Differences between commercial reforming processes ......Naphtha Catalytic Reforming Semi-regenerative Process 26 A slight modification to the semi-regenerative process is to add an

PROFESSIONAL COURSE IN ENGLISH

“FUNDAMENTALS OF PETROLEUM REFINING”

Unit 8. Naphtha Catalytic Reforming

Catalytic Reforming Processes

17

Differences between commercial

reforming processes

Catalyst regeneration procedure

Catalyst type

Conformation of the equipment




Process classification

18

This classification is based on the frequency and mode of

regeneration.




Naphtha Reforming Processes

19

Table 1. Summary of Naphtha Reforming Processes




Semi-regenerative Process

20Figure 5. Semi-regenerative (SR) fixed bed reforming process





21

The name semi-regenerative comes from

regeneration of the catalyst in the fixed bed

reactors after shut down by burning off the

carbon formed on the catalyst surface.

Reactions such as dehydrogenation of

paraffins and naphthenes which are very

rapid and highly endothermic occur in the

first reactor, with high temperature drop.





22

Reactions that are considered rapid, such as

paraffin isomerization and naphthens

dehydroisomerization, give moderate

temperature decline in the second reactor.

Furthermore, slow reactions such as

dehydrocyclization and hydrocracking give

low temperature decline in the third reactor.





23

The temperature and

concentration profile

in each reactor.

Figure 6.

(A) Furnace and reactor layout for fixed

bed reformer

(B) Variation of temperature in the

reactors

(C) Variation in effluent compositions;

Po is initial paraffins

No is initial napthenes

Ao is intial aromatics





24

To prevent catalyst coking, the hydrogen

partial pressure is maintained at a level such

that the hydrogen-to-hydrocarbon ratio by

weight (H2/HC) is 4-6.

This is done by recycling some of the

hydrogen produced.





25

Some light hydrocarbons (C1–C4) are separated

from the reformate in the stabilizer.

At the top of the stabilizer residual hydrogen and

C1 to C4 are withdrawn as condenser products,

which are then sent to gas processing, and part

of the liquid product (C3 and C4) is returned from

the reflux drum back to the stabilizer.

The main product of the column is stabilized

reformate, which is sent to the gasoline

blending plant.





26

A slight modification to the semi-regenerative

process is to add an extra-reactor to avoid

shutting down the whole unit during

regeneration.

Three reactors can be running while the forth

is being regenerated.

This modified process is called the ‘‘cyclic

fixed bed’’ process.




Continuous Regenerative (moving bed) Process

27Figure 7. Continuous regenerative reformer (CCR), UOP Platforming process





28

The effluent from each reactor is sent to a

common furnace for heating.

The catalyst moves downwards by gravity

from the first reactor (R1) to the forth reactor

(R4).

The catalyst is sent to the regenerator to

burn off the coke and then sent back to the

first reactor R1.

The final product from R4 is sent to the

stabilizer and gas recovery section.





29

The process can be operated at lower

hydrogen partial pressure (PH2 = 3 bar)

compared to the semi-generative process

(PH2 = 35 bar), with a reformate yield gain of

nearly 10 vol %.




Catalytic Reforming Processes

30

Table 2. Typical operating conditions of three reforming processes

re




Comprehension questions

1. What is the role of the reformer in the refinery?

2. What groups of hydrocarbons have the highest octane

numbers?

3. What groups of hydrocarbons have the lowest octane

numbers?

4. How does the number of carbon atoms in the chain of

molecule influence the octane number of paraffins, iso-

paraffins, naphthenes / aromatics?

5. List the types of reforming reactions and show their

relative importance.

31





32

6. List the types of reforming reactions and show their

relative importance.

7. What two types of coke form in the catalytic reforming?

8. Why the feed of catalytic reforming is heated before

entering the reactors?

9. List the promoters for reforming catalyst which are

added to improve properties of the catalyst.

10.List the impurities for the reforming catalyst.





33

12.What are the main pieces of equipment in the reforming

process?

13.What modes of reforming process operation exist

according to the catalyst regeneration procedure?

14.What types of catalyst bed do you know?

15.What reforming reactions occur in the first, second and

last reactor?

16. In your opinion, will the reforming play the same role of

the major process for gasoline components production

in the future?

Documents

Differences between commercial reforming processes ......Naphtha Catalytic Reforming Semi-regenerative Process 26 A slight modification to the semi-regenerative process is to add an