Naphthenic acids (NAs) are carboxylic acids found in crude oil and petroleum products. The objectives of the research presented here were to: a) assess the occurrence and fate of NAs in crude oil and refinery wastewater streams; b) evaluate the biotransformation potential and inhibitory effects of NAs under nitrifying, denitrifying and methanogenic/fermentative conditions; c) investigate the factors affecting NA biotransformation under aerobic conditions and the microbes involved; and d) assess the toxicity of individual model NAs using quantitative structure-activity relationships (QSAR) and examine the effect of structure on NA biotransformation potential. NAs are ubiquitous in refinery wastewater streams and the desalter brine was found to be the main source of NAs in refinery wastewater. A commercial NA mixture was not biodegraded under nitrate-reducing or methanogenic/fermentative conditions. NAs were degraded under aerobic conditions by an NA-enriched culture; however, a residual fraction was not degraded under all conditions studied. The results indicated that NAs are not inherently recalcitrant and the residual fraction was due to the individual NA concentrations being below the minimum substrate concentrations at which they are no longer degraded. A fraction of the NA mixture was completely mineralized to carbon dioxide, with the remaining portion biotransformed to more oxidized intermediates. Overall, the results indicated that NAs were degraded under aerobic conditions; however, biological treatment of NA-bearing wastewater will not completely remove NA concentrations and thus, biological treatment must be combined with physical/chemical treatment to achieve complete NA removal.

Thesis (MSc)--University of Stellenbosch, 2011. / ENGLISH ABSTRACT: Landfarming is a widely used method for the disposal of contaminants in the petrochemical industry. It involves ploughing the contaminants into the top soil layer allowing biological breakdown. A historically landfarmed site was identified at a South African petrol refinery. The refinery used to dispose so-called American Petroleum Institute (API) -sludge onto a landfarming site. API-sludge consisted of a mixture of oil and water soluble contaminants originating from a process of separating refinery waste from reusable water and oil. Landfarming on this site was discontinued after excessive quantities of sludge were ploughed into the soil over time and it became obvious that effective biodegradation could not take place. An environmental assessment had to be carried out to assess to what extent the soil has recovered from the contamination and after remediation was done over time. Bioassays together with chemical analyses were executed to determine the level of pollutants in the soil and to assess the integrated effects of their bioavailable fractions. The landfarming site of the refinery was divided into two sections namely, a more contaminated north-site and less contaminated south-site. Soil samples were collected from both sites as well as from an off-site (control site). The soils were analysed physically, chemically and used in the bioassays. Two additional control soils were also used, OECD-soil and LUFA2.2 soil. Chemical analysis of the site soils showed the presence of heavy metals and high levels of diesel range organic hydrocarbons. The north-site had higher levels of contaminants compared to the south-site. Three species of soil organisms were used in standardised tests: Eisenia andrei, Enchytraeus doerjesi and Folsomia candida were exposed to the respective soils to study their survival, growth, reproduction success and avoidance behavior. Exposures to both site-soils were not acutely toxic to any organisms. F. candida had a decrease in juvenile production in both north- and south-site soils (289.42 ± 58.62 and 253.33 ± 122.94 respectively) compared to the control soil (479.89 ± 30.42). E. doerjesi showed an increase in produced juveniles exposed to north- and south-site soil (339.75 ± 76.92 and 414.00 ± 17.78 ) compared to control soil (57 ± 34.39). E. andrei had similar cocoon production when exposed to south-site soil than in off-site soil (19.00 ± 5.3 and 18.5 ± 9.7 respectively) but significantly less in north-site soil (1.25 ± 0.7). Only E. doerjesi showed avoidance of north-site soil. To determine the sensitivity of the organisms to the API-sludge, they were exposed to concentration series of API-sludge-spiked control soils. The effect concentrations were calculated as the concentration of API-sludge that will decrease the studied endpoints by 50% of the control soil (EC50). The EC50s varied for each species exposed in the different control soils showing that the toxicity of the API-sludge is to a certain extent dependent on the physical soil properties of the substrate. The reproduction of F. candida were most sensitive to the API-sludge in off-site soil (EC50 = 90 mg/kg) and the E. doerjesi the least sensitive in LUFA2.2 soil (EC50 = 36000 mg/kg). Five plant species were exposed to API-sludge-spiked potting soil and the germination success, early growth rate and biomass were studied. The plants were not as sensitive to API-sludge as the soil animals. Lettuce and grass were affected the most by API-sludge and beans were the most resilient species. With