【作者】 王鑫；

【导师】 向军； 徐俊；

【作者基本信息】 华中科技大学 ， 动力工程及工程热物理， 2023， 硕士

【摘要】 随着我国工业化和城市化的发展,污泥和煤泥产量逐年递增,导致大量污泥和煤泥急需处理。污泥和煤泥混合燃烧技术作为一种能够同时处理二者的方法,是一种具有广泛应用前景的固体废弃物处置技术。由于污泥和煤泥两种燃料常常具有“高硫”“高氮”的固有性质,混合燃烧过程中硫、氮迁移转化需要深入研究。为探究混合燃烧过程中硫、氮氧化物的生成规律和硫、氮的迁移转化机理,本文开展如下研究工作:开展了污泥和煤泥燃烧实验,研究了单独燃烧和混合燃烧的燃烧特性、SO₂和NO生成特性。结果表明,混合燃烧可加速燃烧进程,缩短燃烧持续时间;当温度大于900℃时,污泥出现两个SO₂释放峰;污泥的NO转化率随温度升高逐渐增加,煤泥的NO转化率则在800℃达到最大值;在温度为800℃,污泥掺混比例为20%时,混合燃烧可最大程度抑制SO₂和NO的生成。揭示了混合燃烧过程中硫的迁移转化机理。XPS分析结果表明,混合燃烧可促进硫化物（S5）向芳香族S（S4）转化;硫酸盐（S1）实际相对含量比计算值更早达到最大值,说明混合燃烧更易形成硫酸盐;XRD分析发现燃料中Ca元素是影响硫转化的主要矿物元素,其存在形式为CaCO₃,CaCO₃与SO₂反应生成CaSO₄可将SO₂保留于固相;部分CaSO₄可能会在燃烧后期被分解导致SO₂的二次生成;TG-MS实验结果表明混合燃烧可促进H₂S、CS₂、SO₃和C₄H₄S生成,抑制COS和SO₂生成。揭示了混合燃烧过程中氮的迁移转化机理。XPS分析结果表明,混合燃烧可促进燃烧前期吡啶酮（N-5）向吡啶（N-6）的转化;混合燃烧末期,充足的OH基团与N-6结合促进了吡啶酮的形成;拉曼光谱分析发现混合燃烧可大幅促进大芳香环结构的破裂过程;N-6在燃烧末期形成的C=O结构也会导致N-5相对含量的增加;TG-MS实验结果表明混合燃烧能促进NH₃生成,抑制HCN、NO和NO₂生成,且对NO₂的抑制作用最明显。更多还原

【Abstract】 With the development of industrialization and urbanization in our country,the output of sewage sludge and coal slime has been increasing year by year,which results in a large number of sewage sludge and coal slime urgently needed treatment.The co-combustion of sewage sludge and coal slime can achieve the purpose of reasonable and efficient treatment of both.However,due to their high sulfur and nitrogen content,it is necessary to study the migration and transformation of sulfur and nitrogen during co-combustion.To explore the release characteristics of sulfur and nitrogen oxides and the migration and transformation mechanism of sulfur and nitrogen during co-combustion,this paper mainly conducted the following studies:Sewage sludge and coal slime combustion experiments were carried out to study the combustion characteristics,SO₂ and NO release characteristics of co-combustion.The results showed that the co-combustion could accelerate the combustion process and shorten the combustion duration.When the temperature was higher than 900℃,two SO₂ release peaks appear.The NO conversion rate of sewage sludge increased gradually with the increase of temperature,and the maximum value of coal slime was reached at 800℃.When the temperature was 800℃and the sewage sludge mixing ratio is 20%,the formation of SO₂ and NO could be inhibited to the greatest extent.The migration and transformation mechanism of sulfur during co-combustion was studied.The results of XPS analysis showed that co-combustion could promote the conversion of sulfide（S5）to aromatic S（S4）.The actual relative content of sulfate（S1）reached the maximum earlier than the theoretical value,indicating that the co-combustion was more likely to form sulfate.XRD analysis showed that Ca element in fuel is the main mineral element that affected sulfur conversion,and its existing form is CaCO₃,which reacted with SO₂ to form CaSO₄,which could retain SO₂ in the solid phase.Some CaSO₄may be decomposed in the later stage of combustion,leading to the secondary release of SO₂.TG-MS experiment results show that co-combustion could promote the formation of H₂S,CS₂,SO₃ and C₄H₄S,and inhibited the formation of COS and SO₂.The migration and transformation mechanism of nitrogen during co-combustion was studied.The results of XPS analysis showed that co-combustion could promote the conversion of pyridone（N-5）to pyridine（N-6）at the early stage of combustion.At the end of co-combustion,sufficient OH groups combined with N-6 promoted the formation of pyridone.Raman spectrum analysis showed that co-combustion can greatly promote the structure breakdown process of large aromatic ring.The C=O structure formed by N-6 at the end of combustion also leaded to the increase of the relative content of N-5.TG-MS experiment results show that co-combustion could promote the formation of NH₃ and inhibited the formation of HCN,NO and NO₂,and the inhibition of NO₂ was the most obvious.更多还原