Papers by Dorin Miscenco
Crude glycerol from biodiesel production is the main source for commercial glycerol used in vario... more Crude glycerol from biodiesel production is the main source for commercial glycerol used in various industries. However, existing technologies for crude glycerol processing are economically challenging, especially for small and medium sized biodiesel plants. Historical importance and current markets trends for glycerol production and consumption were briefly analyzed and described in order to predict glycerol market evolution. Due to strict environmental regulations, production of crude glycerol is expected to rise substantially until 2020 creating a great opportunity for economical profit from crude glycerol processing. Today a big effort is being made in research and development for new applications of glycerol in order to adapt the market for glycerol surplus originated by emerging biodiesel industry. This studies present promising results which may generate new potential industrial applications. Development of new applications and efficient processing methods is crucial for stab...
Este documento constitui o modelo de formatação e organização do artigo científico a elaborar no ... more Este documento constitui o modelo de formatação e organização do artigo científico a elaborar no âmbito do trabalho sobre o projecto e análise de um processo em ciclo fechado sob controlo PID. São apresentados os objectivos do trabalho, bem como os critérios de avaliação. 1-Introdução Controlar um qualquer sistema físico envolve projectar o seu controlador, de modo a obter o tipo de resposta desejado ao operador. Em primeira instância, deve definir-se qual dos tipos de controladores vai ser utilizado, sendo para tal usados critérios de desempenho. Idealmente um controlador devia cumprir os seguintes critérios: Ser estável em anel fechado, quaisquer disturbios minimizados, resposta rápida e suave a mudanças de " setpoint " , ausência de " offset " , evitar controlo excessivo e ser robusto, ou seja, insensível a mudanças nas condições do processo e a imprecisões do modelo. Como satisfazer todas estas condições em simultâneo é impossível, pois alguns critérios, em certas situações são mutualmente exclusívos, recorre-se a um tipo de critérios, baseados no erro do controlador, chamados critérios do integral no tempo. Este tipo de critérios assume 3 formas: Integral do erro ao quadrado (" Integral of the Square Error " , ISE) onde, í µí°¼í µí±í µí°¸= ∫ í µí¼ 2 (í µí±¡) ∞ 0 í µí±í µí±¡ [1], Integral do valor absoluto do erro (" Integral of the Absolute value of the Error " , IAE) onde, í µí°¼í µí°´í µí°¸= ∫ |í µí¼(í µí±¡)| ∞ 0 í µí±í µí±¡ [2] e Integral do tempo vezes o erro absoluto (" Integral of the Time-weighted Absolute Error " , ITAE) onde, í µí°¼í µí±í µí°´í µí°¸= ∫ í µí±¡|í µí¼(í µí±¡)| ∞ 0 í µí±í µí±¡ [3]. De modo a determinar qual o melhor controlador, é necessário minimizar o valor do critério escolhido. Este critério é escolhido com base no tipo de resposta que se pretende, sendo que o ISE é melhor que o IAE para suprimir valores elevados da função erro, pois esta está ao quadrado e como tal, contribui mais para o valor do integral, o IAE é melhor que o ISE para suprimir pequenos erros pois a ausência do quadrado para números menores que 1 faz com que o valor do integral seja maior e o ITAE é melhor para suprimir erros que persistem com o tempo, pois inclui a variável tempo dentro do integral. Testando a resposta para os vários tipos de controlador, escolhe-se o controlador cuja resposta melhor cumpre os requisitos de controlo. De seguida, enumeram-se as características gerais de cada tipo de controlo: Acção Proporcional: Acelera a resposta de um processo com controlo e cria um " offset " , ou seja, um desvio em relação ao valor pretendido, ou " setpoint " , excepto para processos cuja função de transferência envolve o termo 1/s (ex.: nível do líquido num tanque, ou a pressão de um gás num contentor). Acção Integral: Elimina por completo o offset, à custa de um maior desvio máximo da resposta em relação ao " setpoint ". Resulta num tipo de resposta lento e oscilatório. No caso de controlo Proporcional-Integral, o aumento de Kc para aumentar a rapidez da resposta pode causar instabilidade do sistema. Acção Derivativa: Prevê os erros, reagindo antecipadamente, diminui o tempo de resposta e confere maior estabilidade a um sistema em anel fechado. Deve-se sempre tentar recorrer, se possível, a um controlador proporcional devido à sua simplicidade, no entanto, poucos são os casos em que tal é possível, e como tal, nestes casos recorre-se a controladores PI, que eliminam o " offset " , embora aumentem o tempo de resposta (os tempos de resposta destes controladores são aceitáveis para casos como o controlo de caudal, onde são muito utilizados). Para sistemas com respostas muito lentas (ex.: controlo de temperatura ou composição), torna-se necessário recorrer a controladores PID, pois usando controladores PI iria aumentar ainda mais o tempo de resposta. A lei de controlo tipicamente usada para um controlador PID (forma paralela) é: í µí±(í µí±¡) = í µí± ̅ + í µí°¾ í µí± [í µí±(í µí±¡) + 1 í µí¼ í µí°¼ ∫ í µí±(í µí±¡ *) í µí±¡ 0 í µí±í µí±¡ * + í µí¼ í µí°· í µí±í µí±(í µí±¡) í µí±í µí±¡ ] [4] , no entanto, para contabilizar a influências dos fenómenos de " kick " proporcional e derivativo, o forma da lei de controlo é alterada, sendo introduzidos dois parâmetros, β e γ, que reflectem o peso que estes fenómenos têm no erro e na variável manipulada. A lei de controlo
Cascata de calor e curva composta global de um conjunto de 10 correntes Relatório do 1º trabalho ... more Cascata de calor e curva composta global de um conjunto de 10 correntes Relatório do 1º trabalho no âmbito da disciplina Resumo – O seguinte trabalho procede à integração energética de um problema de 10 correntes proposto por Briones et. al. em 1999, calculando nomeadamente a cascata de calor e respectiva curva composta global, sendo para o efeito usada uma rotina no MATLAB desenvolvida pelo grupo.
