Coal gasification fly ash(CGFA)is an industrial solid waste from the coal circulating fluidized bed(CFB)gasification process,and it needs to be effectively disposed to achieve sustainable development of the environmen...Coal gasification fly ash(CGFA)is an industrial solid waste from the coal circulating fluidized bed(CFB)gasification process,and it needs to be effectively disposed to achieve sustainable development of the environment.To realize the application of CGFA as a precursor of porous carbon materials,the physicochemical properties of three kinds of CGFA from industrial CFB gasifiers are analyzed.Then,the activation potential of CGFA is acquired via steam activation experiments in a tube furnace reactor.Finally,the fluidization activation technology of CGFA is practiced in a bench-scale CFB test rig,and its advantages are highlighted.The results show that CGFA is characterized by a high carbon content in the range of 54.06%–74.09%,an ultrafine particle size(d50:16.3–26.1 μm),and a relatively developed pore structure(specific surface area SSA:139.29–551.97 m^(2)·g^(-1)).The proportion of micropores in CGFA increases gradually with the coal rank.Steam activation experiments show that the pore development of CGFA mainly includes three stages:initial pore development,dynamic equilibrium between micropores and mesopores and pore collapse.The SSA of lignite fly ash(LFA),subbituminous fly ash(SBFA)and anthracite fly ash(AFA)is maximally increased by 105%,13%and 72%after steam activation;the order of the largest carbon reaction rate and decomposition ratio of steam among the three kinds of CGFA is SBFA>LFA>AFA.As the ratio of oxygen to carbon during the fluidization activation of LFA is from 0.09 to 0.19,the carbon conversion ratio increases from 14.4%to 26.8%and the cold gas efficiency increases from 6.8%to 10.2%.The SSA of LFA increases by up to 53.9%during the fluidization activation process,which is mainly due to the mesoporous development.Relative to steam activation in a tube furnace reactor,fluidization activation takes an extremely short time(seconds)to achieve the same activation effect.It is expected to further improve the activation effect of LFA by regulating the carbon conversion ratio range of 27%–35%to create pores in the initial development stage.展开更多
This work evaluated the effects of inherent alkali and alkaline earth metals on nitrogen transformation during steam gasification of Shengli lignite at the temperature of 873-1173 K in a fluidized-bed/fixed-bed quartz...This work evaluated the effects of inherent alkali and alkaline earth metals on nitrogen transformation during steam gasification of Shengli lignite at the temperature of 873-1173 K in a fluidized-bed/fixed-bed quartz reactor. The results indicated that the alkali metal Na and alkaline earth metals Ca, Mg in coal have different effects on inherent nitrogen transformation to NH3, HCN and char-N during the lignite steam gasification. Specifically during the steam gasification of Shengli lignite, Na and Ca, Mg not only catalyze the inherent nitrogen conversions to NH3, but also promote the secondary reactions of the nascent char-N as well as the generation of NH3 from the generated HCN, meanwhile they also inhibited the inherent nitrogen conversion to HCN and char-N. The presence of Na, Ca and Mg hindered the formation of oxidized nitrogen (N-X) functional groups, but enhanced pyridinic nitrogen (N-6) and quaternary nitrogen's (N-Q) formation in char.展开更多
The effects of the constituents of mineral matter in brown coals from different deposits of Kansk-Achinsk, Lenaand from Yallourn Basins on the structural parameters and steam gasification reactivities of respective co...The effects of the constituents of mineral matter in brown coals from different deposits of Kansk-Achinsk, Lenaand from Yallourn Basins on the structural parameters and steam gasification reactivities of respective coal chars at moderate temperature and at low and high pressure were studied in this paper. The data on how the preliminary decationization with diluted hydrochloric, acetic and sulphuric acids affect char gasification reactivities are presented. The importance of surface area and crystallinity of chars and the presence of naturally occurring metals on gasification reactivity is considered. Quantitative correlations between the calcium contents and the extents of gasification are revealed. The gasification results obtained in a flow reactor with steam stream and in an autoclave reactor at high pressure of gaseous products are compared. The catalytic effect of dispersed calcium oxide-carbonate particles produced from the naturally occurring calcium containing carboxylates was shown to be a key factor for char gasification reactivity, the effect in the flow reactor being much larger as compared to that in the autoclave reactor. This was mainly related to different forms of catalytically active calcium species and to the composition of the gaseous reaction mixture.展开更多
