10kg/h下行床褐煤低氧气化及半焦反应特性

利用进料量10kg/h的下行床反应器对褐煤进行气化实验.与前期相同类型的小型气化炉进行比较,对比考察反应器尺度对褐煤低氧气化特性的影响.通过物理吸附手段和等离子体发射光谱仪(ICP-OES)分别研究气化半焦的孔隙结构和碱金属滞留,并应用热重分析仪(TGA)研究半焦的反应性.结果表明:10kg/h气化炉的煤气变化趋势尽管与小型气化炉的煤气变化趋势一致,但10kg/h气化炉特有的折流结构能增加煤气的停留时间,促进二次反应和大分子裂解;煤气组成中CH_4的体积分数偏高.随着气化剂中氧气体积分数的增加,10kg/h气化炉气化半焦的孔隙破裂、坍塌程度增大,半焦孔隙趋向介孔/大孔过渡.10kg/h气化炉的局部"热效应"及特有的折流结构可促进碱金属挥发,使生成半焦的碱金属滞留量减少.10kg/h气化炉气化半焦的反应性比小型气化炉半焦的反应性更低,半焦孔隙过渡所导致的反应活性位减少及半焦中碱金属滞留量减少所导致的催化作用减弱是半焦反应性更低的原因.

间歇、低流量氧气驱动雾化吸入治疗AECOPD的护理体会

目的：探究间歇、低流量氧气驱动雾化吸入治疗AECOPD的护理方法与临床效果。方法：对我院2012年11月至2013年11月期间收治的72例AECOPD患者的临床资料进行回顾性分析，将72例患者随机划分为研究组与对照组，两组各36例；对照组患者给予持续雾化吸入疗法，研究组患者给予间歇、低流量氧气驱动雾化吸入疗法，两组患者采取相应的护理方法；对比两组患者的临床治疗效果与不良反应发生率。结果：研究组患者的临床治疗效果明显优于对照组患者，且不良反应发生率明显低于对照组，两组差异具有统计学意义（P〈0.05）。结论：间歇、低流量氧气驱动雾化吸入治疗AECOPD的临床效果十分显著，值得在临床治疗中推广应用；同时，合理的护理方法能够进一步提高临床疗效。

Time evolution of coal structure during low temperature air oxidation

The time evolution of coal structure during low temperature oxidation was investigated by oxidizing coal samples in air at 120℃ for periods of up to 14 days. The structure of the oxidized coal samples was char- acterized by Fourier transform infrared spectroscopy （FFIR） and curve fitting analysis. The results show that carboxyl and ether groups are the main oxygen containing moieties in oxidized coal. Ethers are most abundant during the first 3 days of oxidation, thereafter carboxyl groups predominate. The content of carboxyl and ester functionality increases with oxidation time. The other oxygen containing groups vary in concentration over time. The amount of hydroxyl groups first decreases then increases and finally decrease again during the oxidation. The aliphatic structure and the degree of branching of the aliphatic chains is reduced as the oxidation proceeds. The proportion of aromatic structure increases with oxida- tion time. Obvious decomposition of aromatic rings occurs after about 9 days of oxidation. The aryl ester bands and the CH3/CH2 ratio both have a good linear relationship to oxidation time.

Calculation of Apparent Activation Energy of Coal Oxidation at Low Temperatures by Measuring CO Yield

By analyzing previous studies on activation energy of coal oxidation at low temperatures, a theoretical calculation model of apparent activation energy is established. Yield of CO is measured by using the characteristic detector of coal oxidation at 30-90 ℃. The impact of parameters, such as airflow and particle size, on activation energies is analyzed. Finally, agreement was obtained between activation energies and the dynamic oxygen absorbed in order to test the accuracy of the model. The results show that： 1） a positive exponential relation between concentration of CO and temperature in the process of the experiment is obtained： increases are almost identical and the initial CO is low; 2） the apparent activation energies increase gradually with the sizes of particle at the same airflow, but the gradients increase at a decreasing rate; 3） the apparent activation energies increase linearly with airflow. For the five coal particles, the differences among the energies are relatively high when the airflow was low, but the differences were low when the airflow was high; 4） the optimum sizes of particle, 0.125-0.25 ram, and the optimum volume of airflow, 100 mL/min, are determined from the model; 5） the apparent activation energies decrease with an increase in oxygen absorbed. A negative exponential relation between the two is obtained,

Experimental simulation and numerical analysis of coal spontaneous combustion process at low temperature

