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Processes, Volume 6, Issue 11 (November 2018)

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Cover Story (view full-size image) Fleet-level monitoring and fault diagnostics tools are essential to increase the availability, and [...] Read more.
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Open AccessArticle Fault Detection in Wastewater Treatment Systems Using Multiparametric Programming
Processes 2018, 6(11), 231; https://doi.org/10.3390/pr6110231
Received: 28 August 2018 / Revised: 30 October 2018 / Accepted: 12 November 2018 / Published: 20 November 2018
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Abstract
In this work, a methodology for fault detection in wastewater treatment systems, based on parameter estimation, using multiparametric programming is presented. The main idea is to detect faults by estimating model parameters, and monitoring the changes in residuals of model parameters. In the
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In this work, a methodology for fault detection in wastewater treatment systems, based on parameter estimation, using multiparametric programming is presented. The main idea is to detect faults by estimating model parameters, and monitoring the changes in residuals of model parameters. In the proposed methodology, a nonlinear dynamic model of wastewater treatment was discretized to algebraic equations using Euler’s method. A parameter estimation problem was then formulated and transformed into a square system of parametric nonlinear algebraic equations by writing the optimality conditions. The parametric nonlinear algebraic equations were then solved symbolically to obtain the concentration of substrate in the inflow, S c i n , inhibition coefficient, K i , and specific growth rate, μ o , as an explicit function of state variables (concentration of biomass, X ; concentration of organic matter, S c ; concentration of dissolved oxygen, S o ; and volume, V ). The estimated model parameter values were compared with values from the normal operation. If the residual of model parameters exceeds a certain threshold value, a fault is detected. The application demonstrates the viability of the approach, and highlights its ability to detect faults in wastewater treatment systems by providing quick and accurate parameter estimates using the evaluation of explicit parametric functions. Full article
(This article belongs to the Special Issue Wastewater Treatment Processes)
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Open AccessArticle Numerical Simulation of Water Absorption and Swelling in Dehulled Barley Grains during Canned Porridge Cooking
Processes 2018, 6(11), 230; https://doi.org/10.3390/pr6110230
Received: 18 October 2018 / Revised: 11 November 2018 / Accepted: 13 November 2018 / Published: 20 November 2018
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Abstract
Understanding the hydration behavior of cereals during cooking is industrially important in order to optimize processing conditions. In this study, barley porridge was cooked in a sealed tin can at 100, 115, and 121 °C, respectively, and changes in water uptake and hygroscopic
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Understanding the hydration behavior of cereals during cooking is industrially important in order to optimize processing conditions. In this study, barley porridge was cooked in a sealed tin can at 100, 115, and 121 °C, respectively, and changes in water uptake and hygroscopic swelling in dehulled barley grains were measured during the cooking of canned porridge. In order to describe and better understand the hydration behaviors of barley grains during the cooking process, a three-dimensional (3D) numerical model was developed and validated. The proposed model was found to be adequate for representing the moisture absorption characteristics with a mean relative deviation modulus (P) ranging from 4.325% to 5.058%. The analysis of the 3D simulation of hygroscopic swelling was satisfactory for describing the expansion in the geometry of barley. Given that the model represented the experimental values adequately, it can be applied to the simulation and design of cooking processes of cereals grains, allowing for saving in both time and costs. Full article
(This article belongs to the Special Issue Process Modelling and Simulation)
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Open AccessArticle Alternative Approach to Current EU BAT Recommendation for Coal-Fired Power Plant Flue Gas Desulfurization Wastewater Treatment
Processes 2018, 6(11), 229; https://doi.org/10.3390/pr6110229
Received: 18 October 2018 / Revised: 12 November 2018 / Accepted: 14 November 2018 / Published: 19 November 2018
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Abstract
Fossil fuel combustion is a serious environmental problem. Significant quantities of flue gasses and wastewater, requiring further treatment, are produced. This article compares three wet flue gas desulfurization (FGD) wastewater treatment methods: coagulation with precipitation using iron(III) ions—recommended by the European Union as
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Fossil fuel combustion is a serious environmental problem. Significant quantities of flue gasses and wastewater, requiring further treatment, are produced. This article compares three wet flue gas desulfurization (FGD) wastewater treatment methods: coagulation with precipitation using iron(III) ions—recommended by the European Union as the best available technique (BAT)—and two alternative advanced oxidation processes (Fe2+/H2O2 and Fe0/H2O2). Both oxidation processes that were used met the technical FGD wastewater treatment requirements of the BAT. The best treatment effects, expressed as pollutants’ removal, were obtained for the Fe2+/H2O2 process for 150/300 mg/L reagent doses. It allows effective removal of boron up to 212 mg/L and heavy metals up to below the detection limit <0.010 mg/L for Pb and <0.005 mg/L for Cu. Therefore, the Fe2+/H2O2 process could be an option for FGD wastewater treatment as an alternative to the BAT recommended iron(III)-based coagulation with precipitation. Additionally, an analysis of variance was applied to check the significance of the two independent variables and their interactions. Statistical analysis confirmed high efficiency and applicability of treatment process. Full article
(This article belongs to the Special Issue Wastewater Treatment Processes)
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Open AccessArticle Production Process Optimization of Metal Mines Considering Economic Benefit and Resource Efficiency Using an NSGA-II Model
Processes 2018, 6(11), 228; https://doi.org/10.3390/pr6110228
Received: 30 September 2018 / Revised: 8 November 2018 / Accepted: 13 November 2018 / Published: 19 November 2018
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Abstract
The optimization of the production process of metal mines has been traditionally driven only by economic benefits while ignoring resource efficiency. However, it has become increasingly aware of the importance of resource efficiency since mineral resource reserves continue to decrease while the demand
