Brazilian Journal of Chemical Engineering This is an RSS file. You can use it to subscribe to this data in your favourite RSS reader or to display this data on your own website or blog.

Development of a start-up operation and dynamic behavior of a thermally coupled extractive distillation scheme
ABSTRACT The startup operation of distillation columns is one of the most complex steps performed in the industry. This complexity becomes even greater for thermally coupled extractive distillation systems. Thermally coupled configurations are commonly used in order to minimize the excessive amount of energy required to perform distillation. In view of this, this study aimed to develop a startup procedure for the thermally coupled extractive distillation system to obtain anhydrous ethanol by simulation using the computational package Aspen Plus Dynamics. From the startup procedure developed, the complex dynamic behavior of...
Source: Brazilian Journal of Chemical Engineering - July 16, 2019 Category: Chemistry Source Type: research

Optimization of pressure-swing distillation for anhydrous ethanol purification by the simulated annealing algorithm
ABSTRACT The present study addresses the novel application of the simulated annealing algorithm (SAA) to optimize the pressure-swing distillation (PSD) process for anhydrous ethanol purification. Three different softwares (Aspen Plus ®, Excel® and Matlab®) were integrated to simultaneously optimize seven design and operational variables. The configuration with the best TAC represented a 40.2% saving per year in comparison to the non-optimized PSD. Such reduction was achieved by using the higher acceptance probability and the slower temperature decrement. This saving is mainly related to operational cost reductions, a fa...
Source: Brazilian Journal of Chemical Engineering - July 16, 2019 Category: Chemistry Source Type: research

Model predictive control for production of ultra-low sulfur diesel in a hydrotreating process
ABSTRACT There is a continual desire around the world to reduce the sulphur content of diesel fuel to ultra-low levels (below 10 ppm) due to environmental concerns and the intention of improving air quality and lowering harmful exhaust emissions of diesel engines. In this work, a hydrodesulfurization unit fed with multiple diesel streams was addressed using a phenomenological mathematical model aiming to produce Ultra-Low Sulfur Diesel (ULSD). A three-phase model of a trickle-bed reactor was considered. A model-based predictive control strategy (MPC) was implemented with the objective of controlling the sulfur concentratio...
Source: Brazilian Journal of Chemical Engineering - July 16, 2019 Category: Chemistry Source Type: research

State estimation and trajectory tracking control for a nonlinear and multivariable bioethanol production system
ABSTRACT In this paper a controller is proposed based on linear algebra for a fed-batch bioethanol production process. It involves finding feed rate profiles (control actions obtained as a solution of a linear equations system) in order to make the system follow predefined concentration profiles. A neural network states estimation is designed in order to know those variables that cannot be measured. The controller is tuned using a Monte Carlo experiment for which a cost function that penalizes tracking errors is defined. Moreover, several tests (adding parametric uncertainty and perturbations in the control action) are car...
Source: Brazilian Journal of Chemical Engineering - July 16, 2019 Category: Chemistry Source Type: research

K-rank: an evolution of y-rank for multiple solutions problem
ABSTRACT Y-rank can present faults when dealing with non-linear problems. A methodology is proposed to improve the selection of data in situations where y-rank is fragile. The proposed alternative, called k-rank, consists of splitting the data set into clusters using the k-means algorithm, and then apply y-rank to the generated clusters. Models were calibrated and tested with subsets split by y-rank and k-rank. For the Heating Tank case study, in 59% of the simulations, models calibrated with k-rank subsets achieved better results. For the Propylene / Propane Separation Unit case, when dealing with a small number of sample...
Source: Brazilian Journal of Chemical Engineering - July 16, 2019 Category: Chemistry Source Type: research

Statsscandleplot: a new way of monitoring operational performance indicators
ABSTRACT Operational KPIs play an extremely important role in the process industry, aiding in decision making. However, they need to be reliably calculated to be representative. The present work presents a schematic methodology for the calculation of these KPIs, including techniques of steady-state detection, denoising, error propagation and sensitivity analysis, presented, as far as it is known, in the form of a new graphical tool proposed by the authors named StatSSCandlePlot. The methodology was applied in a real case study of a gas fired boiler in which the indicator studied was its efficiency evaluated by the Stack Lo...
Source: Brazilian Journal of Chemical Engineering - July 16, 2019 Category: Chemistry Source Type: research

Sensitivity analysis for model comparison and selection in tissue engineering
In this study, the contribution of oxygen to Contois growth kinetics and porosity variation with time due to polymer degradation was evaluated through a sensitivity analysis. The effect of initial glucose concentration, porosity and thickness of the scaffold on the cell volume fraction and substrate concentration was analyzed for three models. Even with the inclusion of oxygen concentration in the model, the output variables are more affected by the initial cell number, while the model with variable porosity is quite robust to variations in the input variables. (Source: Brazilian Journal of Chemical Engineering)
Source: Brazilian Journal of Chemical Engineering - July 16, 2019 Category: Chemistry Source Type: research

