石脑油中的硫化物对裂解过程的影响研究

在蒸汽裂解制乙烯过程中,硫化物的存在对裂解性能的影响比较复杂,主要影响裂解反应过程和结焦性能。从硫的种类和含量两方面叙述了石脑油中的硫化物对产物收率、原料转化率、结焦速率和一氧化碳生成量等方面的影响,同时根据不同硫化物的热分解情况分析硫化物在裂解过程中的作用。简要介绍了硫化物的抑制结焦可通过将其连续注入裂解原料或离线等方式在裂解炉管内表面形成含硫化合物实现。     

重柴油裂解结焦抑制剂工业应用试验

在中国石化北京燕山分公司化工一厂乙烯装置新区60kt／a SRT-1V型裂解炉上，进行了两个周期以重柴油为裂解原料、整炉添加结焦抑制剂的工业应用试验。试验表明，该试验所采用的有机硫磷抑制剂适用于重原料，抑制结焦效果明显，裂解炉运行周期可延长O．5—1.0倍。     

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。     

裂解炉管涂层材料的制备及其作用机理的研究

以一种中间基石脑油和萘的混合烃为裂解原料。在连续流动的微反蒸汽裂解评价实验装置上，对裂解的辐射段高温部位结焦进行了研究。并且用测试挂片对铝涂层，铝硅涂层，铬涂层，铝铬复合层抑制结焦性能进行了综合分析。结果表明：铝硅涂层具有良好的抑制结焦的性能，在裂解温度的条件下。与空白实验相比，能降低结焦速率60%-80%。     

Cr/W/稀土氧化物涂层的抑制结焦性能

急冷锅炉(TLE)是乙烯热裂解装置的重要设备,在运行中急冷锅炉炉管内壁会有结焦现象,降低急冷锅炉传热系数并增加炉管压力降,严重影响传热效果,需要进行周期性清焦.为了能够有效地抑制结焦,在炉管内壁表面上制备了一层Cr/W/稀土Re_xO_y惰性涂层,借助乙烯裂解结焦模拟装置、金相显微镜、扫描电子显微镜(SEM)和透射电镜(TEM)等设备从试样结焦表面形貌特征和结焦量等方面对所开发的涂层进行了抑焦性能研究.实验结果表明,无涂层试样表面存在催化焦和颗粒状焦,结焦严重;而涂层试样抑焦效果明显,表面不存在催化结焦,且焦层与涂层表面黏附性差结合较弱容易脱落,其结焦抑制率可达79.1%.     

乙烯裂解炉管结焦抑制剂

应用有机硫与有机磷化物所组成的混合物或有机硫磷化合物作为结焦抑制剂，可明显地降低结焦速度和减少结焦量。     

聚烯烃与其裂解产物返回共裂解的研究

以聚烯烃塑料为裂解原料,在间歇反应釜中进行轻度热裂解,加热速率3—5℃/min,温度400℃,停留时间0—80 min;制取液相石油烃。为克服热裂解过程中的传热不均匀,提高热裂解产物轻质馏分的含量,进行了部分热裂解产物返回作为原料与聚烯烃塑料进行共裂解的实验探究,并对其裂解气相产物进行了气相色谱分析,液相产物进行了红外光谱、核磁共振氢谱表征以及GC-MS定量分析。结果表明:在400℃进行共裂解,液相产物平均收率约为90%,所得液相石油烃C数分布广,主要组分为链烷烃,其中直链烷烃所占比例44.03%。在聚烯烃塑料轻度裂解过程中部分热裂解产物返回共裂解,有利于裂解过程的传热,促进所得石油烃的轻质化且裂解过程中不会发生结焦反应。但共裂解液相产物中离心沉积物增多,主要组成为链烷烃,可作为裂解原料再次进行利用。     

我国乙烯生产技术的发展近况

烃类热裂解、催化裂解、煤基甲醇制烯烃、从干气中回收乙烯以及生物资源制乙烯是目前我国工业上生产乙烯的主要技术,概述了这些技术的发展及应用情况。重点介绍了烃类热裂解的大型化技术、结焦抑制技术及节能技术,今后烃类热裂解技术应继续向低能耗、低投资、大型化和延长运转周期的方向发展。CPP催化热裂解技术可以降低裂解温度,并且采用重质原油为原料,尤其适合我国国情;MTO技术利用煤或天然气作原料得到乙烯,对于优化我国能源结构调整具有重大的意义。     

超临界条件下甲基环己烷的结焦抑制研究

以甲基环己烷作为烃类燃料环烷烃的模型化合物,研究了超临界反应条件下结焦抑制剂二苄基二硒醚和供氢剂四氢蔡/四氢蔡酮对环烷烃热裂解的结焦抑制作用.结果表明,二苄基二硒醚添加质量分数为300×10-6的结焦抑制率可达到56.3%,四氢蔡/四氢蔡酮添加摩尔分数为3%的结焦抑制率可达到53.5%,且对气体产物分布影响不大.SEM...     