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The optimization of the production process of metal mines has been traditionally driven only by economic benefits while ignoring resource efficiency. However, it has become increasingly aware of the importance of resource efficiency since mineral resource reserves continue to decrease while the demand continues to grow. To better utilize the mineral resources for sustainable development, this paper proposes a multi-objective optimization model of the production process of metal mines considering both economic benefits and resource efficiency. Specifically, the goals of the proposed model are to maximize the profit and resource utilization rate. Then, the fast and elitist Non-Dominated Sorting Genetic Algorithm (NSGA-II) is used to optimize the multi-objective optimization model. The proposed model has been applied to the optimization of the production process of a stage in the Huogeqi Copper Mine. The optimization results provide a set of Pareto-optimal solutions that can meet varying needs of decision makers. Moreover, compared with those of the current production indicators, the profit and resource utilization rate of some points in the optimization results can increase respectively by 2.99% and 2.64%. Additionally, the effects of the decision variables (geological cut-off grade, minimum industrial grade and loss ratio) on objective functions (profit and resource utilization rate) were discussed using variance analysis. The sensitivities of the Pareto-optimal solutions to the unit copper concentrate price were studied. The results show that the Pareto-optimal solutions at higher profits (with lower resource utilization rates) are more sensitive to the unit copper concentrate prices than those obtained in regions with lower profits. Full article
(This article belongs to the Section Computational Methods)
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Open AccessPerspective Application of Laser-Induced Fluorescence in Functional Studies of Photosynthetic Biofilms
Processes 2018, 6(11), 227; https://doi.org/10.3390/pr6110227
Received: 18 October 2018 / Revised: 9 November 2018 / Accepted: 13 November 2018 / Published: 19 November 2018
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Abstract
Biofilms are a ubiquitous form of life for microorganisms. Photosynthetic biofilms such as microphytobenthos (MPB) and biological soil crusts (BSC) play a relevant ecological role in aquatic and terrestrial ecosystems, respectively. On the other hand, photosynthetic epilithic biofilms (PEB) are major players in
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Biofilms are a ubiquitous form of life for microorganisms. Photosynthetic biofilms such as microphytobenthos (MPB) and biological soil crusts (BSC) play a relevant ecological role in aquatic and terrestrial ecosystems, respectively. On the other hand, photosynthetic epilithic biofilms (PEB) are major players in the microbial-induced decay of stone structures of cultural heritage. The use of fluorescence techniques, namely, pulse-amplitude-modulated fluorometry, was crucial to understanding the photophysiology of these microbial communities, since they made it possible to measure biofilms’ photosynthetic activity without disturbing their delicate spatial organization within sediments or soils. The use of laser-induced fluorescence (LIF) added further technical advantages, enabling measurements to be made at a considerable distance from the samples, and under daylight. In this Perspective, we present state-of-the-art LIF techniques, show examples of the application of LIF to MPB and present exploratory results of LIF application to BSC, as well as to PEB colonizing stone structures of cultural heritage. Thereafter, we discuss the perspectives of LIF utilization in environmental research and monitoring, in cultural heritage conservation and assessment, and in biotechnological applications of photosynthetic biofilms. Full article
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Open AccessFeature PaperArticle Development of a Dynamic Model and Control System for Load-Following Studies of Supercritical Pulverized Coal Power Plants
Processes 2018, 6(11), 226; https://doi.org/10.3390/pr6110226
Received: 8 October 2018 / Revised: 6 November 2018 / Accepted: 14 November 2018 / Published: 17 November 2018
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Abstract
Traditional energy production plants are increasingly forced to cycle their load and operate under low-load conditions in response to growth in intermittent renewable generation. A plant-wide dynamic model of a supercritical pulverized coal (SCPC) power plant has been developed in the Aspen Plus
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Traditional energy production plants are increasingly forced to cycle their load and operate under low-load conditions in response to growth in intermittent renewable generation. A plant-wide dynamic model of a supercritical pulverized coal (SCPC) power plant has been developed in the Aspen Plus Dynamics® (APD) software environment and the impact of advanced control strategies on the transient responses of the key variables to load-following operation and disturbances can be studied. Models of various key unit operations, such as the steam turbine, are developed in Aspen Custom Modeler® (ACM) and integrated in the APD environment. A coordinated control system (CCS) is developed above the regulatory control layer. Three control configurations are evaluated for the control of the main steam; the reheat steam temperature is also controlled. For studying servo control performance of the CCS, the load is decreased from 100% to 40% at a ramp rate of 3% load per min. The impact of a disturbance due to a change in the coal feed composition is also studied. The CCS is found to yield satisfactory performance for both servo control and disturbance rejection. Full article
(This article belongs to the Special Issue Modeling and Simulation of Energy Systems)
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Open AccessArticle Modeling the Circular Economy Processes at the EU Level Using an Evaluation Algorithm Based on Shannon Entropy
Processes 2018, 6(11), 225; https://doi.org/10.3390/pr6110225
Received: 23 October 2018 / Revised: 6 November 2018 / Accepted: 13 November 2018 / Published: 16 November 2018
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Abstract
In this paper we propose a methodology to study circular economy processes based on mathematical modelling. In open-ended systems, waste could be converted back to recycling, transforming the economy from linear to circular. The concept of entropy and the second law of thermodynamics
