selecting thermodynamic property in hysys

8/9/2019 Selecting Thermodynamic Property in HYSYS

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SELECTINGTHERMODYNAMICPROPERTY METHODS


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A key requirement of process design is the

need to accurately reproduce the variousphysical properties that describes chemicalspecies.

The property packages available in HYSYS

allow you to predict properties of mixturesranging from well de ned light hydrocarbonsystems to complex oil mixtures and highlynon!ideal "non!electrolyte# chemical

systems.


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PHYSICAL PROPERTIES

The physical properties required for modelingand simulation often includes$

%olecular reaction and kinetic data. Thermodynamic properties Transport properties


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MOLECULAR REACTION & KINETICDATA

&n this case 'ritical properties are$(ate equationActivation energies(eaction mechanism


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THERMODYNAMIC PROPERTIES

)nthalpy)ntropy*ugacity coe+cient

,ibbs free energy


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TRANSPORT PROPERTIES

-i usion coe+cient Thermal conductivities/iscosities


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HYSYS provides enhanced equations ofstate " PR and PRSV) for rigoroustre t!e"t of #$%ro r'o" s$ste!s(se!i e! iri * and vapour pressuremodels for the heavier hydrocarbonsystems0 steam correlations for accuratesteam property predictions0 and activitycoe+cient models for chemical systems. Allof these equations have their own inherentlimitations.


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So HYSYS includes following methods for theestimation of 1hysical properties$)quations of state

Activity models'hao!Seader based empirical methods/apour pressure models an%iscellaneous methods.


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E+UATIONS O, STATES


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The table listssome typical

systems andrecommendedcorrelations.


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PENG-RO.INSON EOS*or oil$ gas and petrochemical applications$the 1eng!(obinson )2S " PR) is ge"er **$t#e re o!!e"%e% ro ert$ / ge0


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&t rigorously solves any single$ two!phase orthree!phase system with a high degree ofe+ciency and reliability$ and is applicable

over a wide range of conditions$ as shown inthe following table.


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the 1eng!(obinson equation of statesupports the widest range of operatingconditions and the greatest variety ofsystems. The 1eng!(obinson and Soave!(edlich!3wong equations of state ")2S#generate all required equilibrium andthermodynamic properties directly.


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PR AND SRK The PR e1u tio" of st te *ies fu" tio" *it$ to so!e s e i2component!component interactionparameters. 3ey components receivingspecial treatment include He$ H 4$ 5 4$ '2 4$H4S$ H42$ 'H 62H


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The PR or SRK EOS should not be used fornon ideal chemicals such as alcohols$ acidsor other components. They are moreaccurately handled by the Activity %odels"highly non ideal# or the PRSV EOS"moderately non!ideal#.


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LEE KESLER PL3CKER E+UATION The 7ee 3esler 1l8cker equation is anaccurate general method for non polarsubstances and mixtures.


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ACTIVITY MODELS


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ACTIVITY MODELSAlthough equation of state models have

proven to be very reliable in predictingproperties of most hydrocarbon based9uids over a large range of operatingconditions$ their application has beenlimited to primarily non!polar or slightlypolar components. 1olar or non!idealchemical systems have traditionally beenhandled using dual model approaches.


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E4TENDED AND GENERAL NRTL:ith a wide boiling point range between

components. 5#ere $ou re1uiresi!u*t "eous so*utio" of VLE "% LLE6"% there exists a wide boiling point range

or concentration range betweencomponents.


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CHAO SEADER MODELS


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VAPOUR PRESSUREMODELS


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MISCELLANEOUS MODELS


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VAPOUR PRESSUREMODEL

The /apour 1ressure options include theMo%i2e% A"toi"e6 .r u"K786 and EssoK

/ ges


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MISCELLANEOUS - SPECIALAPPLICATION METHODS

A!i"es Pro ert$ P / ge


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STEAM PACKAGEHYSYS includes two steam packages;9 ASME Ste !9 N.S Ste !


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ASME Ste ! esses t#e ASME 7:;??@*.Selecting N.S=Ste ! uti*i>es t#e N.S7:?@ Ste ! T '*es6 5#i # reportedlyhas better calculations near the 'ritical1oint.


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ASSIGNMENT


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PUMP1umps are used to move liquids. The pumpincreases the pressure of the liquid. :ater

=4? ' and 6 baris fed into a pump that has only =?e+ciency. The 9ow rate of the water is =??kgmoleBh and its outlet pressure from thepump is CD bar. Esing 1eng!(obinsonequation of state as a 9uid package$

determine the outlet temperature of thewater.


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RESULTS This example shows that pumping liquid canincrease their temperature. &n this case$ the

pump was only =? e+cient and itcaused =C@' in the temperature of the water.

The less e+cient a pump is$ the greater theincrease in the temperature of the 9uid beingpumped. This arises because in a lowe+cient pump$ more energy is needed to

pump the liquid to get the same outletpressure of a more e+cient pump. So theextra energy gets transferred to the 9uid.


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COMPRESSOR

'ompressors are used to move gases. Thecompressor increases the pressure of thegases. A mixture of natural gas "'=$ '4$ '6$ i!'D$ n!'D$ i!'>$ n!'>$ n!'F$ 'G # at =?? ' and =

bar is fed into a compressor that has only 6?e+ciency. The 9ow rate of the natural gas is=?? kgmoleBh and its outlet pressure from thecompressor is > bar. Esing 1eng!(obinsonequation of state as a 9uid package$ determinethe outlet temperature of the natural gas.&f the outlet temperature is D?? '$ what is thee+ciency of the compressorI

selecting thermodynamic property in hysys

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