Question

It is found that when acetone/water mixture at the top of the tower is introduced from a spray distributor rather than three ports acetone recovery is higher. Provide a brief explanation as to why this happens.

Answer 1

Using spray distributor increases the breaking of the mixture into very small bubbles. As the number of bubbles is increased by the spray column, the interfacial area of contact between the gas and liquid mixture also increases. This is opposite to that of the three ports where not many bubbles are formed and hence, low interfacial area of contact between the gas and liquid.

Rate of mass transfer = Ky*a*(Driving force) where a is interfacial area of contact.

As a increases in spray distributor, rate of mass of acetone transfered increases, and hence, recovery also increases.