Simulation Modeling And Dynamic Characteristics Of Oxy-Combustion Circulating Fluidized Bed Boiler

Oxy-CFB technology combines the advantages of the oxygen enriched combustion and circulating fluidized bed,it is the most prominent representative of C02 capture and storage technology(CCS)has been well acknowledged as one of the most promising C02 mainstream capture technologies by the industry and academia.In this paper,a 330MW circulating fluidized bed(CFB)boiler in a power plant is studied.On the gCCS simulation platform,the overall dynamic simulation model of CFB boiler and Oxy-CFB boiler are established respectively.The dynamic characteristics of Oxy-CFB boiler and the simulation of the combustion mode switching process are studied.The main research contents include:Firstly,according to the law of conservation of mass and energy,establishing the equilibrium equation of Oxy-CFB boiler's combustion system,steam water system and some other sub processes and integrating these sub models to establish the overall dynamic mathematical model of Oxy-CFB boiler followed.The thermal system of boiler is studied deeply,which provides a theoretical basis for Oxy-CFB boiler simulation modeling.Secondly,based on the dynamic mathematical model of Oxy-CFB boiler,according to the idea of block modeling,the simulation model of 330MW concept Oxy-CFB boiler subsystem is established on the gCCS simulation platform.The input and output interfaces of each module are specified,and each sub model was packaged.According to the boiler system and equipments structure,the flow of working medium and the law of flue gas flow,connecting each sub module,the core simulation model of Oxy-CFB boiler is established.Then,combining with the original module of gCCS,the whole simulation model of Oxy-CFB boiler is built.Furthermore,based on the simulation model,the boiler parameter setting and model debugging are carried out.The overall simulation results of CFB boiler are compared with the field test data.The steady state and dynamic verification are carried out to validate the accuracy of the model,and simulation results reliability.Finally,based on the simulation model of Oxy-CFB boiler,the step disturbance of input variables are simulated,and the dynamic characteristics are analyzed.In addition,from the researched combustion mode switching of the Oxy-fuel boiler,the influence of the main process variables vary with constant rate on the switching process are analyzed.The drawbacks of this method are analyzed,and the simulation of the main process variables with different change rates are carried out.The simulation results show that this method makes the switching process more stable and the boiler is more safe and reliable,so it can be used to guide the design,manufacture and operation of Oxy-CFB boiler.