流态化技术在甲醇制低碳烯烃装置中的应用

本文总结了甲醇制低碳烯烃(MTO)的发展历程,根据MTO反应机理及反应特点,评述了各类MTO工业反应型式的适用性,认为流态化反应器和再生器之间的循环适合于MTO反应热效大、催化剂寿命短的特点。中国神华煤制油化工有限公司包头煤化工分公司1.80×106 t/d的MTO工业示范装置近3年的运行数据表明流化床技术非常适合于MTO反应。     

Effects of high temperature and combustion on fluidized material attrition in a fluidized bed

This study investigated the effects of high temperature and combustion conditions on the attrition of fluidized material in a fluidized bed. Silica sand was fluidized in air at an atmospheric pressure between 873 K and 1,073 K. The operating parameters evaluated in investigating the attrition rate of fluidized material included particle size, temperature and both combustion and non-combustion conditions. Experimental results indicated that the total weight of attrition increased with increasing temperature and decreased with increasing particle size. The attrition was higher during the initial fluidization period than the later period, due to the loss of sharp corners and edges of the attrition particles. The initial and final attrition rates during combustion were higher than those in the non-combustion condition, because the heat and thermal shock were produced to increase attrition rate during incineration. Comparing the experimental data with previous correlations, that reveals a significant level of error in the prediction results from existing correlations. This error may occur because the experimental equations neglected the operating temperature and particle size.     

Continuous preparation of activated carbon supported zinc acetate catalyst and industrial synthesis of vinyl acetate from acetylene

A continuous manufacturing method of an activated carbon supported zinc acetate catalyst has been established. Based on the dipping of a crushed activated palm carbon into a zinc acetate aqueous solution, the catalyst is prepared for the synthesis of vinyl acetate from acetylene in an industrial fluidized reaction vessel. The relationship between the supported amount of zinc acetate and various factors has been studied. Based on these results, an empirical formula was developed. Using this formula, the continuous manufacturing apparatus was designed and constructed for the purpose of preparing the optimum supported fluidized catalyst. To minimize the activated carbon loss due to crushing and wearing, a vibrating conveyor system was employed. This continuous manufacturing process produced a uniform catalyst with an activated carbon feed rate of 0.25 m³ h^?1. Using this catalyst, a series of operational tests of the vinyl acetate synthesis was performed for investigating the optimum reaction conditions. These operational tests were carried out using an industrial fluidized reaction vessel of 3.28 m diameter and 50 tons day^?1 vinyl acetate production capacity. Based on these test results, the reaction rate constant and the deterioration rate constant were newly introduced, and the optimum operation conditions were then determined.     

High-temperature attrition of sorbents and a catalyst for sorption-enhanced steam methane reforming in a fluidized bed environment

Mechanical degradation of the solid particles used in sorption-enhanced steam methane reforming (SE-SMR) was investigated in a gas jet attrition apparatus. The performance of a dolomite, a limestone and a commercial reforming catalyst were compared based on the air jet attrition index (AJI). The dolomite showed the poorest resistance to attrition, likely due to the extra pore volume caused by calcination of MgCO₃. The degree of loss of fines from the catalyst was significant, pointing to the need to develop catalysts suited to fluidized bed operation. Co-fluidization of the harder catalyst and the dolomite did not lead to additional attrition of the dolomite.     

Attrition behavior of fine particles in a fluidized bed with bimodal particles: Influence of particle density and size ratio

To process the solid particulates in fluidized bed and slurry phase reactors, attrition is an inevitable consequence and is therefore one of the preliminary parameters for the catalyst design. In this paper, the mechanical degradation propensity of the zeolite catalysts (particles) was investigated in a bimodal distribution environment using a Gas Jet Attrition — ASTM standard fluidized bed test (D-5757). The experimentation was conducted in order to explore parameters affecting attrition phenomena in a bimodal fluidization. In a bimodal fluidization system, two different types of particles are co-fluidized isothermally. The air jet attrition index (AJI) showed distinct increases in the attrition rate of small particles in a bimodal fluidization environment under standard operating conditions, in comparison with single particle. A series of experiments were conducted using particles of various sizes, with large particles of different densities and sizes. Experimental results suggest that the relative density and particle size ratio have a significant influence on attrition behavior during co-fluidization. Therefore a generalized relationship has been drawn using Gwyn constants; those defined material properties of small particles. Moreover, distinct attrition incremental phenomenon was observed during co-fluidization owing to the change in collision pattern and impact, which was associated with relative particle density and size ratios.     

