Estudo da correção do fator de potência em pontos de conexão entre as redes básica e de distribuição

TCC (graduação) - Universidade Federal de Santa Catarina. Centro Tecnológico. Engenharia Elétrica.O fator de potência de pontos de conexão entre as redes básica e de distribuição, quando não corrigido, pode influenciar negativamente o custo da operação e a segurança da operação do sistema elétrico. Neste sentido, este estudo propõe analisar esse parâmetro em toda a região Sul do Brasil durante o ano de 2018, e avaliar dois procedimentos para compreender o impacto econômico da conjuntura estabelecida. O primeiro procedimento consistiu na contabilização dos custos gerados e do estudo da viabilidade técnica, caso o Operador Nacional do Sistema Elétrico corrigisse o fator de potência nos pontos de conexão utilizando os serviços ancilares de compensação reativa de usinas hidráulicas. O segundo procedimento avaliou os custos evitados, caso os agentes de distribuição corrigissem tal parâmetro pelo desligamento de bancos de capacitores ou pela instalação de reatores. Focou-se na análise de regime permanente por meio da utilização do programa de fluxo de potência convencional ANAREDE. Os resultados obtidos evidenciaram que a correção do fator de potência mediante serviço ancilar de manejo de reativo é inviável ao considerar a complexidade do sistema elétrico. Além disso, constatou-se que a administração correta de bancos de capacitores ou emprego de reatores para correção do fator de potência possibilita a flexibilização das máquinas síncronas no manejo de reativo. Isso promove maior folga na curva de capabilidade das usinas, aumentando a performance do controle de tensão, e consequentemente, maior contribuição para um sistema elétrico mais robusto em caso de contingências, além, da redução de gastos com os serviços ancilares, o que acarreta em economia e maior segurança para o sistema elétrico.The lack of a power factor correction of connection points between transmission and distribution grids can lead to a negative impact on the economy and the security of the electric power system operation. In this context, this study proposes to analyze the influence of this parameter in South Brazil during the year 2018. In addition, it intends to evaluate two procedures to understand the economic impacts of the established situation. The first procedure consisted of a cost assessment and the technical analysis in case of a correction of the power factor at the connection points by the National Electric System Operator through an ancillary service of reactive power compensation. The second procedure assessed the avoided expenses in case of this parameter correction by the distribution network operators through shutdown of capacitor banks and reactor installations. The study was focused on the analysis of the steady state by the use of the Network Analysis Program - ANAREDE. The generated results made evident, that the power factor correction by means of ancillary service for reactive power compensation is unviable, when the complexity of the electric grid is considered. Besides, it was verified that the correct management of capacitor banks or introduction of reactors for the power factor correction enable the synchronous generator flexibilization of the reactive power flow control. It promotes a higher actuation of the synchronous generator on the voltage control and consequently contributes to a more prepared electric power grid in case of contingency. Moreover, it assures the reduction of expenses for the ancillary services. These two points result in more profits and insurance for the electric power system

Erhöhung der Wertschöpfung von Jatropha curcas L. Nüssen durch die Entwicklung verbesserter Verfahren zur Ölraffination und Proteinextraktion

