环隙气升式气固环流反应器内颗粒速度特性

针对中心气升式气固环流反应器在工业化中暴露出来的问题,提出了一种新型的环隙气升式气固环流反应器,并建立了一套大型的冷态实验装置（装置总高4．56m,环流反应器筒体外径300mm）来考察环隙气升式气固环流反应器内颗粒速度特性。操作条件为环隙区表观气速0.10-0.54m／s,导流筒区表观气速0.059-0.200m／s。分别测量了环流反应器环流段内颗粒的密度和速度,基于实验数据对催化剂颗粒的运动速度和环流推动力进行系统分析。结果表明,环隙区颗粒分布形式为“中心稀两边浓”;环隙气升式气固环流反应器内,颗粒环流速度随着环隙区表观气速的增大而增大,而环流速度梯度逐步减小。随着导流筒高径比H／D的增大,环隙气升式气固环流反应器的环流推动力增大而颗粒环流速度减小。     

生物降解聚对苯二甲酸丁二醇酯-co-聚己二酸丁二醇酯的热分解行为研究

合成了聚对苯二甲酸丁二醇酯-co-聚己二酸丁二醇酯(PBAT),利用热重分析法研究了PBAT的热稳定性,并采用Ozawa-Flynn-Wall方法研究了PBAT的非恒温热分解行为、动力学参数和恒温分解过程中端基及黏数变化及其分解速率常数。讨论了升温速率对分解行为的影响,失重率对PBAT分解活化能的影响,时间对端羧基和黏数的影响。结果表明,PBAT热分解活化能为202 kJ/mol,端羧基增加和黏数降低与时间为线性关系,不存在自催化。     

Isothermal Curing Kinetics and Thermal Degradation of o-CFER/MeTHPA/O-MMT Nanocomposite

The isothermal curing kinetics of nanocomposite of o-cresol-formaldehyde epoxy resin (o-CFER), 3-methyl-tetrahydrophthalic anhydride (MeTHPA) with organic montmorillonite (O-MMT) were investigated by means of X-ray diffraction (XRD) and differential scanning calorimetry (DSC) using N,N-dimethyl-benzylamine as a curing accelerant. The XRD result indicates that an exfoliated O-MMT nanocomposite was obtained. The analysis of DSC data indicated that an autocatalytic behavior appeared in the first stages of the cure for the system, which could be well described by the Kamal model. In the later stages, the reaction is mainly controlled by diffusion and a diffusion factor, f(α), was introduced into Kamal's equation. In this way, the curing kinetics were predicted well over the entire range of conversion. The thermal degradation kinetics of this composite were investigated by thermogravimetric analysis (TGA), which revealed that with increasing O-MMT content, TG curves shift to higher temperature.     

Autothermal Reforming of Methanol in an Isothermal Reactor – Concept and Realisation

Based on a new isothermal approach a reactor design for the autothermal reforming of methanol is developed. The new reactor concept addresses the special requirements of mobile applications, such as compact design and good dynamic behaviour. With the catalyst carried in porous disks, an even temperature profile combined with a constant flow distribution can be achieved. The disks provide a copper‐matrix, that fixes the small catalyst‐particles, transports heat and provides an open structure for mass‐transport. Therefore heat and mass transfer are not limiting, and the reactor is operated at optimum temperature, resulting in high reaction rates with low concentrations of by‐products like carbon monoxide or methane. There are no changing temperature profiles and negligible product‐fluctuations as a response to load steps of more than one order of magnitude. This enables the easy and precise control of the reaction. For start‐up the reactor is heated by catalytic oxidation of methanol. Starting from room‐temperature, a temperature of 300 °C is reached within less than a minute.     

Thermal Conductivity Measurement of Bulk Solids

The coefficient of thermal conductivity of particulates and powders is of great importance in process engineering. The prediction of thermal properties of powders using empirical equations is still difficult due to the wide range of specific attributes. This article describes a new measurement methodology for a laboratory device that can be used to determine the thermal conductivity of bulk solids. The presented results show that the created device is highly applicable in industrial practice. It is possible to examine the coefficient of thermal conductivity depending on the sample temperature, the granulometry results and the morphological composition, the moisture content, the degree of consolidation, and other variables that may enter into the entire process and affect it significantly.     

