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    CONTENTS

    Page

    ACKNOWLEDGMENTS . . . . . . . . . . . . . . . . . . . . . . . . . v

    1 IN TRO D U CTIO N

    . . . . . . . . . . . . . . . . . . . . . . . .

    1

    2

    . D E S C R I P T I O N OF MODELS

    . . . . . . . . . . . . . . . . . . .

    6

    2 . 1

    L U R G I GASIFIER

    . . . . . . . . . . . . . . . . . . . .

    6

    2 . 2 E N T R A I N E D G A S I F I E R . . . . . . . . . . . . . . . . . . 10

    2 . 3

    RAW-GAS COOLING

    . . . . . . . . . . . . . . . . . . . . 14

    2 . 4

    I iECTLSO L MODEL . . . . . . . . . . . . . . . . . . . .

    1.7

    2 . 5 METHANOL SYNTHESIS . . . . . . . . . . . . . . . . . . 219

    2 .6

    MTG XODEL . . . . . . . . . . . . . . . . . . . . . . . 26

    2 . 7 S H I F T / M E T H A N A T I O N S E C T I O N . . . . . . . . . . . . . . . 38

    2.8 NAPHTHA HYDROTREATER

    . . . . . . . . . . . . . . . . .

    39

    2 . 9 FORTRAN SUBROUTINES . . . . . . . . . . . . . . . . . . 4 3

    3

    .

    IN TEG RA TIO N

    OF

    MODELS

    . . . . . . . . . . . . . . . . . . .

    45

    4 .

    R E S U L T S

    . . . . . . . . . . . . . . . . . . . . . . . . . . 47

    4 . 1

    B A S E L I N E T R I - S T A T E CASE. . . . . . . . . . . . . . . .

    47

    4 . 2 Fuu-SLzE TRX-STATE CASE

    . . . . . . . . . . . . . . .

    55

    4 . 3 T.LL1NOI.S NO . 6

    FEED

    . . . . . . . . . . . . . . . . . .

    57

    5. CO N CLU SIO N S

    . . . . . . . . . . . . . . . . . . . . . . . .

    59

    6 . REFERENCES . . . . . . . . . . . . . . . . . . . . . . . . . 6 2

    7

    .

    A PPEN D IX : SA SO L COA L TE ST

    DATA

    . . . . . . . . . . . . . . 65

    iii

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    ACKNOWLEDGMENTS

    The

    a u t h o r s gratefully acknowledge the

    s u p p o r t of

    Morgantown

    Energy

    Technology

    Cente r

    f o r

    t h i s work . The t e ch n i ca l gu idance

    and

    review

    comments provided by Leonard E .

    Grahatnn,

    Chief of th e Process

    Simula t ion and Analysis S e c t i o n ,

    and

    by h i s s t a f f w e r e h i g h l y c o n -

    s t r u c t i v e

    and

    added measurably t o

    t h e

    final

    results.

    Yrogrammatic

    guidance

    by Ralph E . Schafer, Deputy

    Director

    of C o a l P r o j e c t s ,

    Management Division,

    was

    i n v a l u a b l e a s t h e T r i - S t a te P r o j e c t

    evolved

    d u r i n g t h e course o f t h i s

    work.

    V

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    ASPEN

    MODELING OF

    THE

    TRT-STATE

    NDIRECT

    LI@~EEACTION

    RBCESF

    Ray E. Barker

    John M. Regovich

    James 11, C l i n t o n

    P h i l i p

    9 .

    J01msc;an

    ABSTRACT

    The

    ASPEN process s i m u l a t o r has been used t o model an

    t n d i r e c t l i q u e f a c t i o n fl ow sh ee t p at t e rn e d a f t e r t h a t of the

    T r i - S t a t e p r o j e c t . T h i s f l o ws h e et use s

    Lurgi

    mving-bed gas i -

    f i c a t i o n wi th s y n t h e s i s gas c o n v e r s i o n

    to

    methanol followed by

    f u r t h e r p ro ce ss in g t o g a s o l i n e using t h e Mob il MTG process.

    N od el s d e ve lo p ed i n t h i s s t u d y i n c l u d e the fo l lowing: LurgI

    g a s i f i e r , Texaco g a s i f i e r , s y n t h e s i s g a s

    c.ooPing

    .i Rect iso l . ,

    me

    hano

    1

    s y n t h e s i s m e thano

    1-r

    o-ga

    s o l

    i

    ne

    o

    CO-s

    h i

    t

    m e thana-

    Eion,

    a n d n a p h t h a h y d ro t r e a t i n g . Therje models

    have

    keen

    successfully developed In modular

    fo rm s o

    t h a t t he y can be

    used t o s imula te a

    number of

    d i f f e r e n t f l aw s h ee t s DT process

    a l t e r n a t i v e s .

    S i mu l a t i o n s of t h e T r i -S t a t e flowsheet have been made

    u s i n g two d i f f e r e n t coa l

    feed

    ra tes and ~ W Q y p e s o f f e e d

    c o a l .

    The o v e r a l l

    s i m u l a t i o n m ~ k l e lWAS a d j u s t e d

    t o

    match the

    Tri-State

    f l o w s h e e t v a l u e s

    for

    methano l , LBG, fsolautane, and

    g a s o l i n e . A s a r e s u l t o f t h i s ad j us tm e n t, t h e MTC r e a c t o r

    y i e l d structure n e c es s ar y t o

    match

    the f lowshee t product ra tes

    w a s

    de te rmined , Tfae models

    were

    e x e r c i s e d a t

    dffferent

    flow

    ra tes

    and

    were

    u n a f f e c t e d b y

    such

    c h a n g es , d e mo ns t ra t i ng t h e i r

    range of

    o p e r a b i l i t y . T h e

    u s e of Lllinois Ma. ti

    c o a l , w i th

    i t s

    lower ash c o n t e n t , resulted i n s l i g h t l y h i g h e r p ro du ct io n

    ra tes of

    each of t h e p r o d u ct s

    a s

    compared

    t o u s e o f

    t h e

    Kentucky c o a l

    1.

    INTKODUCTION

    The T r i - S t a t e P r o j e c t was o r i g i n a l l y c o n c e i v e d as

    an

    i n d i r e c t

    F i s c h e r -Tro p s c h l i q u e fa c t i o n

    p l a n t

    produc ing approx imate ly 56,000 b a r r e l s

    of

    f u e l o i l e q u iv a l en t

    p e r

    day of t r a n s p o r t a t i o n f u e l s a nd c h em i ca ls from

    Kentucky coa l .

    The p r e l i m i n a r y d e s i g n of t h i s

    plant

    was co-funded by

    the

    Department o f Energy

    (DOE)

    and

    t he

    i n d u s t r i a l p a r t i c i p a n t s . W it hi n DOE,

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    th e &rgantown Energy Technology

    Centt?r (METC) has

    t h e r o l e

    of

    t e c h n i c a l

    l e a d

    f o r

    g a s i f i c a t i o n s ys te ms t o

    ME-firnded

    pr o j ec t s . In consonance wit11

    t h e r o l e o n ' h i - S t a t e of providing Lechnological review and advice on

    g a s i f i c a t i o n

    a d

    r e l a t e d sys t e ms

    a

    pr oc e s s

    model

    of t h e

    o v e r a l l

    p l a n t

    would

    (1)

    e nh an ce t h e c a p a b i l i t i e s f o r i n v e s t i g a t i n g

    and

    e v a l u a t i n g

    t c c h n i c a l

    u n c e r z a i n t i e s

    aid

    a l t e r n a t i v e s a n d

    ( 2 )

    provide

    a

    permanent

    r e c o r d

    f o r

    f u t u r e r e f e re n c e

    and

    use .

    Accurate p r o c e s s c a l c u l a t i o n s are n e c es s a ry f o r r a t i o n a l d e s i g n and

    op era t i on of p roces s equipment, These c a lc u la t ions c a n r a nge from very

    s i m p l e

    ( r e q u i r i n g

    o n l y

    a

    poc ke t c a l c u l a to r ) t o ve r y complex ( r e qu i r i ng

    a

    la rge compute r ) .

    I n

    t h e l a t t e r case,

    a

    p ri ma ry t o o l i n u se a t ORlvL i s

    t h e ASPEN (Advanced ys tem

    €o r

    r oc es s ng ine e r ing) p r oc e s s s imu la to r .

    ASPLN i s a modern, s ta te-af- the-ar t process s imu la to r r e c e n t ly de ve lope d

    f u r DOE ar a c o s t of 6 i n i l l i on . Th i s r e p o r t de t a i l s t h e model ing of a n

    i n d i r e c t l i q u e f a c t i o n €1 owshee t us ing the ASPEN s imu la to r . These pro-

    cess models have been developed i n modular form so th at they

    can

    be used

    t o m 4 c l

    a

    :urnmbP?sr

    of

    d i f f e r e n t

    process

    a l t e r n a t i v e s .

    T h i s work h a s c o n s i s t e d of developing models of t he va r ious sys t e ms

    c ompri s ing the T r i - S ta t e p r o j e c z and in t e g r a t in g the models i n a con-

    s i s t e n t

    f a s h i o n

    w i t h

    recyc le

    streams t o produce an ov er a l l p rocess model

    u s i n g t h e ASPEN computer code.

    Adequate

    pr ope r ty da t a

    of

    l i qu id s ha ve

    been obLainrd o r e s t ima te d a nd c o r re ' la e ed t o y i e ld t e c h n ic a l ly con-

    s i s t e n t

    medels

    of

    t h e

    c r i t i c a l

    areas

    of th e pla nt . Although the

    T r f - S t at e p r o j e c t h a s

    been

    te r mina te d , t he

    ASPEN

    models and sp ec ia l pur-

    pose subrout ines deve loped for t h i s wcrk shou ld be a pp l i c a b le t o many

    i n d i r e c t l i q u e f a c t i o n f lo w s h ee t s .

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    3

    S e v e r a l m o d i f i c a t i o n s t o t h e p r o j e c t and i t s f lowshee t

    w e r e

    made

    dur ing th e des ign phase. The f lowshee t of the Tr i -S t a te p r o j ec t modeled

    uses Lurg i moving-bed ga s i f i ca t i on and sy n t he s i s gas convers ion t o

    methanol, which

    i s

    f u r t h e r p r o ce ss e d t o g a s o l i n e u s i n g t h e Mobil MTG

    (methanol- to-gasol ine) process . Syn thes i s

    gas

    no t conver ted to methano l

    i s me th a na te d t o prod u ce s u b s t i t u t e n a t u r a l g a s. A s i m p li f i e d o v e r a l l

    f lowshee t of th e Lurgi-methanol-MTG p ro ce ss i s shown i n Fig.

    1.

    The western Kentucky coal i s f e d t o t h e c o n v e n t i o n a l d ry -a sh Lu rg i .

    T h e L u r g i g a s i f i e r s are t o be modified

    f o r

    u s e w i t h c a k i ng

    coals

    by the

    a d d i t i o n o f

    a

    s t i r r e r

    t o

    main tain good bed poro sfty . This arrangement

    h a s b ee n t e s t e d w i th t h e p ro p os ed c o a l r e c e n t l y a t SAS0L.l The

    L u r g i

    g a s i f i c a t i o n model ha s b een c a l i b r a t e d t o r e f l e c t t h o s e t e s t r e s u l t s .

