脱硫联合单元气动调节阀故障浅析

总结中海炼化惠州炼化分公司脱硫联合单元气动调节阀故障处理经验,分析现场调节阀故障产生的原因,对现场反复处理的调节阀故障提出整改方案,也为以后类似的故障处理积累了经验.     

试论石油化工企业仪表自动化设备的故障预防与维护措施

本文通过对化工生产过程中仪表故障故障处理措施的分析,说明了怎样在生产过程中检查与处理仪表的故障,对如何处理与判断仪表常见故障提供了一种工作思路与方法。     

探析井下皮带运输机的常见故障及处理

针对井下皮带运输机的常见故障及处理进行分析,阐述了几点经常发生的故障,并结合这些故障特点,分析如何对这些故障进行处理。     

旋转设备常见故障和处理方法

通过对水泥生产旋转设备常见故障进行分析和处理,发现设备的振动现象表现形式虽然是单一的,但对应的故障原因往往大不相同,有些故障现象比较常见,但处理起来又无从下手,如果判断失误既浪费人力物力,又会造成失修欠修,故障现象还是依旧。因此我们结合现场实际情况,采用状态监测、故障识别与预知维修新技术对故障加以甄别,快速找到故障原因和处理方法,实现设备管理由定性向定量的全面技术转型。本文就几种故障类型进行汇总。     

低压煤浆泵电机变频器过流故障的原因及对策

介绍了对充矿鲁南化肥厂水煤浆气化技术中低压煤浆泵电机变频器出现的几次过流故障处理过程,并以此为基础总结出引发此类故障的多种原因和处理方法,对变频器故障原因分析及处理具有很参考价值。     

抽油机井井下故障鉴定及处理方法

抽油机井是油田常见井,对抽油机井井下故障判断,是维护及处理故障的依据,结合油田现场生产实际,本文分析了目前抽油机井常见井下故障判别方法及处理方法,并提出了井下故障后作业现场跟踪鉴定方法     

煤矿带式输送机常见故障问题与处理探究

带式输送机是煤矿生产中一种常见的设备,用于提高生产效率,具有诸多的优势,针对带式输送机使用过程中的故障问题要进行早期防范治理,保证矿山生产安全性和高效性。本文对带式输送机的特点展开了讨论,分析了常见的故障和处理措施。对跑偏故障、打滑故障、断带故障、断裂故障的原因和具体的处理方法进行了讨论,用于煤矿生产活动的指导和管理。     

煤化工机电设备的故障分析及处理

现代产业发展背景下,对煤化工产品的需求不断增加。而机电设备作为煤化工产业生产工作开展的基础设备体系,对其故障进行分析与处理对于煤化工产业发展具有重要意义。本文对新时期背景下煤化工机电设备故障分析及处理的意义展开分析,探究现阶段煤化工机电设备常见的故障问题及故障原因,在此基础上提出煤化工机电设备故障处理的主要措施,以推动煤化工产业现代化发展。     

煤矿变电站运行的安全管理及故障处理探究

在现阶段我国的社会经济快速发展中,煤矿变电站的运行和管理活动要向着高效化的方向探索,提高运行管理的规范化水平。本文对煤矿变电站运行的原理、煤矿变电站运行中的故障类型、煤矿变电站运行安全管理及故障防治的要点展开了讨论,通过掌握运行原理,对操作故障和管理不当引起的故障进行防治,在检查线路,以及处理变压器故障、电容器故障、无功补偿装置故障、直流系统故障问题方面,提高故障的处理水平和变电站运行安全管理效率。     

直流接地故障原因与处理方法

分析了直流接地故障的原因,介绍了对故障的处理方法。     

机制砂岩性与级配对混凝土抗硫酸盐侵蚀性能的影响

为了探究不同岩性、不同级配机制砂对混凝土性能的影响,对三种不同岩性机制砂混凝土及天然河砂混凝土的工作性和抗压强度进行研究。此外,对比分析了四种混凝土在干湿循环制度下的抗硫酸盐侵蚀性能。结果表明,天然河砂混凝土的工作性优于机制砂混凝土,钙质机制砂混凝土的工作性略好于硅质机制砂混凝土。机制砂混凝土的抗压强度优于天然河砂混凝土,在硫酸盐侵蚀循环作用下的力学性能变化趋势与天然河砂混凝土基本一致。在相同级配条件下,机制砂混凝土的抗蚀系数高于天然河砂混凝土;机制砂岩性并不会对混凝土抗硫酸盐侵蚀性能带来负面影响。级配良好的机制砂可以增强混凝土抗压强度和抗硫酸盐侵蚀性能。     

