COREX工艺是目前非高炉炼铁工业化应用相对成熟的技术。煤气区域分布管道(areal gas distribution,AGD)是COREX竖炉中保障还原气体均匀分布、调控气体流向和流速的重要部件。然而,AGD管的存在会改变炉内物料的运动特性,进而对螺旋排料...COREX工艺是目前非高炉炼铁工业化应用相对成熟的技术。煤气区域分布管道(areal gas distribution,AGD)是COREX竖炉中保障还原气体均匀分布、调控气体流向和流速的重要部件。然而,AGD管的存在会改变炉内物料的运动特性,进而对螺旋排料机叶片的磨损状况产生影响。因此,着眼于研究AGD管排布方式对COREX竖炉螺旋叶片磨损的影响。基于离散单元法(discrete element method,DEM)并运用Hertz-Mindlin无滑移接触模型与Archard Wear磨损模型,系统探究了不同AGD管排布方式下炉料排出过程中颗粒速度、螺旋叶片所受压力及磨损量的分布规律。结果表明,在无AGD管的竖炉中,颗粒下降过程整体比较平稳。在有AGD管的竖炉中,管上方的颗粒下落滞后,而管周围的炉料颗粒下落超前。无AGD管的竖炉中,不同叶片的磨损量分布较为均匀;安装AGD管的竖炉中,AGD管正下方的螺旋叶片磨损量较小。相较于其他排布方式,安装4根AGD管的竖炉中叶片的整体磨损量最小。螺旋叶片上受到的压力和磨损量集中分布在内外侧边缘;叶片的磨损情况首先出现在每根叶片的中段位置,且该段的磨损量较大。依据研究结果,在实际生产中,优先采用4根AGD管交叉排布的方式;其次,建议在叶片易磨损处采用耐磨材料。展开更多
基于离散单元法,建立引入Areal Gas Distribution(AGD)技术COREX竖炉物料运动行为的DEM模型.模型计算结果与文献物理实验结果一致,证明模型的合理性.模拟结果显示,AGD竖炉内存在三种类型的流动区域:活塞流区、准停滞区及沟流区.物料运...基于离散单元法,建立引入Areal Gas Distribution(AGD)技术COREX竖炉物料运动行为的DEM模型.模型计算结果与文献物理实验结果一致,证明模型的合理性.模拟结果显示,AGD竖炉内存在三种类型的流动区域:活塞流区、准停滞区及沟流区.物料运动流型呈现Flat→波浪→W的演变过程.AGD梁下方形成的三角形空隙是还原煤气导入竖炉中心的主要煤气通道.竖炉围管区域AGD梁的安装会影响该区域物料的均匀下降,局部区域的较大法向力可能导致物料的挤压黏结,诱发围管slot堵塞.展开更多
为研究COREX预还原竖炉内煤气流动特性,利用数值模拟方法研究了炉内煤气停留时间分布(RTD),考察了AGD(Areal Gas Distribution)梁对COREX预还原竖炉炉内RTD的影响以及不同熔炼率下COREX预还原竖炉的RTD变化规律.模拟结果表明,随着2#CORE...为研究COREX预还原竖炉内煤气流动特性,利用数值模拟方法研究了炉内煤气停留时间分布(RTD),考察了AGD(Areal Gas Distribution)梁对COREX预还原竖炉炉内RTD的影响以及不同熔炼率下COREX预还原竖炉的RTD变化规律.模拟结果表明,随着2#COREX预还原竖炉AGD梁的安装,其整体时间密度分布函数变宽,平均停留时间变短,无量纲方差变大.AGD梁的安装增大了炉内的死区体积分数,2#COREX预还原竖炉炉内死区体积分数达到了26.81%.随着竖炉熔炼率的增加,炉内平均停留时间逐渐减小,无量纲方差逐渐增大.当熔炼率从150 t/h增长到180 t/h时,1#COREX竖炉死区体积分数降幅为68.1%,2#COREX竖炉降幅仅为15.52%.展开更多
Anogenital distance （AGD） is used to define degree of virilization of genital development, with shorter length being associated with feminization and male infertility. The first exon of the androgen receptor （AR） ...Anogenital distance （AGD） is used to define degree of virilization of genital development, with shorter length being associated with feminization and male infertility. The first exon of the androgen receptor （AR） consists of a polymorphic sequence of cytosine-adenineguanine （CAG） repeats, with longer CAG repeat lengths being associated with decreased receptor function. We sought to determine if there is an association between AGD and AR CAG repeat length. A cross-sectional, prospective cohort of men evaluated at a urology clinic at a single institution was recruited. AGD （the distance from the posterior scrotum to the anal verge） and penile length （PL） were measured. Sanger DNA sequence analysis was used to define CAG repeat length. AGD and CAG repeat lengths in 195 men were determined. On unadjusted analysis, there was no linear relationship between CAG repeat length and PL （P=0.17） or AGD （P=-0.31）. However, on sub-population analyses, those men with longer CAG repeat lengths （〉26） had significantly shorter AGDs compared to men with shorter CAG repeat lengths. For example, the mean AGD was 41.9 vs. 32.4 mm with a CAG repeat length ≤26 vs. 〉26 （P=0.01）. In addition, when stratifying the cohort based on AGD, those with AGD less than the median （i.e. 40 mm） had a longer CAG repeat length compared to men with an AGD 〉40 mm （P=-0.02）. In summary, no linear relationship was found between AGD and AR CAG repeat length overall.展开更多
