The steam gasification characteristics of poplar sawdust were investigated in a piston fed fixed-bed gasifier,reflecting the batch feeding process of fixed-bed gasifiers in industrial applications.The effects of opera...The steam gasification characteristics of poplar sawdust were investigated in a piston fed fixed-bed gasifier,reflecting the batch feeding process of fixed-bed gasifiers in industrial applications.The effects of operating conditions,including steam supply,the flow rate of inert gas,gasification temperature,and feeding rate,on gasification reactivity and performance were investigated online.The major gas product during pyrolysis was CO,followed by H2,CH4,and CO_(2),and the gasification was greatly facilitated by the injection of steam to generate H2.The gasification reactivity and performance were improved with increased steam supply and temperature.The maximum production rate of H_(2)by char gasification was tripled and doubled,respectively,with an increase in steam supply from 50 to 400 mL/min and a temperature rise from 800 to 900◦C,and the time required for complete gasification was also halved.Compared to pyrolysis,the volume fraction of H2 increased from 23%to 37%,and correspondingly,the H_(2)/CO ratio increased from 0.42 to 0.95.展开更多
The steam gasification kinetics of Zhundong raw coal and the washed coal by deionized water or hydrochloric acid with/without addition of CaO were tested by thermogravimetric analyzer(TGA)at medium temperatures(650℃ ...The steam gasification kinetics of Zhundong raw coal and the washed coal by deionized water or hydrochloric acid with/without addition of CaO were tested by thermogravimetric analyzer(TGA)at medium temperatures(650℃ to 800℃).The cation contents of potassium and sodium in samples were determined by Inductively Coupled Plasma Optical Emission Spectrometer(ICP-OES).The Brunauer-Emmett-Teller(BET)surface area of the samples was tested by N2 adsorption,and the morphologies of the samples were characterized by scanning electron microscopy(SEM).Experimental results showed that the organic sodium was the main catalyst for the gasification of the pyrolysis char,and the gasification rate of the char could be enhanced further with the introduction of CaO.The inherent alkali metals in coal and the introduced CaO showed a synergistic effect that occurred obviously above 735℃.The char conversion curves with or without CaO were fitted by the modified volumetric model(MVM).The calculated results indicated that the addition of CaO increased the pre-exponential factor obviously,but made little changes on the activation energy.It was proposed that the synergistic effect was resulted from the co-melting of the sodium and CaO,which facilitated the migration of the catalyst ions and the generation of C(O)intermediates for the gasification.展开更多
A new type of mixture fuel, sludge–oil–coal agglomerate (SOCA), was catalytically gasified with steam in a thermobalance reactor under atmospheric pressure. All the four catalysts studied (K2CO3, CaO, NiO and Fe2O3)...A new type of mixture fuel, sludge–oil–coal agglomerate (SOCA), was catalytically gasified with steam in a thermobalance reactor under atmospheric pressure. All the four catalysts studied (K2CO3, CaO, NiO and Fe2O3) were found capable of enhancing the steam gasification rate and significantly increasing the conversion of carbon. The ranking of catalytic activity was found to be K2CO3 CaO > NiO > Fe2O3. A modified volumetric-reaction model in the literature was used to describe the conversion behavior of the steam gasification studied by evaluating the kinetic parameters. Expressions of the apparent gasification rates for SOCA were presented for the design of catalytic gasification processes.展开更多
Dual fluidized bed gasifiers (DFBG) are effective in producing nitrogen-free syngas from biomass. How- ever, to improve the gasifier performance, pressure drops and solid fractions within the DFBG system need to be ...Dual fluidized bed gasifiers (DFBG) are effective in producing nitrogen-free syngas from biomass. How- ever, to improve the gasifier performance, pressure drops and solid fractions within the DFBG system need to be controlled. In this study, the effects of varying the fluidizing velocity in the fast fluidized bed (FFB) on the pressure drops and the solid fractions in the system were investigated in a 100 kW DFBG and in a dual fluidized bed cold model (DFCM). Based on the experimental results, empirical correlations were developed to predict the height-averaged solid fraction in the bottom section of the FFB. Accuracy and advantages of the correlations were analyzed. The correlation is useful for design and modeling of the DFBG systems where the height-averaged solid fraction is required to be determined.展开更多
基金supported by the National Key Research and Development Program of China(No.2019YFC1906800).
