+ All Categories
Home > Documents > Chemical Design Ethylbenzene

Chemical Design Ethylbenzene

Date post: 01-Mar-2018
Category:
Upload: afnanlion94
View: 230 times
Download: 0 times
Share this document with a friend

of 32

Transcript
  • 7/25/2019 Chemical Design Ethylbenzene

    1/32

    1.0 INTRODUCTION TO PRODUCTION OF ETHYL BENZENE

    1.5 PROCESS SELECTION

    In order to produce ethyl benzene as a desired product, there are a few process available which are

    by unique process of toluene, super fractionation of mixed aromatic hydrocarbon and alkylation of

    benzene with ethylene.The most suitable process for production ethyl benzene is alkylation of

    benzene with ethylene. This process produce high purity of ethyl benzene as a main product

    compared to other manufacturing process. Less of pure ethylene and benzene has been used in this

    process. This process also has low operating condition and the cost of production is lower than

    other process.

    1.6 REACTION SCHEME THERMODYNAMIC

    thyl benzene is produced by alkylation of benzene with ethylene, illustrated by the

    following chemical reaction!

    C"H"C#H$C"H%C#H%benzene

    ethylene ethylbenzene

    &enzene alkylation process, for the production of ethyl benzene, consists of three basic steps. The

    alkylation reaction takes place at high pressure and low temperature. Typically, ethylene!benzene

    molar ratios between '.(% and '.# are used. The reactor inlet temperature is controlled by recycling

    a small portion of the reactor effluent. In transalkylation step, in which poly ethyl benzene at

    presence of benzene are converted to ethyl benzene on a reverse alkylation process. Transalkylation

    takes place in a separate reactor. Then in separation step, in which unreacted benzene, poly ethyl

    benzenes and other components enter benzene recovery column and separated from each other. The

    bottom for the benzene recovery column is sent to a product column, where ethyl benzene of )

    **.*+ purity is taken overhead. or this reason # distillation columns has been used. The final

    product is obtained in liquid phase.

  • 7/25/2019 Chemical Design Ethylbenzene

    2/32

    2.1 CHEMICAL DESIGN FOR DISTILLATION COLUMN

    2.2 INTRODUCTION

    igure (! -istillation column T/'(

    -istillation column is use to produce high purity of liquid product at operating condition. 0ince

    this criteria is crucial, therefore a suitable distillation column need to be chosen wisely since it

    will effects the purity and amount of production. The purpose of T/'( is to separate the

    ethylbenzene others chemical in stream (1. 2s a result , ethyl benzene discharged from the top of

    T/'# as a liquid together with other light component. The bottom outlet of T/'# contains no

    benzene.

    STREAM 17

    FLOWRATE : 13,321.5 kg/hr

    COMPONENT :

    Benzene ,

    Eh!"#enzen$

    T%&"ene

    STREAM 1'

    FLOWRATE : 2(,3(5.)kg/hr

    COMPONENT : Benzene,Eh!"#enzene,

    1,(*+ Eh!"#enzene

    STREAM 1-

    FLOWRATE : 11 2(.5kg/hr

    COMPONENT :Benzene,

    Eh!"#enzene,

    1,(*+ Eh!"#enzene

  • 7/25/2019 Chemical Design Ethylbenzene

    3/32

    3ame 4nit eed Top &ottom

    50("6 50(76 50(16

    8apor fraction ' ' '

    Temperature 9 7/." 1(.$ ($%.$

    :ressure k:a ((' ('% (#'

    ;olar flow kmol

  • 7/25/2019 Chemical Design Ethylbenzene

    4/32

    =here

    xi ? concentration of component i in liquid

    phase yi ? concentration of component i in

    vapor phase @i ? equilibrium constant of

    component i

    The saturated component solved by using the 2ntoinneAs equation as follows !

