Papers by Francisco Cubillos
Chemical engineering transactions, 2013
Gray-Box models (GBM) which combine a priori knowledge of a process –e.g. first principle equatio... more Gray-Box models (GBM) which combine a priori knowledge of a process –e.g. first principle equationswith a black-box modeling technique are useful when some parameters of the first-principle model – normally time-variant parameters like the specific kinetics of some bioprocessescannot be easily determined. In this case the black-box part of the GBM can be used to model the influence of input and state variables on the evolution of those parameters. The most commonly used black-box technique for GBM is Artificial Neural Networks (ANN). However Support Vector Machine (SVM) has shown its usefulness by improving over the performance of different supervised learning methods, either as classification models or as regression models. In this paper, a kind of SVM –the Least-Square Support Vector Machine (LS-SVM)are used to develop a GBM for a solid-substrate fermentation (SSF) batch process, the growth of the filamentous fungus Gibberella fujikuroi. SSF are well known as low water consumption...
Hydrothermal carbonization (HTC) is a thermochemical technology of biomass conversion that has so... more Hydrothermal carbonization (HTC) is a thermochemical technology of biomass conversion that has some advantages: lower operating temperature than other technologies, ability to process biomass with high moisture content and generation of a final product with a higher calorific value than the original biomass and with hydrophobic characteristics. This study evaluated the influence of temperature, time, biomass blend, nature and dose of additive in the HTC process. The response variables were mass yield (MY) and higher heating value (HHV), generating a total of 128 experiments that were grouped in 8 complete factorial designs (2 4). Pressed olive (OLV), oat husks (AV), Pinus radiata sawdust (AS), and raps seeds (RPS) were used as raw biomass. MY and HHV had an R 2 above 0.90 using the response equations of Experimental Design. Results indicate that temperature was the main effect in both responses, since it produced a decrease of MY between 5 and 10 %, and an increase of HHV between 1.5 and 2.2 MJ / kg. Use of additives did not significantly improve the energy yield. On the other hand, addition of a 'more reactive' biomass with increasing temperature achieved an important improvement in the HHV value. It is a positive fact because the studied biomass presents strong seasonal and geographical availability.
This paper introduces an integrated design for reatime plant modeling at a copper mine, using Sup... more This paper introduces an integrated design for reatime plant modeling at a copper mine, using Support Vector Machines (SVM), Neural Networks, and new technologies as Machine-to-Machine (M2M) and Cloud Computing with and an Android client. This solution was designed for a plant inside a copper mine which cannot tolerate interruption and for which their modeling and identification in situ, in real time, is an essential part of the system to control aspects such as instability by adjusting their corresponding parameters without stopping the process.
Science of The Total Environment, 2021
• Simulation of the long range transportation of atmospheric black carbon. • The biomass burning ... more • Simulation of the long range transportation of atmospheric black carbon. • The biomass burning is the main responsible of the atmospheric black carbon in Antarctica. • West Antarctica is impacted in 17-24 days since black carbon is emitted.
Chemical Engineering Transactions, 2020
The use of firewood and other biomass-based fuels have generated severe environmental pollution p... more The use of firewood and other biomass-based fuels have generated severe environmental pollution problems due high particulate matter emissions. Additionally, developing countries face considerable challenges in aspects related to the final disposal of organic waste in sanitary landfills that are already overflowed, and that constitutes a serious problem. In the last years, the search for alternative energy sources based on organic waste valorization has gained popularity. For waste biomass conversion, Hydrothermal Carbonization (HTC) has some advantages: low process temperatures required and the ability to work with biomass of different compositions and high moisture. Two groups of urban waste were considered in this investigation: 1) organic fraction of municipal solid waste (OFMSW) and 2) digested sludge (DS) from a water treatment plant. An Experimental Design was developed to study the effect of the blend composition with different OFMSW:DS ratios, reaction time (0.5 and 1 h) an...
Processes, 2020
The effect of magnesium chloride as an additive of hydrothermal carbonization (HTC) of lignocellu... more The effect of magnesium chloride as an additive of hydrothermal carbonization (HTC) of lignocellulosic biomass (Pinus radiata sawdust) was studied. The HTC tests were carried out at fixed conditions of temperature and residence time of 220 °C and 1 h, respectively, and varying the dose of magnesium chloride in the range 0.0–1.0 g MgCl2/g biomass. The carbonized product (hydrochar) was tested in order to determine its calorific value (HHV) while using PARR 6100 calorimeter, mass yield by gravimetry, elemental analysis using a LECO TruSpec elemental analyzer, volatile matter content, and ash content were obtained by standardized procedures using suitable ovens for it. The results show that using a dose of 0.75 g MgCl2/g biomass results in an impact on the mass yield that was almost equal to change operating conditions from 220 to 270 °C and from 0.5 to 1 h, without additive. Likewise, the calorific value increases by 33% for this additive dose, resulting in an energy yield of 68%, thu...
