Process fault diagnosis subsystem is used to test the aluminum electrolysis anode effect and the rolling aluminum fault occurred in the process.
Two subnetworks are as follows: one is detecting anode effect and the other is rolling aluminum.
A study of emission of greenhouse gases C[F.sub.4] and [C.sub.2][F.sub.6] during anode effect was undertaken and reported upon in a paper by A Oygard et al.
These are: acceptable alumina dissolution, satisfactory mixing to avoid concentration gradients and a satisfactory rate of alumina increase after anode effect. It is shown that alumina dissolution requirements are most difficult to satisfy.
In the aluminium industry, reported PFC emissions are known to be associated with momentary process imbalances known as Anode Effects.
"We believe our new research is the first of its kind as it aims to tackle emissions from minute changes rather than just reducing Anode Effects that we can all detect today.
The main sources of greenhouse gases (GHGs) at Dubal are: mobile equipment and vehicles; natural gas consumed in the furnaces, baking kilns and rodding room; anode consumption during the aluminium reduction process; perfluorocarbon (PFC) emissions from anode effects
; and power generation activities.
In recent years, this has included introducing new preventative maintenance procedures; alternative anode sizes; and new controls to anticipate and prevent anode effects
. We've also installed evaporative cooling systems on several gas turbines; replaced conventional burners with regenerative see burners in one of our furnaces; and commissioned a new combined cycle turbine," Dubal Power and Desalination Vice-President Tayeb Awadhi said.
"The reduced use of fossil fuel has obvious resource and environmental conservation benefits; while significantly fewer anode effects
compared to lower amperage technologies also contribute to lower perfluorocarbon emissions.
In addition to boosting production capacity, the new technology reduces emissions of perfluorocarbons, a greenhouse gas generated in the aluminium smelting process from anode effects
, by 96%.
* Perfluorocarbon (PFC) gases are greenhouse gases generated during anode effects
in the potrooms.