热解法生产成型生物质炭及其副产物特性研究

【作者】 杨丽；

【导师】 王华；

【作者基本信息】 昆明理工大学 ， 应用化学， 2013， 硕士

【摘要】 生物质能是人类赖以生存的重要能源,它仅次于煤炭、石油和天然气,居于世界能源消费总量的第四位,在整个能源系统中占有重要地位。我国的生物质资源十分丰富,但是生物质能量密度低、分布不集中,限制了生物质的规模生产和利用,而生物质成型技术和热解技术可有效地解决上述问题,使生物质资源得到有效利用。本论文根据不同生物质资源的化学成分分析、原料工业分析及对应的生物质炭工业分析,选取竹材、松木屑和核桃壳为原料,采用螺旋挤压成型设备,把原料压缩成棒状燃料。试验研究了生物质成型燃料成型的影响因素和物理性能,得出适宜的成型温度在170-200℃之间,适宜的原料粒度应大于40目,适宜的原料含水率范围是9%-11%,这为生物质成型燃料的生产和使用提供基础理论数据。利用热分析技术研究了竹材、松木屑和核桃壳的热解过程,分析了此类生物质的热解规律。通过改变热解温度、升温速率和热解时间,研究了这些因素对竹材、松木屑、核桃壳、竹材与核桃壳的混合物、松木屑与核桃壳的混合物热解成炭的性能影响。采用正交实验和多指标直观分析法,通过各因素对成型炭性能参数影响的综合分析评价,得到了竹材的最佳热解温度是400℃、最佳升温速率是10℃/min、最佳热解时间是30min,松木屑最佳热解温度是400℃、最佳升温速率是5℃/min、最佳热解时间是30min,核桃壳的最佳热解温度是500℃、最佳升温速率是5℃/min,最佳热解时间是30min,为竹材、松木屑和核桃壳的综合利用提供依据。对生物质炭进行了工业分析,得到松木炭的固定碳含量达到一级标准,由竹材、核桃壳、75%核桃壳25%竹材和75%核桃壳25%松木屑制备的生物质炭达到优级标准。对生物质炭进行发热量测定,得出生物质炭的发热量大致在32MJ/kg-34MJ/kg,作为固体燃料的燃烧效果优于生物质原料。对生物质炭进行化学活性分析得到,生物质炭的化学活性与温度有着密切的联系,3种生物质炭的化学活性随温度的升高先急剧上升,之后趋于平缓,竹炭、松木炭和核桃壳炭3种生物质炭的还原率分别可达90.17%、86.46%和92.34%,由此可见,3种生物质炭的反应性能较好。对生物质炭进行结构参数分析,结合炭产物的SEM分析,确定生物质炭表面主要是中孔和大孔结构。对生物质热解燃气进行了GC分析,确定在热解过程中产生的气体主要成分为CO、H2、C02、CH4、C2H4、C2H6。热解温度对热解燃气的成分分布起着决定性的作用,升高热解温度有利于燃气的生成。通过计算生物质热解燃气的密度值和热值,发现生物质热解燃气的密度大致为1.0kg/m3-1.7kg/m3,随着热解温度的升高燃气密度降低；燃气热值大致为12000kJ/m3-16500kJ/m3,属于中值燃气,燃气热值随热解温度的升高,先升高后下降,这可能和气体含量随温度的变化有关。对热解得到的焦油进行分析,得到生物质焦油的热值大致在32MJ/kg-34MJ/kg,生物质焦油只含极少量的氮且都不含硫,所以可将生物质焦油作为一种循环环保液体燃料使用。对生物质焦油进行GC-MS分析,结果表明生物质焦油是复杂的有机化合物的混合物,包含了大部分的有机物类别,大致可分为芳香族、机酸、醛酮类、醇类、酯类、呋喃类、吡喃类和脱水糖类八大类,其中芳香族化合物占总量的50%左右,而芳香族化合物中又以酚类居多。更多还原

