The European Commission's objective to respond to the ongoing climate change is clear: decarbonise. The July 2021 “Fit for 55” plan aims to cut CO2 emissions by 55% by 2030 and achieve climate neutrality by 2050 through increased use of renewable sources and improved energy efficiency.

Industry is one of the sectors primarily involved in this energy reform aimed at reducing climate-changing emissions and is strongly called upon to act. The challenge is to find a balance that is technologically and economically sustainable between the technical solutions identified in the laboratory and the existing infrastructure.

In recent years, hydrogen (H2) is increasingly establishing itself as a viable alternative for the energy transition and has in fact been included among the strategies of the European Commission. As pointed out in its communication COM (2020) 301 of 08.07.2020 “A hydrogen strategy for a climate-neutral Europe”, it shows how this chemical element is the solution available to decarbonise and reduce CO2 emissions. The type of hydrogen defined as “green”, obtained from renewable energy processes, is in effect the ideal candidate to fulfil this role.

Riello, attentive to innovations in the world of residential and industrial combustion, has been studying this fuel for over 10 years, both in its pure form and in a mixture with methane. The first applications of hydrogen date back to the 1960s with town gas, a gas mixture with more than 50 per cent hydrogen that was mainly distributed in the centres of a few large cities, such as London and Singapore.

This technology has been studied by the Riello Research and Combustion Centre in Angiari, VR and improved to use hydrogen, either pure or in a mixture, in the latest ranges of burners.

The theoretical studies were confirmed by the first tests carried out in the Research Centre in 2010. Hydrogen has very different physical and chemical characteristics from methane. It has a lower calorific value and density but a significantly higher flame temperature (reaching up to 2000°C!). Modifications to be made to a combustion head designed for hydrogen must therefore include a higher fuel flow rate and materials capable of withstanding higher temperatures to ensure robustness and power equal to a corresponding natural gas burner.

Pure green hydrogen as an energy carrier allows CO and CO2 emissions to be reduced to zero by releasing mainly water vapour as a product of combustion.

European legislation has not yet been comprehensive on the regulation of hydrogen fuel, but Riello in 2022 had already designed, tested and certified according to DIN EN 676:2021-09 and DVGW CERT ZP 3502 two burner ranges up to 1 MW suitable for operating with up to 20% hydrogen for the European market and tested forced draught burners capable of operating with up to 100 per cent hydrogen.

Riello aimed for European certification, with a mixture of up to 20 per cent, for two ranges covering both forced draught and premixed burners. Specifically, the RS and RX series burners represent Riello's product range for hydrogen combustion. Through fluid-dynamic study and careful design of the combustion head, they help to comply with the most stringent emission limits in terms of both nitrogen oxides and carbon monoxide.

These burners offer high performance over a wide power output range and are equipped with the latest technology to achieve excellent power control and combustion quality in the various work stages.

Derived from standard products, they share the same reliability and robustness while incorporating the necessary solutions and upgrades to make them an ideal proposition for hydrogen combustion; they also comply with the European EMC, Low Voltage and Machinery Directives.

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