Application of Danckwerts-type boundary conditions to the modeling of the thermal behavior of metal hydride reactors

The paper presents a model-based investigation of a metal hydride reactor applied as a solid state hydrogen storage device. The elements of a metal hydride reactor are hydrogen supply duct, internal hydrogen distribution, hydride bed, reactor shell and the flow domain of the heat transfer fluid. Internal hydrogen distribution and hydride bed are porous media. Therefore, hydrogen flows through non-porous and porous regions during its reversible exothermic absorption and endothermic desorption, respectively. The interface between porous and non-porous regions is a discontinuity with respect to energy transport mechanisms. Hence, Danckwerts-type boundary conditions for the energy balance equation are introduced. Application of the first and second law of thermodynamics to the interface reveals that temperature jumps may occur at the hydrogen inlet but are not allowed at the hydrogen outlet. Exemplarily the loading behavior of a metal hydride storage tank based on sodium alanate is analyzed. It is demonstrated and experimentally validated that only Danckwerts-type boundary conditions predict the important cooling effect of the inlet hydrogen on the exothermic absorption process correctly.     

Preliminary evaluation of the performance of an adsorption‐based hydrogen storage system

Using modeling and thermal simulations, the feasibility of an adsorption‐based hydrogen storage system for vehicles is evaluated. The storage capacity of a 150 L tank filled with a high surface‐area activated carbon is mapped for temperatures from 60 to 298 K and pressures up to 35 MPa. The thermal simulations are verified using experiments. For a storage capacity target of 5 kg, the adsorption‐based storage system will offer a storage advantage over the cryogenic gas storage if the residual mass of hydrogen in the tank is retrieved by heating. For a discharge rate of 1.8 g/s, the required heat is of the order of 500 W. The net energy requirements for the refueling has contributions from compression, precooling and tank cooling and can approach that for liquid hydrogen storage. With a good insulation and a maximum tank pressure of 35 MPa, the dormancy period can be extended to several weeks. © 2009 American Institute of Chemical Engineers AIChE J, 2009     

甲醇储罐设计技术及注意事项

根据甲醇的性质和储存中的注意事项,对甲醇储罐设计中的必要因素进行了分析总结,结合目前国内外压力容器的设计技术进展,阐明了甲醇储罐的结构形式等优化设计的方向,总结了合理选择设计类型、必要的防范措施和控制措施,总结了甲醇储罐区内需要重点注意的事项,归纳了今后甲醇储罐的发展趋势。     

LNG气化站储存增压系统设计

储存增压系统是LNG气化站工艺设计的重要内容之一,而低温储罐和储罐增压器的设计又是储存增压系统设计的关键。从低温储罐的选择、运行参数的确定及压力控制等方面讨论了LNG储罐的设计方法。从储罐增压器的增压方式、布置形式、选型等方面讨论了LNG储罐增压器的设计方法。最后给出了设计举例。     

A Dynamic Simulation Tool for the Battery‐Hybrid Hydrogen Fuel Cell Vehicle

This paper describes a dynamic fuel cell vehicle simulation tool for the battery‐hybrid direct‐hydrogen fuel cell vehicle. The emphasis is on simulation of the hybridized hydrogen fuel cell system within an existing fuel cell vehicle simulation tool. The discussion is focused on the simulation of the sub‐systems that are unique to the hybridized direct‐hydrogen vehicle, and builds on a previous paper that described a simulation tool for the load‐following direct‐hydrogen vehicle. The configuration of the general fuel cell vehicle simulation tool has been previously presented in detail, and is only briefly reviewed in the introduction to this paper. Strictly speaking, the results provided in this paper only serve as an example that is valid for the specific fuel cell vehicle design configuration analyzed. Different design choices may lead to different results, depending strongly on the parameters used and choices taken during the detailed design process required for this highly non‐linear and n‐dimensional system. The primary purpose of this paper is not to provide a dynamic simulation tool that is the “final word” for the “optimal” hybrid fuel cell vehicle design. The primary purpose is to provide an explanation of a simulation method for analyzing the energetic aspects of a hybrid fuel cell vehicle.     

