乙炔加氢反应系统操作优化策略

乙炔加氢反应系统是乙烯生产流程中的重要装置, 在催化剂反应动力学模型和失活模型已知的情况下, 研究两组串联反应器中除炔负荷的最佳分配。通过优化计算结果显示, 一段反应器入口氢炔比尽量控制在1.0以下, 二段反应器的氢炔比根据实际需要可以从1.9逐渐提高到3.5。考虑实际的操作费用和产品价格因素, 在负荷分配优化操作的前提下, 进一步研究了反应器切换再生对整体经济效益的影响。为使其整体效益最大, 一段反应器应该使用14个月后切换再生, 而二段反应器使用4个月后就需要切换再生。     

影响两段直列式碳二反应器运行周期的因素

国内部分乙烯装置碳二加氢单元采用直列式两段加氢工艺,在工业装置运行实践中发现,二段反应器的失活速率快于一段反应器,避免二段反应器催化剂的失活是延长直列式反应器运行时间的关键。研究了影响二段反应器失活速率的主要工艺因素,结果表明,一段反应器出口C4+含量直接影响直列式两段反应器运行时间;一段反应器出口温度超过120℃,发生乙烯聚合反应,C4+含量快速增加,这些聚合物分子链较长,进入二段反应器后,包覆在二段反应器中催化剂表面,导致催化剂快速失活。     

LY-C_2-02催化剂在两段床反应器的长周期运行

中国石油天然气股份有限公司辽阳石化分公司乙烯厂220 kt·a~(-1)乙烯装置碳二加氢采用两台直列式两段反应器。每段反应器的催化剂装填量6.6 m~3,一段反应器入口物料中乙炔体积分数达到1.85%~2.30%,远高于同类装置。由于乙炔含量高,一段反应器的温升为75℃,致使一段反应器出口温度达到125℃,催化剂结焦严重,催化剂运行周期短为7个月。2010年投入应用LY-C2-02催化剂,从2012年8月至2015年5月,催化剂已连续运行超过32个月,运行状态良好,乙烯平均选择性大于45%。     

碳二加氢反应器优化操作分析

抚顺乙烯碳二加氢反应器原再生周期为6～10个月,通过优化操作、精细管理,对该反应器的一些主要参数进行了调整,使其催化剂选择性一直保持在较高水平,本周期达到连续运行21个月,实现了碳二加氢反应器的长周期运行,为企业降低了成本和能耗.     

改进型LY-C_2-02催化剂模拟抚顺石化碳二加氢装置的侧线运行性能

针对抚顺石化碳二后加氢装置的特点,制备了改进型LY-C2-02催化剂,与G-58C催化剂进行对比,进行了12天的一、二段反应器串联运行的工业侧线运行试验,考察了改进型LY-C2-02催化剂的运行性能。结果表明,LY-C2-02催化剂在模拟抚顺碳二加氢装置工况情况下,在一段反应器除炔量为1.0%,高于G-58C催化剂0.04%;在二段反应器选择性为81.5%,高于G-58催化剂3.5%;综合运行性能达到G-58C催化剂水平。说明改进型LY-C2-02催化剂满足抚顺石化碳二加氢装置一、二段反应器的工艺要求,适宜应用于该装置一、二段反应器。     

新负载型碳三液相加氢催化剂的开发和工业应用

开发新负载型碳三馏分选择加氢催化剂,针对液相加氢工艺特点,在侧线装置上摸索和测试各种操控及运行参数,指导并首次成功应用于770kt/a乙烯装置。通过对催化剂的机械强度、催化性能以及操作窗口考察和研究,发现新型BC-L-83G催化剂的耐磨损、抗破碎以及长周期运行能力都大大优于上一代BC-L-83催化剂,并具有良好的温度适应性和氢炔比敏感度。工业应用的12个月试验结果表明,BC-L-83G具有催化活性高、选择性好、抗波动能力强、再生周期长等优势,非常适合进一步推广使用。     

甲醇制丙烯催化剂侧线装置性能评价

立足于甲醇制丙烯(MTP)工业装置,设计搭建了催化剂装填量为2 t的多段冷激式固定床侧线装置。侧线反应器从工业生产装置引入反应物料,受管线和反应器散热的影响,催化剂床层温度偏低,增加电加热器做热量补偿。催化剂产物分布与反应器入口物料配比密切相关,在侧线反应器内填装与工业装置相同批次的标准催化剂(MTPROP-1)对反应器进行了标定,结果表明,2个反应器内催化剂的丙烯、氢气、低碳烷烃选择性及单周期运行寿命相当。研制的催化剂在侧线装置进行了2 600 h的长周期性能评价,丙烯选择性变化趋势与标准催化剂一致,且数据相当。催化剂经过2次再生,再生性能良好。随着催化剂运行时间的延长,晶体结构没有发生变化,催化剂酸强度和酸量逐步下降,催化剂的介孔容及外表面积也呈下降趋势。     

