The detection of ash content in coal slime flotation tailings using deep learning can be hindered by various factors such as foam,impurities,and changing lighting conditions that disrupt the collection of tailings ima...The detection of ash content in coal slime flotation tailings using deep learning can be hindered by various factors such as foam,impurities,and changing lighting conditions that disrupt the collection of tailings images.To address this challenge,we present a method for ash content detection in coal slime flotation tailings.This method utilizes chromatographic filter paper sampling and a multi-scale residual network,which we refer to as MRCN.Initially,tailings are sampled using chromatographic filter paper to obtain static tailings images,effectively isolating interference factors at the flotation site.Subsequently,the MRCN,consisting of a multi-scale residual network,is employed to extract image features and compute ash content.Within the MRCN structure,tailings images undergo convolution operations through two parallel branches that utilize convolution kernels of different sizes,enabling the extraction of image features at various scales and capturing a more comprehensive representation of the ash content information.Furthermore,a channel attention mechanism is integrated to enhance the performance of the model.The combination of the multi-scale residual structure and the channel attention mechanism within MRCN results in robust capabilities for image feature extraction and ash content detection.Comparative experiments demonstrate that this proposed approach,based on chromatographic filter paper sampling and the multi-scale residual network,exhibits significantly superior performance in the detection of ash content in coal slime flotation tailings.展开更多
This work focuses on the production of a new composite material using Yellow River sediment and coal slime ash via alkali-activating method. XRD, FTIR and SEM/EDS were used to characterize the alkali-activated product...This work focuses on the production of a new composite material using Yellow River sediment and coal slime ash via alkali-activating method. XRD, FTIR and SEM/EDS were used to characterize the alkali-activated products and microstructure of the composite material. Compressive strength was tested to characterize the mechanical property of the composite material. It is found that the compressive strength of the Yellow River sediment-coal slime ash composites increases as the added Ca(OH)_2 content grows. The compressive strength increases fast in the early stage but slowly after 28 days. The strength of the composites can be significantly improved via the addition of small amount of Na OH and gypsum. The products(C-S-H, ettringite and CaCO_3), especially C-S-H, make much contribution to the enhancement of strength. The highest strength of the composites can reach 14.4 MPa after 90 days curing with 5% Ca(OH)_2, 0.2% NaOH and 7.5% gypsum. The improved properties of the composites show great potential of utilizing Yellow River sediment for inexpensive construction materials.展开更多
The effects of moisture content on the combustion characteristics and pore structure change of coal slime are studied in this paper.The effect of moisture content on the bed temperature change,combustion efficiency,an...The effects of moisture content on the combustion characteristics and pore structure change of coal slime are studied in this paper.The effect of moisture content on the bed temperature change,combustion efficiency,and NO_(x)and SO_(2)emission were obtained in a bench⁃scale fluidized bed reactor,revealing that the lowest bed temperature decreases with the increase in moisture content,but the effect on the highest bed temperature is not the same.Moreover,with the increase in moisture content,the observed degree of blackening of the flue gas increased,and more CO was produced,which in turn leads to a lower combustion efficiency of the coal slime.However,the presence of moisture plays a positive role in the reduction of NO_(x)and SO_(2).With the increase in moisture content,the amount of NO_(x)and SO_(2)produced tends to decrease.The effect of water on the combustion process of slime is mostly the impact of the severe vaporization process in the early stage to form a large water vapor channel,which is beneficial to the evaporation and loss of water,conducive to the reaction of water and coal combustion products,such as the formation of CO,reduction of NO_(x),SO_(2),etc.The large holes formed by the impact of water vapor decreased with the decrease of moisture content,and the nanoscale pores are mostly caused by the combustion process of volatilization and coke formation after the end of vaporization,and increase with the decrease of moisture content.展开更多
