Case study on corrosion protection of petrochemical heat exchanger tube bundles: Heat exchanger tube bundles with a polymer coating have been in use for over 8 years

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This post was last edited by Wang Wei2 on 2020-5-31 at 11:08. Case study on corrosion protection for heat exchanger tubes in the petrochemical industry – Heat exchanger tubes coated with polymers have been in use for over 8 years. 1. Overview: We know that since the 1970s, the petrochemical industry has adopted various measures to address corrosion in cooling equipment, depending on the specific corrosion conditions. Through years of effort, significant results and economic benefits have been achieved. However, there are still some issues that remain unresolved in the current situation. In particular, there is still no effective solution to the corrosion problem of the outer walls of the tube bundles in coolers and condensers. For example, the inner and outer walls of the tube bundle are protected against corrosion using 7910 coating (epoxy amino); there is no corrosion inside the tubes but scale has formed there, while the outer walls are severely corroded. For example, in the atmospheric and vacuum distillation primary overhead condenser, the tubes in the tube bundle are Φ25×2.5 in diameter, the diameter of the tube bundle itself is Ф1100, and the material used is 10# carbon steel. If the tube bundle is not protected against corrosion, it will become ineffective in less than 2 years. A considerable portion of the tubes suffered corrosion perforations after use; those without corrosion pits experienced an average annual thinning of 1.2 millimeters. The anti-corrosion coating on the inner wall of the tubes was damaged, resulting in uneven corrosion pits and layers of dirt. Generally, the microstructure in these low-temperature areas is normal ferrite and pearlite structure, with no changes in the microstructural pattern. See Figures 1 and 2 for details. 2. Performance of the polymer-coated tubes: We installed 2 sets of tube bundles with a polymer coating in the atmospheric and vacuum light ends condensers; the operating conditions are shown in Table 1. After opening the equipment for maintenance after 3 years of use, the results are shown in Table 2 and Figures 3–6: Table 1 Operating Conditions Name – Tube side/Shell side; Inlet and outlet temperatures in °C; Inlet pressure in Mpa; Operating medium. Table 2 Comparison between titanium nanotube bundles and 7910-coated tube bundles. Application area – Vacuum and atmospheric distillation primary condenser. A considerable portion of the outer wall of the tube bundles was corroded and perforated; the average annual thickness loss in areas without corrosion pits was 1.2 millimeters. The anti-corrosion coating on the inner walls of the tubes was damaged, resulting in uneven corrosion pits and layers of dirt. Upon core extraction inspection, it was found that the inner and outer walls of the tube bundle were in perfect condition, with no grooves or rust on them. The anti-corrosion tube bundle was in use for 8 years without the coating losing its effectiveness. Polymer-coated tube bundles are a material with good comprehensive properties, and they represent one of the effective methods for addressing corrosion in the tube bundles of petrochemical water coolers.