Steady And Dynamic Simulation Of The Single Nozzle Pulverized Coal Gasifier Of Entrained-Flow

The current study is motivated by a desire to establish steady state and dynamic simulation models of single nozzle pulverized coal gasifier based on the partition concept, and the influencing factors of gasification have been investigated. The detailed contents are as follows:(1) Based on the three-region model and short-circuit model of single nozzle entrained-flow gasifier, the internal space of a gasifier has been divided into combustion region, jet flow secondary reaction region, recirculation secondary reaction region and plug flow secondary reaction region. The primary homogeneous reactions have been calculated by Gibbs equilibrium model while the secondary homogeneous reactions and all heterogeneous reactions have been calculated by kinetic model.The simulation results show temperature distribution and composition of each region, and the gasification results agree well with those of Gibbs equilibrium model; according to the appropriate temperature range of the gasifier, the partition model has predicted the optimal oxygen-coal ratio and steam coal ratio.Based on the partition model, the influence of recirculation ratio, short circuit ratio and particle mean diameter on gasification have been studied.(2) Based on the partition model above mentioned, the control system of gasifier has been established in Aspen Dynamics. The dynamic responses of the variables which include flowrate of oxygen, steam and carriergas, temperature and composition of outlet syngas, temperature and mass holdup of each region under control of PID controllers have been studied. The responses have kept the stable operation and technic indexes of the gasifier. This aspect of study has laid a good foundation for the development of advanced control scheme.