Monitoring-Based Fouling Mitigation in Crude Unit Preheat Trains Using Lab and Field Fouling Units

The physical and chemical mechanisms associated with crude-oil fouling are complex, which hinder effective applications of mitigation methods for the preheat-train (PHT) exchangers. In order to develop an effective mitigation strategy, it is essential to perform a root-cause analysis (RCA) to identify the source(s) of fouling precursors. The next step is to evaluate ways to interrupt or eliminate the source of fouling precursors and conditions under which they are generated.

The multi-year investigation in this presentation focused on monitoring-based mitigation to systematically perform the root-cause analysis using lab and field fouling units. The analysis included the effects of crude-oil blending, physical parameters (such as flow velocity and wall shear stress), wall temperature (heat flux), performance of desalter, iron-sulfide induced fouling, asphaltene conversion and the effects of inorganic salts. The fouling data obtained with lab and field-fouling units were used to develop the threshold fouling model, which was then used to develop maps that help identify PHT exchangers that are in the high-fouling zone. The threshold models were also implemented in Hexxcell Studioâ„¢ to assess the economic impact of fouling and predict future performance in the pre-heat train operation.

The combination of the fouling data from the lab and field fouling units and the simulations were used for the root-cause analysis based on which an effective mitigation strategy can be developed and its benefits assessed.