Coal slimes are mainly composed of coal and clay particles.The interaction energies among these particles were calculated using extended DLVO(DERJAGUIN-LANDAU-VERWEY-OVERBEEK)theory and the aggregation mechanisms were...Coal slimes are mainly composed of coal and clay particles.The interaction energies among these particles were calculated using extended DLVO(DERJAGUIN-LANDAU-VERWEY-OVERBEEK)theory and the aggregation mechanisms were analyzed based on the settling experiments for coal-kaolinite and coal-montmorillonite suspensions,respectively,under different conditions of water hardness.The results indicate that for coal-kaolinite suspensions,as the water hardness reaches 10.0mol/L,the coal particles aggregate with each other easily,and then,the coal particles may aggregate with kaolinite particles.However,no aggregation occurs between kaolinite particles.A clay platelet network is formed in coal-montmorillonite suspensions by montmorillonite particles and coal particles are captured into the network.Coal and montmorillonite particles settle completely.展开更多
It is an effective way to use coal slime as fuel for circulating fluidized bed boilers, which will not only solve its pollution to the environment, but also turn waste to treasure. In order to provide basic technical ...It is an effective way to use coal slime as fuel for circulating fluidized bed boilers, which will not only solve its pollution to the environment, but also turn waste to treasure. In order to provide basic technical information for transportation of coal slime from the coal preparation plant to the boiler, this paper experimentally studied the rheological behaviors of coal slime produced by filter-pressing. By using a rotational viscometer, the influences of water content, temperature, and shear time on the rheological behaviors of coal slime were investigated. Experimental results show that the coal slime will behave like Bingham plastics with low water content and like Bingham pseudo-plastics with 37.5% water content,while like pseudo-plastics with 40% water content. This indicates that the water content of coal slime must be controlled in consideration of both transportation resistance and combustion efficiency. Study results also show that, the apparent viscosity of coal slime at 5℃ is about 1.5–1.7 times of that at 40℃ for water contents 32%–37.5%, while the influence of temperature can be neglected when the water content is 40%. With increasing of water content, the influences of shear time on the apparent viscosity of coal slime becomes less. When the water content is more than 30%, the effect of shear time is negligible. It indicates that water content has the most important influence on the rheological behaviors of coal slime. There must be an optimal water content in considering conveying resistance and combustion efficiency. The environmental temperature must also be considered in coal slime transportation.展开更多
To research a novel technology for dry coarse coal slime beneficiation and extend its application, active pulsing air separation technology was investigated by DEM-CFD coupling simulation approach. The results show th...To research a novel technology for dry coarse coal slime beneficiation and extend its application, active pulsing air separation technology was investigated by DEM-CFD coupling simulation approach. The results show that the ash content of feed is reduced by 10% 15% and the organic efficiency is up to 91.78% by using the active pulsing air separation technology. The gas solid flow in the active pulsing air classifier was simulated. Meanwhile, the characteristics of particle motion and the separation process of different particles were analyzed, and the mechanical structure of the classifier was also modified to achieve high separation efficiency. Therefore, a novel high-efficiency dry beneficiation technique was advanced for coarse coal slime.展开更多
Coal slime can be disposed in quantity and fully utilized in a well-designed circulating fluidized bed(CFB)boiler,but the nitrogen oxides(NO_(x))and sulphur dioxide(SO_(2))emissions generated in the combustion of coal...Coal slime can be disposed in quantity and fully utilized in a well-designed circulating fluidized bed(CFB)boiler,but the nitrogen oxides(NO_(x))and sulphur dioxide(SO_(2))emissions generated in the combustion of coal slime have contributed to serious atmospheric pollution.High Temperature&Post-combustion Technology,a novel and high-efficient way to reduce the NO_(x)emission in the process of combustion,is applied to a 75 t/h CFB boiler burning exclusively coal slime,which will succeed to meet the ultra-low NO_(x)emission standard.To further explore an appropriate method to reduce the SO_(2)emission under the condition of new technology,the experiments were conducted on a 75 t/h CFB boiler with post-combustion chamber to