影响取向硅钢隔离涂层质量的因素分析

介绍了用于取向硅钢表面隔离涂层的MgO(氧化镁)的性质、作用;分析了MgO的水化率、颗粒度、浆液温度及均匀性、涂敷烘干工艺、卷取张力、脱碳退火工艺及高温退火工艺对隔离涂层质量的影响.     

MgO膨胀剂细度对MgO水化和水泥浆体膨胀的影响

基于《水工混凝土掺用氧化镁技术规范》中的Ⅰ型氧化镁（MgO）,研究了该型MgO膨胀剂（MEA）细度对掺粉煤灰水泥浆体膨胀性能的影响。即采用X射线衍射分析(XRD)及同步热分析（TG DSC）分析了掺MEA水泥浆体中MgO的水化性。结果表明,养护温度相同时,MEA的细度对水泥浆体内MEA中MgO的水化和水泥浆体的膨胀无显著影响,产生的膨胀均能补偿水泥浆体的收缩;MEA的细度可从试验设计采用的45 μm筛筛余15%左右增加到30%左右,这将有利于MEA生产企业的节能降耗。     

在碱金属催化作用下煤焦与CO2的气化反应

利用固定床实验装置、以CO2作为气化剂，进行煤焦气化反应动力学的研究，分析了碱金属的含量及气化温度对煤焦-CO2气化反应的影响。采用未反应核收缩模型对试验数据进行处理，得到气化反应动力学参数。发现气化温度对煤焦与CO2的气化反应影响显著，碱金属作为煤焦-CO2气化反应的催化剂，能够降低反应过程的活化能，提高反应速率，用未反应核收缩模型能够很好地描述煤焦。CO2的气化反应过程。     

模拟工业炉温度特性下的型煤固硫特性的试验研究

主要介绍型煤在高温下的固硫特性和改善型煤固硫效率的试验研究结果。研究表明：型煤固硫效率受温度影响很大,在较低温度下由固硫反应生成的固硫产物在温度升高后,又可能发生分解;按以废治废的原则在钙基固硫剂中加入合适的添加剂,可以有效地提高固硫效率。     

焦炭体系下添加剂对CO2重整CH4特性的影响

利用固定床试验装置,以SiO2、MgO和CaO为添加剂,在焦炭体系下进行了CO2重整CH4活性的试验研究,并分析了反应温度和CaO含量对重整反应的影响.利用热重分析仪和扫描电镜分别对重整过程中焦炭失重和反应后焦炭微观形貌进行研究,探讨了反应机理.结果表明:加入SiO2后,制得的焦炭催化活性降低,加入CaO和MgO后,制得的焦炭催化活性提高,且CaO优于MgO;温度对重整反应影响显著,随着温度升高,反应气转化率增加;CaO添加剂含量控制在15%~20%之间对反应速率的提高较合适,且CaO的添加使焦炭失重速率也有所提高.     

生物质在高频耦合等离子体中的热解气化研究

采用高频电容耦合等离子体热解技术对生物质原料进行了热解气化试验，研究气体产物产率、成分随反应条件的变化规律。反应在3000-8000Pa的真空范围内进行，热解温度为1000～2000K。该技术可大幅度提高生物质气的热值及产率，本试验中产气率达到了66％以上，并且还有提高的潜力。     

氢氧化镁热化学储热系统流化床反应器性能分析

热化学储热具有储能密度高、储存时间长、温度范围宽的优点,是目前极具前景的储能技术,流化床反应器具有出色的传热传质性能,非常适合应用于热化学储热系统.本工作基于双欧拉模型,耦合了传热方程与反应动力学方程,构建了二维轴对称非稳态的多相流化学反应模型,以氢氧化镁和氧化镁作为储热材料,对热化学储热系统流化床反应器内的储、放热过程进行了研究,并且分析了床层膨胀率、气体流量对储放热效率的影响.通过实验验证了模型的准确性,探究了反应器内的能量流动过程与能耗优化方向.结果表明,床层温度不受传热效率的影响,反应器内不同区域间以及气相与固相间的温度差值均小于1.0 K,放热反应动力学限制了反应器性能;高温气固反应能显著提高床层膨胀率,床层膨胀率和气体流量的变化对储热效率影响较大,对放热效率影响较小;放热过程中的气体预热量和储热过程中的颗粒显热是反应器能量优化的重点方向.本研究对热化学储热系统中的流化床反应器数值建模分析以及实验设计优化具有指导价值.     

