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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
11

Aspectos ambientais do co-processamento de resíduos em fornos de produção de clínquer no Estado de São Paulo / Environmental aspects of the co-processing in cement clinker kilns in the State of São Paulo

Mantegazza, Ezio 08 December 2004 (has links)
A geração de resíduos sólidos é inerente ao desenvolvimento humano. O concreto armado é um dos materiais mais utilizados pelo homem e tem o cimento Portland como seu principal constituinte, o qual é produzido pela moagem de clínquer e gesso. O clínquer pode ser definido como um mineral artificial, obtido a partir das reações físico-químicas de calcário, argila e corretivos a altas temperaturas, em forno rotativo industrial, mediante a queima de combustíveis fósseis. No início da década de 70 foram realizadas as primeiras experiências de substituição de combustíveis fósseis por resíduos industriais nos Estados Unidos e países europeus, através da técnica denominada co-processamento, resultando na manufatura de um produto ao mesmo tempo em que os resíduos eram eliminados. O co-processamento se baseia na recuperação da energia disponível nos resíduos, substituindo parte daquela fornecida pelos combustíveis tradicionais ou na substituição de matérias-primas por resíduos com características químicas semelhantes àquelas normalmente empregadas na produção do clínquer. No estado de São Paulo as primeiras iniciativas para a utilização de resíduos industriais em fornos de clínquer ocorreram no início da década de 90. A partir de 1997 os órgãos ambientais de alguns estados brasileiros normatizaram procedimentos de licenciamento da atividade que foi, posteriormente, uniformizada por norma em âmbito federal. No ano de 1995 a Companhia de Cimento Ribeirão Grande/SP, Brasil, iniciou os procedimentos visando a substituição parcial dos combustíveis utilizados nos fornos rotativos por uma mistura de resíduos industriais. No período de 1995 a 2002 foram realizadas campanhas de amostragens em chaminés para avaliação das emissões atmosféricas dos dois fornos de produção de clínquer. A análise dos resultados obtidos associada às demais informações disponíveis de monitoramento das características das matérias-primas e combustíveis utilizados, bem como dos produtos finais, clínquer e cimento, não evidenciou alterações significativas nos níveis de emissões atmosféricas, sobretudo de material particulado e óxidos de enxofre, que pudessem ser associadas à utilização dos resíduos. Foram confirmadas as baixas emissões de inorgânicos e evidenciado o papel representado pelos resíduos no aporte dessas substâncias no sistema-forno, concluindo-se que esse aporte pode ser tão ou mais importante pela via da alimentação da farinha, cujos teores estão associados às características das jazidas minerais utilizadas. Foi também confirmada a alta eficiência do sistema-forno na destruição e remoção dos compostos orgânicos perigosos alimentados durante os testes de queima. / The production of industrial residues in inherent to the human development. The cement concrete is one of the most used material, manly the type portland cement, which is constituted by grinding clinker and gypsum together. Clinker can be defined as an artificial mineral obtained by applying physico-chemical reactions, at very high temperatures, to an appropriated mixture of limestone, clay, and some other materials in a rotating industrial kiln wich burns fossil fuels. In the early 1970 decade occurred the first experiences substituting fossil fuels by organic residues in USA and Europe through a technique named co-processing that results the production of certain manufacture while eliminates residues. Co-processing is based in the recovery of thermal energy and/or the mass of some constituents from some residues, with the same chemical characteristics of normal sources of energy, then economizing fuels and mass constituents and making better use of residues, otherwise useless and environmentally polluters. In the state of São Paulo this practice began in early 1990 decade and by 1997 it was started the standardization of the rules for its use in some units of the federation. Later this activity was regulated by nationally approved standard rules. In 1995 the industry Companhia de Cimento Ribeirão Grande (CCRG), a cement plant located in the city of Ribeirão Grande, São Paulo state, Brazil, started procedures searching the partial substitution of the normal fuels by a mixture of industrial residues in its two rotating kilns. The gaseous emissions from the chimneys of these two clinker kilns were studied from 1995 to 2002 about the use of residues as part of the fuel. Analyses of the final results associated with other informations concerning to the quality of raw minerals, fuels and products did not show significant alterations in atmospheric emissions, mainly for particulate material and sulfur oxides, related with the use of residues. The emissions of inorganic continued to be low and not significantly altered by the presence of residues. It was possible to conclude that the alterations in inorganic emissions depend more from the quality of the raw minerals feed in the kilns, which is more difficult to control, than from the presence of residues being burn with the fuel. It was shown a high efficiency in the destruction of dangerous organic compounds feed in the cement kilns, under test conditions.
12

