MODEL PREDICTIVE CONTROL AND REAL-TIME OPTIMIZATION FOR CHEMICAL LOOPING PROCESS

摘要

Alstom Power Inc. (Alstom) is developing a breakthrough "zero emission" low cost, high efficiency technology for the global energy market. This new power plant concept is based on a process utilizing high temperature chemical and thermal looping technology. The Limestone Based Chemical Looping Combustion (LCL-C) technology can be configured as a next generation power plant with a controlled stream of CO_2 for use or sequestration. Because of the complexity of the technology, Alstom is developing advanced controls and optimization solutions for the chemical looping system. An R&D project on dynamic simulation and advanced controls was executed under a DOE advanced research project co-sponsorship between 2007 and 2012. Alstom's R&D efforts were placed on dynamic modeling and simulation analysis, facility testing of new sensors and controls, and application of Model Predictive Controls (MPC) and Real-Time Optimization (RTO) to the chemical looping process. The University of Illinois supported Alstom with its advanced controls research focused on wavelet based model complexity reduction and PDE based control design and analysis during the initial stage of the development. A key part of this project was the development of a new computational approach to process dynamic simulations for use in the controls development. The controls development initially focused on developing an understanding of the basic transport processes and the underlying process control dynamics. The effort included characterization of the chemical looping process, building solids transport process math models, and developing offline and real-time dynamic simulation software to support control investigations. These first-of-a-kind (FOAK) dynamic simulators in conjunction with Alstom's experimental facilities were used to explore advanced controls concepts such as Model Predictive Control for application to the chemical looping process. Most recently, Alstom's 3MWth prototype scale LCL-C facility in Connecticut, was used as the reference to investigate scale-up modeling, simulation and control specification development. This paper presents Alstom's research and development to demonstrate concepts of MPC and RTO applications to its chemical looping process. The LCL-C technology background and development status is provided. Then, the technical approach to first principle modeling of a multi-loop reaction flow dynamic simulation model, including: model discretization, and software and numerical simulation development, is presented. The simulation results and numerical problems resolved during the computational studies are presented at a proper technical level. Next, the design and test results obtained on Linear MPC (LMPC) as well as simulation results on Nonlinear MPC (NMPC) are shared. Further, plant level Real-Time Optimization (RTO) is introduced using a preliminary RTO example incorporating steady-state chemical looping model. It is pointed out that advanced controls operational optimization has been established as a key enhancement for the chemical looping process based power generation plant with carbon capture for utilization and sequestration. Finally, the future plan for the development of integrated control and optimization along with Alstom's Chemical Looping technology development for clean fossil power is outlined.