High Pressure Co2 Separation Using Membranes Membrane Selection and Process Modeling

Pemisahan CO2 daripada gas asli (NG) telah menarik minat penyelidikan kerana permintaan tenaga yang semakin meningkat dan keperluan teknik penulenan gas yang lebih cekap dan mesra alam. Kebanyakan NG dihasilkan bersama CO2 yang perlu disingkirkan demi untuk meningkatkan nilai kalorinya. Teknologi membran merupakan salah satu teknologi yang digunakan secara meluas untuk penyingkiran CO2. Walau bagaimanapun, pasarannya masih kecil berbanding proses-proses pemisahan gas yang lain. Ini adalah kerana penggunaan bahan-bahan membran dengan prestasi pemisahan yang rendah dan keadaan pengoperasian modul yang tidak optimum. Pengoptimuman bersistematik bagi setiap peringkat penyediaan membran dan operasi modul bertekanan tinggi telah dicadangkan untuk menyelesaikan masalah tersebut.Salah satu cabaran utama operasi bertekanan tinggi adalah fenomena kesan penusukan pemplastikan yang disebabkan oleh peningkatan tekanan suapan. Polimer komersil polisulfona telah diubahsuai untuk mengoptimumkan prestasi pemisahannya. Kajian bertekanan tinggi dan pemodelan matematik telah dijalankan untuk menilai prestasi pemisahan membran. Bagi mewujudkan tekanan suapan yang tertinggi semasa penyingkiran CO2 tanpa pemplastikan, ciri-ciri pemisahan membran telah dikaji menggunakan ujian penelapan pada tekanan mencecah 57 bar. Kajian dinamik bagi prestasi membran juga dilakukan menggunakan ujikaji penelapan bagi tempoh masa antara 5 hingga 1080 jam (45 hari) dengan pelbagai tekanan antara 6 hingga 57 bar. Model matematik telah dibangunkan berdasarkan teori “dual-sorption” dan model keseluruhan tidak bergerak. Proses pengoptimuman untuk pemilihan membran telah dicapai dengan menggunakan kaedah pengoptimuman pelbagai objektif, manakala keadaan operasi modul dicapai menggunakan model pengaturcaraan pengoptimuman kekangan non-linear dan algoritma “Golden search” yang dilaksanakan menggunakan MATLAB. Tekanan pemplastikan bagi membran yang disediakan adalah 41.07 bar manakala kebolehtelapan dan kememilihan pada tekanan ini adalah masing-masing 5.99 Barrer, dan 44.19. Ini merupakan peningkatan sebanyak 17.65% bagi tekanan pemplastikan dan 66.39% bagi kebolehtelapan. Walau bagaimanapun, membran tersebut kehilangan kira-kira 79.65% kebolehtelapannya pada tekanan ini manakala kememilihannya meningkat sebanyak 91.13% jika dibanding dengan nilai pada 5 bar. Ujian kebolehtelapan yang bergantung kepada masa mendedahkan bahawa tekanan pemplastikan sebagai titik keseimbangan boleh digunakan sebagai kekangan dalam pengoptimuman proses pemisahan gas membran. Model matematik yang dibangunkan menunjukkan keupayaan ramalan yang sangat baik untuk tekanan pemplastikan. Pemilihan bahan membran juga didapati mampu dioptimumkan dengan cekap dengan menggunakan kaedah pengoptimuman multi-objektif. ________________________________________________________________________________________________________________________ Separation of CO2 from natural gas (NG) has attracted research interest due to increasing demand for energy and the need for more energy efficient and environmental friendly gas purification techniques. Most of the NG is coproduced with CO2 which need to be removed in order to increase its calorific value. Membrane separation is one of the widely used technologies for CO2 removal. However, its market share is still very small as compared to other gas separation processes. This is due to the use of membrane materials with poor separation performance and the use of non-optimum module operating conditions. Systematic optimization of every stage of membrane preparation and high pressure module operation was proposed to solve this problem. One major challenge of high pressure operation is penetrant-induced plasticization phenomenon which is caused by increasing the feed pressure. Commercial polysulfone polymer was modified to optimize its separation performance. High pressure experimental studies and mathematical modeling were performed to evaluate the separation performance of the membrane. To establish the highest possible feed pressure which can be attained during CO2 removal without plasticization, transport properties of the membrane were evaluated using permeation tests at pressure up to 57 bar. Also, dynamic evaluation of membrane performance was performed using timedependent permeation experiments over a period ranging from 5 hours to 1080 hours (45 days) at various pressures between 6 and 57 bar. Mathematical model was developed based on the theory of dual-sorption and the total immobilization models. The optimization for membrane selection was achieved using a multi-objective optimization method while that of module operating conditions was achieved using non-linear programming constraint optimization model and a Golden search algorithm which was implemented using MATLAB. The plasticization pressure of the prepared membrane is 41.07 bar while the permeability and selectivity at this pressure are 5.99 Barrer, and 44.19 respectively. This is equivalent to a 17.65% and 66.39% increase in plasticization pressure and permeability, respectively. However, the membrane lost about 79.65% of its permeability at this pressure while its selectivity increased by 91.13% as compared to the value at 5 bar. The timedependent permeability tests revealed plasticization pressure as possible equilibrium point which can be used as constraint during membrane gas separation process optimization. The mathematical model developed showed an excellent predictive capability for plasticization pressure. It was also shown that membrane materials selection can be efficiently optimized using the multi – objective optimization approach