Chemical Engineering Transactions, 2020
In developing countries, there is a relevant problem related to air pollution caused by the indis... more In developing countries, there is a relevant problem related to air pollution caused by the indiscriminate use of residual biomass and the disposal of Municipal Solid Waste. Currently, various technologies (biological, thermal, thermochemical, among others) are available to valorize them. This review shows a current summary of two technologies: hydrothermal carbonization and gasification. The first one has been considered as a Waste to Energy technology capable of providing a solid, that can be used as a fuel, with higher calorific value and lower moisture and ash content than raw residual biomass. On the other hand, gasification generates syngas used as fuel or in the generation of electricity. During the last decade, most of the studies focused on hydrothermal carbonization of Municipal Solid Waste in contrast to gasification. However, the integration of those technologies has not even had the same interest. This study analyzed in-depth the product characteristics and the associat...
Saccharomyces cerevisiae is the main microorganism responsible for wine alcoholic fermentation. T... more Saccharomyces cerevisiae is the main microorganism responsible for wine alcoholic fermentation. The oenological phenotypes resulting from fermentation, such as the production of acetic acid, glycerol, and residual sugar concentration are regulated by multiple genes and vary quantitatively between different strain backgrounds. With the aim of identifying the quantitative trait loci (QTLs) that regulate oenological phenotypes, we performed linkage analysis using three crosses between highly diverged S. cerevisiae strains. Segregants from each cross were used as starter cultures for 20-day fermentations, in synthetic wine must, to simulate actual winemaking conditions. Linkage analysis on phenotypes of primary industrial importance resulted in the mapping of 18 QTLs. We tested 18 candidate genes, by reciprocal hemizygosity, for their contribution to the observed phenotypic variation, and validated five genes and the chromosome II right subtelomeric region. We observed that genes involved in mitochondrial metabolism, sugar transport, nitrogen metabolism, and the uncharacterized ORF YJR030W explained most of the phenotypic variation in oenological traits. Furthermore, we experimentally validated an exceptionally strong epistatic interaction resulting in high level of succinic acid between the Sake FLX1 allele and the Wine/European MDH2 allele. Overall, our work demonstrates the complex genetic basis underlying wine traits, including natural allelic variation, antagonistic linked QTLs and complex epistatic interactions between alleles from strains with different evolutionary histories.
Wildfires generate large amounts of atmospheric pollutants yearly. The development of an emission... more Wildfires generate large amounts of atmospheric pollutants yearly. The development of an emissions inventory for this activity is a challenge today, mainly to perform modeling of air quality. There are free available databases with historical information about this source. The main goal of this study was to process the results of biomass burning emissions for the year 2014 from the Global Fire Assimilation System (GFAS). The pollutants studied were the black carbon, the organic carbon, fine and coarse particulate matter, respectively. The inputs were pre-formatted to enter to the simulation software of the emission inventory. In this case, the Sparse Matrix Operator Kernel Emissions (SMOKE) was used and the values obtained in various cities were analyzed. As a result, the spatial distribution of the forest fire emissions in the Southern Hemisphere was achieved, with the polar stereographic projection. The highest emissions were located in the African continent, followed by the north...
Processes
Sulfur compounds are removed from petroleum by the addition of sodium hydroxide at a very high co... more Sulfur compounds are removed from petroleum by the addition of sodium hydroxide at a very high concentration. As a result, a residue called spent soda or spent caustic is generated, being extremely aggressive to the environment. In this work, the chemical properties of this residue are described in detail. The sodium hydroxide remains that have not reacted, sulfur compounds, and organic matter are the primary pollutants reported. Additionally, the main characteristics of the methods of treatment used to reduce them are described. This review comes from comprehensive and updated research and bibliographic analysis about the investigation on the topic. The advantages and disadvantages of the different treatment methods are highlighted. We established some criteria to set out when assessing the application of each one of these treatments is considered.
Journal of the Energy Institute
Biofuels
This study presents a new kinetic scheme for the mass yield prediction of waste lignocellulosic b... more This study presents a new kinetic scheme for the mass yield prediction of waste lignocellulosic biomasses treated by Hydrothermal Carbonization (HTC). The proposed reactions are based on the decomposition, solubilization, and polymerization of each main fraction of the biomass: cellulose, hemicellulose, and lignin. The ash content was assumed to be inert. The kinetic parameters have been obtained by non-linear adjustment using a data set with 220 experimental runs collected from the literature. The results indicate that the pre-exponential factors range was from 7.33 x10 1 to 1.412x10 5 min -1 , and activation energies were between 33.75 y 225.3 kJ/mol.
Air Quality, Atmosphere & Health
Chemical Engineering Communications
Http Dx Doi Org 10 1080 00986445 2011 613974, Mar 6, 2012
Miner Eng, 1997
In this paper the identification and control of a rougher flotation process is studied using an a... more In this paper the identification and control of a rougher flotation process is studied using an adaptable hybrid-neural model. The model is based on first principles and a PCA neural network is used for flotation kinetics estimation. Initially, the hybrid model is used for the identification, from input~output data obtained with a realistic phenomenological model, of a series off our flotation cells. Then, different regulatory and optimizing multivariable control alternatives are developed and tested on the process. The control problem is adaptively solved as an optimization problem, using predictions for the steady state obtained using the hybrid model. Results obtained for different input perturbations, setpoint changes and optimization tests show satisfactory performance, satisfying all required objectives without off-set or oscillation. Based on these results, the hybrid model can be considered an excellent option for the identification and control of flotation plants, from the point of view of flexibility and robustness.
2015 Latin America Congress on Computational Intelligence (LA-CCI), 2015
2015 Latin America Congress on Computational Intelligence (LA-CCI), 2015
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Papers by Francisco Cubillos