【作者】 崔宝臣；

【导师】 崔福义；

【作者基本信息】 哈尔滨工业大学 ， 市政工程， 2009， 博士

【摘要】 含油污泥处理一直是困扰油田企业而急需解决的问题之一,也是世界性难题,传统的含油污泥处理技术面临诸多问题,研究开发新型含油污泥无害化处理新技术、新方法成为广泛关注的课题。超临界水氧化能够将有毒难降解有机物迅速、彻底地分解成H2O和CO2等无机小分子,是一种新兴的有机废水废物处理技术。论文以H2O2为氧化剂,采用间歇釜式实验装置,创新性地进行了含油污泥的超临界水氧化、催化超临界水氧化和超临界水共氧化实验研究,旨在为含油污泥无害化处理开辟一条新的可循之路。论文首次研究了超临界水氧化含油污泥的效能,考察了超临界水氧化含油污泥过程中的各种影响因素,并对氧化后尾气、液相产物和固体残渣组成进行了分析,研究发现,随着反应时间和反应温度的增加,水中含油去除率、TOC转化率、COD去除率和CO2收率均提高;CH3COOH和CO为超临界水氧化含油污泥的中间产物,CO2为氧化的最终产物;CH3COOH的收率随反应温度提高而降低,CO收率随反应温度提高而增加;压力对COD去除率的影响较小;过氧化氢不预热直接加入时的氧化效率高,过氧量在217%以上对COD去除率几乎没有影响;COD去除率随着初始COD增加而提高;pH为10时COD去除率最高。含油污泥经过超临界水氧化处理后,流出液的可生化降解性明显提高。在450℃下氧化反应10min后,出水清澈透明,COD去除率达到92%。反应后尾气除含有2.64%的CO外没产生其他有害气体成分。处理之后的剩余固体残渣中有机质含量约为0.97wt%,残渣中重金属含量远低于《农用污泥污染物控制标准》中规定的含量限值以及《土壤环境质量标准》的三级指标。论文对超临界水氧化含油污泥反应路径及反应动力学进行了比较系统地研究。以幂指数方程描述了超临界水氧化含油污泥反应动力学规律,结果表明,氧化剂H2O2和COD的反应级数分别为0和1.405,反应活化能和指前因子分别为213.13±1.33 kJ/mol和8.99×1014 (mol·L–1) -0.405·s-1。超临界水氧化含油污泥的反应路径为:含油污泥首先分解成带有共轭双键的不饱和醛和酮以及羧酸,然后经过系列反应生成中间控制产物CH3COOH和CO,最终产物为CO2和H2O。建立了包括含油污泥、CO、CH3COOH和CO2在内的四集总反应网络动力学模型,回归估算了集总反应网络模型中的6个反应速率常数和活化能。四集总反应网络动力学模型能较好地描述超临界水氧化含油污泥的反应规律。论文研究发现碱、过渡金属离子和过渡金属氧化物三类催化剂对超临界水氧化含油污泥具有催化作用。结果表明,添加Na2CO3和NaHCO3均有利于含油污泥COD的去除,添加NaHCO3比Na2CO3更有优势;添加NaHCO3的最佳浓度为100mg/L。低温下NaHCO3催化活性比在高温下好,在高温下添加NaHCO3起到抑制作用。添加NaHCO3降低了中间产物CO收率和醋酸收率,并有利于控制反应体系的pH值。研究发现金属离子催化剂对超临界水氧化含油污泥具有较好的催化活性。各种金属盐催化剂的催化活性由高到低的顺序为:MnSO4>Mn(NO3)2 > CuSO4 > Cu(NO3)2 > Fe2(SO4)3 > CoSO4 > Fe(NO3)3 > Ni(NO3)2 >NiSO4。在金属离子Mn2+和Cu2+催化下,随着反应时间的增加COD去除率提高。当Mn2+和Cu2+浓度高于50mg/L时,增加金属离子浓度对催化活性的提高作用不明显。体相V2O5、MnO2、TiO2、CuO、ZrO2和ZnO的催化活性不如负载型的MnO2/γ-Al2O3和CuO/γ-Al2O3的催化活性高。催化剂CuO-MnO2/γ-Al2O3的催化活性较好,CuO和MnO2之间存在协同作用,最佳Cu:Mn原子比为1:10。对于CuO-MnO2/γ-Al2O3和MnO2/γ-Al2O3催化剂,COD去除率最高分别达到99.2%和99.1%。体系pH对催化活性具有一定影响。使用过的催化剂活性下降明显。论文创新性地提出采用超临界水共氧化技术处理含油污泥,考察了添加简单易氧化化合物对超临界水氧化含油污泥的促进作用,研究发现,添加甲醛对含油污泥的转化具有明显的促进作用,在最佳反应条件下,COD去除率可达99.0%。更多还原

