Biogas as a co-firing fuel in thermal processing industries: implementation in a glass melting furnace

Abstract In many energy-intensive manufacturing processes, natural gas is the dominant fuel to provide process heat. There is increasing pressure, however, to reduce both fuel costs and carbon dioxide (CO2) emissions. One possible approach in this regard is the use of mostly untreated biogas as a fuel in a co-firing approach. While the use of such biogas can decrease both natural gas consumption and overall CO2 emissions (biogas is considered to be a CO2-neutral fuel), there is concern how this change of fuel will impact on product quality, combustion behavior and the refractory material. Trace contaminations in the biogas are one aspect in this context which might have a negative impact on product quality or the durability of the refractory of industrial furnaces. In a previous research project, GWI and its partners investigated the principal applicability of biogas combustion, using the glass melting process as an example. It was found that there was no negative impact on combustion behavior, product quality or refractory properties if the process is adapted to the different characteristics of the fuel, for example by adjusting melting times. Another result was that for existing plants, it is more sensible to use a co-firing approach, partly substituting natural gas by biogas, instead of switching fuels completely. Consequently, the co-firing of roughly de-sulphurized biogas in an industrial glass melting furnace in Germany is currently being investigated as part of a follow-up project. Aspects such as pollutant formation, energy efficiency and product quality when using untreated biogas on an industrial scale will be examined.