    Th e s y n t h e s i s gas from the Lurgi

    i s

    cooled t o condense water and the

    conden sable hydrocarbons. The

    heat

    r e l e a s e d f r o m t h i s c o o l i n g i s used

    t o g e n er a te

    l o w -

    and medium-pressure steam.

    The coo led syn th es i s gas

    i s

    t h en s e n t t o t h e R e c t i s o l p l a n t , w here

    i t i s cooled and the H2S i s removed by absorption

    i n

    refrigerated metha-

    nol . The R e c t i s o l f l o w s h e e t

    i s a

    s t a n d a r d d es i g n f o r

    gases

    c o n t a i n i n g

    condensable hydrocarbons (i.e. naph tha) . The s u l f u r - f r e e g a s i s then

    c ompres se d a nd p a s s e s t o t h e me th a no l s y n t h e s i s r e a c t o r .

    The

    methanol

    s y n t h e s i s

    process

    u s e s t h e L u rg i r e a c t o r , w i t h t h e h e a t

    of

    r e a c t i o n

    being

    u se d t o g e n e r a t e

    steam

    i n t h e r e a c t o r j a c k e t . The r e a c t o r p ro d uc t

    i s

    cooled

    t o

    condense th e methanol, and th e unr eacte d gases

    are

    r e c y c l e d

    t o t h e r e a c to r . I n or d e r t o pr e ve n t bu il du p of i n e r t s i n t h e r e a c t o r

    recycle, I t

    i s necessary to pu rge

    a

    p o r t i o n

    of

    t h a t stream, ca l l ed

    t h e

    purge gas .

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    u

     

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    The

    u n i t s ulodeled i n t h i s s t u dy I n c h d e : Lurg i

    gasi.Cler,

    Texaco

    ( o r

    o t h e r

    e n t r a i n e d )

    g a s i f i e r ,

    s y n t h e s i s g as c o o l i n g , X e c t i s o l ,

    methanol

    sy n th es is , methamol-to-gasoliznf, CO-shift , methanation,

    and

    naphtha

    hydrci t . rea t ing. A d d i t i o n a l l y , two user

    FORTRAN

    subroul:tnnes have been.

    w r t t t e n f o r t h e d e v o l a t i l i z a t i o n of c oa l t o form char and v o l a t i l e pro-

    d u c t s and fo r t h e d e c o mpo s i ti o a of coal.

    t o

    i t s

    elements

    p l u s a s h and

    char . These rou t ine s

    are

    general.

    and very i i s e f e r P i n

    t h e

    rztcsde'ling of

    many

    coal convers i .an processes .

    Orie

    user P O K T W - u n i t a p c ra t i o n mo d e l

    h a s

    been

    written to f a c i l i t a t e m od elin g of waste h e a t : b o i l e r s ,

    wMch a i e

    wl.dely

    used i n coal. convers ion

    processes.

    An

    enhancemen t t o t h e ASPEN

    p h y s i c a l p ro p e r t y s y s te m h a s a l s o been made t o a l lo w f o r t h e d i r e c t

    i11put: of hea t of combust ion val ues fo r

    c o d .

    T h e

    rernrairrder of

    t h i s r e p o r t p r e s e n t s

    (1)

    t he de.ta. i .1~

    f

    t h e

    u n i t

    ope ra t ion models , FORTRAN

    subrout j .nes

    and ASPEN enhancement ; ( 2 1

    how

    t he se models were

    t i i tegrated

    t o a l l o w o v e r a l l mater ta l halances t o be

    made; and ( 3 ) t h e r e s u l t s

    u s i n g

    d i f f e r e n t types

    of feed

    c o a l

    and

    v a r i a t i o n s

    i n

    coa l th roughpu t . The ASPEN computer i n p u t and r e p o r t

    f i l e s f o r th e m0dels and

    FBB IH.AN

    s u b r o u t i n e s developed i n t h i s s tu dy are

    b e l n g i s s u e d as a Suppleslent

    t o

    t h i s r e p or t . A l imited number

    of

    c o p i e s

    a r e

    a v a i l a b l e by c o n t a c t i n g ORNL. Micro f iche

    c o p i e s

    a r e available f r o m

    the

    N a t i o n a l Te c h n i c a l I n fo rma t i o n S e rv i c e (NTIS >.

    2.

    DESCRIPTION

    OF MODELS

    2 . 1 LURGI GASIFIER

    The information necessary t o f o r m 1

    a t e

    the L u r g i g a a f f i e r model w a s

    1 2

    t a k e n

    from

    t h e SASOL c o a l t e s t and a r e l a t e d p u b l i c a t i o n . The model

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    7

    h as e s s e n t i a l l y f o u r s t e p s : (1) dryingldevolatilization;

    ( 2 )

    convers ion

    o f d e v o l a t i l i z e d coa l t o i t s e lemen ts , p l us ash and char;

    3)

    convers ion

    of th e eleme nts t o produce gas-phase components; and

    ( 4 )

    e q u i l i b r a t i o n

    of th e gas-phase components. The e q u il i b r a te d gas-phase components

    a r e t h e n r em ix ed w i th t h e v o l a t i l e s t o f o rm t h e raw s y n t h e s i s g a s .

    The

    s o l i d s f rom t h e g a s i f i e r are removed i n ano the r stream. The ASPEN

    block

    f low diagram for th i s model i s shown

    i n

    Fig.

    2.

    The c o a l d e v o l a t i l i z a t i o n

    i s

    d on e i n b l o ck

    PROD

    u s i n g t h e ASPEN

    r e a c t o r mo d e l

    KYIELD

    w i t h u s e r y i e l d s u b r o u t i n e DEVOL. S u b r o u t h e DEVOL

    c o n v e r t s h a l f

    of

    t he v o l a t i l e matter from the proximate analys is com-

    p o n e n t a t t r i b u t e

    t o

    v o l a t l l e p ro d u c ts . The p ro d u c t s are assumed t o be

    H2,

    CH4,

    R 0 , CO,

    C,+, CO

    a r e

    p as se d t hr ou gh t h e f i r s t e i g h t l o c a t i o n s of t h e RFCAL vector i n t h e

    ASPEN inpu t l anguage. These y i e l ds must

    be

    o b t a i n e d f ro m e mp i r i c a l

    d e v o l a t i l i z a t i o n d a t a

    o r from some

    o t h e r s o u rc e . DEVOL u p d a t e s t h e

    proximate and

    u l t i m a t e

    a n a l y s l s

    of

    t h e c o al t o

    reElect

    the changes due

    t o d e v o l a t i l i z a t i o n ; i n t h i s m anner t h e e le me nt b al an c e

    i s

    maintained .

    phenol , and t a r . Th e i r r e spec t ive y i e l d s

    2

    2’

    A f t e r t h e v o l a t i l e s are removed i n t h e s e p a ra t i o n

    block.

    LBEVOL, t h e

    d e v o l a t i l l z e d c o a l

    i s

    decomposed t o I t s e l e me n ts f n b l o ck C O W . Block

    C OW also u s e s t h e ASPEN R Y I E L D r o u t i n e and a user y i e l d r o u t i n e ,

    DECOMP. Subrou t ine DECOMP merely decomposes th e co a l t o i t s e lemen ts

    p lus char and ash based on t h e u l t l m a t e a n a l y s i s . ‘Ilhis scheme places

    t h e c o a l ( o r c h a r ) u n d er go in g g a s i f i c a t i o n i n t o c o n v e n t io n a l c om po nents

    w h i l e s t i l l main ta in ing th e e lemen ta l ba lance .

    The e lemen ta l coal c o n s t i t u e n t s

    are

    t h e n

    m i x e d

    w i th t h e g a s i f i e r

    oxygen and

    steam

    f e e d s . I n block GAS1, t h e ASPEN

    RSTOIC

    model

    i s

    used

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    ORNL DWG 82-1011R

    COAL-FD

    q

    PRUDGAS

    COALPROD

    RGAS

    REACTD I

    OFFGAS

    JACKTSTM

    r

    I

    I

    Q 1

    Fig.

    2 ,

    ASPEN black

    diagram

    of L u r g i

    gasifier model.

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    10

    2.2

    EN I KAIINED

    GASIFIER

    The Texaco eiztrainetl g a s i f i e r model i s sirnil.ar to the TAurg imodel.

    e x c e pt t h a t t h e e n t ra i -n e d g a s i f i e r a ssu mes t h a t d e v o l a t i l i z a t i o n i s

    un impor tan t phis model h a s g i w n e x c e l l e n t r e s u l t s f o r m od elin g

    entrained

    g a s i f i e r s ;

    T a h l e

    shows

    a

    comparison between our model

    pre-

    d i ct i o n s arnd da ta

    from

    Koppers5 f o r t h r e e w id el y d i f f e r e n t c o a l s :

    westerii , I l l i n o i s , and e a s t e r n c o a l s - F O P each coa l , th e ag reemen t

    between

    t h e

    ASPEN p r e d i c t i o n s an d t h e

    Koppers

    data i s q u i t e g o a d ,

    A n ASPEN block f l o w diagram of t h e e n tr a in e d g a s i f i e r

    model.

    for a

    s o l i d coal f e e d

    i s shown

    i n Fig .

    3. The

    model beg ins by f i r s t decom-

    p o s i n g a l l com pon en ts h av i ng a n u l .t ii na te a n a l y s i s a t t r t b u t e t o t h e i r

    e l e me n t s , p l u s ash and char . T h is d e c o ~ ~ ~ p o s i t f ~ ~ ~

    s

    done

    i n

    b lock CONV

    u s i n g

    tlrcs

    user y i e l d s u b r o u t i n e , DECBMP, as d e s cr i b ed i n t h e p r e v io u s

    d i s cus s io n o f th e Lurg i model. IF n ot o t h e r w i s e s p e c i f i e d , t h e carbon

    burnup

    i.s

    assumed t o be

    100%.

    It s h o u l d b e n o t e d t h a t DECOMP will a l s o

    decompose a t t r i b u t e c o n v e n t i o n a l co mp on en ts , s u c h as t a r . When a s o l i d

    coal. feed i s

    not

    used , as i n the

    T r i - S t a t e

    case, t h e ASPEN

    flow

    diagram

    shown i n Fig .

    4 i s

    used.

    The

    conver ted e lemen ts a r e t h e n m f x ed w i t h t h e

    oxygen and t h e s o l i d phases r e a c t e d t o gas-phasi? c o m p ~ n e n t ~nd adia-

    b a t i c a l l y e q u i l i b r a t e d

    as

    in the Lurgi model . The h o t , e q u i l i b r a t e d

    gases

    are then quenched w i t h

    water

    t o a temperature of 1800'F;

    a de s ign

    s p e c i f i c a t i o n

    i s

    i n c l u d e d t o v a ry

    the

    quench water f low r a t e t o o b t a i n

    t h e s p e c i f i e d o u t l e t t em p er at ur e.

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    11

    Table

    1.

    Comparison

    of ASPEN

    entrained g as if ie r model and published reports

    of

    Koppers-

    T ot zek g a s i f i e r p e r f o m n e e (basfs: 1 t o n / h )

    Analysis , w t X

    C

    H

    N

    s

    0

    Ash

    Moisture

    Gross heating value

    ( B tu / l b )

    Oxygen

    (98% 0 2 >

    ( l b l h )

    Steam (250 F, 14.7 p s i )

    ( I b l h )

    INPUT

    Coal

    Western

    56,76

    4.24

    1.01

    0.67

    13.18

    22.14

    2.00

    I l l i n o i s

    61.94

    4.36

    0.97

    4.88

    6.73

    19.12

    2.00

    Eastern

    -___.

