Narciso Pérez - Academia.edu (original) (raw)

Papers by Narciso Pérez

Zenodo (CERN European Organization for Nuclear Research), Oct 20, 2017

Se evaluó el efecto del tipo de alimentación sobre el rendimiento y la calidad de los productos d... more Se evaluó el efecto del tipo de alimentación sobre el rendimiento y la calidad de los productos de la coquización retardada procesando mezclas con concentraciones controladas de los grupos fundamentales (saturados, aromáticos, resinas y asfaltenos, S.A.R.A.) provenientes de residuos de vacío de crudos venezolanos. Cada una de las mezclas procesadas tiene uno de los grupos fundamentales en una concentración superior al 50 % másico. El proceso se realizó a escala laboratorio, fueron determinados los rendimientos de los productos y se realizó la caracterización físicoquímica de las mezclas preparadas y de los productos obtenidos (coque y líquidos). Los resultados mostraron que al incrementar la concentración de resinas y asfaltenos o al disminuir la concentración de aromáticos y saturados en la alimentación, se obtiene un incremento del rendimiento de coque y gas, y una disminución en el rendimiento de los líquidos. Con respecto a los análisis fisicoquímicos, se observó que en todos los casos, las variables medidas (relación C/H, contenido de metales y azufre) cambian de forma importante a medida que aumenta la presencia de fracciones más polares y condensadas. Estos resultados corresponden con las tendencias teóricas esperadas y evidencian que cada grupo constituyente tiene un efecto notoriamente diferente en los productos obtenidos en el proceso.

The Orinoco Belt is the largest known heavy and extra-heavy petroleum reserve worldwide. To turn ... more The Orinoco Belt is the largest known heavy and extra-heavy petroleum reserve worldwide. To turn this type of crude oil into useful products, it must be subjected to upgrading processes. One of these processes is delayed coking; which, in addition to light products, yields up to 30%w petroleum coke. The direct combustion of the coke produced is limited due to its high sulfur, nickel and vanadium content. The aim of the present work was to develop a low cost adsorbent for the separation of the abovementioned metals from petroleum products. Lignin was considered for this purpose, since it is a low cost waste product from the paper industry and has been used with satisfactory results for the removal of Ni from wastewaters. In order to evaluate the feasibility of using lignin as a large scale bioadsorbent for nickel, best adsorbing condition were determined. For this, lignin was soaked with nickel containing acid solutions varying parameters such as mg Ni solution/ g lignin, contact tim...

In the Delayed Coking process (DC), it is well known the influence of the type of feedstock on co... more In the Delayed Coking process (DC), it is well known the influence of the type of feedstock on coke characteristics and overall yield products for a given set of operation condition. Considering that Venezuela is the world's second producer of oil coke, it is important to understand the mechanisms of transformations taking place inside the coke drum. To this end reaction systems should be developed, which simulate the product concentration data. Therefore, the objective of this paper is to propose a mechanism to predict kinetic of DC using Venezuelan vacuum residual as feed. The chemistry of the DC process suggests that kinetic studies of such a complex system can be carried out considering a few reactions. Three kinetic models (two proposed by Del Bianco and one by Yue) were used to simulate the reaction kinetics of DC with four series of experimental data (each series at a different temperature), obtained from one Venezuelan crude type. Finding out, first, that one of Del Bian...

Zenodo (CERN European Organization for Nuclear Research), May 29, 2019

The effect of resin and asphaltene concentration in the feed, on the yield of delayed coking prod... more The effect of resin and asphaltene concentration in the feed, on the yield of delayed coking products was assessed, feeding controlled concentrations of the groups: saturates, aromatics, resins and asphaltenes (SARA) (50-100%w/w of asphaltene or resin and a fixed mass ratio of the others groups) prepared from a Venezuelan vacuum residue. The results of yield of products obtained in a laboratory-scale process show, that the increases of concentration of resins or asphaltenes raise yield of coke and decreases the not-condensable. The distillates yield remained at levels close to zero (<1%w/w) when asphaltene rich blends where fed, while in case of resin rich blends, the amount of distillate produced increased when the resins contents increased. These results are consequence of a higher condensation level of the molecules present in the crude. For distillates, a discriminatory behaviour occurred depending on in which fraction was rich the blend fed to the process, with yields in the order of 20-40% w/w for the mixtures rich in resins and practically equal to zero in the case of mixtures rich in asphaltenes.

