Feedforward control of the transverse strip profile in hot-dip galvanizing lines

Hot-dip galvanizing is a standard technology to produce coated steel strips. The primary objective of the galvanizing process is to establish a homogeneous zinc layer with a defined thickness. One condition to achieve this objective is a uniform transverse distance between the strip and the gas wiping dies, which blow off excessive liquid zinc. Therefore, a flat strip profile at the gas wiping dies is required. However, strips processed in such plants often exhibit residual curvatures which entail unknown flatness defects of the strip. Such flatness defects cause non-uniform air gaps and hence an inhomogeneous zinc coating thickness. Modern hot-dip galvanizing lines often use electromagnets to control the transverse strip profile near the gas wiping dies. Typically, the control algorithms ensure a flat strip profile at the electromagnets because the sensors for the transverse strip displacement are also located at this position and it is unfeasible to mount displacement sensors directly at the gas wiping dies. This brings along that in general a flatness defect remains at the gas wiping dies, which in turn entails a suboptimal coating.In this paper, a model-based method for a feedforward control of the strip profile at the position of the gas wiping dies is developed. This method is based on a plate model of the axially moving strip that takes into account the flatness defects in the strip. First, an estimator of the flatness defects is developed and validated for various test strips and settings of the plant. Using the validated mathematical model, a simulation study is performed to compare the state-of-the-art control approach (flat strip profile at the electromagnets) with the optimization-based feedforward controller (flat strip profile at the gas wiping dies) proposed in this paper. Moreover, the influence of the distance between the gas wiping dies and the electromagnets is investigated in detail.     

Hydrogen wettability of clays: Implications for underground hydrogen storage

This study investigates the ability of hydrogen (H₂) to wet clay surfaces in the presence of brine, with implications for underground hydrogen storage in clay-containing reservoirs. Rather than measuring contact angles directly with hydrogen gas, a suite of other gases (carbon dioxide (CO₂), argon (Ar), nitrogen (N₂), and helium (He)) were employed in the gas-brine-clay system under storage conditions (moderate temperature (333 K) and high pressures (5, 10, 15, and 20 MPa)), characteristic of a subsurface environment with a shallow geothermal gradient. By virtue of analogies to H₂ and empirical correlations, wettabilities of hydrogen on three clay surfaces were mathematically derived and interpreted. The three clays were kaolinite, illite, and montmorillonite and represent 1:1, 2:1 non-expansive, and 2:1 expansive clay groups, respectively. All clays showed water-wetting behaviour with contact angles below 40° under all experimental set-ups. It follows that the presence of clays in the reservoir (or caprock) is conducive to capillary and/or residual trapping of the gas. Another positive inference is that any tested gas, particularly nitrogen, is suitable as cushion gas to maintain formation pressure during hydrogen storage because they all turned out to be more gas-wetting than hydrogen on the clay surfaces; this allows easier displacement and/or retrieval of hydrogen during injection/production. One downside of the predominant water wettability of the clays is the upstaged role of biogeochemical reactions at the wetted brine-clay/silicate interface and their potential to affect porosity and permeability. Water-wetting decreased from kaolinite as most water-wetting clay over illite to montmorillonite as most hydrogen-wetting clay. Their wetting behaviour is consistent with molecular dynamic modelling that establishes that the accessible basal plane of kaolinite's octahedral sheet is highly hydrophilic and enables strong hydrogen bonds whereas the same octahedral sheet in illite and montmorillonite is not accessible to the brine, rendering these clays less water-wetting.     

Back-analysis of geotechnical parameters on PVD-improved ground in the Mekong Delta

This study presents a back-analysis of geotechnical parameters on prefabricated vertical drain improved ground at a site in the Mekong Delta. Various time?settlement behaviors that reflected different clay thicknesses and loading patterns were observed. The total surface settlement behavior at several monitoring locations was simulated using an updated exponential method that considered staged construction. The analyzed results were validated by substituting the values into a theoretical solution for radial consolidation. The estimated theoretical behaviors were comparable with the monitored behaviors. The geotechnical parameters were back-analyzed by applying the previously analyzed results to various theoretical and empirical formulas. However, the use of extensometer data that were installed at large intervals produced different values of the geotechnical properties. Furthermore, finite element analysis supported the back-analyzed total settlement behaviors and nearly disregarded the application of the geotechnical properties that were obtained using either surface or subsurface settlement data. However, settlements and excess pore pressures in the sublayers were not successfully predicted even when the geotechnical properties were adjusted. Thus, subsurface instruments that can be installed closely in thick clay deposits are required to reliably reevaluate the variations in geotechnical properties along a certain depth.     

