Making Welsh steel energy efficient and eco-friendly

A Welsh steel company has a hot strip mill with two gas reheat furnaces. Both feature three Combustion Air Fans to pressurise the burner manifolds. Originally the fans had Direct-on-Line starters, with the airflow and pressure controlled by dampers in the air ducting.

It was decided to change the system so that the air pressure is controlled by varying the speed of the fans, to lower running costs and reduce environmental impact. Replacing the motor starters with variable speed drives, we also had to modify the 3.3KV switchgear and change the protection relays from motor protection to feeder protection, since that is now performed within the variable speed drive panels.

 

Our Solution

Six new variable speed drives were enclosed in a pre-fabricated outdoor enclosure – three for furnace ‘A’ and three for furnace ‘B’. The completed container was delivered by road and required supervised offloading and positioning onto prepared concrete foundations.

• Modifying the original system and switchgear required detailed analysis and coordination, involving: Modified gas control panels including hardwired safety interlock and PLC IO interface changes
• Interfaces to enable correct signals at correct terminals
• Complete set of cable schedules
• 3.3kv breaker modifications including interface circuit
• Cable installation including jointing of the 3.3kv motor cables
• Install new remote IO cubicle with Ethernet communication to SCADA/PLC system and individual variable speed drives

 

Results

• Saving in excess of £10,000 per week on energy costs
• Reduced environmental impact
• Installed and commissioned with minimum disruption to the production schedule

 

Client Feedback

The project went to plan and was completed on time ready for production. The client is extremely pleased with the system, which is now operating successfully and saving in excess of £10,000 per week on energy costs.