Using Chinese fir sawdust as research object,wood vinegar was prepared by pyrolysis after hydrothermal pretreatment at 180-280℃.The evolution of Chinese fir sawdust components at different hydrothermal temperatures was analyzed by van Soest method,and the effects of the evolution of Chinese fir sawdust components after hydrothermal pretreatment on the yield,organic components,and physicochemical properties of wood vinegar were investigated by using gas chromatography-mass spectrometry(GC-MS),acidity meter,and other testing methods.The results showed that with the increase of hydrothermal temperature,the content of hemicellulose in hydrothermal sawdust decreased continuously.The cellulose content showed a trend of first increasing and then decreasing.The lignin content gradually increases.With the increase of hydrothermal temperature to 230℃,the contents of phenolic and aldehyde in wood vinegar increased gradually,which was consistent with the change trend of lignin and cellulose content respectively.The content of acid compounds slightly decreased,showing a positive correlation with changes in the total content of hemicellulose and cellulose,which are the main sources of acid compounds.When the hydrothermal temperature is 180-230℃,the massive decomposition of hemicellulose in hydrothermal Chinese fir sawdust leads to an increase in the content of cellulose and lignin,resulting in a higher density and lower pH of wood vinegar,but the yield increases only before 200℃.By optimizing the proportion of three components of Chinese fir sawdust through hydrothermal pretreatment,higher quality wood vinegar can be produced.

随着畜禽养殖业的规模化、集约化发展,畜禽粪便大量、集中产生,由于我国畜牧业与农业结合不紧密,且畜禽粪便中含过量重金属和抗生素,导致畜禽粪便的回田利用难度大.畜禽粪便经水热处理后制备生物燃料,可实现其能源化、无害化利用.以产量最大的猪粪为代表,总结了其组分及理化性质,讨论了传统处理方式的缺陷,对水热处理后猪粪残渣的产率、燃烧特性及脱水性能进行分析概述,最后探讨了水热残渣作生物燃料的发展前景.猪粪中含有半纤维素、纤维素、木质素、蛋白质及脂类等成分,且富含氮、磷、钾等植物生长所需的营养元素,合理处理后可实现资源化利用.好氧堆肥及厌氧发酵技术难以高效降解猪粪中的抗生素,且猪粪中高浓度的重金属也会对堆肥及发酵过程产生不利影响.水热处理是一种很极具前景的处理畜禽粪便等高含水率生物质的技术.通过水热处理可将猪粪转化为与褐煤相当的水热残渣及稀释后可用于灌溉的水热残液,且能有效固化重金属及降解抗生素.水热处理过程中有机物的降解和溶解使猪粪水热残渣的产率随水热温度升高呈下降趋势.在范式图中,猪粪水热残渣可达到褐煤区域,且其挥发分及高位热值也能达到褐煤水准.大量结合水在水热处理过程中被转化为自由水,改善了猪粪水热残渣的脱水及干燥性能.此外,碱金属在水热处理过程中易溶解进水热残液,降低了水热残渣燃烧时的结渣风险.水热处理可将重金属富集在水热残渣中,并降低其浸出率及生态毒性.猪粪水热残渣良好的燃烧特性及可研磨性使其具备与煤共燃的潜力,但需对煤粉炉进行适当改造并控制合理的过量空气系数等参数.猪粪与农林废弃物的共水热处理可降低水热残渣的灰分含量,提高固定碳含量及高位热值.畜禽粪便水热处理工艺的经济性问题是限制其工业化应用的主要原因,通过优化工艺设计等手段,有助于水热处理技术在畜禽粪便处理问题上的实际应用.

新疆的高钠煤是一种开采成本低、灰分低、含硫量低的优质燃料,但较高的钠含量导致其在燃烧利用的过程中易出现沾污结渣等现象,严重阻碍了高钠煤的开发利用.以2种高钠煤(五彩湾煤(WCW)、哈密煤(HM))和1种低钠煤(平朔煤(PS))作为实验对象,在900℃下燃烧制灰,并将所制煤灰置于38％、51％和76％的NaCl蒸气下进行钠捕获实验,使用ICP-OES测得钠捕获前后煤灰的钠含量,采用XRD分析钠捕获前后煤灰中矿物质的变化,采用压降法测量钠捕获前后煤灰的烧结温度,深入探究不同NaCl蒸气体积分数下煤灰烧结特性的衍变规律.结果表明:在3种NaCl蒸气体积分数下,3种煤灰样品中PS煤灰的钠捕获量最大,HM煤灰次之,WCW煤灰最低.Si、Al能增强煤灰的钠捕获性能,而Ca则会与Si、Al发生反应,从而抑制Si、Al对NaCl蒸气的化学固定,不利于煤灰的钠捕获.随NaCl蒸气体积分数升高,钠捕获量增大,煤灰的烧结温度降低幅度与其钠捕获量呈正相关.HM、WCW煤灰烧结温度降低幅度均大于PS煤灰,一方面是由于HM和WCW煤灰固钠后生成的含钠化合物的熔点低于PS煤灰,另一方面NaCl蒸气体积分数升高促进了低熔点含钠化合物的生成.PS煤灰在900℃下尚未发生烧结,其结构疏松、内部孔隙多,与NaCl蒸气反应完全程度相对较高,其烧结温度受NaCl蒸气体积分数影响最小.