A Four Lump Kinetic Model for the Simulation of the Hydrocracking Process

Abstract:

Hydrocracking is a very important secondary refining process used to convert low value vacuum gas oils into high value fuels. The chemistry of the hydrocracking process is very complex due to the involvement of high molecular weight complex hydrocarbons in the reactions. Process modeling and simulation of the hydrocracking unit is very challenging due to the complexities of chemistry and the process. In the present work, a mathematical model is described to analyze the performance of the hydrocracking process in terms of product yields. A four lump discrete lumping approach is employed with a hydrocracking reaction scheme involving six reactions. The kinetic constants for the reactions were estimated by minimizing the error between the experimental and predicted yields of kinetic lumps. Experimental data reported by Ali et al. (2002) Ali, M. A., Tatsumi, T. and Masuda, T. 2002. Development of heavy oil hydrocracking catalysts using amorphous silica-alumina and zeolites as catalyst supports. Applied Catalysis A: General, 233: 77–90. [CSA][Crossref], [Web of Science ®] , [Google Scholar] were used to validate the proposed model. The model predictions were found to agree well with the experimental data. The proposed model can be used to simulate the performance of commercial hydrocrackers using kinetic parameters estimated from pilot plant experiments.     

A Kinetic Model for Hydrocracking Process

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悬浮床加氢裂化集总动力学模型的研究

在不同反应温度、氢初压条件下,通过高压反应釜对克拉玛依常压渣油（KLAR）进行加氢裂化实验,以此模拟悬浮床加氢裂化过程,并根据实验数据及实际工艺中对各种轻油产品收率预测的需求建立了悬浮床加氢裂化六集总（气体、汽油、柴油、蜡油、减压渣油、焦）动力学模型,用matlab软件进行编程,采用最小二乘法对动力学参数进行估算,并进行误差分析。结果表明,建立的六集总动力学模型能很好的对各集总产品收率进行预测,计算结果与实验值基本吻合,大部分误差在5%以内。     

加氢裂化集总反应动力学模型研究

根据加氢裂化反应机理和反应特征，建立了通用性较强的加氢裂化集总动力学模型；采用序列二次规划方法进行参数估计，确定了反应动力学参数。研究结果表明，模型能很好地拟合实验数据，并具有良好的预测性能。     

减压蜡油加氢裂化催化剂组合动力学模型

以高压加氢裂化六集总动力学模型为基础,建立预测催化剂组合体系产品分布的数学模型。按固定馏程间隔将原料油和加氢裂化生成油划分为减压蜡油 加氢裂化尾油（>360℃）、柴油馏分（290～360℃）、喷气燃料馏分（175～290℃）、重石脑油馏分（65～175℃）、轻石脑油馏分（<65℃）和炼厂气（C4-）6个集总。分别以2种不同类型加氢裂化催化剂的实验数据为基础,采用Matlab 2011b数值计算软件和非线性最小二乘法对动力学模型参数进行了优化回归。以优化回归后的动力学模型参数为初值,调整部分模型参数,建立了预测催化剂组合体系产品分布的数学模型。用该模型计算得到的加氢裂化产品分布与实验值之间的一致性较好,其偏差均小于2%。     

Application of a Continuous Kinetic Model for the Hydrocracking of Vacuum Gas Oil

Hydrocracking is one of the most versatile petroleum refining processes for production of valuable products including gasoline, gas oil, and jet fuel. In this paper, a five-parameter continuous lumping model was used for kinetic modeling of hydrocracking of vacuum gas oil (VGO). The model parameters were estimated from industrial data obtained from a fixed bed reactor operating at an average temperature of 400°C and residence time of 0.3 h. Product distributions were obtained in terms of the weight fraction of various boiling point cuts. The model parameters were estimated using the Nelder-Mead optimization procedure and were correlated with temperature. Comparison of experimental and predicted product distributions indicated that the model was successful in predicting the products from hydrocracking reactions.     