Biomass,a source of renewable energy,represents an effective substitute to fossil fuels.Gasification is a process that organics are thermochemically converted into valuable gaseous products(e.g.biogas).In this work,th...Biomass,a source of renewable energy,represents an effective substitute to fossil fuels.Gasification is a process that organics are thermochemically converted into valuable gaseous products(e.g.biogas).In this work,the catalytic test demonstrated that the biogas produced from biomass gasification mainly consists of H2,CH4,CO,and CO2,which were then be used as the fuel for solid oxide fuel cell(SOFC).Planar SOFCs were fabricated and adopted.The steam reforming of biogas was carried out at the anode of a SOFC to obtain a hydrogen-rich fuel.The performance of the SOFCs operating on generated biogas was investigated by I-V polarization and electrochemical impedance spectra characterizations.An excellent cell performance was obtained,for example,the peak power density of the SOFC reached 1391 mW·cm-2 at 750℃when the generated biogas was used as the fuel.Furthermore,the SOFC fuelled by simulated biogas delivered a very stable operation.展开更多
In loss-of-coolant accidents,a passive containment heat removal system protects the integrity of the containment by condensing steam.As a large amount of air exists in the containment,the steam condensation heat trans...In loss-of-coolant accidents,a passive containment heat removal system protects the integrity of the containment by condensing steam.As a large amount of air exists in the containment,the steam condensation heat transfer can be significantly reduced.Based on previous research,traditional methods for enhancing pure steam condensation may not be applicable to steam–air condensation.In the present study,new methods of enhancing condensation heat transfer were adopted and several potentially enhanced heat transfer tubes,including corrugated tubes,spiral fin tubes,and ring fin tubes were designed.STAR-CCM+was used to determine the effect of enhanced heat transfer tubes on the steam condensation heat transfer.According to the calculations,the gas pressure ranged from 0.2 to 1.6 MPa,and air mass fraction ranged from 0.1 to 0.9.The effective perturbation of the high-concentration air layer was identified as the key factor for enhancing steam–air condensation heat transfer.Further,the designed corrugated tube performed well at atmospheric pressure,with a maximum enhancement of 27.4%,and performed poorly at high pressures.In the design of spiral fin tubes,special attention should be paid to the locations that may accumulate high-concentration air.Nonetheless,the ring-fin tubes generally displayed good performance under all conditions of interest,with a maximum enhancement of 24.2%.展开更多
In the present study the catalytic steam gasification of biomass to produce hydrogen-rich gas with calcined dolomite and Nano-NiO/γ-Al2O3 as catalyst in an externally heated fixed bed reactor was investigated. The in...In the present study the catalytic steam gasification of biomass to produce hydrogen-rich gas with calcined dolomite and Nano-NiO/γ-Al2O3 as catalyst in an externally heated fixed bed reactor was investigated. The influence of the catalyst and reactor temperature on yield and product composition was studied at the temperature range of 700oC - 900oC. Over the ranges of experimental conditions examined, calcined dolomite revealed better catalytic performance, at the presence of steam, tar was completely decomposed as temperature increases from 800oC to 900oC. Higher temperature resulted in more H2 and CO2 production, and dry gas yield. The highest H2 content of 51.02 mol%, and the highest H2 yield of 1.66 m3/kg biomass were observed at the highest temperature level of 900oC.展开更多
The choked back pressure characteristic of the steam turbine unit with air cooled condenser is very different with the unit with wet cooling technology, and the understanding of the choked back pressure performance ch...The choked back pressure characteristic of the steam turbine unit with air cooled condenser is very different with the unit with wet cooling technology, and the understanding of the choked back pressure performance change with operation load is important to guide the economic operation of the unit. One simplified Variable Operation Condition Analysis Method was put forward for calculation of the unit output-turbine back pressure characteristics. Based on this method, the choked back pressure for each operation load can be determined. An example was given for a super-critical, regenerative single-shaft, 2-casing with 2-exhaust steam turbine generation unit with air cooled condenser. The calculation result was provided and compared with the result of the unit with wet cooling technology.展开更多