Investigation into Photocatalytic Degradation of Gaseous Benzene in a Circulated Photocatalytic Reactor (CPCR)

Due to the fact that suspended TiO₂ powder enjoys free contact with gaseous pollutant molecules in photocatalytic reactors, it can generally achieve better efficiency than immobilized TiO₂ catalysts. However, difficulties with the separation of this catalyst powder from treated pollutants and its re‐use often limit its application. Therefore, a circulated photocatalytic reactor (CPCR) was designed to enhance the performance of the photocatalytic degradation of gaseous benzene. TiO₂ film photocatalysts were prepared by the sol‐gel method at low temperatures and coated onto the inner wall of this reactor by a bonding agent composed of poly‐(2, 2‐dimethyl)‐acrylic ethylene ester emulsion in which TiO₂ powder was characterized by FTIR, TEM and SEM. In particular, the influences of initial concentration and gas flow rate of benzene on the degradation conversion, D_p, apparent reaction rate constants, k_r, initial degradation rate, r, and the deactivation and regeneration of catalyst in the CPCR, were investigated. The results indicated that the degradation conversion, apparent reaction rate constants and initial degradation rate were closely correlated to the initial concentration of benzene. To elucidate the factors governing the observations, the adsorption characteristics and kinetics of the photocatalytic degradation of benzene were analyzed using the Langmuir adsorption isotherm and Langmuir‐Hinshelwood kinetic model. It was found that the reaction kinetics were best described by a fixed pseudo‐first‐order kinetic equation of photocatalytic degradation of gaseous benzene in the CPCR.     

Heats of Mixing Using an Isothermal Titration Calorimeter: Associated Thermal Effects

The correct determination of the energy generated or absorbed in the sample cell of an Isothermal Titration Calorimeter (ITC) requires a thorough analysis of the calorimetric signal. This means the identification and quantification of any thermal effect inherent to the working method. In this work, it is carried out a review on several thermal effects, studied by us in previous work, and which appear when an ITC is used for measuring the heats of mixing of liquids in a continuous mode. These effects are due to: (i) the difference between the temperature of the injected liquid and the temperature of the mixture during the mixing process, (ii) the increase of the liquid volume located in the mixing cell and (iii) the stirring velocity. Besides, methods for the identification and quantification of the mentioned effects are suggested.     

无卤阻燃SBR的阻燃性能及热失重行为

利用锥形量热仪(CONE)和热失重分析(TG)研究了化学膨胀阻燃剂(IFR)、氢氧化铝/红磷(Al(OH)3/P)及二者复合阻燃SBR的阻燃性能及热失重行为。结果表明,阻燃剂用量为40份,聚磷酸铵(APP)与季戊四醇(PER)质量比为3∶1时,SBR/APP/PER的热释放速率及生烟速率均大幅度下降,阻燃效果较好;Al(OH)3与P质量比为26∶14时,可有效降低SBR/Al(OH)3/P的热释放速率,但生烟速率较大;将APP/PER∶Al(OH)3/P=1∶1复配,SBR/IFR/Al(OH)3/P的热释放速率和生烟速率没有进一步改善,协同效应不明显。热失重研究表明,空气气氛下,试样SBR/IFR/Al(OH)3/P在300~500℃时,Al(OH)3/P反应使得SBR分解速度下降;在500~800℃时,APP与PER形成炭层,有效地起到隔热隔氧的作用,从而抑制炭黑的分解;两者复合使用,使阻燃SBR分解速度降低,热稳定性提高。     

热重-红外联用方法在药物热降解和热氧降解研究上的应用

通过用热重 -红外联用方法 (TG -IR)研究药物氯甲双磷酸钠 (NaHPO3 ) 2 CCl2 4H2 O在空气流中的热氧降解过程 ,取得很好的结果 ,证明热重 -红外联用是研究药物热氧降解历程的好方法。     

Thermal Degradation of Polystyrene

The thermal degradation of polystyrene in the absence of oxygen is examined, at temperatures above or below 300°C. The decrease in degree of polymerisation occurring either with negligible volatilisation at lower temperatures, or with evolution of low molecular weight products at higher temperatures, is simulated by Monte-Carlo procedures. The results suggest that below 300°C, scission of the polymer chains is random, and involves also a minor fraction of some abnormal, as yet unidentified, structures. Above 300°C, an extensive intermolecular transfer process seems to be the main cause of the decrease in degree of polymerisation, whereas an overall depolymerisation of 100 structural units at each chain scission is the source of volatilisation.     

三维电极反应器降解甲基叔丁基醚

主要考察了三维电极反应器对地下水污染物甲基叔丁基醚(MTBE)降解效果。实验分别从温度、初始浓度、Fe2+浓度等方面,探究了三维电极反应器对MTBE去除效果的影响。由实验结果可得:当温度为25℃、Fe2+初始浓度为1 mmol/L、pH=3时,初始浓度为1 mmol/L的MTBE溶液,在150分钟内的去除效率可以达到75%以上。     

热降解动力学方法研究ABS的降解机理

在空气气氛下,采用热重分析(TGA)研究了不同升温速率下丙烯腈-丁二烯-苯乙烯共聚物（ABS）的热降解过程,分别使用Flynn-Wall-Ozawa法和Kissinger法对降解过程进行动力学分析。结果表明,ABS降解包含2个阶段,350~450 ℃之间发生降解反应,同时伴有交联反应,降解活化能（Ea）在200 kJ/mol左右,转化率在80 %~90 %时发生炭化反应,Ea提高到262.81 kJ/mol;500~600 ℃之间是残炭的氧化,Ea降低到130 kJ/mol左右,炭层稳定性较差。ABS的降解过程反应级数为0.946,降解受到随机成核与生长机理控制,降解在ABS基体内进行,而不是表面,所以降解气体燃烧不完全,易产生黑烟和熔融滴落。     

