SO_(2)and NO emitted from coal-fired power plants have caused serious air pollution in China.In this study,a test system for NO oxidation using O_(3)is established.The basic characteristics of NO oxidation and product...SO_(2)and NO emitted from coal-fired power plants have caused serious air pollution in China.In this study,a test system for NO oxidation using O_(3)is established.The basic characteristics of NO oxidation and products forms are studied.A separate test system for the combined removal of SO_(2)and NO_(x)is also established,and the absorption characteristics of NO_(x)are studied.The characteristics of NO oxidation and NO_(x)absorption were verified in a 35 t·h^(-1)industrial boiler wet combined desulfurization and denitrification project.The operating economy of ozone oxidation wet denitrification technology is analyzed.The results show that O_(3)has a high rate and strong selectivity for NO oxidation.When O_(3)is insufficient,the primary oxidation product is NO_(2).When O_(3)is present in excess,NO_(2)continues to get oxidized to N_(2)O_(5)or NO_(3).The removal efficiency of NO_(2)in alkaline absorption system is low(only about 15%).NOx removal efficiency can be improved by oxidizing NO_(x)to N_(2)O_(5)or NO_(3)by increasing ozone ratio.When the molar ratio of O_(3)/NO is 1.77,the NOx removal efficiency reaches 90.3%,while the operating cost of removing NO_(x)per kilogram is 6.06 USD(NO_(2)).展开更多
In this study,the open-source software MFIX-DEM simulations of a bubbling fluidized bed(BFB)are applied to assess nine drag models according to experimental and direct numerical simulation(DNS)results.The influence of...In this study,the open-source software MFIX-DEM simulations of a bubbling fluidized bed(BFB)are applied to assess nine drag models according to experimental and direct numerical simulation(DNS)results.The influence of superficial gas velocity on gas–solid flow is also examined.The results show that according to the distribution of time-averaged particle axial velocity in y direction,except for Wen–Yu and Tenneti–Garg–Subramaniam(TGS),other drag models are consistent with the experimental and DNS results.For the TGS drag model,the layer-by-layer movement of particles is observed,which indicates the particle velocity is not correctly predicted.The time domain and frequency domain analysis results of pressure drop of each drag model are similar.It is recommended to use the drag model derived from DNS or fine grid computational fluid dynamics–discrete element method(CFD-DEM)data first for CFD-DEM simulations.For the investigated BFB,the superficial gas velocity less than 0.9 m·s^(-1) should be adopted to obtain normal hydrodynamics.展开更多
Circulating fluidized bed(CFB)boilers has realized the clean and efficient utilization of inferior coal like gangue and coal slime,high sulfur coal,anthracite,petroleum coke,oil shale and other resources.As a country ...Circulating fluidized bed(CFB)boilers has realized the clean and efficient utilization of inferior coal like gangue and coal slime,high sulfur coal,anthracite,petroleum coke,oil shale and other resources.As a country with the largest amount of CFB boilers and the largest installed capacity in the world,China has 440100-600 MWe CFB boilers with a total capacity of 82.29 GWe,including 227 units of 135 MWe,95 units of300 MWe,and 24 supercritical units.The statistics of typical 100-300 MWe CFB boilers showed that the average number of unplanned shut-down was only 0.37 times per year,among which the 135 MWe was 0.26 times per year and 300 MWe was 0.46 times per ycai*.The auxiliary power ratio of some 300 MWe CFB boilers based on flow-pattern reconstruction can be reduced to about 4%,which is closed to the same level of pulverized coal(PC)boilers.This paper summarizes the development process and application status of China's large-scale CFB boilers,analyzes the characteristics and technical performance of the iconic units,and introduces solutions to the problems such as water wall wear and bottom ash cooling.展开更多
基金Huaneng Group Science and Technology Project(HNKJ17-H14)the Project of National Science and Technology Supporting Plan(2014BAA07B00)for their financial support。
文摘SO_(2)and NO emitted from coal-fired power plants have caused serious air pollution in China.In this study,a test system for NO oxidation using O_(3)is established.The basic characteristics of NO oxidation and products forms are studied.A separate test system for the combined removal of SO_(2)and NO_(x)is also established,and the absorption characteristics of NO_(x)are studied.The characteristics of NO oxidation and NO_(x)absorption were verified in a 35 t·h^(-1)industrial boiler wet combined desulfurization and denitrification project.The operating economy of ozone oxidation wet denitrification technology is analyzed.The results show that O_(3)has a high rate and strong selectivity for NO oxidation.When O_(3)is insufficient,the primary oxidation product is NO_(2).When O_(3)is present in excess,NO_(2)continues to get oxidized to N_(2)O_(5)or NO_(3).The removal efficiency of NO_(2)in alkaline absorption system is low(only about 15%).NOx removal efficiency can be improved by oxidizing NO_(x)to N_(2)O_(5)or NO_(3)by increasing ozone ratio.When the molar ratio of O_(3)/NO is 1.77,the NOx removal efficiency reaches 90.3%,while the operating cost of removing NO_(x)per kilogram is 6.06 USD(NO_(2)).
基金the China-CEEC Joint Higher Education Project(Cultivation Project)(CEEC2021001)Srdjan Beloševic,Aleksandar Milicevic and Ivan Tomanovic acknowledge the financial support by the Ministry of Science,Technological Development and Innovation of the Republic of Serbia(Contract Annex:451-03-47/2023-01/200017).
文摘In this study,the open-source software MFIX-DEM simulations of a bubbling fluidized bed(BFB)are applied to assess nine drag models according to experimental and direct numerical simulation(DNS)results.The influence of superficial gas velocity on gas–solid flow is also examined.The results show that according to the distribution of time-averaged particle axial velocity in y direction,except for Wen–Yu and Tenneti–Garg–Subramaniam(TGS),other drag models are consistent with the experimental and DNS results.For the TGS drag model,the layer-by-layer movement of particles is observed,which indicates the particle velocity is not correctly predicted.The time domain and frequency domain analysis results of pressure drop of each drag model are similar.It is recommended to use the drag model derived from DNS or fine grid computational fluid dynamics–discrete element method(CFD-DEM)data first for CFD-DEM simulations.For the investigated BFB,the superficial gas velocity less than 0.9 m·s^(-1) should be adopted to obtain normal hydrodynamics.
文摘Circulating fluidized bed(CFB)boilers has realized the clean and efficient utilization of inferior coal like gangue and coal slime,high sulfur coal,anthracite,petroleum coke,oil shale and other resources.As a country with the largest amount of CFB boilers and the largest installed capacity in the world,China has 440100-600 MWe CFB boilers with a total capacity of 82.29 GWe,including 227 units of 135 MWe,95 units of300 MWe,and 24 supercritical units.The statistics of typical 100-300 MWe CFB boilers showed that the average number of unplanned shut-down was only 0.37 times per year,among which the 135 MWe was 0.26 times per year and 300 MWe was 0.46 times per ycai*.The auxiliary power ratio of some 300 MWe CFB boilers based on flow-pattern reconstruction can be reduced to about 4%,which is closed to the same level of pulverized coal(PC)boilers.This paper summarizes the development process and application status of China's large-scale CFB boilers,analyzes the characteristics and technical performance of the iconic units,and introduces solutions to the problems such as water wall wear and bottom ash cooling.
