Pulverized Coal-Fired Utility Boiler

Application

Pulverized coal-fired utility boiler with a baghouse in parallel to an existing mechanical collector/electrostatic precipitator system. Baghouse effluent used to reheat flue gas leaving SO2 scrubber.

Optimization Potential

The pulse jet baghouse was designed at an A/C ratio of 3.8 cfm/ft2 (gross) 5.0 cfm/ft2 (net) with on-line or off-line cleaning capabilities. Design gas flow of 45,000 acfm at 400ºF. Conventional woven glass bags quickly blinded due to fineness of dust (25% < 3.3 µ) and the formation of sulfate compounds in the weave of the fabric. Bag life was < 9 months. The pressure drop was 10" w.g. at 75% of design airflow. TEFLON® felt and fiberglass felt bags were tested and found to blind quickly also.

Solution

GORE® membrane/Teflon® B fiberglass fabric filter bags (16.8 oz fabric) were installed. Pulse pressure was reduced to 70 psig; diffusers were removed.

Results

Design airflow achieved. Bags cleaned on demand at 6" w.g. SO2 scrubber costs reduced by over $12,000/month (less reagent used and less fuel for reheat). Installed second set of GORE® membrane filter bags. During annual outages, the first and second set of GORE® membrane filter bags were replaced after 20 months and 36 months respectively, even though the bags had not failed.