Batch process monitoring using on-line MIR spectroscopy

Many high quality products are produced in a batch wise manner. One of the characteristics of a batch process is the recipe driven nature. By repeating the recipe in an identical manner a desired end-product is obtained. However, in spite of repeating the recipe in an identical manner, process differences occur. These differences can be caused by a change of feed stock supplier or impurities in the process. Because of this, differences might occur in the end-product quality or unsafe process situations arise. Therefore, the need to monitor an industrial batch process exists. An industrial process is usually monitored by process measurements such as pressures and temperatures. Nowadays, due to technical developments, spectroscopy is more and more used for process monitoring. Spectroscopic measurements have the advantage of giving a direct chemical insight in the process. Multivariate statistical process control (MSPC) is a statistical way of monitoring the behaviour of a process. Combining spectroscopic measurements with MSPC will notice process perturbations or process deviations from normal operating conditions in a very simple manner. In the following an application is given of batch process monitoring. It is shown how a calibration model is developed and used with the principles of MSPC. Statistical control charts are developed and used to detect batches with a process upset.     

氟碳铈矿提取稀土的绿色化学进展

氟碳铈矿是稀土工业的重要原材料，目前从氟碳铈矿提取稀土主要采用酸法工艺，该工艺虽然稀土回收高，但流程长，试剂消耗长，成本较高，同时酸法产生ＨＦ及废酸碱污染环境。因此寻找低成本，低污染的绿色化学处理工艺是近几十年中人们一直努力的方向。本文系统介绍了氟碳铈矿分解工艺的发展，并着重介绍邓氯化铵法提取氟碳铈矿稀土的的新工艺。该工艺采用盐类分解并氯化氟碳铈矿，直接用水浸取回收稀土，不引入酸和碱，提高了反应选择性，减轻了稀土在稀土杂质分负荷，降低了化工材料消耗，简化了工艺，提高了回收率，是符合绿色化学要求的工艺。     

A validation concept for purity determination and assay in the pharmaceutical industry using measurement uncertainty and statistical process control

 The analytical chemists in process development in the pharmaceutical industry have to solve the difficult problem of producing high quality methods for purity determination and assay within a short time without a clear definition of the substance to be analyzed. Therefore the quality management is very difficult. The ideal situation would be that every method is validated before use. This is not possible because this would delay the development process. A process-type quality development approach with an estimation type fast validation (measurement uncertainty) is therefore suggested. The quality management process consists of the estimation of measurement uncertainty for early project status. Statistical process control (SPC) is started directly after measurement uncertainty estimation and a classical validation for the end of the project. By this approach a process is defined that allows a fast and cost-efficient way of supporting the development process with the appropriate quality at the end of the process and provides the transparency needed in the development process. The procedure presented tries to solve the problem of the parallelism between the two development processes (chemical and analytical development) by speeding up the analytical development process initially. Received: 25 March 1997 · Accepted: 17 May 1997     

Adsorption process of phenothiazine solution in dimethyl sulfoxide on graphite electrodes

In this paper, an original solution for the modeling and simulation of the adsorption process of a phenothiazine derivative on graphite electrodes is presented. The adsorption process is considered a distributed parameter one, due to the fact that the adsorbed phenothiazine quantity is a function depending on two independent variables. The structure parameters of the adsorption process, which define the influence of both independent variables, are determined using an experimental identification method. The experimental data are obtained through an experiment which is based on the process step response. In order to simulate the adsorption process, the approximate analytical solution, representing the process model, is determined. The simulation results prove the model generality; it is being simulated in relation to both independent variables.     