Finite element failure analysis of wires for civil engineering applications with various crack-like laminations

This paper presents the finite element (FE) failure predictions and analyses of a typical wire for civil engineering applications with various crack-like lamination types (Single and double), geometries (straight-end and inclined-end) and orientations (longitudinal, lateral and transverse). FE prediction and analysis of the failure of notched pre-cracked wires with a surface across-the-thickness crack-like lamination validated with experimental results are also presented. The FE predicted fracture shape for the notched pre-cracked wires that consists of a cup and cone fracture shape below the bottom tip of the surface across-the-thickness crack-like lamination agrees with the experimental fracture shape. Wires with the double straight-end and double inclined-end crack-like/line-type laminations exhibit a “slant-middle W” and a “zigzag” fractures respectively. Above and below the lateral mid-width across-the-thickness lamination, the wires with the lateral mid-width across-the-thickness lamination exhibit a combination of a transverse mid-thickness flat fracture that is perpendicular to the lateral mid-width across-the-thickness lamination and negatively inclined slant fractures on each side of the mid-thickness flat fracture at the remaining outer edges of the wire's thickness. On both the front and back sides of the transverse mid-thickness across-the-width lamination, the wires with the transverse mid-thickness across-the-width lamination exhibit a combination of transverse flat fractures parallel to the transverse mid-thickness across-the-width lamination and positively inclined slant fractures at the outer edges of the wire's thickness. FE failure analysis reveals that fracture initiations do not always begin at the termini of every longitudinal crack-like/line-type lamination as reported in a published fractographic failure analysis report of wires with longitudinal crack-like laminations. Fracture initiation only begins at the termini/tip of longitudinal inclined-end crack-like laminations and at the termini/tip of transverse and lateral laminations. FE failure analysis also reveals that wires with single straight-end, double straight-end and double inclined-end longitudinal crack-like/line-type laminations do not exhibit cup and cone fractures as reported. This work further demonstrates the need to employ FE failure analysis as a complimentary or alternative failure analysis approach where the destruction/alteration of the fracture markings by corrosion could affect the accuracy of fractographic failure analysis.Fil: Adewole, Kazeem Kayode. University Of Newcastle; Reino Unido. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Nordeste. Instituto de Modelado e Innovación Tecnológica. Universidad Nacional del Nordeste. Facultad de Ciencias Exactas Naturales y Agrimensura. Instituto de Modelado e Innovación Tecnologica; ArgentinaFil: Bull, Steve J.. University Of Newcastle; Reino Unid

Effects of defects and reverse bending on tensile properties of tensile armour wires

PhD ThesisFlexible pipes are used for risers and flowlines in the offshore oil and gas industry and in many other applications. As part of the construction of these pipes, tensile armour wires are incorporated to resist longitudinal stresses which arise during installation and service. Tensile armour wires also resist hoop stresses for pipes without a designated pressure armour layer. The flexible pipeline manufacturing industry desires a better understanding of the tensile armour wire fracture mechanism, and especially the effects of defects with dimensions less than 0.2mm. Reverse bending operations (which arise due to the wire moving through paired rollers on unreeling during pipe manufacture) also affect the tensile properties of the tensile armour wires. Customarily, engineers estimate the safe load carrying capacity of defective wires solely by multiplying the ultimate strength obtained from a tension test by the original nominal area of the wire without any consideration for the fracture mechanisms of the wire. This approach may overestimate the strength of the wire. Recent research considering the fracture mechanisms of wires has employed a classical fracture mechanics approach, mainly using Linear Elastic Fracture Mechanics (LEFM) and/or Net Section Theory (NST). Obtaining parameters for fracture mechanics analyses requires large/thick standard fracture mechanics test specimens which cannot be made out of tensile armour wires due to their small size. Also fracture mechanics analyses based on these parameters including the elastic plastic crack opening displacement (COD) and J-integral parameters are largely size and geometry dependent making transferability of the results obtained from full size specimens to actual structures questionable. Laboratory tensile testing and tensile testing finite element simulations with mechanism-based fracture mechanics carried out on the as-received tensile armour wire and tensile armour wires with engineered defects reveal that the tensile armour wires fail by a shear mechanism. They also reveal that flat bottom scratches, pointed end scratches and dents identified from the Scanning Electron Microscope images of the as-received wire surface reduce the ultimate load and extension at fracture of the wires. In addition, denting was found to increase the wires yield load while scratching reduced the wire‟s yield load. The reduction in the tensile/ mechanical properties of tensile armour wires were found to depend largely on defect dimensions rather than defect locations with defects less than 0.2mm in any of its dimensions causing less than 0.072%, 0.238% and 10.946% reduction the yield load, the ultimate load and the displacement at fracture of tensile armour wires respectively. Laboratory and finite element simulations of reverse bending, straightening and tensile testing of the reverse bent tensile armour wires reveal that reverse bending and straightening operations reduce the ultimate load and fracture displacement of the wires. This work also reveals that the reverse bending process can only reveal near surface laminations as wires with mid depth laminations or with scratches less than 1mm deep would pass through the reverse bending process without fracturing

