【作者】 严君伟；

【导师】 姜秀民；

【作者基本信息】 上海交通大学 ， 热能工程， 2013， 博士

【摘要】 油页岩是一种富含油母质的沉积物，是非常重要的替代能源之一。随着当今世界能源需求的不断增长，寻找有效和经济的利用油页岩的方法具有十分重要的意义。遗憾的是，油页岩工业中仍然存在着一些严重的问题，其中之一便是油页岩半焦的处理。为了有效利用油页岩半焦并且解决油页岩工业中存在的一些其他问题，一些学者提出了“油页岩综合利用技术”，其中的关键技术就是将油页岩半焦作为燃料投入循环流化床焚烧来发电和供热，这样既最大程度地利用了半焦中残余的化学能又避免了对环境造成严重的污染。但是，油页岩半焦流化床燃烧的工业应用中依然存在着一些技术难题需要去克服，比较突出的是由于油页岩半焦高灰分、低热值的特点使其在流化床中着火和燃烧性能较低，燃尽很困难。而另外一个问题则是由于流化床技术低温燃烧特性及油页岩半焦本身燃料特性两方面原因造成燃烧过程中排放的温室气体氧化亚氮(N2O)的浓度较高。本文研究的就是这两个技术难题，尝试着反映其实质，寻找提高油页岩半焦燃烧效率和降低其N2O排放的方法。首先研究了油页岩半焦的一些基础燃料特性，然后在热态流化床实验台上对半焦进行燃烧实验掌握了不同工况下的燃烧特性和炉膛中氮氧化物的生成、转化和排放特性，随后根据实验结果建立半焦流化床燃烧的数学模型并对燃烧过程及氮氧化物的转化过程进行数值模拟，通过实验和模拟结果的分析对比提出若干降低半焦流化床燃烧过程中氮氧化物特别是N2O排放的技术措施，最后在实际生产的循环流化床锅炉上进行油页岩半焦的工业实验来验证通过流化床技术处理油页岩半焦的可行性。对于油页岩半焦基础特性的研究中，主要针对的是半焦热化学转化过程中矿物质对有机物燃烧的催化作用和燃烧过程中由矿物质生成的灰分对于氧气的传质阻力特性。研究结果表明半焦中无机矿物质能够催化有机物的氧化反应，从而加快有机物的燃烧速率；氧气沿着平行于灰分层层理面的传质能力比垂直于层理面时强一个数量级，因此在研究油页岩半焦流化床燃烧时完全可以忽略后者而认为氧气在灰层中的传质完全是通过平行于层理面的方向进行的。而研究过程中计算得到的半焦燃烧动力学参数和灰分层有效扩散系数则可以用于后文的数值模拟工作。油页岩半焦流化床燃烧特性研究中，通过小型、大型热态流化床实验台考察了颗粒粒径、钙硫比、循环倍率和矿物质等四个燃料因素和床温、过量空气系数和二次风工况这三个运行参数对于半焦燃烧特性和污染物排放的影响，分析了两个实验台上燃烧的异同点，初步了解了燃烧过程中氮氧化物的生成和转化规律。油页岩半焦流化床燃烧数值模拟部分，首先进行了半焦热解实验，通过对热解残渣、冷凝的液相和不凝的气相进行分析测试，建立了半焦热解产物模型。然后，根据小型、大型流化床的实验结果建立了油页岩半焦流化床燃烧的反应器模型、多相流模型、动力学模型、破碎模型等并结合热解产物模型对半焦流化床燃烧进行了数值模拟，通过与实验结果进行对比分析总结出了对氮氧化物转化起重要作用的反应，掌握其基本转化机理，并提出了一些可行的减排措施。油页岩半焦流化床燃烧工业示范实验部分，在实际运行的工业循环流化床锅炉上进行了两个工况下的工业示范实验，实验结果证明了以油页岩半焦为燃料的循环流化床锅炉可以稳定运行，各基本参数保持稳定,燃烧效率能达到95%以上，污染物排放达到国标要求。更多还原

