Page 77 - Application Handbook - TOC

Sum parameter – Total Organic Carbon
Continuous condensate monitoring using
the TOC-4200
SCA-130-604
The chemical and petrochemical industry
uses superheated steam as energy carrier for
the supply of energy needed in various
thermal processing steps. Superheated
steam is usually generated from ultrapure
water, which prevents damage to the boilers.
In order to use as little water as possible, the
reflux condensate is redirected to the boiler. It
is, therefore, important to ensure that the
condensate is free from organic pollutants.
■ TOC determination in condensate
The TOC parameter provides information on
organic pollution. The TOC can be easily
determined and is easy to implement in
process analysis. Two oxidation techniques
are now commonly used in TOC analysis:
 Catalytic combustion, where carbon
compounds are converted into CO 2
using a catalyst under high
temperatures with subsequent
detection of the resulting CO 2 using
an NDIR detector
 Wet chemical oxidation, which uses a
combination of UV irradiation and
persulfate for oxidation. The resulting
CO 2 is either detected via an NDIR
detector or a via conductivity detector.
When applying TOC determination to
condensates, few particles are usually
expected, but here as well, it is better to be
on the safe side with the higher oxidation
potential offered by catalytic combustion. It is
important to be able to quickly and reliably
detect every possible organic contamination.
Due to the low pollution level of the sample,
the catalyst remains stable over a long time
span, whereby the need for maintenance is
relatively low.
■ TOC-4200
The high-performance TOC-4200 analyzer
applies catalytic combustion at 680 °C. Three
TOC analysis methods can be selected
depending on the sample characteristics:
differential method, addition method, direct
method. Due to the automatic dilution
function TOC analyses up to 20,000 mg/L are
possible. In order to measure the total bound
nitrogen (TN), the TOC-4200 can be
extended with a specific module.
The self-calibration option and an automatic
dilution function enable a virtually
independent operation of the measuring
system which can be started and calibrated
from one measuring station. The different
measuring streams can be selected.