José Jailson Nicácio Alves

Optimal Operation of an Industrial PVC Dryer

This article describes the design of a control structure architecture for an industrial polyvinyl chloride (PVC) dryer, currently operating at Braskem Company (Marechal Deodoro, Alagoas, Brazil). The underlying motivation is to search for a control configuration that leads to optimal economic operation, while promptly rejecting disturbances at lower layers in the control hierarchy. We start by optimizing a nonlinear model of the process with respect to reducing energy consumption as a criterion of optimization for different disturbance scenarios. The results show that it is optimal to control the temperature level of the utilities serving the dryer and the outlet PVC moisture contents at their respective upper bounds. In addition, the flow of air to the dryer should be fixed at its optimum nominal setpoint despite disturbances. Application of this strategy results in a reduction of about 16% in energy consumption with respect to the current dryer operation policy and a 22% increase in throughput under nominal operation. In addition, almost perfect indirect control of the outlet PVC moisture was achieved by tightly controlling a temperature difference in the dryer. The proposed decentralized control configuration gives good dynamic performance for the outlet PVC moisture content with maximum settling time of about 1.8 h for the more difficult disturbance of increasing the inlet slurry moisture content by 40% and magnitude of overshoot of ca. 5% w.r.t. the optimum setpoint for an increase of 20% in PVC feed flow rate to the dryer.

A new correlation for hazardous area classification based on experiments and CFD predictions

A correlation developed by the authors for prediction of hazardous area extension due to fugitive emissions is described in this work. The correlation is based on computational fluid dynamic (CFD) simulation data. The CFD simulation setups were obtained from a Computational Design of Experiments. The CFD model has been validated experimentally. The transport properties, orifice size, temperature, pressure, gas molar mass, and lower explosive limit (LEL) were varied in a range of practical interest using the statistical Technique Latin hypercube to spread the simulation setups. The effect of each variable on hazardous area extension was obtained from the CFD results leading to an analytical correlation for practical use in estimating the extension of the hazardous area. The results showed that the extension of hazardous area in still ambient is merely a function of the leaking gas molar flow rate and gas volume fraction at LEL. The results from the correlation described in this work were compared to results from correlations existing in the literature.

Experimental Planning of Mixtures to Obtain Geopolymer

This work had the aim to optimize the synthesis process of a geopolymer using experimental planning of mixtures. The geopolymer was prepared with different proportions of bauxite mud (R), rice husk ash (C) and metakaolin (M). The aluminosilicatealkaline activation was made with sodium hydroxide (NaOH) solution of 12 mol/L. Afterwards, the obtained material was submitted through a thermal treatment for 6 hours in an oven followed by a cure time of 28 days at room temperature. The final material was characterized through combinations of different techniques such as Scanning Electron Microscopy (SEM) and X-Ray Diffraction. Through carefully analysis of the flexural strength results, it was possible to conclude that the geopolymeric material (R6C2M) had a greater resistance in the seventh cure day at 0.6 MPa, however, it also can be said that the other samples presented an increase in the resistance over the 28 days of cure time.

Modeling of the Fischer-Tropsch Synthesis Aiming to Predict the Production of Paraffins and Olefins

The growing concern with the global environmental issues has resulted in a constant demand for the production of clean fuels. Therefore, researches were carried out in order to improve the gas-to-liquids technology, well represented by the Fischer-Tropsch synthesis. This synthesis is able to produce liquid fuels from syngas, a mixture of carbon monoxide and hydrogen which is obtained through the processing of the methane gas. Based on literature data, this paper suggests a kinetic model developed by making use of the Matlab® commercial application. The goal was to predict the production of hydrocarbons such as paraffins and olefins with up to six carbons in each chain. The Fischer-Tropsch synthesis was conducted with the catalyst 20% Co/ MCM-41 in fixed bed reactor at the temperature of 270 °C and atmospheric pressure. The results obtained by the model for both paraffins and olefins were compared with experimental data found in the literature.

New Routes Study for Synthesis of Molecular Sieves Type Al-MCM-41 and Al-SBA-15

The areas of research, synthesis and catalytic application of zeolites as molecular sieves are a field of great development and prominence in recent decades. Needs of the industries of petrochemical and fine chemicals have been encouraging specific studies for the application of molecular sieves looking for technological, commercial, and more recently sustainable developments. In this work molecular sieves type Al-MCM-41 and Al-SBA-15 has been synthesized using new synthesis routes by replacing the silica source conventionally used by rice husk. The molecular sieves obtained were confirmed by X-ray diffraction. Through the thermograms the decomposition of the driver at different temperatures was noticed. According to SEM micrographs can be observed that the material shows an aggregate of relatively uniform short particles.