JNTU B.Tech II POWER SYSTEMS I Previous Question Paper (August/September - 2022 - R15)

The selection of a site for a thermal power station is critical for economic operation and efficiency. Key factors include:

• Proximity to Fuel Supply: To minimize transportation costs, the plant should be located near coal mines or have reliable rail/water transport links.
• Availability of Water: Large quantities of water are required for condenser cooling and steam generation; therefore, the site must be near a river or lake.
• Transportation Facilities: Adequate infrastructure is necessary for transporting heavy machinery during construction and fuel during operation.
• Cost and Type of Land: The land must be inexpensive, vast, and have high load-bearing capacity to support heavy equipment and foundations.
• Proximity to Load Centers: Locating the plant near the load center reduces transmission losses and costs.
• Ash Disposal Facilities: Large areas are required for the disposal of ash produced by burning coal; the site should have low-lying land nearby for this purpose.

These components are essential for the efficient conversion of thermal energy into steam power:

• Boiler: The boiler is a closed vessel where water is converted into steam by the heat generated from burning fuel. It functions as the primary heat exchanger where chemical energy in fuel is transferred to the working fluid (water).
• Economizer: The economizer is placed in the path of flue gases before they reach the chimney. Its function is to recover heat from the exhaust gases to preheat the feed water entering the boiler, thereby increasing the overall thermal efficiency of the plant and reducing fuel consumption.
• Superheater: The superheater consists of a group of tubes located in the boiler furnace. Its function is to remove any moisture from the saturated steam produced by the boiler and increase its temperature significantly above the saturation point. Superheated steam prevents condensation in the turbine blades and increases the plant's cycle efficiency.

Diagrammatically, the flue gases flow from the boiler through the superheater, then through the economizer, and finally exit through the chimney, ensuring maximum heat extraction from the combustion process.