Theoretical investigation of aromatics production enhancement in thermal coupling of naphtha reforming and hydrodealkylation of toluene

In the current research, an exothermic reaction is proposed to be coupled with naphtha reforming reactions. Hydrodealkylation (HDA) of toluene, which is a well-known petrochemical reaction, is discussed and is suggested as a potential exothermic reaction to be coupled with the endothermic naphtha reforming reactions. The first, the second, and the third reactor of the conventional naphtha reforming process have been substituted in three different cases by thermally coupled reactors and optimized parameters of the final case have been investigated. Considering lower operational costs due to the elimination of inter stage heaters, investigation of thermally coupled reactors has been the first priority of this research. The investigation shows that substitution of the first two reactors and, in the final case, all conventional reactors by the new configuration can improve the production yield of the aromatics by 14% and 21%, respectively compared with conventional naphtha reforming process. The final case has been optimized as well, and 45% and 11% improvement in aromatics and hydrogen production has been observed.     

Kinetics of coke deposition in naphtha pyrolysis

The effect of run time, surface area, reaction temperature and inlet naphtha partial pressure on the rate of coke formation during naphtha pyrolysis has been investigated in a jet-stirred reactor. The pyrolysis products could be predicted by a model developed earlier for naphtha pyrolysis. Various simplified models for the coke formation involving either the reactant or products were postulated and the kinetic parameters determined by a statistical analysis. The rate of coke formation was best modelled by an approximately second order reaction involving the aromatics.     

A comparative study on optimised and non‐optimised axial flow,spherical reactors in naphtha reforming process

In this study, the operating conditions of an axial flow spherical reactor have been optimised using a reliable optimisation technique and the results are compared with the results of non‐optimised conditions. The dynamic behaviour of the reactor has been considered in the optimisation process and orthogonal collocation method has been used in order to solve the obtained equations from mathematical modelling of the process. The goal of this study is to maximise the aromatics and hydrogen production rate. Therefore, the objective function is the combination of two terms which include the production rate of the mentioned components. The catalyst distribution for each reactor, the inlet pressure of the system, Length per radius for each reactor, the naphtha feed molar flow rate and the hydrogen mole fraction in the recycle stream as well as the inlet temperature of each reactor have been optimised in this study. © 2011 Canadian Society for Chemical Engineering     

Optimal design and operation of a natural gas tri-reforming reactor for DME synthesis

Korea Gas Corporation (KOGAS) is developing a new di-methyl-ether (DME) plant. Syngas is provided by natural gas tri-reforming, in a reactor consisting of a homogenous part where oxidation leads to a temperature increase required for the reforming reactions and a catalytic part where the reforming reactions take place. A first principle model for the tri-reforming reactor is developed. A kinetic mechanism is proposed combining homogeneous gas-phase reactions and heterogeneous catalytic reactions. The proposed model is systematically calibrated and validated with global sensitivity analysis followed by global parameter estimation against concentration measurements of a lab-scale prototype reactor and comparisons of the sensitivity of the outlet as a function of inlet composition and design parameters with experimental results. The validated model is finally used for the optimization of design variables such as length ratio of homogeneous and heterogeneous section and operational variables such as the feed composition.     

Thermal Integration of Sulfuric Acid and Continuous Catalyst Regeneration of Naphtha Reforming Plants

An optimal reactor design is proposed that simultaneously improves the naphtha reforming reactor performance and increases sulfur trioxide production. In this new configuration, the naphtha reforming process as an endothermic reaction is coupled with the oxidation reaction of sulfur dioxide, which is an exothermic reaction. The differential evolution optimization technique is applied to maximize the produced amounts and yields of aromatics and hydrogen. The results obtained with the optimized thermally coupled reactor are compared with those of the conventional and thermally coupled reactors, proving the superiority of the proposed configuration.     

