Barium Sulphate Formation Kinetics and Inhibition at Surfaces

This study refers to experimental work and analysis of the barium sulphate deposition onto surfaces. In the oil field the formation of barium sulphate is a major flow assurance issue. The build up of the BaS04 inorganic scale on surfaces and facilities is undesirable as it causes increased function, reduction in production and other flow assurance issues. To date the overwhelming amount of research has been on the bulk precipitation of barite and little attention has been paid to deposition onto surfaces. This study shows an integrated approach to access the formation kinetics of barite at surfaces. Both the formation kinetics and the crystallography of the deposited barite are explored under examined conditions intended to imitate in some part the off-shore environment. In addition the effect of chemical additives performing as inhibitors of the barite growth is kept as a main concern of this study. Understanding the behavior of the inhibitors and their retardation mechanisms can further target the improvement of inhibition and overall antiscaling techniques. The thesis work has demonstrated that the surface growth kinetics of barite is largely different to bulk kinetics and interesting phenomena occur at surfaces especially when inhibitors are used. There are complex interactions of the inhibitor with the scale and both growth kinetics and crystal morphology are affected with threshold concentrations. The input of the inhibition mechanisms is discussed

Assessment of combined scale/corrosion inhibitors - A combined jar test/bubble cell

The formation of calcium carbonate scale and the occurrence of CO corrosion are both widespread phenomena observed within pipework during oil and gas production. The most common form of treatment for both processes is the application of chemical inhibition through corrosion and/or scale inhibitors. Surface scaling of pipework rarely occurs in environments where no corrosion exists, yet techniques used to develop and assess the performance of scale inhibitors tend to focus on assessing and reducing solely bulk/surface scaling, without affording consideration towards corrosion, whilst corrosion inhibitors are frequently evaluated in non-scaling environments. Furthermore, both chemicals tend to be evaluated independently meaning that any potential antagonistic effects between the chemicals can go unrecognised. This paper addresses this very issue by presenting a unique setup and methodology to enable the occurrence of scale and corrosion to be monitored simultaneously in a CO-saturated environment in the presence and absence of combined scale and corrosion inhibitors. The test cell focuses on evaluating four key parameters which are quantified either throughout the duration of the test, or from the implementation of post-test surface analysis techniques. The multiple assessment of (i) bulk scale precipitation, (ii) surface scaling, (iii) general corrosion and (iv) localised corrosion permits a full assessment of the chemical blends propensity to mitigate both scaling and corrosion. Non-inhibited tests were initially conducted at 60 °C to form a baseline for comparison. Four combined scale/corrosion inhibitors were subsequently used at low concentrations in order to understand their mechanisms and highlight any competitive effect which existed in reducing either scale or corrosion. The results demonstrate that the methodology implemented is effective at assessing the efficiency of combined inhibitors in reducing both corrosion and scale in environments where both processes occur simultaneously. The limitations of conducting solely bulk scaling or corrosion tests in non-scaling environments are discussed relative to the results obtained in this work. The results of each individual inhibitor are discussed and markedly different behaviour is observed according to the concentration administered, as well as the particular blend of chemicals applied

Διαλυτοποίηση διοξειδίου του πυριτίου παρουσία χημικών πρόσθετων. Εφαρμογές στο βιομηχανικό ψυκτικό νερό

Scale formation is a challenge for industrial cooling water systems. Formation of sparingly soluble electrolytes is observed in industrial plants. Water is a universal cooling medium because of its cost-effectiveness and high heat capacity. After the cooling water comes in contact with the &hot& process, it needs to be re-cooled for re-use. This cooling is achieved by partial evaporation. Eventually, concentration of all dissolved species ensues until a critical point of &scaling& is reached, leading to precipitation, and ultimately deposition of mineral salts. Species usually associated with such deposits (depending on water chemistry) are calcium salts (carbonate(s), sulfate(s) and phosphate(s)), colloidal silica and metal silicates etc. Formation and deposition of tenacious colloidal SiO2 deposits is one of the most difficult problems of water treatment and has been named as &water treatment&s Gordian Knot&. Prevention of scale formation is greatly preferred to chemical cleaning of the adhered scale. Classic examples of scales that require laborious (mechanical) and potentially dangerous (hydrofluoric acid) cleaning are silica and silicate salts. Unfortunately, prevention of scale formation is not always possible. At times, system operators are faced with the difficult task of removing hard and tenacious scale deposits from critical heat exchange surfaces. Therefore, an integrated chemical water treatment approach must contain contingencies that relate to chemical cleaning of a potentially scaled system. This specific research is focused on the dissolution of silica using chemical additives, with emphasis on use of environmentally benign additives.Ο σχηματισμός ιζημάτων αποτελεί πρόκληση για τα βιομηχανικά συστήματα νερού. Το νερό αποτελεί το πιο διαδεδομένο ψυκτικό μέσο, εξαιτίας του ικανοποιητικού κόστους αλλά και της μεγάλης θερμοχωρητικότητας του. Όταν το νερό χρησιμοποιείται επανειλημμένα σε αυτές τις &θερμές& διαδικασίες είναι αναγκαίο να επαναψύχεται. Η ψύξη πετυχαίνεται με μερική εξάτμιση. Τα είδη των διαλυτών ειδών συσσωρεύονται μέχρι που η συγκέντρωση τους, προσεγγίζει το κρίσιμο σημείο σχηματισμού ιζημάτων. Τελικά λαμβάνει χώρα ιζηματοποίηση και εναπόθεση δυσδιάλυτων, ανόργανων αλάτων όπως είναι τα ανθρακικά, θειικά, φωσφορικά, κολλοειδές διοξείδιο του πυριτίου, πυριτικά άλατα κ.α. Η φύση αυτών των ειδών εξαρτάται από την χημεία του νερού. Ο σχηματισμός και η εναπόθεση μεγάλων ποσοτήτων ιζημάτων κολλοειδούς διοξειδίου του πυριτίου αποτελεί ένα από τα πιο δύσκολα προβλήματα επεξεργασίας ύδατος και έχει ονομαστεί ως &επεξεργασία ύδατος Gordian Knot&. Δυο είναι οι καθιερωμένες μέθοδοι για την αντιμετώπιση και απομάκρυνση του κολλοειδούς διοξειδίου του πυριτίου από τις κρίσιμες επιφάνειες. Η μηχανική μέθοδος στηρίζεται στην &αμμοβολή&, ενώ η χημική στηρίζεται στην χρήση NH4F.HF και αποτελεί μια επικίνδυνη μέθοδο. Ακριβώς γι' αυτόν τον λόγο απαιτείται μια ευρεία και όσο το δυνατόν ηπιότερη προσέγγιση χημικής επεξεργασίας ύδατος, η οποία θα είναι κατάλληλη για συστήματα που πάσχουν από εναποθέσεις ιζημάτων. Στη συγκεκριμένη εργασία περιγράφεται η χρήση χημικών πρόσθετων, τα οποία συμβάλλουν στην διαλυτοποίηση του κολλοειδούς SiO2. Μάλιστα κάποια από αυτά τα πρόσθετα συγκαταλέγονται στις &πράσινες& ενώσεις Οι διαλυτοποιητές που χρησιμοποιήθηκαν έχουν την δυνατότητα να αντικαταστήσουν τις μέχρι τώρα προσεγγίσεις διαλυτοποίησης του SiO2, όπως είναι το ammonium bifluoride, το οποίο επιφυλάσσει κίνδυνο για την υγεία αλλά και κίνδυνο καταστροφής μηχανικών τμημάτων του συστήματος

