Refining and Troubleshooting Hydrotreatment Units · PDF fileAssistance Technique Refining and Troubleshooting Hydrotreatment Units Ano lectivo 2005/2006 Pedro da Silva

Assistance Technique

Refining and Troubleshooting

Hydrotreatment Units

Ano lectivo 2005/2006

Pedro da Silva

Assistance Technique TOTAL : First Refiner in Europe

CANARIESCANARIES

Milford Haven

Flandres

Normandie

Grandpuits Donges

Feyzin

Provence

LOR

Flessingues

Brunsbuttel

Schwedt

Leuna

Reichstett

Dunkerque

Anvers

RomeTarragona (Cepsa)

Algesiras (Cepsa)

Huelva (Cepsa)

Teneriffa (Cepsa)

(100% ; 229)

(40%)

(100% ; 351)(100%)

(55% ; 158)

(16.7% ; 222)

(100% ; 227)

(18%; 86)

(57.5% ; 92)

(50%)

(100% ; 215)(100% ; 88)

(100% ; 100)

(100% ; 164)

(100%; 121)

(100% ; 238)

(100% ; 354)

(100% ; 165)

(70% ; 108)

(100%; 100)

TOTAL opérateurParticipation < ou = à 50%

Raffinerie avec :- Participations en %

- Capacités de brut en Kb/j

Cepsa =Total actionnaire à 45,3%

Hubs de raffinage

03-10-2.3

CANARIESCANARIESCANARIESCANARIES

Milford Haven

Flandres

Normandie

Grandpuits Donges

Feyzin

Provence

LOR

Flessingues

Brunsbuttel

Schwedt

Leuna

Reichstett

Dunkerque

Anvers

RomeTarragona (Cepsa)

Algesiras (Cepsa)

Huelva (Cepsa)

Teneriffa (Cepsa)

(100% ; 229)

(40%)

(100% ; 351)(100%)

(55% ; 158)

(16.7% ; 222)

(100% ; 227)

(18%; 86)

(57.5% ; 92)

(50%)

(100% ; 215)(100% ; 88)

(100% ; 100)

(100% ; 164)

(100%; 121)

(100% ; 238)

(100% ; 354)

(100% ; 165)

(70% ; 108)

(100%; 100)

(100% ; 229)

(40%)

(100% ; 351)(100%)

(55% ; 158)

(16.7% ; 222)

(100% ; 227)

(18%; 86)

(57.5% ; 92)

(50%)

(100% ; 215)(100% ; 88)

(100% ; 100)

(100% ; 164)

(100%; 121)

(100% ; 238)

(100% ; 354)

(100% ; 165)

(70% ; 108)

(100%; 100)





Hubs de raffinage









Hubs de raffinage

03-10-2.3


« Ce n’est pas la plus forte des espèces qui survit ni la plus intelligente ; c’est celle qui

est la plus apte au changement »

Charles Darwin

Assistance Technique Refining Scheme


Simplified Scheme of Refining Process


Typical Scheme of Atmospheric Distillation

Assistance Technique Scheme of a Simple Refinery

Atm

osph

eric

Dis

tilla

tion

Crude

Heavy fuel

Reforming

propanebutane

gasoline

naphtha

Hydrodesulphurisationkerosene

diesel

H2

Amine wash

HDT


Typical Scheme of a Semi-Regenerative Reforming Unit

Production of high octane gasoline and of hydrogen


Atm

osph

eric

Dis

tilla

tion

Heavy fuel

Crude

Scheme of a Complex Refinery

Reforming

propanebutane

gasoline

naphtha


diesel

H2

Amine wash

HDT

Assistance Technique Typical Scheme of FCC Unit


Atm

osph

eric

Dis

tilla

tion

Heavy fuel

Crude

Vacu

um D

istil

latio

n

CatalyticCracker

FCC

Visbreaking

Scheme of a Complex Refinery

Reforming

propanebutane

gasoline

naphtha


diesel

H2

Amine wash

HDT


Gasoline and Diesel sulphur specifications

CO, NOx, HC, Particulates

BEFORE

NOW


Gasoline and Diesel sulphur specifications

Desulphurisation units become more and more important in refineries


Chemical Reactions in Hydrodesulphurisation

EXOTHERMICREACTIONS

Other reactions are the nitrogen compounds

deazotation, aromatics hydrogenation, olefins

hydrogenation, cracking,…

all these reactions are EXOTHERMIC


Hydrodesulphurisation Catalysts

- Generally HDS catalysts are constituted by metal oxides from columns VIA (Mo,W) and VIIIA ((Co),Ni) periodic table

- The active phase of HDS catalysts consists in the sulphided form of these oxides – MoS2 slabs

Al2O3γ

Mo

MoS6Å

30Å

.. .. ... .. . .