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In this paper we propose a methodology to study circular economy processes based on mathematical modelling. In open-ended systems, waste could be converted back to recycling, transforming the economy from linear to circular. The concept of entropy and the second law of thermodynamics give the argument for a scale reduction of material circulation. As humans extract more and more energy and matter for the economy, the degree of entropy is likely to increase. Based on the findings of economic studies on the implications of industrialization in the case of growing economies, this study aims at evaluating circular economy processes at the European Union (EU) level using a Shannon-Entropy-based algorithm. An entropy-based analysis was conducted for the 28 European Union countries during the time frame 2007–2016. The modelling process consists of constructing a composite indicator which is composed of a weighted sum of all indicators developed by an algorithm based on Shannon Entropy. The weights assigned to each indicator in our analysis measure the significance of each indicator involved in the development of the composite indicator. The results are similar to the international rakings, consolidating and confirming the accuracy and reliability of this approach. Full article
(This article belongs to the Special Issue Energy, Economic and Environment for Industrial Production Processes)
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Open AccessArticle Energy Consumption and Economic Analyses of a Supercritical Water Oxidation System with Oxygen Recovery
Processes 2018, 6(11), 224; https://doi.org/10.3390/pr6110224
Received: 15 October 2018 / Revised: 8 November 2018 / Accepted: 14 November 2018 / Published: 16 November 2018
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Abstract
Oxygen consumption is one of the factors that contributes to the high treatment cost of a supercritical water oxidation (SCWO) system. In this work, we proposed an oxygen recovery (OR) process for an SCWO system based on the solubility difference between oxygen and
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Oxygen consumption is one of the factors that contributes to the high treatment cost of a supercritical water oxidation (SCWO) system. In this work, we proposed an oxygen recovery (OR) process for an SCWO system based on the solubility difference between oxygen and CO2 in high-pressure water. A two-stage gas–liquid separation process was established using Aspen Plus software to obtain the optimized separation parameters. Accordingly, energy consumption and economic analyses were conducted for the SCWO process with and without OR. Electricity, depreciation, and oxygen costs contribute to the major cost of the SCWO system without OR, accounting for 46.18, 30.24, and 18.01 $·t−1, respectively. When OR was introduced, the total treatment cost decreased from 56.80 $·t−1 to 46.17 $·t−1, with a reduction of 18.82%. Operating cost can be significantly reduced at higher values of the stoichiometric oxygen excess for the SCWO system with OR. Moreover, the treatment cost for the SCWO system with OR decreases with increasing feed concentration for more reaction heat and oxygen recovery. Full article
(This article belongs to the Special Issue Gas Capture Processes)
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Open AccessArticle Calculation Model and Rapid Estimation Method for Coal Seam Gas Content
Processes 2018, 6(11), 223; https://doi.org/10.3390/pr6110223
Received: 27 September 2018 / Revised: 11 November 2018 / Accepted: 12 November 2018 / Published: 14 November 2018
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Abstract
Coalbed gas content is the most important parameter for forecasting and preventing the occurrence of coal and gas outburst. However, existing methods have difficulty obtaining the coalbed gas content accurately. In this study, a numerical calculation model for the rapid estimation of coal
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Coalbed gas content is the most important parameter for forecasting and preventing the occurrence of coal and gas outburst. However, existing methods have difficulty obtaining the coalbed gas content accurately. In this study, a numerical calculation model for the rapid estimation of coal seam gas content was established based on the characteristic values of gas desorption at specific exposure times. Combined with technical verification, a new method which avoids the calculation of gas loss for the rapid estimation of gas content in the coal seam was investigated. Study results show that the balanced adsorption gas pressure and coal gas desorption characteristic coefficient (Kt) satisfy the exponential equation, and the gas content and Kt are linear equations. The correlation coefficient of the fitting equation gradually decreases as the exposure time of the coal sample increases. Using the new method to measure and calculate the gas content of coal samples at two different working faces of the Lubanshan North mine (LBS), the deviation of the calculated coal sample gas content ranged from 0.32% to 8.84%, with an average of only 4.49%. Therefore, the new method meets the needs of field engineering technology. Full article
(This article belongs to the Special Issue Gas Capture Processes)
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Open AccessArticle Waste Fuel Combustion: Dynamic Modeling and Control
Processes 2018, 6(11), 222; https://doi.org/10.3390/pr6110222
Received: 15 October 2018 / Revised: 8 November 2018 / Accepted: 9 November 2018 / Published: 13 November 2018
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Abstract
The focus of this study is to present the adherent transients that accompany the combustion of waste derived fuels. This is accomplished, in large, by developing a dynamic model of the process, which can then be used for control purposes. Traditional control measures
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The focus of this study is to present the adherent transients that accompany the combustion of waste derived fuels. This is accomplished, in large, by developing a dynamic model of the process, which can then be used for control purposes. Traditional control measures typically applied in the heat and power industry, i.e., PI (proportional-integral) controllers, might not be robust enough to handle the the accompanied transients associated with new fuels. Therefore, model predictive control is introduced as a means to achieve better combustion stability under transient conditions. The transient behavior of refuse derived fuel is addressed by developing a dynamic modeling library. Within the library, there are two models. The first is for assessing the performance of the heat exchangers to provide operational assistance for maintenance scheduling. The second model is of a circulating fluidized bed block, which includes combustion and steam (thermal) networks. The library has been validated using data from a 160 MW industrial installation located in Västerås, Sweden. The model can predict, with satisfactory accuracy, the boiler bed and riser temperatures, live steam temperature, and boiler load. This has been achieved by using process sensors for the feed-in streams. Based on this model three different control schemes are presented: a PI control scheme, model predictive control with feedforward, and model predictive control without feedforward. The model predictive control with feedforward has proven to give the best performance as it can maintain stable temperature profiles throughout the process when a measured disturbance is initiated. Furthermore, the implemented control incorporates the introduction of a soft-sensor for measuring the minimum fluidization velocity to maintain a consistent level of fluidization in the boiler for deterring bed material agglomeration. Full article
(This article belongs to the Special Issue Modeling and Simulation of Energy Systems)
