Combustion characteristics of pulverized torrefied biomass for use in co-firing boilers

为了满足快速增长的全球人口的能源需求，并尽量减少对环境的负面影响，需要替代能源。美国有很大的可再生生物质生产能力，其利用可以减少碳排放总量。用生物质部分替代煤炭，可以成为一种可行的选择，用于产生大多数替代能源（风能、太阳能、潮汐能）由于其间歇性而无法提供的基荷电力。然而，生物质是潮湿的，可生物降解的和纤维的。因此，运输、储存和研磨以用于锅炉是昂贵的。这项研究将解决烘焙生物质的燃烧问题，生物质经过烘焙过程（类似于咖啡烘焙）以去除水分，氯和硫。然而，随着研磨成本随着目标研磨尺寸的减小而急剧增加，这项工作的目的是确定适当的最大焙烧生物质颗粒尺寸范围，以在现有锅炉中进行有效燃烧。这些知识是需要的焙烧生物质成为一个标准化的产品燃烧在几乎未经改造的燃煤电厂。在这项研究的过程中，学生将接受能源领域的教育，并将在收集生物能源以帮助实现可持续发展的环境方面开展多项国际合作。这项研究将产生与电站锅炉中烘焙生物质有效燃烧相关的新知识。这项调查将确定方法，以评估适当大小的各种焙烧生物质材料（包括几个典型的木本和草本生物质类型）与煤粉共燃，同时保持高燃烧效率和高辐射通量在现有的锅炉。颗粒燃尽时间，挥发性物质的火焰和残留的焦炭，在火焰中的烟灰的体积分数，颗粒与颗粒的相互作用，碳燃尽的温度相关的数据是需要预测反应速率，热通量，结渣和污垢沉积倾向的锅炉。拟议的基础研究将评估这些燃烧参数的粉碎焙烧的生物质在颗粒水平上，通过监测整个燃烧历史的单个颗粒的高温和电影。这些数据将与本实验室先前收集的所有等级煤颗粒的类似数据进行比较。随后，燃烧效率和颗粒间的相互作用将通过纯燃料和混合燃料的燃烧流进行评估，并将监测排放。该奖项反映了NSF的法定使命，并被认为值得通过使用基金会的知识价值和更广泛的影响审查标准进行评估。

To satisfy energy needs of the fast-growing global population and minimize the negative impact on the environment, alternative energy sources are needed. The U.S. has a large capacity for renewable biomass production, the utilization of which can reduce the total carbon emissions. Partial substitution of coal with biomass can be a viable option for generating the baseload power that most alternative sources (wind, solar, tidal) cannot supply due to their intermittent nature. However, biomass is moist, biodegradable and fibrous. Thus, it is costly to transport, store and grind for use in the boilers. This research will address the combustion of torrefied biomass, which has been subjected to the process of torrefaction (akin to coffee roasting) to remove moisture, chlorine and sulfur. However, as grinding costs drastically increase with decreasing targeted grind size, this work aims to identify appropriate maximum torrefied biomass particle size ranges for effective combustion in existing boilers. Such knowledge is needed for torrefied biomass to become a standardized product for burning in virtually unmodified coal-fired plants. During the course of this research, students will be educated in the energy field and several international collaborations will be advanced on the subject of harvesting bioenergy to help achieve a sustainable environment.This research will generate new knowledge pertinent to effective combustion of torrefied biomass in utility boilers. This investigation will identify methods for assessing the proper size of various kinds of torrefied biomass materials (including several typical woody and herbaceous biomass types) for co-firing with pulverized coal, while maintaining high combustion efficiencies and high radiative fluxes in existing boilers. Data pertinent to particle burnout times, temperatures of both volatile matter flames and residual chars, in-flame soot volume fractions, particle-to-particle interactions, carbon burnout are needed to predict reaction rates, heat fluxes, and slagging and fouling deposition tendencies in boilers. The proposed fundamental research will assess these combustion parameters of pulverized torrefied biomass at the particle level, by monitoring entire combustion histories of single particles pyrometrically and cinematographically. These will be compared to analogous data for coal particles of all ranks, previously collected in this laboratory. Subsequently, combustion effectiveness and particle-to-particle interactions will be assessed by burning streams of neat and blended fuels and emissions will be monitored.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.