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Radiotracer forProcessInvestigation
the authors:Albert Zeuner Peter Krüger
Fraunhofer Institut für zerstörungsfreie Prüfverfahren, Institutsteil DresdenMaria-Reiche-Straße 2, D-01109 Dresdenwww.izfp-d.fraunhofer.de
VeranstaltungOrt, Termin
4th International Freiberg Conference on IGCC & XtL Technologies
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Process investigation - Radionuclides ?
Process investigation seeks correlations between
pressurestemperatures
amounts andconcentrations
flowsbalancies
of materialsand energies
depending ondepending on-- time andtime and-- location in the reactorlocation in the reactor
investigation options:• unique investigation at constant
parameters
• repeated investigation with variation of parameters
actual conditiongives
interrelationsgives
derived from this:
elapsed timefilling degreebetween different
reactor sectionsmaterial velocity
residence timereaction timemixinghomogeneity
process parametersresult(product) and
RADIONUCLIDES may be useful in the following fields:qualityquantity
tech
nica
l and
econ
omic
para
met
ers yield
degree of reactioncosts of material
energyplant
of product
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measurement ofinherent radioactivity
use of„open“ radionuclides
What can you do with radioactivity ?
• own radioactivity for non-destructice material analysis• potassium determination in potassium salts
• potassium (raw) salt is a mixture from about 80 % of NaCl and only 20 % KCl. Because natural potassium contains a radioactive isotop (K-40), it is possible to estimate the potassium content during the process by measuring the radioactivity
• radionuclide measuremtent in human body• „Body counter“
• earth and water analysis• gammaspectrometry
• localisation („labelled atoms“) – also non-destructice• tracing of fertilizers in plants• nuclear medicine (incl. emission tomography)• residence time measurement in technical equipment• mixing investigation
• use of interaction (between radiation and material) – also non-destructice• measurement of fill level, thickness, density, grammage• compound analysis• structur analysis• (transmission) tomography
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application:nuclear medicine
technics
principle: • addition of a (radioactive) indicatorwhichever indicator?how much?
„labelled atoms“ allow
• residence time (and mixing) investigation
• szintigraphy in nuclear medicine:• residence time analysis in continously
working technical equipment• mixing investigation
• conclusions about the radiation origin
justifiable?• conclusion about the behaviour of the
material of interest
measuring technique• measurement of the indicator concentration
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labelling of material (with radionuclides)
but properties must be not different from the original material.
prob
lem
2:
„labelling paradoxon“
solu
tion:
radiotracer:
• extremely low concentration= practically no change of properties• extremely good detectibility
in addition: • decay of radioactivity enablesfurther use of the product
some remarks to:
to label something (by an indicator)leads to a change of properties
good detectabilitybut big change of propertiesexcessive indicator
low change of propertiesbut bad detectibility
insufficient indicator
prob
lem
1:
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radiotracer application scheme
process section of interest improvement ofprocess regime
yieldconversion
energy consumptioncosts
transferfunction
process-interpretation
process control
labelling measurement interpretation
outs
ide
dete
ctor
s
taki
ngsa
mpl
es
radiationmeasurementand correction
inpu
tsi
gnal
feed
er fo
rla
belle
dm
ater
ial
technicalphysical conditionschemical
(radioactive) contaminationof environment
radionuclides
propertiesnuclear physicsphysicschemistry
availabilitycost
radioactivelabelling
of a material sample
choice ofradionuclide
activity estimation
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important relations:
labelled substance= source of radiation
activity is defined bydecrease of atom quantity
time unit
radiation
radiation emission =quants (resp. particles)
time unit
detector (measurement)
produceselektrical pulses
time unit(puls density / puls rate)
specific activity ∼
concentration
some transformations:
A A e t= ⋅ −0λ
A N= ⋅λ division by V
A
puls rate at the detector
radiation intensityproportional
activity / activity concentrationproportional
indicator concentrationproportional
conclusion
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radiation measurement under technical conditions
scintillation detector,
if required: (measurement at hot plants) inserted into an
cooling jacket (water, air)
20°
120
Ø
20160
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cooling jacket with detector may be inserted into an collimator (e.g. lead, tungsten), so that the
detector receives radiation only from a desired solid angle
some remarks to:
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modular (from single slices) tungsten collimators allow in connection with a sandwich plate more sensitive radiation measurements
modulartungsten collimator
with scintillation detector
sandwich plate
possibility for for four detectors
example 1: special equipment for measurement at an extruder
labelled with Tc-99m, half-life 6 h
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residence time distributions in an extruder along the transport path
5 residence time distributions *
*
* time scale with regard to tracer injection („zero“)
5 detectors (or groups of detectors)
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equipment in investigation:
•vertical tube reactor
•high-velocity gas stream
example 2: special equipment for measurement at an gas reactor
©© TU Bergakademie FreibergTU Bergakademie Freiberg
•
multiple detector planes,each collimated by some layersof lead bricks(5 x 10 x 15 cm³)
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layers of lead bricks(collimation for detectors)
flexible tubefor cooling water
©© TU Bergakademie FreibergTU Bergakademie Freiberg
special detector assembly:some detectors in one plane= addition of detector pulses
special equipment for measurement at an gas reactor
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, half-life only 109 min, noble gas4118Ar
special equipment: measurement at an gas reactor
• half-life is short with regard to transport by car
• for that reason
radionuclide:i.e. no chemical reactions = transport of the gas phase
• is produced by (n,γ) activation in the research reactor of the HMI in Berlin
• half-life is long enough for measurements in gas streams
• emits high energy γ-radiation (1.293 MeV), suitable to penetrate metal walls
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gas reactor: measured residence time distributions
0.040.060.080.100.120.140.160.180.200.220.24
0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0Normalised residence time t/tm0
Signal: Upp. free space (2)Signal: Outlet (6)Approx. by convolution
0.000.02
0.0
Prob
abili
ty d
ensi
ty E
(t)
catalystcatalystlayerlayer
6
2
natural gas +oxygen + steam
synthesis gas
Source: Zeißler et al., CIT 2006, 78, No. 1-2
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• Radionuclides in sealed and open Form are very suitable for process control and analysis and for investigation of chemical and medical problemes
• sometimes there is no alternative to radioactivity(thickness of tubes, filling level, γ-defectoscopy; nuclear medizine, reactions under high
pressure or vacuum)
• open radionuclides have some advantages in the investigation of material transport and mixing processes• (practically) no pollution of the product• no samples needed• contactless measurement through the walls of the plant• information about the tracer concentration at many positions• on-line measurement• after decay the products are usable without limitations
• measurements by working groups with special measuring technique• we have a legal permission and work - of course - in accordance with radiation
protection specifications
Summary 1
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We have used open radionuclides in the followingfields of investigation
Summary 2
residence time investigation•
gas: natural gas conversion
•
liquids: organic matter, water balance, sewage plants, filtrationoil consumption of combustion engines
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fluidized bed: particle growth in a granulation fluidized bed
•
solids: conveyors, dryers, rotary kilnsmillssynthetic fibres, polymers, extruders
homogeneity•distribution of binding agent in rock wool
single particles•CARPT (Computer Aided Radioactive Particle Tracking) in a screw conveyor
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We thank youfor
yourattention
Albert [email protected]
Peter Krügerpeter.krueger@izfp-
d.fraunhofer.de
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