کنترل کیفیت پروسه های تولید پلیمر
|کد مقاله||سال انتشار||مقاله انگلیسی||ترجمه فارسی||تعداد کلمات|
|4566||2000||14 صفحه PDF||سفارش دهید||5320 کلمه|
Publisher : Elsevier - Science Direct (الزویر - ساینس دایرکت)
Journal : Journal of Process Control, Volume 10, Issues 2–3, April 2000, Pages 135–148
For the polymer production industries, the competitive edge will come from the technology that excels in controlling the polymer properties in a consistent way over the entire plant and in maximizing the production performance while keeping safety regulations. Based on the experience in applying advanced process control and scheduling schemes to industrial polyolefin polymerization plants, the state of the art in quality control systems for providing the polymer production plant with an enlarged capacity for product discrimination and flexibility is reviewed. On-line soft-sensing and optimal grade changeover control problems are the main focus of this paper. A quality control system for polymer production plants, which integrates optimal control with on-line sensing and scheduling techniques, is discussed making reference to an application of a prototype system to an industrial plant.
Use of polymers has been growing steadily in many industrial fields, such as automobile, food, apparel, electronics, etc. In the US, a fivefold growth of plastics in two decades (1974–1994) was reported . It was attained by exploring new and various plastic applications. Polypropylene (PP) is now used for almost all automobiles. Soft drink bottles made of PET (polyethylene terephthalate) have almost completely superseded glass bottles, and PE (polyethylene) plastic bags have replaced the paper bags at grocery stores. Consumers are learning that many plastic products are made from the same polymer. For example, PP used for a core material of instrumentation panel of cars is also used for car batteries, indoor–outdoor carpeting, and polyolefin intimate apparel. For each use, specific properties of the polymer are needed. In order to meet these demands, the polymer industries are producing many different grades of high quality polymers. In recent years, the pressure from customers for greater grade variation and product diversification has been growing while specification of polymer quality becomes increasingly severe. For the future polymer industries, the competitive edge will come from a technology that excels in tailoring polymer properties and in controlling production plants toward maximizing product quality as well as production performance and safety. In this paper, the state of the art in quality control systems for polymer production processes is discussed, based on the experience of joint university–industry projects in applying advanced process control and scheduling schemes to industrial polyolefin polymerization plants. A significant amount of research has been done in the area of control, monitoring, and modeling of polymerization reactors, and excellent reviews have also been given by several researchers , , ,  and . Because of the authors’ bias and space limitation, this paper could not cover every important issue addressed in the past. On-line soft sensing and optimal grade changeover control are mainly focused on this paper. One of the issues discussed throughout this paper is plant-wide total quality control with design of molecular structure at microscale to macroscale levels: The polymer production plant does not consist only of reactor(s). It consists of reactor(s), separator(s), dryer(s), extruder(s) and blending tank(s). Therefore, quality of the polymer is affected not only by reactors' operation conditions but also by extruding and blending operations. In addition, polymer properties are determined by low-order and high-order molecular structures of the polymer. Thus, to provide the production plant with an enlarged capacity for product discrimination and flexibility, the polymer properties should be controlled on each molecular structure level in a consistent way throughout processing history — from reactors to separation units, extruders, and to blending tanks. A scheme of quality control system for polymer production plants, which integrates optimal control with on-line sensing and scheduling techniques, is discussed making reference to an application of a prototype system to an industrial plant.
نتیجه گیری انگلیسی
As discussed, quality control of a polymer plant is a very important and active area for future research. To attain the highest quality control in the production plant, it is indispensable to integrate technologies in three key areas, process control, sensing, and optimization, and to create an intelligent manufacturing system supervising the entire plant. The most important factor in developing such a system is quality modeling. Without it, practical quality control cannot be achieved.