Air used in industry as an oxidant, has a high nitrogen content (78% N2), which is useless ballast. The use of oxygen reduces nitrogen in the furnace, full replacement of air by oxygen allows to get rid of the nitrogen. Reduction of nitrogen increases productivity, reduces NOx emissions and increases thermal influence due to higher partial pressure of CO2 and H2O.
Linde has carried out over 150 oxyfuel installations in various processes in aluminium production.
The benefits of oxyfuel combustion can be summarised as:
Up to 100% higher melt rate for increased furnace throughput.
50% lower energy costs due to a more highly efficient combustion and improved heat transfer.
Unwanted containments in low grade aluminium scrap can be turned into valuable energy.
Better possibilities to control the process.
Possibility to increase power input into furnace.
Up to 70-80% less flue gases volume.
Substantially lower emissions of carbon dioxide (CO2), nitrogen oxide(NOx), carbon monoxide (CO).