CFB PROCESS ANALYSIS AND CONTROL SYSTEM DEVELOPMENT WITH MODERN SIGNAL PROCESSING AND PILOT CFB REACTOR

摘要

In the future, fluctuations in electricity consumption will increase. This sets new demands for control systems of boilers. The development of a high efficiency CFB power plant (once through steam cycle with supercritical steam values) and the use of alternative fuels require advanced methods of control and knowledge of the dynamic behaviour of the furnace and combustion process. New approach and tools are needed in developing and optimizing the CFB technology considering emissions, combustion process and furnace scale-up. Also in the future, information from process measurements must be utilized more effectively in optimisation and monitoring of the process. There is a lot of information that can be extracted from process measurements by utilizing different signal processing methods. This information can then be applied to process monitoring and control. A prototype for the signal processing tool has been developed, enabling the user to evaluate the results of different analysis techniques in an easy, graphical, and exact way. In order to develop control system performance, a new method to improve flue gas oxygen control is introduced. The method is based on models and analysis of the fluctuation of flue gas oxygen concentration. Fluctuation of oxygen concentration depends on fuel and air feeds and combustion. An estimate for fuel reactivity can be calculated in existing process conditions based on fluctuation in order to apply it to combustion control e.g. during load changes.