电镀中的渗氢研究

本文报道利用电化学方法研究酸洗过程的渗氩、镀层-基体复层体系的渗氢以及金属电沉积过程的渗氢等若干典型的实验结果,用不同渗氢模型导出的理论关系式定量地解释渗氢电流曲线,讨论了渗氢测定在电镀研究中的可能应用。     

馏分油氢转移能力的测定与分析

采用管式反应器考察了三种馏分油的受热氢转移能力,用气相色谱分析反应产物,并根据实验结果改进了氢转移能力的计算方法。结果表明:不同的馏分油/探针比,测得的馏分油氢转移能力不同,随着馏分油/探针比的增大,氢转移能力大体呈先减小后不变的趋势;馏分油的氢转移能力与其结构组成密切相关,三种馏分油的供氢能力与其α氢含量顺序一致BCA,夺氢能力与β氢、芳炭率fA、缩合度大小顺序一致CBA。综合考虑供氢能力和夺氢能力,三种馏分油的供氢指数大小顺序为BAC。     

Zn-Ni合金电沉积过程中的渗氢行为

用电化学渗氢测试方法探讨了氯化物体系、硫酸盐-氯化物混合体系电沉积Zn-N i合金镀层过程中的渗氢行为。结果表明,氯化物体系比硫酸盐-氯化物混合体系渗氢电流小,用电镀过程中的氢覆盖率和镀层孔隙率对渗氢特点进行了解释。     

运用多氢源匹配法设计氢分配网络

石油炼化企业中氢网络的优化对提高氢资源的利用率意义重大,以降低氢消耗和简化集成方法为目标提出了一种氢回用网络的设计新方法。在向一个氢阱分配氢源时,优先分配内部氢源,并将浓度刚好高于和刚好低于该氢阱入口浓度的氢源进行匹配利用,从而最大限度地降低外部氢源消耗。对文献中几个实例的研究表明,本文方法得到的结果可与文献方法得到的目标值相媲美,而设计步骤简单计算量小,可用手算即能完成,说明本文提出的方法是可行的。另外,本文方法不仅可以得出氢消耗目标值,还可以同时得出氢网络设计。     

氢系统关键氢阱最优氢浓度的确定

氢气网络优化时一般将氢阱氢浓度降低至最低限制浓度,以获取最大可能的节氢效果,然而这会降低系统操作弹性。分析了在氢阱氢浓度降低的过程中,有可能出现夹点位置的改变,从而导致节氢量-氢阱氢浓度曲线斜率的减小以及氢气网络中要考虑的其他经济因素,提出了在氢阱氢浓度降低过程中找出最优浓度并在此浓度下进行系统优化的方法,使得氢阱氢浓度降低幅度不大但系统的节氢效果较为显著。以某炼厂为例,通过选择关键氢阱,分析该关键氢阱氢浓度与系统节氢量的关系,确定最优浓度,系统优化后节氢量为42.81 mol·s^-1,占现行系统新氢用量的21.58%。结果表明,该方法可在氢阱氢浓度降低较小的情况下实现较好的节氢目的。     

从氯碱尾气中提取高纯氢

本文叙述了氯碱工业副产氢气的应用及其成分分析。提出了从氯碱工业尾气制取工业氢和高纯氢的经济方法,为发展氢能事业开拓了新的制氢技术和丰富而又经济的氢气来源。同时,用该法可回收原料氢中的微量氯气,从而消除了环境污染,节约了大量能源。     

节能析氢电极的研究

用电镀法制备了镍－钼析氢电极，考察了制备条件对该电极析氢活性的影响。本文实验条件下，镀液中钼与镍的原子比为1：2，电镀电流密度为18mA·cm－2时，制备的镍－钼电极有较高的折氢活性。与现行氯碱电解槽的低碳钢网析氢电极比较，析氢过电位降低0．116V。     

储氢提纯和氢网络的耦合优化

基于氢网络的集成以及AB₅型储氢材料LaNi_4.75Fe_0.25及LaNi_4.85Al_0.15的特性,对储氢提纯在氢网络中的应用进行研究。综合考虑LaNi_4.75Fe_0.25及LaNi_4.85Al_0.15储氢/放氢动力学,建立了储氢提纯氢网络的优化方法,根据单位质量储氢材料提纯的节氢能力和公用工程节省量与提纯参数的关系,确定最优提纯氢源浓度、最大公用工程节省量、储氢材料量和吸氢时间。用该方法对某炼厂氢网络和储氢提纯单元进行优化,结果表明,最优提纯氢源浓度为70%,提纯后公用工程可节省23.72%; LaNi_4.85Al_0.15作为储氢提纯材料优于LaNi_4.75Fe_0.25,其消耗量为991.26 kg。     

