SustainPro—A tool for systematic process analysis,generation and evaluation of sustainable design alternatives

Chemical processes are continuously facing challenges from the demands of the global market related to economics, environment and social issues. This paper presents the development of a software tool (SustainPro) and its application to chemical processes operating in batch or continuous modes. The software tool is based on the implementation of an extended systematic methodology for sustainable process design (Carvalho et al., 2008, Carvalho et al., 2009). Using process information/data such as the process flowsheet, the associated mass/energy balance data and the cost data, SustainPro guides the user through the necessary steps according to work-flow of the implemented methodology. At the end the design alternatives, are evaluated using environmental impact assessment tools and safety indices. The extended features of the methodology incorporate life cycle assessment analysis and economic analysis. The application and the main features of SustainPro are illustrated through a case study of β-galactosidase production.     

DBU-based CO_2 absorption–mineralization system: Reaction process,feasibility and process intensification

Amine-based carbon dioxide(CO_2) capture is still limited by high desorption energy consumption. Fixing CO_2 into carbonate is a safer and more permanent method. In this work, calcium oxide(CaO) is introduced to perform chemical desorption instead of thermal desorption on 1,8-diazabicyclo [5.4.0] undec-7-ene(DBU) aqueous solution after CO_2 absorption. The X-ray diffraction(XRD) patterns of solid products show the formation of calcite calcium carbonate(CaCO_3), which prove the feasibility of this method. The effects of reaction temperature, reaction time and Ca~(2+)/CO_3~(2-) molar ratios on the related reactions in CO_2 absorption–mineralization process and CaCO_3 precipitation are discussed, and purer CaCO_3 is obtained by ultrasonic treatment. The CaCO_3 content can be increased to 95.8% and the CO_2 desorption ratio can achieve 80% by 30 min ultrasonic dispersion treatment under the conditions(40℃, 180 min, Ca~(2+)/CO_3~(2-) molar ratio = 1.0). After five cycles, DBU aqueous solution shows stable CO_2 absorption and mineralization ability. Fourier transform infrared spectroscopy(FT-IR) spectra of the reaction process also indicate the regeneration of the solvent. Compared with thermal desorption, this process is exothermic, almost without no additional heat.     

Catalytic cyclic distillation – A novel process intensification approach in reactive separations

Cyclic distillation uses a periodic operation mode that leads to key benefits, such as increased column throughput, lower energy requirements and much higher separation performance. By integrating chemical reactions with cyclic distillation, a novel process intensification approach is possible – catalytic cyclic distillation – which outperforms classic reactive distillation.This paper is the first to describe the catalytic cyclic distillation process and to develop a rigorous mathematical model. By means of a case study involving a simple reaction system, the model is used to demonstrate the key benefits of this operation mode. In addition, the synthesis of dimethyl ether by catalytic cyclic distillation is considered, for which a design algorithm is suggested. Investigation of the column behavior reveals the coexistence of two periodic states, one of them being unstable.     

Work and heat integration—A new field in process synthesis and process systems engineering

The extension from heat integration and design of heat exchanger networks (HENs) to including heating, cooling, and power effects from pressure changing equipment has been referred to as work and heat integration and design of work and heat exchange networks (WHENs). This is an emerging research area in Process Synthesis and Process Systems Engineering, and WHENs represent a considerably more complex design task than HENs. A key challenge is the fact that temperature changes and pressure changes of process streams are interacting. Changes in inlet temperature to compressors and expanders resulting from heat integration will influence work consumption and production. Likewise, pressure changes by compression and expansion will change the temperatures of process streams, thus affecting heat integration. The state-of-the-art of this new research area including insight, methodologies, tools, opportunities, challenges, and literature is presented. Key aspects are illustrated by simple examples, whereas smaller case studies indicate potentials for industrial applications. © 2018 American Institute of Chemical Engineers AIChE J, 65: e16477 2019     

Purification and isolation of β-glucans from barley: Downstream process intensification

