Hydrodynamics and Micro Flow Structure of Gas- Solid Circulating Turbulent Fluidized Beds
Bibliographic record
Abstract
Circulating Turbulent Fluidized Beds (CTFB) refer to fluidized beds integrated into high density circulating systems to simultaneously achieve highly efficient gas-solid interactions existing in turbulent fluidized beds and low solids backmixing featured by circulating fluidized beds. Hydrodynamics and micro flow structure were experimentally studied in a CTFB (3.6 m high and 0.104 m id) using 76 µm FCC particle with air velocities of 0.5 ~ 5.0 m/s and solids circulation rates of 0 ~ 420 kg/m2s The distributions of solids holdup were acquired using optical fibre probes and pressure transducers at sampling frequencies of 50 kHz × 131 s and 1 kHz × 400 s respectively. A Pseudo Bubble-Free Fluidized Bed was developed to dynamically calibrate the optical fibre probes. Based on statistical parameters, a Moment Consistency Data Processing Method (MCDPM) was proposed to calculate solids holdups of the dense and dilute phases from the experimental data. A Divided Phase Cross-Correlation Method (DPCCM) was adopted in cross-correlating the solids holdup signals of the dense and dilute phases to obtain the phase particle velocities.\nMCDPM provided average solids holdups of the dense and dilute phases and the phase fractions over bubbling (BFB), turbulent (TFB), circulating turbulent (CTFB), high density circulating (HDCFB) and circulating (CFB) fluidized beds. The flow structure in terms of phase division and the micro flow characteristics were studied across all five regimes from low to high velocities, CTFB was found to have strong similarities with TFB.\nStudy on the detailed hydrodynamics and transition characteristics of the CTFB demonstrated that solids holdup distribution in CTFB was more homogeneous both axially and radially than that of other regimes, and the local solids flux and the local particle velocity were both proportional to the solids circulation rate. Microscopically, CTFB was characterized by dilute phase dominating flow in the centre and dense phase dominating flow in the annular region. Such flow structure was different from either dense phase dominating flow in BFB or dilute phase dominating flow in CFB. New criteria for the transition air velocities were proposed for CTFB. The results demonstrated that the onset transition velocity from BFB to CTFB remained nearly unchanged, and the ending transition air velocity from CTFB to CFB increased, with increasing solids circulation rate.
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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 | 0.001 |
| Scholarly communication | 0.001 | 0.001 |
| 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".