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Fluidized bed hydrodynamic modeling of CO2 in syngas: Distorted RTD curves
  • Ariane Berard,
  • Bruno Blais,
  • Gregory Patience
Ariane Berard
Polytechnique Montreal
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Bruno Blais
Ecole Polytechnique de Montreal
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Gregory Patience
École Polytechnique de Montreal
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Abstract

Bubbles rising through fluidized beds at velocities several times superficial velocities contribute to solids backmixing. In micro-fluidized beds, the walls constrain bubble sizes and velocities. To evaluate gas-phase hydrodynamics and identify diffusional contributions to longitudinal dispersion, we injected a mixture of H2, CH4, CO, and CO2 (syngas) as a bolus into a fluidized bed of porous fluid catalytic cracking catalyst while a mass-spectrometer monitored the effluent gas concentrations at 2 Hz. The CH4, CO, and CO2 trailing RTD traces were elongated versus H2 demonstrating a chromatographic effect. An axial dispersion model accounted for 92% of the variance in the data but including diffusional resistance between the bulk gas and catalyst pores and adsorption explained 98.6% of the variability. At 300 °C, the CO2 tailing disappeared consistent with expectations in chromatography (no adsorption). H2 and He are poor gas-phase tracers at ambient temperature. We recommend measuring the RTD at operating conditions.

Peer review status:IN REVISION

13 Feb 2021Submitted to AIChE Journal
16 Feb 2021Submission Checks Completed
16 Feb 2021Assigned to Editor
17 Feb 2021Reviewer(s) Assigned
04 May 2021Editorial Decision: Revise Major
09 May 20211st Revision Received
12 May 2021Submission Checks Completed
12 May 2021Assigned to Editor
16 May 2021Reviewer(s) Assigned
14 Jun 2021Editorial Decision: Revise Minor