PX氧化反应-结晶-精馏耦合过程模型

PX氧化是一个气液固三相复杂反应过程,反应同时伴随着吸收、蒸发、放热、结晶等多种耦合的物理化学效应,反应器采用反应段(下部)与精馏段(上部)一体化结构.在已有工作基础上,全面考虑了反应、传递、结晶、精馏多种过程之间的耦合作用,建立了氧化反应器的综合数学模型.模型给出了反应动力学、相平衡、流动与传递、结晶动力学等各类模型与参数的计算方法,计算结果与工业现场数据吻合.通过模型模拟考察了各工艺条件对反应器操作性能的影响,提出了工业装置改造和优化的方向与措施.     

含H2S酸性气体处理新工艺过程研究

由化学吸收过程和电解反应过程构成的双反应工艺过程,处理炼油厂或油田含H2S酸性气体.在化学吸收过程中,H2S被氧化成固体硫磺;在电解反应过程中,由H2S生成的H+被还原成H2.现场放大实验结果表明,该工艺过程是可行的.在适宜的操作条件下,H2S的吸收率可达到99%以上,制得的硫磺纯度高于99.8%.对于化学吸收过程,适宜的操作条件为吸收剂中含Fe3+浓度大于2.5mol/L,操作温度为60℃,液气比1.5～3.0.     

含H2S酸性气体处理新工艺过程研究

由化学吸收过程和电解反应过程构成的双反应工艺过程,处理炼油厂或油田含H2S酸性气体.在化学吸收过程中,H2S被氧化成固体硫磺;在电解反应过程中,由H2S生成的H 被还原成H2.现场放大实验结果表明,该工艺过程是可行的.在适宜的操作条件下,H2S的吸收率可达到99%以上,制得的硫磺纯度高于99.8%.对于化学吸收过程,适宜的操作条件为:吸收剂中含Fe3 浓度大于2.5mol/L,操作温度为60℃,液气比1.5～3.0.     

沥青基带状纤维的预氧化研究

采用熔融纺丝工艺制备中间相沥青基带状纤维,分别于不同温度和不同时间进行氧化稳定化处理,采用红外光谱仪和元素分析测定预氧化纤维官能团和氧含量的变化,并采用扫描电镜和纤维强伸度仪等检测设备研究2 500℃石墨化纤维的结构和性能.实验结果表明：沥青分子在预氧化过程中与氧发生反应,生成了热固性的沥青大分子.氧化温度越高,氧化时间越长,带状纤维的氧含量越高.厚度为～35μm,宽度为～380μm的带状沥青纤维于氧气气氛经220℃下预氧化20h和2 500℃石墨化处理后,其拉伸强度可达1.75GPa,比240℃和260℃预氧化制得的石墨纤维的拉伸强度高.     

对二甲苯直接电解氧化反应的研究

研究了在有机溶剂、支持电解质和碳棒存在下，对二甲苯的直接电解氧化反应，使用GC－MS方法分析鉴定了主要电解氧化产物，讨论了电解氧化产物成分随电解时间的变化规律，提出了对二甲苯的直接电解氧化反应过程。     

液相氧化反应失控过程的动态流程模拟

随着化工工业现代化、绿色化概念的普及,氧化工艺特别是新型氧化工艺在当前工艺中所占比重日益增加,但氧化反应多为强放热反应,反应所涉及的物料往往也具有不稳定性. 为防止反应安全事故的发生,有必要进行系统的反应安全性研究. 针对液相氧化反应,本工作利用流程模拟手段,建立了带控制条件的半间歇动态反应器模型. 介绍了反应器模型的结构、传热设置和工艺控制设置方案. 选择丙烯环氧化反应开展了模拟研究,设置了相关的动力学参数和反应器参数. 通过模拟正常反应过程对设计的反应器参数进行核算,证明在正常工艺条件下可保证反应平稳进行. 利用所建立的模型模拟了密闭绝热、冷却失效和冷却水调节阀故障条件下的多场景反应危险性,得到了各场景下反应器温度、压力和反应器内物料组成的变化曲线,为后续工作中制定合理的安全控制措施提供数据支持.     

