纸箱厂锅炉冷凝水开闭式回收分析

通过对一家纸箱厂锅炉冷凝水开闭式回收改造近四年的持续参与调研,结合实际,通过大量的数据计算与分析,得出开闭式两种冷凝水回收对企业所产生的效益,闭式回收系统是开式回收系统效益的两倍。     

CaSO4氢气下还原分解的热重研究

在ＴＧ－１５１加压热天平上,对常压和加压氢气气氛下ＣａＳＯ４的分解反应进行了研究,并采用ＸＲＤ技术对不同反应条件下的产物进行分析测试,结果表明：在氢气还原气氛下升高温度和压力都导致ＣａＳＯ４还原分解速率快,ＣａＳＯ４分解产物主要是ＧａＳ;在１０００℃时ＣａＳＯ４和ＣａＳ之间可以发生固－固反应生成ＣａＯ。     

印尼油砂热重红外及基于AKTS动力学分析

通过热重分析仪、傅里叶红外光谱仪和质谱仪对印尼油砂的热解过程和热解产物进行了探究,基于不同升温速率下的TG-DTG曲线,将热解过程分为两个阶段,即热解低碳化合物析出段和无机物高温受热分解段。升温速率相同时,YN₂油砂比YN1油砂挥发分析出的温度低。油砂热解产物是由脂肪烃、芳香烃、含氧官能团和羟基等组成的混合物,利用傅里叶红外光谱仪探究印尼油砂在不同升温速率下气体产物H₂O、CO₂、CO、CH₄、C_nH_m等的析出特性,气态烃类、含氧有机物等有机气体是由羰基和羧基以及甲氧基、亚甲基、甲基在热解低温段受热分解产生的,根据质谱图,确定了各个时刻逸出气体的种类和产量。利用AKTS软件基于F-W-O和Kissinger模型计算了油砂脱挥发分的热解动力学参数,计算结果表明,在相同的转化率下,不同升温速率的活化能呈线性分布,YN1的活化能高于YN₂的活化能。     

竹材炭化过程的热重分析及动力学研究

采用热重法研究了不同条件下竹材的炭化过程。通过对竹材炭化过程热失重和微分热重曲线的分析,初步探讨了竹材炭化的机理。对所得的热失重曲线进行拟合,计算了炭化反应的动力学参数,其活化能和频率因子分别在40.3～58.8 kJ/mol和336～6230 min^-1的范围内。     

吸湿性纤维热重干燥特性及动力学研究

为研究吸湿性纤维的干燥特性及动力学反应机理,采用非等温热重法对粘胶纤维在30—200℃温度区间范围内的干燥特性进行实验研究,利用等转化率KAS及FWO方法求解干燥过程表观活化能,并借助于固体热解的积分主曲线法(IMP)探讨纤维干燥动力学机制。结果表明:随着升温速率的提升,转化率α(TG)曲线及水分比MR曲线均向高温侧偏移;KAS和FWO方法计算所得的表观活化能值E_a值较为接近,且随转化率α升高而呈现单调性增高;通过最概然机理函数分析发现当干燥过程转化率大于0.5时,干燥过程以直接吸附水分的蒸发为主,更接近于物理化学反应,可由随机成核与随机生长A6机制描述。     

碳热还原镁橄榄石合成MgO-SiC复合粉体的热力学研究

本文对碳热还原镁橄榄石合成MgO-SiC复合粉体进行了热力学研究,结合实验,分析了反应的中间过程,对合成粉体具有重要的指导意义.热力学分析表明:当T=1923 K时,所形成的产物,从容易到困难排序依次为:MgO+SiC,MgO+Si,MgO+SiO,Mg+SiC,Mg+Si,Mg+SiO,Mg+SiO2;增大惰性气体流速,降低CO的分压,可以降低镁橄榄石解构温度.在不同氩气流量下的实验证明,增大氩气流量,促进了镁橄榄石的碳热还原反应,有益于MgO-SiC复合粉体的合成.以镁橄榄石与炭黑物质的量比为1∶5配料,混合均匀后,在氩气保护下,在气体流量分别为100 mL/min,300 mL/min,500 mL/min时,1650℃保温3h合成粉体.用X射线衍射仪(XRD)测试合成的物相,用扫描电子显微镜(SEM)观察各物相形貌.实验结果表明,合成的产物MgO为八面体,SiC为条形.过程分析表明,碳还原镁橄榄石生成MgO和SiO,是合成复合粉体的重要中间过程.     

