Polymers have a profound impact on the way that we live our daily lives. From various kinds of consumer packaging, like soda bottles, plastic bags, and food containers, to auto tires and manufactured industrial parts, countless polymer products enrich the world we live in. There is no doubt that rapid global development of over the last 30 years has ushered in a “golden age” for the polymer production industry, with major growth in the production and usage of polyethylene and polypropylene.
As is true in many process industries, polymerization reaction processes and procedures are complicated. Facing continuously changing business demands, rising costs of raw materials, and more intense domestic and overseas competition, many enterprises cannot meet the requirements of safe, stable, and efficient production of polymers based on current process control systems.
Advanced plants also have hidden production problems
Large-scale production environments can be daunting and complex, but they also offer opportunities to gain efficiency and improve processes with leading technology. For example, one polymer industry leader in China operates a state-of-the-art manufacturing site for polyethylene, polypropylene, styrene, butadiene, and other mainstream polymer products. One of their primary enterprise goals is to become a model of green chemistry and sustainable development in China. As a technology-driven chemical enterprise, its polymer production equipment uses the world’s newest process technologies (Hostalen ACP polyethylene and Spherizone polypropylene technologies), setting high operational and technical thresholds.
However, the reality of production can be more complicated and fraught with problems than one may expect. Since equipment needs frequent adjustment and young operators lack operational experience, there are often fluctuations in product quality. In order to enhance the core competitiveness of the enterprise, the customer sought to improve the stability of technological parameters and reduce parameter fluctuations, raising the overall standard of their capabilities.
Furthermore, for a major chemical production base in which various kinds of products are manufactured, the efficiency of grade transition is a key contributor to product quality, increases in production, and long-term operational stability of equipment. Traditional grade transitions involve complicated personnel coordination, which not only relies on manual changes and the tuning of grade parameters, but also production volume fluctuations, equipment adaptation, product form changes, and other potential uncertainties, all leading to difficulties in realizing cost reduction and increasing productivity.
Pavilion8 software contributes to great leaps in operational efficiency
In recent years, with the continuous evolution and development of modern control systems, various kinds of advanced control policies, methods, and technologies have been applied in the petrochemical industry. Compared with classic PID control, the advanced control system (APC) system centers on multivariable predictive control and features unparalleled advantages, including more powerful adaptability, robustness, and prediction features. Therefore, it is an effective tool for chemical enterprises to realize untapped potential and achieve operational excellence through increased efficiency, stabilized production equipment, and optimized product quality.
In the case of the example Chinese enterprise, the variety of prospective technology and the industry position of the company makes them careful about choosing technology partners. After a series of in-depth research studies and investigations, the customer chose Rockwell Automation’s process modeling, advanced control, and optimization software platform - Pavilion8, offering process calculations, non-linear and multivariable advanced control technologies based on its original mechanism model and statistical model to address their problems.
In terms of the implementation of basic functions, Pavilion8 software is based on a service-oriented architecture (SOA), which can easily be integrated with the current customer processes and plant infrastructures. It cannot only analyze, evaluate, and tune many PID loops; its embedded controller performance index calculations can facilitate the dynamic evaluation and long-term monitoring of the operational effects of an advanced control system for customers, guaranteeing more stable operation of assets.
With a built-in database, Pavilion8 software can model the historical actions and control curves of the controller, enabling the customer to process fault analysis quickly. Based on the unique mixed nonlinear model, the system can enable control of the whole process for polymers and whole device edge control, which effectively delivers prediction accuracy and stability of product quality. By virtue of unique Extrapolated Gain Constrained Neural Networks (EGCNN), the system can also guarantee accuracy of models beyond normal production and operation conditions, by contributing to a huge leap forward in operational efficiency.
To address the lack of operational experience among the operations staff, Pavilion8 software displays real-time trends on the web-based graphical interface, which aids operators in data-driven decision-making. Thanks to the online programming and editing functions of Pavilion8 models, customers can customize the optimized objective functions, which can be especially important for petrochemical production featuring complicated processes and process coupling. In the same respect, Pavilion8 software can also help to reduce the consumption of supplemental materials and energy to maximize the yield. These are the key points of differentiated value when using the Pavilion8 solution compared with other APC solutions.
A role model for the lean production of polymers
Today, the customer successfully implemented APC retrofitting on two sets of polymer equipment. After the project was operational, with the help of the Pavilion8 nonlinear controller and automatic grade transition software, operators only need to click on the menu and the controller can automatically start and end grade transitions as defined, while automatically recovering all grade parameters and control parameters (such as the MI, density, temperature, partial pressure of ethylene, etc.) without the need of manual changes and tuning. This not only ensures the consistency of grade transitions, shortening the transition time, but also greatly reduces labor intensity and solves untimely and unstable labor adjustment issues and other problems.
Furthermore, Rockwell Automation is known by its partners for powerful project implementation capabilities, software products and solutions, professional acumen, and business communication. The comprehensive training, commissioning, and delivery services make put customers at ease. With the success of this project, the customer plans to migrate the solutions to other polymers and chemical devices at a future date.
Rockwell Automation has accumulated rich experience in the field of polymers, which has led to success in this project, just as with many previous projects. As early as 1995, Rockwell Automation had successfully implemented an APC project with early-model polymer equipment and has upgraded more than 160 advanced control systems, more than 200 polymerization reactors in total to-date, which cover almost every known kind of polymerization technique and catalyst type. The leading polymer APC solution provided by Rockwell Automation also plays a key role in the production plants of many leading polymer enterprises.
The solution for APC systems can not only use a nonlinear model to control the polymerization reactors of different grades of products, but also implement the advanced control of squeezing granulators and polymer bins, providing multiple levels of insurance for product quality, yield, and conversion rate. According to statistics, the implementation of similar projects can improve KPIs as follows:
- Reduce fluctuations of equipment by 30–50%
- Reduce fluctuations of product quality by 30–70%
- Increase yield by 2–8%
- Decrease average grade transition time by 20–50%
- Decrease off-grade products by 2–5%
- Availability is greater than 95%
As one of the largest production-capacity petrochemical plants in China, the successful implementation and deployment of the APC solutions for the customer is a point of pride for Rockwell Automation as a service and technology provider. With powerful technical advantages and rich project experience, Rockwell Automation is equipped to help customers look to the future, empowering their digital transformation journey and giving increased visibility and control to petrochemical customers through digital and intelligent solutions.
