Добірка наукової літератури з теми "Naphtha Hydrotreating"

Hydrotreating processing is commonly used to remove platforming catalyst poisons from straight run or cracked naphthas prior to charging to the platforming Process unit. It can be seen that the primary function of the naphtha Hydrotreating Process can be characterized as a “Clean up” Operation. The catalyst used in the Naphtha Hydrotreating Process is composed of an alumina base impregnated with compounds of cobalt or nickel and molybdenum. The catalyst is insensitive to most poisons which affect dehydrogenation reactions. A relatively high percentage of carbon on the catalyst does not materially affect its sensitivity or selectivity. Volumetric recoveries of products depend on the sulfur and olefin contents [1]. The Naphtha Hydrotreating Process is a catalytic refining process employing a selected catalyst and a hydrogen-rich gas stream to decompose organic sulfur, oxygen and nitrogen compounds contained in hydrocarbon fractions. In addition, hydrotreating removes organo-metallic compounds and saturates olefinic compounds. Organo-metallic compounds, notably arsenic and lead compounds, are known to be permanent poisons to platinum catalysts. "The complete removal of these materials by Hydrotreating processing gives longer catalyst life in the platforming unit. Sulfur, above a critical level, is a temporary poison to platforming catalysts and causes an unfavorable change in the product distribution. Organic nitrogen is also a temporary poison to platforming catalyst. It is an extremely potent one, however, and relatively small amounts of nitrogen compounds in the Platformer feed can cause large deactivation effects, as well as the deposition of ammonium chloride salts in the platforming unit cold sections. Oxygen compounds are detrimental to the operation of a Platformer. Any oxygen compounds which are not removed in the hydrotreater will be converted to water in the platforming unit, thus affecting the water/ chloride balance of the platforming catalyst. Large amounts of olefins contribute to increase coking of the platforming catalyst. Also, olefins can poly­merize at platforming operating conditions which can result in exchanger and reactor fouling. The Naphtha Hydrotreating Process makes a major contribution to the ease of operation and economy of platforming. Much greater flexibility is afforded in choice of allowable charge stocks to the platforming unit. Because this unit protects the platforming catalyst, it is important to maintain consistently good operation in the Hydrotreating Unit. In addition to treating naphtha for Platformer feed, naphthas produced from thermal cracking processes, such as delayed coking and visbreaking, are usually high in olefinic content and other contaminants, and may not be stable in storage. These naphthas may be hydrotreated to stabilize the olefins and to remove organic or metallic contaminants, thus providing a marketable product.

Hydrotreating process of Sunan candlenut oil by using NiMo-γAl2O3 catalyst has been successfully investigated. Preparation of NiMo-γAl2O3 catalyst by using dipping impregnation method generated catalyst used for hydrotreating process. This method consists of three stages: support activation, impregnation, and calcination. This factors influencing the process including temperature, pressure, and the ratio of Sunan candlenut oil to the H2 gas factor were examined. The hydrotreating product of fuel similar to oil was obtained at a minimum temperature of 380 °C, a pressure of 30–60 bar, and the ratio of the sample to H2 gas of 0.5–1. The diesel fuel from physical properties range for the density of 0.82–0.86 g/cm3, and kinematic viscosity of 2–6 cSt have been fulfilled by hydrotreating result. Gasoline, naphtha, diesel oil, and gas oil products of Sunan candlenut oil were obtained by distillation from hydrotreating process. Sunan candlenut oil fuel qualified fuel requirement.

Reuse of spent hydrodesulphurization (HDS) of middle petroleum fractions catalyst CoMo/γAl2O3 was accomplished via removal of coke and contaminants such as vanadium, Iron, Nickel, and sulfur. Three processes were adopted; extraction, leaching, decoking. Soluble and insoluble coke was removed. Leaching step used three different solvents (oxalic acid, ammonium peroxydisulfate and oxalic acid + H2O2) in separate in order to remove contaminant metals (V, S, Ni and Fe). The effect of soluble coke removal on leaching step was studied. It was found that the removal of soluble coke significantly enhances the leaching of contaminants and barely affected the removal of active metals (Co and Mo). It was found that the best route (sequence) was soluble coke extraction followed by contaminants leaching then decoking process and the best leaching solvent was oxalic acid. According to this determination, the removed contaminants were 79.9 % for sulfur, 13.69% for vanadium, 82.27 % for iron, and 76.34 % for nickel. The active components loss accompanied with this process were 5.08 % for cobalt and 6.88% for molybdenum. Leaching process conditions (leaching solvent concentration, temperature and leaching time) were studied to determine the best-operating conditions. The rejuvenated catalyst activity was examined by a pilot scale HDS unit of naphtha. Sulfur content removal of naphtha was found to be 85.56 % for single pass operation under typical operating conditions of refinery HDS unit of naphtha which are 1 ml/min feed flow rate, 200 H2/HC ratio, 32 bar operating pressure and 320 °C operating temperature.

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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.