A Comprehensive Study Of Esterification Of Free Fatty Acid To Biodiesel In a Simulated Moving Bed System

Simulated Moving Bed (SMB) systems are used for separations that are difficult using traditional separation techniques. Due to the advantage of adsorption-based chromatographic separation, SMB has shown promising application in petrochemical and sugar industries, and of late, for chiral drug separations. In recent years, the concept of integration of reaction and in-situ separation in a single unit has achieved considerable attention. The simulated moving bed reactor (SMBR) couples both these unit operations bringing down the operation costs while improving the process performance, particularly for products that require mild operating conditions. However, its application has been limited due to complexity of the SMBR process. Hence, to successfully implement a reaction in SMB, a detailed understanding of the design and operating conditions of the SMBR corresponding to that particular reaction process is necessary. Biodiesel has emerged has a viable alternative to petroleum-based diesel as a renewable energy source in recent years. Biodiesel can be produced by esterification of free fatty acids (present in large amounts in waste oil) with alcohol. The reaction is equilibrium-limited, and hence, to achieve high purity, additional purification steps increases the production cost. Therefore, combining reaction and separation in SMBR to produce high purity biodiesel is quite promising in terms of bringing down the production cost. In this work, the reversible esterification reaction of oleic acid with methanol catalyzed by Amberlyst 15 resin to form methyl oleate (biodiesel) in SMBR has been investigated both theoretically and experimentally. First, the adsorption and kinetic constants were determined for the biodiesel synthesis reaction by performing experiments in a single column packed with Amberlyst 15, which acts as both adsorbent and catalyst. Thereafter, a rigorous model was used to describe the dynamic behaviour of multi-column SMBR followed by experimental verification of the mathematical model. Sensitivity analysis is done to determine robustness of the model. Finally, a few simple multi-objective optimization problems were solved that included both existing and design-stage SMBRs using non-dominated sorting genetic algorithm (NSGA). Pareto-optimal solutions were obtained in both cases, and moreover, it was found that the performance of the SMBR could be improved significantly under optimal operating conditions

MULTI-OBJECTIVE DIFFERENTIAL EVOLUTION: MODIFICATIONS AND APPLICATIONS TO CHEMICAL PROCESSES

Ph.DDOCTOR OF PHILOSOPH

A comprehensive study of esterification and hydrolysis of methyl acetate in simulated moving bed systems

Ph.DDOCTOR OF PHILOSOPH

Operator Training Simulator Using Plantwide Control for Biodiesel Production from Waste Cooking Oil

