Asia-Pacific Journal of Chemical Engineering
1932-2135
1932-2143
Mỹ
Cơ quản chủ quản: Wiley-Blackwell , WILEY
Lĩnh vực:
Renewable Energy, Sustainability and the EnvironmentChemical Engineering (miscellaneous)Waste Management and Disposal
Các bài báo tiêu biểu
Design and optimization of isolated energy systems through pinch analysis Abstract Isolated energy systems seem to be a promising option for electrifying remote locations where grid extension is not feasible or economical. Integration of battery bank as means of energy storage with different renewable energy systems can enhance the system reliability and its overall performance. Therefore, appropriate choices of generator sizes and the battery bank capacity are critical to the success of such renewable‐based isolated power systems. In this article, the tools of pinch analysis are extended to design isolated renewable energy systems. The importance of setting targets before design is highlighted for designing renewable‐based isolated energy systems. The system sizing through the grand composite curve (GCC) representation of stored energy is proposed in this article. The set of all feasible solutions, defined as the design space for the system, is graphically represented for in‐depth visualization. The relation between the design space approach for designing and optimizing an isolated energy system and the principles of pinch analysis have been established in this article. The GCC representation also provides opportunity to the system designer for strategic load growth without affecting the system size. Copyright © 2011 Curtin University of Technology and John Wiley & Sons, Ltd.
Tập 6 Số 3 - Trang 518-526 - 2011
CFD modeling of rotary cement kilns Abstract Rotary cement kilns are widely used to convert calcineous raw meal into cement clinker, and are key components in the cement industry. In this article, we report a comprehensive computational fluid dynamics (CFD)‐based model to capture key transport processes in rotary cement kilns. Separate but coupled computational models were developed for the bed and the freeboard regions of the rotary kiln. The complex swirling airflow produced by kiln burners, coal combustion, gas‐phase combustion of volatile matter and radiative heat transfer in the freeboard region were modeled. The clinkerization reactions in the bed region were modeled assuming solids as pseudo fluids. Coating formation in cement kilns (for both bed and freeboard regions) was considered. Appropriate source and sink terms were developed to model transfer of CO2 from the bed to the freeboard region due to calcination reaction in the bed region. The developed bed and freeboard models were coupled by mass and energy communication through common interface. These coupled computational models were able to quite satisfactorily predict the available data from industrial kilns and previously published results. The computational models were also able to capture the intricacies of the burning zones of rotary cement kilns for changing burner‐operational parameters like axial to swirl ratio and oxygen enrichment. The developed approach, computational models and simulation results will not only help in developing better understanding of cement kilns but also provide quantitative information about influence of burner design and other design parameters on kiln performance. Copyright © 2008 Curtin University of Technology and John Wiley & Sons, Ltd.
Tập 3 Số 2 - Trang 106-118 - 2008
An analytical study on settling of non‐spherical particles Abstract The clarification of the unsteady falling movement of immersed bodies in fluids occurs in several natural situations and many manufacturing processes, e.g. particulate processing and two‐phase solid–liquid applications. In this paper, the acceleration motion of a spherical particle in an incompressible Newtonian environment has been studied for a wide range of Reynolds numbers using a drag coefficient as defined by Chien [S.F. Chien. SPE Drill. Complet., 1994; 9, 281]. The governing equation is strongly nonlinear due to nonlinear nature of the drag coefficient. An analytical mathematical procedure is performed to express an expression for velocity of the particle during the acceleration motion using variational iteration method. Therefore, both the acceleration and position of the particle were easily obtained. The equation of motion was solved in a general form and also for some realistic solid–liquid combinations. The effects of particle sphericity and continuous‐phase viscosity were investigated for different practical situations, where the results satisfactorily describe the settling behavior of the particle. The results were compared with a numerical method and very good agreement was obtained. This work demonstrates the effectiveness of the current mathematical method and presents a simple approach for this type of problem, where the derived expression can be used in different numerical and analytical surveys. Copyright © 2010 Curtin University of Technology and John Wiley & Sons, Ltd.
