Flow property of coal ash and slag is an important parameter for slag tapping of entrained flow gasifier.The viscosity of slag with high contents of calcium and iron exhibits the behavior of a crystalline slag,of whic...Flow property of coal ash and slag is an important parameter for slag tapping of entrained flow gasifier.The viscosity of slag with high contents of calcium and iron exhibits the behavior of a crystalline slag,of which viscosity sharply increases when temperature is lowered than temperature of critical viscosity(TCV).The fluctuation in temperature near the TCVcan cause an accumulation of slag inside the gasifier.In order to prevent slag blockage,it is necessary to adjust the ash composition by additive to modify the flow property of coal rich in calcium and iron.Main components of coal gangue are Al_(2)O_(3) and SiO_(2),which is a potential additive to modify the ash flow properties of these coals.In this work,we investigated the ash flow properties of a typical coal rich in calcium and iron by adding coal gangue with different SiO_(2)/Al_(2)O_(3)ratio.The results showed that the ash fusion temperatures(AFTs)firstly decreased,and then increased with increasing amount of coal gangue addition.Chemical composition of coal ash rich in calcium and iron moved from gehlenite primary phase to anorthite,quartz and corundum primary phases.The slags with coal gangue addition behaved as a glassy slag,of which the viscosity gradually increased as temperature decreased.Besides,a high SiO_(2)/Al_(2)O_(3)ratio of coal gangue was beneficial to modify the slag viscosity behavior.Addition of coal gangue with a high SiO_(2)/Al_(2)O_(3)ratio impeded formation of crystalline phases during cooling.This work demonstrated that coal gangue addition was an effective way to improve the ash flow properties of the coal rich in calcium and iron for the entrained flow gasifier.展开更多
One of the crucial issues in modern ash chemistry is the realization of efficient and clean coal conversion.Industrially,large-scale coal gasification technology is well known as the foundation to improve the atom eco...One of the crucial issues in modern ash chemistry is the realization of efficient and clean coal conversion.Industrially,large-scale coal gasification technology is well known as the foundation to improve the atom economy.In practice,the coal ash fusibility is a critical factor to determine steady operation standards of the gasifier,which is also the significant criterion to coal species selection for gasification.Since coal behaviors are resultant from various evolutions in different scales,the multi-scale understanding of the ash chemistry is of significance to guide the fusibility adjustment for coal gasification.Considering important roles of molecular simulation in exploring ash chemistry,this paper reviews the recent studies and developments on modeling of molecular systems for fusibility related ash chemistry for the first time.The discussions are emphasized on those performed by quantum mechanics and molecular mechanics,the two major simulation methods for microscopic systems,which may provide various insights into fusibility mechanism.This review article is expected to present comprehensive information for recent molecular simulations of coal chemistry so that new clues to find strategies controlling the ash fusion behavior can be obtained.展开更多
基金supported by the Fundamental Research Funds for the Central Universities(2017CXNL04)。
文摘Flow property of coal ash and slag is an important parameter for slag tapping of entrained flow gasifier.The viscosity of slag with high contents of calcium and iron exhibits the behavior of a crystalline slag,of which viscosity sharply increases when temperature is lowered than temperature of critical viscosity(TCV).The fluctuation in temperature near the TCVcan cause an accumulation of slag inside the gasifier.In order to prevent slag blockage,it is necessary to adjust the ash composition by additive to modify the flow property of coal rich in calcium and iron.Main components of coal gangue are Al_(2)O_(3) and SiO_(2),which is a potential additive to modify the ash flow properties of these coals.In this work,we investigated the ash flow properties of a typical coal rich in calcium and iron by adding coal gangue with different SiO_(2)/Al_(2)O_(3)ratio.The results showed that the ash fusion temperatures(AFTs)firstly decreased,and then increased with increasing amount of coal gangue addition.Chemical composition of coal ash rich in calcium and iron moved from gehlenite primary phase to anorthite,quartz and corundum primary phases.The slags with coal gangue addition behaved as a glassy slag,of which the viscosity gradually increased as temperature decreased.Besides,a high SiO_(2)/Al_(2)O_(3)ratio of coal gangue was beneficial to modify the slag viscosity behavior.Addition of coal gangue with a high SiO_(2)/Al_(2)O_(3)ratio impeded formation of crystalline phases during cooling.This work demonstrated that coal gangue addition was an effective way to improve the ash flow properties of the coal rich in calcium and iron for the entrained flow gasifier.
基金supported by National Nataral Science Foundation of China-Deutsche Forschungsgemeinschaft(Grant number21761132032)National Key R&D Program of China(2017YFB0304300&2017YFB0304303)National Key R&D Program of China(2017YFB0304000)。
文摘One of the crucial issues in modern ash chemistry is the realization of efficient and clean coal conversion.Industrially,large-scale coal gasification technology is well known as the foundation to improve the atom economy.In practice,the coal ash fusibility is a critical factor to determine steady operation standards of the gasifier,which is also the significant criterion to coal species selection for gasification.Since coal behaviors are resultant from various evolutions in different scales,the multi-scale understanding of the ash chemistry is of significance to guide the fusibility adjustment for coal gasification.Considering important roles of molecular simulation in exploring ash chemistry,this paper reviews the recent studies and developments on modeling of molecular systems for fusibility related ash chemistry for the first time.The discussions are emphasized on those performed by quantum mechanics and molecular mechanics,the two major simulation methods for microscopic systems,which may provide various insights into fusibility mechanism.This review article is expected to present comprehensive information for recent molecular simulations of coal chemistry so that new clues to find strategies controlling the ash fusion behavior can be obtained.
