Academic literature on the topic 'Mokhada'

Abstract Hydrate formation in pipelines has been a serious flow assurance issue in the oil and gas industry hence several methods have been developed to predict the conditions which favor its formation in order to develop a proper mitigation plan to control its formation. This study evaluated the inhibition effect of hydrogen gas on a methane / methane gas mixture using UNISIM software and Towler & Mokhatab correlation. After which the effectiveness of this prediction method was determined by comparing their predictions with experimentally obtained data. The predictions of hydrate formation temperature of the methane / methane gas mixtures by Unisim and correlation all showed a decrease in their hydrate formation temperatures when mixed with hydrogen gas. An error evaluation on the two prediction methods showed that the UNISIM prediction has a better prediction than the correlation for all the methane / methane gas mixture because it predicted hydrate formation temperature closer to the experimental predictions.

Base-Isolation system using laminated rubber bearings is considered to be an efficient technology of providing a mitigation of seismic damage for structures and equipments, and has proven to be reliable and cost-effective. There are many structures in various countries, which concern not only new constructions but also existing structures, especially after the Loma Prieta (1989), Northridge (1994) and Kobe (1995) earthquakes. Since seismic response of base-isolated structures greatly depends on the mechanical properties of the bearings, deep understanding of the characteristics of the bearings under the conditions of interest is essential toward a rational design of the base-isolation. Considering that the base isolation system in the two horizontal directions has already been used in the bridges and buildings, behaviors of the bearings under the multi-axial loading should be studied experimentally. In the actual design of multi-axial base-isolated structures, bilinear models have often been used independently in the two horizontal directions, and the coupling effects of hysteretic loops are not considered (AASHATO 1999; JRA 1998). Mokha et al. (1990) investigated the behaviors of Teflon friction bearings under tri-axial loading, and proposed a model for this type of bearings (Constantinou et al. 1990; Mokha et al. 1993). Multi-axial behaviors of a HDR and a steel damper have been investigated by Yasaka et al. (1988), and they empirically developed a multi-spring model, in which several bilinear springs or Ramberg-Osgood springs are circularly arranged with regular angle intervals. Huang et al. (2000) investigated the characteristics of tri-axial behaviors of a LRB and proposed a multi-axial model by considering a circular force interaction function of the bilinear model. However, systematic studies have not been conducted on the experimental investigation of several types of laminated rubber bearings. In addition, previously proposed models for laminated rubber bearings do not have definite theoretical backgrounds in the extension into multi-axial case, and they also do not consider the hardening behaviors in the large deformation range. In this paper, multi-axial restoring forces of various types of laminated rubber bearings, which have widely been used in the base-isolated bridges, are investigated experimentally. Then, a one-dimensional and two-dimensional models of the bearings are proposed on the basis of the experimental results.

Objectives/Scope Gas dehydration is a vital step in the processing of natural gas, where triethylene glycol (TEG) is commonly employed as a desiccant to decrease and control the water content, ensuring the safe processing and transmission of natural gas streams [Abdulrahman, R. K., 2014, Anyadiegwu, C., 2014, Chebbi, R., 2019, Khan, M. A., 2012, Mokhatab, S., 2019, Wang, X., 2013]. The traditional layout of TEG gas dehydration typically consists of an inlet scrubber, a TEG contactor vessel, and an outlet scrubber [Bahadori, A., 2014, Chebbi, R., 2019, Viteri, R., 2006]. The inlet scrubber is responsible for removing any liquid carryover to meet the specifications for the gas stream entering the TEG contactor. The TEG contactor, which serves as the central component of gas dehydration systems, carries the crucial mass transferring section for achieving efficient and effective gas dehydration. The outlet scrubber aims to capture free liquid TEG carryover in the dry gas stream, thereby minimizing TEG loss [Gupta, A., 1996, Trueba, L. J., 2011]. This research paper focuses on a case study involving the design of a TEG contactor for an offshore floating production, storage, and offloading (FPSO) facility. Designing the TEG contactor for an FPSO platform presents several challenges, such as limited footprint and equipment height, motion effect caused by sea waves, and stringent performance requirements. To reduce the footprint, piping complexity, and overall weight of the high-pressure gas-side equipment, the design integrates the gas inlet scrubber and outlet scrubbers into the TEG contactor (i.e., one integrated TEG contactor served the functions of three vessels of inlet scrubber, TEG contactor, and outlet scrubber). The integrated inlet scrubber incorporates proprietary inlet vane diffusers, a mesh pad, and proprietary demisting cyclones. Similarly, the integrated outlet scrubber consists of a mesh pad and demisting cyclones to minimize TEG losses. The integration of the inlet and outlet scrubbers leads to an increased height of the TEG contactor, resulting in higher weight and cost. Therefore, it is essential to develop innovative approaches for the internal design of the TEG contactor to optimize its height while maintaining or improving process performance. Given the significant influence of TEG contactor internals on separation efficiency and dehydration performance, the design approach aims to meet the height optimization requirement while enhancing process performance. In this study, high-efficiency vessel internals with advanced features for height reduction and motion effect mitigation were designed for the integrated TEG contactor. In the integral scrubber section, the demisting cyclones were integrated into the chimney trays, significantly reducing the overall height requirement. Moreover, the distances between vessel internals and level settings at various sections were justified for reduction. Wave baffles, liquid protection plates, and level instrument dampening were incorporated into/recommended to the design to mitigate the impact of FPSO motion. To ensure desirable gas flow distribution and process performance, the process efficiency of the innovative internal design was verified using computational fluid dynamics (CFD) [Lu, Y., 2009, Olaleye, O., 2022]. CFD analysis was also employed to investigate the effect of FPSO motion on liquid levels and level instrumentation, confirming that the overall design efficiently diminishes motion effects with satisfactory liquid level response.