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Open AccessFeature PaperArticle Membrane-Based Processes: Optimization of Hydrogen Separation by Minimization of Power, Membrane Area, and Cost
Processes 2018, 6(11), 221; https://doi.org/10.3390/pr6110221
Received: 29 September 2018 / Revised: 29 October 2018 / Accepted: 7 November 2018 / Published: 12 November 2018
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Abstract
This work deals with the optimization of two-stage membrane systems for H2 separation from off-gases in hydrocarbons processing plants to simultaneously attain high values of both H2 recovery and H2 product purity. First, for a given H2 recovery level
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This work deals with the optimization of two-stage membrane systems for H2 separation from off-gases in hydrocarbons processing plants to simultaneously attain high values of both H2 recovery and H2 product purity. First, for a given H2 recovery level of 90%, optimizations of the total annual cost (TAC) are performed for desired H2 product purity values ranging between 0.90 and 0.95 mole fraction. One of the results showed that the contribution of the operating expenditures is more significant than the contribution of the annualized capital expenditures (approximately 62% and 38%, respectively). In addition, it was found that the optimal trade-offs existing between process variables (such as total membrane area and total electric power) depend on the specified H2 product purity level. Second, the minimization of the total power demand and the minimization of the total membrane area were performed for H2 recovery of 90% and H2 product purity of 0.90. The TAC values obtained in the first and second cases increased by 19.9% and 4.9%, respectively, with respect to that obtained by cost minimization. Finally, by analyzing and comparing the three optimal solutions, a strategy to systematically and rationally provide ‘good’ lower and upper bounds for model variables and initial guess values to solve the cost minimization problem by means of global optimization algorithms is proposed, which can be straightforward applied to other processes. Full article
(This article belongs to the Special Issue Membrane Materials, Performance and Processes)
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Open AccessFeature PaperArticle Impact of Filled Materials on the Heating Uniformity and Safety of Microwave Heating Solid Stack Materials
Processes 2018, 6(11), 220; https://doi.org/10.3390/pr6110220
Received: 16 October 2018 / Revised: 27 October 2018 / Accepted: 29 October 2018 / Published: 7 November 2018
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Abstract
Microwave heating of solid stack materials is common but bothered by problems of uneven heating and electric discharge phenomena. In this paper, a method introducing fluid materials with different relative permittivity is proposed to improve the heating uniformity and safety of solid stack
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Microwave heating of solid stack materials is common but bothered by problems of uneven heating and electric discharge phenomena. In this paper, a method introducing fluid materials with different relative permittivity is proposed to improve the heating uniformity and safety of solid stack materials. Simulations have been computed based on the finite element method (FEM) and validated by experiments. Simulation results show that the introducing of fluid materials with proper relative permittivity does improve the heating uniformity and safety. Fluid materials with the larger real part of relative permittivity could obviously lower the maximum modulus value of the electric field for about 23 times, and will lower the coefficient of variation (COV) in general, although in small ranges that it has fluctuated. Fluid materials with the larger imaginary part of relative permittivity, in a range from 0 to 0.3, can make a more efficient heating and it could lower the maximum modulus value of the electric field by 34 to 55% on the whole studied range. However, the larger imaginary part of relative permittivity will cause worse heating uniformity as the COV rises by 246.9% in the same process. The computed results are discussed and methods to reach uniform and safe heating through introducing fluid materials with proper relative permittivity are proposed. Full article
(This article belongs to the Special Issue Microwave Applications in Chemical Engineering)
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Open AccessArticle Simulation of High Pressure Separator Used in Crude Oil Processing
Processes 2018, 6(11), 219; https://doi.org/10.3390/pr6110219
Received: 10 October 2018 / Revised: 19 October 2018 / Accepted: 1 November 2018 / Published: 5 November 2018
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Abstract
The aim of this research was to simulate a high-pressure (HP) separator in order to investigate the effect of changing separator operating conditions on product properties. In this study, the results obtained using the CHEMCAD simulation software package were compared with those obtained
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The aim of this research was to simulate a high-pressure (HP) separator in order to investigate the effect of changing separator operating conditions on product properties. In this study, the results obtained using the CHEMCAD simulation software package were compared with those obtained using the UniSim software package. The simulation results were comparable with industrial data. A sensitivity study was conducted by changing the gas stream properties, such as temperature, pressure, and flow rate, in order to investigate and optimize the process. The results showed that increasing the separator inlet pressure from 30 to 80 bar decreased the outlet gas flow rate from 1202 to 871.15 kmol/h. Also, the methane mole fraction increased from 0.69 to 0.74; however, the preheater heating duty was increased from 8.71 to 11.48 GJ/h. The simulation results showed that increasing the temperature of the separator feed stream from 43 to 83 °C increased the flow rate of the outlet gas stream from 871.15 to 1142.98 kmol/h. However, this temperature change reduced the methane concentration in the gas product and decreased the heating duty of the heat exchanger. Finally, the study demonstrated that there is no effect of increasing the inlet feed flow rate on the produced methane gas concentration. Full article
(This article belongs to the Section Chemical Systems)
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Open AccessArticle The Effect of Collision Angle on the Collision and Adhesion Behavior of Coal Particles and Bubbles
Processes 2018, 6(11), 218; https://doi.org/10.3390/pr6110218
Received: 8 October 2018 / Revised: 30 October 2018 / Accepted: 31 October 2018 / Published: 5 November 2018
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Abstract
The collision and adhesion behavior of particles and bubbles is the key to flotation. Many scholars have investigated the collision and adhesion law of regularly shaped and homogeneous particles (glass beads, glass fiber), but the particles in flotation cells are irregular and heterogeneous.