非催化烟气还原脱硝法脱硝特性的试验研究

在沉降炉脱硝试验平台上,对不同氨剂的选择性非催化还原(SNCR)脱硝特性进行了试验研究.结果表明:反应适宜氨氮比为1.5,氨气、尿素、碳酸氢铵脱硝的最佳温度窗口分别为985～1 030℃、775～1 085℃、760～1 075℃,尿素和碳酸氢铵最大脱硝效率达90%,优于氨气的80%;增大氨氮比或降低烟气氧浓度均可提高SNCR脱硝效率;在以尿素作为还原剂的SNCR脱硝反应过程中,协同加入钠盐添加剂可在保证最大脱硝效率基本不变的前提下,使反应温度窗口由782.9～1 086.3℃拓宽为749.5～1 086.3℃.     

含磷共聚物钻井液降黏剂合成及性能评价

以丙烯酸(AA)、2-丙烯酰胺基-2-甲基丙磺酸(AMPS)和含磷化合物共聚合成了抗220℃高温的钻井液降黏剂,对含磷化合物用量、引发剂(过硫酸铵)用量和滴加温度等对钻井液降黏剂特性黏度和降黏率的影响进行了考察。结果显示,钻井液降黏剂的最佳合成条件为:含磷单体用量为反应单体总质量的6%,过硫酸铵用量为反应单体总质量的2%,滴加溶液温度为55℃。利用红外光谱(IR)对钻井液降黏剂进行了表征,并借助热分析考察了钻井液降黏剂的热稳定性,同时对其在泥浆中的降黏性能进行了室内评价。研究结果表明:研制的钻井液降黏剂可以显著降低泥浆的黏度和切力,加入0.5%降黏剂的淡水基浆,高温降黏率可以达到91.4%;具有较好的抗盐、抗钙性能,在饱和盐水泥浆和含钙泥浆中也具有很好的降黏作用和分散作用;具有较好的热稳定性。     

氧化镁和葡萄酸对混凝土耐久性性能的影响

为研究氧化镁和葡萄酸对混凝土耐久性的影响,设计5组不同氧化镁和葡萄酸含量的混凝土试块,对混凝土进行了抗压试验、抗折试验和氯离子侵蚀试验。结果表明,混凝土的抗压强度和抗折强度随着氧化镁和葡萄酸的增加先增后降,氧化镁的最佳掺量为1%,葡萄酸的最佳掺量为1.5%;掺入氧化镁和葡萄酸的混凝土的抗氯子能力均得到了提高,同等掺量下,掺入氧化镁的效果比葡萄酸的效果要好。微观测试分析表明外加剂对混凝土内部结构的影响是外加剂影响混凝土耐久性的原因,也验证了氧化镁对混凝土性能的提升效果比葡萄酸的更好的结论。     

A chemical heat pump using hydration of mgo particles in a three-phase reactor

A chemical heat pump using hydration of magnesium oxide in a three-phase reactor is proposed. Magnesium oxide particles suspended in the triethylene glycol are hydrated exothermally by introducing water vapour. The hydration rate was measured under the temperatures ranging from 383 K to 523 K. It was found that the reaction rate was proportional to the amount of adsorbed water molecules, and correlated in an equation.     

Kinetic study of the hydration of magnesium oxide for a chemical heat pump

A kinetic study of the hydration of magnesium oxide was performed to test the possibility of developing a magnesium oxide/water chemical heat pump. The hydration rate of magnesium oxide was measured by a gravimetric analysis with a sample of average particle size 10 μm for the reaction temperature 373–423 K and the reaction vapor pressure 12.3–47.4 kPa. It was a reasonable hypothesis that the reactant magnesium oxide had four reaction regimes. An empirical rate equation based on this hypothesis was proposed with parameters determined from experimentally measured values. The performance of the heat pump was estimated numerically using the rate equation. The heat output rate was large enough in comparison with other common heat pumps. It was shown that the reaction system would be applicable to a chemical heat pump system.     

