Coal-fired plants are under pressure to reduce their carbon-intensity. Available options include co-firing CO2-neutral biomass, oxy-fuel-combustion as part of a carbon capture process or a combination of both to give...Coal-fired plants are under pressure to reduce their carbon-intensity. Available options include co-firing CO2-neutral biomass, oxy-fuel-combustion as part of a carbon capture process or a combination of both to give a “CO2-negative” power plant. BioCCS, the combination of CO2 Capture and Storage (CCS) with sustainable biomass conversion, is the only large-scale technology that can achieve net negative emissions. Combining, developing and demonstrating the oxy-combustion of high ratios of sustainable biomass with coal in flexible circulating fluidized bed (CFB) boiler will bring significant advances in the reduction of greenhouse gases (GHG) emissions. Areas addressed include possibilities for: biomass characterization;handling and feeding;co-firing ratios definition;CFB oxy-co-combustion studies;combustion performance;boiler flexibility in fuel and load;main emissions analysis;slaging, fouling and agglomeration;corrosion and erosion;and implications on plant operation and associated costs. The article will detail a comprehensive understanding on sustainable biomass supply, co-firing ratios and how direct biomass co-combustion under oxy-fuel conditions can be implemented. It seeks to push biomass co-combustion in future large-scale oxy-fuel CFB power stations to high thermal shares while enhancing the power plants’ operational flexibility, economic competitiveness and give operational procedures. There will be a need to consider the public acceptance of power production from coal and coal sustainability, by its combination with renewable sources of energy (biomass).展开更多
In this study,the thermogravimetric analysis(TGA)method has been used to evaluate the kinetic behavior of biomass,coal and its blends during oxyfuel co-combustion.The thermogravimetric results have been evaluated by t...In this study,the thermogravimetric analysis(TGA)method has been used to evaluate the kinetic behavior of biomass,coal and its blends during oxyfuel co-combustion.The thermogravimetric results have been evaluated by the Coats-Redfern method and validated by Criado’s method.TG and DTG curves indicate that as the oxygen concentration increases the ignition and burn out temperatures approach a lower temperature region.The combustion characteristic index shows that biomass to coal blends of 28%and 40%respectively can achieve enhanced combustion up to 60%oxygen enrichment.In the devolatilization region,the activation energies for coal and blends reduce while in the char oxidation region,they increase with rise in oxygen concentration.Biomass,however,indicates slightly different combustion characteristic of being degraded in a single step and its activation energies increase with rise in oxygen concentration.It is demonstrated in this work that oxygen enrichment has more positive combustion effect on coal than biomass.At 20%oxygen enrichment,28%and 40%blends indicate activation energy of 132.8 and 125.5 kJ·mol^-1 respectively which are lower than coal at 148.1 kJ·mol^-1 but higher than biomass at 81.5 kJ·mol^-1 demonstrating synergistic effect of fuel blending.Also,at char combustion step,an increase in activation energy for 28%blend is found to be 0.36 kJ·mol^-1 per rise in oxygen concentration which is higher than in 40%blend at 0.28 kJ·mol^-1.展开更多
Mixed incineration of municipal solid waste (MSW) in existing coal gangue power plant is a potentially highefficiency and low-cost MSW disposal way. In this paper, the co-combustion and pollutants emission characteris...Mixed incineration of municipal solid waste (MSW) in existing coal gangue power plant is a potentially highefficiency and low-cost MSW disposal way. In this paper, the co-combustion and pollutants emission characteristic of MSW and coal gangue was investigated in a circulating fluidized bed (CFB) combustor. The effect of MSW blend ratio, bed temperature and excess air ratio was detailedly studied. The results show the NOX and HC1 emission increases with the increasing MSW blend ratio and the SO2 emission decreases. With the increase of bed temperature, the CO emission decreases while the NOX and SO2 emission increases. The HC1 emission is nearly stable in the temperature range of 850-950℃. The increase of excess air ratio gradually increases the NOX emission but has no significant effect on the SO2 emission. The HC1 emission firstly increases and then decreases with the increase of excess air ratio. For a typical CFB operating condition with excess air ratio of 1.4, bed temperature of 900℃ and MSW blend ratio of 10%, the original CO, NOX, SO2 and HC1 emissions are 52, 181, 3373 and 58 mg/Nm^3 respectively.展开更多
