Modeling and simulation of a beet pulp dryer for a training simulator

This paper deals with the modeling of a high-temperature rotatory sugar beet pulp dryer for training simulators. This model adds some aspects to traditional drum dryer models; particle size distribution, detailed modeling of the solid phase, and the inclusion of malfunctions in the model. An object-oriented simulation package is selected to implement this model in a library, together with models of other components of a drying plant. Using this library, the complete plant and its control system are built and simulated. Finally, the simulation of the plant integrated together with a SCADA makes up the training simulator.     

燃料乙醇系统模拟平台开发及应用

对典型燃料乙醇系统进行了分析,阐述了目前该系统相关全流程模拟模型的不足以及由非线性和复杂性等特征导致的系统建模难点。在此基础上,运用VC#编程工具和SQLSERVE开发了全新的燃料乙醇系统模拟平台,该平台可模拟燃料乙醇实际生产过程,能够从物质流、能量流、水流、价值流等方面对系统开展工业生态学分析。最后利用实际生产过程中出现的两个问题案例对平台进行了检验。     

气流床气化仿真培训系统开发与应用

采用过程系统仿真平台开发多喷嘴气化炉仿真培训系统,模拟多喷嘴对置式煤气化装置运行过程,通过分析实际生产装置,建立数学模型,采用序贯模块法搭建气化流程模型,成功模拟了开车、停车、典型故障处理等工况,并开发了在线评价系统,为多喷嘴对置式煤气化技术的进一步推广应用提供了良好的仿真培训平台。     

Can simulation technology enable a paradigm shift in process control?: Modeling for the rest of us

Commercial process simulation software makes it easy for experts to develop very complex models with thousands of equations. But how well are these models used? Remember the admonition of Box [Box, G. E. P. (1979). Robustness in scientific model building. In R. L. Launer & G. N. Wilkinson (Eds.), Robustness in statistics (pp. 201–236). New York: Academic Press], “All models are wrong, but some are useful”. Are case runs just captured in a report and then filed away? Is the expert the only one who can run additional cases? We believe that process dynamics simulation should be ubiquitous in chemical engineering practice and education. Undergraduate engineers should experience unit operations through a virtual process simulator. In industry, engineers must be able to quickly build dynamic models to study operability and design control strategies. We feel that DuPont has undergone a paradigm shift where engineers are much more likely to use dynamic simulation as part of their day-to-day work. This paper illustrates some of the features that process dynamic simulators need to enable this paradigm shift.     

Design of different bioreactor configurations: application to ligninolytic enzyme production in semi‐solid‐state cultivation

The production of ligninolytic enzymes by Phanerochaete chrysosporium BKM‐F‐1767 (ATCC 24725) in laboratory‐scale bioreactors was studied. The cultivations were carried out in semi‐solid‐state conditions, employing corncob as carrier, which functioned both as a place of attachment and as a source of nutrients. Several bioreactor configurations were investigated in order to determine the most suitable one for ligninolytic enzyme production: a 1‐dm³‐static‐bed bioreactor, a 1‐dm³‐static‐bed bioreactor with air diffusers into the bed, a 0.5‐dm³‐static‐bed bioreactor with air diffusers into the bed and a tray bioreactor. Although the static‐bed configurations produced maximum individual lignin peroxidase (LiP) activities about 400 U dm⁻³ (1.0‐dm³ bioreactor) and about 700 U dm⁻³ (0.5‐dm³ bioreactor), manganese‐dependent peroxidase (MnP) was not detected throughout the cultures. Nevertheless, the tray configuration led to maximum individual MnP and LiP activities of about 200 U dm⁻³ and 300 U dm⁻³, respectively. Therefore, this configuration is the most adequate of the different bioreactor configurations tested in the present work, since the ligninolytic complex formed by MnP and LiP is more efficient for its application to bio‐processing systems. In addition, the results indicated the influence of the oxygen in ligninolytic enzyme production. © 2001 Society of Chemical Industry     

