Advances in Microbial Strains and Bedding Materials in a Deep-Litter System for Pig Breeding

The selection and compatibility of the microbial strains and bedding materials in a deep-litter system is the primary issues for this ecological breeding technology. In this paper, we analyzed and summarized the categories of microbial strains and bedding materials suitable for a deep-litter system, the fermentation properties of different microbes, the parameter requirements of bedding materials, and the fermentation process led by functional microbial flora in a deep-litter system, with the objective to provide theoretical bases and practical guidance for the promotion of deep-litter breeding method nationwide.

Synthesis gas production using oxygen storage materials as oxygen carrier over circulating fluidized bed

A novel process for synthesis gas production over Circulating Fluidized Bed （CFB） using oxygen storage materials as oxygen carder was reported. First, oxygen in the air was chemically fixed and converted to lattice oxygen of oxygen storage materials over regenerator, and then methane was selectively oxidized to synthesis gas with lattice oxygen of oxygen storage materials over riser reactor. The results from simulation reaction of CFB by sequential redox reaction on a fixed bed reactor using lanthanum-based perovskite LaFeO3 and La0.8Sr0.2Fe0.9CO0.1O3 oxides prepared by sol-gel, suggested that the depleted oxygen species could be regenerated, and methane could be oxidized to synthesis gas by lattice oxygen with high selectivity. The partial oxidation of methane to synthesis gas over CFB using lattice oxygen of the oxygen storage materials instead of gaseous oxygen should be possibly applicable.

Oxidation Kinetics of Aluminum Powders in a Gas Fluidized Bed Reactor in the Potential Application of Surge Arresting Materials

In this technical paper, the oxidation mechanism and kinetics of aluminum powders are discussed in great details. The potential applications of spherical aluminum powders after oxidation to be part of the surging arresting materials are discussed. Theoretical calculations of oxidation of spherical aluminum powders in a typical gas fluidization bed are demonstrated. Computer software written by the author is used to carry out the basic calculations of important parameters of a gas fluidization bed at different temperatures. A mathematical model of the dynamic system in a gas fluidization bed is developed and the analytical solution is obtained. The mathematical model can be used to estimate aluminum oxide thickness at a defined temperature. The mathematical model created in this study is evaluated and confirmed consistently with the experimental results on a gas fluidization bed. Detail technical discussion of the oxidation mechanism of aluminum is carried out. The mathematical deviations of the mathematical modeling have demonstrated in great details. This mathematical model developed in this study and validated with experimental results can bring a great value for the quantitative analysis of a gas fluidization bed in general from a theoretical point of view. It can be applied for the oxidation not only for aluminum spherical powders, but also for other spherical metal powders. The mathematical model developed can further enhance the applications of gas fluidization technology. In addition to the development of mathematical modeling of a gas fluidization bed reactor, the formation of oxide film through diffusion on both planar and spherical aluminum surfaces is analyzed through a thorough mathematical deviation using diffusion theory and Laplace transformation. The dominant defects and their impact to oxidation of aluminum are also discussed in detail. The well-controlled oxidation film on spherical metal powders such as aluminum and other metal spherical powders can potentially become an important part of switch devices of surge arresting materials, in general.

Impact of train speed on the mechanical behaviours of track-bed materials

For the 30,000 km long French conventional railway lines(94% of the whole network),the train speed is currently limited to 220 km/h,whilst the speed is 320 km/h for the 1800 km long high-speed lines.Nowadays,there is a growing need to improve the services by increasing the speed limit for the conventional lines.This paper aims at studying the influence of train speed on the mechanical behaviours of track-bed materials based on field monitoring data.Emphasis is put on the behaviours of interlayer and subgrade soils.The selected experimental site is located in Vierzon,France.Several sensors including accelerometers and soil pressure gauges were installed at different depths.The vertical strains of different layers can be obtained by integrating the records of accelerometers installed at different trackbed depths.The experimentation was carried out using an intercity test train running at different speeds from 60 km/h to 200 km/h.This test train was composed of a locomotive(22.5 Mg/axle) and 7 'Corail'coaches(10.5 Mg/axle).It was observed that when the train speed was raised,the loadings transmitted to the track-bed increased.Moreover,the response of the track-bed materials was amplified by the speed rise at different depths:the vertical dynamic stress was increased by about 10% when the train speed was raised from 60 km/h to 200 km/h for the locomotive loading,and the vertical strains doubled their quasistatic values in the shallow layers.Moreover,the stressestrain paths were estimated using the vertical stress and strain for each train speed.These loading paths allowed the resilient modulus Mrto be determined.It was found that the resilient modulus(M_r) was decreased by about 10% when the train speed was increased from 100 km/h to 200 km/h.However,the damping ratio(D_r) kept stable in the range of speeds explored.

