PEX COMPOUNDS | WIRE & CABLE
so well homogenised this does not happen,” Labbé says.
PM and Buss claim the more simplified design of the LSHC system, together with the use of some upgraded components, means it can produce cleaner XLPE compounds. The liquid antioxidant, for example, is filtered to 2 microns, the compound itself to 10 or 20 microns according to the applica- tion, and the peroxide to 3 microns. Meanwhile, 100% of the pellets are inspected for inclusions down to 60 microns prior to packaging. The closed nature of the LSHC process also contributes to cleanliness, says Labbé. “During the soaking with the traditional process there is more opportunity for contamination. Even if the inner pellet is really clean you can collect contaminants from the top of the soaking tower on the surface. With our process the peroxide is injected, then it goes to the boxing station and it is finished.” Labbé says older traditional soaking lines can struggle to meet the cleanliness levels required for extra high voltage applications of 500kV or more. “Older plant may take a couple of days to reach the super clean level. The process will stay at that level for a week maybe, then contamination comes back and they have to stop and clean the filters. For a modern traditional process it is a couple of hours to super clean mode,” he says. The LSHC system has not yet been validated at
commercial scale but the developers expect it to reach super clean production at least as quickly as the best soaking systems and to hold that state for longer. Work to date also shows that recipes used on a traditional soaking system transfer readily to the LSHC process. However, most high perfor- mance cable compounds must be qualified and Labbé says homologation would be required. Aside from the more homogenous and poten-
tially cleaner compounds, the LSHC technology provides considerable cost savings due to simplifi- cation of the process. Replacing the batch mixer, soaking tower and associated materials handling and heating infrastructure with the PEPA unit reduc- es the capital cost by 40% or more, according to Labbé. He says LSHC also avoids reheating the pellets and maintaining them at an elevated temperature during the soaking cycle, which reduces energy usage from an estimated 0.35 kWh/kg of XLPE to around 0.2kWh/kg. Users also gain from a more flexible production system that could, if required, be repurposed or relocated. “We say it is like Lego,” says Labbé. “If you go for the traditional process you have a 50m huge tower; this new process is just a compound- ing plant and you can do whatever you want with it.
www.compoundingworld.com
It is modular; you can transfer it from one location to another.”
Buss has a long association with cable industry. Its low shear kneader technology developed a leading place in PEX-b (silane crosslinking) compounding systems and the company has a strong position in the demanding semicon com- pound sector. It also supplies compounding extruders and engineers complete systems for use in single pass production of PEX-a compounds for LV cable insulation and for traditional soaking production of PEX-a HV and EHV cables. The company expects the new LSHC technology to help it make further headway in the new and growing market for extra high voltage DC XLPE cable compounds.
Changing markets “The market is going clearly towards extra high voltage DC and that wasn’t the case 15 years ago,” says Buss Head of Business Development, Innovation and Digitalisation Dr Krischan Jeltsch. “When someone is considering a traditional plant with a soaking tower, in terms of capex the price is very expensive. This new process is precisely developed for extra high voltage, AC or DC, and is more affordable in terms of money, people and maintenance.” LSHC’s energy savings should also not be under-
estimated, says Jeltsch. “The desire for ‘greener’ technologies has arrived in the wire and cable industry,” he says. “While lower generation of degassing by-products, such as methane among others, are already being realised by XLPE produc- ers, this new LSHC compounding process address- es the need for reduced energy and carbon footprint from an engineering perspective.”
CLICK ON THE LINKS FOR MORE INFORMATION: �
www.pm-ch.com �
www.busscorp.com
May 2023 | COMPOUNDING WORLD 29
Above: The new LSHC technology is built around the latest Compeo 110, 137 and 176 kneader extruders, providing throughputs of 1,000, 2,000 and 4,000 kg/h respectively
IMAGE: BUSS CORP
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