Basic Mechanical Engineering (3110006)

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.