Petrochemical processing, high-temperature corrosion

High-temperature corrosion is a practical problem in most applications of metals and alloys at elevated temperatures in corrosive environments. In power plants, chemical and petrochemical process industries, for aircraft engines, heat treatment and other metallurgical processes, and new technologies such as waste-incineration plants, high-temperature fuel cells, and so on, the metallic materials must he carefully selected, to allow sufficient lifetime and avoid premature failure. Sometimes processes are not possible since the materials would not withstand the process conditions that must he adapted to the available materials. 

Many models have been developed to explore the mechanisms involved in the high temperature corrosion processes found in the petrochemical industry, such as high temperature oxidation, sulfidation, naphthenic acid corrosion and carburization. The major focus of industrial application-oriented research... 

Many factors can affect high temperature corrosion processes in the petrochemical industry. Current investigations therefore aim to find the potential influences of some major factors on the corrosion processes and rates, such as temperature, velocity of flow and vacuum on high temperature naphthenic acid corrosion, and temperature and active sulfur content on high temperature sulfidation. 

Sulfur chemistry is important both in combustion and in the petrochemical industry. Most fossil fuels contain sulfur, and also biofuels and household waste have a sulfur content. As a consequence sulfur species are often present in combustion processes. Knowledge of gas-phase sulfur chemistry occurring in combustion has bearing on pollutant emissions and on system corrosion. Air pollution by SO2 still constitutes a major environmental concern and search for control techniques has motivated research also on high-temperature homogeneous sulfur chemistry. However, more recent work on sulfur chemistry has been concerned mainly with the effect of sulfur on other pollutant emissions, such as NO and CO, and with the SO3/SO2 ratio, which is important for the corrosive potential of the flue gas and for formation of sulfur containing aerosols. 

In selecting materials for petrochemical plants, considerable effort should be paid to fluid composition, sizing of lines, valve and pump details, and processing temperature and pressure. Most environments in petrochemical processes involve flammable hydrocarbon systems, highly toxic chemicals, explosive gases, and strong acids and caustics. Therefore corrosion could be a mysterious and costly enemy to the safety of personnel and community. 

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