The Method of A-Harmonic Approximation and Optimal Interior Partial Regularity for Nonlinear Elliptic Systems Under Controllable Growth Conditions

考虑具有可控增长条件的非线性椭圆方程组弱解的部分正则性.利用Duzaar和Grotowski引进的弱解部分正则性证明的新方法,该方法是建立在调和逼近技巧一般形式的基础上的,我们把前人的结果由自然增长条件推广到了可控增长条件,并且所得到的弱解导数的Hlder指标是最优的.In this paper,we consider the nonlinear elliptic systems under the controllable growth condition.We use a new method introduced by Duzaar and Grotowski,for proving partial regularity for weak solutions,based on a generalization of the technique of harmonic approximation.We extend previous partial regularity results under the natural growth condition to the case of the controllable growth condition,and establishing the optimal Hlder exponent for the derivative of a weak solution directly.Supported by NSF(No:10531020)of China and the Program of 985 Innovatio Engineering on Information in Xiamen University(2004-2007

MONTE CARLO SIMULATION of SINGLE-/MULTI-ACTIVE SITE CATALYSTS FOR PROPYLENE POLYMERIZATION

采用MOnTE CArlO模拟技术研究了在不考虑聚合物颗粒内物料与热量传递效应及不存在氢气作用下的单、多活性种类催化剂催化的丙烯聚合动力学。探讨了聚合产率、催化剂活性中心分率以及多分散指数随时间的变化规律,并对单、多活性中心种类催化的反应体系分别作了比较。基于MOnTE CArlO方法的模型得出的聚合动力学结果与文献相一致。此外,由MOnTE CArlO模拟也得到,催化剂多活性中心种类的性质对聚合产物的分布性质有很大影响;以多分散指数而言,多活性中心种类催化剂催化得到的聚丙烯多分散指数要比单活性中心种类催化剂催化得到的产物多分散指数宽。A Monte Carlo model was established to describe the propylene polymerization kinetics catalyzed by single-or multi-active site catalyst,ignoring the effects of intraparticle mass and heat transfer and the effect of hydrogen.Corresponding propylene polymerization kinetic data,including polymerization yield,concentration transformation of catalyst active sites,polydispersity etc.,were obtained via the model.Comparisons of the kinetic results between the polymerization catalyzed by the single-active site catalyst and the multi-active site type catalyst were conducted via the model.The simulated kinetic results are found to be in agreement with the reference ones obtained experimentally.The studied results showed that nature of multi-active site type could have a significant influence on polymer distribution properties.As of the polydispersity(PDI),polypropylene catalyzed by multi-active site type catalyst has a broader PDI than the one catalyzed by the single-site catalyst,under the same reaction circumstance.中国石油兰州石油化工研究中心课题(2007019);固体表面物理化学国家重点实验室(厦门大学)课题(200505)项目资

STEADY-STATE MODELING of COMMERCIAL LIQUID PHASE BULK PROPYLENE POLYMERIZATION

采用POlyMErS PluS软件对HyPOl聚丙烯工艺进行了模拟。建立了与现场流程及POlyMErS PluS软件均相匹配的模拟流程;采用PC-SAfT状态方程,并根据zIEglEr-nATTA催化体系的丙烯聚合机理,确定了丙烯聚合动力学。此外,通过文献提供的现场数据分析并确定了丙烯聚合动力学参数。最终建立了完整的HyPOl工艺流程模型。以采集的工业数据对模型进行验证,并采用模型考察了工业稳态操作下的主要工艺条件对丙烯聚合过程的影响。结果表明,模拟结果与工业现场采集数据比较吻合。随着H2进料量增加,聚合产品的熔融指数(MI)增大,数均相对分子质量(Mn)及其多分散分布指数(PdI)下降;催化剂及丙烯进料量的增加都将使各反应釜的聚合物产量增加。The HYPOL technology of polypropylene was simulated by Polymers Plus.First,a flowsheet which incorporates the actual technology into Polymers Plus was obtained.In addition,based on the perturbed-chain statistical associating fluid theory(PC-SAFT) and the propylene polymerization mechanism catalyzed by Ziegler-Natta catalyst,the propylene polymerization kinetics was obtained.Simultaneously,the polymerization kinetic parameters were obtained through the industrial dada provided via literature.Accordingly,the whole process model of the HYPOL technology was developed.The comparison between the simulated and plant data showed that they were in good agreement with each other.The model was also used to investigate the effects of the main operation parameters on the propylene polymerization under steady-state condition.The results indicated that the polymer melt index(MI) increased and the number average relative molecular mass(Mn) of the polymer and its polydispersity index(PDI) both decreased with the increase of the H2 flow rate.The polymer yield increased with the increase of the feed flow rate of catalyst and propylene.中国石油天然气股份有限公司兰州石油化工研究中心资助项