    =here :sat ? saturated pressure in mmBg

    T ? Temperature in 9

    2, &, 9 ?2ntoineAs coefficient

    9omponent 2 & 9

    &enzene 7.'"$/7 (#*".*/ ##*.*("

    thylbenzene ".*%7(* ($#$.#%% #(/.#(

    (,$ diethylbenzene ".**1# (%11./( #'(.*7

    Table #.# ! 2ntoineAs coefficient

    or bubble point calculation at feed stream which is stream ("irst use Tb ? 7/."

    o9 5 /$"."@6

    :ressure ? ((' k:a ? 1#%.( mmBg

    or bubble point calculation at bottom stream which is stream (1

    irst use Tb ? ($%.$o9

    :ressure ? (#' k:a ? *''.( mmBg

    Component Xi, f %sat & mm'() *i *iXi,f&enzene 0.6244 618.$1 0.#49 0.468

    0.33#3 98.02 0.12 0.04

    (.$ 0.0381 1#.1$ 0.02 0.000#62

    Total 1.0 0.$08

  • 7/25/2019 Chemical Design Ethylbenzene

    5/32

    or dewpoint

    calculation at top stream which is stream (7

    irst use Tb? 1(.$

    o9

    :ressure ? ('% k:a ? 717.% mmBg

    #./ ! C4LI&DI4; 9>30T23T

    The equilibrium constant can be calculated as follows !

    Table 1 : Ki value for stream 16

    Component Xi, t %sat & mm'() *i *iXi,t&enzene 0.9943 #91.4 1.00$ 0.9993

    0.00$4 132.68 0.1# 0.00918

    (.$ 0 24.#2 0.03 0

    Total 1.0 1.00

    Component Xi, b %sat & mm'() *i +i, b&enzene 0.00168 4062.$8 0.00$ 0.0000084

    thylbenzen 0.8964 96#.3# 1.0#$ 0.96363

    (.$ diethylbenzene 0.1024 266.3# 0.30 0.030#2

    Total 1.0 1.00

    Component Xi, b %sat & mm'() *i +i, b&enzene 0.00168 4062.$8 0.00$ 0.0000084

    thylbenzen 0.8964 96#.3# 1.0#$ 0.96363

    (.$ diethylbenzene 0.1024 266.3# 0.30 0.030#2

    Total 1.0 1.00

    9omponent Ei, t Fi, t @i, t&enzene 0.9943 0.9993 (.''%

    thylbenzene 0.00$4 0.00918 (.7

    (.$ diethylbenzene 0 0 '

    Total (.' (.'

    9omponent Ei, f Fi, f @i&enzene 0.6244 0.468 '.7$%

    thylbenzene 0.33#3 0.04 '.((*

    (.$ diethylbenzene 0.0381 0.000#62 '.'#

    Total (.'

  • 7/25/2019 Chemical Design Ethylbenzene

    6/32

    Table 2 : Ki value for stream 17

    Table 3 : Ki value for stream 18

    #.$

    DL2TI8 8>L2T2LITI0

    Delative volatility,G is the volatility separation factor in vaporliquid system. In other

    words, it is the volatility of one component divided by the volatility of the other. The

    greater the value of G, the easier will be the desired separation. The relative volatility can

  • 7/25/2019 Chemical Design Ethylbenzene

    7/32

    be calculated between any two components in a mixture. &ased on @ values the relative

    volatility can be expressed as belows

    which is subscript L@ for light key and B@ is for heavy key.

    The component separated are called light key, which more volatile . The component more

    volatile than light key are called light key components and will be present in the bottom

    in small amount. The component less volatile than the heavy key are called heavy

    component and will be present in the distillate in small amount.5Heankoplis,#'($6. Light

    component is the component of feed mixture which is desired to be kept out of the bottom

    product while heavy key component is a component of feed mixture which is desired to

    be kept out of the top product. Thus, the selection of key component is as below!

    Light key ? &enzene

    Beavy key ? thylbenzene

    9omponent @ i, f G f

    &enzene '.7$% ".#"

    thylbenzene '.((* (

    (,$ -iethylbenzene '.'# '.("1

    T#"e ( : 0 "&e %r re4 1'

    9omponent @ i, t G t

    &enzene (.''% '.%*

    thylbenzene (.7 (

  • 7/25/2019 Chemical Design Ethylbenzene

    8/32

    (,$ -iethylbenzene ' '

    T#"e 5 : 0 "&e %r re4 17

    9omponent @ i, b G b

    &enzene '.''% '.''%

    thylbenzene (.'7% (

    (,$ -iethylbenzene './ '.#1

    T#"e ' : 0 "&e %r re4 1-

    The following approximation may be used to calculate the average relative volatility !

