Ronaldo Hoffmann

Aplicabilidade das cinzas da casca de arroz

Currently, the accumulation of rice husk is a serious environmental problem. The burning of rice husk generates a considerable volume of ash, that falls to the ground and gets into the air and the rivers, causing a disequilibrium in the ecosystem. This motived research into solutions that aim to exploit the husks for energy generation and the ashes for developing diverse technological products. This work presents the possibilities of using rice husks and their ashes after burning.

AN INNOVATIVE PROJECT INVOLVING AN APPROPRIATE HYBRID DISTILLATION SYSTEM FOR SMALL-SCALE ETHANOL FUEL PRODUCTION

A yield increase in the distillation step reveals a promising way to guarantee technical and economic feasibility for small-scale ethanol production (SSEP), up to 30 L · h−1. The objective of this study is to assess a differentiated distiller, a hybrid composition involving a Vigreux column and a packing (Raschig rings) column in the stripping and rectifying sections, respectively. To evaluate the distiller, seven tests were performed in a continuous operation system. The feed and vaporization rates were varied so that their influence on the operational performance of the distiller could be measured. Specifically, the ethanol concentration in the distillate and bottom products, the operational capacity, and the energy factor were measured. The results prove the technical feasibility of the hybrid distiller, and the application of the hybrid distiller in small-scale distilleries is promising. To improve the distillation step, construction of a pilot-scale column is recommended.

Síntese do espinélio MgAl2O4 via "sol-gel"

The spinel MgAl2O4 has a specific combination of desirable properties such as: high melting point (2135 oC), high resistance to chemical attack, good mechanical resistance at room temperature and high temperatures, low dielectric constant, excellent optical properties and good catalytic properties. In this work, the spinel MgAl2O4 was synthesized through hydrolysis of metallic alkoxides of Mg and Al. The formed spinel precursor phase was calcined at temperatures between 600 and 1100 oC for 4 h. It was observed through X-ray diffraction the formation of the spinel phase at temperatures above 700 oC, and through microscopy (SEM) it was observed that MgAl2O4 particles present very small size.

Análise da matriz energética e econômica das culturas de arroz, soja e trigo em sistemas de produção tecnificados no Rio Grande do Sul

A presente analise tem a finalidade de comparar o desempenho entre unidades e atividades produtivas, interligando os parâmetros energeticos aos economicos, sociais e culturais, na gestao dos recursos naturais nos sistemas de producao. Sendo assim, a dissertacao tem como questao norteadora analisar a relacao entre a energia produzida e consumida durante o processo de producao das principais culturas de cereais do Estado do Rio Grande do Sul, a saber: trigo, arroz e soja, em contraposicao aos resultados economicos das respectivas atividades. A pesquisa foi do tipo exploratorio, a partir de estudos de multicaso, com uso de pesquisa bibliografica, analises de laboratorio e entrevistas com produtores. A escolha das unidades de producao estudadas privilegiou as que adotam sistemas produtivos tecnificados, onde se desenvolve a agricultura de precisao e a utilizacao controlada de recursos naturais, como a agua. Para determinar os resultados de analises energeticas foram realizados os balancos energeticos e as eficiencias culturais e energeticas das culturas, ao passo que para os resultados economicos das atividades estudadas foi utilizada a teoria do Valor Agregado. Os resultados demonstram que a atividade da soja, em sistema de plantio direto com rotacao de culturas, alcancou a maior eficiencia energetica, entre 25,58 MJ.ha-1 a 38,39 MJ.ha-1, sendo que a relacao de menor eficiencia foi a cultura do trigo, com 3,13 MJ.ha-1. Em relacao ao desempenho economico das culturas, a soja igualmente mostrou a melhor eficiencia economica 2,47 e o do trigo 1,14 a menor. Cabe destacar os significativos resultados economicos obtidos pela cultura do arroz, expressos pelo alto valor agregado obtido por unidade de area (VAL/ha de R

Implementation of an Indirect Control Structure for Composition in a Hybrid Distillation Column

3.802,00) em funcao de sua alta produtividade fisica. Apesar dos indicadores energeticos serem positivos, houve significativos gastos com fertilizantes, combustiveis e agrotoxicos em todas as propriedades estudadas. Desta forma reforca-se a importância do debate sobre a sustentabilidade socioambiental dos sistemas estudados, principalmente quando analisados sob a otica dos gastos energeticos de bens nao-renovaveis e da problematica social atribuida a mao-de-obra.

Online real-time inference of ethanol composition in a mixed distillation column

In this paper a PID controller is proposed to ensure the fuel ethanol composition at desired value, above 92.5°INPM, at the same time as saving energy through the minimal use of reboiler power. Due to the fact that composition analyzers are expensive and have a high response time, an inference model was developed in which the product composition is inferred from the product temperature and thermodynamics equations, enabling the monitoring and the indirect control a posteriori of this variable. In addition, the inference of composition allows defining the reference value of the product temperature, which ensures the fuel ethanol production at the desired composition.

Environmental and energy analysis of biodiesel production in Rio Grande do Sul, Brazil.

Abstract The main indicator of the distilled ethanol quality is its composition. In general, the online composition analyzers are not available due to their high cost. To overcome the lacking of devices to measure online and at real-time the process composition, we have proposed a soft-sensor to work as a virtual analyzer. Among the techniques available in the literature to achieve this goal, we have chosen the identification and neural networks. Both are used to infer online the ethanol composition through the real-time measured temperatures. According to our results, the neural networks have shown better performance in the composition inference. Further, this technique as soft-sensor was implemented in a SCADA (Supervisory Control And Data Acquisition) software in order to monitor the distilled ethanol composition.