Thermo 004 HeatOfVaporization

7/29/2019 Thermo 004 HeatOfVaporization

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© 2012 Aspen Technology, Inc. All rights reserved

Revised: November 26, 2012

Heat of Vaporizationwith Aspen HYSYS®

Using Aspen HYSYS® V8.0



© 2012 Aspen Technology, Inc. All rights reserved | 2

Objectives

Learn how to calculate the heat of vaporization using theheater block in Aspen HYSYS

Understand the impact of heat of vaporization on

distillation




Background

Physical properties such as vapor pressure, normal boilingpoint and relative volatility (i.e., the shapes of Txy diagrams)have direct and significant impacts on separation processes.Given these things equal, the heat of vaporization of components impacts the energy consumption of distillation

columns.

A large heat of vaporization of the component enriched in thebottom of a column typically means large heat duty for thereboiler.




Key Teaching Points

When we compare the heat of vaporization of relevant

components for the purpose of evaluating the energyefficiency of a distillation column, we should compare them ata given pressure and on the mole basis for the followingreasons:– The stage pressure at the bottom stage mostly depends on column

hydraulics and typically has a fixed targeted design value.

– Phase equilibrium relations (e.g., Txy diagram) are based on the molebasis.

A pure analysis on the heat of vaporization for componentsgenerates a plot of the heat of vaporization versus

temperature, which gives us a rough idea of the comparison,but not the exact comparison we are looking for.

A vapor fraction of 0.0 means that the mixture is at the bubble

point and a vapor fraction of 1.0 means it is at the dew point.




Copyright

Copyright © 2012 by Aspen Technology, Inc. (“AspenTech”). Allrights reserved. This work may not be reproduced or distributedin any form or by any means without the prior written consent of AspenTech. ASPENTECH MAKES NO WARRANTY ORREPRESENTATION, EITHER EXPRESSED OR IMPLIED, WITHRESPECT TO THIS WORK and assumes no liability for any errors or

omissions. In no event will AspenTech be liable to you fordamages, including any loss of profits, lost savings, or otherincidental or consequential damages arising out of the use of theinformation contained in, or the digital files supplied with or foruse with, this work. This work and its contents are provided foreducational purposes only.

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Thermo 004 HeatOfVaporization