中低温煤焦油加氢裂化集总动力学模型的研究

以煤焦油为原料,在高压固定滴流床反应器中,以工业NiMo/Al2O3为催化剂,考察了360-380℃范围内煤焦油的产物分布,基于此建立了5集总煤焦油加氢裂化动力学模型。动力学模型的集总包括：未反应的煤焦油、柴油、汽油、气体和焦炭。通过对实验产物与模型预测产物的对比数据,发现本文所建立的动力学模型可以用于煤焦油加氢裂化过程。同时,基于动力学模型,进一步分析了煤焦油的加氢裂化机理：在整个煤焦油加氢裂化过程中,柴油馏分可作为反应中间组分。     

减压蜡油加氢裂化六集总动力学模型研究

以加氢裂化催化剂A的加氢裂化实验结果为基础,建立了减压蜡油加氢裂化六集总动力学模型。六集总的划分原则以实际加氢裂化产品切割方案为参照,具体划分如下：按固定馏程间隔把石油馏分（原料油和生成油）划分为六个集总,即减压蜡油-加氢裂化尾油（>360 ℃）、柴油馏分（290~360 ℃）、航空煤油馏分（175~290 ℃）、重石脑油（65~175 ℃）、轻石脑油（<65 ℃）和炼厂气（C4－）。在Matlab 2011b数值计算软件上,利用非线性最小二乘法对动力学模型参数进行了优化回归。通过统计分析,忽略了部分集总间的反应。模型预测所得加氢裂化产物收率与实验结果的最大偏差为1.80%,满足工业应用要求。     

Mild Hydrocracking—A Review of the Process, Catalysts, Reactions, Kinetics, and Advantages

The demand for high quality middle distillates is increasing world wide while the demand for residue and fuel oil is decreasing. Hydrocracking is the major conversion process that meets the twin objectives of producing more middle distillates of very high quality. Since hydrocracking is a capital-intensive process, many refiners consider the option of converting their existing vacuum gas oil hydrotreating units into mild hydrocracking units. The use of mild hydrocracker bottom as FCC feedstock can improve the quality of FCC products. In view of the advantages of mild hydrocracking process, it is essential to understand the process, catalysts used, reactions, kinetics, and advantages. This article reviews recent literature on MHC process, various catalysts used, reactions involved and advantages of mild hydrocracking process in terms of improved product qualities and increased distillates. The kinetics of the mild hydrocracking process and kinetic challenges with respect to aromatic saturation have been summarized. The limitations of the process and future scope of work in this area are also discussed briefly.     

Maximizing Diesel Production From Vacuum Gas Oil Using a Two Stage Hydrocracker

In this study, a six-lump model was sufficient to describe the kinetics of vacuum gas oil (VGO) hydrocracking in order to maximize the production of middle distillate diesel. The kinetic lump model target was to obtain the reaction rate constants that represent all the hydrocracking reactions in the process. The operating conditions such as temperature, pressure, and hydrogen severity were tested to find the optimum parameters that maximize diesel yields. Mild hydrocracking operating conditions of temperature and pressure were used in a commercial hydrocracker with hydrogen severity similar to hydrotreating processes. The main reaction was the VGO conversion to diesel based on its high reaction rate constant compared with other reactions. In addition, the main reaction had the highest effect on catalyst deactivation based on the resulted deactivation factor. A multi-linear regression correlation was obtained for maximizing diesel production as a function of operating pressure, temperature, and hydrogen amount, keeping the diesel specifications within the market demand.     

Mild Hydrocracking—A Review of the Process,Catalysts, Reactions,Kinetics, and Advantages

Abstract

The demand for high quality middle distillates is increasing world wide while the demand for residue and fuel oil is decreasing. Hydrocracking is the major conversion process that meets the twin objectives of producing more middle distillates of very high quality. Since hydrocracking is a capital-intensive process, many refiners consider the option of converting their existing vacuum gas oil hydrotreating units into mild hydrocracking units. The use of mild hydrocracker bottom as FCC feedstock can improve the quality of FCC products. In view of the advantages of mild hydrocracking process, it is essential to understand the process, catalysts used, reactions, kinetics, and advantages. This article reviews recent literature on MHC process, various catalysts used, reactions involved and advantages of mild hydrocracking process in terms of improved product qualities and increased distillates. The kinetics of the mild hydrocracking process and kinetic challenges with respect to aromatic saturation have been summarized. The limitations of the process and future scope of work in this area are also discussed briefly.     

