Boiler Type Identification — Fire-Tube Example Which one of the following is a fire-tube boiler (hot gases through tubes, water around tubes)?

Introduction / Context:
Boilers are classified by the relative path of water and hot gases. In fire-tube designs, flue gases pass through tubes immersed in water, whereas in water-tube designs, water flows inside tubes heated externally. Recognising these archetypes is foundational for design selection and safety analysis.

Given Data / Assumptions:

• Lancashire, Babcock and Wilcox, and Yarrow are standard textbook examples.
• No hybrid or special-case configurations assumed.

Concept / Approach:
The Lancashire boiler is a classic horizontal, internally fired, fire-tube boiler with two large furnace tubes. The Babcock and Wilcox and the Yarrow are water-tube boilers with water inside inclined or straight tubes and hot gases outside. Therefore, among the listed items, Lancashire is the correct fire-tube example.

Step-by-Step Solution:
Identify gas–water paths for each named boiler.Lancashire → fire-tube; Babcock & Wilcox and Yarrow → water-tube.Select Lancashire as the fire-tube boiler.

Verification / Alternative check:
Historical and modern references consistently classify these designs accordingly.

Why Other Options Are Wrong:
Babcock and Wilcox: water-tube arrangement.Yarrow: water-tube, three-drum naval pattern.none of these: incorrect because Lancashire qualifies as fire-tube.

Common Pitfalls:
Letting shell shape or orientation mislead classification; the path of water relative to hot gases is the key.

Final Answer:
Lancashire boiler