This paper describes a single fluidized bed by the two-step gasification of the working method, process and biomass and coal co-gasification by a certain proportion of the results of a typical run. The results show th...This paper describes a single fluidized bed by the two-step gasification of the working method, process and biomass and coal co-gasification by a certain proportion of the results of a typical run. The results show that the biomass gasifi-cation technology for raw materials has a wide adaptability, the tar content in the gas is less than 10mg/m3,component in it ,the H2+CO>70%, H2/C ≈1~2,especially suitable for biomass from hydrogen, synthetic alcohol fuel, is a promising approach.展开更多
As the performance of an air-cooled condenser is apt to be affected by the fluctuating ambient condition, some difficulties are brought to the use of a steam feeding water pump in an air-cooled unit. This paper introd...As the performance of an air-cooled condenser is apt to be affected by the fluctuating ambient condition, some difficulties are brought to the use of a steam feeding water pump in an air-cooled unit. This paper introduces a new design of for steam feeding the water pump of an air-cooled unit using the back-pressure steam turbine as the prime motor. Using variable condition analysis on a 600 MW direct air-cooled unit, and with consideration of the effect on the ambient conditions, the feasibility, economy, and adaptability of the design are verified.展开更多
In the present study the catalytic steam gasification of biomass to produce hydrogen-rich gas with calcined dolomite as catalyst in an externally heated fixed bed reactor was investigated. The influence of the reactor...In the present study the catalytic steam gasification of biomass to produce hydrogen-rich gas with calcined dolomite as catalyst in an externally heated fixed bed reactor was investigated. The influence of the reactor temperature on yield and product composition was studied at the temperature range of 700 PoPC-900 PoPC. Over the ranges of experimental con-ditions examined, tar was completely decomposed as temperature increases from 800P oPC to 900 PoPC. Higher temperature resulted in more HR2R and COR2R production, and dry gas yield. The highest H2 content of 51.02 V%, and the highest HR2 Ryield of 1.66 mP3P/kg biomass were observed at the highest temperature level of 900P oPC.展开更多
Alumina-supported bimetallic cobalt-nickel catalyst has been prepared and employed in a fixed-bed reactor for the direct production of synthesis gas from glycerol steam reforming. Physicochemical properties of the 5Co...Alumina-supported bimetallic cobalt-nickel catalyst has been prepared and employed in a fixed-bed reactor for the direct production of synthesis gas from glycerol steam reforming. Physicochemical properties of the 5Co-10Ni/85Al2O3 catalyst were determined from N2-physisorption, H2-chemisorption, CO2 and NH3-temperature-programmed desorption measurements as well as X-ray diffraction analysis. Both weak and strong acid sites are present on the catalyst surface. The acidic:basic ratio is about 7. Carbon deposition was evident at 923 K;addition of H2 however has managed to reduce the carbon deposition. Significantly, this has resulted in the increment of CH4 formation rate, consistent with the increased carbon gasification and methanation. Carbon deposition was almost non-existent, particularly at 1023 K. In addition, the inclusion of hydrogen also has contributed to the decrease of CO2 and increase of CO formation rates. This was attributed to the reverse water-gas-shift reaction. Overall, both the CO2:CO and CO2:CH4 ratios decrease with the hydrogen partial pressure.展开更多
The 300 MW steam turbine installed in Waigaoqiao Power Plant with combined HPIP cylinders of double casing structure is a product of the Shanghai Turbine Works utilizing licensed technology. It has a large heat storag...The 300 MW steam turbine installed in Waigaoqiao Power Plant with combined HPIP cylinders of double casing structure is a product of the Shanghai Turbine Works utilizing licensed technology. It has a large heat storage capacity and good thermal insulation, so the metal temperature of first stage of HP cylinder (FSMTI) may reach 400-450℃ after shut down and it takes 7-8 days to cool to 150℃ by natural cooling, Now with a forced cooling system the cooling time may be reduced to 40 hours, so that the turbine may be opened for repair work in about 5-6 days. The cooling system for #2 unit and test procedure are briefly described below.展开更多
基金financially supported by the Special Research Assistant Fund Project of Chinese Academy of Sciences.
