- Stirling Boiler Definition: A Stirling Boiler is defined as a type of bent tube boiler used for generating large amounts of steam in power plants.
- Structure: It has three steam drums on top and two mud drums at the bottom, connected by bent steel tubes.
- Heat Management: A brick enclosure and fire brick arch manage heat effectively by preventing dissipation and guiding combustion gases.
- Circulation System: Water and steam circulate through specific tubes connecting the mud and steam drums, ensuring efficiency.
- Safety and Applications: It features a safety valve on the back steam drum and is used in central power stations due to its high capacity.
A Stirling Boiler is a late-nineteenth-century bent-tube water-tube boiler. New thermal power generating plants use other water-tube layouts. Alan Stirling designed his first unit in 1883 and formed the Stirling Boiler Company in 1888. Indian notes often quote about 50,000 kg of steam per hour and about 60 kgf/cm². Those figures describe the class, not one current rating. Surviving units are mostly older industrial or heritage plant.
The five-drum Stirling Boiler taught in many notes has three steam drums at the top and two mud drums at the bottom. Earlier Stirling layouts used three or four drums. Bent steel tubes join the drums so thermal expansion does not pry the tube seats. The drums and tubes are steel and hang from a supporting frame.
The setting is a brick enclosure. The brickwork holds the furnace gases around the tube banks rather than letting them spill into the boiler house. A fire door sits low in the front wall. A damper on the gas-outlet side sets how much combustion gas leaves toward the flue.
A firebrick arch sits above the grate. Baffles, often three in the five-drum setting, send the gas across the tube banks in a zigzag path. Water tubes join the mud drums. Steam equalising tubes join the middle steam drum to the outer steam drums. Hot-water tubes also run from the front steam drum to the middle steam drum.
A safety valve is fitted on the rear steam drum. Saturated steam is taken from a compartment on the middle steam drum. A steel pipe then leads that steam to the superheater when one is fitted.