- Co or Ni are activity promoters and ‘decorate’ the edge of MoS2 slabs

- CoMo catalysts are generally used for low pressure units and were the main objective are HDS reactions

- NiMo catalysts are generally used for higher pressure units and were the main objective is density and cetane gain (hydrogenation reactions)

Co


Hydrodesulphurisation Catalysts

- Oxyde catalysts must be sulphided in order to transform the inactive metal oxides into active metal sulphides

•MoO3 + H2+ 2H2S MoS2 + 3H2O + heat•3NiO + H2 + 2H2S Ni3S2 + 3H2O + heat•9CoO + H2 + 8H2S Co9S8 + 9H2O + heat

-HDS catalysts can be sulphided after loading in the reactor – in situsulphiding-HDS catalysts can be sulphided ex situ and loaded afterwards in the reactor


Simplified Scheme of an Hydrodesulphurisation Unit

2

Partial by-passRecycle

compressor

Raw feed

Make-up compressor

Make-up hydrogen

to fuel gas

H.P.Flash drum

Furnace Reactor

Air coolers

Heat Exchangers

Stripper

Product

Quench

Operating parameters: feed, product, catalyst, flowrate, pressure, hydrogen/oil ratio and temperature


PROCESS Pressure (bar)

Temperature (°C)

Flowrate/ catalyst volume

(h-1) Naptha 7-30 280-320 3-10 Kerosene 15-50 300-330 2-6 Diesel oil 15-90 320-390 1-4 VGO 30-100 340-410 1-2 ARDS 80-200 370-410 0.2-0.5 VGO, residue hydrocracker 100-200 370-410 0.5-1.5

Typical operating conditions of Hydrodesulphurisation Units

- The most important parameters followed in these units (apart from product qualities!) are the temperature and unit pressure drop

- The difference on activity and stability of different catalysts is measured by °C


Time

SOR EOR

Feed rate

Max temp

Cycle length

Regeneration or catalyst changeout

Temperature

Fixed bed reactor - Cycle

Reactor – Cycle Length


Reactor – Cycle Length

Time

Feed rate

Max temp

Cycle length

Temperature

Time

Feed rate

Max temp

Cycle length

Poor catalyst performance High pressure drop


Operating an Hydrodesulphurisation Unit

- Average Reactor Temperature = 1/3 inlet T + 2/3 outlet T- Temperature increase with time due to coke formation and poisons adsorption- 3,5°C/month deactivation

320

330

340

350

360

370

380

390

400

0 40 80 120 160 200 240 280 320 360Days on stream

Rea

ctor

Ave

rage

Tem

pera

ture

(°C

)

10°C differenceCatalyst B

Catalyst A


Kinetic Models

Feed + H2

Desulphurized product+ H2 + H2

[ ] [ ]SkdtSd

×−=

LHSVektck

SoutSin TR

Eact×

−×

=×=

0ln

××

−=

0

)/ln(lnk

LHSVSoutSinR

ET act

[ ][ ]

[ ][ ] ∫∫∫∫ =⇔−=

tcSin

Sout

tcSout

Sindtk

SSddtk

SSd

00


Operating an Hydrodesulphurisation Unit

320

330

340

350

360

370

380

390

400

0 40 80 120 160 200 240 280 320 360Days on stream

Rea

ctor

Ave

rage

Tem

pera

ture

(°C

)

Normalized temperature1,5°C/monthActual temperature3,5°C/month

- Normalized temperature allows to correct for unit conditions and feed variations- Assessment of the real performances of the unit and the catalyst are much more precise


Reactors and Internals

Feed + H2


Reactorinlet distributor

reactor distributor tray

Quench system

reactor outlet collector


Distribution Trays

catalyst

inert balls

Gasliquidfeed


Distribution Trays

Additional gasketing


Distribution Trays

Elimination of dry spots and moving waves on the distributor,

Stable, homogeneous and "pulsation free" mix phase (fine mist) distribution,

High tolerance to unleveled installation,

Capabilit to hold solids and sl dge itho t degradation on performance

catalyst

inert balls

Gasliquidfeed


plug flow patternIdeal situation

funnel flow patternSituation with a small outlet collector

and/or with too much free sectionin the top of the collector

Coking zone

Outlet Collector


inert balls 3/4''

inert balls 1/2''


plug flow patternIdeal situation

funnel flow patternSituation with a small outlet collector

and/or with too much free sectionin the top of the collector

Coking zone

Outlet Collector


inert balls 3/4''

inert balls 1/2''


