Viatcheslav Kafarov

Development of a topology of microalgae-based biorefinery: process synthesis and optimization using a combined forward–backward screening and superstructure approach

Microalgae continues emerging as a promising feedstock for the development of biorefineries. Since there are numerous possible technologies that can be used to process microalgae and produce a wide variety of products and co-products, it is necessary to develop an efficient approach for the generation and screening of processing technologies. This work introduces a combined methodology for the synthesis and analysis of topological pathways for the processing of microalgae based on main approaches of hierarchical and mathematical programming-based process synthesis. The methodology uses a hierarchical approach that starts with top-level data and focuses attention and effort on the promising pathways integrating various process synthesis and optimization concepts such as forward–backward branching, superstructure optimization, and in-depth analysis for high-priority pathways. A case study is solved for the production of diesel-like fuel from microalgae biomass.

Study and modeling of simultaneous hydrodesulfurization, hydrodenitrogenation and hydrodearomatization on vacuum gas oil hydrotreatment

Abstract One of the objectives of the present work is to expose the use of a trickle bed reactor model to predict the quality of products during the hydrotreatment of vacuum gas oil using a commercial catalyst and based on data obtained at pilot-plant scale, where catalytic experiments were carried out under typical industrial considerations, at different temperatures, pressures, and space-velocity (LSHV). Most of the models only consider the hydrodesulfurization reaction (HDS). However, models that involve hydrogenation of aromatics (HDA) and hydrodenitrogenation (HDN) are scarce in the literature, and they are also very important for hydrotreatment reactor modeling, because mainly to news maximum limits in aromatics and nitrogen. A sequential design of experiments was used for model discrimination and parameter estimation during kinetic investigation. Also, was investigated the effect of aromatics molecules (naphthalene, phenantrene) and nitrogen containing compounds (carbazol, acridine) on the HDS of a vacuum gas oil (VGO). The reactor was simulated with a steady-state one-dimensional heterogeneous model. In addition, all necessary thermophysical properties, such as phase densities, viscosities, conductivities, diffusivities, and molar partial enthalpies were continuously calculated as functions of the system pressure, temperature and phase composition.

ENVIRONMENTAL ASSESSMENT OF MICROALGAE BIODIESEL PRODUCTION IN COLOMBIA: COMPARISON OF THREE OIL EXTRACTION SYSTEMS

Resumen en: The objective of the study was to compare three cases of biodiesel production from microalgae dried biomass applying the Life Cycle Assessment (LCA) tech...

Modeling of trickle bed reactor for hydrotreating of vacuum gas oils: effect of kinetic type on reactor modeling

Abstract The hydrodesulfurization (HDS) processes research requires a lot of experimental work to define promotion and inhibition effects and find out correlations between the variables that participate on the sulphur removal. By means of modeling and simulation is possible to determine the scope of the process, and by means of the sequential design of experiments (SDE) is possible to reduce the experimental work required through comparison of kinetic models, at the same time that it predicts experimental conditions that allow to select a unique model and estimate its parameters. The purpose of this work was to simulate the HDS process using the mathematical model developed in previous work and several kinetic models founded in literature. Together simulation is proposed a SDE-based software with Runge-Kutta routines, orthogonal collocation methods an Sequential Quadratic Programming to develop the steps of the Design and to be used on pilot plant applications. The good agree between theoretical and experimental data led to the development of a user-friendly program to simulate the complex process, make easier the interpretation of simultaneous reactions, and become a useful tool for to improve the operation conditions of hydrotreating industrial reactors.

Computer-aided modeling for hydrodesulfurization, hydrodenitrogenation and hydrodearomatization simultaneous reactions in a hydrotreating industrial process

Abstract The purpose of this research is to utilize computer aided modeling as a tool for the investigation of simultaneous hydrodesulfurization (HDS), hydrodenitrogenation (HDN) and hydrodearomatization (HDA) reactions in industrial reactors. This study is based on the modeling of an industrial process as a mean to predict the quality of products during the hydrotreatment of a vacuum gas oil (VGO) using a commerical catalyst (Ni-Mo/γAl 2 O 3 ), including the three selected reactions (HDS, HDN, HDA), and utilizing data obtained at a pilot-plant, where catalytic experiments were carried out under typical industrial conditions. Analytical techniques such as nuclear magnetic resonance (NMR), gas chromatography coupled with high performance mass spectrometry (GC-MS), ultraviolet-visible spectrometry (UV-VIS), simulated distillation (SimDis), analysis of saturates-aromatic-resin (SAR), and standard tests (ASTM) were used for the construction of a database. A suitable numerical program with a user-friendly interface was written for this simulation. The simulated results show a good agreement with experimental data obtained from the pilot plant.