流化床-提升管耦合反应器内固含率的轴向分布及流动发展

在耦合流化床反应器大型冷模实验装置上,考察了不同表观气速下FCC颗粒在耦合流化床内截面平均密度的轴向分布. 结果表明,反应器轴向固含率可分为底部流化床区域和上部提升管区域. 前者的密相区平均固含率随表观气速增大而减小;后者的平均固含率随表观气速Ug增大而增大,Ug<0.58 m/s时固含率分布均匀,Ug=0.70~1.04 m/s时提升管出口出现约束返混区(>8.62 m),Ug>1.16 m/s时提升管底部出现密度重整区(3.82~4.57 m)、加速平稳区(4.57~8.62 m)和出口返混区(>8.62 m). 确定了耦合反应器内提升管区域截面平均固含率的影响参数,并利用实验数据回归了平均固含率的轴向分布经验模型,计算值与实验值吻合较好.     

碳二加氢等温反应器在大庆乙烯装置中的应用

介绍了碳二加氢等温反应器ER-424A/B在大庆乙烯装置中的应用情况。碳二加氢等温反应器ER-424A/B具有活性高、选择性好、运行周期长等特点，在碳二加氢反应器中具有独特的加氢效果。     

Thermal Fluctuations Limit the Adhesive Strength of Compliant Solids

For compliant solids, the stress required to separate an interface (its adhesive strength) appears to be much lower than that calculated by computing intersurface interactions. We explore the hypothesis that the adhesive strength is limited in value by thermal fluctuations. In a simple model of an interface, molecules bridging the two surfaces are represented by linear entropic springs. Asymptotic and numerical analyses are carried out to evaluate the adhesive strength and effective work of adhesion. For stiff materials, adhesive strength is found to be equal to the intrinsic strength—the maximum value of intersurface stress computed ignoring fluctuations. For compliant materials, adhesive strength is significantly reduced and is on the order of the elastic modulus. The effective work of adhesion agrees with the intrinsic work of adhesion for stiff materials and can decay slowly with increasing compliance.     

Thermal Fluctuations Limit the Adhesive Strength of Compliant Solids

For compliant solids, the stress required to separate an interface (its adhesive strength) appears to be much lower than that calculated by computing intersurface interactions. We explore the hypothesis that the adhesive strength is limited in value by thermal fluctuations. In a simple model of an interface, molecules bridging the two surfaces are represented by linear entropic springs. Asymptotic and numerical analyses are carried out to evaluate the adhesive strength and effective work of adhesion. For stiff materials, adhesive strength is found to be equal to the intrinsic strength—the maximum value of intersurface stress computed ignoring fluctuations. For compliant materials, adhesive strength is significantly reduced and is on the order of the elastic modulus. The effective work of adhesion agrees with the intrinsic work of adhesion for stiff materials and can decay slowly with increasing compliance.     

Thermal Degradation of some Azines

The thermal characteristics of tetraformaltrisazine and formalazine were studied for the first time using differential thermal analyser, thermogravimetric analyser and mass spectrometer. Kinetic analysis of the degradation of each of these compounds and the effect of enveloping atmosphere on the degradation are reported. Degradation mechanisms have been postulated. Based on values of activation energy and supported by evidences made available by mass spectrometric studies it has been concluded that the second stage of thermal degradation of tetraformaltrisazine and formalazine in inert atmosphere may be ascribed to N-N bond rupture. The heats of degradation of tetraformaltrisazine and formalazine were determined by differential scanning calorimeter. The Values obtained are + 360.4 ± 0.5 cal/g and + 105.8 ± 0.7 cal/g respectively.     

Thermal Processing of Particulate Solids in a Gas-Fired Pulse Combustion System

Abstract

An experimental study on thermal processing of particulate solids has been carried out on a valved pulse combustion unit. The test-bench consists of a 60 kW natural gas-fired valved (flappers) pulse combustor having a 4.63 × 10^?3 m³ combustion chamber, horizontal tailpipe with variable geometry, and a cylindrical drum. The particulate solid used is clean sand (311 µm and 2646 kg/m³), which flows within the tailpipe and the cylindrical drum located at its end. The sand flowrate was varied from 10 to 50 kg/h and it was heated from 20 to 600°C. Local pressure measurements showed clearly that the propagation of sonic waves remain stable when they are in direct contact with the sand particles. The heating time of sand particles in the pulsed system was found shorter than the one observed when operating with a conventional burner under the same conditions; this resulted in a 25.5% reduction of natural gas consumption.