(601b) Optimal Investigation on Heat Transfer and Hydrodynamics in a Gas-Solid Fluidized Bed with Vertical Immersed Internals

Optimal
investigation on heat transfer and hydrodynamics in a gas-solid
fluidized bed with vertical immersed internals

Jiantao Li, Lu Liu,
Xiuying Yao*, Chunxi Lu*

The
State Key Laboratory of Heavy Oil Processing, Faculty of Chemical Engineering,
China University of Petroleum Beijing, Changping, Beijing 102249, People's
Republic of China

*Corresponding
author. E-mail: lcx725@sina.com

Gas-solid
fluidized beds have been widely used in both the
chemical reaction and the physical operation process for their excellent gas-solid
contacting and relatively uniform temperature profiles within the beds. For
example, external catalyst coolers have been widely used in the fluid catalytic
cracking (FCC) for decades in order to remove extra heat. Essentially, the
cooler is a fluidized bed with a number of vertical heat tubes. However,
it meets various problems during service, such as low heat transfer efficiency
and poor fluidization of particles. Therefore, a big cold model experimental
device was set up to study heat transfer and hydrodynamics in coolers. The
influence of operating conditions on flow characteristics of particles and heat
transfer efficiency between heat transfer surface and fluidized particles were
determined. Moreover, the empirical correlations for the heat transfer
coefficient between particles and heat transfer surface are obtained. Besides,
for the purpose of optimizing the heat transfer performance of coolers and the
flow performance of particles, a series of specially designed baffles were
installed in the bed. The results show that the radial velocity and residence
time in the coolers of particles were increased because of the inclined
installation of baffles. The diameter of the bubbles in
the bed decreases and the turbulence of particles become intense. The heat
transfer coefficient is increased by 30%.

Keywords:
gas-solid fluidized bed; heat transfer; hydrodynamics; baffles;

Fig.1 h under different operating
conditions

Fig.2
A
comparison of the instantaneous solid volume fraction by the instantaneous h

Fig.3
The deviation between the calculated Nu and the experimental Nu

Fig.4
Optimization
effect of baffles on h