1 Fire Tube Boilers
Lancashire Boiler
It is a stationary, fire tube, horizontal straight tube, internally fired, natural circulation boiler. Its normal working pressure range is up to 15 atmospheres and evaporative capacity up to approximately 8000 kg/h. The size varies from 7−9 m in length and 2−3 m in diameter.
The three sectional views of the Lancashire boiler are shown in Fig. 3.1. The gaseous products of combustion formed as a result of burning of fuel on the grate move along the furnace tube or main flue. They are deflected up by the brick wall bridge. After reaching the back of the main flue, they deflect downwards and travel through the bottom flue. The bottom flues are situated below the water shell. These flue gases heat the lower portion of the shell. After travelling from the back to the front, these gases bifurcate into two separate paths in the side flues. They travel from the front to the back again in the main flue from where they discharge to the chimney and atmosphere. The flues are built of ordinary brick-work and lined with refractory material or bricks.
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