    69.88

    4.90

    1.37

    1.08

    7.05

    13.72

    2.

    oa

    9,888

    11,388

    12,696

    1,298 1,408

    1 , 634

    272.9 541.3 587 .4

    RE sULT

    ASPEN Koppers

    ASPEN

    Koppers ASPEN Koppers

    -~

    Gas production (SCFH)

    5 1 665

    51,783 57,752 59,489 64,473

    65,376

    Gas compositfon,

    m o l X

    ( d r y )

    33,3 32.86

    35.0 34.62

    35.7 35.39

    59.5 58 .68 55.4

    55.38 56.0 55. Y O

    5-81

    7.04 6.7

    7.04

    6.88 7. 18

    1.07

    1.12 0.98

    1.01

    1.11 1.14

    0.27 0.28

    1.80 1.83

    0.36 0.35

    0.02

    0.02

    a. 09 0.12

    0.02 0.04

    Carbon burnup, w t X

    -

    assumed

    1

    99.5 97. 0 -

    97.0

    -

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    1 2

    I

    I

    I

    I

    I

    I

    I

    I

    I

    -

    I

    1.

    w

    Fig.

    3 .

    a solid

    coal f

    COOLASH

    ASPEN

    eed.

    GAS

    BFWl

    block diagram of

    e n t r a i n e d

    g a s i f i e r

    model

    w i t h

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    13

    ORNL DWG

    82-1451R

    TSTEAM TOXYGEN

    TLIQ5UT

    WATER

    TSTEAM

    PROPUCT

    Fig.

    4 .

    ASPEN

    block diagram of e n t r a i n e d

    gasifier w d e l

    w i t h

    l i q u i d f e e ds .

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    2.3

    RAW-GAS

    COOLING

    The

    Tr-t -S ta te

    f lowshee t c a l l s f o r t h e r a w synthes j is gas t o he

    c o o l e d and s e n t t o R e c t i s o l , n o t u s i n g

    a

    r a w s h i f t as i n some other

    p roposed p rocesses . ‘l’he se ns ib le hea t i n ho t raw s y n t h e s i s g as i s a

    s i g n i f i c a n t f r a c t i o n of t h e h e a t i n g v a l ue of t h e f ee d c o a l a nd , t h e r e -

    f o r e , must b e r e c o v e re d e f f i c i e n t l y . This recovery p rocess ts the func-

    t i o n of th e raw-gas coo l ing sec t io n .

    The

    process f low diagram used

    f o r

    our gas cooking model

    i s

    shown i n

    6

    Fig .

    5.

    Th e d e t a i l s

    of

    t h i s f l o w s h e e t

    w e r e

    t aken f rom

    Wham

    e t a:

    The gas c o o l in g s e c t f o n c o o ls t h e raw synthesis g as t o t h e lowest prac-

    t i c a l t e mp e ra t u re u s i n g

    water

    and

    a i r

    coo l ing , This maximum practical

    c o o l i n g re du ce s t h e r e f r i g e r a t i o n r eq u ir em e nt s i n t h e R e c t i s o l u n i t

    which fo l lows.

    The ASPEN block flow diagram f o r th e gas-cool ing model i s shown i n

    Fig . 6 . The ho t s yn th es i s gas i s first scrubbed wPth recycle condensate ,

    b lock M1

    The

    tw o-ph ase d x t u r e from t h e s c ru b b e r i s co oled i n th e f i r s t

    he a t exchanger , b lock

    E 3 0 1 E 3 ,

    generating medium-pressure steam. The gas

    f ro m t h e f i r s t h e a t e xc ha ng er i s

    f e d t o

    a knockout drum, with t he con-

    d e n s a t e r e c y c l e d t o the sc rubber . The

    gas

    from the knockout drum

    i s

    c o o l ed fu r t h e r i n t h e s e co nd h e a t e x c ha n g er , b l oc k E 3 0 3 A E 1 , producing

    more

    medium-pressure steam and d i r ty condensa te. ‘ h e gas i s t h e n f e d t o

    t h e t h i r d h e a t e xc ha ng er

    t o

    produce low-pressure

    steam.

    A t

    t h i s

    p o i n t ,

    t h e g a s s t r ea m

    i s

    a i r -cooled

    and

    water-cooled and se nt 60 t h e R e c t i s o l

    u n i t .

    This

    model assumes a c l e a n t a r /wa te r separation i n b lo ck SWPLIT,

    w i t h t h e t a r being f e d

    t o

    t h e

    Texaco

    gasifier. R e Redlich-bong-Soave

    (SYSOP3) equat ion , which i s e x c e l le n t f o r l i g h t gases and hydrocarbons ,

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    i s used f o r t h e c a l c u l a t i o n

    of

    p h y s i c a l p r o p e r t i e s f o r p r o c e s s

    streams;

    t h e ASME

    steam

    t a b l e c o r r e l a t io n s SYSOP12) are used for

    steam

    and

    c o o l i n g water. Tbe p h y s i c a l p r o p e r t i e s for the condensable hydrocarbons

    w e r e o b t a i n e d u s i n g t h e

    Wilson

    co rr e l a t io n. When a r f go r ous ASPEN

    sour-water

    f la sh mde l has been developed,

    I t

    should r e p f a c e the p r e s e n t

    FLASH2 blocks.

    3

    2.4 RECTISOL ESODEL

    T h e c a t a l y s t s

    u s e d

    f o r me th an o l s y n t h e s i s

    and

    methanat ion

    are

    sen-

    s i t i v e

    t o

    poisoning

    by

    s u l f u r

    C O I U ~ Q U ~ ~ S ,

    he

    R e e t i so l

    process i s

    one

    of

    t h e more

    w f d e k y

    used p rocesse s

    f o r

    removing

    H S from

    s y n t h e s i s gas. "he

    R e c t i s o l p r o c e s s uses methanol

    as

    a s o l v e n t

    f o r

    the H , S a

    A t

    the tempera-

    t u r e s used (-70"F), H,

    S

    i s

    more scslub1.e

    i n

    methanol

    than are

    t h e o t h e r

    major

    components

    of

    s y n t h e s i s

    gaso The flowsheet

    used he re

    I s

    t h e s t a n -

    dard f ive-column process

    designed f o r

    t r e a t i n g g a s es c o n t a in i n g

    a

    s i g n i f i -

    c a n t c o n c e n t r a t i o n of naphtha , The presence

    of

    naph tha compl i ca t e s t he

    p r o c e s s i n g b e ca u se an azeo t rope i s f~rmedlbetween naphtha

    and methanol

    and two l i q u i d p ha s es c a n be formed i n the naph tha /me thano l/wa te r

    system. To prov ide

    f o r

    t h e s e h i g h l y n o n i d e a l v a p o r - l i qu i d

    equilibria,

    t h e v e r s i o n

    of

    t h e Soave-Redlich-Kwong eq ua ti on

    of

    s t a t e t h a t

    has

    been

    modi f i ed for polar components (Redlich-bong-ASPEN) was u s e d . F i t t e d

    b i n a r y i n t e r a c t i o n p ar a me te r s

    are

    u s e d f o r

    a l l

    i n t e r a c t i n g s p e c i e s .

    The

    data

    shown

    i n

    the

    ASPEN

    i n p u t

    file

    are

    i d e n t i c a l t o t h e

    RKSKIJ

    i n s e r t

    u s e d

    i n the

    gasifier s e c t i o n .

    2

    2

    4

    The process flow diagram f o r the Rec t i so l model i s shown i n Fig. 7.

    The c or re sp on di ng ASPEN block diagram

    i s

    shown i n Fig,

    8,

    "he

    r a w

    gas

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    _

    _

    _

     

    _

    _

     

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    RECMXG

    RREFRIGl

    HEATER

    RECDESC.2

    RECVAP 13

    REC.WG3

    RECGLIQ

    LASri3

    REiGbI92

    SC

    1

    RECAZEO

    HXDL'TP3

    I

    L,

    P I 7

    R E C L i Q i 7

    I

    RECNAPEF

    REC SAP

    15

    HECH

    RHZOWASH

    RHZOWCV

    PADFRC RADFRC

    RECOFFG

    4

    RECHZOEF

    kECMStiR3

    I

    Fig. 8. ASPEN

    block

    diagram

    of

    Rectissl section.

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    20

    from gas c oa l ing i s exchanged against

    the

    purified gas and

    w P t h

    makeup

    r e f r l g e r a t i o n

    and

    f e d t o the prewash se c t io n of t h e

    absorber.

    The

    prewash

    i s o p e ra t e d

    SQ t h a t

    t h e naphtha i s

    absorbed

    whlbe allowing

    t he

    l i g h t e r components t o pa ss t o

    t b e upper

    s e c t i o n

    s E the absorber. The

    loaded

    soPvent

    i s se n t t o t he a z e o t r ope c olumn t o

    separa te

    a

    c lean

    naphtha product and a methanol-r ich

    stream.

    The loaded so lvent

    from “ t ~ s

    u p p e r

    s e c t i o n

    of

    the

    absorber i s f l as h e d t o release a bso r be d syn the s i s

    gas (w:iich i s

    r e c y c l e d t o

    t h e

    absorber

    i n l e t ) and then f e d t o t h e

    s t r i p p e r a l o ng w i t h the methanol-r lch

    stream

    f rom the aze~trope olumn.

    In

    t h e

    stripper

    t h e

    H r S

    is s t ~ i p p e d . n m

    the

    solvent-

    forming

    a

    H

    S-rich

    vapor stream. The 3 , s - r i c h stream i s washcd with

    water

    t o rzcover t h e

    meehanol. The water-methanol mixture i s

    t hen

    d i s t i l l e d t o ob ta i i l a l e a n

    methanol stream

    for

    r ecy e l c to

    the

    absorber .

    ‘ R e bottom s t r e m from

    t h e

    H ~ S t r i p p ~ rs a l s o

    recycleel t o t h e

    absorber ,

    2 7

    E

    2. S P I E T W Q L SYNTHESIS

    The methanol synthes is model i s based on t h e 14urgh tubular

    reactor

    6 , 8 - - 1 1

    concept . In

    that

    scheme,

    t h e

    h e a t

    s f

    r e a c t i o n

    i s

    u s e d t o

    wake

    steam I n t h e r e a c t o r shell, which

    i s

    t he n

    available

    f o r

    use

    e l sewhe re in

    t h e process. rtao m et ha no l s y n t h e s i s r e a c t i o n s are assumed t o

    occur

    and

    t o be a t

    e qu i l i b r ium

    a t

    the

    reactor exit:

    CO

    +

    2R2 8 11-I OH

    CO, 4- 3s2 *

    C H p

    , 3

    1120

    The f lowshe e t d e t a i l s have been taken f rom Wham e t a1.6

    The

    f lowshee t

    compressed a n d d x e d w i t h the recyc le . The mbxtrsre of fresh feed and

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    z

    re

     

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    22

    recyc1.e i s then compressed t o t h e d e s i r e d r e a c t i o n p r e s s u re . TE-IPS

    stream i s heated by heat exchange w i t h r e a c t o r e f f l u e n t before e n t e r i n g

    t h e r e a c t o r . A f t e r heat exchange with the r e a c t o r f e e d , t h e r e a c t o r

    e f f l u e n t i s coo led . fu r ther

    i n

    air- and water-cooled exchangers t o con-

    dense the prod1xc.t methanol. The noncondensalzles are s p l i t part

    r e c y c l e d , a n d the rest purged t o p r e v e n t hi . l .&ap of i n e r t s s uc h as

    methane and h igher hydrocarbons i n t h e r e a c t o r l o o p , The purge gas

    i s

    s e n t t o

    the s h i f

    t / m e t h a n a t i ~ o n

    i n i t

    f o r f u r t h er

    processing. The methanol

    pi:odiict

    i s

    f u r t h e r d e p r e s s u r i z e d v a p o r i z i n g a d d i t i o n a l l i g h t g a s w hic h

    can be

    w e d as

    fuel .

    o r

    sen t

    to methanat ion .

