the new techpap nir spectroscopy for recycled …spectroscopy for recycled paper bales inspection...

Speaker: Didier Rech (Techpap)

Authors: -Alain Cochaux (CTP – France)-Pascal Borel (CTP – France)-Guy Eymin Petot Tourtollet (CTP – France)- Didier Rech (Techpap)

The New Techpap NIR spectroscopy for Recycled Paper Bales Inspection

28th Research Forum on Recycling, Niagara Falls , septembre 2007

Content of the presentation

• General presentation of topic : problems & solutions proposed

• NIR spectroscopy• First trials in laboratory with NIR spectroscopy• Our industrial “recovered paper bales quality control”

sensors• First industrial trials in a mill : procedures & results

obtained• Last industrial trials ... completed !

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1.1 Problem: recovered paper bales quality control

• Increasing necessity for papermakers to control, at delivery, recovered paper bales to ensure raw material quality & to pay the “right price”

• Crucial interest for papermakers:• Measurement of moisture• Detection of possible presence of unusable materials

(metals, plastics, etc)• Distinction of different raw materials (paper / board) for

coherence with EN643 standard (1.04, 1.05 …)

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1.2 Current control procedures used

• Generally speaking, they are :• Manually made• Very long and tiresome for operators

example: core sampling & traditional measurement of moisture• Limited objectivity

example: visual and/or manual controls

• Consequence : Low efficiency so papermakers certainly “lose money” …

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1.3 Solution proposed

• To do that, we have developed a sensor based on a new approach : Core-drilling device & Near Infra-Red (NIR) Spectroscopy

• The objective of MONITOR project is to develop an easy-to-use sensor:• Direct, rapid, objective, reliable, low cost• To control in recovered paper bales at delivery:

MoistureUnusable materialsGrades

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2. NIR spectroscopy (in a few words …)

• Already used since several years in different sectors (food processing, chemicals, drugs …) to study the composition of samples (in particular: moisture measurement)

• Papermaking sector: « emerging » and « promising » technology for the future

• Main advantages:• powerful technique to precisely study samples composition• no need of sample preparation• low price• very rapid (~ 50 ms / spectrum) ~ 200 measurements

in only 10 seconds

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Sample to study

Reflected photonsNIR Spectrometer

Light source with 800nm < λ < 2500nm

Composition of sample

Black Box = Multi-Linear statistics models (for predictions) obtained by “calibration /

learning”

Black Box

Black Box

2. NIR spectroscopy (in a few pictures …)

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• Development of a “lab prototype” to simulate the behaviour of a coring device used with our NIR equipment:

Displacement of sample

Measurement window

Fibre with measurement head

3. First trials in laboratory with NIR spectroscopy

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• Samples (cores) were made with different moisture contents

• For each core, we have done:

•Acquisitions of NIR spectrum (= inlet data X)

•An accurate traditional measurement of moisture: weighing, complete oven drying, re-weighing

(= outlet data Y)

3.2 Moisture measurement

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12 %

18 %13 %

20 %

10 %

8 %

7 %

Two « λ bands » seem interesting (around 1440 and 1940 nm)

Dynamic more important around 1940 nm

• Using statistical methods, several moisture prediction models were built and tested :Δ = « accuracy » of the prediction model = ± 0.35 %

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Same “procedure” as for moisture : making of cores with different compounds, building of prediction models ( = calibration) & tests

•Choice of the different compounds to take into accountAluminium (metals), 3 kinds of plastics (types:PP, PE, PET), paper and corrugated board

•Acquisitions of core spectra with 100% of each compound (for calibration)

•Acquisitions of core spectra with blends of several compounds (for tests)

8 “blends cores” were made with random %

3.3 Unusable & raw materials measurements

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Plastics Papers

1700 nm < λ < 2150 nm

Water / Papers

Using this « λ band », the system is able to distinguish the different compounds

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The first results obtained in lab with the NIR spectroscopyhave allowed us to check the use and the discriminant capability of this approach for moisture and unusable materials that we would like to characterize (metals, plastics) vs raw materials (paper, board)

Conclusion of these first laboratory studies

Manufacture of an industrial prototype

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• Two versions of the sensor have been developed:

•An “embedded” version : to instrument an industrial coring device, in order to perform direct control at delivery on trucks. This sensor was made to be fixed directly on the output pipe of any coring device.

•A “transportable” version : less precise and efficient than the first one, but also much less expensive (no need of a coring device). This sensor is hand-held and it has to be introduced in a hole done with a “simple” drill.

4. Our industrial sensor for “recovered paper bales quality control”

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Spectrometer

Light source power

PC

control buttonsoptical fiber / power wire

Industrial rackcoring device

measurement head

control buttonsscreen

Synopsis of our complete sensor:

4.1 Our monitor sensor:“embedded” version

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pipe with optical fibre & power wire

measurement head

NIR light source

reflected signal collection

• The head is very light and very rigid• Total length of the head = 20 cm• Inside the head : optical device to optimize the light illumination

& the signal collection in the optical fibre

Some details aboutthe measurement head …

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• All the acquisition and data processing device is the same as for the embedded version, except for the measurement head which is longer (1m), to be introduced directly in a hole done with any perforating device

4.2 Our MONITOR sensor:“transportable” version

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• We have used an industrial coring device with our MONITOR sensors for industrial trials programs

• Trials have been carried out on ~ 70 bales(= ~ 150 cores), and for each bale core:

• NIR spectra acquisition• Recording of the corresponding outlet data wanted

Black Boxspectra

Moisture

EN643 classification (1.04 / 1.05)

% of unusable / raw materialsBlack Box

Black Box

5. First industrial trials in a mill:procedures & results obtained

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« accuracy » of the prediction model = ± 0.75 %

5.1 Results obtained:Moisture prediction

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• For metals prediction : we can’t conclude with the data obtainable (because only 5 values are not 0 % and the max. value is “only” 0.5 %)

• For plastics prediction :

5.2 Results obtained:Unusable materials prediction

« accuracy » of the prediction model = ± 0.45 %

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• After the first encouraging trials in a mill, different adaptations (mechanic, hardware, software interface) were done on our prototype to fit it to an autonomous and continuous use in mill by operators

6. Last industrial trials performed

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• A new trials program (still in progress) has started for a long duration period with one of our industrial partners

• These trials have allowed us to identify and to correct some adverse industrial conditions relevant to the industry (clogging, mechanical constraints, …)

• Now, the sensor seems to work well, and we are beginning to obtain interesting results …

6. Last industrial trials performed

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6. Last industrial trials performed(still in progress) : a few results …

Plastics prediction« accuracy » of the model = ± 0.5 %

Moisture prediction« accuracy » of the model = ± 1 %

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• 2 versions available :• Easy-to-use• Direct• Rapid• Objective• Reliable

• Short pay-back

the “recovered paper bales quality control” sensor