The August newsletter introduced information related to the importance of jacket cleaning to reactor longevity. Since August we had the opportunity to replace the lower sealer ring on a glass lined reactor that had been in service since 1991. This vessel is in service with approximately 25 additional reactors installed at the same time or earlier.
The glass lining protects the base metal of a reactor so effectively that corrosion will usually occur in another area. All too often deterioration of the reactor jacket goes unnoticed. Although the heat transfer fluids used in the jacket space are relatively mild (especially in comparison to the contents inside the reactor itself), they will generally attack the jacket as well as the reactor exterior long before the glass-lined interior becomes damaged.
Iron oxide corrosion is the most common form of jacket fouling. Fouling interferes with heat transfer. It results in extended heating and cooling times, a reduction in product quality, and equipment deterioration.
Corrosion accelerates via steam condensate. Dissolved materials like calcium, magnesium, silica and iron distill from the plant service water. These materials deposit on the inside of the jacket diminishing the heat transfer process.
The Big Picture: During the normal thermal cycles material will distill from the coolant. A maintenance procedure to clean the jacket will remove the material. If not removed, the scaling will build up until it diminishes the thermal efficiency. In addition, scaling will encourage deterioration of the lower jacket which can lead to other expensive repairs.