A million pounds in annual energy savings is expected since the installation of drives on pumps at Corus Strip Products.

As part of a plant-wide energy saving programme, 24 industrial drives, ranging from 140 to 400kW, are being installed to control pumps on the hot strip and cold mills and three fans on the coke ovens at Corus Strip Products.

The pumps recirculate cooling water in the mills, while the fans are used for dust extraction at the coke ovens.

The project was initiated in 2006, when Guy Simms, leader of the energy optimisation team at the Port Talbot site, started looking into possible energy savings at the plant. The use of drives seemed to be a good solution to help reduce energy costs on the mills.

Simms explains: “The pump and fan motors were oversized and running longer hours than necessary. Much of the equipment on the site was installed during the sixties, seventies and early eighties. At the time, it was common practice to oversize the equipment by as much as 50 per cent, to make sure it was sufficiently robust. In many ways this was a successful policy as the equipment has lasted all these years.”

ABB was chosen to supply drives for the project. Simms said: “With the ABB drives we can fine-tune the applications to a degree that was not possible in the past.” The applications have varying demand but until now, the pumps and fans have been running continuously at full speed. Running to demand is expected not only to reduce energy costs but also to save water and improve control, particularly of the cold mill, which could result in better product quality.

Low voltage drives
Low voltage drives were specified as they have a small footprint, compared to medium voltage drives. A transformer reduces the voltage from the 3.3kV network on the site to the 690V used by the drives. ABB was the preferred choice of drives supplier as there is already a lot of ABB equipment on the site. The engineers were happy with the performance of the existing equipment, and standardising on equipment from one manufacturer reduces training needs and makes maintenance easier.

The Port Talbot site is one of the biggest steelmaking plants in the UK. Energy is Corus’ second highest cost after raw materials. The costs and revenues of the business are fixed, so high productivity is crucial to stay competitive.

“Using drives to improve energy performance is not just a matter of payback, it is also a modification with low risk,” said Simms. “We cannot afford production stoppages. If a drive solution does not work out, the worst that can happen is that we have to turn up the speed to 100 per cent again. An alternative approach could be to install a new and smaller pump, but then we would also need new pipes and a new bedplate. Once built, we would be stuck with this solution. We preferred to just add new drives to existing applications that have already proven their reliability.”