The highly active absorbent with oxidization based on fly ash, lime and additive was prepared. Experiments of simultaneous desulfurization and denitrification were carried out using fixture bed and duct injection. The...The highly active absorbent with oxidization based on fly ash, lime and additive was prepared. Experiments of simultaneous desulfurization and denitrification were carried out using fixture bed and duct injection. The influencial factors for the absorptive capacity of the absorbent were studied. The absorptive capacities of 120.7 mg for SO 2 and 43.7 mg for NOx were achieved at a Ca/(S+N) molar ratio 1.2, respectively, corresponding removal efficiencies of 87% and 76%, while spent absorbent appeared in the form of dry powder. The optimal temperature and humidity of flue gas treated with this process were shown to be approximately 50℃, and 5% respectively. The mechanism of removal for SO 2 and NOx was investigated. In comparison with traditional dry FGD, this process appears to have lower cost, less complicated configuration and simpler disposal of used absorbent. The valuable references can be provided for industrial application by this process. The foreground of application will be vast in China and in the world.展开更多
Coal combustion technologies are changing in order to burn coal more cleanly.Many 'clean combustion' and post-combustion technologies are developed to remove SO_2 and NO_xgases, particulate matter during combu...Coal combustion technologies are changing in order to burn coal more cleanly.Many 'clean combustion' and post-combustion technologies are developed to remove SO_2 and NO_xgases, particulate matter during combustion, or from the flue gases leaving the furnace. This paperfocuses on three types of fly ash (flue gas desulfurization (FGD) residuals, atmospheric fluidizedbed combustion (AFBC) residuals and sorbent duct injection (SDI) residuals) which produced by 'theclean combustion' and post-combustion technologies. The residuals formed by FGD are PCFA (pulverizedcoal fly ash) grains entrained with reacted and unre-acted sorbent and have lower bulk densitiesthan PCFA grains because it contains higher concentrations of calcium and sulfur, and lowerconcentrations of silicon, aluminum and iron than PCFAs. AFBC residuals consist of spent bed whichis a heterogeneous mixture of coarse-grained bed material and irregularly shaped, unfused, sphericalPCFAs. The main crystalline phases in AFBC residuals are anhydrite (reacted sorbent), quartz andlime (unreacted sobent), calcite, hematite, periclase, magnetite and feldspars. The residualsproduced by SDI contained 65 percent-70 percent PCFA with the larger sizes material beingirregularly shaped, fused or rough-edged. The reaction products of sorbent (portlandite and lime)included calcium sulfate (anhydrite) and calcium sulfate. The chemical properties of these residualsare similar to those of high calcium PCFAs because of the high alkalinity and high pH of theseresiduals.展开更多
文摘The highly active absorbent with oxidization based on fly ash, lime and additive was prepared. Experiments of simultaneous desulfurization and denitrification were carried out using fixture bed and duct injection. The influencial factors for the absorptive capacity of the absorbent were studied. The absorptive capacities of 120.7 mg for SO 2 and 43.7 mg for NOx were achieved at a Ca/(S+N) molar ratio 1.2, respectively, corresponding removal efficiencies of 87% and 76%, while spent absorbent appeared in the form of dry powder. The optimal temperature and humidity of flue gas treated with this process were shown to be approximately 50℃, and 5% respectively. The mechanism of removal for SO 2 and NOx was investigated. In comparison with traditional dry FGD, this process appears to have lower cost, less complicated configuration and simpler disposal of used absorbent. The valuable references can be provided for industrial application by this process. The foreground of application will be vast in China and in the world.
文摘Coal combustion technologies are changing in order to burn coal more cleanly.Many 'clean combustion' and post-combustion technologies are developed to remove SO_2 and NO_xgases, particulate matter during combustion, or from the flue gases leaving the furnace. This paperfocuses on three types of fly ash (flue gas desulfurization (FGD) residuals, atmospheric fluidizedbed combustion (AFBC) residuals and sorbent duct injection (SDI) residuals) which produced by 'theclean combustion' and post-combustion technologies. The residuals formed by FGD are PCFA (pulverizedcoal fly ash) grains entrained with reacted and unre-acted sorbent and have lower bulk densitiesthan PCFA grains because it contains higher concentrations of calcium and sulfur, and lowerconcentrations of silicon, aluminum and iron than PCFAs. AFBC residuals consist of spent bed whichis a heterogeneous mixture of coarse-grained bed material and irregularly shaped, unfused, sphericalPCFAs. The main crystalline phases in AFBC residuals are anhydrite (reacted sorbent), quartz andlime (unreacted sobent), calcite, hematite, periclase, magnetite and feldspars. The residualsproduced by SDI contained 65 percent-70 percent PCFA with the larger sizes material beingirregularly shaped, fused or rough-edged. The reaction products of sorbent (portlandite and lime)included calcium sulfate (anhydrite) and calcium sulfate. The chemical properties of these residualsare similar to those of high calcium PCFAs because of the high alkalinity and high pH of theseresiduals.
