调整碳三加氢反应器提高丙烯收率

分析乙烯装置丙烯损失大的原因,比较几种方案,找出目前情况下可立即采取的提高丙烯收率的方法,并根据实际情况说明调整的正确性。     

碳二加氢反应器的优化

合理分配一段、二段、三段的炔烃脱除量,并配入适量CO,可以将三段入口乙炔浓度提高到0.2%左右,二段入口乙炔浓度提高到0.6%左右,从而提高加氢反应的选择性,增加乙烯收率,使得装置运行时间更长。     

碳二加氢体系热力学分析

对碳二加氢体系进行了较为详尽的热力学分析,得到不同温度条件下各反应的热焓、吉布斯自由能以及反应平衡常数,确定了主要副反应和绿油生成反应,根据计算结果指出,提高反应选择性、降低绿油生成量是碳二加氢催化剂开发所面临的主要难题,而降低乙炔在催化剂表面强吸附物种的数量,是提高选择性、抑制绿油生成的主要手段。     

碳二加氢反应器在线无扰动切换方法的探索

碳二加氢反应器的切换是乙烯装置运行过程中的重大操作工序，而离线切换会造成乙烯产品的大量损失。文中介绍的是天津乙烯在不干扰其它设备的运行和不影响产品质量的前提下，在线无扰动切换碳二加把反应器的方法。     

乙烯装置碳二加氢反应器改造及开车条件优化

对乙烯装置的碳二加氢反应器本体进行改造,以改善物料在反应器内的流动状态;优化裂解气压缩机五段出口防喘振控制方案,以满足反应器运行对空速的要求;优化催化剂钝化方案,缩短碳二加氢反应合格时间。通过上述改造和优化措施,乙烯装置减少了开工过程中的火炬排放,顺利实现装置原始开车一次成功。     

碳二加氢催化剂选择性快速评价法及其应用

从理论推导得出碳二加氢催化剂选择性快速评价法,并用此方法对三种碳二加氢催化剂选择性进行评价,并指出此快速评价法的独特应用。     

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.     

碳二加氢反应器在线切换技术探索

经过多年来对碳二加氢反应器切换方式的摸索实践认为,单段床加氢反应流程中在线切换可行。双段床加氢反应流程,采用全加氢负荷在线切换,完全可保证乙炔加氢反应合格。     

碳四组分对碳二加氢系统的影响

论述了碳二加氢进料C4组分含量较高的原因及其对反应器的影响,提出了避免反应器飞温和出口漏炔的方法,减少乙烯损失,提高经济效益,节能降耗。     

Model predictive control of an industrial pyrolysis gasoline hydrogenation reactor

This study focuses on the implementation of a nonlinear model predictive control (MPC) algorithm for controlling an industrial fixed-bed reactor where hydrogenations of raw pyrolysis gasoline occur. An orthogonal collocation method is employed to approximate the original reactor model consisting of a set of partial differential equations. The approximate model obtained is used in the synthesis of a MPC controller to control the temperature rising across a catalyst bed within the reactor. In the MPC algorithm, a sequential optimization approach is used to solve an open-loop optimal control problem. Feedback information is incorporated in the MPC to compensate for modeling error and unmeasured disturbances. The control studies are demonstrated in cases of set point tracking and disturbance rejection.     

碳二加氢直列式三段反应器的长周期运行

国内部分乙烯装置的反应器为直列式三段反应器,这种布局方式的优点是物料流向和操作简单,但缺点是反应器的切换和再生是3个反应器同时进行,在反应器切换过程中,易发生漏炔和飞温,再生时由于温度从下到上逐渐降低,很难使催化剂再生完全,因此,保证催化剂的长周期运行至关重要。通过对碳二加氢直列式三段反应器负荷的优化分配,合理设定各段的氢与炔体积比,使反应器由原来平均运行6个月,提升到运行13个月以上,满足了装置长周期运行的要求。     

A porous structured reactor for hydrogenation reactions

A novel combination of catalyst carrier and reactor design was developed for intensified production of vitamin intermediates. The so called Design Porous Structured Reactor (DPSR) is a laser sintered porous 3D-structure that can be tailored to the desired reaction properties such as fluid conditions or heat removal and can also act simultaneously as catalyst support.The selective hydrogenation of 2-methyl-3-butyn-2-ol (MBY) to 2-methyl-3-buten-2-ol (MBE) under solvent-free conditions was chosen as the reaction to evaluate the potential of DPSRs in comparison to conventional batch reactors. DPSR experiments were performed at varying temperatures and liquid flow rates.DPSRs exceeded batch performance in terms of selectivity, yield and turnover frequency in the analyzed process parameter range. However, DPSRs showed some mass transfer effects. Selectivities and yields increased with higher liquid flow rate due to reduced system pressures and sharper residence time distributions.Overall mass transfer coefficients for DPSRs were determined based on an isothermal non-ideal plug flow model applying heterogeneous Langmuir–Hinshelwood kinetics to account for the chemical conversion. The model showed sufficient accuracy to describe the occurring mass transfer processes.DPSRs were found to be viable alternative for batch reactors, demonstrating the potential for process intensification with an inherent potential for further improvement.     

