大型挤压造粒机组现场安装、试车问题分析

针对某聚丙烯装置建设中大型挤压造粒机组的安装、调试和试车出现的问题,分析了现场安装、试车过程中出现的设计、施工和设备的质量问题,提出了产生这些问题的原因和解决方案,供今后此类成套机组设计、制造及现场安装作参考。     

氯乙烯球罐设计、制造和安装问题探讨

叙述了5 000 m3氯乙烯球罐在设计、制造和安装过程中出现的问题;论述了关于球罐分析设计、球壳板尺寸设计变更、焊缝间隙超标等问题的原因和解决办法;针对球壳板制造和组装过程中出现的纵、环缝间隙问题,提出了调整安装形式的改进措施。     

石油化工厂中泵配管设计与现场泵管道安装中的问题

泵配管设计以及管道现场安装涉及多项内容，可能会因为管材质量或者人员操作等各项因素影响而出现失误问题，所以需要对设计和安装工作展开全面把控。通过对石油化工厂中泵配管设计相关内容的详细探讨，对现场泵管道安装注意事项展开深度分析，通过对设计要点和安装要点的研究，为相关泵配管设计和管道安装工作开展提供一些参考。     

化工工艺中的设备安装设计问题与对策的探索

日前在国内化工工艺中的设备安装没有形成一个独立的设计专业,通常被概括到化工工艺设计之中,设备安装也没有引起设计人员足够的重视,从而忽略到其中的一些问题。实际上在此环节中涵盖了很多并且复杂的设计内容,是化工工艺设计不可忽视的一部分。化工产品和一般的生产类产品有很大的区别,因为产品拥有有毒、有害和容易爆炸的特质,所以在安装的时候,要特别注意设备安装哪个在前哪个在后。这样才可以避免一些不必要的失误。文章会通过化工工艺中设备安装目前的实际情况,分析化工工艺中设备安装的重要性,并且就安装中会出现的问题来提出相应的解决方案。     

浅谈压力容器设计制造安装常见问题及解决方法

压力容器是人们在日常的生产和生活中使用十分广泛的一种设备,是人们生活中必不可少的工具。所以在设计过程当中,一定要严格按照标准所规定的要求进行设计,并且要特别重视制造过程,防止问题的出现。对于压力容器在设计过程、制造过程、安装过程中存在的问题,本文将进行探讨,进一步对压力容器在设计制造安装过程中的问题进行解决。     

石油化工工艺管道安装工程施工管理中的问题分析

在石化工艺管道的实际安装过程中,由于不同的地理条件,不同的材料和不同的安装位置,常会发生不同的安装问题。这些问题对项目的总体质量有直接而严重的影响。本文简要介绍了支配石化管道设计的特定过程,安装和施工过程中出现的各种问题,并安装了管道以促进现代石油的发展,促进化学工艺技术的进一步发展,为各种工艺问题提供了切实有效的解决方案。     

压力管道安装中材料存在问题及预防措施

压力管道安装现场材料种类多、牌号多、规格多、组成件多,在材料使用环节极易出现问题。材料的使用符合标准和设计的要求,是保证压力管道质量安全的重要环节之一。本文对近年来压力管道安装监检过程中发现材料存在的问题进行列举分析,并提出预防措施,防止不合格的材料投用到管道安装中,提高压力管道安装质量。     

化工装置建设中静设备安装施工的若干问题

从现场设计代表的角度,介绍化工静设备在安装、建造施工中出现的若干问题及解决方法,涉及立式容器安装及储罐保温和罐底板防腐施工,储罐盘梯平台制作等。     

电泳循环管路设计中的注意事项

阴极电泳在现在高档家电涂装和汽车涂装中是比较常见的工艺。电泳循环管路的合理设计和安装对于电泳漆循环相当重要，如有不当，将会带来电泳漆的沉淀和管路堵塞，给维护和管路带来不必要的麻烦。现结合近几年的电泳设计和安装，对循环管路系统中出现的一些问题进行分析。     

浙江壳牌化工石油有限公司润滑油2X＋项目完工总结

本文是针对工程安装调试过程中出现的问题进行分析，并提出解决方案，便于以后的项目有借鉴，以及项目设计时吸取经验，避免错误。     

苯酚在浊点萃取中凝聚层相的增溶规律

采用分光光度法测定了苯酚在非离子表面活性剂单相胶束溶液中和在非离子表面活性剂两相浊点萃取时凝聚层相中的增溶结果.实验表明：溶质在凝聚层相的增溶与表面活性剂形成胶束的结构有关.当凝聚层相的表面活性剂形成正相胶束时,溶质在凝聚层相的增溶规律和在表面活性剂胶束溶液中的增溶规律一致;当凝聚层相的表面活性剂形成反相胶束时,溶质在凝聚层相和在溶液相的浓度关系可理解为在这两种溶剂之间的分配随着凝聚层相的含水率逐渐降低趋近于一定值,溶质的分配系数也趋近于一定值.     

