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8/10/2019 Final Boris Sova Hy Sys
1/17
FAO: Dr Antonia Borissova
Mariam Hussain
200603585
PEME2030
HYSYS 2 - Mass & Enr!" Ba#an$s %on-
ra$tiv S"stms'
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Pro(#m statmnt
100 kmol/h of a mixture consisting of the following three components and their
respective mole fractions:
n-Hexane 0.3
n-Heptane 0.4
n-ctane 0.3
is fed at a temperature of !0 "# into the first of two separators operating at apressure of $00 k%a a&solute and 'emperature 1$3 "#. 'he li(uid from the firstseparator is then fed to the second separator operating at the same pressure) &ut atemperature of 1$* "#. + fraction 0., of the li(uid from the second separator isreccled to the first separator.
S#$tion o) *uation o) stat
'here are a few reasons the e(uation of state setting was used. 'he
setting uses the oave-edlich-wong method to determine the properties of the
components of the streams) it is suita&le &ecause all chemicals present are non-
polar and this e(uation is onl valid for non-polar chemicals. 'his e(uation of state
has advantages over other e(uations of state. or example the &asic edlich-wong
e(uation can &e used) however) when the chemicals involved are non-polar or
complex the results are ver inaccurate. 2n the separator processes designed) the
chemicals were all non-polar and (uite complex) making this e(uation rather
unsuita&le.
'he oave edlich-wong e(uation is shown in e(uation 1 &elow:
)(
)(
bVV
Ta
bV
RTp
+
= 1
p5pressure) k%a) a'5 a parameter which is the function of temperature)
it6s e(ual to
25.0
22
114274.0
+
c
c
c
T
Tm
p
TR
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where m5 2176.07.148.0 + and 5 acentric factor. 95volume in m3)
c
c
p
RTb 08664.0= where is the universal gas constant 2#H+) $001.
'5temperature) elvins
Ba$+!roun,
eparation of chemicals highl depends on the phsical and chemical properties of
the chemicals; separation processes exploit these properties to allow efficient
separation) such as differences in &oiling points) viscosit and densit.
'he differences is &oiling points of different chemicals is used to separate chemicals
in industrial processes such as fractional distillation of crude oil) in the
pharmaceutical industr various isomers of pharmaceuticals) and in the purification
of polmers where lower &oiling point monomers are removed. #hemicals with lower
&oiling points have a higher volatilit. 2n industrial applications) temperatures of
evaporators are carefull controlled to evaporate and separate various chemicals.
=#H=72#+?#) $011.
+spen H@@Ais used in industr to design process plants. 2t is often used in the
petroleum industr &ecause it is pre-set with various crude oil components and the
relevant properties of these components such as cloud point. 2t simplifies the designs
of multi-component) multi-unit operations. 2t contains multiple operations used in the
petroleum industr such as separators and reactors +%=B'=#H) $01$a.
+spen H@@ has the advantage of accuratel stimulating real life stream flows)
stimulating expected &ehaviour of these streams +%=B'=#H) $01$&.
om.utr simu#ation
irstl) +spen H@@ was opened) then a new case was opened up and the
fluid package was selected and three components was added) n-heptane) n-hexane
and n-octane. 'hen) the simulation environment was added.
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$ process flow diagrams were designed on +spen H@@ software. Coth process
flow diagrams involved mixers and separators. ue to this it was apparent &oth
sstems would have mass and energ &alances. 'o define an stream) $ properties
must &e known. +s the input temperature and compositions of the 3 chemicals were
know aswell as the input pressure and the molar &asis was set asinlet5100kmol/hour) when all the unit operations were all added and heat was input
as re(uired) H@@ automaticall using the e(uation calculated the properties
of all streams.
or the 1 separator process) the process flow diagram was set up as shown in figure
1 &elow:
Fi!ur /: .ro$ss )#o ,ia!ram )or / s.arator s"stm
'he inlet and inlet feed had the specified properties:
3.0
4.0
3.0
188
167
146
=
=
=
HC
HC
HC
x
x
x
'he inlet pressure was $00 k%a and the molar flow was set as 100k7ol/hr) these
were entered in the Dwork&ook6. =nerg was also added as an inlet & dou&le clicking
on the separator as the separator was set to operate at 1$3o# and the energ input
was automaticall calculated. 'his separation occurs due to the differing &oiling
points of the three components to &e separated. Hexane has a &oiling point of !Eo#)
heptane has a &oiling point of E8o# and octane has a &oiling point of 1$*o#
=?7H>') $003.
