Q1: In a backward feed multiple effect evaporator

ANS:B - feed flows from low pressure to high pressure.

The correct statement should be: "Feed flows from low pressure to high pressure." In a backward feed multiple effect evaporator, the feed typically flows from a lower pressure in the first effect to a higher pressure in the last effect. This flow direction is contrary to what might be intuitively expected, as it goes against the natural tendency of fluids to flow from high pressure to low pressure. The reason for this configuration is to take advantage of the increasing boiling point of the solution as pressure increases. By feeding the solution into the first effect at a lower pressure and allowing it to flow through each subsequent effect to a higher pressure, the boiling point of the solution also increases incrementally. This allows for the use of lower temperature heating mediums in each effect, reducing energy consumption and operational costs. Additionally, feeding the solution at a lower pressure helps prevent precipitation or fouling of the solution in the earlier effects, as the lower pressure reduces the risk of reaching supersaturation conditions too quickly. Therefore, in a backward feed multiple effect evaporator, the flow of the feed from low pressure to high pressure is a deliberate design choice aimed at optimizing energy efficiency and preventing operational issues.