3 research outputs found
Numerical Simulation of the Flue Gas and Process Side of Coking Furnaces
A numerical simulation for the flue gas and process sides
of a
coking furnace with floor gas burners was conducted. The computational
fluid dynamics (CFD) approach was employed to simulate flow, combustion,
and heat transfer in the furnace. The process-side conditions were
calculated with a special program. The simulation provides detailed
information about the flue gas velocity, temperature fields, and process
conditions for this type of coking furnace. Good agreement is obtained
between industrial measurement and simulated excess air coefficient,
outlet temperature of flue gas, and outlet pressure on the process
side. Moreover, the simulated results indicate that there are hot
spots on the tubes, located at the height of 1.5–2.5 m. That
is consistent with the actual phenomenon of industrial coking furnaces.
To investigate the effect of furnace structure on physical field distribution
and process-side conditions, a comparative simulation case with more
wide spacing of burners to walls was conducted. Results indicate that
the comparative case improves the uniformity of heat flux distribution,
obviously, which is beneficial for the run length of coking furnaces
Practical Model for the Induction Period of Heavy Oil during Thermal Reaction
The
induction period is a significant concept for design and operation
of the delayed coking process. To simplify the prediction of the induction
period and make it applicable to operational analysis and real-time
control of the thermal cracking process, a practical model for the
induction period of heavy oil during thermal reaction, which is suitable
for the non-isothermal reaction in the industrial conditions, was
presented. The development of this model was based on the experimental
data of five heavy oils. The model parameters were correlated with
microcarbon residue (MCR) of heavy oil to improve the model universality.
Furthermore, the validity of correlation between MCR and cracking
kinetic parameters was proven. The model-predicted cracking conversion
agrees well with the experimental values. The induction period model
was employed to predict the induction period of two feedstocks reported
in the literature. Results indicated that the induction period model
is available for the thermal reaction of these heavy oils
Kinetic Model for the Deep-Severity Thermal Reaction in the Coke Drum of Delayed Coking
The
coke drum is the main reactor of the delayed coking process, in which
the deep-severity thermal reaction of heavy oil takes place. To simulate
the product distribution in this reactor, a kinetic model for the
deep-severity thermal reaction was developed on the basis of the experimental
data of a vacuum residuum in a microbatch reactor at 430–490
°C. The model-predicted results agree well with the experimental
values. The ratio of the cracking gas/light distillate rate constant
increases with the reaction temperature. Both the primary condensation/cracking
rate constant and the secondary condensation/cracking rate constant
increase with the reaction temperature. It means that the lower reaction
temperature is advantageous to increase the distillate yield at the
same reaction severity. Furthermore, a practical transformation method
was presented to improve the suitability of this model. The comparison
results indicated that this transformation method is available for
the kinetic model in this research. Moreover, it can also be used
for other lumping models similarly