Modeling of vaporization and cracking of liquid oil injected in a gas-solid riser

Subramanya V. Nayak, Saket L. Joshi, Vivek V. Ranade*

*Corresponding author for this work

Research output: Contribution to journalArticle

76 Citations (Scopus)

Abstract

Vaporization and cracking of liquid oil injected in a gas-solid riser (fluid catalytic cracking riser reactor) was computationally studied in this work. Evaporation of a single drop injected in a stream of gas-solid mixture was analyzed first. A model for simulating evaporation of a drop considering heat transfer from the gas phase as well as from the solid particles was developed. The model relates the evaporation rate of droplet with rate of collisions of solid particles, specific heat capacities of solid and liquid, latent heat of vaporization, relative velocity of gas and liquid and temperatures of three phases. The understanding gained from such a model was then extended to simulate evaporation of liquid drops injected in FCC risers. The Eulerian-Lagrangian approach was used to simulate simultaneous evaporation and cracking reactions occurring in FCC riser reactors. A commercial CFD code, FLUENT (of Fluent Inc., USA) was used. Four and ten lump models were used for simulating cracking reactions. Appropriate user defined functions were developed to implement heterogeneous kinetics and heat transfer models in FLUENT. A special algorithm was developed to calculate accumulated coke on catalyst particles. A boiling point range was considered for simulating realistic oil feedstock. The model was first evaluated by comparing predicted results with published industrial data. The simulations were then carried out to understand influence of key design and operating parameters on performance of FCC riser reactors. The parameters studied included; initial oil droplet distribution, catalyst inlet temperature, catalyst to oil ratio and thermal cracking. The approach, model and results presented here would be useful for optimization of FCC operation, cost to benefit analysis of new FCC nozzles and related decision-making.

Original languageEnglish
Pages (from-to)6049-6066
Number of pages18
JournalChemical Engineering Science
Volume60
Issue number22
DOIs
Publication statusPublished - Nov 2005
Externally publishedYes

Keywords

  • Cracking reactions
  • Evaporation
  • FCC
  • Heat transfer
  • Riser

ASJC Scopus subject areas

  • Chemical Engineering(all)

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