L17_Comparing measurement principles DLG1 AP

www.anton-paar.comwww.anton-paar.com
Comparing measurement principles for alcohol,
extract and CO2 and a new, low cost method for
inline alcohol measurement
Ottakringer Brewery, Vienna
September 9, 2014

▸Company Profile
▸Measurement Principles
• Density, sound velocity and refractive index
• Optical Infrared (IR) absorption
Transmission
Attenuated Total Reflection (ATR)
• Temperature/pressure
▸A new method for process alcohol measurement
▸How to compare different principles
Contents

Company Profile
Establishment 1922
Owner
Charitable
Santner Foundation
CEO Dr. Friedrich Santner
Chairman of the Board Ulrich Santner
Employees worldwide
(*as of the end of 2013)
892* in Graz
1.913* worldwide
Turnover 2013 202 million Euro
Exports > 94 %
Investment in R&D 19 % of annual turnover
Quality management ISO 9001:2008
www.anton-paar.com

▸~20 years ago, density/sound velocity and the alcohol combustion cell
replaced RI and density/distillation in the laboratory.
▸~10 years ago, optical infrared spectroscopy (IR) and density became
the preferred technology in the lab (Alcolyzer)
▸Process sensors continuously evolve and optical IR methods using
Attenuated Total Reflection (ATR) are now available
Measurement Principles: In the Beginning…

▸Traditional measurement methods excel with:
• Robust & proven design
• Very long life span
• High accuracy
• Drift free measurement
Measurement Principles: Today…

▸Optical methods also have definite benefits:
▸Highly selective
▸Easy to install
▸Compact size
▸Maintenance-free
▸Low cost of ownership
Measurement Principles: Today…

U-tube filled with air U-tube filled with sample
Measurement Principles: Density
Density one of the most important parameters in lab and process

▸The propagation of a sound
pulse through a sample
▸The sample flows between a
transmitter and a receiver
▸The propagation time directly
correlates to the concentration
Measurement Principles: Sound Velocity

▸A refractometer measures the
critical angle of total reflection
▸The position of the light/dark line
is detected by an optical Charged
Coupled Device (CCD)
▸The concentration is calculated
based on the location of the line
on the sensor
Measurement Principles: Refractive Index

▸IR is selective, has a very wide range of applications
▸Works best when the absorption peak is clearly visible
▸The physics of optical process measurement remain difficult
▸Minor temperature changes influence the measurement
▸Water, extract and CO2 absorb light, so a reference wavelegnth is
required
Measurement Principles: A Look at the IR Method

800 1000 1200 1400 1600 1800 2000 2200 2400
0.01
0.1
1
10
100
ethanol
water
wavelength (nm)
absorptioncoefficient(cm-1)
▸Only a few wavelengths exist
where the ethanol absorption is
higher than water
▸Not all wavelengths are equally
suited for accuracy
▸Clearly defined peaks work
best
Measurement Principles: IR Wavelengths

▸Highly temperature dependent
▸Especially at modern beer production temperatures
▸Influenced by the extract concentration
▸Influenced by process and batch extract variations
▸Hence, Anton Paar’s Alcolyzer replaced sound velocity in lab only
Measurement Principles: IR Alcohol Measurement

▸All sugars have different but similar wavelengths
▸The absorption peaks are small
▸All are temperature dependent
▸The mash, extract efficiency, enzyme activity, and feedstock
influence the sugar composition and change batch to batch
▸A mathematical model is required to measure the cumulative extract
▸This model is used to compensate the alcohol measurement
Measurement Principles: IR Extract Measurement

Measurement Principles: IR absorption ATR
wavelength in nm
referencedabsorption
Various CO2 concentrations at a specific wavelength
▸Large absorption peak
▸Clearly defined wavelength
▸Mostly free of other influences
▸This allows for a strong, accurate
signal with little interference.

Various sugar concentrations at a given CO2 concentration
▸Alcohol, extract and temperature
influence absorption
▸A reference wavelength is
needed to compensate
▸1°Plato ≈ 0.2 g/l CO2
Measurement Principles: IR absorption ATR

▸Low wavelengths require transmission method
▸~1200nm transmission length is 8mm
▸Used in Anton Paar’s Alcolyzer
Measurement Principles: IR Transmission

Measurement Principles: IR ATR
▸Higher wavelengths require Attenuated Total Reflection (ATR)
▸~2230nm transmission length is 1 mm

Measurement Principles: IR ATR
The NIR absorption takes place in the surface layer (evanescent wave)
IR
light source
Detector
ATR
crystal
Filter
Beer
Beer
Evanescent field
Boundary surface
Penetration depth
0.05 mm – 2 mm
Sapphire

▸Most instruments typically use Henry’s law
▸A chamber is filled with sample, temperature and pressure are
measured
▸CO2 solubility is temperature and composition dependent
▸Temperature: 0.05°C = 0.1 g/L
▸Sugar: 1°Brix = 0.1 g/L
▸Solubility coefficients of beverage types are stored in the instrument
Measurement Principles: Pressure / Temperature

▸Anton Paar’s at-line and lab instruments combine the
temperature/pressure and “Multiple Volume Expansion” (MVE)
methods
▸MVE measures the temperature and pressure equilibrium at two
different volume expansions
▸This method eliminated the influence of all other dissolved gases
Measurement Principles: Pressure / Temperature / MVE

Why?
The Beer Monitor has been the standard over 20 years!
Because…
▸Some installations only require the alcohol value (pre filler)
▸Some breweries do not need the highest accuracy
▸Some breweries want an “entry level” system (beer monitor light)
▸Compact size is easier to install and integrate
▸Lower cost of ownership & zero maintenance
A New, Low Cost Alcohol Sensor

Introducing: Beer Monitor Basic
The classic Beer Monitor: accurate, robust and proven

Beer Monitor Basic: compact, easy to install, low cost of ownership

An upgrade is always possible should needs change

▸Similar principle to the Original Extract Monitor
▸Alcohol and OE are determined via sound velocity and a stored
average brand density
▸Density is not measured, so real extract can not be determined
▸CO2 compensation optional but not necessary
Beer Monitor Basic: How Does it Work?

