Modeling of dynamic properties of the combustion system of a circulating fluidized bed boiler

According to the profile of the solid suspension density along the height of the furnace which is obtained by many hot test measurement in different operating conditions, a hydrodynamic model is developed, and on the basis of this, a "three zones" heat transfer model is presented to calculate the heat transfer coefficient (HTC) of the circulating fluidized bed (CFB) boiler, furthermore, with dynamic balance equations, a mathematical model is formed to study the dynamic properties of the combustion system. Through simulation, for each zone, this paper works out follow responses: exit temperature responses, carbon mass fraction responses and oxygen concentration responses to step change in fuel feed rate, in primary air feed rate and in secondary air feed rate, and also pressure drop of bed material to step change in above rate are given. Some of these achieved responses fit well with the corresponding experimental results.