化工系统工程讲座(四)

<正> 在第二讲中已经指出,过程系统分解的目的主要是识别过程网络系统中全部封闭的再循环回路,选择适当的物流,将其切断后使整个网络系统断开,构成一个树的结构,并给出一个最优的迭代程序。但是,由于一个化工过程中,单元过程和设备多,物料流和能量流来回串接,构成各种再循环回路以及过程变量的多值性,用数学语言来说,一个过程系统实际上     

集成化工过程模拟系统的建立和应用

集成化工模拟系统的意义在于使化工过程的概念设计(包括摸拟、控制、设备估计、经济分析和评价等)实现一体化,这就要求系统在结构上更具有通用性和灵敏性。本文首先对集成模拟系统软件设计进行了描述,给出了系统的数据结构及框架;其次,介绍了这样一个集成模拟系统的模型软件及其应用;最后,讨论了今后该模型系统在几个主要方面的发展前景。     

混和过程的工业放大

混和是化学工业中常见的化工单元操作,在化工过程开发中经常会遇到混和过程的工业放大,混和过程工业放大的好坏直接影响到产品的质量,设备的生产能力和厂家的经济效益,由于混和过程的工业放大失败可能会导致整个工厂无法正常运行,因此,对混和过程的工业放大进行分析探讨,有一定的工业现实意义。     

全国首届化工单元过程及设备技术交流暨展览会将于九月在沪举行

全国首届化工单元过程及设备技术交流暨展览会将于九月在沪举行在化工科技开发工作中，各种化工单元过程及设备的研究开发及工程放大具有重要意义。＂八五＂以来，各高等院校、科研设计单位和化工企业已开发出一批成龙配套、行之有效的化工单元过程及设备成果，并成立了一...     

化工单元操作和过程的系统层次结构

阐述了化工单元操作和过程的系统层次结构。化工单元操作是系统的要素,经过组合形成化工过程(工段)——低层系统,若干化工过程(工段)再经组合形成工艺流程——高层系统;构成工艺流程的化工过程之间相互有一定的联系,具有一定的系统层次结构。     

双乙烯酮生产中醋酸回收工艺的节能改造

通过对以往的醋酸回收生产工艺的调查分析,从工艺、化工单元操作设备、化工过程系统等方面提出的节能改造,一方面使系统更稳定,另一方面减少了能源的浪费。     

电子计算机在化学工业中的应用(二)

1.化工流程的物料及热量平衡计算将化工流程计算分解为基本的单元操作问题,并分别建立一些通用的数学模型作为该系统的结构单元,其中每一种单元完成某一种特定的单元操作计算。根据计算要求,按照一定的次序,把相应的短小简单的结构单元连接起来,便可形成所要求的化工流程模型,再结合必需的计算参数、物流数据及物性数据,便可在计算机上进行化工流程的计算。这种计算机算法系统称为化工流程模拟系统,这个方法的优点是:当编写好了基本的结构单元程序模块以后,便可非常简单地组成任何复杂流程的工艺过程。借助于这些流程     

单元操作的过程强化

过程强化研究渐成热点,过程技术和设备是化工过程强化的两个方面。单元操作是化工过程基本操作,其过程的强化对化工过程有较大的影响。本文综述了化工原理课程中各主要单元操作的过程强化。     

化工单元仿真课程中安全生产的教学实践

以离心泵单元仿真培训系统为例,通过模拟离心泵的开车、停车、正常运行和各种事故现象处理,重点描述了设备缺陷和人为因素等安全问题在化工单元仿真课程中的体现。通过化工单元仿真培训,不仅提高了培训人员对工艺过程参数控制的能力,还增强了化工生产的安全工作意识。     

基于GLSAFIS的氟化工过程操作单元可靠性监测

氟化工产物的剧毒特性,使得对于氟化工过程设备的运行可靠性监控异常重要。为此,提出了基于全局-局部结构分析的模糊推理系统（GLSAFIS）在线评估氟化工过程操作单元运行可靠性。依据氟化工工艺流程选取操作单元过程变量后,通过全局-局部结构分析算法（GLSA）对操作单元过程变量进行全局-局部特征提取。这些低维的全局-局部特征代替原始变量作为模糊推理系统（FIS）的输入,不仅可以克服噪声的影响,降低对专家知识的依赖,同时可以通过特征空间的降维压缩,大大加速后续模糊推理系统的逻辑设计。最后模糊推理系统的实施,使得本方法可以对化工过程操作单元可靠性进行在线评估。国内某氟化工厂二氟一氯甲烷（R-22）生产过程的实际应用以及田纳西伊斯曼模拟过程的仿真结果均证实了所提方法可以准确地反映实际化工过程操作单元的运行状况,大大提高了对实际化工过程的安全监控力度。     

论化工过程的节能

本文分析了我国能源形势,从化工热力学定律着手,强调节能的原理和意义。化工过程以及化工设备涉及诸多节能问题,教学中结合化工原理知识,通过化工设备节能以及余热的回收利用,阐述了化工过程的节能技术。目前,节能已从单个的单元操作发展到过程系统,过程集成最终目标是使得设计的过程效率最高即实现多目标最优设计。     

Integrated Modelling of Process Operation Systems Using the Agent‐Oriented Approach

For the past years, several software and computer tools have been developed to aid the chemical process operations including real‐time simulation, on‐line optimization, fault diagnosis, process monitoring, and many other functions. These tools were designed separately and did not collaborate efficiently, making it difficult to integrate different engineering tasks for the optimal process operation. In this paper, an agent‐oriented modelling approach is presented to address this problem. Elements in the process operation systems are divided into two classes. One class consists of equipment, units and processes, while the other class consists of production operation tasks. The two classes of elements are modelled as objects and agents, respectively. Then, three strategies are presented to implement the integration of the whole process operation system, which are integration of object models, integration of agent models and supervision of operator. Also presented is a case study of integration of process operation decision optimization and abnormal situation management using the proposed agent oriented approach for TE challenge problem.     