the addition of low levels API-sludge to the substrate, the growth rate of beans was stimulated. This study showed that the south-site has been successfully remediated and most soil organisms exposed to these soils were not affected by the levels of toxicants present. However, exposures to north-site soil still had negative effects on soil organisms. It is recommended that hydrocarbon contamination should be further remediated in the north-site soil before landfarming should be allowed to continue. / AFRIKAANSE OPSOMMING: Ploegverwerking is ‘n algemene remediëringsmetode vir die verwerking van afvalmateriaal in petrochemiese industrieë. Dit behels die inploeg van toksiese afvalmateriaal in die boonstegrondlaag sodat dit biologies afgebreek kan word. ‘n Voorbeeld van ‘n histories ploegverwerkte grondstuk is geidentifiseer by ‘n Suid-Afrikaanse olieraffinadery. Die raffinadery het in die verlede van die grondstuk gebruik gemaak om sogenaamde Amerikaanse Petroleum Instituut-slik (API-slik) daarin te ploeg. Die API-slik bestaan uit ‘n mengsel van olie- en wateroplosbare kontaminante afkomstig van die proses waardeur die raffinadery se afvalprodukte van hernubare water en olie geskei word. Nadat oormatige konsentrasies slik in die grond ingewerk is en bioremediasie nie meer doeltreffend kon voortgaan nie, is die ploegverwerking gestaak. ‘n Omgewingimpakstudie moes uitgevoer word om te bepaal tot watter mate die grond herstel het nadat remediasie oor tyd uitgevoer is. Toksisiteitstoetse en chemiese analises is uitgevoer om die vlakke van besoedeling sowel as die biobeskikbare fraksie daarvan in die grond te bepaal. Die ploegverwerkte area van die raffinadery is in twee verdeel naamlik, ‘n meer gekontamineerde noordelike area en ‘n minder gekontamineerde suidelike area. Grondmonsters is van die onderskeie areas asook van ‘n ongekontamineerde veld (as kontrole) naby die ploegverwerkte area versamel Die gronde is fisies- en chemies geanaliseer en toksisiteitstoetse is uitgevoer. Twee addisionele kontolegronde is ook tydens die blootstellings gebruik naamlik, OECD- en LUFA2.2-grond. Die chemiese analises van die ploegverwerkte toetsgronde het getoon dat daar steeds swaarmetale en hoë vlakke van dieselgekoppelde organiese koolwaterstowwe in die gronde teenwoordig is. Kontaminante was in hoër konsentrasies teenwoordig in die grond van die noordelike gebied as in dié van die suidelike gebied. Drie spesies van grondorganismes is gebruik tydens standaard toksisitetitstoetse. Eisenia andrei, Enchytraeus doerjesi en Folsomia candida is blootgestel aan die onderskeie toets- en kontrolegronde waarna hul oorlewing, groei, voortplantingsukses en vermydingsreaksies bestudeer is. Blootstellings aan die ploegverwerkte toetsgronde het geen akute toksisiteit vir enige van die spesies getoon nie. F. candida se juveniele produksie was laer in beide noordelike- en suidelike toetsgronde (289.42 ± 58.62 en 253.33 ± 122.94 onderskeidelik) as in die kontolegrond (479.89 ± 30.42). E. doerjesi blootstellings het ‘n toename in juveniele getalle getoon in die noordelike- en suidelike toetsgronde (339.75 ± 76.92 en 414.00 ± 17.78) in vergelyking met die ongekontamineerde kontolegrond (57 ± 34.39). Kokonproduksie by E. andrei was soorgelyk in die suidelike toetsgrond en ongekontamineerde kontrolegronde (19.00 ± 5.3 en 18.5 ± 9.7 onderskeidelik) maar beduidend minder as in noordelike toetsgrond (1.25 ± 0.7). Slegs E. doerjesi het ‘n beduidende vermydingsreaksie vir die noordelike toetsgronde getoon. Om die sensitiwiteit van die organismes aan vars API-slik te bestudeer, is hulle blootgestel aan konsentrasiereekse van API-slik in die onderskeie kontrolegronde. Die effektiewe konsentrasie (EK50) is bereken as die konsentrasie van API-slik wat die bestudeerde eindpunte met 50% sal verminder in vergelyking met die kontrolegrond Die EK50-waardes vir al die spesies het verskil na blootstelling aan die onderskeie kontrolegronde. Dus, die toksisiteit van die API-slik is tot ‘n sekere mate ook afhanklik van die fisiese grondeienskappe van die blootsellingssubstraat. Die voortplanting van F. candida was die gevoeligste eindpunt vir die blootstelling aan API-slik in kontolegrond (EK50 = 90 mg/kg) en E. doerjesi was die minste gevoelig in LUFA2.2 grond (EK50 = 36000 mg/kg). Vyf plantspesies is ook blootgestel aan API-slikgekontamineerde potgrond en die saadontkiemingssukses, vroeë groeikoers en biomassa is bestudeer. Alhoewel plante nie so sensitief was vir die API-slik soos die gronddiere nie, was blaarslaai en gras die meeste geaffekteer tydens die blootstellings. Boontjies was die ongevoeligste en met die toevoeging van lae konsentrasies API-slik (2.5% API-slik), is hul groeikoers selfs gestimuleer. Uit die studie was dit duidelik dat die suidelike deel van die grondstuk meer suksesvol as die noordelike geremidieer is en dat meeste grondorganismes wat daaraan bloot gestel is nie geaffekteer is deur die vlakke van kontaminasie wat steeds teenwoordig is in die grond nie. Die toetsgronde uit die noordelike deel het egter steeds negatiewe effekte op die grondorganismes gehad. Dit word voorgestel dat die koolwaterstof kontaminasie verder geremidieër behoort te word in die noordelike deel van die grondstuk voordat verdere ploegverwerking van die afval daar gedoen word.

