FULL CONTROL OF PITCH BURN DURING BAKING: IT’S IMPACT ON ANODE QUALITY, OPERATIONAL SAFETY, MAINTENANCE AND OPERATIONAL COSTS

摘要

The quality of a baked anode is, amongst other criteria, defined bythe heat treatment. Each anode in a pit has to reach a specifictemperature overall in a certain time. The heat transfer isdetermined by the temperature versus time curve of thesurrounding flues and the furnace geometry.Due to the physical design of the open top ring furnace, lessenergy is introduced to the outer flues in the preheat area. Further,the pitch burn starts and ends at a later point than at the innerflues. As a primary result, the homogeneity of the anode qualitywill be affected. Secondarily, other disadvantages will occur aswell as which are:1. unburned volatile fractions which condensedownstream in the furnace, exhaust pipe, ducts and FTCfacilities2. higher emissions, especially hydrocarbons (PAH16),CO, CO_2 and NOx parts3. high operational costs for extensive maintenance toclean equipment, ducts and FTC facilities4. impact on operational safety due to accumulation ofignitable fractions downstream to the FTC5. higher running and energy costsThis paper will describe the different steps and strategies tooptimize the baking process, achieving full control of the pitchburn and will show the results as remarkable improvements onanode quality, emissions, fuel consumption and running costs.