Simulation Research Of CO₂?1?/Low Rank Coal Slurry Gasification System Based On Aspen Plus

Under the background of demand to steady energy supply and low carbon emission in China,the technology of coal water slurry?CWS?gasification has been considered as an effective clean coal technology.It has been widely studied and used recently.The reserve of LRC?low rank coal?reaches more than 50 percent of the gross reserve in China.It is suitable to be converted into gas by CWS gasification process.However,the solid concentration of CWS and gasification efficiency are very low for LRC.Compared to CWS,Liquid CO₂?CO₂?1??slurry has lots of advantages,such as low latent heat of vaporization,ability to improve the dispersion of the coal in the gasifier,comparatively high concentration of coal slurry and less CO₂ emissions.Therefore,CO₂?1?slurry is suitable for LRC gasification.This work focus on the simulation of LRC-CO₂?1?slurry gasification in Aspen Plus.This would provide a theoretical basis for the applications of LRC gasification.Firstly,an Aspen Plus model for simulation of the gasification of LRC-CO₂?1?slurry was developed.The laboratory experimental results were used to validate this model.Then,the influence of different parameters on gasification reaction were mainly performed,such as coal characteristics,the ratio of oxygen to coal,concentration of CO₂?1?slurry,pressure and different ratio of H₂ O to CO₂,and so on.Finally,comparion analysis between LRC-CO₂?1?slurry and CWS for an IGCC system were further studied.It can be seen from the results that temperature in the gasifier increased with rising of O₂/coal.O₂/coal also significantly influenced the composition of syngas.The concentration of CO and H₂ in syngas rose with O₂/coal and then decreased when O₂/coal exceeded 0.72.CO and H₂ content in syngas increased at higher concentration of LRC-CO₂?1?slurry,the temperature in gasifier also increased accordingly.The concentration of the slurry should be set at about 60%.When O₂/coal and slurry concentration were all taken into consideration,the best operating conditions appeared at 0.74 of O₂/coal with 60% slurry concentration.Pressure in the gasifier didn't significantly affect the gasification procedure.When H₂ O was used to replace part of the CO₂,higher H₂O/CO₂ led to more H₂ content in syngas,while the percentage of CO went to opposite tendency more rapidly.Wide range of H₂/CO could be expected,which offered a flexible adaptivity according to the different demands.Besides,the emission of CO₂ also reduced.Simulation research of the IGCC system in Aspen Plus was conducted.It was found that LRCCO₂?1?slurry could greatly enhance the usage of the LRC.The IGCC system reached to a higher carbon conversion rate and net effiency when using LRC-CO₂?1?slurry.Furthermore,the amount of water consumption,CO₂ emission and energy consumption decreased.The results show that great economic and environmental benefits will be accomplished by the introduction of LRC-CO₂?1?slurry in IGCC system.