The purpose of this work was to study the purification and isolation (downstream process) of the β-glucan extracted from barley in an ultrasound assisted extraction (UAE) process. The co-extracted starch (average concentration 5.2 ± 0.1 g/L) was hydrolyzed by means of α-amylase. The optimization of the hydrolysis length, temperature and enzyme dose led to removal efficiencies higher than 90% (9 min hydrolysis length and enzyme doses of 100 μL/g at 55 °C), compared to the traditional hydrolysis processes (1 h at 95 °C). In a second step, a significant intensification of the process has been achieved by dosing the enzyme during the UAE step (7 min at 55 °C), resulting in a starch removal of 90%.Dextrins and other oligosaccharides were formed as a consequence of the enzymatic hydrolysis. In order to separate these low molecular weight molecules from the β-glucan (239 kDa), an ultrafiltration process (polysulfone membrane, nominal MWCO 100 kDa) was tried in a tangential flow cell: diafiltration successfully eliminated more than 45% of the oligosaccharides present in the liquid, providing a significant increase in the concentration of β-glucan and with the possibility of improving the percentage of elimination.The combination of these three technologies (UAE, enzymatic hydrolysis and diafiltration) allows getting high purity β-glucan concentrates (greater than 70%).     

A new way of enhancing transport process –The hybrid process accompanied by ultrafine particles

A brief review is presented on the enhancing effects of fine particles on multiphase mass transfer in the first part of this paper. Some experimental results on the following aspects are shown and discussed: influence of fine particles on mass transfer parameters (k_La, k_L, a), enhancement due to particles adsorption and catalyzing a chemical reaction, and effects of particle size. The second part of this paper proposes two kinds of hybrid process accompanied by ultrafine particles: adsorptive distillation and slurry catalytic distillation. Finally, prospective fields for additional research are proposed.     

Screening of chemical pulp,revisiting technology options,and the state-of-the-art equipment—A critical review

Screening of pulp can be expressed as a process where solid contaminants are removed from a pulp slurry without an excessive loss of fibres of acceptable quality. The impurities originate from the feedstock, or they are generated during the transport, handling, storage, or pulping process. The most typical impurities include bark, fibre bundles or shives, knots, plastic, rubber, and sand. Moreover, there are also other objectives for screening, such as the improvement of the pulp quality, savings in bleaching chemical consumption, and protection of process equipment. In industrial applications, pulp screening is typically carried out with more than one screen for a more beneficial screening result. The pulp screening equipment can be divided into different types by the separation technique employed, such as atmospheric or pressurized screens, centrifugal screens, vibrating screens, etc. In addition, there are other types of related equipment that are common in the pulp screening process, such as knotters, refiners, and hydrocyclones. The main objective of this review is to discuss the advantages and disadvantages of modern screening equipment as well as introduce contemporary screening strategies for chemical pulp mills.     

Processing methods for making porous bioactive glass-based scaffolds—A state-of-the-art review

Bioactive glasses exhibit the unique ability of bone bonding, thus creating a stable interface by stimulating bone cells toward mechanisms of regeneration and self-repair activated by ionic dissolution products. Therefore, 3D glass-derived scaffolds can be considered ideal porous templates to be used in bone tissue engineering strategies and regenerative medicine. This review provides a comprehensive overview of all technological aspects relevant to the fabrication of bioactive glass scaffolds, including the fundamentals of materials processing, a summary of the conventional porogen, and template-based methods and of recent additive manufacturing technologies, which are promising for large-scale production of highly reproducible and reliable implants suitable for a wide range of clinical applications.     

Computer simulation of gas generation and transport in landfills. IV: Modeling of liquid–gas flow

In the first three parts of this series a three-dimensional (3D) model was developed for transport and reaction of gaseous mixtures in a landfill. An optimization technique was also utilized in order to determine a landfill's spatial distributions of the permeability, porosity, the tortuosity factors, and the total gas generation potential, given a limited amount of experimental data. In the present paper we develop the model further by including the flow of both the leachate and the gases. A 3D dynamic model is developed that accounts for the generation of the four main gases of a landfill, along with the dissolved organic acids and the carbon in the presence of the leachate. The model is then utilized, through extensive numerical simulations, to study the effect of the various factors on the concentrations of the gases and the micro-organism. In particular, we demonstrate the strong effect of the heterogeneities of a landfill, represented by the spatial distribution of the local porosities, as well as an anisotropic distribution of the local permeabilities, on the behavior of a landfill, and in particular pressure buildup in it.     

