Content area
Full Text
German minimill BSW of the Badisene Group is charging billet to reheat furnace No 2 at an average temperature of 750°C and achieving 85% of all billet hot charged. This has resulted in a 50% reduction in natural gas consumption and improved productivity in the mill by between 11% for sections over 7.5mm diameter and up to 55% for 14mm sections. New tools such as simulations are employed to continuously improve the process.
ENERGY prices for gas and oil are on a rising trend while prices and sales volumes for rolled products remain stagnant. This now influences the focus of the logistics consulting services of BSE - the engineering and consulting company of the Badisene Group - with regard to material flow optimisation in the steel plant and rolling mill.
In the past the primary task to achieve an increase in production was to eliminate internal transport bottlenecks or to prevent them when planning new plants. Today, the focus is increasingly put on cost reduction.
The billet yard, which is the link between the steel plant and the rolling mill, has often been a neglected interface in the entire material flow, but it offers a valuable approach to reduce energy consumption and so the cost of running the reheat furnace. This can be achieved with a minimum of investment so providing an extremely short payback time to optimise material flow to the furnace. These savings counter the trend of continuously increasing energy costs.
BSW can call on 30 years of experience in the field of hot charging and is therefore an excellent show-case to illustrate optimisation of this technique. In the past 10 years, gas consumption on the pusher furnace at the bar mill RM 1 at BSW has been reduced by 90 to lOOkWh/t to a value of 240kWh/t (Fig 1). This is a 28% reduction since 1996.
Also, in wire rod mill RM2, which mainly focuses on hot charging, the average hot charging rate has, for five out of 16 years achieved an average proportion of 85% of billet hot charged at an average temperature of 750°C. This corresponds to a natural gas consumption of less than 200kWh/t on average for both rolling mills at a mean hot charging rate of 76%.
Hot...