陕西省双王金矿床中自然金属与金属互化物

为研究陕西省双王金矿床的物质组分,对矿物进行反光显微镜观察和电子探针分析,发现了自然金、自然铋的金属矿物以及黑铋金矿的金属互化物。这些自然金属矿物与金属互化物在卡林型、类卡林型金矿床中均有较罕见的产出,其生成条件独特,是在一种缺氧、低硫的较强还原环境中形成的,反映出成矿作用与岩浆活动有密切联系。

不同品牌输液器对输液泵输液精度的影响

目的验证不同品牌输液器对输液泵应用过程中输液精度的影响。方法以国产某品牌、型号输液泵作为试验载体,选用其指定品牌输液器及3种其他品牌输液器,使用IDA4 PLUS输注设备检测仪,按GB 9706.27-2005《医用电气设备第2-24部分:输液泵和输液控制器安全专用要求》标准进行测试,并进行统计分析。结果指定品牌输液器与3种其他品牌输液器的输液精度比较,除C品牌输液器在设定流速为25 ml/h时P>0.05,其他情况下均为P<0.05。结论在输液泵的应用过程中,应合理选用输液器,认真阅读、掌握、理解使用说明书中载明的内容,严格执行护理操作规程。

乙烯气相聚合工艺研究与技术进展

聚乙烯已成为全球产量最大、用途最广的合成材料。由于生产流程短和设备投资低的优势,流化床气相聚合工艺是聚乙烯的主要生产路线,得到了广泛而深入的研究和开发。本文综述了国内外乙烯气相聚合工艺技术的研发历程,特别是中国在气相法聚乙烯技术方面做出的重要贡献。总结了气相聚合工艺的七种操作模式,即干法气相聚合、超干法气相聚合、气相冷凝聚合、气相超冷凝聚合、气液固云雾聚合、露点聚合以及交替交变聚合。分析了各操作模式所涉及的关键科学问题和工程技术解决方案,例如反应器时空产率模型、冷凝态聚合操作点优化、溶剂的作用、黏性流化颗粒熔融温度预测、流化质量监控与声发射、多流型复合以及一器多用等,并重点介绍了气-液-固云雾聚合流化床反应器中颗粒团聚、气泡运动的新特征,云雾聚合流化床运行的新稳定机制,以及实现聚合物产品结构调控的新途径——乙烯的露点聚合和交替交变聚合技术。指出聚合反应工程学科正从聚焦传统的过程强化,发展到过程强化与产品多样化相互兼顾的变化趋势。

气液法流化床乙烯云聚合工艺开发及产品高性能化

随着国内聚烯烃产量的不断增加,聚烯烃通用料市场竞争加剧,开发新型高性能聚烯烃产品至关重要。针对气液法流化床乙烯云聚合工艺的构建以及聚乙烯产品高性能化,在气液法流化床所包含的典型介尺度结构实验和理论研究基础上,明确聚合反应条件,优化气液法流化床进料系统,最终应用于气液法流化床乙烯云聚合工艺的开发。通过对工业试验产品的分子链结构的表征分析,证明云聚合工艺是生产高性能聚乙烯产品的全新成功途径。

多层流化床床层及溢流管中气固流动特性的模拟

采用多孔介质模型描述两床层间的气体分布板,开发了一种多层流化床典型结构单元的计算流体动力学(CFD)模拟方法,研究了操作气速对多层流化床床层流化状态及其溢流管内颗粒流动特性的影响。结果表明:层间溢流管内颗粒料位具有缓冲作用,使得颗粒进入下床层后被迅速均匀分散,保证了下床层固相均匀性。流化气速增大,下床层进入溢流管的气体量增加,导致管内密相区范围增大、浓度降低、浓度梯度增大,密相区与稀相区间的过渡区范围增大,密相区内逐渐出现气泡或气体栓塞,同时使溢流管内上升气流的阻挡作用增强,上流化床层向溢流管的间歇进料难度变大,溢流管上方出现料位积累。颗粒溢流状态的改变和间歇进料难度的加剧可能是颗粒溢流失稳的原因。

Modeling and Optimization of Ethane Steam Cracking Process in An Industrial Tubular Reactor with Improved Reaction Scheme

Ethane steam cracking process in an industrial reactor was investigated.An one-demsional(1D)steady-state model was developed firstly by using an improved molecular reaction scheme and was then simulated in Aspen Plus.A comparison of model results with industrial data and previously reported results showed that the model can predict the process kinetics more accurately.In addition,the validated model was used to study the effects of different process variables,including coil outlet temperature(COT),steam-to-ethane ratio and residence time on ethane conversion,ethylene selectivity,products yields,and coking rate.Finally,steady-state optimization was conducted to the operation of industrial reactor.The COT and steam-to-ethane ratio were taken as decision variables to maximize the annual operational profit.