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The collision and adhesion behavior of particles and bubbles is the key to flotation. Many scholars have investigated the collision and adhesion law of regularly shaped and homogeneous particles (glass beads, glass fiber), but the particles in flotation cells are irregular and heterogeneous. Therefore, it is necessary to take actual coal samples as the research object. First, based on previous research, a particle–bubble collision and adhesion behavior measurement device was set up to study free falling coal particles with different surface properties colliding and adhering to a bubble (db = 1.0 mm). Then bituminous coal from Inner Mongolia was taken as the test object, and the collision and adhesion process of a large amount of coal particles was traced. The entire process is photographically recorded by a camera and analyzed frame by frame through a self-designed software. Finally, the relationship between collision angle and initial settlement position (initial), particle velocity (process), and adhesion efficiency (result) was studied by taking the collision angle as the cut-in point. It was found that both the distribution range of the initial settlement position and the particle central distribution interval are expanding outward with the increase of collision angle. The resistance layer has an important influence on the velocity of particles. The collision angle had an effect on adhesion efficiency and the adhesion efficiency of low-density particles was higher than that of high-density particles. Full article
(This article belongs to the Special Issue Fluid Flow in Fractured Porous Media)
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Open AccessFeature PaperArticle Multicellular Models Bridging Intracellular Signaling and Gene Transcription to Population Dynamics
Processes 2018, 6(11), 217; https://doi.org/10.3390/pr6110217
Received: 26 July 2018 / Revised: 29 October 2018 / Accepted: 31 October 2018 / Published: 4 November 2018
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Abstract
Cell signaling and gene transcription occur at faster time scales compared to cellular death, division, and evolution. Bridging these multiscale events in a model is computationally challenging. We introduce a framework for the systematic development of multiscale cell population models. Using message passing
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Cell signaling and gene transcription occur at faster time scales compared to cellular death, division, and evolution. Bridging these multiscale events in a model is computationally challenging. We introduce a framework for the systematic development of multiscale cell population models. Using message passing interface (MPI) parallelism, the framework creates a population model from a single-cell biochemical network model. It launches parallel simulations on a single-cell model and treats each stand-alone parallel process as a cell object. MPI mediates cell-to-cell and cell-to-environment communications in a server-client fashion. In the framework, model-specific higher level rules link the intracellular molecular events to cellular functions, such as death, division, or phenotype change. Cell death is implemented by terminating a parallel process, while cell division is carried out by creating a new process (daughter cell) from an existing one (mother cell). We first demonstrate these capabilities by creating two simple example models. In one model, we consider a relatively simple scenario where cells can evolve independently. In the other model, we consider interdependency among the cells, where cellular communication determines their collective behavior and evolution under a temporally evolving growth condition. We then demonstrate the framework’s capability by simulating a full-scale model of bacterial quorum sensing, where the dynamics of a population of bacterial cells is dictated by the intercellular communications in a time-evolving growth environment. Full article
(This article belongs to the Special Issue Systems Biomedicine)
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Open AccessFeature PaperArticle Diagnostics-Oriented Modelling of Micro Gas Turbines for Fleet Monitoring and Maintenance Optimization
Processes 2018, 6(11), 216; https://doi.org/10.3390/pr6110216
Received: 14 October 2018 / Revised: 29 October 2018 / Accepted: 31 October 2018 / Published: 2 November 2018
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Abstract
The market for the small-scale micro gas turbine is expected to grow rapidly in the coming years. Especially, utilization of commercial off-the-shelf components is rapidly reducing the cost of ownership and maintenance, which is paving the way for vast adoption of such units.
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The market for the small-scale micro gas turbine is expected to grow rapidly in the coming years. Especially, utilization of commercial off-the-shelf components is rapidly reducing the cost of ownership and maintenance, which is paving the way for vast adoption of such units. However, to meet the high-reliability requirements of power generators, there is an acute need of a real-time monitoring system that will be able to detect faults and performance degradation, and thus allow preventive maintenance of these units to decrease downtime. In this paper, a micro gas turbine based combined heat and power system is modelled and used for development of physics-based diagnostic approaches. Different diagnostic schemes for performance monitoring of micro gas turbines are investigated. Full article
(This article belongs to the Special Issue Modeling and Simulation of Energy Systems)
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Open AccessArticle Second-Order Symmetric Smoothed Particle Hydrodynamics Method for Transient Heat Conduction Problems with Initial Discontinuity
Processes 2018, 6(11), 215; https://doi.org/10.3390/pr6110215
Received: 21 September 2018 / Revised: 19 October 2018 / Accepted: 23 October 2018 / Published: 2 November 2018
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To eliminate the numerical oscillations appearing in the first-order symmetric smoothed particle hydrodynamics (FO-SSPH) method for simulating transient heat conduction problems with discontinuous initial distribution, this paper presents a second-order symmetric smoothed particle hydrodynamics (SO-SSPH) method. Numerical properties of both SO-SSPH and FO-SSPH
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To eliminate the numerical oscillations appearing in the first-order symmetric smoothed particle hydrodynamics (FO-SSPH) method for simulating transient heat conduction problems with discontinuous initial distribution, this paper presents a second-order symmetric smoothed particle hydrodynamics (SO-SSPH) method. Numerical properties of both SO-SSPH and FO-SSPH are analyzed, including truncation error, numerical accuracy, convergence rate, and stability. Experimental results show that for transient heat conduction with initial smooth distribution, both FO-SSPH and SO-SSPH can achieve second-order convergence, which is consistent with the theoretical analysis. However, for one- and two-dimensional conduction with initial discontinuity, the FO-SSPH method suffers from serious unphysical oscillations, which do not disappear over time, and hence it only achieves first-order convergence; while the present SO-SSPH method can avoid unphysical oscillations and has second-order convergence rate. Therefore, the SO-SSPH method is a feasible tool for solving transient heat conduction problems with both smooth and discontinuous distributions, and it is easy to be extended to high dimensional cases. Full article
