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Processes, Volume 4, Issue 3 (September 2016)

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Editorial

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Open AccessEditorial Special Issue “Polymer Modeling, Control and Monitoring” of Processes
Processes 2016, 4(3), 24; doi:10.3390/pr4030024
Received: 25 July 2016 / Revised: 25 July 2016 / Accepted: 25 July 2016 / Published: 29 July 2016
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Abstract Polymers range from synthetic plastics, such as polyacrylates, to natural biopolymers, such as proteins and DNA.[...] Full article
(This article belongs to the Special Issue Polymer Modeling, Control and Monitoring) Printed Edition available

Research

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Open AccessArticle Incorporating Enhanced Decision-Making Capabilities into a Hybrid Simulator for Scheduling of Batch Processes
Processes 2016, 4(3), 30; doi:10.3390/pr4030030
Received: 18 May 2016 / Revised: 23 July 2016 / Accepted: 30 August 2016 / Published: 2 September 2016
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Abstract
A simulation model can accurately capture the details of product recipes in a batch process. By incorporating enhanced capabilities for making key assignment decisions in the simulation executive a model can mimic the experiential knowledge and rules employed in operating a process. As
[...] Read more.
A simulation model can accurately capture the details of product recipes in a batch process. By incorporating enhanced capabilities for making key assignment decisions in the simulation executive a model can mimic the experiential knowledge and rules employed in operating a process. As the process complexity and problem size increase using the mathematical programming (MP) techniques to generate schedules becomes increasingly difficult. A simulation run typically takes very little computation time and generates a schedule that is verifiable. Moreover, the model can be used to explore a wide range of parametric space to evaluate alternate policies and the impact of process uncertainties. Although there is no guarantee of optimality, the quality of schedules thus generated is very good and can be deployed in operations. In this paper the decision-making capabilities of the BATCHES simulator are presented with its application to a set of scheduling problems reported extensively in the literature. The results show that ‘smart’ simulation can be used effectively for a large set of scheduling problems. Full article
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Open AccessFeature PaperArticle Parallel Solution of Robust Nonlinear Model Predictive Control Problems in Batch Crystallization
Processes 2016, 4(3), 20; doi:10.3390/pr4030020
Received: 6 May 2016 / Revised: 20 June 2016 / Accepted: 22 June 2016 / Published: 30 June 2016
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Abstract
Representing the uncertainties with a set of scenarios, the optimization problem resulting from a robust nonlinear model predictive control (NMPC) strategy at each sampling instance can be viewed as a large-scale stochastic program. This paper solves these optimization problems using the parallel Schur
[...] Read more.
Representing the uncertainties with a set of scenarios, the optimization problem resulting from a robust nonlinear model predictive control (NMPC) strategy at each sampling instance can be viewed as a large-scale stochastic program. This paper solves these optimization problems using the parallel Schur complement method developed to solve stochastic programs on distributed and shared memory machines. The control strategy is illustrated with a case study of a multidimensional unseeded batch crystallization process. For this application, a robust NMPC based on min–max optimization guarantees satisfaction of all state and input constraints for a set of uncertainty realizations, and also provides better robust performance compared with open-loop optimal control, nominal NMPC, and robust NMPC minimizing the expected performance at each sampling instance. The performance of robust NMPC can be improved by generating optimization scenarios using Bayesian inference. With the efficient parallel solver, the solution time of one optimization problem is reduced from 6.7 min to 0.5 min, allowing for real-time application. Full article
(This article belongs to the Special Issue Algorithms and Applications in Dynamic Optimization)
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Open AccessArticle Functional Properties of Punica granatum L. Juice Clarified by Hollow Fiber Membranes
Processes 2016, 4(3), 21; doi:10.3390/pr4030021
Received: 18 May 2016 / Revised: 4 July 2016 / Accepted: 4 July 2016 / Published: 15 July 2016
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Abstract
There is currently much interest in pomegranate juice because of the high content of phenolic compounds. Moreover, the interest in the separation of bioactive compounds from natural sources has remarkably grown. In this work, for the first time, the Punica granatum L. (pomegranate)
[...] Read more.
