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Singapore, August 2012
Claus Weihermueller
Case Study: POLYETHYLENE TEREPHTHALATE (PET) Polycondenzation
Place for application relevant picture!
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Agenda
Customer and Case 1
Application Description 2
FLEXIM Solution 3
Customer Benefits 4
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PET – history and applications
PET is short for polyethylene terephthalate - the chemical name for polyester. PET is made by
combining ethylene glycol and terephthalic acid under high temperature and low vacuum pressure to
form a polymer chain. The resulting polyester polymer is extremely stable, tough and essentially inert.
PET is highly resistant to chemical or biological reaction with other substances. This non-reactive
quality is at the heart of PET's safety.
PET was first synthesized in the U.S. during the mid-1940s by DuPont chemists, who were searching
for polymers that could be used to make new textile fibers. DuPont would later brand these polyester
fibers as "Dacron."
In the late 1950s, researchers found a way to stretch a thin extruded sheet of PET to create PET film,
which today is used extensively as video, photographic and X-ray film, as well as for packaging films.
In the early 1970s, the technology was developed to allow for the blow-stretch molding of PET into
strong, lightweight and shatterproof bottles. In 1973, the PET bottle was patented and quickly gained
market acceptance. In 1977, the first PET bottle was recycled.
Today PET is one of the world's most commonly used, versatile and trusted materials. More than half of
the world's synthetic fiber is made from PET, and almost all individual-sized bottles of carbonated soft
drinks and water sold are made from PET resin.
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Customer and Case
Sail Cloth are typically made out of PET
resin – better known as polyester or the
brand name DRACON
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Agenda
Customer and Case 1
Application Description 2
FLEXIM Solution 3
Customer Benefits 4
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PTA
PET is made by combining ethylene glycol and terephthalic acid (PTA) under high temperature and
low vacuum pressure to form a polymer chain.
Terephthalic acid is the organic compound with formula C6H4(COOH)2. This colourless solid is a
commodity chemical, used principally as a precursor to the polyester PET, used to make clothing and
plastic bottles.
By 2006, global purified terephthalic acid (PTA) demand had exceeded 30 million tons / annum.
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Application – PET polymerization process
FIT
PTA, Glycol and Catalyst
are mixed in the
esterification reactor.
From there the high viscose
slurry mixture is pumped
into the polycondensation
reactor
The Flow Measurement is
important to monitor the
pump performance and to
control the batch.
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Application – earlier used Flow Technology
Initial installed technology - Coriolis Omega Tube 3” size
The PTA /Glykol / Catalyst mixture is a high viscosity slurry.
Due to the low flow velocity (of 0.2m/s in 6” size) particles tended
to foul the Omega tubing causing the Coriolis meter to drift
Another vendor of Coriolis meter promoted his Straight Tube
design which consists of much shorter tubes without bends and
was supposed not to accumulate particles
Nevertheless the Straight Tube Coriolis design has to be taken
out of the process to be cleaned monthly.
RECRON was searching for a flow meter technology which can
operate long time without being affected by particles and
viscosity.
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Agenda
Customer and Case 1
Application Description 2
FLEXIM Solution 3
Customer Benefits 4
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Application - Measurement Point
INSTALLATION of GRK Transducers in DIRECT MODE on 6” SCHED10 stainless steel pipe
Diagnosis values obtained PTA/Glycol mixture
SNR: pink color (around 35 dB)
SCNR: blue color (around 42 dB)
Gain: green color (around 60 dB)
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Solution - Performance
Measured flow velocity stable at 0.20 m/s
The medium has shown to have a high viscose
signal damping. The measurement is possible with
Lambwave in single (direct) path only
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Agenda
Customer and Case 1
Application Description 2
FLEXIM Solution 3
Customer Benefits 4
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Solution - Results
RECRON Malaysia is operating 4 PET plants with 2 polymerization reactors each.
Recron has made budget to install the first 2 Clamp On meters in late 2012 to proof operational
reliability for 4000 hours and will then replace the other 8 straight tube coriolis installations
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Evaluation of Potential
PET is a commodity and is produced in the countries where it is used, hence PTE plant can be
found in any country.
The medium is a heavy slurry with viscosity up to 100 cSt. We tried CDM transducer in direct
mode with no result. CRK transducers work very well in direct mode but are not strong enough
for reflection mode installation.
So far it seems that Coriolis meter in size 3” are the industry standard here. Those meters are
expensive in Capex and have to be cleaned regularly.
RECRON assured us that the purpose of the measurement to the reactor is for monitoring and
accuracies of 2-3% are absolutely sufficient here.
From what we have seen so far I must believe that our regular competitors as E+H, GE,
KROHNE and so on wont be able to handle this application.
I therefore give it a high priority to pursue the PET plants in your territory