乙烷裂解制乙烯的工艺研究进展

以乙烷裂解制乙烯为切入点,围绕乙烷裂解制乙烯的工艺特点、工艺研究最新进展及国内外乙烷裂解装置应用情况进行了简述。通过对比分析发现,乙烷作为最有潜力替代石油资源裂解制乙烯的原料之一,其裂解制乙烯工艺具有多种优势及良好的发展前景。     

乙烷丙烷裂解研究

由于我国油气资源相对贫乏,裂解原料主要来自炼厂装置产品,包括轻烃、石脑油、柴油和加氢尾油。在我国裂解原料结构中,以石脑油和加氢尾油液体裂解原料为主,乙烷和丙烷所占比例较少,主要来自乙烯装置的循环乙烷和循环丙烷。近年来,随着炼油装置的升级改造以及美国页岩气的成功开发,使得乙烯装置使用乙烷和丙烷作为裂解原料的比例逐渐增加。当前,乙烷和丙烷均以混合方式裂解。通过研究工业裂解炉裂解乙烷、丙烷和乙丙烷的裂解产物收率,与乙丙烷混合裂解相比,乙烷和丙烷单独裂解降低甲烷收率,提高了乙烯、双烯、三烯和高附产品收率,从而提高了乙烷和丙烷的裂解效率。     

SRT-Ⅰ型炉裂解乙烷分析

通过建立SRT-Ⅰ型炉乙烷裂解数学模型,采用逐段计算法,分析了乙烷裂解反应过程中的操作参数和裂解产物沿管长的分布情况,讨论了操作参数对乙烷裂解反应过程和结焦的影响。     

SRT—I型炉裂解乙烷分析

通过建立ＳＲＴ－Ｉ型炉乙烷裂解数学模型，采用逐段计算法，分析了乙烷裂解反应过程中的操作参数和裂解产物沿管长的分布情况，讨论了操作参数对乙烷裂解反应过程和结焦的影响。     

前进化工厂新建乙烷炉经济效益显著

燕山石油化学总公司前进化工厂裂解装置原有10台轻柴油裂解炉和1台乙烷裂解炉。乙烷裂解炉是用于裂解循环乙烷,以提高乙烯总收率。裂解装置自1976年投产以来,存在着以下几个问题: 1.乙烷裂解炉烧焦、清焦和检修时,     

毫秒炉共裂解及单独裂解乙烷技术分析

对毫秒炉石脑油单独裂解、石脑油与乙烷共裂解、乙烷单独裂解工况下的乙烯、丙烯收率进行比较。结果表明,以乙烷在裂解温度为870℃、汽油比为0.60及注硫条件下的单独裂解为优,乙烯收率达到40.58%(体积分数),经济效益明显。     

国内外乙烷裂解制乙烯发展现状及思考

介绍了乙烷裂解制乙烯工艺技术特点与国内外乙烷裂解制乙烯产业现状,重点对美国乙烷出口情况、未来发展趋势及我国采用进口乙烷制乙烯项目的投资现状及有关问题进行了分析。乙烷裂解制乙烯具有生产成本低、乙烯收率高、装置投资少等优势,是北美和中东地区生产乙烯的主要工艺路线;面对美国乙烷出口以及我国乙烯市场产能不足、需求旺盛的现状,我国企业加快布局进口乙烷裂解制乙烯项目很有必要,但也存在产业链复杂、进口乙烷原料不足等风险,建议国内企业谨慎投资,防止项目投资过热带来的原料供给风险与经营风险。     

乙烷-丙烷混合裂解不同维度的数值模拟

随着乙烯原料向着轻质化发展,乙烷、丙烷成为重要的裂解原料,乙烷-丙烷混合裂解自由基反应机理的研究对乙烯原料优化具有重要意义。利用FLUENT模拟软件对乙烷-丙烷混合裂解自由基反应机理进行一维和二维模拟,根据一维、二维模型轴向和径向的流速、温度、原料及产物浓度分布,分析其混合裂解规律。径向的传递过程会降低裂解温度,所需供热量减少,同时径向自由基的返混促进了管中心原料的裂解,因此二维模型中乙烯和甲烷的浓度高于一维模型。乙烷-丙烷混合裂解的链引发阶段只有丙烷参与,乙烷参与了链传递过程,反应体系内自由基需要一定量的积累后才生成乙烯和丙烯。     

USC裂解炉出口温度、炉管构型对循环乙烷裂解性能的影响

在USC裂解炉上进行了不同乙烯原料、裂解炉出口温度、炉管构型的工业裂解标定试验,结果表明,循环乙烷易脱氢生成大量的乙烯(56.35%),丙烯、丁二烯、裂解液相产物收率极低,液化气通过断链反应可生成乙烯、丙烯、丁二烯以及少量的裂解液相产物,石脑油拔头油裂解乙烯收率低,但裂解液相产物(高附加值)收率较高;乙烷裂解炉出口温度宜控制在858℃左右;与U型炉管相比,乙烷在M型炉管裂解乙烷转化率、乙烯收率、丙烯收率、三烯收率高。     