On the performance of different rans based models to describe the turbulent flow in an agitated vessel using non-structured grids and piv validation
ABSTRACT The performances of the Standard κ - ε , RNG, Realizable, κ - ω and RSM turbulence models to describe the behavior of the flow in agitated tank reactors were evaluated. Because most of these tanks have complex geometries, structured meshing schemes are not a practical alternative in engineering. Two particular unstructured meshing schemes composed of either Cartesian Cut-Cell (CC) or Tetrahedral elements were tested in domains larger than 3 million cells. In this work, the blade thickness, which is usually disregarded, was accounted for. The performance of the turbulence models was validated by PIV measuremen...
Source: Brazilian Journal of Chemical Engineering - July 16, 2019 Category: Chemistry Source Type: research

Comparison between experimental and simulated results of biodiesel production by reactive distillation and energetic assessment
ABSTRACT Biodiesel appears to be a likely substitute to conventional diesel. However, the main challenge has been the creation of a competitive advantage for the biodiesel production process in terms of innovation and efficiency. The reactive distillation technique for biodiesel production is possibly a key force to overcome this technological issue because it combines chemical reaction and the separation process inside the same unit. This work presents kinetic data for biodiesel production via the ethylic route and compare them with the methylic one. It also compares experimental results in a 1.5m reactive distillation pi...
Source: Brazilian Journal of Chemical Engineering - July 16, 2019 Category: Chemistry Source Type: research

Simulation of thermal decomposition in an open cavity: entropy analysis
ABSTRACT This paper presents a numerical analysis of entropy generation in a two-dimensional rectangular channel where the inlet flow undergoes thermal decomposition resulting from a chemical reaction. The model considered viscosity and thermal conductivity to be dependent of temperature. Irreversibility due to mass transport was included in the entropy generation analysis. Relevant applications of this study are possible for the design of power generation systems and reactors. The effects of the Reynolds number, Schmidt number, and length of the heat source on thermal fluid dynamics, mass transfer, and irreversibility wer...
Source: Brazilian Journal of Chemical Engineering - July 16, 2019 Category: Chemistry Source Type: research

Reliability-based multi-objective optimization applied to chemical engineering design
ABSTRACT Chemical engineering optimization represents a significant challenge due to the complexity of the mathematical models that are frequently required in this area. These models are normally associated with nonlinear equations that represent mass, energy, and momentum balances, which are submitted to physical, constitutive, environmental, and design limitations. The design of chemical systems is generally carried out by considering the model, the vector of design variables, and system parameters as deterministic values, i.e., small variations in these quantities do not affect the objective function. In this contributi...
Source: Brazilian Journal of Chemical Engineering - July 16, 2019 Category: Chemistry Source Type: research

The role of sulfonated activated carbons as catalysts for the hydrolysis of cellobiose
ABSTRACT In this work the production of glucose via hydrolysis of cellobiose using sulfonated active carbons as catalysts was studied. Commercial carbons presenting different types of porous system (micropores and mesopores) have been treated with sulfuric acid at different temperatures, being characterized afterwards. Such carbons have been tested as catalysts in the reaction of cellobiose hydrolysis. The results indicated that the type and density of sulfonic sites are not the only parameters responsible for the activity of the catalysts. Indeed, the porosity of the catalysts also plays an important role in the determina...
Source: Brazilian Journal of Chemical Engineering - July 16, 2019 Category: Chemistry Source Type: research

Esterification of oleic acid in a semi-batch bubble reactor for biodiesel production
ABSTRACT A semi-batch bubble reactor has been developed to produce fatty acid ethyl ester (biodiesel) by acid-catalyzed esterification of oleic acid with superheated ethanol vapor. In this paper, the effects of reaction temperature (110, 130 and 150 °C), ethanol volumetric flow rate (1.35, 2.50 and 3.65 mL/min) and vapor bubble size on the reactor performance were evaluated. The results demonstrated that temperature and volumetric flow rate have significant effects on the chemical reaction, gas phase solubility and mass transfer limitations. I n addition, the free fatty acid conversion velocity was increased by approximat...
Source: Brazilian Journal of Chemical Engineering - July 16, 2019 Category: Chemistry Source Type: research

Production of fatty acid methyl esters from an olive oil industry waste
This study shows that pomace oil can be used as a raw material for biodiesel production. At short reaction times and under moderate operating conditions, it was possible to convert triglycerides and fatty acids selectively toward FAME. (Source: Brazilian Journal of Chemical Engineering)
Source: Brazilian Journal of Chemical Engineering - July 16, 2019 Category: Chemistry Source Type: research

Characterization and behaviour of pt catalysts supported on basic materials in dry reforming of methane
ABSTRACT Different basic materials, such as K-L zeolite, K-Al2O3, K-Mg/Al mixed oxide and MgO, were used as supports of Pt-catalysts for the dry reforming of methane (DR) reaction. The effects of the distribution of basic strength in the support on the metal-support properties and catalyst performance were evaluated. The density of strong and the total basic sites decreased as follows: MgO>K(Mg-Al)>K-Al2O3>K-L. The total basic sites decrease from 214 to 23 µmol CO2. g-1, for MgO and KL, respectively. Pt catalysts supported on materials with high density of strong basic sites such as MgO were the most adequate for...
Source: Brazilian Journal of Chemical Engineering - July 16, 2019 Category: Chemistry Source Type: research