文摘Coal gasification fly ash(CGFA)is an industrial solid waste from the coal circulating fluidized bed(CFB)gasification process,and it needs to be effectively disposed to achieve sustainable development of the environment.To realize the application of CGFA as a precursor of porous carbon materials,the physicochemical properties of three kinds of CGFA from industrial CFB gasifiers are analyzed.Then,the activation potential of CGFA is acquired via steam activation experiments in a tube furnace reactor.Finally,the fluidization activation technology of CGFA is practiced in a bench-scale CFB test rig,and its advantages are highlighted.The results show that CGFA is characterized by a high carbon content in the range of 54.06%–74.09%,an ultrafine particle size(d50:16.3–26.1 μm),and a relatively developed pore structure(specific surface area SSA:139.29–551.97 m^(2)·g^(-1)).The proportion of micropores in CGFA increases gradually with the coal rank.Steam activation experiments show that the pore development of CGFA mainly includes three stages:initial pore development,dynamic equilibrium between micropores and mesopores and pore collapse.The SSA of lignite fly ash(LFA),subbituminous fly ash(SBFA)and anthracite fly ash(AFA)is maximally increased by 105%,13%and 72%after steam activation;the order of the largest carbon reaction rate and decomposition ratio of steam among the three kinds of CGFA is SBFA>LFA>AFA.As the ratio of oxygen to carbon during the fluidization activation of LFA is from 0.09 to 0.19,the carbon conversion ratio increases from 14.4%to 26.8%and the cold gas efficiency increases from 6.8%to 10.2%.The SSA of LFA increases by up to 53.9%during the fluidization activation process,which is mainly due to the mesoporous development.Relative to steam activation in a tube furnace reactor,fluidization activation takes an extremely short time(seconds)to achieve the same activation effect.It is expected to further improve the activation effect of LFA by regulating the carbon conversion ratio range of 27%–35%to create pores in the initial development stage.
基金The authors gratefully acknowledge the financial support provided by the 12th Five-Year Plan of National Science and Technology Support (Grant 2012BAA04B02)the National Natural Science Foundation of China (No.21406261).
文摘This work evaluated the effects of inherent alkali and alkaline earth metals on nitrogen transformation during steam gasification of Shengli lignite at the temperature of 873-1173 K in a fluidized-bed/fixed-bed quartz reactor. The results indicated that the alkali metal Na and alkaline earth metals Ca, Mg in coal have different effects on inherent nitrogen transformation to NH3, HCN and char-N during the lignite steam gasification. Specifically during the steam gasification of Shengli lignite, Na and Ca, Mg not only catalyze the inherent nitrogen conversions to NH3, but also promote the secondary reactions of the nascent char-N as well as the generation of NH3 from the generated HCN, meanwhile they also inhibited the inherent nitrogen conversion to HCN and char-N. The presence of Na, Ca and Mg hindered the formation of oxidized nitrogen (N-X) functional groups, but enhanced pyridinic nitrogen (N-6) and quaternary nitrogen's (N-Q) formation in char.
