GO-nafion composite membrane development for enabling intermediate temperature operation of polymer electrolyte fuel cell

Increasing Polymer Electrolyte Fuel Cells’ (PEFCs) operating temperature has benefits on the performance and the ease of utilisation of the heat generated; however, efforts for high temperature PEFCs have resulted in high degradation and reduced life time. In the literature, conventional low temperature (T < 80 °C) and high temperature (140–200 °C) regimes have been extensively studied, while the gap of operating at intermediate temperature (IT) (100–120 °C) has been scarcely explored.The main bottleneck for operating at IT conditions is the development of a suitable proton exchange membrane with comparable performance and lifetime to the commercially used Nafion operating at conventional conditions. In this work, composite membranes of Graphene Oxide (GO) and Nafion of varied thickness were fabricated, characterised and assessed for in-situ single cell performance under automotive operating conditions at conventional and intermediate temperatures.The material characterisation confirmed that a composite GO-Nafion structure was achieved. The composite membrane demonstrated higher mechanical strength, enhanced water uptake, and higher performance. It was demonstrated that by utilising GO-Nafion composite membranes, an up to 20% increase in the maximum power density at all operating temperatures can be achieved, with the optimum performance is obtained at 100 °C. Moreover, the GO-Nafion membrane was able to maintain its open circuit voltage values at increased temperature and reduced thickness, indicating better durability and potentially higher lifetime.     

Impacts of the subsurface storage of natural gas and hydrogen mixtures

The subsurface storage of hydrogen (H₂) provides a potential solution for load-balancing of the intermittent electricity production from renewable energy sources. In such technical concept, surplus electricity is used to power electrolyzers that produce H₂, which is then stored in subsurface formations to be used at times when renewable electricity is not available. Blending H₂ with natural gas (NG) for injection into depleted gas/oil reservoirs, which are already used for NG storage, is considered a good option due to the lower initial capital cost and investment needed, and potential lower operating costs. In this study, the potential impact of storing a mixture of H₂ and NG in an existing NG storage field was investigated. Relevant reservoir, caprock and cement samples from a NG storage formation in California were characterized with respect to their permeability, porosity, surface area, mineralogy and other structural characteristics, before and after undergoing 3-month incubation experiments with H₂/NG gas mixtures at relevant temperature and pressure conditions. The results indicated relatively small changes in porosity and mineralogy due to incubation. However, the observed changes in permeability were more dramatic. In addition, polymeric materials, similar to those used in NG storage operations were also incubated, and their dimensions were measured before and after incubation. These measurements indicated swelling due to the exposure to H₂. However, direct evidence of geochemical reactions involving H₂ was not observed.     

半干法烟气脱硫脱硝除尘一体化技术在焦化厂中的应用

介绍了焦化厂半干法烟气脱硫脱硝除尘一体化技术在焦化厂中的应用,描述了半干法烟气脱硫、低温选择性催化还原法(SCR)脱硝+除尘一体化工艺流程,该工艺运行效果、运行参数、工艺技术的特点,运行中常见问题及解决方法和未来需要进一步思考和解决的问题等。实践证明,该工艺技术在焦化厂能够长期稳定运行,脱硫脱硝及除尘效果较好,烟气指标可达到环保要求。     

Characterization of the ash deposits along deep-cooling of the exhaust gas in coal-fired power plants

Ash deposition and condensation of acid vapors under deep-cooling of exhaust gas in a 1000 MW ultra-supercritical power plant were investigated. X-ray diffraction, X-ray fluorescence and laser particle size analyzers were employed to characterize the components, elements and particle size distribution of deposits at different metal wall temperatures. The results show that the deposits formed at the metal wall temperatures of 40 °C–60 °C were much thicker than the deposits at 70 °C–90 °C from the perspectives of the morphology and thickness. Fluorides and chlorides were observed in deposits formed at the metal wall temperatures of 40 °C–60 °C. Thin deposits were composed of Al-Si oxides and simple sulfates when the metal wall temperatures were 70 °C–90 °C. The dew-point temperatures of water, HCl and HF vapors were around 40 °C, 60 °C, and 60 °C, respectively. Basic ferric, aluminum and calcium sulfates, which were acted as traps to absorb the condensate and fly ash. Hydration played an important role in the growth of deposits formed at the metal wall temperature of 40 °C–60 °C.     