Operator training simulators for biorefineries: current position and future directions

Recent technological advances in the development of alternative energy sources, including biofuels, for transportation and energy requirements have demonstrated the need for highly skilled engineers and operators in the biotechnological industries. Although operator training simulators (OTS) used in the traditional chemical process industries may be used to train biorefinery operators and engineers, several distinct aspects of bioprocess operations make their direct application limited. The development and deployment of OTSs for use in biotechnological processes is therefore beginning to gain increasing attention. This review paper examines the present status of OTS development and use in biorefineries, including future considerations on how an OTS may be used to improve operator competence, maximise biorefinery operational efficiencies and protect people and the environment. The general premise of an OTS is that model‐based operator training simulators can be used to verifiably enhance the training of industrial operators to run complex biorefineries. Only a few examples of the design and application of OTSs in large‐scale biorefineries have so far been reported. A discussion of the mathematical models used for OTS development is briefly presented, as well as available OTS design frameworks and vendors, including their benefits and drawbacks. The review concludes by looking at possible future directions of OTS development and use in biorefineries and their contribution in facilitating the transition to a bio‐based economy. © 2018 Society of Chemical Industry     

Bipolar membrane electrodialysis for clean production of L-10-camphorsulfonic acid: From laboratory to industrialization

In this study, bipolar membrane electrodialysis (BMED) was implemented for cleaner production of L-10-camphorsulfonic acid (L-CSA) to lower the environmental impact. Under the current density of 300–400 A/m² and feed salt concentration of 6–10 wt.%, the energy consumption and current efficiency were 2.24–2.70 kWh/kg and 20.89–29.5%, respectively. Positron annihilation lifetime spectroscopy, x-ray photoelectron spectroscopy with ion beam etching, and other characterizations were used to elucidate the transport behaviors of large-sized anions across the membranes. It was speculated that the large-sized camphor sulfonate ions were more likely to deposit on the surface of the anion-exchange membrane to form a deposition layer under a direct current electric field. The appearance of water splitting at this deposition layer would offset the water dissociation in the bipolar membrane. Nevertheless, the successful commissioning of industrial-scale stack proved the feasibility and sustainability of BMED technique for a closed loop L-CSA production.     

蒸汽渗透技术在燃料乙醇生产中的应用研究进展

蒸汽渗透作为一种新型膜分离技术,可有效解决生物燃料乙醇生产中发酵产物浓度低、能源消耗量大、污染环境等诸多瓶颈问题。与渗透蒸发相比,蒸汽渗透技术具有分离性能好、进料清洁、能量损耗低、操作弹性大等优点,在燃料乙醇生产领域具备更广阔的应用前景。本文在比较渗透蒸发和气体分离技术的基础上,简述了蒸汽渗透过程的机理和特点。介绍了优先透水膜和优先透醇膜两类应用于燃料乙醇生产不同阶段的蒸汽渗透膜和这两类膜材料当前的研究进展,重点阐述了有机/无机杂化膜在成膜方法、杂化材料选择等方面的最新成果。回顾了蒸汽渗透在乙醇脱水方面的工业应用成果,指出该技术在发酵原位分离乙醇和替代精馏工艺方面所具有的优势,探讨了与固态发酵技术相结合进行一次相变生产燃料乙醇工艺实现的可能性,并提出未来亟待研究和解决的问题,为蒸汽渗透技术在燃料乙醇生产领域大规模发展提供参考。     

CFD simulation and optimization of effective parameters for biomass production in a horizontal tubular loop bioreactor

