Tutorial Sheet
Q.No. 1.: During an air pollution monitoring study, the inlet gas stream to a
bag filter is 1,69,920 m3 /hr and the dust loading is 4577 mg/m3 . The outlet
gas stream from the bag filter is 1,65,040 m3 /hr and the dust loading is 57
mg/m3 . What is the maximum quantity of ash that will have to be removed
per hour from the bag filter hopper based on these test results?
Solution: Based on dust balance, Mass (in) = Mass (out)
Inlet gas stream dust = outlet gas stream dust + Hopper Ash
1. Calculate the inlet and outlet dust quantities in kg per hour Inlet dust
quantity = 169920 (m3 /hr) x 4577 (mg/m3 ) x 1/1000000 (kg/mg) =
777.7 kg/hr
Outlet dust quantity = 165040 (m 3 /hr) x 57 (mg/m3 ) x 1/1000000
(kg/mg) = 9.41 kg/hr
2. Calculate the quantity of ash that will have to removed from the
hopper per hour
Hopper ash = Inlet gas dust quantity - Outlet gas dust quantity
= 777.7 kg/hr – 9.41 kg/hr
= 768.2 kg/hr
Q.No. 2: If 35,000kg of whole milk containing 4% fat is to be separated in a
6 hour period into skim milk with 0.45% fat and cream with 45% fat, what
are the flow rates of the two output streams from a continuous centrifuge
which accomplishes this separation? Take Basis 1 hour's flow of whole milk
Solution:
Mass in
Total mass = 35000/6 = 5833 kg.
Fat = 5833 x 0.04 = 233 kg.
And so Water plus solids-not-fat = 5600 kg.
