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，并将对环境的负面影响降至最低，需要替代能源。美国有很大的可再生生物质生产能力，利用可再生生物质可以减少碳排放总量。生物质能部分替代煤炭，是一种可行的基本负荷发电方式，而大多数替代能源(风能、太阳能、潮汐能)由于其间歇性，无法提供这些电力。然而，生物质是潮湿的、可生物降解的和纤维状的。因此，运输、储存和研磨用于锅炉的成本很高。这项研究将研究经过烘烤(类似于咖啡烘焙)以去除水分、氯和硫的精炼生物质的燃烧。然而，由于粉碎成本随着目标粉碎粒度的减小而急剧增加，这项工作的目的是确定在现有锅炉中有效燃烧的合适的最大托瑞特生物质粒度范围。这些知识是托瑞德生物质成为标准化产品，在几乎没有经过改造的燃煤电厂中进行燃烧所必需的。在这项研究的过程中，学生们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环境的主题上推进几项国际合作。这项研究将产生与在电站锅炉中有效燃烧托瑞德生物质有关的新知识。这项研究将确定在现有锅炉中保持高燃烧效率和高辐射通量的同时，评估各种精制生物质材料(包括几种典型的木质和草本生物质类型)与煤粉混烧的合适尺寸的方法。需要与颗粒燃尽时间、挥发分火焰和残炭的温度、火焰中的碳烟体积分数、颗粒对颗粒的相互作用、碳燃尽有关的数据来预测锅炉中的反应速率、热通量以及结渣和结垢倾向。拟议的基础研究将通过高温和摄影监测单个颗粒的整个燃烧历史，在颗粒水平上评估超细生物质的这些燃烧参数。这些数据将与本实验室以前收集的所有煤级颗粒的类似数据进行比较。随后，将通过燃烧纯燃料和混合燃料来评估燃烧效率和颗粒到颗粒的相互作用，并将监测排放。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

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.