Revista Latinoamericana de Metalurgia y Materiales, May 30, 2019

Revista Latinoamericana de Metalurgia y Materiales, Oct 21, 2017

Se evaluó el efecto del contenido de aromáticos sobre la calidad de los productos d... more Se evaluó el efecto del contenido de aromáticos sobre la calidad de los productos de coquización retardada. Para lograr este objetivo, se procesaron 5 mezclas con un contenido de las fracciones S.A.R.A. (saturados, aromáticos, resinas y asfaltenos) controlado, provenientes de un residual de vacío del crudo venezolano denominado comercialmente “Merey”. Las mezclas tienen un porcentaje de aromáticos de 40 a 60 %p, las cuales fueron procesadas en una unidad de coquización retardada a escala laboratorio y se caracterizaron fisicoquímicamente las mezclas y los productos líquidos condensables y coque (no destilados) obtenidos. Los resultados muestran que al aumentar el contenido de aromáticos, aumenta el porcentaje de materia volátil y disminuye el porcentaje de carbono fijo, cenizas y metales, por lo que es posible modificar las características de los productos obtenidos por medio de cambios e...

Revista Latinoamericana de Metalurgia y Materiales, Apr 10, 2015

Latin American applied …, 2007

The adsorption process of Nickel and Vanadium dissolved in acid liquor on lignin is studied in th... more The adsorption process of Nickel and Vanadium dissolved in acid liquor on lignin is studied in this work. Different adsorption isotherm models are used to adjust liquid-solid systems: Langmuir, Freundlich and Redlich-Peterson. It was obtained that the metal adsorption using lignin proceeds by similar chemical mechanisms. Possibly the Nickel is adsorbed in heterogeneous monolayers, contrary to Vanadium which is adsorbed in homogeneous ones. Results of the parameters obtained for every adsorption model and adsorption system are reported too.

El presente trabajo surge de la necesidad de estimar el perfil de condensado en tuberias de produ... more El presente trabajo surge de la necesidad de estimar el perfil de condensado en tuberias de produccion de gas natural, como parte del desarrollo de un paquete de simulacion comercial que, empleando los modelos termodinamicos propuestos por Soave, Peng-Robinson y Kabaddi-Danner, estime las caracteristicas de la formacion de condensado y agua en las tuberias de produccion de seis pozos de gas natural. Se diseno un algoritmo de calculo que permite estimar el perfil de condensado en segmentos de tuberia utilizando el modelo de equilibrio Phi-Phi. Se desarrollaron las ecuaciones de balance de materia para equilibrio liquido-vapor (LV) y liquido-liquido-vapor (LLV), asi como el uso de las ecuaciones cubicas en la determinacion de los coeficientes de fugacidad y las constantes de reparto de las sustancias, en las cuales los valores iniciales se estimaron a partir de la correlacion de Wilson. Finalmente se compararon los resultados obtenidos respecto a datos de campo y se determino que el e...

Esta investigacion presenta una comparacion de dos procesos existentes en la actualidad que han d... more Esta investigacion presenta una comparacion de dos procesos existentes en la actualidad que han demostrado su aplicabilidad en el mejoramiento de crudos. Son empleados para la precipitacion de asfaltenos a nivel laboratorio con un residuo de vacio denominado Merey, de origen venezolano, en la busqueda de alternativas que involucren la reduccion del disolvente y de la energia, necesarios para el proceso de desasfaltado existente. Los metodos escogidos fueron: metodo de agitacion (referencia), metodos de irradiacion con microondas y con ultrasonido (emergentes). Se disenaron pruebas que permitieran, a partir de la determinacion de rendimiento y la caracterizacion via espectroscopia de infrarrojo por transformada de Fourier de los solidos obtenidos, establecer el potencial que tienen los metodos emergentes en la precipitacion de asfaltenos. Los resultados muestran que el metodo de irradiacion con microondas presenta el mayor rendimiento obtenido con una desviacion de 36 % (por encima) ...

