Construction The boiler consists of a cylindrical shell, hemispherical fire box, fire tubes and chimney. The top of the shell having hemispherical shaped crown as shown in fig. The hemispherical crown of boiler gives good strength to withstand pressure of steam inside the boiler. The hemispherical shape of furnace can withstand high heat and it is also useful to increase radiant heat transfer. The grate is placed at the bottom of furnace and ash pit is located below the grate. The furnace and the combustion chamber are connected by short flue pipe. The wall of the combustion chamber is lined with the fire bricks. Working The water is supplied to the boiler through feed check valve. The level is adjusted with the help of water level indicator. Coal is added through the fire-hole or door to the grate and burnt. The hot gases produced are collected in the fir box. These hot gases enter into horizontal fire tubes and heat transfer takes place from flue gases passing inside the tubes to water surrounded the tubes. The flue gas coming from the fire tubes enter into smoke box and finally they discharged to atmosphere through a chimney. The ash formed is collected in ash pit. The steam is collected through anti priming pipe on the top of the shell.
