Combustion By-Products Destruction by Arc Plasma

Abstract

The parameters affecting complete thermal decomposition of methane, and 1,1–dichloroethane in a dc argon plasma were investigated. The 1,1–dichloroethane was chosen as a representative reactant from chlorinated–compounds and chemical warfare agents. Theoretical studies were conducted using STANJAN thermochemical equilibrium solver–code on stoichiometric mixtures of methane–air and dichloroethane–air systems. In addition, the effect of 10% excess oxygen in the stoichiometric methane–air system was studied in order to understand the role of oxygen at a plasma condition. The results from these studies give valuable information in predicting the species concentrations and evaluating the quenching process. To conduct experimental investigations, a 10 kW laboratory scale dc plasma generator was built and operated to produce a stable argon plasma. The representative organic species: methane, and dichloroethane were included in the argon stream for decomposition in the plasma. The decomposition of the species in the plasma was monitored by optical emission spectroscopy. The extent of thermal decomposition was measured by the emission spectrum obtained from the data acquisition system. The gas–flow rate of the reactants and the power dissipated in the plasma were found to be important parameters for achieving complete decomposition of a particular chemical species. The argon–methane plasma was used as a reference, because methane is the simplest saturated hydrocarbon and we could use it to simulate the effluent from an incinerator. The plasma destruction of hazardous wastes was thus found to be very promising.