study the influence of limestone addition on the combustion and emission characteristics of coal slime.The experimental results showed that High Temperature&Post-combustion Technology combined with the sorbent injection in the furnace is a very promising technology to control the NO_(x)and SO_(2)emissions simultaneously.Limestone addition can cause the slight decrease in combustion temperature.Limestone addition will lead to the increase in NO_(x)emission in the combustion of coal slime.In 75 t/h coal slime CFB boiler,the desulfurization efficiency of limestone injection in furnace is close to 98%,achieving the ultra-low SO_(2)emission.To meet the standard of ultra-low NO_(x)and SO_(2)emission,the two technologies for simultaneous removal of NO_(x)and SO_(2)emissions are economical and feasible currently:Removal of SO_(2)under ultra-low NO_(x)emission and Removal of NO_(x)under ultra-low SO_(2)emission.展开更多
The NO_(x)emission of coal slime burned in circulating fluidized bed(CFB)boilers could hardly meet the increasingly strict standards in China.Feeding coal slime from the top of furnace led to uneven combustion in furn...The NO_(x)emission of coal slime burned in circulating fluidized bed(CFB)boilers could hardly meet the increasingly strict standards in China.Feeding coal slime from the top of furnace led to uneven combustion in furnace and cyclones,short residence time and overheated tail heating surface.The effects of feeding positions on the combustion uniformity and pollutant emission characteristics of coal slime were studied.The experimental results showed that the coal slime combustion was more uniform when feeding from the front wall and longer residence time was conducive to the control of NO_(x)emission.When the boiler temperature and excess air ratio were almost identical,the initial NO_(x)emissions were 45.0 mg·m^(−3)and 70.7 mg·m^(−3)when feeding from the front wall and the top of furnace,respectively;the NO_(x)emission was cut down 36.35%when feeding from the front wall,successfully meeting the ultra-low NO_(x)emission standard of China.The adoption of feeding from the front wall greatly reduced the original emission of NO_(x);the operation costs in the practical applications were saved to a large extent.展开更多
Coal slime has low ash content,and adding coal slime during coal gangue combustion may have influence on combustion character;and at this process,NO will emit,and lead to environmental pollution.O_(2)/CO_(2)atmosphere...Coal slime has low ash content,and adding coal slime during coal gangue combustion may have influence on combustion character;and at this process,NO will emit,and lead to environmental pollution.O_(2)/CO_(2)atmosphere is conducive to NO emission reduction.Thus combustion characteristics and NO emissions during co-combustion of coal gangue and coal slime in O_(2)/CO_(2)atmospheres were studied.The results showed the addition of coal slime increased the combustion activity of the mixed fuels in both air and O_(2)/CO_(2)atmospheres.During co-combustion,there are synergistic effects between them at the fixed carbon combustion stage,and higher blending ratio of coal slime leads to stronger synergistic effect.Furthermore,this study also showed that with the increasing of coal slime blending ratio,the emission concentration of NO increases gradually;with the increase of temperature and O_(2)concentration,the NO emission concentration also gradually increases,and higher O_(2)concentration leads to shorter time required for the complete release of NO.Besides that,the results also demonstrate that the proportion of pyrrole and nitrogen oxide in the ashes increases with the increase of combustion temperature,and pyridine and quaternary nitrogen gradually disappear,while the total nitrogen content in ash decreases with the increase of temperature.The results will contribute to a better understanding of the co-combustion process of coal gangue and coal slime in O_(2)/CO_(2)atmosphere,and provide basic data for the practical industrial application of coal gangue and slime.展开更多
Coal slime is a kind of solid waste and inferior fuel, which is urgently needed to utilize. In this paper, a high-temperature thermal treatment of coal slime in a circulating fluidized bed(CFB) was attempted to achiev...Coal slime is a kind of solid waste and inferior fuel, which is urgently needed to utilize. In this paper, a high-temperature thermal treatment of coal slime in a circulating fluidized bed(CFB) was attempted to achieve resource utilization. In the experiment, the combustion characteristics of dried coal slime during high-temperature thermal treatment were investigated in a 0.5 MW pilot-scale CFB. The stable fluidized combustion of dried coal slime was realized. When the excess air ratio was closer to 1.0, the furnace temperatures would be uniform. The ignition method of dried coal slime was changed correspondingly while the feeding position changed. However, feeding coal slime to the loop seal was instrumental in decreasing NO_(x) emissions. Moreover, the NO_(x) emissions were tried to further control by the post-combustion technology. Post-combustion technology could significantly reduce NO_(x) emissions below 50 mg·Nm^(-3) while ensuring combustion efficiency. Besides, it was found that there was an optimum excess air ratio in CFB of about 0.9 resulting in minimum NO_(x) emissions of coal slime. The experiment results could well guide the industrial-scale high temperature thermal treatment of coal slime.展开更多
