Catalytic hydrotreating (HDT) is a mature process technology practiced in the petroleum refining industries to treat oil fractions for the removal of impurities (such as sulfur, nitrogen, metals, asphaltene). Hydrotreating of whole crude oil is a new technology and is regarded as one of the more difficult tasks that have not been reported widely in the literature. In order to obtain useful models for the HDT process that can be confidently applied to reactor design, operation and control, the accurate estimation of kinetic parameters of the relevant reaction scheme are required. This thesis aims to develop a crude oil hydrotreating process (based on hydrotreating of whole crude oil followed by distillation) with high efficiency, selectivity and minimum energy consumption via pilot plant experiments, mathematical modelling and optimization. To estimate the kinetic parameters and to validate the kinetic models under different operating conditions, a set of experiments were carried out in a continuous flow isothermal trickle bed reactor using crude oil as a feedstock and commercial cobaltmolybdenum on alumina (Co-Mo/¿-Al2O3) as a catalyst. The reactor temperature was varied from 335°C to 400°C, the hydrogen pressure from 4 to10 MPa and the liquid hourly space velocity (LHSV) from 0.5 to 1.5 hr-1, keeping constant hydrogen to oil ratio (H2/Oil) at 250 L/L. The main hydrotreating reactions were hydrodesulfurization (HDS), hydrodenitrogenation (HDN), hydrodeasphaltenization (HDAs) and hydrodemetallization (HDM) that includes hydrodevanadization (HDV) and hydrodenickelation (HDNi). An optimization technique is used to evaluate the best kinetic models of a trickle-bed reactor (TBR) process utilized for HDS, HDAs, HDN, HDV and HDNi of crude oil based on pilot plant experiments. The minimization of the sum of the squared errors (SSE) between the experimental and estimated concentrations of sulfur (S), nitrogen (N), asphaltene (Asph), vanadium (V) and nickel (Ni) compounds in the products, is used as an objective function in the optimization problem using two approaches (linear (LN) and non-linear (NLN) regression). The growing demand for high-quality middle distillates is increasing worldwide whereas the demand for low-value oil products, such as heavy oils and residues, is decreasing. Thus, maximizing the production of more liquid distillates of very high quality is of immediate interest to refiners. At the same time, environmental legislation has led to more strict specifications of petroleum derivatives. Crude oil hydrotreatment enhances the productivity of distillate fractions due to chemical reactions. The hydrotreated crude oil was distilled into the following fractions (using distillation pilot plant unit): light naphtha (L.N), heavy naphtha (H.N), heavy kerosene (H.K), light gas oil (L.G.O) and reduced crude residue (R.C.R) in order to compare the yield of these fractions produced by distillation after the HDT process with those produced by conventional methods (i.e. HDT of each fraction separately after the distillation). The yield of middle distillate showed greater yield compared to the middle distillate produced by conventional methods in addition to improve the properties of R.C.R. Kinetic models that enhance oil distillates productivity are also proposed based on the experimental data obtained in a pilot plant at different operation conditions using the discrete kinetic lumping approach. The kinetic models of crude oil hydrotreating are assumed to include five lumps: gases (G), naphtha (N), heavy kerosene (H.K), light gas oil (L.G.O) and reduced crude residue (R.C.R). For all experiments, the sum of the squared errors (SSE) between the experimental product compositions and predicted values of compositions is minimized using optimization technique. The kinetic models developed are then used to describe and analyse the behaviour of an industrial trickle bed reactor (TBR) used for crude oil hydrotreating with the optimal quench system based on experiments in order to evaluate the viability of large-scale processing of crude oil hydrotreating. The optimal distribution of the catalyst bed (in