功图在抽油机自适应平衡调整中的应用

根据油田数字化建设的需要,抽油机生产商设计开发了系列数字化抽油机。平衡调节装置是数字化抽油机的重要部件。本文提出了一种直接根据实测示功图来对抽油机平衡配重位置进行调整的方法,以此实现抽油机的平衡节能。由已知油井实测示功图,假定平衡配重力矩,推导悬点载荷与电动机输出功率的关系式,预测数字化抽油机驴头在基于实测示功图的载荷作用下的电机输出功率曲线,得出平衡半径的调整量,分析、判断和计算数字化抽油机平衡配重的调整方向与调整量,准确调节平衡。     

刮板输送机驱动电机功率平衡分析

刮板输送机是采掘工作面常用的运输设备,重型刮板输送机常用多台驱动电动机提供动能。驱动电动机输出功率不平衡时会导致输出转矩不均衡,从而造成电动机故障,给刮板输送机正常运行带来不利影响,因此,文中在对刮板输送机载荷特性分析基础之上,对刮板输送机驱动电动机功率协调进行分析,采用主从控制方式中的转矩随动方式,可以较好的解决刮板输送机功率平衡问题,提高刮板输送机服役时间,降低设备磨耗,提高矿井生产效率。     

关于2PF1010破碎机转子平衡的一点体会

我公司于１９９３年安装１台上海重型机器厂生产的２PF１０１０双转子式破碎机，使用至２００２年９月份时，发现双转子出现振动，经静平衡配重处理，振动未见好转。后经打开转子两侧密封盖发现，转子空腔内积满细粉，经清理后振动加剧，遂拆除送协作单位作平衡试验，安装后振动消除，但随之轴承（皮带轮侧）温度逐渐升高，清洗换油后，使用１０d左右，轴承温度再次升高（达１０５℃），并伴有异音，后经清洗发现，轴承外圈已呈波浪形曲面，不得不拆除更换。２次更换轴承后，又重复出现上述情况，于是我们怀疑配重可能偏向一端，配重时转速…     

煤矿刮板输送机调速系统关键技术探析

为使刮板输送机实现智能调速,基于刮板输送机应用现状,介绍了刮板输送机调速系统常用的变频驱动控制技术,叙述了控制原理与实现策略;分析了多电机驱动下的重型刮板输送机常用的多电机功率平衡技术的原理与实现方案;此外为使刮板输送机更好地与采煤机相配合,研究了刮板输送机与采煤机相互配合的协同调速控制技术,刮板输送机关键调速技术的应...     

南磷硫酸装置热料埋刮板输送机的改造

本文介绍了南化集团公司磷肥厂２０万吨／年硫酸装置排渣埋刮板输送机的技术改造情况。其中对输送机的头部、托轮段、尾部和张紧装置等进行了技术改造,取得了较好的效果。文中对重锤张紧装置常规的重锤配重计算方法,提出了增加重锤备用系数的建议,可供参考。     

导丝辊不平衡量的矢量特性分析与应用

通过对不平衡量矢量特性的分析,指导长丝导丝辊的动平衡配重操作,总结出一种便捷的操作方法,减少配重误差,提高动平衡的工作效率。     

抽油机井杆柱变化后平衡配重预测及应对策略

采用扭矩法预判抽油机杆柱组合变化后的平衡状况，给出杆柱变化后需要的平衡重最大扭矩，与原机型平衡配重最大扭矩进行比较，若已无法满足措施后平衡需要，可提前采取措施，在允许范围内，优化杆柱组合。若优化杆柱组合仍达不到平衡需求，则考虑更换大机型，按照满足平衡需求的平衡重最大扭矩选择抽油机机型，这样既缩短了不平衡井治理时间，又能保证治理后抽油机达到平衡，使抽油机安全高效运行，拓展节能降耗空间。     

抽油机游梁平衡自动调节系统的设计

针对抽油机由于不平衡而造成的耗能问题,设计了一个抽油机游梁平衡自动调节系统。系统采用功率法检测抽油机的平衡度,当抽油机处于失衡状态时,系统通过步进电机驱动游梁上的平衡配重小车改变它与游梁支点的相对位置,进而调整曲柄轴上的扭矩,使抽油机重新在新平衡状态下运行。     

14型抽油机后配重节能改造应用

目前中原油田普遍使用的抽油机是CYJY14—4．8—73HF型抽油机，由于泵挂深、结蜡等原因导致不平衡。本文找出了目前抽油机在现场应用过程中存在的问题，实施了增加悬挂式游粱后配重，现场应用节能效果明显。     