In this study,coal slime was mainly utilized to conduct experiments on a 30 kW preheating combustion test rig to analyze the conversion pathway of sulfur during the experiment,aiming at reducing slime pollution,contro...In this study,coal slime was mainly utilized to conduct experiments on a 30 kW preheating combustion test rig to analyze the conversion pathway of sulfur during the experiment,aiming at reducing slime pollution,controlling sulfur emission reasonably,and providing theoretical support for the preheating combustion technology.The results showed that after the coal slime was preheated,a large number of elements were released.The maximum release rates for H and S were 94.0%and 73.3%,respectively.The released S was converted into the sulfur-containing gases like H_(2)S,COS,CS_(2),and the rest existed in the solid in the five forms of mercaptan,thiophene,sulfoxide,sulfone,and sulfate.Besides,during the combustion process,the gas was oxidized continuously and finally converted into SO2,leaving only the sulfate in the fly ash.In the preheating combustion process,26.7%of the S was released from the coal,73.3%of the S was retained in the semi-coke,and the final SO2 emission concentration of combustion was 959 ppm.展开更多
基金This work was supported by National Natural Science Foundation of China:Grant No.62106048.
文摘The detection of ash content in coal slime flotation tailings using deep learning can be hindered by various factors such as foam,impurities,and changing lighting conditions that disrupt the collection of tailings images.To address this challenge,we present a method for ash content detection in coal slime flotation tailings.This method utilizes chromatographic filter paper sampling and a multi-scale residual network,which we refer to as MRCN.Initially,tailings are sampled using chromatographic filter paper to obtain static tailings images,effectively isolating interference factors at the flotation site.Subsequently,the MRCN,consisting of a multi-scale residual network,is employed to extract image features and compute ash content.Within the MRCN structure,tailings images undergo convolution operations through two parallel branches that utilize convolution kernels of different sizes,enabling the extraction of image features at various scales and capturing a more comprehensive representation of the ash content information.Furthermore,a channel attention mechanism is integrated to enhance the performance of the model.The combination of the multi-scale residual structure and the channel attention mechanism within MRCN results in robust capabilities for image feature extraction and ash content detection.Comparative experiments demonstrate that this proposed approach,based on chromatographic filter paper sampling and the multi-scale residual network,exhibits significantly superior performance in the detection of ash content in coal slime flotation tailings.
基金Funded by the National Natural Science Foundation of China(No.51578108)the Ministry of Water Resource of the People’s Republic of China(No.201501003)
文摘This work focuses on the production of a new composite material using Yellow River sediment and coal slime ash via alkali-activating method. XRD, FTIR and SEM/EDS were used to characterize the alkali-activated products and microstructure of the composite material. Compressive strength was tested to characterize the mechanical property of the composite material. It is found that the compressive strength of the Yellow River sediment-coal slime ash composites increases as the added Ca(OH)_2 content grows. The compressive strength increases fast in the early stage but slowly after 28 days. The strength of the composites can be significantly improved via the addition of small amount of Na OH and gypsum. The products(C-S-H, ettringite and CaCO_3), especially C-S-H, make much contribution to the enhancement of strength. The highest strength of the composites can reach 14.4 MPa after 90 days curing with 5% Ca(OH)_2, 0.2% NaOH and 7.5% gypsum. The improved properties of the composites show great potential of utilizing Yellow River sediment for inexpensive construction materials.