(This article belongs to the Section Computational Methods)
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Open AccessArticle Experimental Study on Feasibility of Enhanced Gas Recovery through CO2 Flooding in Tight Sandstone Gas Reservoirs
Processes 2018, 6(11), 214; https://doi.org/10.3390/pr6110214
Received: 15 October 2018 / Revised: 31 October 2018 / Accepted: 31 October 2018 / Published: 2 November 2018
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The development of natural gas in tight sandstone gas reservoirs via CH4-CO2 replacement is promising for its advantages in enhanced gas recovery (EGR) and CO2 geologic sequestration. However, the degree of recovery and the influencing factors of CO2
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The development of natural gas in tight sandstone gas reservoirs via CH4-CO2 replacement is promising for its advantages in enhanced gas recovery (EGR) and CO2 geologic sequestration. However, the degree of recovery and the influencing factors of CO2 flooding for enhanced gas recovery as well as the CO2 geological rate are not yet clear. In this study, the tight sandstone gas reservoir characteristics and the fluid properties of the Sulige Gasfield were chosen as the research platform. Tight sandstone gas long-core displacement experiments were performed to investigate (1) the extent to which CO2 injection enhanced gas recovery (CO2-EGR) and (2) the ability to achieve CO2 geological storage. Through modification of the injection rate, the water content of the core, and the formation dip angle, comparative studies were also carried out. The experimental results demonstrated that the gas recovery from CO2 flooding increased by 18.36% when compared to the depletion development method. At a lower injection rate, the diffusion of CO2 was dominant and the main seepage resistance was the viscous force, which resulted in an earlier CO2 breakthrough. The dissolution of CO2 in water postponed the breakthrough of CO2 while it was also favorable for improving the gas recovery and CO2 geological storage. However, the effects of these two factors were insignificant. A greater influence was observed from the presence of a dip angle in tight sandstone gas reservoirs. The effect of CO2 gravity separation and its higher viscosity were more conducive to stable displacement. Therefore, an additional gas recovery of 5% to 8% was obtained. Furthermore, the CO2 geological storage exceeded 60%. As a consequence, CO2-EGR was found to be feasible for a tight sandstone gas reservoir while also achieving the purpose of effective CO2 geological storage especially for a reservoir with a dip angle. Full article
(This article belongs to the Special Issue Fluid Flow in Fractured Porous Media)
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Open AccessArticle The Impact of Oriented Perforations on Fracture Propagation and Complexity in Hydraulic Fracturing
Processes 2018, 6(11), 213; https://doi.org/10.3390/pr6110213
Received: 30 September 2018 / Revised: 25 October 2018 / Accepted: 26 October 2018 / Published: 1 November 2018
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Abstract
To better understand the interaction between hydraulic fracture and oriented perforation, a fully coupled finite element method (FEM)-based hydraulic-geomechanical fracture model accommodating gas sorption and damage has been developed. Damage conforms to a maximum stress criterion in tension and to Mohr–Coulomb limits in
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To better understand the interaction between hydraulic fracture and oriented perforation, a fully coupled finite element method (FEM)-based hydraulic-geomechanical fracture model accommodating gas sorption and damage has been developed. Damage conforms to a maximum stress criterion in tension and to Mohr–Coulomb limits in shear with heterogeneity represented by a Weibull distribution. Fracturing fluid flow, rock deformation and damage, and fracture propagation are collectively represented to study the complexity of hydraulic fracture initiation with perforations present in the near-wellbore region. The model is rigorously validated against experimental observations replicating failure stresses and styles during uniaxial compression and then hydraulic fracturing. The influences of perforation angle, in situ stress state, initial pore pressure, and properties of the fracturing fluid are fully explored. The numerical results show good agreement with experimental observations and the main features of the hydraulic fracturing process in heterogeneous rock are successfully captured. A larger perforation azimuth (angle) from the direction of the maximum principal stress induces a relatively larger curvature of the fracture during hydraulic fracture reorientation. Hydraulic fractures do not always initiate at the oriented perforations and the fractures induced in hydraulic fracturing are not always even and regular. Hydraulic fractures would initiate both around the wellbore and the oriented perforations when the perforation angle is >75°. For the liquid-based hydraulic fracturing, the critical perforation angle increases from 70° to 80°, with an increase in liquid viscosity from 10−3 Pa·s to 1 Pa·s. While for the gas fracturing, the critical perforation angle remains 62° to 63°. This study is of great significance in further understanding the near-wellbore impacts on hydraulic fracture propagation and complexity. Full article
(This article belongs to the Special Issue Fluid Flow in Fractured Porous Media)
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Open AccessArticle Enantioselective Extraction of Phenylalanine Enantiomers Using Environmentally Friendly Aqueous Two-Phase Systems
Processes 2018, 6(11), 212; https://doi.org/10.3390/pr6110212
Received: 9 October 2018 / Revised: 20 October 2018 / Accepted: 23 October 2018 / Published: 1 November 2018
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Abstract
(1) Background: The environmentally friendly choline-amino acid ionic liquids (ChAAILs) and deep eutectic solvents (DESs) have been used as excellent alternatives to volatile organic compounds (VOCs) and ionic liquids (ILs) in recent years; (2) Methods: Thus, ChAAILs/salt and DESs/salt aqueous two-phase systems (ATPSs)
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(1) Background: The environmentally friendly choline-amino acid ionic liquids (ChAAILs) and deep eutectic solvents (DESs) have been used as excellent alternatives to volatile organic compounds (VOCs) and ionic liquids (ILs) in recent years; (2) Methods: Thus, ChAAILs/salt and DESs/salt aqueous two-phase systems (ATPSs) were developed for the chiral extraction of phenylalanine enantiomers. The optimum ATPS of [Ch][L-Pro]/K3PO4 was chosen, and the influencing parameters were investigated, including ChAAILs concentration, salt concentration, chiral selector concentration, extraction temperature, phenylalanine concentration, and system pH; (3) Results: The phenylalanine enantiomers were mainly extracted into the top phase (ChAAIL-rich phase), meanwhile, the (S)-phenylalanine [(S)-Phe)] was preferentially recognized by the chiral selector in the top phase. The maximum separation factor (α) of 2.05 was obtained under the optimal conditions; and (4) Conclusions: This ATPS that was used for the chiral extraction of enantiomers is much more environmentally friendly, simple, and rapid, and has the potential to be used in the enantioselective extraction of other enantiomers. Full article
(This article belongs to the Section Chemical Systems)
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Open AccessArticle Experimental Development Process of a New Fluid–Solid Coupling Similar-Material Based on the Orthogonal Test
