Introduction to Processes for the conversion of heavy feed Flashcards

1
Q

Which cuts are send to conversion units ?

A
  • Atmospheric residues (if no vacuum column)
  • VGOs
  • Vacuum residue
  • Deasphalted oil (DAO)
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2
Q

Where does DAO come from ?

A

DAO is vacuum residue after deasphalting unit

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3
Q

What is the goal of the deasphalting unit ?

A

The goal is to concentrate the impurities of the vacuum residue in the asphlalt

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4
Q

What is a comon deasphalting solvent ?

A

Light HC (butane or pentane) to extract mostly saturated components and aromatics but not resins and asphlatene

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5
Q

What does SARA stand for ?

A

Saturated Aromatics Resins Asphaltenes

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6
Q

What is SARA ?

A

SARA is an analytical method to recognize famlily of molecules and separate the families using specific solvents

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7
Q

How do we measure the capacity of a cut to generate coke in conversion operations ?

A

We use Condrason carbon in %wt

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8
Q

Why is DAO interesting compared to vacuum residue ?

A

Low asphaltene and metal content

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9
Q

What are the tools for the different cracking techniques ?

A
  • Thermal cracking -> T + residence time
  • Catalytic cracking -> T + catalyst
  • Catalytic hydrocracking -> T + catalyst + H2
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10
Q

What is the difference between Visbreaking and Coker ?

A

In visbreaking we want a moderate thermal cracking to limit coking whereas in a coker we want intensive cracking which leads to coke formation

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11
Q

What family of product is found in thermal and catalytic cracking but not HCK ?

A

Olefins

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12
Q

Are cracking reactions endoT or exoT?

A

EndoT

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13
Q

What is the advantage of thermal cracking over catalytic cracking and hydrocracking ?

A

No catalyst so we don’t care about metal content

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14
Q

What is the selectivity and quality of thermal cracking processes ?

A

Low selectivity and quality (rich in olefins and diolefins)

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15
Q

What is the maximum conversion in a visbreaker ?

A

Max 40 %

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16
Q

What is the state of the catalyst in a catalytic cracking unit ?

A

The catalyst is used as a fine powder ciruclating in a fluidized state

17
Q

What are the advantages of using a catalyst ?

A
  • More selectivity

- Better quality products (only olefins)

18
Q

What is the proble of using a catalyst ?

A

To avoid poisoning the catalyst, we need feed with low metal content (< 20 ppm wt)

19
Q

What is the usual gasoline yield of a FCC ?

A

40 to 50 %

20
Q

What are the advantages of HCK ?

A
  • High selectivity

- No coke because no cracking of aromatics

21
Q

What are the problems with HCK ?

A
  • High H2 consumption

- Catalyst requiring high purity feed