农业废弃物混煤燃烧特性及污染物排放特性研究

发布时间：2018-02-13 11:19

本文关键词： 农业废弃物煤混烧污染物 HCl　出处：《华中科技大学》2015年硕士论文　论文类型：学位论文

【摘要】：农业废弃物是重要的生物质资源,由于它具有资源丰富和利用过程环境友好等特点受到了世界各国的广泛关注。然而在目前的技术条件下农业废弃物混煤燃烧是大规模利用农业废物的方法之一,农业废弃物混煤燃烧不仅可以降低污染物的排放,并且可以高效的利用低热值的农业废弃物物,是一种高效且环保的获取能源的方法。由于农业废弃物混煤燃烧的现在技术条件限制和对燃烧特性认识的欠缺以及国内没有相关的扶植政策,使得混燃技术在中国并没有普及。本文以此为背景,选用麦秆、玉米秆和稻壳三种典型的农业废弃物,研究农业废弃物混煤(无烟煤和褐煤)燃烧时的燃烧特性和污染物排放特性。使用德国NETZSCH公司的STA409C型热重分析仪对农业废弃物和煤样单独燃烧和混合燃烧时的燃烧特性进行了研究,考察了在不同混合比例和不同升温速率下的混合物的燃烧特性。结果表明,当农业废弃物掺混比为20%的时候混合物整体表现出煤样的特性,当掺混比升高到50%的时候混合物整体表现出生物质的特性。升温速率的升高有利于混合物的燃烧。运用Coats-Redfern积分法求得动力学特性参数,结果表明农业废弃物挥发分燃烧阶段所需的活化能明显低于焦炭燃烧阶段更低于煤燃烧所需的活化能,当农业废弃物混煤燃烧时能明显降低煤燃烧所需的活化能,提高煤的燃烧性能。总的来说农业废弃物混煤燃烧能明显提高煤的燃烧特性使用管式炉进行燃烧过程中污染物排放的实验研究,主要针对SO2、NO和HCl这三种污染物进行了研究,实验中对农业废弃物和煤单独燃烧时的污染物排放特性进行了研究并考察了不同掺混比和不同炉温条件下的污染物排放特性。结果表明相对于煤单独燃烧而言,农业废弃物混煤燃烧能降低SO2和NO的排放,同时掺混比和炉温变化时SO2和NO的排放特性也随之变化,但是总体而言都能减少SO2和NO的排放。但是相对于煤单独燃烧而言,农业废弃物混煤燃烧时会增加HCl的排放,随着掺混比的增加HCl的转化率降低,但是都远高于煤单独燃烧时HCl的排放量。由于HCl的危害性极大,并且目前没有成熟的技术减少HCl的排放,所以本文研究了添加剂对燃烧过程中HCl排放的影响。结果表明:石灰石和高岭土都能减少燃烧过程中HCl的排放,但是石灰石的减排效果更好也更经济。
[Abstract]:Agricultural waste is an important biomass resource. Because of its rich resources and environmentally friendly utilization process, it has attracted wide attention from all over the world. However, under the present technical conditions, mixed coal combustion of agricultural waste is one of the methods for large-scale utilization of agricultural waste. The mixed coal combustion of agricultural waste can not only reduce the emission of pollutants, but also efficiently utilize the low calorific value of agricultural waste. It is an efficient and environmentally friendly way to obtain energy. Due to the current technical conditions of mixed coal combustion of agricultural waste, the lack of understanding of the combustion characteristics and the absence of relevant domestic support policies, In this paper, three typical agricultural wastes, wheat straw, corn stalk and rice husk, are selected. The combustion characteristics and pollutant emission characteristics of agricultural waste mixed coal (anthracite and lignite) were studied. Combustion of agricultural waste and coal samples by using STA409C thermogravimetric analyzer of NETZSCH, Germany. The burning characteristics were studied. The combustion characteristics of the mixture with different mixing ratios and different heating rates were investigated. The results showed that when the blending ratio of agricultural wastes was 20%, the whole mixture showed the characteristics of coal samples. When the blending ratio increases to 50%, the whole mixture exhibits the characteristics of biomass, and the increase of the heating rate is beneficial to the combustion of the mixture. The kinetic parameters are obtained by using the Coats-Redfern integral method. The results show that the activation energy required in the volatile combustion stage of agricultural waste is obviously lower than that in the coke combustion stage, and the activation energy required for coal combustion can be significantly reduced when agricultural waste is mixed with coal. Generally speaking, the combustion characteristics of agricultural waste mixed coal can obviously improve the combustion characteristics of coal. The experimental study on pollutant emission during combustion is carried out in tubular furnace, mainly for the three kinds of pollutants such as so _ 2O _ 2 no and HCl. In the experiment, the pollutant emission characteristics of agricultural waste and coal combustion alone were studied, and the pollutant emission characteristics under different mixing ratio and different furnace temperature were investigated. The results showed that compared with coal combustion alone, The combustion of mixed coal from agricultural waste can reduce the emission of SO2 and no, and the emission characteristics of SO2 and no also change with the change of blending ratio and furnace temperature, but in general, it can reduce the emission of SO2 and no, but compared with coal combustion alone, With the increase of blending ratio, the conversion rate of HCl will decrease, but it will be much higher than the amount of HCl in coal combustion alone. Because of the great harmfulness of HCl, And there is no mature technology to reduce the emission of HCl, so the effect of additives on HCl emission during combustion is studied. The results show that both limestone and kaolin can reduce the emission of HCl during combustion. But limestone cuts emissions better and more economically.
【学位授予单位】：华中科技大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TQ534;X71

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