Maurício Bezerra de Souza

Enzymatic hydrolysis optimization to ethanol production by simultaneous saccharification and fermentation

There is tremendous interest in using agro-industrial wastes, such as cellulignin, as starting materials for the production of fuels and chemicals. Cellulignin are the solids, which result from the acid hydrolysis of the sugarcane bagasse. The objective of this work was to optimize the enzymatic hydrolysis of the cellulose fraction of cellulignin, and to study its fermentation to ethanol using Saccharomyces cerevisiae. Cellulose conversion was optimized using response surface methods with pH, enzyme loading, solid percentage, and temperature as factor variables. The optimum conditions that maximized the conversion of cellulose to glucose, calculated from the initial dried weight of pretreated cellulignin, (43°C, 2%, and 24.4 FPU/g of pretreated cellulignin) such as the glucose concentration (47°C, 10%, and 25.6 FPU/g of pretreated cellulignin) were found. The desirability function was used to find conditions that optimize both, conversion to glucose and glucose concentration (47°C, 10%, and 25.9 FPU/g of pretreated cellulignin). The resulting enzymatic hydrolyzate was fermented yielding a final ethanol concentration of 30.0 g/L, in only 10 h, and reaching a volumetric productivity of 3.0 g/L·h, which is close to the values obtained in the conventional ethanol fermentation of sugar cane juice (5.0–8.0 g/L·h) in Brazil.

Neural Network Based Modeling and Operational Optimization of Biomass Gasification Processes

© 2012 de Souza et al., licensee InTech. This is an open access chapter distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Neural Network Based Modeling and Operational Optimization of Biomass Gasification Processes

Quantitative risk assessment integrated with process simulator for a new technology of methanol production plant using recycled CO2

The use of process simulators can contribute with quantitative risk assessment (QRA) by minimizing expert time and large volume of data, being mandatory in the case of a future plant. This work illustrates the advantages of this association by integrating UNISIM DESIGN simulation and QRA to investigate the acceptability of a new technology of a Methanol Production Plant in a region. The simulated process was based on the hydrogenation of chemically sequestered carbon dioxide, demanding stringent operational conditions (high pressures and temperatures) and involving the production of hazardous materials. The estimation of the consequences was performed using the PHAST software, version 6.51. QRA results were expressed in terms of individual and social risks. Compared to existing tolerance levels, the risks were considered tolerable in nominal conditions of operation of the plant. The use of the simulator in association with the QRA also allowed testing the risk in new operating conditions in order to delimit safe regions for the plant.

RSM analysis of the effects of the oxygen transfer coefficient and inoculum size on the xylitol production by Candida guilliermondii

Biotechnology production of xylitol is an excellent alternative to the industrial chemical process for the production of this polyalcohol. In this work the behavior of Candida guilliermondii yeast was studied when crucial process variables were modified. The K(L)a (between 18 and 40/h) and the initial cell mass (between 4 and 10 g) were considered as control variables. A response surface methodology was applied to the experimental design to study the resulting effect when the control variables were modified. A regression model was developed and used to determine an optimal value that was further validated experimentally. The optimal values determined for K(L)a and X(0) were 32.85/h and 9.86 g, respectively, leading to maximum values for productivity (1.628 g/h) and xylitol yield (0.708 g/g).

Rethinking Petroleum Products Certification

Facing various challenges in the everchanging refining landscape, it is essential that refiners raise their operations to new levels of performance. Advances in in-line blending (ILB) technology accuracy and reliability have encouraged refiners to take a step forward. Having ILB as a precursor, a new methodology is in concern: the so-called in-line certification (ILC) procedure. Blending processes make use of in-line measurements which, at least in principle, can be used to certificate the product, if the precision and accuracy of available in-line measurements are comparable to measurements provided by standard off-line tests. Such procedure may allow for significant reduction in refinery’s tank farming and product inventory, increase of process flexibility, and reliability with benefits to company image. The main limitations for real-world ILC applications in the oil industry remain at the legal and technological levels. This paper proposes novel concepts and foundations of a basic in-line certification model for petroleum products regarding current interdisciplinary challenges and promising solutions.

Dynamic Simulation of a Compressor Located in a Natural Gas Processing Unit Using EMSO Simulator

Abstract Nowadays, a profound knowledge of all the stages involved in large scale processing of oil, natural gas or other fuels is necessary, due to the increased preoccupation with how to use the natural resources in a responsible way. The facilities for processing natural gas can be divided in two main parts, the first one responsible for the condensation of larger hydrocarbons (ethane, propane, butane, and the like) and the second one for the distillation of these larger hydrocarbons obtained. The first part of these facilities achieves a minimum temperature of -90°C due to a propane refrigeration system. This work studies a centrifugal compressor situated in the propane refrigeration system of a Natural Gas Liquid Recovery Unit (LRU) located in Macae (Rio de Janeiro, Brazil) -Petrobras Transporte S.A. (Transpetro). This compressor is one of the most complex and important equipments of the LRU. The main contribution of this paper is to propose a dynamic model for this centrifugal compressor based on mass and energy balance coupled with thermodynamics equations for the nonidealities of the gas. This dynamic model was used to simulate real conditions in some situations observed in the LRU, analyzing its open loop behavior and investigating its automatic control (controller tuning and closed loop behavior). The situations studied consisted in applying step disturbances to the centrifugal compressor and then interpreting the results in the light of the developed model. The modeling, simulation and control investigations were achieved using a Brazilian simulator called EMSO (Environment for Modeling, Simulation and Optimization), which is a graphical environment that can be freely modified by all users. In this environment, the language is fully object-oriented, allowing the user to develop complex dynamic or steady models by composing them with existent small models or build specific models by deriving standard ones. EMSO was developed by the ALSOC Project (Free Environment for Simulation, Optimization and Control of Processes) which supplies this software without costs for partners and universities, aiming therefore to standardize and spread out its use. The present work provides information on the operation and control of the compressor allowing the further development of abnormal situation management tools that will support the control system and provide an easier and safer operation of the LRU.

Influence of reaction operation conditions on the final properties of high impact polystyrene (hips)

The main objective of the present work is to analyze the influence of some important operational reaction parameters (agitation speed, polybutadiene - PB - content and initiator concentration) on the final properties of High Impact Polystyrene (HIPS) produced in bulk. Variable effects are analyzed both qualitatively and quantitatively with the help of a fractional factorial design. Physical, chemical and mechanical properties were evaluated through measurement of the weight-average molecular weight (Mw), polydispersity (PD), volume-average diameter of PB particles (D(4,3)) and impact strength (Izod). It was found that PD and D(4,3) depend strongly on the initiator concentration, rubber concentration and agitation speed; Mw depends on initiator and rubber concentrations; and Izod depends on the rubber concentration, PD and D(4,3) in the analyzed experimental range. As a consequence, it was shown that control of final polymer properties can be easily performed through proper manipulation of the analyzed operational variables.