Hydrocracking of Vacuum Gas Oil: Conversion,Product Yields,and Product Quality over an Industrial Hydrocracking Catalyst System

Pilot plant experiments were conducted over an industrial hydrotreating/hydrocracking catalyst system using vacuum gas oil fraction obtained from a refinery crude distillation unit. Extensive pilot plant data were generated on the performance of industrial hydrocracking catalyst system with respect to conversion, product yields, and product quality at various operating conditions. The pilot plant experiments were carried out in a dual-reactor hydrotreating pilot plant system with downflow mode of operation. The temperature varied from 360 to 400°C and liquid hourly space velocity varied from 0.8 to 2.4 hr^?1, keeping a constant pressure of 170 kg/cm² and H₂/HC feed ratio of 845 L/L. The hydrocracked total liquid product was distilled in a true boiling point distillation unit to obtain yields and qualities of different fractions such as naphtha, kerosene, diesel, and unconverted oil. The effect of operating conditions on the performance of the hydrocracking catalyst system was discussed in detail. The kinetics of hydrocracking reaction was studied using a simple first-order reaction and a complex four-lump reaction system and the kinetic parameters were reported.     

基于半监督学习-多通道卷积神经网络的加氢裂化产品性质预测

提出了一种用于加氢裂化产品性质预测的半监督学习-多通道卷积神经网络(SSL-MCCNN),通过逐层卷积实现加氢裂化工艺流程空间域局部特征提取,并基于多通道采样实现了时域特征提取。在应对模型训练中由于产品性质数据量不足导致的小样本学习问题方面,基于教师-学生半监督学习(TS-SSL)生成虚拟样本集实现了数据扩充,进一步提升了模型预测性能。基于SSL-MCCNN对煤油-柴油加氢裂化工业装置重石脑油密度和柴油闪点预测的均方根误差(RMSE)分别为0.83和1.03,判定系数(R²)分别为0.90和0.98,与BP神经网络(BPNN)和径向基神经网络(RBFNN)相比,SSL-MCCNN在实现最小RMSE的同时达到了最优R²。实验结果表明,所提出的SSL-MCCNN有效提取了加氢裂化工艺流程的时空域特征,显著提升了模型预测性能。     

Study of nonisothermal gas-oil catalytic cracking applying the microactivity test

Catalytic cracking of gas oils has been studied in a standard microactivity test (MAT) reactor. The cracking product distribution was measured as a function of temperature. Based on these experimental results, a four-lump kinetic model was developed. Kinetic constants were estimated using the sequential step-optimization method. A nonisothermal nonsteady-state model for a fixed-bed MAT reactor was proposed. The overall heat of the reactions were taken from the macroscopic differences in the enthalpies of the products and reactants. The influence of the feedstocks used and reactor temperature were discussed. The reactor and kinetic model were validated with results from MAT test data. The simulation results are in good agreement with the experimental data.     

Performance Evaluation Studies of First- and Second-Stage Hydrocracking Catalysts Using Kuwait Vacuum Gas Oil Feedstocks

In a two-stage hydrocracking process, two types of catalyst are used to remove undesirable contaminants (such as S, N, hydrogenation of aromatic compounds, etc.) and convert the heavy feedstock to lighter products. In the present work, individual set of experiments were conducted to obtain information regarding activity and selectivity with emphasis on the evaluation of kinetic parameters of first- and second-stage commercial catalysts used in hydrocracking process. The performance tests were conducted in a down-flow fixed-bed hydrocracking pilot plant using a single reactor. The hydrotreating type A catalyst and hydrocracking type B catalyst were used individually with typical Kuwaiti refinery feedstocks, namely, hydrotreated vacuum gas oil (HVGO) and unconverted residual oil (UCRO), respectively. The order of reaction in this study shows first-order kinetics for HDS and HDN over CAT-A, and first-order hydrocracking conversion over CAT-B. For CAT-A the activation energies were found for HDS and HDN reactions at 22 and 27.3 kcal/gmole, while for CAT-B activation energies were 27.4 kcal/gmole.     

