The application of theoretical solutions to the differential mass balance equation for modeling of adsorptive desulfurization in a packed bed adsorber

Adsorptive removal of organosulfur compounds, lumped as total sulfur content, from a real diesel fuel was carried out in a packed bed adsorber. A novel approach was taken in the application of theoretical solutions to the differential mass balance equation using modern software tools, and one classic method as point of reference. Adsorptive desulfurization is a perspective downstream process to hydrodesulfurization for achieving sulfur concentration levels of less then 10 mg kg⁻¹. Compared to the conventional hydrodesulfurization process, the deep desulfurization can be accomplished without changing the physical properties of the product and at relatively low temperature and pressure. The adsorber apparatus comprised computer control, enabling completely automated operation. Adsorbent was activated carbon SOLCARB C from Chemviron Carbon, Belgium. The experimental results regarding the influence of flow rate and bed depth on the outlet sulfur concentration were evaluated as well as the models ability to describe the adsorption kinetics and to estimate the breakthrough curves. Ultra deep desulfurization of diesel fuel was achieved and it was determined that outlet sulfur concentration was being lowered by decreasing flow rate and increasing bed depth. The closest fit to the experimental data was achieved for the Bohart-Adams model.     

Intensification of Deep Hydrodesulfurization Through a Two-stage Combination of Monolith and Trickle Bed Reactors

Deep hydrodesulfurization (HDS) is an important process to produce high quality liquid fuels with ultra-low sul-fur. Process intensification for deep HDS could be implemented by developing new active c...     

Isobutane production with a catalytic reformer pretreater

For some refineries, production of isobutane is economically viable; for others, isobutane self-sufficiency is strategically important. However, a process unit specifically for isobutane production often is not justified. A process has been developed to use an existing unit to produce isobutane on demand. In this process, the reformer pretreater is filled with a special catalyst with a high selectivity for desulfurization over hydrocracking. It can pretreat the reformer feed to low sulfur levels at low temperatures without significant hydrocracking; this selectivity can be further enhanced by temporary poisoning with nitrogen compounds. The catalyst is also active for hydrocracking so that, when isobutane is in demand, a moderate increase in reactor temperature allows the production of butanes at a high iso-to-normal ratio while maintaining desulfurization. Preliminary tests indicate that catalyst stability appears excellent.     

Hydrocracking: An improved Kinetic Model and Reactor Modeling

Stangeland's kinetic model for predicting hydrocracker yields was modified to explicitly account for the mass balance closure in each individual hydrocracking reaction and for the effect of hydrogen partial pressure on the hydrocracking reaction rate. This improved kinetic model has two additional parameters. The model was applied to the modeling of a fixed bed reactor for mild hydrocracking of vacuum gas oils in the framework of the Aspen Plus® process simulator. The kinetic parameters were regressed using the algorithm of Levenberg-Marquardt such that the mass balance in each individual hydrocracking reaction is satisfied. The reactor model assumed gas-liquid equilibrium and was used to quantify the effect upon conversion of the operating variables--liquid hourly spatial velocity, reactor pressure, and hydrogen-to-feed ratio--showing that both the kinetic and reactor models predict the appropriate trends compared to the reference data. The practical implications of explicitly introducing the mass balance closure for each hydrocracking reaction in the kinetic model are discussed.     

Hydrocracking: An improved Kinetic Model and Reactor Modeling

Stangeland's kinetic model for predicting hydrocracker yields was modified to explicitly account for the mass balance closure in each individual hydrocracking reaction and for the effect of hydrogen partial pressure on the hydrocracking reaction rate. This improved kinetic model has two additional parameters. The model was applied to the modeling of a fixed bed reactor for mild hydrocracking of vacuum gas oils in the framework of the Aspen Plus® process simulator. The kinetic parameters were regressed using the algorithm of Levenberg-Marquardt such that the mass balance in each individual hydrocracking reaction is satisfied. The reactor model assumed gas-liquid equilibrium and was used to quantify the effect upon conversion of the operating variables--liquid hourly spatial velocity, reactor pressure, and hydrogen-to-feed ratio--showing that both the kinetic and reactor models predict the appropriate trends compared to the reference data. The practical implications of explicitly introducing the mass balance closure for each hydrocracking reaction in the kinetic model are discussed.     

