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A cfd study comparing different feed nozzle arrangement within an empty spray section in a coker fractionator

INTRODUCTION
  • Coker Fractionator is the main equipment in a Delayed Coking Unit
  • It receives the effluent from the Coke Drums and separates them into distillates
  • Products specifications are achieved in coker fractionators and the interest in this subject has increased lately
OBJECTIVE

To predict the fluid dynamic behavior in a coker fractionator washing zone and analyze the influence of vapor distribution on the heat and mass transfer efficiency, considering different number of inlet feed nozzles

MODEL SET-UP – SIMULATION CASES
  Phase Inlet characteristics Spray section
Case 1 vapor one inlet none
two inlets
three inlets
Case 2

vapor-liquid

ideal 30º
45º
MODELING APPROACH
  • Eulerian-Lagrangian approach
    1. Continuous phase: vapor (Eulerian)
    2. Dispersed phase: liquid droplets distribution (Lagrangian)
  • Takes into account the influence of the liquid flow within the vapor phase flow
    1. Allows to predict the spray distributor arrangement and geometry improvement cities
CUSTOMER

Petrobras - Brazil

CONCLUSIONS

Case 1: Number of inlet feed devices

  • Coker fractionator tower simulation can change the number of inlet feed device among one, two or three inlets
  • CFD results indicated that two inlets feed device provides the highest homogeneity of vapor under normal operational conditions of all cases studied


Case 2: Spray section configuration

  • Ideal vapor condition was set to optimize a hollow cone spray distributor by rotating the base distributor in 30 and 45 degrees
  • CFD results indicated that no great difference has been observed between the analyzed conditions, but 30 degrees provides higher liquid-vapor distribution within the washing zone