The term Agriculture Green Development(AGD)was introduced by the 19 th National Congress of China’s CPCC in2017 as a name for the national strategy of sustainable development to realize green development.This nationa...The term Agriculture Green Development(AGD)was introduced by the 19 th National Congress of China’s CPCC in2017 as a name for the national strategy of sustainable development to realize green development.This national strategy aims at fundamental solutions for the so called three rural issues:(1)agriculture.展开更多
文摘COREX工艺是目前非高炉炼铁工业化应用相对成熟的技术。煤气区域分布管道(areal gas distribution,AGD)是COREX竖炉中保障还原气体均匀分布、调控气体流向和流速的重要部件。然而,AGD管的存在会改变炉内物料的运动特性,进而对螺旋排料机叶片的磨损状况产生影响。因此,着眼于研究AGD管排布方式对COREX竖炉螺旋叶片磨损的影响。基于离散单元法(discrete element method,DEM)并运用Hertz-Mindlin无滑移接触模型与Archard Wear磨损模型,系统探究了不同AGD管排布方式下炉料排出过程中颗粒速度、螺旋叶片所受压力及磨损量的分布规律。结果表明,在无AGD管的竖炉中,颗粒下降过程整体比较平稳。在有AGD管的竖炉中,管上方的颗粒下落滞后,而管周围的炉料颗粒下落超前。无AGD管的竖炉中,不同叶片的磨损量分布较为均匀;安装AGD管的竖炉中,AGD管正下方的螺旋叶片磨损量较小。相较于其他排布方式,安装4根AGD管的竖炉中叶片的整体磨损量最小。螺旋叶片上受到的压力和磨损量集中分布在内外侧边缘;叶片的磨损情况首先出现在每根叶片的中段位置,且该段的磨损量较大。依据研究结果,在实际生产中,优先采用4根AGD管交叉排布的方式;其次,建议在叶片易磨损处采用耐磨材料。
文摘基于离散单元法,建立引入Areal Gas Distribution(AGD)技术COREX竖炉物料运动行为的DEM模型.模型计算结果与文献物理实验结果一致,证明模型的合理性.模拟结果显示,AGD竖炉内存在三种类型的流动区域:活塞流区、准停滞区及沟流区.物料运动流型呈现Flat→波浪→W的演变过程.AGD梁下方形成的三角形空隙是还原煤气导入竖炉中心的主要煤气通道.竖炉围管区域AGD梁的安装会影响该区域物料的均匀下降,局部区域的较大法向力可能导致物料的挤压黏结,诱发围管slot堵塞.
文摘为研究COREX预还原竖炉内煤气流动特性,利用数值模拟方法研究了炉内煤气停留时间分布(RTD),考察了AGD(Areal Gas Distribution)梁对COREX预还原竖炉炉内RTD的影响以及不同熔炼率下COREX预还原竖炉的RTD变化规律.模拟结果表明,随着2#COREX预还原竖炉AGD梁的安装,其整体时间密度分布函数变宽,平均停留时间变短,无量纲方差变大.AGD梁的安装增大了炉内的死区体积分数,2#COREX预还原竖炉炉内死区体积分数达到了26.81%.随着竖炉熔炼率的增加,炉内平均停留时间逐渐减小,无量纲方差逐渐增大.当熔炼率从150 t/h增长到180 t/h时,1#COREX竖炉死区体积分数降幅为68.1%,2#COREX竖炉降幅仅为15.52%.
文摘Anogenital distance （AGD） is used to define degree of virilization of genital development, with shorter length being associated with feminization and male infertility. The first exon of the androgen receptor （AR） consists of a polymorphic sequence of cytosine-adenineguanine （CAG） repeats, with longer CAG repeat lengths being associated with decreased receptor function. We sought to determine if there is an association between AGD and AR CAG repeat length. A cross-sectional, prospective cohort of men evaluated at a urology clinic at a single institution was recruited. AGD （the distance from the posterior scrotum to the anal verge） and penile length （PL） were measured. Sanger DNA sequence analysis was used to define CAG repeat length. AGD and CAG repeat lengths in 195 men were determined. On unadjusted analysis, there was no linear relationship between CAG repeat length and PL （P=0.17） or AGD （P=-0.31）. However, on sub-population analyses, those men with longer CAG repeat lengths （〉26） had significantly shorter AGDs compared to men with shorter CAG repeat lengths. For example, the mean AGD was 41.9 vs. 32.4 mm with a CAG repeat length ≤26 vs. 〉26 （P=0.01）. In addition, when stratifying the cohort based on AGD, those with AGD less than the median （i.e. 40 mm） had a longer CAG repeat length compared to men with an AGD 〉40 mm （P=-0.02）. In summary, no linear relationship was found between AGD and AR CAG repeat length overall.
文摘The term Agriculture Green Development(AGD)was introduced by the 19 th National Congress of China’s CPCC in2017 as a name for the national strategy of sustainable development to realize green development.This national strategy aims at fundamental solutions for the so called three rural issues:(1)agriculture.
