![Sample our Engineering & Technology journals, sign in here to start your access, latest two full volumes FREE to you for 14 days]({"type":"image" , "src" : "/sda/5933/TOC-Subject-Sample-2021-Engineering-Tech.jpg"})
ABSTRACT
Supercritical water fluidized bed reactor is a promising in the clean and efficient conversion of coal, and the distributor is one of the key component for the heat and mass transfer enhancement. However, the optimization study for the distributor in supercritical water fluidized bed reactor has been seldom conducted due to the special thermal properties of supercritical water. In this work, the swirling flow distributor was designed for its optimization for heat and mass transfer inside a supercritical water fluidized bed reactor. The swirling flow can be generated by the concentric circle or triangle type hole distribution in distributor with 0 or 45° intersection angle between the fluid inlet velocity direction and the distributor plane. The computational particle fluid dynamics (SCWFB) method, which has quick calculating speed and high accuracy, was used in this work to study the particle-fluid two-phase flow behaviors inside SCWFB with swirling flow distributors. Investigations were made to reveal the influence of the hole distribution type and intersection angle on the bed pressure drop and particle volume fraction characteristics. The results showed that the triangle type distributor with 45° intersection angle has the best fluidization performance. The conclusions drawn may has potential application for continuous and stable operation of supercritical water fluidized bed reactor for coal gasification.
Acknowledgments
This work was financially supported by the China National Key Research and Development Plan Project (Contract No. 2016YFB0600100), National Natural Science Foundation of China (Contract No. 51776169 and 51323011) and Shaanxi Science & Technology Co-ordination & Innovation Project (Contract No. 2015TZC-G-1-10)
Nomenclature
| A | = | particle acceleration (m2/s) |
| CPFD | = | computational particle fluid dynamics |
| Dp | = | drag coefficient |
| DPM | = | discrete particle method |
| f | = | particle probability distribution function |
| F | = | momentum exchange per volume (kg·m−2·s−2) |
| g | = | gravitational acceleration (m2/s) |
| m | = | mass (kg) |
| p | = | pressure (Pa) |
| ps | = | a positive constant of pressure (Pa) |
| P0, P1, P2 | = | pressure probe point in supercritical fluidized bed |
| SCW | = | supercritical water |
| SCWFB | = | supercritical water fluidized bed |
| t | = | time (s) |
| TFM | = | two fluid method |
| u | = | velocity (m/s) |
| uf | = | fluid velocity (m/s) |
| up | = | particle velocity (m/s) |
| umf | = | minimum fluidized velocity (m/s) |
Greek symbols
| γ | = | a constant recommended to be 2–5 |
| ϵ | = | volume fraction |
| ϵcp | = | particle volume fraction at the close packing |
| θ | = | a small value with the order of 10−7 to eliminate the singularity |
| ρ | = | density (kg/m3) |
| τ | = | stress tensor (Pa) |
Subscripts
| cp | = | close packing |
| f | = | fluid |
| mf | = | minimum fluidization |
| p | = | particle |
Additional information
Notes on contributors
Hui Jin
Hui Jin is an associate professor in State Key Laboratory of Multiphase Flow in Power Engineering, Xi'an Jiaotong Univeristy. He received his PhD degree from Xi'an Jiaotong University in 2011. Currently his research mainly focuses on coal gasification in supercritical water and its heat mass transfer characteristics.
Zhenqun Wu
Zhenqun Wu is a PhD candidate in State Key Laboratory of Multiphase Flow in Power Engineering. He received his bachelor's degree from Xi'an Jiaotong University in 2010. His main research direction is the granular flow behaviours inside supercritical water fluidized bed.
Liejin Guo
Liejin Guo is the dean of State Key Laboratory of Multiphase Flow in Power Engineering. He is Most Cited Researchers in Energy Science and Engineering, Elsevier, 2016, Highly Cited Researchers in Engineering, Thomson Reuters, 2015, The World's Most Influential Scientific Minds, Thomson Reuters, 2014. His research field is multiphase flow and heat and mass transfer, high efficient clean energy-power system and thermal power conversion process.
Xiaohui Su
Xiaohui Su is a PhD candidate in State Key laboratory of Multiphase Flow in Power Engineering. His Research Interests focus on multiphase flow, heat and mass transfer involved in advanced energy conversion technology.