Chemical Engineering January 2017 - 19

accuracy, high zero stability and high repeatability. They
are engineered with advanced, configurable multi-gas/
multi-range capabilities. " Onboard control electronics
control flow without any external input, except for user
programmed commands, " says Kramer. " This means
users tell the mass flow controller what to do and it will
not only provide the flow rates, but also compensate for
any inadequacies in the process, such as by opening or
closing a valve to compensate for a change in upstream
pressure. This is a big deal because it means that the
process can continue, but also because the instrument
will alert the user to the fact that it had to compensate
for an upstream issue. As soon as the user knows there's
an anomaly in the process, he or she knows there is an
issue that needs attending in order to keep the process
going, which is a huge benefit in the chemical industry. "
Also helping to better and more accurately control
gas two-phase flows is the Entrained Gas Management
(EGM) technology available on Krohne (Duisburg, Germany;
www.krohne.com) Optimass Coriolis mass flowmeters
(Figure 3), says Ralf Haut, industry manager for
chemicals with Krohne. With the additions of Optimass
3400 and 7400, the entire series of instruments offers
continuous and repeatable mass-flow or density measurement
with two-phase flows such as liquids mixed
with gas, slurries with gases or highly viscous fluids with
gas entrainments. In the past, this presented a huge
challenge for mass flowmeters: without gas entrainments,
the measuring tubes in the Coriolis mass flowmeters
have the desired regular oscillation. Gas entrained
in the liquid dampens this and, as the gas content increases,
it can come to a complete stop. To overcome
this, Krohne developed control algorithms that allow the
meter to maintain oscillation and continue to measure
even with complex flow conditions. This is possible even
during a complete transition from a pure liquid phase to
a gas phase and back, allowing mass flow and density
measurements to remain stable, continuous and repeatable.
" This technology allows robustness and an advanced
level of process control, " says Haut. " The instrument
won't stop working, production is more efficient
and the output may increase, which all means the profit
at the end of the process will also be greater, thanks to
better control of the flow. "
Enhancing safety
" In the chemical industry, many products are hazardous
and processes use high temperatures and high
pressures, so they must be properly monitored and
controlled, " says Art Womack, regional manager with
Fluid Components International (FCI; San Marcos, Calif.;
www.fluidcomponents.com). He says this mandates that
processors use equipment that controls the process but
also maintains certain safety limits demanded by internal
processes, as well as by government standards.
" Many applications and equipment are currently in place
because they are a safe and reliable technology, so the
focus becomes being able to demonstrate that the system
meets a certain risk reduction factor and that equipment
complies with current safety regulations, " says
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Circle 10 on p. 62 or go to adlinks.chemengonline.com/66424-10
JANUARY 2017
19
http://www.krohne.com http://www.fluidcomponents.com http://adlinks.chemengonline.com/66424-10 http://WWW.CHEMENGONLINE.COM
Chemical Engineering January 2017

Table of Contents for the Digital Edition of Chemical Engineering January 2017