Thesis (PhD)--Stellenbosch University, 2004. / ENGLISH ABSTRACT: During the last 30 years I have been involved in the theory and practice of thermal engineering and in particular, in the areas of air-cooled heat exchangers and cooling towers for the power, refrigeration, process and petrochemical industries in South Africa and internationally. During this period, I have authored and co-authored more than 120 papers that were published in technical journals or presented at conferences nationally or internationally. Most of these papers are included in a manuscript entitled "Air-cooled Heat Exchangers and Cooling Towers", in which Ipresent a systematic approach to the thermal performance evaluation and design of industrial air-cooled heat exchangers and cooling towers. This original publication also includes the relevant practice applicable to the design of cooling systems, based on my experience as a consultant to industry. Design offices throughout the world presently follow our design methods, or at least employ many of our research results. Our work has furthermore contributed to the development of improved cooling system designs (e.g. new dephlegmator header designs), components (e.g. single-row flattened finned tubes) and product improvement and quality control (e.g. performance testing and measurement of thermal contact resistance between fin and tube during production). Many of our research findings have found application in the modification of existing cooling systems. The manuscript has also been used as reference work during the presentation of short courses to practising engineers and consultants in industry and to engineering graduates at the University of Stellenbosch. A two-volume edition of this manuscript was published by PennWell Corp., Tulsa, Oklahoma, USA in 2004. / AFRIKAANSE OPSOMMING: Gedurende die laaste 30 jaar was ek betrokke by die teorie en praktyk van lugverkoelde warmteoordraers en koeltorings vir die kragopwekkings-, verkoelings-, proses- en petro-chemiesenywerhede in Suid-Afrika sowel as in die buiteland. Gedurende hierdie periode was ek outeur en mede-outeur van meer as 120 publikasies wat in tegniese tydskrifte, of by plaaslike of oorsese konferensies aangebied is. Die meeste van hierdie publikasies vorm deel van 'n manuskrip getiteld "Air-cooled Heat Exchangers and Cooling Towers" waarin ek 'n sistematiese benadering tot die bepaling van die termiese vermoë en ontwerp van industriële lugverkoelde warmteoordraers en koeltorings aanbied. Hierdie oorspronklike publikasie bevat ook die relevante praktyk wat van toepassing is op verkoelingsaanlegte. Ontwerpkantore wêreldwyd volg tans hierdie ontwerpsmetodes, of gebruik ten minste baie van ons navorsingsresultate. Ons werk het verder bygedra tot die ontwikkeling van verbeterde verkoelingsaanlegte (bv. nuwe deflegmatore), komponente (bv. enkelbuisry platvinbuise ) en verbeterde produkte en kwaliteitskontrole (bv. toetsing van verkoelingsvermoë oftermiese kontakweerstand tussen vin en buis gedurende produksie). Baie van ons bevindinge het toepassing gevind in die modifikasie van verkoelingsaanlegte. Die manuskrip is ook as verwysing gebruik gedurende die aanbieding van kort kursusse aan ingenieurs in die praktyk en aan nagraadse studente aan die Universiteit van Stellenbosch. 'n Twee-volume uitgawe van die manuskrip is deur PennWell Corp., Tulsa, Oklahome, VSA in 2004 gepubliseer.

