Pick the correct example of a fire-tube boiler.

Explanation:Fire Tube boiler:In this boiler, the hot flue gases are present inside the tubes and water surrounds them and sometimes around the outside of the tubes.Hence we can say that they are internally as well as EXTERNALLY fired boilers.They are low-pressure boilers. The operating pressure is about 25 bar.Externally fired fire tube boilers are locomotive type boilers, horizontal return tubular (HRT) boiler, ETC.Internally fired fire tube boilers are Scotch-marine boilers, Cochran boiler, package boilers, etc. Water Tube Boiler:In this boiler, the water is present inside the tubes and the hot flue gases surround them.They are high-pressure boilers and the operating pressure is about 250 bar.Water-tube boilers are ALWAYS externally fired.Stirling Boiler, La-Mont Boiler, Benson Boiler, Yarrow Boiler, Babcock and Wilcox Boilers are water tube boilers