Thermal Engineering Questions and Answers – Jet Condensers

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This set of Thermal Engineering Multiple Choice Questions & Answers (MCQs) focuses on “Jet Condensers”.

1. Which of the following is NOT a type of jet condenser?
a) Parallel flow type
b) counter flow type
c) Ejector type
d) Central flow type
View Answer

Answer: d
Explanation: Jet condensers are classified into parallel flow type, counter flow type and ejector flow type condensers. Central flow type condensers are not jet condensers but surface condensers. In jet condensers the exhaust steam comes in direct contact with the cooling water.
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2. Parallel flow type condensers are further classified into _____
a) high speed type and low speed type condensers
b) high steam type and low steam type condensers
c) high level type and low level type condensers
d) high capacity and low capacity type condensers
View Answer

Answer: c
Explanation: Parallel flow type condensers are a type of jet condensers. Further parallel flow condensers are classified into high level type and low level type. In this type of steam condenser, water and exhaust steam both enter the condenser from the top.

3. Which of the following statement regarding parallel flow type jet condensers is FALSE?
a) They are classified into Low level type and high level type
b) Condensate is collected at the bottom
c) Exhaust steam and cooling water enter the condenser from top
d) Exhaust steam and cooling water enter from opposite directions
View Answer

Answer: d
Explanation: Exhaust steam and cooling water enter from opposite directions in case of counter-flow type steam condensers and not parallel-flow type. In parallel flow type jet condensers, cooling water and exhaust steam enter from the top and the condensate is collected at the bottom.
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4. Counter-flow type jet condensers are classified into – Low-level type and High level type jet condensers.
a) True
b) False
View Answer

Answer: a
Explanation: The given statement is correct. Jet condensers are classified into parallel flow type and counter flow type jet condensers. Both these categories are further sub-divided into low level type and high level type jet condensers.

5. What is the function of baffle plate in parallel flow type low level jet condenser?
a) It keeps cooling water and exhaust steam from mixing
b) It ensures proper mixing of cooling water and exhaust steam
c) It collects condensate over it for extraction
d) It helps condenser wall withstand the inside pressure
View Answer

Answer: b
Explanation: In low level parallel flow type jet condensers, the steam enters from the top of the condenser. The cooling water is sprayed over the steam. A baffle plate is provided to ensure proper mixing of the cooling water and steam.
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6. Where is condensate extraction pump provided in case of low level parallel flow type jet condenser?
a) At the bottom of the condenser
b) At the top of the condenser
c) Near the baffle plate
d) Near the steam entry point
View Answer

Answer: a
Explanation: In a low level parallel flow type jet condenser, the steam comes in direct contact with the cooling water. The proper mixing is ensured using a baffle plate. The condensate is collected at the bottom of the condenser. The condensate extraction pump is hence located at the bottom of the condenser.

7. Which of the following statements regarding low level counter flow type jet condensers is FALSE?
a) Cooling water is broken into jets by perforated trays
b) Condensate is collected at the bottom
c) Steam is discharged near the bottom and moves upwards
d) The air suction pump is placed near the bottom of the condenser
View Answer

Answer: d
Explanation: In low level counter flow type jet condensers, the air suction pump is placed at the top of the condenser. Steam is discharged near the bottom and it moves upwards. Cooling water is discharged from the top, it is broken into water jets by perforated trays.
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8. Which of the following condensers is also called barometric condenser?
a) Low level parallel flow type jet condenser
b) Low level counter flow type jet condenser
c) High level counter flow type jet condenser
d) High level parallel flow type jet condenser
View Answer

Answer: c
Explanation: A high level counter flow type jet condenser is also called as barometric condenser. The shell of this condenser is placed at an approximate height of 10.363 m above hot well. The need of an extraction pump is thus obviated.

9. Which of the following condensers does not require a condensate extraction pump?
a) Low level parallel flow type jet condenser
b) Low level counter flow type jet condenser
c) High level counter flow type jet condenser
d) Central flow type surface condenser
View Answer

Answer: c
Explanation: High level counter flow type jet condensers also called as barometric condensers, they don’t need a condensate extraction pump as their shells are placed at a height of about 10.363 m above hot well.
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10. High level counter flow type jet condenser requires an injection pump to pump cooling water inside the condenser shell (when water under pressure isn’t available).
a) True
b) False
View Answer

Answer: a
Explanation: High level counter flow type jet condenser requires high pressure injection of water in the condenser shell. When water under required pressure isn’t available, an injection pump is used to pump the cooling water.

11. Which of the following statements regarding ejector condenser is FALSE?
a) It is a type of jet condenser
b) Exhaust steam passes through a non-return valve
c) Kinetic energy of cold water decreases as it passes through the truncated cones
d) Pressure of cold water drops as the water progresses through the truncated cones
View Answer

Answer: c
Explanation: In an ejector condenser, cold water passes through a number of truncated cones and as it passes its kinetic energy increases and pressure drops. Due to this pressure drop, exhaust steam is drawn along with the cold water. The exhaust steam passes through a non-return valve to ensure that the steam doesn’t flow back. The exhaust steam and the cold water mix and finally pass through a diverging cone, where a part of its kinetic energy is converted into pressure energy, the mixture is then discharged into hot well.

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Manish Bhojasia, a technology veteran with 20+ years @ Cisco & Wipro, is Founder and CTO at Sanfoundry. He is Linux Kernel Developer & SAN Architect and is passionate about competency developments in these areas. He lives in Bangalore and delivers focused training sessions to IT professionals in Linux Kernel, Linux Debugging, Linux Device Drivers, Linux Networking, Linux Storage, Advanced C Programming, SAN Storage Technologies, SCSI Internals & Storage Protocols such as iSCSI & Fiber Channel. Stay connected with him @ LinkedIn | Youtube | Instagram | Facebook | Twitter