Final - Spring 2013 - Petroleum Refining

8/17/2019 Final - Spring 2013 - Petroleum Refining

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CHEN 590

Petroleum Refining

Chemical Engineering

Faculty of Engineering and Architecture

American University of Beirut

Saturday, May 11th, 2013

9.00-11.00

Final Examination

This exam paper has 5 questions

Answer all questions

You have two hours to complete this exam

GOOD LUCK


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Q1. Are the following statement true (T) or false (F)?. (20 marks)

1.

Hydrocracking is a hydrogen addition process aims at upgrading heavy streams into

distillates.2.

Hydrocracking process in endothermic since it operates at high temperature.

3. hydrocracking is carried out in fixed bed reactors (in one or two stages) at 290-400°C under

high hydrogen pressure (70-140 bar) and using supported NiMo or CoMo catalysts able to

activate desulfurization.

4. Increasing environmental pressure on fuel quality is the main driver for the expansion and

improvement of hydrocracking technologies.

5.

Optimization of catalytic systems for getting higher selectivity to middle distillates and

higher efficiency in sulfur and nitrogen removal (HDS, HDN).

6.

Hydrotreating indicates a hydrogen treatment aimed at saturating olefins, reducing sulfurand nitrogen or other heteroatoms content, without modifying the distillation range of the

feed.

7. Hydrotreating catalysts are based on Cobalt-Molybdenum on alumina, or Nickel-

Molybdenum on alumina.

8. Co-Mo catalysts are the most largely used since they are very selective in HDN and poison

resistant.

9. In order to get ULS (ultra-low-sulfur) fuels (less than 10 ppm S) catalysts based on noble

metals (Pd, Pt, Re) are increasingly used for finishing.

10.

Main operating parameters in hydrotreating are reactor temperature, hydrogen partialpressure and space velocity.

11. Transformation of heavy feed with gravities < 20°API in distillates requires technologies

able to accept very high Concarbon, and concentration of metal and sulfur.

12.

Residues hydrocracking technologies are targeted to reduce the molecular weight (cracking

reactions) and improve the product quality by removing at the best sulfur, metals, nitrogen

(upgrading).

13. High quality gasoline can be obtained by reforming, isomerization and alkylation processes.

14. Reforming process converts linear paraffins and naphthenes into aromatics, high octane

components for gasoline (alternatively for petrochemical use).15. In catalytic reforming, feed needs desulfurization for limiting S poisoning and hydrogen

presence for limiting coke poisoning.

16.

Reforming is the main hydrogen source for all refinery hydrotreatments.

17. Side reactions (unwanted) in reforming include dealkylation and/or cracking of aromatics

and naphthenes with light paraffin formation (butane).


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18. Catalytic reforming is an endothermic process with interstage heating.

19. In Catalytic reforming, catalysts need coke regeneration and are accomplished in

continuous catalyst regeneration (CCR).

20. Paraffin isomerization is a slightly exothermic reaction favorite by low temperatures.

21.

Isomerization is commercially carried out in fixed bed reactors with a solid acid catalyst(noble metals on chlorinated Al2O3 or zeolites.

22. Alkylation is a reaction inverse to cracking.

23. HF & H2SO4 are traditional catalysts in alkylation that are strong and corrosive acids with

associated environmental problems.

24.

H2SO4 alkylation process needs a refrigeration cycle since it operates below ambient

temperature.

25. Solids catalysts can be potentially used in alkylation to overcome environmental and

corrosive issues related to acids.

26.

ETBE Etherification is the addition of an alcohol to a tertiary olefin, catalyzed by strongacid.

27. Blending properties of MTBE and ETBE are similar and better than any other oxygenate

and particularly lower volatility (which helps refiners to meet volatility specification limits).

28. One of the “Water Cooled Tubular Reactor ” features is having “Optimal temperature profile

for favoring kinetics and reduce the thermodynamic”.

29. Oxygenates assumed the new and important role of “clean air additives” and sealed the

success of MTBE as oxygenate of choice.

30. MTBE and ETBE can be obtained from renewable biomass sources.

Q2. Using a simple block flow diagram, show the different treatment, separation, conversion and

product quality upgrade processes of crude oil. Explain the concept of (H/C) adjustment (if any) in these

processes. (15 marks)

Q3. A hydrocracker feedstock has a boiling range of 650 to 920°F, an API gravity of 23.7°, and contains 1.7 wt%

sulfur. If the hydrocracking hydrogen consumption is 1500 scf/bbl of feed and the feed rate is 7500 BPSD,

determine:

a) Total hydrogen consumption; (7 Marks)

b)

Barrels of gasoline; (6 marks)c) Barrels of jet fuel produced per day. (7 marks)

LV% iC4 = 0.377 [LV% (C5-180°F)]

LV% nC4 = 0.186 [LV% (C5-180°F)]

wt% C3 and lighter = 1.0 + 0.09 [LV% (C5-180°F)]


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Q4. Explain the hydroprocessing of residue in terms of:

a. Objectives (2 marks)

b. Catalysts used (3 marks)

c. Reactors (hydrodynamics) used and the function of the guard reactor (10 marks)

d.

Processing conditions (5 marks)

Q5. Octanizing Technologies that include catalytic reforming, isomerization and alkylation aim at increasing

octane number of gasoline. Explain the three processes in terms of the reactions involved, catalysts used,

operating conditions and products. (25 marks)

End of Exam

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Final - Spring 2013 - Petroleum Refining