CFD-Aspen Plus interconnection method. Improving thermodynamic modelling in computational fluid dynamic simulations

Producción CientíficaThermodynamic modelling in CFD is basically limited to the models available in the simulators. The method presented in this paper connects CFD simulators with Aspen Plus which instantaneously calculates and returns the value of any physical property required. Therefore, all the thermodynamic models and compounds available in Aspen Plus can be implemented in CFD simulations. The connection, created via Matlab and Excel-VBA, has been validated solving two identical CFD simulations first selecting a thermodynamic model available in the simulator and then connecting the simulator with Aspen Plus and selecting the same model. The maximum absolute average deviation between the density and viscosity values obtained in both simulations, for the two case studies analyzed, is lower than 0.7% which demonstrates the proper interconnection. The accuracy of the results obtained modeling multicomponent mixtures and supercritical fluids proves the applicability of the method to any scenarios2018-12-31Ministerio de Economía, Industria y Competitividad - FEDER (Proyects CTQ2013-44143-R and CTQ2016-79777-R

Heterogeneous catalysis for the extraction of arabinoxylans from wheat bran

Introduction The conversion of biomass within biorefineries into chemicals and energy is seen as a real possibility for the substitution of fossil resources. Raw materials of high lignocellulosic content are an interesting option. Besides wood and non-food crops, agricultural residues like straw and corn stover as well as other by-products of various origins are of high interest as feedstocks. Wheat bran represents such a by-product, which accrues in enormous quantities during the production of white wheat flour. It is estimated that 150 million tons are produced per year worldwide [1]. Currently wheat bran is mainly used as a low value ingredient in animal feed. Arabinoxylans are the most abundant structural polysaccharides in wheat bran, and they can be suitable compounds for the production of sugar alcohols. In general terms, the conversion of these hemicellulosic components from biomass into sugar alcohols is a two‑step reaction: 1) extraction and hydrolysis of arabinoxylans and 2) hydrogenation of these hemicelluloses into polyols (Figure 1). Please click Additional Files below to see the full abstract

Aromatics from Lignin through Ultrafast Reactions in Water

Producción CientíficaNowadays, the valorization of lignin, the major natural source of aromatics in earth, is being a challenge for the scientific community. In this study, kraft lignin is effectively converted into aromatic monomers by ultrafast depolymerization in hot and pressurized water. At reaction times below 500 ms, it is possible to avoid char formation originated from undesirable condensation reactions by controlling accurately the reaction time. Under alkaline medium, the reaction reaches an optimum point at 386ºC and 300 ms with a light oil yield of 60% with a concentration in key compounds such as guaiacol, creosol, vanillin and acetovanillone of around 20 %w/w. The char formation in this point was surprisingly low (4 %w/w). Analysis and quantification of the products allows to identify the evolution of the different reaction steps and propose plausible mechanism for the depolymerization and repolymerization stages. Furthermore, it is proven that the proposed technology is equally effective to treat directly industrial black liquors with a yield higher than 50% to light oil, containing as main monomers guaiacol (2.7%), syringol (3.0%) and syringaldehyde (7.3%).2020-02-152020-02-15Ministerio de Economía, Industria y Competitividad (Project CTQ2016-79777-R)Ministerio de Educación, Cultura y Deporte (Proyect FPU15/00409

Titanium dioxide nanoparticle coating in fluidized bed via supercritical anti-solvent process (SAS)

A process to coat nanoparticle agglomerates has been developed and its critical operation parameters have been studied in this work. It consists on a fluidized bed where a supercritical anti-solvent process (SAS) takes place. Titanium dioxide (TiO2), used as model nanoparticle, has been coated with a polymer, Pluronic F-127, from an ethanolic solution. As main factors that can affect the coating process, the following process parameters were studied: the ratio between the velocity of carbon dioxide through the bed and the minimum fluidization velocity (umf), with values from 1.5 to 2.5 times the umf; the density of carbon dioxide, varying from 640 kg/m3 to 735 kg/m3 approximately; the flow rate of solution, within an interval between 0.5-2 mL/min; the concentration of the solution, from 0.030 mg/mL to 0.090 mg/mL and the mass ratio polymer-particle, 0.45-1.8 g/g. The process parameters were selected taking into account the values that increased the yield, defined as gram of coating material per gram of introduced polymer amount, and maintained a unimodal particle size distribution (PSD), with low increment in the mean particle size with respect to raw TiO2. All the samples were analyzed by four different methods, which showed the successful results of the experiments. The yield was analyzed gravimetrically, and the PSD was determined by laser diffraction. The presence of polymer on the surface of the nanoparticle agglomerates was verified by FT-IR spectrum and fluorescence microscopy, which also showed the quality and uniformity of the coating. Furthermore, the bulk density of the samples was measured showing a lineal variation with the mass ratio polymer-particle.2017-09-01This work is partially supported by the project Shyman FP7-NMP-2011-LARGE-280983 and the project CTQ2013-44143-R of the Spanish Ministerio de Economía y Competitividad. Víctor Martín thanks the University of Valladolid for his doctoral grant. Rut Romero-Díez would like to thanks her agreement with the University of Valladolid. Soraya Rodríguez-Rojo thanks the Spanish Ministerio de Ciencia e Innovación and the University of Valladolid for her Juan de la Cierva fellowship (JCI-2012-14992)

Understanding sulfonated kraft lignin re-polymerization by ultrafast reactions in supercritical water

Producción CientíficaRe-polymerization reactions are a commonly reported issue on the way to the higher recovery of monomers from lignin. The reactivity of monomers obtained from lignin depolymerization and their contribution to the re-polymerization in supercritical water (SCW) was investigated. Sulfonated Kraft lignin (SKL) was used along with four monomers: vanillin, vanillic acid, vanillyl alcohol and acetovanillone. Indulin Kraft lignin was also employed as the reference to understand the re-polymerization of SKL in SCW. The formation of diarylmethane structures was detected in HSQC spectra of solid residue after the SCW process. Lignin released fragments with free phenolic β-O-4 structures, as well as the monomeric product vanillyl alcohol are involved with the formation of o-o´ and o-p´ diarylmethane structures. Chemical structure of Kraft lignin and its polymeric product after the SCW process was remarkably similar, as shown by HSQC, indicating that re-polymerization reactions occur through cross-linking polymerization, mainly in their fractions of low molecular weight products.Ministerio de Ciencia, Innovación y Universidades - Fondo Europeo de Desarrollo Regional (projects CTQ2016-79777-R and PID2019-105975GB-I00)Junta de Castilla y León (project CLU-2019-04 T

Characterization of rosemary essential oil for biodegradable emulsions

The characterization of rosemary essential oil (EO) for its formulation in biodegradable emulsions has been carried out. Firstly, the required HLB (hydrophile–lipophile balance) value of the oil was determined to be 15 based on droplet size analysis and the stability of emulsions with synthetic surfactants. Moreover the emulsion resulted to be stable after 50 days of storage in ambient conditions. Secondly, four biodegradable and non-toxic surfactants derived from starch were tested. The effect of these surfactants was analyzed by measuring interfacial tension between the oil and the aqueous phase.The authors thank the financial support of Junta de Castilla y Leon (Spain) through the project GR11/2008. National Starch Group is acknowledged for supplying the OSAmodified starches and giving permission to publish the results obtained with them. S.Rodríguez-Rojo thanks the Spanish Ministry of Education for her postdoctoral grant. S. Varona thanks the University of Valladolid through the FPI-UVa research program