Petroleum coke was thermally treated on a fixed bed reactor in a temperature range of 1173-1673 K. The changes of the elemental composition and crystalline structure of petroleum coke, with heat treatments as well as ...Petroleum coke was thermally treated on a fixed bed reactor in a temperature range of 1173-1673 K. The changes of the elemental composition and crystalline structure of petroleum coke, with heat treatments as well as the gasification reactivity of the heat-treated petroleum cokes were investigated. The results showed that the petroleum coke was carbonized and grapbitized to a higher degree with increasing heating temperature, while the gasification reactivity decreased. The treatment at temperatures of 1173 and 1473 K significantly enlarged the specific surface area and the pore volume of petroleum coke. Both the specific surface area and the pore volume decreased at 1673 K. An empirical normal distribution function model （NDFM） was found to fit the gasification rates of petroleum coke well. The correlation coefficient of petroleum coke by normal distribution function model at different heat treatment temperatures is between 0.93 and 0.95.展开更多
Catalytic coal gasification technology shows prominent advantages in enhancing coal gasification reactivity and is restrained by the cost of catalyst.Two typical biomass ash additions,corn stalk ash(CSA,high K–Na and...Catalytic coal gasification technology shows prominent advantages in enhancing coal gasification reactivity and is restrained by the cost of catalyst.Two typical biomass ash additions,corn stalk ash(CSA,high K–Na and low Si)and poplar sawdust ash(PSA,high K–Ca and high Si),were employed to study the influence of biomass ash on pyrolysis process and char gasification reactivity of the typical anthracite.Microstructure characteristics of the char samples were examined by X-ray diffraction(XRD).Based on isothermal char-CO2 gasification experiments,the influence of biomass ash on reactivity of anthracite char was determined using thermogravimetric analyzer.Furthermore,structural parameters were correlated with different reactivity parameters to illustrate the crucial factor on the gasification reactivity varied with char reaction stages.The results indicate that both CSA and PSA additives hinder the growth of adjacent basic structural units in a vertical direction of the carbon structure,and then slow down the graphitization process of the anthracite during pyrolysis.The inhibition effect is more prominent with the increasing of biomass ash.In addition,the gasification reactivity of anthracite char is significantly promoted,which could be mainly attributed to the abundant active AAEM(especially K and Na)contents of biomass ash and a lower graphitization degree of mixed chars.Higher K and Na contents illustrate that the CSA has more remarkable promotion effect on char gasification reactivity than PSA,in accordance with the inhibition effect on the order degree of anthracite char.The stacking layer number could reasonably act as a rough indicator for evaluating the gasification reactivity of the char samples.展开更多
The gasification reactivity and kinetic parameters of coal chars for non-isothermal steam gasification were investigated.One kind of lignite and three kinds of bituminous coals were used as the samples,and their coal ...The gasification reactivity and kinetic parameters of coal chars for non-isothermal steam gasification were investigated.One kind of lignite and three kinds of bituminous coals were used as the samples,and their coal ranks follow the ascending order:XB<KL<ZJ<GD.As characterized by the comprehensive gasification index,the gasification reactivity of coal chars follows the descending order:XB>KL>ZJ>GD.Through systematically analyzing factors affecting gasification reactivity,it was ascertained that the gasification reactivity is mostly determined by the carbonaceous structure.The gasification reactivity is inversely proportional to the coal rank,and the higher the coal rank,the lower the gasification reactivity.A new kinetic model was proposed to calculate the kinetic parameters,in which the reaction order was considered as an unknown kinetic parameter.The reaction order n follows the ascending order:XB<KL<ZJ<GD,which are n=1.00,n=1.34,n=1.83,and n=2.63,respectively.It is proved that the reaction order is proportional to the coal rank,and the higher the coal rank,the higher the reaction order.展开更多
