Black substance on the inner surface of the water wall
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Since the plant began operation, various inspections have revealed black deposits on the inner walls of the water wall pipelines, which cannot be removed with a cloth. Remove the black powdery substance from the pump inlet filter. Based on the operation data, there is no leakage in the coil. It should also be noted that during the initial commissioning of our plant, no chemical cleaning was carried out on the water wall system. Gentleman experts, has anyone encountered this situation? What’s the reason?
The inner wall is black due to the presence of a ferric oxide protective layer; the black powdery substance removed from the pump inlet filter is made up of detached oxide scale particles.
Take a sample for analysis to see if it dissolves in acid, which can help narrow down the possibilities