Hydrogen is currently being discussed as a decarbonisation option for many sectors, some of them very different, from the transport sector to process heat in industry. The publicly funded research project HyGlass is investigating how hydrogen and natural gas-hydrogen mixtures can be used to decarbonise the energy-intensive high-temperature processes in the glass industry.
Glass is a material that is indispensable in modern society and is used almost everywhere – as containers for food, drinks and vaccines, as windows in buildings and vehicles, as glass fibres in IT technology or even as insulation material. Production is energy-intensive and requires process temperatures of up to 1,650 °C to melt the glass. In further process steps, heat at different temperature levels is required to thermally homogenise the melt, shape the product and cool it down in a controlled manner.
The glass industry covers about 75 per cent of its energy needs with natural gas, which corresponds to about two per cent of German gas consumption. The production processes are highly optimised to be able to manufacture glass products with high quality and efficiency with low pollutant emissions. At the same time, however, the use of predominantly fossil energy sources also generates considerable greenhouse gas emissions.
Decarbonisation options for the glass industry
In view of the climate targets in Germany, Europe and worldwide, but also as a result of pressure from customers and society, the glass industry, like many basic industries, is also faced with the question of how it can decarbonise its energy-intensive manufacturing processes. Green electricity is an option, but for physical reasons alone, not all types of glass can be electrically melted. In addition, the size of electric melting tanks is technically limited. Therefore, the use of hydrogen is an interesting alternative.
Hydrogen is relevant for the glass industry, as well as for many other sectors of the thermo-processing industries, for another reason: The gas industry in Germany and Europe is planning to feed more hydrogen directly into the natural gas grid in the future, with up to 20 percent H2 by volume being discussed. This means that existing plants (more than 40 per cent of Germany’s natural gas consumption is currently accounted for by industry) will also come into contact with H2 concentrations. Considering the often sensitive industrial manufacturing processes with their high demands on product quality, efficiency and pollutant emissions, this can be a considerable challenge.
The combustion properties of hydrogen and natural gas differ significantly: For example, hydrogen has a considerably lower volumetric calorific value, but at the same time the resulting combustion temperatures are higher. This means that significantly higher volume flows are required to realise a given necessary energy input into the process. The flow and heat transfer in the furnace chamber will change accordingly, with possible effects on product quality and process efficiency.
At the same time, higher local temperature peaks, local overheating of components or also higher nitrogen oxide emissions (NOX) are to be expected as possible consequences. However, it is difficult to generalise how exactly these changes affect a specific industrial manufacturing process, as industrial firing processes are very heterogeneous and often highly specialised. Therefore, detailed investigations for different industrial processes are necessary to assess the impacts and to develop solutions.
For the glass industry, such investigations are the focus of the HyGlass research project. In this research project, funded by the state of North Rhine-Westphalia, the Gas- und Wärme-Institut Essen e.V. (GWI) and the Bundesverband der Glasindustrie e.V. (BV Glas) are jointly investigating the effects of higher H2 concentrations in natural gas, but also of pure hydrogen, on combustion processes in glass production. […]
… Read this article to the end in the latest H2-International
Dr. Jörg Leicher, Bledar Islami, Anne Giese, Prof. Klaus Görner – all from Gas- und Wärme-Institut Essen e. V., Essen; Dr. Johann Overath – BV Glas – Bundesverband Glasindustrie e.V.