    =here is Gf ? relative volatility of light key to heavy key at feed of column

  • 7/25/2019 Chemical Design Ethylbenzene

    9/32

    Gt ? relative volatility of light key to heavy key at top of column

    Gb ? relative volatility of light key to heavy key at bottom of column

    9omponent GL@,B@ Gavg

    eed Top &ottom

    &enzene 5 L@ 6 ".#" '.%* '.''% '.$$7

    thylbenzene5B@6 ( ( ( (

    (,$ -iethylbenzene '.("1 '.#1 '.##$

    Table #.(#, G average value for all stream

  • 7/25/2019 Chemical Design Ethylbenzene

    10/32

    #.% DL4E D2TI>

    The minimum reflux ratio can be estimated by using the method of approximation

    evolved by 9olburn 5(*$(6 and the exact procedure of 4nderwood 5(*$16. The equation

    can be express as belows

    Gi ? relative volatility of component i with respect to some reference

    Dm ? minimum reflux rati

    Ei,d ? concentration of component i in the tops at minimum reflux

    is the root of the following equation

    xi,f ? concentration of component i in the feed

    q ? depends on the condition of the feed

    The value of q is given by

    Bv,feed ? Latent heat of the feed

    9p,feed ? 0pecific heat of the feed

  • 7/25/2019 Chemical Design Ethylbenzene

    11/32

    T 7/." 9

  • 7/25/2019 Chemical Design Ethylbenzene

    12/32

    Tbubble 7/." 9

    0pecific heat (//.% J

  • 7/25/2019 Chemical Design Ethylbenzene

    13/32

    ix i ,f

    i

    &y using Hoal 0eek operation in ;icrosoft >ffice xcel the satisfactory value of is

    (.'7**/7

    9omponent Ei, f G i G iEi ixi , f

    i

    &enzene

    '."#$$

    ".#" /.*( '.7%

    thylbenzene

    './/7/

    ( './/7/ $.#(*"

    (,$ -iethylbenzene'.'/1(

    '.("1 '.''" '.''7

    Total (.''

    Table ! , data for calculation at feed stream

    The value of is then substitute into the equation as below

    ixi ,d

    i=Rm+1

    9omponent Ei, d G i G iEi ix i ,d

    i

    &enzene

    '.**$/

    '.%* '.%* (.#'$

    thylbenzene

    '.''%$

    ( '.''%$ '.'"1

    (,$ -iethylbenzene

    '

    ' ' '

    Total (.''

    Table ! data for calculation Dm at stream (*

    Dm ( ? (.#7#

    Dm ? '.#7#

  • 7/25/2019 Chemical Design Ethylbenzene

    14/32

    D ? (.%Dm

    ?(.%5'.#7#6

    ?'.$'1

    #." ;I3I;4; 23- TB>DTI92L 34;&D > 0T2H0

    ;inimum stages

    ,a

    2LF LD LW

    2(6.26)(0.56)(0.005)

    2.83

    XLK

    XHK

    XHK

    XLKblog

    Nm=

    0.9943

    0.0054

    0.8964

    0.00168blog

  • 7/25/2019 Chemical Design Ethylbenzene

    15/32

    /m 11.#6 sta(es

    !eoetial sta(es

    R

    R+1=

    0.408

    0.408+1=0.29

    Rmin

    Rmin+1=

    0.272

    0.272+1=0.213

    Nm

    N =0.49

    11.76

    N =0.49

    N=24 theoretical stages(23 trays+1reboiler)

    LOCATION OF FEED TRAY

    logNe

    Ns=0.206log [(!D )(

    xf , HK

    xf , LK)(Xb, LK

    Xd , HK)2

    ]

    =here EL@,- ? mol fraction of light key in distillate

    EB@,- ? mol fraction of heavy key in distillate

    EB@,& ? mol fraction of heavy key in bottom

    EL@,& ? mol fraction of light key in bottom

    Ga ? average relative volatility of light key

  • 7/25/2019 Chemical Design Ethylbenzene

    16/32

    logNr

    Ns=0.206log[( 101.1170.2 )(

    0.6244

    0.3373 )( 0.8964

    0.00168 )2

    ]

    N r

    Ns=0.47

    3r 3s?# $

    '.$73s 3s? #$

    3s? ("./#

    This mean feed tray is (" trays from top

    #.1 9>L4;3 I9I39F

    The prediction of overall column efficiency can be obtained from the correlation given

    by >A9onnell below!