Using computer simulation to assist in the robustness analysis of an ion-exchange chromatography step

This paper presents a methodology to gain process knowledge and assist in the robustness analysis of an ion-exchange step in a protein purification process using a model-based approach. Factorial experimental design is common practice in industry today to obtain robustness characterization of unit operations with respect to variations in process parameters. This work aims at providing a better insight into what process variations affect quality and to further reduce the experimental work to the regions of process variation that are of most interest. This methodology also greatly increases the ability to predict process performance and promotes process understanding. The model calibration part of the methodology involves three consecutive steps to calibrate a steric mass action (SMA) ion-exchange chromatography model. Firstly, a number of gradient elution experiments are performed. Secondly, experimental breakthrough curves have to be generated for the proteins if the adsorption capacity of the medium for each component is not known. Thirdly, a multi-component loading experiment is performed to calibrate the multi-component effects that cannot be determined from the single-component experiments. The separation process studied in this work is the separation of polyclonal IgG from a mixture containing IgG, myoglobin and BSA. The calibrated model is used to simulate six process variations in a full factorial experiment. The results of the simulations provide information about the importance of the different process variations and the simulations are also used to determine the crucial points for the process parameter variations. The methodology can be used to assist in the robustness analysis normally performed in the pharmaceutical industry today as it is able to predict the impact on process performance resulting from variations in salt concentration, column load, protein concentration and flow rate.     

N，N－二甲基甘氨酸乙酯分解反应机理的理论研究

利用量子化学计算方法MP2／6－31＋G^*研究了N，N－二甲基甘氨酸乙酯在气 相中热分解反应机理，并计算了反应的协同性，得出此反应是一个多步反应过程。 主要有两个阶段：第一个阶级是N，N－二甲基甘氨酸乙酯热分解产生N，－N二甲基 甘氨酸中间体和乙烯，第二个阶段是N，N－二甲基甘氨酸进一步分解生成三甲氨和 二氧化碳。第一个反应阶段为速率控制步骤。研究表明，该反应机理是一个非协同 的质子转移过程。计算结果与实验值吻合。     

Monitoring of an industrial process by multivariate control charts based on principal component analysis

The control and monitoring of an industrial process is performed in this paper by the multivariate control charts. The process analysed consists of the bottling of the entire production of 1999 of the sparkling wine "Asti Spumante". This process is characterised by a great number of variables that can be treated with multivariate techniques. The monitoring of the process performed with classical Shewhart charts is very dangerous because they do not take into account the presence of functional relationships between the variables. The industrial process was firstly analysed by multivariate control charts based on Principal Component Analysis. This approach allowed the identification of problems in the process and of their causes. Successively, the SMART Charts (Simultaneous Scores Monitoring And Residual Tracking) were built in order to study the process in its whole. In spite of the successful identification of the presence of problems in the monitored process, the Smart chart did not allow an easy identification of the special causes of variation which casued the problems themselves.     

Broadband dielectric study of the glass transition in poly(ethyleneglycol)-water mixture

We performed broadband dielectric measurements of a polyethyleneglycol-water mixture in the frequency range between 10 GHz and 1 microHz and the temperature range between 300 and 133 K. One relaxation process is observed throughout the whole temperature range. The temperature dependence of the relaxation time clearly obeys the Vogel-Fulcher law above 183 K, and the Arrhenius law below 183 K. This observed relaxation process is the secondary process, and the primary process related to the glass transition is masked by the low-frequency ionic contribution below 183 K. The glass transition concerned with the masked primary process leads to the Vogel-Fulcher to Arrhenius transition of the secondary process.     

A novel multi‐mode data processing method and its application in industrial process monitoring