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ollowing this) a $ separator sstem was designed in the +spen H@@ software. 2t
was designed as shown in figure $ &elow:
Fi!ur 2: 2 s.arator s"stm PFD
'he inlet flows were same as for separator 1) the pressure of feed is $00k%a) heat is
input into separator 1 to allow it to reach a temperature of 1$3o#. 'here are $
product streams from the first separator) a vapour stream and a li(uid stream. 'he
li(uid stream is fed into another separator and the second separator operates at a
temperature of 1$*o# as heat is further added into the second separator to maintain
this temperature. 'here are $ product streams from the second separator; a li(uid
product and vapour product stream. 'he li(uid product stream is split into $ streams
where ,0F of the li(uid product is a reccle stream and is fed into the separator. 'o
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ensure the ratio of the li(uid product to reccle is ,:3) a Dtee6 is added and the li(uid
stream which is fed into the tee parameters are set to make the flow ratio of the
output 0., for the li(uid product and 0.3 for the reccle.
1su#ts
or 1 separator sstem:
Fi!ur 3: .ro.rtis o) a## in#t an, out#t strams
igure 3 a&ove shows the properties of the inlet and outlet streams. 'he text in &lue
was entered and the text in &lack was calculated & the software.
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Fi!ur : $om.ositions o) t / s.arator s"stm
igure 4 a&ove shows the compositions of the input and output streams of the 1
separator sstem.
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Fi!ur 5: at in.ut into t s.arator
igure * shows the heat input into the separator.
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eparator $ results
igure ! &elow shows the properties of all the streams of the $ separator sstem.
Fi!ur 6: .ro.rtis o) a## strams o) t 2 s.arator s"stm
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igure , &elow shows the commpositions of all the components of the $ separator
sstem.
Fi!ur 4: $om.onnts $om.ositions o) a## strams in t 2 s.arator s"stm
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Fi!ur 8: at in.uts into (ot s.arators
igure 8 shows the $ individual heat inputs of &oth separators of the $ separator
sstem; heat 1 is the heat input into the first separator and heat $ is the heat input
into the second separator.
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Dis$ussion
Coth the 1 separator and $ separator sstems are a&le to effectivel separate thesemixtures; however there are advantages and disadvantages of &oth sstems.
Temperature, oC
Vapourfraction ofhexane
liquidfractionofhexane
Vapourproductmolarow,kMol/hr
liquidproductmolarow,kMol/hr
VapourfractionofOctane
liquidfraction ofOctane
molar owof hexanein vapour,kMol/hr i
115 !5"#5 !" 1 !1#5$ !"
11% !5#%1 !#&%1 1!#'' &(!%" !1#(1 !"##
!''%"('
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11& !$("& !#'1' 1%!#& (#!%1 !1$(5 !""1%
(!"'''"1
1#1 !$$## !##&" ""!#1 ''!%& !1%# !"'"%
1$!'(5$'#
1#" !$#$ !#" $&!"1 5!'& !1&(( !"&(
5
1&!($#"$
$1#5 !"'51 !1%$' '5!(" "$!1% !##&$ !$"' #$!"$5""
1#% !""" !151( ("!1 1'!&& !#'"& !$%'1
#%!$1(#"
1#& !" !1"" 1 !" !5155
"
'he $ separator sstem has higher initial costs due to the fact it has and extra
separator and a Dtee flow splitter6 unit which ultimatel makes set-up of the
e(uipment more costl. urthermore) the total energ input to the $ separator sstem
is much greater than the total energ input into the one separator sstem) meaning
the running costs for a one separator sstem is much greater than the one separator
sstem. 7oreover) the $ separator sstem has the advantage that it contains a
reccle stream which allows the overall separation of hexane in the inlet feed to &e
maximised &ecause some of the li(uid outlet containing hexane is again fed into the
first reactor as the reccle stream.
+ sensitivit analsis was carried out on the 1 separator sstem. irstl the effect of
changing temperature of the inlet feed stream on the compositions of the n-hexane
component and n-octane component was recorded for the separator in the 1
separator sstem and is shown in ta&le 1 &elow:
a(# /: A ta(# soin! $om.ositions o) an in t va.our an, #i*ui,out#t strams o) t / s.arator s"stm as ## as t mo#ar )#o o) #i*ui, an,va.our strams an, o it7s a))$t, (" tm.ratur
'his shows that as the temperature increases the vapour fraction of hexane in the
vapour stream decreases and the li(uid fraction of octane in the li(uid stream also
decreases meaning separation increases) however the molar flow of the vapour
stream also decreases. 'o maximise the hexane molar vapour fraction the
temperature needs to &e decreased. However) if the temperature is decreased &elow
11*o
#) it no longer affects the molar fraction of the hexane molar vapour fraction.