terms of optimal reactor length to diameter) with the best quench position and quench rate are investigated, based upon the total annual cost. The energy consumption is very important for reducing environmental impact and maximizing the profitability of operation. Since high temperatures are employed in hydrotreating (HDT) processes, hot effluents can be used to heat other cold process streams. It is noticed that the energy consumption and recovery issues may be ignored for pilot plant experiments while these energies could not be ignored for large scale operations. Here, the heat integration of the HDT process during hydrotreating of crude oil in trickle bed reactor is addressed in order to recover most of the external energy. Experimental information obtained from a pilot scale, kinetics and reactor modelling tools, and commercial process data, are employed for the heat integration process model. The optimization problem is formulated to optimize some of the design and operating parameters of integrated process, and minimizing the overall annual cost is used as an objective function. The economic analysis of the continuous whole industrial refining process that involves the developed hydrotreating (integrated hydrotreating process) unit with the other complementary units (until the units that used to produce middle distillate fractions) is also presented. In all cases considered in this study, the gPROMS (general PROcess Modelling System) package has been used for modelling, simulation and parameter estimation via optimization process. / Tikrit University, Iraq

科学研究費補助金 研究種目:一般研究(C) 課題番号:62550695 研究代表者:中村 正秋 研究期間:1987-1988年度

Submitted by Irene Nascimento (irene.kessia@ufpe.br) on 2016-10-13T19:12:36Z No. of bitstreams: 1 Dissertação de Mestrado PPEQ - Alexsandro Fausto de Araújo.pdf: 3235090 bytes, checksum: e4c74119c72ea3471a47fb36a515e632 (MD5) / Made available in DSpace on 2016-10-13T19:12:36Z (GMT). No. of bitstreams: 1 Dissertação de Mestrado PPEQ - Alexsandro Fausto de Araújo.pdf: 3235090 bytes, checksum: e4c74119c72ea3471a47fb36a515e632 (MD5) Previous issue date: 1998-11-13 / Com a crescente exigência dos mercados e da sociedade por produtos derivados do petróleo cada vez mais livres de contaminantes que prejudicam o meio ambiente e a qualidade dos mesmos, os parques de refino de petróleo vêm investindo cada vez mais em tecnologias que permitam uma produção mais limpa, rentável e econômica. Desse modo, O hidrotratamento tem assumido um papel cada vez mais importante dentro das refinarias, sendo aplicado em diversos cortes do petróleo, desde os mais leves até os mais pesados. O hidrotratamento consiste na adição de hidrogênio na carga a ser hidrotratada com o propósito de, através de reações de hidrogenação, reduzir ou eliminar os componentes contaminantes presentes na carga, como o enxofre, nitrogênio, oxigênio, olefinas, diolefinas e metais. A adição de hidrogênio é feita em cocorrente descendente, onde a carga e o hidrogênio entram misturados e pré aquecidos no topo do reator a uma razão pré-definida (Razão H2/Carga), sendo esta forma a mais utilizada em escala industrial devido aos seus inúmeros benefícios. O foco da unidade de HDT é o reator, pois é nele que os contaminantes são removidos da carga. O tipo de reator mais utilizado é o de leito fixo (Trickle Bed Reactor - TBR). A nafta é a principal matéria prima do setor petroquímico nacional, de modo que todas as unidades instaladas são baseadas nela. A partir dela são produzidos os componentes da primeira geração do setor petroquímico. O HDT de nafta ainda é um tema pouco explorado mas que vem recebendo maior importância nos últimos anos. Por isso, este trabalho foi desenvolvido sobre esse tema, construindo e simulando modelos dinâmicos de reatores de leito fixo, com alimentação em cocorrente de uma unidade reacional de HDT de nafta, composta por um reator trifásico de conversão de diolefinas, utilizado para o pré-tratamento da nafta de coqueamento retardado e dois reatores bifásicos (G-S) de HDT de nafta, dispostos em série com resfriamento por quenchs independentes entre os leitos dos reatores e entre os reatores, para a