❚❚❚ The factory in Brunsbüttel employs 520 people and is a mod­ern and important production unit for the Sasol group. Thanks to excellent infrastructure, the location is also perfect for future growth. Technological progress, new developments and the use of modern technologies is day-to-day business for this global player in the chemistry industry. Manfred Rohwer explains SASOL’s philosophy, “We see change as a chance for constant improvement”. Rohwer manages the department for electronics, measurement and control. The Sasol group is a South African company with 30,000 employees worldwide and a sales volume of about 10 billion US dollars.

In Germany, Sasol produces raw materials for detergents (tensides) and fatty alcohols, ethylene oxide and alkyl phenol, as well as solvents, waxes and oleochemicals. In Brunsbüttel, Sasol produces fatty alcohols, their derivates and special anorganic chemicals, such as high purity alumina. Alumina is re­quired for the production of refining and chemical catalysts, it helps with cleaning automobile emissions and it is used for the production of heavy-duty plastics (for example, for use in the aviation industry).

For a successful future: modernizing the infrastructure

Sasol has a pipeline system with about 300 valves for routing alumina and chemicals in the alumina halls in their Brunsbüttel factory. This resulted in a total of about 200 different paths of getting from the source to the required destination. The existing process control system was used for routing control. All function blocks were developed by Sasol employees. Because of the dis­tributed structure of the process control system the valves were connected to different process stations. The cross-communica­tion required by this structure resulted in high network loading and performance restrictions.

In order to improve the existing infrastructure, and at the same time increase flexibility, Sasol looked for a flexible control system that could also be extended in the future. Keeping the routing control unchanged after extending the system would not have been possible. Jörg Brouwer, in charge of the process control system at Sasol, decided on a new approach. The task of finding and evaluating a new solution for routing control was posted as a diploma thesis. The interaction of the new superor-dinated system for the control of routes OPC. The OPC interface ensures the smooth exchange of information between different control components. The diploma thesis was undertaken in co­operation with the University of Applied Sciences in Hannover: Kamil Janus was supported in this project by Professor Rüdiger Kutzner and Jörg Brouwer of Sasol.

Zenon as the optimum solution for transport control

After extensive market analysis, Manfred Rohwer and Jörg Brouwer chose the software package zenon from COPA-DATA. zenon is now used in the alumina production area. zenon sup­ports the flexible transport of alumina products that have to be delivered from the source to the destination while going through storage, processing and packaging. Now, Sasol uses two redun­dant zenon operating stations in a central control room ensuring high availability routing control. There were many reasons for choosing zenon:

► Sasol needed a modular solution that would be easy to extend

► the intuitive zenon development environment allows for flexible, quick engineering and implementation of new software components, zenon has an integrated soft PLC - straton the comprehensive support provided by COPA-DATA.

Automated route selection saves time and gives a better overview

With the new routing control system, users can now config­ure 665 different paths. At the same time, they always have an overview of the status of every path. As zenon communicates with the process control system, via the OPC interface, which also allows for the manual control of each valve, zenon must be able to quickly react to all inputs. This task is performed by the straton programming system, which is integrated with zenon. The sequences developed within straton react to all possible states of the routing control system. “The control system we were us­ing required a lot of maintenance. At the same time, we could not extend the system as we wished to”, Jörg Brouwer explains. He states that the process stations and the system bus experi­enced such a high load that switching actions would sometimes take more than a minute with the old control system. “Now, the switching actions are limited only by the speed at which the valves can move. Users can now react really quickly and easily to all events and situations.” At the same time, the operators can still manipulate the valves with the process control system. “This allows us to act faster and more flexibly.”

The application of zenon with straton by SASOL demon­strates the effectiveness and flexibility that this combination provides; improving plant operation and providing a reliable and expansible solution.

❚❚❚ ArcelorMittal is based on a site of around seven square kilo­metres next to the Weser River in Bremen, where it has been producing steel since 1957. This integrated steelworks includes plants for all production steps from pig-iron production to thin sheet metal. The company produces exclusively sheet-steel products and today includes a blast-furnace plant, an LD steel­works, a continuous casting facility, a hot-rolling plant, a cold-rolling plant and two galvanising plants. At present this Bremen steelworks employs 3,600 people, and the production target for the current year is 3.2 million tonnes of steel slabs. In addition to its steelworks in Germany, this international group is repre­sented in more than 60 countries, employing a total workforce of around 310,000. The company achieves a turnover of around 70 billion Euros and commands a share of around ten percent of the international market.