【作者】 赵宇；

【导师】 胡国新；

【作者基本信息】 上海交通大学 ， 工程热物理， 2014， 博士

【摘要】 目前国内外比较成熟的脱硫技术主要是湿法石灰石-石膏法及循环流化床半干法，但是随着现有电厂烟气脱硫设备运行数量的不断增加和规模的不断扩大，脱硫副产品产量的日益增加，其处理问题也日益变得突出。按照国家节能环保和循环经济发展的要求，理想的烟气脱硫技术应该是无废物产生、可再生循环利用并且无二次污染。所以，可回收硫资源的烟气脱硫技术正成为当前研究的热点和主要方向。而腐植酸钠法烟气脱硫技术正是由于具有无废物产生且无二次污染等特点使其有可能成为替代石灰石-石膏湿法脱硫的新技术之一，具有广阔的应用范围和良好的发展前景。此外，腐植酸钠来源广泛，价格便宜，脱硫后处理产物可用于肥料原料使其在烟气脱硫技术领域更具可行性。因此探索腐植酸钠复合吸收剂吸收二氧化硫的性能对腐植酸钠脱硫技术的进一步发展和应用具有重要的理论价值和现实意义。本文按照脱硫副产物资源化的目标对腐植酸钠复合吸收剂吸收二氧化硫及产物进行相关分析研究，根据实验结果研究了腐植酸钠复合吸收剂吸收二氧化硫的机理及产物后处理方法，为其今后能工业化应用提供理论基础。本文的主要内容包括以下几点：1、通过对腐植酸钠氨水复合吸收剂负载在α-氧化铝上并有二氧化氮同时存在的条件下吸收二氧化硫的研究，分析其过程化学反应机理与吸收产物成分，结果发现：在实验条件下二氧化氮的存在有利于负载腐植酸钠氨水复合吸收剂对二氧化硫的吸收，其吸收二氧化硫的最大效率可达98%以上，吸收二氧化氮的最大效率在80%左右，其主要产物为硫酸铵、亚硫酸铵和硝酸铵等。同时动力学实验结果表明，负载腐植酸钠氨水复合吸收剂同时吸收二氧化硫和二氧化氮时分为两个反应区段，即快速反应区段和慢速反应区段。在快速反应区段二氧化硫的分级数为0.291，而二氧化氮的分级数为0.464。在慢速反应区段则无论是二氧化硫还是二氧化氮，反应级数均为0。2、通过对污泥进行碱解制备出污泥腐植酸钠后，使用其作为吸收剂在鼓泡反应器内进行了吸收二氧化硫的实验研究，发现污泥腐植酸钠吸收剂对二氧化硫有较好的吸收效果，其吸收量可达0.037gSO2/gSHA-Na。在实验研究条件下，二氧化硫的浓度变化在整个吸收过程可以分为三段：急速下降段，近似水平段，最后经历缓慢升高段。与此同时，整个过程中吸收剂的pH值从最初的10.8开始变化，经历急速下降段、近似水平段的线性下降后在缓慢升高段保持不变，最后维持在约3.4。在通过对污泥腐植酸钠吸收剂与水（同体积）、氢氧化钠（同pH）的吸收比较后发现污泥腐植酸钠无论是吸收二氧化硫持续时间还是吸收效率均优于相比较的水与氢氧化钠。在改变不同工况条件后，得出不同入口二氧化硫浓度及温度对污泥腐植酸钠吸收剂吸收二氧化硫的吸收效率影响较小，但对其吸收持续时间则影响较大，入口浓度越高吸收持续时间越短，温度越高吸收持续时间越短，而有氧气存在的条件下污泥腐植酸钠吸收剂吸收二氧化硫的最大吸收效率高但吸收持续时间则较没有氧气存在的条件下要短。通过对污泥腐植酸钠吸收剂吸收二氧化硫的产物进行分析得到其主要成分是腐植酸、蛋白质、糖类、脂肪及其他一些小分子有机酸等，可以用作制备腐植酸液肥原料，实现污泥资源化利用。3、通过使用稀硫酸对腐植酸钠脱硫产物的模型化合物腐植酸在有季铵盐相转移催化剂的条件下的磺化实验研究，得到季铵盐相转移催化剂中四丁基溴化铵的催化效果最好，四丙基溴化铵次之，四乙基溴化铵再次之，而四甲基溴化铵则最差。在四丁基溴化铵为相转移催化剂条件下硫酸浓度为0.98%时就可以与硫酸形成离子对而将其转移到有机相中使腐植酸磺化。当跟对照组无超声作用相比较，发现增加超声作用后腐植酸的磺化度得到了提高，并且超声功率越大，则磺化效果越明显，但是当超声功率增大到一定程度后腐植酸的磺化度变化就不再明显增加，而增加超声作用时间则有助于腐植酸的磺化度提高。通过正交试验设计得到：用相转移催化剂四丁基溴化铵的条件下进行针对磺化腐植酸的优选方案为超声功率为120W，超声作用时间为30分钟，添加相转移催化剂四丁基溴化铵为0.02g，温度控制在85℃为佳，此时磺化度为0.517mg-S/g-HA。4、通过对腐植酸钠/[CPL][TBAB]复合吸收剂吸收二氧化硫的过程研究，得出在利用腐植酸钠/[CPL][TBAB]复合吸收剂吸收二氧化硫的吸收过程中，来自混合气体中的二氧化硫首先溶入吸收剂溶液发生溶解平衡和离子平衡而生成HSO3-、SO32-、H+等离子，然后与腐植酸钠所带的的羧基和羟基基团发生反应生成难溶的腐植酸后，亚硫酸氢钠作为亲核试剂与腐植酸片断上的苯环可以发生迈克尔加成反应，从而使腐植酸部分磺化成磺化腐植酸。并且通过计算吸收增强因子判断出：腐植酸钠/[CPL][TBAB]复合吸收剂吸收二氧化硫的吸收反应控制步骤为扩散控制，整个吸收曲线过程可以分成三个阶段，其中第一和第二阶段中φ>6.9×1010因此是由气侧传质阻力控制的化学吸收过程，而在第三阶段φ <50则为气-液侧传质阻力共同控制的过程，此时体系已经不能完全吸收二氧化硫。5、通过对腐植酸钠/[CPL][TBAB]复合吸收剂循环吸收二氧化硫的研究，分别考察了循环次数对复合吸收剂吸收二氧化硫效率、吸收量以及复合吸收剂吸收前后pH的影响，得出在使用腐植酸钠/[CPL][TBAB]复合吸收剂吸收二氧化硫工艺时为了得到较高的效率则需要根据工艺要求在排出产物的同时及时补充更换新鲜复合吸收剂以维持较高的吸收效率，而且随着循环次数的增加复合吸收剂吸收二氧化硫的吸收量在逐步降低，这是与复合吸收剂循环使用时的初始pH值的降低相一致。随后在此基础上对复合吸收剂循环吸收二氧化硫的产物分别进行了FTIR、XRD、XPS及离子色谱分析等，得出产物主要是磺化腐植酸及硫酸钠，在磺化腐植酸中硫元素主要是以磺酸R-SO3H形式存在于吸收产物中，氧元素以O–C O与R-SO3H为主要存在形式，碳元素以C-C、C=O与O–C O为主要存在形式。更多还原

【Abstract】 For the purpose of conducting desulfurization, the wet limestone-gypsum methodand circulating fluidized bed half-dry method are widely used domestically andinternationally. Though mature in practicing, they are not ideal for energy saving andcircular economy, and has become less adequate as the scale of flue gasdesulfurization equipment is enlarging and the by-product is not cyclic utilization.So the technology, which the by-product can be recycled, is becoming a hot spot incurrent research and the main direction on flue gas desulfurization. The method thatuses sodium humate in flue gas desulfurization technology is expected to become avaluable desulfurization technology in our country in the future as it is free fromcreating secondary pollution. Sodium humate desulfurization technology, after yearsof domestic and