3D printing, also known as additive manufacturing, is emerging as a trend in the process industry. With its help, the ecological impact of industrial production can be reduced. This is partly due to lower material and energy consumption, and partly due to the possibilities for individualization and optimization of design. Küppers Solutions GmbH from Gelsenkirchen has developed the iRecu, the first series burner produced by 3D printing. For this, it won the 2022 Innovation Award for Climate and Environment in the category "Product and service innovations for climate protection."
More efficient design
By using new types of heat exchanger structures, the efficiency of the recuperative burner - measured in terms of relative air preheating - was increased from the market-standard 60% to as much as 90%. The structures would not be feasible without 3D printing. In other words, the additive manufacturing method is what makes the burner's structure possible in the first place, and thus its increased performance.
The devices are geometrically based on the so-called TPMS (triply periodic minimal surfaces) structure. The triply periodic minimal surface optimizes flow control, resulting in lower pressure losses and improved heat transfer within the recuperator. Due to its complexity, the structure can only be modeled digitally.
An example of the iRecus' efficiency: at a temperature of 1,000 °C, conventional recuperators today achieve relative air preheats of 60 %, which corresponds to a combustion air temperature of 600 °C. In the same process, the iRecu achieves a combustion air temperature of 900 °C. This means an additional energy saving of 10 %.
Possible use of hydrogen
Another advantage of the iRecu is its specially developed dual-fuel mixing unit, which allows it to run in hybrid mode on 100% hydrogen or 100% natural gas. This does not require any cost-intensive conversion of the plant.
However, the combustion of hydrogen in recuperative burners poses a particular challenge: hydrogen generates nitrogen oxide emissions. This is because the preheating of the combustion air and the higher reactivity of hydrogen mean that the overall combustion reaction takes place at a significantly higher temperature level than with natural gas. This promotes thermal nitrogen oxide formation
The iRecu counteracts this problem with its multi-channel mixing unit: Here, the combustion zones are designed so that the respective fuel gas can burn optimally. In this way, the unit accommodates the different combustion properties of natural gas and hydrogen, while nitrogen oxide emissions remain minimal.
Major CO2 savings
It was probably these advantages that convinced the jury headed by Prof. Ottmar Edenhofer when awarding the German Innovation Prize for Climate and Environment 2022. Among 150 applicants, Küppers Solution was declared one of the 21 nominated finalists.
"With the iRecu, Kueppers Solutions GmbH offers the world's first 3D-printed series burner with optimized heat recovery. Even before the availability of green fuels, this can save 2.2 million tons of CO2 in industrial thermoprocessing plants, and in the next step, with green hydrogen via the dual-channel gas mixing unit, a further 13 million tons per year," the jury explained.
