Content area
Full text
The Sohar Aluminium anode baking furnace was commissioned in 2008, and furnace performance since has remained at excellent levels in terms of gas consumption, baking level, fire productivity, tar emissions and firing cycle range. Some of the challenges in achieving these results are discussed.
Sohar Aluminium is a joint venture between Oman Oil (40%), Abu Dhabi Water and Electricity Authority (ADWEA) (40%) and Rio Tinto Alean (20%) and operates a greenfield aluminium smelter in Oman.
This smelter, started in 2008, operates 360 reduction cells using AP 36 technology and produces an aluminium tonnage of 374kVy at current operating amperage of 37OkA.
More than 200kt/y of carbon is needed to supply the 360 reduction cells. The carbon plant employs the latest AP technology and includes a 52 section gas fired horizontal baking furnace comprising three fires equipped with an Innovatherm firing system and operating at a 24 hour fire cycle at full capacity.
Furnace design characteristics
The Sohar furnace is characterised by the following specific points:
* A section design with 9 pits and 10 flue walls per section.
* A very efficient pit packing geometry to maximise the amount of carbon in the pit.
* innovative headwall expansion joints.
* A fluewall designed using proven modeling techniques.
* The ability to achieve required baking levels by the use of a 4th burner ramp on shorter cycles when necessary.
* The ability to operate at a fire cycle range of 24 to 36 hours by the application of a new process control methodology that favours optimum combustion.
These design characteristics in turn deliver a productivity level of 210kt baked anode with three fires. They reduce the ground surface area to approximately 15Om by 35m and minimise the capital expenditure.
The 9 pit configuration and the optimised pit sizes lead to a high anode/refractory ratio. This ratio is a measure of the refractory impact on energy consumption I1I Fig 1 presents the evolution of this ratio from 1980 until today for open type AP baking furnaces. Sohar has the highest ratio which contributes to low energy consumption in the furnace.
The 9 pit configuration also results in a long headwall, which increases the risk of distortion in the event of uncontrolled expansion. A headwall expansion joint...