Pollutant formation during oxy-combustion of coal

煤富氧燃烧过程中污染物的形成

• 批准号: 1236761
• 负责人: BIHTER PADAK
• 金额: $ 27.2万
• 依托单位: University South Carolina Research Foundation
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2012
• 资助国家: 美国
• 起止时间: 2012-09-01 至 2015-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1236761&HistoricalAwards=false
• 关键词: Pollutant; formation; during; oxy; combustion

Carbon dioxide emissions from combustion of fossil fuels is of great concern for global warming. A technology being considered for carbon capture and sequestration in power plants is oxy-coal combustion. Thus, the operational and environmental impacts of oxy-coal combustion need to be evaluated. Sulfur dioxide emissions can also be reduced with oxy-firing compared to air combustion due to high concentrations of sulfur trioxide in the flue gas resulting in sulfur retention on fly ash and ash deposits in the furnace. Higher sulfur retention on the ash particles reduces the sulfur dioxide emission rates, on the other hand it creates problems utilizing the fly ash for cement and concrete production. Further research regarding the sulfur dioxide emissions under oxy-firing conditions needs to be performed, specifically to investigate the fly ash retention. In comparison to the emissions of nitrogen and sulfur oxides, the subject of trace metal emissions in oxy-fuel combustion has not received much attention in the literature and little information has been reported on the mercury transformations under oxy-fired conditions. One area of concern is that the pollutants such as mercury and sulfur trioxide cause corrosion in carbon dioxide compressors and recirculation lines. The characteristics of oxy-combustion and air-combustion are fairly different and this results in changes in the behavior of pollutants in the flue gas, thus the emissions. As research in this area is beginning to grow, the fundamental understanding of pollutant formation remains to be elucidated and before developing removal technologies, one needs to understand the speciation and behavior of these pollutants under oxy-fired conditions. The objective of this project is to investigate the differences in pollutant behavior under air- and oxy-fired conditions. This research is unique in the fact that it will be the first comprehensive investigation of pollutant formation during oxy-fuel combustion at a fundamental level combining bench-scale experiments, kinetic modeling and molecular modeling. Two major milestones that will be achieved by the end of this project are the following: 1) Gas phase chemistry of sulfur oxides and trace metals will be elucidated by both bench-scale experiments and kinetic modeling and effects of other flue gas constituents and the recycling will be determined 2) Heterogeneous chemistry of sulfur oxides and trace metals on fly ash will be investigated by bench-scale experiments and molecular modeling and the mechanism of sulfur retention on fly ash will be identified.This research will provide useful information for the oxy-fired power plants regarding the risk of corrosion associated with the pollutants in the flue gas as well as the extent of sulfur retention on fly ash that could prevent them selling the fly ash to concrete producers. Besides the practical knowledge, it will also provide a fundamental understanding of the pollutant chemistry that is taking place in the flue gas and on the fly ash surface. Experimental data that will be produced from this project will be made available in the literature and could be used to validate the existing models in the literature. Additionally, the graduate and undergraduate students working on this project will gain an in-depth knowledge of combustion chemistry as well as excellent experimental and modeling skills.

化石燃料燃烧产生的二氧化碳排放是全球变暖的主要原因。发电厂正在考虑的碳捕获和封存技术是氧煤燃烧。因此，需要评估富氧煤燃烧的操作和环境影响。与空气燃烧相比，氧气燃烧也可以减少二氧化硫排放，因为烟道气中的三氧化硫浓度高，导致硫保留在飞灰上和炉中的灰沉积物上。在灰颗粒上较高的硫保留降低了二氧化硫排放率，另一方面，它产生了利用粉煤灰生产水泥和混凝土的问题。需要对富氧燃烧条件下的二氧化硫排放量进行进一步研究，特别是调查飞灰的保留情况。与氮氧化物和硫氧化物的排放相比，富氧燃烧中痕量金属排放的主题在文献中没有得到太多关注，关于富氧燃烧条件下汞转化的信息报道很少。一个令人担忧的领域是，汞和三氧化硫等污染物会导致二氧化碳压缩机和再循环管线的腐蚀。富氧燃烧和空气燃烧的特征是相当不同的，这导致烟气中污染物的行为发生变化，从而导致排放物的变化。随着这一领域的研究开始发展，对污染物形成的基本认识仍有待阐明，在开发去除技术之前，人们需要了解这些污染物在氧燃烧条件下的形态和行为。本项目的目的是调查空气和氧气燃烧条件下污染物行为的差异。这项研究的独特之处在于，它将是第一次在基础水平上结合实验室规模实验，动力学建模和分子建模对氧燃料燃烧过程中污染物形成的全面调查。到本项目结束时将实现的两个主要里程碑如下：1）硫氧化物和痕量金属的气相化学将通过实验室规模的实验和动力学建模来阐明，并且将确定其他烟气成分的影响和再循环2）硫氧化物和痕量金属在飞灰上的非均相化学将通过实验室规模的实验和动力学建模来研究。本研究将通过室内模拟实验和分子模拟，探讨粉煤灰固硫的机理，为粉煤灰的氧化脱硫提供理论依据。火力发电厂关于与烟气中污染物相关的腐蚀风险以及飞灰上的硫保留程度，这可能会阻止他们出售飞灰水泥生产商。除了实践知识，它还将提供对烟气和飞灰表面发生的污染物化学的基本了解。该项目将产生的实验数据将在文献中提供，并可用于验证文献中的现有模型。此外，从事该项目的研究生和本科生将获得燃烧化学的深入知识以及出色的实验和建模技能。