Proces Control

Cokes 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%.

Since 2011, our efforts are more focussed towards the control of other installations in the cokes furnace.

Chemical process. Customer: DSM, the Netherlands.

VDL Weweler is a producer of automotive suspension systems and axles. In 2010, after a feasibility study, DotX was assigned by VDL Weweler to implement DNPC  to one of the Weweler walking beam furnaces. In January 2011, the controller was operational. A reduction of at least 4 % on average was measured. Further reductions are foreseen, after minor hardware changes.

	Brochure on DNPC for Furnaces

A paper on this subject was presented on the METEC InSteelCon 2011 conference in Dusseldorf (E. A. Nederkoorn, P. van Wilgen, J. Schuurmans, "Nonlinear model predictive control of walking beam furnaces", 2011).

Crown van Gelder is a paper producer. When paper is produced from pulp, the grinding of the pulp must be performed with minimal fluctuations, while the pulp tank level must remain within fixed limits. DotX has changed the control system in January 2008 in such a way that the grinding fluctuations reduced by more than 40%.

In cooperation with Nelen & Schuurmans BV, a tailor made DNPC application was developed for the control of two pumpstations in the polder 'Waterlandse Boezem'. The DNPC controller had to satisfy complicated on/off requirements, and had to minimise pumping activity in the more expensive day-hours. This DNPC application is running under the Control Next software www.control-next.nl.

To download a paper on this subject (in dutch), please click here.