Biogas, a promising substitute for fossil fuels, is predominantly a mixture of methane and carbon dioxide. Both are major greenhouse gases. Methane is having more long term effect on environment while carbon dioxide is recycled by plants, hence capture and burning of biogas to consume methane as fuel is desired both from energy and environmental outlook. The presence of a large amount of carbon dioxide in biogas, however, impairs combustion in engines resulting into slow burning and higher hydrocarbon and carbon monoxide emissions.

 

Dry reformation, a conversion process of biogas to synthesis gas (syngas), a mixture of hydrogen and carbon monoxide, is a catalytic process that has potential to greatly improve biogas combustion in engines. The researchers’ focus in dry reformation, however, has been for generation of hydrogen for fuel cells and raw material generation for Fischer Tropsch process in industry. This approach aims towards maximum conversion of methane and carbon dioxide. The work presented here investigates the possibility of partial conversion of biogas to harness maximum energy and reduce emissions from I.C. Engines. The published research on dry reformation of biogas has examples of such high concentrations of methane in the syngas. Analysis of calorific values of such syngas compositions reveal their suitability as I.C. Engine fuels to operate as improved biogas fuels. (e.g. a 50:50 v/v CH~4~/CO~2~ composition biogas has calorific value of 13.33 MJ/kg the same converted to a syngas at 550^o^C to a composition of 18:42:14:26 v/v CO~2~/CH~4~/H~2~/CO has calorific value of 19.96 MJ/kg) Such compositions have moderate percentage of hydrogen to act as combustion enhancer and the carbon dioxide present helps to control NOx emissions. The major contributors of energy are methane and carbon monoxide in these cases.

 

The dry reformation reaction is an endothermic reaction, which produces hydrogen. The side reactions that happen are the reverse water gas shift reaction, which reduces hydrogen yield due to water formation and the Bouduard reaction which results in carbon deposition on the catalyst surface. The reactor conditions need to be chosen appropriately, especially the reactor temperature. Simulation of dry reformation reaction using a process simulation software (Aspen Plus) is carried out to find the extent of conversion and exit syngas composition for different biogas compositions. The endothermic heat for the reactor can be  provided by the heat of the engine exhaust – therefore, an opportunity exists to use waste heat recovery from the engine exhaust. However, there is a trade-off between the reactor temperature, syngas composition going to engine inlet and the engine exhaust heat – which is investigated in this study.

 


Dry Reforming of Biogas to Syngas: An Eco-friendly Renewable Fuel for IC Engines

Division / Sponsors: 
Aerospace, Bioengineering, Applied Mechanics, Design Engineering Division, Advanced Energy Systems, Manufacturing Engineering Division, Noise Control and Acoustics, Nondestructive Evaluation, Diagnosis, and Prognosis (NDPD), Nuclear Engineering Division, Process Industries Division, Fluids Engineering, Heat Transfer, Materials, Microelectromechanical Systems, Safety Engineering and Risk Analysis, Computers & Information in Engineering


Paper Proceedings: https://asmedigitalcollection.asme.org/IMECE/IMECE2020/volume/84478

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