Improvement of Boiler's Efficiency Using Heat Recovery and Automatic Combustion Control System

This research was conducted to improve the efficiency of a fire tube boiler with a fixed gate and screw conveyor for feeding fuel. The efficiency improvement was based on the use of flue gas heat for fuel drying, air preheating before combustion, and controlling amount of air for fuel combustion before entering the combustion chamber using the fuzzy logic control algorithm. The experimental result indicates that using heat recovery and fuel drying reduces 3%wt of fuel moisture content and boiler efficiency increases 0.41%. Preheating air means a 35 °C increase of temperature or a 0.72% increase of boiler efficiency. The average accuracy of air control is 89.15%, indicating a 4.34% increase of boiler efficiency. If the three systems are operated simultaneously, 5.15% increase of boiler efficiency will be achieved or 246.88 tons/year saving of fuel.