搅拌薄膜蒸发器在离子膜烧碱蒸浓中的应用

搅拌薄膜蒸发器腐蚀的原因主要是氯酸盐腐蚀，湍流腐蚀及刮板与筒壁的摩擦损失和温度控制较高所致，造成碱液污染，转子刮板转速越高，湍流腐蚀越严重，采用正确的转速、下轴承减少转子不平衡影响，改为外置滚动球轴承，降低碱液中ＣｌＯ＾３－含量，控制预热器温度≤８０℃可有效防止蒸发器腐蚀和碱污染。     

LNG储罐气升顶工艺分析

在国内外储罐施工中,气升顶方法由于其施工速度快且成本低等特点而被广泛采用。但对于大型储罐拱顶,由于其质量大,提升高度高,影响因素多,施工安全风险大等特点,气升顶成为施工中的技术难点之一。平衡、供气及密封系统作为气升顶核心环节,是拱顶平稳上升的基本保障。结合1.6×105 m3LNG储罐项目,论述了气升顶的施工过程及原理,并对平衡校正系统、平衡配重系统及供气系统进行了计算和分析,总结了气升顶过程的关键技术要点。     

反应精馏法实验制取醋酸乙酯

传统直接酯化法制取乙酸乙酯，由于反应平衡的存在，收率较低。采用反应精馏酯化法，以浓硫酸为催化剂，控制回流比为3，进料质量比为1：1，间歇操作，反应时间为2h可以实现80％以上的转化率和收率。     

The influence of compositional variations in compounded thermoplastic olefins (TPOs) on the physical and mechanical attributes of injection molded plaques

Compounded TPO continues to make inroads into automotive applications because of the excellent price/performance balance reached in this thermoplastic substrate. Thermoplastic olefin (TPO), a blend of elastomer and poly(olefin), achieves its balance of properties through the choice of compounded ingredients. The injection molding conditions through which the desired plastic part is achieved are known to also influence the attained properties of the blend. In this paper, the influence of poly(olefin), namely poly(propylene) homopolymer, and elastomer utilized in the compounded blend, in conjunction with molding properties used to produce plaques, are studied as they relate to the physical and mechanical properties achieved. Paint adhesion and friction induced paint damage resistance of coated plaques are shown to be directly related to poly(propylene) molecular weight and elastomer crystallinity. Molding conditions, mainly influenced through the shear induced injection molding process, are also correlated.     

关于双平面平衡矢量计算法和影响系数法一致性的论证

探讨了双平面平衡的矢量计算法和影响系数法。论证了矢量计算法和影响系数法的一致性。给出应用矢量计算法确定校重大小和位置角的例子,其结果与基于影响系数法编程的动平衡测试十分接近。基于影响系数法编程的动平衡测试具有快速、简便的特点,采用该法获得的影响系数可用于同类转子中,转子平衡校正时,可极大地减少启停运行次数,获得较好的平衡效果。     

Bioinspired fibrillar adhesives: a review of analytical models and experimental evidence for adhesion enhancement by surface patterns

Fibrillar structures are found on the attachment pads of insects and small reptiles. These structures enable exquisite conformation to rough surfaces, increase the number of van der Waals interactions between the structure and the target surface, and thus enhance adhesion. Biomimetic adhesives replicate this effect by patterning polymer films with micron- or sub-micron-sized protrusions. Numerical contact-mechanics models as well as experimental adhesion measurements have been reported for a variety of protrusion shapes including flat, rounded, mushroom and spatula geometries. Although superior adhesion has been reported for the mushroom and spatula tip geometries, straight, flat-tipped pillars offer the potential for much simpler mass production such as by injection moulding and are thus the focus of this review. Existing models for straight, flat-tipped pillar arrays do not fully agree with reported experimental results. Analytical models are generally limited to elastic materials, and inherently assume that neighbouring pillars behave independently. For elastic pillars in close proximity, however, pillars do in fact interact mechanically, affecting adhesion. Moreover, visco- and hyper-elastic materials are often used in practice, yet dissipative effects receive little attention in analytical models. We find that no study has conclusively investigated the limit of adhesive strength achievable by fibrillar adhesives. It also remains unclear what happens to the adhesive strength as the areal density of contacting regions approaches 100%.     

