What is a fired heater and what are its main components?

A fired heater (process furnace) directly heats process fluids using combustion of fuel. Main components include: radiant section (direct flame radiation to tubes), convection section (recovers heat from flue gases), burners (atomize and combust fuel with air), tubes/coils (contain process fluid), stack (discharges flue gases, provides draft), refractory lining (insulates and protects shell), and air preheater (optional, improves efficiency). Fired heaters achieve higher temperatures than steam heating and are essential in refineries and petrochemical plants.