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首页> 外文会议>International Technical Conference on Coal Utilization amp; Fuel Systems vol.1; 20060521-26; Clearwater,FL(US) >Coal Particle Ignition and Devolatilization during Oxy-Coal Combustion
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Coal Particle Ignition and Devolatilization during Oxy-Coal Combustion

机译：氧煤燃烧过程中煤粉的着火与脱挥发分

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摘要

Oxy-coal combustion technologies are being actively investigated to achieve emission reductions and reductions in flue gas cleanup costs, as well as for coal-bed methane and enhanced oil recovery applications. To fully understand the results of pilot-scale tests and to accurately predict scale-up performance through CFD modeling, fundamental data are needed concerning coal and coal char combustion properties under these unconventional conditions. In the work reported here, the effect of enhanced oxygen levels and a CO_2 bath gas (reflecting O_2-recycle coal combustion) are independently analyzed for their influence on single-particle pulverized coal ignition and devolatilization. The experiments were conducted in a combustion-driven laminar entrained flow reactor with very high particle heating rates (10~5 K/s) reflecting typical coal burner operation. Both a high-volatile eastern U.S. bituminous coal and a Powder River Basin subbituminous coal were analyzed. The measurements show that the presence of CO_2 in the bath gas retards the onset of ignition and increases the duration of devolatilization, once initiated. For a given diluent gas (CO_2 or N_2), a higher oxygen concentration yields shorter ignition delay and devolatilization times. Particle ignition and devolatilization times in a mixture of 30% O_2 in CO_2 are very similar to those in air. The effect of CO_2 on coal particle ignition may be explained by its higher molar specific heat and the effect of O_2 is explained by its effect on the local mixture reactivity. The effect of CO_2 on the duration of devolatilization results from the somewhat lower diffusivity of volatiles in CO_2 mixtures.
机译：富氧煤燃烧技术正在积极研究中，以实现排放量的减少和烟道气净化成本的降低，以及用于煤层气和提高采油率的应用。为了充分了解中试规模的测试结果并通过CFD建模准确预测按比例放大的性能，需要在这些非常规条件下有关煤和煤焦燃烧特性的基础数据。在此处报告的工作中，独立分析了氧气含量增加和CO_2浴气（反映O_2循环煤燃烧）对单颗粒煤粉着火和脱挥发分的影响。实验是在燃烧驱动的层流气流床中进行的，具有很高的颗粒加热速率（10〜5 K / s），反映了典型的煤燃烧器操作。分析了美国东部的高挥发分烟煤和粉河盆地的次烟煤。测量表明，一旦启动，浴液中CO_2的存在会延迟着火的发生并增加脱挥发分的持续时间。对于给定的稀释气体（CO_2或N_2），较高的氧气浓度会产生较短的着火延迟和脱挥发分时间。在CO_2中30％O_2的混合物中，粒子着火和脱挥发分的时间与空气中的非常相似。 CO_2对煤粉着火的影响可以通过其较高的摩尔比热来解释，而O_2的影响可以通过其对局部混合物反应性的影响来解释。 CO_2对脱挥发分持续时间的影响是由于CO_2混合物中挥发物的扩散性较低。

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