Fluid Corrosion General

Alter the chemistry of the common fluid to render it less conductive and/or less corrosive. Generally, water corrosivity increases with an increase in temperature and oxygen content and a decrease in pH. Inhibitors may he effective. Note that in mixed-metal systems, higher dosages of inhibitors may be required than would be necessary in single-metal systems in the same environment. 

Erosion-corrosion. Generally, all types of corrosive media can cause erosion-corrosion, including aqueous solutions, organic media, gases, and liquid metals. The corrodent can be a bulk fluid, a film, droplets or a substance adsorbed on or absorbed on another substance. For example, hot gases may oxidize a metal at high velocity and blow off an otherwise protective scale. Solid suspensions in liquids (slurries) are particularly destructive from the standpoint of erosion corrosion.16 31... 

Field Safety. The objective of well stimulation is to use highly pressurized fluids to improve the productivity of petroleum reservoirs. This objective will not be achieved if the productivity is improved at the expense of the workers or equipment safety. The well stimulation sector of the petroleum industry is a hazardous sector that not only involves the use of highly pressurized fluids, but also includes fluids that may be flammable or corrosive or contain radioactive tracers. Foams that use compressed gas may be hazardous if the gas is allowed to expand quickly. Reservoir fluids also pose a danger to field personnel and equipment, because the fluids are generally flammable, combustible, or extremely poisonous, as is the case with H2S. 

CORROSION, IMPINGEMENT - A form of eroslon-corrosion generally associated with local impingement of a high velocity, flowing fluid against a solid surface. 

In this chapter, the progress that has been made in this area will be reviewed. First, however, the nature of supercritical fluids in general will be introduced and then the properties of supercritical water in particular discussed. In the final section, corrosion problems faced by those wishing to establish processes are examined. 

Corrosion inhibiting surfactants used in lightweight fluids for general and oxygen-related corrosion include ... 

The use of supercritical and hot water as a solvent is still largely experimental. Because supercritical technology is well known in the power industry, this use of water is likely to increase in the future. Corrosion control may be an important limiting consideration. General process economics are the second potential limit (see SUPERCRITICAL FLUIDS). 

Selection of Flow Path In selecting the flow path for two fluids through an exchanger, several general approaches are used. The tube-side fluid is more corrosive or dirtier or at a higher pressure. The shell-side fluid is a liquid of high viscosity or a gas. 

Basic to establishing whether power recovery is even feasible, let alone economical, are considerations of the flowing-fluid capacity available, the differential pressure available for the power recovery, and corrosive or erosive properties of the fluid stream. A further important consideration in feasibihty and economics is the probable physical location, with respect to each other, of fluid source, power-production point, and final fluid destination. In general, the tendency has been to locate the power-recoveiy driver and its driven unit where dictated by the driven-unit requirement and pipe the power-recoveiy fluid to and away from the driver. While early installations were in noncorrosive, nonerosive services such as rich-hydrocarbon absorption oil, the trend has been to put units into mildly severe seiwices such as amine plants, hot-carbonate units, and hydrocracker letdown. 

Figure 7.25 Smooth, wavelike contour in a region of general metal loss on copper due to carbonic acid. The groove patterns indicate channeling of corrosive fluids by flow. (Light is coming from the reader s right.)...

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