A Facile Method to Construct Graphene Oxide–Based Magnesium Hydroxide for Chemical Heat Storage

Mg(OH)₂ nanoparticles anchored on graphene oxide (GO) were facilely prepared by a hydrothermal method. The main diameter scale of nanoparticles on the graphene sheet was about 25–50 nm shown by transmission electron microscopy characterization results. X-ray diffraction results indicated that the nanoparticles are in accordance with the data on magnesium hydroxide. This material exhibited significantly improved heat storage capacity and a higher hydration rate than pure magnesium oxide, and the introduction of GO leads to greatly increased thermal conductivity of the nanocomposites. As a novel thermochemical heat storage material, Mg(OH)₂/GO has huge potential for high-efficiency energy systems.     

Dehydration and hydration behavior of metal-salt-modified materials for chemical heat pumps

Lithium chloride (LiCl) modified magnesium hydroxide (Mg(OH)₂) is a potential new material for chemical heat pumps. However, there is insufficient information concerning its dehydration and hydration behavior. In this study, the dehydration and hydration reactions, corresponding to the heat storage and the heat output operations, respectively, of authentic Mg(OH)₂ and LiCl-modified Mg(OH)₂ were investigated by thermogravimetric methods and near infrared spectroscopy. The dehydration of authentic Mg(OH)₂ proceeded as a one-step reaction. In contrast, the dehydration of LiCl-modified Mg(OH)₂ occurred in two steps. The dehydration reaction rates were increased by LiCl modification of the Mg(OH)₂ surface, while the activation energy for the first-order dehydration reaction was lowered. The mechanism for the hydration reaction of magnesium oxide (MgO) was different to that for the hydration of LiCl-modified MgO. This difference was explained by the effect of the LiCl on the MgO particle surface.     

纳米多孔碳对MgO/Mg(OH)2化学蓄热性能影响的实验研究

为提高MgO/Mg(OH)₂的热化学蓄/放热性能,采用焙烧法将氧化镁（MgO）负载在纳米多孔碳（NCP）材料上制备纳米碳基氧化镁（NCP-MgO）复合材料。研究结果表明,NCP载体使MgO在其表面形成粒径为10 ~ 30 nm大小的颗粒,复合材料NCP-MgO具有较高的导热系数,负载80% MgO后导热系数是纯MgO的2.6倍。在反应温度110℃、水蒸气压力57.8 kPa的实验工况下,发现水合速率的大幅提升是强化MgO/Mg(OH)₂蓄热性能的主要原因,在水合反应60 min和120 min时,NCP-MgO复合材料的水合转化率分别是纯MgO的2.25倍和1.6倍。在水合反应120 min后,MgO负载率为80%的NCP-MgO复合材料的蓄热密度可达1 053 kJ/kg,是纯MgO的1.4倍。该研究可为MgO/Mg(OH)₂在化学蓄热系统的应用提供一定的参考。     

Hydrogen generation by the reaction of Al with water using oxides as catalysts

Hydrogen generation by the reaction of pure Al powder in water with the addition of Al(OH)₃, γ‐Al₂O₃, α‐Al₂O₃, or TiO₂ at mild temperatures was investigated. It was found that the reaction of Al with water is promoted and the reaction induction time decreases greatly by the above hydroxide and oxides. X‐ray diffraction analyses revealed that the hydroxide and oxide phases have no any change during the Al–water reaction, indicating that they are just as catalysts to assist the reaction of Al with water. A possible mechanism was proposed, which shows that hydroxide and oxides could dissociate water molecules and promote the hydration of the passive oxide film on Al particle surfaces. Copyright © 2013 John Wiley & Sons, Ltd.     

