Mass transfer controlled corrosion of pipelines under two phase (gas—liquid) flow

Abstract

Rates of diffusion controlled corrosion of smooth and rough pipes were studied under single phase liquid flow and two phase (gas–liquid) flow using the diffusion controlled dissolution of copper in acidified FeCl₃. The study was carried out using a recirculating batch tubular reactor through which acidified FeCl₃ solution was circulated. The mass transfer coefficient of the dissolution of the copper pipe in the solution was obtained from FeCl₃ concentration–time data. Variables studied were solution velocity, gas velocity, and peak to valley height of the rough pipe. For single phase fully developed flow, the mass transfer coefficients of the smooth uncorroded pipes were correlated for the conditions 3000 < Re_L < 18 000 and 1688 < Sc < 1899 by the equation Sh = 0·054Sc^O·33Re_L ^0·79, where Re_L is the liquid Reynolds number, Sc is the Schmidt number, and Sh is the Sherwood number. For single phase flow in rough pipes, the data were correlated for the conditions 5 < e⁺ < 52·5, 3000 < Re_L < 18 000, and Sc = 1688 by the equation Sh =0·0383Sc^O·33Re_L ^0·92, where e⁺ is the dimensionless roughness. For two phase flow in smooth pipes, the data were correlated for the conditions 3000 < Re_L < 18 000, 213 < Re_g < 2137, and Sc = 1688 by the equation Sh = 0·025Sc^O·33Re_L ^0·66Re_g ^0·39, where Re_g is the gas Reynolds number. For two phase flow in rough pipes, the data were correlatedfor the conditions 3000 < Re_L < 18 000, 213 < Re_g < 2137, and 0·5 mm <e < 1·25 mm by the equation Sh = 0·l SC^O·33Re_g ^0·79Re_g ^0·39(e/d)^o·4, where e is the peak to valley height of the roughness elements and d is the tube diameter.