Políticas públicas para a formação de professores e contextos emergentes na educação superior

This text refers to training policies for teachers and the rebound in emerging contexts in higher education, from the development of programs such as Fellowship Program Introduction to Teaching (PIBID) Training Program of Municipal Directors of Education (PRO -Board) and Centre of Education (OBEDUC). The objective is, in this sense, analyzing the policies of teacher training (initial and ongoing), developed by the Education Center of the Federal University of Santa Maria, and emerging contexts in higher education. It is a qualitative research from the case study, and the data analysis is grounded in the collection and building data from regulatory frameworks and allusive reports to Government programs already mentioned implemented by the Education Center the Federal University of Santa Maria (CE / UFSM). The study has contributed to the understanding of public policies for teacher training (initial / continuous) in close interrelation with emerging contexts in higher education; recognition and understanding of the organizational culture and management processes of the programs analyzed from the experiences developed by CE / UFSM and its impact on quality of initial and continuing teacher training; a critical reflection on the understanding and involvement of teachers / managers on emerging contexts in higher education.Este texto refere-se a políticas de formação de professores e a repercussão em contextos emergentes na educação superior, a partir do desenvolvimento de programas como o Programa de Bolsas de Iniciação à Docência (PIBID), Programa de Capacitação de Conselheiros Municipais de Educação (PRÓ-CONSELHO) e Observatório de Educação (OBEDUC). Objetiva-se, nesse sentido, analisar as políticas públicas de formação de professores (inicial e permanente), desenvolvidas pelo Centro de Educação da Universidade Federal de Santa Maria, e os contextos emergentes na educação superior. Trata-se de uma pesquisa de natureza qualitativa, a partir do estudo de caso, sendo que a análise de dados está embasada na coleta e construção de dados a partir de marcos regulatórios e relatórios alusivos a Programas de Governo já mencionados implementados pelo Centro de Educação da Universidade Federal de Santa Maria (CE/UFSM). Os estudos vem contribuindo para a compreensão das políticas públicas voltadas para a formação de professores (inicial/permanente) em íntima inter-relação com contextos emergentes na educação superior; o reconhecimento e a compreensão da cultura organizacional e dos processos de gestão dos programas analisados a partir das experiências desenvolvidas pelo CE/UFSM e sua repercussão na qualidade da formação inicial e permanente de professores; uma reflexão crítica acerca da compreensão e o envolvimento dos professores/gestores sobre contextos emergentes na educação superior.Este texto se refiere a políticas de formación de profesores y la repercusión en contextos emergentes en la educación superior, a partir del desarrollo de programas como el Programa de Becas de Iniciación a la Docencia (PIBID), Programa de Capacitación de Consejeros Municipales de Educación (PRÓ-CONSELHO) y Observatorio de Educación (OBEDUC). Se objetiva, en ese sentido, analizar las políticas públicas de formación de profesores (inicial y permanente), desarrolladas por lo Centro de Educación de la Universidad Federal de Santa Maria, y los contextos emergentes en la educación superior. Se trata de una investigación de naturaleza cualitativa, a partir del estudio de caso, siendo que el análisis de datos se basa en la colecta y construcción de datos a partir de marcos regulatorios e informes alusivos a Programas de Gobierno ya mencionados implementados por el Centro de Educación de la Universidad Federal de Santa Maria (CE/UFSM). Los estudios vienen contribuyendo a la comprensión de las políticas públicas vueltas a la formación de profesores (inicial/permanente) en íntima interrelación con contextos emergentes en la educación superior; el reconocimiento y la comprensión de la cultura organizacional y de los procesos de gestión de los programas analizados a partir de las experiencias desarrolladas por lo CE/UFSM y su repercusión en la calidad de la formación inicial y permanente de profesores; una reflexión crítica acerca de la comprensión y el envolvimiento de los profesores/gestores sobre contextos emergentes en la educación superior