Numerical investigation of H2 absorption in an adiabatic high-temperature metal hydride reactor based on thermochemical heat storage: MgH2 and Mg(OH)2 as reference materials

A two-dimensional mathematical model to predict the thermal performance of an adiabatic hydrogen storage system based on the combination of magnesium hydride and magnesium hydroxide materials has been developed. A simple geometry consisting of two coaxial cylinders filled with the hydrogen and thermochemical heat storage materials was considered. The main objective was to gain a better knowledge on the thermal interaction between the two storage media, and to determine the dependence of the hydrogen absorption time on the geometric characteristics of the reactor as well as the operation conditions and the thermophysical properties of the selected materials. The dimensions of the two compartments where the two materials are filled were chosen based on the results of a preliminary analytical study in order to compare the absorption times obtained analytically and numerically. The numerical results have shown that the hydrogen absorption process can be completed in a shorter interval of time than analytically as a result of the larger temperature gradient between the magnesium hydride and magnesium hydroxide beds. This was mainly due to variation of temperature in the thermochemical heat storage material during the more realistic dehydration reaction in the numerical solution. Larger temperature gradients, thus a faster hydrogen absorption process can also be achieved by increasing the hydrogen absorption pressure. Moreover, it was found that the increase of the thermal conductivity of the magnesium hydroxide material is crucial for a further improvement of the performance of the MgH₂–Mg(OH)₂ combination reactor.     

循环流化床锅炉脱硫飞灰的水活化实验研究

以310 t/h循环流化床锅炉脱硫飞灰为原料,在不同的水活化条件下进行活化机理的实验研究,探讨了水活化温度、活化时间、活化水量对灰中游离氧化钙水合反应转化率的影响规律,并研究了水活化对孔隙结构的影响。结果表明:水活化过程中,水合反应与消耗氢氧化钙的胶凝反应同时进行;水活化过程中氢氧化钙含量呈现快速上升、慢速上升、缓慢下降的规律;随活化温度提高,水合反应与胶凝反应速率均提高,中期持续时间缩短,活化时间一定时,活化温度存在最佳值;活化水量的增加,可以加快水合反应与胶凝反应速率,活化时间处于后期时,活化水量存在最佳值。     

Magnesium oxide/water chemical heat pump to enhance energy utilization of a cogeneration system

A chemical heat pump using a magnesium oxide/water reaction system is expected to be applicable to cogeneration systems using gas engine, diesel engine, and fuel cells. The operability of the heat pump was examined experimentally under hydration operation pressures between 30 and 203 kPa. In the experiment, a reactant having high durability for repetitive operation was packed in a cylindrical reactor. The cycle of operation was repeated under various thermally driven operation conditions. The forward and reverse reactions were studied by measuring the reactor bed temperature distribution and the reacted fraction changes. The reactor bed stored heat at around 300–400 °C by the dehydration reaction and released heat at around 100–200 °C by the hydration reaction under the heat amplification mode operation. The practical possibility of the reactor bed was discussed based on the experimental results. The heat pump is expected to be applicable for load leveling in a cogeneration system by chemically storing surplus heat during low heat demand and supplying heat during peak demand. It was shown that the chemical heat pump would be able to improve the efficiency of energy utilization in cogeneration systems while also helping to reduce energy consumption and global carbon dioxide emissions.     

钢渣/碱式碳酸镁新型复合脱硫剂的性能研究

在脱硫剂中加入添加剂会对脱硫剂的脱硫效率产生显著影响。实验采用了碱式碳酸镁作为脱硫剂,使用钢渣作为添加剂,通过实验室规模的鼓泡反应装置模拟烟气湿法脱硫过程,研究添加钢渣对碱式碳酸镁脱硫性能的影响。结果表明,在模拟的烟气湿法脱硫反应过程中,添加钢渣能够有效地提高复合脱硫剂的比表面积,同时提高脱硫效率,但复合脱硫剂的硫容量较碱式碳酸镁低,分析认为钢渣中含有的金属氧化物水解后生成的固溶体催化了脱硫反应,这是复合脱硫剂脱硫效率升高的原因,但钢渣中活性成分较少导致了硫容率的下降。