Kajian ini bertujuan untuk membangunkan simulator latihan operator (OTS) untuk mangkin homogen bagi proses dua langkah biodiesel yang kompleks. Latihan sambil bekerja selalunya memerlukan kos yang tinggi, berisiko dan tidak lengkap kerana beberapa situasi kecemasan mungkin tidak berlaku semasa sesi latihan. Biodiesel dilihat sebagai sumber bahan api alternative, Disebabkan ketersediaan yang terhad sumber tenaga yang tidak boleh diperbaharui dan juga kebimbangan terhadap alam sekitar. Walau bagaimanapun, kos pengeluaran yang tinggi bagi biodiesel menghadkan pengeluaran dan penggunaannya. Salah satu pilihan yang terbaik adalah dengan menggunakan sisa minyak masak (WCO) sebagai sumber bahan mentah bagi pengeluaran biodiesel yang kos efektif dan juga penggunaan WCO yang berkesan. Dalam kajian ini, sisa minyak sawit masak dianggap dengan 6% asid lemak bebas (FFA) sebagai bekalan simpanan. Dua proses pengeluaran biodiesel (kedua-duanya melibatkan pengesteran asid dan transesterifikasi alkali) telah dibandingkan untuk analisis ekonomi dan alam sekitar. Pertama, proses ini dalam simulator Aspen Plus. Selepas itu, kedua-dua proses dioptimumkan dengan mengambil kira keuntungan, tenaga haba dan bahan buangan organik sebagai objektif, dan menggunakan program berasaskan Excel pengoptimuman multi-objektif (EMOO) untuk pengisihan algoritma genetic elitis tidak dikuasai (NSGA-II). Proses 1 mempunyai tiga reaktor transesterifikasi yang menghasilkan sisa organik jauh lebih rendah (32%), memerlukan duti haba yang lebih rendah (39%) dan sedikit keuntungan (1.6%) berbanding Proses 2 yang hanya mempunyai satu reaktor transesterifikasi dan juga urutan pemisahan yang berbeza. Sistem kawalan loji lebar (PWC) yang berkesan adalah penting untuk operasi loji biodiesel yang selamat, lancar dan ekonomi. Oleh itu, sistem PWC yang sesuai telah dibangunkan untuk proses biodiesel yang menggunakan simulasi rangka kerja bersepadu dan heuristik (IFSH). Merit utama metodologi IFSH adalah keberkesanan penggunaan proses simulator yang baik dan heuristik dalam membangunkan sistem PWC dan kesederhanaan applikasinya. Akhir sekali, pelaksanaan sistem kawalan yang dibangunkan dinilai dari segi masa penetapan, sisihan daripada sasaran pengeluaran (DPT), dan jumlah variasi keseluruhan (TV) dalam pembolehubah yang dimanipulasi. Penilaian-penilaian prestasi dan keputusan simulasi dinamik menunjukkan bahawa sistem PWC yang dihasilkan adalah stabil, berkesan, dan teguh terhadap beberapa gangguan. Akhir sekali, OTS telah dibangunkan untuk penghasilan biodiesel daripada WCO. Oleh itu, latihan menggunakan OTS adalah penting. OTS telah dibangunkan untuk pengeluaran biodiesel dan telah diapplikasikan dengan beberapa keadaan proses yang tidak normal. Keadaan proses ini boleh dimuatkan dan digunakan pada bila-bila masa untuk melatih operator baru dan sedia ada. Kajian ini adalah yang pertama dibangunkan menggunakan struktur lengkap PWC dan OTS untuk mangkin yang homogeneous bagi dua langkah pengeluaran biodiesel daripada WCO. ________________________________________________________________________________________________________________________ This study aims at developing an operator training simulator (OTS) for the complex homogeneously catalyzed two-step biodiesel process. On-job training is often costly, risky and incomplete as some emergency situations may not arise during the training session. Therefore, training using an OTS is crucial. Pertaining to the limited availability of non-renewable energy sources and the environmental concerns, biodiesel is considered as a potential alternative fuel. However, the high production cost of biodiesel limits its manufacture and utilization. One attractive option is to use waste cooking oil (WCO) as the feedstock that enables cost effective biodiesel production and also facilitates effective WCO utilization. This study considers waste cooking palm oil with 6% free fatty acids (FFA) as feedstock. Two biodiesel production processes (both involving acid esterification and alkali transesterification) are compared for economic and environmental objectives. Firstly, these processes are simulated realistically in Aspen Plus simulator. Subsequently, both the processes are optimized considering profit, heat duty and organic waste as objectives, and using an Excel-based multi-objective optimization (EMOO) program for the elitist non-dominated sorting genetic algorithm (NSGA-II). Process 1 having three transesterification reactors produces significantly lower organic waste (by 32%), requires lower heat duty (by 39%) and slightly more profitable (by 1.6%) compared to Process 2 having a single transesterification reactor and also a different separation sequence. An effective plantwide control (PWC) system is crucial for the safe, smooth, and economical operation of a biodiesel plant. Hence, a suitable PWC system is developed for the biodiesel process using the integrated framework of simulation and heuristics (IFSH). The main merits of the IFSH methodology are effective use of rigorous process simulators and heuristics in developing a PWC system and simplicity of application. Later, the performance of the developed control system is assessed in terms of settling time, deviation from the production target (DPT), and overall total variation (TV) in manipulated variables. These performance assessments and the results of dynamic simulations showed that the developed PWC system is stable, effective, and robust in the presence of several disturbances. Finally, an OTS has been developed for the biodiesel production from WCO. The developed OTS for biodiesel production process has been investigated for several abnormal process conditions. These process scenarios can be loaded and utilized at any point in time to train the new and existing operators. This is the first study to develop a complete PWC structure and OTS for a homogeneously catalyzed two-step biodiesel production from WCO

A Comprehensive Study of Sequential Simulated Moving Bed: Purification of Xylo-oligosaccharides and fructose-glucose

Chromatographic separation is a promising alternative for separation and purification of sugars in industry. Simulated moving bed (SMB) technique has been proven as an efficient chromatographic separation method due to its enhanced productivity and purity, reduced solvent consumption, convenient operating control, and improved separation performance for some systems with low resolution and selectivity. The sequential simulated moving bed (SSMB) is a modification of the conventional SMB process, which currently has some applications for sugar separation due to its low solvent consumption. This work mainly investigates the design strategy of the innovative SSMB process and explore its advantages and disadvantages over the SMB process based on the xylo-oligosaccharides (XOSs) and fructose-glucose systems. SSMB separation of XOSs, a functional food additive in the form of a oligomeric saccharide, was firstly conducted. DOWEX MONOSPHERETM 99/310 resin ionized with K+, which has better selectivity compared with Ca2+ and Na+ was used as the stationary phase.Breakthrough experiments showed that XOSs and the two major industrial impurities, xylose and arabinose, all exhibit linear isotherms. Transport-dispersive (TD) model parameters were determined by pulse experiments carried out at various flowrates. Finally, both the averaged and individual parameters of XOSs and XOS2-XOS7 were obtained. Lab-scale SSMB experiments and the corresponding simulations were carried out to validate the acquired TD model parameters and adsorption isotherms. After that, in order to investigate the optimal operating conditions of this process, the multi-objective optimizations were carried out for three cases with various objectives and constraints. It was found that, for a given SSMB unit, there exist a pareto curve for simultaneous maximization of purity and unit throughput. The flowrate ratios (m values), however, exhibit some trends that are different from those of conventional SMB and cannot be explained by the direct use of Triangle Theory with averaged m values. According to the literature, the fructose-glucose system is representative and have linear isotherms over a wide concentration range, which makes it an excellent example system to conduct some basic analysis and performance prediction. Therefore, the multi-objective optimization of SMB and SSMB processes was conducted and compared based on the fructose-glucose system. The results show that the solvent consumption of SSMB is always less than that of SMB unit

