FLUID CATALYTIC CRACKING

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FLUID CATALYTIC CRACKING
-SUSHMIT GOYAL (CH05B044) -SANTOSH
KUMAR (CH05B035) -ANAND RENGARAJAN
(CH05B003)
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THE GENERAL PROCESS

• FEED (GAS OIL) IS HEATED
• BROUGHT IN CONTACT WITH CATALYST
• FLUIDIZATION
• BUBBLE,PARTICULATE, SLUG AND TURBULENT
• CRACKING
• POISONING OF CATALYST

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THE GENERAL PROCESS(CONT)

• SEPERATION
• CYCLONES-EFFICIENCY 99.995
• REGENERATION
• REINTRODUCTION IN THE REACTOR
• FLUE GAS

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OUR FOCUS FOR THIS PRESENTATION

• CHALLENGES
• CATALYST ROLE
• MODELING AND SIMULATION

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CHALLENGES AND USE OF ENGINEERING

• THERMAL CRACKING
• NON UNIFORM
• USE OF INJECTOR
• USE OF BAFFLES
• BUT NO THEORY,ALL IS EMPERICAL

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ZEOLITE

• TETRAHEDRAL GEOMETRY
• CONTAINS VACANT SITES(PORES)
• PREFERENTIAL CRACKING
• ZEOLITE TYPES

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OPTIMIZATION!
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MODELLINGLMPA IMPREGNATION OF CATALYST
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MODELLING(CONT)

• PARTICLES DIFFER IN PROPERTIES
• NEED FOR AVERAGE PROPERTIES
• SO A PROPOSED CONCEPT
• STAGED CRACKING

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STAGED CRACKING

• PORES INTERIOR
• TO EXTERIOR
• SIZE OF PORES VARY
• ACHIEVES BETTER
• CRACKING

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Freely bubbling bed of FCC catalyst and Simulation

• Four regimes of fluidization Particulate,
  Bubbling, Slugs, Turbulent.
• FCC units use a dense, moving fluidized bed
  operating in either the bubbling or turbulent
  regime.
• Computational Fluid Dynamics (CFD) for
  understanding fluidization hydrodynamics.
• Reason for model failure use of mean bubble and
  emulsion properties.
• Bubble sizes and velocities exhibit a
  distribution about the mean value, affecting the
  predicted hydrodynamics.

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Bubble splitting and Coalescence

• Four groups of particles Geldart A particles
  (fine) and Geldart B particles (coarse), Geldart
  C, Geldart D.
• Bubble splitting and coalescence important
  phenomenon associated with Geldart A bubbling
  beds.
• Factors gravity and drag are the dominant
  terms, the solids phase stress predicted by
  kinetic theory play a minor role.
• Poor simulation results Cohesive interparticle
  forces neglected.

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• ECT (Electrical capacitance tomography) is used
  to obtain dynamic tomographic images of the
  entire cross-section of the fluidized bed.

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Challenges in understanding bubbling fluidization

• Cohesive forces important for FCC fluidization.
• Challenges implementing realistic equations to
  represent these forces. But the calculation of
  Van der Waals forces is at present very
  approximate.
• Discrete element method (DEM) uses individual
  particle tracking. A Multiple of the single
  particle buoyant weight to calculate cohesive
  forces.
• Problems with DEM computational requirements is
  proportional to the number of particles !!!

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BIBLOGRAPHY

• FCC HANDBOOK
• - REZA SADEGHBEIGI
• CATALYST TODAY 18(1993) 509-528
• -R MANN
• POWDER TECHNOLOGY 163(2006) 2-8
• YE-MON CHEN
• POWDER TECHNOLOGY 129(2003) 139-152
• TIM MCKEEN AND TOD PUGSLEY
• OTHER INTERNET RESOURCES