【Abstract】 Oil shales, which are kerogen-rich sediments, are one of the most important energy alternatives.1With the growing of the energy demand in today’s society, it has important significance to seek theeffective and economical ways to utilize oil shale. Unfortunately, there are still some vital problems inthe oil shale industry and one of them is the disposal of shale char.In order to utilize shale char effectively and solve some other problems in oil shale industry, someresearcher put forward the “New technology for the comprehensive utilization of Chinese oil shaleresources”. The key section of this system is the burning of shale char in circulating fluidized bedfurnaces to supply heat and generate electricity, which achieves high utilization-factors for both oilshale’s chemical and energy potentials, and avoiding serious environmental impacts.However, there are still some technical problems need to be overcome during the practicalindustrial application of burning shale char in circulating fluidized bed furnace. One of them is thelower ignition and combustion property of shale char due to its high ash content and low calorific value,which makes it difficult to be burned out in fluidized bed combustor. Another problem is the relativelyhigh N2O emission during the combustion due to the low-temperature combustion characteristics offluidized bed technical and the fuel characteristics of shale char.The research objects of this paper are just these two problems, it tries to reflect their essences andfind solutions to improve the combustion efficiency of shale char and reduce N2O emission. In thispaper, some basic properties of shale char were studied firstly. And then the combustion experiments ofshale char in fluidized bed apparatuses was carried out and the transformation of nitrogen oxide andfinal emission characteristics were obtained. After that the mathematical model of shale char burning influidized bed furnace was established and the numeraical simulation of combustion process andtransformation of nitrogen oxide were carried out. By comparing the experimental and simulationresults, the transformation discipline of nitrogen oxide in fluidized bed furnace was summarized. At last,thedemonstration experiment of shale char burning in industrial CFB boiler was carried out to verify thefeasibility of disposing shale char through fluidized bed technology.During the research of shale char basic properties, two main study aspects were the the catalysis effect of mineral matrix in shale char during its thermochemical conversion and the mass transfercharacteristics for oxygen in the ash layer of shale char. The research results indicate that minerals inshale char can accelerate the combustion rate of organic matter and the ash layer effective diffusivityalong the direction parallel to the bedding planes is almost an order of magnitude greater than that alongthe direction perpendicular to the bedding planes. And the calculated kinetic parameters of shale charcombustion and ash layer effective diffusivity can be used in the later numerical simulation work.During the research of combustion properties of shale char in fluidized bed furnace, firstly, theinfluences of particle size, Ca/S, circulation ratio and minerals on the pollutant emissions during thecombustion of shale char were investigated in a small-scale fluidized bed furnace, and theconcentrations of some gases at different height above distributor at standard condition were measured,thus the formation and abatement disciplines of nitrogen oxide during the FB combustion wereunderstood preliminarily. And then systematic experimental research of burning shale char in alarge-scale semi-industrial fluidized bed furnace was carried out, thus the formation and transformationproperties of nitrogen oxide at dfferent bed temperatures, secondary ratios and Ca/S conditions wereobtained preliminarily.During the research of numerical simulation of burning shale char in fluidized bed furnace, thepyrolysis experiment of shale char was carried out by using the small-scale fluidized bed furnace firstly,and the pyrolysis products model was established through the analysis and test to the pyrolysis residual,condensed liquid phase and non-condensable gas phase. Then the reactor model, multiphase flow model,kinetic model, crushing model etc were established according to the experimental results of burningshale char in small and large scale fluidized bed furnace. The numerical simulation of burning shalechar in fluidized bed furnace was carried out by integrating the above models. By comparing andanalyzing the simulation and experiment results, the key reactions for the conversion of nitrogen oxidewere summarized and the basic transformation mechanism of them was obtained, some effectiveemission reduction measures have been proposed.During the research of industrial demonstration experiment of burning shale char in CFB boiler,the industrial demonstration experiments at two conditions selected according to the preliminaryresearch results were carried out in an industrial CFB boiler. The experimental results certified that theCFB boiler burning shale char could operate stably, the basic parameters remained stable, thecombustion efficiency could reach more than95%, and the pollutan emissions meet the national standard.更多还原