    Part

    of

    the

    steam

    g e n e r a t e d

    i n

    the

    r e a c t o r j a c k e t i s expanded through a t u r b i n e

    t o

    g e n e r a t e

    the

    p m m r

    n e c e s s a ry t o w n t h e f e e d a nd r e c y c l e c omp re ss or s.

    T h e ASPEN block diagram f o r t h e methanol s y nt he si s simulacj.on -Is

    shown io. Fig. 10.

    he

    si.mul.ation u s e s

    t h e ASPEN

    COMPR

    block t o s i m -

    l a t e t h e two

    compressors

    and

    thtt:

    t u r b i n e , ASPEN BEATER b lo ck s have been

    u s e d t o s i m r r l a t e t h e h e a t e x c h a n g e r s , w i t h the two s ides of t h e

    f ee d / e f f i ue n t exchanger connected

    by

    a beat i n f o r m a t i o n

    stream, Q1.

    r e a c t o r i s

    modeled by an ASPEN REQUXL b lock and

    i s

    assu med t o o p e ra t e

    i s o t h e r m a l l y . The

    heat

    of reactf-on

    f rom

    the reactor i s passed

    t o

    the

    b o i l . e r

    user model v ia heat :

    stream

    42.

    'The steam. produced

    i n t h e

    b o i l e r

    i s s p l i t , w i t h p a r t o f t h e steam sent t o t h e t u r b i n e . Tlie t u rb i n e b l o c k

    The

    accepts t h e work i t ~ f o r r n a t i o n

    treams

    f rom the @ompj:&SsoTS,

    W1 and

    W2,

    a n d c a l c u l a t e s a n "excess" work i n f o r m a t i o n stream, W3. An ASPEN DESIGN-

    SPEC va r i e s t h e s p l i t

    u f t h e

    steam

    s t ream

    so t ha t t h e e x c e s s work from

    t h e t u r b in e

    i s

    zero. The produc t

    condensation

    and l e t d o w n o p e r a t i o n s arc

    s i m u l a t e d

    w i t h

    the ASPEN FLASH2 bl0c.k. The f i t t e d b l n a ry i n t e r a c t - i o n

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    2 3

    PUREGAS

    w2

    I ?

    ? iLTKECYA

    M L I K t I

    I

    I

    JJ

    ETNIXER METRECYC

    MIXER

    H i A l I R

    I

    HETCOOLR w r w

    E TcDND

    HEATER

    FLASH2

    Fig. 20

    ASPEN block

    diagram

    of the methanal synt.hesis

    s e c t i o n .

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    24

    c o n s t a n t s disci . issed i n rhe Re ct i so l model are used Tor the v a p o r - l i q u i d

    equi

    l l b r i u m c a l c u l a t i o n s .

    T h e

    methanol synthesis

    model

    has

    Four

    primary

    i n d e p e n d e n t v a r i a b l e s

    :

    ( 1 )

    feed composi t ion and s t a t e , ( 2 )

    reactor

    t e mp e ra t u re , (3) r e a c t o r

    p r e s s u r e , and ( 4 )

    r ecy c l e

    ratio. Other v a r i a b l e s , u s u a l l y c o n si d e re d

    constant ( e . g . , pressure d r o p s through the equipment , tem peratur e and

    p r e s s u r e of t he

    product

    sepa r a to r s , steam p r e s s u r e ,

    e r e . ) , can

    a l s o be

    v a r i e d .

    Tab le 2 shows t h e r e s u l t s of v a ry i n g t h e

    reactor

    p r e s s u r e

    and

    r ecyc le r a t i o , h o l d i n g the s y n t h e s i s temperature constant (500°F)

    and

    u s i n g t h e f e e d eonposition. from t h e Tr f -S t a t e design r e p o r t . l 2 m e

    cornposittoen

    and

    c o n d i t i o n s are shown

    i n

    Tab le 3.

    The

    r e s u l t s i n

    Table

    2

    i n d i c a t e

    t h a t

    u s i n g recyc le r a z i o s g r e a t e r t h a n a b o u t 1.0 i n c r e a s e s t h e

    equipment

    s i z e

    and comprt:..ssor horsepower,

    with

    l i t I e increase i n metha-

    n o l product ion. I n t h e case

    of

    T r i - S t a t e , where t h e purge

    gas

    i s to be

    s h i f t e d and m t h a n a t e d

    t o

    produce

    SNG

    (assuming

    t h a t

    t h e

    SNG

    can

    be

    s o l d ) ,

    the re

    i s 1it:tIe inc ent €ve t o use a recycle ratio g r e a t e r than 1.0.

    Table

    3 ,

    Synthcs-bs gas f e e d t o

    methanol s y n t h e s i s m o d e l

    Cornpocent

    Plow

    rate

    1

    -mol/h

    1

    H

    C 6

    c02

    C B

    H20

    CH

    C ;

    Ci30K

    N

    Feed

    t empera tu re

    Feed p ressu re

    57 , 2 4 1

    1 ,528

    28,630

    13 , 5 9 4

    388

    92

    541

    0

    0

    100°F

    508 p s i a

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    2 6

    2 , 4

    MTG

    MODEJ.,

    The b a s i s f o r p ro d u ci n g g a s o l i n e

    from synthesis

    gas v i a

    methanol

    i s

    t h e Mobil methanol- to-gasol ine

    (MTG)

    p ro c e s s - T n i s p r o p r l e t a r y p r o c e s s

    u s e s a z e o l i t e c a t a l y s t t o c on ve rt m.tljPai101 to l igh t 1 . iqu i .d fue l s

    ( l i g h t e r t ha n

    about

    C ) and some l i g h t , gases. Because of t h e

    p r o p r i e t a r y n a t u r e of

    Che ~ P O C ~ R R , ery 1 i t t l . e i s

    known about

    the

    MTG

    s y a t h e s i s r e a c to r i t s e l f . A produc t yPe1.d s t r u c t u r e

    f o r

    t h e r e a c t o r

    was

    taken from Schreitner. Other process d e t a i l s

    were

    t aken from b m nd

    Lee

    and

    from

    S d o v e r .

    1 0

    9

    1 3 1 1

    The process f l o w d iagram used fo r the s imu la t ion o f the MTG, f r a c -

    t i o n a t l o n , and a .l k y l ac fo n s e c t i o n

    i s showr, i n

    P ig .

    11.

    The f e e d t o

    t h e u n i t i s h e a t e d a g a i n s t t h e

    reac tor

    e f f l u e n t , m i x e d

    w i t h

    Light,-gas

    r e c y c l e , and f e d t o t h e r e a c t o r . The r e a c t o r i s assunzed t o be

    t h e

    Luxgi . - tubular typep

    and

    t h e h e a t

    of

    r e a c t i o n i s used t o g e n e ra t e

    steam.

    T h e r e a c t o r e f f l u e n t i s coo led t o p roduce a

    three.-p'taase mixtinre

    of gaso-

    l i n e , w 2 te r , and l i g h t

    gases:

    (1) t h e gases are

    recycled

    t o t h e r e a c t o r ;

    ( 2 ) the water i s

    s e n t t o was tewate r t rea tmen t ; and 3 )

    the

    g a s o l i n e i s

    sent t o t h e g a s o l i n e f r a c t i o n a t i o n s ec t do n .

    T h e f r a c t i o n a t i o n s e c t i o n I s of

    t he

    st an da rd two-column des ig n,

    producing l i g h t

    gases (C2 - j ,

    a

    stabillzed gasc,l.ine

    C5 - t - ) , and a n a l k p l a -

    t i o n f e e d e3.

    w t t h o u t

    f u r t h e r t r e a t m e n t .

    'l"ne

    a l k y l a t i o n f e e d

    i s

    mixed

    w i t h

    t h e i s o b u -

    t a n g

    r e c y c l e stream and f e d t o th e a lkg7latPon

    reactor .

    The alkylat : i .on

    s t e p reac ts u n s a t u ra t e s w i t h Ls o al k an e s t o

    produce

    h igh-oc tane gaso l ine

    by

    t h e r e a c t i o n s :

    Il r\e g a s o l i n e can be

    s en t

    t o gaso?.ine b l e n d i n g

    5

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    28

    c B +

    i-B:

    M

    +

    3 6 4

    1 0

    C7H1

    s

    C,,H8

    -f-

    i-c

    I I

    +.

    c 1

    ‘c

    1 0

    8

    1 8

    I-

    i -c

    1-7

     

    c

    K

    0 ‘4 1 0 9

    2 0

    1.

    1

    Tt

    i s c o rn o n p ra c t i c e t o r e c y c l e l a r g e amounts

    p o l y me r i z a t i o n a nd t o e n s u re

    complete

    c o n v e r s i o n

    of i s sbs l t ane t o p re v e n t

    of t h e u n s a t u ra t e s .

    The

    a l k y l a t i o n p ro d u c t 9s s e n t

    t o a

    two-column f r a c t i o n a t i o n system t o

    recover the unreacted isobutasie f o r r ecyc le , t h c a l k y l a t e f o r g a s ol i ne

    b lend ing , as well as

    C 3

    and (21,

    product

    sL;r%ams.

    The

    ASPEN block diagram f a r t h i s s i r n i l a t i o n i s shown i n

    Ffg.

    12.

    The o v e r a l l s e c t i o n c o n t -a i m r e a c t o r s , h e a t exchangers, and d i s t i l l a t i o n

    columns.

    The Grayson-S t reed co r re la t ion

    (SPSOPZ)

    i s

    used

    f o r vapor-

    l i q u i d e q i i l l i h r ia c a l c u l a t lo n s . Gragson-Streed i s adequa te

    f o r

    t h i s

    uni t :

    s ince

    the compounds

    haadlied

    a re

    p r t m r i l y

    l i g h t l i q u i d hydrocarbons .

    The ASPEN r e a c t o r model RYIELD i s used t o s i m ul a te the MTG s y n t h e s i s

    r e a c t o r , based on yield data froisn

    Schreiner .

    e q u i l i b r i u m

    reactor

    model could no t be

    used

    because the ac tu a l re ac t io ns have not been

    p u b l is h e d ; i n

    addition,

    a s h a p e - s e l e c t i v e z e o l i t e catalyst

    which

    skews

    t h e product slate has been used i n t h e process.

    The

    R Y I E L D model quan-

    t i t a t i v e l y c o n ve rt s t h e f ee d methanol t o g a so l in e and l i g h t e r p r o d uc t s

    u s i n g the f i n a l p ro du ct d i s t r i b u t i o n as pub l i shed

    by

    Hobil. A s e r i o u s

    l i m i t a t i o n of t h i s model i s that t h e reactor

    is

    based on a s i n g l e

    p r u d u c t d i s t r i b u t i o n ,

    obtlalned

    a t Mo b i l ‘ s “ p re f e r r e d “ o p e r a t i n g

    c o n d i t i o n s . Therefore, v a r y i n g r e a c t o r tempesattnre a n d p re s s u re may

    g i v e

    e r r ~ n e o u f i

    results.

