垃圾富氧焚烧特性及工艺研究

发布时间：2018-08-13 16:31

【摘要】：随着经济的快速发展,我国城镇化规模日益增大,随之带来的是各种城市问题,其中城市生活垃圾(MSW)的处理已经越来越受政府及公众的重视。焚烧是垃圾资源化、无害化、减容减量化最佳的处理方式,但由于我国垃圾水分、灰分高、热值低的特点,再加上垃圾分类制度不健全,我国城市垃圾利用常规空气焚烧技术时主要遇到两大类问题:一是焚烧不完全、不稳定;二是污染物成分复杂、治理难度大。现有的焚烧技术已经很难在这两方面实现突破,并且常规焚烧技术在高原地区并不适用,开发新的焚烧技术势在必然。富氧焚烧技术是一种新型高效的焚烧技术,十分适合焚烧我国这种低品质的垃圾燃料。因此本文对垃圾富氧焚烧技术的焚烧特性以及工艺系统的开发进行了针对性的研究。首先,通过热重分析仪(TGA)对垃圾中最典型、最主要的可燃成分以及其混合组分进行了富氧焚烧特性的研究,实验结果显示氧浓度的升高能有效的改善焚烧特性,水分却推迟了着火点,使TG曲线滞后。通过TG/DTG实验数据计算出了综合燃烧特性指数、动力学参数并对着火点进行了判别。计算结果同样显示了富氧对改善焚烧有明显的促进作用。然后利用X射线光电子能谱仪(XPS)对垃圾典型组分中的C、N、S、Cl等物质的赋存形态进行了定性分析,并结合水平管式炉上的富氧焚烧实验对各污染物的排放机理进行了研究,还探讨了水分对污染物排放的影响。结果发现,氧浓度的升高使得CO、CH4的排放下降,同时HCN的排放也会随着CH自由基的减少而明显降低;垃圾焚烧后NO的生成主要来源于燃料-N,在焚烧过程中燃料-N会随着氧浓度的升高而更多的生成NO;同时氧浓度的升高使得炉内氧化性增强,HCl的排放会略微降低,但SO2的生成会略微增大,这是因为氧气会促进HCl与硫酸盐的反应。水分的提高会使得CO、CH4、HCN的生成出现先降低后增大的变化趋势,因为水分会与CO、CH4以及固定C发生一系列的化学反应;同时水分的OH自由基会将更多的燃料N氧化为NO,同时燃料中的更多的氯盐在高温水解析出,然后再分解,使得HCl的排放同样增大;水分对垃圾焚烧后SO2的生成没有明显的影响。富氧焚烧能够抑制水分与含碳污染物的反应,但NO与HCl的排放却有一定幅度的升高,由于实际垃圾富氧焚烧技术会降低过量空气系数并采用烟气再循环,NO的排放总量并不会升高,但是脱水预处理与脱硫脱硝对于垃圾富氧焚烧同样必不可少。最后对垃圾富氧焚烧技术的关键参数以及工艺系统进行了初步研究,在绝对燃烧温度、排烟损失、实际燃烧温度等方面与常规空气焚烧进行了对比,提出了不同供氧模式和各个系统流程图,还提出了不同注氧装置的设计思路及结构示意图。从全文的研究结果显示,垃圾富氧焚烧作为一种新型焚烧技术在国内有广阔的运用前景,但同样还需要更多,更广的基础实验、分析测算以及工程运用的研究工作用以支持该技术的发展。
[Abstract]:With the rapid development of economy, the scale of urbanization in China is increasing day by day, which brings about a variety of urban problems. Municipal solid waste (MSW) treatment has been paid more and more attention by the government and the public. With the characteristics of MSW and the imperfect classification system of MSW, there are two major problems in the use of conventional air incineration technology in China: incomplete and unstable incineration; complex pollutant composition and difficult treatment. Oxygen-enriched incineration technology is a new and efficient incineration technology, which is very suitable for incinerating this low-quality waste fuel in China. Therefore, the incineration characteristics of waste oxygen-enriched incineration technology and the development of process system are studied. The most typical and main combustible components of garbage and their mixtures were studied by means of TGA. The experimental results show that the combustion characteristics can be improved effectively with the increase of oxygen concentration, but the ignition point is delayed by the increase of moisture content, and the TG curve lags behind. The results also show that oxygen enrichment can improve the incineration obviously. Then the occurrence forms of C, N, S and Cl in typical components of garbage were qualitatively analyzed by X-ray photoelectron spectroscopy (XPS), and the pollutants were discharged by oxygen enrichment incineration experiment in horizontal tube furnace. The results show that the emission of CO and CH4 decreases with the increase of oxygen concentration, and the emission of HC N decreases with the decrease of CH free radicals. The formation of NO after MSW incineration mainly comes from fuel-N, which increases with the increase of oxygen concentration. At the same time, with the increase of oxygen concentration, the oxidation of HCl is enhanced and the emission of HCl is slightly decreased, but the formation of SO2 is slightly increased, because oxygen will promote the reaction of HCl with sulfate. Fixed C undergoes a series of chemical reactions; at the same time, OH radicals in water oxidize more fuel N to NO, and more chloride salts in the fuel are hydrolyzed and precipitated at high temperature, and then decomposed to increase HCl emissions. Water has no obvious effect on SO2 formation after MSW incineration. Oxygen-enriched incineration can inhibit water and carbon content. However, the emission of NO and HCl increases to a certain extent. As the actual waste incineration technology will reduce excess air coefficient and use flue gas recycling, the total emission of NO will not increase, but dehydration pretreatment and desulfurization and denitrification are also necessary for waste oxygen-enriched incineration. Finally, waste oxygen-enriched incineration technology The key parameters and process system are preliminarily studied. The absolute combustion temperature, exhaust smoke loss and actual combustion temperature are compared with those of conventional air incineration. Different oxygen supply modes and flow charts of each system are proposed. The design ideas and structural sketches of different oxygen injection devices are also presented. The results show that as a new type of incineration technology, waste oxygen-enriched incineration has broad application prospects in China, but it also needs more and more extensive basic experiments, analysis, calculation and engineering application research to support the development of this technology.
【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】：X705

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