Oven Technology: Steps towards a lower footprint
Victoria Barrett, sales and marketing manager at Greenbank Technology, talks about how new oven technology is helping to reduce energy consumption
With the current global focus on sustainability, renewable energies and the shared goal of becoming carbon neutral to prevent further damage to our planet; there is no wonder the metal packaging industry is booming. Forever easily recycled, using relatively small amounts of energy and no loss in material quality, make metal the easy packaging choice for an eco-conscious brand.
But just because beverage cans are the most sustainable single-use beverage packaging doesn’t mean we should stop there. The more we can do as an industry to collectively bring down the carbon footprint of each can through every aspect of the process and supply chain, the better.
Breaking from tradition
Traditional ovens and their processes pose a problem for can makers, as historically their excessive use of gas cannot be offset, with their two main fuel sources being natural gas or LPG. But oven suppliers, alongside can makers are focused on helping to achieve the collective industry sustainability goals no matter how difficult. There have already been many changes introduced to reduce the consumption of energy within the process and we have an ambitious idea for what the future of can making will look like.
Steel to aluminium
One of the biggest changes to the thermal processes from within the industry was the change from steel to aluminium and the downgauging that followed. Although the metal finishing processes didn’t change in a direction to significantly reduce cure times or temperatures, the energy required to heat a lightweight aluminium can is vastly less than what was required to heat heavier steel cans. The footprint of the ovens has reduced because of this, as well as reduced airflows required which, put simply, means less gas is burned per can and even less power is required to operate the fans.
Efficient fans
While on the subject of the fans, more efficient types are now available, such as ones that use aerofoil fan blades that use less power to move the same volume of air than a traditional backward curved fan. As well as this, the majority of newer oven designs feature direct driven fans instead of belt driven fans which can see up to 10 per cent less motor power required to drive the impellor.
Another new fan feature is the addition of VFDs rather than running fans at full speed and relying on dampers to control the airflows. Secondary to the obvious benefit of this, it also allows for more accurate fine-tuning, which in turn reduces spoilage.
Height adjustment
The automatic height adjustment and recipe loading inside the IBOs and washer-dryers also have a significant impact. In the past where can makers might settle for a rail height between two can sizes with a similar trimmed can height, and have to compensate with higher temperatures or airflows for the smaller can size, it can now be adjusted at the push of a button, as well as loading the settings that were saved from the last time that size was run.
Nozzle designs
In addition to having the nozzles in the optimum position for all sizes now, oven manufacturers have improved their nozzle designs in recent years for more effective and efficient air delivery to the cans. This further reduces the need for excessive airflows or temperatures in the ovens, to the extent that where we used to require 18 passes and two zones in a pin oven to achieve a good cure, we can now do that with a single zone across 12 passes. It’s not only in the pin ovens that these designs have been optimised though, IBOs and washer-dryer ovens have also seen improvements in nozzle design.
Insulation quality
Another aspect of the oven build/design that has changed for the better is the improvement in quality and amount of insulation. The external oven walls are no longer littered with signs warning operators about the danger of hot surfaces. This improvement is three-fold – not only are the ovens becoming better insulated and therefore more energy efficient, but are removing a hazard from the shop floor and making the environment around the ovens a more comfortable place to work for the operators.
Vacuum fans
One specific improvement to the washer-dryers has been the add-on of vacuum fans to an extended area infeed. This has been designed to pull water from the belt and can, minimising the amount of water actually entering the dryer and therefore reducing the temperatures and air flows required to completely dry the cans.
Burning process
Now onto the main source of the problem in the process – the burners. Although at this moment in time we are limited to burning either natural gas or LPG as the two main options for our process requirements, the burner controllers have come on leaps and bounds in the last five years and now a modulating gas/air burner is the industry standard. This not only creates the leanest mixture to burn which minimises gas usage, but it also creates the optimum combination so that NOX and CO emissions are minimised. Gas meters are now also standard on all can making ovens, making it easier for can makers to monitor their gas usage and trial their reduction efforts.
Manufacturing
An aspect of sustainability and a consideration for the environment that goes one step further than the oven process, is the actual manufacture of them. Considering the huge amount of emissions created by the transport of goods, sourcing supply of component parts close by to the manufacturing location of the oven means the oven’s carbon footprint before it is even installed is lower.
Similarly, looking at the transport of the oven to its destination, clever designs and split points could help to reduce the amount of road freight or containers required to ship the ovens. As sustainability goals become tougher worldwide and not just for can makers, we may eventually even eliminate this issue by seeing goods transported only on electric vehicles.
So, what does the future of the thermal processing side of can making look like?
Plenty of can makers and suppliers have invested a lot into looking at thermal capture concepts. The heat generated in thermal oxidisers – can this be redirected to assist in the heating of the ovens? Or maybe the heat generated by the ovens can help to power the hot water supply to the plant? There’s a lot of ideas and trials around this subject but they all involve multiple can making businesses working together and collaborating, and that there is the key concept – collaboration.
Collaboration
This means collaboration between customer and supplier, project and plant teams, and between the can making industry and other industries.
Another example of this collaboration being key will be the consideration of the formulation of the materials applied to the cans; internal lacquers, overvarnish, mobility enhancers, inks, etc. The relationship and collaboration between these suppliers and oven suppliers will become more important as we are required to move forward and not only look at the removal of materials of concern, but also how we can reduce the temperature and cure time required for these products, and even consider how the formulation affects the content of the emissions produced.
Renewable sources
And finally, maybe the obvious, removal of fossil fuels from our processes all together.
There was a time we couldn’t imagine a car running off a battery or houses being powered by solar energy. The goals for sustainability move quickly but so does the can making industry. It is not inconceivable that the new industry standard in a few years might be ovens powered by completely renewable sources. Watch this space.
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