A comprehensive review on modeling of pneumatic and flash drying

Pneumatic conveying drying (PCD) is a widely used process in the industries and is a combination of heat and mass transfer and pneumatic handling technology. Drying processes consume large amounts of energy and, therefore, reduction in operating cost will be extremely beneficial for the industry. Many studies have been conducted to model and optimize the pneumatic drying. This review article focuses on the different strategies used in the literature to model pneumatic drying processes. An analysis is provided for the different mathematical modeling and its components such as balance and complementary equations and modeling assumptions. Two-fluid theory, Eulerian granular, and the discrete element method are reviewed as well as gas–solid flow modeling methods. In addition, the numerical methods and the main studied parameters in the field of pneumatic drying are investigated. To this end, heat and mass transfer coefficients, gas and dispersed phase properties are reviewed.     

气力输送系统技术和部件的新进展

随着社会发展、市场需求的变化和环保要求的日益提高，气力输送技术面临着许多新课题。介绍了国外开发的高浓度物料低速气力输送、带多级喷射真空发生器的气力输送装置，细粉的收尘技术，管道中料流流动的改性技术，以及几种供料器和耐磨Dome阀等的工作原理和结构，使气力输送技术达到了高效、节能、无污染、自动化程度高等目的，以适应市场需求的变化。     

Analysis of Asymmetrical Creep of a Ceramic at 1350°C by Digital Image Correlation

The glass industry requires the use of innovative ceramics that enable for long lifetimes. At very high temperatures, one of the key parameters for ceramics is their creep resistance. The characterization of the creep behavior, usually assessed through flexural tests, can be complex when an asymmetry appears between tension and compression. To detect and quantify such asymmetrical behaviors, the use of Digital Image Correlation (DIC) is proposed. First, several challenges are to be tackled for DIC at high temperature, namely, the random pattern stability, the radiation filtering and the heat haze. They are exacerbated by the limited possibilities to heat ceramics, the nonuniform strain fields and their low levels. Beyond several experimental developments, the strain uncertainties are decreased thanks to the use of two global approaches of DIC based on ad hoc finite‐element kinematics. Last, the proposed methodology is applied to the analysis of asymmetric creep at 1350°C of an industrial zircon ceramic designed for its high creep resistance.     

Vakuumpumpen in der Verfahrenstechnik

Vacuum pumps in chemical engineering. Applications of vacuum pumps in chemical engineering are numerous. After a general systematization of the working principles of vacuum pumps, the most important types – liquid ring vacuum pumps, sliding vane vacuum pumps, and ejectors – are discussed with regard to their development and their working principle. Attention is focussed on aspects which allow a comparison of the advantages and disadvantages of vacuum pumps. A systematic survey of the criteria leading to the selection of a certain type of pump show that these criteria may be based on the process as a whole or on environmental and safety considerations as well as economic aspects. In areas where liquid ring vacuum pumps, sliding vane vacuum pumps, and ejectors may be applied the extent to which the pumps fulfill these criteria is shown. In this context, a comparison of the liquid ring pump and the sliding vane pump is of special interest. The doubts recently publicized concerning the environmental compatibility of liquid ring vacuum pumps are shown to be groundless if the pumps are installed correctly. Great care must be taken comparing the economic aspects of liquid ring pumps and sliding vane pumps.     

Design and assessment of delay timer alarm systems for nonlinear chemical processes

In process and manufacturing industries, alarm systems play a critical role in ensuring safe and efficient operations. The objective of a standard industrial alarm system is to detect undesirable deviations in process variables as soon as they occur. Fault detection and diagnosis systems often need to be alerted by an industrial alarm system; however, poorly designed alarms often lead to alarm flooding and other undesirable events. In this article, we consider the problem of industrial alarm design for processes represented by stochastic nonlinear time‐series models. The alarm design for such complex processes faces three important challenges: (1) industrial processes exhibit highly nonlinear behavior; (2) state variables are not precisely known (modeling error); and (3) process signals are not necessarily Gaussian, stationary or uncorrelated. In this article, a procedure for designing a delay timer alarm configuration is proposed for the process states. The proposed design is based on minimization of the rate of false and missed alarm rates—two common performance measures for alarm systems. To ensure the alarm design is robust to any non‐stationary process behavior, an expected‐case and a worst‐case alarm designs are proposed. Finally, the efficacy of the proposed alarm design is illustrated on a non‐stationary chemical reactor problem. © 2017 American Institute of Chemical Engineers AIChE J, 63: 77–90, 2018     