redução de teores de enxofre, nitrogênio e olefinas presentes na nafta através das reações de hidrodessulfurização, hidrodesnitrogenação e saturação de olefinas. Foram construídos dois programas em ambiente MATLAB®, um para simular o reator trifásico de conversão diolefinas e outro para os reatores bifásicos de HDT de nafta, ambos simularam correntes de alimentação de nafta com diferentes níveis de contaminação, para que fossem avaliados os efeitos. Os programas simularam os perfis dinâmicos das temperaturas das fases envolvidas e das concentrações dos contaminantes e hidrogênio. Os resultados obtidos para o reator de conversão de diolefinas e os reatores de HDT de nafta se mostraram bem coerentes com relação aos fenômenos envolvidos. O reator de conversão de diolefinas atingiu o estado estacionário aos 80 minutos e os reatores de HDT de nafta aos 2 minutos, com os teores de contaminantes próximos de zero na saída do reator. Os resultados das simulações realizadas para os dois tipos de nafta apresentaram perfis dinâmicos semelhantes diferindo apenas quanto à temperatura mais elevada atingida no início do primeiro reator de HDT de nafta no caso da nafta com maior teor de contaminação. / With the growing demand of markets and society by oil products increasingly free of contaminants that harm the environment and their quality, oil refining plants have been increasingly investing in technologies to cleaner production, profitable and economical. Thus, the hydrotreating has assumed an increasingly important role in the refinery and is used in many petroleum cuts, from the lightest to the heaviest. The hydrotreating is the addition of hydrogen in the load to be hydrotreated in order to, via hydrogenation reactions, reduce or eliminate the contaminating components present in the load, such as sulfur, nitrogen, oxygen, olefins, diolefins and metals. The addition of hydrogen is done in descending current, where load and hydrogen enter mixed and pre heated at the top of the reactor to a pre-defined (ratio H2/Oil), and this way the most used at industrial scale due to its numerous benefits. The focus of the HDT unit is the reactor, because that is where the contaminants are removed from the load. The most used type of reactor is the fixed bed (Trickle Bed Reactor - TBR). Naphtha is the main raw material of the national petrochemical industry, so that all installed units are based on it. From there, the components of the first generation of the petrochemical industry are produced. The naphtha HDT is still a subject little explored but it's getting more important in recent years. Therefore, this study was conducted on this issue, building and simulating dynamic models of fixed bed reactors with feed in cocurrente of a reactional unit of HDT naphtha, consisting of a three-phase reactor diolefins conversion, used for pretreatment naphtha delayed coking and two dual-phase reactors (G-S) naphtha HDT arranged in series with cooling by independent quenchs between beds of the reactor and between the reactors to reduce contents of sulfur, nitrogen and olefins present in the naphtha through reactions of hydrodesulfurization, hidrodesnitrogenação and saturation of olefins. Were built two programs in MATLAB®, one to simulate the three-phase reactor diolefins conversion and one for the dual-phase reactors naphtha HDT, both simulated currents naphtha feed with different levels of contamination, so that the effects are assessed. The simulated programs dynamic profiles of the temperatures of the phases involved and the concentrations of contaminants and hydrogen. The results obtained for diolefins conversion reactor and the reactors of naphtha HDT were well consistent with relation to the phenomena involved. The diolefins conversion reactor reached steady state at 80 minutes and the HDT reactors naphtha after 2 minutes, with near zero contaminant levels in the reactor output. The results of simulation performed for the two types of naphtha showed similar dynamic profiles differing only as to the highest temperature reached at the beginning of the first naphtha HDT reactor in the case of naphtha higher contamination level.

