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Energy-cost squeeze pushing machine efficiency further

According to Germany’s energy information service EID (Hamburg), processors in Italy saw an average 22% jump in electricity costs from July 2007-July 2008. In Germany, energy costs, depending on region and provider, went up by an average of 8%-15% for the same period. Overall, extruder manufacturer KraussMaffei Berstorff (Munich, Germany) says that in the last eight years, prices of industrial electricity in Germany have jumped by 120%.

7 Min Read
Energy-cost squeeze pushing machine efficiency further

Market observers don’t see a decrease in energy prices in the offing and possible bottlenecks in supply could affect the sector well into the future. Ulf Thiele, senior design engineer at blowmolding equipment maker Kautex Maschinenbau (Bonn, Germany), says energy reduction has become one of the biggest issues concerning processors today. Christian Aigner, marketing manager at tenter frame manufacturer Brückner Maschinenbau (Siegsdorf, Germany) says, “In the past, efficient use of energy has only seldom appeared on the agenda [of customers] as long as a factory or production line was profitable. However, in today’s business climate, maximizing energy efficiency and minimizing pollution are more important than ever.” Adolfo Edgar, regional sales manager at blown-film equipment maker Brampton Engineering (Brampton, ON) says, “No doubt that energy saving is today an important topic for processors contemplating the purchase of new equipment since it will be an ongoing operating cost.”

Equipment makers are promoting energy savings with new market introductions, as well as pinpointing elements eligible for retrofit on existing machinery that can help processors reduce costs and get the most value from each pellet they process.

Aspects of efficiency
Blowmolding machine manufacturer Kautex Maschinenbau (Bonn, Germany) has, for example, opted since last year to install only EFF1 motors, said to be the most efficient available, for hydraulic drives on its equipment. EFF classification is based on standards set in the EU by the European Committee of Manufacturers of Electrical Machines and Power Electronics. Ulf Thiele, R&D process manager at Kautex, points to an annual saving of up to €690, based on 6000 hours energy consumption/yr, compared to EFF3 motors.

Other areas where the company achieves savings include reducing compressed air demands from a screw compressor by using the lowest possible pressure to obtain the desired end result. A traditional pressure of 13 bar, based on electrical consumption of 34.5 kW at €0.1/kWhr for effective free air delivery of 3.82 m3/min, results in an energy cost for 1,000,000m3 of €15,100. By lowering the pressure needed to 8 bar with effective free air delivery of 5.17 m3/min, Thiele says the electrical costs for the same amount drop to €11,100.

High on the list of ways to corral power costs is the elimination of air-pressure leaks in blowmolding equipment, he says. Based on production of 20L cans, blowmolding machines in general need 100 m3/hr of air, but even a 1-mm-diameter leakage point can cause €360 of energy loss annually, while a 5-mm-diameter compressed air leak means processors are laying out €8160 for lost energy.

Extruder maker Cincinnati Extrusion (Vienna, Austria) has come up with its patent-pending KryoSys technology to shorten the cooling length of an extrusion line producing polyolefin (PO) pipe, in wall thickness up to 150 mm, while saving energy. Such a line reduces the water cooling length by 56% and the air cooling length by 30% yet is said to increase output and total pipe quality. Key to the system is a special die head based on a spiral distributor design using water and air that cools both the exterior and interior. Heat is reclaimed and sent back to the material hopper to dry and pre-heat the pellets, thereby reducing extruder load by 10%.

Other areas where savings are achieved using the KryoSys technology include circulation pumps in the water tanks and the cooling system. This is packaged in a production line that is only 40m long compared to one of Cincinnati Extrusion’s standard lines, which is 85m. Josef Dobrowsky, product manager pipe at the company, points to the prospects of processors achieving €100,000/yr savings (based on 6000-hour production/energy costs of €0.1/kWhr).