    The

    modcl

    is a d eq u at e f o r e a l c u l a t i n g heat

    d u t l e s p r o d u c t r e c o v e r i e s ,

    etc .

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    31

    MTGGASBL

    F i g . 1 3 . ASPEN block f low

    diagram

    of

    fractionation

    s e c t i o n .

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    3 2

    O N , WG 8 2 - l 4 5 2 R

    M G C 3

    IBUTRECL

    GASPROD

    MIXER

    TGGASBL

    GAS

    LPGPRBD

    HIXER

    l

    P i g .

    14 .

    ASPEN bl.ock diagram of alkylation sec t ion .

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    O A N L

    DWG

    82-12898

    N m n T n A

    HYDROTREATER

    PRESSOR

    60 N

    DENSATE

    METHANOL OFF-GAS

    Fig .

    '15.

    Process f l a w diagram

    of methanatton

    s ec t i o n .

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    35

    u n i t . In t h e me th a n at io n u n i t , 6 8 , C82 , CII30H, and

    w i t h hydrogen t o form CH4 and water in t w o r e a c t o r s

    eo -t- 3112 f C l t 4 f B20

    C2Rg + H 2 8 26H,

    CH30W f H2

    CMq

    -4- H2Q

    coz

    +

    4a, f CBq -4-

    2H20

    The f i r s t r e a c t o r reacts most of t h e 60 ,

    CR301-2,

    and

    C ~ R P J are r e a c t e d

    as fo l lows :

    C2Rg wit h hydrogen,

    a nd t h e s e co nd r e a c t o r e s s e n t f a l l y c o m p le te s t h e s e r e a c t i o n s a nd r e a c t s

    C O 2 w i t h the remaining hydrogen, In bo th th e sh iE t and the methanat ion

    se c t io ns condensers remove

    water

    f rom

    the

    r e a c t o r e f f l u e n t

    The ASPEN

    block

    f lo w dia gr am f o r t h e s h i f t u n i t s i m u l a ti o n

    1s shown

    i n Fig .

    17.

    The purge gas from th e methanol sy nt he s i s

    ks

    s p l i t b etw ee n

    t h e s h i f t a r e a and t h e m t h a n a t i o n area, A s p l i t of

    35 t~

    t h e

    shift

    u n i t has been assumed f o r t h i s s t ag e of deve lopmen t

    of

    t h e d e t a i l e d

    models . The amount of gas se n t t o th e s h i f t area w i l l depend on

    how

    much hydrogen

    i s

    needed

    and

    will

    be

    de te rmined concurren t wi th the

    o v e r a l l p l an t mass balance. The g as t o t h e s h i f t u n i t i s heat exchanged

    w i th r e a c t o r e f f l u e n t us tng ASPEN h e a t

    streams.

    The gas i s then mixed

    w i t h steam v i a a FORTRAN d e s i g n s t a t e me n t t o ach ieve

    a

    WpO-to-CO r a t i o

    o f 3:1 . The steam-gas mixture i s r e ac t ed i n

    an

    a d i a b a t i c REQUIL r e a c t o r

    t o a c h i e v e t h e

    CO

    and

    H 2 0

    c o nv e rs io n t o

    H2

    and C 0 2 .

    The r e a c t o r e f f l u e n t 1s hea t exchanged wi t h th e reactor f e e d I n

    HEATER block. The r e a c to r e f f l u e n t i s c o o l e d f u r t h e r by heat exchange

    w i t h b o i l e r f e ed

    w a t e r

    t o p ro d uc e

    steam.

    The u s e r s u b r o u t i n e BOILER

    d e t e rmi n e s how much bo i l e r f eed water

    i s

    r e q u i r e d t o p ro d u c e s a t u r a t e d

    steam a t

    a

    given pres sure . The gas i s c oo le d f u r t h e r i n a ser ies of

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    t

     

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    d

     

    H

     

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    b l o c k ; a

    FLASH3

    ASPEN block i s used as a condenser , and on ly

    the

    o rg a n i c

    phase i s r e f l u x e d a f t e r b ei n g h ea t e d

    by a

    HEATER

    block.

    The

    h y d ro t r e a t e d n a p h t h a

    w a s given

    a

    mo l e c u l a r

    weigh :

    o f

    S c hr e ine r , bu t no molecu la r welght w a s a s si g n ed t o t h e g a s i f i e r naphtha,

    I n

    t h i s s t u d y , a molecular weight of

    100 was

    ass igned t o t he

    gasifier

    naph tha and mzy bc ad jus ted i f

    more

    informatfon i s obta ined.

    The

    g a s i f i e r n a p ht ha a nd h y d r o t r e a t e d

    napb tha

    are e n t e r e d

    as

    user-def-ined

    components. E x c e p t f o r t h e m o l ec u la r w e ig h t, t h e p h y s i c a l p r o p e r t i e s

    a r e those of to luene bu t may b e a d j u s t e d

    as

    f u r t h e r in format ion dfc-.

    t n t e s , The b.dlfeh-)i(wong-Soave

    equa t ion o f

    s t a t e

    w a s used for vapor:

    l i q u i d e q u l l i b r i u m a nd e n t h a l p y

    calcul at

    ons

    I n t h e course of d e v e l o p i n g t h e ASPEN s i m u l a t i o n s ,

    %t

    was found

    n e c e s s a ry (or conveniiE.nt 1

    to

    w r i t e .

    some

    ~~~~~~ subroutines to perform

    some

    simple,

    r e p e t i t i v e

    tasks

    and

    to

    enhance

    the

    f l e x i b i l i t y and

    utility

    of the models.

    Two

    of these subroutines i.zser--yiel.d r o u t i n e s DE'UOJ,

    and

    IDECOMP,

    were

    descr ibed

    in

    t h e Lurg l

    gas j - f i e r

    section, The gasifiers

    also call three oth-er user S U ~ ~ O U ~ Z R ~ Sdeveloped hy a p r e v f o u s s t u d y

    1:

    (1) ENYHLU,

    Salrnic,h

    c a l c u l a t e s

    t he

    e n t h a l p y

    of ash a t

    any t e m p e r a t u r e ;

    ( 2 )

    ASH.I l ,

    w hi ch c a l c u l a t e s the e n t h a l p y of a s h s o l i d s a t a g i v e n tern-

    p e r a t u r e , and (3) S

    which ca lcu la t e s the

    average mohecular weighl:

    of a stream. U se r u n i t o p e r a t i o n s u b r o u t i n e B O I L E R a n the enhancements

    t o the

    coal enthalpy

    model

    ~ C O ~ X ~ ~ ~ ~

    re

    d i s c u s s e d

    in this

    section.

    4

    Ma i n t a i n i n g a n a c c u r a t e steam ba lance I s very impor tan t if

    usefiml.

    s i m u l a t i o n s are to be produced,

    User

    un i t ope ra t i on model

    BOILER

    was

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    4 5

    th e new su bro u t in e ENT445. S u b ro u t i n e ENT445 merely obtains

    the heat

    of

    combust ion from t h e

    component

    a t t r i b u t e v e c to r , c o nv e rt s th e u n i t s t o

    S I , a n d r e t u rn s the v a l u e t o ENTBCC.

    3.

    INTEGRATION

    OF

    MODELS

    A s

    can be s ee n i n

    Fig.

    I , most of the uni% o p e r a t i o n s present i n

    t h e T r l - S t a t e p r o j e c t f l o w sh e e t h av e been rmdeled u s fn g ASPEN. [Unit

    o p e r a t i o n s n o t modelea i n c l u d e head-end process ing s teps ; (such

    as

    coal

    p r e p a r a t i o n a n d the oxygen and steam p l a n t s ) a n d c leanup p ro c e s s e s (such

    as ammonia and

    s i l l f u r

    r e c o v e r y . ) ?

    m a t e r i a l and energy ba lances ,

    i t

    would now be des-irable t o c o u p l e

    a p p r o p r i a t e l y a11 of the deve loped models in t o a s d n g l e simi-ilation,

    P l a n t o u t p u t streams could t h e n

    be

    checked f o r v a r i o u s

    input

    feed and

    i n t e r n a l p r o ce s s c o n d i ti o n s

    e In t h i s w a y

    t h e

    process

    eff c i e n c y a n d / o r

    produc t s l a t e d e s i r e d c o u l d

    be

    op t imized f o r

    a

    particular coa l and

    o v e r a l l

    E l c l w s l i e e t

    e

    In o r d e r t o per fo rm o v e r a l l plant

    The coupl ing of a l l of

    these

    ASPEN models

    i n t o a s h a l e s3mula t ion

    program y i e l ds , however ,

    a

    computer program

    chat

    is qui te ccmplcx and

    o n e t h a t requfres a

    co n s l d e rab l e

    amount of

    care. Th ls

    problem has been

    circumvented by d i v id i n g t h e o v e r a l l flowsheet dnto suhsets, *9s shown

    i n Fig. 21, the v a r i o u s ASPEN m o d e l s have been combinied i n t o flvc

    m j o r

    groups: 1) h r g i gasifter, gas cool ing, g a s - l i q u o r s e p a r a t i o n ,

    arid

    T e x a c o g a s i f i e r ;

    ( 2 )

    k c t i s o l ; ( 3 ) raet l ianol synthes is W - s k l f t , metha-

    nation, and

    SNG

    p u r i f i c a t l o n ; ( 4 ) naphtha h y d r o t r e a t e r ; and (5) 'I.lohPE

    MTG, f r a c t i o n a t i o n , a l k y l a t i o n , and gasoline b lend ing . S e q u e n t g a l ex@-

    c u t i o n

    of these

    major groups s h o u l d a l l o w

    a v e ra l l

    p l a n t balances

    t o

    he

    achieved

    i n

    e s s e n t i a l l y

    a

    s i n g l e

    p a s s .

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    47

    4 .

    SULTS

    The f i n a l T r i -S t a c e S y n fu e l s P ro j e c t b l oc k

    f l o w

    d i a g r a m , e n t i t l e d

    **case

    3

    -

    coal

    t o G a so l in e

    -

    % a r t c r Size

    Plant , ' "12

    w a s

    used

    as

    t h e

    b a s e l i n e T r i - S t a t e case f o r

    checkfng

    the deve loped

    ASPEN

    models I n an

    o v e r a l l s h n i la t i o n p e r f o m e d

    by

    s e q u e n t i a l e x e c u t i o n of t h e ma jo r

    groups . To d e mo n s t r a t e t h e

    range

    of

    o p e r a b i l i t y of these models ,

    overall

    s i mu l a t i o n s were also performed

    us ing

    feed of I l l i n o i s No. 6

    c o a l a nd t h e o r i g i n a l f u l l - s c a l e f e e d r a t e

    rsf

    Kentucky No. 9 c o a l to t he

    I:

    l a n t.