Μοντελοποίηση, έλεγχος και διάγνωση σφαλμάτων κινητήριου συστήματος αποτελούμενου από δύο ασύγχρονες μηχανές με κοινό φορτίο κλίβανο τσιμεντοβιομηχανίας

Μπογιατζίδης, Ιωάννης 02 March 2015 (has links)
Το κεφάλαιο 1 αποτελεί εισαγωγή του αναγνώστη σε θέματα που αφορούν τα ηλεκτρικά κινητήρια συστήματα. Αρχικά πραγματοποιείται μια σύντομη ιστορική αναδρομή και περιγραφή της εξέλιξης αυτών, ενώ στη συνέχεια παρουσιάζονται οι θεματικές ενότητες που αποτελούν τη συμβολή της παρούσας διατριβής όπως ο έλεγχος των κινητήριων συστημάτων και η διάγνωση σφαλμάτων σε αυτά. Τέλος, υπογραμμίζονται οι στόχοι που ορίστηκαν και εκπληρώνονται στο πλαίσιο της εργασίας αυτής. Στο κεφάλαιο 2 γίνεται μια γενική περιγραφή των σταδίων παραγωγής τσιμέντου, παρουσιάζεται η χαρακτηριστική ροπής-στροφών του κλιβάνου με βάση τη διαθέσιμη βιβλιογραφία, αναλύονται λεπτομερώς οι τοπολογίες συστημάτων μετάδοσης που εγκαθίστανται σε κλιβάνους μικρής και μεγάλης παραγωγικής δύναμης, αναδεικνύονται οι προδιαγραφές που υφίστανται κατά την επιλογή των ηλεκτρικών κινητήριων μηχανών και τέλος τονίζονται οι απαιτήσεις του ελέγχου των κινητήριων μηχανών, έτσι όπως τίθενται από τη βιομηχανία τσιμέντου. Στο κεφάλαιο 3 περιγράφεται το μαθηματικό μοντέλο που αναπτύχθηκε και χρησιμοποιήθηκε για την προσομοίωση της λειτουργίας του συστήματος και το οποίο απαρτίζεται από τα επιμέρους μοντέλα του κλιβάνου, του συστήματος μετάδοσης της κίνησης, των τριφασικών ασύγχρονων μηχανών, των ηλεκτρονικών μετατροπέων ισχύος καθώς και του ελέγχου των κινητήριων μηχανών. Στο κεφάλαιο 4 περιγράφονται τα υποσυστήματα του υπό κλίμακα συστήματος με σκοπό την εξομοίωση, που κατασκευάστηκε στο εργαστήριο με στόχο την επαλήθευση των αποτελεσμάτων της προσομοίωσης στον ηλεκτρονικό υπολογιστή. Στο κεφάλαιο 5 γίνεται λεπτομερής αναφορά στις υφιστάμενες τεχνικές ελέγχου των τριφασικών ασύγχρονων μηχανών και στις εφαρμογές αυτών σε μονά και διπλά κινητήρια συστήματα. Στη συνέχεια πραγματοποιείται σύγκριση δύο εκ των επικρατέστερων μεθόδων ελέγχου διπλών κινητήριων συστημάτων και παρουσιάζονται ενδεχόμενες δυσλειτουργίες αυτών λαμβάνοντας υπόψη τα αποτελέσματα που προέκυψαν από την προσομοίωση του συστήματος και τα οποία πιστοποιούνται μέσω της πειραματικής διαδικασίας αλλά και της διαθέσιμης βιβλιογραφίας. Στη συνέχεια προτείνεται ένας καινοτόμος υβριδικός έλεγχος που, όπως αποδεικνύεται μέσω προσομοίωσης αλλά και πειραματικών αποτελεσμάτων, αντιμετωπίζει αποτελεσματικά τις προαναφερθείσες δυσλειτουργίες οδηγώντας σε ομαλή λειτουργία του συστήματος. Στο κεφάλαιο 6 προτείνεται, αντί των υφιστάμενων μεθόδων που περιλαμβάνουν την εγκατάσταση επιταχυνσιομέτρων, τη χρήση ακουστικών σημάτων και άλλων παρόμοιων μεθόδων, η χρήση της ηλεκτρικής κινητήριας μηχανής (τριφασικής ασύγχρονης μηχανής στην προκειμένη περίπτωση) ως αισθητήριο μέσο για τη διάγνωση μηχανολογικών σφαλμάτων στις οδοντώσεις γραναζιών. Συγκεκριμένα, εξετάζεται η επίδραση των εν λόγω σφαλμάτων στο φάσμα συχνοτήτων του φασικού ρεύματος και της ηλεκτρομαγνητικής ροπής της τριφασικής ασύγχρονης μηχανής, αποδεικνύεται η δυνατότητα διάγνωσης του σφάλματος ανιχνεύοντας την ύπαρξη πολλαπλών αρμονικών στο φάσμα τόσο του φασικού ρεύματος όσο και της ηλεκτρομαγνητικής ροπής. Στο κεφάλαιο 7 γίνεται μια εκτίμηση σε ό,τι αφορά τη συμβολή της διδακτορικής διατριβής, το κεφάλαιο 8 περιλαμβάνει μία ανά κεφάλαιο περίληψη της παρούσας διατριβής ενώ το κεφάλαιο 9 περιέχει τη διαθέσιμη