Combustion of Hydrogen and Natural Gas at Elevated Air Temperature Using 3D Printed Burner

Abstract

Abstract Hydrogen is a clean-burning fuel that produces only water vapor when combusted, making it a highly attractive option for reducing greenhouse gas emissions and combating climate change. Hydrogen can be produced from a variety of domestic sources with potentially near-zero greenhouse gas emissions. However, combustion associated with hydrogen for industrial heating applications poses some serious challenges in terms of flame stability and high flashback propensity due to its highly reactive nature. At the same time the burner hardware is also expected to be fuel flexible (with varying LHV), i.e., to be able to operate with different blends of LPG/NG and H2. This demands a bit complex geometry to mix the fuel and air in an efficient way (fuel nozzle sizing) and at the same time to mitigate the flash back risk and introduce complex cooling schemes. Towards this, advanced additive manufacturing techniques (3D printing) open the doors to manufacture highly complex systems and facilitate the scaling of complex systems. 3D printing is an additive process, where material is only used where it is needed. Thus, it leads to reduced material wastage and more sustainable manufacturing practices. This experimental study aims to determine the operating margins of a fuel flexible 3D printed burner, that is designed to burn different fuel blends up to 100% hydrogen. Following thorough Computational Fluid Dynamics (CFD) analyses, the burner was designed for and produced through additive manufacturing technology (3D printing). As a first validation and demonstration, tests were carried at atmospheric pressure test conditions, using natural gas (NG) and hydrogen (H2) up to 250 (kW) of thermal power and air preheating up to 500°C. The results demonstrated the burner capabilities in terms of low emissions (below 3 ppm) low pressure drop (below 2.5%) in a broad operating window (flame temperatures up to 1850K), relevant for gas turbine and other industrial heating system applications. The first tests with the 3D printed burner, with integrated fuel injection and cooling concept system showed encouraging results in terms of flash back resistance and at the same time meeting low pressure drop system compared to the conventional swirl stabilized flames.