Question

Two liquid streams are flowing at constant rates into a blender. One is benzene, which flows at a measured rate of 20.0 L/min, and the other is toluene. The blended mixture enters a storage tank (inner diameter = 5.5 m) equipped with a sight gauge. During an interval in which no liquid leaves the storage tank, the liquid level in the tank is observed to increase by 0.15 meters over a one-hour period. Calculate the flow rate of toluene into the blender (L/min) and the composition of the tank contents (wt% benzene).

Answer 1

Basis: one hour time

Volume of tank increased in one hour = pi x d ²/4*h

V= 3.142 x 5.5 x 5.5 /4 x 0.15 m³

V = 3.5642 m³

V=3564.2 L

Volume of Benzene enter in tank in one hour =20 L/min x 60 min/hr

= 1200 L in one hour

Volume of toluene enter into the reactor in one hour = volume of tank increased - volume of benzene entered

= 3564.2-1200

= 2364.2 L in one hour

Flow rate of toluene = 2364.5/60 L/min

= 39.4 L/min

Density of toluene = 867 kg/m3

Density of Benzene = 876 kg/m3

Weight of benzene in tank after one hour =1200x0.001x876 kg

Weight of benzene = 1051. 2 kg

Similarly weight of Toulene = 2364.2x0. 001x867

Weight of toluene = 2049. 76 kg

Weight fraction of benzene = 1051.2/(1051.2+2049.79)

=0.33899

Weight % of benzene = 33.899%