Processes 2018, 6(11), 211; https://doi.org/10.3390/pr6110211
Received: 27 September 2018 / Revised: 23 October 2018 / Accepted: 24 October 2018 / Published: 1 November 2018
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Abstract
Similar-material, composed of different raw materials with different properties, is similar to the physical and mechanical properties of geotechnical media, in which raw material proportioning is an important means to control the performance of similar-material in physical simulation. On this basis, a new
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Similar-material, composed of different raw materials with different properties, is similar to the physical and mechanical properties of geotechnical media, in which raw material proportioning is an important means to control the performance of similar-material in physical simulation. On this basis, a new fluid–solid coupling similar-material was developed through proportioning tests, in which similar-material is mixed with river sand, calcium carbonate, talc powder, white cement, vaseline, antiwear hydraulic oil. The optimum proportioning test development process was established. First, the proportioning test scheme was designed based on the orthogonal test. Subsequently, test specimens were produced to obtain parameters such as density, compressive strength, tensile strength, and permeability coefficient. Then, by increasing the ingredients of the proportioning, the evolution law of parameters was obtained by range and variance analysis. Finally, four multiple linear regression equations between the parameters and similar-material ingredients were obtained, and the optimum proportioning of ingredients was further determined for different requirements. The results indicate that the selected raw materials and their proportioning method are feasible, and the results were also verified in a coal mine floor water inrush by physical simulation test. The experimental development process of a fluid–solid coupling similar-material can provide a reference for similar-material under different demand conditions. Full article
(This article belongs to the Special Issue Fluid Flow in Fractured Porous Media)
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Open AccessArticle High Mixing Efficiency by Modulating Inlet Frequency of Viscoelastic Fluid in Simplified Pore Structure
Processes 2018, 6(11), 210; https://doi.org/10.3390/pr6110210
Received: 26 September 2018 / Revised: 15 October 2018 / Accepted: 16 October 2018 / Published: 1 November 2018
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Abstract
Fluid mixing plays an essential role in microscale flow systems. Here, we propose an active mixing approach which enhances the mixing of viscoelastic fluid flow in a simplified pore T-junction structure. Mixing is actively controlled by modulating the driving pressure with a sinusoidal
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Fluid mixing plays an essential role in microscale flow systems. Here, we propose an active mixing approach which enhances the mixing of viscoelastic fluid flow in a simplified pore T-junction structure. Mixing is actively controlled by modulating the driving pressure with a sinusoidal signal at the two inlets of the T-junction. The mixing effect is numerically investigated for both Newtonian and viscoelastic fluid flows under different pressure modulation conditions. The result shows that a degree of mixing as high as 0.9 is achieved in viscoelastic fluid flows through the T-junction mixer when the phase difference between the modulated pressures at the two inlets is 180°. This modulation method can also be used in other fluid mixing devices. Full article
(This article belongs to the Special Issue Fluid Flow in Fractured Porous Media)
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Open AccessArticle Local Fixed Pivot Quadrature Method of Moments for Solution of Population Balance Equation
Processes 2018, 6(11), 209; https://doi.org/10.3390/pr6110209
Received: 16 September 2018 / Revised: 18 October 2018 / Accepted: 25 October 2018 / Published: 31 October 2018
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Abstract
A local fixed pivot quadrature method of moments (LFPQMOM) is proposed for the solution of the population balance equation (PBE) for the aggregation and breakage process. First, the sectional representation for aggregation and breakage is presented. The continuous summation of the Dirac Delta
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A local fixed pivot quadrature method of moments (LFPQMOM) is proposed for the solution of the population balance equation (PBE) for the aggregation and breakage process. First, the sectional representation for aggregation and breakage is presented. The continuous summation of the Dirac Delta function is adopted as the discrete form of the continuous particle size distribution in the local section as performed in short time Fourier transformation (STFT) and the moments in local sections are tracked successfully. Numerical simulation of benchmark test cases including aggregation, breakage, and aggregation breakage combined processes demonstrate that the new method could make good predictions for the moments along with particle size distribution without further assumption. The accuracy in the numerical results of the moments is comparable to or higher than the quadrature method of moment (QMOM) in most of the test cases. In theory, any number of moments can be tracked with the new method, but the computational expense can be relatively large due to many scalar equations that may be included. Full article
(This article belongs to the Special Issue Recent Advances in Population Balance Modeling)
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Open AccessFeature PaperArticle Optimal Design of a Two-Stage Membrane System for Hydrogen Separation in Refining Processes
Processes 2018, 6(11), 208; https://doi.org/10.3390/pr6110208
Received: 17 September 2018 / Revised: 27 October 2018 / Accepted: 27 October 2018 / Published: 31 October 2018
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Abstract
This paper fits into the process system engineering field by addressing the optimization of a two-stage membrane system for H2 separation in refinery processes. To this end, a nonlinear mathematical programming (NLP) model is developed to simultaneously optimize the size of each
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This paper fits into the process system engineering field by addressing the optimization of a two-stage membrane system for H2 separation in refinery processes. To this end, a nonlinear mathematical programming (NLP) model is developed to simultaneously optimize the size of each membrane stage (membrane area, heat transfer area, and installed power for compressors and vacuum pumps) and operating conditions (flow rates, pressures, temperatures, and compositions) to achieve desired target levels of H2 product purity and H2 recovery at a minimum total annual cost. Optimal configuration and process design are obtained from a model which embeds different operating modes and process configurations. For instance, the following candidate ways to create the driving force across the membrane are embedded: (a) compression of both feed and/or permeate streams, or (b) vacuum application in permeate streams, or (c) a combination of (a) and (b). In addition, the potential selection of an expansion turbine to recover energy from the retentate stream (energy recovery system) is also embedded. For a H2 product purity of 0.90 and H2 recovery of 90%, a minimum total annual cost of 1.764 M$·year−1 was obtained for treating 100 kmol·h−1 with 0.18, 0.16, 0.62, and 0.04 