天然气化工技术及进展

目前，世界上76％的合成氨、80％的甲醇、39％的乙烯由天然气为原料制取。甲烷、乙烷、丙烷用于裂解制乙烯世界富产天然气的地区都将廉价的天然气中的乙烷和丙烷用作裂解装置制乙烯的原料，大大提高了裂解制乙烯的经济性。据统计，美国乙烷产能(2718万t／a)的75％都采用乙烷和丙烷为原料，     

Influence of potassium on the competition between methane and ethane in steam reforming over Pt supported on yttrium-stabilized zirconia

The effect of addition of potassium to Pt supported on yttrium-stabilized zirconia (PtYSZ) catalyst for steam reforming of methane, ethane and methane/ethane mixtures was explored. Addition of potassium has a positive effect on preferential steam reforming of methane in mixtures of methane and ethane over Pt/YSZ catalysts. The activity of potassium-modified catalysts increased with time-on-stream during steam reforming of mixtures of methane and ethane, while the ratio of reaction rates of methane and ethane remained constant. Most importantly, it was demonstrated that the presence of potassium prevents competition between methane and ethane during steam reforming. The reaction rate ratio in methane/ethane mixtures is changed from preferential ethane reforming on PtYSZ towards preferential methane conversion as a result of addition of potassium.     

中国进口乙烷裂解制乙烯项目前景分析

乙烷裂解制乙烯与传统石脑油制乙烯相比,具有工艺流程短、占地面积小、装置投资少、乙烯收率高等相对优势,但中国进口乙烷裂解制乙烯项目是一个复杂的系统性工程,在原料稳定获取和经济效益等方面仍存在诸多问题。本文总结据不完全统计,中国正在建设和规划的乙烷裂解制乙烯项目共15个,其中全部或部分依赖进口美国乙烷资源的项目多达13个。文章从美国乙烷资源量、本土需求量、出口量、出口终端能力、海运能力以及中国进口乙烷接卸和储运能力、对乙烷原料的需求量等多个环节对获取进口乙烷的稳定性进行了分析。同时设定不同油价情境,对以进口乙烷为原料的裂解装置的经济性和竞争力进行分析。分析表明,美国乙烷出口量、出口设施能力、海运能力以及中国进口乙烷接卸和储运能力等多个环节仍存在不确定性,建议行业主管部门加强规划引导,各企业根据自身实际情况理性对待,深入开展项目可行性论证,避免一拥而上。     

Hydrogen production by decomposition of ethane-containing methane over carbon black catalysts

Mixtures of methane and small amounts of ethane were decomposed in the presence of carbon black (CB) catalysts at 1,073–1,223 K for hydrogen production. Although most of the added ethane was first decomposed to ethylene and hydrogen predominantly by non-catalytic reaction, subsequent decomposition of ethylene was effectively facilitated by the CB catalysts. Because some methane was produced from ethane, the net methane conversion decreased as the added ethane increased. The rate of hydrogen production from methane was decreased by the added ethane. A reason for this is that adsorption of methane on the active sites is inhibited by more easily adsorbing ethylene. In spite of this, the hydrogen yield increased with an increase of the added ethane because the contribution of ethane and ethylene decomposition to the hydrogen production was dominant over methane decomposition. A higher hydrogen yield was obtained in the presence of a higher-surface-area CB catalyst.     

Effect of ethane addition on propane pyrolysis

Pyrolysis of propane/argon mixture in the presence of trace quantities (0.1% and 0.9%) of ethane was investigated at reflected shock wave temperatures between 1200 and 2000K. Traces of ethane accelerated propane decomposition at high temperature. However, increase in the quantity of ethane added to propane/argon mixture did not result in the same increase of its accelerating influence. Ethylene, methane and acetylene were the main hydrocarbon reaction products, with small quantities of propylene and ethane detected only at lower temperatures. Below 1500K, addition of ethane slightly enhanced the yields of ethylene and methane at the expense of propylene and ethane respectively. The selectivity for acetylene increased with increasing temperature and with the decline of those for the other products. For none of the products, did the presence of ethane alter the relationship between product formation rates and temperature. The influence of ethane addition on propane pyrolysis at high temperatures was explained in terms of increased radical concentrations, especially hydrogen atoms and vinyl radicals, formed at high conversions. These accounted for the rapid acceleration of propane decomposition and the high yield of acetylene at high temperatures.     