espanolSe sintetizaron hidrogeles interpenetrados (IPN) mediante polimerizacion via radical en so... more espanolSe sintetizaron hidrogeles interpenetrados (IPN) mediante polimerizacion via radical en solucion acuosa de acrilamida (Aam) y anhidrido maleico (MAH) en presencia de peroxidisulfato de Amonio como iniciador, N,N’-metilen-bis-acrilamida como monomero entrecruzante y lignina comercial Indulin AT como fase interpenetrada. Se estudio, mediante un diseno factorial 2n, el efecto de la cantidad de fase interpenetrada tipo lignocelulosica y la composicion de los hidrogeles sobre la sintesis y el proceso de hinchamiento de hidrogeles tipo IPN. Los resultados obtenidos demostraron que la estructura quimica del copolimero y la presencia de la fase interpenetrada, en lo que respecta a la cantidad de grupos funcionales hidrofilos presentes en la matriz o una mayor hidrofobia en el sistema, juegan un papel importante en la absorcion de agua, pudiendose alcanzar capacidades de hinchamiento por encima de 13.000% al variar la composicion de las mezclas. EnglishInterpenetrated Polymer Network ...

Interciencia, 2016

De los 23 paises que conforman la region de America Latina y el Caribe (LAC) 18 cuentan con regul... more De los 23 paises que conforman la region de America Latina y el Caribe (LAC) 18 cuentan con regulaciones propias vigentes de calidad de aire, de acceso publico a traves de sitios web oficiales. Se establece la trazabilidad de esas regulaciones para los contaminantes de criterio (PM10, PM2,5, SO2, NO2, O3, CO), usando como referencia el historico de estandares de la Agencia de Proteccion Ambiental de los EEUU (USEPA) y los valores guia de la Organizacion Mundial de la Salud (OMS). Se identifican los programas de monitoreo atmosferico llevados a cabo por pai- ses LAC y la difusion de esa informacion en sitios web oficiales. Con respecto a sistemas de monitoreo de calidad de aire se encontro que 15 paises LAC recolectan datos sobre concentracion de algunos contaminantes de criterio, 13 la publican total o parcialmente en sitios web oficiales, y cinco lo hacen en tiempo real. El material particulado en sus diferentes tamanos (PTS, PM10 o PM2,5) es el contaminante de criterio mas monitor...

An experimental setup was developed at laboratory scale to reproduce the performance and quality ... more An experimental setup was developed at laboratory scale to reproduce the performance and quality of products of the Delayed Coking process, using intermediates products from Venezuelan refineries. The assembly developed allowed to collect all the liquid and solid products generated. The experimental design allowed us to evaluate the effect of the conditions of design and operation involved, such as drum temperature, reaction time, ramps of heating inside the furnace and orientation of the reactor. The results of characterization of the products composition of metals, optical texture, MBE (solid), indicate that all design and operating conditions studied have an impact on the characteristics and composition of the final product and that a detailed study of the relations between the conditions and the properties of the products would propose reaction mechanisms and better conditions of operation to get liquid products of commercial quality and coke with morphological properties approp...

In this study, the impact of the pre- cipitation process over the adsorption capability o f Nicke... more In this study, the impact of the pre- cipitation process over the adsorption capability o f Nickel and Vanadium of precipitated lignins of Kraft black liquor was studied. The studied conditions of precipitation were: mixing (shaking and stirring), mixing speed and mixing sequence. To determine the best lay out for the studied conditions, the quanti ty of produced adsorbent by precipitation and its ad- sorption capability were correlated. It was deter- mined that the type of mixing in the process of pre - cipitation affects the adsorption capability of lig nins and conditions for a higher adsorption capability o f each of the studied metals were determined.

Se evaluo el efecto de la composicion de aromaticos sobre el rendimiento de los productos de coqu... more Se evaluo el efecto de la composicion de aromaticos sobre el rendimiento de los productos de coquizacion retardada. Para ello se dispuso de un residual de vacio del crudo venezolano denominado comercialmente “Merey”, al cual se le realizo una separacion S.A.R.A. para obtener fracciones de hidrocarburos (saturados, aromaticos, resinas y asfaltenos) que permitieron la preparacion de cinco mezclas de composicion controlada de estas fracciones con un porcentaje de aromaticos de 40 a 60 %p. La coquizacion de las mezclas de composicion controlada se realizo en una unidad de coquizacion retardada disponible en el Laboratorio de Carbon y Residuales de Petroleo de la Universidad Simon Bolivar, a una temperatura de 650⁰C, rampa de calentamiento de 5⁰C/min, tiempo de reaccion 60 min, y 150 ml/min de nitrogeno de arrastre. Los resultados muestran que, al aumentar el contenido de aromaticos en la alimentacion, aumenta el rendimiento de materia volatil y disminuye el rendimiento de coque, para lo...

