As part of the expansion of its Attunga facility in New South Wales, Unimin installed a Quick Lime Hydrator. The process is difficult to de-dust with a dry dust collector since it operates very close to the dew point temperature and the dust is extremely cohesive.
Luehr received the contract for the design and supply of the exhaust system. Having considerable experience in the process it was essential to choose the correct filter cloth, the correct bag configuration and a conservative filtration velocity. The Luehr DFR design was selected.
The Luehr DFR filter is an air pulse on-line cleaned filter using tubular filter elements (bags). The bags are mounted vertically in the collection chamber. Dust presented bags is collected on the outer surface of the bag and is periodically removed by pulsing with compressed air. The pulse-jet cleaning system, which efficiently distributes equal compressed air volumes to each bag for efficient cleaning, is controlled by monitoring the bag differential pressure and actuating cleaning on demand.
To minimise maintenance requirements on the filter an automated purge pulse cleans the dirty side differential pressure tapping point. The filter was fitted with Gore® 100% PTFE filter bags designed for excellent filter cake release and to withstand the highly alkaline conditions and any local high temperatures.
The system was installed on schedule and is performing well. The operators reported that the hydrator is much more predictable and easier to control since the installation of the Luehr baghouse. Emission levels of under 8mg/m3 are being achieved.