Pulverized bituminous coal was burned in a 10W externally heated entrained flow furnace under air-combustion and three oxy-combustion inlet oxygen conditions (28, 32, and 36%). Experiments were designed to produce flames with practically relevant stoichiometric ratios (SR=1.2-1.4) and constant residence times (2.3s). Size-classified fly ash samples were collected, and measurements focused on the soot, elemental carbon (EC), and organic carbon (OC) composition of the total and ultrafine (<0.6μm) fly ash. Results indicate that although the total fly ash carbon, as measured by loss on ignition, was always acceptably low (<2%) with all three oxycombustion conditions lower than air-combustion, the ultrafine fly ash for both air-fired and oxy-fired combustion conditions consists primarily of carbonaceous material (50-95%). Carbonaceous components on particles <0.6μm measured by a thermal optical method showed that large fractions (52-93%) consisted of OC rather than EC, as expected. This observation was supported by thermogravimetric analysis indicating that for the air, 28% oxy, and 32% oxy conditions, 14-71% of this material may be OC volatilizing between 100 and 550°C with the remaining 29-86% being EC/soot. However, for the 36% oxy condition, OC may comprise over 90% of the ultrafine carbon with a much smaller EC/soot contribution. These data were interpreted by considering the effects of oxy-combustion on flame attachment, ignition delay, and soot oxidation of a bituminous coal, and the effects of these processes on OC and EC emissions. Flame aerodynamics and inlet oxidant composition may influence emissions of organic hazardous air pollutants (HAPs) from a bituminous coal. During oxy-coal combustion, judicious control of inlet oxygen concentration and placement may be used to minimize organic HAP and soot emissions.

中文翻译：

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空气燃烧和全氧燃烧产生的烟灰、有机物和超细灰分。

烟煤粉在10W外热式气流床炉中在空气燃烧和三种富氧燃烧入口氧气条件（28%、32%和36%）下燃烧。实验设计为产生具有实际相关化学计量比（SR=1.2-1.4）和恒定停留时间（2.3s）的火焰。收集按尺寸分类的飞灰样品，测量重点是总飞灰和超细飞灰（<0.6μm）的烟灰、元素碳（EC）和有机碳（OC）组成。结果表明，尽管所有三种富氧燃烧条件下的飞灰总碳（通过烧失量测量）始终处于可接受的低水平（<2%），但空气燃烧和富氧燃烧的超细飞灰燃烧条件主要由碳质材料（50-95%）组成。通过热光学方法测量的 <0.6μm 颗粒上的碳质成分表明，大部分 (52-93%) 由 OC 而不是 EC 组成，正如预期的那样。这一观察结果得到了热重分析的支持，表明对于空气、28% 氧气和 32% 氧气条件，该材料的 14-71% 可能是 OC，在 100 至 550°C 之间挥发，其余 29-86% 是 EC/煤烟。然而，对于 36% 的氧气条件，OC 可能包含超过 90% 的超细碳，而 EC/烟灰的贡献要小得多。通过考虑富氧燃烧对烟煤的火焰附着、点火延迟和烟灰氧化的影响以及这些过程对 OC 和 EC 排放的影响来解释这些数据。火焰空气动力学和入口氧化剂成分可能会影响烟煤中有机有害空气污染物 (HAP) 的排放。在富氧煤燃烧过程中，可以明智地控制入口氧气浓度和位置，以最大限度地减少有机有害空气污染物和烟灰排放。