In the current work, gasification is proposed as an alternative to other crude glycerol purificat... more In the current work, gasification is proposed as an alternative to other crude glycerol purification processes. Gasification processes allows energy recovery of crude glycerol but does not involve combustion. In this process, the crude glycerol is introduced as input obtaining syngas as a product, which can be used as an alternative energy source or as a reagent for other processes, due to the high hydrogen content. To evaluate approximate the performance of such a process, simulation studies were performed using the software Aspen Plus 8.6. A fluidized bed reactor configuration was subject to simulation, with the objective of optimising a few key operational parameters, such as temperature and steam-to-glycerol ratio, being the optimized parameters 900°C and 3, respectively. Other design parameters were also determined, such as height, diameter, pressure drop and heat duty, which are 15 m, 0,5 m, 0,8 bar and -184,940 kW, respectively.
Ao longo deste último semestre, durante a realização deste projeto, foram várias as pessoas que d... more Ao longo deste último semestre, durante a realização deste projeto, foram várias as pessoas que de alguma forma contribuíram para a sua realização. Expressamos aqui o nosso agradecimento:
A review of microgeneration of energy from renewable or eficient sources.
Conference Presentations by Dorin Miscenco
Thesis Chapters by Dorin Miscenco
Crude glycerol from biodiesel production is the main source for commercial glycerol
used in vario... more Crude glycerol from biodiesel production is the main source for commercial glycerol
used in various industries. However, existing technologies for crude glycerol processing are economically challenging, especially for small and medium sized biodiesel
plants.
Historical importance and current market trends for glycerol production and consumption were briefly analyzed and described in order to predict glycerol market evolution. Due to strict environmental regulations, production of crude glycerol is expected to rise substantially until 2020 creating a great opportunity for economical profit
from crude glycerol processing. Today a big effort is being made in research and development for new applications of glycerol in order to adapt the market for glycerol
surplus originated by emerging biodiesel industry. These studies present promising results which may generate new potential industrial applications. Development of new
applications and efficient processing methods is crucial for stability in future glicerol
market.
This dissertation was elaborated in collaboration with a local small biodiesel producer. A purification process for low quality crude glycerol, based on physical and
chemical separation steps was developed using experimental data. Economical feasibility of the process was analyzed and tested for various market scenarios.
A simple and cheap experimental procedure for glycerol purification was developed and described in order to provide simple and reproducible instructions for
quality and process control in related future studies and process implementation. The
most important results for the purification steps were presented. Using the proposed
separation sequence, efective removal of Mater-Organic-Non-Glycerol (MONG) impurities and decolorization was observed. A yeild of approximately 50 % (% wt.) was
obtained and a purity of the final product up to 94% glycerol was achieved. However, the ash content was only slightly reduced since the product still presents significant amounts of salts 3-4 %. Various techniques were used to indirectly characterize
che-mical compositions of the obtained samples presenting simple and reasonably accurate methods for crude glycerol characterization. Methods like Thermo-Gravimetric
Analysis, Elemental Analysis and chemical tritation are very useful tools in low-cost
industrial applications.
Finally, the economical feasibility was analyzed for various market conditions in
order to define the most profitable process configuration. A discontinuous, easy scalable, simple and relatively cheap process was designed in order to evaluate necessary capital investment, which is estimated near 1 million euros. It was concluded
that the proposed process sequence is economically viable with present market prices,
presen-ting a Net Present Value at the end of the project of 455 thousands euros. It was
also noted that for 10 times the base capacity the profitability is much higher giving
a final NPV of approximately 11 million euros, showing great economical interest for
medium-sized biodiesel plants or even for plants dedicated solely for crude glycerol
processing, which can yield large profits especially when large quantity of cheap crude
glycerol is available.