    4.1 BASELlNE TRI-STATE CASE

    I n the b a s e l i n e Tri-State case, 240 trans/h

    of

    Kentucky No. 9 coal

    w ou ld b e c o n v er t e d t o t r a n s p o r t a t i o n f u e l s and chemicals e The chemical

    a nd p h y s ic a l c h a r a c t e r i s t i c s of t h i s coal are g i v e n in Tab le 4. It

    s h o u l d

    be

    no ted

    t h a t

    the hydrogen and oxygen v a lu e s l i s t e d i n Ta bl e

    4

    i n c l u d e c o n t r i b u t i o n s f ro m t h e m o i s tu r e i n t h e

    coal.,

    so

    t h a t t h e u l t i m a t e

    a n a l y s i s I s on an "as - rece ived" bas i s . Th is form of t h e u l t i m a t e a n al y -

    s i s

    i s

    r e q u i r e d by the ASPEN model. Before a s i mu l a t i o n c o u l d b e

    per fo rmed ,

    i t was

    n e c e s s a ry t o matc h t h e ASPEN p re d i c t e d Lu rg i g a s i f i e r

    o u t p u t r e s u l t s w i t h t h e e x p e r i m e n t a l l y de t er m in e d o u t p ut o f t h e Lurg i

    g a s i f i e r u sed i n

    the

    SASOL

    t e s t of

    Kentucky No.

    9

    coa l '

    (see

    Appendix).

    This

    was accomplished i n two s t e p s : ( 1 ) by v a r y i n g t h e

    REAL

    v e c t o r

    s p e c if i e d i n the ASPEN i n p u t f i l e a nd us ed by t h e s u b r o u t i n e DEVOL t o

    form

    the v o l a t i l e p r o d u c t s , a nd ( 2 ) by vary ing the t empera tu re a t which

    t h e f o l l o w i n g f i r s t two r e a c t i o n s of t h e REQUIL

    block

    took p lace :

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    4 8

    Tab le

    4.

    C h c a i c a l

    and

    p h y si c al c h a r a c t e r i s t i c s

    of Kentucky No. 9

    coal .

    UI imare a n a l y s i s (as r e c e i v e d coal)

    Ash

    Carbon

    Bydrogerf

    Ntt rogen

    S u l f u r

    oxygen

    P r oximat s analy8

    s

    Mois t u r c

    Fixed

    carbon

    V o l a t i l e

    matter

    Ash

    15 . 4

    5 9 . 6

    5.3

    1.2

    3.5

    15.0

    100.0

    x

    8 . 2

    43.4

    33 .0

    15.4

    100.0

    Sen t of combustton

    =

    1? , 4 7 5 B t u / l b ( d r y e o a l )

    CO

    + H2Q -$ H 2 -b CO2

    co

    4-

    3 H 2

    *

    CHq

    4-

    H26)

    A comparisorz of the experimental and p r e d i c t e d g a s t f i e r r e s u l t s

    (using

    1620 and

    141OoP,

    respectfveiy, f o r

    t h c t w o r e a c t i o n s above) i s shown in

    Table 5.

    ’l”ma agreement is q u i t e

    g o o d ; fu r t h e r

    ref inem ent of the REAL

    v e c t o r and/or t h e r e a c t i o n t empera tu res could make i t e v e n b e t t e r . Prom

    t h e

    SASOL

    co a l tes’r, the amount of tar, C2+, and

    phenol formed

    were

    known,

    S l n c e

    these c o ~ p o n e ~ t sr e o n l y

    formed

    i n t h e s u b ro u t in e DEVOL,

    t h e i r Vector values r t 3e r e

    e a s l l y

    deter1114

    ed.

    L-I

    a d d l t i o n , t h e water vec-

    tor v a l u e

    was

    s e t t o a c co u n t f o r

    the

    amount of w a t e r i n d i c a t e d by

    the

    c o a l

    proxjmate analysis.

    r e mal n in g v e c t o r v a l u e s ( fo r N2, @ H q ,

    CO,

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    49

    Table 5. L u rg i g a s i f i e r o u tp u t u s i n g Kentucky No.

    9 coal

    Mode1 SASOZ c o a l t es t

    --

    Clean

    t a r

    produced

    as

    X

    W

    c o a l

    fed: 5.6

    5 6

    Dry gas composition, X

    Wy

    rogen

    41.4 40.8

    Carbon monoxide

    15.4 15*9

    Carbon

    d iox ide

    30,8 30.6

    Methane 9 .

    P . 4

    C 2 +

    0.9

    0 * 9

    N i t ro g e n

    1.0

    8,9

    Hydrogen su l f ide

    1,4 1.5

    100.0

    100.0

    and CO,) w e r e

    se t

    t o

    make

    t h e t o t a l v e c to r

    sum

    t o u n i t y w h i le s l mu l ta -

    n e o u s l y t h e y

    w e r e

    m a ni pu la te d , a l o n g w i t h t h e r e a c t i o n t e m p er a t u re s , t o

    match the coal

    t es t

    d a t a .

    The

    f i n a l v e c t o r s o b t ai n ed were 0.0072,

    0 .2863 , 0.340Q,

    0.0131,

    0 .0849 ,

    0.0915,

    0.0036,

    and 8.1734 f o r t he f o r -

    mat ion of

    H,,

    c=Hq H,O, 6 0 , C2+,

    60

    phenol , and

    t a r ,

    r e s p e c t i v e l y .

    2’

    I n t er m e d ia t e r e s u l t s

    of

    s e q u e n t i a l e x ec u ti o n o f the major groups

    shown

    i n Fig .

    21. are

    g i v en i n T a b le

    6.

    The o u t p u t of t h e f i r s t

    major

    group c o n s i s t s

    of

    t h e

    cooled

    g a s e s f ro m t h e

    Lurgi

    a n d Te x a c o g a s i f i e r s

    and i s t h e i n p u t

    t o

    t h e R e e t i s o l

    model. The C O S , NTl[3,

    and

    C2-C4

    o u t p u t

    streams

    w e r e

    n o t i n p u t t e d t o t h e R e c t i s a l mod el b ec a u se t h e y h av e n o t

    y e t b een i n c o r p o r a t e d i n t o t h a t

    model

    ($.e., b i n a r y i n t e r a c t i o n p a ra m e te r s

    for

    t h e s e s p e c i e s

    were

    not

    a v a i l a b l e ) .

    amount

    of

    naphtha e n te r i ng rthe second major group. Since ( 1 ) t h e SASOL

    The

    C6H6

    e n t r y r e p r e s e n t s t h e

    c o a l

    t e s t s

    d i d n ot i n d i c a t e t h e f o r m a t io n

    of any

    naphtha, and

    ( 2 )

    t h e

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    50

    ZaZ11-. 6 .

    Interme3iate

    simulat. o n r e s u l t s f o r b ase 1 i n e T r i- S ta t e

    case

    G a s i f i e r a n d

    &OH synthesis

    c o o l i n g o u t p u t , K e r t i s o l o u t p u t ,

    o u t p u t ,

    MTG

    Rectisol i n p u t

    MeOH

    s y n t h e s i s

    i n p u t j.

    np

    u t

    Coiiiponcnr (

    1

    -mo

    1

    h

    1

    (Ib-moP/h)

    ( lb -mol /h

    )r

    16,583

    11,823

    7 , 6 6 0

    3,460,

    100

    418

    333b

    j i i

    6a

    173

    41

    -

    1 4 , 5 3 2

    7 , 5 5 1

    1 , 4 4 1

    3,306

    . -

    -

    4 L2

    0 . y

    0.4

    0.7

    120

    13

    -

    0.2

    -

    O u t p u t

    stream

    component,

    b a t not u se d i n i n p u t stream.

    MeO H s y n t h e s i s =

    ( 5 3 4 4

    lb--mol/h)(32 ,042

    l .b/lb-mol)

    ( 2 4

    h/d3/(2000

    h s e d as an i n p u t s t r e a n only .

    e

    1 b / t o n ) =

    2670

    t m s / d ; MeOh s y n t h e s i s from CasP 13

    Flowsheet

    = 2670

    t 1 7 s d .

    Case

    13 f l awshee t

    shows

    naph tha

    €rota

    t h e

    k c t i s o l .

    u n i t be ing fed

    t o

    t h e

    Tewaco g a s i f i r : r , the f o u r t h

    major

    group, nap htha hydrotreat- ing , has been

    o m i tt e d i n

    t h i s

    o v e r a l l

    sirraillation.

    The

    s i x

    L4DPRC blocks i n

    the

    ASPEN B e e t i s o l modal are

    shown

    in

    F i g . 8. The first two

    of t h es e d i s t l l l a t i o n u n i t s

    are

    used

    t o

    remove

    t h e S i mp u r i t y , w h t l e t h e r e ma i n i n g u n i t s are u s e d p r i ma s f l y t o

    recover naph tha frvlln t h s s y n t h e s i s gas stream. 10a c t u a l ASPEN s imula-

    t i o n s ,

    a l l

    of these

    RADF RC

    b l o c k s c o n v e rg e d i n d i v i d u a l l y , b u t o v e ra l l

    2

    convergence of t h e e n t i r e f l o ~ h e e t :

    as

    very d i f f i c u l t t o o b t a i n .

    NUDE~GUS a t t e m p t s were made t o a c h ie v e convergence of the right h a l f

    of

    t h e f lowsheet (Fig . 8) by (1 ) b re a k i n g the

    t i e s between

    t h e t w o h a l v e s

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    51

    of t h e f l o w s h e e t elg. streams R E C W 1

    RECLIQ2,

    and

    ~~~~~~~~~~

    and

    ( 2 ) r e p l a c i n g

    he RADFRC

    blocks by sLmple

    SEP

    b l o c k s , i n d i v i d u a l l y

    and

    in varying

    combinat ions

    Unfortunately

    n e i t h e r o f these approaches

    a i d e d t h e c o n v e rg e n c e p ~ o b l e ms e r e

    were

    some fnd ica t ions however ,

    that

    t h e c o n v e r g e n c e d i f f i c u l t i e s could be

    t race

    t o WO i n n e r loops in

    t h e r i g h t hal f

    of

    the flowsheet* T h s e

    inner

    loops are d e f i n e d by

    the

    following: ( I )

    streams RECACIDG, ~~~A~~~~

    REGVAPPT, E C L I Q 1 9 ,

    and

    ~ E ~ ~ A ~ 1 8 ~nd (2)

    streams

    R E C L E Q l 7 , R.ECLTQ18, and ~ ~ ~ ~ ~ ~ear ing

    stream REcVM-as -might e o n f t r m

    .if

    t h e s e l o o p s

    are

    indeed t he souT(le o f

    t h e c o n v e rg e n c e p ro b l e

    The number of i t e r a t i o n s was

    cot

    i n c r e a s e d

    above

    the

    default

    v a l u e s

    because

    t h e

    hPstory

    f i l e d i d

    nor

    i n d i c a t e

    that

    t h e

    maximum

    number of

    i t e r a t i o n s was bei ng approached . However, more i r r a t lo i a s and/or t h e use

    of

    d i f f e r e n t c o n v e rg e n c e schemes c ou ld be t r i e d t o see i f any

    inprovement

    c o u l d be made. For t h i s s im u la t io n , only

    the

    f i r s t t w o W F R C

    blocks

    were used. T h i s w a s r e a s o n a b l e s i n c e all. of

    the H2S

    i s removed from the

    gas stream by t h e s e f i r s t two blocks, while t h e

    remaining

    b locks are

    p r i ma r i l y u s e d to rec ov er naphtha. Sfmce th e

    SASOL

    coal

    t e s t

    d i d n o t

    I n d i c a t e t h e f o r m a t i o n

    of

    any n a p h t h a , t h e use of the remain ing W P R C

    blocks w a s no t cons idered

    essential.

    he

    entire

    ASPEN

    language I s

    i n cl u d ed i n t h e in p u t f i l e , b ut t h e r i g h t hal f of t h e flowsheet shown Pn

    F i g . 8 ha s been commented ou t. These

    could

    be used by anyone d e s i r i n g

    to check the recovery

    of

    t h e n ap ht ha i n t h e s y n t h e s i s g as stream.