Latin American Applied Research, 2012

 Lignins were precipitated from Kraft black liquor to different acidic conditions; subsequently... more  Lignins were precipitated from Kraft black liquor to different acidic conditions; subsequently were subjected to oxidative treatment with KMnO4. The oxidized material was characterized using IR spectroscopy for structural elucidation, and potentiometry in aqueous medium for determination of carboxylic groups. Among the trends, it found that the proportion of carboxylic groups in lignins increases with the oxidative treatment of the lignin. In addition with the IR were identified functional groups characteristic of lignin and showed also the changes caused by oxidative modification confirming the increase of oxidized groups when comparing the spectra of the different materials. Known the effects of oxidation on the lignins was evaluated adsorptive capacity of the oxidized lignin, showing that the oxidized lignin was able to adsorb up to 98% of Ni available initially, which corresponds to an increase in this ion sorption capacity of the double with respect to which only was precipi...

In the present study an analysis of the adsorption of Ni and V on lignin from national black liqu... more In the present study an analysis of the adsorption of Ni and V on lignin from national black liquor was carried out using thermodynamic principles. A comparison was established between both the precipitated lignins and one commercial analytical grade lignin. The adsorptive capacity of both materials was evaluated through the construction of isotherms whose data was fitted to the following models: Freundlich, Langmuir and Redlich - Peterson. For all these models, the best fit for the obtained data was the one of Langmuir’s. For the adsorption process, the thermodynamic parameters ΔGo, ΔHo y ΔSo, were also calculated. The adsorption enthalpy yielded values of less than 40 KJ / mol, which can not clarify what type of adsorption (physical or chemical) is ocurring, since both types of adsorption may be present. With respect to the Gibbs free energy, negative values were obtained for the adsorption of Ni, suggesting a spontaneous process, while for V values were positive, suggesting a not...

En el presente trabajo se sintetizaron hidrogeles interpenetrados de acrilamida (AAm)/anhidrido m... more En el presente trabajo se sintetizaron hidrogeles interpenetrados de acrilamida (AAm)/anhidrido maleico (AM), en presencia de peroxidisulfato de Amonio como iniciador y N,N’-metilen-bis-acrilamida como monomero entrecruzante (AE), utilizando como fase interpenetrada lignina Indulin AT (LN) carbonizada y sin carbonizar. Se estudio la influencia del grado de entrecruzamiento y la composicion de los hidrogeles sintetizados sobre el proceso de hinchamiento. La caracterizacion se llevo a cabo mediante las tecnicas de Espectroscopia Infrarroja con Transformada de Fourier (FTIR), Microscopia Electronica de Barrido (MEB) y del estudio del proceso de hinchamiento y desorcion a temperatura ambiente. Se comprobo que la incorporacion de lignina a los sistemas y las diferentes proporciones de AAm/AM/AE en los mismos, afecta la capacidad de hinchamiento de los geles. Se alcanzaron capacidades de hinchamiento de 13343% y se comprobo que el tipo de lignina utilizada influye directamente en las prop...

The adsorption process of Ni and V with lignin as adsorbent in acid solution is of chemical type ... more The adsorption process of Ni and V with lignin as adsorbent in acid solution is of chemical type (chemisorption), so an increase in the groups that function as active sites for adsorption on lignin should increase the adsorptive capacity of the same. A modification of the lignin was raised, by means of adding nitro groups and using the nitric acid (HNO3) as nitration agent in sulfuric acid, and then was evaluated its effect on the adsorption of Ni and V. For this, an experimental design of type 2 4 was used, in which four operational variables were studied. These variables were selected as those that during the nitration could affect the amount of active sites, such as nitric acid concentration, temperature, time and stirring rate of nitration. From this experimental work were obtained lignins with high adsorption capacity for both metals. A statistical analysis showed that between the four operational variables studied, only concentration of HNO3 and the temperature of nitration, g...