Computer aided evaluation of eco-efficiency of solvent-based algae oil extraction processes for biodiesel production

Abstract This paper provides an environmental assessment and exergy analysis for the extraction of oil of microalgae. In this work, three solvent extraction methods are simulated with the Aspen Plus®7.1 software, using as feedstock the microalgae genera Chorella sp. The solvent-based methods evaluated were methanol/chloroform, ethanol/hexane, and in situ-hexane extraction; operating conditions for each method were adjusted with experimental work. Mass, energy and exergy balances for each method were performed. The impact categories considered were: Global Warming (GWP100), acidification, eutrophication, photochemical oxidation, ozone layer depletion (ODP) and non-renewable fossil; each one were evaluated with the SIMAPRO 7.1 software. The environmental assessment was applied following the procedures established by the ISO 14040 and 14044 (2006) standards. Finally, exergetic losses, efficiency and environmental profile were calculated for the process. The environmental assessment and exergy analysis confirms the potential of third generation biofuels as an energy source, but is necessary to perform some technical improvements in the oil extraction stage to increase exergetic efficiency and to reduce environmental impacts of the process.

Comparison of technology alternative for palm oil biodiesel production using exergy analysis

Abstract In the present paper, the exergy analysis was applied to comparison of two alternatives for palm oil biodiesel production, with the aim to identify the location and magnitude of the irreversibilities and the exergetic efficiency in each one of the equipments. The first case of study was a homogeneous transesterification, where the process was divided in three stages, the pre-treatment of the crude palm oil, triglycerides transesterification reaction with methanol and NaOH as catalyst, and finally the separation system; the other case was a heterogeneous esterification in three stage, the pre-treatment performed to hydrolyze triglycerides presented in palm oil, the esterification of fatty acid and separation and purification system. Each process were designed and simulated using the software Aspen Hysys 6.5. The exergy analysis methodology used in this paper was proposed by Dincer and Rosen, and the Reference Stable Environment (RSE) was defined at 25 °C and 1 atm, and each process equipments was taken as volume control system.

Computer-aided forecast of catalytic activity in an hydrotreating industrial process using artificial neural network, fuzzy logic and statistics tools

Abstract Complex hierarchic organization of heterogeneous catalytic systems makes impossible to design a theory to quantitatively predict catalytic activity based on strict laws of heterogeneous catalysis. For this reason here we present a methodology based on computer-aided and mathematical tools to solve the problem of choice of catalysts for a hydrotreating industrial process. Twenty-four hydrotreatment catalysts with different textural and physicochemical properties were aged in an industrial reactor during the length of the run. First, an evaluation of the uncertainty of the industrial experimentally collected data is made based on the Hotelling T 2 statistic tool. Next, the application of artificial neural networks (ANN) to determine the influence of each selected physicochemical variable on the catalytic activity (capacity of metals removal: contents of nickel, vanadium and molybdenum) is proposed. Then, a methodology based on the application of several kinds of multiple regression (MLR), including Brandons method (which provides a mathematical model using priority of selected variables) is applied. Similarly, we also propose the application of ANN to correlate process variables as well as the utilization of fuzzy logic tools to obtain qualitative models. In this manner it was possible to compare the results obtained from different mathematical methods and to make decisions about the optimum chemical compositions and texture of the industrial catalyst.

Kinetics of Lycopene Degradation in Sunflower and Grape Seed Oils

The stability of lycopene in two vegetable oils, sunflower seed oil (SSO) and grape seed oil (GSO), was investigated by analyzing the carotenoid degradation kinetics in the temperature range of 10–40°C. A tomato oleoresin containing 6% (w/w) of lycopene was used to prepare lycopene-enriched oil samples. Analysis of kinetic data showed that lycopene degradation follows first-order kinetics, with an apparent activation energy of 70.7 kJ mol–1 in SSO and 69 kJ mol–1 in GSO. The estimated half-life of lycopene was found to depend on oil type and storage temperature. At 20°C, it varied between 59 and 122 days, while at 4°C it was comprised between 302 and 650 days. At all temperatures, lycopene was more stable in SSO than in GSO, which is likely due to the higher content of antioxidant compounds in SSO.

METHODOLOGICAL PROPOSAL FOR EVALUATION OF OIL SPILLS ENVIRONMENTAL VULNERABILITY IN RIVERS

ABSTRACT 2017-397 Rivers have been a major part in the development of human activities since the beginning of civilization. Globally, increased navigation in rivers and construction of oil storage ...