Thornycroft boiler

Thornycroft boiler

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Thornyeroft water tube marine steam boiler with one water drum
The Thornycroft marine steam boiler has an upper steam drum and a lower waterdrum connected together by banks of tubes. The tubes are very curved and all of them discharge into the steamdrum above the water level. In later models some of the tubes discharge below the water level. A down comer between the steam drum and the water drum is located behind the boiler.
The flue gas pass through the banks of tubes and violent circulation arise in the tubes and the evaporated steam conveys water to the steam drum. The heavy water circulation keeps the tubes free from deposits.

These boilers have an upward narrowing shape and call for, especially if they are placed side by side, a larger space than other square-shaped boilers.

Thornyeroft water tube marine steam boiler with two water drums
Thornycroft marine boiler has two lower drums. Huge downcomers are installed between the steam drum and the water drums.

Thornyeroft water tube steam boiler
Thornycroft water tube boiler with two water drums. Notice that the fire in the furnace doesn't heats the downcomers.