Q4. (a) An electrostatic precipitator is installed at an iron and steel plant to capture particles of 0.3 um in diameter from the flue gas emitted from the stack at 250 C flowing at 12 m3/s. The migration velocity is expressed as w = 3 x 105 dp, m/s Determine the plate area required to collect the particles with 99.5% removal efficiency. (5 marks) (b) Explain why particles in intermediate size are less efficiently captured by ESP. (4 marks) (c) Suggest another ONE (1) type of air pollution control device which is also suitable for removing the particles stated in Q1(a)