Das wachsende Bewusstsein um die Umweltprobleme, welche durch einen steigenden Lebensstandard verursacht werden, führte zu einem Umdenken hinsichtlich der Nutzung natürlicher Ressourcen und der Nachhaltigkeit industrieller Prozesse. In den letzten Jahrzehnten stieg daher das Interesse an der nicht essbaren tropischen Ölpflanze Jatropha curcas L. Um ihre nachhaltige Nutzung zu gewährleisten, beschäftigt sich diese Arbeit mit der Entwicklung alternativer enzymatischer Prozesse zur Ölraffination sowie zur Extraktion und Verwertung der Proteine, dem wertvollsten Nebenprodukt der Ölgewinnung aus Jatropha Saat. Die enzymatische Entschleimung von Jatropha-Rohöl mittels Lecitase® Ultra ermöglichte eine Reduktion des Phosphorgehaltes im Öl unter 4 ppm. Die enzymatische Entsäuerung wurde durch Veresterung der freien Fettsäuren mit Glycerin unter Verwendung einer immobilisierten Lipase aus Rhizomucor miehei erreicht. Zunächst wurden die kritischen Einflussparameter auf die Reaktion ermittelt. Anschließend erfolgte eine Prozessoptimierung mittels statistischer Versuchsplanung. Der Prozess ermöglicht eine Reduktion der Säurezahl auf 0.3 mg KOH pro g Öl. Die restlichen Fettsäuren können leicht über die folgenden Raffinationsschritte abgetrennt werden. Die Kinetik der enzymatischen Entsäuerungsreaktion scheint einem Ping Pong Mechanismus mit dead-end Hemmung durch den Acylakzeptor Glycerin zu folgen. Die Regeneration der Lipase mittels Isopropanol und n-Hexan stellte sich als vielversprechend heraus und ermöglichte eine Wiederverwendung des Enzyms in 13 Zyklen. Um das Protein aus wässrig extrahiertem oder gepresstem Jatropha Rückstand zu extrahieren wurden ein wässriger sowie ein enzymatischer Prozess entwickelt. Dabei wurden Proteinausbeuten von 75% erreicht. Anschließend wurden verschiedene Methoden zur Proteingewinnung und –aufreinigung entwickelt und bewertet. Die Proteine weisen vielversprechende Emulgier- und Gelbildungseigenschaften auf. Sie zeigen jedoch kein Schaumbildungsvermögen. Die Funktionalität der enzymatisch extrahierten Proteine ist geringer als die der wässrig extrahierten Proteine. Jatropha Proteine weisen ein hohes Potential auf in technischen Anwendungen, z.B. als Emulgatoren, in bioabbaubaren Mülltüten oder als Antischaummittel eingesetzt zu werden. Die vorliegende Arbeit zeigte, dass Jatropha curcas eine vielversprechende Öl- und Proteinquelle für technische Anwendungen sein kann.The awareness of environmental problems caused by an increasing standard of living lead to a revised view on industrial processes and the handling of resources. During the last decades, the tropical, non-edible plant Jatropha curcas L. became a focus of interest especially with respect to its high oil content. In order to increase the sustainability of its utilization the present work deals with the establishment of alternative enzymatic processes for the oil refining as well as with the extraction and application of the protein, the most valuable by-product inherent to the residues left after oil extraction from the Jatropha seeds. Enzymatic degumming of crude Jatropha oil was performed successfully applying Lecitase® Ultra. Phosphor content can be decreased below 4 ppm. Enzymatic neutralization was achieved esterifying the free fatty acids with glycerol by an immobilized lipase from Rhizomucor miehei. Initially, the crucial influencing parameters were determined and afterwards the reaction was optimized by the help of a statistical design of experiments. The process allows acid number reduction to 0.3 mg KOH per g of oil. Residual fatty acids are easily removed within the following refining steps. According to a kinetic investigation, the enzymatic neutralization is expected to follow a Ping Pong mechanism with dead end inhibition by the acyl-acceptor glycerol. Enzyme regeneration was also investigated and found to be most effective applying isopropanol and n-hexane allowing a reutilization of the enzyme in at least 13 cycles. In order to extract the protein from aqueous-extracted as well as from screw-pressed Jatropha residue an aqueous and an enzyme-assisted process were developed. Protein yields of about 75% were obtained. Different methods for protein recovery and purification subsequent to protein extraction were performed and evaluated. In principle, Jatropha proteins show good emulsifying as well as gelation behaviour. No foam forming capacity is measured. The functionality of enzymatically extracted protein is minor to the functionality of aqueous-extracted protein. Jatropha protein owns potential for its utilization in technical applications such as emulsifiers, biodegradable bags or antifoam reagent. The current work revealed Jatropha curcas as a promising source of oil and protein to be valorized for their use in technical applications

