Slagging characteristics during residential combustion of biomass pellets
Slagging characteristics during residential combustion of biomass pellets
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DOI：
10.1021/ef800087x
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发表时间：
2008-09-01
期刊：
影响因子：
5.3
通讯作者：
Burvalll, Jan
中科院分区：
文献类型：
--
作者：
Gilbe, Carl;Ohman, Marcus;Burvalll, Jan
欧洲对木屑和刨花的有限供应，以及对生物质颗粒日益增长的需求，正在推动市场转向其他更有问题的原材料，总燃料灰含量和灰分形成元素的组成以及它们的结渣倾向存在更大的差异。因此，本工作的主要目的是确定燃料灰组成对残渣行为的影响。使用了12种不同的生物质颗粒：芦苇金丝雀草(两个不同的样品)、大麻(两个不同的样品)、小麦秸秆。柳树、伐木残留物(两个不同的样本)、船尾木材(锯末)以及云杉、松树和桦树皮。不同性质的球团在一台安装在参考锅炉上的商业欠给球团燃烧器(20kW)上进行了燃烧。锅炉尾气中O-2、CO、CO2、HCl、SO2和总颗粒物质量浓度的连续测量直接在锅炉后完成。用X射线衍射仪(X射线衍射仪)和扫描电子显微镜结合能谱分析(SEM/EDS)对收集到的炉渣、锅炉底渣和收集到的颗粒物进行了表征。对于富含硅(固有的或被砂污染的)和低碱土金属含量的生物质燃料颗粒，钾的主要部分与富硅的灰渣发生反应。形成粘性的碱-硅酸盐颗粒，这些颗粒没有携带在燃烧器前面，从而引起/开始结渣。富硅燃料，即燃料的灰分特性以硅酸盐-碱化学为主，因此普遍表现出较高的结渣倾向。秸秆燃料通常具有这种灰分成分，但也存在例外情况(例如，本工作中使用的一种大麻燃料)。因此，固有硅含量相对较低的木质燃料表现出较低或相对中等的结渣倾向。然而，砂料对这些燃料的污染可能会大大增强结渣倾向。
Limited availability of sawdust and planer shavings and an increasing demand for biomass pellets in Europe are pushing the market toward other, more problematic raw materials with broader variation in total fuel ash content and composition of the ash forming elements as well as in their slagging tendencies. The main objective in the present work was therefore to determine the influence of fuel-ash composition on residual ash and slag behavior. Twelve different biomass pellets were used: reed canary grass (two different samples), hemp (two different samples), wheat straw. salix, logging residues (two different samples), stern wood (sawdust) as well as spruce, pine, and birch bark. The different pellet qualities were combusted in a commercial under fed pellet burner (20 kW) installed in a reference boiler. Continuous measurements of O-2, CO, CO2, HCl, SO2, and total particle matter mass concentrations were determined in the exhaust gas directly after the boiler. The collected slag deposits, the corresponding deposited bottom ash in the boiler and the collected particle matter were Characterized with X-ray diffraction (XRD) and scanning electron microscopy combined with energy dispersive X-ray analysis (SEM/EDS). For biomass fuel pellets rich in silicon (either inherent or contaminated with sand) and low content of alkaline earth metals the main part of the potassium reacted with the silicon rich ash-residual. forming sticky alkali-silicate particles, which were not entrained front the burner and thereby giving rise to/initiating slag formation. Silicon rich fuels, i.e. fuels were the ash characteristics were dominated by silicate-alkali chemistry, therefore generally showed relatively high slagging tendencies. Straw fuels have typically this ash composition but exceptions to these general trends exists (e.g., one of the hemp fuels used in this work). Wood derived fuels with a relatively low inherent silicon content therefore showed low or relatively moderate slagging tendencies. However, contamination of sand material to these fuels may greatly enhance the slagging tendencies.