The benchmark pressure above which a boiler is considered to be a high-pressure boiler is 80 bar.

High-Pressure Boiler

• A boiler is called a high-pressure boiler when it operates with a steam pressure above 80 bar.
• High-pressure boilers are widely used for power generation in thermal power plants.
• If the feed-water pressure increases, the saturation temperature of water rises, and the latent heat of vaporization decrease.
• The feed water can be heated to saturation temperature in the economizer with the help of waste heat recovery from the exhaust gases escaping to the chimney.
• Then the boiler supplies only latent heat of vaporization and superheat.
• Thus, a boiler operating at high pressure will require less heat addition for steam generation.

Features of High-Pressure Boilers

1. Forced circulation of water.
2. The large number of small-diameter tubes.
3. Higher steam pressure and temperature.
4. Improved mode of heat transfer.
5. An improved method of heating.
6. Pressurized combustion.
7. Compactness.
8. High efficiency.
9. Intensive heating.
10. Once through construction