High-Pressure Boilers :
A boiler is said to be high-pressure boiler if it operates above 80 bars. These boilers are mostly used for the power generation in the thermal power plants. In all the high-pressure boilers, when the water pressure increases, the saturation temperature of water increases and latent heat of vaporization decreases. The feed water will be heated in the economizer using the waste heat. The boiler operation will require less heat at high-pressure only for steam generation. The world’s largest power plant is in Japan and has a steam capacity of 1600 Tons / hour. Trombay power plant in India has the capacity 550 Tons / hour steam generating capacity. Water tube boilers are generally preferred for high output and high pressure. On the other hand, fire tube boilers are used low pressure and low output.
Advantages of High-Pressure Boilers –
1. In a high-pressure boiler, each and every part is equally heated. So the risk of overheating is drastically reduced and thermal stress problem is rectified.
2. The efficiency obtained from the heat of combustion by the use of small diameter tube like large number of tubes and large number of circuits.
3. It eliminates the scale formation which is due to high velocity water passing through the tubes.
4. Pressurized combustion can be used for decreasing the rate of firing.
5. High pressure and high temperature can be used which will be inexpensive.
6. Less floor space is required for high-pressure boilers.
7. Forced circulation of water can be maintained with the help of the pipes.
8. With the use of high-pressure boilers, the mode of heat transfer will be improved.
9. The furnace with high-pressure boilers is so high and therefore 70 % of heat is transferred to water by the help of radiation. This is a much faster way of heat transfer.
10. High-pressure boilers always use forced circulation of water which will provide increased evaporative capacity and positive circulation of water.
11. The generation of steam is economical with the help of high-pressure boilers.
Disadvantages of High-Pressure Boilers –
1. The formation of bubbles at the inner face of the tube reduces the heat transfer rate.
2. When the flow of water is insufficient, tubes are responsible for the overheating.
3. The high-pressure boilers can function only when the operating function is a fluid.
These are the advantages and disadvantages of high-pressure boilers.