In watertube boilers, where do the heat and gases of combustion pass?

In watertube boilers, the heat and gases of combustion pass around the tubes containing water rather than through them. This design allows water to be heated in the tubes, which are surrounded by the combustion gases that provide the heat necessary for the water to turn into steam.

This method is efficient because it maximizes the surface area of the tubes that comes into contact with the hot gases, thus improving heat transfer. The construction also facilitates the quick response to demand changes, as water can be heated more rapidly in this configuration. Understanding the specific flow of heat and water in watertube boilers helps in recognizing their advantages in various applications, such as in power plants where quick steam generation is critical.

This distinguishes watertube boilers from other types, such as firetube boilers, where combustion gases pass through the tubes themselves and are surrounded by the water.