高温环境下催化裂化催化剂磨损状况的研究

为研究流化催化裂化(FCC)催化剂在高温环境下的磨损行为,在一套固定流化床装置中考察了FCC平衡剂CGP-I在500℃和600℃高温环境下磨损率的时变关系和过孔气速对磨损率的影响,分别从颗粒形貌、磨损动力学等方面对催化剂的磨损机制进行了研究。结果表明:随着磨损时间的延长,磨损速率逐渐下降;随着磨损温度和孔气速的增加,磨损率增大。通过分析结果并与Gwyn磨损动力学方程比较建立了宏观磨损平衡方程,整个磨损过程可近似看作一级不可逆过程,该催化剂磨损率随磨损时间和孔气速的升高呈指数关系增加,高温环境下催化剂的磨损行为主要受表层磨损机制支配。     

甲醇制烯烃催化剂SAPO-34分子筛的制备和喷雾成型

SAPO-34分子筛用于催化甲醇转化制烯烃,乙烯和丙烯选择性高,是很好的甲醇制烯烃催化剂。由于SAPO-34分子筛失活速率快,甲醇制烯烃反应器通常是连续循环再生的流化床反应器,SAPO-34分子筛必须喷雾成型并达到一定抗磨强度后才能使用。在50 L反应釜合成了SAPO-34分子筛,并在中试喷雾装置上,以SAPO-34为活性组分喷雾成型甲醇制烯烃催化剂。结果表明,喷雾成型甲醇制烯烃催化剂的抗磨损指数为1.58%·h-1,抗磨性能达到工业应用要求,与两种工业甲醇制烯烃催化剂对比,喷雾成型甲醇制烯烃催化剂寿命最长,达260 min,乙烯、丙烯选择性以及乙烯+丙烯总选择性在对应的各个反应时间点均最高,260 min分别达到49.09%、35.05%和84.98%。     

Kinetic model for hydroisomerization reaction of C-aromatics

Based on the reported reaction networks, a novel six-component hydroisomerization reaction network with a new lumped species including C₈-naphthenes and C₈-paraffins is proposed and a kinetic model for a commercial unit is also developed. An empirical catalyst deactivation function is incorporated into the model accounting for the loss in activity because of coke formation on the catalyst surface during the long-term operation. The Runge-Kutta method is used to solve the ordinary differential equations of the model. The reaction kinetic parameters are benchmarked with several sets of balanced plant data and estimated by the differential variable metric optimization method (BFGS). The kinetic model is validated by an industrial unit with sets of plant data under different operating conditions and simulation results show a good agreement between the model predictions and the plant observations.     

甲苯歧化与C9芳烃烷基转移反应动力学模型和模拟分析

A new kinetic model for commercial unit of toluene disproportionation and C9-armatiocs transalkylation is developed based on the reported reaction scheme.A time based catalyst deactivation function taking weight hourly space velocity（WHSV）into account is incorporated into the model,which reasonably accounts for the loss in activity because of coke deposition on the surface of catalyst during long-term operation.The kinetic parameters are benchmarked with several sets of balanced plant data and estimated by the differential variable metric optimiza- tion method.Sets of plant data at different operating conditions are applied to make sure validation of the model and the results show a good agreement between the model predictions and plant observations.The simulation analysis of key variables such as temperature and WHSV affecting process performance is discussed in detail,giving the guidance to select suitable operating conditions.     

CATALYST FRACTURE DUE TO THERMAL SHOCK IN FLUIDIZED CATALYTIC CRACKER UNITS

The formation of fines in a fluidized catalytic cracker unit (FCCU) due to catalyst attrition and fracture is a major source of catalyst loss. In addition to standard attrition tests described in the literature, the possibility that thermal conditions could lead to catalyst fracture and fines production has been explored. Samples of fresh and used (equilibrium or e-cat) type catalysts were heated up to 600°C and mixed with cold samples to determine the impact of thermal shock on particle stability. It was found that significant fracture occurs under these conditions, leading to loss of larger catalyst particles in the bed and significant gain in the amount of fine particles. Agglomeration of particles was also evident, in some cases leading to an increase in the quantity of larger particles appearing to be present in the catalyst sample.     

前置烧焦式催化裂化装置稳态模拟:再生器取热器负荷对过程的影响

应用本文作者课题组开发的前置烧焦式催化裂化装置过程模拟平台,对某工业装置进行现场条件下的稳态模拟,并完成全装置模型的校正及验证。在此基础上,模拟分析了再生器取热器负荷对该装置操作产生的影响。模拟结果显示,改变再生器取热器的负荷,能够有效调节两器热量平衡,在确保工艺范围不超限的前提下提高装置剂油比,原料油转化率提高,装置产品分布得到有效调节,但是使得密相床再生器密相区床层温度降低,从而影响再生器的再生效果,不利于提升管进口再生催化剂初始活性的提高。     

Estimation of Kinetic Parameters for Hydrogenation Reactions Using a Genetic Algorithm

The kinetics of acetylene hydrogenation in a fixed‐bed reactor of a commercial Pd/Al₂O₃ catalyst has been studied. The hydrogenation reactor considered in this work is an essential part of a vinyl chloride monomer (VCM) plant. Three well‐known kinetic models were used to simulate the hydrogenation reactor under industrial operating conditions. Since none of the models provide appropriate prediction, the industrial data and calculated values were compared and optimum kinetic parameters were evaluated utilizing a genetic algorithm (GA) technique. The best kinetic parameters for the three models were determined under specified industrial operating conditions. The hydrogenation reactor was simulated using the estimated optimum kinetic parameters of the three models. Simulation results from the three models were compared to industrial data and the best kinetic model was found. This kinetic model with the evaluated optimum kinetic parameters can well predict the behavior of the industrial hydrogenation reactor to improve the performance of the process.     

