Dynamics of Anode Baking Furnace VOC Emissions Through a Firing Cycle

The anode baking process produces significant amounts of volatile organic compounds (VOC) and polyaromatic hydrocarbons (PAH). Measuring the full range of these emissions is costly and time-consuming. However, VOC and lighter PAH components that exist mainly in gas phase can be measured by simpler means. Establishing a known ratio between the components could enable estimates of the total emissions by following certain proxy components. To document the distribution and time profiles of VOC and light PAH components, different sampling methodologies with time resolution better than 30 min were evaluated. Measurements using thermal desorption (TD) tubes, a photoionisation detector (PID) instrument, and a gas chromatograph with flame ionization detector (GC-FID) were conducted up and downstream the gas treatment centre. Removal efficiencies of selected VOC were calculated. In addition, dynamics between different gas components during the firing cycle was shown, showing high initial load of light VOC just after the onset of the firing cycle while heavier components emerged later.