A system for controlling a gas burning appliance is disclosed. The system includes a central control unit. A pilot valve and main valve controls the flow of fuel from a fuel source to the pilot and main valve, respectively, and are configured for accepting an electrical current from a thermopile and from a power source. A spark generator generates for igniting fuel received by the pilot thereby generating a pilot flame. A flame sensor is adapted for monitoring the presence of a pilot flame. A thermopile proximate to the pilot burner is configured for generating an output electrical current for powering the pilot and main valve control devices. A relay routes electrical current between the power source and thermopile to the pilot and main valve control devices. A flame height regulating device conductively coupled with the power source is configured for adjusting a height of a main flame.

Various embodiments include a method for controlling a combustion device comprising a first combustion sensor and a second sensor. An example includes: specifying a first setpoint value for the first sensor for a first fuel; controlling the combustion device to the first setpoint value; recording a first value of the signal from the first combustion sensor and a second value of the signal from the second sensor; determining a second fuel as a function of the first signal and the second signal; comparing a composition of the first fuel to a composition of the second fuel; and, if the second fuel is of a different composition from the first fuel, determining a second setpoint value for the signal from the first combustion sensor as a function of the second fuel and adjusting the combustion device using the first combustion sensor to the second setpoint value for the signal from the first combustion sensor; else making no further adjustment.

A sensor device for detecting a flame comprises a carbon dioxide sensor for detecting a CO.sub.2 concentration, a fuel sensor for detecting the combustion of a fuel, an electrostatic charge variation sensor for detecting electrostatic charge variations generated by the flame, and a control unit. The control unit is configured to acquire a carbon dioxide signal indicative of the concentration of carbon dioxide, a fuel signal indicative of the fuel combustion, and an electrostatic charge variation signal indicative of a difference between the electrostatic charge variations detected by a first and a second electrode of the electrostatic charge variation sensor, determine a quantized signal based on the electrostatic charge variation signal, determine an aggregate datum based on the carbon dioxide signal, the fuel signal and the electrostatic charge variation signal, and generate, based on the aggregate datum, a flame signal indicative of the presence or absence of the flame.

Provided are a method and an arrangement for monitoring performance of a burner of a suspension smelting furnace. The burner is arranged at the top structure of a reaction shaft of the suspension smelting furnace. The burner has a solids feeding channel that has a solids outlet opening up into the reaction shaft, and a reaction gas channel comprising a reaction gas channel a that has a reaction gas outlet opening up into the reaction shaft. The arrangement comprises at least one imaging means for producing images representing the cross-section of the reaction gas channel, and a processing means for receiving images of the cross-section of the reaction gas channel from the imaging means.

A flame sensing system, a flame sensing unit, and a method for sensing a flame are described. The flame sensing system includes a flame sense probe and a power regulating device. The power regulating device is configured to generate a regulated voltage from an input voltage received from a power source and to output the regulated voltage to the flame sense probe such that a flame current along a flame can be measured. The flame sensing system also includes a flame current detector to measure the flame current and generate an output voltage corresponding to the flame current, and a first level detector to generate a flame strength output signal based on the output voltage, where the flame strength output signal is indicative of a strength of a flame.