Question

Tomato juice containing 7% solids by mass is fed to an evaporator and water is removed at a rate of 500 kg/h. If the concentration is to contain 35% solids, then determine the necessary feed rate.

Answer 1

Feed rate F = 625 kg/h

Step-by-step explanation:

Given that:

percentage mass of the solids = 7% = 0.07

rate of removal of water W = 500 kg/h

Concetration C = 35% = 0.35

To fine the feed rate = ???

Using the Overall balance equation,

Suppose: F = W + C

F = 500 + C ---- (1)

Then, the Solids balance can be computed as:

(0.07)F = (0)500 + (0.35)C

0.07F = 0.35C

C = 0.07F/0.35

C = 0.2F

Now

F = 500 + 0.2F

Collect like terms

F – 0.2F = 500

0.8F = 500

F = 500/0.8

F = 625 kg/h

Therefore, the feed rate F = 625 kg/h