Problems with operating heat exchangers under oxygenation conditions
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Generally, to prevent corrosion of the wall surfaces of heat exchange tubes, the oxygen content in the medium should be as low as possible. In supercritical power plants, high-pressure heaters operate with oxygen present, so as to form a dense layer of iron oxide on the wall surfaces. Question: 1. How are the oxygen addition amount and time controlled? 2. How thick is the oxide layer? 3. Could there be opposite effects, such as local corrosion or the shedding of the oxide layer? This post was last edited by email_cao on 2009-4-5 09:27]
No one answered; here’s a link for you to take a look: http://cache.baidu.com/c?m=9d78d513d9d431a54f9be0697b15c016124381132ba7a10209d5843999732a4b506793ac56260770d6d27c1616df384b9cf12173471456b48cbc8f5ddccb855e299f5644676a845664d10de88b182a9b66d618feae6afaa7a63093a8d1d8d55244ca245524dda59c5a77449736a74326e3d1c51f534240e4b06530a8192874c9641ee15aa9be6f3b10868299071b867a8e3c4480af42e66305b467ff490c2532ab49b2035421&p=8c7f8d16d9c401ff57eb91295208&user=baidu
Water oxygenation treatment technology was successfully applied in countries in Europe such as Germany as early as the early 1970s. Our country is now starting to roll it out gradually. Therefore, I hope to discuss with everyone the experiences gained during the application process. Principle: By oxygenating the feed water, its redox potential is increased from -300/400 mV under the fully volatile treatment (AVT) condition to +100/150 mV. At this point, the magnetic oxide (Fe3O4) on the surface of carbon steel is covered and protected by a thin, dense layer of γ-FeOOH (or α-Fe2O3). Due to the very low solubility of trivalent iron, the migration and deposition of corrosion products in the boiler are reduced. Practice has shown that the oxide film formed by oxygenation of the feed water possesses strong corrosion resistance. Oxygenation of the feed water can reduce the pressure loss in the boiler, decrease the number of times regeneration is required for condensate treatment, mitigate corrosion of the copper tubes in the condenser, and extend the interval between chemical cleanings of the boiler.