Durante muitos anos tem-se usado a técnica de programação linear (Linear programming- LP) para abordar o problema do planejamento da produção em refinarias de petróleo. Esta técnica é baseada na linearização do comportamento não linear dos processos num conjunto particular de condições operacionais. Contudo, modelos lineares não são uma boa representação da operação dos processos de refino, pois estes envolvem diferentes operações físicas (separação de fases, mistura de correntes intermediárias, etc.) e químicas (reações de craqueamento, reações de hidrotratamento, etc.) caracterizadas pelo seu comportamento não linear. Como conseqüência, os resultados (plano de operação) de modelos de planejamento da produção baseados na técnica de programação linear são de difícil implementação na operação. Por outro lado, recentes avanços na capacidade de cálculo dos computadores, assim como nas ferramentas matemáticas (algoritmos de otimização) utilizadas para solucionar os modelos de planejamento da produção, permitem a implementação de modelos não lineares de processos em modelos de planejamento da produção. Este trabalho é focado na formulação de modelos de processos adequados (boa aproximação da operação e baixo custo computacional) para o planejamento da produção em refinarias de petróleo. Inicialmente, é abordada a formulação de um modelo empírico para unidade de destilação o qual foi validado com sucesso usando um simulador rigoroso de processos. A seguir, um modelo empírico para uma unidade de craqueamento catalítico fluidizado (FCC) foi gerado e validado a partir de dados obtidos num simulador rigoroso de processo da PETROBRAS. Estes modelos empíricos superam as limitações dos modelos lineares e não lineares para unidades de destilação e unidades de FCC previamente propostos por outros autores. Em seguida, os modelos empíricos desenvolvidos foram implementados no planejamento da produção (para um único período) de duas refinarias: uma de pequena escala (só duas unidades de processo) e uma de média escala (com 7 unidades de processo). Os modelos de planejamento resultaram em dois problemas de programação não linear que foram resolvidos usando três solvers (CONOPT 3, IPOPT e MINOS) disponíveis na plataforma computacional GAMS (General Algebraic Modeling System). Os modelos de planejamento da produção foram resolvidos com sucesso num tempo computacional inferior a um segundo (CPU time < 1 s) pelos solvers. / For many years production planning problems in the petroleum refineries have been addressed using the linear programming (LP) technique. This technique is based on linear process models (linearization of nonlinear process behavior at a particular set of operating conditions). Nevertheless, the linear process models are not suitable for refinery process modeling, since refinery processes involve both physical (phase separations, blending operations, etc.) and chemical operations (cracking reactions, hydrotreating reactions, etc.) that are characterized by their nonlinear nature. Due to this fact, the results (operating plans) from production planning models based on the linear programming technique are operationally not reliable. On the other hand, recent advances in the computer hardware and in the mathematical tools (optimization algorithms) used for the solution of production planning problems, allow the implementation of nonlinear process models in the production planning models. This work deals with the formulation of non linear empirical process models for petroleum refinery planning. Firstly, the formulation of non linear empirical process model for refinery process is addressed. Two processes were studied: distillation and fluid catalytic cracking (FCC). An empirical model for crude distillation units was developed and successfully validated using rigorous simulations carried out in HYSYS® and the empirical model for a FCC unit was developed and successfully validated using a rigorous FCC simulator from PETROBRAS. These empirical models overcome the limitations of both linear and nonlinear empirical models for crude distillation and FCC units previously developed by others authors. Subsequently, the empirical models developed in this work were successfully implemented in the production planning model for two refineries: a small scale refinery (with two process units) and a medium scale refinery (with 7 process units). The production planning models resulted in two nonlinear programming problems that were solved using three different solvers (CONOPT 3, IPOPT and MINOS) available in GAMS (General Algebraic Modeling System) platform. The computational time for the solution of the production planning models were less than 1 second (CPU time < 1 s).

Thesis submitted in partial fulfilment of the requirements for the degree Master of Technology: Chemical Engineering in the Faculty of Engineering at the Cape Peninsula University of Technology 2013 / In South Africa, the Department of Environmental Affairs (DEA) under the National Environmental Management Act, 1998 (Act 107 of 1998) (“NEMA”) sets out a series of environmental management principles that apply to the interpretation and application of all legislation that may affect the environment. Since 1998, various specific environmental statutes that fall under the NEMA framework have been promulgated, including the National Environmental Management: Air Quality Act, Act 39 of 2004 (NEM: AQA).NEM:AQA provides norms and standards for all technical aspects of air quality management. The National Framework (Sections 7 and 8 of NEM:AQA) must provide mechanisms, systems and procedures to promote holistic and integrated air quality management through pollution prevention and minimisation at source, and through impact management with respect to the receiving environment, from local scale to international issues. Among other measures, the NEM:AQA (Section 9) requires the establishment of Ambient Air Quality Standards and Emission Standards. These standards were promulgated in December 2009 and March 2010 respectively. Air quality monitoring stations, which sample and analyse pollutant concentrations continuously, are a common method of assessing air quality in a region. But a few continuous monitors located in source given region or airshed are inadequate for assessing compliance with ambient air quality standards – they are only able to monitor concentrations at a fixed site, not through the entire region of impact. In contrast, the ambient air quality standards are applicable everywhere. Air quality models estimate ground level ambient concentrations throughout the modelling domain, and in principle (subject to proper validation) provide better estimates of area-wide concentrations and hence the basis for assessing compliance with air quality standards. The United States Environmental Protection Agency (US EPA) approved atmospheric air dispersion models AERMOD and CALPUFF were used in this thesis to predict the ground level concentrations of SO2 emitted from Chevron Refinery (Cape Town), for the year 2010. The modelling is validated by comparing measured ambient concentrations with modelled concentrations. The results showed AERMOD-modelled annual average values for 2010, based on refinery emissions only, are in good agreement with monitored values at