The Cochran boiler, shown in Fig. 3.4, is a multi-tubular, internal furnace vertical fire tube boiler having several horizontal fire tubes. Its normal size is about 2.75 m shell diameter and 6 m height of the shell. The steaming capacity is about 3500 kg/h.
The flame and hot gases produced as a result of burning fuel on the grate, rise in the combustion furnace which is dome shaped. The unburnt fuel, if any, will be deflected. The gases are also deflected back and pass through the flue to the fire tubes from where they pass out to smoke box and hence to chimney.
The water circulation is shown by arrows. Water flows down by cooler wall of the shell and rise up past the fire tubes by natural circulation due to convection currents.
Figure 3.4 Cochran boiler
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