Improvement and Application of Grain Size Distribution Characteristics Calculation of Bed Material

Grain size distribution of bed material is an important characteristic for studying evolution of natural river channel by means of experimental ways and numerical modeling of flow and sediment process.In this study,the fractal characteristic of sediment particle has been defined by means of fractal theory based on ana- lyzing the property of grain size distribution of bed material in the river channel.Furthennore,the fractal prop- erty of sediment particle has been applied to judge the process of armorin...

Advances in Application of New Catalytic Materials in Petroleum Refining and Petrochemicals Production

This article introduces the solid acid catalyst for isobutene/butylenes alkylation, the HTS Ti/Si zeolite for ammonoxidation of cyclohexanone and the noncrystalline alloy catalyst and magnetically stabi- lized bed for hydrofining of caprolactam that were developed recently by SINOPEC Research Institute of Petroleum Processing (RIPP).

海相细粒沉积成因机制与有机质富集模式研究进展

综合分析了国内外细粒沉积的特征、成因及有机质富集模式研究进展。海相细粒沉积主要由黏土矿物、石英、碳酸盐矿物和有机质组成,受风力、异轻流、重力流和底流4大搬运营力作用,发育泥纹层和粉砂纹层2类纹层,单一型、顺序型和交互型3类纹层组(层系),块状层、递变层和交互层3类层(层组)。海相细粒沉积发育浊流沉积、底流沉积及远洋-半远洋沉积3种主要沉积相类型及其过渡类型。海相细粒沉积有机质存在高生产力和强保存2种富集模式,高生产力富集模式下黑色页岩主要通过“上升洋流”、“氧含量最低值区(OMZ)”和“近岸透光带缺氧(PZE)”模式形成高有机质富集,强保存富集模式下黑色页岩主要通过“受限盆地”、“改进的受限盆地”、“不规则底形”、“水洼扩张”、“海侵化变层”和“近岸海侵(TN)”模式形成高有机质富集。目前海相细粒沉积成因机制与相模式研究存在的主要问题包括名词术语不规范、不同矿物成分成因不明确,以及细粒浊流沉积、等深流沉积和半远洋沉积难以区分,需要今后进一步研究解决。

低渗煤层瓦斯抽采钻孔注浆封堵技术研究

为解决低渗煤层瓦斯抽采钻孔封孔质量差,导致的瓦斯抽采效率降低等问题,提出适用于低渗煤层瓦斯抽采钻孔的封孔材料及注浆压力的研究。通过对瓦斯抽采钻孔封孔参数的确定,选取合适的注浆材料配比,并采用COMSOL Multiphysics数值模拟封孔压力参数对注浆效果的影响。得到封孔注浆材料封孔水泥浆液配比为1:2;注浆压力应介于1.2~1.8 MPa。经现场跟踪和抽采效果分析,在注浆压力为1.8 MPa时,在孟津煤矿12070底抽巷试验了8个钻孔,发现采用所提出的注浆材料配比和注浆压力能够产生很好封孔效果,瓦斯抽采浓度有明显提升。

