Document Type : Research Paper

Authors

• Zahraa S. Hassan ¹
• Asawer A. Al Wasiti ²
• Zainb Y. Shnain ²
• Peter Philib ³

¹ Chemical Engineering Department, University of Technology, Baghdad, Iraq

² Chemical Engineering Department / University of Technology / Baghdad /Iraq

³ Mechanical Engineering and Energy Processes, Southern Illinois University, USA

Abstract

The importance of using EBR has been renewed recently due to the sharp increase in heavy feedstocks sent to refineries and the hydrocracking process. Most of these feedstocks have a non-Newtonian behavior. The performance of this type of reactor using non-Newtonian liquid is complicated and has not been covered well yet. Hence, the present work is devoted to elucidating the effect of the non-Newtonian behavior of fluid on the hydrodynamic properties of a three-phase (gas-liquid-solid) reactor under operating conditions of different values ​​of gas velocity (2, 4, 6) cm/sec, liquid velocity (0.9, 1.39, 1.8, 2.3) cm/sec, and recycle ratio (1.5, 2, 2.5). The study observed the effect of non-Newtonian behavior using polymethyl Cellulose (PMC) at different concentrations (0.1, 0.2, 0.3, and 0.4) wt%. The pressure gradient method was used to elucidate the minimum liquid fluidization velocity and to estimate hold up, while the imaging method was used to measure the bubble's size. The results showed that the higher the gas velocity, the lower the minimum liquid fluidization velocity. As the intensity of the non-Newtonian behavior increased, gas velocity showed the opposite effect. The results also showed that increasing the velocity of liquid and gas and the intensity of the non-Newtonian increase the gas hold-up. The bubbles characteristics, represented by bubble size results, show that small bubbles appear at low gas velocities, and these bubbles collapse as gas and liquid velocities increase as well as liquid viscosity.

Graphical Abstract

Highlights

• The effect of non-Newtonian behavior on minimum fluidization velocity, phase hold-up, and bubble diameter in such a reactor was investigated.
• The effect of gas and velocity and reflux ratio was considered.
• Increasing the gas velocity leads to a lower liquefaction velocity. It also decreases with the intensification of non-Newtonian behavior. An increase in the recycle ratio leads to a decrease in the minimum liquefaction velocity.
• The size of the bubbles increases with gas velocity and PMC concentration, while it decreases with the increase in the gas velocity and the recycle ratio.

• The increase in gas hold-up coincided with increased gas and liquid velocities and apparent viscosity.

Keywords

• Fluidization
• Ebullated bed reactor
• Non-Newtonian
• rheology
• empirical correlation

Main Subjects

• Chemical