Analysis of fiberglass filter bags for the dry scrubber of a municipal solid waste incinerator (AA3)

ISSUE

A municipal solid waste incinerator in the Province of Quebec tested a new type of filter media for its dry scrubbing unit. The tested bags were made of woven fiberglass with an expanded PTFE membrane (ePTFE) on its surface. Until now, the dust collector of the dry scrubbing unit has been equipped with regular woven fiberglass filter bags (without membrane) which is a filter media commonly used for this application.

Following the trial with the new type of bags, the incineration plant’s management wanted to know whether this new type of filter bag should become their standard for the next bag changeout instead of the original type of bags. To assist them with this task, STS Canada was mandated to perform the relevant analyses and provide recommendation on which type of filter bags were best suited for their operation.

RECOMMENDED SOLUTION

STS Canada performed the physical, mechanical and aeraulic analyses of both types of filter bags. The results were interpreted to identify which filter media was the most suitable for their operation.

RESULTS

The analyses revealed that both types of filter bags were expected to have a somewhat comparable useful life. However, the bags with ePTFE membrane presented better mechanical and aeraulic properties than the original woven fiberglass bags and offered a better resistance to acid gases.

Hence the woven fiberglass bags with ePTFE membrane offered advantages over the original bags but the plant should not expect a significant improvement in useful bag life. The decision was left to the plant to decide which type of filter bag to select for the next bag changeout considering that the aeraulic advantages of the ePTFE membrane bags must be balanced against the superior price of these bags compare to regular woven fiberglass bags.

Finally, the analysis revealed that after 12 000 operating hours the current set of woven fiberglass filter bags had almost reached the end of its useful life and that a complete bag changeout should be planned for the coming months.