超厚料层烧结过程固体燃料的分布规律

铁矿烧结以固体燃料作为主要热量来源,其热量高效利用对于烧结节能减排具有重要意义。本文聚焦超厚料层烧结条件下固体燃料在料层中的分布特性,系统解析其在泥辊宽度方向以及料层高度方向的分布规律。结果表明:沿泥辊宽度方向,整体混合料粒度中间偏细、两侧略粗,而含碳量则为中间偏高、两侧略低;布料之后,台车宽度方向混合料粒度组成和含碳量与泥辊对应位置处的混合料规律一致;在料层高度方向上,自上而下混合料粒度整体呈增大趋势,含碳量则逐渐减小,由于泥辊与九辊布料的偏析程度有限,在部分高度处粒度与含碳量会出现波动;利用台车高度方向混合料的粒度组成和泥辊下料处各粒级的含碳量计算出沿料层高度方向的燃料分布,与实际规律基本一致。研究结果可为超厚料层烧结过程固体燃料的优化分布提供指导。

仿生葫芦储热单元潜热蓄热堆积床数值研究

在碳达峰与碳中和的“双碳”能源背景下,传统封装相变材料(PCM)的储热单元与潜热储热堆积床(LHTES)系统无法满足当前的储热需求,而仿生学在储热领域的应用,可以为二者储热效率的提升提供一种全新的思路。为此,提出一种仿生葫芦结构的新型储热单元以增加传热面积,提高LHTES系统的热性能。优化仿生葫芦单元结构的尺寸参数对单元熔融特性的影响,确定最优熔融特性的尺寸参数。分析传统球形和仿生葫芦LHTES的温度分布、液相率、蓄热能力等性能指标的影响。结果表明,葫芦结构可提升14.5%的单元换热面积,与传统模型相比,仿生模型液相率和储热完成率最大可分别提升12.67%和6.2%。在此基础上,分析入口温度和流速对系统性能的影响,结果表明,进口温度对系统的储热性能影响较大,进口温度增大15 K,堆积床系统的储热时间比原来缩短59.6%。该研究可为优化LHTES系统、提高实际条件下的热性能提供参考。

基于圆柱封装单元的水合盐相变储热填充床的储释特性实验研究

水合盐相变储热技术具有储热密度高、成本低等优势,在清洁供暖中具有广阔应用前景。本研究设计并搭建了以三水合乙酸钠作为储热材料,以圆柱形相变材料封装单元作为基础单元的填充床相变储热装置。通过实验研究填充床储热装置的运行特性,研究了流量和储热温度对装置的储释热用时、出口温度、热效率及储热密度的影响。实验结果表明:提高储热温度和增大流量可缩短储热用时、提升热效率和储热密度。储热装置的热效率可达94.73%,储能密度可达71.77 kW·h/m^(3)。

黄河下游近期持续冲刷过程中床沙粗化特性分析

床沙组成的变化影响悬沙沿程恢复及河床阻力变化。本文基于黄河下游7个水文站1999—2020年的实测床沙资料,计算了各水文断面不同粒径组床沙占比的年际变化,分析了近二十年持续冲刷过程中不同河型河段床沙的时空粗化特性,讨论了河床冲淤过程对床沙粗化的影响。从时间来看,小浪底水库运用后,不同时期床沙的粗化特点不同,拦沙初期(2000—2006年)急剧粗化,拦沙后期(2007—2020年)粗化放缓,高村站及上游各站床沙呈波动粗化,高村站以下则变化不大,且粗化程度最强处由游荡段向下游过渡段转移;从空间来看,床沙沿程细化,游荡段以极粗沙为主,过渡段以粗沙和极粗沙为主,弯曲段的中细沙不可忽视。拦沙初期各河段床沙组成的调整表现为中细均冲;拦沙后期则表现为中粗均冲,极粗沙占比增大,利津以上各站细沙占比不足5%,对悬沙的补给受限,中沙和粗沙仍经受冲刷,极粗沙对相应悬沙有较好补给作用。河段汛后床沙中值粒径与河床累计冲刷量呈良好的幂函数正相关关系,但拦沙后期床面已粗化到相当程度,河床冲淤对床沙粗化的影响受限。研究结果有助于掌握近期整个黄河下游床沙的粗化现状及预测下游河道冲淤变形规律。

