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Crude tar plant chooses Endress+Hauser for level measurement

Crude tar refining factory Koppers Australia has installed a new level measurement solution from Endress+Hauser to operate two continuous tar distillation units and a naphthalene still to produce coal tar bi-products, carbon black and timber preservation chemicals.

The pungent smelling, viscous and abrasive crude tar is the by-product of the coal used in coke ovens in the steel manufacturing process. It is also the source of oil products required for timber processing and tyre manufacturing.

Given its aggressive chemical properties and high process temperatures, ensuring minimal down time at a crude tar refining plant is indeed a challenge, says Endress+Hauser.

At its facility in Newcastle, Koppers operates two continuous tar distillation units. Heat is applied to distillation columns containing crude tar and the resulting vapours of naphthalene and creosote are captured and condensed.

The entire process consists of a series of distillation columns each with precise level measurement and control. This can be a challenge as temperatures exceed 350°C and the condensate is corrosive and abrasive, says Endress+Hauser.

Koppers operated its plant using displacer level measuring devices which work on the principle of buoyancy. This mechanical level measuring instrument is sometimes used in chemical and petrochemical plants.

In a crude tar distillation process, the displacer frequently gets coated leading to a change in the buoyance of the displacer and therefore inaccurate measurements. Tar deposits on the arm and joint mechanism also impair movement leading to faulty readings.

The Koppers team had settled into a routine of high maintenance and frequent calibration since the cost of failure and downtime is very high. The distillation columns are connected in series and production of the entire line is affected if there is a fault on any one column. Failure to control levels within optimal and safe limits can also result in damage to the plant, said Endress+Hauser.

Given the mechanical displacer’s high maintenance and frequent calibration requirements, and potential hazards, the Koppers team was keen to identify a reliable, safe alternative.

They settled on Endress+Hauser’s Levelflex FMP45 which uses ‘guided radar’ to measure the distance to the surface of the product. This version is ideally suited to the harsh operating conditions, being able to withstand pressures up to 400 bar, and temperatures from -200ºC to +400ºC.

There are no moving parts and the distillate properties have no adverse affect on Levelflex’s reliability or accuracy.

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