Due to its low volatile characteristics of lean coal,it is difficult to catch fire and burn out.Therefore,high temperature is needed to maintain combustion efficiency,while,this leads to high nitrogen oxide emission.F...Due to its low volatile characteristics of lean coal,it is difficult to catch fire and burn out.Therefore,high temperature is needed to maintain combustion efficiency,while,this leads to high nitrogen oxide emission.For power plant boilers burning lean coal,stable combustion with lower nitrogen oxide emission is a challenging task.This study applied the 3D numerical simulation on the analysis of a novel de-coupling burner for low-volatile coal and its structure and operation parameters optimization.Results indicate that although it was more difficult for lean coal decoupling burner to ignite lean coal than high volatile coal,the burner formed a stepwise ignition trend,which promoted the rapid ignition of lean coal.Comparison of three central partition plate structure shows that in terms of characteristics of the flow field distribution,rich and lean separation and combustion,the structure with an inclination of 0°showed good performance,with its rich-lean air ratio being 0.85 and concentration ratio being 22.94,and there was an apparent decoupling combustion characteristic.Finally,the structure of the selected burner was optimized for its operational conditions.The optimal operating parameters was determined as the primary air velocity of 24.9 m·s^-1 and the mass flow rate of pulverized coal of 2.5 kg·s^-1,in which the pyrolysis products were utilized as reductive agent more fully.Eventually,the nitrogen oxide was efficiently reduced to nitrogen,which emission concentration was 61.88%lower than that in the design condition.展开更多
This study mainly introduces the technical properties of a kind of lean coal mined from Lu＇ an, a prefecture of Shanxi Province and its application to coal injection in large-scale blast furnaces（BFs） in Baosteel. ...This study mainly introduces the technical properties of a kind of lean coal mined from Lu＇ an, a prefecture of Shanxi Province and its application to coal injection in large-scale blast furnaces（BFs） in Baosteel. China is rich in lean coal resources. The technical properties of lean coal, including ash content, sulfur content and caloricity, etc., are similar to those of anthracite coal used in Baosteel, except the fact that the volatile of lean coal is higher. Besides, the explosive property and the coking property of lean coal are suitable for the BF coal injection. In this study, lean coal was tested in the pulverized coal injection （PCI） of a BF. In the test, the blending proportion of lean coal in the coal blend was increased gradually, and the consequential production indexes were traced. All the operational indexes show that the results of the BF coal injection are good, demonstrating that lean coal can be substituted for anthracite coal in the PCI in BFs. With an abundant amount and specific utilization,lean coal is found to be of a high economic value.展开更多
Melina wood torrefied at 260℃ for 60 min was agglomerated with lean grade coal fines into composite briquettes using pitch as binder.Torrefied biomass(3%-20%)and coal fines(80%-97%)were blended together to produce th...Melina wood torrefied at 260℃ for 60 min was agglomerated with lean grade coal fines into composite briquettes using pitch as binder.Torrefied biomass(3%-20%)and coal fines(80%-97%)were blended together to produce the composite briquettes under a hydraulic press(28 MPa).The briquettes were cured at 300℃.Density,water resistance,drop to fracture,impact resistance,and cold crushing strength were evaluated for the composite briquettes.The proximate,ultimate,and calorific value analyses were carried out according to different ASTM standards.Microstructural studies were carried out using scanning electron microscope and electron probe microanalyzer equipped with energy dispersive x-ray.Fourier Transform Infrared Spectrophotometer(FTIR)was used to obtain the functional groups in the raw materials and briquettes.The density of the composite briquettes ranged from 0.92 to 1.31 g/cm^(3) after curing.Briquettes with<10%torrefied biomass has good water resistance index(>95%).The highest cold crushing strength of 4 MPa was obtained for briquettes produced from 97%coal fines and 3%torrefied biomass.The highest drop to fracture(54 times/2 m)and impact resistance index(1350)were obtained for the sample produced from 97%coal and 3%torrefied biomass.The fixed and elemental carbons of the briquettes showed a mild improvement compared to the raw coal.The peaks from FTIR spectra for the briquettes shows the presence of aromatic C=C bonds and phenolic OH group.The composite briquettes with up to 20%torrefied biomass can all be useful as fuel for various applications.展开更多
