Effect of casting process on the inner-wall band segregation of high-strength antisulfur pipes

Controlling inner-wall band segregation is one of the difficulties in the production of high-strength antisulfur pipes.Comparative tests were carried out on different casting processes(superheat,mold electromagnetic stirring,end electromagnetic stirring,casting speed and soft reduction)for the smelting of high-strength antisulfur pipes.The microstructures of continuous-casting billets and hot-rolled or tempered pipes were analyzed using a metallographic microscope and scanning electron microscope.The mechanism and evolution law regarding the inner-wall band segregation of high-strength antisulfur pipes were studied,and the influence of different casting processes was explored.

Design and Optimization of New Smoke Exhaust Pipe for Mining Trucks

In order to improve the maintenance efficiency,extend the use time,ensure that the exhaust emission meets the standard,forthe 830E truck heating bucket exhaust pipe design defects,the current single smoke exhaust system is transformed into atime period,convertible smoke exhaust system.After the transformation,it can not only realize the side row to prevent direct corrosion of the box bucket in summer,but also realize the heating of the box bucket at low temperature in winter to prevent snow and ice and frozen blocks from sticking to the box bucket and the materials transported.After the transformation can save a lot of manpower,material resources,financial resources,improve the service life.

Quantitative Prediction of Reduction in Large Pipe Setting Round Process

The control manner during the process to ensure the quality of pipe products mainly relies on the operator’s experience, so it is very necessary to study the setting round process and obtain its spring-back law. The setting round process is shaping an oval section pipe into circular section, so it is difficult to provide a quantificational analysis for its spring-back process because of the curvature inequality of pipe section neutral layer. However, the spring-back law of the circle-oval process can be easily predicted. The experimental method is firstly used to establish the equivalent effect between the setting round process and the circle-oval process. The setting round process can be converted into the circle-oval process. There are two difficulties in the theoretical analysis for the circle-oval process: elastic-plastic bending problem of curved beam; statically indeterminate problem. A quantitative analytic method for the circle-oval process is presented on the basis of combination of the spring-back law of plane curved beam with the element dividing idea in finite element method. The ovality after unloading versus the relative reduction is plotted with analytical and experimental results respectively, which shows a fair agreement. Finally, the method of quantitative prediction of reduction for large pipe setting round is given based on the equivalent effect and the analytical results. Five pipes, which are needed to be set round, are used to carry out experiment so as to verify this method. The results of verification experiment indicates that, in the experimental range, the residual ovality are all under 0.35% after the once only setting round with the theoretical prediction reductions. It is much less than the 1% requirement of pipe standard. Applying the established theoretical analysis is able to correct the pipe ovality with sufficient accuracy, which provides theoretical direction to plant use.

Experimental and Simulation Studies on Cold Welding Sealing Process of Heat Pipes

Sealing quality strongly affects heat pipe performance, but few studies focus on the process of heat pipe sealing. Cold welding sealing technology based on a stamping process is applied for heat pipe sealing. The bonding mechanism of the cold welding sealing process （CWSP） is investigated and compared with the experimental results obtained from the bonding interface analysis. An orthogonal experiment is conducted to observe the effects of various parameters, including the sealing gap, sealing length, sealing diameter, and sealing velocity on bonding strength. A method with the utilization of saturated vapor pressure inside a copper tube is proposed to evaluate bonding strength. A corresponding finite element model is developed to investigate the effects of sealing gap and sealing velocity on plastic deformation during the cold welding process. Effects of various parameters on the bonding strength are determined and it is found that the sealing gap is the most critical factor and that the sealing velocity contributes the least effect. The best parameter combination （AIB3CID3, with a 0.5 mm sealing gap, 6 mm sealing length, 3.8 mm sealing diameter, and 50 mm/s sealing velocity） is derived within the experimental parameters. Plastic deformation results derived from the finite element model are consistent with those from the experiment. The instruction for the CWSP of heat pipes and the design of sealing dies of heat pipes are provided.