Functional properties of proteins in foods

The measurement of functionality of protein food ingredients has developed somewhat haphazardly, probably due to the wide range of proteins used as ingredients and the diversity of foods. Studies of the physiochemical properties of proteins should enable prediction of a proteins response to process environments and prove more fruitful than many of the empirical measurements of functionality. The effects of pH, salt type and concentration on the phase behaviour of the oilseed globulin and arachin, demonstrates the complexity of protein solubility and the inadequacies of simple tests that have arisen. Studies of the effects of salts and conditioning on meat fibres, coupled with measurement of the location of water in pellets from water holding tests enable the latter to be applied with increased confidence. Comparison of the endothermic transitions observed on heating with the development of storage and loss moduli allow the contributions of domains of skeletal muscle myosin to gel structure to be investigated.     

Failure of tannic acid to inhibit digestion or reduce digestibility of plant protein in gut fluids of insect herbivores

The rate of hydrolysis of the abundant foliar protein, ribulose-1,5-bisphosphate carboxylase/oxygenase (RuBPC), in enzymatically active gut fluid ofManduca sexta larvae is very rapid and is unaffected by the presence of tannic acid, even when tannic acid is present in the incubation mixture in amounts in excess of the amount of RuBPC. When this protein is dissolved in the denatured gut fluids ofM. sexta larvae orSchistocerca gregaria nymphs, large amounts of tannic acid must be added to bring about the precipitation of significant quantities of protein. The ability of insect gut fluid to prevent the formation of insoluble tannin-protein complexes is due to the presence of surfactants. On the basis of our results and a review of the findings of other investigators, we argue that there is no evidence that tannins reduce the nutritional value of an insect's food by inhibiting digestive enzymes or by reducing the digestibility of ingested proteins and, further, that the failure of tannins to interfere with digestion is readily explained on the basis of well-documented characteristics of the digestive systems of herbivorous insects. In challenging the currently popular notion that tannins are digestibility-reducing substances, we do not challenge the general utility of either the apparency theory or resource availability theory of plant defense. In debating the merits of these two analyses of plant-herbivore interactions, however, the demise of tannins as all-purpose, dose-dependent, digestibility-reducing defensive substances must be taken into account.     

Aggregation pheromone system of adult gregarious desert locust schistocerca gregaria (forskal)

Six electrophysiologically active aromatic compounds, viz., anisole, benzaldehyde, veratrole, guaiacol, phenylacetonitrile, and phenol, were identified in the volatiles of older-adult male desert locust. Young adults and females of all age groups produced none or only trace quantities of these compounds. Comparison of the aggregation responses of young and older adults to the crude, older-adult, volatile extract and different synthetic blends of the six compounds showed that the aggregation pheromone system of the adult gregarious locust consists of phenylacetonitrile, guaiacol, phenol, and benzaldehyde. Like the crude volatile extract of older males, neither the synthetic blend of the six compounds nor the adult pheromone blend evoked any significant aggregation responses from nymphs. These results confirm our previous report of sexual differentiation in the production of adult aggregation pheromone in the desert locust and of the evidence of two distinct aggregation pheromone systems in the two stages of the insect.     

Molecular mechanics modelling of interfacial energy and flexibility on cellulose

Molecular mechanics modelling is used to calculate the energies of interaction, hence the molecular level energy of adhesion at the interface with crystalline cellulose I of three different photopolymerizable primers and of a polyester varnish at the interface with the primer/cellulose assembly. The energy of interactions for just one of the primers with the statistically most common conformation of amorphous cellulose has also been obtained for comparison. Experimental results of adhesion by a standard peel test and by thermomechanical analysis, in which the effect of viscoelastic energy dissipation by crack tip propagation has been respectively minimized or is not present, hence in which the energy of interfacial interaction is nothing else but the work of adhesion, correlated well with the energies of interaction calculated by molecular mechanics. An equation correlating the energy of interaction at each finish/cellulose interface with the deflection derived by thermomechanical analysis, and with the number of internal bond rotational degrees of freedom as well as the degree of networking of the finish, has been derived and is presented. A relationship between the intrinsic fracture energy Go and the molecular mechanics-derived energy of interaction at the interface equating this to the square of the work of adhesion is obtained and is presented.     