文摘The effects of the constituents of mineral matter in brown coals from different deposits of Kansk-Achinsk, Lenaand from Yallourn Basins on the structural parameters and steam gasification reactivities of respective coal chars at moderate temperature and at low and high pressure were studied in this paper. The data on how the preliminary decationization with diluted hydrochloric, acetic and sulphuric acids affect char gasification reactivities are presented. The importance of surface area and crystallinity of chars and the presence of naturally occurring metals on gasification reactivity is considered. Quantitative correlations between the calcium contents and the extents of gasification are revealed. The gasification results obtained in a flow reactor with steam stream and in an autoclave reactor at high pressure of gaseous products are compared. The catalytic effect of dispersed calcium oxide-carbonate particles produced from the naturally occurring calcium containing carboxylates was shown to be a key factor for char gasification reactivity, the effect in the flow reactor being much larger as compared to that in the autoclave reactor. This was mainly related to different forms of catalytically active calcium species and to the composition of the gaseous reaction mixture.
基金financially supported by the National Natural Science Foundation of China(Grants Nos.51302135 and 51678291)the Natural Science Foundation of Jiangsu Province,China(Grant No.BK20190965)+1 种基金the Research Project of Nanjing Institute of Technology(Grant No.YKJ201435)the Australian Research Council(ARC)Discovery Early Career Researcher Award DE180100773。
文摘Biomass,a source of renewable energy,represents an effective substitute to fossil fuels.Gasification is a process that organics are thermochemically converted into valuable gaseous products(e.g.biogas).In this work,the catalytic test demonstrated that the biogas produced from biomass gasification mainly consists of H2,CH4,CO,and CO2,which were then be used as the fuel for solid oxide fuel cell(SOFC).Planar SOFCs were fabricated and adopted.The steam reforming of biogas was carried out at the anode of a SOFC to obtain a hydrogen-rich fuel.The performance of the SOFCs operating on generated biogas was investigated by I-V polarization and electrochemical impedance spectra characterizations.An excellent cell performance was obtained,for example,the peak power density of the SOFC reached 1391 mW·cm-2 at 750℃when the generated biogas was used as the fuel.Furthermore,the SOFC fuelled by simulated biogas delivered a very stable operation.
基金supported by the National Key R&D Program of China(No. 2020YFB1901405)
文摘In loss-of-coolant accidents,a passive containment heat removal system protects the integrity of the containment by condensing steam.As a large amount of air exists in the containment,the steam condensation heat transfer can be significantly reduced.Based on previous research,traditional methods for enhancing pure steam condensation may not be applicable to steam–air condensation.In the present study,new methods of enhancing condensation heat transfer were adopted and several potentially enhanced heat transfer tubes,including corrugated tubes,spiral fin tubes,and ring fin tubes were designed.STAR-CCM+was used to determine the effect of enhanced heat transfer tubes on the steam condensation heat transfer.According to the calculations,the gas pressure ranged from 0.2 to 1.6 MPa,and air mass fraction ranged from 0.1 to 0.9.The effective perturbation of the high-concentration air layer was identified as the key factor for enhancing steam–air condensation heat transfer.Further,the designed corrugated tube performed well at atmospheric pressure,with a maximum enhancement of 27.4%,and performed poorly at high pressures.In the design of spiral fin tubes,special attention should be paid to the locations that may accumulate high-concentration air.Nonetheless,the ring-fin tubes generally displayed good performance under all conditions of interest,with a maximum enhancement of 24.2%.
文摘In the present study the catalytic steam gasification of biomass to produce hydrogen-rich gas with calcined dolomite and Nano-NiO/γ-Al2O3 as catalyst in an externally heated fixed bed reactor was investigated. The influence of the catalyst and reactor temperature on yield and product composition was studied at the temperature range of 700oC - 900oC. Over the ranges of experimental conditions examined, calcined dolomite revealed better catalytic performance, at the presence of steam, tar was completely decomposed as temperature increases from 800oC to 900oC. Higher temperature resulted in more H2 and CO2 production, and dry gas yield. The highest H2 content of 51.02 mol%, and the highest H2 yield of 1.66 m3/kg biomass were observed at the highest temperature level of 900oC.
