Cochran boiler

A vertical boiler with horizontal fire-tubes is a type of small vertical boiler, used to generate steam for small machinery. It is characterised by having many narrow fire-tubes, running horizontally.

Boilers like this have been widely used on ships as either auxiliary or donkey boilers. Smaller examples, particularly the Robertson type have been used for steam wagons.

Parallel tube boilers place all of their fire-tubes in a single parallel group, running from side to side of the boiler shell. The best known of these is the Cochran design.

The Cochran boiler was produced by Cochran & Co. of Annan, Scotland. It is widely used in marine practice, either fired directly by coal or oil fuels, or else used for heat recovery from the exhaust of large diesel engines. Where such a boiler may be heated either by the exhaust gases of the main propulsion plant, or else separately fired when in port (usually by oil rather than coal) it is referred to as a composite boiler.

The boiler is a cylindrical vertical water drum with a hemispherical domed top. This domed shape is strong enough not to require staying. The firebox is another hemispherical dome, riveted to the base foundation ring to give a narrow waterspace.

The fire-tubes are arranged in a single horizontal group above this, mounted between two flat vertical plates that are inset into the boiler barrel. The first of these plates forms a shallow combustion chamber and is connected to the firebox by a short diagonal neck. The combustion chamber is of the "dry back" form and is closed by a steel and firebrick plate, rather than a water jacket. The exhaust from the fire-tubes is into an external smokebox and a vertical flue. For maintenance access to the tubes, a manhole is provided in the hemispherical dome.

...
Wikipedia