铱-钽氧化物涂层阳极氧化再生酸性蚀刻液

采用Ir-Ta氧化物涂层阳极(DSA)和直流电解法研究了酸性蚀刻液的阳极氧化再生回用过程.酸性蚀刻液在Ir-Ta氧化物涂层阳极的氧化再生过程中发生浓差极化,电极反应速率为Cu+离子扩散传质所控制,极限电流密度与Cu+离子浓度和温度成正比,采用小于或等于极限电流密度的电流密度进行阳极氧化时不析出氯气.酸性蚀刻液阳极氧化再生的电流密度小,槽电压低,电解能耗少,电流效率可达到100%.阳极氧化再生后酸性蚀刻液的蚀刻能力与双氧水再生的相近,完全可以替代双氧水再生.     

催化液化气脱硫醇装置技术改造

介绍了催化液化气脱硫醇装置改造为纤维液膜处理技术的过程。采用纤维液膜反应器提高碱液和液化气中硫醇的反应速率和反应深度,降低碱洗流量,从而降低氧化再生负荷。采取增加氧化塔气体分布器、增加碱液—二硫化物分离塔聚结器等措施提高碱液中二硫化物的脱除效果,最终降低装置的碱渣排放。     

MTP反应系统设计及相关控制探析

MTP装置MTP反应器有3台,正常运行时2台反应器处于反应状态,1台反应器为再生或备用状态,因为MTP反应器是两台同时运行且反应过程为强放热反应,为了保证反应器的进料均衡以及能够对反应过程进行有效的控制,在反应过程的控制上做了很多文章,结合流程对MTP反应系统的设计及整个控制进行进一步的探讨。     

一九七六年农药文摘

761001 电化法制菲醌中间试验(50吨/年)技术总结——博山农药厂、山东省化学石油研究所《山东化工》1976,№1,4～12 菲醌经试验对小麦、玉米、谷子、糜子等黑穗病和小麦杆黑粉病,有较高的防治效果,可代替汞制剂。中试技术路线采用一步电解氧化法,即电解再生铬酸与铬酸氧化菲醌在一个反应器(电解槽)中进行。电解温度50～65℃,电解液组成:H_2SO_4450克/升,Cr_2O_3120克/升,投工业菲量:31克/升电解液。在此条件下电解再生形成的Cr~( 6)及时与菲反应生成菲醌,Cr~( 3)又迅速在阳极上被氧化。中试对电解氧化条件、不同原料对反应的影响、含铬废水的处理进行了试验。采用菲含量达65%以上、咔唑含量不超过30%、含油量不超过0.2%的工业菲,可获得菲醌含量50%以上的产品,理论收率64%,菲转化率85%。‘     

A REACTOR WITH CATALYTIC MEMBRANE PERMEATED BY HYDROGEN

A hydrogenation reactor with palladium as a membrane selectively permeated by hydrogen was designed. This reactor has some advantageous characteristics: (1) Reaction by permeate hydrogen makes it possible to omit one separation process. (2) Reaction rate is controlled by changing the permeation rate through the hydrogen pressure. In the present study, it was elucidated that the reaction by permeate hydrogen was much faster than that by gaseous hydrogen when the other reactant affected the hydrogen adsorption strongly.     

