Feasibility Study of Biogas Reforming To Improve Energy Efficiency and To Reduce Nitrogen Oxide Emissions

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• 作者：Sasan DabirMingyuan Cao ; Richard Prosser ; Theodore Tsotsis
• 刊名：Industrial & Engineering Chemistry Research
• 出版年：2017
• 出版时间：February 8, 2017
• 年：2017
• 卷：56
• 期：5
• 页码：1186-1200
• 全文大小：739K
• ISSN：1520-5045

文摘

The goal of this research was to determine the feasibility of employing the catalytic steam reforming of biogas to increase its energy content by converting the methane it contains into a hydrogen-rich syngas mixture and using this reformate product intermixed with raw biogas in a lean-burn gas engine in order to enhance combustion stability and to reduce NO_X emissions. The field-testing component of the project involved catalytically reforming a side stream of biomethane from a landfill gas collection system at a California landfill via a waste energy chemical recuperation process, in which waste heat from a gas engine was used to promote the reforming reaction of biogas. In the study, the total flow of raw biogas diverted to the engine remained constant. A fraction of that biogas was, however, separated and directed to the aforementioned catalytic reactor. The reformer exit stream was then dried, blended with the remaining biogas, and burned in an internal combustion engine to produce electricity. When operating on the blended biogas mixture, combustion stability was enhanced, and the engine ran smoothly at the full speed of 3600 rpm with a 60 Hz output frequency. On the other hand, when burning raw biogas without any reformate gas blended, the test engine ran poorly, sputtering and never reaching 3600 rpm. Also, when operating at various loads under fuel-lean (excess-air) conditions, NO_X emissions were significantly reduced when compared to the engine operating on propane under the same load conditions. Similar comparative testing could not be performed on raw landfill gas alone because the engine would not operate at full speed, as noted above. The research presented here has validated the technical and economic feasibility of using reforming products during biogas combustion in a lean-burn gas engine in order to reduce NO_X emissions and to enhance combustion stability. This, in our opinion, is an important contribution to the scientific/technical literature and a significant advance for the field of biogas utilization.