Equivalent Residence Time (ERT) as a Correlating Parameter for Visbroken Bitumen Properties
Bibliographic record
Abstract
Field visbreaking of bitumen is a possible path to reducing diluent requirements for pipeline transport. To design such processes, tools are needed to relate visbroken product properties to the reactor conditions. The purpose of this study was to collect property data of visbroken bitumen products and use the data to develop correlations of product properties with reactor temperature and space time. Two Western Canadian bitumens, a deasphalted bitumen, and a vacuum residue fraction were visbroken over a range of temperatures and space times in a continuous tubular reactor. The following measurements were performed on the visbroken products: SimDist, C7-asphaltene content, C5-asphaltene content, toluene-insoluble (TI) content, gas yield, viscosity, and density. The distillate and residue contents and the conversion (a measure of the extent of reaction) were determined from the SimDist. The product stability was assessed in terms of the wt % of n -heptane required to cause asphaltene precipitation (onset). The composition, density, viscosity, and stability of the visbroken products were first correlated with conversion and feed properties. The conversion was then correlated with the equivalent residence time (ERT), a function of temperature and space time only. The product properties were determined from previously developed correlations using the conversion determined from the ERT. The average absolute deviation of the correlated conversion was 2.4 percentage units, almost within the error of the measurement. The average deviations of the compositions were all within experimental error. The deviations for the density (1.4 kg/m 3 ) and viscosity (22%) exceeded experimental error but were typical for density and viscosity correlations of crude oils. Hence, ERT was found to be a sufficient parameter for the correlation of conversion and visbroken bitumen product properties, at least for Western Canadian bitumen. The final set of correlations depends only on the reactor conditions and feed properties.
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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 | 0.001 | 0.002 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.002 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| 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".