Machanized oxyfuel control with ion current sensing: An approach for sensing standoff distance and fuel-oxygen mixture using only the electrical characteristics of the flame is descirbed

This paper advances an approach to sensing in mechanized oxyfuel systems where sensors are eliminated and the electrical characteristics inherent to the torch, flame, and workpiece are used to measure standoff distance and fule-oxygen ratio. Electrical properties are also shown to be correlated to preheat flow rate and work temperature. These measurements were conducted by applying voltage to the torch and measuring the resulting current transmitted through the flame. Measurements with an Oxweld C-67 torch heating a temperature-stabilized plate revealed an nonlinear current-voltage characteristic with three regimes at signal level voltages (-10 to 10 V). These regimes were dominated by different physical phenomena that empowered the observer to understand various parameters of the system typically only available by mounting sensors in the vicinity of the flame. Eliminating sensors from the "hot zone" had positive cost implications, but there was an even stronger potential benefit to the reliability of the system, because those sensors were susceptible to damage from the process.