TANKBLD - Liquid Stream Blending

Two aqueous streams containing salt at differing concentrations flow continuously into a well-mixed tank and a mixed-product stream is removed. In this case, the densities of the streams are not assumed constant but vary as a function of concentration. All three streams can have time varying flow rates, and hence the concentration and volume of liquid in the tank will also vary with time. 

The density of salt solution varies linearly with concentration, according to 

The above system is treated in detail by Russell and Denn (1972), and an analytical solution is obtained. 

LIQUID BLENDING PROBLEM OF RUSSELL AND DENN Liquid densities depend on concentration 

RH03=RH0+B C3 Initial mass of liquid VRHO3=V0 RHO3 Initial mass of salt VC3=V0 C30 

5 Simulation Tools and Examples of Chemical Engineering Processes 

The tank is filled with streams 1 and 2, and when the tank is approximately full, the outlet volumetric flow rate is set to the approximate steady state value, as would be controlled by a pump. This leads to some further volume change as the final product density is reached. 

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