轻质高压储氢容器

氢的储运是氢能发展的关键技术之一。轻质高压储氢是一种切实可行的氢能储运方法。结合纤维缠绕气瓶和高压储氢容器的国内外最新研究进展,介绍了轻质高压储氢容器的结构、设计方法和有待深入研究的若干问题。     

原油储罐抗震设计及附件选用

当前,随着石油峰值的来临和我国面临的石油资源匮乏的危机,国家将大力推进石油的战略储备工作,这也使得我国将加大对大型储罐的投资建设。但由于地理位置的影响,储罐会受到地震等外界因素的影响,因此对储罐进行抗震设计是必不可少的。提出了一些在设计大型原油储罐过程中应该重视的附件选择问题。     

固定式燃料电池储氢气瓶的研制

以固定式燃料电池储氢气瓶的广泛应用为背景,对12L碳纤维全缠绕储氢气瓶的开发进行了研究。本文对CYD-128树脂浇铸体的拉伸性能进行了测试,同时开展了T700-12K/CYD-128复合材料NOL环的层间剪切试验。在此基础上,利用商业CADWIND软件,根据气瓶的技术指标对其进行了碳纤维的缠绕铺层设计,并利用ANSYS有限元应力分析,以对复合材料气瓶的缠绕工艺方案进行验证。根据设计的线型完成35 MPa高压储氢气瓶的缠绕,各项指标均满足使用要求。     

石油储运系统中储油罐区的设计

介绍了石油储运系统中储油罐区的设计,通过介绍储油罐区的总容量确定、工艺设计及消防设施设计,说明了储油罐区的规范设计和安全防范措施对其功能、作用的发挥及对石油储运系统安全、高效生产运营的重要性。     

Axial Dispersion during Hanford Saltcake Washing

Abstract

This paper describes laboratory‐scale testing conducted to evaluate Selective Dissolution of cesium from non‐radioactive Hanford tank 241‐S‐112 salt cake simulant containing the primary chemicals found in the actual tank. A modified axial dispersion model with increasing axial dispersion was developed to predict cesium removal. The model recognizes that water dissolves the salt cake during washing, which causes an increase in the axial dispersion during the wash. This model was subsequently compared with on‐line cesium measurements from the retrieval of tank 241‐S‐112. The model had remarkably good agreement with both the lab‐scale and full‐scale data.     

大型LNG储罐预冷动态模拟

大型常压LNG储罐在接收站中占有很高的投资份额,是接收站关键的储存容器,在启用时对调试技术的要求较高,其中,储罐的冷却是最重要的预备环节。基于气液两相容积节点原理,建立喷淋LNG蒸发计算模型,搭建大型LNG储罐预冷过程动态仿真平台,以160000 m³大型LNG地上全容储罐为例,计算其在预冷过程中所需要的时间以及预冷所用LNG总量,得到了预冷过程中储罐压力、BOG产生量以及储罐内部温度的动态变化,为设计优化液化天然气储罐预冷策略提供了理论依据。     

Minimum weight design of helically and hoop wound toroidal hydrogen storage tanks with variable slippage coefficients

This article determines the optimal winding parameters for helically and hoop overwound toroidal hydrogen storage tanks, based on the application of variable slippage coefficients. First, an optimality condition between helical winding angle and hoop‐to‐helical thickness ratio is derived from the minimum strain energy density criterion. The winding angle distributions are then obtained with the aid of the optimality condition, taking into account the shell thickness variation along the meridional direction. The general criteria for fiber trajectory stability on a torus are presented, and the relationship for the slippage coefficient and the helical winding angle is formulated according to the windability and manufacturability. The helical winding angle and thickness at the equator are considered as design variables, whereas the minimum weight acts as the objective function. A design example with a toroidal hydrogen storage tank is outlined to demonstrate the favorable performance of the present method. The results show that the present method using variable slippage coefficients leads to a better distribution of the fiber stress in the toroidal shell and an efficient utilization of the laminate strength. The obtained winding parameters can thus be regarded as optimal for filament‐wound toroidal hydrogen storage tanks. POLYM. COMPOS., 2012. © 2012 Society of Plastics Engineers     

Enhanced Selective Leaching of Chromium from Radioactive Sludges

Abstract

An enhanced selective oxidative alkaline leaching (ESOAL) process has been developed for the removal of chromium from high level waste (HLW) tank sludges. Because of the adverse effect of excess chromium on the vitrification process, chromium removal becomes a critical factor in the pretreatment of underground storage tanks (USTs) containing nuclear waste. The ESOAL process described here uses a unique approach based on the innovative combination of an effective oxidant and sonochemical oxidation, achieving efficiencies and removal rates substantially better than either of the processes used independently. Results are shown here for the ESOAL treatment of a tank sludge simulant (Hanford tank S‐101). The effects of different variables (e.g., time, ultrasound power, temperature, sodium hydroxide concentration, and the use of an oxidant) on the amount of sludge dissolved are presented.     

