What is a boiler?
Since the time James Watt invented the steam machine, people have come to realize the importance of steam in generating energy. It is on the principle of converting thermal energy generated by steam into mechanical rotational energy of the turbine to generate electricity that a thermal power plant works on. There is a significant amount of steam that needs to be produced in order to make a thermal power plant efficient. It is for this purpose that thermal power plant boilers are used. They use the heat generated by various fuels. Depending on the fuel used to make a steam generator or thermal power plant boilers function, thermal plants are classified into fossil fuel plants, nuclear power plants, solar thermal plants, geothermal power plants etc.
Types of boilers used in a power plant
As technology developed, the types of boilers used also changed. There are broadly three types of boilers that have been used in a thermal power plant:
• Three pass boiler- This was one of the earliest types of thermal power plan boilers. There were two designs that were created- one was rounded called the haycock boiler and the other was larger and more rectangular in shape and was called the wagon top boiler. These boilers were crude and used a lot of steam as the energy generated was because of the vacuum that was created when the steam was condensed. These boilers were heated from underneath with coal and were placed in a brick structure to retain the generated heat. The gases that were heated in the boiler passed through a flue or a duct and then went to the sides of the boiler to create the necessary heat.
• Fire tube boiler- This was an improved type of boiler that used less amount of steam to create energy. Instead of using the vacuum created when steam condensed, these thermal power boilers used the power of steam itself to move pistons to create movement. These were cylindrical boilers that had a fire tube in the centre. At one end of the fire tube was a combustions system called the fire grate where the fuel was placed to be heated. These boilers were no doubt more efficient than the three pass boilers. A modification was the Lancashire boiler which used two separate furnaces. This allowed the user to clean one furnace while the other functioned.
• Boilers with multiple tubes- this type of thermal power plant boiler was a breakthrough not only for the locomotive industry but for the industry of energy generation as well. These boilers only used two passes and the second one incorporated many tubes that increased the efficiency and the power of the steam generator.
All though all of the above boilers were primarily developed to generate power for locomotives, their application in power plants began soon. These boilers are only a part of the cycle that creates energy. However, this apparatus is the base of a thermal power plant and is extremely essential.