【作者】 莫建松；

【导师】 吴忠标；

【作者基本信息】 浙江大学 ， 环境工程， 2006， 博士

【摘要】 本文首先分析了我国的烟气脱硫技术现状及应用情况，指出我国烟气脱硫中存在的和潜在的问题，特别指出双碱法烟气脱硫工艺中存在的可靠性问题，如结垢、堵塞。通过分析结垢成因，分别研究了共沉淀、抑制氧化和晶种诱导结晶等方法来提高系统的可靠性。同时，通过工艺革新，采用浓碱双碱法替代稀碱双碱法，提高了系统的可靠性、并克服了稀碱双碱法回流量大、再生池和沉淀池占地面积大的缺陷。此外，提出了用一个综合影响因子ε表达的浓碱双碱法脱硫效率模型，该模型可用于工艺参数优化、指导工艺设计。 低浓度硫酸钙和亚硫酸钙混和溶液的共沉淀混合实验研究表明，硫酸根离子的存在明显降低了亚硫酸根离子的浓度，提高了溶液中的钙离子平衡浓度，而增加亚硫酸根离子浓度可以有效的降低钙离子浓度，有必要抑制体系中亚硫酸根离子的氧化。研究发现，亚硫酸钙和硫酸钙的混和溶液发生了共沉淀现象，并提出了适用于共沉淀的溶度积计算公式。 稀碱双碱法体系中，亚硫酸盐的氧化导致系统的脱硫效率降低，同时提高了系统的硫酸根和钙离子浓度，容易导致结垢，降低系统的可靠性。本文引入硫代硫酸钠作为氧化抑制剂对均相脱硫体系的抑制氧化进行研究，考察抑制剂浓度、pH值、催化剂和温度对氧化速率的影响。同时探讨了硫代硫酸根离子抑制氧化的机理，得到了抑制氧化时的反应速率表达式、反应活化能和抑制剂的消化速率。 在稀碱双碱法工艺的再生池后增加结晶池，或在再生池内直接添加晶种的方式诱导结晶，有效的缩短硫酸钙结晶的生长期，迅速达到平衡，避免过饱和溶液进入吸收系统，预防结垢。实验研究了晶种浓度、粒径、pH值对结晶过程的影响，得到了硫酸钙的结晶反应级数和总反应速率常数K_T。同时发现，硫酸钙过饱和溶液的诱导结晶过程的主要影响因素是单位体积内的晶种表面积S/V。 浓碱双碱法工艺研究发现，增加钠离子浓度不仅明显提高脱硫效率，还增加系统的缓冲能力，减小液气比和降低吸收塔进出口pH差值，同时大大更多还原

【Abstract】 In this dissertation, the current state of the flue gas desulfurization (FGD) technology and its application was analyzed. And then the current and future problem of domestic FGD, especially the problem of reliability and disadvantage of dual-alkali FGD system, had been indicated. The reliability of dual-alkali FGD system included scaling in the scrubber and plugging in the pipeline. Therefore, the reliability of dual-alkali FGD system could be improved by studying co-precipitation of calcium sulfite and calcium sulfate, oxidation inhibition and adding seed crystal to the regeneration tank. On the other hand, by using concentrated alkali dual-alkali FGD system instead of diluted alkali dual-alkali FGD system, the reliability of dual-alkali FGD system could be improved. Furthermore, desulfurization efficiency model of concentrated alkali dual-alkali FGD system with a dimensionless factor ε was proposed, which can be used to guide the design and optimize the operations.Experimental results of precipitation of the mixed solution of low concentration calcium sulfate and calcium sulfite indicated that the present of sulfate ion would lead to a great reduction of the concentration of sulfite, which then resulted in an increasing in the concentration of calcium ion. Hence it is necessary to inhibit the oxidation of sulfite ion to prevent the scaling problem.. It was found that co-precipitation phenomenon of calcium sulfite and calcium sulfate happened in the mixed solution of diluted calcium sulfate and calcium sulfite. And a new dissolution equilibrium equation had been presented for this co-precipitation system.In the diluted alkali dual-alkali FGD system, the oxidation of sulfite would lead to low desulfurization efficiency and the increase of the concentration of calcium and sulfate ion. Consequentially, this system was easy to scaling, which would result in a lower reliability. Sodium thiosulfate was introduced to the更多还原