煤化工产品加工流程模拟系统CCPS的设计与实现

结合煤化工产品工艺特点,建立了此过程的热力学计算方法和单元设备数学模型,开发了煤化工产品加工流程模拟软件ＣＣＰＳ,并对焦油闪蒸及初馏生产工艺流程进行了模拟运算,计算结果与现场数据吻合。     

化工过程系统集成建模的面向智能体方法

引　言化工过程系统中常用的建模方法是结构化分析方法和面向对象方法 .面向对象方法较好地克服了结构化方法按功能将系统分解的缺点 ,但对化工生产过程的故障诊断、模拟优化、排产等具有主动性的事物采用对象来描述具有一定的缺点[1] .因此 ,在面向对象方法的基础上提出了面向     

A safe-parking framework for plant-wide fault-tolerant control

This work addresses the problem of handling actuator faults in a chemical plant. We consider a multi-unit nonlinear process system subject to input constraints and actuator faults in one unit that preclude the possibility of operating the unit at its nominal equilibrium point. The interconnected nature of the units in a plant brings forth unique opportunities as well as challenges that simply do not exist when handling faults in isolated units. In particular, the fact that the outlet streams from a faulty unit go through subsequent (well functioning) units raises the possibility of better restricting the effects of the fault to the faulty unit. At the same time, handling a fault in a unit may necessitate appropriate action in the downstream unit, which is not a result of a fault in the downstream unit. To address such issues that arise when handling faults in chemical plants, in this work we present a safe-parking framework (we define, in a previous work on handling faults in isolated units, a safe-park point as an operating point where in the event of a fault, a unit can be operated in a way that prevents onset of hazardous situation and allows smooth resumption of nominal operation) for plant-wide fault-tolerant control. We first consider the case where there exists a safe-park point for the faulty unit such that the effect of safe-parking can be completely rejected (via changing the nominal values of the manipulated variables) in the downstream unit. Steady-state as well as dynamic considerations (including the presence of input constraints) is used in determining the necessary conditions for safe-parking the multi-unit system. We next consider the problem where no viable safe-park point for the faulty unit exists such that its effect can be completely rejected in the subsequent unit. A methodology is presented to simultaneously safe-park the consecutive units. Finally, we incorporate performance considerations in the safe-parking framework and illustrate the implementation of the safe-parking framework using a multi-unit chemical reactor system.     

面向对象方法在化工过程控制系统设计中的应用研究

通过分析传统软件设计方法在化工控制系统软件设计中的不足,从面引入面向对象方法,包括面向对象分析和面向对象设计。在给出计算过程控制基本模型之后,以化工过程控制为例,给出了其中一些对象类的Ｃ＋＋描述。     

Design standardization of unit operations for reducing the capital intensity and cost of small-scale chemical processes

A methodology is proposed to reduce the cost and capital intensity of small-scale chemical processes by creating new opportunities for economies of numbers through standardizing the equipment designs across multiple processes. We depart from asynchronous design of single-processes and adopt a common-functionality based simultaneous design of multiple processes that use similar unit operations. A generalized cost function is used to appropriately balance the trade-offs between economies of scale and economies of numbers. An optimization-based framework for design standardization is developed and illustrated using two case studies. The first involves the simultaneous synthesis of methanol and ammonia processes, and the second addresses the optimal synthesis of multi-column natural gas liquid (NGL) fractionation processes for different natural gas sources. We observe that considerable reduction in capital intensity of small-scale processes is possible through equipment standardization.     

煤基合成气一步制备高纯度二甲醚的全流程建模与模拟

As a result of shortage supply of oil resources, the process for the alternative coal-based fuel, dimethyl ether (DME), has emerged as an important process in chemical engineering field. With the laboratory experiment data about DME synthesis and separation, the production process for DME with high purity is proposed when one-step synthesis of DME in slurry bed reactor from syngas is adopted. On the basis of experimental research and process analysis, the proper unit modules and thermophysical calculation methods for the simulation process are selected. Incorporated the experimentally determined parameters of reaction dynamic model for DME synthesis, regression constants of parameters in non-random two-liquid equation (NRTL) model for binary component in DME separation system with built-in properties model, the process flowsheet is developed and simulated on the Aspen Plus platform. The simulation results coincide well with data obtained in laboratory experiment. Accordingly, the accurate simulation results offer useful references to similar equipment design and process operation optimization.     

振荡流发生装置应用研究进展

振荡流反应器是一种新型的化工设备。由于其独特的流动特点,能够强化许多化工过程,在化工生产中具有广泛的应用前景。文章介绍了振荡流反应器在设备结构、流场特点及停留时间特性等方面的基础研究以及它在发酵、生物反应器、絮凝、颗粒悬浮领域的应用状况。