催化重整装置反应器的建模与仿真

针对催化重整装置的流程模拟,基于集总理论与催化重整反应机理,提出了一种反应器的模型。该模型的反应网络较全面地考虑了烷烃、环烷烃及芳烃之间的反应关系,覆盖了重整反应过程中的大部分反应。为了降低参数估计的难度,通过合理假设将待估参数数量减少至99个,并将复杂的反应网络依据碳原子数划分为C₆~C₁₁₊六个反应子网络,再采用BFGS算法与SQP算法相结合的分组迭代估计方法以降低参数估计的误差。通过催化重整装置的模拟计算对模型进行了验证,结果表明,模型能够对反应产物组成进行较准确的预测,可满足现代工业应用对模型精度的需求。     

Simulation of an Industrial Pyrolysis Gasoline Hydrogenation Unit

A model is developed based on a two‐stage hydrogenation of pyrolysis gasoline to obtain a C₆–C₈ cut suitable for extraction of aromatics. In order to model the hydrogenation reactors, suitable hydrodynamic and reaction submodels should be solved simultaneously. The first stage hydrogenation takes place in a trickle bed reactor. The reaction rates of different di‐olefines as well as hydrodynamic parameters of the trickle bed (i.e., catalyst wetting efficiency, pressure drop, mass transfer coefficient and liquid hold‐up) have been combined to derive the equations to model this reactor. The second stage hydrogenation takes place in a two compartment fixed bed reactor. Hydrogenation of olefines takes place in the first compartment while sulfur is eliminated from the flow in the second compartment. These reactions occur at relatively higher temperature and pressure compared to the first stage. The key component in this stage is considered to be cyclohexene, of which the hydrogenation was found to be the most difficult of the olefines present in the feed. The Langmuir‐Hinshelwood kinetic expression was adopted for the hydrogenation of cyclohexene and its kinetic parameters were determined experimentally in a micro‐reactor in the presence of the industrial catalyst. The model was solved for the whole process of hydrogenation, including hydro‐desulfurization. The predictions of the model were compared with actual plant data from an industrial scale pyrolysis gasoline hydrogenation unit and satisfactory agreement was found between the model and plant data.     

催化重整反应38集总动力学模型及其在连续催化重整中的应用

根据集总理论和催化重整的反应机理,基于工业连续重整装置,提出了一个包含38个集总组分、86个反应催化重整反应动力学模型。该模型将重整物料按碳原子数集总为C6～C11+组分,相同碳原子数的物料又划分为正构烷烃、异构烷烃、五元环烷烃、六元环烷烃和芳烃,裂化产物细分为C1～C5组分。通过合理简化,确定了86个待估模型参数,并在工业现场数据的基础上,利用分层策略与BFGS算法对其进行了估计。通过对某炼厂连续重整反应器的模拟计算对该模型进行了验证,计算值与实际值吻合较好,表明该模型具有较好的可靠性与准确性,达到了工业应用的要求。将模型用于芳烃收率的预测,在较大的时间跨度内,精度与趋势均令人满意。最后,利用该模型对芳烃收率进行了优化计算,经优化后芳烃收率提高0.17%,该结果可为连续重整装置的优化操作提供参考。     

Modeling of naphtha reforming unit applying detailed description of kinetic in continuous catalytic regeneration process

Naphtha reforming is one of the most important processes in refineries in which high value-added reformate for gasoline pool and aromatics such as benzene, toluene, and xylene are produced. It is necessary to establish new naphtha reforming units and develop the traditional units to increase the efficiency of the processes. In this study, according to the recent progresses in the naphtha reforming technology, mathematical modeling of this process in continuous catalyst regeneration mode of operation is accomplished in two dimensions (radial and axial) by considering cross flow pattern. In addition, a new catalyst deactivation model has been proposed and a new reaction network model based on 32 pseudo-components with 84 reactions is investigated. Then, this model has been validated by comparing with industrial data, and its results have acceptable agreement.     

催化重整过程的多目标优化

In this article, a multiobjective optimization strategy for an industrial naphtha continuous catalytic reforming process that aims to obtain aromatic products is proposed. The process model is based on a 20-lumped kinetics reaction network and has been proved to be quite effective in terms of industrial application. The primary objectives include maximization of yield of the aromatics and minimization of the yield of heavy aromatics. Four reactor inlet temperatures, reaction pressure, and hydrogen-to-oil molar ratio are selected as the decision variables. A genetic algorithm, which is proposed by the authors and named as the neighborhood and archived genetic algorithm （NAGA）, is applied to solve this multiobjective optimization problem. The relations between each decision variable and the two objectives are also proposed and used for choosing a suitable solution from the obtained Pareto set.     