Development of a microchannel catalytic reactor system

The purpose of this article is to demonstrate the applicability of microreactors for use in catalytic reactions at elevated temperatures. Microchannels were fabricated on both sides of a silicon wafer by wet chemical etching after pattern transfer using a negative photoresist. The walls of the reactor channel were coated with a platinum layer, for use as a sample catalyst, by sputtering. A heating element was installed in the channel on the opposite surface of the reactor channel. The reactor channel was sealed gas-tight with a glass plate by using an anodic bonding technique. A small-scale palladium membrane was also prepared on the surface of a 50-Μm thick copper film. In the membrane preparation, a negative photoresist was spin-coated and solidified to serve as a protective film. A palladium layer was then electrodeposited on the other uncovered surface. After the protective film was removed, the resist was again spin-coated on the copper surface, and a pattern of microslits was transferred by photolithography. After development, the microslits were electrolitically etched away, resulting in the formation of a palladium membrane as an assemblage of thin layers formed in the microslits. The integration of the microreactor and the membrane is currently under way.     

大庆石化碳二加氢反应器运行影响因素分析

通过对大庆石化碳二加氢反应器运行状态进行分析,研究了反应温度、空速、一氧化碳、碳四含量对碳二加氢反应器的影响,并提出优化操作方法,保证反应器长周期运行。     

Model predictive control for the reactant concentration control of a reactor

The reactant concentration control of a reactor using Model Predictive Control (MPC) is presented in this paper. Two major difficulties in the control of reactant concentration are that the measurement of concentration is not available for the control point of view and it is not possible to control the concentration without considering the reactor temperature. Therefore, MIMO control techniques and state and parameter estimation are needed. One of the MIMO control techniques widely studied recently is MPC. The basic concept of MPC is that it computes a control trajectory for a whole horizon time minimising a cost function of a plant subject to a dynamic plant model and an end point constraint. However, only the initial value of controls is then applied. Feedback is incorporated by using the measurements/estimates to reconstruct the calculation for the next time step. Since MPC is a model based controller, it requires the measurement of the states of an appropriate process model. However, in most industrial processes, the state variables are not all measurable. Therefore, an extended Kalman filter (EKF), one of estimation techniques, is also utilised to estimate unknown/uncertain parameters of the system. Simulation results have demonstrated that without the reactor temperature constraint, the MPC with EKF can control the reactant concentration at a desired set point but the reactor temperator is raised over a maximum allowable value. On the other hand, when the maximun allowable value is added as a constraint, the MPC with EKF can control the reactant concentration at the desired set point with less drastic control action and within the reactor temperature constraint. This shows that the MPC with EKF is applicable to control the reactant concentration of chemical reactors.     

Ethylene selectivity variation in acetylene hydrogenation reactor with the hydrogen/acetylene ratio at the reactor inlet

Variation in the selectivity of ethylene produced by acetylene hydrogenation in an integral reactor was analyzed as a function of the hydrogen/acetylene ratio in the reaction stream at the reactor inlet. The analyses were made for two sample catalysts, which showed different dependence of the ethylene selectivity on the reactant composition. Even a small mismatch between the hydrogen/acetylene ratio at the reactor inlet and the ratio for converted reactants caused a large change in the ethylene selectivity along the reactor position, particularly when the conversion was high. The results of this study indicate two important factors to be considered in the design and operation of acetylene hydrogenation process: the hydrogen/acetylene ratio in the reactor inlet should be controlled close to the ratio for converted reactants; and catalysts showing high ethylene selectivity over a wide range of the hydrogen/ acetylene ratio are required for the design of a highly selective hydrogenation process. This paper is dedicated to Professor Wha Young Lee on the occasion     

Model predictive control of a fixed-bed reactor with nonlinear quality inference

A generic model predictive control framework has been proposed for a fixed-bed reactor with exothermic reaction. The proposed framework can conduct nonlinear inferential control of a product concentration together with linear multivariable control of bed temperatures. In addition, the framework can accommodate the multi-rate sampling and analysis delay caused by the product measurement. Performance of the proposed technique has been demonstrated with a non-adiabatic fixed bed reactor model producing maleic anhydride under various operating scenarios.     

先进控制系统在精馏中的应用

本文主要讨论分析了轻烃分馏分公司戊烷精分车间装置先进性系统建立的原因,以及建立过程中出现的问题,投用后取得的成效。这次采用先进控制技术对原有的DCS集散系统进行了进一步的优化。该技术是在国内同类装置上首次应用,使我国乃至亚洲戊烷精分装置的综合自动化水平实现了重大突破。它的最大作用是可以克服各种干扰因素,实现对戊烷精分装置的稳定、快速和准确的控制,同时通过优化调整工艺参数实现产品质量和产量的＂卡边＂控制。