There is currently much interest in pomegranate juice because of the high content of phenolic compounds. Moreover, the interest in the separation of bioactive compounds from natural sources has remarkably grown. In this work, for the first time, the Punica granatum L. (pomegranate) juice—clarified by using polyvinylidene fluoride (PVDF) and polysulfone (PSU) hollow fiber (HF) membranes prepared in the laboratory—was screened for its antioxidant properties by using different in vitro assays, namely 2,2-diphenyl-1-picrylhydrazyl (DPPH), 2,2'-azino-bis-(3-ethylbenzothiazoline-6-sulphonic acid) (ABTS), Ferric Reducing Antioxidant Power (FRAP), and β-carotene bleaching tests, and for its potential inhibitory activity of the carbohydrate-hydrolysing enzymes, α-amylase and α-glucosidase. The effects of clarification on quality characteristics of the juice were also investigated in terms of total phenols, flavonoids, anthocyanins, and ascorbic acid. Experimental results indicated that PVDF membranes presented a lower retention towards healthy phytochemicals in comparison to PSU membranes. Accordingly, the juice clarified with PVDF membranes showed the best antioxidant activity. Moreover, the treatment with PVDF membranes produced a clarified juice with 2.9-times fold higher α-amylase inhibitory activity in comparison to PSU (IC50 value of 75.86 vs. 221.31 μg/mL, respectively). The same trend was observed using an α-glucosidase inhibition test. These results highlight the great potential of the clarified juice as a source of functional constituents. Full article
(This article belongs to the Special Issue Membrane Separation Processes)
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Open AccessFeature PaperArticle Comparison of Membrane Chromatography and Monolith Chromatography for Lactoferrin and Bovine Serum Albumin Separation
Processes 2016, 4(3), 31; doi:10.3390/pr4030031
Received: 13 July 2016 / Revised: 16 August 2016 / Accepted: 29 August 2016 / Published: 6 September 2016
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Abstract
These last few decades, membranes and monoliths have been increasingly used as stationary phases for chromatography. Their fast mass transfer is mainly based on convection, which leads to reduced diffusion, which is usually observed in resins. Nevertheless, poor flow distribution, which causes inefficient
[...] Read more.
These last few decades, membranes and monoliths have been increasingly used as stationary phases for chromatography. Their fast mass transfer is mainly based on convection, which leads to reduced diffusion, which is usually observed in resins. Nevertheless, poor flow distribution, which causes inefficient binding, remains a major challenge for the development of both membrane and monolith devices. Moreover, the comparison of membranes and monoliths for biomolecule separation has been very poorly investigated. In this paper, the separation of two proteins, bovine serum albumin (BSA) and lactoferrin (LF), with similar sizes, but different isoelectric points, was investigated at a pH of 6.0 with a BSA-LF concentration ratio of 2/1 (2.00 mg·mL−1 BSA and 1.00 mg·mL−1 LF solution) using strong cation exchange membranes and monoliths packed in the same housing, as well as commercialized devices. The feeding flow rate was operated at 12.0 bed volume (BV)/min for all devices. Afterward, bound LF was eluted using a phosphate-buffered saline solution with 2.00 M NaCl. Using membranes in a CIM housing from BIA Separations (Slovenia) with porous frits before and after the membrane bed, higher binding capacities, sharper breakthrough curves, as well as sharper and more symmetric elution peaks were obtained. The monolith and commercialized membrane devices showed lower LF binding capacity and broadened and non-symmetric elution peaks. Full article
(This article belongs to the Special Issue Membrane Separation Processes)
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Open AccessArticle Discrete Blood Glucose Control in Diabetic Göttingen Minipigs
Processes 2016, 4(3), 22; doi:10.3390/pr4030022
Received: 14 April 2016 / Revised: 5 July 2016 / Accepted: 13 July 2016 / Published: 22 July 2016
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Abstract
Despite continuous research effort, patients with type 1 diabetes mellitus (T1D) experience difficulties in daily adjustments of their blood glucose concentrations. New technological developments in the form of implanted intravenous infusion pumps and continuous blood glucose sensors might alleviate obstacles for the automatic
[...] Read more.