Intraparticle Mass and Heat Transport Model of Polypropylene in a Loop Reactor

针对环管反应器中zIEglEr-nATTA催化剂催化的聚丙烯颗粒增长过程,采用多层模型建立了聚丙烯颗粒内部的质量与热量传递预测模型。通过模型模拟得到聚丙烯颗粒内部的丙烯单体浓度梯度和温度梯度。此外,通过模型分析了聚丙烯颗粒的增长规律。结果表明,环管反应器中的聚丙烯颗粒内部的单体浓度梯度明显,该浓度梯度值随扩散系数的增大而减小,随催化剂初始粒径减小而减小;相比于浓度梯度而言,聚丙烯颗粒内部的温度梯度并不明显,温度值随聚合进行而增加,温度梯度则随催化剂初始粒径的增加而增加;不同大小的催化剂颗粒增长得到的聚丙烯颗粒的增长倍数不同。In the present study,the multilayer model(MLM)was used to describe the intraparticle mass and heat transport phenomena of polypropylene produced by propylene polymerization with the Ziegler-Natta catalyst in a loop reactor.Accordingly,the monomer concentration gradient and temperature gradient in the polymer particles and the rule of polymer particle growth were obtained based on the MLM.The results show that the intraparticle monomer concentration gradient is obvious,while the intraparticle temperature gradient is not so evident.Moreover,the simulated intraparticle monomer concentration gradient decreases with the increase of the value of the diffusion coefficient and decreases with the decrease of the original catalyst particle size.In addition,the intraparticle temperature increases with the increase of the polymerization time and the intraparticle temperature gradient increases with the increase of the catalyst original particle size.The results also show that the growth multiple of the polypropylene particle changes with the change of the original particle diameter of the catalyst.中国石油化工股份有限公司资助项目(x505029

ANALYSIS ON INFLUENCING FACTORS OF PARTICLE SIZE DISTRIBUTION IN PROPYLENE POLYMERIZATION LOOP REACTOR BASED ON PARTICLE POPULATION

在液相本体法环管反应器聚丙烯生产过程中,聚丙烯颗粒粒径分布影响聚合速率、气力输送、后处理工序生产成本和最终的聚丙烯物性,特别是对后续工序有流化床烯烃共聚的工艺有重要影响。为预测环管反应器中聚丙烯的粒径分布,考察各操作变量和动力学参数对聚丙烯粒径分布的影响,运用了粒群衡算方法。在综合分析环管反应器中物料流型、聚丙烯颗粒动力学和聚丙烯颗粒生长的基础上,建立了稳态操作时聚丙烯颗粒粒径分布预测模型。模型计算结果表明,当单一粒径催化剂进料时,随着催化剂粒径或是预聚合与主聚合反应温度的增加,聚丙烯粒径分布向大粒径方向偏移,且分布变宽;相比于反应温度,催化剂粒径作用更为显著。同时发现,丙烯进料流速对聚丙烯粒径分布的影响很小。在催化剂粒径有分布的情况下,不同粒径催化剂的质量比不但影响聚丙烯的平均粒径,而且也影响其粒径分布曲线,并在一定的质量比下会出现双峰颗粒粒径分布曲线。In a propylene polymerization loop reactor,polymerization rate,fluid transport,and cost of post-treatment after polymeric process and polymer properties may be affected by polymer particle size distribution,especially when a co-polymerization technology including olefin polymerization fluidized-bed reactor is followed.In order to investigate the effects of operation parameters and kinetics parameters on the polypropylene particle size distribution in the loop reactor,a steady-state particle size distribution model was developed,in which the flow type in the loop reactor,polypropylene particle dynamics and the particle growth were taken synthetically into account based on the mass balance and solid population balance.The result showed that for uniform size catalyst feed,by increasing either initial catalyst size or the reaction temperature of the main polymeric reactor,the polypropylene particle size distribution in loop reactors became boarder and shifted to larger size,in comparison with the reaction temperature,the effect of catalyst particle size was obvious.The effect of propylene feed rate on polypropylene particle size distribution was much smaller.It's also shown that the ratio of catalyst masses with different sizes in the case of multi-size catalyst feed strongly affected not only the average polypropylene particle size,but also the particle size distribution in the loop reactor.Bimodal polypropylene particle size distribution can be obtained by using a catalyst feed with a distinct particle size distribution.国家自然科学基金(20406016);; 中国石油化工股份有限公司福建炼油化工有限公司项目(G7808-06-ZS-1006)资

低温催化裂解烷烃法制备碳纳米管

低温催化裂解烷烃法制备碳纳米管陈萍，王培峰，林国栋，张鸿斌，蔡启瑞（厦门大学化学系固体表面物理化学国家重点实验室，厦门，３６１００５）关键词碳纳米管，催化裂解，甲烷碳纳米管的制备与研究是国际上新材料领域的探索热点［１］．由于具有纳米级的管径，碳纳米管..

