Solve this multiple-choice question and choose the correct option.

Concept In natural-circulation boilers, heating in the riser tubes reduces water density, producing convection currents between risers and downcomers that circulate water without any pump. Why others are incorrect No pump or draft fan circulates water in a natural system. Injectors are for feeding water into the boiler, not for internal circulation. Final AnswerCirculation is by convection currents due to density differences.

Curioustab

Natural circulation in steam boilers: driving mechanism State how water circulation is produced in natural-circulation boilers during operation. Choose the correct statement.

Mechanical Engineering Steam Boilers and Engines Difficulty: Easy

Choose an option

A

By a forced draft fan pushing water through tubes
B

By a circulation pump in the downcomer
C

By convection currents established by density differences when water is heated
D

By the injector using steam jet action

Answer

Correct Answer: By convection currents established by density differences when water is heated

Explanation

Concept

In natural-circulation boilers, heating in the riser tubes reduces water density, producing convection currents between risers and downcomers that circulate water without any pump.

Why others are incorrect

No pump or draft fan circulates water in a natural system.
Injectors are for feeding water into the boiler, not for internal circulation.

Final AnswerCirculation is by convection currents due to density differences.