The pulverized coal combustion in O2/CO2 atmosphere is one of the promising new technologies which can reduce the emission of carbon dioxide and NOx. In this study, the combustion behaviors of different mixing ratio o...The pulverized coal combustion in O2/CO2 atmosphere is one of the promising new technologies which can reduce the emission of carbon dioxide and NOx. In this study, the combustion behaviors of different mixing ratio of Shenhua coal with 20 μm and 74 μm particle size in the O2/CO2 atmosphere and air atmosphere were studied by using a thermal-gravimetric analyzer. The combustion characteristics such as ignition and burnout behavior were investigated in the temperature from 20℃ to 850℃. The influence of mixing ratio on combustion characteristics was conduced. The results obtained showed that the ignition temperature of the two kinds of particle size in O2/CO2 atmosphere is higher than in the air, while the activation energy in O2/CO2 atmosphere is lower. With the increasing ratio of 20 μm superfine pulverized coals, the ignition temperature and the activation energy decreased, while the DTG peak value increased, the maximum burning rate position advanced. There were three trends for the ignition temperature curve with the increasing of superfine coal ratio: the ignition of the mixed coal decreased rapidly, then changed less, at last reduced quickly.展开更多
Based on the theory of computational fluid dynamics(CFD),pulverized coal combustion alone,and the co-combustion of pulverized coal and refuse-derived fuel(RDF)in a Trinal-sprayed calciner(TTF)precalciner were simulate...Based on the theory of computational fluid dynamics(CFD),pulverized coal combustion alone,and the co-combustion of pulverized coal and refuse-derived fuel(RDF)in a Trinal-sprayed calciner(TTF)precalciner were simulated.The results revealed that when coal was used as a single fuel,the velocity field in the precalciner had good symmetry,and formed three spray effects and multiple recirculation zones.The main combustion zone was distributed in the lower tertiary air and pulverized coal area,and the highest temperature reached up to 1,500 K.According to the simulation results,the predicted decomposing rate of raw meal was 90.12%,which is in good agreement with the actual measured result.In addition,with the increase in RDF content,the average temperature of the furnace,the decomposition rate of the raw meal,and the NO_(x) concentration all exhibited a downward trend.Under the condition of ensuring the normal operation of the precalciner,blending with 20%RDF is the most reasonable strategy,and the NO_(x) emissions decreased by approximately 16%.展开更多
文摘Coal-fired plants are under pressure to reduce their carbon-intensity. Available options include co-firing CO2-neutral biomass, oxy-fuel-combustion as part of a carbon capture process or a combination of both to give a “CO2-negative” power plant. BioCCS, the combination of CO2 Capture and Storage (CCS) with sustainable biomass conversion, is the only large-scale technology that can achieve net negative emissions. Combining, developing and demonstrating the oxy-combustion of high ratios of sustainable biomass with coal in flexible circulating fluidized bed (CFB) boiler will bring significant advances in the reduction of greenhouse gases (GHG) emissions. Areas addressed include possibilities for: biomass characterization;handling and feeding;co-firing ratios definition;CFB oxy-co-combustion studies;combustion performance;boiler flexibility in fuel and load;main emissions analysis;slaging, fouling and agglomeration;corrosion and erosion;and implications on plant operation and associated costs. The article will detail a comprehensive understanding on sustainable biomass supply, co-firing ratios and how direct biomass co-combustion under oxy-fuel conditions can be implemented. It seeks to push biomass co-combustion in future large-scale oxy-fuel CFB power stations to high thermal shares while enhancing the power plants’ operational flexibility, economic competitiveness and give operational procedures. There will be a need to consider the public acceptance of power production from coal and coal sustainability, by its combination with renewable sources of energy (biomass).
