It is fire tube, multitubular, internal fired, and vertical boiler. Its maximum steam generation capacity is 3,500 kg/h. Its shell diameter and height are 2.75 m and 5.8 m, respectively. The fuel (coal) is fired on the grate in the furnace. The hot flue gas passes through the fire tube located in the water space and heat is transferred to water. Water becomes hot in contact with the tube surface. Flue gas goes to the smoke box and finally into the atmosphere through chimney. The circulation of water is natural; hot water rises up and cold water comes down as shown in Figure 4.10. Steam formed is collected at the upper space of the dome-shaped shell and supplied for use through steam stop valve.
Figure 4.10 Cochran Boiler
The flames and hot gases produced as a result of combustion of coal on the grate rise in dome-shaped combustion furnace. The unburnt fuel is reflected back to the grate and hot flue gas passes through the fire tubes and dissipates the heat to the water. Finally, the flue gas escapes into the atmosphere through smoke box and chimney. Water circulation is natural circulation. Hot water rises up and cold water comes down continuously. Steam is collected at the upper space of the boiler.
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