Diffusion Behavior of Cesium,Strontium and Cobalt in Pellet Waste Package

A leaching model for a radioactive pellet package for nuclear power plant wastes was studied. Calculated results obtained in term of the model were compared with experimental ones, where volumetric averages of diffusion coefficients in the Na₂SO₄ pellet and in the cement-glass were used to solve the diffusion equation in the pellet package. Since Na₂SO₄ pellets dissolved quickly, the pellet part were simulated by saturated Na₂SO₄ solution. The leaching ratios were meaured with different volume ratios of cement-glass in the package to discuss the validity of the model. The cement glass diffusion coefficient and distribution factor, which were required to solve the equation, were also measured. The calculated results agreed with the experimental ones within a 20% error.     

润磨预处理对硫酸渣精矿球团性能的影响研究

为了研究润磨对硫酸渣精矿球团性能的影响, 将配加1.7%膨润土, 15%H₂O和润磨6 min的硫酸渣精矿进行造球, 并对球团进行预热和焙烧实验研究。结果表明, 与未经润磨的硫酸渣精矿制备的球团相比较, 经润磨的精矿球团的预热温度降低150 ℃, 预热时间从12 min降低至6 min; 焙烧温度可降低75 ℃, 焙烧时间从15 min降低到8 min。在预热温度1 075 ℃, 预热时间12 min, 焙烧温度1 225 ℃, 焙烧时间13 min的优化条件下, 成品球团的抗压强度为4 726 N, 还原度指数达到87.56%, 还原膨胀指数为8.48%, 润磨精矿球团的冶金性能指标能满足高炉冶炼的要求。     

玉米芯载体吸附法固定化米根霉发酵L-乳酸的工艺条件

研究玉米芯作为部分替代碳源及载体固定化米根霉R-1发酵L-乳酸的工艺条件,考察玉米芯作为替代碳源的利用率及作为载体的添加比例和最佳粉碎粒度。研究表明：米根霉R-1以玉米芯为碳源,其利用率达14.9%;玉米芯作为部分替代碳源与葡萄糖混合发酵时最佳比例为1:4,此比例下葡萄糖对L-乳酸的转化率高达82.5%,较纯葡萄糖发酵提高了14.6%;玉米芯载体的最佳粉碎粒度为40目,此条件下米根霉R-1发酵混合碳源产酸达到34.68g/L,并形成直径为0.5～1.0mm具有连续发酵能力的固定化菌丝球,连续发酵6批,葡萄糖对L-乳酸的平均转化率为83.1%。由此得出,玉米芯可以作为良好的载体及原料直接发酵产L-乳酸。     

高温气冷堆控制棒B4C芯块的研制

阐述了用电弧炉碳热还原法制备核级B4C粉末、经热压烧结制备高温气冷堆控制棒B4C芯块的研制过程，研究了添加剂对制备B4C芯块的影响。     

Moving behavior of pellets in a pellet shaft furnace

The downward moving behavior of pellets in a 8 m2 pellet shaft furnace with an internal vertical air channel and a drying bed was studied by means of a visualized model(1-15) and a top model(1-1).The visualized model experiment shows that the downward movement of pellets can be regarded as plug flow approximately inside the furnace except for the lower region of cooling zone due to the influence of the drained hopper.The top model experiment reveals that the pellet sizes increase along the moving direction because of the percolation phenomenon,which results in a decrease of the resistance coefficient and an increase of the gas flow rate from the furnace wall toward the furnace center.     

竖炉中硫酸渣生产自熔性球团矿的研究

本文探计硫酸渣添加转炉尘及生石灰,不再细磨就可在竖炉中生产自熔性球团矿的可能性。试验表明:硫酸渣添加8％转炉尘及5％生石灰,可以不再细磨,得到质量良好的球团矿。     

THE STORAGE OF YEOMAN HOPS AND PELLETISED POWDERS

Studies have shown that on extended storage of up to 90 weeks at ambient temperature pockets of Yeoman hops lose α-acids less rapidly than do the other varieties of English hops which are rich in resins. As expected the rate of loss of α-acids is further reduced when Yeoman hops are stored in the cold. Pelletised powders made from Yeoman hops show excellent storage characteristics when commercial packs are kept for 12 months either at ambient temperature or in the cold.     