Molecular distillation of copaiba oleoresin—A clean process for diterpenes enrichment

Copaiba oleoresin has sesquiterpenes and diterpenes with significant medicinal properties, including being antimicrobial, antiparasitic, and wound healing, among others. Thus, the objective of this work was to study the diterpene enrichment of the copaiba oleoresin from Copaifera officinalis via molecular distillation. Evaporator temperature (EVT) and feed flow rate (Q) were evaluated using an experimental design (2² with central point) considering the ratio of distillate and residue streams (DTR) as the response to optimize the residue recovery. EVT and Q were the main effects for diterpenes recovery, with the best experimental condition at 100°C (EVT) and 15 ml/min (Q) under 0.001 mbar, of which the residue stream had a diterpenes content of 99.25%. With the molecular distillation process, it was possible to add value to the copaiba streams, separating and purifying diterpenes with applicability in the biomedical and pharmaceutical industries since no solvent is used in this process (clean).     

Intensified plasma assisted processing — A novel process in surface coating techniques

Conclusions  The feasibility of using IPAP for the deposition of AIN for 2-stroke engine applications has been tested and the results have proved favourable. The quality of the initial coatings deposited was poor in terms of surface roughness and porosity. However, the micro-hardness of the IPAP coatings is three times greater than conventional nitriding process. Further investigations are being carried out to optimise the IPAP process for coating 2-stroke engine components and obtain a better fundamental understanding of the processing parameters involved. It is also hoped to extend the utility of this process for silicon nitride coatings. The optimum parameters recorded for AIN coatings should facilitate initial trials. The IPAP process has shown several advantages over other plasma processing systems at laboratory scale. Yet, a transfer from a laboratory scale to an industrial scale needs further assessment. The current work on IPAP is directed towards a final achievement at an industrial scale processing system.     

A local and global statistics pattern analysis method and its application to process fault identification☆

Traditional principal component analysis (PCA) is a second-order method and lacks the ability to provide higher-order representations for data variables. Recently, a statistics pattern analysis (SPA) framework has been incor-porated into PCA model to make full use of various statistics of data variables effectively. However, these methods omit the local information, which is also important for process monitoring and fault diagnosis. In this paper, a local and global statistics pattern analysis (LGSPA) method, which integrates SPA framework and locality pre-serving projections within the PCA, is proposed to utilize various statistics and preserve both local and global in-formation in the observed data. For the purpose of fault detection, two monitoring indices are constructed based on the LGSPA model. In order to identify fault variables, an improved reconstruction based contribution (IRBC) plot based on LGSPA model is proposed to locate fault variables. The RBC of various statistics of original process variables to the monitoring indices is calculated with the proposed RBC method. Based on the calculated RBC of process variables' statistics, a new contribution of process variables is built to locate fault variables. The simula-tion results on a simple six-variable system and a continuous stirred tank reactor system demonstrate that the proposed fault diagnosis method can effectively detect fault and distinguish the fault variables from normal variables.     

Lipids and endothelium-dependent vasodilation—A review

Studies using both in vitro and in vivo techniques have repeatedly shown that endothelium-dependent vasodilation (EDV) is impaired in different forms of experimental as well as human hypercholesterolemia. Clearly this impaired EDV can be reversed by lowering cholesterol levels by diet or medical therapy. Competitive blocking of l-arginine, changes in nitric oxide synthase acitivity, increased release of endothelin-1, and inactivation of nitric oxide due to superoxide ions all contribute to the impairment in EDV during dyslipidemia. The oxidation of low density lipoprotein, with its compound lysophosphatidylcholine, plays a critical role in these events. However, data on the role of triglycerides and fat-rich meals regarding EDV are not so consistent as data for cholesterol, although a view that the compositions of individual fatty acids and antioxidants are of major importance is emerging. Thus, this review shows that while impaired FDV is a general feature of hypercholesterolemia, the mechanisms involved and the therapeutic opportunities available still have to be investigated. Furthermore, discrepancies regarding the role of triglycerides and fat content in food may be explained by divergent effects of different fatty acids on the endothelium.     

