A pilot-scale demonstration of oxy-combustion with flue gas recirculation in a pulverized coal-fired boiler

摘要

Over the past years, environmental concerns for various combustion-generated emissions have grown rapidly: acid rain precursors (NO_x, SO_x) were initially targeted, followed by mercury emissions and more recently by carbon dioxide emissions, brought into focus as a greenhouse gas. As a consequence, governments have strengthened regulations, imposing SO_2, NO_x and mercury limits in a growing number of areas, and encouraging CO_2 reductions. Since the power generation industry and more specifically coal-fired power plants are responsible for a large amount of these pollutants, new combustion processes have to be developed in order to provide coal-fired power plants with a solution to comply with existing and future regulations. In this context, a new combustion process based on oxygen-enriched flue gas recirculation for pulverized coal-fired power plants is being proposed to provide an easy-to-implement option for multi-pollutant control, including CO_2 capture. To date, theoretical analyses and lab-scale experiments have been reported, with no large-scale implementations. This paper presents the experimental results obtained from a pilot-scale demonstration of the oxygen-enriched flue gas recirculation combustion process on a pulverized coal-boiler. This demonstration was performed on a 1.5MW boiler simulator, using Illinois coal. Measurements from the pilot boiler demonstrate the technical feasibility of the process for larger scale-boilers, highlighting the favorable impact on NO_x, SO_x and mercury emissions, while concentrating the carbon dioxide in the flue gas. The results also show a significant reduction in fly ash unburned combustible content resulting in improvement in boiler efficiency due to the use of oxygen. The paper concludes that oxygen enrichment represents a technically sound technology for multi-pollutant control. A consequent paper presented during this conference discusses the economical aspects related to the technology, indicating that oxygen enrichment is an attractive solution for ultra-clean coal-based power generation.