Asphaltene Precipitation Prediction via Solvent Power Ratios
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Solution Overview
Problem
Current methods for predicting asphaltene precipitation during refining are inadequate, as they rely on fixed margins between solvent power and critical solvent power, which can lead to unexpected fouling and economic constraints, especially in processing crude oil blends with high light paraffin content.
Innovation Solution
A method that divides hydrocarbon fluids into subgroups based on the ratio of solvent power to critical solvent power, determines the threshold light paraffin content for each subgroup, and establishes a relationship between this ratio and fouling tendency to predict asphaltene precipitation, allowing for accurate assessment and blending adjustments to prevent fouling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a fixed margin of 5-15% between solvent power and critical solvent power is maintained, then asphaltene precipitation risk is reduced, but fouling still occurs in crude oil blends with high light paraffin content and economic constraints arise
Solution Approach 1:
The invention changes the prediction parameter from a fixed solvent power margin (5-15%) to a light paraffin content threshold parameter. This allows the prediction model to account for the specific compositional characteristics of different crude oil blends, particularly the effect of light paraffins on asphaltene stability, thereby improving prediction accuracy without unnecessarily constraining feedstock selection flexibility
Solution Approach 2:
The invention segments crude oil blends into different subgroups based on their light paraffin content thresholds. Each subgroup has its own specific threshold value that determines asphaltene precipitation risk. This segmentation allows for more nuanced and accurate predictions compared to the blanket fixed margin approach, enabling better adaptation to different feedstock types
2Stability of the object's composition
If thermal expansion is managed to maintain solvent power, then asphaltene stability is improved, but the complexity of process control increases
Solution Approach 1:
The invention determines the light paraffin content threshold in advance for each crude oil blend subgroup before processing. This preliminary characterization allows operators to predict asphaltene precipitation risk without requiring complex real-time monitoring and control systems during thermal expansion processes, thereby maintaining asphaltene stability while avoiding increased process control complexity
3Stability of the object's composition
If pressure is maintained to prevent boiling point reduction, then thermal expansion effects are reduced, but energy consumption increases
Solution Approach 1:
The invention replaces the mechanical approach of maintaining high pressure to prevent boiling and thermal expansion with a compositional analysis approach. By determining light paraffin content thresholds and using them to predict precipitation risk, the system allows normal pressure reduction and thermal expansion to occur while still maintaining asphaltene stability through informed feedstock selection and blending decisions, thereby reducing energy consumption
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach provides a more accurate prediction of asphaltene precipitation risks, reducing fouling in refineries by identifying optimal blending ratios, thereby enhancing operational efficiency and reducing economic constraints.
Implementation Method 1
During the entire cold and hot pre-heating stages, the crude oil undergoes thermal expansion. The solvent power of the crude oil is inversely related to the molar volume of the crude oil. Thus, as the crude oil undergoes thermal expansion, the molar volume increases and the solvent power drops.
Implementation Method 2
However, once the crude oil has entered the furnace, components of the crude oil begin to vapourise. As components are evolved from the oil, the solvent power of the remaining liquid phase increases and asphaltene precipitation risks are generally lowered.
Implementation Method 3
If the solvent power falls below the critical solvent power of the crude oil, asphaltenes in the crude oil become unstable and precipitation may be observed.
Data Source
Figure 1
Figure 2
Figure 3a~3b
AI summary
A method for determining a relationship between the ratio of solvent power to critical solvent power and the threshold light paraffin content of a hydrocarbon fluid is provided. The method comprises: dividing the plurality of hydrocarbon fluids into subgroups, based on the ratio of solvent power to critical solvent power; for each of the subgroups, determining the threshold light paraffin content, said threshold light paraffin content being the light paraffin content of the hydrocarbon fluids at the point at which the fouling tendency of the hydrocarbon fluids exceeds a fouling threshold; and determining a relationship between the ratio of solvent power to critical solvent power and the threshold light paraffin content.