    =here

    Ma ? the molar average liquid viscosity, m3s

  • 7/25/2019 Chemical Design Ethylbenzene

    17/32

    Where 89SA,

    89SB %nn n he "&6 e"%! e&%n

    Te4;er&re 6e< ;%n =%;> -1.(

    Te4;er&re ##"e ;%n =#%%4> 1(5.(

    Aerge e4;er&re 113.( C/3-'.( ?

    Component 5 5 B XF 7ean isosit"

    &m/sm2)

    isosit"

    &m/sm2)

    Benzene 328.49 182.48 0.6244 0.22 0.13#

    t!"lben 410.$8 219.6# 0.33#3 0.1$ 0.0$1

    1,4 - - 0.0381 3.6 0.13#

    Thus the average a can be calculated as below

    a ='.(/7 '.'%( '.(/7

    ? './#%

    >verall efficiency is

    ' ?%( /#.% log5'./#%x /.$"#6

    ? $*./$ +

    2.) N@MBER OF ACT@AL STAES

    #! &ng e % %er"" r! een!,

    E% =n&4#er % 6e" r! / n&4#er % &" r!

    N&4#er % &" r! 23 / .()33 =('.'2 (' r!

    -30ITF 23- DL2TI8 ;>L2D ;200

  • 7/25/2019 Chemical Design Ethylbenzene

    18/32

    Component feed Distillate bottom 7ola ei(!t

    &(mol)

    " ,liq# id

    &:(m3)

    Benzene 0.6244 0.9943 0.0016

    8

    #8.11 8#6

    t!"lben 0.33#3 0.00$4 0.8964 106.1# 866

    1,4 0.0381 0 0.1024 134.22 862

    Relative Molar Mass, RMM

    RMM = ( Component mole fraction x Molecular weight)

    RMM at feed =(0.6!!x"#.$$) % (0.&&"&x$06.$") % (0.0$&!.) =#'.0

    g*mol

    RMM at +istillate(op -roduct)

    =(0.!& x"#.$$) % (0.00'! x$06.$6') % (0 x$&!.$#$) ="#.& g*mol

    RMM at ottom -roduct

    =(0.00$6# x"#.$$) % (0.0#6! x$06.$") % (0.$0! x$&!.) =&.& g*mol

    +ensit/ top

    i1uid densit/, 2 = (0.!&x#"6) % (0.00'!x#66) % (0x#6)

  • 7/25/2019 Chemical Design Ethylbenzene

    19/32

    = #"!.06 g*m&

    3apor densit/, 23 = ("#.& g*mol * .! m&*mol)("& 4 * &'!.! 4)

    ($.0' 5ar * $5ar)

    = .# g*m&

  • 7/25/2019 Chemical Design Ethylbenzene

    20/32

  • 7/25/2019 Chemical Design Ethylbenzene

    21/32

  • 7/25/2019 Chemical Design Ethylbenzene

    22/32

    .$$ C7M8 +9:M;;R

    he important factor that affects the column diameter is vapor flowrate.

    he vapor velocit/ should 5e 5elow than which would cause excessive

    li1uid entrainment or high pressure drop. o estimate the maximum

    allowa5le superficial vapor velocit/, we use owenstein ($6$) e1uation

  • 7/25/2019 Chemical Design Ethylbenzene

    23/32

    or diameter column a5ove than $ m, plate spacing of 0.& to 0.6 m will

    normall/ 5e used, and 0.! m ($' in.) can 5e taen as an initial estimate.

    (Coulson > Richardon, 00&) 9n this design, taing plate spacing as 0.& m,

    the allowa5le superficial vapor velocit/, calculated is=.3> D =.3 2> D =('*1>=.5> 1(.'25

    4

    1'.) 4 =n"&6ng 1G e! %r>

    .$ C7M8 B;9B

    ?ithout considering the sirt or an/ support, the column height can 5e

    calculated using the e1uation 5elow


Recommended