Q1: Which of the following absorbs maximum heat in a high pressure boiler ?

ANS:D - Furnace water wall

The Furnace water wall absorbs maximum heat in a high-pressure boiler. Explanation:

1. Steam Superheater: The steam superheater is a heat exchanger located in the boiler's flue gas path after the primary combustion chamber. Its primary function is to increase the temperature of saturated steam produced by the boiler to its superheated state. Superheated steam has higher energy content and is used in various industrial processes, such as turbine operation in power plants or heating applications requiring high-temperature steam.
2. Heat Absorption: The steam superheater absorbs maximum heat in a high-pressure boiler because it is directly exposed to the hot flue gases generated during combustion. These gases contain a significant amount of thermal energy resulting from the combustion of fuel, which is transferred to the superheater tubes. As the saturated steam passes through the superheater tubes, it absorbs heat from the hot gases, causing its temperature to rise to the desired superheat level.
3. Other Components:
   • Economiser: The economiser is another heat exchanger in the boiler system, typically located in the flue gas path before the air preheater. Its primary function is to preheat the boiler feedwater using residual heat from the flue gases before it enters the boiler. While the economiser does absorb heat, its main purpose is to improve boiler efficiency by recovering heat that would otherwise be lost to the environment.
   • Air Preheater: The air preheater is also a heat exchanger located in the boiler's flue gas path, typically before the economiser. Its purpose is to preheat the combustion air using heat from the flue gases before it enters the furnace. Preheating the combustion air helps improve combustion efficiency and reduce fuel consumption but does not absorb as much heat as the steam superheater.
   • Furnace Water Wall: The furnace water wall is a structural component of the boiler that forms the walls of the combustion chamber. While it is exposed to high-temperature combustion gases, its primary function is to provide structural support and containment for the combustion process. The water circulating through the furnace water wall absorbs heat to generate steam but does not directly absorb as much heat as the steam superheater.