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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.com

or

J.Alexander@KROHNE.com

Abbreviations/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