Hydro Årdal CarbonCarbon produces approximately 220,000 tons of baked anodesAnode annually from two closed-top bakingBaking furnaces: Furnace 4 (commissioned in 1999) and Furnace 3 (commissioned in 2004). As part of the Furnace 3 project, a new flue gas treatment plantFlue Gas Treatment Plant (FTP) was installed, featuring two Regenerative Thermal OxidizersRegenerative Thermal Oxidizer (RTO) (RTOs) and four seawater scrubbers serving both furnaces. In 2007, the scrubber line was further upgraded with Wet Electrostatic Precipitators (WESPs). Since 2004, emissionEmissions and discharge permit for EPA 16 PAHPolycyclic Aromatic Hydrocarbons (PAH) compounds have been progressively tightened, with the latest revision from the Norwegian Environmental Authorities taking effect in 2025. The current discharge limit to sea is approximately one-fifth of the level permitted when the flue gas treatment plantFlue Gas Treatment Plant (FTP) was completed in 2007. These increasingly stringent regulations place greater demands on both the operation of the bakingBaking furnaces and the performance and uptime of each stage of the flue gasFlue gas treatment systemGas Treatment System (GTC). The main fans within the treatment plant represent a critical bottleneck, operating near or at full capacity. Excessive vibrations in the support frames have caused mechanical stressMechanical stresses in couplings, bearings, and shafts, leading to unpredicted breakdownsBreakdown, motor shutdowns, and inadequate draft levels in the furnaces. Vibration measurementsMeasurements and thermomechanical finite elementFinite element analysis revealed that the support frames exhibited resonant frequencies close to the motors’ operating range. To address this, modal analysis results were used to redesign the frames, shifting their natural frequencies away from critical ranges and thereby reducing harmful oscillations.