催化重整过程的多目标优化

In this article, a multiobjective optimization strategy for an industrial naphtha continuous catalytic reforming process that aims to obtain aromatic products is proposed. The process model is based on a 20-lumped kinetics reaction network and has been proved to be quite effective in terms of industrial application. The primary objectives include maximization of.yield of the aromatics and minimization of the yield of heavy aromatics. Four reactor inlet temperatures, reaction pressure, and hydrogen-to-oil molar ratio are selected as the decision variables. A genetic algorithm,which is proposed by the authors and named as the neighborhood and archived genetic algorithm (NAGA), is applied to solve this mulfiobjective optimization problem. The relations between each decision variable and the two objectives are also proposed and used for choosing a suitable solution from the obtained Pareto set.     

Multiobjective Optimization of the Industrial Naphtha Catalytic Re-forming Process

1 INTRODUCTION Petroleum refining and petrochemical industries aim at maximizing one prime product while simulta-neously minimizing another accessory product to im-prove the quality of the prime product. Unfortunately, the two requirements are often conflicting or incon-sistent. It is necessary to determine the trade-off com-promises to balance the two objectives[1,2]. As the core of aromatics complex unit, catalytic reforming is a very important process for transforming naphtha into arom…     

Operability of an Industrial Catalytic Naphtha Reformer in the Presence of Catalyst Deactivation

Bifunctional naphtha reforming catalysts are deactivated by side reactions such as coking, sintering, and poisoning in the course of industrial operation. This results in a reduction of the octane number of the product in a commercial naphtha reforming unit. Catalyst deactivation is compensated for by increasing the operating temperature so that the primary product yields are kept constant during an operating cycle. In the present study, a deactivation model has been developed for industrial catalytic naphtha reformers. The parameters for the deactivation model have been estimated using plant data. The results of the model show that increasing the reactor weighted average inlet temperature (WAIT) can offset the decrease in aromatic yield. Concentration and temperature profiles have been obtained to provide information about the extent of conversion in the individual reactors. Reactor inlet temperature is an important parameter, which can significantly affect reformer performance, the aromatic yield increasing with an increase in temperature.     

Simulation of Secondary Reformer in Industrial Ammonia Plant

In order to develop a reactor design model for the secondary reformer in the industrial ammonia plant, the effectiveness factor and convection heat transfer coefficient between gas and catalyst surface have been studied. The temperature and composition of inlet gas to the catalyst bed are predicted using the kinetic equations of 32 radical reactions. The effect of oxygen content in air on the product synthesis gas composition and the ratio of synthesis gas to nitrogen have been studied. The effectiveness factor has been calculated with the assumption that the steam methane reforming reaction is first order in methane partial pressure. The catalyst shape is assumed to be spherical with an equivalent volumetric diameter. The temperature and composition profiles along the axial distance are predicted using a one‐dimensional heterogeneous catalytic reaction model. The temperatures of both gas and catalyst surface decreased with the axial distance from the top of the bed, while the reactions took place. The temperature difference between gas and catalyst surface also decreased along the axial distance. The predicted temperature and composition by the proposed simulation method have been verified with the data from the industrial plant.     

Modeling of an industrial fixed bed reactor based on lumped kinetic models for hydrogenation of pyrolysis gasoline

In this work, a mathematical model of an industrial fixed bed reactor for the catalytic hydrogenation of pyrolysis gasoline produced from olefin production plant is developed based on a lumped kinetic model. A pseudo-homogeneous system for liquid and solid phases and three pseudo-components: diolefins, olefins, and parraffins, are taken into account in the development of the reactor model. Temperature profile and product distribution from real plant data on a gasoline hydrogenation reactor are used to estimate reaction kinetic parameters. The developed model is validated by comparing the results of simulation with those collected from the plant data. From simulation results, it is found that the prediction of significant state variables agrees well with the actual plant data for a wide range of operating conditions; the developed model adequately represents the fixed-bed reactor.     