【Abstract】 The treatment and disposal of oily sludge represent major challenges for petroleum industries and are difficult problems in the world. Several conventional technologies for oily sludge treatment are confronted with many problems. It has been attracted widely attention for developing novel methods for harmless treatment of oily sludge. Supercritical water oxidation is a promising organic wastewater or wastes treatment process which can rapidly and perfectly convert toxic and refractory organics into mineral products of CO2 and H2O and so on. The treatment of oily sludge by means of supercritical water oxidation, catalytic supercritical water oxidation and supercritical water co-oxidation were performed innovatively using H2O2 as oxidant in a batch reactor, focusing on opening up a new way that can be followed for harmless treatment of oily sludge.It is the first time that effectiveness of oxidation of oily sludge in supercritical water was studied. Effect of reaction parameters on supercritical water oxidation of oily sludge was investigated. The analysis of the samples like exhaust gas, liquid effluent, and solid residues was performed. It was found that oil removal rate, TOC conversion, COD removal rate and carbon dioxide yield increase as the reaction time and temperature increase. Oxidation of oily sludge can produce final product of carbon dioxide and intermediate products of carbon monoxide and acetic acid in supercritical water. Intermediate acetic acid yields decreased with the increase of temperature, on the contrary, carbon monoxide yields increased with the increase of temperature. Pressure has no remarkable affect on the reaction. H2O2 is more effective by the direct addition of H2O2 without preheating. The rate of oxidation is independent of oxygen feed concentration above an O2 excess of 217%. COD removal rate increases as the initial COD increase. The highest COD removal rate is reached at pH of 10. Biodegradability of liduid effluents was improved obviously after treatment of oily sludge with supercritical water oxidation. The COD removal rate of 92% can be reached at reaction temperatures of 450℃in 10 min. The liquid effluent is clear and transparent. Gas does not contain other hazardous compounds except for CO of 2.64%. Organic matter content in solid residues is about 0.97wt %. Contents of heavy metals in solid residues are lower than limit values in“Control standards for pollutants in sludges from agricultural use”and third grade indexes in“Environmental quality standard for soils”.The kinetics and possible pathways for supercritical water oxidation of oily sludge were studied systematically. The kinetics of supercritical water oxidation of oily sludge can be described by a global power-law rate expression. The results revealed that the reaction orders for oxidant of H2O2 and on COD are 0 and 1.405 respectively. The activation energy and the resulting pre-exponential factor are 213.13±1.33 kJ/mol and 8.99×1014 (mol·L–1) -0.405·s-1 respectively. The possible pathways for supercritical water oxidation of oily sludge were as follow: the oily sludge is decomposed firstly to acetaldehyde, acetone with conjugated double bond and carboxylic acids. The intermediate products of carbon monoxide and acetic acid may have been formed from a series of oxidation of the decomposed matter, then the final products of carbon dioxide and water are produced. Four-lumped kinetics model, comprising of oily sludge, carbon monoxide, acetic acid and carbon dioxide, was established. Six reaction rate constants and the activation energies of the model were determinated on the basis of experimental results. The results showed that the four-lumped kinetics model is reasonable.It was found that three catalysts containing alkali, transitional metal ions and transitional metal oxides could catalyze oxidation of oily sludge in supercritical water. The results showed that addition of Na2CO3 and NaHCO3 is propitious to COD removal from oily sludge in supercritical water oxidation. The addition of NaHCO3 is superior to that of Na2CO3. Optimal concentration of NaHCO3 is 100mg/L. Catalytic activity of NaHCO3 is higher at lower temperature than that at higher temperature. The addition of NaHCO3 appears in inhibition at higher temperature. The addition of NaHCO3 results in a decrease in yields of intermediate products of carbon monoxide and acetic acid, and is propitious to control of pH. It was found that the transitional metal ions catalysts show a significant activity for supercritical water oxidation of oily sludge. The overall order of catalytic activity of transitional metal salts is MnSO4 > Mn(NO3)2 > CuSO4 > Cu(NO3)2 > Fe2(SO4)3 > CoSO4 > Fe(NO3)3 >Ni(NO3)2>NiSO4. COD removal rate increases as the reaction time increases in the presence of Mn2+ and Cu2+. Increase in concentrations of metal ions results in no remakble incresing in catalytic activity when the concentrations of Mn2+ and Cu2+is above 50mg/L. MnO2/γ-Al2O3 and CuO/γ-Al2O3 present an advantage of catalytic activity over bulk phase transitional metal oxides such as V2O5, MnO2, TiO2, CuO, ZrO2 and ZnO. Catalytic activity of CuO-MnO2/γ-Al2O3 is higher due to a synergic action between CuO and MnO2. Optimum Cu:Mn atomic ratio is 1:10. COD removal rates are respectively 99.2% and 99.1% over MnO2/γ-Al2O3 and CuO/γ-Al2O3. Initial pH has an impact on catalytic activity of catalyts. Catalytic activity of the used catalysts decreases significantly.This paper proposed innovatively the idea that oily sludge was treated using supercritical water co-oxidation. The enhancements of labile, reactive species in supercriticai water oxidation of oily sludge were investigated. It was found that the addition of formaldehyde enhances significantly conversion of oily sludge. COD removal rate can reach 99.0% under the best condition.更多还原