Enhancing peak shaving capability of supercritical carbon dioxide(S-CO_2) boiler is the key to realize flexible operation of S-CO_2 coal-fired power plants. Research on dynamic characteristics of S-CO_2 boiler is beneficial to optimize the boiler operation control strategies. A dynamic simulation model of S-CO_2 boiler is established by the principles of thermodynamics and heat transfer based on the boiler of a 5 MW S-CO_2 cycle power unit designed and built by Xi'an Thermal Power Research Institute

and the reliability of the model is validated with operational data from unit. Based on the simulation model

dynamic characteristics of the above S-CO_2 boiler under step disturbance of different boundary conditions

such as fuel flow rate

working fluid flow rate

and working fluid temperature

are analyzed. The results show that

the S-CO_2 boiler has large thermal inertia

stability times of working fluid temperature at the boiler outlet are different under disturbance of different boundary conditions.With the increase of disturbance range of boundary conditions

stability times become longer. With the increase of boiler heat load

the working fluid pressure at the S-CO_2 boiler outlet decreases

and the working fluid flow rate at the S-CO_2 boiler outlet increases instantaneously in the initial stages of a dynamic process.