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Hydroprocessing Units - ULisboa · PDF fileCatalytic Cracker FCC Visbreaking Reforming propane butane gasoline naphtha Hydrodesulphurisation kerosene ... Hydroprocessing Reactor and

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  • Hydroprocessing Units

    November 2004

    Pedro da Silva

  • Why Hydroprocessing?

    CO, NOx, HC, Particulates

    BEFORE

    NOW

  • Why Hydroprocessing?

    Desulphurisation units become more and more important in refineries

  • Market of solid catalysts in refining, (IFP data,1994)

    tons /year Catalytic cracking 440 000 Hydroprocessing 80 000

    Claus 20 000 Hydrocracking 8 000

    Reforming 5 000 isomerization 1 000

    other 12 000 TOTAL 566 000

    More than 80% of refined molecules see at leastone catalyst in their liver !

    Why Hydroprocessing?

  • Hydroprocessing Units Layoutin a Refinery Scheme

    Atm

    osph

    eric

    Dis

    tilla

    tion

    Heavy fuel

    Crude

    Vacu

    um D

    istil

    latio

    n

    CatalyticCracker

    FCC

    Visbreaking

    Reforming

    propanebutane

    gasoline

    naphtha

    Hydrodesulphurisationkerosene

    diesel

    H2

    Amine wash

    HDT

  • Hydroprocessing Units Layoutin a Refinery Scheme

    Atm

    osph

    eric

    Dis

    tilla

    tion

    Heavy fuel

    Crude

    Vacu

    um D

    istil

    latio

    n

    CatalyticCracker

    FCC

    Visbreaking

    Reforming

    propanebutane

    gasoline

    naphtha

    Hydrodesulphurisationkerosene

    diesel

    H2

    Amine wash

    HDT

    HDS

  • Hydroprocessing Units Layoutin a Refinery Scheme

    Atm

    osph

    eric

    Dis

    tilla

    tion

    Heavy fuel

    Crude

    Vacu

    um D

    istil

    latio

    n

    CatalyticCracker

    FCC

    Visbreaking

    Reforming

    propanebutane

    gasoline

    naphtha

    Hydrodesulphurisationkerosene

    diesel

    H2

    Amine wash

    HDT

    HDS

  • Typical operating conditions of Hydrodesulphurisation Units

    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

    - 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

  • Chemical Reactions in Hydroprocessing

    Not limited by thermodynamics

    Refractory compoundS

    Hydrogen consumption

  • Chemical Reactions in Hydroprocessing

    222120191817161514131211109876543210

    48 00046 00044 00042 00040 00038 00036 00034 00032 00030 00028 00026 00024 00022 00020 00018 00016 00014 00012 00010 0008 0006 0004 0002 000

    0-2 000-4 000-6 000

    SP

    W 0

    .20

    ST

    H 1

    0.00

    TI

    OF

    F

    RT [min]

    V A21 41838-01_1.DATA

    S

    C1

    S

    C2

    S

    C4

    S

    C3

    S

    S

    C1

    S

    C2

    S

    C3

    S

    C4+

    S

    C5

    Soufre peu rfractaire Soufre trs rfractaire

    Soufre rfractaire

    S

    S

    BT:Benzothiophne

    DBT:Dibenzothiophne

  • Soufre total=6 ppmS

    S

    S

    S

    S

    S

    S

    4,6-EtMeDBT

    1,4,6-TriMeDBT

    2,4,6-TriMeDBT

    4,6-DiMeDBT

    4,6-DiEtDBT

    3,4,6-TriMeDBT

    4,6-PrMeDBT

    Chemical Reactions in Hydroprocessing

  • Chemical Reactions in Hydroprocessing

  • Chemical Reactions in Hydroprocessing

  • Temprature (C)

    % H

    DA

    Souf

    re e

    fflue

    nt (p

    pm)

    T1 T2

    HDS

    Rgime thermodynamique(HDA)

    Rgime cintique(HDA)

    Equilibre thermodynamiqueHDA

    Chemical Reactions in Hydroprocessing

  • Chemical Reactions in Hydroprocessing

    - Hydroprocessing reactions are exothermic- Temperature and pressure are needed for hydroprocessing reactions- Reactor delta temperature:8-9C rise per 1 wt% sulphur removal1-2C rise per 1vol% of polyaromatics removal1C rise per bromine number removal

    quench

    four lit 1

    lit 2

    0

    R1

    Opration normale

    R1

    temprature

  • 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

    Quench

  • Hydroprocessing reactor and internals

    Vapor/liquid distribution tray

    Catalyst bed

    Varies between 3 to 15 m

    Catalyst support grid

    Quench distributor

    Mixing chamber

    Outlet collector

    Inlet diffuser

    Unloading nozzle

    Reactor diameter varies between 1,5 to 4,5 m

  • Hydroprocessing Reactor and Internals

    Catalyst bed

    reactor outlet collector

  • Hydroprocessing Reactor and Internals

    Additional gasketing

  • Hydroprocessing Reactor and Internals

    What techniques can be used to check the gas-liquid distribution inside the reactor?