基于响应面法的采空区充填材料配比优化研究

为解决采空区垮落和瓦斯扩散问题,分别选用矿渣、粉煤灰和水泥作为充填材料的骨料、细料和胶结剂,采用响应面法(Response Surface Method,RSM)设计配比试验,以质量浓度、材料比例和矿渣粒径作为单因素影响因子,材料流动性、抗压强度和渗透率为响应目标值,分析料浆质量浓度、材料比例和矿渣粒径对充填材料流动性、抗压强度和渗透性能的影响规律,并建立非线性回归方程,优化多目标条件下的充填材料配比。研究结果表明:①粉煤灰的火山灰效应会影响充填材料的水化反应进程,随着粉煤灰比例增大,各龄期的抗压强度先增大后减小,各龄期的渗透率增大;②矿渣表面粗糙,密度变化较大,在养护后期,随着矿渣粒径增大,材料抗压强度先增大后减小,材料渗透率减小;③充填材料的最佳材料配比为水泥∶粉煤灰∶矿渣=1∶3∶5,其中料浆质量浓度为80%,矿渣粒径为5~10 mm;④该配比条件下的充填材料浆体流动度为20.5 cm,14 d渗透率为0.021×10^(-14)m^(2),14 d抗压强度为22.2 MPa。研究成果为采空区减沉与瓦斯封存协同治理提供了基础参数和理论依据。

Research progress in CALPHAD assisted metal additive manufacturing

Metal additive manufacturing(MAM)technology has experienced rapid development in recent years.As both equipment and materials progress towards increased maturity and commercialization,material metallurgy technology based on high energy sources has become a key factor influencing the future development of MAM.The calculation of phase diagrams(CALPHAD)is an essential method and tool for constructing multi-component phase diagrams by employing experimental phase diagrams and Gibbs free energy models of simple systems.By combining with the element mobility data and non-equilibrium phase transition model,it has been widely used in the analysis of traditional metal materials.The development of CALPHAD application technology for MAM is focused on the compositional design of printable materials,the reduction of metallurgical imperfections,and the control of microstructural attributes.This endeavor carries considerable theoretical and practical significance.This paper summarizes the important achievements of CALPHAD in additive manufacturing(AM)technology in recent years,including material design,process parameter optimization,microstructure evolution simulation,and properties prediction.Finally,the limitations of applying CALPHAD technology to MAM technology are discussed,along with prospective research directions.

Succession of bacteria communities during production and application of dairy bedding by membrane-covered aerobic fermentation

The cost of dairy manure treatment and bedding material purchase increases the operating cost of the dairy farm.Membrane-covered aerobic fermentation system has been widely used for dealing with dairy manure and recycling the final product as bedding material.However,the microbial safety in each processing step is still uncertain.To better understand the bacterial community dynamics during the whole bedding conversion process,a full-chain and large-scale experiment including 16-day membrane-covered aerobic fermentation and 11-day bedding material application was conducted.The results showed that the pile temperatures in the fermentation stage rapidly increased to 80°C and maintained>50°C for more than 11 days and the use of fermentation product as bedding material provided cows with a stable and comfortable bedding environment.The Chao1 and Shannon index decreased at the end of the fermentation stage and remained stable in the application stage,indicating that membrane-covered aerobic fermentation effectively killed some pathogenic bacteria and guaranteed both the maturity and stability of the final product.The dominant bacteria in the fermentation stage were Acinetobacter,Thermus,and Rhodothermus at genus level.Seven common potential pathogens of mastitis(Staphylococcus,Enterococcus,Serratia,Pseudomonas,Corynebacterium,Mycobacterium,and Bacillus)were found at the end of fermentation stage but the relative abundance was low(0.0025%-0.2727%).The dominant bacteria in the application stage mainly included Acinetobacter,Pseudomonas,and Flavobacterium at the genus level.The relative abundance of Pseudomonas increased in the application stage,which was a reminder to the dairy farm to pay attention to the disinfection and timely replacement of bedding material to prevent the occurrence of dairy mastitis.The results of this study contributed deep understanding of the microorganism-driven bedding conversion process and provide practical guidance and cautions for the bedding materials application.

