Nitrogen, pollutants metal corrosion

The refining industry generally seeks either to eliminate asphaltenes or to convert them to lighter materials because the presence of heteroelements cause pollution problems, e.g., sulfur and nitrogen, catalyst poisoning, and corrosion (formation of metal vanadates during combustion). 

Various types of non-hydrocarbon compounds occur in crude oils and refinery streams. The most important are the organic sulfur, nitrogen, and oxygen compounds. Traces of metallic compounds are also found in all crudes. The presence of these impurities is harmful and may cause problems to certain catalytic processes. Fuels having high sulfur and nitrogen levels cause pollution problems in addition to the corrosive nature of their oxidization products. 

Nitrogen dioxide is a powerful corrosive agent that acts on metal, stone, and even human tissue. Its brown color is responsible for the brown haze typically seen over a polluted city. 

As alluded to in Chapter 8, the ideal biomass feedstock for thermal conversion, whether it be combustion, gasification, or a combination of both, is one that contains low or zero levels of elements such as nitrogen, sulfur, or chlorine, which can form undesirable pollutants and acids that cause corrosion, and no mineral elements that can form inorganic ash and particulates. Ash formation, especially from alkali metals such as potassium and sodium, can lead to fouling of heat exchange surfaces and erosion of turbine blades, in the case of power production systems that use gas turbines, and cause efficiency losses and plant upsets. In addition to undesirable emissions that form acids (SOx), sulfur can... 

The pollutants include SO2, nitrogen oxides, chlorides, and phosphates. All gases in the Troposphere (Ne, Kr, He, and Xe) do not participate in atmospheric corrosion [11]. Only oxygen acts as an oxidizer in a cathodic reaction. The presence of CO2 in the electrolyte ( 300 ppm) decreases pH and increases the corrosion rate of metals. 

Atmospheric pollutants, such as sulfur dioxide, nitrogen oxides, hydrogen sulfide, ammonia (SO2, NOx, H2S, NH4, respectively), and particulate matter, are known to have an effect on corrosion of metals [4], The presence of SO2 in the... 

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