By expanding an undersized baghouse, the Lafarge Roberta plant in Calera, Alabama was able to reduce daily cleaning cycles by a factor of ten and eliminate frequent bag changes due to excessive abrasion.
In 2002, the Lafarge Roberta plant built a new cement line that included a ten-compartment pulse-jet raw mill/kiln baghouse. The new baghouse turned out to be undersized. Lafarge consulted with GE Energy to correct the situation and improve the line’s efficiency.
In production, air volume was 22% over design capacity. The increased air volume pushed the air-to-cloth ratio to the limit, causing drastic increase in filter bag cleaning cycles and leading to bag failure due to flex fatigue. The increased volume also caused high velocity in the ductwork and in the hoppers, creating abrasion around the top of the bags. In the first three years of operation, two sets of filter bags (12 880 total) were used.
Analysis showed that the baghouse needed to be expanded. An additional 8% increase in air volume was also needed. Among the factors to be considered were how to redesign all the ductwork to maintain proper velocity and proper air and dust distribution. In addition, changes to the inlet baffling in the baghouse hoppers were required.