Influence of hydrodynamic parameters on particle attrition during fluidization at high temperature

In a fluidized bed, attrition both increases the number of particles and reduces particle size, which may affect reactor performance, fluidizing properties, operating stability and operating costs. Most fluidized applications are conducted at high temperature, but in the past most attrition correlations were performed at room temperature, so the attrition rate at high temperature could not be predicted. In contrast, this study investigates the attrition rate of fluidized materials at high temperature. Silica sand was used as the bed material; the operating parameters included temperature, particle size, static bed height and gas velocity to assess the attrition rate. Then an appropriate correlation was developed by regression analysis to predict attrition rate at high temperature. Experimental results indicated that the attrition rate increases with increasing temperature. In addition, the particle attrition increased as average particle size decreased because the probability of collision increases with surface area. The attrition rate increased with increasing gas velocity because of increased kinetic stress of particle movement. The actual density and viscosity of air at specific fluidization temperature were modified and an Ar number was introduced to fit our experimental data. The experimental correction agrees with the experimental results, which can predict particle attrition rate at high temperatures.     

煤基高流动性LLDPE DNDA-8320的工业化生产

总结了煤基气相流化床聚乙烯装置从线型低密度聚乙烯(LLDPE)DFDA-7042转产LLDPE DNDA-8320的工业化过程,重点在于反应器和挤压造粒机的工况变化,出现的故障和生产难点,并对DNDA-8320的性能和应用进行了评价.结果表明:转产实施时,反应器流化松密度和床重下降,催化剂活性从21740 g/g降至1...     

流化床喷雾造粒制备MTO薄层催化剂实验研究简

根据甲醇制烯烃流化床反应一再生工艺对催化剂反应性能、球形度、耐磨强度等的要求,利用流化床喷雾造粒法制备了MTO薄层催化剂。实验研究了进料流率、分子筛组合物与粘结剂质量比、分子筛组合物浓度对薄层生长速率的影响并比较了分别以分子筛和成型催化剂为原料造粒时的薄层生长速率。实验结果表明,当分子筛组合物浓度高、进料流率大时,催化剂涂层生长速率快,表面活性成分负载量大。     

环氧乙烷合成银催化剂宏观动力学及失活分析

在工业生产的条件下用无梯度反应器研究了工业颗粒银催化剂上乙烯氧化合成环氧乙烷宏观动力学 ,得到了能反映该系统主副反应特性的双速率方程 .建立了二维非均相反应器模型 ,模拟并比较了工业生产操作数据 ,获得了该种催化剂的活性校正因子随使用时间变化的经验关联式和主副反应失活速率方程     

Selective Hydrogenation of 1‐Butene Rich Cuts: the Impact of the Intraparticle Diffusion Limitations on the Selectivity

The impact of intraparticle diffusion limitations on the selectivity of an industrial reactor for selective hydrogenation of 1‐butyne and 1,3‐butadiene contained in 1‐butene rich cuts was evaluated. To this end, a simple model of a trickle‐bed reactor was employed and actual process operating conditions were chosen. A kinetic model was chosen whose parameters correspond to a commercial catalyst. These parameters were calculated from experiments conducted under industrial operating conditions. The complex diffusion and reaction phenomena occurring inside catalyst pellets placed at different depths of the reactor are comprehensively described. 1‐Butene losses in the range 20–30 %, which are usual in commercial plants, were predicted. It was concluded that the operating pressure is crucial for enhancing process selectivity.     

Simulation of the ammonia oxidation process over an oxide monolith catalyst

A mathematical model of ammonia oxidation over an oxide monolith honeycomb catalyst has been developed. Experimental data from a pilot unit operating under process conditions equal to those in a type UKL-7 commercial nitric acid plant were used to refine the parameters of the mathematical model. The results from calculating the NO yield are in satisfactory agreement with the pilot unit data. There is now computer program that allows us to calculate the conditions of an industrial reactor functioning.     

Optimal hybrid modeling approach for polymerization reactors using parameter estimation techniques

The dynamics of polymerization catalytic reactors have been investigated by many researchers during the past five decades; however, the emphasis of these studies was directed towards correlating process model parameters using empirical investigation based on small scale experimental setup and not on real process conditions. The resulting correlations are of limited practical use for industrial scale operations. A statistical study for the relative correlation of each of the effective process parameters revealed the best combination of parameters that could be used for optimizing the process model performance. Parameter estimation techniques are then utilized to find the values of these parameters that minimize a predefined objective function. Published real industrial scale data for the process was used as a basis for validating the process model. To generalize the model, an artificial neural network approach is used to capture the functional relationship of the selected parameters with the process operating conditions. The developed ANN-based correlation was used in a conventional fluidized catalytic bed reactor (FCR) model and simulated under industrial operating conditions. The new hybrid model predictions of the melt-flow index and the emulsion temperature were compared to industrial measurements as well as published models. The predictive quality of the hybrid model was superior to other models. The suggested parameter estimation and modeling approach can be used for process analysis and possible control system design and optimization investigations.