The focus of the current study was to perform an experimental investigation and computational fluid dynamic (CFD) simulation of flow hydrodynamics in a forced-liquid horizontal tubular loop bioreactor for the production of biomass. The simulations were performed using the FLUENT commercial CFD package, a segregated unsteady solver and a two-phase Eulerian multiphase model. To validate the simulation results, several experiments were performed in a pilot bioreactor. In addition, the design of experiments methodology using a Taguchi orthogonal array (OA) was applied to evaluate the influence of four factors on the hydrodynamic behavior of the bioreactor. The effective parameters considered for optimization were air inlet velocity, liquid inlet velocity, bubble diameter, and viscosity. An L₉ OA was used to conduct the Taguchi experiments to study the significance of these parameters and the possible effects of any two-factor interactions. The optimum conditions and most significant process parameters affecting the hydrodynamic behavior were determined using an analysis of variance model. The results showed that the liquid inlet velocity had the most influence on the air volume fraction in the bioreactor. A subsequent confirmatory test demonstrated that the results were within the confidence interval.     

基于虚拟现实和多媒体的硫酸生产过程仿真培训系统的研究

论述了虚拟现实和多媒体技术的主要特征及技术组成，研究了硫酸生产过程的仿真培训系统与虚拟现实、多媒体技术的关系，基于虚拟现实和多媒体技术的硫酸生产仿真培训系统具有人机交互自然性、信息处理多样性、虚拟环境真实性等优点，研究和开发此系统具有十分重要的意义。     

迭代遗传算法及其用于生物反应器补料优化

针对化工动态优化的数值求解问题,提出将迭代思想与遗传操作相结合,构建迭代遗传算法.算法首先对时间区间和控制搜索域实施离散化,进而应用遗传操作搜索离散问题的最优控制策略.逐步收缩搜索域并迭代以消减离散化带来的偏差,不断改善寻优结果,增强算法的稳健性.实例测试表明该算法简便、可行、高效,已成功地应用于Lee-Ramirez生物反应器补料流率的优化,运算结果优于文献值,显示了迭代遗传算法的优越性.迭代遗传算法尤其适用于系统的梯度信息不可得的情况.     

Toxicity-based selection of Escherichia coli mutants for functional recombinant protein production: application to an antibody fragment

We propose a novel approach to the selection of Escherichia coli bacterial strains improved for the production of recombinant functional proteins. This approach is based on aggregation-induced toxicity of recombinant proteins. We show that selection of clones displaying a reduced toxicity is an efficient means of isolating bacteria producing recombinant protein with reduced aggregation in favour of correct folding. For an efficient selection, we found that time of toxicity induction must be precisely determined and recombinant protein must be expressed as a fusion with a protein whose activity is easily detectable on plates, thus allowing elimination of non-productive mutants. Choosing the expression to the periplasmic space of an scFv fragment fused to the N-terminus of alkaline phosphatase as a model, we selected chromosomal mutations that reduce aggregation-induced toxicity and showed that they concomitantly improve production of a functional recombinant hybrid. The effects of the mutations isolated could then be cumulated with those of other strategies used for recombinant scFv production. Thus, we could ensure a 6- to 16-fold increase in production of a functional scFv-PhoA hybrid. This is the first report demonstrating the possibility of directly selecting on agar plates E.coli strains improved for functional recombinant protein production from a large bacterial mutant library.     

Product diversification to enhance economic viability of second generation ethanol production in Brazil: The case of the sugar and ethanol joint production

Commercial simulator Aspen Plus^® was used to simulate the conventional processes of the autonomous distillery producing ethanol and the joint production of sugar and ethanol. Changes in conventional processes were evaluated to increase electricity and second generation ethanol production using bagasse fine fraction composed by parenchyma cells (P-fraction). The evaluated processes were thermal and water integrated. The results indicated that the integration of the second generation process to the conventional processes was possible after thermal and water integration. The economic analysis showed that the second generation process integrated to the joint production presented lower payback time, 2.3 years, in comparison with this process integrated to the autonomous distillery, 4.7 years. Due to the high enzyme costs, the cases without second generation ethanol production presented higher economic viability. Product diversification, as sugar and ethanol production in the same site, lowered the impact of enzymes cost on the payback time of second generation process, showing that the integration of the second generation ethanol production process to the conventional sugar production process could be a step to cellulosic ethanol production feasibility in sugarcane mills.     