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=ven though the vapour fraction of the vapour is at its maximum) there is no vapour
stream) so a compromise needs to &e made &etween the vapour fraction of hexane
and the molar flow of the vapour product.
However) if ou consider the hexane molar flow of the outlet streams of the
separator) it can help the decision of selecting the temperature. 'his graph is shown
in figure E:
Fi!ur : A !ra. soin! t ))$t o) t tm.ratur o) in#t stram on mo#ar)#o o) an in #i*ui, an, va.our strams
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'his graph shows that the molar flow of hexane in the vapour is maximum at
temperatures of 1$8o# and a&ove a plateau is reached at 1$Eo#. o) at higher
temperatures rate of hexane separated is increased.
ollowing this) a sensitivit analsis was carried out for the effects on changing the
pressure of the inlet and hence outlet streams for the one separator sstem:
)re**ur
e, k)a
Vapour
fraction ofhexane
liquid
fraction ofhexane
Vapour
productmolarow,kMol/hr
liquid
productmolarow,kMol/hr
Vapour
fraction ofOctane
liquid
fraction ofOctane
molar ow
of hexane invapour,kMol/hr
# !$#$ !#" $&!"1 5!'& !1&(( !"&(5
1&!($#"$$
#1 !$'1 !#"1 $%!%# 5#!#( !1&'1 !"&$(
1&!"%&
## !$&( !#5& $'!1$ 5"!(' !1&"5 !"&1#
1(!&(1%#
#" !$1"5 !#(( $$!5' 55!$$ !1&& !#(%%
1(!$#55'
a(# 2: A ta(# soin! $om.ositions o) an in t va.our an, #i*ui,out#t strams o) t / s.arator s"stm as ## as t mo#ar )#o o) #i*ui, an,va.our strams
'his shows that as pressure increases) the vapour fraction of hexane increases) and
the molar fraction of octane in the li(uid outlet increases meaning separation
increases) however the molar flow of the vapour product decreases. +t $$! k%a
pressure) the vapour fraction of hexane reaches its maximum) so separation is
maximised however) at this pressure) the molar flow is Gero so a compromise is
needed &etween maximum separation and molar flow rate of vapour.
However) if ou consider the hexane molar flow of the outlet streams of the
separator) it can help the decision of selecting the pressure. 'his graph is shown in
figure 10:
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Fi!ur /0:A !ra. soin! t ))$t o) .rssur o) in#t on mo#ar )#o o)an in va.our an, #i*ui, strams
o) as pressure increases) molar flow rate of hexane in the vapor outlet stream
decreases and the maximum molar flow rate is at a pressure of 1,4 k%a and if the
pressure is decreased &elow this point) it has no effect on the molar flow rate of
hexane in the vapour stream.
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1EFE1EES
+%=B'=#H) $01$a)ASPEN HYSYS Petroleum refining,onlineI) +vaila&le from:
http://www.aspentech.com/products/aspen-refss.aspx +ccessed 1$/11/$01$I
+%=B'=#H) $01$&, ASPEN HYSYS Dynamics) onlineI) +vaila&le from:
http://www.aspentech.com/products/aspen-hss-dnamics.aspx +ccessed
1$/11/$01$I
=?7H>') $003) BOILING POINTS AND ST!"T!ES O# HYDO"ABONS)
onlineI) +ccessed 1$/11/$01$I +vaila&le from:
http://www.elmhurst.edu/Jchm/vchem&ook/*01hc&oilingpts.html +ccessed
1$/11/$01$I
%=>=#H=72#+?#) $011) istillation #apa&ilities ) onlineI) +vaila&le from:
http://www.presschem.com/distillation.htm+ccessed 1$/11/$01$I
2#H+) $001) "$a%ters &' e(uations of state) pdfI) onlineI +vaila&le from:
http://www.swin&urne.edu.au/ict/research/cms/documents/disertations/sw#hap3.pdf
+ccessed 1$/11/$01$I
7ariam Hussain $00!03*8*
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http://www.presschem.com/distillation.htmhttp://www.presschem.com/distillation.htm