The characteristic of coal spontaneous combustion includes oxidative property and exothermic capacity. It can really simulate the process of coal spontaneous combustion to use the large scale experimental unit loading coal 1 000 kg. According to the field change of gas concentration and coal temperature determined through experiment of coal self ignite at low temperature stage, and on the basis of hydromechanics and heat transfer theory, some parameters can be calculated at different low temperature stage, such as, oxygen consumption rate, heat liberation intensity. It offers a theoretic criterion for quantitatively analyzing characteristic of coal self ignite and forecasting coal spontaneous combustion. According to coal exothermic capability and its thermal storage surroundings, thermal equilibrium is applied to deduce the computational method of limit parameter of coal self ignite. It offers a quantitative theoretic criterion for coal self ignite forecasting and preventing. According to the measurement and test of spontaneous combustion of Haibei coal, some token parameter of Haibei coal spontaneous combustion is quantitatively analyzed, such as, spontaneous combustion period of coal, critical temperature, oxygen consumption rate, heat liberation intensity, and limit parameter of coal self ignite.

Role of surface frustrated Lewis pairs on reduced CeO2(110)in direct conversion of syngas

Direct syngas conversion to light olefins on bifunctional oxide-zeolite(OX-ZEO)catalysts is of great interest to both academia and industry,but the role of oxygen vacancy(Vo)in metal oxides and whether the key intermediate in the reaction mechanism is ketene or methanol are still not well-understood.To address these two issues,we carry out a theoretical study of the syngas conversion on the typical reducible metal oxide,CeO2,using density functional theory calculations.Our results demonstrate that by forming frustrated Lewis pairs(FLPs),the VOs in CeO2 play a key role in the activation of H2 and CO.The activation of H2 on FLPs undergoes a heterolytic dissociative pathway with a tiny barrier of 0.01 eV,while CO is activated on FLPs by combining with the basic site(O atom)of FLPs to form CO2^2-.Four pathways for the conversion of syngas were explored on FLPs,two of which are prone to form ketene and the other two are inclined to produce methanol suggesting a compromise to resolve the debate about the key intermediates(ketene or methanol)in the experiments.Rate constant calculations showed that the route initiating with the coupling of two CO*into OCCO*and ending with the formation of ketene is the dominant pathway,with the neighboring FLPs playing an important role in this pathway.Overall,our study reveals the function of the surface FLPs in the activation of H2 and CO and the reaction mechanism for the production of ketene and methanol for the first time,providing novel insights into syngas conversion over OX-ZEO catalysts.

Study on PECVD SiO_2 /Si_3 N_4 double-layer electrets with different thicknesses

In this paper, performance of PECVD SiO 2 /Si 3 N 4 double layers electrets with different thicknesses were investigated detailedly in respect of chargeability, storage charge stability in high temperature and reliability in high humidity environment. Samples with different thicknesses of Si 3 N 4 and SiO 2 were prepared on Pyrex 7740 glass substrates and characterized by isothermal and high humidity charge decay. The results of experiment approved that the PECVD SiO 2 /Si 3 N 4 double layers electrets on glass substrate has as good chargeability and charge stability in high temperature and high humidity environment as thermal oxidation or APCVD/LPCVD ones on silicon substrates. The experiment results indicated that a Si 3 N 4 layer no less than 50 nm is necessary for good charge stability in high temperature and a Si 3 N 4 layer thicker than 500 nm decreases the chargeability. Even a 2 nm Si 3 N 4 layer is enough to significantly improve the charge stability in high humidity environment. Thick SiO 2 layer can increase the surface potential of electrets under the same charging condition and its charge stability in high temperature. However, the electrets with high surface potential also exhibit poor uniformity of charge stability in high humidity environment.

Review on carbon emissions, energy consumption and low-carbon economy in China from a perspective of global climate change

Accompanying the rapid growth of China's population and economy, energy consumption and carbon emission increased significantly from 1978 to 2012. China is now the largest energy consumer and CO2 emitter of the world, leading to much interest in researches on the nexus between energy consumption, carbon emissions and low-carbon economy. This article presents the domestic Chinese studies on this hotpot issue, and we obtain the following findings. First, most research fields involve geography, ecology and resource economics, and research contents contained some analysis of current situation, factors decomposition, predictive analysis and the introduction of methods and models. Second, there exists an inverted "U-shaped" curve connection between carbon emission, energy consumption and economic development. Energy consumption in China will be in a low-speed growth after 2035 and it is expected to peak between 6.19–12.13 billion TCE in 2050. China's carbon emissions are expected to peak in 2035, or during 2020 to 2045, and the optimal range of carbon emissions is between 2.4–3.3 PgC/year(1 PgC=1 billion tons C) in 2050. Third, future research should be focused on global carbon trading, regional carbon flows, reforming the current energy structure, reducing energy consumption and innovating the low-carbon economic theory, as well as establishing a comprehensive theoretical system of energy consumption, carbon emissions and low-carbon economy.