Puianu Monica IIPCB , 2017
Styrene production
Contents 1. Short description of the process................... process ....................................... ....................................... ....................................... ........................................ ........................... ....... 2 2. Simulations.................. Simulations ...................................... ........................................ ........................................ ........................................ ....................................... ................... .....................3 .....................3 2.1. spen Plus !".# ......................................................................................................................................... $ 2.1.1. Model of the process ........................................................................................................................
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2.1.2. Simulation results..............................................................................................................................
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2.1.3. Model %alidation............................................................................................................................. ..# 2.1.$. Sensiti%ity analysis .............................................................................................................................# 2.1.&. Conclusions ......................................................................................................................... ................"
3.'eferences. 3.'eferences.................... ....................................... ........................................ ........................................ ....................................... .................................. ............... ..........................(
1
1. Short description of the process Styrene, also )no*n as phenylethylene, %inyl+enene, styrol or cinnamene, is an important industrial unsaturated aromatic monomer. It occurs naturally in small -uantities in some plants and foods. It is a colorless li-uid *ith an aromatic odor, is innitely solu+le in acetone, car+on tetrachloride, ether, n/heptane and ethanol 1 2. ther important properties of styrene are listed in a+le 1. Table 1. Physical properties of styrene monomer [1]
Property
Value
Boiling point ree!ing point "utoignition temperature #$plosi%e limits in air &eat of polymeri!ation
1$& /30.#
Unit 4C at 1atm 4C
$(0
4C
1.1/1.#
5
7$.$"
)6mol
here are t*o process routes commercially used for the manufacture of styrene8 dehydro9enation and coproduction *ith propylene o:ide. Both routes use ethyl+enene as an intermediate. Styrene is a commodity chemical, traded in lar9e %olumes domestically and internationally. he product specications are lar9ely dictated +y the mar)et. he minimum purity is usually ((."5 *hich can +e easily met in a *ell/operated plant of modern desi9n. Styrene is the monomer used to ma)e polystyrene *hich has multiple uses, the most common +ein9 in pac)a9in9 and insulated Styrofoam +e%era9e cups. In this *or) the production of styrene from dehydro9enation of ethyl+enene *as studied. he process ;o* dia9ram is sho*n in
2
igure 1. 'eference styrene production process (o)*sheet
=thyl+enene feed is mi:ed *ith recycled ethyl+enene, heated and then mi:ed *ith hi9h/temperature superheated steam. Steam is used in the process in order to dri%e the e-uili+rium reaction sho*n in
3
'eaction 1 to the ri9ht +y reducin9 the concentration of all components. Because styrene production is hi9hly endothermic, the superheated steam also pro%ides ener9y to dri%e the reaction. >ecomposition of ethyl+enene to +enene and ethylene?'eaction 2@ and the hydrodeal)ylation reaction resultin9 in methane and toluene ?'eaction 3@, are un*anted side reactions.
'eaction 1 'eaction +
'eaction ,
he reactants enter a t*o adia+atic pac)ed +ed *ith inter/heatin9. he products are cooled, producin9 steam from the hi9h/temperature reactor eAuent. he cooled product stream in then sent to a three phase separator *here the li9ht 9ases, or9anic li-uid and *ater are separated in dierent streams. he 9as stream is further puried and used as a source of hydro9en else*here in the plant. he +enene/toluene stream is returned as a feed stream to a petrochemical facility. he or9anic stream containin9 the desired product is distilled once to remo%e the +enene and toluene and a9ain to separate the unreacted ethyl+enene from the styrene product and recycled. he styrene product can spontaneously polymerie at hi9her temperatures and for this reason is necessary to maintain the temperature less than 12&4C. Because this is less than styrenes normal +oilin9 point and +ecause lo* pressure pushes the e-uili+rium to the ri9ht, much of this process is run at %acuum 3.