    The output front t h e Rec t i sa l u n i t , w i th i t a mch reduced content of

    H25

    and COz, is f e d i n t o

    the

    t h i r d

    major

    group : methanol sy n t he s i s ,

    s h i f t , and methana tion . The pr ed ic t ed amount

    of

    methanol produced,

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    52

    2 6 7 0

    tons/d, was forced

    to agree closcly with

    t lw 2670 tons/d

    shown

    on

    t he Case 13

    flowsheet by

    varying

    t h e

    rt.,cyele r a t i o

    in

    the methanol

    s y n t h e s i s a o d e l - To obtahn

    agreement,

    a recycle

    r a t i o

    o f

    1.63 was used.

    The

    predicted composition and

    pate of

    SNG

    prod;ic23ui-t a re

    shown

    in

    Table 7 ,

    d o n g w i t h the ~ u t p t s f the

    fifth najor

    groixp

    (MTG,

    fractionation, and

    alkylation).

    The ASPEN

    block diagrams shorn

    in

    Figs. 13 and 14 f o r t h e frat-

    tlonation and

    alkylat- ion sections,

    respecttvcly

    use several

    RlhDPRC

    distillation blocks .

    Ac;

    was

    t h e

    case

    for the Rect i soP model, these

    RBDFRC

    blocks

    can

    be

    made

    t o

    converge

    indtvPdually,

    b u t

    are

    very

    d i f -

    f i c u l t

    to

    converge when

    p a r t of the overall.

    f lowshee t*

    ?%is, in these

    Table 7.

    Predicted o u t p u t s

    f o r

    baseline

    T r f - S t a t e

    case

    ------ _I

    produc tton Model Case 13

    Flowsheet

    S NG, MNSCFI)

    LPG, l b / h

    I s o b u t a n e ,

    lbJh

    GasolPne

    l b / h

    Component

    Tota l

    39.5

    4 , 3 0 0

    8 5 , 4 0 0

    1 -mo

    I h.

    30.7

    205.7

    1.2

    4,104.2

    4 ,341 .8

    37-0

    4,300

    4 , 7 5 0

    85,600

    0.71

    4 - 7 3

    0.03

    94 .53

    100.00

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    5 3

    s i m u l a t i o n s t h e KmFRC blocks have been replaced by simple SEP blocks

    which requfre no i t e r a t i v e c a l c u la t i o ns

    u s i n g t h e r e s u l t s o b t a i ne d when t h e a p p r o p r i a t e i n d i v i d u a l

    w a s used. The ASPEN

    input

    f % l e developed

    i n

    thBs work, however , conta ins

    b o t h t h e

    SEP

    blacks

    and the original RADFRC blocks , wfth t h e l a t t e r

    being commented out.

    use

    a l l

    or

    p a r t

    o f

    t h e RADPRC

    blocks,

    along w i t h two

    specaa l

    FOR

    b loc ks (ETSPEG and GSSPEC) u s e f u l f o r s e t t l n g t h e pr od uc t f l o ws a t es

    from

    blocks PIDEETHAN

    and

    MGASST

    (see Pig.

    13).

    "I'laese blocks

    were

    c a l i b r a t e d

    If d e s i r e d ,

    a

    user could remove the comments and

    The

    s i m u l a t i o n p r e d i c t s t ha t:

    39.5

    MPI

    SCFD

    af

    SNG,

    contaitihng

    94.5

    methane, w i l l be produced.

    SCFD shown on t h e Case

    13

    f lowshee t .

    The

    models p r e d ic t t ha t 4760 Ib/h

    This

    value compares favor ably wi th th e 37 MM

    of i sobutane

    i s

    formed (stream XSIBUT on F4.g.

    1 4 ) ,

    which i s 0,2X

    higher

    t ha n the f lowske et va lue of 4750

    lb /h .

    The p r e d i c t e d g a s o l i n e v a l u e

    (stream GAS on Fjg.

    1 4 )

    o f

    85 ,40 l b / h

    i s 0.2X less

    t ha n the f lowshe e t

    v a l u e

    o f

    85,600

    l b f h .

    The pred ic ted LPG produc t ion i s f d e n t i c a l

    to the

    f lowshee t va lue of

    4300

    lbfh. These

    predicted

    produe t

    ra tes

    w e r e

    o b t a h e d by m od if yi ng t h e y i e l d s t r u c t u r e u se d

    f o r

    the

    MTG

    r e a c t o r

    so

    t h a t t h e LPG,

    isobutane,

    and gaso l ine produc t

    ra tes

    would match the

    Tr i - S ta t e f l owshe e t .

    This

    T ri -S ta te y k l d s t r u c t u r e

    i s

    shown In Table 8.

    When t he y i e l d s t r uc tu re g iven by Schreiner9 and shown

    i n

    Table 9 w a s

    use d , t he p r oduc t ion

    ra tes

    p r e d i c t e d

    by

    the models

    were

    changed con-

    s i d e r a b l y ,

    as

    Shawn

    in

    Table

    10.

    It

    should

    be

    n o t e d t h a t

    a

    s l i g h t

    e r r o r

    w i l l oc cu r i n t he a tom bala nc e a round th e r e a c t o r when e i th e r of t h e s e

    y i e l d s t r u c t u r es are used . This e r ro r

    i s

    caused by lumping a l l

    of

    t h e

    products beyond C g i n t o a s ing le - te r m l a be le d ga so l ine and the n

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    a

     

    m

     

    N

     

    u

    2

     

    0

     

    L

    Q

     

    A

    r

    n

     

    g

    v

     

    n

    m

     

    n

     

    e

    m

     

    m

     

    O

    r

     

    N

     

    4

     

    N

    a

     

    4

     

    ~

    h

     

    0

     

    l

    0

    0

    0

    0

    0

    0

    8

    0

    0

    0

    0

    0

    0

    0

    N

     

    o

    m

    o

    o

    o

    o

    o

    o

    o

    o

    o

    o

    o

    o

    o

    o

    8

     

    a

     

    a

     

    P

     

    9

     

    3

    1

     

    d

    d

    d

    d

    d

    d

    d

    d

    d

    d

    d

    d

    d

    d

    d

    d

    d

     

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    Schreiner

    y i e l d T r i - S t a t e ytelnz

    Prcrdlact:ican

    S

    :

    TU

    ct

    re seructure

    assigning this pseudocomponent the p r o p e r t i e s of n-heptane a If these

    higher

    moleanlar

    weight products were not

    combined,

    however, an

    addi-

    tional 31

    components

    w o u l d

    have

    t be alsed

    i n

    t h e

    r P t d n d e r

    of tile

    simulati@ln. us ing Schre iner

    s yfeld

    s t n x t u r e 9 the predfeted aaollint of

    gasoline produced is eonsfderably reduced, w h i l e the p r e d i c t e d m o u n t

    of

    isobutane and LPG

    produced

    are larger,

    Thus

    the bas ic d:EEfererzce between

    t h e

    t w o y h l d s t r u c t u r e s

    has been to

    shift

    produet format ion toward the

    higher carbon ( $ . e . * gasalFne) end of t h e

    groc3uc.t

    s l a t e .

    4 .2 FULL-SIZE TRP-STATE

    CASE

    I n

    t h e f u l l - s i z e Trl -S tace case9 960 t o n s of coal. per 11oer1- would

    b e f e d to tbe

    L u r g i

    gas t f i e r . This case was sIwul.ated to ensure that

    the d e v e l o p e d could opera te

    over

    a range of flow

    rates.

    e

    intermediate s i m u l a t f s n results are shown

    in

    Table 11. ~o~~~~~~~~ with

    Table 6

    shows that each

    component of

    t h e

    gasifier o u t p u t

    streams have

    been increased by a f ac tor of 4 , the same factor t h a t

    t h e

    coal

    f e e d

    rate

    h a s been increased, Similarly, t h e Kect isol o u t p u t

    streams

    have been

    Increased by a f a c t o r of

    4

    as cornpared to

    Table

    6 , Tne R s c o n t e ~ ~ tf

    2

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    56

    66,334

    30 , 6 41

    4 7 , 2 9 2

    1,571

    2 ,044

    2

    5u

    593,

    245

    6h9

    31

    3 0 , 2 0 4

    1 3 , 2 2 2

    5,764

    -

    -

    1,647

    a

    2.8

    1.6

    2 .8

    481

    54

    -

    -

    1,138

    27 ,

    me

    the

    gas

    stream has

    been

    reduced

    by

    99.867: so that t he t o t a l gas stream

    c o n t a i n s orrly 24 ppm H S

    i s

    a l s o a factor

    of i~ t.lmes ehe baseldne case? v a l u e

    of

    2670 tons /d .

    '%he

    amount

    of

    n e t h a n o 1 produced, 10,680 tnns/d,

    2

    The pred i c t ed product r a t e s f o r t h f s case are shown I n

    Tab1.e

    12.

    A s w o u l d be

    expected,

    since ethanol i s being converted t o g a s o l i n e , the

    preddr t e i l

    g as o l i n e p r s d u c t I o n r a t e

    of

    341,6363 l b / h f s 4

    t f w s

    the base-

    l i n e

    val.ue

    cf

    85 , 400 Ib /h . The

    est imzited i s o b u t a n e ,

    SNG, and

    LFG ra tes

    are

    a l s o

    4

    t i m e s

    the

    baseline

    va lues .

    Thus

    the

    change i n

    coal

    f e e d

    r a t e

    p r o p a r t I o n a P l y

    changed

    a14 the o u t p u t p ro d u c t rates , showing

    tihe

    rangeability of the ASPEN

    models developed

    i n Lhis s tudy .

    Demonstrating such

    v e r a a t - l l i t y

    and

    range

    of

    o p e r a b i l i t y

    i s

    very

    Impor tan t f o r any process simulation s i n c e

    it

    shows i f the wnsde.1~

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    5

    7

    Table 12. P r e d i c t e d o u t p u t s

    for

    f u l l - s i z e T r i - S t a t e

    case

    Produc t ion

    Model

    SNG, MlMSCFD 158

    LPG, l b / h 19,200

    Gasol ine ,

    l b / h 341,600

    I sobu ta ne , l b /h

    SWG

    u

    l b V O l / h

    x

    elm

    omponent

    H2 118

    0.68

    N 2 822

    4.74

    CO 5

    0 03

    C R 4 16,376 94 55

    T o t a l

    1 7 , 3 2 1 100"80

    Meat

    of combustion

    (HHV) =

    956

    Btu/SCF

    __

    developed have

    been

    s u f f i c i e n t l y g e n er a li z ed . In t h i s case, s p e c i f i c

    values

    f o r

    c e r t a i n

    feeds, splits, and

    o u t p u t s

    w e r e

    r e p l a c e d w i t h r a t i o s ,

    o f t e n u s in g

    FORT

    b l o c k s t o

    set

    i n i t i a l

    estimates.

    Similar

    te s ts

    of

    any

    new models t h a t

    are

    developed should

    be

    made

    t o

    a s s u r e g e n e r a l i t y .

    4 . 3 ILLINOIS No. 6 FEED

    I n o r d e r t o d em on st ra te t h e v e r s a t i l i t y of the ASPEN models developed

    i n t h i s s t u dy , t h e b a s e l i n e T r i- S ta t e

    case ( i r e .

