Effects of hydrocarbon impurities,vibrational relaxation,and boundary-layer-induced pressure rise on the ignition of H2–O2‒Ar mixtures behind reflected shock waves

The results of an experimental and theoretical study of the ignition of H₂–O₂?Ar mixtures behind reflected shock waves are reported. The experiments are performed with mixtures containing from 0.15 to 8.0% H₂ and from 0.75 to 2.0% O₂ at temperatures of 980–1800 K and a total gas concentration of (1.0 ± 0.1) × 10^?5 mol/cm³. The progress of the process is monitored by recording the time evolution of the pressure behind the reflected shock wave and the intensity of the chemiluminescence of electronically excited OH1 radicals (λ = 308 ± 2.5 nm). A numerical model capable of predicting the effects of additional factors, such as hydrocarbon impurities, the vibrational relaxation of the test mixture, and boundary-layer-induced pressure rise, is developed and used to simulate our own and published experimental data on the ignition of H₂–O₂?Ar mixtures. It is demonstrated that the best agreement between experimental and theoretical results is achieved when all the additional factors are taken into account. A sensitivity analysis shows that the effects of the vibrational relaxation of the test mixture and the presence of hydrocarbon impurities are significant only for lean mixtures, whereas the influence of the boundary-layer-induced pressure rise is important across a wide range of stoichiometries at long ignition delay times. Additionally, an analytical model is developed, which takes into account the finite time of the chain?propagation reactions O + H₂ and OH + H₂. The predictions of the numerical and analytical models are demonstrated to be in close agreement for a wide range of mixture compositions and experimental conditions.     

应用于羊肉脱膻的三种发酵剂筛选及发酵特性研究

为筛选出适合发酵羊肉制品的优质发酵剂，对肉葡萄球菌（Staphylococcus carnosus）、植物乳杆菌（Lactobacillus plantarum）和戊糖片球菌（Pedicoccuspentosaceus）的发酵特性进行研究，通过耐盐、耐亚硝酸盐、产酸能力、蛋白质和脂肪分解能力、膻味脂肪酸降解能力、抑菌能力、菌种间拮抗作用等试验对其筛选。结果表明，三株菌对食盐和亚硝酸盐具有较好的耐受性，能在6%的食盐溶液和150 mg/L亚硝酸盐溶液中存活，具有一定产酸能力，除植物乳杆菌无脂肪酶活性，其他两株菌具有蛋白质和脂肪降解能力，膻味脂肪酸降解率可达60%～80%，能抑制病原微生物的生长，且三株菌间无拮抗作用，对羊肉制品的风味和品质无负面影响。因此肉葡萄球菌、植物乳杆菌和戊糖片球菌可进一步应用于发酵羊肉制品的生产和开发。     

预浸出对硫化铜精矿硫酸化焙烧处理的影响

采用硫酸化焙烧-浸出-电积工艺来处理硫化铜精矿时增加预浸出可以使得铜浸出率增加，焙砂浸出液中影响铜电积的主要杂质元素Fe、Mn、Co等含量降低，预浸出段酸矿比0.3:1、温度50 ℃、时间3 h、液固比1:1时，Cu的最终浸出率大于99%，焙砂浸出液中Fe、Mn含量分别为0.12g/L和0.005g/L。通过预浸出段正交试验，确定了酸矿比对各个元素的浸出率影响最大，当酸矿比0.6:1，温度70 ℃，时间2 h，液固比1:1时，Fe的渣计浸出率为93.61%，Mn的渣计浸出率为59.50%，Mg的渣计浸出率为32.97%。     

Impact of bioethanol impurities on steam reforming for hydrogen production: A review

Hydrogen fuel cells (H₂–FCs) are promising devices for pollution-free and efficient power production. Renewable H₂ from biomass is often produced through catalytic ethanol steam reforming (ESR), which requires a steam/ethanol molar ratio of at least three. The bioethanol obtained by biomass fermentation contains large amounts of water and can be directly subjected to ESR without complex purification steps. However, a wide spectrum of impurities is present in such bioethanol samples, thus complicating the ESR process. Acetic acid, fusel alcohols, ethyl acetate, and sulfur components have been reported as important bioethanol impurities, and also as the main precursors of carbon deposits on the ESR catalyst. On the other hand, amines, methanol, and aldehydes, which are minor bioethanol impurities, have been reported to enhance the H₂ production. This review seeks to define alternatives to reduce the above negative impurities and increase the positive ones during biomass pretreatment and fermentation. Additionally, ESR catalysts are reviewed to identify the features that make them more resistant to deactivation. The combination of strategies to control the impurities during biomass pretreatment, fermentation, purification and the development of highly resistant catalysts may allow processes to produce H₂ from biomass with a low carbon footprint, rendering H₂–FCs an environmentally friendly technology for power production.     

A facile pathway to prepare molybdenum boride powder from molybdenum and boron carbide

Molybdenum boride is an ideal hard and wear-resistant material. In this study, a new method is proposed for preparing molybdenum boride, by which Mo first reacts with B₄C to generate the mixture of molybdenum boride and C, and then the product is decarburized by molten Ca to generate CaC₂. Pure molybdenum boride could be obtained after acid leaching to remove the by-product CaC₂. According to the experimental and thermodynamic calculation results, it is concluded that the single-phase MoB could be successfully prepared, while Mo₂B, Mo₂B₅, and MoB₄ could not be synthesized by this method. Moreover, it was found that the particle size of finally prepared MoB is determined by particle size of raw Mo powder. The residual carbon content of the product could be decreased to 0.10 wt% after first reaction at 1673 K for 6 hours and then decarburization reaction at 1673 K for 6 hours.     

高档普采工作面快速搬家回撤的几点经验

通过采用特殊的支护形式及回撤方式,使高档普采工作面在搬家回撤时能够大大缩短停采时间,同时降低了材料消耗,为今后同类型采煤工作面的回撤提供了经验。     

深孔控制卸压爆破防突措施在潘三矿效果考察

从理论上分析深孔控制卸压爆破措施的防突原理,根据潘三矿1741(3)工作面实际特点,采取此措施并进行了防突措施效果考察,验证其可行性,从而使深孔控制卸压爆破这一局部防突措施,能够在相似矿井得以更好的应用。     

强夯抛填定向挤淤在地基处理中的应用

采用抛填卵石挤淤置换并辅以强夯对淤泥地基进行了处理,对处理后的地基进行了钻探、重型动力触和浅层平板载荷试验,表明此方法加固效果显著。     

金精矿氰化前的预处理

浮选药剂及硫化物是影响金精矿氰化的主要成分，通过采用解吸剂X－P脱药以及碱性充气预氧化处理，可消除或抑制有害成分的不良影响，提高金的浸出率和降低药剂的消耗。