Companies that produce polyolefins, PE, PVC and PET in old plants are under pressure from spiralling costs and the need for modernization to meet environmental and safety standards. ThyssenKrupp Uhde offers solutions.
Only the best is good enough — this well-known saying applied to the polymer plants that were constructed during the plastics boom between the 1960s and the 1980s. After World War II, polyolefins, PVC and polyester began to take off. During the boom years up to 1980, Germany, for example, rose to become the third biggest producer of plastics in the world, with an annual output of 4.5 million metric tons, behind only the USA and Japan.
This rise in global demand was also reflected in the number of factories that were erected across the world. However, plants that were state of the art when built 30 to 40 years ago, are now starting to show their age. For the operators, it is all a question of whether a retrofit is worthwhile or closure is the better option.
Dr. Rolf Guth, Head of Technology Service Polymers at Thyssen-Krupp Uhde, knows from experience the dilemma facing operators — after all, the Dortmund-based engineering company has a long tradition in the engineering and construction of production facilities for polyethylene of all densities (PE), polypropylene (PP), polyvinyl chloride (PVC), polyester (PET) and polyamide (PA).
When is it worth revamping a plant?
Firstly, tougher environmental and safety requirements are making life difficult for operators. Primarily, though, it is often the product spectrum of the old plants that no longer meets the needs of the market.
In addition, the traditional plastics giants are facing increasing competition, with resource-rich Arab countries building gigantic chemicals complexes equipped with world-scale facilities that are forcing down prices for mass-produced plastics. The market researchers at Ceresana Research expect to see Saudi Arabia, Qatar and Iran boost their low-density polyethylene (LDPE) capacities by 3.5 million metric tons through 2014.
Specific production costs are therefore usually the main reason for revamps. “Older LDPE plants often still use the autoclave process for mass-produced plastics, for instance, and are therefore no longer cost-effective to run”, Guth explains. Dow Chemical, for example, explained their closure in 2009 of an LDPE plant commissioned in 1959 with the fact that replacing the outdated technology would have cost too much. The arguments that Pieter Platteeuw, Global Business Director for LDPE, gave at the time are typical, reckons Guth, because if an operator thinks a plant is not worth revamping, the only option left is to shut it down.
Today, the majority of LDPE plants contain tubular reactors that allow production capacities of up to 400,000 t/a, while old plants can produce at the most half of that, and usually only 100,000 t/a. Tubular reactors have also led to a change in the product spectrum, as they now allow the production of copolymers with a vinyl acetate fraction of up to 30% (EVA copolymers). Copolymers with even higher EVA fractions can now be produced cost-effectively in modern autoclaves of much greater volume.
Whether retrofitting an LDPE plant with a capacity of 200,000 t/a at all, for example, is shown in a study that works through four scenarios:
- pure debottlenecking;
- modifications in reaction & product cleaning;
- modifications in reaction combined with debottlenecking;
- modification in reaction, product cleaning plus debottlenecking.