This is simplest type of a fire tube boiler. A simple vertical boiler produces low Pressure and small quantity of steam. It occupies very less space so it is used where limited space is available. We discuss about simple vertical boiler working design and its Parts. Simple vertical boiler diagram is shown.
It consists of a cylindrical shell surround by vertical cylindrical box name called fire box. This is slightly tapered towards the top of shell to allow ready passage of the steam to the surface. At the bottom of the fire box, is a grate. The fire box is fitted with two or more inclined cross tubes. These tube are used to increase the heating surface of simple vertical boiler and also increase the water circulation. At the top of fire box there is stack (Produce Natural Draught). Hand holes are provided at the end of cross tubes to clean them. A man hole is also available at the top of shell for a man to enter in the boiler for cleaning or maintenance. A mud hole is provided at the bottom of the shell to remove the mud that settles down. The space between the boiler shell and fire box is filled with water to be heated. A tubular gauge glass is also provided to see water level inside the boiler. Pressure gauge, safety valve, air vent valve and steam supply valves are also installed there at the top of crown plate.
Simple vertical boiler working
The fuel is fed into the grate through the fire hole. when fuel is burnt ,the ashpit used to collect the ash from burning fuel which is located at the bottom of the grate. The boiler dia is normally 3 feet and 9 inch to 5 feet and its height is 9 feet .each cross tube has the dia of 9 inches. The boiler heating surface is 80 feet square and its grate area 8.4 feet square. The boiler pressure is 100 PSI. The combustion gas flows from the furnace and pass around the tubes. These gasses escape to the atmosphere through the chimney. Due to natural circulation hot water moves from the lower end to higher end. Supply of steam is then regulated through stop valve.
Also Read Package type Boiler