Electrothermal Characterization of an AC Thermal Plasma Torch

A primary component in gasification is the plasma torch. Conversion of electrical energy to a high-temperature arc is essential. The properties of this arc determines, among other things, the efficiency of converting electrical input power to heat and mass transfer in the reactor chamber. A unique, single-phase torch was acquired for gasification studies. Power for this torch is supplied from the electric mains and is stepped up to 6 kV. The torch uses gas flow to complement the electrical energy transfer. Electrical operation of the torch is characterized by the Volt-Ampere plot, which is useful in determining the power rating of the torch as well as diagnosing the dynamic behavior of the plasma. The output of the torch is a thermal source at or near local thermodynamic equilibrium (LTE). Diagnostics are employed to characterize the torch. Plasma current is obtained by using a current transformer. Measurement of the plasma voltage is via an isolated technique. Optical emission spectroscopy, with the assumption of LTE, is used to determine the plasma kinetic temperature using the relative line method. An electrothermal plasma code provides the fundamental parameters at the torch nozzle, which are needed for gasification reactor design.