Impact of Different Hop Compounds on the Overfoaming Volume of Beer Caused by Primary Gushing

When weather conditions favour the growth of moulds on barley, beers brewed from the resulting malts often tend to gush. Certain Fusarium species (e.g., F. graminearum and F. culmorum) may cause this problem. Supersaturated with CO₂, a primary gushing beer contains an overcritical concentration of microbubbles; these are reputed to be stabilised by Fusarium‐derived hydrophobins. Research with varying brewhouse parameters has been performed to investigate the factors of primary gushing. As hops are known to contribute to a wide range of both gushing positive and negative substances in beer, the hopping regime has emerged as an important aspect. This paper examines the impact of different hop varieties on gushing. Hop oils and unsaturated fatty acids are reputed to be gushing‐suppressors. Compounds such as dehydrated humulinic acid can intensify the effect. Hop pellets, with a prevalent range of conductometric values (5–10% α‐acid), commonly employed in breweries to adjust bitterness and aroma were selected. By working with the same “gushing malt”, the spectrum of compounds in the finished beer only differed through the hop product used. The overfoaming volumes of different samples were determined according to MEBAK guidelines. Respective hop oil and fatty acid concentrations (by GC) and iso‐α‐acid contents (by HPLC) were compared and a chronological sequence of the changing percentages of beer loss is shown.     

玉米秸秆颗粒热解活化过程的热力学和动力学研究

利用热重分析研究了玉米秸秆颗粒制备活性炭的热解和活化过程.热解采用氮气为保护气体,升温速率 K/min,终温723 K,恒温时间30 min.热解过程主要发生在40～620 K之间,热解炭材微孔结构和机械强度良好.活化采用CO2为活化剂,升温速率10 K/min,终温1073 K,恒温时间20 min,活化反应主要发生在90～1070 K之间,得到的活性炭具有较大的比表面积(404.6 m²/g)和优良的吸附性能.通过对热解和活化过程的热重及差热变化综合分析,确定了两段热化学反应的活化能和频率因子.了解了热解和活化过程的热力学和动力学特性,为制备优质的生物质颗粒活性炭提供理论指导作用.     

Biosorption of 2,4-dichlorophenol from aqueous solution by Phanerochaete chrysosporium biomass: isotherms, kinetics and thermodynamics

The biosorption of 2,4-dichlorophenol (2,4-DCP) from aqueous solution on non-living mycelial pellets of Phanerochaete chrysosporium was studied with respect to pH, initial concentration of 2,4-DCP, temperature and pellet size. The fungal biomass exhibited the highest sorption capacity of 4.09 mg/g at an initial pH of 5.0, initial 2,4-DCP concentration of 50.48 mg/l, 25 degrees C and a pellet size of 1.0-1.5 mm in the investigated pH 2.0-11.0, initial concentrations of 5-50 mg/l, temperature 25-50 degrees C, and pellet size of 1.0-2.5 mm. The Freundlich model exhibited a slightly better fit to the biosorption data of 2,4-DCP than the Langmuir model. The biosorption of 2,4-DCP to biomass followed pseudo second-order adsorption kinetics. The second-order kinetic constants decreased with increasing temperature, and the apparent activation energy of biosorption was estimated to be -16.95 kJ/mol. The thermodynamic analysis indicates that the biosorption process was exothermic and that the adsorption of 2,4-DCP on P. chrysosporium might be physical in nature. Both intraparticle diffusion and kinetic resistances might affect the adsorption rate and that their relative effects varied with operation temperature in the biosorption of 2,4-DCP by mycelial pellets.