神府煤液化油石脑油馏分重整生产芳烃的研究

由于煤液化油石脑油馏分(200℃)中芳烃潜含量较高,利用煤液化油石脑油馏分为原料,进行加氢精制,将原料中的硫氮含量降至1 mg/kg左右,满足重整进料要求,然后在小型固定床连续反应器上进行加氢重整生产芳烃试验。着重考察重整反应前、后族组成的变化及主要芳烃化合物的产率。结果表明,加氢重整过程中发生正构烷烃异构化反应;环烷烃主要发生脱氢芳构化反应转化为芳香烃;煤液化油石脑油馏分适宜进行催化重整,C_1~C_4烃气产率6.03%,氢气产率3.60%;重整后,芳烃含量达83.20%,其中C_6~C_8芳烃含量61.03%,是提取BTX的良好原料。石脑油的馏程对芳烃的组成和产率有一定影响,适宜的馏程为60~160℃。     

The aromatic enhancement in the axial‐flow spherical packed‐bed membrane naphtha reformers in the presence of catalyst deactivation

Because of some disadvantages of conventional tubular reactors (CTRs), the concept of spherical membrane reactors is proposed as an alternative. In this study, it is suggested to apply hydrogen perm‐selective membrane in the axial‐flow spherical packed‐bed naphtha reformers. The axial flow spherical packed‐bed membrane reactor (AF‐SPBMR) consists of two concentric spheres. The inner sphere is supposed to be a composite wall coated by a thin Pd‐Ag membrane layer. Set of coupled partial differential equations are developed for the AF‐SPBMR model considering the catalyst deactivation, which are solved by using orthogonal collocation method. Differential evolution optimization technique identifies some decision variables which can manipulate the input parameters to obtain the desired results. In addition to lower pressure drop, the enhancement of aromatics yield by the membrane layer in AF‐SPBMR adds additional superiority to the spherical reactor performance in comparison with CTR. © 2011 American Institute of Chemical Engineers AIChE J, 2011     

Detailed description of kinetic and reactor modeling for naphtha catalytic reforming

Kinetic and reactor modeling of catalytic reforming of naphtha is described in the present work. The development of a kinetic reforming model is reported with detail. The validation of the developed kinetic model with bench-scale isothermal reactor experiments is also carried out. The kinetic and reactor models are applied for the simulation of commercial semi-regenerative reforming unit. The effect of benzene precursors in the feed in both laboratory and commercial reactors is also simulated, and the use of the reactor model to predict other process parameters is highlighted.     

工业级催化重整装置的全流程模拟与优化

1 INTRODUCTION Catalytic naphtha reforming is a very important process for producing high octane gasoline, aromatic feedstock and hydrogen in petroleum-refining and petrochemical industries[1]. To design new plants and optimize the existing ones, an appropriate mathema- tical model for simulating the industrial catalytic re-forming process is needed[2,3]. The naphtha used as catalytic reforming feed-stock is very complex usually consisting of about three hundred hydrocarbons with carbon nu…     

A novel dynamic membrane reactor concept with radial‐flow pattern for reacting material and axial‐flow pattern for sweeping gas in catalytic naphtha reformers

Naphtha reforming units are of high interest for hydrogen production in refineries. In this regard, the application of membrane concept in radial‐flow tubular naphtha reactors for hydrogen production is proposed. Because of the importance of the pressure drop problem in catalytic naphtha reforming units, the radial‐flow reactors are proposed. A radial‐flow tubular membrane reactor (RF‐TMR) with the radial‐flow pattern of the naphtha feed and the axial‐flow pattern of the sweeping gas is proposed as an alternative configuration for conventional axial‐flow tubular reactors (AF‐TR). The cross‐sectional area of the tubular reactor is divided into some subsections in which walls of the gaps between subsections are coated with the Pd‐Ag membrane layer. A dynamic mathematical model considering radial and axial coordinates ((r, z)‐coordinates) has been developed to investigate the performance of the new configuration. Results show ～300 and 11 kg/h increase in aromatic and hydrogen production rates in RF‐TMR compared with AF‐TR, respectively. Furthermore, smaller catalyst particles with higher efficiency can be used in RF‐TMR due to a slight pressure drop. The enhancement in aromatics (octane number) and hydrogen productions owing to applying simultaneously the membrane concept and radial‐flow pattern in naphtha reactors motivates the application of RF‐TMR in refineries. © 2011 American Institute of Chemical Engineers AIChE J, 2012