Studies on fermentation with recombinant yeast cells: plasmid stability and kinetics of biomass and protein production

Plasmid stability of the recombinant Saccharomyces cerevisiae YPB‐G strain harbouring a YEp plasmid with α‐amylase and glucoamylase genes as a fusion has been investigated in shake flasks and in a bioreactor using various compositions of media containing glucose or starch as the main carbon source. The medium composition affected both the growth characteristics and the stability of the plasmid. Superior plasmid stability was obtained in yeast minimal medium and in complex medium with glucose. Plasmid stability was substantially increased at high growth rates. Additional data were collected in the same system to investigate the kinetic characteristics of biomass and protein production, and unstructured kinetic models were used to interpret the results. At high initial glucose concentrations, where the biomass and protein production rates were similar, the kinetic models displayed good fits associated with high degrees of correlation. © 2000 Society of Chemical Industry     

The energy landscape for protein folding and possible connections to function

In this article we review and discuss the state-of-the-art methods using minimalist models in the context of energy landscape theory to study protein folding. As good agreement between computational/theoretical studies and experimental observations in vitro continues to emerge, many research groups are asking how this structural and dynamical information can be used to understand proteins in vivo. This is a non-trivial question drawing from very limited in vivo studies. From the perspective of theory, it is a new horizon for theoreticians to test or revise their theories by making connections to experiments on this matter. We present a short discussion of several recent efforts that include factors reflecting the cellular environment in computer simulations—and that may provide some insight into the behavior of protein dynamics inside the living cell as well as inspire the development of new experimental approaches for a better understanding of the molecular mechanisms for function.     

A tubular bioreactor for photosynthetic production of biomass from carbon dioxide: Design and performance

A theory of photobioreactor design is developed. A photobioreactor was constructed in the form of a loop made from 52 m of glass tubing of 1 cm bore; the loop covered about 0.5 m². The culture was illuminated with mercury halide lamps to reproduce sunlight. Computer control was used to maintain constant biomass concentration. The influence of radiation on the reactor temperature is quantitatively predicted. An air lift system was preferred to a liquid pump for culture recycle. The energy required for culture recycle in the loop with Reynolds number 2000 was 0.6 W m^?2. The CO₂ gas/liquid transfer rate achieved was sufficient to meet the maximum possible demand with solar irradiation. The O₂ gas/liquid transfer rate was sufficient to meet the maximum respiration demand at night. The maximum algal biomass concentration achieved exceeded 20 g dry weight litre^?1. A biomass concentration of 8 g dry weight litre^?1 was found to be convenient for normal operation. The maximum uptake of light in the available wavelength range (400–700 nm) was 38 W m^?2, this corresponds to utilisation of solar irradiation up to 89 W m^?2. Below the maximum light uptake rate the efficiency of storage of light energy in the biomass corresponded to 16.6% of solar energy.     

A bioprocessing mode for simultaneous fungal biomass protein production and wastewater treatment using an external air‐lift bioreactor

A pilot plant investigation for bioprocessing has been undertaken to develop a simple, non‐aseptic, low‐cost single process for production of fungal biomass protein (FBP) and wastewater treatment using starch processing wastewater. It has been confirmed that the newly developed external air‐lift bioreactor was very suitable for bioconversion of starch materials and FBP production by the microfungi Aspergillus oryzae and Rhizopus arrhizus. Bioproduct yields of 8.5 g dm^?3 of FBP that contained 46–50% protein were obtained within a comparatively short retention time. A fungal biomass productivity in a range of 0.85–0.92 g dm^?3 h^?1 and removals of total suspended solids and 95% COD were achieved in batch, semi‐continuous and continuous processes. The operation modes of the semi‐continuous and continuous processes demonstrated a high biological dynamics in fungal biomass productivity and COD reduction. The semi‐continuous process appeared to be the most practical mode. © 2001 Society of Chemical Industry     

