Method for Determining the Effectiveness of Asphaltene Antifoulants at High Temperature: Application to Residue Hydroprocessing and Comparison to the Thermal Fouling Test

Abstract

Using a new on-column filtration technique, the effectiveness of asphaltene antifoulants was determined by measuring the percentage of reduction of asphaltenes at process and near process conditions (up to 200°C such as heat exchangers). This methodology uses conventional HighPressure Liquid Chromatography apparatus (HPLC), is fast (<50min), uses a small amount of sample (<0.1 g of oil) and has very good repeatability and reproducibility (±7%) than conventional gravimetric methods (±14.5%). Laboratory experiments showed that the on-column filtration method can quantitatively measure asphaltene antifoulant activity by determining the percentage of reduction of asphaltene content versus the case without additives at high temperature. It allows performance of mass balances, is fast, repeatable and has little human intervention. For a hydroprocessed product, a virgin crude oil and three commercial antifoulants, comparisons of the on-column filtration method with the thermal fouling test gave correlations factors in the 0.69-0.99 range. Improved correlations were obtained (R 2 = 0.96-0.99) when the asphaltene contents were measured at near processes conditions (195°C) vs. room temperature (R 2 = 0.69-0.92). These results indicate that, in order to better predict fouling tendencies, measurements of the reduction of asphaltene contents should be carried out at temperatures as close as possible to those used during hydroprocessing.

Evaluation of the Compatibility of Crude Oil Blends and Its Impact on Fouling

“…The heater tube is composed of carbon steel. A detailed scheme of the instrument and methodology can be found elsewhere …”

“…A detailed scheme of the instrument and methodology can be found elsewhere. 24 During the testing, the fluid is constantly stirred to avoid sedimentation of particulates. It is also kept at high pressure (725 psi) under a nitrogen atmosphere to avoid vaporization of light components.…”

Selective Asphaltene Precipitation from Hydroconverted Bottoms

“…Asphaltenes are known to cause a wide range of problems in the petroleum industry for both upstream and downstream operations. To mitigate upstream problems, asphaltenes are often treated with additives , or are removed through various processes . One common method for removing asphaltenes is through solvent deasphalting. − The deasphalted oil (DAO) has made it possible to efficiently upgrade portions of heavy oils and residua by catalytic processes by preserving catalyst activity and lifetime. , …”

“…8 Asphaltenes are known to cause a wide range of problems in the petroleum industry for both upstream and downstream operations. To mitigate upstream problems, asphaltenes are often treated with additives 9,10 or are removed through various processes. 11 One common method for removing asphaltenes is through solvent deasphalting.…”