用改性活性碳纤维去除CO2原料气中的H2S

采用固定床动态吸附实验，用改性活性碳纤维（ACF）吸附去除CO2原料气中的H2S。通过改变改性剂种类、反应温度和原料气中CO2浓度，找出用改性ACF去除CO2原料气中H2S的规律。实验结果表明：常温下，可用NaON改性的ACF来消除CO2的酸性对去除H2S的不利影响；随着反应温度的升高，CO2与ACF形成的C（O＊）中间产物增多，CO2的存在有利于改性ACF去除H2S；而当反应温度过高时，CO2与ACF形成的C（O＊）中间产物发生分解，导致ACF碳化，不利于H2S的吸附去除。     

多因素耦合条件下硫化矿自燃神经网络动态预测模型研究

硫化矿石自燃是多种因素、多场耦合综合作用的结果,是一典型的非线性问题。笔者应用人工神经网络技术,以Matlab软件为平台,通过现场调查和理论分析,建立了矿石含硫量、通风强度、环境温度3因素与硫化矿石自燃之间的预测模型;通过数据样本学习与部分现场监测数据相结合进行模拟,研究表明预测数据与实测结果基本吻合,误差控制在10%以内,取得了较好的效果。该研究为预防硫化矿石自燃提供一个新的思路和方法,具有一定的理论意义和应用价值。     

钠盐量影响下DD6单晶高温合金的高温热腐蚀规律研究

目的 开展镍基单晶高温合金DD6在950 ℃下的热盐腐蚀试验(95%Na2SO4+5%NaCl)，探明涂盐量和涂盐方式(周期涂盐和单次涂盐)对DD6高温热腐蚀的影响规律和机理。方法 结合扫描电子显微镜、X射线能量色散谱、X射线衍射等设备，对不同涂盐量及涂盐方式下DD6的表面及横截面形貌进行观察分析，分析不同涂盐量和涂盐方式下DD6的高温热腐蚀机理。结果 DD6在950 ℃下主要发生碱性熔融热腐蚀，同时伴随氧化、硫化和氯化等过程。高温热腐蚀使得DD6合金表面生成的保护性氧化膜被熔融态的腐蚀介质破坏，导致O、S、Cl等外部元素通过氧化膜的缺陷进入DD6基体中，在合金的亚表面发生内氧化、内硫化以及内氯化反应，横截面上出现明显的腐蚀层，其主要由氧化物以及硫化物组成。随着热腐蚀的进行，DD6表面物质发生了剥蚀，沉积盐量的增加导致剥蚀现象越加严重，合金内部致密的组织结构也被破坏，横截面上出现了大量孔洞、裂纹等缺陷。在相同涂盐量下，周期涂盐法使得DD6的腐蚀程度高于单次涂盐法。结论 DD6高温热腐蚀行为与涂盐量及涂盐方式密切相关，相同涂盐方式下，涂盐量越大，DD6热腐蚀更加严重。涂盐量一定时，周期涂盐法使得DD6的热腐蚀剧烈程度大于单次涂盐法，且DD6在上述热腐蚀条件下均发生剥蚀破坏。     

Variability of tropospheric hydroperoxides at a coastal surface site in Antarctica

The annual cycles of hydrogen peroxide (H₂O₂) and methylhydroperoxide (MHP) have been investigated at a remote site in Antarctica in order to study seasonal variations as well as chemical processes in the troposphere. The measurements have been performed from March 1997 to January 1998 and in February 1999 at the German Antarctic research station Neumayer which is located at 70°39′S, 8°15′W. The obtained time series for hydrogen peroxide and methylhydroperoxide in near-surface air represents the first all-year measurements in Antarctica and indicates clearly the occurrence of seasonal variations. During polar night mean values of 0.054±0.046 ppbv (range<0.03–0.11 ppbv) for hydrogen peroxide and 0.089±0.052 ppbv (range<0.05–0.14 ppbv) for methylhydroperoxide were detected. At the sunlit period higher Mixing ratios were found, 0.20±0.13 ppbv (range<0.03–0.91 ppbv) for hydrogen peroxide and 0.19±0.10 ppbv (range<0.05–0.89 ppbv) for methylhydroperoxide. Occasional long-range transport of air masses from mid-latitudes caused enhanced peroxide concentrations at polar night. During the period of stratospheric ozone depletion we observed peroxide mixing ratios comparable to typical winter levels.     

A “measurable” definition of sustainable development based on closed cycles of resources and its application to energy systems

Human society consumes resources that it is not able to reproduce. Human activities are still based on “open cycles,” starting from a condition of natural environmental balance and reaching an environmental imbalance. The challenging scope of scientific and technological research towards sustainability appears clear if it is based on this analysis: to find development systems based on “closed cycles” of resources. The challenging objective of realizing closed cycles leads to a definition of sustainability that indicates the path to sustainable development, as well as stating the general principle. It also provides a key to the qualitative measurement of sustainability. This means that the sustainability level of a system can be measured by measuring its capacity to avoid the consumption of resources. Zero consumption is a necessary condition for sustainability, and brings about as a side effect the highly desired “zero-waste” result. Materials entering the proposed endless scheme pass through the process of usefulness without losing their capacity to feed the system again after being used. Thus, the concept of “consumption” itself is replaced by one of “use” when resources are inserted into closed loops capable of feeding human development. The application of the closed cycle sustainability criterion particularly displays its feasibility, and a theoretical guiding role, in the energy sector. Energy vectors such as hydrogen and electricity enable the closure of the energy resources loop by effectively approaching the objective of “zero consumption” (and the side result of “zero waste”) through already demonstrated technological solutions.     

