A method has been developed to measure gas composition inside the pit in open anode baking furnaces. The gas composition can be used to understand attack on and degradation of the refractory lining, baking behavior and combustion energy contribution through the baking cycle. A probe was installed in the packing coke near the bottom of the pit while extracting gas over several days with continuous analysis with an FTIR spectrometer. The results show a clear temperature dependence of CO and CO2 composition. Methane was found to be the dominating gas species at the beginning of the measuring cycle. Fluoride gases was also present, indicated by reactions with the glass wool filter to yield SiF4 that was detected in small amounts. PAH condensates were observed but not systematically determined in the present campaign. Earlier results from PAH measurements before the scrubbing, showing large fluctuations, will be discussed in relation to present findings
