Improving the accuracy of mechanistic models for dynamic batch distillation enabled by neural network:An industrial plant case

Neural networks are often viewed as pure‘black box’models,lacking interpretability and extrapolation capabilities of pure mechanistic models.This work proposes a new approach that,with the help of neural networks,improves the conformity of the first-principal model to the actual plant.The final result is still a first-principal model rather than a hybrid model,which maintains the advantage of the high interpretability of first-principal model.This work better simulates industrial batch distillation which separates four components:water,ethylene glycol,diethylene glycol,and triethylene glycol.GRU(gated recurrent neural network)and LSTM(long short-term memory)were used to obtain empirical parameters of mechanistic model that are difficult to measure directly.These were used to improve the empirical processes in mechanistic model,thus correcting unreasonable model assumptions and achieving better predictability for batch distillation.The proposed method was verified using a case study from one industrial plant case,and the results show its advancement in improving model predictions and the potential to extend to other similar systems.

Silver modified Cu/SiO2 catalyst for the hydrogenation of methyl acetate to ethanol

A series of silver modified Cu/SiO2 catalysts were synthesized with ammonia-evaporation method and applied in vapor-phase hydrogenation of methyl acetate to ethanol.The influence of additive‘Ag’on the structural evolution of catalyst was systematically studied by several characterization techniques,such as N2 adsorption–desorption,N2O titration,PXRD,FTIR,in-situ FTIR,H2-TPR,H2-TPD,XPS and TEM.Results showed that incorporation of a small amount of Ag could enhance the structural stability,and the strong interaction between Cu and Ag species was conducive to increase the dispersion of copper species and create a suitable Cu+/(Cu0+Cu+)ratio,which was proposed to be responsible for the improved catalytic activity.The maximum conversion of MA(94.1%)and selectivity of ethanol(91.3%)over optimized Cu-0.5 Ag/SiO2 and 120 h on stream without deactivation under optimal conditions demonstrates its excellent stability.

A novel kind of multiple steady states characteristics in the dividing wall column

In this article, one kind of multiple steady states(MSS) phenomenon was investigated for a dividing wall column(DWC). The four-section model constructed in Aspen Plus was employed to simulate two DWC cases: mixture of n-hexane, n-heptane and n-octane;system of methanol, ethanol and n-propanol. It can be seen that there is a range of vapor split ratio in which multiple solutions of reflux ratio exist for fixed DWC configuration with the same feed and product streams. The width and the curve shapes of the MSS region, and the number of solutions change with the liquid split ratio. This MSS phenomenon was further explained using the component recovery around the prefractionator and the component recycling flow inside the DWC. This MSS phenomenon is helpful for DWC design by knowing the probable existence of multiple solutions in advance.

A novel synthetic method of porous and nanoflower-like Al_(2)O_(3)/MoS_(2)catalyst for reduction of SO_(2)to elemental sulfur

MoS_(2)nanoflowers are favored for their potential in the production of elemental sulfur due to abundant surface area and good catalytic performance for reducing SO_(2).A novel synthetic strategy of porous Al_(2)O_(3)supported on the MoS_(2)with nanoflower structure was proposed.The effects of preparation concentration,calcination atmosphere,Al_(2)O_(3)contents on the growth of catalysts with nanoflower structure were systematically studied via X-ray diffraction(XRD),scanning electron microscopy(SEM),X-ray photoelectron spectroscopy(XPS),transmission electron microscopy(TEM),Fourier transform infrared(FTIR)spectroscopy,Brunauer–Emmett–Teller(BET).The surface area was increased to 295.502 m^(2)/g and the amount of Lewis acid on the surface of the Al_(2)O_(3)/MoS_(2)catalyst was increased by adjusting the ratio of Al/Mo.The porous and nanoflower structures of Al_(2)O_(3)/MoS_(2)catalysts promoted the sulfur selectivity without inhibiting the catalytic performance of MoS_(2).The conversion of SO_(2)and the selectivity of sulfur were 100%and 92%after 100 h life evaluation.

丁烷氧化反应器装置数据分析与优化

基于丁烷氧化反应器的实际装置数据,经预处理后,采用主成分分析进行数据挖掘。结果表明,可利用该方法来筛选及判断异常数据点,从而可用于反应器状态的实时诊断和预警,同时对反应器输入和输出参数之间的相关性进行分析,理解和把握参数之间的变化特征,发现丁烷转化率与反应器出口的CO/CO2比值呈负相关,体现主反应和副反应的选择性问题,从而可用于指导反应器操作优化等。