Zhtmdong coalfield is the largest intact coalfield worldwide and fluidized bed gasification has been considered as a promising way to achieve its clean and efficient utilization. The purpose of this study is to invest...Zhtmdong coalfield is the largest intact coalfield worldwide and fluidized bed gasification has been considered as a promising way to achieve its clean and efficient utilization. The purpose of this study is to investigate the phy- sicochemical properties and gasification reactivity of the ultrafme semi-char, derived from a bench-scale fluidized bed gasifier, using Zhundong coal as fuel. The results obtained are as follows. In comparison to the raw coal, the carbon and ash content of the semi-char increase after partial gasification, but the ash fusion temperatures of them show no significant difference. Particularly, 76.53% of the sodium in the feed coal has released to the gas phase after fluidized bed gasification. The chemical compositions of the semi-char are closely related to its particle size, attributable to the distinctly different natures of diverse elements. The semi-char exhibits a higher graphitization degree, higher BET surface area, and richer meso- and macropores, which results in superior gasification reactiv- ity than the coal char. The chemical reactivity of the semi-char is significantly improved by an increased gasifica- tion temperature, which suggests the necessity of regasification of the semi-char at a higher temperature. Conse- quently, it will be considered feasible that these carbons in the semi-char from fluidized bed gasitiers are rec- laimed and reused for the gasification process.展开更多
The structural evolution and gasification reactivity of biochar prepared from the pyrolysis of wheat straw were investigated by in-situ Raman spectroscopy and thermogravimetric analysis.The Raman spectra consisted of ...The structural evolution and gasification reactivity of biochar prepared from the pyrolysis of wheat straw were investigated by in-situ Raman spectroscopy and thermogravimetric analysis.The Raman spectra consisted of a combination of four Lorentzian bands(D1,D2,D4,G)and one Gaussian band(D3)in the first-order region.The experimental results showed that the addition of catalysts or the presence of ash could improve the CO_(2) gasification reactivity of biochar and result in a larger ID1/IG ratio and a lower IG/IALL ratio,meaning that the carbon structure was less ordered,and there were also more active sites such as amorphous carbon and cross-linked structures;Ca-based catalysts and K-based catalysts changed the evolution of biochar structure in a different way in CO_(2) atmosphere,the ID3/ID1 of Ca-based biochar was close to the value of non-catalyst biochar and decreased slowly,indicating that the Ca-based catalysts can stabilize the aromatic rings,while the IG/IALL of K-based biochar decreases significantly and the ID3/ID1 increased significantly,indicating the increase of carbon structure defects and the cracking of large aromatic rings in bio-char into small ones;a scheme of K and Ca reaction with biochar in CO_(2) gasification process was proposed.展开更多
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
Coal utilization,as a major energy source,raises sustainability concerns and environmental impacts,prompting researchers to explore blending it with other feedstocks.This study discusses hydrochar coal-water slurry(HC...Coal utilization,as a major energy source,raises sustainability concerns and environmental impacts,prompting researchers to explore blending it with other feedstocks.This study discusses hydrochar coal-water slurry(HC-CWS)preparation conditions,emphasizing apparent viscosity and exploring the influence of high ash content on char reactivity.The study highlights that the presence of free water in sludge is moderately influential,while high amounts of free water in raw sewage sludge(SS)and its near absence during hydrothermal carbonization(HTC)of SS are both unfavorable for enhancing the overall performance of coal-water slurry(CWS).HTC reduces the concentration of hydroxyl functional group,enhancing slurry performance and reducing ash content in HC-CWS,indicating that coal complements hydrochar(HC).High-temperature HC preparation is unsuitable for HC-CWS due to increased viscosity and decreased stability.In terms of ash content,the optimal pH and HC ratio for CWS are determined at 30%HC.The gasification reactivity of HC,prepared at 180℃ with a 30%HC ratio in CWS at R0.5 is 6×10^(−3) and at R0.9 is 9×10^(−3).However,increasing HC to 50%diminishes reactivity under CO_(2) atmosphere.The inhibitory effect was observed with an increasing percentage of HC in CWS and the synergy factor decreased in the following order:10%HC>30%HC>50%HC,i.e.,from 1.04 to 0.35.The possible reason is the presence of high ash content and their similar initial gasification rates during its early stages.展开更多
文摘Petroleum coke was thermally treated on a fixed bed reactor in a temperature range of 1173-1673 K. The changes of the elemental composition and crystalline structure of petroleum coke, with heat treatments as well as the gasification reactivity of the heat-treated petroleum cokes were investigated. The results showed that the petroleum coke was carbonized and grapbitized to a higher degree with increasing heating temperature, while the gasification reactivity decreased. The treatment at temperatures of 1173 and 1473 K significantly enlarged the specific surface area and the pore volume of petroleum coke. Both the specific surface area and the pore volume decreased at 1673 K. An empirical normal distribution function model （NDFM） was found to fit the gasification rates of petroleum coke well. The correlation coefficient of petroleum coke by normal distribution function model at different heat treatment temperatures is between 0.93 and 0.95.