Comparative analysis on performance of vertical drain improved clay deposit under vacuum or surcharge loading

This paper presents two well-instrumented large-scale field tests of PVD-improved soft soil with vacuum and surcharge preloading, respectively. The two large-scale field tests were conducted adjacent to each other with the same preload. A comparative analysis was performed to investigate the performance of subsoil (i.e., the ground settlement, the layered settlement, the lateral displacement of subsoil and pore water pressure) under vacuum preloading and equivalent surcharge preloading. Some design methods were verified based on the field data. Cone Penetration Tests (CPT) and Vane Shear Tests (VST) were conducted to assess the improvement effects on subsoil after preloading. The results showed that as compared with surcharge preloading, vacuum preloading mitigated the differential settlement of the ground. The vacuum pressure transmitted into the soil with a minor loss through the PVD length. From a practical point of view, the improvement effects by vacuum preloading and surcharge preloading were similar in terms of influence depth and soil strength based on the in-situ tests.     

SGXP—400液压泥炮的应用及其性能分析

通过本钢５＃高炉液压泥炮的技术改造实践，阐述了斜底座式液压泥炮在大型高炉上的应用情况，并且进一步对ＳＧＸＰ—４００液压泥炮的某些性能特点及其液压系统进行了分析。     

未增塑聚氯乙烯(PVC-U)异型材配方基础

PVC-U异型材配方十分复杂,常用原料通常在10种以上。根据大连实德集团实际生产情况,这10多种原料通常以7大组分的方式进行配料和生产。文中就该配方中7大组分的分类、特点及应用情况分别进行了详细介绍。     

旋转导向钻井偏心稳定器横向振动研究

旋转导向钻井偏心稳定器横向振动研究是国家863“可控(闭环)三维轨迹钻井技术”课题研究的部分内容。选取偏心稳定器的心轴作为研究对象,以偏心稳定器心轴连续梁系统的横向振动模型受力分析为基础,根据课题研究中所设计的心轴结构形式,建立了与实际情况较为接近的三铰支点的连续梁系统横向振动方程;并分析了偏心稳定器横向振动对钻井工具和钻具系统的影响,为合理进行心轴设计以及偏心稳定器样机在现场的正确使用和钻井参数的合理选择,提供了科学的理论依据和实用的计算方法。计算实例表明,当钻压范围选择在80~250kN时,215.9mm井眼钻进中的确存在19~20、61~63、162~163r/min前三阶横向共振转速区间,因此在选择钻井参数时应通过钻压与转速的配合,尽可能避开横向共振转速,以保证下部钻具组合系统及作业安全。     

粘土矿物对低渗透储层性质的影响——以鄂尔多斯盆地三叠系低渗透储层为例

粘土矿物是低渗砂岩储层的主要胶结物，对储层物性及开发过程中储层物性变化趋势有着重要的影响和控制作用。另外，粘土矿物也蕴含着大量沉积环境介质的物理化学信息，认识其自然规律，可以有效地指导预测有利储层，认识和改造油层。以鄂尔多斯盆地砂岩储层中的粘土矿物为研究对象，探讨分析粘土矿物对低渗储层性质的影响，该研究对含油气盆地低渗储层有效开发具有一定的参考价值。     

斜井抽油系统优化设计技术研究及应用

结合斜井井身轨迹特点,建立了斜井三维井眼中杆柱轴向载荷和侧向载荷计算数学模型,给出扶正器间距和加重杆配置的计算方法;应用系统工程分析方法,给出系统参数设计的步骤,形成了斜井有杆泵抽油系统抽汲参数优化设计方法,编制了相应的优化设计软件。现场应用实例表明,该优化设计方法理论正确可靠,根据本方法编制的斜井抽油系统优化设计软件用于现场设计,可达到有效降低管杆偏磨,减小悬点载荷,提高油井产量、泵效和井下系统效率之目的。