接触式机械密封界面泄漏机理研究的关键科学问题

密封界面的泄漏机理是机械密封研究与应用的焦点问题之一,涉及泄漏通道表征、粗糙表面的接触力学模型、界面微观形貌变化以及介质流体在泄漏通道中的流动阻力等问题。回顾了近几十年国内外接触式机械密封泄漏通道模型的研究,深入分析了G-W模型、M-B模型和Persson模型3种粗糙表面接触力学模型的贡献和存在的问题,提出了一种基于逾渗理论的泄漏通道新模型;探讨了密封界面的分形参数、泄漏通道的流动阻力以及密封界面的有限尺寸效应对泄漏特性的影响,指出孔隙连通贯穿界面和流体流经贯穿通道的流动阻力小是密封界面产生泄漏的成因,以及泄漏通道的形成和泄漏通道内的流体流动特性是泄漏机理研究的主要方向。     

Sr改性Cu催化剂的果糖加氢制备甘露醇性能

使用共沉淀法制备负载Cu催化剂。通过添加碱土金属Sr，对Cu催化剂进行了改性，以提高Cu催化剂在果糖加氢制备甘露醇过程中的活性和选择性。采用ICP-MS、TEM、XRD、H₂-TPR、XPS和CO₂-TPD等对所制备的催化剂进行了系统表征。结果表明：Sr的添加能增大催化剂的比表面积，促进活性组分Cu的分散，从而提高了催化剂的活性，并且增加了催化剂的碱性，使果糖优先形成β-呋喃糖中间体，从而提高了甘露醇的选择性。在果糖浓度为1.1 mol·L^-1、催化剂用量为反应物质量的6%、反应温度为373 K、反应氢压为4.0 MPa、Cu/Sr原子比为7∶1的反应条件下，果糖转化率为99%，甘露醇的选择性为79%。催化剂循环使用了20次，其催化稳定性基本保持不变。     

Distribution of birch (Betula SPP.), willow (Salix SPP.), and poplar (Populus SPP.) secondary metabolites and their potential role as chemical defense against herbivores

Isoprenoids and phenolics, major metabolites of important browse species, are reviewed in regard to concentrations, distribution within tissues, and between species. Seasonal variation of specific substances and changes with age of the plant are also considered. The distribution of substances may affect food selection and feeding behavior of animals. Wild mammalian herbivores tend to avoid plant parts rich in these substances, in spite of high nutritional content of the plant tissue. Possible mechanisms for defense by plants against depredation by mammalian herbivores are discussed within the framework of the plants' biochemistry.     

Biogenic and bio‐structured inorganic materials in heterogeneous catalysis: a brief overview

This mini‐review highlights some research results related to the production and application of biogenic and biomorphic materials in catalysis. Such approaches are of interest for the preparation of materials of unusual and well defined morphology, as well as the recovery of valuable resources from waste streams. Areas covered are the application of biogenic iron oxide occurring as a natural waste in the form of iron ochre which can cause issues in water management, the application of biogenic manganese oxide materials formed from manganese rich media (and therefore possibly playing a role in water remediation), the application of bacteria for the preparation of metal nanoparticles of potential relevance to precious metal recovery from waste streams and the application of natural biological materials as templates for biomorphic inorganic materials of controlled and unusual uniform morphology. © 2015 Society of Chemical Industry     

Selecting the optimal linear alcohol ethoxylate for enhanced oily soil removal

Use of nonionic surfactants in detergent products has become increasingly popular because of their tolerance to hardness ions and their effect on lowering the critical micelle concentration of anionics. Their performance as detergents, however, is very sensitive to changes in temperature and electrolyte concentration, which need to be carefully controlled in order to ensure that phase inversion conditions prevail. For a fixed temperature in an application, the only variables available for optimizing the performance of a system containing nonionics are: the type of nonionic, and the concentrations of electrolytes and anionics. Based on the mutual interactions of these ingredients in mixed systems, we have devised some guidelines for selection of the optimal ethylene oxide (FO) chain length in lauryl alcohol ethoxylate type of nonionics for a range of electrolytes and anionic surfactant concentrations. For any given concentration of electrolytes (sodium carbonate and sodium tripolyphosphate), anionic (sodium linear alkyl benzene sulfonate) and nonionic, the detergency of synthetic sebum from blended polyester/cotton fabrics shows a maximum as a function of average FO moles in the nonionic. Oil/water interfacial tension shows an expected reverse trend. The optimal EO moles (for maximal detergency) show a monotonically increasing trend when plotted as a function of the ratio of nonionic to anionic concentration for a fixed level of electrolyte. The optimal EO moles also increase with increasing level of electrolytes in the system. However, the effect of nonionic/anionic ratio is much stronger than the effect of electrolytes on the optimal EO moles.