Tập 7 Số 1 - Trang 63-72 - 2012
An exergy calculator tool for process simulation Abstract The constant tightening of environmental regulations and the ongoing need to reduce operating costs have posed a challenge for the design of any chemical process. Process engineers use process simulators to help them perform calculations that will, ultimately, result in design parameters or operating conditions for a plant or process. Exergy is a potential indicator that can aid in the design of energy efficient chemical processes and plants. The exergy concept has been increasingly used as a tool to locate the critical energy use in many industrial processes, both chemical and non‐chemical. However, currently most process simulators in the market do not offer the capability of calculating the exergy of a process. An open‐source exergy calculator has been created by embedding the calculation procedure in an open‐source chemical process simulator. This improves process simulation by including a potential tool for design teams to quickly evaluate several process options in detail in order to understand their energy utilisation. A simple exergy analysis for a gas processing facility is used to demonstrate the capabilities of the tool. The analysis shows where the largest quantities of exergy are being consumed within the plant, thus pointing to areas where improvement in energy usage can be made. The use of exergy as a potential design and retrofit tool is also discussed. Copyright © 2007 Curtin University of Technology and John Wiley & Sons, Ltd.
Tập 2 Số 5 - Trang 431-437 - 2007
Discussion of shale rock wettability and the methods to determine it Abstract Because of ultra‐low permeability of shale rocks, capillary pressure is very high. Wettability not only determines the value of capillary pressure, but, more importantly, it also determines whether the capillary pressure is a driving force or a resistance to fluid flow. This paper is to address the wettability characteristics of shale rocks. First, the common methods to determine wettability are reviewed and discussed for their feasibility for shale rocks. It is found that the real reservoir wettability must be determined in a system with oil and water being present; it cannot be determined by comparing the water and oil‐wetting angles measured on dry rock surfaces. It is also interesting to note that more shale rocks are water wet, although the oil‐wetting angles are smaller than water‐wetting angles on dry rock surfaces. The factors that affect shale wettability are also reviewed.
Tập 13 Số 6 - 2018
Optimization of reactive distillation processes using differential evolution strategies Abstract Many problems of process synthesis and design in chemical engineering can be modeled as mixed integer nonlinear programming (MINLP) problems. They include both the continuous (floating point) and integer variables. A common feature of this class of mathematical problems is the potential existence of nonconvexities due to a particular form of the objective function and/or the set of constraints. Owing to their combinatorial nature, these problems are considered to be difficult to solve. In the present study, a model based on an extension of conventional distillation is proposed for the synthesis of ethylene glycol using the nonequilibrium reactive distillation. The proposed model is simulated using the relaxation and homotopy‐continuation methods. The differential evolution (DE) algorithm is applied to find the minimum total annualized cost of the nonequilibrium reactive distillation for the synthesis of ethylene glycol, which is a MINLP optimization problem. The optimization is performed with nonideal vapor–liquid equilibrium using ten strategies of DE, considering synthesis reaction on all trays. The results show that the optimized objective function values are better than those reported in the literature, and mostly independent of the number of trays and of the reaction distribution. It is shown that the proposed homotopy‐continuation method with DE strategy (DE/best/1/bin) is capable of providing optimized solutions which are close to the global optimum, and reveals its adequacy for the optimization of reactive distillation problems encountered in chemical engineering practice. Copyright © 2007 Curtin University of Technology and John Wiley & Sons, Ltd.
