Description

Level measurement of feedstock tanks

Requirements

  • Horn antennas (without gasket) for corrosive media (PP or PTFE)
  • Bent antenna extensions for tanks with internal obstructions

Description

Inflow measurement of catalyst

Requirements

  • High accuracy mass flow for catalyst
  • Available in four sensor materials: titanium, stainless steel, Hastelloy® or tantalum

Description

Level measurement in esterification reactor

Requirements

  • Extensive choice of probes for harsh process conditions
  • Converter is rotatable and removable under process conditions

Description

Pressure measurement in esterification reactor

Requirements

  • Process control

Description

Flow measurement to polymerisation reactor

Requirements

  • High accuracy mass flow and density measurement
  • Device commissioning, verification, diagnostics and monitoring via a secure wireless Bluetooth

Description

Pressure measurement in polycondensation reactor

Requirements

  • Process control

Description

Temperature measurement during recirculation of intermediate products

Requirements

  • Chemically resistant PTFE or similar coating for all wetted parts available
  • Tapered Tip for fast reaction

Description

Flow measurement of waste products from pre-polymerisation

Requirements

  • Certified for safety applications up to SIL 2/3
  • Integrated conductivity measurement

Description

Flow measurement of distilled reaction water from pre-polymerisation

Requirements

  • High measuring accuracy and long-term stability
  • Full on-site verification without process interruption

Description

Level measurement in tank with granulated PET end product

Requirements

  • Remote versions to facilitate access to the device
  • Tank Bottom Management with dedicated algorithms to filter and compensate for irregular radar wave reflections

Description

Integrated control valve with flow, pressure and temperature measurement of water

Requirements

  • Local measurement and control of flow
  • High control quality

Overview

Polyethylene Terephthalate (PET) production in plastics & polymers production

Instrumentation for Temperature- and Pressuresensitive PET Production Processes

Polyethylene terephthalate (PET) is used in the manufacture of blow-moulded plastic bottles (PET bottles) and in films amongst other things and is one of the main synthetic fibres. In order to produce PET, the monomers terephthalic acid and ethylene glycol extracted by petrochemical means are esterified in the reactor at a moderate pressure (2.7–5.5 bar) and high temperature (220–260°C) using a catalyst. In a second stage, gradual pre-polymerisation is performed, whereby separated water and waste products are continuously removed from the reaction mixture, as otherwise the reaction would be inhibited. In parallel to this, reactive intermediate products are returned to the esterification reactor. The final polymerisation stage takes place at up to 280°C and at very low pressure (< 1 mbar). The PET fibres can then be produced from the extracted molten polyester using the melt-spinning method for example.

PET manufacture must not only fulfil food regulatory limit values and taste requirements, but nowadays the plant must also significantly reduce energy consumption and sustainably lower operating costs too. This involves keeping the process variables of flow rate, pressure and temperature within narrow limits, which requires comprehensive monitoring. KROHNE offers the ideal technical measuring systems for this, such as industrial/resistance thermometers for use in piping and tanks. There are also pressure transmitters to simultaneously measure the process pressure and fill level up to +200 °C as well as radar level meters for liquids, pastes and sludges, which are suitable for continuous, non-contact level measurement in storage and process tanks. And 2-wire level transmitters with guided radar come in a wide range of sensors and materials, which means they can even be used in high pressure and temperature conditions.

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