the Table View and Bothasig sites, predicting the monitored values by -11% and +17% respectively. The 24-hr average values similarly are in good agreement with monitored values, on average over-predicting by 9% at Table View, although the fit of the day-to-day modelled vs monitored values is comparatively poor (R2=0.32); at the Bothasig site the corresponding values are - 36% and R2= 0.089. The AERMOD-modelled isopleths imply that the 2010 annual average concentrations exceeded the South African Standard of 50 μg/m3 in a small area in the immediate vicinity of the refinery. The hourly and 24-hourly average standard concentrations of 350μg/m3 and 125μg/m3 respectively are exceeded in significantly larger areas. The allowable exceedences for hourly and 24-hourly averages are also exceeded, implying that the hourly and 24-hourly standards were exceeded. CALPUFF-modelled average values for 2010, based on refinery emissions only, are in comparatively poor agreement with monitored values at the Table View and Bothasig sites, under-predicting the monitored values by -20% and -61% respectively. Since the AERMOD-modelled concentrations are in far better agreement with monitored concentrations, only AERMOD was used for further analysis. The Emission Standards promulgated in March 2010 included emission limit values for sulphur dioxide emitted from oil refineries. If the actual 2010 emission rates were adjusted downwards to match the emission standards (to be complied with from 1 April 2015), AERMOD modelling indicates that the annual, 24-hourly and hourly Ambient Air Quality Standards would not be exceeded. Based on this case study, the current Emission Standard for SO2 emissions from existing crude oil refineries is therefore coherent with the Ambient Air Quality Standards. Regulatory air dispersion modelling practices in South Africa are being standardised for model applications regulatory purposes and to ensure that dispersion modelling practices are undertaken in a compatible form to ensure that results from one dispersion model study can be compared directly to those from another. In this study both AERMOD and CALPUFF modelling complied with the draft South African guidelines for Air Quality Modelling, yet the CALPUFF- modelled outputs differed significantly from the monitored values. This emphasizes the importance of the inclusion of modelling validation in guidelines for modelling for regulatory purposes. The 2012 draft regulation should be amended to make validation of regulatory dispersion modelling compulsory rather than optional as per the draft.

Durante muitos anos tem-se usado a técnica de programação linear (Linear programming- LP) para abordar o problema do planejamento da produção em refinarias de petróleo. Esta técnica é baseada na linearização do comportamento não linear dos processos num conjunto particular de condições operacionais. Contudo, modelos lineares não são uma boa representação da operação dos processos de refino, pois estes envolvem diferentes operações físicas (separação de fases, mistura de correntes intermediárias, etc.) e químicas (reações de craqueamento, reações de hidrotratamento, etc.) caracterizadas pelo seu comportamento não linear. Como conseqüência, os resultados (plano de operação) de modelos de planejamento da produção baseados na técnica de programação linear são de difícil implementação na operação. Por outro lado, recentes avanços na capacidade de cálculo dos computadores, assim como nas ferramentas matemáticas (algoritmos de otimização) utilizadas para solucionar os modelos de planejamento da produção, permitem a implementação de modelos não lineares de processos em modelos de planejamento da produção. Este trabalho é focado na formulação de modelos de processos adequados (boa aproximação da operação e baixo custo computacional) para o planejamento da produção em refinarias de petróleo. Inicialmente, é abordada a formulação de um modelo empírico para unidade de destilação o qual foi validado com sucesso usando um simulador rigoroso de processos. A seguir, um modelo empírico para uma unidade de craqueamento catalítico fluidizado (FCC) foi gerado e validado a partir de dados obtidos num simulador rigoroso de processo da PETROBRAS. Estes modelos empíricos superam as limitações dos modelos lineares e não lineares para unidades de destilação e unidades de FCC previamente propostos por outros autores. Em seguida, os modelos empíricos desenvolvidos foram implementados no planejamento da produção (para um único período) de duas refinarias: uma de pequena escala (só duas unidades de processo) e uma de média escala (com 7 unidades de processo). Os modelos de planejamento resultaram em dois problemas de programação não linear que foram resolvidos usando três solvers (CONOPT 3, IPOPT e MINOS) disponíveis na plataforma computacional GAMS (General Algebraic Modeling System). Os modelos de planejamento da produção foram resolvidos com sucesso num tempo computacional inferior a um segundo (CPU time < 1 s) pelos solvers. / For many years production planning problems in the petroleum refineries have been addressed using the linear programming (LP) technique. This technique is based on linear process models (linearization of nonlinear process behavior at a particular set of operating conditions). Nevertheless, the linear process models are not suitable for refinery process modeling, since refinery processes involve both physical (phase separations, blending operations, etc.) and chemical operations (cracking reactions, hydrotreating reactions, etc.) that are characterized by their nonlinear nature. Due to this fact, the results (operating plans) from production planning models based on the linear programming technique are operationally not reliable. On the other hand, recent advances in the computer hardware and in the mathematical tools (optimization algorithms) used for the solution of production planning problems, allow the implementation of nonlinear process models in the production planning models. This work deals with the formulation of non linear empirical process models for petroleum refinery planning. Firstly, the formulation of non linear empirical process model for refinery process is addressed. Two processes were studied: distillation and fluid catalytic cracking (FCC). An empirical model for crude distillation units was developed and successfully validated using rigorous simulations carried out in HYSYS® and the empirical model for a FCC unit was developed and successfully validated using a rigorous FCC simulator from PETROBRAS. These empirical models overcome the limitations of both linear and nonlinear empirical models for crude distillation and FCC units previously developed by others authors. Subsequently, the empirical models developed in this work were successfully implemented in the production planning model for two refineries: a small scale refinery (with two process units) and a medium scale refinery (with 7 process units). The production planning models resulted in two nonlinear programming problems that were solved using three different solvers (CONOPT 3, IPOPT and MINOS) available in GAMS (General Algebraic Modeling System) platform. The computational time for the solution of the production planning models were less than 1 second (CPU time < 1 s).

