C2.2 oil refining

Question 1

Why use a hydroskimming refinery?

Answer 1

used for contamined HC with H2 –> pure HC + off gas
Produces H2S, NH3, H2O…

Question 2

What are the 3 steps of the hydroskimming refinery (after desalting the crude oils)?

Answer 2

1. atmospheric crude distillation
2. hydrotreatment
3. Catalyze reforming

Question 2

Explain what the hydrotreatment step is in a hydrocracking refinery

Answer 2

remove heteroatoms (O,N,S) by producing H2O, H2S, NH3
conversion using H2, reduces double bond –> single bond
equilibrium, exo, heterogeneous, catalytic reaction
protect the catalyst used in downstream process

Question 2

Explain the atmospheric crude distillation in a hydroskimming refinery (step1), what is the maximum T

Answer 2

T max = 620K or else thermal cracking and degradation of HC = coke

Seperation by boiling points

Question 3

What type of reactor is used for hydrotreatment and why?

Answer 3

Adiabatique PBR, because T rises in reactor

Question 4

What are the process conditions in hydrotreatment?

Answer 4

excess H2 will shift towards products
high T, high P

Question 5

Explain what the catalyze reforming purpose is in a hydrockraking refinery?

Answer 5

^ON of gasoline
rearrengement of HC structure + aromatics
major source of H2

Question 6

What is the product of hydroskimming refinery?

Answer 6

fuel for cars

Question 6

What are 3 different types of reforming that can be used in hydroskimming?

Answer 6

1. isomerization
2. cyclisation
3. aromatization

Question 6

what catalyst can be used in catalyze reforming

Answer 6

Pt, Al2O3
*Sulfur deactivates Pt = needs hydrotreating

Question 7

Why do we need multiple PBR w/ intermediate cooling, what are the 2 different options?

Answer 7

Because the undesired reactions will occur if T too high

quench reactors or heat exchanger reactors (x3)

Question 8

For a cat rxn in adiab PBR, with increasing T:

which reactor to chose for irrev + endo

Answer 8

PBR with intermediate cooling
if V cte, X smaller –> need increasing V

Question 9

For a cat rxn in adiab PBR, with increasing T:

Reversible + endothermic

Answer 9

Design with highest T as possible

Question 10

For a cat rxn in adiab PBR, with increasing T:

Irreversible + exo

Answer 10

3-4 reactors
X is higher with more reactors
If V cte steps get smaller

Question 11

For a cat rxn in adiab PBR, with increasing T:

reversible + exo

Answer 11

Want a lower T
kinetics will push for higher T

Question 12

What is the optimal T profile for a cat + exo in PBR+ adiab?

Answer 12

rxn to max rate
smaller reactor V = less cat = less $ spent
exo rxn = lower T favoured

Question 13

What are the 3 main steps of a cracking refinery?

Answer 13

1. Vacuum distillation
2. Catlytic cracking
3. hydro-cracking

Question 14

What is the difference with a cracking refinery?

Answer 14

extra vacuum distillation + catalytical cracking

Question 15

Explain the vacuum fractionator/distillation, how does it work?

Answer 15

Low P = lower T boiling = limits coke formation = allows high-boiling-point fractions to be distilled without thermal cracking

used to separate heavier hydrocarbons

Question 16

what happens in the disengagement zones of a vacuum fractionator?

Answer 16

it enhences seperation

Question 17

Why use downcomers in vacuum fractionator?

Answer 17

controls liquid flow, pressure, efficicency…

Question 18

What is a problem in vacum fractionators?

Answer 18

high vapor loads

Question 19

What is a high vapor load, what is the impact

Answer 19

velocity of vapour ^= flooding = lowers engagement zones = lowers efficicency of distillation

Question 20

What is the formula to describe vapor loads

Answer 20

Q_v = V_v * A

Question 21

***What is the solution to high vapor loads? --> check developement fait en classe

Answer 21

higher A (higher diameter) or packed columns lower P : ^Q_v, higher A = ^Vv if Vv too high, vapour entrains liquid

Question 22

What is the FCC technology/ wha is its purpose?

Answer 22

fluidized bed technology = make lighter compounds like gasoline

Question 23

What are 3 cons of FCC?

Answer 23

1.endothermic --> needs energy for cracking + 2.coke formation due to cracking 3. Pollution : emission, poluted waste water, errosion, water + S

Question 24

What are the operation conditions of FCC?

Answer 24

T = 775 k P = 1 bar

Question 25

What does coke do?

Answer 25

deactivates catalyst

Question 26

what is a solution to coke formation?

Answer 26

use a PFR regenerator for spent catlyst to decoke (burn it off) --> 2 stage cyclone

Question 27

What T for coke burning?

Answer 27

T = 970K

Question 28

What does compexity and flexibility depend on? Is it on the crude oils?

Answer 28

No it depends on the number of unit operations

Question 29

Name 2 limits of the catalyst used in FCC?

Answer 29

very sensitive to coke formation pores size = heavy components don't have access to active sites

Question 30

Explain the working principle of FCC

Answer 30

1. Particles with coke = heavy = accumulate at the bottom of the reactor = sent to regenerator 2. Burn of the coke = reactivate catalyst or combustion = catalyst particles are heated = energy carrier = cracking reaction works

Question 31

Why use a cyclone in cracking refinery?

Answer 31

entrained particles removal

Question 32

What is a coking refinery for

Answer 32

thermal process + heavy optimize HC ratio Includes a coker unit—a process designed to handle very heavy crude fractions and convert them into lighter, more valuable products.

Question 33

Do the hydrocracker and FCC work as a team

Answer 33

FCC takes the more easily cracked, alkane-rich atm and vacuum gas oil Hydrocracker: process the aromatic feed and heavier gas oil due to the cage size of

Question 34

What is a zeolite?

Answer 34

microporous mineral, ion-exchange adsorption and catalysis --> is a catalyst

Question 35

What are 2 ways to upgrade the bottom of barrel (BoB)

Answer 35

visebreaking delayed coking

Question 36

What is vice-breaking

Answer 36

non-cat, thermal process conversion by heating to ^T (500°C) t = 1-8 min main product = cracked residue = lower viscocity than vacuum residu

Question 37

Delayed coking

Answer 37

Cracking in furnace - transfer line - coke drums more severe conditions = higher T, t = 24hrs (avoid coke) coked form : introduce heated feed to coke drum --> rxn removal of coke = high P water jets

Question 38

What is the purpose of the alkylation process

Answer 38

^ON works towards performance

Question 39

Cat used for alkylation process

Answer 39

H2SO4

Question 40

What reaction is happening in alkylation process

Answer 40

rxn of alkenes with iso-butane = branched alkanes = ^ON

Question 41

Conditions of alkylation

Answer 41

exo equilibrium low T t = 20-30 min excess iso-butane -->

Question 42

Do you stirr in every compartment ?

Answer 42

all but the last

Question 43

What is the Claus process used for?

Answer 43

treatment of H2S

Question 44

Explain the Claus process

Answer 44

H2S obtained by absorption of off-gas from hydrotreating 95% transformed S removed by conditioning after each reactor

Question 45

What are the 3 steps of Claus Process

Answer 45

conditionning (x4) --> reheater (x3)--> Claus reactor (x3)