Chemical Engineering December 2011 - 27

date models. It allows users to base
decisions on better, more timely information
and ultimately make safer
plants, much faster. "
And interaction with other tools
can also allow people who may not
be using simulation on a daily basis
to become simulation experts. For example,
AspenTech's Simulation Workbook
can link to an Excel spreasheet.
" The beauty in this is that where traditionally
users had to build custom
interfaces using programming, now
they can copy and paste links between
the simulator and Excel, " says Sanjeev
Mullick, director of industry marketing
with AspenTech. " This environment
allows users to quickly crate tables of
input and output data, charts, graphs
and pictures of the plant so people who
aren't experts can point and click and
change numbers and see the power of
simulation at work.
" Using Excel allows people who
aren't familiar with simulation tools to
perform 'what-if' studies, " says AspenTech's
Tremblay. " They can bring in
plant data and change some variables
in the model using Excel and see how
the rest of the process is affected. In
that fashion they can experience the
cause and effect and get insight that
allows them to make better decisions.
Specialty simulations
However, there are times when simulation
needs to go beyond training
and creating " what if " scenarios, and
that is where more complex tools
come into play. For example, when
building actual equipment, computation
fluid dynamics (CFD) tools can
be used to model and understand
the behavior of a piece of equipment,
such as a gas-solid chemical reactor,
in detail. They will typically need to
model the equipment in full 3D and
in a time-transient way, since the
phenomena to be modeled and understood
are time-transient themselves.
The objectives of the modeling
are ultimately to ensure that
the chemical reaction to be run and
controlled will be safe, efficient, repeatable,
stable, reliable and as energy
efficient as possible, says CPFD
Software's Thibauld. " Such details as
how the equipment will be started up
and shut down must be studied if a
Circle 6 on p. 62 or go to adlinks.che.com/35072-06
CHEMICAL ENGINEERING WWW.CHE.COM DECEMBER 2011 27
practical process is eventually to be
designed and deployed.
His company's Barracuda software
is a niche CFD software package
based on a unique numerical method
called Computational Particle Fluid
Dynamics, which is an implementation
of a method known more generically
as multiphase particle-in-cell.
It is designed for performing simulations
that involve particles, either gasparticle
or liquid-particle flows, which
is an application area that general
purpose CFD packages do not serve
well, he says. " The CFPD method
and Barracuda software work very
well because they can model the particle
size distribution and its effects
on fluid-particle flows in detail, plus
handle solids loadings from dilute to
dense packed at the same time and in
the same domain. "
Barracuda can model gas-gas, gassolid,
and solid-solid chemical reactions
in detail and at a discrete particle
level while still being able to
model very large devices at full scale
within a reasonable calculation time.
In the chemical and petrochemical
industries, it is often used for modeling
fluidized systems such as fluidized
bed reactors (Figure 2).
Likewise, Bryan Engineering & Research
offers ProMax, which has extensive
enhancements to allow simulation
of more complex processes. In
particular, it offers a very specialized
electrolytic thermodynamic package
for modeling ionic systems, such as
amine treating and sour water strippers,
and a special reactor and thermo
package for modeling sulfur recovery
systems. The thermo models for traditional
hydrocarbon systems have been
expanded to allow modeling of a wider
range of conditions and also include
special data for associated systems
such as glycol dehydration and methanol
injections.
■
Joy LePree
http://adlinks.che.com/35072-06 http://WWW.CHE.COM
Chemical Engineering December 2011

Table of Contents for the Digital Edition of Chemical Engineering December 2011