Optimal operation of simulated moving bed and varicol processes for bio-separation

Master'sMASTER OF ENGINEERIN

Optimization of Chiral Separation of Nadolol by Simulated Moving Bed Technology

Simulated Moving Bed (SMB) technology has gained increasing attention as one of the most powerful techniques for chromatographic separations due to its cost-effectiveness and efficiency. Application of SMB technology is especially important in the pharmaceutical industry for production of enantiopure drugs, as required under strict FDA regulations, to avoid possible adverse effects of racemic drugs. In this study, the performance of the SMB process in separation of racemic nadolol on a perphenyl carbamoylated beta cyclodextrin (β-CD) stationary phase was investigated. The equilibrium dispersive model coupled with bi-Langmuir adsorption isotherm and lumped kinetic approximation, constitute the mathematical model used to simulate the dynamic behavior of SMB. Multi-objective optimization was carried out using a robust state-of-the-art optimization technique, non-dominated sorting genetic algorithm (NSGA). Two optimization problems were solved to simultaneously maximize productivity and purity of the product and minimize consumption of desorbent. The generated Pareto optimal solutions showed that selection of operating conditions can significantly affects the performance of SMB to meet the desired objectives

Algorithms for Self-Optimising Chemical Platforms

The appreciable interest in machine learning has stimulated the development of self-optimising chemical platforms. The power of harnessing computer aided design, coupled with the desire for improved process sustainability and economics, has led to self-optimising systems being applied to the optimisation of reaction screening and chemical synthesis. The algorithms used in these systems have largely been limited to a select few, with little focus paid to the development of optimisation algorithms specifically for chemical systems. The expanding digitisation of the process development pipeline necessitates the further development of algorithms to tackle the diverse array of chemistries and systems .Improvements and expansion to the available algorithmic portfolio will enable the wider adoption of automated optimisation systems, with novel algorithms required to match the previously unmet domain specific demands and improve upon classical designed experiment procedures which may offer a reduction in optimisation efficiency. The work in this thesis looks to develop novel approaches, targeting areas currently lacking or under developed in automated chemical system optimisations. This includes development and application of hybrid approaches looking at improving the robustness of optimisation and increasing the users understanding of the optimum region, as well as expanding multi-objective algorithms to the mixed variable domain, enabling the wider application of efficient optimisation and data acquisition methodologies

Controlled Branching of Industrially Important Polymers: Modeling and Multi-objective Optimization

Long chain branching (LCB) in any polymerization is of profound importance. It helps in improving certain properties such as melt strength and strain hardening. Branched polymers are, therefore, having different characteristics than linear polymers. In addition to having good end use properties, they are well suited for various processing applications such as blow molding, thermoforming, extrusion coating etc. As real world applications demand different extents of branching of polymers for different applications, this study aims to perform an investigation for a controlled way of long chain branching of polymers with enhanced properties. The main goal of this research is, therefore, three fold; viz. i) Finding the optimal process conditions for the desired combination of conflicting objectives, ii) Development of a kinetic model for long chain branched polypropylene system based on the available experimental data from open literature and simultaneously performing the multi objective optimization for the desired combination of conflicting performance objectives within experimental limits, and iii) Development of Kriging based surrogate model to replace the first principles based computationally expensive model to save execution time, while performing the multi objective optimization task for a highly non-linear, multi-modal search space. First, a batch optimization study for the bulk polymerization of vinyl acetate has been considered to find optimal process conditions for imparting LCB in polymer architecture. A theoretical study has been conducted with a validated model to observe the effect of live radical concentration on long chain branching as this is an important factor for branching in polymer molecule via ‘chain transfer to polymer’ route

Improvement in the design and operation of Bio-reactors and Bio-separators based on SMB Technology

Ph.DDOCTOR OF PHILOSOPH