Question

_______ are simple heat exchangers for imparting additional energy to steam for given pressure.
1. Superheaters
2. Economizers
3. Draught systems
4. None of the above

Answer 1

Correct Answer - Option 1 : Superheaters

Superheater:

• A superheater is a device used to convert saturated steam or wet steam into superheated steam or dry steam
• It is a simple heat exchanger for imparting additional energy to steam for given pressure.
• Superheated steam is used in steam turbines for electricity generation, steam engines, and in processes such as steam reforming
• While the temperature of the steam in the superheater rises, the pressure remains the same as that of the boiler

Air preheater:

• Air preheaters are used in large boilers found in thermal power stations producing electric power.
• An air preheater or air heater is a general term to describe any device designed to heat air before another process (for example, combustion in a boiler) with the primary objective of increasing the thermal efficiency of the process.
• The purpose of the air preheater is to recover the heat from the boiler flue gas which increases the thermal efficiency of the boiler by reducing the useful heat lost in the flue gas.

Economiser:

• An economiser is a mechanical device that is used as a heat exchanger by preheating a fluid to reduce energy consumption.
• In a steam boiler, it is a heat exchanger device that heats up fluids or recovers residual heat from the combustion product i.e. flue gases in a thermal power plant before being released through the chimney.
• Economiser is situated before air pre-heater in the flue gas path. 
• Economiser increases the efficiency of the power plant.