烃类裂解装置的结焦抑制技术

介绍了烃类裂解装置(裂解炉、急冷锅炉)的结焦抑制技术:改变工艺条件、裂解原料预处理、炉管表面预处理、混合原料裂解以及裂解原料中添加结焦抑制剂等。重点讨论了添加结焦抑制剂抑制结焦的机理、应用效果以及工业实施方案的选择。     

原位涂层技术在茂名乙烯裂解炉上的应用

介绍了茂名石化1号乙烯装置H-115裂解炉应用原位涂层技术后的运行情况。运行结果表明:原位涂层抑制裂解炉辐射段炉管结焦效果明显,在抑制辐射段炉管结焦的同时,对于提升裂解炉的投油量、降低急冷锅炉出口温度等产生了积极作用,延长了裂解炉的运行周期。在石脑油工况下,H-115裂解炉在高深度、高负荷裂解条件下的运行周期达到110 d,运行效果良好。采用原位涂层技术改造后,急冷锅炉出口温度在运行末期和初期的温差由24℃降至10℃。     

乙烯裂解炉屏障涂层和催化涂层技术进展

介绍了国内外乙烯裂解过程中屏障涂层和催化涂层的技术进展及其应用。屏障涂层作为一道惰性阻隔层,能够阻隔物料与炉管内表面的铁、镍元素接触,避免催化结焦和炉管渗碳。催化涂层除了能抑制催化结焦外,还能自动去除沉积在炉管内壁的焦炭,是一种双功能涂层。目前国内外针对屏障涂层技术的研究较为广泛;因催化涂层的应用能够实现无清焦操作,近年来逐渐引起业内关注。催化涂层实现工业应用的难点在于如何降低碳氧化物的生成量,使其控制在可接受范围。     

乙烯裂解模拟装置急冷结构的优选研究

在具有不同急冷结构的乙烯裂解模拟装置上进行石脑油裂解模拟对比试验,比较分析其产物收率及结焦量大小。在混合急冷器上、下部区域向裂解气分别注入急冷水、循环气体产品,裂解模拟试验结果表明:采用该急冷结构的裂解模拟装置,具有较高的冷却效率,可实现高温裂解气的快速急冷;裂解产物分离充分,炉管结焦量少,烧焦持续时间短;当急冷水注入量减少后仍可实现裂解气快速急冷,且后续装置的负荷和压力波动减小,提高了装置操作的灵活性和稳定性。注水管插入混合急冷器内部可使裂解产物更加快速、顺利地通过裂解炉管进入产物急冷回收装置,防止了注水孔处结焦而堵塞炉管,装置可实现长周期运转。     

乙烯急冷锅炉的结焦

在乙烯裂解装置中,急冷锅炉担负着将裂解气迅速冷却以终止二次反应和利用裂解气的热量产生高压蒸汽的双重作用。换热管内结焦是急冷锅炉运行过程中的一个突出问题。尤其是,裂解原料为重质油(如重质AGO,VGO 等)时,急冷锅炉的结焦更加严重,并且构成了裂解装置运转周期的主要制约因素。为保证物流的畅通,不得不使裂解炉不定期停车,以对急冷锅炉进行清焦(机械或水力清焦)。这不但影响了裂解炉的开工率,而且使裂解炉的使用寿命缩短。另外,急冷锅炉的结焦,使其阻力降增加,上游的压力升高,     

乙烯裂解炉的结焦及其抑制措施

介绍了烃类在裂解炉中裂解的结焦机理及影响结焦的因素,国内外乙烯裂解过程中裂解炉管结焦抑制技术的进展．包括炉管表面涂层技术、最新结焦抑制剂和新型炉管等的应用。     

醋酸钾对轻石脑油裂解结焦的影响

为考察碱金属元素对裂解结焦的影响,以醋酸钾为结焦抑制剂,在850℃下对退役25Cr35Ni炉管试样内表面进行了结焦实验。利用扫描电子显微镜(SEM)、场发射扫描电镜(FE-SEM)、能量色散谱仪(EDS）、X射线衍射(XRD)和Raman光谱对退役25Cr35Ni炉管试样内表面和焦层进行了表征。结果表明,退役25Cr35Ni炉管内表面主要由Cr_1.3Fe_0.7O₃相似文献   