foreign research and development, will be further developed. Thefeasibility of this technology, the construction and operation in economy, and thedesulfurization by-products utilization, need to be further studied. The study on thesodium humate compound absorbent has a considerable theoretical and practicalsignificance for sodium humate desulfurization technology. In this paper, accordingto the goal of resource recovery the research in sodium humate composite absorbentto absorb sulfur dioxidehas been done. With the result of the experiment, themechanism of sodium humate compound absorbent to absorb sulfur dioxide whichprovides the theoretical foundation for its industrial application in the future isstudied. The main contents and results are summarized as follows:1. Sodium humate and ammonia loaded on α-alumina used to absorb sulfurdioxide when the simulated flue gas has nitrogen dioxide. Under this condition, thechemical reaction mechanism and absorption process have been analyzed. It is foundthat the presence of nitrogen dioxide in experimental conditions is conducive forabsorbing sulfur dioxide and the sulfur dioxide absorption efficiency can reachabove98%while the nitrogen dioxide absorption efficiency is about80%. The mainproducts are ammonium sulfate, ammonium sulfate and ammonium nitrate, etc.Through analyzing, the kinetics experimental results show that the desulfurizing process, with sodium humate and ammonia loaded on α-alumina used to absorbsulfur dioxide, is divided into two reaction sections, namely the fast reaction sectionand the slow reaction.The order of reaction on sulfur dioxide is0.291in fast reactionextents, and the order of reaction on nitrogen dioxide is0.464. Meanwhile, in theslow reaction section, either sulfur dioxide or nitrogen dioxide, the order of reactionis0.2. The sludge sodium humate absorbent had been prepared from sludge. Theexperimental research has been conducted about the absorbing process of sulfurdioxide in bubbling reactor used the sludge sodium humate absorbent. It is foundthat sodium humate sludge absorbent has better absorption effect for sulphur dioxidethan water, sodium hydroxide. Under the condition of experiment research, theconcentration of sulfur dioxide changes in the absorption process can be divided intothree sections: a rapid decline section, an approximate horizontal section, and a slowrise section. Meanwhile the pH value of sludge sodium humate absorbent in thisprocess changes from the original10.8to a constant about3.4. It is concluded thatdifferent inlet sulfur dioxide concentration and temperature on sludge sodiumhumate absorbent to absorb sulfur dioxide have little effect on the absorptionefficiency and have a significant effect on the absorption duration. The higher theinlet concentration is, the shorter the duration is. With the presence of oxygen theabsorption efficiency of sludge sodium humate absorbent on sulfur dioxide is higherbut the duration is shorter than without the presence of oxygen. Through analyze theproduct, it can be concluded that the main ingredient in product is humic acid,protein, carbohydrate, fat and other small molecule organic acids, etc.3. Phase-transfer catalysis (PTC) is a synthetic organic method and manufacturingprocess technology that is applied successfully in a wide range of organic reactions.A