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The bag life improved, while baghouse down-time, maintenance costs, and stack emissions have all been drastically reduced. Bags have survived several acid upsets which would have completely destroyed the previous bags.

GORE Membrane Filter Bags improved bag life to three to four years, while baghouse down-time, maintenance costs, and stack emissions have all been drastically reduced. Baghouse emission rates are lower than the required regulatory limits and draft at the blast furnace is adequate for the operation. The hygiene conditions inside the plant have improved as a result.

The baghouse differential pressure decreased resulting in increased gas flow without expanding the baghouse. This was achieved even though the plant installed considerably less GORE^® Membrane Filter Bags than they had used when operating with non membrane bags. They closed the dilution air damper so that all the baghouse capacity is applied to the furnace. The frequent bag failures stopped and the inside of the baghouse is much cleaner.

By removing the U Tube cooler pressure loss the plant was able to open the canopy hood dampers more. This allowed increased secondary flow from the shop. With less flow resistance through the DEC system the primary evacuation has also increased with better fume capture at the furnace.

Eliminated the need for sonic horns and dramatically decreased baghouse pressure drop. Gas flow increased significantly, even with fewer filter bags than had originally been used in the non membrane sytem.

Bag failures stopped since the GORE ePTFE membrane and the fiberglass backing material are not subject to hydrolysis and resist spark damage. The bags have not required tensioning since start up. Furnace suction and shop evacuation have improved due to the more consistent operation of the baghouse.

An emergency order was placed for GORE® Low Emission Filter Bags. The new filters were rushed to the plant site, where the leaking filters were completely replaced.

Results showed furnace extraction has been increased by 41%, blockage was eliminated from furnace offtake ducts, hood temperatures were been reduced and stack emissions were below 5 mg/Nm3.

Extraction at the furnace has increased above the design. The main fan damper is partially closed to control the extraction at the furnace. Tapping fume has been added into the same baghouse. The smelt house environment is much cooler, and it led to a decrease in maintenance of the electrode system and mechanical stokers.

System optimization and installation of GORE filter bags resulted in improvements to the baghouse and overall production process. Emissions from all the filters are well below 10 mg/Nm, maintenance on the filters has been significantly reduce, and extraction volumes from the furnaces have been significantly increased, leading to lower stack temperatures.