Assistance Technique Case 3 – Increasing hydrogen

partial pressure- Case 3a – Diesel hydrotreater

increase H2/oil ratio?

purify hydrogen?

change liquid feed?

decrease pressure drop?

-Case 3b – Naphtha hydrotreater

increase H2/oil ratio?

purify hydrogen?

change liquid feed?

decrease pressure drop?

   

Assistance Technique Case 4 – Pressure Drop

-Situation 1 – Poor catalyst loading or poor start-up procedures

-Situation 2 – Internals, catalyst strength or corrosion impurities coming into the catalyst bed

   

0

2

4

6

8

10

12

14

16

0 5 10 15 20 25

Pre

ssu

re d

rop

situation 1situation 2situation 4situation 3

Assistance Technique Case 4 – Pressure Drop

Possible causes for pressure drop

- Reactor - coking, polymerization, particles (FeS),

catalyst loading, maldistribution, metal

poisons

- Exchangers - salts deposition, coking, polymerization,

particles deposits

0

1

2

3

4

5

6

06/11/01 26/11/01 16/12/01 05/01/02 25/01/02 14/02/02 06/03/02

Be

d 2

pre

ss

ure

dro

p (

ba

r)

Assistance Technique Case 4 – Pressure Drop

HR-448 1.2 mm DENSE LOAD

3/4" inert balls

1/4" inert balls

3/4" inert balls

3/4" inert ballsACT 065 - 12 mm

1/4" inert balls

ACT 075 - 6 mm

HMC 841 - 3 mm

Reasons for this high

pressure drop build-up??

Reasons for the higher

pressure drop in the

second bed??

Assistance Technique Case 4 – Pressure Drop

Assistance Technique Case 4 – Pressure Drop

Catalyst grading bed – trickle bed reactors

Assistance Technique Case 4 – Pressure Drop

Scale baskets – Gas phase bed reactors

Scale baskets are needed in order to provide longer resistance to

pressure drop build up.

The role of the basket is not intended to retain the fines which should

be trapped on the top layer of inert balls, but to act as a fuse in case of

pressure build up

They should remain clean

Inert balls3/4"

Inert balls3/4"

Catalyst bed

Vapors + fines

Vapors free of finesFines accumulation

Assistance Technique Case 4 – Pressure Drop

Pressure drop must be corrected for process conditions,

as gas and liquid flowrates for example

0

1

2

3

4

5

6

01/09/02 31/10/02 30/12/02 28/02/03 29/04/03 28/06/03 27/08/03 26/10/03 25/12/03

Pre

ssu

re d

rop

(b

ar)

Delta P measured

Delta P predicted

Assistance Technique

Case 4 – Pressure DropFeed + H2

Desulphurized product+ H2 + H2

After start-up a very high pressure dropWas observed across the reactor

Assistance Technique

Case 5 – Hydrogenation Activity

S

+ 2H2 + 2H2S

+ 2H2

Assistance Technique

Case 5 – Hydrogenation Activity

Température (°C)

% H

DA

So

ufr

e ef

flu

ent

(pp

m)

T1 T2

HDS

Régime thermodynamique(HDA)

Régime cinétique(HDA)

Equilibre thermodynamiqueHDA

Assistance Technique

quench

quench (0 t/h)

fou

r

lit 1

lit 2

lit 3

0

R1

0

R2

0

R1

0

R2

Opération normaleDiminution de la température

dans le dernier lit

R1

R2

température température

Case 5 – Hydrogenation Activity

Assistance Technique

Case 6 – Unit Shut-Down

In the race of increasing severity in sulphur specifications - NZSD, optimising the unit shut-down and scheduling it as a non routine event is as important for the overall unit

performance as a Formula 1 pit stop can be to wining

reactor cool down

catalyst unloading

catalyst loading

distribution tray removal(mechanical details)

catalyst drying

reactor inspectionunder air atmosphere

regenerated catalyst pool

catalyst activation method

Dedicated flow-bins - FUTURE

Assistance Technique

Case 6 – Unit Shut-Down

reactor

Pre-heat exchangers

Furnacemaxicold

HP separator

By pass to be openedat 150°C

Co

mp

ressor

stripper

dryer

LP separator

GO to storage

Cooling loop for hydrotreatment units

Gasoil cooling loop

Air coolers

Air coolers

To LPseparator

From HPseparator

stripper Pre-heatexchangers

Normal operating circuit