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Original set of GORE® membrane filter bags were in service for more than three years and were removed during a planned maintenance shutdown. Emission levels measured less than required by standards/regulations during this operational period.

After the GORE Filter Bags were installed, bag life increased from one year to five years. Production downtime caused by the need to replace bags prematurely was virtually eliminated.

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.

The system now runs with a consistent airflow of 41,000 acfm and compartment pressure drops of 4.5 - 6.5" H2O. The customer is able to run two ladles simultaneously, increasing metal throughput.

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.

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.

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.

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.