宝钢转炉钢包用耐火材料的现状及发展趋势

综述了宝钢转炉钢包用耐火材料的变化过程及使用现状 ,重点介绍了近年来宝钢在钢包耐火材料使用上的一些技术进步 ,提出了存在的问题及对策 ,展望了今后宝钢转炉钢包的发展方向。     

Oral Administration of Dihomo-γ-Linolenic Acid Prevents Development of Atopic Dermatitis in NC/Nga Mice

Disorders of the metabolism of essential fatty acids (EFAs) are related to atopic dermatitis (AD). Concentrations of dihomo-γ-linolenic acid (DGLA), an EFA, in the serum of AD patients are lower than those in healthy volunteers. Recently we developed a fermented DGLA oil, and examined whether oral administration of DGLA prevents development of dermatitis in NC/Nga mice, which spontaneously develop human AD-like skin lesions. NC/Nga mice were fed a diet either containing or not containing DGLA for 8 weeks under in air-uncontrolled conventional circumstances. Clinical skin severity scores were significantly lower in mice fed DGLA than in mice not fed it. Scratching behavior and plasma total IgE levels were also reduced in the DGLA group, in association with histological improvement. DGLA suppressed clinical severity of skin lesions dose-dependently, with an increase in DGLA contents in phospholipids of skin, spleen, and plasma. Discontinuation of DGLA administration resulted in the onset of dermatitis and a decrease in DGLA contents in skin, spleen, and plasma. These findings indicate that oral administration of DGLA effectively prevents the development of AD in NC/Nga mice, and that DGLA in phospholipids is a compound of key importance in the development and prevention of dermatitis.     

Effects of Tyrosine and Tryptophan Supplements on the Vital Indicators in Mice Differently Prone to Diet-Induced Obesity

We studied the effects of the addition of large neutral amino acids, such as tyrosine (Tyr) and tryptophan (Trp), in mice DBA/2J and tetrahybrid mice DBCB receiving a high-fat, high-carbohydrate diet (HFCD) for 65 days. The locomotor activity, anxiety, muscle tone, mass of internal organs, liver morphology, adipokines, cytokines, and biochemical indices of animals were assessed. The Tyr supplementation potentiated increased anxiety in EPM and contributed to a muscle tone increase, a decrease in the AST/ALT ratio, and an increase in protein anabolism in both mice strains. Tyr contributed to a decrease in liver fatty degeneration and ALT reduction only in DBCB that were sensitive to the development of obesity. The addition of Trp caused an increase in muscle tone and potentiated an increase in anxiety with age in animals of both genotypes. Trp had toxic effects on the livers of mice, which was manifested in increased fatty degeneration in DBCB, edema, and the appearance of micronuclei in DBA/2J. The main identified effects of Tyr on mice are considered in the light of its modulating effect on the dopamine neurotransmitter metabolism, while for the Trp supplement, effects were presumably associated with the synthesis of its toxic metabolites by representatives of the intestinal microflora.     

精-异丙甲草胺在大豆及土壤中的残留动态

为了评价精-异丙甲草胺在大豆上的残留动态及环境安全性,在天津、吉林两地同时进行了精-异丙甲草胺在大豆上的残留动态试验.结果表明,天津地区精-异丙甲草胺在大豆植株中的半衰期为19.1 d,在土壤中的半衰期为27.9 d;吉林地区精-异丙甲草胺在大豆植株中的半衰期为21.4 d,在土壤中的半衰期为34.1 d.收获的大豆籽粒中精-异丙甲草胺最终残留量均为未检出.     

