High Pressure Co2 Separation Using Membranes Membrane Selection and Process Modeling

Adewole, Jimoh Kayode Adewole (2015) High Pressure Co2 Separation Using Membranes Membrane Selection and Process Modeling. ["eprint_fieldopt_thesis_type_phd" not defined] thesis, Universiti Sains Malaysia.

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Abstract

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.

Item Type: Thesis (["eprint_fieldopt_thesis_type_phd" not defined])
Additional Information: Full text is available at http://irplus.eng.usm.my:8080/ir_plus/institutionalPublicationPublicView.action?institutionalItemId=2116
Subjects: T Technology
T Technology > TP Chemical Technology > TP155-156 Chemical engineering
Divisions: Kampus Kejuruteraan (Engineering Campus) > Pusat Pengajian Kejuruteraan Kimia (School of Chemical Engineering) > Thesis
Depositing User: Mr Mohd Jasnizam Mohd Salleh
Date Deposited: 13 Jun 2018 02:34
Last Modified: 13 Jun 2018 02:34
URI: http://eprints.usm.my/id/eprint/40776

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