Despite continuous research effort, patients with type 1 diabetes mellitus (T1D) experience difficulties in daily adjustments of their blood glucose concentrations. New technological developments in the form of implanted intravenous infusion pumps and continuous blood glucose sensors might alleviate obstacles for the automatic adjustment of blood glucose concentration. These obstacles consist, for example, of large time-delays and insulin storage effects for the subcutaneous/interstitial route. Towards the goal of an artificial pancreas, we present a novel feedback controller approach that combines classical loop-shaping techniques with gain-scheduling and modern H -robust control approaches. A disturbance rejection design is proposed in discrete frequency domain based on the detailed model of the diabetic Göttingen minipig. The model is trimmed and linearised over a large operating range of blood glucose concentrations and insulin sensitivity values. Controller parameters are determined for each of these operating points. A discrete H loop-shaping compensator is designed to increase robustness of the artificial pancreas against general coprime factor uncertainty. The gain scheduled controller uses subcutaneous insulin injection as a control input and determines the controller input error from intravenous blood glucose concentration measurements, where parameter scheduling is achieved by an estimator of the insulin sensitivity parameter. Thus, only one controller stabilises a family of animal models. The controller is validated in silico with a total number of five Göttingen Minipig models, which were previously obtained by experimental identification procedures. Its performance is compared with an experimentally tested switching PI-controller. Full article
(This article belongs to the Special Issue Biomedical Systems Control)
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Open AccessFeature PaperArticle Pure Hydrogen Production in Membrane Reactor with Mixed Reforming Reaction by Utilizing Waste Gas: A Case Study
Processes 2016, 4(3), 33; doi:10.3390/pr4030033
Received: 5 July 2016 / Revised: 29 August 2016 / Accepted: 13 September 2016 / Published: 20 September 2016
Cited by 2 | PDF Full-text (1974 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
A rise in CO2 and other greenhouse gases’ concentration from gas refinery flares and furnaces in the atmosphere causes environmental problems. In this work, a new process was designed to use waste gas (flue gas and flare gas) of a domestic gas
[...] Read more.
A rise in CO2 and other greenhouse gases’ concentration from gas refinery flares and furnaces in the atmosphere causes environmental problems. In this work, a new process was designed to use waste gas (flue gas and flare gas) of a domestic gas refinery to produce pure hydrogen in a membrane reactor. In particular, the process foresees that the energy and CO2 content of flue gas can provide the heat of the mixed reforming reaction to convert flare gas into hydrogen. Furthermore, the characteristics of the feed stream were obtained via simulation. Then, an experimental setup was built up to investigate the performance of a membrane reactor allocating an unsupported dense Pd-Ag membrane at the mentioned conditions. In this regard, a Ni/CeO2 catalyst was loaded in the membrane reformer for mixed reforming reaction, operating at 450 °C, in a pressure range between 100 and 350 kPa and a gas hourly space velocity of around 1000 h−1. The experimental results in terms of methane conversion, hydrogen recovery and yield, as well as products’ compositions are reported. The best results of this work were observed at 350 kPa, where the MR was able to achieve about 64%, 52% and 50% for methane conversion, hydrogen yield and recovery, respectively. Furthermore, with the assistance of the experimental tests, the proposed process was simulated in the scaling up to calculate the needed surface area for MR in the domestic gas refinery. Full article
(This article belongs to the Special Issue Membrane Separation Processes)
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Open AccessFeature PaperArticle Development of Chemical Process Design and Control for Sustainability
Processes 2016, 4(3), 23; doi:10.3390/pr4030023
Received: 11 April 2016 / Revised: 14 June 2016 / Accepted: 19 July 2016 / Published: 25 July 2016
Cited by 2 | PDF Full-text (5257 KB) | HTML Full-text | XML Full-text
Abstract
This contribution describes a novel process systems engineering framework that couples advanced control with sustainability evaluation for the optimization of process operations to minimize environmental impacts associated with products, materials and energy. The implemented control strategy combines a biologically-inspired method with optimal control
[...] Read more.
