SH5107: The pressure drop across a fabric filter is 22 mm w.g. when the volume flow rate: Industrial Ventilation Assignment, NUS, Singapore

Question 1

(A) The pressure drop across a fabric filter is 22 mm w.g. when the volume flow rate is 2 m3/s cmm. Given: Total filtration area is 90 m2. Determine the clean filter resistance k (answer in mm w.g./ mps). Assume STP (21°C, 1 atm or 760 mm Hg).

(B)  In question (A), if the air moves through the bag filter at 80°C and 1 atm (760 mm Hg). Determine the pressure drop across the filter at the same air flowrate.

Question 2

(A) Dry air moves through a cyclone dust collector at STP (21°C, 760 mm Hg). The static pressures at the inlet and outlet of the cyclone are -55 mm w.g. and -110 mm w.g. respectively.  If the velocity pressure of air leaving the cyclone is 20 mm w.g., what is the loss factor of the cyclone? Assume the inlet and outlet diameters are the same.

(B) In Question (A), if the cyclone is operating at 50°C and 670 mm w.g., determine the press drop at the same velocity pressure.

Question 3

An industrial cyclone is operating at an airflow of 0.70 cms and has a pressure drop of 110 mm w.g.. If the airflow is increased to 1.0 cms, what is the new pressure drop across the cyclone? Assume STP (21°C, 1 atm)?

Question 4

It is desired to clean the exhaust from a line kiln. A two-stage cleaner is selected i.e. a cyclone followed by a wet centrifugal collector. The cyclone has a collection efficiency of 30% and the wet centrifugal collector has an efficiency of 80%.

(a) Determine the combined collection efficiency.

(b) If the inlet exhaust concentration to the cyclone is 200 mg/m3, what is the effluent concentration leaving the wet centrifugal collector?

Question 5

An electrostatic precipitator operating at an airflow rate of 2.5 m3/s has a collection efficiency of 97%. If the airflow rate is increased to 5 m3/s, what is the new collection efficiency?