Method of calculation of product yields in hydrocracking middle distillates

The hydrocracking of straight-run and secondary middle distillates (180–360°C) is aimed at obtaining naphthas (gasolines) and jet fuels. A procedure described in [1] can be used to characterize the complex reactions involved in hydrocracking the aromatic and naphthenic hydrocarbons in these distillates to form paraffins, as well as reactions of isomerization and hydrocracking of paraffins. In the absence of any data on the group composition of the feed, but with a known distillation range, the product yields in hydrocracking middle distillates (D) can be calculated.Translated fromKhimiya i Tekhnologiya Topliv i Masel, No. 2, pp. 28–31, March–April, 1996.     

Kinetic Study on the Hydrocracking Reaction of Vacuum Residue Using a Lumping Model

Based on the experimental hydrocracking of vacuum residue, a kinetic study using a lumping model was carried out to gain insight into the characteristics of catalytic reactions. The lumped species were the saturates, aromatics, resins, and asphaltenes (SARA) constituents in the residue (798 K⁺) fraction and gas, naphtha, kerosene, gas oil, vacuum gas oil, and coke in the products. The pyrite reaction favoring hydrocracking to lighter products was more temperature-dependent than that using a mixture of pyrite and active carbon. The kinetic study showed that the addition of active carbon to pyrite limited the transformation of resins to asphaltenes.     

FCC汽油催化转化动力学模型

以催化裂化反应机理为基础，将FCC汽油原料及产品按馏程和化学组成进行集总划分。考虑裂化、氢转移、芳构化和缩合等反应，对反应网络进行合理简化，提出了一种接近分子水平的动力学模型。通过参数估算求取14个动力学速率常数、反应活化能和指前因子，建立了汽油催化转化反应的十集总动力学模型。研究结果表明，采用该模型能预测不同反应条件下汽油转化反应产率分布和产品中汽油的烃类组成。     

加氢裂化集总动力学模型的研究Ⅱ．正十烷加氢裂化集总模型

选用３８２４加氢裂化催化剂，对正十烷加氢裂化动力学进行了研究。根据Ｗｅｅｋｍａｎ集总理论，建立了正十烷加氢裂化四集总动力学模型。用Ｍａｒｑｕａｒｄｔ法估计了各反应速率常数，确定了较完善的速率表达式和表现活化能，同时讨论了空速、温度、压力和反应活化能对产物分布的影响，为石油馏份加氢裂化集总动力学研究提供了基础数据。     

沥青质加氢热裂解和催化加氢裂解反应动力学与选择性

A pentane-insoluble mixture of asphaltenes was processed by thermal hydrocracking and catalytic hydrocracking over Ni-Mo/γ-Al2O3 catalyst in a microbatch reactor at 430 ℃.The experimental data of asphaltene conversion adequately fit second-order kinetics to give the apparent rate constants of 2.435×10-2 and 9.360×10-2 (wt frac)-1 min-1 for the two processes,respectively.A three-lump kinetic model is proposed to evaluate the rate constants for parallel reactions of asphaltenes producing liquid oil (k1) and gas+coke (k3),and consecutive reaction producing gas+coke (k2) from this liquid oil.The evaluated constants for asphaltenes hydrocracking,in the presence and absence of the catalyst,respectively,show that k1 is 2.430×10-2 and 9.355×10-2 (wt frac)-1 min-1,k2 is 2.426×10-2 and 6.347×10-3 min-1,and k3 is 5.416×10-5 and 4.803×10-5 (wt frac)-1 min-1.As compared with the thermal hydrocracking of asphaltenes,the catalytic hydrocracking of asphaltenes promotes liquid production and inhibits coke formation effectively.