Inhibition of lignite ash slagging and fouling upon the use of a silica-based additive in an industrial pulverised coal-fired boiler: Part 3 – Partitioning of trace elements
Inhibition of lignite ash slagging and fouling upon the use of a silica-based additive in an industrial pulverised coal-fired boiler: Part 3 – Partitioning of trace elements
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DOI：
10.1016/j.fuel.2014.09.015
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发表时间：
2015
期刊：
影响因子：
7.4
通讯作者：
Fiona Low;A. D. Girolamo;Xiaojiang Wu;Baiqian Dai;Lian Zhang
中科院分区：
文献类型：
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作者：
Fiona Low;A. D. Girolamo;Xiaojiang Wu;Baiqian Dai;Lian Zhang
本文对某工业褐煤锅炉不同炉段灰渣和烟气中12种微量元素（As、Ba、Be、Co、Cr、Cu、Mn、Ni、Pb、Sr、V和Zn）的排放、分配和特征进行了全面研究。除了原料褐煤的燃烧之外，还进行了混合了4wt %的硅基添加剂的煤的燃烧，以抑制灰结渣和结垢，以研究二氧化硅对上述微量元素行为的影响。在燃烧区（即煤焰区）的相对富集（RE）方面，所研究的褐煤中个别微量元素的汽化趋势与国际能源署（IEA）煤炭研究中心报告的常规分类有显著偏差。不考虑添加剂的使用，经典的II族元素中的Zn和通常作为I族和II族中间产物的Ba、Co、Cu和Ni在褐煤测试中被提升为III族元素。在整个锅炉的微量元素分配趋势上，包括As， Cr， Mn和V的组，在使用硅基添加剂后，在所有锅炉位置的富集都显着减少。该集团;Ba、Co、Ni和Zn的浓度与使用硅基添加剂无关。其余微量元素，特别是Be、Cu和Pb，在不同RE段之间，以及原煤和掺硅助剂煤的两种燃烧情况之间都有交织的趋势。在所研究的所有微量元素中，添加硅基添加剂对Sr的影响相反，其RE因子自始至终都在增加。对原煤单独进行统计分析，发现As主要与Ca、Si相关；发现Ba、Cr、Cu与Fe相关；和V，与Ca相关。硅基添加剂的加入为微量元素的非均相转化提供了竞争反应，从而改变了它们的关系。灰渣中Cr的x射线吸收近边结构光谱（XANES）分析进一步支持了这一观点。研究发现，高危害Cr（VI）的含量在0%至14%之间，硅基添加剂的加入导致Cr（VI）的捕获/固定总体减少，部分原因是硅基添加剂本身产生了显著的Cr污染效应。
In this paper, the emission, partitioning, and characterisation of twelve trace elements (As, Ba, Be, Co, Cr, Cu, Mn, Ni, Pb, Sr, V, and Zn) in the ash deposits from different sections of an industrial pulverised lignite-fired boiler and in the flue gas have been thoroughly examined. Apart from the combustion of the raw lignite, the combustion of coal mixed with 4 wt% of a silica-based additive for the inhibition of ash slagging and fouling has also been conducted to investigate the influence of silica on the behaviour of the aforementioned trace elements. In terms of relative enrichment (RE) in the combustion zone (i.e.coal flame zone), the vaporisation tendencies of the individual trace elements in the lignite studied showed a remarkable deviation from the conventional classification reported by the International Energy Agency (IEA) Coal Research Centre. Irrespective of the use of the additive, Zn in the classic group II and Ba, Co, Cu, and Ni, which are commonly presented as intermediates between group I and II, have been elevated to group III elements for the lignite tested. On trace element partitioning trends across the boiler, the group encompassing As, Cr, Mn, and V, witnessed a noticeable reduction in enrichment across all boiler positions upon using the silica-based additive. The group; Ba, Co, Ni and Zn, have depleted concentrations irrespective of the use of the silica-based additive. For the rest of the trace elements particularly Be, Cu, and Pb, they have intertwining trends between the different RE sections, and also between the two combustion cases of the raw coal and coal mixed with the silica-based additive. Out of all the trace elements studied, addition of the silica-based additive had an opposite effect on Sr where its RE factors was increased throughout. Upon statistical analysis for the case of raw coal alone, As was found to mainly correlate with Ca and Si; Ba, Cr, and Cu was found to correlate with Fe; and V, to correlate with Ca. Addition of the silica-based additive was shown to provide competing reactions for the heterogeneous transformation of the trace elements and hence altering their relationships. This was further supported by X-ray absorption near-edge structure spectroscopy (XANES) analysis of Cr in ash deposits. The amount of highly hazardous Cr(VI) was found to be in between 0% and 14%, with the addition of the silica-based additive incurring an overall reduced Cr(VI) capture/fixation, partially due to significant Cr contamination effect derived from the silica-based additive itself.