用于煤气化动力学研究的高温高压热重装置

热重法是在程序控制温度下,连续测量固体样品在反应过程中重量变化的一种技术,由于能直观重量变化,转化率的信息也很容易获得。热重装置还具有微分反应器的特点,并通过合理的设计可以在一定程度上模拟流化床反应器的行为,因此这种装置在     

氟磷灰石碳热还原过程及动力学研究

为探明电炉法黄磷的反应历程,采用纯物质模拟电炉法黄磷生产,并使用HSC热力学软件、X射线衍射(XRD)、扫描电子显微镜(SEM)等分析方法对该过程进行辅助研究。HSC和XRD分析结果表明氟磷灰石碳热还原反应历程如下:Ca_5(PO_4)_3F优先与SiO_2发生脱氟反应生成Ca_3(PO_4)_2,而Ca_3(PO_4)_2又被碳还原产生CaO,并结合SiO_2形成钙硅酸盐,而F最终以SiF_4(g)的形式排出体系;动力学分析结果表明氟磷灰石的碳热还原反应是一个变级反应,反应级数随温度升高而降低,反应速率随温度升高而增大,随时间增大而降低,其反应活化能为188.96 kJ×mol~(-1),表明是一个高能耗反应;渣相SEM分析结果表明随着温度的升高,体系的液相逐渐增多,物质扩散加快,导致反应速率增大,这与动力学分析结果相一致。     

铌酸铁碳热还原的等温动力学分析

在热力学分析的基础上,结合XRD分析,确定了铌酸铁在1000~1300℃下碳热还原的中间产物和最终产物. 采用热重热分析仪测量了氩气保护下含碳铌酸铁以35℃/min升温速率分别从室温加热至1170, 1230, 1290和1320℃并保温40 min的TG-DSC曲线. 根据TG曲线,采用等温热分析法计算了铌酸铁碳热还原反应的动力学参数,确定了反应的限制性环节. 结果表明,铌酸铁碳热还原反应的表观活化能为515.2 kJ/mol,反应的动力学方程为[(1-a)-1/3-1]2=kt,为三维扩散Z-L-T方程. 除了反应的初始阶段外,反应速率是由产物层扩散所控制,即CO气体在产物层中的内扩散为反应的限制性环节.     

松木脱脂行为的热重研究

本文应用热重分析法研究了松木在10℃.m in-1升温速率下,30~700℃的热分解过程,分析了每个阶段的化学物理变化,并比较了干燥脱脂和丙酮脱脂后松木的热解行为,找出高温脱脂的最佳温度为180~200℃。利用松木热重分析曲线求得松木热解脱脂反应为一级反应,表观活化能为93.18KJ.mol-1,这些数据可为松木的脱脂与防火研究提供参考。     

Kinetic Study of Nickel Oxide Reduction by Methane

The reduction of the nickel oxide, NiO, by methane was investigated in this work. The thermogravimetric technique was used for the determination of kinetic parameters for the reaction. The reaction was carried out in the temperature range of 600–725 °C, at atmospheric pressure with porous pellets prepared from nickel oxide powder with a mean particle size of 0.026 μm. The conversion‐time data have been interpreted by using the grain model. Complete conversion can be achieved in 11 min at 725 °C, which is shorter than the time required by carbon, i.e., ca. 120 min at 1000 °C. This faster reduction in comparison with carbonthermal reduction is attributed to the high carbon activity in methane. For the first order reaction with respect to methane concentration, the activation energy is found to be 63.9 kcal/g mol.     

氢气还原氧化铁动力学的研究(英文)

Kinetics parameters of iron oxide reduction by hydrogen were evaluated by the isothermal method in a differential micro-packed bed.Influence of external diffusion,internal diffusion and heat transfer on the intrinsic reaction rate was investigated and the conditions free of internal and external diffusion resistance have been deter-mined.In the experiments,in order to correctly evaluate the intrinsic kinetics parameters for reducing Fe2O3 to Fe3O4,the reaction temperatures were set between 440 °C and 490 °C.However,in order to distinguish the reduc-tion of Fe3O4 to FeO from that of FeO to Fe,the reaction temperature in the experiment was set to be greater than 570 °C.Intrinsic kinetics of iron oxide reduction by hydrogen was established and the newly established kinetic models were validated by the experimental data.     

Kinetic Analysis of Nonisothermal Reduction of Silica-Supported Nickel Catalyst Precursors in a Hydrogen Atmosphere

A series of silica-supported nickel catalyst precursors was synthesized with different SiO₂/Ni molar ratios. Reduction of Ni catalyst precursors with different SiO₂/Ni molar ratios under a hydrogen atmosphere was investigated at different heating rates. Kinetic parameters were determined using Kissinger–Akahira–Sunose isoconversional and invariant kinetic parameter methods. It was found that for all molar ratios, the apparent activation energy (E_a) is practically constant in the conversion range of 0.20 ≤ α ≤ 0.80. In the considered conversion range, following values of E_a were found: 134.5 kJ mol^?1 (SiO₂/Ni = 0.20), 139.6 kJ mol^?1 (SiO₂/Ni = 0.80), and 128.3 kJ mol^?1 (SiO₂/Ni = 1.15). It was established that the reduction of Ni catalyst precursors with different SiO₂/Ni molar ratios is a complex process and can be described by the ?esták–Berggren autocatalytic model. It was found that the reaction is more Langmuir–Hinshelwood type, as hydrogen dissociates rapidly on surface nuclei and the dissociated hydrogen reacts with the Ni–O active system. It was concluded that the reduction process proceeds through bulk nucleation, which is a dominant mechanism, where three-dimensional growth of crystals with polyhedron-like morphology exists. It was found that the Ni/Si ratio decreases after the reduction process. This has been explained by low Ni and higher Si surface concentrations. It has been disclosed that Ni dispersion decreases.     