乙烯装置碳二加氢反应器无扰动切换探讨

乙烯装置碳二加氢反应器运行正常与否直接影响乙烯产品质量。由于其具有运行一定时间必须进行切换再生的特性,故能否做到在线无扰动切换,对提高装置效益及减少排放至关重要。就镇海乙烯装置碳二加氢反应器切换为例,提出通过控制反应器入口加热器的暖管时间、配氢比等措施实现该反应器的无扰动切换。     

固定床半再生重整装置长周期运行分析

本文从离心式重整循环氢压缩机长期运行、氯腐蚀与氯结盐、重整催化剂活性3个方面分析了对固定床半再生重整装置长周期运行的影响：指出了固定床半再生重整装置长周期运行应努力的方向。     

KL7741B-T碳二加氢催化剂的工业应用及操作优化

使用KL7741B-T碳二加氢催化剂,以裂解气(裂解气中含过量氢气)为原料,在绝热床反应器中,通过分析反应器运行数据,系统测试KL7741B-T碳二加氢催化剂在中国石油大庆石化公司600 kt·a-1乙烯装置上的运行状况,测试结果为乙烯选择性大于80%,表明KL7741B-T碳二加氢催化剂具有良好的稳定性,能够满足装置长周期运行的需求。运行一段时间后,反应器各段温度有上升趋势,通过稳定CO浓度和降低各段入口温度等优化措施,使反应器的运行状态更优,装置运行更趋于稳定。     

Innovene工艺聚丙烯装置反应器结块原因分析与控制

对Innovene聚丙烯工艺进行分析,探讨了导致粉料结块的原因,并分别从催化剂类型、反应控制、催化剂分散性、催化剂喷嘴问题、共聚牌号生产和牌号切换等进行了分析,列举了各种原因导致的结块。从生产实际出发,针对性地采取措施,对工艺控制、设备设施、生产操作和检修维护等进行优化,减少或者消除反应器结块现象,保障Innovene工艺聚丙烯装置生产的顺利进行。     

Heat Removal from Reverse Flow Reactors Used in Methane Combustion

The idea of using Reverse Flow Reactors (RFR) for methane reduction in exhausts has been well elucidated in the past. However, there are intricacies in such operations to maintain the ignited state of the reactor along with maintaining low outlet concentrations of methane. This is especially true under rich feed conditions where combustion reactions liberate more heat leading to possible catalyst deactivation. Under favourable conditions, it is possible to continuously extract heat from the RFR system‐this is a viable way of maintaining acceptable thermal conditions in the reactor and consequently retaining catalyst activity. This paper elaborates upon the optimal amount of heat that can be removed from the system without losing the sustainability while preventing overheating of the catalyst bed. A simple event based control strategy is implemented for switching the inlet and outlet ports (flow reversal). Issues relating to the operation of reverse flow reactors with side feeding and the possibility of extraction of useful heat from such systems are also discussed. Methane combustion reaction and a continuous two dimensional heterogeneous model of the reactor have been employed in this study.     

A novel reverse flow reactor coupling endothermic and exothermic reactions. Part I: comparison of reactor configurations for irreversible endothermic reactions

A new reactor concept is studied for highly endothermic heterogeneously catalysed gas phase reactions at high temperatures with rapid but reversible catalyst deactivation. The reactor concept aims to achieve an indirect coupling of energy necessary for endothermic reactions and energy released by exothermic reactions, without mixing of the endothermic and exothermic reactants, in closed-loop reverse flow operation. Periodic gas flow reversal incorporates regenerative heat exchange inside the reactor. The reactor concept is studied for the coupling between the non-oxidative propane dehydrogenation and methane combustion over a monolithic catalyst.Two different reactor configurations are considered: the sequential reactor configuration, where the endothermic and exothermic reactants are fed sequentially to the same catalyst bed acting as an energy repository and the simultaneous reactor configuration, where the endothermic and exothermic reactants are fed continuously to two different compartments directly exchanging energy. The dynamic reactor behaviour is studied by detailed simulation for both reactor configurations. Energy constraints, relating the endothermic and exothermic operating conditions, to achieve a cyclic steady state are discussed. Furthermore, it is indicated how the operating conditions should be matched in order to control the maximum temperature. Also, it is shown that for a single first order exothermic reaction the maximum dimensionless temperature in reverse flow reactors depends on a single dimensionless number. Finally, both reactor configurations are compared based on their operating conditions. It is shown that only in the sequential reactor configuration the endothermic inlet concentration can be optimised independently of the gas velocities at high throughput and maximum reaction coupling energy efficiency, by the choice of a proper switching scheme with inherently zero differential creep velocity and using the ratio of the cycle times.In this first part, both the propane dehydrogenation and the methane combustion have been considered as first order irreversible reactions. However, the propane dehydrogenation is an equilibrium reaction and the low exit temperatures resulting from the reverse flow concept entail considerable propane conversion losses. How this ‘back-conversion’ can be counteracted is discussed in part II Chemical Engineering Science, 57, (2002), 855-872.     

