Question

A multiple effect evaporator has a capacity to process 4000 kg of solid caustic soda per day when it is concentrating from 10% to 35% solids. The water evaporated in kg per day is:

• A. 28571
• B. 24571
• C. 16000
• D. 48571

Hint:

In evaporators, the water evaporated is the difference in the amount of water before and after the concentration process.

Answer 1

The Correct Option is A

Step 1: Problem Definition.
The evaporator's capacity is 4000 kg of solid caustic soda daily. The concentration shifts from 10% to 35% solids. The water removed is the difference between the initial and final water quantities.

Step 2: Calculation.
The mass of solids remains constant. The water evaporated is calculated as the initial water mass minus the final water mass.\[\text{Water evaporated} = \text{Initial water} - \text{Final water} = 4000 \times \left( \frac{10}{90} \right) - 4000 \times \left( \frac{35}{65} \right)\]\[\text{Water evaporated} \approx 28571 \, \text{kg per day}.\]

Final Answer: \[\boxed{\text{A) 28571}}\]