单筒双井预斜扩眼技术研究及在渤海油田的应用

传统的单筒双井技术为两口井共用一个一开井眼,受工具、工艺和技术的限制,表层中完井深较浅,且存在一开井段双井轨迹无法分离、扩眼易出现新井眼、固井质量差等问题,严重限制了单筒双井作业的顺利实施。为解决该问题,在分析现有技术优缺点的基础上,梳理其工艺难点及技术局限,从表层预斜、扩眼、套管下入、注水泥固井工艺、两井眼分离等关键环节进行改进优化,最终得出了一套切实可行、安全高效的单筒双井预斜扩眼技术。     

Non-classical crystal growth of inorganic and organic materials

Abstract

Investigation of the early stage morphologies of some organic and inorganic systems has established that their crystal growth does not always follow the classical route established 120 years ago. The classical theory assumes that a highly symmetric crystal develops from the nucleation and repeated attachment of atoms, molecules or ions to a single nucleus. In instances where surfactants or polymers are introduced, the crystal growth is often found, however, to follow a ‘reversed crystal growth’ route. This non-classical growth route is initiated by organic molecules adsorbed onto the surface of the nanocrystallites in the early stages of growth. In the reversed route, these nanocrystallites form large disordered aggregates followed by surface crystallisation to create a thin, highly crystalline, dense shell and, finally, an extension of the crystallisation from the surface to the core. Although systems following a non-classical crystal growth route have been known for many years, their formation mechanisms have a much shorter history. Discovery of the reversed crystal growth route in several hollow, core–shell and twin crystal type morphologies not only assists in the designing of materials for industrial applications but also helps to understand the interactions between organic and inorganic components. This review highlights recent research relating to organic and inorganic systems whose growth follows the reversed crystal growth route.     

Grid deformation strategies for CFD analysis of screw compressors

Customized grid generation of twin screw machines for CFD analysis is widely used by the refrigeration and air-conditioning industry today, but is currently not suitable for topologies such as those of single screw, variable pitch or tri screw rotors. This paper investigates a technique called key-frame re-meshing that supplies pre-generated unstructured grids to the CFD solver at different time steps. To evaluate its accuracy, the results of an isentropic compression-expansion process in a reciprocating piston cylinder arrangement have been compared. Three strategies of grid deformation; diffusion equation mesh smoothing, user defined nodal displacement and key-frame remeshing have been assessed. There are many limitations to key-frame re-meshing. It requires time consuming pre-processing, has limited applicability to complex meshes and leads to inaccuracies in conservation of calculated variables. It was concluded that customized tools for generation of CFD grids are required for complex screw machines.     

基于流动模式的汽车双筒式磁流变减振器设计与试验研究

提出一种基于流动模式的汽车单出杆、双筒式磁流变减振器的结构与工作原理,该减振器采用已有汽车悬架双筒式普通液压减振器的设计标准制造,对现有双筒式减振器具有很强工艺继承性。根据Bingham流体模型建立双筒式磁流变减振器阻尼力数学模型,并提出该减振器的磁路设计方法;针对磁路的非轴对称特性,建立磁路三维有限元仿真模型,结合北京现代某款汽车前悬架减振器的技术要求和磁流变液流变特性,进行三维静态磁场分析,确定活塞磁路的主要参数。制作汽车双筒式磁流变减振器,并对此进行台架特性试验;通过试验与理论计算对比,结果表明理论计算数据与试验数据较吻合,所提出的双筒式磁流变减振器设计方法是可行的,对汽车双筒式磁流变减振器的设计使用具有指导意义。     

OptiDry Twin冲击式干燥

本文以OptiDry Twin为主,介绍了一种新型的纸页干燥技术——冲击式干燥。这种技术对干燥部的初期干燥尤其有效,其突出的干燥能力和优化的牵引力控制有助于改善纸机运行性能、提高产品质量和车速,同时具有良好的经济性。     

30t～120t单电极双塔式结构三工位可交替熔炼的恒熔速保护气氛电渣炉

本电渣炉是双塔式结构三工位可交替熔炼的恒熔速保护气氛电渣炉,其特征是配有两套塔式结构的可转动炉头部分,可分别在三个工位进行交替重熔冶炼。其特征在于,结合上述特征,再通过塔式机架、可转动和升降的炉头、电极调整装置、升降烟罩气氛保护、高精度称重系统、恒熔速自动控制系统技术的采用,最终满足大吨位高质量电渣锭的生产需求。优点：解决了现有技术所存在的大吨位高质量电极生产的困难,同时,还提高了电渣炉的有效利用率和生产的灵活性,提高生产效率。     

Droplet breakup and coalescence in a twin-screw extrusion processing of starch based matrix

Formation of oil droplets during twin screw extrusion processing of maize starch was investigated by analyzing the droplet breakup and coalescence mechanisms separately. For this purpose, the flow was characterized by computational fluid dynamics (CFD) using material data derived from online rheological measurements. The simulated results on local flow conditions were coupled to experimental data on the dispersed phase morphology, which was analyzed by confocal laser scanning microscopy (CLSM). This was used to elucidate the influence of process characteristics relevant for droplet breakup and coalescence. The results showed that increasing screw speed does not necessarily result in smaller droplet sizes. This could be related to the contradictory effects: increasing screw speed improves droplet breakup but also increases the rate of coalescence. Smaller droplet sizes were obtained at higher blend viscosities, which could be achieved either by increasing the feed rate or by using screw configuration that applies less mechanical stress. The results suggest that an increase in blend viscosity reduced the rate of coalescence. Moreover, increasing oil content led to an increased rate of coalescence, and therefore to remarkably bigger droplets. Selection of process parameters (e.g. screw configuration, feed rate, screw speed) based on the findings of this study allowed enhancing the dispersive mixing efficiency of triglyceride droplets during extrusion processing of maize starch.     

Research on the performance of water-injection twin screw compressor

Due to the development of the automotive fuel cell systems, the study on water-injection twin screw compressor has been aroused again. Twin screw compressors with water injection can be used to supply the clean compressed air for the Proton Exchange Membrane (PEM) fuel cell systems. In this research, a thermodynamic model of the working process of water-injection twin screw compressor was established based on the equations of conservation of mass and energy. The effects of internal leakage and air–water heat transfer were taken into account simultaneously in the present mathematical model. The experiments of the performance of a prototype compressor operating under various conditions were conducted to verify the model. The results show that the predictions of the model are in reasonable agreement with the experimental data.