This contribution describes a novel process systems engineering framework that couples advanced control with sustainability evaluation for the optimization of process operations to minimize environmental impacts associated with products, materials and energy. The implemented control strategy combines a biologically-inspired method with optimal control concepts for finding more sustainable operating trajectories. The sustainability assessment of process operating points is carried out by using the U.S. EPA’s Gauging Reaction Effectiveness for the ENvironmental Sustainability of Chemistries with a multi-Objective Process Evaluator (GREENSCOPE) tool that provides scores for the selected indicators in the economic, material efficiency, environmental and energy areas. The indicator scores describe process performance on a sustainability measurement scale, effectively determining which operating point is more sustainable if there are more than several steady states for one specific product manufacturing. Through comparisons between a representative benchmark and the optimal steady states obtained through the implementation of the proposed controller, a systematic decision can be made in terms of whether the implementation of the controller is moving the process towards a more sustainable operation. The effectiveness of the proposed framework is illustrated through a case study of a continuous fermentation process for fuel production, whose material and energy time variation models are characterized by multiple steady states and oscillatory conditions. Full article
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Open AccessArticle Crystallization in Emulsions: A Thermo-Optical Method to Determine Single Crystallization Events in Droplet Clusters
Processes 2016, 4(3), 25; doi:10.3390/pr4030025
Received: 21 June 2016 / Revised: 28 July 2016 / Accepted: 29 July 2016 / Published: 11 August 2016
Cited by 2 | PDF Full-text (3320 KB) | HTML Full-text | XML Full-text
Abstract
Delivery systems with a solid dispersed phase can be produced in a melt emulsification process. For this, dispersed particles are melted, disrupted, and crystallized in a liquid continuous phase (melt emulsification). Different to bulk crystallization, droplets in oil-in-water emulsions show individual crystallization behavior,
[...] Read more.
Delivery systems with a solid dispersed phase can be produced in a melt emulsification process. For this, dispersed particles are melted, disrupted, and crystallized in a liquid continuous phase (melt emulsification). Different to bulk crystallization, droplets in oil-in-water emulsions show individual crystallization behavior, which differs from droplet to droplet. Therefore, emulsion droplets may form liquid, amorphous, and crystalline structures during the crystallization process. The resulting particle size, shape, and physical state influence the application properties of these colloidal systems and have to be known in formulation research. To characterize crystallization behavior of single droplets in micro emulsions (range 1 µm to several hundred µm), a direct thermo-optical method was developed. It allows simultaneous determination of size, size distribution, and morphology of single droplets within droplet clusters. As it is also possible to differentiate between liquid, amorphous, and crystalline structures, we introduce a crystallization index, CIi, in dispersions with a crystalline dispersed phase. Application of the thermo-optical approach on hexadecane-in-water model emulsion showed the ability of the method to detect single crystallization events of droplets within emulsion clusters, providing detailed information about crystallization processes in dispersions. Full article
(This article belongs to the Special Issue Emulsification Processes)
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Open AccessFeature PaperArticle On the Use of Nonlinear Model Predictive Control without Parameter Adaptation for Batch Processes
Processes 2016, 4(3), 27; doi:10.3390/pr4030027
Received: 12 May 2016 / Revised: 19 August 2016 / Accepted: 22 August 2016 / Published: 29 August 2016
Cited by 1 | PDF Full-text (486 KB) | HTML Full-text | XML Full-text
Abstract
Optimization techniques are typically used to improve economic performance of batch processes, while meeting product and environmental specifications and safety constraints. Offline methods suffer from the parameters of the model being inaccurate, while re-identification of the parameters may not be possible due to
[...] Read more.
Optimization techniques are typically used to improve economic performance of batch processes, while meeting product and environmental specifications and safety constraints. Offline methods suffer from the parameters of the model being inaccurate, while re-identification of the parameters may not be possible due to the absence of persistency of excitation. Thus, a practical solution is the Nonlinear Model Predictive Control (NMPC) without parameter adaptation, where the measured states serve as new initial conditions for the re-optimization problem with a diminishing horizon. In such schemes, it is clear that the optimum cannot be reached due to plant-model mismatch. However, this paper goes one step further in showing that such re-optimization could in certain cases, especially with an economic cost, lead to results worse than the offline optimal input. On the other hand, in absence of process noise, for small parametric variations, if the cost function corresponds to tracking a feasible trajectory, re-optimization always improves performance. This shows inherent robustness associated with the tracking cost. A batch reactor example presents and analyzes the different cases. Re-optimizing led to worse results in some cases with an economical cost function, while no such problem occurred while working with a tracking cost. Full article
(This article belongs to the Special Issue Real-Time Optimization) Printed Edition available
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Open AccessArticle Electro- or Turbo-Driven?—Analysis of Different Blast Processes of Blast Furnace