Polymer derived ceramic microparts from X-ray lithography—cross-linking behavior and process optimization

The fabrication of micro components made from ceramic materials is becoming more and more important because of their outstanding chemical stability. Different replication methods like low or high-pressure injection molding of ceramic feedstocks have been established. Various lithographic methods are being widely used for the direct fabrication of very precise plastic or metal micro structured surfaces.The presented work deals with the direct manufacturing of microstructures by using ceramic precursors in combination with X-ray lithography. This allows for a rapid fabrication of micro structured plastic components that are stable at high temperatures (400 °C), chemically resistant and transparent. Pyrolysis of these parts yields amorphous SiCN or Si₃N₄ ceramics.The applicability of different preceramic polymers based on polysilazane for direct structuring with synchrotron radiation was investigated.X-ray exposures of polysilazane polymer filled with Si₃N₄ ceramic powders were carried out, showing that it is possible to microstructure those composites. By inserting ceramic fillers, a reduction of the shrinkage during pyrolysis was possible. Further investigations were made to determine the maximum filler content, the required exposure dose and the cross-linking mechanism using IR- and NMR-spectroscopy. As established in the LIGA technique with PMMA, resist layers up to 1 mm should be possible by deep X-ray lithography on preceramic polymers. Admittedly for the pyrolytic conversion into the amorphous SiCN ceramic, film thickness should be limited as crack formation is deteriorating with increasing dimensions.     

Mechanical, thermal and transport properties of nitrile rubber (NBR)—nanoclay composites

The article describes the properties of nitrile rubber (NBR)—nanoclay composites prepared by a two-step method. viz. preparation of a 3:1 [by weight] masterbatch of NBR and nanoclay followed by compounding on a two roll mill and molding at 150 °C and 20 MPa pressure. The tensile strength, elongation at break, modulus, storage modulus (E’) and loss modulus (E”) increased with the nanofiller content, reached the maximum value at 5 phr and decreased thereafter. The solvent uptake, diffusion, sorption and permeation constants decreased with nanoclay content with the minimum value at 5 phr nanoclay. The mechanism of solvent diffusion through the nanocomposites was found to be Fickian. Thermodynamic constants such as enthalpy and activation energy were also evaluated. The dependence of various properties on nanoclay content was correlated to the morphology of the nanocomposites. supported by morphological analysis.     

Mechanical, thermal and transport properties of nitrile rubber (NBR)—nanoclay composites

The article describes the properties of nitrile rubber (NBR)??nanoclay composites prepared by a two-step method. viz. preparation of a 3:1 [by weight] masterbatch of NBR and nanoclay followed by compounding on a two roll mill and molding at 150?°C and 20?MPa pressure. The tensile strength, elongation at break, modulus, storage modulus (E??) and loss modulus (E??) increased with the nanofiller content, reached the maximum value at 5 phr and decreased thereafter. The solvent uptake, diffusion, sorption and permeation constants decreased with nanoclay content with the minimum value at 5 phr nanoclay. The mechanism of solvent diffusion through the nanocomposites was found to be Fickian. Thermodynamic constants such as enthalpy and activation energy were also evaluated. The dependence of various properties on nanoclay content was correlated to the morphology of the nanocomposites. supported by morphological analysis.     

SIMBAD: A process simulator linked to a DBMS—I: The executive system

The data-handling capabilities of a commercial data base management system (DBMS) are used to control the information flow in a sequential modular steady-state process simulator. Thus, a new structure for the execution of this type of simulators is presented, in which executable program using a rigid agenda from a command file are called sequentially to reduce the amount of main memory occupied during the execution. All the executable programs, representing the basic simulation modules, recover information from the data base and return the new information generated through a common procedure.