典型生物质提取二氧化硅的反应控制机理及其实验研究

发布时间：2018-03-15 04:21

本文选题：生物质　切入点：二氧化硅　出处：《哈尔滨工业大学》2016年博士论文　论文类型：学位论文

【摘要】：我国生物质资源储量丰富、分布广泛。但是,大部分生物质或常年堆积,占用大量良田,或就地焚烧,浪费严重且造成环境污染。本文对典型生物质提取二氧化硅的反应控制机理及其实验进行了研究,主要研究内容包括:生物质提取二氧化硅的可行性与经济性研究、获取含高活性二氧化硅生物质灰的生物质燃烧前处理(干燥)及其颗粒燃烧反应控制研究、生物质作为电厂燃料燃烧后得到的活性灰制取水合二氧化硅的工艺参数影响及活性灰中二氧化硅提取的动力学特性研究。本文主要工作包括以下几个方面:利用改进的Harrion方法,将四种生物质(稻壳、玉米秸秆、稻秸和豆秸)完全氧化。采用傅里叶光谱分析、扫描电镜和透射电镜等方法分析四种生物质中所含硅的形态、结构以及含量等参数,得出结论:稻壳、稻秸、玉米秸秆都可以作为提取二氧化硅的原材料,而豆秸内的二氧化硅含量较少,可以忽略不计;其中稻壳是四种生物质中提取二氧化硅(用来制取水合二氧化硅)最经济的原材料。对适于利用其灰提取二氧化硅的生物质(以稻壳为例)进行干燥实验,研究干燥特征;从干燥过程中湿分扩散的角度对传质规律进行分析,建立干燥动力学模型,利用扩散方程根据实验数据求出有效湿分扩散系数等参数,得到相应的动力学模型。生物质根据干燥特征及动力学特性干燥后,将生物质的燃烧分为三个主要阶段:预热(初始预热阶段和热解前预热阶段)、热解、炭转化,建立生物质颗粒燃烧反应控制模型并进行数值分析。控制燃烧反应条件,利用模型预测得到稻壳燃烧转化时间与二氧化硅提取效率的关系曲线,与实验得到的稻壳燃烧转化时间与二氧化硅提取效率的关系曲线比较,验证模型的有效性。以生物质电厂活性灰(含有活性二氧化硅的生物质灰)为原料,采用碱煮沉淀法制取水合二氧化硅。分析提取二氧化硅过程中的各种影响因素,得出制取水合二氧化硅的优化方案。检测该方案得到的产品性能,结果显示产品性能优于国家标准HG/T3061(2009)。采用二阶速率法,对不同的因素在二氧化硅提取过程中提取作用的显著性及提取动力学特性进行了研究。对生物质前处理(干燥)的研究以及建立保证二氧化硅高活性的生物质燃烧反应控制模型,可以指导有利于生物质中二氧化硅提取的燃烧设备设计、制造及运行。而碱煮沉淀法制取水合二氧化硅以及对生物质活性灰中二氧化硅提取反应动力学的研究,指导了鹤岗万源生物质电厂稻壳灰制取水合二氧化硅的工业化生产,年处理稻壳灰1.2万吨,年产5000吨优质水合二氧化硅。
[Abstract]:The biomass resources in China are rich in reserves and widely distributed. However, most of the biomass is accumulated all year round, occupying a large amount of good farmland or burning on the spot. In this paper, the reaction control mechanism and experiments of extracting silica from typical biomass are studied. The main research contents include: feasibility and economy of extracting silica from biomass. Study on biomass combustion pre-treatment (drying) and particle combustion reaction control of biomass fume containing highly active silica, The effects of the process parameters on the production of hydrated silica from the activated ash from biomass as fuel combustion in power plant and the kinetic characteristics of the extraction of silica from the activated fume are studied in this paper. The main work of this paper includes the following aspects: the improved Harrion method is used to produce hydrated silica. Four kinds of biomass (rice husk, corn straw, rice straw and soybean straw) were completely oxidized. The morphology, structure and content of silicon in the four kinds of biomass were analyzed by Fourier spectroscopy, scanning electron microscopy and transmission electron microscopy. Conclusion: Rice husk, rice straw and corn straw can all be used as raw materials to extract silica, but the content of silica in soybean straw is less and can be ignored. Rice husk is the most economical raw material for extracting silica from four kinds of biomass. From the point of view of wet diffusion during drying, the mass transfer law is analyzed, the drying dynamics model is established, and the effective moisture diffusion coefficient is obtained by using the diffusion equation according to the experimental data. The biomass combustion was divided into three main stages: preheating (initial preheating and preheating before pyrolysis, pyrolysis, carbon conversion). The control model of biomass particle combustion reaction was established and numerically analyzed. The relationship curve between the combustion conversion time of rice husk and the extraction efficiency of silica was obtained by controlling the combustion reaction conditions and using the model to predict the relationship between the combustion conversion time and the extraction efficiency of silica. Compared with the experimental curves between the combustion conversion time of rice husk and the extraction efficiency of silica, the validity of the model was verified. The active ash of biomass power plant (biomass fume containing active silica) was used as raw material. The hydrated silica was prepared by alkali boiling precipitation method. The factors affecting the extraction of silica were analyzed, and the optimized scheme for the preparation of hydrated silica was obtained. The performance of the product obtained from the scheme was tested. The results show that the performance of the product is superior to that of the national standard HG / T3061 / 2009.The second order rate method is used. The significance and extraction kinetics of different factors in the extraction of silica were studied. Study on Biomass Pretreatment (drying) and Establishment of Biomass Combustion with High activity of Sio _ 2. Burning reaction control model, It can be used to guide the design, manufacture and operation of combustion equipment for the extraction of silica from biomass, while the preparation of hydrated silica by alkali boiling and precipitation and the study on the kinetics of extraction reaction of silica from biomass active fume. The industrial production of producing hydrated silica from rice husk ash in Hegang Wanyuan Biomass Power Plant was guided. The annual treatment of rice husk ash was 12,000 tons and the annual output was 5 000 tons of high quality hydrated silica.
【学位授予单位】：哈尔滨工业大学
【学位级别】：博士
【学位授予年份】：2016
【分类号】：TQ127.2

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