+. Simulations Styrene production process *as modeled usin9 the simulation soft*areand spenPlus !".#. he S'D ?Soa%e/'edlich/D*on9@ thermodynamic pac)a9e *as chosen for the simulations. he inlet stream of the ra* materials as ta)en from literature as presented in a+le 2. Table +. -nlet streams characteri!ation
Stream umber
1 0#thylben! ene
Temperature 13# [2C] 2 Pressure [bar] Vapor mole 0 fraction Total (o) 123.$2 [3mol4h] Component (o)rates [3mol4h] 0 5ater 121 #thylben!ene 0 Styrene
/ 0&igh Pressure Steam
$
Eist of e-uipments used in the simulation8
2&3.7 $2.37
−
1
−
compressors8 1 heat e:chan9ers8 &
$01#.3
−
red heater8 1
$01#.3 0 0
− − − −
pumps8 $ reactors8 2 to*ers8 2 %essels8 2
&ydrogen Ben!ene Toluene #thylene 6ethane
0 1.21 1.21 0 0
0 0 0 0 0
+.1. "spen Plus V7.8 +.1.1. 6odel of the process he ;o*sheet +uild in spen Plus that descri+es the styrene production process can +e found in P=F>IG 2. In this case too, an additional separator *as added to further separate the or9anic phase from the li9ht 9ases and *ater. he reactors *ere modeled as adia+atic stoechiometric reactors, in the same *ay as in CH=MC>. 'M1 *as selected from the Separators Palette and for parameteriation the temperature, pressure and %alid phases8 !apor/Ei-uid/>irtyJater, *as specied. In case of the to*ers, t*o distillation columns *ere chosen and parameteried as it can +e seen in
igure 19. :istillation columns parameteri!ation in "spen Pl us
+.1.+. Simulation results he most important results o+tained *ith spen Plus simulation soft*are, are presented +elo*. he results from the three/phase separator are presented in
&
separator does not perform an ideal separation and for this reason another component separator is added in order to separate all the li9ht 9ases and *ater from the or9anic mi:ture as *ater forms aeoptropes *ith all of the or9anic components8 +enene, toluene, styrene and ethyl+enene8
igure 11. "!eotropes search results from "spen Plus
#
igure 1+. Three*phase separator results from "spen Plus
+.1.,. 6odel %alidation >ata used for %alidation *as ta)en from reference 38 Table /. Validation of "spen Plus model
+1 Stream umber
Temperature [2C] Pressure [bar] Vapor mole fraction Total (o) [3mol4h]
0Styrene1 6od 'ef el
+8 0Ben!ene;Tolu ene1 'ef
123." 2
12$.3 2
70 2
0
0
120.0"
(".($3
6odel
+, 0&ydrogen1 6ode 'ef l
++ 05aste)ater 6ode 'ef l
7&." 2
202.2 1.$
1&0.( 1.$
#& 2
33.1 2
0
0
1
1
0
0
3.3$
2.7$#
120.2 1(3.#73
0 0.1 0.#7( 0 0 0 0 1.37 0.711 1."# 1.3 0 0 0 0
0 #3.3&2 0 10.("( 0 (.#01 11(.3" 107.(2$ 0 0.#3" 0 0.$3" 0.1# 0.1$$ 0.#& 0.&"#
3000
2(3#.7&
Component (o)rates [3mol4h] 5ater #thylben!ene Styrene &ydrogen Ben!ene Toluene #thylene 6ethane
0 0 0.0& 0 120.03 (".($3 0 0 0 0 0
0
3000 2(3#.#& 0.0&$ 0 0.001 0 0.033 0 0.00# 0 0.003 0 0.001 0 0.001 0
s it can +e seen from a+le $, there are small dierences +et*een the simulated and the literature data, thus the can say that the model can +e used successfully to descri+e the styrene production process.
