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A distillation column is fed with a stream of ethanol, propanol and butanol
flowing at a total rate of 1350 kg h−1 and containing 20 wt% ethanol. The top product consists of 80% of the ethanol and 50% of the propanol contained in the feed. All of the 500 kg h−1 of butanol in the feed ends up in the bottom product. Calculate the bottom product component mass flow rates.
A stream of aqueous sulphuric acid of 62.4 wt% H2SO4 is mixed with pure water in a stirred vessel to produce a stream of 20.5 wt% acid. What ratio of water to concentrated acid should be used?
Write in words the Conservation Equation and State what is meant by an Open System and a Closed System
water 1 mm thick where the concentrations are 20 weight % and 8 weight %
respectively on either side of the film. The diffusivity of sodium chloride in water is
1.35 X 10-9 m
2
/s. Densities of 20 % and 8 % NaCl solutions are 1145.3 kg/m3
and 1054
kg/m3
respectively.
content reduced to 1 % of this value by counter current absorption in a packed
tower. Gas flow rate is 1 kg/m2
.sec of air. Water rate is 1.6 kg/m2
. sec. For this
system Henry’s law holds good and Y = 1.75 X/ (1-0.75X). What is the height of the
tower required if height of overall transfer unit HtoG= 50cm.
Ammonia is removed from a 15% ammonia- air mixture by scrubbing with water in
a packed tower, so that 99.5% of ammonia removed. Entering gas and water rates
are 1.5 and 0.95 kg/m2
.sec. respectively. KG.a = 0.0008 K.mol/m3
.sec.KN/m2
.X : 0.021 0.031 0.042 0.053 0.079 0.106 0.159
Y : 0.016 0.0245 0.0339 0.0435 0.0704 0.101 0.176
Q = 20,000 m3 /day, Qw = 100 m3 /day, QR = 30,000 m3 /day, S0 = 500 mg COD/L, S = 25 mg, COD/L V = 5000 m3, XR = 4.5 g/L
Assumes that there is no solid concentration the effluent flow from the top of the settling tank. the engineer change the design by assuming a solid loss with the clarified effluent of 5 mg/L by maintaining the same SRT, S, Qw, concentration in the aeration tank (X) and the reactor volume (V). He change the (QR) which changes the (XR). Performing mass balance of the biomass for both overall process and on settling tank, determine the XRnew, X, SRT and the value of QRnew that have to be used under the hypothesis of solid losses with the effluent
An activated sludge process has been designed to treat wastewater of a new township community. The results of the design calculations below:
Q = 20,000 m3 /day
Qw = 100 m3 /day
QR = 30,000 m3 /day
S0 = 500 mg COD/L
S = 25 mg
COD/L V = 5000 m3
XR = 4.5 g/L
and 300 K with a spring attached to the wall and piston as shown in the figure below. Initially,
the spring is stretched up to 1 cm. The gas is heated so that the piston moves by 3 cm and the
final temperature becomes 310 K. The diameter of piston is 10 cm. Find the heat added to
the gas. The surrounding pressure is 1 atm.
Air is compressed from 1 bar , 300 K to 5 bar in a steady flow compressor at the rate of 1200
kg/h. The inlet and outlet pipe diameters are 10 cm each. The rating of compressor is 100
hp. For air, Cp=3.5R, Cv = 2.5R. Assuming ideal gas, estimate the heat transfer rate.