Microwave irradiation of nadic-end-capped polyimide resin (RP-46) and glass–graphite–RP-46 composites: cure and process studies

Microwave energy was investigated to cure nadic-end-capped polyimide precursors (RP-46 resin) using a Cober Electronics Model LBM 1.2A/7703 microwave oven at a frequency of 2.45 GHz. Both neat resin samples and glass cloth and hybrid glass cloth–graphite cloth–RP-46 resin composites were studied. For the resin studies, the effect of various parameters, such as power level, sample size, processing temperature, time, and graphite fiber absorber, were investigated. The variables investigated with the composite study were the power level, mold material, vacuum, and low pressure. The results showed that microwave energy was effective in curing both neat resin samples and composite specimens. The presence of a small quantity of absorber (chopped carbon fiber) accelerates the cure dramatically. Moreover, soapstone mold material was found to be an efficient absorber for glass and glass–graphite composite processing, causing an effective cure in less than 1 h. Glass and glass–graphite hybrid composites with flexural strengths of 372–588 MPa (54–85 ksi) and moduli of 28.7–31.7 GPa (4.2–4.6 Msi) have been fabricated. This is equivalent to 50 to 80% of the properties of composites fabricated by conventional means. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 73: 2391–2411, 1999     

MONITORING THE HYDROGEN RELEASE FROM COAL LIQUID SOLVENTS USING A HYDROGEN PROBE

A hydrogen probe made of nickel tubing has been used to monitor the release of hydrogen from coal liquid solvents at elevated temperatures and pressures. A knowledge of this release rate is helpful in determining the overall hydrogen balance for coal liquefaction operations, in choosing among alternative solvents and in evaluating the validity of model compounds. The hydrogen release was found for coal liquids to reach a constant value when the reactor temperature was steady. In the case of some model compounds the amount of hydrogen released continued to increase and equilibrium was not attained during a 10 hours measurement period. For the coal liquids the total pressure of the system was found to increase sharply with time indicating the production of gases other than hydrogen, while for the model compounds the total pressure increases were almost parallel to the increases of the hydrogen partial pressure. A correlation was developed for the percentage of hydrogen released with the aromatic fraction distribution in the coal liquids. The hydrogen probe was a valuable instrument for continuously following the hydrogen changes in these dehydrogenation experiments.     

HIGH-TEMPERATURE SOLAR CHEMICAL REACTORS FOR HYDROGEN PRODUCTION FROM NATURAL GAS CRACKING

This study deals with the thermal cracking of natural gas for the coproduction of hydrogen and carbon black from concentrated solar energy without CO₂ emission. A laboratory-scale solar reactor (1 kW) was tested and modeled successfully. It consists of a tubular graphite receiver directly absorbing solar radiation, in which a mixture of Ar and CH₄ flows. A temperature increase or a gas flow rate decrease results in chemical conversion increase. Methane conversion higher than 75% was obtained. Reaction occurred near the wall where temperature is maximal and gas velocity is minimal due to the laminar flow profile. The work focused also on the design of a medium-scale tubular solar reactor (10 kW) based on the indirect heating concept. A reactor model including gas hydrodynamics and heat and mass transfers coupled to the chemical reaction was developed in order to predict the reactor performances. Temperature and species concentration profiles and final chemical conversion were quantified. According to the results, temperature was uniform in the tubular reaction zone and the predicted chemical conversion was 65%, neglecting the catalytic effect of carbon particles.     

Disintegration of graphite matrix from the simulative high temperature gas-cooled reactor fuel element by electrochemical method

Electrochemical method with salt as electrolyte has been studied to disintegrate the graphite matrix from the simulative high temperature gas-cooled reactor fuel elements. Ammonium nitrate was experimentally chosen as the appropriate electrolyte. The volume average diameter of disintegrated graphite fragments is about 100 μm and the maximal value is less than 900 μm. After disintegration, the weight of graphite is found to increase by about 20% without the release of a large amount of CO₂ probably owing to the partial oxidation to graphite in electrochemical process. The present work indicates that the improved electrochemical method has the potential to reduce the secondary nuclear waste and is a promising option to disintegrate graphite matrix from high temperature gas-cooled reactor spent fuel elements in the head-end of reprocessing.     

Calculation of effective conductivity profile of electrochemical reactor with flow-type three-dimensional electrodes

We have set the problem of calculating the optimum conductivity profile of an electrochemical reactor with flow-type three-dimensional electrodes made of a graphite fiber material on the basis of the criterion of uniformity of the through-thickness distribution of electroactive components within the electrode. The results of calculations and experimental studies are presented.     

