Cold Metal Melting Capacity up 50%. Waste now less than 2%.
Acting as a sub-supplier to Linde Gas, Invensys Eurotherm provided an intelligent burner control solution at Hydro Aluminium in Norway for control of Low-temperature Oxyfuel burners on a total of 4 aluminium furnaces.
By using the low temperature Oxyfuel technology Hydro Årdal can replace 20,000 tonnes of liquid primary aluminium, by re-melting cold metal. Previously, in PFA2, the charge mix was 8 tonnes cold and 22 tonnes liquid metal, and now the mix is 13 tonnes cold and 17 tonnes liquid metal. The overall average re-melting capacity increase is 50% for the four furnaces at the cast house.
This solution not only increased capacity on melting cold metal, but also provided large energy savings in the production process. The Foxboro T2550 Process Automation Controller combined with a Safety-PLC to comply with regulations and a HMI, in conjunction with Linde Gas Oxyfuel burners has provided significant economic savings and also supported Hydro’s commitment to reduce greenhouse emissions and reduce dross.
In general the use of Oxyfuel combustion substantially increases the thermal efficiency of a furnace. This is due to the fact that radiant heat transfer of furnace gases produced by Oxyfuel combustion is significantly more efficient than those of air-fuel. Due to the absence of nitrogen in the combustion mixture, which does not need to be heated up, the volume of exhaust gas is also substantially reduced, thus lowering total heat loss through the exhaust gas.
Thanks to improved thermal efficiency, heating, melting rates and productivity are increased for a given process, while, at the same time, saving on fuel and reducing CO2 and NOX emissions.
The two lines for primary foundry alloys production at Hydro Aluminium’s Årdal works converted to Low temperature Oxyfuel resulted in a 60% increase in re-melting capacity and a 50% reduction of fuel consumption and significant reduction of CO2 and NOX emissions
The Challenge
- Accurate combustion control and smooth transitions
- Optimize energy output over melting cycle
- Economic and environmental savings
The Solution
- Eurotherm Intelligent Burner Control System
- Combined with Linde Gas Oxyfuel Burner
The Result
- Energy savings at 50%
- Re-melt capacity up 50%
- Dross less than 2%
- Reduced emissions
Production has now been increased by the control system, with cold aluminium melting capacity up 50% while waste is less than 2%.
Aerial view of Hydro, Norway – Pictures courtesy of Hydro and Linde
“The key element Hydro needed was increased capacity on melting cold metal, the solution gives them that alongside large energy savings, It was vital to provide accurate combustion control and a smooth transition between all aspects of the cycle, while optimizing the melting cycle and applying the maximum energy when the thermal efficiency is highest.”
Lars-Göran Elfgren, Eurotherm Project Manager.
