A study on toxic organic emissions from batch combustion of styrene.
A study on toxic organic emissions from batch combustion of styrene.
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DOI：
10.1016/s0045-6535(02)00311-9
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发表时间：
2002-10
期刊：
影响因子：
8.8
通讯作者：
Charlotte Westblad;Y. Levendis;H. Richter;J. Howard;J. Carlson
中科院分区：
文献类型：
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作者：
Charlotte Westblad;Y. Levendis;H. Richter;J. Howard;J. Carlson
本文报道了苯乙烯间歇燃烧实验室规模的研究结果。有限数量的废苯乙烯单体被焚烧，然而，这种单体也是废聚苯乙烯燃烧过程中的主要热解物，废聚苯乙烯是全球生产的第二大聚合物。因此，其燃烧产生的排放物对危险废物焚烧炉和城市废物能源发电厂的运行至关重要。这项工作的重点是多环芳烃（PAHs），颗粒物，以及一氧化碳的排放。为了研究使这种排放物最小化的方法，在两级燃烧炉中进行单体的间歇燃烧。在两个阶段之间安装了额外的空气混合室。将少量的液体单体插入用作气化器/燃烧器的初级炉中。炉温在300-1000 °C的范围内，并且在大多数条件下形成扩散火焰。在与额外的空气混合后，未燃烧的气体燃料和初级反应产物在二级炉（后燃器）中继续燃烧，二级炉保持在1000或800 °C的恒定温度下。使用这种技术，最大限度地减少排放的条件进行了探索和理论研究的污染物在二次炉的命运进行。结果表明，苯乙烯，这是一种高挥发性的燃料，燃烧发生的火焰，往往是非锚定，不稳定和不稳定的形成。有机污染物，烟尘和CO的排放量比在聚苯乙烯燃烧的情况下，以前在相同的条件下研究，由于其中的额外的解聚/热解步骤更激烈。二次燃烧室的排放量超过了一次燃烧室的排放量，这与燃料转化的很大一部分发生在二次燃烧室这一事实相一致。在多环芳烃和烟尘的排放量，不完全燃烧的产物，与主炉（气化炉）的温度的明显趋势进行了观察。随着气化炉温度的降低，排放量大大减少。虽然高温下多环芳烃和烟灰的最终累积排放量占燃料质量的三分之一以上，但当主炉在300 °C热解条件下运行时，其在补燃室出口的浓度可以忽略不计。在后一种情况下，空气被添加到加力燃烧室。采用基于复杂反应网络的数值模拟方法，对主燃烧室和补燃室进行了描述。动力学分析表明，乙炔和苯是多环芳烃增长的关键物种。多环芳烃的形成在加力燃烧室，实验发现，重现模型使用活塞流假设。
Results from a laboratory-scale investigation on batch combustion of styrene are reported herein. Limited quantities of waste styrene monomer are incinerated, however this monomer is, also, the primary pyrolyzate during combustion of waste polystyrene, the second most abundant polymer produced worldwide. Thus, its combustion-generated emissions are of importance to the operation of hazardous waste incinerators and municipal waste-to-energy powerplants. This work focuses on emissions of polycyclic aromatic hydrocarbons (PAHs), particulates, as well as carbon monoxide. To investigate methods for minimizing such emissions, batch combustion of the monomer was conducted in a two-stage muffle furnace. An additional air mixing chamber was installed between the two stages. Small quantities of the liquid monomer were inserted in the primary furnace which served as a gasifier/burner. The furnace temperature was in the range of 300–1000 °C and diffusion flames were formed under most conditions. Upon mixing with additional air, combustion of unburned gaseous fuel and primary reaction products continued in the secondary furnace (afterburner), which was kept at a constant temperature of either 1000 or 800 °C. Using this technique, conditions that minimize emissions were explored and theoretical investigations on the fate of pollutants in the secondary furnace were undertaken. Results revealed that combustion of styrene, which is a highly volatile fuel, occurred with the formation of flames that were often non-anchored, unsteady and unstable. Emissions of organic pollutants, soot and CO were more intense than in the case of the polystyrene combustion, studied previously under identical conditions, due to the additional depolymerization/pyrolysis steps therein. The emissions from the secondary furnace exceeded those of the primary furnace, consistent with the fact that a very significant fraction of the fuel conversion occurred in the secondary chamber. Clear trends in the emissions of PAHs and soot, products of incomplete combustion, with the temperature of the primary furnace (gasifier) were observed. Emissions were drastically reduced with lowering the gasifier temperature. While final cumulative emissions of PAHs and soot accounted for more than one third of the mass of the fuel at high temperatures, their concentrations at the exit of the afterburner were negligible when the primary furnace was operated at 300 °C under pyrolytic conditions. In the latter case air was added to the afterburner. Numerical modeling based on a complex reaction network was used for the description of the primary furnace as well as of the afterburner. Kinetic analysis showed acetylene and benzene to be key species in the growth of PAHs. Formation of PAHs in the afterburner, found experimentally, was reproduced by the model using a plug-flow assumption.