1.) An electrostatic precipitator (ESP) is being designed to collect flue gas particles at a power plant. The following information has been collected: electric field intensity = 100,000 V/m, and average particle charge = 0.30 fC (1 fC = 10-15 C). Characterization of the air stream yields the following information: air viscosity = 18.5 x 10-6 Pa-s; average particle diameter = 1 m; airflow rate = 1.5 m3/s; air temperature = 120° C; and average inlet particle concentration = 100 mg/m3. The state regulators are granting this facility a permit to have an average stack (effluent) concentration of 0.5 mg/m3.
(a) Estimate the required removal efficiency of particles in the ESP.
(b) Estimate the required plate area to achieve the above removal efficiency by estimating a drift velocity of 2 cm/s.
2.) Lime (CaO) scrubbing is used to neutralize the sulfur dioxide in a stack. The chemical reactions are:
CaO + H2O Ca(OH)2
SO2 + Ca(OH)2 CaSO3 + H2O
Determine the amount of lime required to neutralize each kilogram of sulfur dioxide: