Bifurcation Behavior and Efficient Pure Hydrogen Production for Fuel Cells Using a Novel Autothermic Membrane Circulating Fluidized-Bed (CFB) Reformer: Sequential Debottlenecking and the Contribution of John Grace
Bibliographic record
Abstract
I am pleased to contribute, together with my Ph.D. student Zhongxiang Chen, this paper to the Ind. Eng. Chem. Res. special issue for Professor John Grace of the University of British Columbia in recognition of his many contributions to subjects of interest to readers in this journal. I have known John since the early 1970s (over 30 years now) when we were both studying for our Ph.D.'s in the U.K. (he was in Cambridge, and I was in Edinburgh). Since then, we have always been in close contact. I visited him at McGill and British Columbia Universities, and he visited me at King Saud and Auburn Universities, and we cooperated in the development of novel fluidized-bed reformers (e.g., Adris, A.; Grace, J.; Lim, C.; Elnashaie, S. S. E. H. Fluidized Bed Reaction System for Steam Hydrocarbon Gas Reforming to Produce Hydrogen. U.S. Patent 5,326,550, Jun 1994; Canadian Patent 2,081,170, Dec 2002). This was our first explicit application of the sequential debottlenecking methodology, although John has used the approach implicitly in many cases to develop novel processes. He is running the Fluidization Research Center (FRC), which he established in 1997 at the University of British Columbia (UBC) and which is funded by Mitsubishi Chemical Corporation (MCC), the Natural Science and Engineering Research Council of Canada (NSERC), and a number of other government and industrial sponsors. The contributions of Professor Grace to fluidization and fluidized-bed reactors are outstanding. Recently, he edited the excellent proceedings for the 7th International Conference on Circulating Fluidized Beds, Niagara Falls, Ontario, Canada, May 5−8, 2003, and contributed excellent papers to it. I would like to congratulate John for his latest award of the Innovation and Science Council of British Columbia for 2003. He was accorded this prestigious award for distinguishing himself as an educator, researcher, and innovator in his 35-year career as a leading authority on fluidization and chemical reaction engineering. I would like also to congratulate him for his recovery from his latest operation and wish him a fast and safe complete recovery. If you want to know more about the outstanding achievements of Professor John Grace, I advise you to visit his Web site at the University of British Columbia, Canada ( http://faculty.chml.ubc.ca/jgrace/ ). The present paper is an investigation of the bifurcation behavior of a novel circulating fluidized-bed (CFB) autothermic reformer. I have learned a lot about CFBs from the excellent work of Professor John Grace. My Ph.D. student Zhongxiang Chen and I are happy to contribute this paper to this special IECR issue in the honor of this excellent academician. Said S. E. H. ElnashaieThe multiplicity of steady states (static bifurcation behavior, SBB) in a novel circulating fluidized-bed (CFB) membrane reformer for the efficient production of hydrogen by steam reforming of heptane (model component of heavy hydrocarbons) is investigated. The present paper highlights the practical implications of this phenomenon on the behavior of this novel reformer with a special focus on hydrogen production. Two configurations are considered and compared. One has catalyst regeneration before gas−solid separation, and the other has catalyst regeneration after gas−solid separation. The multiplicity of the steady states prevails over ranges of a number of design and operating parameters with significant impacts on the performance of the reformer. The basis of process evaluation is focused on the net hydrogen production. The dependence of the behavior of this autothermal CFB is shown to be quite complex and to defy the simple logic of nonautothermal processes. The unit can be a very efficient hydrogen producer provided that its bifurcation behavior is well understood and correctly exploited.
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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) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 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".