In a firetube boiler, soot accumulates on which part?

In a firetube boiler, soot primarily accumulates on the inside tube surface. This is because the combustion gases, which contain particulate matter and unburned fuel, pass through the tubes where the water or steam is held. As these gases flow, they can deposit carbon, ash, and other particulate matter on the interior surfaces of the tubes during the combustion process.

Regular maintenance and cleaning of the inside tube surfaces are essential to ensure efficient heat transfer and to prevent potential issues with overheating or reduced boiler performance. If soot buildup is not managed, it can lead to decreased efficiency and even dangerous operating conditions.

The other components mentioned do not typically accumulate soot in the same manner. The outside tube surface, for example, would not collect soot as it is not in direct contact with the combustion gases. Similarly, while the heat exchanger is designed to facilitate temperature transfer, it does not typically accumulate soot as a firetube does. The smoke stack may have some residual deposits from flue gases, but this is not the primary location where soot accumulates in the context of a firetube boiler operation.