Catalytic wet air oxidation of phenol in concurrent downflow and upflow packed-bed reactors over pillared clay catalyst

An experimental study is presented for comparing the behavior of a packed bed reactor in the catalytic liquid-phase oxidation of aqueous phenol with two modes of operation, downflow and upflow. The operating parameters investigated included temperature, reactor pressure, gas flowrate, liquid hourly space velocity and feed concentration. Because of the completely wetted catalyst, the upflow reactor generally performs better for high pressures and low feed concentrations when the liquid reactant limitation controls the rate. The interaction between the reactor hydrodynamics, mass transfer, and reaction kinetics is discussed. For both operation modes, complete phenol removal and significant total organic carbon (TOC) reduction can be achieved at rather mild conditions of temperature (150-170 °C) and total pressure (1.5-3.2 MPa). The results show that the phenol and TOC conversion are considerably affected by the temperature, while the air pressure only has minor influence. Total elimination of TOC is difficult since acetic acid, as the main intermediate, is resistant to catalytic wet oxidation. All tests were conducted over extrudates of Fe-Al pillared clay catalyst, which is stable and maintains its activity during the long-term experimental process. No significant catalyst deactivation due to metal ion leaching and polymer deposition was detected.     

A logic-based controller for the mitigation of ventilation air methane in a catalytic flow reversal reactor

The control system of a catalytic flow reversal reactor (CFRR) for the mitigation of ventilation air methane was investigated. A one-dimensional heterogeneous model with a logic-based controller was applied to simulate the CFRR. The simulation results indicated that the controller developed in this work performs well under normal conditions. Air dilution and auxiliary methane injection are effective to avoid the catalyst overheating and reaction extinction caused by prolonged rich and lean feed conditions, respectively. In contrast, the reactor is prone to lose control by adjusting the switching time solely. Air dilution exhibits the effects of two contradictory aspects on the operation of CFRR, i.e., cooling the bed and accumulating heat, though the former is in general more prominent. Lowering the reference temperature for flow reversal can decrease the bed temperature and benefit stable operation under rich methane feed condition.     

我国镍系顺丁橡胶聚合过程的工程分析及其改进 Ⅰ.釜式反应器聚合工艺

根据我国镍系顺丁橡胶的生产数据和工艺方案,对釜式丁二烯聚合工艺进行了动力学分析和工程分析。由分析结果推断,镍系催化剂的催化活性具有依温性和依时性两大特性,而釜式反应器的热不穗态操作特性则是过程偏离优化操作的主要根源。     

THE OPTIMUM TEMPERATURE POLICY FOR A DEACTIVATING IMMOBILISED ENZYME FIXED BED REACTOR†

A criterion is developed for the optimum operation of an isothermal fixed bed reactor using a deactivating immobilised enzyme catalyst. The chemical reaction is assumed to follow a Michaelis-Menten type kinetics, and the deactivation is assumed to depend only upon the temperature of operation. An explicit equation for dT/dt is derived from the criterion which makes it possible to calculate the optimum reactor temperature as a function of time in a straightforward manner for a given initial temperature by standard numerical integration techniques. It turns out that the optimum temperature policy results in a varying conversion at the reactor outlet. A numerical example is presented which indicates that such a policy is better than both a constant temperature policy and a constant conversion policy. The techniques developed here can also be used for a gas-solid catalytic reactor involving Langmuir-Hinshelwood kinetics with concentration independent deactivation.     

低压立式水冷甲醇合成塔在20kt／a甲醇装置上的应用总结

简要介绍了低压立式水冷甲醇合成塔开车及初步运行情况。实际运行结果表明,该甲醇合成塔壳体与内件设计为分体诘构,催化剂装御方便,具有操作简单、移热能力强、床层温度分布均匀、反应热利用率高、塔阻力小、运行稳定等特点。     

THE OPTIMUM TEMPERATURE POLICY FOR A DEACTIVATING IMMOBILISED ENZYME FIXED BED REACTOR†

A criterion is developed for the optimum operation of an isothermal fixed bed reactor using a deactivating immobilised enzyme catalyst. The chemical reaction is assumed to follow a Michaelis-Menten type kinetics, and the deactivation is assumed to depend only upon the temperature of operation. An explicit equation for dT/dt is derived from the criterion which makes it possible to calculate the optimum reactor temperature as a function of time in a straightforward manner for a given initial temperature by standard numerical integration techniques. It turns out that the optimum temperature policy results in a varying conversion at the reactor outlet. A numerical example is presented which indicates that such a policy is better than both a constant temperature policy and a constant conversion policy. The techniques developed here can also be used for a gas-solid catalytic reactor involving Langmuir-Hinshelwood kinetics with concentration independent deactivation.