We have developed a process model to simulate the behavior of an industrial-scale pressurized Lurgi fixed-bed coal gasifier using Aspen Plus and General Algebraic Modeling System(GAMS). Reaction characteristics in the...We have developed a process model to simulate the behavior of an industrial-scale pressurized Lurgi fixed-bed coal gasifier using Aspen Plus and General Algebraic Modeling System(GAMS). Reaction characteristics in the fixed-bed gasifier comprising four sequential reaction zones—drying, pyrolysis, combustion and gasification are respectively modeled. A non-linear programming(NLP) model is developed for the pyrolysis zone to estimate the products composition which includes char, coal gases and distillable liquids. A four-stage model with restricted equilibrium temperature is used to study the thermodynamic equilibrium characteristics and calculate the composition of syngas in the combustion and gasification zones. The thermodynamic analysis shows that the exergetic efficiency of the fixed-bed gasifier is mainly determined by the oxygen/coal ratio. The exergetic efficiency of the process will reach an optimum value of 78.3% when the oxygen/coal and steam/coal mass ratios are 0.14 and 0.80, respectively.展开更多
Attrition resistance in an adsorbent is one measure of its mechanical strength.It quantifies its ability to resist the impact of frictional forces generated in a milieu where hydrodynamic agitation exists.However,attr...Attrition resistance in an adsorbent is one measure of its mechanical strength.It quantifies its ability to resist the impact of frictional forces generated in a milieu where hydrodynamic agitation exists.However,attrition resistance has been only sporadically examined in adsorbents used to remove aqueous adsor-bates.Since attrition is relevant in aqueous adsorption process design,this review discusses the quan-tification of attrition resistance,variability in loss due to attrition across adsorbents,and the implications of attrition on adsorption systems.Finally,some key research opportunities that could be explored for a better understanding of attrition in real-scale water purification are presented.It is inferred that sub-stantial research and development still needs to be accomplished to better understand the attrition resistance-adsorbent behavior within real-scale aqueous adsorption environments.The results can be harnessed to design and produce more robust,efficient and cost-effective adsorbents.展开更多
基金Supported by the National Basic Research Program of China(2012CB720500)the National Natural Science Foundation of China(U1162121)
文摘We have developed a process model to simulate the behavior of an industrial-scale pressurized Lurgi fixed-bed coal gasifier using Aspen Plus and General Algebraic Modeling System(GAMS). Reaction characteristics in the fixed-bed gasifier comprising four sequential reaction zones—drying, pyrolysis, combustion and gasification are respectively modeled. A non-linear programming(NLP) model is developed for the pyrolysis zone to estimate the products composition which includes char, coal gases and distillable liquids. A four-stage model with restricted equilibrium temperature is used to study the thermodynamic equilibrium characteristics and calculate the composition of syngas in the combustion and gasification zones. The thermodynamic analysis shows that the exergetic efficiency of the fixed-bed gasifier is mainly determined by the oxygen/coal ratio. The exergetic efficiency of the process will reach an optimum value of 78.3% when the oxygen/coal and steam/coal mass ratios are 0.14 and 0.80, respectively.
文摘Attrition resistance in an adsorbent is one measure of its mechanical strength.It quantifies its ability to resist the impact of frictional forces generated in a milieu where hydrodynamic agitation exists.However,attrition resistance has been only sporadically examined in adsorbents used to remove aqueous adsor-bates.Since attrition is relevant in aqueous adsorption process design,this review discusses the quan-tification of attrition resistance,variability in loss due to attrition across adsorbents,and the implications of attrition on adsorption systems.Finally,some key research opportunities that could be explored for a better understanding of attrition in real-scale water purification are presented.It is inferred that sub-stantial research and development still needs to be accomplished to better understand the attrition resistance-adsorbent behavior within real-scale aqueous adsorption environments.The results can be harnessed to design and produce more robust,efficient and cost-effective adsorbents.
