ELSEVIER June 1997 Materials Letters 31 (1997) 291-296 Diffusion-controlled corrosion of gas agitated convection conditions S.A. Nosier vessel under forced zyxwvuts Chemical l%gineering Department, Faculty of Engineering, Alexandria University, Alexandria 21544, Egypt IReceived 13 September 1996; revised 15 November 1996; accepted 18 November 1996 zyxwvutsrqponmlkjihgfedcbaZ Abstract The rate of diffusion-controlled corrosion of a bubble column was studied by determining the rate of diffusion-controlled dissolution of the column wall (copper) in acidified chromate solution. Variables studied were gas (N,) flow rate, physical properties of the solution and the height of the solution in the column. For particle-free solution, the data were correlated by an empirical equation. The effect of solid particles on the rate of diffusion-controlled corrosion in a bubble column containing suspended solid was also studied. Keywords: Diffusion: Corrosion; Gas agitated vessel; Forced convection 1. Introduction Bubble columr~s and slurry bubble column reac- tors are used in many areas of chemical industries such as fermentation, hydrogenation, oxidation or chlorination of organic liquids. In view of their cheap and simple construction, large effective interfi- cial area and high heat and mass transfer coeffi- cients, these devices are preferred to other gas-liquid contactors. Such reactors usually handle corrosive fluids and suffer severely from corrosion. The rate of corrosion may be determined by the rate of dissolved oxygen to the corroding surface or the rate of diffu- sion of the corrosion products away from the corrod- ing surface. In view of the enormous financial losses caused to chemical industries as a result of corrosion, much attention has been directed to diagnosing and reme- dying corrosion prolblems in chemical plants. Most attention was directed to corrosion in pipelines [l] and mechanically agitated vessels [2-41 and little attention has been given to the corrosion of bubble columns in spite of its importance. The object of the present work is to study the rate of diffusion-controlled corrosion in bubble columns in the presence and absence of solid particles. The present study was conducted by measuring the rate of diffusion-controlled dissolution of the copper wall of a bubble column in acidified chromate solution; this technique has been frequently used to study liquid-solid mass transfer in view of its accuracy and simplicity [5-91. 2. Experimental technique A schematic diagram of the experimental setup is shown in Fig. 1. It consisted of a copper cylindrical 00167-577X/97/$17.00 Copyright 0 1997 Elsevier Science B.V. All rights reserved. PII SO167-577X(96)00288-1