Density, viscosity, and stability of products from combinations of visbreaking and deasphalting
Bibliographic record
Abstract
Abstract Transporting bitumen through pipelines in Western Canada is cost intensive because the oil has to be diluted with light solvents to meet pipeline specifications. The diluent requirement can be reduced by visbreaking (VIS) and solvent deasphalting (SDA), each of which decrease the viscosity and density of the oil. Combinations of the two processes can provide a greater viscosity and density reduction while minimizing the risk of asphaltene precipitation and coke formation. However, data on the product properties are required to assess these combined processes. In this study, a Western Canadian bitumen was visbroken at conversions from 24% to 42% and each product was then deasphalted with extents ranging from 50% to 96 wt.% asphaltene removal (VIS‐SDA sequence). The same bitumen was deasphalted with extents from 30% to 96% and each deasphalted oil was then visbroken at conversions from 6% to 44% (SDA‐VIS sequence). The following measurements were performed on the products: simulated distillation, gas yield, pentane‐insoluble asphaltene content, toluene insoluble (TI) content, density, viscosity, and stability. Stability was assessed in terms of the onset of asphaltene precipitation from mixtures of oil and n ‐heptane. Neither the VIS‐SDA nor the SDA‐VIS sequence met the pipeline density specification, but both were able to reduce the diluent requirement to approximately 10 wt.% compared with 28 wt.% for the feed bitumen. The VIS‐SDA sequence offered better product stability; however, the suitability of the separated asphaltenes for downstream processes has not been established. The SDA‐VIS sequence produced usable asphaltenes but less stable oil products.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.001 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".