Vakuumerzeugung bei Fettsäuredestilationen

Vacuum Generation in Fatty Acid Distillation Operation costs, i. e. energy cost and depreciation, for the various processing alternatives in vacuum generation for fatty acid distillation are explained and compared. This should enable a decision for a particular process with due consideration of the operational conditions. Following alternative processes are compared: 1. Vacuum generation using vapour compressors and ejectors with intermediate condensation in direct condensers without recycling of cooling water; 2. same as 1 but with recycling of cooling water; 3. vacuum generation using vapour compressors and ejectors with intermediate condensation in surface condensers without recycling of cooling water; 4. same as 3 but with recycling of cooling water. The most economical process is discussed and technical modifications for the solution of ecological problems and energy savings are shown.     

光刻机用精密碳化硅陶瓷部件制备技术

本文介绍了光刻机用碳化硅陶瓷结构件的特点及其对材料的要求,分析了碳化硅陶瓷在光刻机中作为结构件材料使用的优势,着重介绍了中国建筑材料科学研究总院在精密碳化硅结构件的制备领域所取得的技术成果,列举了精密碳化硅结构件在光刻机等集成电路制造关键装备中的应用。     

Dynamics and control of integrated microchemical systems with application to micro-scale fuel processing

Microchemical systems are a new generation of miniature chemical systems that carry out chemical reactions and separations in precisely fabricated three dimensional microreactor configurations in the size range of a few microns to a few hundred microns. Typical microchemical systems combine fluid handling and reaction capabilities with electronic sensing and actuation, are fabricated using integrated circuit (IC) manufacturing techniques and use silicon and related IC industry materials, polymers, ceramics, glass or quartz as their material of construction. The use of such systems for in situ and on-demand chemical production is gaining increasing importance as the field of microreaction engineering transitions from a theoretical concept to a technology with significant industrial applications. In this paper, we present a review of our work on MEMS-based microfabrication, modeling and control of micro-reformers for hydrogen delivery systems in micro-fuel cells and put it in the context of a number of reported studies in the literature on this topic. The paper concludes by suggesting possible areas of future research.     

过程工业企业模型系统及战略建模

介绍了过程工业企业模型系统的概念和企业模型系统的构成,并对企业模型系统的研究现状和企业系统模型进行了分析,在此基础上提出了过程企业系统战略模型的层次建模方法,还分析了企业系统战略决策方法。     

Enhancement of entrainment rates in liquid–gas ejectors

Ejectors are widely used as effective distributors in many chemical and bioprocess industries. Gas entrainment rate as a function of liquid flow rate in ejectors is investigated using nozzles of different geometries. The data are analyzed through macro-energy balance for each phase considering air and water inlet line discharge coefficients. Nozzles with smaller discharge coefficients are effective in producing higher vacuum and hence higher entrainment rates. It has been observed that the factor limiting the air entrainment rate is the low discharge coefficient in the air inlet line. Higher air inlet line discharge coefficients can increase the entrainment rate.     

数据挖掘技术在化工优化中的应用

简要介绍了数据挖掘基本概念和发展现状，综述了数据挖掘的任务、数据挖掘的常用方法和技术，重点介绍了数据挖掘在化学工业优化中的应用，对数据挖掘在化学工业优化应用中面临的挑战进行了总结，并对其发展趋势进行了预测。     

Modelling of a vacuum residue hydrocracking in an industrial slurry phase reactor

The upgradation of the bottom of the barrel has gained much interest across the refineries due to severe environmental rules, limitations of conventional oil reserves, and its flexibility to produce light end products which benefit end users. Slurry phase hydrocracking is one of the growing technologies to fulfil the increasing demand for light cut. Modelling of an industrial slurry phase reactor (SPR) for vacuum residue hydrocracking using different kinetic models is proposed. The axial dispersion model (ADM) is used for modelling an industrial SPR. The mathematical model of the reactors is incorporated for the three different lump kinetic models. This study deals with the continuous stirred tank reactor (CSTR) and SPR modelling, followed by industrial SPR modelling. The small lab-scale reactor models are validated with the experimental data reported in the literature. The study's objective was to investigate the one-dimensional and two-dimensional concentration dynamics of each lump along the axial and radial positions of industrial SPR. The vacuum residue conversion into the light fractions was obtained by more than 73% in industrial SPR. Also, the yield of vacuum gas oil and resins were evaluated as 49% and 63%, respectively. The sensitivity analysis was performed to explain the effect of process variables. The optimum range was found as a length of 15 m, liquid hourly space velocity (LHSV) of 0.2 h⁻¹, 1% catalyst concentration, and 420°C reaction temperature to enhance the throughput of the reactor.     