Catalyst Loading


Catalyst Loading


Case 1 – Reactor Design

1. Choose main conditions – Pressure, cycle length, type feed, product, flowrate

2. Catalyst volume

3. Optimum mass flux is set at 2,7 – 3 kg/s/m2

4. Normal pressure drop per bed not higher 3-3,5 bar

5. Set maximum catalyst bed length – 10-12 m

6. Set a maximum catalyst bed exotherm

7. Choose the internals – tray, quench, outlet collector

8. Care should be taken for all shut-down, catalyst unloading and loading

9. Choosing metallurgy as a function of Pressure, Temperature and liquid/gas composition


Case 2 – Unit Poor Performances

Case 2A - Unit A in France had an apparent activity at 25°C higher than expected

HDS - Evolution of normalised temperature for operating conditions feed sulphur = 5000 wppm, product sulphur = 200 wppm, LHSV = 1,6 h-1

320

330

340

350

360

370

380

390

400

0 60 120 180 240 300 360

cycle length (days)

norm

alis

ed te

mpe

ratu

re (°

C)

Expected performances

Actual performances



Cause analysis

a. Sampling and analysis validity!

b. Bad H2S stripping – H2S recombination

c. Leak or by-pass on a start-up line or a ∆P measurement line

d. Feed-Effluent exchanger leak

e. Impurities in gaz phase

f. Mal distribution

g. Poor catalyst performances



Leak or by-pass confirmation

- Kinetic analysis - Use of chemical tracers

- Pressure drop variation - Use radioactive tracers

320

330

340

350

360

370

380

390

0,0 0,2 0,4 0,6 0,8 1,0 1,2 1,4 1,6Leak %

Req

uire

d te

mpe

ratu

re to

reac

h sp

ecifi

catio

n (°

C)

Feed containing 3500 wtppm S

Effluent at 10 wtppm S




Effluent 28 ppmEffluent + 1%charge

4,6 DMDBTDBTC3 BT

Feed-effluent exchanger leak - feed effluent analysis

Sulphur compounds specific chromatograph




four

échangeur

Scharge

Seff réacteur

Seff éch A

Seff éch B

1

2

3

4

AB




Case 2 – Unit Poor PerformancesPACKINOX Exchangers


Case 2B - Unit A in the south of France lost 40°C of activity in few days

Evolution de la température normalisée%S de la chage = 5000 ppm, GO désulfuré = 320 ppm, VVH = 1 h -1 , PPH 2 = 25 bar, H 2 /Hc = 90 Nm 3 /m 3

300

310

320

330

340

350

360

370

380

390

0 30 60 90 120 150 180 210 240 270 300 330 360 390

Tem

péra

ture

norm

alis

éeen

°C

Jours de cycle



Possible causes:

- Catalyst deactivation during shut-down?

- Catalyst pollution by heavier feeds (metals)?

- Gas/Liquid maldistribution?

- …

Always the same:WHAT CHANGED BEFORE THEN AND NOW?




250 mm

Reactor diameter - 3000 mmBeam of 321 stainless steelThermal growth of 2 mm/m/100°C(general rule for steels is 1 mm/m/100°C)


#1 (R) 13FC1.COR 25/08/2003 02:35:42 3995,58 T/J (Raw) CHARGE DGO2**#2 (R) 13TC30.PNT 25/08/2003 02:35:42 355,03 DEGC (Raw) TRANSFERT_H1**#3 (R) 13PC48.PNT 25/08/2003 02:35:42 28,00 BAR (Raw) D1**#4 (R) 13L16B.PNT 25/08/2003 02:35:42 49,97 % (Raw) D1**

4443,00

-41,00

376,00

184,00

36,00

12,00

71,00

15,00

25/08/2003 02:22:48 26/08/2003 02:22:4

New Plot Title @ 1d 0h 0m 0s


temperature

HP separatorliquid level

flowrate

HP separatorpressure

Possible causes:- beam dilatation?

- other?


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

Pres

sure

dro

p

situation 1situation 2situation 4situation 3


Case 4 – Pressure DropPossible 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

Bed

2 p

ress

ure

drop

(bar

)



HR-448 1.2 mm DENSE LOAD

3/4" inert balls

1/4" inert balls3/4" 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??





Catalyst grading bed



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

Pres

sure

dro

p (b

ar)

Delta P measured

Delta P predicted


Case 4 – Pressure DropFeed + H2


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

Documents

Refining and Troubleshooting Hydrotreatment Units · PDF fileAssistance Technique Refining and Troubleshooting Hydrotreatment Units Ano lectivo 2005/2006 Pedro da Silva