Kinetic parameter estimation and simulation of trickle-bed reactor for hydrodesulfurization of crude oil

Hydrodesulfurization (HDS) of crude oil has not been reported widely in the literature and it is one of the most challenging tasks in the petroleum refining industry. In order to obtain useful models for HDS 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. In this work, an optimization technique is used in order to obtain the best values of kinetic parameters in trickle-bed reactor (TBR) process used for hydrodesulfurization (HDS) of crude oil based on pilot plant experiment. The optimization technique is based on minimization of the sum of the square errors (SSE) between the experimental and predicted concentrations of sulfur compound in the products using two approaches (linear (LN) and non-linear (NLN) regressions).A set of experiments were carried out in a continuous flow isothermal trickle-bed reactor using crude oil as a feedstock and the commercial cobalt–molybdenum on alumina (Co–Mo/γ-Al₂O₃) as a catalyst. The reactor temperature was varied from 335 to 400 °C, the hydrogen pressure from 4 to 10 MPa and the liquid hourly space velocity (LHSV) from 0.5 to 1.5 h⁻¹, keeping constant hydrogen to oil ratio (H₂/oil) at 250 L/L.A steady-state heterogeneous model is developed based on two-film theory, which includes mass transfer phenomena in addition to many correlations for estimating physiochemical properties of the compounds. The hydrodesulfurization reaction is described by Langmuir–Hinshelwood kinetics. gPROMS software is employed for modelling, parameter estimation and simulation of hydrodesulfurization of crude oil in this work. The model simulations results were found to agree well with the experiments carried out in a wide range of the studied operating conditions. Following the parameter estimation, the model is used to predict the concentration profiles of hydrogen, hydrogen sulfide and sulfur along the catalyst bed length in gas, liquid and solid phase, which provides further insight of the process.     

Hydrodesulfurization of diesel in a slurry reactor

The need for more complete removal of sulfur from fuels is due to the lower allowable sulfur content in gasoline and diesel, which is made difficult by the increased sulfur contents of crude oils. This work reports an experimental study on the hydrodesulfurization (HDS) of diesel in a slurry reactor. HDS of straight-run diesel using a NiMoS/Al₂O₃ catalyst was studied in a high-pressure autoclave for the following operating conditions: 4.8–23.1 wt% catalyst in the reactor, 320–360 °C, 3–5 MPa pressure, and 0.56–2.77 L/min hydrogen flow rate. It was found that the reaction rate was proportional to the catalyst amount and increased with temperature, pressure and hydrogen flow rate. The reaction kinetics for the HDS reaction in the slurry reactor was obtained. As compared with HDS in a fixed bed reactor, HDS in a slurry reactor is promising because of the uniform temperature profile, high catalyst efficiency, and online removal and addition of catalyst.     

新型含USL分子筛柴油加氢精制催化剂的研究

制备了NiW/Al₂O₃-USL系列催化剂,采用XRD、NH₃-TPD、UV-vis DRS(紫外-可见漫反射光谱)以及BET比表面积分析等多种技术对催化剂的基本物性进行表征,并以柴油为原料,在高压加氢微反装置中进行催化剂的加氢脱硫(HDS)活性评价。结果表明,在相同反应条件下具有适宜USL添加量的NiW/Al₂O₃-USL^-1催化剂的加氢脱硫效果优于参比的商业加氢催化剂,并且所得柴油产品硫含量<10 μg·g^-1,满足世界燃油规范IV类的标准。     

Oxidative Desulfurization of Hydrocarbon Fuels

New requirements for very low sulfur content (10 ppm) in liquid motor fuels demand novel approaches for ultra-deep desulfurization. For production of near-zero-sulfur diesel and low-sulfur fuel oil, removal of refractory sulfur compounds, like 4,6-dimethyldibenzothiophene and other alkyl-substituted thiophene derivatives, is necessary. Elimination of these compounds by hydrodesulfurization (HDS) requires high hydrogen consumption, high pressure equipment, and new catalysts. Various oxidative desulfurization processes, including recent advances in this field for diesel fuels, and the drawbacks of this technology in comparison with HDS are examined and discussed. It is shown that the oxidation of sulfur compounds to sulfones with hydrogen peroxide allows for production of diesel fuels with a sulfur content of 10 ppmw or lower at atmospheric pressure and room temperature. The gas phase oxidative desulfurization of sulfur compounds with air or oxygen is feasible at atmospheric pressure and higher temperatures: 90–300 °С and offers better economic solutions and incentives.     