mole fraction of H2, CO, N2, CO2, respectively. The optimal solution selected a combination of compression and vacuum to create the driving force and removed the expansion turbine. Afterwards, this optimal solution was compared in terms of costs, process-unit sizes, and operating conditions to the following two sub-optimal solutions: (i) no vacuum in permeate stream is applied, and (ii) the expansion turbine is included into the process. The comparison showed that the latter (ii) has the highest total annual cost (TAC) value, which is around 7% higher than the former (i) and 24% higher than the found optimal solution. Finally, a sensitivity analysis to investigate the influence of the desired H2 product purity and H2 recovery is presented. Opposite cost-based trade-offs between total membrane area and total electric power were observed with the variations of these two model parameters. This paper contributes a valuable decision-support tool in the process system engineering field for designing, simulating, and optimizing membrane-based systems for H2 separation in a particular industrial case; and the presented optimization results provide useful guidelines to assist in selecting the optimal configuration and operating mode. Full article
(This article belongs to the Special Issue Membrane Materials, Performance and Processes)
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Open AccessFeature PaperArticle Eden Model Simulation of Re-Epithelialization and Angiogenesis of an Epidermal Wound
Processes 2018, 6(11), 207; https://doi.org/10.3390/pr6110207
Received: 31 July 2018 / Revised: 28 September 2018 / Accepted: 23 October 2018 / Published: 25 October 2018
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Abstract
Among the vital processes of cutaneous wound healing are epithelialization and angiogenesis. The former leads to the successful closure of the wound while the latter ensures that nutrients are delivered to the wound region during and after healing is completed. These processes are
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Among the vital processes of cutaneous wound healing are epithelialization and angiogenesis. The former leads to the successful closure of the wound while the latter ensures that nutrients are delivered to the wound region during and after healing is completed. These processes are regulated by various cytokines and growth factors that subtend their proliferation and migration into the wound region until full healing is attained. Wound epithelialization can be enhanced by the administration of epidermal stem cells (ESC) or impaired by the presence of an infection. This paper uses the Eden model of a growing cluster to independently simulate the processes of epithelialization and angiogenesis in a cutaneous wound for different geometries. Further, simulations illustrating bacterial infection are provided. Our simulation results demonstrate contraction and closure for any wound geometry due to a collective migration of epidermal cells from the wound edge in fractal form and the diffusion of capillary sprouts with the laying down of capillary blocks behind moving tips into the wound area. Full article
(This article belongs to the Special Issue Systems Biomedicine)
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Open AccessArticle Optimization of Microwave-Assisted Extraction of Essential Oil from Vietnamese Basil (Ocimum basilicum L.) Using Response Surface Methodology
Processes 2018, 6(11), 206; https://doi.org/10.3390/pr6110206
Received: 27 September 2018 / Revised: 16 October 2018 / Accepted: 23 October 2018 / Published: 25 October 2018
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Abstract
Basil plant is a common source for linalool and estragole. However, it has been showed that the chemical composition of basil varies considerably depending on many factors including method of extraction, cultivar of the plant or geographical location. In this study, we attempted
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Basil plant is a common source for linalool and estragole. However, it has been showed that the chemical composition of basil varies considerably depending on many factors including method of extraction, cultivar of the plant or geographical location. In this study, we attempted to extract essential oil from Vietnamese basil and analyze the chemical composition of the obtained oil using gas chromatography–mass spectrometry (GC-MS). The extraction method of choice was microwave-assisted hydro-distillation (MAHD) and the process was optimized with Response Surface Methodology (RSM) with regard to four experimental parameters including raw material size, raw material to water ratio, extraction time and microwave power. The results showed that ground basil leaves, when extracted with optimal conditions of water-to-material ratio of 3.2:1, extraction time of 97 (min) and microwave power of 430 (W), gave the actual essential oil yield of 0.6%. Regarding ANOVA results of the quadratic model, high determination coefficient (R2 = 0.9077), significant F-value of 10.92 and the p-value of less than 0.05 indicate that this model is significant between experimental and predicted variables, and should be fixed. In addition, GC-MS analysis revealed that major components of Vietnamese Basil were Estragole (87.869%), α-Bergamotene (2.922%), τ-Cadinol (2.770%), and Linalool (1.347%). Full article
(This article belongs to the Special Issue Microwave Applications in Chemical Engineering)
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Open AccessFeature PaperArticle Regeneration of Sodium Hydroxide from a Biogas Upgrading Unit through the Synthesis of Precipitated Calcium Carbonate: An Experimental Influence Study of Reaction Parameters
Processes 2018, 6(11), 205; https://doi.org/10.3390/pr6110205
Received: 11 October 2018 / Revised: 18 October 2018 / Accepted: 22 October 2018 / Published: 24 October 2018
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Abstract
This article presents a regeneration method of a sodium hydroxide (NaOH) solution from a biogas upgrading unit through calcium carbonate (CaCO3) precipitation as a valuable by-product, as an alternative to the elevated energy consumption employed via the physical regeneration process. The
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This article presents a regeneration method of a sodium hydroxide (NaOH) solution from a biogas upgrading unit through calcium carbonate (CaCO3) precipitation as a valuable by-product, as an alternative to the elevated energy consumption employed via the physical regeneration process. The purpose of this work was to study the main parameters that may affect NaOH regeneration using an aqueous sodium carbonate (Na2CO3) solution and calcium hydroxide (Ca(OH)2) as reactive agent for regeneration and carbonate slurry production, in order to outperform the regeneration efficiencies reported in earlier works. Moreover, Raman spectroscopy and Scanning Electron Microscopy (SEM) were employed to characterize the solid obtained. The studied parameters were reaction time, reaction temperature, and molar ratio between Ca(OH)2 and Na2CO3. In addition, the influence of small quantities of NaOH at the beginning of the precipitation process was studied. The results indicate that regeneration efficiencies between 53%–97% can be obtained varying the main parameters mentioned above, and also both Raman spectroscopy and SEM images reveal the formation of a carbonate phase in the obtained solid. These results confirmed the technical feasibility of this biogas upgrading process through CaCO3 production. Full article
(This article belongs to the Special Issue Gas Capture Processes)
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