基金Sponsored by the Key Technologies Research and Development Program of China(Grant No.2016YFB0600203).
文摘The effects of moisture content on the combustion characteristics and pore structure change of coal slime are studied in this paper.The effect of moisture content on the bed temperature change,combustion efficiency,and NO_(x)and SO_(2)emission were obtained in a bench⁃scale fluidized bed reactor,revealing that the lowest bed temperature decreases with the increase in moisture content,but the effect on the highest bed temperature is not the same.Moreover,with the increase in moisture content,the observed degree of blackening of the flue gas increased,and more CO was produced,which in turn leads to a lower combustion efficiency of the coal slime.However,the presence of moisture plays a positive role in the reduction of NO_(x)and SO_(2).With the increase in moisture content,the amount of NO_(x)and SO_(2)produced tends to decrease.The effect of water on the combustion process of slime is mostly the impact of the severe vaporization process in the early stage to form a large water vapor channel,which is beneficial to the evaporation and loss of water,conducive to the reaction of water and coal combustion products,such as the formation of CO,reduction of NO_(x),SO_(2),etc.The large holes formed by the impact of water vapor decreased with the decrease of moisture content,and the nanoscale pores are mostly caused by the combustion process of volatilization and coke formation after the end of vaporization,and increase with the decrease of moisture content.
基金Project(50425168)supported by the National Natural Science Foundation of ChinaProject (0100471413)supported by China Postdoctoral Science FoundationProject (201104547)supported by Pisdoctorcal Science Foundation of Jiangsu Province,China
文摘Coal slimes are mainly composed of coal and clay particles.The interaction energies among these particles were calculated using extended DLVO(DERJAGUIN-LANDAU-VERWEY-OVERBEEK)theory and the aggregation mechanisms were analyzed based on the settling experiments for coal-kaolinite and coal-montmorillonite suspensions,respectively,under different conditions of water hardness.The results indicate that for coal-kaolinite suspensions,as the water hardness reaches 10.0mol/L,the coal particles aggregate with each other easily,and then,the coal particles may aggregate with kaolinite particles.However,no aggregation occurs between kaolinite particles.A clay platelet network is formed in coal-montmorillonite suspensions by montmorillonite particles and coal particles are captured into the network.Coal and montmorillonite particles settle completely.
基金the National Key Technology R&D Program for the 12th Five-Year Plan of China (No. 2014BAB01B03)the National Natural Science Foundation of China (No. 51304192)
文摘It is an effective way to use coal slime as fuel for circulating fluidized bed boilers, which will not only solve its pollution to the environment, but also turn waste to treasure. In order to provide basic technical information for transportation of coal slime from the coal preparation plant to the boiler, this paper experimentally studied the rheological behaviors of coal slime produced by filter-pressing. By using a rotational viscometer, the influences of water content, temperature, and shear time on the rheological behaviors of coal slime were investigated. Experimental results show that the coal slime will behave like Bingham plastics with low water content and like Bingham pseudo-plastics with 37.5% water content,while like pseudo-plastics with 40% water content. This indicates that the water content of coal slime must be controlled in consideration of both transportation resistance and combustion efficiency. Study results also show that, the apparent viscosity of coal slime at 5℃ is about 1.5–1.7 times of that at 40℃ for water contents 32%–37.5%, while the influence of temperature can be neglected when the water content is 40%. With increasing of water content, the influences of shear time on the apparent viscosity of coal slime becomes less. When the water content is more than 30%, the effect of shear time is negligible. It indicates that water content has the most important influence on the rheological behaviors of coal slime. There must be an optimal water content in considering conveying resistance and combustion efficiency. The environmental temperature must also be considered in coal slime transportation.
