Coperion: Know-how package for Polyolefin compounding

Current developments, experiences in industrial applications and future challenges in the large-scale compounding of Polyolefins were the focus of attention at the recent “Polyolefin Technology Update” conference in Stuttgart/Germany, the corporate home of
Coperion Werner & Pfleiderer GmbH & Co. KG. The two day conference, now the sixth one organized by Coperion Werner & Pfleiderer, took place at the end of October and was entailing a total of 21 lectures, six of which were delivered by guest speakers, and a highly informative factory tour. Manfred Eiden, CEO of the Coperion Group, welcomed over 100 experts from 35 companies and from as many as 20 countries. The main themes of the conference were all aspects of extruder design from start to finish, from drive train technology through screw configuration and barrel design to melt pumps, pelletizers and pellet cooling units, as well as processing aspects in compounding of the different Polyolefin resins, increasing capacities for different Polyolefins –especially Polypropylene –, utilizing the new ZSK NT two-stage twin-screw compounder technology, specially designed for bimodal Polyethylene, and the ZSK applications
for reactor melt discharge and devolatizing for processing LDPE and EVA. Of particular interest to users of existing compounding lines were questions concerning spare parts availability and supply of replacement parts along with possible modernization and debottlenecking of their equipment. In his welcoming address, Manfred Eiden presented the Coperion Group as a healthy and wellestablished global player which, contrary to the current trend in the plastics processing machinery industry, can boast a remarkably upward development: sales in 2005, expected to reach November 2005 380 million Euros, will be 23% up compared to the previous year. The 27% growth in incoming
orders, which will reach 420 million Euros by the end of the year, makes this upward development even more pronounced.
Matthias Gronies, CEO of Coperion Werner & Pfleiderer GmbH & Co. KG, then gave a brief overview of the continuing technological progress made with the company’s large-capacity twinscrew compounding extruders. In barely five decades, the output of around 500 kg/hour (ZSK twin-screw compounder with 120 mm screw diameter in 1958) has risen to over 65,000 kg/hour today (ZSK MEGAcompounder with 380 mm screw diameter). The basis of this success lies in the optimum combination of process engineering, mechanical engineering and production engineering expertise, as can only be expected from such a technology-driven company as Coperion Werner & Pfleiderer. The economic success of this corporate philosophy is also reflected in the fact that
around 6,900 compounding systems have been supplied by Coperion Werner & Pfleiderer worldwide – this being approximately 25% of all compounding systems – and that over 75% of all plastics compounds have been developed and tested in Coperion’s own R&D facilities.

Licensing – an early indicator of changes in the market
The two introductory guest lectures dealt with important aspects of the global Polyolefin market. In his lecture “A Licensor’s View of the Polyolefin Market”, Dr. Kaspar Evertz, responsible at Basell for the licensing business, explained how licensing is an early indicator as to where production capacities will be established or expanded within the next five years. After only negligible growth during the last few years, the production capacity for PE and PP is currently starting to expand to such an extent that by 2008 to 2010 capacity growth will be in the region of 10% per year. As this expansion of capacity is taking place primarily in the Middle East and the Asian-Pacific region, Europe and North America are changing from being net exporters to net importers of Polyolefins.
The licensing market also indicates that higher-output machines are being planned. This
development is not all that serious in the case of polymerizing plants, but it poses quite a
challenge for Coperion Werner & Pfleiderer as manufacturer of compounding and palletizing systems. The second important aspect was addressed by Sergio Paggi, the responsible technology manager at Tecnimont for Petrochemicals, in his lecture “A Contractor’s View of the Polyolefin November 2005 Market”. In single line Polyolefin production systems, which enjoy wider acceptance for reasons of cost, the compounding and pelletizing systems constitute the main component. Here the machine manufacturer must take up the challenge of developing a high-performance extruder that is both
reliable and flexible. The medium-term requirement for increased output rate is only one of numerous different application-specific requirements. An example of such a requirement is the compounding of HDPE and LLDPE with the same compounding extruder; this also goes for unimodal and bimodal Polyethylene, or for Polyolefins produced conventionally or with metallocene catalysts. And when it comes to executing projects, the manufacturer will have to resolve the dilemma that, on the one hand, a compounding system has a long delivery time, on the other, its technical specifications are determined relatively late, and perhaps not until intensive trials have been carried out by the extruder manufacturer.

Innovations push performance limits to new heights
The conference was chaired by Klaus Kapfer, Head of Business Unit Polyolefin Compounding. As moderator he tied together all the speakers, from their detailed views to the overall picture and put individual advancements and improvements into the perspective and challenges of a modern world-scale Polyolefin compounding plant. Besides descriptions of the design and mode of operation of the ZSK MEGAcompounder, including precise explanations of the conveying, mixing
and shear elements of the screws, the lectures that followed dealt with a great many different themes, the main ones being:
Optimization of Coperion melt pumps in combination with the compounding extruder to reduce
energy input and hence ensuring gentle treatment of the melt while increasing the output rate.
The newly developed ZSK NT for the compounding of bimodal Polyethylene. This two-stage compounder features a relatively small extruder with a fast rotating screw (e.g. a ZSK 250 with a screw speed of up to 700 r.p.m.) for melting the polymer. The second-stage consists of a larger extruder with a slowly rotating screw (e.g. a ZSK 350 with a screw speed of 80 to 150 r.p.m.) for homogenizing the melt and building up the pressure for pelletizing. Thus the “plasticizing” and “homogenizing” stages of the process are performed under respectively optimum conditions while at the same time reducing energy input.
The use of the ZSK MEGAcompounder with low density Polyethylene (LDPE) and ethylenevinyl
acetate copolymer (EVA) for direct reactor discharge and devolatization of the polymer:
November 2005 the MEGAcompounder’s high output rate not only makes it a highly competitive extruder in comparison with existing systems but also offers additional advantages through its palletizing system. In a large-scale test carried out under realistic operating conditions for the duration of almost 1 ½ hours, a ZSK 380 achieved an output rate of 68 tonnes/hour.
The broad spectrum of themes addressed during this highly informative conference was rounded off by the other four guest speakers, whose lectures dealt with the demands for electric motors with up to 22 MW power for extruder drive systems, the necessity for accurate metering of all components in such high-capacity plants, the possibilities of online rheometry on high output compounding lines, and viscosity feedback control in the reactive compounding of PP.

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