Filter bag analytical investigation from an aluminum smelter Gas Treatment Center (GTC) dust collector (AA9)

ISSUE

The changeout of filter bags in large capacity dust collectors such as those installed in the Gas Treatment Centers (GTC) of aluminum smelters is always a costly operation in terms of consumable (purchase of filter bags) and manpower. Furthermore, poor planning of bag changeout can cause operational problems, out of compliance stack emission and unplanned shutdown, all of which can have major economic impact. Therefore, in order to control these costs, it is essential 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 the residual bag life is therefore of the utmost importance for a reliable filter bag maintenance and changeout planning. With the expertise and analytical methods developed by STS Canada, filter media performance and parameters can be evaluated and tracked using a series of simple laboratory tests on new and used filter bags.

Depending on the level of analysis carried out, it is possible to determine the level of bag wear, the residual bag time or the cause of bag failures. In this specific case, STS Canada was commissioned to perform the necessary analyses to assess the level of deterioration of filter bags from two (2) Gas Treatment Centers (East GTC and West GTC) and determine if the level of wear and state of deterioration is consistent with the filter bag maintenance and replacement program.

RECOMMENDED SOLUTION

STS Canada performed the analyses of the physical, mechanical and aeraulic properties of properly selected filter bags in each GTC. Subsequently, the STS Canada team interpreted the results to determine the level of deterioration of the filter bags and whether they had reached the end of their useful life.

RESULTS

Following the analyses of the filter bags taken from the two Gas Treatment Centers, STS Canada determined that the bags had not yet reached the end of their useful life. However, the level of degradation of the airflow properties was higher for bags of the East GTC than for those of West GTC. It ensued a higher pulse cleaning frequency at the East GTC than at the West GTC and a shorter residual bag life for the East GTC. STS Canada recommended a bag changeout schedule that took into consideration those differences and redacted a filter bag specification to assist the selection of the filter bag supplier and to ensure that premature bag deterioration and short bag life will be avoided.