含新型有机硅缓蚀剂的制备及性能研究

为了研究缓蚀剂组分及添加条件对发射药性的影响,设计并制备了一种含新型有机硅的缓蚀剂材料;采用烧蚀管法,对比石蜡+TiO2型缓蚀剂,研究了新型有机硅缓蚀剂的静态降烧蚀效果;采用密闭爆发器研究了不同缓蚀剂添加条件对高能硝胺发射药点火和燃烧性能的影响;采用14.5mm弹道枪和壁温测试装置,研究不同缓蚀剂添加条件对膛壁温度、内弹道性能和枪口烟雾的影响。结果表明,采用含新型有机硅的缓蚀剂,降烧蚀效果更为显著;随着缓蚀剂添加量的增加,压力峰值、弹丸初速也会产生小幅下降,但总体影响幅度较小;添加缓蚀剂后,射击过程膛壁峰值温度显著下降,下降幅度随着缓蚀剂添加量的增加而增加,在缓蚀剂质量分数为3%时,对身管壁温降低幅度可达17.1%,且产生的枪口烟雾量较少;在缓蚀剂质量分数为5%时,缓蚀剂添加过量,枪口产生较大烟雾。该缓蚀剂及添加条件有望应用于低烧蚀发射药配方中。     

高温烟气中煤焦气化行为

针对高温烟气中煤焦的气化行为，本文采用FactSage 6.1计算了煤焦在高温烟气下的高温反应特性，并利用热重分析仪分析了煤焦气化行为。通过沉降炉实验进一步研究了不同温度、气体配比、粒径条件下气体产物的动态析出特性，同时计算了评价指标α、β、LHV值。结果表明：随着温度的升高，气体产物H₂和CO的含量增加，β、α、LHV值增大，CH₄和CO₂的含量下降。在温度为1200℃时，β、α值分别由CO₂/CO比为10∶70时的10.80%、5.21%增加到CO₂/CO比为50∶30时的24.71%、41.06%。同时，随着CO₂/CO比值的增大，高温烟气对煤焦气化反应抑制减弱。通过对比反应温度和粒径对煤焦气化反应的影响，得出反应温度远大于粒径对煤焦气化反应的影响。通过实验验证了向高温烟气中喷吹煤焦制备高品质可燃气体方法的可行性。     

垂直矩形窄通道启动过程壁温变化特性研究

以去离子水为介质，对竖直矩形窄通道在启动过程中壁面温度的变化规律进行了研究。将一次启动与二次启动时壁面温度的变化特性进行了对比，并改变入口温度，研究了入口温度对启动壁面温度的影响。结果表明：一次启动时壁面温度经过三个阶段，即急剧上升阶段、缓慢升高阶段、缓慢上升至最高壁面温度后又缓慢降至稳态饱和沸腾阶段；二次启动时产生的沸腾滞后现象较一次启动时明显；提高入口温度可增加饱和沸腾段，减少壁面温度的波动，在一定程度上可避免壁面温度过冲对换热器的损坏。     

Structural characteristics and flammability of low-order coal pyrolysis semi-coke

This study focused on the effects of pyrolysis temperature on the structural characteristics and combustion properties of low rank coal. The combustion performance of semi-coke at different temperatures was studied by using low-temperature pyrolysis technology and non-isothermal thermogravimetric analysis. The variation of functional groups and carbon structure was quantitatively analyzed. The results show that the temperature has a significant effect on the semi-coke structure and flammability. In the middle and low temperature pyrolysis stage, the removal of water, volatile matter and functional groups is mainly carried out, and the degree of condensation and graphitization of carbon atoms is not obvious. The semi-coke performance with a pyrolysis temperature of 1023K is close to that of anthracite. The pyrolysis process is accompanied by the destruction of carbonaceous and the formation of mesopores, which affects the combustion performance. As the temperature increases, the flammability of the semi-coke is lowered, and the chemical structure of the semi-coke is a major factor affecting the flammability. The method of Coast-Redfern integration was used to calculate the kinetic parameters of the semi-coke. As the pyrolysis temperature increases, the activation energy of the combustion reaction increases, which is consistent with the trend of combustion performance change.     

630℃超超临界二次再热塔式锅炉热力特性与壁温耦合计算研究

630℃超超临界火电技术作为下一代超超临界发电技术,对于煤炭资源的节约、发电机组的经济性以及环境改善,都显示了优越性。目前630℃超超临界锅炉的热力计算还缺乏相关研究。本文以某1000MW超超临界二次再热塔式锅炉布置方案为例,将锅炉管道、炉膛、高温受热面作为串联管路计算,在工质侧将热力计算与管路计算进行耦合建立数值分析模型。该计算模型能够同时得到比实现水动力和热力计算更精细的结果,对后续700℃工程持续优化提升做好技术储备。