Explanation: The concentration of the feed increases as we move to subsequent effects in the evaporator setup. We know that due to the colligative properties of water, the boiling point increases with increasing concentration.

Explanation: The concentration of the feed decreases as we move to subsequent effects in the evaporator setup because the feed supply is opposite to that of forward flow, hence the lowest concentration is in the last effect and highest in the first one. We know that due to the colligative properties of water, the boiling point increases with increasing concentration.

Explanation: The concentration of the feed as we move to subsequent effects in the evaporator setup cannot be sequentially represented because the feed supply is mixed/ haphazard as compared to that of forward/backward flow. We know that due to the colligative properties of water, the boiling point increases with increasing concentration and hence we can follow the feed to determine the trend of concentration.

Explanation: The parallel feed operation has independent feed supplies to each effect which has no connection to the prior evaporators, and hence it has no such trends.

Explanation: The most economic and fruitful way to evaporate water after its concentration increases (BP also hiked) is to lower the pressure as lowering the pressure decreases its boiling point and hence the solution can now boil by the steam from the previous effect.

Explanation: Yes, the statement is correct. Forward feed evaporator in order to evaporate water after its concentration increases is to lower the pressure as lowering the pressure decreases its boiling point and hence the solution can now boil by the steam from the previous effect. This in a way creates pressure difference in the effects which pull the feed from former effects to the subsequent effects without requiring pumps.

Explanation: The backward feed does have more running cost than others because it pumps backwards from low pressure to high pressure and makes sure that the highest concentration product receives the maximum heat (directly from steam) which increases the evaporate yield considerably but at a cost.

Explanation: This operation is not possible as in such cases the vapour released in the 1st effect will not be able to effectively heat the solution in subsequent effect.

Explanation: The concentration should increase only then the evaporation would be effective for the setup, else if we have same concentration for all the feed, we should opt for forward feed.

Explanation: Forward feed evaporator in order to evaporate water after its concentration increases is to lower the pressure as it decreases its boiling point and hence the solution can now boil by the steam obtained from the previous effect. This in a way creates pressure difference in the effects which pull the feed from former effects to the subsequent effects without requiring pumps.

Explanation: The backward feed has more running cost than others as it pumps backwards from low pressure to high pressure making sure that the highest concentration product receives the maximum heat (directly from steam) which increases the evaporate yield considerably but at the cost of electrical pumps.

Explanation: The Duhrings’ rule is a rule that measures BPE of a solution. The boiling point of a solution is a linear function of the boiling point of the pure water at the same pressure.