超高料层烧结工艺下优化料层透气性生产实践

传统烧结料层厚度因料层透气性被限制在750~800 mm,从而影响了烧结矿的生产效率。在不影响烧结矿质量的前提下,改善料层透气性,有效提高烧结料层厚度已成为进一步提高烧结矿生产效率的重要途径。涟钢360 m 2烧结机,通过加强制粒性能,优化原料结构,改进生石灰下料设备,优化圆筒混合机扬料角钢方式等措施,强化制粒,改善了烧结料层的透气性。相比于料层厚度700~750 mm烧结,料层厚度950~1000 mm超高料层条件下,烧结矿的转鼓强度逐步提高至79.23%,利用系数稳定在1.50 t/(m^(2)*h)以上,固体燃耗稳定在51.48 kg/t,返矿配比降低至21.52%,为超高料层烧结(1000 mm)提高烧结矿生产效率提供了参考。

凌钢1^(#)烧结机提高烧结矿转鼓强度生产实践

介绍了2021年以来凌钢第二炼铁厂1^(#)烧结机为了提高烧结矿转鼓强度而进行的系列生产实践。结果表明,采用厚料层烧结、实行生产参数标准化控制、强化热风烧结作用、提高混合料布料精度、提高机前混合料温度等措施可有效提高烧结矿转鼓强度,满足高炉的生产需要。

循环流化床锅炉分离器靶区耐火材料损坏原因分析及防治

循环流化床锅炉脱硝改造后,锅炉分离器靶区耐火材料频繁脱落,导致埋藏在耐火材料内的汽冷管受到烟尘高速冲刷而爆管停炉。通过分析靶区耐火材料脱落原因,对脱硝系统与耐火材料进行优化改进并采取相应预防措施,使得靶区耐火材料运行寿命大大提升。

复掺纤维水泥改良风积沙抗压强度试验研究

和若铁路(和田—若羌)DK111+500—DK111+800段的风积沙为C3间断级配细沙,不能直接用作铁路路基基床填料。为了对风积沙进行改良,考虑在其中单独掺加聚丙烯纤维,以及将聚丙烯纤维分别与玄武岩纤维、玻璃纤维、聚酯纤维按质量比1∶1复掺。不管单掺还是复掺,纤维掺量(质量分数)均分别取6‰、8‰、10‰,水泥掺量(质量分数)为5%,养护龄期7 d。通过无侧限抗压强度试验,研究不同纤维单掺和复掺对水泥改良风积沙应力、应变、无侧限抗压强度和割线模量的影响。结果表明:与相同掺量的单掺试样相比,掺量为6‰、8‰时复掺聚丙烯纤维与玻璃纤维试样峰值应力小幅增大,其他复掺试样峰值应力均减小;不同纤维复掺对水泥改良风积沙无侧限抗压强度增强效果不明显,但对水泥改良风积沙割线模量影响明显;掺量8‰时复掺聚丙烯纤维与玻璃纤维试样无侧限抗压强度比单掺试样增大6.53%,而其他复掺试样无侧限抗压强度均比相同掺量单掺试样减小0.21%~11.73%;不同掺量下复掺试样割线模量均比单掺试样大,掺量6‰时复掺聚丙烯纤维与玄武岩纤维试样割线模量比单掺试样增加了1.12倍。研究结果可为沙漠地区铁路路基基床表层填料改良设计及施工提供参考。

600 MW CFB锅炉汽冷式旋风分离器受热面管失效分析及优化措施

基于超临界循环流化床(CFB)锅炉汽冷式旋风分离器受热面管发生的1次失效,为防止类似失效的再次发生,对失效进行试验分析。超低排放选择性非催化还原(SNCR)脱硝系统对耐火材料和受热面管有腐蚀,在高温下分解的产物与受热面管金属发生反应,引起受热面的有效壁厚减薄,最终受热面管因无法承受内部介质的压力而发生失效。结合运行状况及失效原因分析,对耐火材料进行固定方式优化和材料优化,以及提高防磨防爆检查力度、优化雾化空气压力等优化措施,有效提升了运行的可靠性,在汽冷式旋风分离器检修管理方面有推广意义。