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1. CE4102
Petrochemical Processes
Learning Outcomes:
1. Cracking Reaction Principles
2. Operating Variables on Steam Cracking
3. Cracking Furnace
2
Lecture 3
OLEFINS PRODUCTION Part 2: Steam Cracking

2. 3
OPERATING VARIABLES

3. Petrochemical Processes 31
Important Definition in Cracking

4. Petrochemical Processes 32
Important Definition in Cracking

5. Petrochemical Processes 33
OPERATING VARIABLES affecting Pyrolysis YIELD
1
2
3
4
5

6. Petrochemical Processes 34
Parameter: Effect of Feedstock Composition

7. Petrochemical Processes 35
Parameter: Effect of Feedstock Composition
What is the YIELD?

8. Petrochemical Processes 36
Parameter: HC Flow on Yield

9. Petrochemical Processes 37
Parameter: Effect of Reaction Severity
Conversion
use in gas cracker. Ethylene conversion 60-70%
Severity (P/E)
use in naptha cracker.
P/E = 0.45 corresponds with 8500C
P/E = 0.6 corresponds with 8100C

10. Petrochemical Processes 38
Parameter: Effect of Reaction Severity

11. Petrochemical Processes 39
Parameter: Effect of XOT on Yield
XOT [=] Crossover TEMPT
Crossover temperature is the
temperature coming out of the
convection and going into the
radiant.

12. Petrochemical Processes 40
Parameter: Effect of Residence Time
Residence Time
time on molecule in the cracking coil, typically fraction of a second

13. Petrochemical Processes 41
Parameter: Effect of Primary & Secondary Rxn

14. 42
Parameter: Effect of Primary & Secondary Rxn (cont'd)
Petrochemical Processes

15. Petrochemical Processes 43
Parameter: Effect HC Partial Pressure

16. Petrochemical Processes 44
Parameter: COP (coil outlet pressure)

17. Petrochemical Processes 45
Parameter: HC to Steam Ratio
CE4102 Petrochemical Processes

18. 46
Parameter: HC to Steam Ratio
DRAWBACKS
Petrochemical Processes

19. 47
Parameter: HC to Steam Ratio on Yield
Petrochemical Processes

20. Petrochemical Processes 48
Summary

21. Petrochemical Processes 49
Co-cracking

22. Petrochemical Processes 50
Split-Cracking

23. 51
FURNACE

24. Furnace
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Petrochemical Processes

25. Furnace
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Petrochemical Processes
TASK of a FURNACE

26. Furnace
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Petrochemical Processes

27. Furnace
Heat
Balance
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Petrochemical Processes

28. Burners
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Petrochemical Processes

29. The Reactor = Coil/Tube
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Petrochemical Processes
The basic consideration to design the tubes essentially deal with the determination of the following characteristics:
▪ Heat exchange area required: calculated from the feasible heat fluxes and energy needs of the system
▪ Severity of the operation
▪ Residence time, determination from the mass flow rate of the reaction mixture and its average specific weight in the
tube.
▪ The quantity of heat to be transferred to raise the temperature and compensate for the endothermic character of
the pyrolysis reactions, based on the thermodynamic properties.
▪ The heat flux that can be achieved across the tube wall
▪ Pressure drop form the length and diameter of the tube selected
▪ Rate of coke formation on the inside wall of the pyrolysis tube, which alters the overall heat transfer coeff.

30. The Reactor = Coil/Tube
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Petrochemical Processes
dz
Fz Fz+dz
R
In – Out – Reaction – Accumulation = 0
Mass balance:
Accumulation = 0
dF
dz
=−R.A
Reaction = R.dV = R.A.dz
In = Fz
Out = Fz+dz
MASS BALANCE OF TUBULAR REACTOR

31. The Reactor = Coil/Tube
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Petrochemical Processes
ENERGY BALANCE OF TUBULAR REACTOR
dz
R
Q
In – Out – Reaction – Accumulation = 0
Energy balance:
Accumulation = F.cp.dT
q = heat flux
ω = circumference of the tube
Ω = cross section of the tube
ΔH = heat of reaction
Cp = heat capacity
F.cp.
dT
dz
=q.ω+R.ΔH.Ω
In = q.ω.dz
Out = 0
Reaction = -R.ΔH.Ω.dz

32. The Reactor = Coil/Tube
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Petrochemical Processes

33. The Reactor = Coil/Tube
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34. PyroCrackTM
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Petrochemical Processes

35. PyroCrackTM
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36. The Reactor = Coil/Tube
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37. Furnace
65
https://www.youtube.com/watch?v=rjo6ZVmUVZc
Petrochemical Processes

38. 66
COKING

39. Coke
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Petrochemical Processes

40. Coking
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41. Coking
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42. Process Trip due to Coking
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43. Coking Prevention
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44. “End-of-Run”Criteria
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45. Decoking
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46. Decoking
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47. Learning Outcomes Check!
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Learning Outcomes:
1. Cracking Reaction Principles
2. Operating Variables on Steam Cracking
3. Cracking Furnace

48. Thank You.