Assessing the Performance of Microfibrous Entrapped Sorbent Enhanced Gas Phase Filter in a Full Scale Test Rig

A full scale test rig was designed and constructed based on the ASHREA Standard 52.2 to systematically assess the performance of the filters in terms of pressure drop, gas life, single pass removal efficiency, etc. Pre-qualification exams including the air leakage, face velocity uniformity, challenge gas uniformity were conducted to verify the reliability of the test rig. The filters were subjected to a 5ppm hexane gas and operated at 200fpm face velocity. For a commercial carbon filter (24”x24”x1/2”, 2kg carbon), the initial removal efficiency was only 60%, the 50% breakthrough time was 150min, and the pressure drop was as high as 0.8” W.G. The slow mass transport of large particle size and the severe channeling and bypass flow were considered as the main reason of the low efficiency of filter. To improve the performance of the filters, a novel multi-element structured array (MESA) and composite bed design was developed. The MESA can significantly increase the carbon load and available media area. For a W shape MESA, the carbon load increased to 8kg per unit, and the initial removal efficiency increase to about 80%, while the 50% breakthrough time increased to about 1000min under the same operation condition. Meanwhile, the composited bed applied microfibrous entrapped sorbent (MFES) as a polishing layer to remove the penetrated or by-passed gas from the preceding bed, increasing the initial remove efficiency from 60% to more than 99%.  The combination of MESA and composite bed provides a solution to deliver clean air with long protection period. This is very important to protect the power system such as fuel cells stack in the naval ships and stationary power plant.