Energy Sources, Vol.24, No.11, 1019-1030, 2002
The inhibitive characteristics of mixed inhibitor combinations under heat and mass transfer conditions
Oil and gas production operations are characterized by the inevitability of numerous technical problems related to the nature of the products and effluents. Moreover these problems change gradually and require a periodic adjustment of the solution. One of the major concerns in the oil and gas industry is corrosion. Corrosion can be defined as the destruction or deterioration of material because of a reaction with its environment. In this paper the inhibitive characteristics of mixed inhibitor combinations on mild steel, under controlled conditions of heat and mass transfer, have been investigated using a rotating cylinder electrode system. Potentiostatic polarization experiments were carried out in both inhibited and uninhibited brackish water solutions under isothermal and heat transfer conditions. The optimum concentrations of the inhibitors used were estimated under the isothermal and dynamic conditions. Under isothermal conditions, the limiting current density values of oxygen reduction in the brackish water followed the Eisenberg equation. The presence of heat transfer enhanced the oxygen transfer rate over and above the value under isothermal conditions. The corrosion potential, passivation potential, and passive current density values, were a complex function of temperature, flow rate, and heat transfer. The anodic current density values increased with increases in temperature, flow rate, and the presence of heat transfer. The mixed inhibitor combinations showed high protection efficiency under the studied heat and mass transfer conditions.
Keywords:corrosion inhibitors;mild steel;rotating cylinder electrode;potentiostatic polarization curves;heat transfer conditions;mass transfer conditions;brackish water