基金Projects(51221462,51134022,51074156)supported by the National Natural Science Foundation of ChinaProject(2012CB214904)supported by the National Basic Research Program of ChinaProject(20120095130001)supported by Specialized Research Fund for the Doctoral Program of Higher Education,China
文摘To research a novel technology for dry coarse coal slime beneficiation and extend its application, active pulsing air separation technology was investigated by DEM-CFD coupling simulation approach. The results show that the ash content of feed is reduced by 10% 15% and the organic efficiency is up to 91.78% by using the active pulsing air separation technology. The gas solid flow in the active pulsing air classifier was simulated. Meanwhile, the characteristics of particle motion and the separation process of different particles were analyzed, and the mechanical structure of the classifier was also modified to achieve high separation efficiency. Therefore, a novel high-efficiency dry beneficiation technique was advanced for coarse coal slime.
基金financially supported by the"Transformational Technologies for Clean Energy and Demonstration",Strategic Priority Research Program of the Chinese Academy of Sciences,Grant No.XDA21040100。
文摘Coal slime can be disposed in quantity and fully utilized in a well-designed circulating fluidized bed(CFB)boiler,but the nitrogen oxides(NO_(x))and sulphur dioxide(SO_(2))emissions generated in the combustion of coal slime have contributed to serious atmospheric pollution.High Temperature&Post-combustion Technology,a novel and high-efficient way to reduce the NO_(x)emission in the process of combustion,is applied to a 75 t/h CFB boiler burning exclusively coal slime,which will succeed to meet the ultra-low NO_(x)emission standard.To further explore an appropriate method to reduce the SO_(2)emission under the condition of new technology,the experiments were conducted on a 75 t/h CFB boiler with post-combustion chamber to study the influence of limestone addition on the combustion and emission characteristics of coal slime.The experimental results showed that High Temperature&Post-combustion Technology combined with the sorbent injection in the furnace is a very promising technology to control the NO_(x)and SO_(2)emissions simultaneously.Limestone addition can cause the slight decrease in combustion temperature.Limestone addition will lead to the increase in NO_(x)emission in the combustion of coal slime.In 75 t/h coal slime CFB boiler,the desulfurization efficiency of limestone injection in furnace is close to 98%,achieving the ultra-low SO_(2)emission.To meet the standard of ultra-low NO_(x)and SO_(2)emission,the two technologies for simultaneous removal of NO_(x)and SO_(2)emissions are economical and feasible currently:Removal of SO_(2)under ultra-low NO_(x)emission and Removal of NO_(x)under ultra-low SO_(2)emission.
基金This work was financially supported by the Strategic Priority Research Program of the Chinese Academy of Sciences(Grant No.XDA21040100).
文摘The NO_(x)emission of coal slime burned in circulating fluidized bed(CFB)boilers could hardly meet the increasingly strict standards in China.Feeding coal slime from the top of furnace led to uneven combustion in furnace and cyclones,short residence time and overheated tail heating surface.The effects of feeding positions on the combustion uniformity and pollutant emission characteristics of coal slime were studied.The experimental results showed that the coal slime combustion was more uniform when feeding from the front wall and longer residence time was conducive to the control of NO_(x)emission.When the boiler temperature and excess air ratio were almost identical,the initial NO_(x)emissions were 45.0 mg·m^(−3)and 70.7 mg·m^(−3)when feeding from the front wall and the top of furnace,respectively;the NO_(x)emission was cut down 36.35%when feeding from the front wall,successfully meeting the ultra-low NO_(x)emission standard of China.The adoption of feeding from the front wall greatly reduced the original emission of NO_(x);the operation costs in the practical applications were saved to a large extent.