Set-point optimization of an adiabatic trickle-bed reactor system

A combined system parameter estimation and deactivation model identification procedure is proposed to create a grey model of an adiabatic residue hydrodesulfurization (RDS) trickle-bed reactor. Using the resulting grey model, a precomputed set-point table is used to optimize the set-point of the RDS reactor unit. The objective function chosen is the predetermined reactor outlet sulfur content and the optimal set-point is the reactor inlet temperature. Five crucial case studies using a dynamic simulator of an adiabatic RDS trickle-bed reactor demonstrate the applicability of the proposed algorithm in developing optimal set-points for a commercial process.     

部分转化加氢裂化生产清洁柴油

由于人们环境保护意识的提高，世界各国对机动车燃料的标准越来越高，生产高十六烷值，低硫含量的高质量清洁柴油迫在眉睫。对催化原料进行部分转化加氢裂化处理，可以降低柴油产品的硫含量，提高十六烷值，满足目前对产品质量不断提高的要求。增加产品的收率，提高炼厂的经济效益。介绍了几种新的部分转化加氢裂化工艺以及其工业性能和其为炼厂所带来的益处。     

Diesel upgrading into a low emissions fuel

The revamp of existing diesel hydrotreating units using SHP technology was studied to improve the emission of the diesel engine. Gas and liquid-phase reactors were sequentially added to the actual trickle bed reactor. A special catalyst was employed. Micro-plant kinetic studies were performed and the results compared with those obtained with conventional trickle bed reactor operation. It was shown that using the gas and liquid-phase reactor, the hydrogenation, hydrogenolysis, and ring-opening reactions can be enhanced, so can be the sulfur and cetane number properties. The new scheme decreased the mono-aromatic content in the lighter part of the diesel that improve the NO_x and particulate emissions in exhaust gases of a diesel engine. A simplified kinetic model for gas and liquid-phase reactors was developed to optimize SHP reactors and to minimize investment.     

The effects of gas-to-oil rate in ultra low sulfur diesel hydrotreating

Hydrotreating has become a critical refining process as fuel sulfur specifications are tightened around the world. Recently, refiners in the United States have been learning how to optimize the performance of ultra low sulfur diesel (ulsd) hydrotreaters. The gas-to-oil feed rate ratio is known to be an important variable in this respect. It is well known that the gas-to-oil rate must be kept high enough to maintain the desired hydrogen partial pressure through the hydrotreating reactor, and to minimize the inhibiting effect of hydrogen sulfide. A lesser-known effect is the effect of gas-to-oil rate on the vapor–liquid equilibrium in the reactor. Changing the gas-to-oil rate alters the distribution of reactants between vapor and liquid in a way that changes the relative reaction rates of different sulfur compounds. This paper presents some pilot plant data and analysis showing this effect of phase equilibrium in deep diesel desulfurization. The effect can be modeled using the Frye–Mosby equation, which accounts for the effects of feed vaporization and phase equilibrium on the reaction rates of individual sulfur compounds in a trickle bed hydrotreater.     

加氢裂化反应动力学建模研究进展

加氢裂化是炼油与石化行业的关键技术,借助反应动力学建模以及软件模拟技术来深入认识加氢裂化反应机理并指导生产,优化装置操作条件,可以给企业带来显著的经济效益.本文主要对利用集总法来模拟加氢裂化反应过程动力学的相关研究进行了综述,包括基于生产方案划分的集总、离散集总以及连续集总建立的反应动力学模型[微软用户1],重点介绍了这三类集总模型的建模思路及发展现状,对不同模型的优缺点和反应网络进行了详细的对比分析,其中连续集总模型能够充分考虑混合物性质、反应途径以及切割方案变化的影响,进而实现对加氢裂化这一复杂体系反应器的模拟,准确预测其产品分布和产品性质.同时,本文还指出未来加氢裂化反应动力学建模深入研究的方向,将集总法建模和分子法建模有效结合,开发出一个全面的混合动力学模型,将是未来加氢裂化反应器模拟中一项很有意义并且具有挑战的工作.     