基金This work was financial supported by Natural Science Foundation of Shanxi Province(Grant Number 201801D12105)Fund Program for the Scientific Activities of Selected Returned Overseas Professionals in Shanxi Province(Grant Number 2017006)Shanxi Scholarship Council of China(Grant Number 2017-086).
文摘Catalytic coal gasification technology shows prominent advantages in enhancing coal gasification reactivity and is restrained by the cost of catalyst.Two typical biomass ash additions,corn stalk ash(CSA,high K–Na and low Si)and poplar sawdust ash(PSA,high K–Ca and high Si),were employed to study the influence of biomass ash on pyrolysis process and char gasification reactivity of the typical anthracite.Microstructure characteristics of the char samples were examined by X-ray diffraction(XRD).Based on isothermal char-CO2 gasification experiments,the influence of biomass ash on reactivity of anthracite char was determined using thermogravimetric analyzer.Furthermore,structural parameters were correlated with different reactivity parameters to illustrate the crucial factor on the gasification reactivity varied with char reaction stages.The results indicate that both CSA and PSA additives hinder the growth of adjacent basic structural units in a vertical direction of the carbon structure,and then slow down the graphitization process of the anthracite during pyrolysis.The inhibition effect is more prominent with the increasing of biomass ash.In addition,the gasification reactivity of anthracite char is significantly promoted,which could be mainly attributed to the abundant active AAEM(especially K and Na)contents of biomass ash and a lower graphitization degree of mixed chars.Higher K and Na contents illustrate that the CSA has more remarkable promotion effect on char gasification reactivity than PSA,in accordance with the inhibition effect on the order degree of anthracite char.The stacking layer number could reasonably act as a rough indicator for evaluating the gasification reactivity of the char samples.
基金The present work was supported by the National Natural Science Foundation of China(U1960205 and 51574023).
文摘The gasification reactivity and kinetic parameters of coal chars for non-isothermal steam gasification were investigated.One kind of lignite and three kinds of bituminous coals were used as the samples,and their coal ranks follow the ascending order:XB<KL<ZJ<GD.As characterized by the comprehensive gasification index,the gasification reactivity of coal chars follows the descending order:XB>KL>ZJ>GD.Through systematically analyzing factors affecting gasification reactivity,it was ascertained that the gasification reactivity is mostly determined by the carbonaceous structure.The gasification reactivity is inversely proportional to the coal rank,and the higher the coal rank,the lower the gasification reactivity.A new kinetic model was proposed to calculate the kinetic parameters,in which the reaction order was considered as an unknown kinetic parameter.The reaction order n follows the ascending order:XB<KL<ZJ<GD,which are n=1.00,n=1.34,n=1.83,and n=2.63,respectively.It is proved that the reaction order is proportional to the coal rank,and the higher the coal rank,the higher the reaction order.
