The ceramics industry plays a substantial role in the EU economy, driven by 17 000 companies, employing over 240 000 people, and producing nearly EUR 30 billion in revenue. However, the industry is also a big user of energy. In fact, producing just one tonne of ceramic tiles requires 1.67 MWh of energy.
Most of this energy (55%) is used during the firing process, where clay and glazes are brought to a very high temperature. This heating is typically done with natural gas which, as a fossil fuel, means the process produces a substantial amount of greenhouse gases. As these gases are heavily regulated, it comes as no surprise that the ceramics industry has the most installations in the EU’s Emission Trading System (ETS).
The key to reducing this carbon footprint is to create a more efficient kiln – which is exactly what the EU-funded DREAM project has done.
“To shift the evolution of kilns towards a more sustainable paradigm, the DREAM project designed, developed, and demonstrated a radically improved architecture for ceramic industrial furnaces,” says Gabriele Frignani, Head of Applied Research at Sacmi, an Italy-based multinational ceramics corporation, and DREAM project coordinator. “The result is a new, state-of-the-art kiln defined by optimised energy consumption, reduced emissions, and lower operating costs.”
Testing through technology
Traditionally, the industry has lowered polluting emissions by installing a bag filter in the kiln’s exhaust chimney. Although this does keep emission levels just under the legal threshold, it doesn’t prevent pollutants such as nitrogen and sulphur oxides from escaping into the air. This shortcoming, along with the fact that acceptable emission levels are set to be lowered, meant a better solution was needed.
To solve this problem, the DREAM project turned to technology. The team developed and tested a software-based simulation model capable of analysing all the thermal processes happening in a kiln, including preheating, firing, and cooling. Using this system, it was not only possible to quickly identify areas of inefficiency, but also to digitally test various modifications and solutions.
“These simulations save time and costs during the development phase as they quickly highlight which roads show promise and which ones probably lead to a dead end,” explains Frignani. “This approach is particularly valuable in this type of research project where, due to time and budget constraints, a precise roadmap is required.”
For example, through the simulation exercises, it could be anticipated that replacing large turbines with micro-turbines along the production line would produce a customised level of electricity for a given machine. Not only does this eliminate the use (and waste) of excess energy, it also reduces the time needed to restore the thermal conditions after electrical blackouts and helps reduce a kiln’s carbon footprint.
A better kind of kiln
Despite the advantages, using simulation tools does have its limits. For instance, they cannot predict whether a variation in the firing process will negatively affect the material itself. To fill this gap, the project conducted industrial-level testing, applying its virtual model to a real production kiln.
“These tests conclusively showed that with our software, ceramic companies can get real-time monitoring and the ability to intervene directly as needed to improve the efficiency of an individual phase,” explains Frignani. “The net result is a kiln capable of producing better while consuming and polluting less.”
Frignani notes that, due to the time and investment required, this type of research and development has become nearly impossible for individual companies to finance – particularly within a competitive sector such as ceramics. “Research projects like DREAM will play an increasingly important role in developing the technology and know-how that will enable the eco-friendly solutions of tomorrow,” he concludes.