    0

    5

    10

    15

    20

    0 100 200 300 400 500 600

    Days on stream

    Rad

    ial T

    dis

    pers

    ion

    (C

    )

    R1 B2 outlet

    R2 B1 outlet

    R2 B2 outlet

    Radial temperature dispersionRadioactive tracers

    Unit start-upUnit response to flow variations

  • Hydroprocessing 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

    Al2O3

    Mo

    MoS6

    30

    .. .. ... .. . .

    - 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

  • Hydroprocessing Catalysts

    Used catalystSulphide + coke

    Regeneration of used catalyst is possible by carefully burning sulphur and coke. The resulting catalyst will in its oxide form.

    Fresh CoMo cataltyst 1.2-2.5 mmOxide state

  • Hydroprocessing Catalysts Life

    Were should I go on holidays?Why not a reactor of a

    diesel hydrotreater?

    Unloading under inertatmosphere as Imquite keen to react

    with air

    RotaryRotary Kiln Kiln OvenOven

    Spent CatalystSpent CatalystHot AirHot Air

    Lets do it again

    Nice staying here, its always hot!however, its also always raining

    and it smells !!

    catalystloading

  • Catalyst Loading

  • Catalyst loading

  • Catalyst loading

    Loca

    l por

    osity

    ,

    Catalyst bed grading must be adapted in orderto avoid pressure drop build-up

  • Catalyst loading

    Different particles are available to be loaded above themain catalyst and minimize pressure drop build-up

    good hold inert balls or

  • Catalyst Activation

    Oxide catalystMoO3

    reactor

    Reductionto MoO2

    Unactive phase

    Under H2T > 230-250C

    Oxide catalystMoO3

    ex situ

    preSulphidedMoOxSyex situ

    Active catalystMoS2

    reactor

    in situSulphidation

    preSulphidingSulficat, Acticat,

    EasyActive

    H2 Activation

    Active catalystMoS2

    ex situ

    ex situ sulphidingTotsucat, XpresS

    H2S

    DMDS

    Final step

  • Catalyst Activation

    Rea

    ctor

    inle

    t tem

    pera

    ture

    (C

    )

    350

    300

    250

    200

    150

    100

    50

    00 2 4 6 8 10 12 14 16 18 20

    Time (hours)

    Drying(120-150C)

    Pre sulphiding step(reactor T < 15C)

    Catalyst sulphiding(320-350C)

    Catalyst wetting(liquid flow)

    1.Catalyst wetting at lower temperature allows better gas-liquid distribution2.The drying step should always be below 150C to avoid molybdenum oxide reduction3.DMDS injection 1 hour before reaching presulphiding step4.Maximum reactor exotherm should be below 15C to avoid high catalyst temperatures

    in without H2S5.Catalyst sulphiding step temperature depends on catalyst type and unit operation

    DMDS injection

    Unit under pressure

  • 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

  • Kinetic ModelsTypically, for HDS reactions on diesel and VGO Eact = 25000 - 29000 cal/moleExample - Catalyst volume = 200 m3

    Catalyst AFlowrate = 300 m3/hBed 1 Tin = 345C, Tout = 365C, Bed 2 Tin = 360C, T = 370CWABT = 362,5CSin = 7000 wtppmSout = 40 wtppmk0 = 1,5E10 h-1

    Catalyst BFlowrate = 280 m3/hBed 1 Tin = 342C, Tout = 362C, Bed 2 Tin = 352C, T = 362CSin = 7000 wtppmSout = 33 wtppmWABT = 359,9Ck0 = 1,4E10 h-1

    Catalyst A is 2C more active than catalyst B(this value is higher with more precise models!)

  • Kinetic Models - Cycle LengthOther parameters that must be taken into account in the kinetic models are:- hydrogen partial pressure- feed severity (nitrogen, density, aromatics, T95, other)- hydrogen/oil ratio, hydrogen sulphide and ammoniac partial pressure

    Time

    SOR EOR

    Feed rate

    Max temp

    Cycl

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