气力输送中供料方式的比较分析

对塑料加工中气力输送的各种供料方式的性能、特点和使用场合进行比较、分析。重点讨论了传统文丘里供料器在实际应用中存在的问题。介绍了国内外几种新型文丘里供料器的结构、特点和用途。指出采用组合式供料器，即将文丘里供料器与机械旋转式连续供料器进行组合使用，可以同时改善两者单独使用时存在的问题。     

Light and redox switchable molecular components for molecular electronics

The field of molecular and organic electronics has seen rapid progress in recent years, developing from concept and design to actual demonstration devices in which both single molecules and self-assembled monolayers are employed as light-responsive components. Research in this field has seen numerous unexpected challenges that have slowed progress and the initial promise of complex molecular-based computers has not yet been realised. Primarily this has been due to the realisation at an early stage that molecular-based nano-electronics brings with it the interface between the hard (semiconductor) and soft (molecular) worlds and the challenges which accompany working in such an environment. Issues such as addressability, cross-talk, molecular stability and perturbation of molecular properties (e.g., inhibition of photochemistry) have nevertheless driven development in molecular design and synthesis as well as our ability to interface molecular components with bulk metal contacts to a very high level of sophistication. Numerous groups have played key roles in progressing this field not least teams such as those led by Whitesides, Aviram, Ratner, Stoddart and Heath. In this short review we will however focus on the contributions from our own group and those of our collaborators, in employing diarylethene based molecular components.     

表观气速对密相气力输送流型影响的模拟研究

针对目前密相气力输送数值模拟关于流型演变方面所存在的问题,提出了一种基于颗粒所在局部空间的固相浓度及颗粒群运动特征来描述颗粒间相互作用的数学模型。该模型能够对气力输送,甚至是颗粒发生大量堆积情况下的密相输送进行数值模拟,使得长期以来缺乏有效模型对密相输送流型进行数值模拟研究的问题得到一定解决。利用该模型,对水平管中煤粉高压密相气力输送的颗粒流动过程进行了数值模拟,获得了输送过程中管道内所发生的气固两相之间的分离、沉积现象,展现了沙丘流及栓塞流等流型的演变特征,模拟结果与实验观察到的现象吻合较好,从而进一步验证了新数学模型的有效性。此外,通过对不同表观气速下固相流态分布的定量分析,揭示了输送流型变化的一些内在规律。     

Discrete element reduced‐order modeling of dynamic particulate systems

One of the key technical challenges associated with modeling particulate processes is the ongoing need to develop efficient and accurate predictive models. Often the models that best represent solids handling processes, like discrete element method (DEM) models, are computationally expensive to evaluate. In this work, a reduced‐order modeling (ROM) methodology is proposed that can represent distributed parameter information, like particle velocity profiles, obtained from high‐fidelity (DEM) simulations in a more computationally efficient fashion. The proposed methodology uses principal component analysis (PCA) to reduce the dimensionality of the distributed parameter information, and response surface modeling to map the distributed parameter data to process operating parameters. This PCA‐based ROM approach has been used to model velocity trajectories in a continuous convective mixer, to demonstrate its applicability for pharmaceutical process modeling. © 2014 American Institute of Chemical Engineers AIChE J, 60: 3184–3194, 2014     

Steuerung und Regelung von Dampfstrahlverdichtern

Operation and Control of Steam Ejectors On the basis of typical characteristics of steam ejectors the various possibilities for regulating the vacuum are discussed. It is shown that economy in steam consumption can be achieved by OZ-regulation, the savings being proportional to the fluctuating steam pressure and/or counter pressure.     

气动执行器技术现状与展望

介绍气动执行器核心部件--电／气阀门定位器、转换器的工作原理，国内外研究现状和未来发展趋势。