A Kinetic Study on the Catalytic Reductive Methylation of Acetylhydrazine

Catalytic reductive methylation of acetylhydrazine (AH) to dimethyl acetylhydrazine (DMAH) is a key step in the production of unsymmetrical dimethyl hydrazine (UDMH). The results of the present study show that the limiting step in this process is the hydrogenation of AH to mono methyl acetylhydrazine (MMAH). The kinetics of the hydrogenation of acetylhydrazone (AOH) using an activated carbon catalyst impregnated with 5 % palladium were studied in a stirred slurry reactor at 40–65 °C and 5–25 bar hydrogen pressure. Analysis of the data from this investigation indicates that the rate of hydrogenation is consistent with an Eley‐Rideal reaction mechanism. The activation energy for the hydrogenation was determined as 44 kJ/mol.     

Kinetic Study of Metal-Catalyzed Reaction of Solid Calcium Oxide with Gas Mixtures of Methane and Water Vapor to Form Hydrogen

With noble metal catalysts (Pd, Pt, Rh, Ir) present, hydrogen is formed by the interaction of solid calcium oxide with gas mixtures of methane and water vapor, according to CaO + CH₄ + 2H₂O CaCO₃ + 4H₂. Among the metals, Ir and Rh are so active that the reaction takes place at temperatures as low as 600 K. Rate data obtained with these metals show a nearly first order with respect to CH₄ pressure, while a negative order with respect to H₂O vapor pressure. The apparent activation energies are 171 and 217 kJ/mol for the Ir- and Rh-catalyzed reactions, respectively. On the other hand, Ni does not catalyze the reaction below 733 K, probably due to its strong interaction with H₂O vapor.     

氧化铜灼烧温度对磷酸铜胶粘剂粘接强度的影响

沉淀法制备的氧化钢用不同的温度灼烧，再与多聚磷酸盐、促进剂、添加剂等组份调酸，发现当氧化铜灼烧温度在８５０℃时，压剪强度达８０．８ＭＰａ。用差热－热重分析，温度在１０５０℃范围内没有相变。未经灼烧和６５０℃、９４０℃、１０５０℃灼烧的氧化铜粉末样品，经Ｘ射线衍射实验，证实氧化铜全部为单斜晶型。氧化铜晶粒随着温度的升高长大，改变了低温时细晶粒聚集的疏松收集合体，降低了表面能。排除了氧化铜晶型改变对胶粘剂强度的影响因素。     

中低温氢还原铁矿微粉过程的实验研究与数值模拟

采用失重法研究了500~600℃条件下,H2还原铁矿微粉的反应过程. 针对气体浓度及反应热对铁矿粉还原过程的影响,提出了传热、传质与反应耦合动力学模型,以模拟铁矿微粉气相还原过程. 通过数值计算得到矿粉在不同温度下还原率随时间的变化规律,同时模拟了矿粉内温度变化与分布,以及气体浓度在微粒内部的分布与变化. 模拟结果表明,矿粉在600℃下完全还原时间仅为20 min,气体在15 min后全部扩散到粉粒中心.     

Kinetic Study of Copper Deposition on Iron by Cementation Reaction

Abstract

Cementation of copper on iron powder was shown to be a feasible process to achieve a high degree of copper removal over a broad operational range. First-order kinetics were followed for both the copper concentration and the surface area of iron. To minimize the effect of copper-hydroxyl formation and excess iron consumption, the cementation process was found to be more practical in weak acidic conditions     

氧化铜纳米粉体的制备工艺研究

以三水硝酸铜为反应物,氨水为络合剂,氢氧化钠为沉淀剂,乙醇水混合溶液为反应溶剂,聚乙二醇为分散剂,采用络合沉淀法,成功制备出平均粒径约20nm的氧化铜单晶纳米粉体。通过单因素实验和正交实验考察了硝酸铜溶液初始浓度、反应温度及氢氧化钠与硝酸铜物质的量比等因素对产物粒径大小的影响,利用x射线衍射（XRD）、透射电镜（TEM）和红外光谱仪（FT-IR）等对产物进行表征分析。研究结果表明,影响其粒径大小主要因素的主次顺序依次是：反应温度,硝酸铜溶液初始浓度及氢氧化钠与硝酸铜的物质的量比;优化制备工艺条件为：反应温度70℃,硝酸铜溶液初始浓度0．3mol／L,氢氧化钠与硝酸铜的物质的量比3：1,氨与硝酸铜的物质的量比5：1;氧化铜纳米粉体的红外吸收峰出现了红移和蓝移同时并存的反常现象。