【作者】 李佳；

【导师】 郎春燕； 周如金；

【作者基本信息】 成都理工大学 ， 化学工程， 2016， 硕士

【摘要】 随着乙烯需求的增长以及原油的日趋重质化和劣质化,重质馏分油用作乙烯裂解原料的比例越来越大,重质馏分油中硫等杂质对环境安全、产品质量、管道及设备腐蚀等问题日趋突出,严重影响着乙烯裂解原料的加工过程。硫化物作为乙烯裂解原料的主要杂质之一,其性质和含量的差异决定了其在不同产品中的富集量和分配量的大小以及对环境的污染程度和对设备的腐蚀程度。此外,硫化合物的形态不同,其对生产的影响也存在明显的差异。因此,研究乙烯裂解料与下游产品中硫化物的含量及赋存形态具有十分重要的意义。为了拓宽乙烯原料来源,减少生产成本,提高石油化工产品市场竞争力,茂名石化分公司主要以石脑油和加氢裂化尾油为原料制取乙烯。由于原油的劣质化,导致石脑油和加氢裂化尾油等裂解原料性质变差,从而产生了炉管容易结焦、设备腐蚀、产品质量变差等问题。本课题针对乙烯装置下游产物C₅馏分硫含量超标问题展开研究,以重质石脑油为研究对象,在自行设计的实验室模拟裂解装置上进行一系列裂解试验,对比分析了原料及裂解产物C₅馏分中硫化物含量与形态分布情况,为解决C₅馏分因硫含量高而导致产品不合格的问题提供依据。本文涉及的主要工作及结论有:根据乙烯工艺生产的特征,综合考虑了停留时间、裂解炉进口及出口温度、急冷所需传热面积等工艺参数以及原料的适用性,优化设计并加工制造了一套结构简单、成本低廉、适宜多种裂解原料的实验室模拟裂解常压实验装置。试用结果表明,该装置不仅能有效避免石脑油、尾油裂解造成管道堵塞、冷凝效果差、结焦严重等问题,还能进行烧焦实验,以研究原料的结焦规律。在实验室模拟裂解中试装置上对不同裂解温度、不同水油质量比和不同停留时间条件下的石脑油进行了一系列模拟裂解实验,建立了裂解气各组分的分析方法,计算了裂解气各组分在裂解产物中的百分含量。比较不同裂解条件下乙烯、丙烯及丁二烯等主要裂解产物的收率情况,得到重质石脑油模拟裂解的最适宜条件:裂解温度860℃、水油质量比0.79、停留时间0.32s。采用电位滴定仪及硫氮分析仪对重质石脑油及其裂解产物C₅馏分中硫醇硫、硫醚硫、二硫化物硫、噻吩类硫以及总硫含量进行了测定;并以GC-MS技术分析了预处理后的石脑油及其裂解产物C₅馏分中硫化物的赋存形态。研究发现:重质石脑油中硫化合物含量较高且形态极其复杂,其类型硫含量顺序为:噻吩硫>硫醚硫>硫醇硫>二硫化物,其中噻吩硫百分含量达60%,主要存在形态为甲基噻吩和二甲基噻吩;硫醚类硫百分含量为31%左右,可能存在形态为甲基乙基硫醚、乙基丙基硫醚、甲基叔丁基硫醚等;硫醇硫主要为含有3-6个碳原子的同分异构体,百分含量仅占5.1%;石脑油中总硫的10.33%会进入C₅馏分。C₅馏分中噻吩硫占绝大部分,其百分含量高达84%,噻吩硫主要存在形态为噻吩和二甲基噻吩等。更多还原

【Abstract】 With the growth of domestic demand for ethylene and increasingly heavy and inferior crude oil,the proportion of heavy distillate used as cracking raw material is becoming bigger and bigger.As a result,the problems of environmental safety and production quality and equipment corrosion caused by sulfur impurities in heavy distillate occured undoubtedly,which would seriously affect the pyrolysis process of raw materials of ethylene.Acted as some kind of the main impurities in cracking raw materials,sulfer compounds with different forms have different properties and composition,which determined the amount of enrichment and allocation in different product as well as the degree of pollution to the environment and corrosion of equipment.Moreover,the influences of sulfides on production varied with various species.Therefore,it is significant to study on conversion and distribution of sulfur with different forms in the pyrolysis process of ethylene cracking materials and its downstream product.In order to broaden the cracking raw material source,reduce the production cost and improve market competitive power,petrochemical company of Mao Ming mainly used naphtha and hydrocracking tail oil to make ethylene.Due to the poor properties of ethylene cracking material resulted from inferior change of crude oil,it came to a series of problems such as furnace tube coking severely and equipment corrosion and poor product quality.Based on the problem that sulfur concentration of C₅ distillate in the downstream product of ethylene plant exceeded the standard value,a series of cracking experiments with heavy naphtha as the research object were carried out in laboratory simulated cracking unit designed by ourselves.The distribution of sulfur compounds in the cracking raw material of naphtha and the pyrolysis product of C₅ distillate were studied and discussed to provide basis for solving the issue that the C₅ distillate was unqualified because of high sulfur content.Some of the principal work and conclusions are listed below.According to the characters of ethylene process,the process parameters including the residence time,inlet and outlet temperature of cracking furnace and the heat trans-fer area required in the process of rapid cooling as well as the applicability of the raw materials were taken into consideration before a set of laboratory simulated cracking atmospheric pressure experiment device with simple structure,low cost and feasibility for a variety of raw materials was designed and optimized.Trial results showed that the device not only could effectively avoid blockage,poor condensation,serious cooking problem and so on when naphtha or tail oil was cracked,but also could carry out burning experiments to study the coking regulation of raw materials.A series of simulated pyrolysis experiment of heavy naphtha were carried out on laboratory simulated cracking plant in different conditions by changing pyrolysis temperature,quality ratio of w/o or residence time.Analysis and calculated methods were established for cracking gas component in the pyrolysis products.By comparing the yields of ethylene,propylene and butadiene in different conditions,the optimal conditions of heavy naphtha cracking with cracking temperature of 860⁰C,quality ratio of water and oil of 0.79 and the residence time of 0.32s were obtained.Sulfur contents of thiol compounds,disulfides,sulfoether compounds and thiophenic compounds and total sulfur contents in heavy naphtha and its cracking product of C₅ distillate were determined by using potentiometric titration instrument and sulfur and nitrogen analyzer,respectively.Speciation of sulfides of pretreated naphtha and C₅ distillate were identified by using gas chromatography with mass spectrometry detection.The results showed that the total sulfur in heavy naphtha had a high content and speciation of sulfides was very complex.The contents of various sulfides were listed in the order of thiophenic sulfur>sulfoether sulfur>thiol sulfur>disulfides.Among of them,the thiophenic sulfur accounted for 60%and its main existing forms were methyl thiophene and dimethyl thiophene;the sulfoeher sulfur was approximately 31%whose possible forms were methyl ethyl ether,methyl tert-butyl ether,etc.;thiol sulfur mainly contained isomers of three to six carbon atoms and its mass percentage just accounted for 5.09%;10.33%of total sulfur in naphtha would enter into C₅ distillate.And sulfur compounds in C₅ distillate were mainly thiophene and dimethyl thiophene,whose quality percentage accounted for as high as 84%.更多还原