2012 Corporate Capabilities - Spectroscopy

www.spectroscopyonline.com
December 2011 Spectroscopy 26(12) 23
FT-IR system (Gasmet Technologies
Oy, Finland). Other FT-IR systems
could also be utilized, but portability
and 24/7 continuous data acquisition
are key requirements.
Case Study — Fouling
The first case study is an application
in a plant trying to solve
plugging and fouling events that
have been occurring regularly
over multiple years. The stream
was primarily ethylene with other
C 2
–C 8
hydrocarbons and unknown
low levels of acrylic acid monomer,
water, and other small organics
thought to be present in concentrations
less than 1 mol%. It was
known that the substance plugging
the equipment at the facility was
polyacrylic acid polymer and that
minimizing the presence of acrylic
acid and water in the stream would
minimize the fouling. Several process
control changes had been tried
throughout the years, based purely
on Aspen process models (Aspen
Abs Arb
(a)
2
0
(b)
2
(c)
0
2
0
(d)
2
0
4000
3000
Technology, Inc., Burlington, Massachusetts),
but the plugging issues
persisted. The unknown was how
various process operating conditions
in surrounding portions of the
Wavenumber (cm -1 )
2000
Figure 3: Spectra of (a) 100% ethylene, (b) 500 ppm water, and (c) 932 ppm acrylic acid, and
(d) a process spectrum at 150 °C and 1 atm with a 5.11-m pathlength at 0.5-cm -1 resolution and
a 1-min collection time.
plant impacted the residual levels of
acrylic acid and water in the region
where fouling occurred. Attempts
to validate the assumptions used for
the process models using aluminum