二氢黄樟素的气相色谱分析

采用DEGS为固定液、联苯为内标物,用气相色谱法测定二氢黄樟油中二氢黄樟素的含量。该方法的标准偏差为0.418,变异系数为0.452％。     

硫酸氢钾重量法测定硫化橡胶中的二氧化硅

本文介绍了用硫酸氢钾重量法测定硫化橡胶中二氧化硅含量的新方法。用硫酸氢钾熔融胶样的灰分,以氢氟酸处理熔块中的盐酸不溶性残渣,而使二氧化硅组分挥脱。本方法具有快速、准确等特点,适用于含有白炭黑及硅酸盐填料的各种硫化橡胶与混炼胶中的二氧化硅组分的测定。     

医疗废物焚烧废气中氯化氢的离子色谱法测定研究

以0．09mol／L碳酸钠和0．085mol／L碳酸氢钠的混合液为吸收液,同时串联两个多孔玻板吸收管两级吸收采样,采集医疗废物焚烧废气中的氯化氢,采样后用离子色谱法测定。当采样体积为10L时,氯化氢的检出限为0．4mg/m^3。实际水样的加标回收率为95．3％-101％。方法操作简便快速、准确、灵敏度高,完全满足环境监测对医疗废物焚烧废气中的氯化氢的测定。     

Direct synthesis of hydrogen peroxide from H2 and O2 using zeolite-supported Au-Pd catalysts

The direct synthesis of hydrogen peroxide from H₂ and O₂ using zeolite-supported Au-Pd catalysts is described using two zeolites, ZSM-5 and zeolite Y, using an impregnation method of preparation. The addition of Pd to Au for these catalysts significantly enhances the productivity for hydrogen peroxide. The use of zeolites as a support for Au-Pd gives higher rates of hydrogen peroxide formation when compared with alumina-supported Au catalysts prepared using a similar method. The addition of metals other than Pd is also investigated, but generally Au-Pd catalysts give the highest activity for the synthesis of hydrogen peroxide. The addition of Ru and Rh have no significant effect, but the addition of Pt does enhance the activity for the selective formation of hydrogen peroxide.     

Off‐Gases Optimization in a Hydrogen Network Refinery

For optimization of a hydrogen network, a steam reformer is associated to the feedstock and linear programming (LP) is applied. The investigated network consists of one steam reformer and two feedstocks. By exerting LP and the mentioned association, total annual cost decreasing is achieved in a case study in which natural gas and off‐gas were considered as feedstocks. The optimization problems of the hydrogen network comprise the hydrogen network retrofit design and the feedstock selection with respect to their cost. Nonlinear programming (NLP) and mixed‐integer nonlinear programming (MINLP) models are developed for optimization based on a two‐case study: for the first one, an existent optimization method on hydrogen networks is investigated and for the second one, revision of a recent optimization method on hydrogen networks associated by an LP model in the steam reformer unit is applied. These two cases resulted in total annual cost reductions of 34 % and 45.9 %, respectively.     

Optimization of hydrogen networks with constraints on hydrogen concentration and pure hydrogen load considered

The mathematical model of hydrogen network is developed to minimize the total exergy consumption of the hydrogen utility and compressor work. The constraint on the hydrogen to oil ratio of hydrogen consuming reactor is represented by that on pure hydrogen load of each sink. Instead of reducing the hydrogen concentration and pure hydrogen load to the minimum directly, all the possible combinations of them are considered. Furthermore, the optimal flow rate of each sink is taken as a variable in the model and the matching flow rate constraint is introduced to remove the source-sink match with small flow rate. This method can be applied to target the minimum utility consumption of systems with any number of impurities. In addition, both the hydrogen to oil ratio and hydrogen concentration can be guaranteed not be less than their lower limitations. The proposed method is applied to the hydrogen network of a real installation, and the results show the hydrogen utility saving potential accounts for 16.52% of the current hydrogen utility consumption.     