催化-分离脱氢膜反应器的透氢性能研究

1 前言在化学化工领域中利用膜材料的选择性渗透和催化作用来改善反应性能正越来越受到人们的重视。与传统的颗粒状催化剂-固定床反应器体系相比较,膜催化反应器在质量传递、热量传递和活化反应物方面有较大的差异。例如,用传统的固定床反应器由于受热力     

耦合相变储热的金属氢化物反应器吸氢过程模拟

基于金属氢化物储氢反应,建立了相变材料蓄热的固体储氢反应器模型,模拟研究了吸氢压力等操作参数及相变材料的相变温度、固(液)态导热系数、相变潜热等物性参数对固体储氢反应器工作过程的影响. 结果表明,相变材料的固态导热系数和相变潜热对固体储氢反应器性能的影响较小,相变温度和液态导热系数对反应器性能影响较大. 相变温度越低,液态导热系数越大,储氢反应器性能越好. 在使用最优的相变材料储能时,提高充入氢气的压力可加快反应速率,强化相变材料的传热,有助于进一步优化反应器的储氢性能.     

Improvement on the electrochemical characteristics of graphite anodes by coating of the pyrolytic carbon using tumbling chemical vapor deposition

The electrochemical characteristics of graphite coated with pyrolytic carbon materials using tumbling chemical vapor deposition (CVD) process have been studied for the active material of anodes in lithium ion secondary batteries. Coating of pyrolytic carbons on the surface of graphite particles, which tumble in a rotating reactor tube, was performed through the pyrolysis of liquid propane gas (LPG). The surface morphology of these graphite particles coated with pyrolytic carbon has been observed with scanning electron microscopy (SEM). The surface of graphite particles can well be covered with pyrolytic carbon by tumbling CVD. High-resolution transmission electron microscopy (HRTEM) image of these carbon particles shows that the core part is highly ordered carbon, while the shell part is disordered carbon. We have found that the new-type carbon obtained from tumbling CVD has a uniform core (graphite)-shell (pyrolytic carbon) structure. The electrochemical property of the new-type carbons has been examined using a charge-discharge cycler. The coating of pyrolytic carbon on the surface of graphite can effectively reduce the initial irreversible capacity by 47.5%. Cyclability and rate-capability of theses carbons with the core-shell structure are much better than those of bare graphite. From electrochemical impedance spectroscopy (EIS) spectra, it is found that the coating of pyrolytic carbon on the surface of graphite causes the decrease of the contact resistance in the carbon electrodes, which means the formation of solid electrolyte interface (SEI) layer is suppressed. We suggest that coating of pyrolytic carbon by the tumbling CVD is an effective method in improving the electrochemical properties of graphite electrodes for lithium ion secondary batteries.     

Selective recovery of gold from spent gold sulphite solutions by electrodeposition on graphite cloth electrodes

A flow-through cell, employing an array of twin graphite cloth electrodes and connected to a charge injector potentiostat was employed for the electroseparation of gold from gold sulphite, Au(SO₃) ₂ ^3– , solution containing cadmium, copper and chloride ions. The high overvoltage for the reduction of gold ions in this medium prevents its selective deposition (copper codeposits and hydrogen gas evolves at the same time). Hydrogen peroxide, added judiciously, oxidizes sulphite to sulphate; the gold Au(I) ions complex with chloride, establishing a system similar in its electrochemical behaviour to one previously discussed. Gold chloride, [AuCl₂]^–, solutions disproportionate readily; to minimize this process, a double flow-through system was built, in which the sulphite and hydrogen peroxide solutions enter a small mixing chamber as separate streams, are mixed in the appropriate ratio and allowed to react only a few minutes before reaching the electrodes. Gold deposits on the first graphite screen, and cadmium and copper deposit partially on the next screen, providing an economical approach to the continuous recovery and/or separation of gold from gold sulphite effluents containing base metal admixtures.