Psychosocial Implications of COVID-19 on Children in Nigeria

There has been a plethora of research since the emergence of COVID-19 around the world but several of these studies have not focused on the psychosocial implication of the novel Coronavirus on children in Nigeria. Though the psychosocial impact of the virus is huge, there is paucity of literature addressing the needs of the Nigerian children during the pandemic. The paper explored the psychosocial implications (health, poverty issues, safety needs and learning) of COVID-19 on children in Nigeria. The study recommends the expansion of social assistance for children of families in extreme poverty, and there is a need to adapt standard physical distancing protocols to reflect the characteristics of children in different settings. Also, the Government of Nigeria should prioritize child-centred services. Training parents and caregivers on how to talk to their children about the pandemic, managing their mental health and providing tools to help children’s learning will be crucial

Early Experience with Ponseti Club Foot Management in Lagos, Nigeria

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Entrepreneurial Well-Being of Small and Medium Scale Business Owners: Role of Gender and Emotional Strategies

Entrepreneurial well-being has been associated with different emotional strategies but, the exact impact of cognitive reappraisal and expressive suppression together with gender difference on entrepreneurial well-being has not been adequately studied among Nigerian small-scale enterprises. Therefore, in this study, we investigated the role of emotional strategies and gender on entrepreneurial well-being among small and medium scale business owners in Ibadan, Oyo State, Nigeria. An ex-post facto research design was adopted to collect data from three hundred and ten (310) small and medium scale business owners at Bodija market area of Ibadan, Oyo State. The questionnaire comprised demographic variables and two standardized psychological scales used to assess relevant information from the respondents: emotional strategies scale and entrepreneurial well-being scale. Multiple regression and t-test for independent samples were used to test the three hypotheses formulated in the study. Findings reveal that cognitive reappraisal and expressive suppression jointly predicted entrepreneurial well-being among small and medium business owners (R = .458 and a multiple R2 of .210). Further analysis showed that only cognitive reappraisal independently predicted entrepreneurial well-being (β = .405, p<.05). Again, t-test analysis revealed a statistically significant mean difference in entrepreneurial well-being (t(308) = 5.060, p < .05) between high and low emotional strategy. The findings further revealed no gender difference in entrepreneurial well-being of small and medium scale business owners. Therefore, this study concludes that entrepreneurial well-being is largely dependent on the individual level of cognitive reappraisal, while gender difference does not constitute any barrier for both existing and potential entrepreneurs. Based on the findings, it was recommended that entrepreneurs, existing as well as intending, should endeavour to embark on periodical psychologically structured training with focus on emotional management/regulation

The role of big data in smart city

The expansion of big data and the evolution of Internet of Things (IoT) technologies have played an important role in the feasibility of smart city initiatives. Big data offer the potential for cities to obtain valuable insights from a large amount of data collected through various sources, and the IoT allows the integration of sensors, radio-frequency identification, and Bluetooth in the real-world environment using highly networked services. The combination of the IoT and big data is an unexplored research area that has brought new and interesting challenges for achieving the goal of future smart cities. These new challenges focus primarily on problems related to business and technology that enable cities to actualize the vision, principles, and requirements of the applications of smart cities by realizing the main smart environment characteristics. In this paper, we describe the existing communication technologies and smart-based applications used within the context of smart cities. The visions of big data analytics to support smart cities are discussed by focusing on how big data can fundamentally change urban populations at different levels. Moreover, a future business model that can manage big data for smart cities is proposed, and the business and technological research challenges are identified. This study can serve as a benchmark for researchers and industries for the future progress and development of smart cities in the context of big data