A Linearized Corrosion Double-Layer Model for Laminar Flow Electrification of Hydrocarbon Liquids in Metal Pipes
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- 作者：H. Chen ; G. G. Touchard ; and C. J. Radke
- 刊名：Industrial & Engineering Chemistry Research
- 出版年：1996
- 出版时间：September 1996
- 年：1996
- 卷：35
- 期：9
- 页码：3195 - 3202
- 全文大小：243K
- 年卷期：v.35,no.9(September 1996)
- ISSN：1520-5045
文摘
A metal/liquid interface corrosion-reaction model is developed forthe flow electrification of low-conductivity liquids in metal pipes. In the proposed model,impurity anions participate in acorrosion reaction at the wall, leaving a net positive ionconcentration in the diffuse electricaldouble layer. Convection of this positive charge constitutes thestreaming current. Theoreticalcalculations for the convected space charge density demonstrate avelocity-dependent entranceeffect that diminishes in pipes of larger radii, in agreement withexperimental data for heptanein stainless steel pipes. Far downstream, the proposed model alsocorrectly predicts that theconvected space charge density falls with increasing pipe radius.As in previous work, theconvected space charge density far downstream,(I/Qecb)
, is found tobe linear with the
-potential. However, the proposed model is self-consistent inthat the -potential arises aspart of the calculation and is not an adjustable constantcharacteristic only of the metal/hydrocarbon interface. In the entrance region, the convected spacecharge density is assumedto vary exponentially with axial position with the form(I/Qecb) =(I/Qecb) -A(I/Qecb)1×exp(-
), where A is a preexponentialfactor, (I/Qecb)1 is adeviation function, is a characteristiceigenvalue, and is the dimensionless axial coordinate.With a known value of 79.8 
m for thesolution Debye length, calculations show A to be 0.075, and(I/Qecb)1 and to be7.98 (10-4),1.42 (10-4), and 2.60 (10-5) and 1.242,2.425, and 2.938, respectively, for pipe radii of 0.24,0.58,and 1.25 mm, respectively.
, is found tobe linear with the-potential. However, the proposed model is self-consistent inthat the -potential arises aspart of the calculation and is not an adjustable constantcharacteristic only of the metal/hydrocarbon interface. In the entrance region, the convected spacecharge density is assumedto vary exponentially with axial position with the form(I/Qecb) =(I/Qecb) -A(I/Qecb)1×exp(-), where A is a preexponentialfactor, (I/Qecb)1 is adeviation function, is a characteristiceigenvalue, and is the dimensionless axial coordinate.With a known value of 79.8 m for thesolution Debye length, calculations show A to be 0.075, and(I/Qecb)1 and to be7.98 (10-4),1.42 (10-4), and 2.60 (10-5) and 1.242,2.425, and 2.938, respectively, for pipe radii of 0.24,0.58,and 1.25 mm, respectively.