Thesis (MBA)--Stellenbosch University, 2005. / ENGLISH ABSTRACT: The oil industry is under pressure to select refinery projects that will provide higher and more predictable returns. In the past Discounted Cash Flow (DCF) techniques have been used to choose between refinery project alternatives. One of the problems with DCF techniques is that they ignore management flexibility when evaluating projects that contain embedded options. Real Option Valuation (ROV) is an approach that takes management flexibility into account and places a value on this flexibility. ROV has been used extensively by the oil industry for the evaluation of oil and gas reserves. The aim of this study is to determine the extent to which the use of ROV will improve the decision making process when evaluating a refining project containing embedded options as well as to determine the most appropriate option valuation method for refining projects. This was done by evaluating a refining project using both a probabilistic DCF approach and the various option pricing models and comparing the results. It was concluded that ROV will improve the decision making process when evaluating refining projects containing embedded options. The most appropriate option pricing method for refining projects was found to be the simulation approach since simulation is already being used by refineries to perform probabilistic DCF analysis. It is not recommended that ROV should be blindly applied to all refining projects containing embedded options. The use of ROV should be limited to larger refining projects for which probabilistic cash flows have been developed and the extent of the ROV analysis required should be determined by a careful review of the net present value (NPV) cumulative probability curves. / AFRIKAANSE OPSOMMING: Die olie industrie is onder druk geplaas om projekte te kies met 'n hoër opbrengs op kapitaal en 'n opbrengs wat meer voorspelbaar is. In die verlede is slegs die Verdiskonteerde Kontant Vloei (VKV) metode gebruik om projekte te selekteer vir die raffinadery. Een van die onderliggende tekortkominge met die gebruik van die VKV metode is dat verskillende bestuursopsies in terme van alternatiewe met ingeboude opsies, nie voldoende ondersoek word nie. Reële Opsie Waardasie (ROW) is 'n metode wat bestuursopsies in ag neem deur 'n waarde te plaas op elke beskikbare bestuursopsie. ROW het wye toepassings in die olie industrie vir die evaluasie van gas en olie reserves. Die doel van hierdie studie is om te bepaal tot watter mate die gebruik van ROW die besluitnemingsproses sal verbeter in terme van die evaluasie van projekte met ingeboude opsies vir raffinaderye en watter opsiewaardasie metode die mees geskikte is vir sulke projekte. 'n Raffinadery projek is evalueer deur beide KV en verskeie opsie-prysbepalingsmetodes te gebruik en die resultate is vergelyk. Die resultate van die studie het bewys dat die ROW metode die besluitnemingsproses verbeter. Die studie het gewys dat die mees geskikte opsie-waardasie metode vir projekte in the raffinadery die simulasie benadering is omdat simulasie alreeds vir probalisties VKV ontleding gebruik word. 'n Verdere aanbeveling is dat die ROW metode nie blindelings gevolg moet word vir alle projekte met ingeboude opsies nie. Die gebruik van ROW moet beperk word tot groter projekte waarvoor probabilistiese kontantvloei alreeds ontwikkel is. Die mate van ROW ontleding moet bepaal word deur 'n noukeurige ondersoek te doen van die kumulatiewe netto huidige waarde-waarskynlikheidskurwe.