Reducing the risk level for pipelines transporting carbon dioxide and hydrogen by means of optimal safety valves spacing

In many countries where electricity generation is based on their natural resources of fossil fuels a need arises to implement new power engineering technologies that allow carbon dioxide capture. Simultaneously, efforts are made to find new energy carriers which, if fired, do not involve carbon dioxide emissions. Hydrogen is one of such fuels with this future potential which is now becoming increasingly popular. Obviously, this means that the two gases mentioned above – carbon dioxide and hydrogen – will be produced in large quantities in future, which in many cases will necessitate their transport over considerable distances. If a pipeline failure occurs, the transport of the gases may pose a serious hazard to people in the immediate vicinity of the leakage site. This paper presents an analysis of the possibility of reducing the level of risk related to pipelines transporting CO₂ and H₂ by means of safety valves. It is shown that for a 50 km long and a 0.4 m diameter pipeline transporting gas with the pressure of 15 MPa the individual risk level can be reduced from 1·10⁻⁴ to 6.5·10⁻⁷ for CO₂ and from 1·10⁻⁶ to 6·10⁻¹⁰ for H₂. The social risk can be diminished in similar proportions.     

Influence of concentration distribution of hydrogen in air on measured flammability limits

There is a clear difference between exiting data on the measured flammability limits of hydrogen-air mixture. The non-uniformity of concentration distribution of hydrogen in air is a contributor to deviations of the upper flammability limit (UFL) and the lower flammability limit (LFL) measured in different experiments. This paper presents a numerical model to simulate the gas mixing process from start to stability, to predict the concentration distribution, and to research the influence of concentration distribution of hydrogen in air on measured UFLs and LFLs. The commercial software package Fluent was used to carry out the numerical simulation for the concentration distribution of hydrogen in air in the vessels with length-to-diameter ratios (L: D) of 1:1, 3:1, 5:1 and 7:1 respectively. Based on the numerical simulation and analysis, the influence of concentration distribution on measured flammability limits was demonstrated for hydrogen in air in the vessel. It is found that the deviations of measured flammability limits of hydrogen in air are the minimum in the vessel with length-to-diameter ratio of 1:1, and augment with the augmentation of vessel length-to-diameter ratio. Moreover, it is presented that the deviations of measured flammability limits of hydrogen in the center of the vessel are lower than that in the top and the bottom.     

Bioreduction of vanadium (V) in groundwater by autohydrogentrophic bacteria: Mechanisms and microorganisms

As one of the transition metals, vanadium (V) (V(V)) in trace amounts represents an essential element for normal cell growth, but becomes toxic when its concentration is above 1 mg/L. V(V) can alter cellular differentiation, gene expression, and other biochemical and metabolic phenomena. A feasible method to detoxify V(V) is to reduce it to V(IV), which precipitates and can be readily removed from the water. The bioreduction of V(V) in a contaminated groundwater was investigated using autohydrogentrophic bacteria and hydrogen gas as the electron donor. Compared with the previous organic donors, H₂ shows the advantages as an ideal electron donor, including nontoxicity and less production of excess biomass. V(V) was 95.5% removed by biochemical reduction when autohydrogentrophic bacteria and hydrogen were both present, and the reduced V(IV) precipitated, leading to total-V removal. Reduction kinetics could be described by a first-order model and were sensitive to pH and temperature, with the optimum ranges of pH 7.5–8.0 and 35–40°C, respectively. Phylogenetic analysis by clone library showed that the dominant species in the experiments with V(V) bioreduction belonged to the β-Proteobacteria. Previously known V(V)-reducing species were absent, suggesting that V(V) reduction was carried out by novel species. Their selective enrichment during V(V) bioreduction suggests that Rhodocyclus, a denitrifying bacterium, and Clostridium, a fermenter known to carry out metal reduction, were responsible for V(V) bioreduction.     

连续流动法测定沉积物中的酸挥发性硫化物

优化沉积物中酸挥发性硫化物(Acid Volatile Sulfide,AVS)的提取方法并采用连续流动分析法检测提取液中的硫化物.研究了吸收液的种类、氮气流量与吹气的时间和反应温度对AVS提取效果的影响以优化提取方法.结果表明,与传统的氢氧化钠或硫酸镉-氢氧化钠吸收液相比,以氯化锌-羧甲基纤维素钠溶液为吸收液吸附效率好,稳定性高且无毒.用连续流动分析法检测提取液中的AVS快速、准确、稳定性好.     

Propagation and intensity of blast wave from hydrogen pipe rupture due to internal detonation

The coupled fluid-structure-rupture model was developed to study the propagation and intensity of blast wave from hydrogen pipe rupture due to internal detonation. The dynamic rupture of pipe and propagation of blast wave were well coupled together in every timestep during the simulation. The numerical model was validated with experiments in terms of both typical rupture profiles and blast overpressures. Results reveal that crack branching of pipe can dramatically increase the rupture opening rate which controls the intensity and shape of the resultant blast wave. Due to the process of crack initiation and extension, the blast wave out of the pipe first forms and then is strengthened by the subsequent compression waves. This makes the maximum peak overpressure appears at a certain standoff distance above the rupture. Despite consuming some percentages of energy, the dynamic rupture of pipe generally presents positive effects (up to 2–3 times) on the blast wave intensity along the jetting direction due to the convergence effect of rupture opening on the release of internal high-pressure gas. Finally, through defining normalized overpressure and impulse based on the same hydrogen detonation in open spaces, the quantitative influences of pipe rupture on the blast wave intensity in cases of different detonation pressures and standoff distances are clarified.