offset relative to the vertical, longitudinal axis of the melter shell;
• the melter hood having a materials feed port offset relative to the vertical, longitudinal axis of the melter shell for introducing the materials to be heated into the melter shell at a location offset from the vertical, longitudinal axis;
• and
• means for rotating the melter shell such that the materials introduced into the melter shell of the plasma arc melter through the feed port pass beneath the discharge end of the cathode torch nozzle before passing beneath the discharge end of the anode torch nozzle.

In a method of heating materials in a plasma arc furnace which is equipped with at least two transferred arc plasma torches of opposite polarities, one of said torches being a cathode torch comprising a cathode electrode and a nozzle for emitting a cathode plasma jet, one of said torches being an anode torch comprising an anode electrode and a nozzle for emitting an anode plasma jet, and a melter shell for holding the materials, the improvement comprising:

• positioning a plasma jet discharge end of the anode torch nozzle and a plasma jet discharge end of the cathode torch above an upper surface of the materials in the melter shell;
• transferring current between the torches through a coupling zone to heat the materials;
• injecting an oxidizing gas into the coupling zone for greater combustion efficiency;
• and deflecting the plasma jets with the injected oxidizing gas to keep the plasma jets from contacting the discharge ends of the torches.

In a method of heating materials in a plasma arc furnace which is equipped with at least two transferred arc plasma torches of opposite polarities, one of said torches being a cathode torch comprising a cathode electrode and a nozzle for emitting a cathode plasma jet, another of said torches being an anode torch comprising an anode electrode and a nozzle for emitting an anode plasma jet, a melter shell for holding the materials, the melter shell being generally cylindrical in shape and having an open top with a vertical axis, a non-rotating hood carrying the torches located over the open top of the melter shell, and means to rotate the shell about the vertical axis to rotate the materials relative to the torches, the improvement comprising:

• positioning a plasma jet discharge end of the anode torch nozzle at least as far away from the upper surface of the materials in the melter shell as a plasma discharge end of the cathode torch nozzle during the transfer of current between the torches through a coupling zone to heat the materials;
• offsetting the discharge end of the cathode torch nozzle from the vertical axis of the melter shell;
• introducing the materials to be heated into the melter shell at a location offset from the vertical axis of the melter shell;
• and
• rotating the melter shell to pass the materials introduced into the melter shell at the location offset from the vertical axis of the melter shell beneath the discharge end of the cathode torch nozzle before the materials pass beneath the discharge end of the anode torch nozzle.

A plasma arc melter for melting materials comprising at least two transferred arc plasma torches of opposite polarities, one of said torches being a cathode torch comprising a cathode electrode and a nozzle for emitting a cathode plasma jet, and one of said torches being an anode torch comprising an anode electrode and a nozzle for emitting an anode plasma jet;

• means for locating a discharge end of the cathode nozzle and a discharge end of the anode nozzle relative to each other for the transfer of current between the torches through a coupling zone to heat the materials and means for supplying current to the torches;
• the plasma arc melter having a melter shell having a bottom wall, a sidewall and an open top;
• a melter hood located over the open top of the melter shell, and the plasma torches being mounted in the melter hood;
• the improvement comprising:
• means for introducing an oxidizing gas into the coupling zone for greater combustion efficiency comprising the anode torch which has a tubular electrode and uses an oxidizing gas as a plasma gas for the anode plasma jet;
• the anode torch having a collar with spiral channels that guide the plasma gas, give the plasma gas a rotational motion within the tubular electrode and cause an arc attachment point of the anode plasma jet to rotate about an inner cylindrical surface of the tubular electrode.

A plasma arc melter for melting materials comprising at least two transferred arc plasma torches of opposite polarities, one of said torches being a cathode torch comprising a cathode electrode and a nozzle for emitting a cathode plasma jet, and one of said torches being an anode torch comprising an anode electrode and a nozzle for emitting an anode plasma jet;

• means for locating a discharge end of the cathode nozzle and a discharge end of the anode nozzle relative to each other for the transfer of current between the torches through a coupling zone to heat the materials and means for supplying a current to the torches;
• a generally cylindrical melter shell for holding the materials, said melter shell having a bottom wall and said melter shell having an open top, a melter hood located over the open top of the melter shell, and the plasma torches being mounted in the melter hood;
• the improvement comprising:
• means for introducing an oxidizing gas into the coupling zone comprising an injection tube mounted on an outside surface of at least one of the torches through which the oxidizing gas is introduced into the existing plasma jet as the plasma jet exits the discharge end of the torch nozzle.

A plasma arc melter for melting materials comprising at least two transferred arc plasma torches of opposite polarities, one of said torches being a cathode torch comprising a cathode electrode and a nozzle for emitting a cathode plasma jet, and one of said torches being an anode torch comprising an anode electrode and a nozzle for emitting an anode plasma jet;

• means for locating a discharge end of the cathode nozzle and a discharge end of the anode nozzle relative to each other for the transfer of current between the torches through a coupling zone to heat the materials and means for supplying current to the torches;
• a generally cylindrical melter shell for holding the materials, said melter shell having a bottom wall and an open top;
• a melter hood located over the open top of the melter shell, and the plasma torches being mounted in the melter hood;
• the improvement comprising:
• a means for introducing an oxidizing gas into the coupling zone comprising a shroud mounted on at least one of the torches through which the oxidizing gas is introduced into the existing plasma jet as the plasma jet exits the discharge end of the torch nozzle.