La1-xSrxMnO3钙钛矿涂层的抗结焦性能

目前，钙钛矿材料在汽车尾气催化处理、污水处理及燃料电池等方面应用广泛，但在抑制热裂解结焦涂层应用方面鲜有报道。本文以磷酸二氢铝为黏结剂，采用浆料法在HP40不锈钢基体表面制备了La_1-xSr_xMnO₃钙钛矿涂层，采用X射线衍射(XRD)、扫描电子显微镜(SEM)、能谱仪(EDS)和Raman光谱考察了La_1-xSr_xMnO₃钙钛矿涂层及表面焦层的物相组成和微观结构，利用X射线光电子能谱(XPS)研究了涂层组成元素的化学状态，通过石脑油热裂解结焦实验评价了涂层的抗结焦效果。结合材料表征与实验结果，阐述了涂层抗结焦机理。表征结果显示，La_1-xSr_xMnO₃钙钛矿涂层涂覆均匀，厚度约为30μm，与基底贴合紧密，粒子之间结合较好，但表面存在少量微孔；La_1-xSr_xMnO₃钙钛矿氧化物具有明显的立方晶体特征，Sr进入La Mn O3...     

裂解炉清焦工艺的改进

吉林乙烯装置年产乙烯11.5万吨,丙烯5.99万吨,采用日本三菱油化及三菱重工联合开发的M-TCF倒梯台型裂解炉及M-TLX急冷锅炉(以下简称M-TCF及M-TLX)。装置运转了一定时间以后,由于高温下烯烃及芳烃等在M-TCF炉管及M-TLX上结焦,使其传热效率降低,炉管表面温度上     

25Cr35NiNb合金表面Al-Si-Cr涂层抑制结焦性能

采用固体粉末包埋渗方法在25Cr35NiNb合金表面制备Al-Si-Cr涂层,通过乙烯裂解模拟装置中的结焦实验,对涂层抑制结焦性能进行分析评价。运用金相显微镜、扫描电子显微镜(SEM)和能谱仪(EDS)等方法分析了涂层显微组织及结焦层形貌特征。结果表明,采用粉末包埋共渗可以得到厚度在130 mm左右的Al-Si-Cr涂层,涂层具有多层结构且组织致密,外层为富铝硅层,内层为富铬硅层;Al-Si-Cr涂层具有良好的抗结焦性能,可有效抑制催化结焦,抑制结焦率达72.5%。     

Preparation and Anti-coking Property of SiO2/S Coating on HP40 Tube

SiO2/S coating was prepared on the inner surface of an HP40 tube using dimethyldisulfide and tetraethylorthosilicate by atmospheric pressure chemical vapor deposition (APCVD) to alleviate catalytic coking on the inner surface of radiant tube for ethylene production in petrochemical plants. The comparative coking experiments with the coated and uncoated HP40 tubes were carried out under the same cracking conditions. SiO2/S coating was compact and had excellent anti-coking property. The coke on the coated HP40 tube was about 22% of that on the uncoated HP40 tube, and only small granular coke was deposited on the coated HP40 tube. However, the filamentous coke formed on the uncoated HP40 tube. The thermal stability of SiO2/S coating was satisfactory at cracking temperature, and the anti-coking property of SiO2/S coating was still over 60% after 3 coking and decoking cycles.     

SiO2/S涂层与硫磷抑制剂对轻石脑油裂解结焦的影响

引言乙烯裂解炉辐射段炉管结焦是制约乙烯装置长周期运行的主要因素。裂解炉管的结焦会引起[1]:①管壁热阻增加,传热效率降低,裂解炉能耗增加;②炉管内径变小,流体压降增加,装置处理量减少;③炉管内壁渗碳,材料性能弱化;④周期性的清焦引起炉管热疲劳现象,而清焦过程中焦炭的     

硫化物和硫/磷化合物的添加方式对石脑油热裂解结焦影响的研究

以石脑油为裂解原料，考察了硫化物和硫/磷化合物的添加方式对热裂解结焦行为的影响。采用Raman光谱、XRD、SEM和XPS等检测手段表征了HP40试样的氧化层和焦炭的形貌与结构。结果表明，原料连续注入硫化物条件下，磷化物的加入使得焦炭结构改变，显示出优异的抗结焦效果。硫化物和硫/磷化合物预处理导致氧化层中Fe含量升高，抑制结焦效果有限。硫/磷预处理与原料连续注入硫/磷化合物联合方式与原料连续注入硫/磷化合物方式的抗结焦效果接近，但前者在初期的抑制效果更明显。所有添加方式都会引起结焦层中无定形焦炭含量升高，焦炭的石墨化程度降低。热裂解焦炭缩合程度较高，硫化物和硫/磷化合物减少了催化结焦的生成，在一定程度上提高了焦层中氢含量。     

Addition methods of sulfur and sulfur/phosphorus-based compounds on coking behavior during thermal cracking of naphtha