Multi‐mode process monitoring is a key issue often raised in industrial process control. Most multivariate statistical process monitoring strategies, such as principal component analysis (PCA) and partial least squares, make an essential assumption that the collected data follow a unimodal or Gaussian distribution. However, owing to the complexity and the multi‐mode feature of industrial processes, the collected data usually follow different distributions. This paper proposes a novel multi‐mode data processing method called weighted k neighbourhood standardisation (WKNS) to address the multi‐mode data problem. This method can transform multi‐mode data into an approximately unimodal or Gaussian distribution. The results of theoretical analysis and discussion suggest that the WKNS strategy is more suitable for multi‐mode data normalisation than the z‐score method is. Furthermore, a new fault detection approach called WKNS‐PCA is developed and applied to detect process outliers. This method does not require process knowledge and multi‐mode modelling; only a single model is required for multi‐mode process monitoring. The proposed method is tested on a numerical example and the Tennessee Eastman process. Finally, the results demonstrate that the proposed data preprocessing and process monitoring methods are particularly suitable and effective in multi‐mode data normalisation and industrial process fault detection. Copyright © 2014 John Wiley & Sons, Ltd.     

The surface chemistry of Bayer process solids: a review

The Bayer process is used for refining bauxite to smelting grade alumina (Al₂O₃), the precursor to aluminium. The process was developed and patented by Karl Josef Bayer 110 years ago, and has become the cornerstone of the aluminium production industry worldwide. Production of alumina reached 46.8 megatonnes (Mt) worldwide by the end of 1997, with Australia the worlds largest producer of bauxite and refiner of alumina with just under 30% of world production. Although the refining process is well established and the basic theories underpinning it are well defined, the fundamental chemistry of the Bayer process is not well understood. Of particular interest to industrial and academic researchers alike, is the chemistry of the Bayer process solids—aluminium trihydroxide, ‘red mud’ and sodium oxalate. The surface chemistry of these solids is of great industrial importance as the refining industry experiences significant restrictions due to limitations imposed on the process by surface chemical reactions. Of scientific interest is the conceptual advancement of our knowledge and understanding of the nature of surfaces under extreme (non-ideal) conditions. A review of the current literature relating to these important Bayer process solids is thus presented. While not exhaustive, the review is thorough and aims to familiarise the reader with current levels of understanding regarding the nature of Bayer process solids surfaces under Bayer process conditions, and the significant roles these solids play in the overall efficiency of the refining process. It is hoped that this review will provide a useful starting point for researchers new to the area of Bayer process research, whilst also stimulating further fundamental research in this economically and scientifically significant area.     

Cationic membranes for phenols production

Ionic Substitution by Electrodialysis is a good alternative to the industrial conversion of sodium salts of phenols into undissociated phenols, conventionally performed through acidification by strong acids. The acidification through electromembranes combines the possibility to achieve high conversion values with the advantage of keeping the process stream separated from the acid stream. The process is performed through cationic membranes; conversion can be obtained also in the absence of electric current, even if slightly better performances can be achieved by applying an electric field. Process feasibility as well as membrane resistance is tested, for the case of model solutions reproducing the main features of the real process streams. Maximum conversion and process rate are greatly affected by the ratio between protons in the acid solution and sodium ions in the process solution. Phenol losses into the acid stream and chloride contamination of the process stream can be reduced by working with diluted process and acid streams.     

Status of sol–gel process for nuclear fuels

Sol–gel process provides an alternate route for fabrication of ceramic nuclear fuel. The sol–gel process provides several advantages over the conventional powder pellet fabrication process by eliminating handling of radioactive powders. The sol–gel process uses only fluids or fluid like materials, thus become amenable to remote handling. The sol–gel process has been developed for the production of coated particle fuels for High Temperature Gas Cooled Reactors (HTGRs), as sphere-pac fuel for Fast Breeder Reactors (FBRs) and as SGMP fuel for Thermal Reactors. Internal Gelation Process is one of the most important routes of the sol–gel process and has been accepted as the most promising process route globally. Several countries having plutonium or ²³³U based fuel program have developed sol–gel process for nuclear fuels. In India there is special interest for the development of the sol–gel process for the thorium–uranium fuels keeping in view the large resources of thorium in India. Sol–gel process for fuel fabrication is also very attractive route for closing the nuclear fuel cycle efficiently. Author is BRNS Raja Ramanna Fellow.     