Maximum deviation in comparison to the Alcolyzer*:
Beer Monitor Basic: How Well Does it Work?
Beer Monitor Beer Monitor Basic
Alcohol ±0.03 ±0.06
Original extract ±0.06 ±0.10
Extract ±0.04 ±0.15**
*Lab reference: DMA 4500 M and Alcolyzer Beer **Calculated from stored value

Deviations between methods:
Density, sound velocity, IR transmission, IR ATR, temperature/pressure,
MVE, in-line, at-line, laboratory…
all may show small deviations in their results.
▸Why?
▸How do you minimize them?
Comparing Different Principles

In-line, at-line vs. package:
▸After filling, the CO2 changes
▸Head space volume and beverage
temperature influence CO2 content
▸At higher temperatures more CO2
moves from the beverage to the
head space
Comparing Different Principles: Why?

Comparing Different Principles: A Head to Head Test
How do you compare different measurement methods?
With a head to head test!
▸In-line data was recorded every 15 seconds
▸At-line measurements were made every 3 minutes

What did we compare?
As many methods as possible!
▸Carbo 520 Optical (process, ATR CO2)
▸CarboQC (at-line & lab, temp/pres. MVE CO2)
▸Beer Monitor (process, density/sound velocity)
▸Beer Monitor Basic (process, sound velocity)
▸Alcolyzer Beer (laboratory, NIR meter)
▸DMA 4500 M (laboratory, density meter)
Comparing Different Principles: A Head to Head Test

▸The Carbo 520 optical ATR sensor is factory adjusted with a standard
CarboQC using the MVE method
▸The Beer Monitor (density/sound velocity) is calibrated using DMA
4500 M (density) and Alcolyzer Beer (NIR)
▸The Beer Monitor Basic (sound velocity) is calibrated using the
Alcolyzer Beer (NIR)
Comparing Different Principles: ATR vs. MVE CO2

So what happened?
▸Between tank changes high variations in CO2 were seen due to
residual CO2 gas in the pipe.
▸Very short and high peaks are only seen with in-line sensors.
▸Long flow stops and high, quick temperature changes did not affect
the in-line optical sensor.

CO2 peak due to gas
pocket after tank change

Summary:
▸Optical in-line sensor correlates extremely well with at-line
temperature/pressure/MVE meter
▸Optical in-line sensor is drift free
▸Optical in-line sensor tracks quick changes accurately
▸SOPs and Best Practice are key to consistent results
ATR vs. MVE CO2 Test Summary

6 weeks & four beer styles later at a craft brewery in Pennsylvania…
Trial Criteria:
▸Overall measurement stability
▸Correlation to lab reference
▸Influence of batch to batch variations
Comparing Different Principles: Beer Monitor Basic

Excellent measurement stability

How does it correlate to the lab reference?
Lab reference: DMA 4500 M and Alcolyzer Beer
Alcolyzer Alc. %v/v Beer Monitor Alc. %v/v Deviation Alc.
Beer 1 4,51 4,55 -0,04
Beer 2 5,15 5,09 0,06
Beer 2 5,14 5,09 0,05
Beer 2 5,32 5,32 0,00
Beer 2 5,32 5,33 -0,01
Beer 3 6,71 6,75 -0,04
Beer 3 6,71 6,76 -0,05
Beer 3 6,72 6,75 -0,03
Beer 4 9,43 9,37 0,06
Beer 4 9,42 9,38 0,04
Beer 4 9,42 9,36 0,06
Min -0,05
Max 0,06
Std. Dev. 0,05

▸Filtered and bottle conditioned beer tested with equal accuracy
▸Good accuracy and repeatability
▸Density and RE variations have only minor alcohol influence
▸±0.001 g/cm³ = 0.06 % ABV
▸Easy to install, low cost solution
▸Ideal for final alcohol check before packaging
▸Zero maintenance
Beer Monitor Basic: Trial Installation Summary

We have existing formulas for:
▸Beer, wine, spirits, soft drinks, beer mix drinks, FABs, malternatives,
RTDs, cider, liquors…
▸If you are unsure, give us a call
▸Feasibility study costs nothing and lasts only 2-6 weeks!
Existing and New Applications

Presenter & Co-Author:
Daniel L. Gore, Brewer & Malter
Application Specialist - Process Instrumentation
+43 0316 / 257 3340
daniel.gore@anton-paar.com
Co-Author:
Josef Bloder, DI
Key Projects - Process Instrumentation
+43 0316 / 257 3210
josef.bloder@anton-paar.com
Contact Information

L17_Comparing measurement principles DLG1 AP

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