ANALYTICAL SOLUTION OF FILLING AND EXHAUSTING PROCESS IN PNEUMATIC SYSTEM

The filling and exhausting processes in a pneumatic system are involved with many factors, and numerical solutions of many partial differential equations are always adapted in the study of those processes, which have been proved to be troublesome and less intuitive. Analytical solutions based on loss-less tube model and average friction tube model are found respectively by using fluid net theory, and they fit the experimental results well. The research work shows that： Fluid net theory can be used to solve the analytical solution of filling and exhausting processes of pneumatic system, and the result of loss-less tube model is close to that of average friction model, so loss-less tube model is recommended since it is simpler, and the difference between filling time and exhausting time is determined by initial and final pressures, the volume of container and the section area of tube, and has nothing to do with the length of the tube.

Design and Experiment for Exhaust Pipes of Pressure Wave Supercharged Diesel Engine

NOx and soot emissions from diesel engines can be greatly reduced by pressure wave supercharging(PWS).The diesel engine matched with PWS needs redesigning its exhaust pipes.Except for meeting the installation requirements,the exhaust gas must be stable in pressure before rushing into PWS.In this paper the lateral and center ported divergent exhaust pipes are designed,modeled geometrically and analyzed structurally based on a 3-D design software-CATIA to determine the structure of two exhaust pipes having the required inner volume.Then flow analysis for two exhaust pipes is done using a flow analysis software-ANASYS.Moreover,the optimal exhaust pipes are determined comprehensively and cast for engine test.Engine test results show that PWS is superior to turbocharging at low engine speeds and inferior to turbocharging in power and emissions at medium-to-high engine speeds.The performance of PWS engine under high speed operating conditions can be improved by contriving larger surge volume intake and exhaust pipes.

The Studies of the Welding Processes and Procedures on the West-East Pipeline Project

The West East pipeline project attracted the attention from all over the world for its long distance, huge diameter, complex geographic conditions, and diversified welding techniques being applied.In this paper the detail welding process and procedures used in the project are discussed and the distinguished achievements on welding techniques of China pipeline construction are described.

强涌潮区管袋围堰施工安全风险仿真研究

强涌潮区的水域环境复杂多变,这极大增加了管袋围堰施工安全管理的难度。为确定强涌潮区管袋围堰施工从清基到维护阶段的安全管控重点,首先利用系统理论过程分析法(STPA)对施工安全风险因素进行定性分析,从人员、物资、管理、技术、环境5个维度构建了强涌潮区管袋围堰施工安全风险指标体系;然后建立系统动力学(SD)演化模型,并运用网络层次分析法(ANP)确定各指标权重;最后结合工程实例进行模拟仿真。结果表明:随着工程推进以及对安全投入的逐步增加,管袋围堰施工安全风险水平呈现出先大幅上升,后逐步下降,最终趋于平缓的趋势;人员、物资是清基和吹填期影响施工安全的主要因素,而在排水和维护期,环境、管理是主要影响因素;人员、管理和环境这三因素对安全投入变化更为敏感。建议在施工过程中重视不同阶段之间的管控重点差异,及时转换管理策略并采取针对性措施以有效降低施工安全风险。

深海采矿柔性管力学性能及加工工艺研究综述

海洋蕴藏着储量丰富的矿产资源,深海矿产资源开发逐渐成为学术界和工程界的研究热点。管道提升式开采方案是目前公认的最具商业前景的海洋矿产开发方案。矿产输运管道作为连接海底中继舱和海上采矿平台的纽带,需要承受恶劣的风、浪、流环境载荷和复杂作业工况的工作载荷,其设计制造和力学性能分析一直备受关注。相比于刚性管道,柔性管道的弯曲刚度小、便于安装与回收、使用寿命较长。然而,柔性管道的结构复杂,各层之间相互影响,金属柔性管道由于自身结构的限制,在深海采矿行业中难以广泛应用,人们开始把目光放在非金属柔性管的设计与应用上。本文回顾了柔性管的发展历程,总结阐述了柔性管设计及加工制造中的力学性能分析方法和力学特性,并对柔性管设计制造的未来发展提供力所能及的展望。

