Dip-tube erosion is a silent efficiency loss. The first signal is rarely at the dip tube itself — it shows up downstream as rising dust loading, falling cyclone separation efficiency, and a slow climb in stack opacity. By the time anyone inspects the dip tube, gas has been short-circuiting through the eroded section for weeks. The cause is mostly mechanical: high dust velocities, abrasive raw mix, and thermal cycling. The cost is process-wide and grows quietly until the next planned outage exposes it.
Why this matters in the preheater
A degraded dip tube lets gas bypass the cyclone vortex without being separated from dust. Separation efficiency drops, and the dust that would have been collected by that stage moves downstream — into the next cyclone, the ID fan, the conditioning tower, or eventually the stack. Each downstream stage absorbs some of that lost duty, but it accumulates: pressure drop rises, fan power climbs, and stack emissions edge upward.
The slow nature of the loss is what makes it expensive. By the time the dip tube is inspected at a planned stop, it has often been costing efficiency for an entire campaign. Inspection windows on dip tubes — visual or temperature-mapping — pay back faster than most people expect.