Problem 1. Batches of slurry are filtered at a constant differential pressure of 600 kPa. This filtration takes 2 hours per batch and 20 m3 of filtrate are collected. The pressurized feeding system is to be replaced by a positive displacement pump that produces a constant rate filtration. The same filter is to be used and the overall productivity (filtrate volume per batch time) is to remain the same. If the maximum final differential pressure cannot be greater than 900 kPa, can the filter produce 20 m3 of filtrate per batch under constant rate operation? The resistance of the filter medium is negligible compared to that of the filter cake.
Problem 2. The grade efficiency for a cyclone is given by the following relation:
|
Size Range pm
|
0-5
|
5-10
|
10-15
|
15-20
|
20-25
|
25-30
|
|
Feed mass (kg)
|
10
|
15
|
20
|
25
|
20
|
15
|
|
Coarse product ,
|
?
|
?
|
?
|
?
|
?
|
?
|
If the cut size is 10 pm, and the feed contains the following particle size distribution: what is the mass distribution for the coarse particle cut? What is the total efficiency?
Problem 3. A cyclone of 0.5 m body diameter has an Eu value of 50 and an Stk50 value of 5 x 10-3. Using an aliiwble pressure drop of 1200 Pa, what is the voluthetric flow capacity of the cyclone and the cut size? The gas has a density of 1.5 Kg/m3 and a viscosity of 2 x 10-5 Pa-s. The particle density is 1800 Kg/m3.
Problem 4. 1500 Kg of particles of density 2500 Kg/m3 form a packed bed that is 1 m high in a circular vessel that is 1 m in diameter. A gas of density 1.5 Kg/m3 and a viscosity of 2 x 10-5 Pa-s is passed upward through the bed. What is the initial void fraction in the bed? If the gas velocity in the bed is one-half of the minimum fluidization velocity, what is the resulting pressure drop?