Full‐Loop Simulation of Gas‐Solids Flow in a Pilot‐Scale Circulating Fluidized Bed

In order to study the system hydrodynamics in a circulating fluidized bed (CFB), a 3D full‐loop simulation was conducted for a pilot‐scale CFB. The Eulerian‐Eulerian two‐fluid model with the kinetic theory of granular theory helped to simulate the gas‐solids flow in the CFB. The system hydrodynamics including pressure balance, vectors of gas and solids, distribution of solids holdup, and instantaneous circulating rates were obtained to get a comprehensive understanding of the system. It was predicted that the main driving force was the pressure drop of the storage tank. The storage height and valve opening were critical operating factors to control the riser operation. The effects of operating conditions including solids circulating rates and superficial gas velocity on the hydrodynamics were investigated to provide guidance for the stable operation of the CFB system.     

Hydrogen evolution performance of magnesium alanate prepared by a mechanochemical metathesis reaction method

Solvent-free magnesium alanates were prepared by a mechanochemical metathesis reaction method (ball milling method) with a variation of milling time. For the purpose of comparison, magnesium alanate was also prepared by metathesis reaction method in the presence of diethyl ether. The formation of magnesium alanate (Mg(AlH₄)₂) and magnesium alanate-diethyl ether (Mg(AlH₄)₂·Et₂O) adduct was confirmed by XRD measurements. In both magnesium alanates, hydrogen evolution occurred in the first step decomposition. The starting temperature for hydrogen evolution of the solvent-free magnesium alanates decreased with increasing milling time, whereas the amount of hydrogen evolution of the solvent-free magnesium alanates increased with increasing milling time. The maximum amount of hydrogen evolution of the Mg(AlH₄)₂·Et₂O adduct was slightly larger than that of the solvent-free Mg(AlH₄)₂, but the starting temperature for hydrogen evolution of the Mg(AlH₄)₂·Et₂O adduct was much higher than that of the solvent-free Mg(AlH₄)₂. The addition of a small amount of titanium to the solvent-free Mg(AlH₄)₂ greatly reduced the hydrogen evolution temperature of titanium-doped Mg(AlH₄)₂. However, the maximum amount of hydrogen evolution of the titanium-doped Mg(AlH₄)₂ was smaller than that of the solvent-free Mg(AlH₄)₂.     

电镀废水处理技术与实践

用次氯酸钠溶液和双氧水组合的方法处理含氰废水,效果好且成本低。可以用双氧水处理含镍废水中的氰化物,但不能使用次氯酸钠溶液,在碱性条件下Ni 2+被次氯酸钠氧化生成Ni(OH)3沉淀。设置两个中和池,在一级中和池中加入石灰处理掉约90%的废酸,同时在二级中和池中加入石灰处理剩余的废酸。在二级中和池中用pH自动控制系统控制石灰的加入量,保证排放水的浊度达到标准。     

常压储罐群RBI技术的应用与漏磁检测

根据基于风险的检验(RBI)原理,对某储罐群进行了风险评估,得到了储罐壁板和底板的失效可能性、失效后果与风险等级。结合RBI分析结果,针对储罐的主要失效模式及损伤机理制定了相应的检验策略。选取中高风险储罐开罐实施底板漏磁检测,并与评估结果进行对比分析,验证了储罐RBI技术的可靠性,有效降低了罐群运行风险。     

氢气快充温升控制装置数值设计

高压氢气从储氢罐到氢气瓶的加注过程中存在一定的温升．从安全角度出发,本文建立了高压氢气快充温升控制设计模型,基于模型对氢气快充温升控制装置进行了数值分析,并提出了氢气快充温升控制装置的数值设计方法。研究结果可以为加氢站等对于初始温度有要求场合的设计提供参考。     

Design and optimization of hydrogen storage units using advanced solid materials: General mathematical framework and recent developments

This review presents the general mathematical framework of modeling, design and optimization of hydrogen storage using advanced solid materials. The emphasis is given on metal hydride storage tanks, since these systems have been well studied in the literature, both theoretically and experimentally, and are expected to offer significant advantages when current research and development efforts succeed in commercializing the required technology. Enhanced cooling during hydrogen filling of the storage tank is found to be essential to improve hydrogen storage time requirements. For this reason several innovative design strategies for heat exchanger configurations are presented and evaluated in terms of process design and performance improvement. Finally, control and optimization of certain operating conditions can also have a significant impact in hydrogen storage operation.     

Simulation des anaeroben Prozesses bei der Biogaserzeugung

A simulation of the anaerobic process of a biogas production for different substrates was realized. The simulation was based on the Anaerobic Digestion Model No. 1 (ADM1). The experimental work comprehends batch‐experiments and experiments in a continuous stirred‐tank reactor at lab scale with different substrates used in a biogas production. The comparison between the experiments and the simulations of the process leads to a modification in ADM1. Furthermore a classification of substrates was developed according to their biodegradability to meet the fractions of the ADM1 simulation. The simulations for the different substrates showed a satisfactory agreement with the measured values.