Vertragsschluss und Vertragsbindung bei Verbraucherverträgen | Zugleich eine Untersuchung der Schutzmechanismen bei Internetgeschäften anhand von § 312j Abs. 2 bis 4 BGB

Durch die zunehmende Verbreitung des Versandhandels über das Internet hat sich gleichzeitig das Problem der Kostenfallen entwickelt. Eine Vielzahl von Verbrauchern ist davon betroffen. Darüber hinaus entstehen jedes Jahr Schäden in Millionenhöhe. Durch die Umsetzung der Verbraucherrechterichtlinie wurde explizit zum Schutz vor Kostenfallen § 312j Abs. 3 und 4 BGB erlassen. Die Vorschrift ist auf Verbraucherverträge anzuwenden und geht nur dann von einem wirksamen Vertrag im elektronischen Geschäftsverkehr aus, wenn die Gestaltungsvorgaben hinsichtlich eines deutlichen Hinweises auf die Entgeltlichkeit einer Dienstleistung eingehalten worden sind.Im Rahmen der Untersuchung werden zum einen Schwachstellen des § 312j Abs. 3 und 4 BGB sowie grundlegende Probleme des Verbraucherschutzrechts aufgezeigt, die zugleich Auswirkungen auf das Problem der Kosten- bzw. Abonnementfallen haben. Eine stetige Fortentwicklung des Verbraucherschutzrechts ist unabdingbar

Kinetics of enzymatic esterification of glycerol and free fatty acids in crude Jatropha oil by immobilized lipase from Rhizomucor miehei

Enzymatic neutralization is a recent research focus due to an increasing awareness of environmental problems caused by conventional oil refining. This study investigated the kinetics of enzymatic neutralization in crude Jatropha oil utilizing an immobilized lipase from Rhizomucor miehei. Free fatty acids, in particular oleic acid were esterified with glycerol. The reaction seems to follow a multisubstrate Ping Pong mechanism with competitive inhibition by the acyl acceptors (mono-, diacylglycerides and glycerol). Free fatty acid content did not affect lipase activity within the ranges investigated. The kinetic parameters were determined and showed that enzyme affinity is much higher to glycerol than to free fatty acids. These observations were supported by the fact that the optimum glycerol level is rather small while the reaction rate increases with increasing free fatty acid concentration

Enzyme-assisted deacidification of Jatropha crude oil by statistical design of experiments

Jatropha curcas L. crude oil has variable and often high free fatty acid content. As free fatty acids are corrosive, the crude oil has to be refined prior to its utilization in technical applications. Conventional refining processes have several environmental and energetic shortcomings, and there is a clear need for more sustainable pathways. In this study, an enzymatic method was studied for the neutralization of Jatropha oil. Detailed insight into the process was achieved by means of a statistical design of experiments utilizing an immobilized lipase from Rhizomucor miehei. The free fatty acids were esterified with glycerol. The most important impact factors and interactions between factors were identified with regard to acid number reduction and the MAG, DAG, and glycerol content. Validation experiments showed that the models obtained for acid number and, mono- and DAG development were valid and adequate for optimizing the esterification reaction for the desired application. The results generated in this study open the possibility of modifying – within limits – the vegetable oil composition depending on the target application requirements. The acid number of the crude Jatropha oil could be decreased to 0.4 mg KOH per g oil by means of enzymatic esterification. The MAG content can be adjusted between 1.5 and 5.0% (w/w) and DAG content between 15.6 and 27.1% (w/w). The enzyme regeneration procedure that was developed allows multiple use of the enzyme at practically constant activity. Practical applications: Due to the advantages of an enzyme-assisted neutralization procedure, future industrial application of this technology is of great interest. Higher oil yields, no generation of waste water, and the avoidance of aggressive chemicals mean this process has greater sustainability than the conventional approach requiring the addition of strong bases to the oil in order to saponify the free fatty acids. Currently, enzymatic processes tend not to be economically viable due the relatively high cost of the enzymes. However, the costs are likely to decrease in the future as demand for them increases. Additionally, enzyme regeneration, which was carried out successfully in this work, offers the opportunity to further lower the process costs