Brampton’s Edgar admits that energy saving measures installed on equipment are not cheap, but says that payback justifies the investment. His company recommends installing hoods above extruders and dies to capture heat emitted, which is redirected elsewhere in the plant or offices, thereby cutting winter heating bills. Basic plant design is another area where processors should evaluate to save costs. “If a blown-film plant is designed with an adequate basement or tunnel where the air ring and the IBC blowers as well as the coolers are installed, then the air sucked by the blowers will be cooled and require less energy to be brought down to the temperature required by the process,” he says.

During winter months, processors in latitudes where temperatures drop significantly during winter months can draw exterior air for air rings and IBC blowers and thereby turn off energy-hungry chillers. Edgar says a savings of up to 17% can be achieved with this simple measure.

Brückner’s Aigner says total energy management has been a key selling point on the company’s big tenter frame lines for several years. The company promotes use of twin-screw technology, particularly for BOPET production, to eliminate drying costs and improve melt quality thanks to special degassing ports. Heat recovery, particularly on the transverse direction orientation (TDO) unit, results in saving up to 270 kW by recirculating the exhaust heat and absorbing condensation that can decrease film quality. Direct (water-cooled linear motors) drives and improved insulation are other areas to limit costs, he says. One of Brückner’s Chinese BOPP customers reports an energy savings on 28-µm film of up to 400 kWhr/tonne compared to a line in the facility used to produce the same product from a competitive tenter frame builder.

Processing equipment manufacturer KraussMaffei Berstorff (Munich, Germany) says it is now offering its range of 36D single-screw extruders for PO pipe production with three-phase, water-cooled AC motors, instead of air-cooled DC motors, to help customers reduce their power consumption. The company says the efficiency gain for processors is, depending on the operating point,  between 5-10%.

Greiner Extrusion (Nussbach, Austria) is offering as a customer service an energy calculator to reveal the energy consumption for each separate machine component as part of a project to slash energy costs, says company CEO Robert Grieshofer. Motors and vacuum pumps on calibration tables use the lion’s share of power on extrusion lines, he says. Greiner has calculated the individual energy consumption values for each component of its equipment portfolio. “In times of escalating costs, this information is the basis for a vital and extensive savings package for every company,” says Grieshofer.

Brückner, too, offers processors such an energy audit via its Brückner Servtec division to help film processors find weak points regarding wasted energy in their lines. Uwe Thönniss, Servtec managing director, says sometimes small alterations to older Brückner and competitors’ lines can result in big energy savings. As a case in point he says one measure is to find the optimized adjustment for fans for the TDO unit. In some cases due to line changes or alterations during years of service life, fan efficiency (standard: 50-70%) may have decreased, leading to energy loss. Retrofitting TDO fans with frequency converters that enable an exact adjustment of the motor’s performance can lead to a five-fold saving per fan annually.

Servtec also recommends replacing all-electric heating systems of the TDO unit on older lines with a combined oil/electric heater unit. Electrical heating is used during TDO startup to shorten heat-up time; afterward, during production, less expensive oil heating kicks in. “This technology enables a saving of about 60% in [heating] energy costs and the payback is less than one year,” says Thönniss. Nuroll (Caserta, Italy), part of Gruppo M&G, was so concerned about rising prices of electricity in Italy that it opted for an energy analysis and modification to direct oil heating of the TDO unit of its “line 1” earlier this year.

Antonio Tufano, site manager of Nuroll says, “This modification will greatly reduce the energy bill, and the payback time is extremely short.” Servtec was responsible for the engineering, supply, and installation of heaters, valves, and flexible pipes, while Nuroll organized its technicians and local subcontractors to carry out the piping and cabling work.

National governments are pushing processors to install more energy-efficient equipment in their plants to cut overall dependence on imported fuel. Servtec is installing a Heat Recovery System at Turkish film processor Polinas Plastik Sanayii ve Ticareti (Manisa) within a government-sponsored program: “Projects for increasing the efficiency of energy in industry (SEVAP).” BOPP processor JSC Mogilev Viscose Fibre Plant  (Mogilev, Belarus) has also opted to have modifications to its 6.6m BOPP line to reduce its dependence on imported energy.

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