基金Financed by the International Cooperation Foundation for ChinaUSA(NSFC-NSF 51661125012)。
文摘In this study,the thermogravimetric analysis(TGA)method has been used to evaluate the kinetic behavior of biomass,coal and its blends during oxyfuel co-combustion.The thermogravimetric results have been evaluated by the Coats-Redfern method and validated by Criado’s method.TG and DTG curves indicate that as the oxygen concentration increases the ignition and burn out temperatures approach a lower temperature region.The combustion characteristic index shows that biomass to coal blends of 28%and 40%respectively can achieve enhanced combustion up to 60%oxygen enrichment.In the devolatilization region,the activation energies for coal and blends reduce while in the char oxidation region,they increase with rise in oxygen concentration.Biomass,however,indicates slightly different combustion characteristic of being degraded in a single step and its activation energies increase with rise in oxygen concentration.It is demonstrated in this work that oxygen enrichment has more positive combustion effect on coal than biomass.At 20%oxygen enrichment,28%and 40%blends indicate activation energy of 132.8 and 125.5 kJ·mol^-1 respectively which are lower than coal at 148.1 kJ·mol^-1 but higher than biomass at 81.5 kJ·mol^-1 demonstrating synergistic effect of fuel blending.Also,at char combustion step,an increase in activation energy for 28%blend is found to be 0.36 kJ·mol^-1 per rise in oxygen concentration which is higher than in 40%blend at 0.28 kJ·mol^-1.
基金This work was supported by the National Natural Science Foundation of China (Grant No.U1610254)Shanxi Province Coal-based key Technology Research and Development Program (Grant No.MD2014-03).
文摘Mixed incineration of municipal solid waste (MSW) in existing coal gangue power plant is a potentially highefficiency and low-cost MSW disposal way. In this paper, the co-combustion and pollutants emission characteristic of MSW and coal gangue was investigated in a circulating fluidized bed (CFB) combustor. The effect of MSW blend ratio, bed temperature and excess air ratio was detailedly studied. The results show the NOX and HC1 emission increases with the increasing MSW blend ratio and the SO2 emission decreases. With the increase of bed temperature, the CO emission decreases while the NOX and SO2 emission increases. The HC1 emission is nearly stable in the temperature range of 850-950℃. The increase of excess air ratio gradually increases the NOX emission but has no significant effect on the SO2 emission. The HC1 emission firstly increases and then decreases with the increase of excess air ratio. For a typical CFB operating condition with excess air ratio of 1.4, bed temperature of 900℃ and MSW blend ratio of 10%, the original CO, NOX, SO2 and HC1 emissions are 52, 181, 3373 and 58 mg/Nm^3 respectively.
文摘The pulverized coal combustion in O2/CO2 atmosphere is one of the promising new technologies which can reduce the emission of carbon dioxide and NOx. In this study, the combustion behaviors of different mixing ratio of Shenhua coal with 20 μm and 74 μm particle size in the O2/CO2 atmosphere and air atmosphere were studied by using a thermal-gravimetric analyzer. The combustion characteristics such as ignition and burnout behavior were investigated in the temperature from 20℃ to 850℃. The influence of mixing ratio on combustion characteristics was conduced. The results obtained showed that the ignition temperature of the two kinds of particle size in O2/CO2 atmosphere is higher than in the air, while the activation energy in O2/CO2 atmosphere is lower. With the increasing ratio of 20 μm superfine pulverized coals, the ignition temperature and the activation energy decreased, while the DTG peak value increased, the maximum burning rate position advanced. There were three trends for the ignition temperature curve with the increasing of superfine coal ratio: the ignition of the mixed coal decreased rapidly, then changed less, at last reduced quickly.
基金the General Institute of Building Materials Research of China(No.2017YFC0210801)the Priority Academic Program Development of Jiangsu Higher Education Institutions(PAPD)。
文摘Based on the theory of computational fluid dynamics(CFD),pulverized coal combustion alone,and the co-combustion of pulverized coal and refuse-derived fuel(RDF)in a Trinal-sprayed calciner(TTF)precalciner were simulated.The results revealed that when coal was used as a single fuel,the velocity field in the precalciner had good symmetry,and formed three spray effects and multiple recirculation zones.The main combustion zone was distributed in the lower tertiary air and pulverized coal area,and the highest temperature reached up to 1,500 K.According to the simulation results,the predicted decomposing rate of raw meal was 90.12%,which is in good agreement with the actual measured result.In addition,with the increase in RDF content,the average temperature of the furnace,the decomposition rate of the raw meal,and the NO_(x) concentration all exhibited a downward trend.Under the condition of ensuring the normal operation of the precalciner,blending with 20%RDF is the most reasonable strategy,and the NO_(x) emissions decreased by approximately 16%.
