Distribution of the gas flow in fluidized beds with a slugging behaviour |
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| Affiliation: | 1. School of Chemical Engineering, Xiangtan University, Xiangtan 411105, China;2. Key Laboratory for Solid Waste Management & Environment Safety (Tsinghua University), Ministry of Education of China, Beijing 100084, China;1. Faculty of Engineering, University of Nottingham, Nottingham, NG7 2RD, UK;2. School of Mechanical, Aerospace and Automotive Engineering, Faculty of Engineering, Environmental and Computing, Coventry University, Coventry, CV1 2JH, UK;3. Department of Chemistry, Government College Women University, Faisalabad, 38000, Pakistan;1. Key Laboratory of Low-Grade Energy Utilization Technologies and Systems, Ministry of Education, Chongqing University, Chongqing 400044, PR China;2. School of Energy and Power Engineering, Chongqing University, Chongqing 400044, PR China;3. College of Mechanical and Power Engineering, Chongqing University of Science and Technology, Chongqing 401331, PR China;1. College of Chemical Engineering, Qingdao University of Science & Technology, Qingdao 266042, China;2. College of Marine Science and Biological Engineering, Qingdao University of Science & Technology, Qingdao 266042, China;3. State Key Laboratory of High-efficiency Utilization of Coal and Green Chemical Engineering, Ningxia University, Yinchuan 750000, China;1. Faculty of Engineering, University of Nottingham, Nottingham NG7 2RD, UK;2. School of Mechanical, Aerospace and Automotive Engineering, Faculty of Engineering, Environmental and Computing, Coventry University, Coventry CV1 2JH, UK;3. Department of Chemistry, University of Agriculture, Faisalabad 38000, Pakistan |
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| Abstract: | Capacitance probe measurements of the visible bubble flow rate have been made in a pressurized fluidized bed burning coal. The bed, of 0.3 × 0.3 m cross-section, was operated at pressures between 1.0 and 2.0 MPa and at temperatures between 750 and 900°C. The fluidizing velocity was 0.95 m/s and the mean particle diameter was 0.9 mm. Based on the experimental results, a model of the gas distribution between the bubble phase and the particulate phase in fluidized beds with a slugging behaviour was developed. The model accounts for the lack of bubble flow obtained if the two-phase theory is employed. In order to verify the model, simultaneous measurements of the visible bubble flow rate and of the gas flow rate through the bubbles were carried out in a bed of similar geometry but operating at ambient conditions. In this bed the fludizing velocity was varied between 1.6 and 2.7 m/s and the mean particle diameter was 1.0 mm. The through-flow of gas was measured with the aid of pressure probes. Evaluation of the experimental results using the model showed that this gas through-flow in the bubble phase subsequently increases the superficial gas velocity in the particulate phase between the vertically aligned bubbles (slugs), and that this gas velocity in excess of the incipient fluidization velocity is responsible for the large deviation from the two-phase theory. The associated increase of the particulate phase voidage was calculated via the Ergun equation. |
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