Orientador: Antonio Carlos Bannwart / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecanica / Made available in DSpace on 2018-07-20T08:34:29Z (GMT). No. of bitstreams: 1 Rossi_LucianoFernandodosSantos_D.pdf: 31189486 bytes, checksum: b5668903a52a4adff00b0520804c237d (MD5) Previous issue date: 1995 / Resumo: Este estudo teve como objetivo a análise de processos industriais, os mais abrangentes possíveis, visando sua otimização do ponto de vista energético-econômico. Neste intento, buscou-se apresentar não apenas um único ponto de otimalidade, mas um conjunto de opções que permita a um decisor escolher a situação mais conveniente. No desenvolvimento deste estudo foram utilizados um conjunto de Métodos de Otimização, dentre os quais podem ser destacados a Metodologia Pinch de Recuperação de Energia, baseada em uma redistribuição de potenciais térmicos dentro do processo analisado, e os Métodos originários da Programação Matemática, em especial a Programação Linear. Analisou-se em profundidade o caso, relativo à lndúsrtria de refino de Petróleo, de uma etapa de Craqueamento Catalítico da Refinaria de Paulínia, da PETROBRÁS. Entretanto, o conjunto de procedimentos aplicados neste trabalho mostrou-se eficiente quando da análise de outros segmentos industriais, em particular das lndústrias Química, de Alimentos e Petroquímica, como apresentado no decorrer deste trabalho. Este estudo mostra que é perfeitamente possível fazer-se uma análise energética e uma avaliação econômica de sua implantação, de uma maneira muito satisfatória e rápida / Abstract: This work deals with the industrial process analysis, includingvarious types and sizes, looking for their optimization fiom the economic and energetic point of view. Not only a single point of optimality was searched but a set of options which could permit to a decision maker to choose the best situation in each case. ln the development of this study were utilized a set of Optimization Methods, among which it can be mentioned the "Pinch Point Methodology" to heat recovery in networks, which is based in a redistribution of the thermal potentials of the process analyzed, and the methods originated tfom the Mathematics Programming, in special the Linear Programming. A deep analysiswas made on the case relative to an oil refinery.More precisely a part ofthe catalytic cracking of the Paulinia's Oil Refinery of PETROBRAS. The set of procedures applied in this work, it can be shown efficient when the analysis is applied to other industrial branches, in particular in the Chemistry, Food and Petrochemistry industries, as shown in throughout this work. This study shows that is possible to make an energetic analysis and an economic cost evaluation on the implementationof a process, in a fast and sactisfatory manner / Doutorado / Termica e Fluidos / Doutor em Engenharia Mecânica

Thesis (MBA)--Stellenbosch University, 2005. / ENGLISH ABSTRACT: South Africa's main requirements for power are in the form of electricity and liquid fuels The country's electricity is generated mainly from coal while the liquid fuels requirement is mainly from crude oil. Both coal and crude oil use are coming under increasing pressure locally because of pollution and accompanying environmental awareness. Internationally both energy sources are also increasingly being abandoned as preferred energy sources, in first world countries, in favour of cleaner energy sources.ln view of these developments in the macro environment South Africa's gas to liquids refinery built in the early 1990's seems a well placed past investment ahead of its time. This study project looks at the economic feasibility of the continued existence of the PetroSA gas to liquid plant in Mossel Bay.The study looks at South Africa as well as Southern Africa's energy resources , the effect of changing legislation on the future use of energy resources and the economics of the Mossel Bay facility. The study finds that South Africa's abundance of coal reserves, its lack of oil and gas reserves and the slow pace of environmental legislation delivery means that gas is unlikely to become a major source of energy in South Africa.The Mossel Bay gas to liquids plant is profitable but its high fixed costs and certain growth of this cost component means that the continued feasibility of operations is dependant on favourable movements in the exchange rate and oil price. To answer the question about whether to continue operating or close down the analysis found that although although early closure would provide a return of more than 15 percent it would be even more viable financially to make an investment for more gas and continue operations.The main reason for the better than average projected returns is the high oil price .The decision to close down the Mossel Bay plant is not likely to be based on financial considerations alone. The recommendation is thus to continue operations untill 2016.The investment required to secure more gas would , even in the worst case scenario, provide a satisfactory return on investment. / AFRIKAANSE OPSOMMING: Suid Afrika se energie behoeftes is hoofsaaklik vir elektrisiteit en brandstof. Die meerderheid van die land se elektristeit word deur middel van steenkool opgewek terwyl ru-olie gebruik word om brandstof te vervaardig. Beide steenkool en ru-olie word al hoe meer onder druk geplaas as gevolg van besoedeling en 'n meer omgewing bewuste