    240

    tons of

    c o a l f e d

    p e r

    hour )

    was s i mu l at ed u s i n g I l l i n o i s

    N o *

    6 coal

    as

    f ee d t o t h e

    Lurgd

    ga s i f i e r . 'She c hemica l and phy s i c a l c h a r a c t e r i s t i c s of t h i s c oa l , shown

    i n Table 13, w e r e taken from t e s t data.

    16

    Table 14 shows that the composit ion of t h e

    d r y gas produced using t he

    Illinois N o . 6

    c o a l , u s i n g

    the same R E f i vector a d reaction temperatures

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    58

    Table

    13. Chemical

    and

    physical

    characteristtcs

    o f 11

    1.j-noE.s

    Ma. 6

    coal.

    Ash

    C a

    a-?ron

    Hytl w g e

    Nitrogen

    S u l f u r

    Oxygen

    9.0

    64 .3

    5.5

    1.2

    2.8

    17.2

    100.0

    Pro s im a t e ana s s

    x

    Mo

    i

    turn

    Fixed

    carbon

    V o l a t i l e natter

    Ash

    10.3

    46.0

    34. 7

    9.0

    100.0

    Beat of combust-ion = 12,770 B t u / l b (dry c oa l )

    1111

    _ ..I.....I

    ___ ___.

    TabLe 14 , L ur gi g a s i f i e r o u tp u t u s i n g Illinois Nae 6 coal

    as

    compared

    to Kentucky No. 9

    coal

    14.1..

    No. 6 Ky. No.

    9

    coal.

    coal

    Clean &ar produerd ,

    as

    MAF coal f e d :

    Dry

    gas composi t ion, %

    Hydr ogeri

    Carbon

    momxide

    Carbori d i o x i d e

    Methane

    c 2

    -1-

    N i t rogen

    Hydrogen sulfide?

    5.9

    4 0 , 3

    16.0

    30.

    '7

    10.0

    1 0

    1.0

    1.0

    5.6

    41 .4

    15.4

    30.8

    9 . 1

    8.9

    1.0

    1.4

    100.0 100.0

    ~ ..

    .̂.,...

    _._

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    59

    as

    previously,

    is ve r y sfrnllar r a

    t ha t p r e d i r t x d

    for the Kentucky

    No,

    9

    coal,

    the Tl.lincis

    c o a l ,

    while a

    s l i g h t l y

    lower pereenmge o f kydrogen i s expected,

    Because

    of its lower sulfur e m t e n t ,

    the

    amoan: of BzS predicted i s

    c ons ide r a b ly

    less ttiian that predtcted

    u e b g the

    Kentucky 9 coal.

    Higher percentages of

    carban

    mc~noxideand aaetha-tae a r ~r e d i c t e d for

    The

    i n t e r m e d i a t e

    simulation resulss re shewn

    in Table

    15.

    X

    c o w

    parison with Table 6 shows that the

    g a s i f i e r

    asintputs are

    very

    simflar

    a n d t h a t

    the

    Rect isol u n i t

    again remooes

    over

    99% of

    the

    B2S from

    t h e

    gas

    stream. The fact that some HzS Ps

    p r e d i c t e d

    t o r e m k n gn

    the

    synthesis

    gas

    stream

    for

    each of these sinnuPations Pndicates

    t h a t

    zinc

    o x i d e

    p a r a

    b.as

    should

    probutaiy be

    ~ L X o

    E PBxPc31 syntbes

    s to

    a vo id pofsoning sf

    its

    c a t a l y s t , The pr-ed-lcted am u :~ t of me t Z~a no2

    pro-

    duced,

    2772 tuns/d is 3.8 greater thzera ?:Ire baselhue

    m ~ < ?

    alueR

    The

    estimated

    outputs;

    are

    given

    in

    Tab le

    16,

    Bison w el.1

    Table

    7 shows

    t h a t

    more SNG2 LPG, lisobaitarae, an

    g

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    6 1

    g a s i f i e r ,

    synthesis

    gas c oo l ing , R e c t i so l , me tha no l syn the s i s ; , methano l-

    to - ga so l ine ,

    @@-shift,

    n e t h a n a t i o n , and na ph tha hyd r o t r e a t ing . In addi -

    t i o n , an enhancement has been

    m d e

    t o

    ASPEN

    t o a ll o w

    for

    t h e d i r e c t

    i n p u t

    of

    c o a l h e a t

    of

    combust ion va l ues , and th re e

    FORT

    programs

    were

    de ve lope d t o hand le t he d e v o l a t i l i z a t io n and de compos i ti on of c o al i n

    dl

    g a s i f i e r a nd t h e h a nd l i ng

    of

    bojl ler feed water.

    S imula t ions

    were

    made of t h r e e c a se s :

    (1)

    t h e b a s e l i n e T r i - S t a t e

    f lowsheet with Kentucky

    NoI 9

    c o al fe d i n a t

    240 tons,%;

    ( 2 )

    a

    f u l l - s i z e

    Tr i -S ta te case wi t h Kentucky No.

    9

    c o a l f e d i n

    at 960

    tone/h; and

    ( 3 )

    t h e

    b a s e l i n e T r i - S t a t e

    case

    w it h I l l i n o i s k

    6

    c o a l f e d

    at 240 tons/h,

    P r e d i c t i o n of th e s yn th es is gas composi t ion produced by the h r g i

    g a s i f i e r was c a l i b r a t e d u s i n g t h e SASOL c o a l

    t e s t

    data . For t h e first

    case,

    t h e s i m u l a t i o n

    was

    f o r c e d t o match the p r odu c t ion

    ra tes

    of metha-

    n o l , LPG, i sobu ta ne , and g a s o l i n e as i nd ic a t e d by the T r f - S ta t e Case 13

    f lowshee t . This w a s accomplished hy (1) u s i n g a r e c y c l e ratio of 1 , 6 3

    i n

    th e methanol s yn th es is model , and

    ( 2 )

    modify ing the

    EaTG

    r e a c t o r y i e l d

    s t r u c t u r e . C ba dr up li ng t h e c o a l f e e d

    r a t e

    of t he f i r s t

    case,

    the second

    ease i n d i c a t e d t h a t e x a c t l y f o u r times as much SNG, LPG, i s a bu ta ne , a nd

    ga so li ne would be produce& The u s e of I l l i n o i s No.

    6

    coal

    i n

    the t h i r d

    case r e s u l t e d Pn o u t p u t s s l i g h t l y h i g h e r t h a n t h o s e p r e d i c t e d by

    Kentucky

    No.

    9 coal . The a n t i c i p a t e d i s o b u t a n e ,

    LPG,

    and g a s o l i n e pro--

    d u c t i o n

    ra tes

    are 3.8 h i g h e r f o r the I l l i n o i s coal, whi le t h e SNG pro-

    duction would be expec ted t o be 12%h ighe r .

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    6. REFERENCES

    3.

    4 .

    5 .

    6 .

    7.

    8.

    9 .

    10.

    11.

    12.

    13.

    Paul

    F. R.

    Kudol.ph,

    P. K.

    Hzrbes t , at id H. Vferrath,

    " G a s i f i c a t i o n

    of

    US--NestF_j-n1 and Eastern Coals in the Jnrrgi

    Ery-Ash

    and t h e

    B r i t i s h G a s j h r g i

    S1

    aggiwg G a s i f i e r s , presen%sd t the 4 th Annual

    Coal U t P I i z a t i s n Conference9 i%oust.oii,

    Texas,

    NOY.

    17-19, 1981.

    R.

    Salmon, M.

    S..

    E d w a r d s , and R.

    M.

    Whim, Pmduc t - io r l

    of

    MethmpzoZ

    a d

    Me-t ruriol-Related

    F u e h

    from

    Coal,

    OWL-5664

    (May

    1980).

    .Je C. SePover, '"Coal

    Conversfon t o

    Methanol Gasol ine and

    S NG,

    p r e s e n t e d

    at the

    31st

    -Annual AIChE bkctirng, Defrrc~it,

    Michigan,

    P*ejg,

    16-19,

    1981.

    T ~ i - S a t o

    ynfuel6

    Pmjec t

    Reviey Cont rac t 835504 , Tr E- S t a t e

    S y n f i . ~ I s ompany (June 1982).

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    1

    A b r i e f srimmary

    of

    the

    SP.SOL

    coal

    t e s t

    da ta is

    shown

    in Table 17.

    These

    d a t a

    represent a

    vary

    small

    p a r ' s

    of t1-r~

    overall

    r e p o r t

    and

    s l ~ o u l d

    not

    b e i n t e r p r e t a d

    as

    r e p r e s e n t i n g

    the d e s i g n

    condf

    t loras

    of

    t h e

    T r S - S t a t e pro.jec&, Extensive da ta and

    di-scuesiicptrc of

    t h e coal test

    ate

    i n c l u d e d

    i n

    the.

    DOE

    r e p o r t , ;mad i r t @ r e s t e d

    e a de r s re

    r e f e r r e d

    t o i t

    1

    The

    d a t a p r e s e n t e d in Tablc

    17

    wem-r. usedl to t leterndne the flow

    r a t e s of oxygen, steam, and

    water to

    the Lurgrh

    gasifier

    In thts

    simulation. In

    a d d i t i o n ,

    the average

    g a s i f i e r ouP:let

    t e mp e r a t u r e o f

    1030'F

    w a s

    used in

    t h e

    s imula t ion . Furt1-tc-c

    coa l

    r e s t r e s u l t s (i.ea,

    produet gas

    composition

    a n d

    acasunl: of

    clean

    t a r produced)

    wcrc prc~se i i ted

    e a r l i e r

    i n T ab le

    5.

    Ta b l e 17. Fec?d ra tes

    used

    I n SASOZ c o a l t e s t

    and

    L u r g i gasifier s imulat l rsn

    of

    b a s e l i n e "b"ri-State

    case

    Coal

    (MhI.')

    Ash

    Moisture

    15.9 0 ,764

    3 6 6 , 2 2 6 0 .74 i .

    3.2 0 . 154 7 3 , 5 7 6 0 , 1 5 4

    1 . 7

    (I*

    82 39,137 O e

    82

    ---.----

    T o t a l as r e c e i v e d c o a l

    20. E?

    479 ,039

    Oxygen

    S t e a m

    Wareer

    G a s i f i e r

    o u t l e t

    t e m p e r a t u r e OF

    8.6

    0 ,413

    197,741 0.413

    34 ,6 1.663

    796 ,864

    1.663

    7.7

    0.370

    177,337

    0 .378

    1000- 1060 1030

    65

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    ORNL

    /n.I-8611

    Dist Category UC-9063

    INTERPJAL DISTRIBUTION

    1-5.

    6 ,

    7 .

    8-12.

    13 I

    14-18 e

    1 9 .

    20.

    21

    2 2 .

    23

    a

    24 .

    2 5 .

    2 6 .

    27 - 31 .

    32

    e

    3 3 *

    34 *

    35 *

    36.

    3 7 .

    J. M . Begovich

    K. 7 .

    Canon

    J . H.

    C l i n t o n

    S .

    D.

    C l i n t o n

    B. D.

    Cochran

    E.

    D. Collins

    T .

    L .

    Donaldson

    P. w F i s h e r

    C . W.

    Forsberg

    R. K.

    Genung

    H a

    W

    Godbee

    M . V . H e l f r i c h

    J .

    R ,

    Hightower

    P.

    J .

    Johnson

    R , F

    Judksns

    J.

    A.

    K l e