【Abstract】 Bioenergy has been the important energy that the mankind depended on for existence all the time, it is only second to the coal, petroleum, natural gas and occupy the fourth in the total amount of the energy consuming of the world, having the important position in the whole energy system. China is abundant in biomass resources, but the biomass’s energy density is too low to utilize. And the effective methods to resolve the problem and valid to utilize the biomass energy are biomass molding and pyrolysis technology.The Paper takes the bamboo, sawdust and walnut shell as the materials, based on the chemical composition analysis of raw materials, industrial analysis of raw materials and biomass carbons. Biomass raw materials are compressed into the clavate biomass densification briquetting by the spiral extrusion-shaping machine, excellent shaping apparatus. The influencing factor of relaxing density and durability of the biomass densification briquetting fuel was investigated in the experiment. The appropriate shaping temperature is between170℃and210℃, the appropriate size of raw materials should more than40mesh and the moisture content of raw materials is between9%and11%. The studying offered the basic data for production and usage of molding biomass.The thermal decomposition process of the mixture of the materials was studied by thermogravimetric analysis technology and then gained the biomass’s pyrolysis rule. Through alter different conditions of the pyrolysis temperature, heating rate, and pyrolysis time, investigated the effect of these factors of conditions to the properties. The paper studied the properties of biomass carbons of bamboo, sawdust, walnut shell; the mix of bamboo and walnut, the mix of bamboo and walnut shell by the orthogonal tests and the multiple indicators intuitive analysis method. Through the intuitive analysis and evaluated the influence of various factors to various properties of the molding carbons, obtained the optimum temperature of bamboo carbon is400℃, the optimum heatingrate of bamboo carbon is10℃/min, the optimum time of bamboo carbon is30min; the optimum temperature of sawdust carbon is400℃, the optimum heatingrate of sawdust carbon is5℃/min, the optimum time of sawdust carbon is30 min; the optimum temperature of walnut shell carbon is500℃, the optimum heatingrate of walnut shell carbon is5℃/min, the optimum time of walnut shell carbon is30min.Realized the sawdust carbon achieved first rank standard, the rest of the carbon achieve optimal level standard by the industrial analysis of carbon. Biomass carbon’s calorific value generally between32MJ/kg and34MJ/kg, it’s mean that as solid fuel, biomass carbon’s combustion effect is better than biomass materials. The chemical activity of the biomass carbon and temperature has the close relation that the chemical activity of the biomass carbons with a sharp rise in temperature increases first, and then tends to be gentle and the chemical activity of bamboo carbon; sawdust carbon and walnut shell carbon are90.17%、86.46%and92.34%by the chemical activity analysis of biomass carbons. Determine the biomass carbon surface is mainly in mesopore and macropore structure by Textural parameters and SEM images of biomass carbons.Determine the main ingredients of pyrolytic gas are CO, H2, CO2, CH4, C2H4and C2H6by the GC analysis of pyrolytic gas. Pyrolysis temperature has played a decisive role on pyrolysis gas composition distribution, high pyrolysis temperature for gas formation. Through the calculation of the biomass pyrolytic gas density value and calorific value, found that biomass pyrolytic gas’s density roughly between1.0kg/m3and1.7kg/m3, low temperature pyrolysis for gas density; pyrolytic gas’s calorific value roughly between12000kJ/m3and16500kJ/m3, belongs to the median gas, with the pyrolysis temperature increases, pyrolytic gas’s calorific value increased at first and then decreased, it’s may because the change of the gas content with the pyrolysis temperature.According to the analysis of biomass tar, found the biomass tar’s calorific value roughly between32MJ/kg and34MJ/kg, biomass tar contains little nitrogen and none of sulfur, its mean biomass tar is a kind of cycle environmental protection liquid fuel. Ingredients for biomass tar was determined by GC-MS, illustrate that biomass tar is a mixture of complicated organic compound, almost include all chemical category of organic matter, It contains organic compounds can be roughly divided into Aromatic compound, Aldehydes&ketones, Organic acid, Alcohol, Esters, Furan, Anhydrosugar and Pyrans. The Aromatic compounds accounted for about50%of the total, and Phenols is majority of Aromatic compounds.更多还原