🔍 Key Concepts

• submerged tube evaporator operation and flow pattern • what happens inside an effect when the shell vacuum becomes unstable • difference between priming, scaling, and air leaks in distilling plant equipment

💭 Think About

• Think about what rapid changes in shell vacuum would do to the boiling conditions of the feedwater in that effect. • Which of the options describes a problem that would be an immediate, dynamic reaction to fluctuating pressure, rather than a slow, long‑term condition? • Consider which problem would most directly affect the separation between liquid and vapor inside that effect.

✅ Before You Answer

• Verify which listed problem is typically associated with sudden pressure/vacuum changes in an evaporator shell. • Check which options usually result from long-term operation (gradual processes) versus instant changes (rapid processes). • Confirm which choice specifically relates to conditions inside that particular effect, not the whole system.