Knowledge Management System Of Institute of process engineering,CAS
我国烷基化油生产工艺中以浓硫酸作为催化剂的烷基化生产装置占到85%以上，每年约产生200~300万吨烷基化废硫酸。烷基化废硫酸含有多达几百种难以去除的有机物，处理难度大，是一种典型危险废物。烷基化废硫酸如不能得到妥善处理，不仅会对环境造成污染，还会造成大量硫资源浪费。本文基于研究团队在废硫酸处理方面的经验积累，提出了拟固相反应新概念，并在此基础上研发了烷基化废硫酸资源化利用新工艺。本文系统开展了拟固相反应工艺研究，煅烧脱除有机物工艺及动力学研究，浸取结晶制备七水硫酸镁工艺研究以及全流程经济性评价研究，形成以湿法浸出、火法煅烧、无机化学品制备和能量梯级利用的一体化集成技术，为烷基化废硫酸的资源化利用提供了新途径。本文的主要研究内容及研究结论如下：（1）研究得出烷基化废硫酸与轻烧氧化镁拟固相反应适宜工艺参数：酸矿质量比(2.45~2.47):1，加酸时间20~25 min，陈化时间7.5~12.5 min，在此条件下，废硫酸利用率可达90%以上。光谱分析结果表明，拟固相反应产物主要是以MgSO4·H2O形态存在，而且颗粒形貌具有多种的结构特征，以层状或片状结构为主。拟固相反应机理初步探究表明，一部分有机物会与硫酸发生聚合和炭化反应，生成具有非极性的炭，一部分有机物会与硫酸发生氧化还原反应，生成SO2和CO2。（2）拟固相反应物料的煅烧特性研究表明，在空气煅烧气氛下，有机物主要是与氧发生化学反应，生成H2O和CO2，最大反应速率峰出现在450~460℃，总失重约19%，硫酸镁几乎不损失；在氮气煅烧气氛下，有机物与硫酸镁发生氧化还原反应，生成MgO，SO2和CO2，最大反应速率峰出现在750℃左右，总失重约35%，硫酸镁损失较大。煅烧过程动力学研究表明，拟合反应机理函数f(α)与Avrami-Erofeev方程机理函数最为接近，反应级数n=3，煅烧过程平均活化能E为127.1 kJ/mol，频率因子A为3.39×1010。研究得出物料煅烧最优工艺参数：煅烧温度为550~600℃，煅烧时间为60 min，煅烧方式为动态煅烧。在此条件下，煅烧产物中无水MgSO4占90.33%，有机物脱除较为彻底，硫酸镁收率可达94%以上。（3）研究得出浸取最优工艺参数：浸取温度为80~90℃，浸取时间为10 min，液固投料比2.6:1；浸取溶液具有自除杂特性，可制得纯净的硫酸镁结晶液；研究得出最优结晶工艺参数：结晶液pH=5~7，结晶温度10~15℃，结晶时间为6~8h，在此条件下，结晶物的形貌最优，结晶收率最高，且最为经济。本文制备的七水硫酸镁产品各项指标均符合行业标准HG/T2680-2017（工业硫酸镁）指标要求，品质优良。（4）对烷基化废硫酸制备七水硫酸镁工艺流程进行了物料衡算，热量梯级利用分析和经济性评价，研究表明，本工艺具有较强的竞争优势，具备显著的环境效益和一定的经济效益，工业应用前景广阔。;Alkylation process units with concentrated sulfuric acid as catalyst in alkylated oil production technology in our country account for more than 85%, about 2~3 million tons of alkylation spent sulfuric acid is produced each year. Alkylation spent sulfuric acid contains more than 200 kinds of organics which are difficult to remove, it is difficult to deal with and is a typical hazardous waste. If alkylation spent sulfuric acid can’t be treated properly, it will not only pollute the environment, but also cause the waste of sulfur resources. In this paper, based on the research accumulation on spent sulfuric acid treatment of our research team, a new concept of quasi-solid reaction were presented，and on this basis, a new technology of resource utilization of alkylation spet sulfuric acid were developed. In this article, the study on the quasi-solid reaction of alkylation spent sulfuric acid with light burned magnesium oxide, the study on the process and kinetic of removal of organics by calcination, the preparation of magnesium sulfate heptahydrate by extraction and crystallization, and the economic evaluation of the whole process were carried out systematically, the integrated technology of wet-leaching, fire-calcination, inorganic chemical preparation and cascade utilization of energy was formed, and the technology provided a new way for the resource utilization of spent alkylation sulfuric acid. The main research contents and conclusions of this paper are as follows:(1) The appropriate process parameters of the quasi-solid reaction between alkylation spent sulfuric acid and light burned magnesium oxide were obtained as follows: the acid ore mass ratio is (2.45~2.47):1, the acid addition time is 20~25 mins, the aging time is 7.5~12.5 mins, under these conditions, the utilization of spent sulfuric acid is more than 90%. Spectral analysis results show that MgSO4·H2O was the main form of the quasi-solid reaction product, and the particle morphology had a variety of structural characteristics, mainly layered or lamellar structure. Preliminary investigation of the mechanism of quasi-solid reaction shows that some organics will undergo polymerization and carbonization with sulfuric acid to form non-polar carbon, while some organics will undergo REDOX reaction with sulfuric acid to form SO2 and CO2.(2) The study on the calcination characteristics of the quasi-solid reaction material shows that, under air atmosphere calcination, organics mainly react with oxygen to form H2O and CO2, the maximum reaction rate peaks occur at 450~460℃, and the total weight loss is about 19%, and magnesium sulfate is almost never lost; under nitrogen atmosphere calcination, REDOX reaction between organics and magnesium sulfate is happened to produce MgO, SO2 and CO2, the maximum reaction rate peaks occur at about 750℃, the total weight loss is about 35%, and the loss of magnesium sulfate is bigger. The kinetic study of the calcination process shows that the fitting reaction mechanism function f(α) is closest to the mechanism function of Avrami-Erofeev equation, and the reaction order n=3, the average activation energy of the calcination process is 127.1 kJ/mol, and the frequency factor is 3.39×1010. The optimum calcination process parameters were obtained as follows: the calcination temperature is 550~600℃, the calcination time is 60 mins, and the calcination method is dynamic calcination. Under these conditions, The anhydrous MgSO4 accounts for 90.33% of the calcination products, the organics were removed completely, and the yield of magnesium sulfate can reach more than 94%.(3) The optimum process parameters of extraction were obtained: the extraction temperature is 80~90℃, the extraction time is 10 mins, the liquid-solid ratio is 2.6:1, the extraction solution has the characteristic of self - impurity removal and can produce pure magnesium sulfate crystallization solution. The optimum crystallization parameters were obtained：the crystallization solution pH is 5~7, the crystallization temperature is 10~15℃, the crystallization time is 6~8h, under these conditions, the crystal has the best morphology, the highest crystallization rate and the most economical. The various indicators of the magnesium sulfate heptahydrate products produced in this paper meet all the requirements of the industry standard HG/T2680-2017 (industrial magnesium sulfate), and the quality is excellent.(4) The material balance, the heat cascade utilization analysis and the economic benefit analysis of the process flow of alkylation spent sulfuric acid to prepare heptahydrate magnesium sulfate were carried out and the researches show that, the technology has strong competitive advantages, significant environmental benefits and certain economic benefits, and it has a broad prospect for industrial application.
|安学斌. 烷基化废硫酸制备硫酸镁的新工艺研究[D]. 中国科学院大学,2020.|
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