The absolute pressure maintained in the...

The absolute pressure maintained in the shell of the salt water feed heater on most flash evaporators used on steam propelled vessels is __________.

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🔍 Key Concepts

• Flash evaporator flow path – where does the salt water feed heater sit in relation to the flash chambers and vacuum stages? • Pressure levels in the plant – which components normally run under vacuum, and which run at positive (above-atmospheric) pressure? • Steam source for the feed heater – is the heater usually supplied by live steam or by low‑pressure extraction/auxiliary exhaust?

💭 Think About

• First, decide whether the salt water feed heater is a piece of equipment that normally operates under vacuum or at a positive pressure. Which of the answer choices match that? • Think about what supplies heat to the salt water feed heater on most steam‑driven flash evaporators: is it live steam from the reducing valve, or lower‑pressure extraction/auxiliary exhaust steam? How does that affect the shell pressure? • Compare the typical vacuum levels in the flash stages with the likely shell pressure of a heater being supplied with steam. Would a steam‑heated shell usually be at a pressure higher or lower than the vacuum in a flash chamber?

✅ Before You Answer

• Eliminate any options that would require the salt water feed heater shell to be at a deeper vacuum than the flash stages, if that conflicts with the usual design of flash plants. • Confirm whether the feed heater shell is normally connected to low‑pressure extraction/auxiliary exhaust steam or to live steam through a reducing valve in common marine installations. • Check which option describes a pressure relationship that allows heat to flow efficiently from the steam side to the seawater side without turning the heater itself into another flash (vacuum) chamber.

🔍 Key Concepts

💭 Think About

✅ Before You Answer