Analysis of filter bags from an anode bake furnace dry scrubber in an aluminium smelter (AA1)

ISSUE

The changeout of filter bags in large capacity dust collectors such as those of an anode baking furnace dry scrubber is always a costly operation in terms of man power and consumables. Furthermore, poor planning of bag changeout can entrain operational problems, out of compliance stack emission and reduced production, all of which can have major economic impacts. Therefore, in order to control these costs, it is imperative to put in place a reliable filter bag monitoring and replacement plan.

TECHNOLOGICAL CHALLENGE

The lowest maintenance cost for bag changeout is achieved when filter bags are replaced at the very end of their useful life. The forecast of residual bag life is therefore of the utmost importance for a reliable filter bag maintenance and changeout planning. This is where STS Canada has an added value: using methods developed through years of experience, filter bag useful life can be determined with simple lab analysis on used filter bags.

Depending on the level of analysis performed, we can determine the mechanical strength, the filtration and aeraulic properties, the estimated residual life and the cause of bag failure. In the present history case, STS was given the task of determining the deterioration level of nine (9) filter bags pulled out from four (4) anode bake furnace dust collectors.

RECOMMENDED SOLUTION

STS Canada performed the analysis of the nine (9) used filter bags to determine their physical, mechanical, and aeraulic properties. Based on this analysis, STS Canada was able to determine the level of bag deterioration and if the bags had reached the end of their useful life.

RESULTS

The analysis of the nine (9) bags demonstrated that the useful life had not been reached yet. However, the level of degradation of the filter bags' aeraulic properties was such that STS Canada recommended their replacement at the next shutdown scheduled in the next 6 months. In doing so, the company ensured reliable bake furnace operation and avoided unscheduled dust collector shutdown and its costs impact.