文摘The steam gasification characteristics of poplar sawdust were investigated in a piston fed fixed-bed gasifier,reflecting the batch feeding process of fixed-bed gasifiers in industrial applications.The effects of operating conditions,including steam supply,the flow rate of inert gas,gasification temperature,and feeding rate,on gasification reactivity and performance were investigated online.The major gas product during pyrolysis was CO,followed by H2,CH4,and CO_(2),and the gasification was greatly facilitated by the injection of steam to generate H2.The gasification reactivity and performance were improved with increased steam supply and temperature.The maximum production rate of H_(2)by char gasification was tripled and doubled,respectively,with an increase in steam supply from 50 to 400 mL/min and a temperature rise from 800 to 900◦C,and the time required for complete gasification was also halved.Compared to pyrolysis,the volume fraction of H2 increased from 23%to 37%,and correspondingly,the H_(2)/CO ratio increased from 0.42 to 0.95.
基金financially supported by the research project“Advancing and Demonstration of the Technology of CO2 Capture,Storage and Usage”(2016YFE0102500)National Natural Science Foundation of China(51606194)。
文摘The steam gasification kinetics of Zhundong raw coal and the washed coal by deionized water or hydrochloric acid with/without addition of CaO were tested by thermogravimetric analyzer(TGA)at medium temperatures(650℃ to 800℃).The cation contents of potassium and sodium in samples were determined by Inductively Coupled Plasma Optical Emission Spectrometer(ICP-OES).The Brunauer-Emmett-Teller(BET)surface area of the samples was tested by N2 adsorption,and the morphologies of the samples were characterized by scanning electron microscopy(SEM).Experimental results showed that the organic sodium was the main catalyst for the gasification of the pyrolysis char,and the gasification rate of the char could be enhanced further with the introduction of CaO.The inherent alkali metals in coal and the introduced CaO showed a synergistic effect that occurred obviously above 735℃.The char conversion curves with or without CaO were fitted by the modified volumetric model(MVM).The calculated results indicated that the addition of CaO increased the pre-exponential factor obviously,but made little changes on the activation energy.It was proposed that the synergistic effect was resulted from the co-melting of the sodium and CaO,which facilitated the migration of the catalyst ions and the generation of C(O)intermediates for the gasification.
基金New and Renewable Technology Development Project (2005-N-WA02-P-02-3-010-2005) under MOCIE (Ministry of Commerce, Industryand Energy)New and Renewable Energy R&D Program (2006-N-CO12-P-03-3-050) under MOCIE+2 种基金Korea Research Foundation Grant funded by the Korean Government(MOEHRD) (KRF-2007-041-D0019)KESRI (R-2005-7-072), which is funded by MOCIEThe Specialized Graduate School Program from MKE (Ministry of Knowledge Economy)
文摘A new type of mixture fuel, sludge–oil–coal agglomerate (SOCA), was catalytically gasified with steam in a thermobalance reactor under atmospheric pressure. All the four catalysts studied (K2CO3, CaO, NiO and Fe2O3) were found capable of enhancing the steam gasification rate and significantly increasing the conversion of carbon. The ranking of catalytic activity was found to be K2CO3 CaO > NiO > Fe2O3. A modified volumetric-reaction model in the literature was used to describe the conversion behavior of the steam gasification studied by evaluating the kinetic parameters. Expressions of the apparent gasification rates for SOCA were presented for the design of catalytic gasification processes.
基金funded by the Ministry of Business,Innovation and Employment,New Zealand
文摘Dual fluidized bed gasifiers (DFBG) are effective in producing nitrogen-free syngas from biomass. How- ever, to improve the gasifier performance, pressure drops and solid fractions within the DFBG system need to be controlled. In this study, the effects of varying the fluidizing velocity in the fast fluidized bed (FFB) on the pressure drops and the solid fractions in the system were investigated in a 100 kW DFBG and in a dual fluidized bed cold model (DFCM). Based on the experimental results, empirical correlations were developed to predict the height-averaged solid fraction in the bottom section of the FFB. Accuracy and advantages of the correlations were analyzed. The correlation is useful for design and modeling of the DFBG systems where the height-averaged solid fraction is required to be determined.