Artificial Draught — How It Is Produced Artificial (mechanical) draught in boiler practice is produced by which of the following?

Introduction / Context:
When natural chimney action is insufficient to move the required air and flue gases, artificial draught is created mechanically. This permits finer control of furnace pressure and air-to-fuel ratio across load ranges.

Given Data / Assumptions:

• Boiler requires adjustable draught independent of weather/stack height.
• Recognized mechanical methods: steam jet and fans.

Concept / Approach:
Artificial draught can be produced by a steam jet (jet pump or ejector principle) that entrains flue gases, or by mechanical fans (centrifugal fans or blowers) that push or pull the gases. A chimney alone provides natural draught by buoyancy and is not “artificial.”

Step-by-Step Solution:
Identify steam jet: uses motive steam momentum to create suction.Identify centrifugal fan: imparts mechanical energy to the gas stream.Conclude: both devices produce artificial draught.

Verification / Alternative check:
Balanced-draught systems often combine forced (fan) and induced (fan or ejector) arrangements for optimal furnace pressure.

Why Other Options Are Wrong:
chimney: natural draught device; not artificial.

Common Pitfalls:
Assuming only fans qualify; ejectors are common where steam is readily available.

Final Answer:
both (a) and (b)