What is the purpose of the distribution pipe that injects feedwater inside a boiler?

The purpose of the distribution pipe that injects feedwater inside a boiler is primarily to reduce thermal shock in the drum. When cold feedwater enters the boiler, it must be introduced in a manner that avoids creating abrupt temperature differences that could lead to rapid expansion or contraction of the boiler materials. Such thermal fluctuations can result in stress, potential cracking, or weakening of the drum.

By using a distribution pipe, the feedwater can be spread over a larger area or introduced at a controlled rate, allowing for a more gradual temperature adjustment throughout the boiler. This ensures that the structure maintains integrity and operates efficiently, as sudden changes in temperature can cause significant issues in the long-term operation of the boiler system.

The other options, while relevant to overall boiler function, do not directly relate to the role of the feedwater distribution pipe. For instance, increasing pressure in the drum is a function of the boiler design and the conditions under which it operates, rather than the distribution of feedwater. Similarly, while proper feedwater management does impact efficiency and combustion, it is primarily about maintaining temperature stability and avoiding thermal stress. Finally, distributing flue gases evenly pertains to the combustion process and exhaust management, rather than the feedwater injection.