基金financially supported by National Natural Science Foundation of China-Shanxi coal based low carbon joint fund(U1610254)Natural Science Foundation of Shanxi Province(201901D111006)。
文摘Coal slime has low ash content,and adding coal slime during coal gangue combustion may have influence on combustion character;and at this process,NO will emit,and lead to environmental pollution.O_(2)/CO_(2)atmosphere is conducive to NO emission reduction.Thus combustion characteristics and NO emissions during co-combustion of coal gangue and coal slime in O_(2)/CO_(2)atmospheres were studied.The results showed the addition of coal slime increased the combustion activity of the mixed fuels in both air and O_(2)/CO_(2)atmospheres.During co-combustion,there are synergistic effects between them at the fixed carbon combustion stage,and higher blending ratio of coal slime leads to stronger synergistic effect.Furthermore,this study also showed that with the increasing of coal slime blending ratio,the emission concentration of NO increases gradually;with the increase of temperature and O_(2)concentration,the NO emission concentration also gradually increases,and higher O_(2)concentration leads to shorter time required for the complete release of NO.Besides that,the results also demonstrate that the proportion of pyrrole and nitrogen oxide in the ashes increases with the increase of combustion temperature,and pyridine and quaternary nitrogen gradually disappear,while the total nitrogen content in ash decreases with the increase of temperature.The results will contribute to a better understanding of the co-combustion process of coal gangue and coal slime in O_(2)/CO_(2)atmosphere,and provide basic data for the practical industrial application of coal gangue and slime.
基金financially supported by the National Key Research&Development Program of China(Grant No.2018YFB0605002)“Transformational Technologies for Clean Energy and Demonstration”,Strategic Priority Research Program of the Chinese Academy of Sciences(Grant No.XDA21040100)。
文摘Coal slime is a kind of solid waste and inferior fuel, which is urgently needed to utilize. In this paper, a high-temperature thermal treatment of coal slime in a circulating fluidized bed(CFB) was attempted to achieve resource utilization. In the experiment, the combustion characteristics of dried coal slime during high-temperature thermal treatment were investigated in a 0.5 MW pilot-scale CFB. The stable fluidized combustion of dried coal slime was realized. When the excess air ratio was closer to 1.0, the furnace temperatures would be uniform. The ignition method of dried coal slime was changed correspondingly while the feeding position changed. However, feeding coal slime to the loop seal was instrumental in decreasing NO_(x) emissions. Moreover, the NO_(x) emissions were tried to further control by the post-combustion technology. Post-combustion technology could significantly reduce NO_(x) emissions below 50 mg·Nm^(-3) while ensuring combustion efficiency. Besides, it was found that there was an optimum excess air ratio in CFB of about 0.9 resulting in minimum NO_(x) emissions of coal slime. The experiment results could well guide the industrial-scale high temperature thermal treatment of coal slime.
基金This study is supported by the high-efficiency and low-nitrogen combustion technology and demonstration of coal-fired industrial boilers(XDA20140100).
文摘In this study,coal slime was mainly utilized to conduct experiments on a 30 kW preheating combustion test rig to analyze the conversion pathway of sulfur during the experiment,aiming at reducing slime pollution,controlling sulfur emission reasonably,and providing theoretical support for the preheating combustion technology.The results showed that after the coal slime was preheated,a large number of elements were released.The maximum release rates for H and S were 94.0%and 73.3%,respectively.The released S was converted into the sulfur-containing gases like H_(2)S,COS,CS_(2),and the rest existed in the solid in the five forms of mercaptan,thiophene,sulfoxide,sulfone,and sulfate.Besides,during the combustion process,the gas was oxidized continuously and finally converted into SO2,leaving only the sulfate in the fly ash.In the preheating combustion process,26.7%of the S was released from the coal,73.3%of the S was retained in the semi-coke,and the final SO2 emission concentration of combustion was 959 ppm.