Using naphtha as raw material for cracking, the effects of adding sulfides and sulfur/phosphorus compounds on the coking behavior of thermal cracking were investigated. The morphologies and structures of the pretreated HP40 alloy specimen and coke deposits were characterized by Raman spectroscopy, XRD, SEM and XPS. The results showed that the addition of phosphide into the sulfide additives led to the change in the structure of coke deposits under the condition of continuous addition of additives into the feed. The method with continuous addition of sulfur/phosphorus-based compounds showed excellent anti-coking properties. The surface pretreatment with sulfur or sulfur/phosphorus-based compounds made the increase of Fe content in the oxide film on the specimen. So anti-coking effect was limited when the pretreatment method was applied. The coking inhibition property of the application of surface pretreatment with sulfide/phosphide followed by continuous addition of sulfur/phosphorus-based compounds were similar to that of the application of continuous addition of sulfur/phosphorus-based compounds in the feed. However, the combination method showed the better anti-coking effect during the initial cracking process. All the addition methods led to the increased amounts of amorphous coke in the coke layer and the decreased graphitization degree of cokes. The results of the low H/C ratios showed the highly condensed structure of the coke deposits during thermal cracking process. The addition of sulfur and sulfur/phosphorus-based compounds could influence the dehydrogenation reaction to some extent during the coke formation by reducing catalytic coking.     

涂层技术抑制乙烯炉管结焦的研究进展

对乙烯炉管结焦的机理和抑制结焦的方法进行了综述,并对涂层技术进行了分析比较,指出了抑制结焦技术的发展方向。     

Outlet Temperature Correlation and Prediction of Transfer Line Exchanger in an Industrial Steam Ethylene Cracking Process

Predicting the best shutdown time of a steam ethylene cracking furnace in industrial practice remains a challenge due to the complex coking process. As well known, the shutdown time of a furnace is mainly determined by coking condition of the transfer line exchangers （TLE） when naphtha or other heavy hydrocarbon feedstocks are cracked. In practice, it is difficult to measure the coke thickness in TLE through experimental method in the complex industrial situation. However, the outlet temperature of TLE （TLEOT） can indirectly characterize the coking situation in TLE since the coke accumulation in TLE has great influence on TLEOT. Thus, the TLEOT could be a critical factor in deciding when to shut down the furnace to decoke. To predict the TLEOT, a paramewic model was proposed in this work, based on theoretical analysis, mathematic reduction, and parameters estimation. The feasibility of the proposed model was further checked through industrial data and good agreements between model prediction and industrial data with maximum deviation 2% were observed.     

乙烯裂解炉结焦抑制技术进展

综述了近年来国内外乙烯裂解过程中结焦抑制技术研究及工业应用进展;介绍了添加结焦抑制剂、炉管涂覆技术研究、新材料炉管的工业应用;对中国乙烯装置开发结焦抑制技术提出了建议。     

工艺参数对轻石脑油裂解结焦的影响

为了研究工艺参数对结焦的影响,以轻石脑油为裂解原料,在设定工艺条件下进行了HP40合金试样氧化表面的结焦试验。利用扫描电子显微镜(SEM)、能量色散谱仪(EDS)对HP40合金试样表面的氧化层和焦层进行了表征。考察了裂解时间、裂解温度和稀释比对其结焦的影响。结果表明,HP40合金试样表面氧化层多孔,为尖晶石结构,尖晶石的粒径最大约为0.5μm。在裂解温度为850℃时,随着时间增加,结焦量、催化焦丝直径增加,焦丝直径生长速率约为0.027μm/min;在裂解时间为20 min时,随着温度增加,催化焦丝直径增加,焦丝直径生长速率约为0.0051μm/℃,当焦丝直径增加至0.8μm左右时,催化结焦过程结束,热裂解结焦开始。稀释比增大,结焦速率降低。     

Two-stage cracking catalyst of amorphous silica-alumina on Y zeolite for enhanced product selectivity and suppressed coking

A novel bilayer catalyst composed of amorphous silica-alumina (ASA) layer coated on Y zeolite layer is proposed as a fluid catalytic cracking (FCC) catalyst to cause two-stage reactions of pre-cracking and deep-cracking. The bilayer catalyst (Y/ASA) is compared with the usual mixed one (ASA+Y), in catalytic cracking of a feed composed of 1,3,5-triisopropylbenzene and naphthalene. The two catalyst representations were prepared by applying layers of Y zeolite and ASA or both on inert monolith supports. Catalytic cracking experiments were carried out at 300, 350 and 400 °C. Compared to Y+ASA, Y/ASA yielded about 33% and 46% more benzene and toluene, respectively, and 18% less coke in the catalytic cracking at 350 oC. The coke of Y/ASA was less refractory than that of Y+ASA as burnt at lower temperatures, while emitting less carbon monoxide in regeneration. Y/ASA configuration shows promising features as FCC catalysts for increased bottoms cracking and suppressed coking.