Application

Eighty-ton, steel-scrap-melting, electric-arc furnace, producing carbon and low-alloy steels. An Fläkt Optipulse® pulse-jet style baghouse (low pressure, high volume pulsing), 840 bags, 2,000 m of filter area. Filtering velocity of 1.33 m/min, a baghouse operating temperature between 130°C to 180°C due to the direct-furnace-evacuation-only nature of the fume-extraction system. Furnace gas stream mildly acidic and humid.

Optimization Potential

The pressure drop across the filters would limit the system draft capacity within 60 to 90 days of installation (240 mm w.g.). The lack of draft created unacceptable meltshop emissions and limited production, and allowed for higher CO emissions due to inadequate combustion air at the furnace elbow gap. Occasional baghouse visible emissions, usually due to fume bleedthrough and broken bags. Pulse interval between baghouse rows was 10 seconds.

Solution

Company installed 840 GORE® membrane/RYTON® felt filter bags with a RASTEX® Scrim.

Results

System now pulls design flow rates. Pressure drop is held at 80 mm w.g., with a between-row interval of 60 seconds. Baghouse emissions are near zero. Meltshop emissions are clear, with no lost production time due to interior meltshop conditions. The additional draft allows for better combustion of the CO gases. The baghouse is now so clean that the customer decided to paint it so that it would have a more attractive appearance to the surrounding community and regulatory agencies. Current bag life is 24 months (as of February 1996) on a three-year guarantee, with no performance degradation or bag failures.

FOR INDUSTRIAL USE ONLY

Not for use in food, drug, cosmetic or medical device manufacturing, processing, or packaging operations.