Secondary Plant Products Causing Photosensitization in Grazing Herbivores: Their Structure,Activity and Regulation

Photosensitivity in animals is defined as a severe dermatitis that results from a heightened reactivity of skin cells and associated dermal tissues upon their exposure to sunlight, following ingestion or contact with UV reactive secondary plant products. Photosensitivity occurs in animal cells as a reaction that is mediated by a light absorbing molecule, specifically in this case a plant-produced metabolite that is heterocyclic or polyphenolic. In sensitive animals, this reaction is most severe in non-pigmented skin which has the least protection from UV or visible light exposure. Photosensitization in a biological system such as the epidermis is an oxidative or other chemical change in a molecule in response to light-induced excitation of endogenous or exogenously-delivered molecules within the tissue. Photo-oxidation can also occur in the plant itself, resulting in the generation of reactive oxygen species, free radical damage and eventual DNA degradation. Similar cellular changes occur in affected herbivores and are associated with an accumulation of photodynamic molecules in the affected dermal tissues or circulatory system of the herbivore. Recent advances in our ability to identify and detect secondary products at trace levels in the plant and surrounding environment, or in organisms that ingest plants, have provided additional evidence for the role of secondary metabolites in photosensitization of grazing herbivores. This review outlines the role of unique secondary products produced by higher plants in the animal photosensitization process, describes their chemistry and localization in the plant as well as impacts of the environment upon their production, discusses their direct and indirect effects on associated animal systems and presents several examples of well-characterized plant photosensitization in animal systems.     

Stress Distribution in Single Lap Joints with a Cracked Composite Adherend—Part II: Laminated Adherends

The effect of a crack in the overlap region of an adhesive single lap joint is studied on the shear stress distribution in adhesive layer. Each adherend is considered to be a laminated composite material with unidirectional fibers aligned in the direction of the applied load. Crack location is selected to be in the top adherend laminate, in the form of cut fibers and matrix bays. The crack can occur in any layer. The shear-lag model is used to derive the equilibrium equations which are then solved by means of eigenvector expansion. The effects of adhesive thickness, crack size, and location in the adherend, total number of layers in each adherends, volume fraction of fibers, and type of fibers are investigated on the shear distribution in the adhesive as well as load distribution in the intact fiber at the crack tip located in the top adherend. The effect of dissimilar laminated adherends is also investigated on the adhesive shear stress distribution. According to the results, in the presence of a crack, the peak shear stress in the adhesive layer and load concentration in the fibers are very susceptible to the adhesive thickness and number of layers in laminated adherends.     

DIMBOA Glucoside, a Wheat Chemical Defense, Affects Host Acceptance and Suitability of Sitobion avenae to the Cereal Aphid Parasitoid Aphidius rhopalosiphi

The influence of hydroxamic acids (Hx), plant secondary metabolites associated with aphid resistance in wheat, on the host acceptance and suitability of the aphid Sitobion avenae to the cereal aphid parasitoid Aphidius rhopalosiphi was evaluated. Aphids showed a reduction in mean relative growth rate and in body size in the wheat cultivar with higher Hx level. Reduction in aphid size was related to a decreased success in avoiding parasitoid oviposition. A minor increase in A. rhopalosiphi developmental time was observed in aphids feeding on the higher Hx cultivar. Experiments with different concentrations of DIMBOA glucoside, the main Hx in wheat, in artificial diets showed an increase in parasitoid developmental time at the highest concentration, with no change in other performance variables. The evidence is discussed in relation to the compatible utilization of host-plant resistance and biological control in integrated pest management.     

Influence of water immersion on the single-lap shear strength of aluminum joints bonded with aluminum-powder-filled epoxy adhesive

Durability of adhesively-bonded aluminum joints was investigated by measuring the joint strength using the single-lap shear test before and after exposure to distilled water and seawater. Fractured specimens were examined by photography and scanning electron microscopy to determine the failure modes. Addition of Al particles as much as 50 wt% did not cause any significant decrease in adhesive joint strength. Moreover, varying the Al filler content in the adhesive did not have a significant effect on adhesive behavior in either of the two environments studied. The unexposed adhesive joints failed almost completely in a cohesive (in the adhesive) failure mode. Some decrease in strength was observed in adhesive joints after exposure to both distilled water and seawater for 6 months. The decrease in adhesive joint strength was more significant for specimens immersed in distilled water than those immersed in seawater, probably due to the higher amount of moisture in the adhesive in distilled water than in seawater, as observed in a related moisture diffusion study. The joints exposed to distilled water or sea water failed in more than one mode. The interior part of the adhesive lap area failed in a cohesive mode while an adhesion failure mode was observed near the edges of the adhesive lap area, which is believed to be a result of moisture diffusion through the edges.     

50万t/a合成氨装置钴钼系变换催化剂接气情况分析

贵州开阳化工有限公司50万t/a合成氨装置变换系统的变换炉选用了K811型钴钼系催化剂。介绍了变换系统的工艺流程;分析了变换系统试车时变换炉催化剂接气过程中出现的问题;总结了变换系统接气时防止超温的方法。