Effect of Hydrothermal Treatment on Suppressing Coking of ZSM-5 Zeolite during Methanol-to-Propylene Reaction

Fresh ZSM-5 zeolite catalysts were pretreated at 460 ℃and 500 ℃with various cumulative amount of water feed(CAWF) in a fixed bed reactor. The catalytic process was carried out under the following conditions: a temperature of 480 ℃; a methanol WHSV of 3 h-1; a methanol partial pressure of 30 k Pa; and a time on stream of 12 h, 24 h and 48 h, respectively. The BET parameters of catalysts and diffusion coefficients of toluene showed that there were two types of mesopores generated under different hydrothermal conditions. Mild temperature and moderate CAWF conditions led to external open mesopores which could be entered from the external surface of the zeolite, while a high temperature or a high CAWF condition resulted in the generation of macropores or internal isolated mesopores, which were occluded in the microporous matrix. The TGA results showed that catalyst with external open mesopores had good ability to resist coke accumulation and good performance on propylene selectivity, while the internal isolated mesopores did no contribute to the increased diffusivity of reactants and products.

某黄金矿山氰化尾渣治理试验研究

针对某黄金矿山氰化尾渣开展酸化降氰试验研究,并对浓硫酸用量、反应时间等条件进行了优化,最终给出推荐工艺,即氰化尾渣调浆—酸化降氰—压滤工艺。在浓硫酸用量10 mL/L,反应时间1.0 h条件下,无害化处理后的氰渣达到HJ 943—2018《黄金行业氰渣污染控制技术规范》尾矿库处置标准要求,药剂成本约为11.00元/t氰渣。研究结果为该黄金矿山氰化尾渣无害化治理的工业应用提供数据参考。

Improving Refinery Profits via Fine Management of Hydrogen Networks

Hydrogen network management is important to refineries. Various systematic management techniques have been developed to improve the efficiency of refinery hydrogen networks. However, existing methods all treat the hydrogen network separately. The tradeoff between hydrogen network cost and oil processing network benefit has not been explored in the hydrogen network management yet. A novel sensitivity analysis scheme is presented to take oil processing network into consideration. Oil processing unit which is sensitive to both oil processing networks and hydrogen networks is identified first. Then, sensitivity analysis of the unit around the operating point of oil processing networks and hydrogen networks is carried out. Finally, the overall optimal operating condition is obtained. An example of a real Chinese refinery demonstrates the effectiveness of the proposed analysis method.

Hydrodynamic Instability Analysis of the Axial Flow Pump in an Ethylene Polymerization Loop Reactor

The hydrodynamic instability of the axial flow pump in a loop reactor has long been a troubling issue to be solved in the polyethylene industry due to the lack of a better mechanismic understanding.Generally,the instability of an axial flow pump can be reflected by the fluctuation of the pump head.In this study,the transient computational fluid dynamics(CFD)simulation is adopted to study the hydrodynamic instability of the axial flow pump used in an ethylene polymerization loop reactor.The results show that the pump head under single liquid phase nearly remains constant while the pump head under slurry phase fluctuates due to the variation of solid volume fraction distribution in the pump.Besides,under the combined effect of the maximum solid volume fraction difference in the pump and the turbulence intensity of the liquid phase,the fluctuation of the pump head under slurry phase increases when the solid volume fraction in the loop reactor increases from 0.10 to 0.29,and the fluctuation decreases,when the solid volume fraction increases from 0.29 to 0.35.Furthermore,there is a negative correlation between the pump head and the solid volume fraction in the pump;with the increase of solid volume fraction in the loop reactor,and the correlation coefficient increases as well.Moreover,a‘spiral particulate band’phenomenon is formed in the ascending leg caused by three mechanisms,viz.:the segregation of particles in all bends,the dispersion of particles by the secondary flow in the ascending leg,and the rotational movement of particles in the pump.

