What happens when there is an accumulation of non-condensable gas in a boiler?

When non-condensable gases accumulate in a boiler, they can disrupt the normal flow of steam and lead to the blockage of steam pathways. Non-condensable gases such as air or other gases that do not liquefy at operating temperatures and pressures can form pockets within the boiler system. These pockets reduce the effective steam space, which impedes the steam generation process and can lead to reduced steam quality and efficiency.

The presence of these gases also affects the heat transfer processes inside the boiler. Since non-condensable gases act as an insulating layer, they limit the contact between the heating surfaces and the steam or water, thereby leading to less efficient heating. This can create areas of high temperature within the boiler and potentially lead to overheating in certain circumstances, but the immediate and primary effect is indeed the blockage of steam due to the accumulation of these gases.

Effective removal of non-condensable gases, typically achieved through proper venting and blowdown practices, is critical to ensuring smooth operation and maintaining boiler efficiency.