The effects of fuel washing techniques on alkali release from biomass
The effects of fuel washing techniques on alkali release from biomass
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DOI：
10.1016/s0016-2361(01)00132-6
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发表时间：
2002-01-01
期刊：
影响因子：
7.4
通讯作者：
Jäglid, U
中科院分区：
文献类型：
--
作者：
Davidsson, KO;Korsgren, JG;Jäglid, U
研究了不同清洗工艺对生物质热解过程中碱释放的影响。在洗涤和干燥之后，将小麦秸秆、木材废料和纤维素的样品在N-2气氛中进行恒定的加热速率，并且通过表面电离技术连续测量碱性化合物从样品的释放速率。碱在两个温度区间内从未处理的生物质中释放：（1）与在200-500 ℃下发生的热解过程有关，和（2）在高于600 ℃的温度下从热解后剩余的材料中释放。单独的真空热解实验表明，碱的释放是由含钾化合物占主导地位，从含钠化合物的贡献较小。将生物质的水洗效果与更彻底的酸浸技术进行比较。在200-500 ℃的温度范围内，用水洗涤可将木材废料和小麦秸秆的碱排放量减少5- 30%，而酸浸更有效，可减少约70%的排放量。在600 ℃以上，碱化合物从未处理的小麦秸秆中的蒸发急剧增加，洗涤程序足以使测量的碱释放减少90%以上。用纯纤维素（灰分含量0.07%）进行的实验表明，洗涤方法在去除与生物质的有机结构结合的碱方面是无效的。结果支持了早期研究的结论，即相对简单的洗涤技术可以改善具有高灰分含量的生物质燃料的燃烧性能。对于灰分含量较低的燃料，如木质生物质，与有机结构结合的碱的浓度限制了洗涤技术的效果。(C)2001爱思唯尔科技有限公司版权所有。
The influence of different washing techniques on the alkali release during pyrolysis of biomass is studied. After washing and drying, samples of wheat straw, wood waste and cellulose are subjected to a constant heating rate in a N-2 atmosphere, and the release rate of alkali compounds from the sample is measured continuously by a surface ionization technique. Alkali is released from the untreated biomass in two temperature intervals: (1) in connection with the pyrolysis process taking place at 200-500 degreesC, and (2) from the material remaining after pyrolysis at temperatures above 600 degreesC. Separate vacuum pyrolysis experiments show that the alkali release is dominated by potassium-containing compounds, with minor contributions from sodium-containing compounds. The effect of water washing of the biomass is compared with a more thorough acid leaching technique. In the temperature range 200-500 degreesC, washing with water reduces the alkali emission from wood waste and wheat straw by 5-30%, while acid leaching is more effective and reduces the emission by around 70%. Above 600 degreesC where the vaporization of alkali compounds from untreated wheat straws increases sharply, the washing procedures are sufficient for a reduction in the measured alkali release by more than 90%. Experiments with pure cellulose (ash content 0.07%) indicate that the washing methods are ineffective in removing alkali bound to the organic structure of the biomass. The results support the conclusion from earlier studies that relatively simple washing techniques can improve the combustion properties of biomass fuels with a high ash content. For fuels with a lower ash content like woody biomass, the concentration of alkali bound to the organic structure limits the effect of the washing techniques. (C) 2001 Elsevier Science Ltd. All rights reserved.