sulfuric acid/humic acid (HA) system with quaternary ammonium salts asphase-transfer catalysts were employed in the sulfonation of humic acid. Fourquaternary ammonium salts catalytic systems with ultrasound were carried out,tetrabutyl ammonium bromide behaved as the optimum active catalyst, and thesulfonation degree was above0.407mg-S/g-HA. In order to attain a highersulfonation degree of humic acid, orthogonal experiments of dilute sulfuric acidsulfonated humic acid system with tetrabutyl ammonium bromide as phase-transfercatalysts were carried out in the flask to investigate the effect of main factors, namely, temperature, ultrasound power, ultrasound time and catalyst dose onsulfonation degree. The results of orthogonal experiments showed that the optimalcondition for humic acid sulfonation should be A4B4C1D1, namely, temperature,ultrasound power density, ultrasound time and catalyst dose were85°C,12W ml-1,30min and0.02g, respectively. The verification experiments were carried out inflasks at the corresponding parameters. The results of verification experiments in theshaking flasks showed that sulfonation degree was0.517mg-S/g-HA. Theconclusion in the research would be beneficial for application of dilute sulfuric acidsulfonated humic acid.4. The study on the sodium humate/[CPL][TBAB] composite absorbent in thesulfur dioxide absorption process has been conducted. It is found that sulfur dioxidefrom the mixed gas first dissolve in the absorbent occurring dissolving balance andion balance in the process used sodium humate/[CPL][TBAB] composite absorbent.HSO3-, SO32-and H+generated in this process. And then H+react with carboxyl andhydroxyl groups to generate the undissolved humic acid, sodium bisulfite asnucleophilic reagent react with fragments of humic acid on the benzene ring asMichael addition reaction, which makes part of humic acid into sulfonated humicacid. The whole process of absorption curve can be divided into three stages,including the first and second stage is controlled by the gas side mass transferresistance of chemical absorption process, while in the third stage is common controlprocess for gas-liquid mass transfer. The system has not fully absorbed sulfurdioxide at the third stage.5. By means of the research of sodium humate/[CPL][TBAB] compoundabsorbent for circulation absorption of sulfur dioxide, respectively investigates thecycles of composite absorbent to absorb sulfur dioxide efficiency, absorption and thepH of composite absorbent absorption before and after the absorption. It isconcluded that the fresh composite absorbent should be supply timely to replace theused absorbent in order to maintain higher absorption efficiency. With the increase ofcycling times the amount of compound absorbent to absorb sulfur dioxide ingradually reduce, when it is used with the composite absorber cycle, lower initial pHvalue of consistent. Then on this basis, the product of this process have been testedrespectively by the FTIR, XRD, XPS and ion chromatographic analysis, etc..Products are mainly consists of sodium sulfate and sulfonated humic acid and sulfur element in sulfonated humic acid mainly exists in the form of sulfonic acid R-SO3Hin absorption products, oxygen element in the form of sulfonic acid R-SO3H andO–C O, carbon element in the form of C-C, C=O and O–C O.更多还原