Online Estimation of Catalyst Activity in a Packed bed Reactor

设计了一种不受观测噪声影响的状态观测器，用于估计填充床反应器中的浓度分布和温度分布。采用正交配置法，从反应器的无因次质量和热平衡模型出发，推导出非线性常微分方程组。基于推导出的ODE模型，采用扩展卡尔曼滤波器对状态变量和速率常数频率因子进行估计，并通过仿真验证了所设计观测器的估计性能。结果表明，即使在观测噪声存在的情况下，观测器也能准确地估计出浓度和温度分布，频率因子也与模拟器的值一致。其次，利用填充床反应器（长90 cm，直径2.5cm）进行了乙烯完全氧化实验。通过对反应器内3 ~ 5个点的温度测量和红外气体分析仪的浓度测量，可以较好地估计反应器内的浓度分布、温度分布和频率因子。频率因子的估计值与初步实验值在10%的精度范围内一致。由于没有观察到随着反应时间的进展的催化剂失活，因此没有通过使用观察器检测催化剂失活率。然而，由于该观测器可以在线估计频率因子，因此认为也可以通过随着反应时间的进展观察频率因子的估计值来估计催化剂失活。

A state observer which was not influenced by observation noise was designed to estimate the concentration and the temperature profiles in a packed-bed reactor. By use of orthogonal collocation method, nonlinear ordinary differential equations (ODE) were derived from the non-dimensional mass and the heat balance model of the reactor. Extended Kalman filter based on the derived ODE model was used to estimate both the state variables and frequency factor of rate constant.Simulation was performed to confirm the estimation performances of the designed observer. The results showed that the observer estimated the concentration and the temperature profiles accurately even in the presence of the observation noise, and the frequency factor also agreed with the value of the simulator.Next, experiment of the perfect ethylene oxidation was carried out by using the packed-bed reactor (90cm length, 2.5cm diameter). The concentration and the temperature profiles and the frequency factor were estimated well by using measured temperature of 3 to 5 points in the reactor and concentration measured by infrared gas analyzer. The estimated frequency factor agreed with the value obtained by the preliminary experiment within the accuracy of 10%. Since the catalyst deactivation with the progress in the reaction time was not observed, catalyst deactivation rate was not detected by using the observer. However, because this observer can estimate the frequency factor online, it is considered that the catalyst deactivation can be also estimated by watching the estimated value of the frequency factor with the progress in the reaction time.