基于三维流动的弯管模型的建立及流场分析

排气歧管是发动机的必要零部件之一,对发动机的性能有很大的影响。文章对排气歧管的弯曲管进行了研究,建立了弯管内气体流动的理论模型,利用FLUENT软件对弯管内气体流动状况进行了仿真,然后对两种弯曲管道(90°-56°管和90°-90°管)中的气体进行了对比分析。结果表明,90°-90°管道内的气体速度分布、压力分布和流线分布更为均匀,流动分离面积和涡流相对较小,速度均匀系数更接近于1,对柴油机进气的影响较小,柴油机的动力性能得以充分发挥。

浇注工艺对高强度抗硫管内壁带状组织的影响研究

内壁带状组织的控制是高强度抗硫管的生产难点之一。在高强度抗硫管电炉冶炼过程中,开展不同浇注工艺(钢水过热度、结晶器电磁搅拌、末端电磁搅拌和连铸拉速等)的对比试验,通过金相显微镜、扫描电镜等分别对连铸坯、热轧态管和调质态管进行微观组织分析,研究了高强度抗硫管内壁带状组织的形成机理及演变规律,探索了不同浇注工艺对高强度抗硫管内壁带状组织的影响。

燃气轮机排气装置叶片结构与制造工艺优化

燃气轮机排气装置的优劣对燃气轮机整机运行效率、稳定性、可靠性有显著影响。分析了燃气轮机排气装置的结构特点,对叶片结构进行优化,并从制造材料、焊接材料、焊接工艺三方面对燃气轮机排气装置制造工艺进行优化。优化后,提升了燃气轮机排气装置的可靠性,延长了使用寿命,降低了制造成本,减少了维护费用,提高了产品竞争力。

海洋工程结构用钢管压制工艺的研究

在传统海洋工程项目中,直径大于等于406mm的结构用钢管通常是按照API2B2012《结构钢管制造规范》采用卷制工艺卷制成型,该工艺施工效率低且费用高。针对此问题,文章通过试验对压制工艺进行研究,其较卷制工艺具有效率高、费用低的优势。文章通过试验研究钢板压制折弯成型对钢管母材强度、塑性、韧性的影响,以及压制工艺扩径对管体尺寸精度、母材和焊缝的力学性能的影响,确定了压制工艺在海洋工程结构用钢管制造中应用的可行性。

支管排烟作用下双层隧道顶棚温度分布试验研究

针对下层隧道采用支管排烟模式的双层盾构隧道,通过开展缩尺寸模型试验对烟气温度分布进行系统研究,探讨火源功率、排烟口开启方案(排烟口数量和距离)和排烟量等关键因素对火灾烟气温度分布的影响。结果表明:随着排烟口距离的增加,顶棚烟气温度逐渐升高;开启距离火源最近的两个排烟口时,顶棚烟气温度最低;随着排烟量的增大,在远离火源的区域顶棚烟气温度逐渐降低;火源上下游顶棚下方温度沿隧道纵向呈现指数衰减规律,在不同的排烟量和火源功率下,相对温度衰减ΔT_(x)/ΔT_(max)的值变化不大。通过对试验数据进行拟合分析,推导出支管排烟模式下,火源上下游顶棚烟气温度纵向衰减预测模型。

用于铝压延厂房油雾控制的环吸式排风罩设计方法

环吸式排风罩是针对铝压延加工工艺油雾散发特征而提出的一种高效捕集设备,可以大幅降低系统风量,从而减少能耗和降低碳排放量,但目前仍缺乏此类排风罩的通用设计方法。本文选取10个铝压延车间铝冷轧机及排风罩为研究对象,探究了不同轧机尺寸组合下排风罩罩口处污染物扩散断面尺寸和排风罩捕集性能,通过回归分析得到了排风罩罩口设计尺寸和设计风量的计算方法,可供工程设计人员参考。