汽提介质对二氯乙烷汽提脱除效果的影响研究

对碳五加氢石油树脂均相阳离子聚合体系二氯乙烷的脱除工艺进行了模拟。按照设计工艺流程,分别以180℃过热蒸汽、N2、乙烷、正丁烷、异丁烷及混合碳四为汽提介质,模拟了汽提介质对二氯乙烷残余量、汽提塔尺寸及二氯乙烷损耗量的影响,并分析了以上几种介质可能导致的设备腐蚀问题。结果表明,以N2作汽提介质时,二氯乙烷残余质量分数为0.0005%,回收率为94.12%,且不会产生腐蚀,是一种用于脱除二氯乙烷的良好汽提介质。     

阻燃剂十溴二苯乙烷的市场现状分析及展望

分析了阻燃剂在塑料市场的发展趋势,并以溴系环保型阻燃剂十溴二苯乙烷的特点为基础,分析了十溴二苯乙烷及溴系阻燃剂的发展方向,并对十溴二苯乙烷的规模做出了统计和展望。     

Separation of ethylene/ethane mixtures by adsorption on small-pored titanosilicate molecular sieves

Adsorptive separation of ethylene and ethane may represent a less energy-intensive alternative to current sub-ambient distillation methods. In this approach, ethylene and ethane are separated by inverse-phase gas chromatographic and gravimetric isotherm techniques on ion-exchanged forms of ETS-4 and RPZ titanosilicate molecular sieves. Gas chromatography reveals that kinetic separation of ethylene from ethane is possible using ETS-4 and RPZ adsorbents exchanged with Zn and mixed Ca/H. Gas chromatographic selectivities of 4–40 for the adsorptive separation of ethylene and ethane were measured for these adsorbents, and the limiting selectivity calculated from gravimetric adsorption isotherms was between 4 and 12. In accordance with the ideal adsorbed solution theory, ethylene/ethane selectivity increases with pressure in all cases studied, especially for strontium- and barium-exchanged ETS-4. Due to the molecular sieving character of the adsorbents, steric effects were observed for the adsorption of ethylene and ethane, and contact time between the adsorbent and the gas mixture was the key factor in the separation of the gases. ETS-4 and RPZ materials exchanged with Zn or Ca/H are excellent candidates for the commercial adsorptive separation of ethylene and ethane.     

Oxidative dehydrogenation of ethane on Pt–Sn impregnated monoliths

The oxidative dehydrogenation of ethane was studied over Pt–Sn impregnated monoliths at 1 bar, 600–900 °C and with different contents of oxygen, hydrogen and steam in the feed gas. As expected a decrease in oxygen in the feed led to a decrease in the conversion of ethane due to lower temperatures in the reactor. Adding steam to the feed showed no effect on the ethane conversion or the ethene selectivity. When the hydrogen/ethane ratio in the feed was varied from 0 to 0.5 at 700 and 850 °C, it resulted in a significant increase in the selectivity to ethene while the ethane conversion remained relatively unchanged. At 700 °C the selectivity increased from about 50% to 93% (carbon basis) with only a small decrease in the conversion of ethane. The results clearly show that both Pt and Sn have a catalytic effect. Pt caused the ethane conversion to rise and addition of Sn resulted in much better ethene selectivity. However, even though Sn alone showed some catalytic effect at lower temperatures, it cannot explain the great difference between the Pt and Pt–Sn catalysts. A reasonable assumption is therefore that there exist interactions between Pt and Sn that gives the Pt–Sn catalysts excellent properties for oxidative dehydrogenation of ethane, in particular upon addition of hydrogen.     

PtSn-Mg(Zn)AlO催化剂应用于乙烷脱氢反应研究

采用阴离子交换法合成了一系列不同Zn和Pt含量的PtSn-Mg(Zn)AlO催化剂用于乙烷脱氢反应。实验结果表明,在水滑石载体中掺杂少量的Zn对乙烷脱氢反应有明显影响。当Zn含量为2%（质量）时Pt基催化剂活性性能最优,在550℃时乙烷初始转化率达到27.1%,2 h平均转化率为21.6%。BET和SEM结果表明PtSn-Mg(Zn)AlO催化剂比PtSn-MgAlO催化剂比表面积更大,TEM结果显示,PtSn-Mg(Zn)AlO催化剂和PtSn-MgAlO催化剂的金属颗粒的平均直径分别为（1.49±0.31）nm 和（2.0±0.23）nm,说明Zn的掺杂在一定程度上改变了催化剂的结构,能减小Pt颗粒的尺寸,更好地分散Pt颗粒,从而改善乙烷催化脱氢反应性能。此外,考察温度对乙烷脱氢反应性能影响,发现温度越高乙烷初始转化率越高,但催化剂越易失活;考察Pt负载量对乙烷脱氢反应性能的影响,发现增加Pt含量并不能使乙烷转化率得到相应倍数的增加,即增加Pt含量反而使Pt的利用率降低了,因此适量降低PtSn-Mg(2-Zn)AlO催化剂中Pt含量对研究乙烷脱氢反应有深远意义。     

串联式干气密封在脱乙烷塔回流泵上的应用

分析了脱乙烷塔回流泵接触式机械密封频繁失效的原因,选用适合乙烷介质的串联式干气密封及控制系统对脱乙烷塔回流泵密封进行改造获得成功。