A settling chamber at a coal-burning installation has the following chamber dimensions, operating conditions, and inlet particle- size distribution, where 1 pound = 7,000 grains. Determine the collection efficiency for each particle-size range, and the overall particle-collection efficiency. Assume the settling velocity, ut, is one-half of that computed by Stokes’ law.

Chamber width = 3.29 m, chamber height = 0.75 m, and chamber length = 4.57 m.

Volumetric gas feed rate = 70.6 ft³/s at std. conditions of 32°F and 1 atm.

Actual gas temperature and pressure is 446°F and 1 atm.

Actual gas viscosity = 2.60 x 10^–5 N-s/m², and gas density is negligible compared to particle density, which is 2.65 g/cm³.

Inlet dust particle-size range, um 0-20 20-30 30-40 40-50 50-60 60-70 70-80 80-94 94+ Adapted from [24]. dp, average diameter, um 10 25 35 45 55 65 75 87 94+ Grains/ std ft 0.0062 0.0159 0.0216 0.0242 0.0242 0.0218 0.0161 0.0218 0.0782 Weight % of particles 2.7 6.9 9.4 10.5 10.5 9.5 7.0 9.5 34.0