Modeling And Simulation Study Of 35MW_th Oxy-fuel Combustion Air/Gas System

The oxy-fuel combustion technology has great advantages in aspects like capturing CO₂ easily on large scale, relatively low capturing cost, controllable pollutant emission and plenty reformable power plants. All of these preponderances make it a hot research spot in field of carbon abatement. Distinct from conventional power station, the oxygen-enriched power plant’s air/gas system has different technical processes. Study of flue gas characteristic parameters and air/gas system manipulation over above processes is an important preparatory work for the widely application of oxygen-enriched combustion technology in the future.Firstly, the main features of oxy-fuel combustion technology, parameter monitoring requirements and air/gas system technical processes’ experimental principles on basis of laboratorial actual operation were elaborated in this paper. Then, regarding 35 MWth oxy-fuel combustion power station’s air/gas system as the object, a steady-state Excel calculation model and a dynamic simulation model using Simulink were built from the perspective of mechanism modeling and rational simplification. With experimental datas as model input, the model accuracy was verified after comparing simulation results with measured values from DCS.Through model simulation, impacts of factors like system loading, air leakage, dewaterability, air distribution and oxygen injection methods on flue gas amount, its component properties and manipulation of air/gas system were to explore and study. Over the time of establishing steady-state model, the variables involved and interaction between various parameters during model debugging can provide basis for measuring point arrangement and instrument selection of related runing parameters of oxy-fuel combustion air/gas system.Gathered parameter method was used in dynamic model to simplify the actual air/gas system facilities. Some submodules like flue gas temperature and pressure calculation module, radiation heat transfer module and single-phase medium heat transfer module were consisted in the dynamic model which could be applied to investigate the changing process of model flue gas side temperature, pressure and heat exchange under disturbances such as coal-powder input, air supply volume or its temperature, system loading increasing or decreasing. Based on the built model, a simple PID regulator was added to explore dynamic response characteristics and flue gas temperature adjustment performance of the model system which could provide a well basis for subsequent running parameter adjustment and optimization.The content of research in this paper is an important part of basic theory and operation control study of oxy-fuel coal-fired power plant’s air/gas system, which can be referred during actual operational control of real oxygen-enriched air/gas system.