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Dimensions of a Standard Cyclone. Problem. Design of Cyclone Body diameter = 0.75 m Flow rate = 2.75 m 3 /s ρ p = 1600 kg/m 3 ρ g = 1.1 kg/m 3 µ = 2.5*10-5 kg/m-s High throughput H = 0.8 * body diameter W = 0.35 * body diameter Lb = 1.7 * body diameter Lc = 2.0 * body diameter
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Problem • Design of Cyclone Body diameter = 0.75 m Flow rate = 2.75 m3/s ρp = 1600 kg/m3 ρg = 1.1 kg/m3 µ = 2.5*10-5 kg/m-s High throughput H = 0.8 * body diameter W = 0.35 * body diameter Lb = 1.7 * body diameter Lc = 2.0 * body diameter Calculate the diameter of particle with 50% efficiency
Solution • Step 1: Inlet Velocity = Q/A = 17.46 m/s • Step 2: Number of effective turns Ne = (Lb + Lc/2)/H Ne = 3.375 • Step 3: Diameter of particle dpc = 10 µm
Scrubber • Efficiency where, k = Scrubber coefficient (m3 of gas/ m3 of liquid) R = Liquid-to-gas flow rate (QL/QG) ψ (Psi)= internal impaction parameter • Internal impaction parameter where, c = Cunningham correction factor ρp = particle density (kg/m3) Vg = speed of gas at throat (m/sec) dp = diameter of particle (m) dd = diameter of droplet (m) μ = dynamic viscosity of gas, (Pa-S)
Venturi Scrubber Absolute Pressure Drop Δp = pressure drop ( cm of water) ug = gas velocity (cm/s) Qt = liquid volume flow rate Qg = gas volume flow rate
Problem • Water is introduced into the throat of a venturi scrubber. The air velocity through the scrubber is 550 fps and the liquid to gas ratio is 8.5 gal/1000 actual ft3. Determine the pressure drop? Solution • Step 1: Absolute pressure drop is given by Δp = 4.8
Design of Electrostatic Precipitators • The efficiency of removal of particles by an Electrostatic Precipitator is given by η = fractional collection efficiency w = drift velocity, m/min. A = available collection area, m2 Q = volumetric flow rate m3/min
Migration velocity Where, q = charge (Columbus) Ep = collection field intensity (volts/m) r = particle radius (m) μ = dynamic viscosity of gas (Pa-S) c = Cunningham correction factor
Cunningham correction factor where, T = absolute temperature (°k) dp = diameter of particle (μm)
Problem • An ESP is designed to treat 50,000 m3/min with 97 % efficiency. Assuming an effective drift velocity of 2.5 m/min, calculate the required plate area and the number of plates. The plate size is 10 m by 5 m (height by length).
Solution • Step 1: Efficiency of an Electrostatic Precipitator is given by A =-[ (Q/w)*ln(1- η)] A = 70,000 m2 • Step 2: Number of plates = total area/plate area = 1400
Problem • Estimate the net cloth area for a shaker bag house that must filter 40,000 cfm of air with 10 grams of flour dust per cubic foot of air. Also specify the number of components to be used and calculate the total number of bags required if each bag is 8 feet long and 0.5 feet in diameter. The maximum filtering velocity for flour dust is 2.5 ft/min.
Solution • Step 1: Calculate total area and number of components required. A = Q/V • Step 2: Calculate the area of each bag. A = Π (d) l • Step 3: Calculate the total number of bags required. Number of bags required = Total area / Area per bag = 1270 bags Number of compartments 4000 sq. ft. / compartment