Cokes furnace control improvements.
Result: 70% reduction of pressure peaksCokes oven. Customer: Tata Steel, the Netherlands. Cokes furnaces are primarily producing cokes, for ironmaking. In this process, however, gasses are produced as well. It is important that the pressures in the furnaces are kept at target with minimal variations. DotX investigated the cause of the gas pressure variations and the possibilities to reduce these by adjusting the control system. In 2008, the investigations started. It appeared that the control hardware was not suitable for the required changes. 2010, after a replacement of the control hardware, the PI controllers were extended with D-action, and the PID controllers were tuned optimally. PID autotuners were implemented to maintain optimal settings of the resulting PID controllers. Furthermore, Learning Feedforward was added (read more on these solutions this link). As a result, the pressure peak errors were reduced by 50%, and the standard deviations of the gas pressure variations were reduced by 40%. The figure below shows measurements of the pressure in blue (scaled) BEFORE (i.e. without learning FF), and AFTER (with Learning Feedforward). The green line is the trigger signal; if it jumps to 1, the furnace is filled with coal. The Learning Feedforward learns to compensate the resulting pressure variations. Note that all control solutions were implemented in the Tata PLC system. Since 2011, our efforts are more focussed towards the control of other installations in the cokes furnace.