流体力学与传热课件Filtration Operation-Basic Equations.ppt

For a filter press the flow rate of washing where the cross-section of the frame A′=A/2, then, substitution of A′=A/2 in equation (3.4-31 ) gives the washing rate for a plate and frame filter press (3.4-33) Hence the relationship between the flow rate of washing and that of last filtration in a filter press is (3.4-32) (3.4-33) Problem For constant pressure filtration, if the filtering medium (septum) resistance is ignored, the filtering time is double and other operating conditions keep unchanged, the filtrate volume will be( ) （A) double; (B) half of original; (C) 21/2 of original; (D) uncertain Problem Which the statement is correct in following ( ) Filtration rate is proportional to filtration area (A). Filtration rate is proportional to the square of filtration area (A2). Filtration rate is proportional to the volume of filtrate (V). Filtration rate is inversely proportional to the resistance of filter medium. Problem A standard cyclone separator, 0.5m in diameter and inlet width B=D/4, is used to remove the particles from dust gas. If the gas enters at 15m/s and the numbers of spirals N in the cyclone takes as 5, at what critical diameter of particle will occur? (viscosity of air=0.018mPa and density=1.3 kg/m3; density of particle=2700 kg/m3 .) solution From equation A filter press of 0.1m2 filtering area is used for filtering a sample of the slurry. The filtration is carried out at constant pressure with a vacuum 350mmHg.The volume of filtrate collected in the first 5min was one liter. (1) How much filtrate will be obtained when the filtration has been carried out for 10min on assuming the cake to be incompressible and the resistance of filter medium is negligible ? (2) How much filtrate will be collected for filtrating time of 10 min if the filter press operates at vacuum 700mmHg. Problem Problem A slurry is filtered in a plate and frame press containing 12 frames, each 0.3m square and 25mm thick. During the f