Hydrering är en viktig process för att producera produkter med önskade egenskaper samt att uppfylla de lagliga krav som existerar med avseende på miljö och hälsa. Reaktionerna som sker vid hydreringen är katalytiska vilket innebär att förstå sam utnyttja de mest lämpliga katalysatorerna är av yttersta vikt. Avsvavling (HDS) är en av de mest studerade reaktionerna medan avaromatisering (HDA) samt borttagandet av kväve (HDN) är diskuterade samt förstådda i lägre grad. Trots det är aromatiska samt kväverika föreningar naturligt förekommande i matningar till hydreringsreaktorerna där de organiska kväveföreningarna är inhibitorer. I detta arbete är målet att tillverka samt utvärdera några hydreringskatalysatorer med fokus på deras prestanda för HDA och HDN reaktionerna. Den bästa möjliga tekniken idag för tillverkningen av hydreringskatalysatorer utnyttjar kelateringsreagens vid beredningen. Detta har visat sig ha en positiv inverkan på egenskaperna och aktivteten vid hydrering för NiMo-katalysatorer. För att undersöka detta närmare har två typer av katalysatorer tillverkats, en med kelateringsreagens (typ II) och en utan (typ I). Dessa var sedan utvärderade i dess HDA och HDN aktiveter. Katalysatorerna var tillverkade samt karaktäriserade vid KTH och sedan aktiverade via sulfidering samt utvärderade vid Nynas AB. Aktiviteten för de sulfiderade katalysatorerna var utvärderade i ett surrogatsystem bestående av fenantren (PHE) som modell för aromatiska föreningar samt karbazol (CBZ) eller akridin (ACR) som modell för icke-basiskt samt basiskt organisk-kväve. Aktivitetsutvärderingen utfördes i en porlbäddreaktor där aktiviteten undersöktes vid närvarandet samt avsaknandet av de organiska kväveföreningarna. När matningen byttes, en så kallad modeswitch, ändras aktiviteten beroende på de betingelser som undersöktes. Reaktortemperaturen varierade mellan 300 °C och 320 °C vid ett konstant systemtryck på 120 barg. Katalysatornsaktivitet var positivt korrelerad med reaktortemperaturen där en lägre aktivtetuppmättes vid 300 °C jämfört med 320 °C. Det visade sig även att båda typerna av organiskt kväve påverkade aktivteten negativt vid båda undersökta temperaturerna. Utöver det så var de basiska kväveföreningarna mer inhiberande jämfört med de icke-basiska föreningarna för båda katalysatorerna. Inhiberingen orsakad av karbazol visade sig vara helt reversibel medan akridininhiberingen antydde på mer permanenta effekter för typ II katalsatorn. Dessa resultat antyder, trots de preliminära antagandena, att typ I katalysatorn var bättre än typ II katalysatorn. / Hydrotreating processes are of high importance in helping to obtain the desired characteristics of products as well as to comply with the legislation regarding health hazards and environmental pollution. Hydrotreating reactions are catalytic reactions which imply that the understanding and utilization of the most suitable catalysts is crucial. While hydrodesulfurization is a vastly studied branch of hydrotreating, hydrodearomatization (HDA), and hydrodenitrogenation (HDN) processes are less discussed and understood. However, aromatic compounds along with nitrogen-containing inhibitors are naturally present in the hydrotreater feeds. Therefore, the aim of this study was the preparation and evaluation of hydrotreating catalysts with the main focus on HDA and HDN reactions. According to the current state of the art, the utilization of chelating agents during preparation has a positive impact on the characteristics and activity of hydrotreating catalysts therefore NiMo catalysts with (Type II) and without (Type I) a chelating agent were prepared and evaluated towards HDA and HDN reactions. The catalysts were prepared and characterized at KTH and then activated (sulfided) and evaluated at Nynas AB. The activity of the sulfided catalysts was evaluated using surrogate mixture models containing phenanthrene (PHE) as an aromatic compound, and carbazole (CBZ) or acridine (ACR). The latter ones were representing two types of nitrogen-containing inhibitors, non-basic and basic. The activity testing was carried out in a trickle-bed microreactor during three-step experiments in the presence and absence of the organic nitrogen compounds (mode switches). During the mode switches the activity of the catalysts under varying conditions was investigated. The operating temperature of the reactor varied between 300 and 320°C under constant H2 pressure of 120 barg. The catalytic activity was positively correlated with temperature with the catalysts exhibiting lower activities at 300°C than at 320°C. It is noteworthy that the activity of all the catalysts was hindered by the presence of both nitrogen compounds at all temperatures with the basic nitrogen (ACR) being more inhibitory for both catalysts. CBZ inhibition to the HDA reactions showed reversibility, while ACR had a more permanent inhibiting effect in the case of the Type II catalyst. The results indicated that despite the preliminary assumptions, the Type I catalyst outperformed the Type II.

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