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No presente trabalho foi realizada uma simulação computacional em ambiente Aspen Plus V8.4 da produção de biodiesel a partir de uma alimentação de óleo com elevado teor de ácidos gordos livres em solução. A conversão em biodiesel foi determinada pela cinética química, com recurso a dados cinéticos obtidos na literatura, sendo que as espécies eletrolíticas participantes do processo também foram levadas em conta nas etapas reacionais. O processo simulado é composto por três etapas. As duas primeiras constituem a etapa reacional, sendo a terceira etapa relativa à separação e purificação. A etapa reacional foi dividida na esterificação ácida e na transesterificação alcalina. Na primeira, os ácidos gordos livres em solução são convertidos em biodiesel e na segunda, a corrente de óleos, agora com um teor residual de ácidos gordos livres, é convertida em biodiesel. Na última etapa o biodiesel é purificado, diminuindo-se o seu teor em água e metanol. Nesta etapa também se procede à separação e recuperação do metanol e glicerol utilizados em diferentes pontos do processo. Assim, foram alimentados ao processo uma corrente de 1000 kg/h de óleo, com 25% em massa de ácidos gordos livres. A conversão desta corrente resultou em 952 kg/h de uma corrente de biodiesel com uma pureza mássica de 97,36%. Para além dos óleos, foram também alimentados ao processo 670 kg/h de metanol, 10 kg/h de ácido sulfúrico concentrado (98%), 5 kg/h de hidróxido de sódio sólido, 100 kg/h de glicerol e 500 kg/h de água para lavagem. Do metanol alimentado ao processo foram consumidos cerca de 16% em massa nas etapas reacionais e recuperados, cerca de 63%, da corrente de alimentação, no final do processo, com uma pureza mássica de 96%. O processo de transesterificação alcalina produz cerca de 76% do glicerol alimentado, sendo este recuperado praticamente na totalidade no final do processo com uma pureza mássica de cerca de 80%. A conversão dos ácidos gordos livres na etapa de esterificação ácida foi de 98,89%. Relativamente aos óleos, a conversão obtida para os mesmos na etapa de transesterificação alcalina, foi de 96.41%. A potência térmica consumida para se purificar o biodiesel produzido e recuperar o metanol e glicerol, foi de 202 kW.
In the present work a computer simulation was performed in Aspen Plus V8.4 environment, for the production of biodiesel using an oil feed with a high content of free fatty acids in solution. The conversion to biodiesel was determined by chemical kinetics using literature data and the electrolytic species involved in the process were also taken into account in the reaction stages. The simulated process consists of three steps. The first two constitute the reactional step, the third stage being the separation and purification phase. The reaction step was divided into acid esterification and alkaline transesterification. In the former, the free fatty acids in solution were converted to biodiesel, and in the second, the oil stream, now with a residual content of free fatty acids, is converted into biodiesel. In the last step the biodiesel is purified, reducing its content in water and methanol. This step also separates and recovers methanol and glycerol used at different points in the process. Thus, a stream of 1000 kg/h of oil, with 25% by weight of free fatty acids, was fed into the process. The conversion of this stream resulted in 952 kg/h of a biodiesel stream with a mass purity of 97.83%. 670 kg/h of methanol, 10 kg/h of concentrated sulfuric acid (98%), 5 kg/h of solid sodium hydroxide, 100 kg/h of glycerol and 500 kg/h of water for washing, were also fed into the process. From the methanol fed to the process, about 16% by mass was consumed in the reaction steps and about 63% of the feed stream was recovered at the end of the process, with a mass purity of 96%. The alkaline transesterification process produces about 76% of the fed glycerol, which is recovered substantially at the end of the process with a mass purity of about 80%. Conversion of the free fatty acids in the acid esterification step was 98.89%. Regarding the oils, the conversion obtained for them in the alkaline transesterification step was 96.41%. The thermal power consumed to purify the produced biodiesel and recover the methanol and glycerol, was 202 kW.
In the present work a computer simulation was performed in Aspen Plus V8.4 environment, for the production of biodiesel using an oil feed with a high content of free fatty acids in solution. The conversion to biodiesel was determined by chemical kinetics using literature data and the electrolytic species involved in the process were also taken into account in the reaction stages. The simulated process consists of three steps. The first two constitute the reactional step, the third stage being the separation and purification phase. The reaction step was divided into acid esterification and alkaline transesterification. In the former, the free fatty acids in solution were converted to biodiesel, and in the second, the oil stream, now with a residual content of free fatty acids, is converted into biodiesel. In the last step the biodiesel is purified, reducing its content in water and methanol. This step also separates and recovers methanol and glycerol used at different points in the process. Thus, a stream of 1000 kg/h of oil, with 25% by weight of free fatty acids, was fed into the process. The conversion of this stream resulted in 952 kg/h of a biodiesel stream with a mass purity of 97.83%. 670 kg/h of methanol, 10 kg/h of concentrated sulfuric acid (98%), 5 kg/h of solid sodium hydroxide, 100 kg/h of glycerol and 500 kg/h of water for washing, were also fed into the process. From the methanol fed to the process, about 16% by mass was consumed in the reaction steps and about 63% of the feed stream was recovered at the end of the process, with a mass purity of 96%. The alkaline transesterification process produces about 76% of the fed glycerol, which is recovered substantially at the end of the process with a mass purity of about 80%. Conversion of the free fatty acids in the acid esterification step was 98.89%. Regarding the oils, the conversion obtained for them in the alkaline transesterification step was 96.41%. The thermal power consumed to purify the produced biodiesel and recover the methanol and glycerol, was 202 kW.
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Keywords
Biodiesel Produção de Biodiesel Óleo com elevado teor de ácidos gordos livres Simulação da Produção de Biodiesel em Aspen Plus V8.4. Biodiesel production Oil with high free fatty acid content Simulation of Biodiesel Production in Aspen Plus V8.4.