Tập 2 Số 4 - Trang 322-335 - 2007
Comparative kinetics of esterification of methanol–acetic acid in the presence of liquid and solid catalysts ABSTRACT Esterification of acetic acid with methanol to produce methyl acetate in an isothermal stirred batch reactor has been studied. Sulfuric acid was used as a liquid catalyst, and Indion‐180, Indion‐190 and Amberlyst‐16wet ion exchange resins were used as solid catalysts. The feed mole ratio was varied from 1 : 1 to 1 : 4. The reaction temperatures were varied from 305.15 to 333.15 K for sulfuric acid as catalyst and 323.15 to 353.15 K for the solid catalysts. The catalyst concentrations were used in the range of 1% to 5%, for the sulfuric acid catalyst, and 0.01 to 0.05 g/cc, for the solid catalysts. The effect of temperature, catalyst concentration, agitation speed, size of catalyst particle and reactant concentration on the acetic acid conversion was investigated. A second‐order kinetic rate equation was proposed to fit the experimental data. For both forward and backward reactions, the activation energies were estimated from Arrhenius plots. The reaction rate increased with catalyst concentration and temperature for both the liquid and solid catalysts. The acetic acid conversion was found to increase with increases in acetic acid to methanol ratio in the feed. The developed kinetic rate equation was used for the simulation of reactive distillation process, in our laboratory column. © 2014 Curtin University of Technology and John Wiley & Sons, Ltd.
Tập 9 Số 6 - Trang 791-799 - 2014
Simultaneous heat integration and the synthesis of biogas processes from animal waste Abstract The objective of this work was to perform simultaneous heat integration and the synthesis of biogas process based on the mixed‐integer nonlinear programming (MINLP) model. A synthesis model recently developed by Drobež et al. [R. Drobež, Z. Novak Pintarič, B. Pahor, Z. Kravanja. Chem. Biochem. Eng. Q, 2009; 23, 445–459] has been upgraded for simultaneous heat integration. An industrial case study was solved in order to describe the mathematical model and to illustrate the heat‐integrated MINLP synthesis approach. The optimal solution indicates that during the synthesis of biogas process and when selecting the best auxiliary facilities significant benefit can be obtained if the selected process and auxiliary facilities are heat integrated. In this way almost the complete consumption of hot utility and 1/3 of cold utility can be saved, and thus most of the electricity and heat produced in the cogeneration system from biogas can be sold as surplus to the distribution networks. The proposed optimal synthesis of heat‐integrated biogas process may improve a company's economic performance and significantly reduce its environmental impact by converting environmentally harmful organic and animal wastes into valuable products. Copyright © 2010 Curtin University of Technology and John Wiley & Sons, Ltd.
Tập 6 Số 5 - Trang 734-749 - 2011
Carbon dioxide adsorption by modified carbon nanotubes Abstract In this study the CO2 adsorption of three different diameters of multi‐walled carbon nanotubes (MWCNT) and single‐walled carbon nanotube (SWCNT) was investigated for a mixture of CO2 /Ar at a temperature of 70 °C and atmospheric pressure. The largest diameter of MWCNT showed the highest CO2 uptake of 65.2 mg CO2 adsorbed per g adsorbent. One of the MWCNTs were modified with urea (CH4 N2 O) under two different loading durations with the aim of improving adsorption capacity. After such a functionalization, the CO2 uptake increased from 53.9 to 64.1 mg CO2 adsorbed per g adsorbent after 4 h loading duration. These findings indicate considerable potential of functionalized carbon nanotubes in comparison with other silica and carbon adsorbents. © 2015 Curtin University of Technology and John Wiley & Sons, Ltd.
Tập 10 Số 6 - Trang 885-892 - 2015
Supported ionic liquids as green catalyst for 2‐butanol synthesis from transesterification of <i>sec</i>‐butyl acetate Abstract Two supported ionic liquids using molecular sieve SBA‐15 as supporter were prepared and employed as efficient catalysts for the synthesis of 2‐butanol (SBOH) via the transesterification of sec ‐butyl acetate and methanol (MeOH). [SBA‐15‐Ps‐im]HSO4 performed better in the catalytic activity and was chosen for further studying the influence of experimental conditions. The effects of various parameters, such as the catalyst dosage, initial reactant molar ratio, and reaction time on the reaction were investigated systematically. The maximum conversion of sec ‐butyl acetate (89.2%) was obtained under the optimum reaction conditions. In addition, the catalyst of supported ionic liquids can be easily separated by simple filtration, and the reusability test indicates that the catalyst has outstanding utility for repeated use. © 2016 Curtin University of Technology and John Wiley & Sons, Ltd.
Tập 11 Số 6 - Trang 901-909 - 2016