The balance between durability,reliability, and affordability in structural composites manufacturing

Fiber reinforced structural composites will play a key role in the development of the next generation of transportation vehicles (passenger cars, vans, light trucks, and heavy trucks) because of their high strength‐to‐weight and stiffness‐to‐weight ratio compared with metals. An integrated assessment of the durability, reliability, and affordability of these materials is critical to facilitate the inclusion of these materials into new designs. The result of this assessment should provide information to find the balance between the three performance measures. This paper describes a method to develop this assessment in the fabrication of sheet molding compound (SMC) parts, and discusses the concept of Preform Insert Assembly (PIA) for improved affordability in the manufacturing of composite parts. POLYM. COMPOS., 28:233–240, 2007. © 2007 Society of Plastics Engineers     

Realistic contact for soot with an oxidation catalyst for laboratory studies

Laboratory temperature programmed oxidation (TPO) is popular for diesel soot oxidation catalyst screening. The method of depositing soot on the catalyst can be critical for the measured catalyst performance. Different methods for bringing the soot in physical contact with the catalyst were evaluated in order to determine which methods give a realistic contact. Suitable methods are filtration from a (artificial) soot aerosol, shaking in a sample bottle, mixing with a spatula, and dipping in a soot dispersion. For these preparation methods Printex U synthetic soot is a suitable model compound.     

Molecular design of novel pH/temperature-sensitive hydrogels

A series of poly(β-amino ester)-poly(?-caprolactone)-poly(ethylene glycol)-poly(?-caprolactone)-poly(β-amino ester) pentablock copolymers (PAE-PCL-PEG-PCL-PAE) were designed and prepared to examine factors affecting sol-gel phase transition behavior. First, the composition of a series of PCL-PEG-PCL copolymers was controlled by changing the feed ratios of PCL/PEG and the molecular weight of PEG. Second, the composition of pentablock copolymers was varied using different PCL-PEG-PCL copolymers and several feed ratios of PAE monomers. The physicochemical properties of triblock and pentablock copolymers were characterized by ¹H NMR and gel permeation spectroscopy. The PAE-PCL-PEG-PCL-PAE copolymers in aqueous solution (20-30 wt%) underwent sol-gel transitions with changes in both pH change and temperature. With increasing molecular weight of PAE, the sol-gel transition zone became narrower because the hydrophobic character of the copolymers decreased. Also, with increases in PCL/PEG ratio and PEG molecular weight, changes in the hydrophobic/hydrophilic balance within copolymers resulted in alterations in sol-gel phase transitions.     

Flow balancing in die design of wood flour/HDPE composite extrusion profiles with consideration of rheological effect

This article presents an experimental study on the flow balance of an extrusion die for various wood flour (WF)/high‐density polyethylene (HDPE) compositions. Flow balancing, in the design of a thermoplastic extrusion die, is dependent on the material rheological properties so that a change in the material, in some cases, may result in a total redesign of the die. To investigate the importance of this particular effect, the flow balance of an extrusion die, with a U‐shaped profile having uneven wall thicknesses, was undertaken. The main feature of the die was an adjustable restrictor implemented for fine balancing similar to that employed in the slit dies. The rheological influence of wood plastic composites (WPCs) on the flow balance of the die via loading various WF contents, 40, 60, and 70% by weight, was experimentally investigated; flow balancing was performed via varying the height of the restrictor bar. Interestingly, the results showed that, for a high WF content (above 60%), the issue of flow balancing for an uneven wall thickness profile is much less complicated because of the plug flow behavior of the composite. POLYM. ENG. SCI., 2010. © 2009 Society of Plastics Engineers     

Dietary fat and body weight control

The global obesity epidemic has heightened the debate about dietary factors contributing to weight gain. Media stories have promulgated the notion that obesity has increased despite reductions in dietary fat intake. Some have even speculated that lower dietary fat levels may be driving the rapid rise in weight gain within the population. A close examination of the science reveals a different picture and supports the hypothesis that dietary fat, within the context of the total dietary composition consumed by many populations, promotes obesity. Hence, dietary fat control is still an important strategy as part of an overall approach to body weight management in our modern environment. Dietary fat increases the energy density of foods. Abundant evidence from preclinical and clinical studies indicates that fat promotes excess energy intake and positive energy balance. Dietary fat does not promote its own oxidation in the body and is stored efficiently, promoting a positive fat balance. Thus, both the behavioral and metabolic responses to dietary fat increase the probability of positive energy balance and body fat gain. Restoring fat balance when consuming diets rich in fat requires increasing the size of the body fat mass, increasing physical activity, or reducing dietary fat intake. Numerous epidemiologic, preclinical, and controlled clinical studies have shown that body fat is positively associated with dietary fat intake and that dietary fat manipulation leads to appropriate changes in body fat mass. Finally, data from the National Weight Control Registry, a database of >3000 individuals who have successfully maintained a substantial weight loss, indicate that moderating dietary fat intake is a key strategy for long-term management of body weight.