从噪声到信息:基于声发射监控的聚烯烃流化床反应器新技术（英文）

目的:在全球所有的合成树脂中,聚烯烃的产能位居榜首,在国民经济建设和社会发展中发挥着重要作用。但流化床聚合反应器内的高静电会引起颗粒团聚,一旦传热受阻,颗粒极易熔融结块,甚至导致装置爆聚停车。本研究旨在针对流化床聚合反应过程具有强放热、高静电、变粒径的特点,提出基于声发射技术的多种检测手段和信息提取方法。创新点:针对聚合过程的爆聚结块问题,本研究主要解决了以下难题:(1)流化床内颗粒和结块的原位表征技术缺失,难以检测;(2)颗粒熔融结块过程的在线干预机制不清楚,难以调控;(3)流动传热过程强耦合,反应器放大规律不明,导致反应器难放大等问题。方法:创立声发射信号的多尺度解析方法,通过小波分解和重标极差分析法分类重构将声发射信号分解为微尺度、介尺度和宏尺度信号;提出基于声发射检测的反应器操作优化技术,并通过建模确立流化床聚合反应器的时空产率数学模型。成果:新技术成功应用于"十一五"国家重点建设项目——天津百万吨乙烯工程相配套的年产30万吨气相法聚乙烯流化床反应器的设计建设。并且,新技术已成功应用于14套大型聚烯烃装置的设计或改造,所涉及的聚乙烯产能达263万吨。作者所在团队也因该技术发明获得了2016年度国家技术发明奖二等奖。

模拟研究气液两相在带缩径管的90°弯管内的流动(英文)

目的:90°弯管广泛应用于工业中的流体输送,但是流体在经过弯头时会由于离心力的作用而导致弯头下游管道内出现流体分布不均的现象,从而影响后续的生产过程。本文将实验和计算流体力学(CFD)模拟的方法结合研究缩径管对经过弯头后的流体整流作用并分析原因,以期为缩径管在工业中的应用提供一定的参考。创新点:1.提出在弯头后的管路中增加缩径管来调整流体的方法;2.在冷模实验数据验证模拟结果的正确性的基础上,根据CFD模拟得到的管道内的压力、流体速度、相分布及湍动能分布详细分析了缩径管能起整流作用的原因。方法:1.通过冷模实验所得的压力数据与模拟值进行对比,证明模拟所采用模型的正确性;2.通过对不同流体入口条件模拟结果的比较,找到缩径管的作用规律;3.通过CFD模拟得到管道内的压力、流体速度、相分布及湍动能,分析缩径管的整流原理。结论:1.模拟所采用的模型可较好地反映管道内的流体流动情况;2.缩径管能起到很好的整流效果;3.缩径管可使流体加速,促进流体的快速混合,因此能够使不稳定的流体快速达到稳定状态。

Hole-growth phenomenon during pyrolysis of a cation-exchange resin particle

A novel central hole-expansion phenomenon is identified, in which the cation-exchange resin is pyrolyzed in a mixed atmosphere of nitrogen and oxygen at 400–500 ℃. In this reaction, the reaction path is predictable and always starts from the center of the resin particle to form a central hole, then continues and expands around the hole, finally forming a uniformly distributed hole group;the particle surface remains intact. Analysis shows that this formation mode is due to the different reaction paths of sulfonic groups between the surface and interior of the particle, caused by the temperature difference. On the surface, transformation reactions happen at high temperatures(410–500 ℃) to form stable organic sulfur structures, while decomposition occurs inside the particle at a relatively low temperature(<410 ℃) and promotes complete pyrolysis of the copolymer matrix to form holes.

Halysis Høeg,1932—An ancestral tabulate coral from the Ordos Basin,North China

The problematic calcareous microfossil Halysis is abundant in the Middle Ordovician Darriwilian Stage of the western edge of the Ordos Basin,North China.The rich and well-preserved specimens of Halysis in this area facilitate detailed studies for its skeletal construction and tube microstructure.Halysis differs from calcified cyanobacteria and calcareous red and green algae in morphology,skeletal construction and microstructure,as well as reproduction mode.Halysis typically consists of multiple juxtaposed parallel tubes arranged in sheets(‘multiple-tube'type)or is just composed of one tube(‘single-tube'type).In‘multiple-tube'Halysis,tube fission by bifurcation results from the insertion of a microcrystalline wall at the center of a mother tube.This study demonstrates for the first time that the tube walls of Halysis have a laminofibrous(fibronormal)microstructure,composed of fibrous calcite perpendicular to wall surface,and recognizes the‘single-tube'type Halysis composed of one tube;in addition,for the first time,this study finds out that‘multiple-tube'Halysis develops buddings from the conjunction of two tubes and‘single-tube'Halysis shows wide-angle Y-shaped branchings.Based on these findings,this study further compares Halysis with tabulate corals.Halysis appears stratigraphically earlier than Catenipora and Aulopora,and has a smaller tube size.‘Multiple-tube'Halysis resembles Catenipora and‘single-tube'Halysis resembles Aulopora in skeletal construction and microstructure,and in their tube walls of laminofibrous microstructure composed of fibrous calcite perpendicular to the tube wall surface.Catenipora and Halysis are both characterized by the absence of septal spines.The similarities suggest that Halysis may be the ancestor of Catenipora-like and Aulopora-like tabulate corals.

Modification of acidity in HZSM-5 zeolite for methane-methanol co-reaction

A co-reaction of methane with methanol over zeolite catalysts has emerged as a new approach to the long-standing challenge of methane transformation.However,the effect of catalyst acid properties on the co-reaction has been rarely studied.In this study,a series of HZSM-5 zeolites with comparable diffusion abilities and various acidities were synthesized directly through steaming with 100%water vapor at 693 K.The co-reaction of methane and methanol was subsequently evaluated.Br?nsted acidity at 0.262 mmol/g was detected to reach the maximum methane conversion of 5.42%at 673 K,which was also the odd point in the relationship between acid concentration and C4 hydrogen transfer index.Moreover,the influence of methanol feed was investigated over parent and steamed ZSM-5 catalyst,with results showing that excessive acid sites or methanol molecules reduce methane conversion.It is proposed that acid sites adsorbed with methanol molecules construct the methane activation sites.Hence,a proper design of zeolite acidity should be achieved to obtain higher methane conversion in the co-reaction process.

Preparation of Aryloxy-aluminoxanes and Their Use as Activators in the Bis(imino)pyridyl Iron-catalyzed Oligomerization of Ethylene

In this study, a series of aryloxy-aluminoxanes originated directly from the hydrolysis of reaction products of A1Me3 and phenols were synthesized, which could serve as effective polymer-retarding activators for the iron-catalyzed ethylene oligomerization. The molar ratios of [PhOH]/[AlMe3] and [H2O]/[Al] during the preparation were explored and their impacts on the oligomerization activity and product distribution were discussed. To obtain the effective activators with good polymer-retarding effect and relatively high activity, the optimized conditions were proposed to be [PhOH]/[AlMe3] = 0.5 and [H2O]/[Al] = 0.7. Various aluminoxanes with different [-OH] sources confirmed the importance of using phenols in preparing the effective polymer-retarding activators. By utilizing these aryloxy-aluminoxanes, the mass fraction of polymers in the total products could be reduced to lower than 1.0 wt%, which is much lower than that of the MAO-activated systems （〉 30 wt%）. This is a potential benefit for the industrial application of the iron-catalyzed oligomerization process.