Process technology on recovery of sulphur from copper-bearing gold concentrate by using kerosene method

某含铜金精矿尾矿浸铜渣中含有质量分数约15%的单质硫,严重影响后续提金过程的氰化效果。实验进行了以煤油为溶剂的提硫过程研究,考察溶硫时间、温度、液固质量比等因素。实验表明:采用煤油二段浸取法,当工艺条件为液固质量比2—3,温度140℃,加热40MIn,单质硫的回收率为98.4%,纯度达99%以上。对硫化矿处理过程尾矿中硫的回收,采用煤油为溶媒,是一种有效、环保的清洁生产过程,可以提高贵金属及伴生硫的综合回收率,易于工业应用。In the residues of copper-bearing gold concentrate there is mass fraction 15% sulfur which influences the effect of latish cyanogenation.The experiment was carried out with kerosene as solvent in sulfur removal process and the effect of leaching temperature and time,the mass ratio of kerosene to residue (liquid to solid) on the experiment was investigated.The results show that when the mass ratio of kerosene to residue is 2-3,heating temperature is 140 ℃,heating time is 40 min,the recovery efficiency of sulfur can be more than 98.4%,the purity of sulfur can be more than 99%.The new hydrometallurgical method which uses kerosene as solvent is an effective and clean process.It can improve comprehensive recovery efficiency of precious metals and sulfur,and is easy for industrialization without pollution

甲烷在流态化催化剂床裂解生长多壁碳纳米管

在常压、823～873K、流化床反应条件下,用自行研制的Ni0.5Mg0.5O催化剂,催化甲烷分解生长碳纳 米管(CNTs),考察催化剂床层由固定床过渡到流化床状态的条件及其对制管过程的影响。结果表明,在 Φ32mm管式反应器及相应供热工况条件下,其流化床操作条件以管壁温度控制在约853K、原料气CH4线速 v为18～22cm/s、空速GHSV为3×104～6×104mL(STP) CH4/(h·g)为宜;反应1.0h,最高产率达 10g CNTs/g,这相当于固定床将制管反应时间延长至4～5h的产率水平。所得CNTs产物经TEM、SEM、 TPH、XRD和LRS等测试技术表征。结果表明,其为多壁碳纳米管(MWCNTs),外管径在10～50nm范围;纯 化后的CNTs产物含碳量≥99.5%,石墨状碳含量≥90%

Development and fluidized simulation of semi-continuous pilot reactor for carbon nanotubes preparation

第一作者：朱丽（1980—），女，硕士研究生，从事化工过程开发与设计研究。E-mail:[email protected]。联系人：汤培平，教授。E-mail:[email protected]。[中文文摘]在间歇过程的碳纳米管制备实验基础上结合经验公式,开发设计了制备碳纳米管的半连续中试流化床反应器,结果表明:催化剂100 g、反应温度650℃时,甲烷平均转化率23.2%,碳纳米管产率为177.5 g/h,操作周期为间歇反应器的1/3,反应器可较好地实现碳纳米管制备功能。用计算流体力学方法对此反应器内的气固两相流化行为进行数值模拟,得到在工况条件下,最佳的催化剂用量为100 g、操作气速为0.15 m/s等工艺参数。[英文文摘]Semi-continuous pilot test fluidized bed reactor for carbon nanotubes preparation was designed and fabricated,base on experiments of batch fluidized bed reactor and repeated calculations.When reaction temperature is 650 ℃,reaction time is 4 h,velocity of CH4,H2,N2 are 0.1m/s,0.008 m/s,0.016 m/s,the yield of carbon nanotubes is 177.5 g/h,conversion of CH4 is 23.2%,production cycle is shortened by 2/3.The fluidization behavior of gas-solid fluidization process was calculated by using the computational fluid dynamics(CFD) package Fluent6.1.And the optimal condition for carbon nanotubes is that the velocity of CH4 is 0.1m/s,and catalyst is 100g