基金supported by National Natural Science Foundation of China—Shanxi coal based low carbon joint fund(U1610254)Shanxi Province Basic Applied Research Youth Fund(201801D221345)2018 Xiangyuan County Solid Waste Comprehensive Utilization Science and Technology Projects(2018XYSDYY-14)。
文摘Due to its low volatile characteristics of lean coal,it is difficult to catch fire and burn out.Therefore,high temperature is needed to maintain combustion efficiency,while,this leads to high nitrogen oxide emission.For power plant boilers burning lean coal,stable combustion with lower nitrogen oxide emission is a challenging task.This study applied the 3D numerical simulation on the analysis of a novel de-coupling burner for low-volatile coal and its structure and operation parameters optimization.Results indicate that although it was more difficult for lean coal decoupling burner to ignite lean coal than high volatile coal,the burner formed a stepwise ignition trend,which promoted the rapid ignition of lean coal.Comparison of three central partition plate structure shows that in terms of characteristics of the flow field distribution,rich and lean separation and combustion,the structure with an inclination of 0°showed good performance,with its rich-lean air ratio being 0.85 and concentration ratio being 22.94,and there was an apparent decoupling combustion characteristic.Finally,the structure of the selected burner was optimized for its operational conditions.The optimal operating parameters was determined as the primary air velocity of 24.9 m·s^-1 and the mass flow rate of pulverized coal of 2.5 kg·s^-1,in which the pyrolysis products were utilized as reductive agent more fully.Eventually,the nitrogen oxide was efficiently reduced to nitrogen,which emission concentration was 61.88%lower than that in the design condition.
文摘This study mainly introduces the technical properties of a kind of lean coal mined from Lu＇ an, a prefecture of Shanxi Province and its application to coal injection in large-scale blast furnaces（BFs） in Baosteel. China is rich in lean coal resources. The technical properties of lean coal, including ash content, sulfur content and caloricity, etc., are similar to those of anthracite coal used in Baosteel, except the fact that the volatile of lean coal is higher. Besides, the explosive property and the coking property of lean coal are suitable for the BF coal injection. In this study, lean coal was tested in the pulverized coal injection （PCI） of a BF. In the test, the blending proportion of lean coal in the coal blend was increased gradually, and the consequential production indexes were traced. All the operational indexes show that the results of the BF coal injection are good, demonstrating that lean coal can be substituted for anthracite coal in the PCI in BFs. With an abundant amount and specific utilization,lean coal is found to be of a high economic value.
基金This research was funded by The World Academy of Science(TWAS),FR:3240287331,Italy and The Council of Scientific and Industrial Research(CSIR FUND:P-81-1-09),India.
文摘Melina wood torrefied at 260℃ for 60 min was agglomerated with lean grade coal fines into composite briquettes using pitch as binder.Torrefied biomass(3%-20%)and coal fines(80%-97%)were blended together to produce the composite briquettes under a hydraulic press(28 MPa).The briquettes were cured at 300℃.Density,water resistance,drop to fracture,impact resistance,and cold crushing strength were evaluated for the composite briquettes.The proximate,ultimate,and calorific value analyses were carried out according to different ASTM standards.Microstructural studies were carried out using scanning electron microscope and electron probe microanalyzer equipped with energy dispersive x-ray.Fourier Transform Infrared Spectrophotometer(FTIR)was used to obtain the functional groups in the raw materials and briquettes.The density of the composite briquettes ranged from 0.92 to 1.31 g/cm^(3) after curing.Briquettes with<10%torrefied biomass has good water resistance index(>95%).The highest cold crushing strength of 4 MPa was obtained for briquettes produced from 97%coal fines and 3%torrefied biomass.The highest drop to fracture(54 times/2 m)and impact resistance index(1350)were obtained for the sample produced from 97%coal and 3%torrefied biomass.The fixed and elemental carbons of the briquettes showed a mild improvement compared to the raw coal.The peaks from FTIR spectra for the briquettes shows the presence of aromatic C=C bonds and phenolic OH group.The composite briquettes with up to 20%torrefied biomass can all be useful as fuel for various applications.
