ANALYTICAL INSTRUMENTATION
O
ptical spectroscopy is a well-established method for quanti-
fying compositions. It allows to maximise the performance
of a system, for example, the so-called ‘space-time yield’:
In addition to the use of ‘classical’ process measuring technology
(flow, level, temperature, etc.) PAT tools are increasingly being
used to achieve this aim. The requirements for PAT are very differ-
ent; batch processes require a temporal extension of the
measurements across all concentration ranges. The
composition of the substance on the probe changes
constantly. In continuous processes, however, the
same composition or the same concentration
often appears in only one point in the production
chain and the measurements take place accord-
ing to the various process steps. The ideal state
of always knowing all relevant information or
data would mean a great expense even in a small
plant. With well-placed PAT measuring points, on
the other hand, a higher level of control technology
can be achieved and previously unused potential realised.
KROHNE has developed the OPTIQUAD optical spectros-
copy systems for applications with milk, wastewater and edible oil
and fat. Typical applications include the continuous measurement
of protein, fat, lactose and total solids in milk products, chemical
oxygen demand (COD) in the wastewater flow of dairies or cheese
factories, as well as free fatty acids (FFA), total polar material (TPM),
peroxide value (POV), moisture, dirt and other values in edible oil
and fat processing.
The OPTIQUAD uses optical spectroscopy tomeasure the contents
of milk products continuously and without contact. In the process,
light of varying wavelengths is coupled into the product through an
optical window. The system simultaneously determines the values
of up to four optical effects (transmission, scattering, fluorescence
and refraction) which manifest in different ways depending on the
substances in the product, and then uses them to calculate for ex-
ample in dairy applications the amounts of protein, fat, lactose and
total solids. The measurement is tailored to the application with up to
12 wavelengths from UV to IR. The measuring cycle lasts only a few
seconds. Typical applications for dairies include strategically increas-
ing the protein content in cheese making milk/vat milk, standardising
the fat content in drinking milk or setting a constant ratio of fat to
protein in cheese production.
Unlike bypass devices which are sometimes costly to clean, the
OPTIQUAD M measures without contact directly in the pipeline:
the system is connected to the process via a standard
VARINLINE process connection (nominal sizes DN 40
to DN 150). The measuring section is FDA-compliant
and is cleaned using CIP. There is no need for daily
recalibration thanks to the long-term stability of
the optical measurement, which requires nomov-
ing parts. In addition, operating andmaintenance
costs are lowered as there is no need for chemi-
cals, reagents or cleaning products. Operating the
device requires no special knowledge.
Power of light in industrial process
management:
Spectroscopy
Günter Pinkowski, KROHNE Optosens
Process Analysis Technology (PAT) is an essential prerequisite for the management and control of processes which is optimal, both technically
and economically.
take note
Günter Pinkowski is managing director of KROHNE Optos-
ens, a KROHNE subsidiary dedicated to optical systems,
and has been working in the field of optical spectroscopy
for more than ten years.
Enquiries: Email
g.pinkowski@krohne.comor
J.Alexander@KROHNE.comAbbreviations/Acronyms
CIP – Clean-In-Place
COD – Chemical Oxygen Demand
FDA
– Food and Drug Administration
FFA
– Free Fatty Acids
IR
– Infrared
PAT
– Process Analysis Technology
POV
– Peroxide Value
TPM
– Total Polar Material
UV
– UltraViolet
• Optical spectroscopy is an established method for quantify-
ing compositions.
• Optical spectroscopy systems have been developed for
applications with milk, wastewater, edible oil and fat.
• The OPTIQUAD uses optical spectroscopy to measure the
contents of milk products continuously and without contact.
Electricity+Control
May ‘16
16