基金the support of the National Natural Science Foundation of China(No.21306193)the International Science&Technology Cooperation Program of China(No.2014DFG61680)
文摘Zhtmdong coalfield is the largest intact coalfield worldwide and fluidized bed gasification has been considered as a promising way to achieve its clean and efficient utilization. The purpose of this study is to investigate the phy- sicochemical properties and gasification reactivity of the ultrafme semi-char, derived from a bench-scale fluidized bed gasifier, using Zhundong coal as fuel. The results obtained are as follows. In comparison to the raw coal, the carbon and ash content of the semi-char increase after partial gasification, but the ash fusion temperatures of them show no significant difference. Particularly, 76.53% of the sodium in the feed coal has released to the gas phase after fluidized bed gasification. The chemical compositions of the semi-char are closely related to its particle size, attributable to the distinctly different natures of diverse elements. The semi-char exhibits a higher graphitization degree, higher BET surface area, and richer meso- and macropores, which results in superior gasification reactiv- ity than the coal char. The chemical reactivity of the semi-char is significantly improved by an increased gasifica- tion temperature, which suggests the necessity of regasification of the semi-char at a higher temperature. Conse- quently, it will be considered feasible that these carbons in the semi-char from fluidized bed gasitiers are rec- laimed and reused for the gasification process.
基金supported by the Shanghai Engineering Research Center of Coal Gasification(18DZ2283900)the Fundamental Research Funds for the Central Universities and the National Natural Science Foundation of China(21676091).
文摘The structural evolution and gasification reactivity of biochar prepared from the pyrolysis of wheat straw were investigated by in-situ Raman spectroscopy and thermogravimetric analysis.The Raman spectra consisted of a combination of four Lorentzian bands(D1,D2,D4,G)and one Gaussian band(D3)in the first-order region.The experimental results showed that the addition of catalysts or the presence of ash could improve the CO_(2) gasification reactivity of biochar and result in a larger ID1/IG ratio and a lower IG/IALL ratio,meaning that the carbon structure was less ordered,and there were also more active sites such as amorphous carbon and cross-linked structures;Ca-based catalysts and K-based catalysts changed the evolution of biochar structure in a different way in CO_(2) atmosphere,the ID3/ID1 of Ca-based biochar was close to the value of non-catalyst biochar and decreased slowly,indicating that the Ca-based catalysts can stabilize the aromatic rings,while the IG/IALL of K-based biochar decreases significantly and the ID3/ID1 increased significantly,indicating the increase of carbon structure defects and the cracking of large aromatic rings in bio-char into small ones;a scheme of K and Ca reaction with biochar in CO_(2) gasification process was proposed.
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.
文摘Coal utilization,as a major energy source,raises sustainability concerns and environmental impacts,prompting researchers to explore blending it with other feedstocks.This study discusses hydrochar coal-water slurry(HC-CWS)preparation conditions,emphasizing apparent viscosity and exploring the influence of high ash content on char reactivity.The study highlights that the presence of free water in sludge is moderately influential,while high amounts of free water in raw sewage sludge(SS)and its near absence during hydrothermal carbonization(HTC)of SS are both unfavorable for enhancing the overall performance of coal-water slurry(CWS).HTC reduces the concentration of hydroxyl functional group,enhancing slurry performance and reducing ash content in HC-CWS,indicating that coal complements hydrochar(HC).High-temperature HC preparation is unsuitable for HC-CWS due to increased viscosity and decreased stability.In terms of ash content,the optimal pH and HC ratio for CWS are determined at 30%HC.The gasification reactivity of HC,prepared at 180℃ with a 30%HC ratio in CWS at R0.5 is 6×10^(−3) and at R0.9 is 9×10^(−3).However,increasing HC to 50%diminishes reactivity under CO_(2) atmosphere.The inhibitory effect was observed with an increasing percentage of HC in CWS and the synergy factor decreased in the following order:10%HC>30%HC>50%HC,i.e.,from 1.04 to 0.35.The possible reason is the presence of high ash content and their similar initial gasification rates during its early stages.
