Advanced Control Strategy Reduces Recovery Boiler Fouling While Liquor Throughput is Increased, 1998 International Chemical Recovery Conference Proceedings

An advanced process control strategy was implemented on the chemical recovery boiler process at Canadian Forest Products Ltd. Intercontinental Pulp in Prince George, BC. The strategy improved performance of the boiler with increased liquor throughput being obtained coincident with reduced fouling of convection surfaces. In addition, further benefits were realized of increased thermal efficiency and a more stable process operation. Major functionality provided by the control system includes full automatic control greater than 95 percent of the time, liquor firing control by the Consumed Air method, and an enhanced operator interface. The boiler performance is reviewed before and after control strategy implementation. A boiler Fouling Index used by the mill reliably indicates the degree of plugging of convection surfaces. Results show that implementation of advanced control and automatic operation significantly stabilizes recovery furnace operation and reduces the accumulation rate of ash deposits and fouling of the convection surfaces. The time between water washes of the boiler is significantly extended by the system of automatic control.