文摘The choked back pressure characteristic of the steam turbine unit with air cooled condenser is very different with the unit with wet cooling technology, and the understanding of the choked back pressure performance change with operation load is important to guide the economic operation of the unit. One simplified Variable Operation Condition Analysis Method was put forward for calculation of the unit output-turbine back pressure characteristics. Based on this method, the choked back pressure for each operation load can be determined. An example was given for a super-critical, regenerative single-shaft, 2-casing with 2-exhaust steam turbine generation unit with air cooled condenser. The calculation result was provided and compared with the result of the unit with wet cooling technology.
文摘This paper describes a single fluidized bed by the two-step gasification of the working method, process and biomass and coal co-gasification by a certain proportion of the results of a typical run. The results show that the biomass gasifi-cation technology for raw materials has a wide adaptability, the tar content in the gas is less than 10mg/m3,component in it ,the H2+CO>70%, H2/C ≈1~2,especially suitable for biomass from hydrogen, synthetic alcohol fuel, is a promising approach.
文摘As the performance of an air-cooled condenser is apt to be affected by the fluctuating ambient condition, some difficulties are brought to the use of a steam feeding water pump in an air-cooled unit. This paper introduces a new design of for steam feeding the water pump of an air-cooled unit using the back-pressure steam turbine as the prime motor. Using variable condition analysis on a 600 MW direct air-cooled unit, and with consideration of the effect on the ambient conditions, the feasibility, economy, and adaptability of the design are verified.
文摘In the present study the catalytic steam gasification of biomass to produce hydrogen-rich gas with calcined dolomite as catalyst in an externally heated fixed bed reactor was investigated. The influence of the reactor temperature on yield and product composition was studied at the temperature range of 700 PoPC-900 PoPC. Over the ranges of experimental con-ditions examined, tar was completely decomposed as temperature increases from 800P oPC to 900 PoPC. Higher temperature resulted in more HR2R and COR2R production, and dry gas yield. The highest H2 content of 51.02 V%, and the highest HR2 Ryield of 1.66 mP3P/kg biomass were observed at the highest temperature level of 900P oPC.
文摘Alumina-supported bimetallic cobalt-nickel catalyst has been prepared and employed in a fixed-bed reactor for the direct production of synthesis gas from glycerol steam reforming. Physicochemical properties of the 5Co-10Ni/85Al2O3 catalyst were determined from N2-physisorption, H2-chemisorption, CO2 and NH3-temperature-programmed desorption measurements as well as X-ray diffraction analysis. Both weak and strong acid sites are present on the catalyst surface. The acidic:basic ratio is about 7. Carbon deposition was evident at 923 K;addition of H2 however has managed to reduce the carbon deposition. Significantly, this has resulted in the increment of CH4 formation rate, consistent with the increased carbon gasification and methanation. Carbon deposition was almost non-existent, particularly at 1023 K. In addition, the inclusion of hydrogen also has contributed to the decrease of CO2 and increase of CO formation rates. This was attributed to the reverse water-gas-shift reaction. Overall, both the CO2:CO and CO2:CH4 ratios decrease with the hydrogen partial pressure.
文摘The 300 MW steam turbine installed in Waigaoqiao Power Plant with combined HPIP cylinders of double casing structure is a product of the Shanghai Turbine Works utilizing licensed technology. It has a large heat storage capacity and good thermal insulation, so the metal temperature of first stage of HP cylinder (FSMTI) may reach 400-450℃ after shut down and it takes 7-8 days to cool to 150℃ by natural cooling, Now with a forced cooling system the cooling time may be reduced to 40 hours, so that the turbine may be opened for repair work in about 5-6 days. The cooling system for #2 unit and test procedure are briefly described below.