Processes 2016, 4(3), 28; doi:10.3390/pr4030028
Received: 31 March 2016 / Revised: 20 August 2016 / Accepted: 23 August 2016 / Published: 29 August 2016
Cited by 1 | PDF Full-text (1455 KB) | HTML Full-text | XML Full-text
Abstract
There has always been a dispute about the energy efficiency and energy cost of electro-driven and turbo-driven blast furnace (BF) blast processes. In order to find where the problem lies, energy efficiency analysis models and energy cost analysis models of electro-driven and turbo-driven
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There has always been a dispute about the energy efficiency and energy cost of electro-driven and turbo-driven blast furnace (BF) blast processes. In order to find where the problem lies, energy efficiency analysis models and energy cost analysis models of electro-driven and turbo-driven blast processes were established, and the differences between the two driving processes in terms of theoretical minimum steam consumption, energy efficiency and energy cost were studied. The results showed that the theoretical minimum steam consumption of a blast process depends on steam thermodynamic properties and is unrelated to drive mode and drive process. A certain overlapped interval between electro-driven and turbo-driven blast processes in terms of energy efficiency exists. The equation for calculating the standard coal coefficient of steam was proposed, and the relationship to judge strengths and weaknesses of the two driving modes in terms of energy efficiency and energy cost was established. Finally, two companies were selected for case study research. The results led to different conclusions because of the differences between energy media in terms of standard coal coefficient and unit price. To select the best driving mode, plant-running conditions and energy prices of the region of operation in addition to other relevant factors should all be taken into account. Full article
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Review

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Open AccessFeature PaperReview Origins and Evolution of Inorganic-Based and MOF-Based Mixed-Matrix Membranes for Gas Separations
Processes 2016, 4(3), 32; doi:10.3390/pr4030032
Received: 30 June 2016 / Revised: 13 August 2016 / Accepted: 23 August 2016 / Published: 12 September 2016
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Abstract
Gas separation for industrial, energy, and environmental applications requires low energy consumption and small footprint technology to minimize operating and capital costs for the processing of large volumes of gases. Among the separation methods currently being used, like distillation, amine scrubbing, and pressure
[...] Read more.
Gas separation for industrial, energy, and environmental applications requires low energy consumption and small footprint technology to minimize operating and capital costs for the processing of large volumes of gases. Among the separation methods currently being used, like distillation, amine scrubbing, and pressure and temperature swing adsorption, membrane-based gas separation has the potential to meet these demands. The key component, the membrane, must then be engineered to allow for high gas flux, high selectivity, and chemical and mechanical stability at the operating conditions of feed composition, pressure, and temperature. Among the new type of membranes studied that show promising results are the inorganic-based and the metal-organic framework-based mixed-matrix membranes (MOF-MMMs). A MOF is a unique material that offers the possibility of tuning the porosity of a membrane by introducing diffusional channels and forming a compatible interface with the polymer. This review details the origins of these membranes and their evolution since the first inorganic/polymer and MOF/polymer MMMs were reported in the open literature. The most significant advancements made in terms of materials, properties, and testing conditions are described in a chronological fashion. Full article
(This article belongs to the Special Issue Membrane Separation Processes)
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Open AccessReview Recent Advances on Carbon Molecular Sieve Membranes (CMSMs) and Reactors
Processes 2016, 4(3), 29; doi:10.3390/pr4030029
Received: 13 July 2016 / Revised: 12 August 2016 / Accepted: 13 August 2016 / Published: 31 August 2016
Cited by 2 | PDF Full-text (2981 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
Carbon molecular sieve membranes (CMSMs) are an important alternative for gas separation because of their ease of manufacture, high selectivity due to molecular sieve separation, and high permeance. The integration of separation by membranes and reaction in only one unit lead to a
[...] Read more.
Carbon molecular sieve membranes (CMSMs) are an important alternative for gas separation because of their ease of manufacture, high selectivity due to molecular sieve separation, and high permeance. The integration of separation by membranes and reaction in only one unit lead to a high degree of process integration/intensification, with associated benefits of increased energy, production efficiencies and reduced reactor or catalyst volume. This review focuses on recent advances in carbon molecular sieve membranes and their applications in membrane reactors. Full article
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Other

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Open AccessCorrection Correction: Study of n-Butyl Acrylate Self-Initiation Reaction Experimentally and via Macroscopic Mechanistic Modeling Processes 2016, 4, 15
Processes 2016, 4(3), 26; doi:10.3390/pr4030026
Received: 8 August 2016 / Revised: 10 August 2016 / Accepted: 10 August 2016 / Published: 16 August 2016
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Abstract We wish to correct Table 5 of the published paper in Processes [1].[...] Full article
(This article belongs to the Special Issue Polymer Modeling, Control and Monitoring) Printed Edition available

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