Bringing centrifuges up to speed with sustainability

The big task of questioning and optimizing

Success at GEA is never tiring. Instead, it serves as an incentive. “We do not strive to improve efficiency and conserve resources just for the sake of it – rather, it is part of our corporate DNA,” says Mackel. “We have always been working toward achieving the goals of better performance and more efficient machines, resulting in less wear and maintenance, not to mention less energy and water consumption.”

Although, over time sustainability has become more important. “That is why we have subjected all the relevant parameters to close scrutiny, looked at the entire life cycle from a sustainability perspective and taken a new approach to how we think about design,” he says.

Becker elaborates further: “It always starts with questions that are characterized today more than ever by the issues of sustainability and cost efficiency. Why does it cost so much to operate a centrifuge? Where are we using energy inefficiently? Where is potential for saving water and clean in place (CIP) media? Then we assess the operational and technical options for reducing consumption.” 

This is a departure from previous iterations. “In the past, if we wanted to build a new machine, we packed in more power – usually in the form of higher speed – while the bowl diameter was kept as small as possible,” says Mackel. “More power in the form of speed saves CAPEX, i.e., investment costs, but the higher power consumption then increases the running costs, i.e. OPEX.” 

The price of electricity was barely an issue until a few years ago. Today, things are different. “We are now thinking the other way around, designing larger bowl diameters and building the machines to run slower – 10% less speed, which is the equivalent to 20% less energy consumption,” he says. “That’s because customers are focusing their attention on kilowatt-hours – a particularly sensitive point when considering costs.”

The same goes for drive concepts where there are various losses in efficiency. GEA’s direct drive has made it possible to reduce these losses to a minimum. These concepts are also low-maintenance and space-saving while being compatible with large motors. In the past, engineers emphasized product – higher yield, better quality. Today, such factors have often been exhausted. “We are increasingly looking at how much energy and water the machine consumes over its entire service life,” says Mackel. Previously, for example, control water was added for seven seconds, but two seconds are now sufficient. When you add it all up, this makes a big difference.

Of course, GEA’s own production parameters also count. The aim here is to use as little direct and indirect energy as possible and consume the minimum materials in manufacture. Mackel puts this into perspective: “But what we save internally is only a fraction of what can be saved on the customer side later on with a machine service life of 20 to 40 years.”

The carbon footprint for 150,000 machines

Energy, water and material – these specifications must be precisely measured and recorded as part of the improvement process. Every year, the figure is determined for all machines sold, about 150,000 in total. “We know the efficiency levels of the installed motors, the areas of application and the predicted running times,” explains Mackel. From there, the number of kilowatt-hours each machine consumes per year can be determined. (One kilowatt-hour produces up to 0.9 kg of CO2, depending on the country and region.) 

Of course, not all electricity is the same. Customers who use green electricity generated from hydropower or wind power will have a significantly different balance sheet to those who use fossil fuels. The machine itself can also be traced back to its individual parts for later recycling. “We think in terms of raw materials rather than waste – in keeping with the idea of the circular economy,” Mackel adds. “The large bowls on the separators can be kept in operation for up to 30 years. At the end of the machine’s service life, they are melted down and fed back into the process.”

Waste nothing, that is the goal

Water is one of the most precious resources in the world and is also needed to operate centrifuges. Most water is consumed as either cooling water – both for the motor and for cooling and protecting the product from friction heat – or as control water for the discharging process. Since centrifuges discharge frequently – sometimes every two to three minutes – a lot of water can be saved. Whereas control water used to be added for seven seconds, two seconds now suffice – with one second of control water corresponding to about one liter of water, says Jürgen Mackel. “We are also currently working on solutions to find out how we can use the cooling water – which has been heated from 20 to 40 degrees – elsewhere in the process. That’s over 150 liters per hour on average. The water used to end up in the sewer, but it is now not only used for hand washing – it is also safe to drink because we have closed systems.”

The centrifuge’s energy consumption is just as important. Two energy-saving concepts have been developed here: EngySpeed, which refers to the separators with a larger diameter and lower speed, and EngyVac with a vacuum between the bowl and the hood. Regardless of whether the machine is smaller and rotates quickly or larger and rotates more slowly, the clarification area, throughput and separation efficiency remain the same with EngySpeed. “The speed has a greater impact on the friction than the diameter,” explains Mackel. “The tried-and-tested means of saving energy therefore involves reducing the speed to a quarter of the value of small, high-speed machines.” 

But how quickly does the larger bowl diameter pay for itself in energy savings? In a typical example taken from the dairy sector, based on an average operating time of 6,000 hours per year and a throughput of 25,000 l/h at an estimated electricity price of 30 ct/kWh, the larger system pays for itself in 2.6 years via energy savings. “One major advantage over vacuum machines is that no additional power unit is needed,” says Becker. “In other words, customers get a standard machine and a service concept for the larger machine whose costs are comparable to those for the smaller one.” The large machine with EngySpeed rotates more slowly and thus has longer maintenance intervals for certain assemblies. This is particularly important in the dairy business, where there is a contractual obligation to deliver milk.

EngyVac is typically deployed in the largest product series and centrifuges in the upper power ranges, where reducing the speed is not an option. Here, amortization is often not the decisive factor when investing in sustainable equipment. Instead, compliance with regulatory requirements to save energy or achieve sustainability goals often plays a greater role.

CIP – a secondary role with real potential for improvement

Another idea is to purify cleaning media, CIP liquids, with a clarifying separator – to remove solids so the medium can be used again. The product manager knows from experience: “Especially in the dairy sector, we have cases where dozens of tons of CIP liquids are simply dumped every day,” says Becker. The GEA CIPClean Separator reduces the environmental impact, cuts water consumption and reduces the energy needed to process fresh CIP medium. The recycled CIP maintains residual heat.

The power of speed and other variable parameters

At some point, the designers reach their limits. This is where intelligent automation solutions come into play – such as InsightPartner Separation. “Automation is the new key to saving: Perfect performance, when it is needed,” says Becker. “And proactive service to make predictive calculations with maximum uptime.”

Things are also getting interesting around data-collecting sensors that help control centrifuges. “We also like to break new ground in terms of what is feasible when it comes to design, which is what makes our job at GEA so exciting,” says Becker. “For more than 130 years now, we have been rethinking centrifuges and will continue to do so for the next 130 years. And we remain curious.”

It goes without saying that nothing is left to chance at GEA. “The company’s innovation management also cultivates an innovation community,” adds Mackel. “Contributing to innovation is the duty of every single employee, and that can and should be fun.”