Simulation And Optimization Of IGCC-methanol Polygeneration System Based On Coal Gasification

The IGCC-methanol polygeneration systems were simulated using Aspen Plus software. Energy saving of IGCC-methanol polygeneration system was analysed.An improved one-dimensional steady-state model for an entrained flow coal gasifier was developed in this thesis.In order to evaluate the configurations of the IGCC-methanol polygeneration system based on entrained-bed pulverized coal gasification, the polygeneration systems were simulated using Aspen Plus software. Different configurations, including waste heat boiler process/quench process and series/parallel combination of IGCC and methanol synthesis were evaluated by caculating the relative energy saving ratio.The results show that the waste heat boiler process is more energy-efficient than the quench process. For the parallel polygeneration systems with waste heat boiler process, the relative energy saving ratio increases when the proportion of the synthesis gas to methanol side increases. For the series polygeneration systems with waste heat boiler process, the relative energy saving ratio increases when the proportion of cycle gas increases in the methanol synthesis process. Based on allocation of energy, coal consumption of methanol synthesis and power generation of the IGCC-methanol parallel system with waste heat boiler process were calculated respectively.Because the one-dimensional model is reasonable simplified and its computing speed is very fast,it is suited to be used in the simulation study of polygeneration systems.In this study, an improved one-dimensional model for entrained flow coal gasifier was built by considering kinetics of heterogeneous and homogeneous reactions and residence time distribution of particles. This model includes the coal pyrolysis and volatile combustion subroutine, gasification subroutine and heat balances subroutine.The temperature and composition of the syngas of the coal gasifier, the distribution of gas composition,temperature and carbon conversion of particles was caculated by using the model. The effect of coal type and particle diameter on the the distribution of gas composition,temperature and carbon conversion was analysed.