Post on 15-Jan-2016
description
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