+.1./. Sensiti%ity analysis 7
sensiti%ity analysis *as performed in spen Plus to see the eect of the pressure chan9e inside the three/phase separator. he pressure *as chan9ed +et*een 0.#& +ar and 1 +ar and the ;o* %ariation of the outputs *as in%esti9ated. he results are presented in
S#S-T1 * 'esults Summary 2(&0 H2
DMEH'
2($&
2($0
2(3& H 7 E 2 M D '
2(30
2(2&
2(20
2(1& 0.#& 0.# # 0 .# 7 0 .# " 0 .# ( 0 .7 0 0 .7 1 0 .7 2 0 .7 3 0 .7 $ 0 .7 & 0 .7 # 0. 77 0 .7 " 0.7 ( 0 ." 0 0 ." 1 0 ." 2 0 ." 3 0 ." $0."& 0."# 0 ." 7 0 ." " 0 ." ( 0 .( 0 0 .( 1 0 .( 2 0 .( 3 0 .( $ 0 .( & 0 .( # 0 .( 7 0 .( " 0 .( ( 1 . 00 !'K 1 B2( P'M P'=S B'
igure 1,. 5ater (o) %ariation in the outlet of the three*phase at %arious pressures
S#S-T1 * 'esults Summary 113.&
H2
113.0
DMEH'
112.& 112.0 111.& '111.0 H 7 E 110.& 2 M D
110.0 10(.& 10(.0 10".& 10".0 107.&
0."2 0."3 0."$ 0."& 0.#& 0 .# # 0 .# 7 0 .# " 0 .# ( 0 .7 0 0 .7 1 0 .7 2 0 .7 3 0 .7 $ 0 .7 & 0 .7 # 0 .7 7 0 .7 " 0 .7 ( 0 ." 0 0 ." 1 !'K 1 B2( P ' M P '= S B '
"
0."# 0 ." 7 0 ." " 0 ." ( 0 .( 0 0 .( 1 0 .( 2 0 .( 3 0 .( $ 0 .( & 0 .( # 0 .( 7 0 .( " 0 .( ( 1 .0 0
igure 1/. &ydrogen (o) %ariation in the outlet of the three*phase at %arious pressures
S#S-T1 * 'esults Summary 1.#0 1.&&
B=F L
1.&0
E
DMEH' DMEH'
1.$& 1.$0 1.3& 1.30 1.2& 1.20 DMEH'1.1 0
1.1& 1.0& 1.00 0.(& 0.(0 0."& 0."0 0.7& 0.70 0.#& 0 .# # 0.# 7 0 .#" 0 .# ( 0 .7 0 0 .7 1 0 .7 2 0 .7 3 0 .7 $ 0 .7 & 0 .7 # 0 .7 7 0 .7 " 0.7 ( 0 ." 0 0 ." 1 0 ."2 0. "3 0 ." $0."& 0."# 0."7 0."" !'K 1 B2( P ' M P '= S B '
0."( 0.(0 0.(1 0.(2 0.(3 0.($ 0.(& 0.(# 0.(7 0.(" 0.(( 1.00
igure 1<. Ben!ene and toluene (o) %ariation in the outlet of the three*phase at %arious pressures
S#S-T1 * 'esults Summary 110.&
SK'
110.0
DMEH'
10(.& 10(.0 10".& 10".0 107.& 107.0
' H 7 10#.& E 2 M10#.0 D
10&.& 10&.0 10$.& 10$.0 103.& 103.0 102.& 102.0
0.#& 0 .# # 0 .# 7 0 .# " 0 .# ( 0 .7 0 0 .7 1 0 .72 0 .7 3 0 .7 $ 0 .7 & 0 .7 # 0 .7 7 0 .7 " 0. 7( 0 ." 0 0 ." 1 0."2 0 ." 3 0 ." $ 0 ." & 0."# 0 ." 7 0 ." " 0 ." ( 0 .( 0 0 .( 1 0 .( 2 0 .( 3 0 .( $ 0 .( & 0 .( # 0 .( 7 0.(" 0.(( 1.00 !'K 1 B2( P 'M P '=S B '
igure 18. Styrene (o) %ariation in the outlet of the three*phase at %arious pressures
s it can +e seen from the sensiti%ity analysis results, *ith the increase of the pressure at a constant temperature of #&4C, a +etter separation of the phases present in the three/phase separator ta)es place.
+.1.<. Conclusions he results o+tained usin9 process simulator spen Plus to descri+e the styrene production process are in line *ith literature data and pro%ed to +e satisfyin9. he sensiti%ity analysis conducted sho*ed that *hen increasin9 the pressure at a constant temperature, in the three/phase separator, a +etter separation can +e o+tained.
(
,. 'eferences 1 D. thmer, Styrene, in Encyclopedia of Chemical Technology , Fe* Kor), 6ohn Jiley N Sons, 200#. 2 >. H. 6ames and J. M. Castor, Styrene, 2000. 3 '. urton, '. C. Bailie, J. B. Jhitin9, 6. . Shaei*it and >. Bhattacharyya, Styrene Production, in Analysis, synthesis, and design of chemical processes 4th Edition, Michi9an, Pearson, 2012, pp. 111#/112$.
APENDIX 1
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