柴油加氢脱硫机理的研究进展

从常规加氢脱硫（HDS）到超深度HDS（S〈10μg/g）的转变面临着非常复杂的技术问题。一些硫化物（4,6-二甲基二苯并噻吩等）在常规脱硫条件下很难脱除。在超低硫柴油的生产过程中,这类硫化物也必须脱除。文章对柴油加氢脱硫机理进行了综述。     

加氢裂化装置的工艺优化改造设计

国内某炼厂0.8 Mt/a加氢裂化装置由于所产柴油产品产率偏低、密度偏低,导致全厂仅能生产调和硫含量低于350μg/g的国Ⅲ标准车用柴油产品。根据柴油国V质量升级的需要以及目前装置运行过程中存在的问题,对该装置进行技术改造,催化剂更换为抚顺石油化工研究院开发的FF-46加氢精制、FDW-3临氢降凝和FC-14B加氢改质催化剂组合,采用加氢改质(降凝)操作模式,由一段串联全循环工艺流程改为一段串联一次通过工艺流程,装置改造后可以生产硫含量低于10μg/g的国V标准车用柴油产品,柴油产品密度由800~805 kg/m3提高至812~810.4 kg/m3,柴油产品产率由50.46%提高至88.90%~97.20%。同时考虑到装置原料变差的可能性,通过切换操作,工艺流程可以由一段串联一次通过工艺流程恢复至一段串联全循环工艺流程,给原料加工和生产操作带来极大的适应性。     

Plant-wide optimization and control of an industrial diesel hydro-processing plant

Diesel hydro-processing (DHP) is an important refinery process which removes the undesired sulfur from the oil feedstock followed by hydro-cracking and fractionation to obtain diesel with desired properties. The DHP plant operates with varying feed-stocks. Also, changing market conditions have significant effects on the diesel product specifications. In the presence of such a dynamic environment, the DHP plant has to run in the most profitable and safe way and satisfy the product requirements. In this study, we propose a hierarchical, cascaded model predictive control structure to be used for real-time optimization of an industrial DHP plant.     

DYNAMICS OF A RESIDUE HYDRODESULFURIZATION TRICKLE BED REACTOR SYSTEM

An adiabatic residue hydrodesulfurization trickle bed reactor packed with a porous catalyst undergoing deactivation is simulated numerically in order to examine the dynamic behavior of this specific reaction system. One dimensional pseudo-homogeneous model incorporating the effects of mass and heat dispersion is used in the mathematical derivation. The parameters used in the simulation are primarily based on the experimental data of Shoji Kodama and other correlations. The method of orthogonal collocation is used to obtain the solution of coupled mass and energy balance equations. The catalyst deactivation model adopted was proposed by Shoji Kodama to include the interaction of demetallization and coking reaction on a catalyst. The performance of the reactor during start-up period and that for long time operation are examined. Meanwhile, step-wise changes of feed composition, feed rate, inlet temperature on the dynamic behavior of the reactor @KEYWORDS: Residue hydrodesulfurization, Dynamics, Trickle bed reactor, Simulation Orthogonal collocation.     

FCC原料加氢预处理生产超低硫汽油技术措施综述

阐述了超低硫汽油的生产对现有FCC原料加氢预处理技术的影响以及世界各国的技术策略,并指明了FCC原料加氢预处理技术在生产超低硫汽油中的发展方向和主要技术措施。研究表明:从生产30μg/g的清洁汽油到生产硫含量小于10μg/g的超低硫汽油会造成FCC原料加氢预处理装置氢耗高、运转周期短、加氢预处理-催化裂化联合装置经济性差等问题。FCC原料加氢预处理生产超低硫汽油的主要技术措施有:优化现有的FCC原料加氢预处理装置、对现有FCC原料加氢预处理装置增加一个反应器、增加现有FCC原料加氢预处理装置的进料量、开发FCC原料加氢预处理-FCC组合工艺、新建或改造成缓和加氢裂化装置、新建或改造成部分转化加氢裂化、新建或改造FCC汽油后处理装置。     

渣油加氢技术研究

应用上流式加氢技术处理渣油加氢脱硫,结果表明,相同工艺条件下,上流式加氢脱硫率比固定床提高约5.8%;其他工艺条件不变,空速提高0.5倍,加氢脱硫结果与固定床相当。提高反应温度,有利于提高催化剂的脱金属和脱硫活性,相同的反应温度,原料中的金属更容易脱除。