Steam-jet devices — A steam ejector (steam-jet ejector) is primarily used to:

Introduction:
Steam-jet ejectors use high-velocity motive steam to entrain and compress a secondary fluid (often air, vapors, or non-condensables) to a higher pressure. They are extensively used to create and maintain vacuum in process equipment such as evaporators, condensers, and vacuum pans.

Given Data / Assumptions:

• Motive fluid: steam expanded through a nozzle to high velocity.
• Suction fluid: gases/vapors to be removed from a vessel.
• Diffuser section reconverts kinetic energy to pressure.

Concept / Approach:
The ejector entrains low-pressure gases and discharges them at an intermediate or condenser pressure, thus reducing pressure in the connected equipment. It does not superheat steam, nor is it intended for condensate removal (steam traps do that). The physics is based on momentum transfer and mixing.

Step-by-Step Solution:
Identify device function: entrainment and compression of secondary fluid.Connect function to application: producing vacuum in process vessels.Select the option explicitly stating “create vacuum”.

Verification / Alternative check:
Plant PFDs show steam-jet ejectors on vacuum services with barometric or surface condensers handling ejector discharge.

Why Other Options Are Wrong:

• Condensate removal is handled by traps and drainage systems.
• Superheating requires heat addition, not momentum-based entrainment.
• Throttling valves reduce pressure but do not create vacuum by gas removal.

Common Pitfalls:
Confusing ejectors with eductors or steam traps; assuming any steam accessory superheats or drains lines.

Final Answer:
Create vacuum (produce and maintain low pressure by entrainment)