Multiscale simulation of nutrient transport in hollow fibre membrane bioreactor for growing bone tissue: Sub-cellular scale and beyond

Recent experimental studies suggest that hollow fibre membrane bioreactors (HFMBs) may be used to grow 3-D bone tissues in the laboratory, which may then be implanted into patients to repair skeletal defects. The HFMBs mimic the capillary network that exists in bones and are very effective in supplying nutrients to cells (to maintain cell metabolism) and removing waste products (e.g., excreta from micro-organisms, etc.). In order to guide the design of HFMBs for bone tissue engineering, it is necessary to elucidate the quantitative relationships between the cell environment and tissue behaviour in HFMBs and their relationship with nutrient supply. However, the nutrient transport processes in these bioreactors depend on several scales: from the scale of the individual cell to the scale of the bioreactors (laboratory scale). Further, the significance of the mass transfer processes is different from one scale to another. At the sub-cellular scale (i.e., within individual cell), the transport processes are dominated by diffusive-reaction mechanisms. At the extracellular matrix, these processes are primarily diffusion dominated. The transport of nutrients in the capillary network is convection dominated. At the scale of the laboratory device, the transport behaviour is governed by non-linear coupled convection-diffusion and reaction processes. Therefore, to characterise the ‘overall’ nutrient transfer processes and function of the HFMB, one needs an understanding of the processes at the smaller scale (e.g., sub-cellular scale) and their manifestation at larger scale, such as the bioreactor.This paper presents an approach for modelling and simulating nutrient transport in HFMB for growing bone tissues where the separations of scales from individual cell to the scales of bioreactor are considered. We use direct numerical simulation (finite element method) instead of more tedious applied mathematics based upscaling theorems for modelling nutrient transport in HFMB. The advantage of this approach is that it does not rely on the determination of averaged transport properties (e.g., diffusion coefficient) that appear in averaged transport equations which are often difficult to measure experimentally or may not have significant physical meaning. In this paper, the developed computational framework is used to upscale the mass transfer processes at sub-cellular scale to the scale of HFMB (laboratory scale). The developed framework is then employed to carry out a systematic analysis of the influence of various process parameters of HFMB (e.g., fluid velocity, cell density, cellular size, etc.) on the nutrient transport behaviour. It is envisaged that the developed multiscale tool will provide better understanding of the functioning of HFMB for the purposes discussed above.     

KBR (Kinetics in Batch Reactors): a MATLAB-based application with a friendly Graphical User Interface for chemical kinetic model simulation and parameter estimation

The simulation of chemical kinetic models is necessary in order to analyze comprehensive chemical reaction mechanisms and perform the estimation of the kinetic parameters. In many cases, a chemical process can be composed of several series and/or independent reactions that requires a complex set of kinetic equations to be solved. Computer-based tools for the study of kinetics of chemical reaction networks have been used since the last 50 years. However, the educational tools in this field should be friendly for the user and easy to learn and adapt to practical cases, avoiding long frustrating learning curves. Herein, the main objective of this contribution is to present a Matlab® application for the evaluation of Kinetics in Batch Reactors (KBR), which will help students to estimate kinetic parameters of complex chemical reaction models. The KBR application was used in the Final Degree Projects of Chemical Engineering and Environmental Engineering Degrees at Rey Juan Carlos University (Spain). This application provides a friendly Graphical User Interface to formulate any kind of kinetic model for subsequent simulation in order to monitor the evolution of reagents and products along the reaction time. Moreover, the student will be able to estimate kinetic parameters according to available experimental data as well as to apply sensitivity analysis of those parameters for particular cases of chemical reactions in batch systems. Finally, the results can be exported for further analysis as a spreadsheet of an Excel® file (.xlsx).