βιβλιογραφία που χρησιμοποιήθηκε στην παρούσα εργασία κατά τη σειρά αναφοράς της στο κείμενο. / This thesis deals with the modeling, the control and the diagnosis of mechanical faults in a dual ac drive with common mechanical load. Chapter 1 constitutes an introduction of the reader to the electrical drive systems. Initially, a short historical retrospection of these systems is realized, while afterwards the thematic units that constitute the contributions of the present thesis, which can be summarized as the control of a dual cement kiln drive and the diagnosis of mechanical gear faults using the ac motor as a sensor, are presented. In chapter 2 the specifications and the operational characteristics of the kiln drive system are presented based on the industrial requirements and the existing references. Particularly the torque – speed characteristic load curve of the kiln, the advantages of upgrading the dc drives with ac ones, the parameters which determine the decision of installing a single or a dual transmission system and the need of uninterrupted operation of the kiln drive are underlined. In addition the step by step development of a simulating model of the under study system in the Matlab/Simulink environment is presented in chapter 3. Particularly the equations of motion for the kiln and the transmission system, the dynamic model equations of the asynchronous motor, the power electronics converters and the control strategy based on the Direct Torque Control have been incorporated in the Matlab/Simulink environment through which a theoretical investigation is realized. Moreover, the design and the development of an under scale laboratory simulating system of the kiln drive has been realized and the characteristics of the design specifications of the laboratory system are presented in chapter 4. Using the theoretical model developed in the Matlab/Simulink environment and the laboratory simulating system, a comparison of the existing control methods used for the electric drive systems (speed control and torque control) is being presented (chapter 5), focusing at specific malfunctions which can be caused by the application of these controls at a dual cement kiln drive. Taking into account these malfunctions, a novel hybrid control method is being presented whose operation is based on the application of a parallel-hybrid speed and torque control, simultaneously at both electric motors. In this way an equal load distribution can be achieved, obviating at the same the appearance of mechanical malfunctions. In chapter 6, the fault diagnosis of electromechanical drives is referenced, focusing on the identification of mechanical faults appeared in the pinion/girth gear coupling using the ac motor as a sensor. The proposed diagnostic method is based on the detection of multiples of the defective frequency at both phase current and electromagnetic torque frequency spectrum. The effectiveness of the proposed method is verified using experimental results from the laboratory simulating system, operating as a single drive. Finally, chapter 7, 8 and 9 include an estimation of the thesis contribution, a summary and the reference part respectively.
13

Aspectos ambientais do co-processamento de resíduos em fornos de produção de clínquer no Estado de São Paulo / Environmental aspects of the co-processing in cement clinker kilns in the State of São Paulo