聚乙烯管焊接接头相控阵超声检测的优化设计

在管道工程应用中,由于良好的耐腐蚀性和韧性,聚乙烯(PE)管与其他材料相比具有显着优势,已广泛地应用在核电、油气输送领域;PE管焊接过程中,焊接参数、人员操作和环境等因素会影响聚乙烯管道的焊接情况,可能致使焊接接头内部形成缺陷,影响管道安全运行,而相控阵超声检测技术能够实现聚乙烯管道焊接接头内部结构的无损检测及评估;因此开展PE管焊接接头的相控阵超声实际检测工作,研究了聚乙烯材料的声衰减规律及声频散效应,优化了焊接接头的超声相控阵检测工艺,基于CIVA仿真软件实现了聚乙烯管道相控阵超声检测的声场模拟和缺陷仿真,通过研究检测参数及声学参量变化对检测结果的影响,获得了PE管焊接接头的最优检测工艺;通过加工带有典型缺陷的聚乙烯热熔对接接头试样,对前期基于仿真结果设计的检测工艺以及针对焊接接头相控阵检测研发的楔形耦合组件进行可靠性测试和工艺试验;研究结果为PE管接头缺陷的超声相控阵检测提供了工艺设计的理论支持和可靠的研究方法。

核电厂高压蒸汽管道焊缝切割装置的研制

为了修复某核电厂GPV高压缸排汽管膨胀节导流筒焊缝因热处理不当导致的开裂,研发了一款焊缝切割装置,用于将开裂的焊缝切除并加工坡口以进行下一步的自动焊接修复。首先利用SolidWorks对焊缝切割设备进行了机械设计并三维建模,对驱动电机进行了选型计算,设计了控制系统架构,随后制作了设备样机和膨胀节导流筒模拟体,最后在试验室利用模拟体对设备样机的性能进行了连续切削试验,验证了该装备能够高效完成膨胀节导流筒开裂焊缝的切除和坡口加工,且坡口加工质量优良,装置性能稳定。

基于力学仿真分析的PCCP断丝预警及报警阈值评估方法

分析了钢丝的预应力作用机理和管道的破坏过程,提出了一种基于力学仿真分析的PCCP断丝预警与报警阈值评估方法。通过ABAQUS程序建立了PCCP有限元模型,模拟了包括铺设垫层、安装管道、分步回填在内的完整施工过程,计算了不同埋深、不同设计工作压力近百种工况下管道预应力钢丝、钢筒和管芯混凝土的应力状态,提出将管芯混凝土在水锤作用下起裂的最大允许断丝数作为爆管预警阈值,将管道埋地承载力极限状态的最大允许断丝数作为爆管报警阈值,并分析了不同工作内压和埋深条件下PCCP断丝预警与报警阈值之间的关系。

延长油田某注水示范区地面系统优化改造

延长油田地处鄂尔多斯盆地,属低产、低渗透油藏,注水开发是持续稳产的主要方式。为提高注水开发水平与效果,建立注水示范区,从地下、地上同步调整优化,注水地面系统是否高效、是否适用直接影响着注水开发目标能否实现。为提升示范区注水地面系统适应性,通过注水管网优化改造、注水工艺优化、污水处理站水质提升三方面开展地面系统优化改造,通过管网切割重整、配水间改注水站,实现整体降压、局部增压,注水干线辐射半径小于等于4 km,注水干线流速小于等于1.5 m/s,单井支管流速小于等于1.0 m/s;同时配套单干管、短支线,流动洗井车洗井工艺,完善主要水处理工艺,补齐装置短板,优化药剂投加。改造后,管网效率由43%提高至79%,水质达标率由70%提高至95%,解决了以往注水系统效率低、压损大、能耗高、注不进水、注不够水、水质差的问题。

整体式催化剂的制备及其催化净化发动机尾气的研究进展

随着世界工业规模的不断扩大以及社会的不断发展,越来越多的发动机应用于工业生产中,但发动机排放的尾气造成的环境污染问题也越来越严峻。如何将发动机尾气污染物消除或净化逐渐成为研究热点。目前,催化净化技术是处理大气污染物最有效、应用最广泛的技术之一。如何将开发的粉体催化剂有效地应用到汽车尾气催化净化器并实现工业化应用,其中最关键的因素是整体式催化剂的研发。介绍了整体式催化剂常用的制备工艺,如溶胶-凝胶法、水热法、浸渍法等,并对相关的制备原理进行了描述;同时,对整体式催化剂催化净化发动机尾气如一氧化碳(CO)、氮氧化物(NO_(x))、碳氢化合物(HC)及炭烟颗粒(PM)等的研究进展进行了详细的介绍;最后,对整体式催化剂在催化净化发动机尾气污染物中存在的问题和未来发展趋势进行了总结和展望。