RHO:A Software Tool for Targeting and Design of Refinery Hydrogen Networks

Hydrogen management is important for refineries to improve their business efficiency.Various approaches such as pinch analysis and mathematical programming have been employed in the management of hydrogen system.However,it is not easy for site engineers to implement these techniques,due to the complicated procedures.At this point,it is necessary to develop a software that can implement the proposed methodologies automatically,which is really the goal of this work.The presented refinery hydrogen system optimization software(RHO)is a web based system.It is developed in the Java Web environment,where the subroutines of mathematical model developed in GAMS software can be easily called.RHO can generate graphics of both the hydrogen pinch diagram and the hydrogen distribution network.The purifiers as well as the physical distances between units are considered in the optimization model.In addition,there is a special module for the calculation of membrane separation,which is very important in the hydrogen network.The functions and the interfaces of the software are illustrated via practical cases.Case studies show the effectiveness of the RHO software.

Recent Progresses on Optimal Design of Heat Integrated Water Allocation Network

Energy integration and mass integration are important approaches to achieve energy saving and emission reduction in the process industry.Generally,the methods can be classified into two groups,viz.:conceptual design methods and mathematical programming methods.The former includes mainly graphical methods based on pinch technology that is operated easily.A feasible solution can be quickly obtained.Conceptual design methods are sequential in nature including two steps,namely:targeting and designing.The latter is based on superstructure optimization,and corresponding algorithm is adopted to solve the model.The trade-offs and connections among the entire network can be established and explored.Multiple factors can be considered and optimized simultaneously by mathematical programming methods.This paper describes the synthesis of heat integrated water allocation networks(HIWAN)based on both conceptual design methods and mathematical programming methods systematically.In addition,the characteristics and shortcomings of the existing research methods are summarized,and the future research direction is prospected.

考虑催化剂失活的环氧乙烷反应器机理与数据模型

环氧乙烷是乙烯工业的重要衍生物之一,主要由乙烯在银催化剂作用下直接氧化生产。针对催化剂活性缓慢衰减,需定期调整操作条件以维持产量和高选择性的问题,提出了机理模型和数据模型耦合的方法,以确定催化剂的活性变化和各操作条件的影响。以某工业环氧乙烷反应器为对象,通过阿里云智能制造平台挖掘生产数据,分别使用反应动力学、失活动力学、反应器模型和支持向量回归,建立了各操作条件与反应器出口组成的模型。结果表明,在输入变量中添加机理模型所得的活性变量后,支持向量回归模型较原始模型更加准确,计算的反应器出口组成和选择性在测试集上的平均绝对百分比误差小于3%,为优化选择性提供了基础。

Measurement of the fluidized velocity in gas-solid fluidized beds based on AE signal analysis by wavelet packet transform

An energy distribution theory was presented based on regular evolvement of energy fraction of acous-tic signals with fluidization velocity. Wavelet packet analysis was used in processing the acoustic sig-nals originated from particle impact on the wall of a fluidized bed. A new criterion of judging incipient fluidization(Umf) velocity and minimum turbulent velocity(Umt) was proposed according to the energy distribution theory. Experiments were performed with five groups of high density polyethylene(PE) particles and one bimodal PE to acquire incipient fluidization velocity and minimum turbulent velocity by using the criterion. The feasibility of this method in obtaining characteristic fluidization parameters was further verified by comparing it to results from the pressure drop method and the empirical value from industry.

Acidity Modification of ZSM-5 for Methane Conversion in Co-feeding Method with MTA Reaction

Acidity plays a vital role in methane conversion by co-feeding method,which is one of the best strategies to improve the utilization and gentle the reaction conditions of methane.In this work,Zn,Ni,Mo,La,Ga,Fe and Co-impregnated ZSM-5 zeolites have been prepared with the same substitutions to variate the acidities and tested in co-aromatization of methanol with methane.It is demonstrated that the new medium-strong acid sites formed by metal and strong acid sites are the key role to activate methane in co-reaction.Zn-modified ZSM-5 catalyst is preferred to exhibit the best methane conversion of 12%,whose aromatic selectivity increases from 27.2%to 52.2%compared with that of HZSM-5.Besides,the addition of methane further improves the production of high-valued aromatics compared with methanol to aromatics(MTA)reaction.