Analysis And Optimization To The New Near Zero Emission Coal Utilization Technology With Combined Gasification And Combustion

Coal is the main primary energy source in China, which will remains for a long time in the future. The disadvantage of traditional utilization of coal such as low efficiency and heavy pollution become more and more obvious. Consider of the current situation of our energy structure, it is necessary to exploit a new coal utilization system with higher efficiency and less pollutant emission including carbon dioxide.This thesis constructed an innovative near zero emission coal utilization system presented by Zhejiang University. It consists of six parts: coal gasification system, combustion system with carbon dioxide absorbent, solid oxide fuel cell (SOFC), deep cooling air-separation system, combustion turbine, exhaust-heat boiler and steam turbine system.This thesis builded the model of the whole system with progress simulation software ASPENPLUS, estimated the thermodynamics performance, formulated reasonable process flow and constructure. Emphasized the influence of the reaction temperature, pressure, species on hydrogen output and purity in gasifier. To the burner, examined the influence of CO₂ partial pressure on CaCO₃ decomposition, which could simulated accurately by Aspen Plus. Brought forward the optimized reaction scheme,and modified the carbon reaction ratio in gasifier. Analyzed the influence of output current and voltage on system efficiency, and discussed the oxidant sorts. Chosed a low-presure, deep-cooling air-seperation system with high-degree integration, and computed for a typical air-seperation system. Discussed the influence of main steam parameter in combined steam and gas cycle on system efficiency.At length, the whole performance efficiency is calculated,which could achieve to about 55.5%. The efficiency of the optimized system is much higher than any other coal-based thermodynamic system.