publiek. Op internasionale vlak , in eerste wereld lande word die gebruik van steenkool en ru-olie al hoe meer afgeskaf ten gunsle van skoner kragbronne. In die lig van hierdie verwikkeling in die makro omgewing mag dit op die oog af Iyk of PetroSA se gas na vloeistof aanleg in Mosselbaai, wat reeds in die vroee 1990's gebou is, as 'n goeie destydse strategiese belegging voorkom. Hierdie studie projek ondersoek die ekonomiese lewensvatbaarheid van die voorgesette bestaan van die PetroSA se Mosselbaai gas na vloeislof aanleg. Die studie kyk na Suid-Afrika sowel as die groter Suider Afrika se natuurlike energiebronne, die invloed van verandering in wetgewing op die toekomstige gebruik van energiebronne en die ekonomiese kenmerke van die aanleg in Mosselbaai. Die bevinding van die studie is dat Suid-Afrika se oorvloed van steenkool, sy tekort aan natuurlike gas en die stadige pas waarteen omgewings-wetgewing ontwikkel word, daartoe lei dat gas nie 'n volmatige energiebron in Suid Afrika sal word nie. Die aanleg in Mosselbaai is huidiglik winsgewind maar sy hoe vastekoste en groei hiervan belemmer sy vooruitsigte vanuit 'n finansiele oogpunt. Die winsgewindheid van die aanleg is afhanklik van 'n verswakkende Suid Afrikaanse geldeenheid en verhogende ru-olie pryse. Die vraag onstaan dus of die aanleg moet toemaak en of produksie moet voortgaan. Die ondersoek vind dat alhoewel die sluiting van die aanleg 'n opbrengs van meer as 15 persent sal lewer dit selfs meer finansieel aantreklik is on te belê in meer gas sodat produksie kan voortgaan. Die hoofrede vir die bogemiddelde opbrengs is die hoe oilieprys. Dit is onwaarskynlik dat die oorweging om die Mosselbaaise aanleg sluit suiwer op finansieele oorwegings sal rus. Die aanbeveling is dus om voort te gaan met produksie tot 2016. Die belegging wat nodig is vir meer gas sal selfs onder die mees pessimistiese omstandighede steeds 'n bevredigende opbrengs lewer.

Orientador: Rubens Maciel Filho / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Química / Made available in DSpace on 2018-08-23T11:34:50Z (GMT). No. of bitstreams: 1 Maia_JulioPereira_D.pdf: 8705466 bytes, checksum: e604d7a471ca19eb99492912d431174b (MD5) Previous issue date: 2013 / Resumo: Esta tese apresenta um estudo de estratégias de esquemas de controle em unidades de destilação a vácuo de refinarias de petróleo, com o uso de dados e informações de uma refinaria brasileira, de modo a se desenvolver uma simulação representativa do processo, onde uma diferença global máxima de 5% entre os resultados de simulação e os dados de saída reais foi obtida. A simulação foi executada com alto nível de detalhamento, com cálculos de queda de pressão, dimensionamento de sistemas de bombeamento e uso de internos de coluna comerciais. Uma análise paramétrica foi executada para a verificação das variáveis mais influentes do processo. A simulação em estado estacionário resultante foi então convertida para o regime dinâmico, onde um esquema de controle equivalente ao esquema de controle da planta real foi implementado. Este esquema de controle foi submetido a um conjunto de perturbações usuais ao processo real, produzindo respostas dinâmicas do processo para cada perturbação aplicada. Pela análise das dinâmicas destas respostas e das respostas do sistema em malha aberta, um esquema de controle alternativo foi proposto e verificado da mesma maneira que o esquema de controle equivalente. Malhas de controle específicas para quantificar a qualidade dos produtos, tendo por base o índice ASTM D86 foram inseridas. A comparação entre os dois esquemas de controle por meio das respostas dinâmicas na qualidade dos produtos, considerando como parâmetro o ISE (Integral Squared Error) das malhas de cada esquema para comparação, apresentou uma redução média do erro em 70% na qualidade dos produtos principais / Abstract: A petroleum vacuum distillation unit study on control scheme strategies is developed in this work. Real plant data and information is gathered from a Brazilian Refinery to develop a representative simulation of the process, which had achieved a maximum 5% overall difference from the plant results. The simulation was set to be highly detailed, including pressure drop calculations, pumping system and the use of commercial column internals (packing and plates) in it. A parametric analysis was carried in order to verify the most influent variables in the process, with respect to temperature profiles, product flows and product qualities. The resultant steady state simulation was then converted into dynamic regime, when a control scheme equivalent to the real plant control scheme was implemented. This control scheme was then subjected to a set of common perturbations that occur in the real process, producing the dynamic response of the process to each perturbation applied. By analyzing the dynamics of these responses and the open loop responses, an alternative control scheme is proposed and verified in the same manner the later one was. A specific control loop was proposed to account a petroleum product quality index, such as ASTM D86 95% recovery. The comparison of the control schemes by means of the dynamic responses considering the correlated ISE (integral squared error) of each scheme has shown an average error reduction of 70% in the main products quality / Doutorado / Desenvolvimento de Processos Químicos / Doutor em Engenharia Química