裂解技术发展近况

介绍了裂解技术的发展现状及发展趋势，重点介绍了裂解炉技术，裂解原料与裂解产率，抑制结焦技术以及裂解炉的热效率和大型化，控制技术等方面。     

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.     

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     

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.     

催化裂化烟气排放控制技术现状及面临问题的探讨

催化裂化装置原料油当中往往包含噻吩、硫酚、环硫醚、硫醚以及硫醇等含硫化合物,因此在进行催化裂化反应的时候,一些含硫化合物就会在焦炭以及油浆当中存在。早在再生器中这些含硫焦炭就会由于氧化反应烟气,从而被直接的排放到空中,严重的污染了人们生活的环境,因此必须要采取有效措施,对其进行有效的控制。     

改善焦炭热性能的配煤添加剂研究进展

对国内外改善焦炭热性能的配煤添加剂研究现状进行了综述,总结出不同配煤添加剂的性质及其改善焦炭热性能的效果,探讨了其作用机理。指出配煤添加剂可扩大炼焦煤资源,降低炼焦成本,是解决我国优质炼焦煤资源不足的一种有效手段。并提出在配合煤中加入钝化剂具有一定的工业化应用前景。     

煤在炼焦过程中热解脱硫降低焦炭中硫含量

通过模拟工业焦化过程,针对一种高硫煤考察了不同气体种类、流量及加热速率下,焦炉煤气返回焦化过程对物焦炭中硫含量变化的影响。结果表明,焦化过程中通入H2,CH4和N2气体可以抑制热解气中的硫返回固体焦炭中,H2达到的焦炭脱硫量最大,其次是CH4和N2;增大气体流量、减小加热速率有利于使硫向气相转移,从而使固体焦炭中的硫分配降低;固体焦炭中硫含量变化亦表明,H2效果较佳,在3．0,1．5℃／min2种加热速率下可使焦炭中硫含量分别降低0．36％～0．39％和0．46％～0．56％。     

Formation of coke in thermal cracking of jet fuel under supercritical conditions

Continuous-flow reactor experiments were carried out to study coke formation from thermal cracking of home-made jet fuel RP-3 under supercritical conditions. The mechanism and precursor of coke forming were analyzed. The starting cracking temperature of RP-3 fuel was determined to be 471.8°C by differential scanning calorimetry (DSC). Temperature-programmed oxidation and scanning electron microscopy (SEM) characterizations of the stressed tubes showed that there are three different coke species including chemisorbed carbon, amorphous carbon and filamentous coke in the solid deposits. More than 90% of coke deposits are carried away by the supercritical fluid, which has strong capabilities of extraction for coke deposits and their precursors. There were 17.1 wt-% of iron and 11.1 wt-% of chromium found on the coke surface detected by energy dispersive spectroscopy (EDS) which suggests carburetionon alloy. RP-3 fuel and its cracking liquids were analyzed by GC-MS,which showed that the content of alkyl benzene and alkyl naphthalene increased evidently in cracking liquids. __________ Translated from Petrochemical Technology, 2006, 35(12): 1151–1155 [译自:石油化工]     

Processing oil shales with heavy oil recycle

Recycle of heavy oil (>340 °C) to the retort, in order to crack/coke the oil to lighter fractions, was investigated as a means of producing shale oil of more desirable product slates. Conversion of heavy oil to light oil (<340 °C) by thermal cracking and coking in the absence of and during oil shale retorting was studied using the CSIRO BIRCOS retort. As expected, the conversion by thermal cracking increased as temperature increased, with most of the net oil loss in the form of gas. By contrast, the conversion by coking alone decreased as temperature increased, with coke representing all the net oil loss. Thermal cracking was found not to be a first-order reaction, by showing a reduced conversion of heavy oil with reduced concentration of oil vapour. Retorting Stuart oil shale with heavy oil feeding and simultaneous cracking and coking showed a conversion of 19.1 g per 100 g feed heavy oil to 10.9 g light oil, 2.2 g gas and 6.0 g coke, with a net oil loss of 3.8 g per 100 g shale oil produced. These data were used to generate a set of parameters for a mathematical model which simulated a heavy oil recycle loop.