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Papers by Dorin Miscenco
Conference Presentations by Dorin Miscenco
Thesis Chapters by Dorin Miscenco
used in various industries. However, existing technologies for crude glycerol processing are economically challenging, especially for small and medium sized biodiesel
plants.
Historical importance and current market trends for glycerol production and consumption were briefly analyzed and described in order to predict glycerol market evolution. Due to strict environmental regulations, production of crude glycerol is expected to rise substantially until 2020 creating a great opportunity for economical profit
from crude glycerol processing. Today a big effort is being made in research and development for new applications of glycerol in order to adapt the market for glycerol
surplus originated by emerging biodiesel industry. These studies present promising results which may generate new potential industrial applications. Development of new
applications and efficient processing methods is crucial for stability in future glicerol
market.
This dissertation was elaborated in collaboration with a local small biodiesel producer. A purification process for low quality crude glycerol, based on physical and
chemical separation steps was developed using experimental data. Economical feasibility of the process was analyzed and tested for various market scenarios.
A simple and cheap experimental procedure for glycerol purification was developed and described in order to provide simple and reproducible instructions for
quality and process control in related future studies and process implementation. The
most important results for the purification steps were presented. Using the proposed
separation sequence, efective removal of Mater-Organic-Non-Glycerol (MONG) impurities and decolorization was observed. A yeild of approximately 50 % (% wt.) was
obtained and a purity of the final product up to 94% glycerol was achieved. However, the ash content was only slightly reduced since the product still presents significant amounts of salts 3-4 %. Various techniques were used to indirectly characterize
che-mical compositions of the obtained samples presenting simple and reasonably accurate methods for crude glycerol characterization. Methods like Thermo-Gravimetric
Analysis, Elemental Analysis and chemical tritation are very useful tools in low-cost
industrial applications.
Finally, the economical feasibility was analyzed for various market conditions in
order to define the most profitable process configuration. A discontinuous, easy scalable, simple and relatively cheap process was designed in order to evaluate necessary capital investment, which is estimated near 1 million euros. It was concluded
that the proposed process sequence is economically viable with present market prices,
presen-ting a Net Present Value at the end of the project of 455 thousands euros. It was
also noted that for 10 times the base capacity the profitability is much higher giving
a final NPV of approximately 11 million euros, showing great economical interest for
medium-sized biodiesel plants or even for plants dedicated solely for crude glycerol
processing, which can yield large profits especially when large quantity of cheap crude
glycerol is available.
used in various industries. However, existing technologies for crude glycerol processing are economically challenging, especially for small and medium sized biodiesel
plants.
Historical importance and current market trends for glycerol production and consumption were briefly analyzed and described in order to predict glycerol market evolution. Due to strict environmental regulations, production of crude glycerol is expected to rise substantially until 2020 creating a great opportunity for economical profit
from crude glycerol processing. Today a big effort is being made in research and development for new applications of glycerol in order to adapt the market for glycerol
surplus originated by emerging biodiesel industry. These studies present promising results which may generate new potential industrial applications. Development of new
applications and efficient processing methods is crucial for stability in future glicerol
market.
This dissertation was elaborated in collaboration with a local small biodiesel producer. A purification process for low quality crude glycerol, based on physical and
chemical separation steps was developed using experimental data. Economical feasibility of the process was analyzed and tested for various market scenarios.
A simple and cheap experimental procedure for glycerol purification was developed and described in order to provide simple and reproducible instructions for
quality and process control in related future studies and process implementation. The
most important results for the purification steps were presented. Using the proposed
separation sequence, efective removal of Mater-Organic-Non-Glycerol (MONG) impurities and decolorization was observed. A yeild of approximately 50 % (% wt.) was
obtained and a purity of the final product up to 94% glycerol was achieved. However, the ash content was only slightly reduced since the product still presents significant amounts of salts 3-4 %. Various techniques were used to indirectly characterize
che-mical compositions of the obtained samples presenting simple and reasonably accurate methods for crude glycerol characterization. Methods like Thermo-Gravimetric
Analysis, Elemental Analysis and chemical tritation are very useful tools in low-cost
industrial applications.
Finally, the economical feasibility was analyzed for various market conditions in
order to define the most profitable process configuration. A discontinuous, easy scalable, simple and relatively cheap process was designed in order to evaluate necessary capital investment, which is estimated near 1 million euros. It was concluded
that the proposed process sequence is economically viable with present market prices,
presen-ting a Net Present Value at the end of the project of 455 thousands euros. It was
also noted that for 10 times the base capacity the profitability is much higher giving
a final NPV of approximately 11 million euros, showing great economical interest for
medium-sized biodiesel plants or even for plants dedicated solely for crude glycerol
processing, which can yield large profits especially when large quantity of cheap crude
glycerol is available.