6.5 MW Facility Utilizing Four Vibra-Grate Stoker Boilers; Oil or Coal-Fired

Application

6.5 MW facility utilizing four Vibra-grate Stoker boilers; oil or coal-fired. Off-line American Air Filter reverse air baghouse filtering 242,600 acfm @ 393ºF with a designed air-to-cloth ratio of 1.83 cfm/ft2 (gross) and 2.01 cfm/ft2 (net). Baghouse utilizes 2,112 GORE-TEX® membrane filter bags.

Optimization Potential

2,640 conventional acid resistant fiberglass fabric filter bags were used with operational bag life of less than one year due to acid degradation of conventional fiberglass fabric; complete changeout of filter media required annually. Testing of the filter bags revealed greater than 80% strength loss of the fiberglass fabric after 10 months. In addition to replacement filter bag costs, installation/maintenance expenses and boiler downtime, the yearly expense for hazardous disposal of the conventional fiberglass fabric filter bags was approximately $80,000.00. Hazardous disposal required, due to high levels of arsenic in fly ash collected within filter bags.

Solution

Installed 2,112 GORE® membrane/heavy duty woven GORE® fiber fabric (12.5 oz/yd2) filter bags and 528 GORE® membrane/GORE® felt (20.0 oz/yd2) plugs. Increased A/C ratio to 2.29 cfm/ft2 (gross) and 2.51 cfm/ft2 (net).

Results

Mullen burst strength tests of filter bags revealed no loss of strength after 10 months of operational service (6+ year bag life expected). During full four boiler operation, baghouse pressure differential was maintained at 3.5" w.g. before cleaning and 2.0" w.g. after cleaning. Compartment cleaning initiated every other day with only 10 seconds of reverse cleaning air utilized. Testing revealed total particulate emissions of 0.0024 gr/acf @ 7% O2 using a six-hour sampling time. Testing revealed total particulate emissions of 0.0024 gr/acf @ 7% O2 using a six-hour sampling time. Testing of particulate less than 10 µ (PM-10) revealed emissions averaging <0.00049 gr/acf @ 7% O2.