【作者】 孙佰仲；

【导师】 孙保民； 李少华；

【作者基本信息】 华北电力大学（北京） ， 热能工程， 2009， 博士

【摘要】 油页岩是一种重要的能源资源,在世界范围内油页岩储量折算成发热量仅次于煤,在化石燃料中位列第二。作为油页岩干馏炼油后的半焦,挥发分含量低、热值低、灰分大,因此难着火、难燃尽,且污染环境。为了有效处理油页岩干馏后产生的半焦,最大限度利用油页岩资源,本文通过模拟巴西佩特洛瑟克斯(Petrosix)干馏工艺,搭建了油页岩干馏实验装置。在对油页岩和半焦的理化特性及微观结构特性进行分析的基础上,从理论和试验两个方面开展油页岩半焦、油页岩及半焦混合物的燃烧特性研究。进行了油页岩及半焦混合燃烧热分析实验,详细研究了油页岩干馏终温、升温速率、粒径以及掺混比对燃烧特性的影响。理论上,采用分布活化能模型(DAEM)获得了混合燃烧动力学参数,并分析了活化能的变化趋势。基于补偿效应分析,结合热重曲线、反应性和预测能力对混烧过程中组分间的相互影响,进行了混烧过程动力学参数的预测研究。结果表明,混烧过程中各组分之间产生的协同作用有效改善了混烧特性和反应性。通过采用Logistic函数模拟的分段动力学和总体动力学研究表明,由于存在不同的燃烧段,各段相对应的活化能和频率因子的预测能力不同。在小型流化床燃烧试验台上进行了油页岩及半焦的流化燃烧试验研究,并就原油页岩及灰渣样品的孔隙结构进行了系统分析,获得了相应的吸附和脱附等温线。基于BET法、BJH法和FHH模型,获得了样品的比表面积、孔分布及分形维数。结果表明,燃烧过程中油页岩的比表面积和孔体积的变化趋势为先迅速增加再逐渐降低,而半焦的孔体积整体呈逐渐递减趋势,且较低的流化床温有利于孔结构的形成和发展。燃烧前期,油页岩灰渣表面分形维数迅速增加,而后略有减小,燃烧后期几乎不再变化。燃烧过程中灰渣的分形维数明显大于原油页岩分形维数。从理论和试验两个方面,对固定床及流化床两种不同燃烧方式下混合燃料的着火和燃尽特性进行了研究。结果表明,不同燃烧方式下油页岩着火机理存在明显差异,采用固定床燃烧方式或流化床间断给料的条件下,油页岩燃烧为均相着火;而流化床一次给料时则处在向非均相着火过渡的状态。同样,燃烧方式对油页岩和半焦的着火温度影响显著,固定床下着火温度最低,而流化床一次给料条件下着火温度较高。床温和粒径是影响油页岩及半焦混合燃尽的重要因素,燃尽时间随床温升高而减小,燃料粒径越大,床温影响越明显;燃烧过程比较扩散控制而言更接近于动力控制。在大型循环流化床燃烧试验台上进行油页岩及半焦混烧试验,系统研究了混合比、床层温度、一二次风配比等参数对循环流化床燃烧特性影响,获得炉内温度、物料粒度及炉内烟气成分分布特点。结果表明,采用循环流化床燃烧方式处理油页岩半焦是非常适宜的,所产生的灰渣含碳量总体在3%以内,但一次风率不低于66.7%。如在半焦中掺入10～20%的油页岩可以更好地改善燃烧状况,提高燃烧效率。通过本文研究,不但掌握了油页岩半焦的燃烧特性,而且能为油页岩及半焦循环流化床锅炉的设计开发提供参考依据。更多还原

【Abstract】 Oil shale,a kind of potential and tremendous energy resource,is only next to coal in terms of the calorific value among the fossil fuels in the world.As spent shale,semi-coke is a low-grade fuel with low volatile,low calorific value,high ash content and is difficult to ignite and burnout.At same time,semi-coke has serious pollution to environment.Oil shale was retorted in a laboratory-scale fixed bed reactor to obtain semi-coke.After physicochemical properties and microstrnctures of oil shale and semi-coke were investigated,systematic theory and experimental investigations were conducted for the blends.Combustion experiments of the blends were conducted on thermo-gravimetric analyzer (TGA) with different heating rate,retorting temperature,particle size and blends ratio respectively.Theoretically,combustion kinetics has been determined by distributed activation energy model(DAEM) and activation energy profiles were analyzed.Based on compensation effect incorporation with TG curves,reactivity and prediction ability,co-combustion kinetics was studied in detail.The results indicated that some synergistic effects occured between oil shale and semi-coke during combustion and those effects improved combustion characteristics and reactivity.Logistic function was applied to simulate combustion process and the prediction ability of kinetic parameters was different at different stages.Combustion experiments of oil shale and semi-coke were conducted in bench-scale FBC reactor.Ash samples were obtained under different bed temperature and different resident time.Adsorption and desorption isotherms of samples were determined by Micromeritics Gemini 2380 specific area analyzer under nitrogen atmosphere.The specific surface area and pore size distribution were determined on the basis of BET and BJH theory respectively. While surface fractal dimensions were calculated with FHH model.The results indicated that the specific surface area and porous volume of oil shale ash increased first and then decreased whereas porous volume of semi-coke ash deceased all along with resident time increasing; Low combustion temperature favored the formation of porous structure.At early stage of combustion,the fractal dimension of ash samples increased sharply,and then decreased slightly.At the same time,the fractal dimension of all ash samples was significantly higher than that of original samples. Ignition and burnout characteristic of the blends were studied with different combustion modes.Changes of combustion technique related to different experimental conditions had strong effects on ignition mechanism.Oil shale fixed bed experiment and fluidized bed experiment for pulse feed indicated a homogeneous ignition mechanism.Oil shale ignition mechanism of fluidized bed experiment for once feed shifted from homogeneous to heterogeneous one.Ignition temperature was affected by different combustion technology to some extent.There was a lower ignition temperature for fixed bed experiment than others. Ignition temperature was high for once feed in fluidized bed experiments.CFBC pilot was set up for combustion of oil shale and semi-coke.Co-combustion of the blends was conducted in different conditions such as blends ratio,bed temperature and primary air ratio.Distributions of temperature,flue gas composition were obtained.The result of tests showed that semi-coke was suitable for combustion in CFB and the ash could be utilized as build material when the primary air ratio was not less than 66.7%.The combustion was even improved when 10～20 percent oil shale was added.The results may provide theoretical foundation for the design of large-scale CFB boiler fired with oil shale semi-coke.更多还原