Optimization of Saccharification and Fermentation Process in Bioethanol Production from Oil Palm Fronds

Oil Palm Frond (OPF) is one of lignocellulosic biomass, which can be utilized as raw material for bioethanol production. Bioethanol is produced as alternative energy to substitute gasoline. There are four steps in bioethanol production from OPF, i.e pretreatement, saccharification, fermentation and purification process. In this study, optimization of saccharification and fermentation process for OPF was investigated. Two methods and the variations of enzyme concentration were carried out in the saccharification and fermentation process. Separate hydrolysis and fermentation process (SHF) and simultaneous saccharification and fermentation process (SSF) were conducted to produce ethanol optimally. Variations of enzyme concentration used in this process were 10, 20, 30 and 40 FPU/g substrate. The result shows that the highest ethanol concentration can be obtained in SSF process with 30 FPU/g substrate of enzyme concentration. The process produced 59.20 g/L ethanol (95.95% yield ethanol) at 96 h of SSF process.     

化学计量学在过程分析中的应用及进展

评述了化学计量学方法在生产过程分析中各个方面 ,如过程优化、过程模拟、仪器及仪器校正、过程监测等方面的应用 ,并展望了化学计量学在过程分析中的应用前景     

煤化工工艺技术评述与展望Ⅳ．煤间接液化技术

评述了国内外煤间接液化合成液体燃料开发趋势和工业化状况,从催化剂研制,F－T合成反应器开发,合成油工艺路线,工艺软件开发,工艺集成优化和技术经济分析等方面进行了讨论,指出发展洁净高效煤基合成液体燃料工业过程是解决我国燃油短缺的根本途径,并对我国煤制油工业化开发工作和示范厂建立提出一些建议和展望。     

Generation of surface energy patterns by single pulse laser interference on self-assembled monolayers

Single pulse laser interference lithography is used to structure self-assembled monolayers of thiols on gold. This structuring process is investigated by attenuated total reflection measurements, and a demixing process of a binary polymer blend is used to visualize the produced surface energy pattern. The lithography can be realized with different wavelengths (266, 532, and 1064 nm) which shows that the structuring is a thermal process. As a first demonstration of this process, structures down to 800 nm period and 300 nm width are fabricated.     

Unusual relaxation process in polybutadiene: Resolving the controversy

We report the observation of an unusual relaxation process in depolarized light scattering spectra of polybutadiene (PBD) with two different vinyl contents. The process showed up in the gigahertz frequency range with relatively mild temperature dependence and was similar to a secondary relaxation process. The most surprising observation was that the process exists even at high temperatures and does not merge with the segmental relaxation up to a temperature of 400 K (T > 2T_g). Possible mechanisms of this particular relaxation in PBD are discussed. The process is compared to the so‐called E process, double‐bond hopping process, and dielectric β process. We emphasize that this process differs from the dielectric β process, is unique for 1,4‐PBD, and has not been observed in other polymers. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 994–999, 2004     

Material- und Signalfluß

An industrial production process is considered to be divided into a working process and an information process. Starting point for the information process is the sampling of a material flow. The meaning of “representative” samples as well as questions of continuous and non-continuous sampling methods are discussed. The signals coming out of analysis are arranged in a special way according to statistical methods. Thereafter the information content is calculated by using rules of the information theory. The transmission of the information content within a certain time results in an information flux. The information flux actually required by the working process is compared to the information flux provided by analysis; and both are put into an equilibrium followed by considerations on “necessary and sufficient” analytical actions. It is the aim of analytical information processes to reduce the entropy of the working process to a minimum.     

Liquid-phase hydration process of cyclohexene with zeolites

The liquid-phase hydration process of cyclohexene into cyclohexanol with zeolite is described. The characteristic of this industrial process is that fine particles of zeolite are used in a slurry system, which offers high productivity and a simple separation system. In this process, the hydrophobic property and shape selectivity of ZSM-5 are fully utilized so as to realize an economical industrial process.