Ezio Mantegazza 08 December 2004 (has links)
A geração de resíduos sólidos é inerente ao desenvolvimento humano. O concreto armado é um dos materiais mais utilizados pelo homem e tem o cimento Portland como seu principal constituinte, o qual é produzido pela moagem de clínquer e gesso. O clínquer pode ser definido como um mineral artificial, obtido a partir das reações físico-químicas de calcário, argila e corretivos a altas temperaturas, em forno rotativo industrial, mediante a queima de combustíveis fósseis. No início da década de 70 foram realizadas as primeiras experiências de substituição de combustíveis fósseis por resíduos industriais nos Estados Unidos e países europeus, através da técnica denominada co-processamento, resultando na manufatura de um produto ao mesmo tempo em que os resíduos eram eliminados. O co-processamento se baseia na recuperação da energia disponível nos resíduos, substituindo parte daquela fornecida pelos combustíveis tradicionais ou na substituição de matérias-primas por resíduos com características químicas semelhantes àquelas normalmente empregadas na produção do clínquer. No estado de São Paulo as primeiras iniciativas para a utilização de resíduos industriais em fornos de clínquer ocorreram no início da década de 90. A partir de 1997 os órgãos ambientais de alguns estados brasileiros normatizaram procedimentos de licenciamento da atividade que foi, posteriormente, uniformizada por norma em âmbito federal. No ano de 1995 a Companhia de Cimento Ribeirão Grande/SP, Brasil, iniciou os procedimentos visando a substituição parcial dos combustíveis utilizados nos fornos rotativos por uma mistura de resíduos industriais. No período de 1995 a 2002 foram realizadas campanhas de amostragens em chaminés para avaliação das emissões atmosféricas dos dois fornos de produção de clínquer. A análise dos resultados obtidos associada às demais informações disponíveis de monitoramento das características das matérias-primas e combustíveis utilizados, bem como dos produtos finais, clínquer e cimento, não evidenciou alterações significativas nos níveis de emissões atmosféricas, sobretudo de material particulado e óxidos de enxofre, que pudessem ser associadas à utilização dos resíduos. Foram confirmadas as baixas emissões de inorgânicos e evidenciado o papel representado pelos resíduos no aporte dessas substâncias no sistema-forno, concluindo-se que esse aporte pode ser tão ou mais importante pela via da alimentação da farinha, cujos teores estão associados às características das jazidas minerais utilizadas. Foi também confirmada a alta eficiência do sistema-forno na destruição e remoção dos compostos orgânicos perigosos alimentados durante os testes de queima. / The production of industrial residues in inherent to the human development. The cement concrete is one of the most used material, manly the type portland cement, which is constituted by grinding clinker and gypsum together. Clinker can be defined as an artificial mineral obtained by applying physico-chemical reactions, at very high temperatures, to an appropriated mixture of limestone, clay, and some other materials in a rotating industrial kiln wich burns fossil fuels. In the early 1970 decade occurred the first experiences substituting fossil fuels by organic residues in USA and Europe through a technique named co-processing that results the production of certain manufacture while eliminates residues. Co-processing is based in the recovery of thermal energy and/or the mass of some constituents from some residues, with the same chemical characteristics of normal sources of energy, then economizing fuels and mass constituents and making better use of residues, otherwise useless and environmentally polluters. In the state of São Paulo this practice began in early 1990 decade and by 1997 it was started the standardization of the rules for its use in some units of the federation. Later this activity was regulated by nationally approved standard rules. In 1995 the industry Companhia de Cimento Ribeirão Grande (CCRG), a cement plant located in the city of Ribeirão Grande, São Paulo state, Brazil, started procedures searching the partial substitution of the normal fuels by a mixture of industrial residues in its two rotating kilns. The gaseous emissions from the chimneys of these two clinker kilns were studied from 1995 to 2002 about the use of residues as part of the fuel. Analyses of the final results associated with other informations concerning to the quality of raw minerals, fuels and products did not show significant alterations in atmospheric emissions, mainly for particulate material and sulfur oxides, related with the use of residues. The emissions of inorganic continued to be low and not significantly altered by the presence of residues. It was possible to conclude that the alterations in inorganic emissions depend more from the quality of the raw minerals feed in the kilns, which is more difficult to control, than from the presence of residues being burn with the fuel. It was shown a high efficiency in the destruction of dangerous organic compounds feed in the cement kilns, under test conditions.

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