有机液体载体储氢催化剂的研究

介绍了6种常用的储氢方法:加压压缩储氢技术、液化储氢技术、储氢合金储氢、碳质材料储氢、金属有机骨架储氢、有机液态氢化物可逆储放氢技术等,并对诸项技术的优点以及存在的问题进行了评述。重点介绍了有机液态氢化物可逆储放氢技术的原理和特点,综述了国内外研究现状并提出了使用廉价的液体储氢原料和提高催化剂活性、稳定性的新思路。     

Effect of electrodeposition parameters on the hydrogen permeation during Cu-Sn alloy electrodeposition

The Cu-Sn alloy coatings were synthesized on 27SiMn steel by direct current (DC), pulse current (PC) and pulse reverse current (PRC) electrodeposition techniques from pyrophosphate-based electrolyte. The hydrogen permeation behaviors during the electrodeposition by different techniques were investigated using Devanathan-Stachurski method. The results demonstrated that the hydrogen permeation amount of different electrodeposition techniques decreased in the order: DC > PC > PRC. Frequency and duty cycle have great effect on the sub-surface concentration C_o of atomic hydrogen and hydrogen permeation amount. The minimum of hydrogen permeation amount was observed at the frequency of 1000 Hz or 2500 Hz and the duty cycle of 40%. It indicates that the amount of permeated hydrogen in the steel during deposition can be reduced due to the decrease of C_o by PC and PRC methods.     

A unified graphical method for integration of hydrogen networks with purification reuse

Introducing purifiers into hydrogen network can enhance the recovery and reuse of hydrogen in refineries, further reducing the consumption of fresh hydrogen. Based on previous graphical methods, this work proposes a simple and unified graphical method for integration of hydrogen networks with purification processes. Scenarios with different hydrogen concentrations of purified product can be analyzed by the unified procedure. As a result, the maximum hydrogen saved by purification reuse can be identified and the corresponding purification process can be optimized. The proposed method is easy and non-iterative, and it is valid to purification processes with any feed concentration. A conventional hydrogen network is analyzed to test the effectiveness of the proposed method.     

A novel graphical method for the integration of hydrogen distribution systems with purification reuse

Increase in refining demand and tighter environmental regulations have led to sharp increases in hydrogen consumption of oil refineries. Hydrogen conservation and effective use are of interest to refineries whose operations and profitability are constrained by hydrogen. Purification is widely used in hydrogen networks of refineries to reduce hydrogen production load. To minimize hydrogen utility consumption, it is necessary to optimize the hydrogen network with purification as a whole. In this paper, for hydrogen purification process, a triangle rule (which can be generalized to polygon rule) is proposed for graphical representation of its mass balance. The proposed procedure treats the product concentration and recovery rate of the purification process as adjustable parameters. An ensuing graphical method is developed for targeting the pinch point and minimum utility consumption of the hydrogen system with purification reuse. This graphical method can be used for any purification devices and in systems with any utility concentration. A refinery case is studied to demonstrate the optimization method.     

Perspectives and challenges of hydrogen storage in solid-state hydrides

Hydrogen has been widely considered as a clean energy carrier that bridges the energy producers and energy consumers in an efficient and safe way for a sustainable society. Hydrogen can be stored in a gas, liquid and solid states and each method has its unique advantage. Though compressed hydrogen and liquefied hydrogen are mature technologies for industrial applications, appropriate measures are necessary to deal with the issues at high pressure up to around 100 MPa and low temperature at around 20 K. Distinct from those technologies, storing hydrogen in solid-state hydrides can realize a more compact and much safer approach that does not require high hydrogen pressure and cryogenic temperature. In this review, we will provide an overview of the major material groups that are capable of absorbing and desorbing hydrogen reversibly. The main features on hydrogen storage properties of each material group are summarized, together with the discussion of the key issues and the guidance of materials design, aiming at providing insights for new material development as well as industrial applications.     

Introducing a proper hydrogen liquefaction concept for using wasted heat of thermal power plants-case study: Parand gas power plant

A hydrogen liquefaction concept with an innovative configuration and a capacity of 4 kg·s^-1 (345.6 t·d^-1) is developed. The concept involves an ammonia absorption refrigeration system for the pre-cooling of hydrogen and MR streams from 25 ℃ to -30 ℃. The ammonia absorption refrigeration system is fed by exhaust gases of the Parand gas power plant that are normally dissipated to the environment with a temperature of 546 ℃. The simulation is performed by Aspen HYSYS V9.0, using two separate equations of state for simulating hydrogen and MR streams to gain more accurate results especially for ortho-para conversion. Results show that conversion enthalpy estimated by Aspen HYSYS, fits very well to the experimental data. Determining the important independent variables and composition of MRs are done using trial and error procedure, a functional and straightforward method for complicated systems. The minimum temperature limit in the cooling section is lowered, and an ortho-para converter is implemented in this section. The proposed concept performs well from energy aspects and leads to COP and SEC equal to 0.271 and 4.54 kW·h·kg^-1, respectively. The main advantage of this study is in the low SEC, eliminating the losses of the distribution network, and improving the ability of the hydrogen liquefaction for energy storage in off-peak times.