二元加重质气固搅拌流化床流化及分选特性
发布时间：2018-09-06 14:56
【摘要】：我国水资源和煤炭分布呈现逆向分布,水资源稀缺问题是制约传统选煤技术的最大问题。干法选煤是将气固两相流态化技术应用于选煤领域的一项新型高效分选技术。其主要特点是以气固两相悬浮体作为分选介质,在细颗粒介质床中均匀通入稳定气流,使颗粒介质流化,形成具有一定密度和似流体性质的气固两相悬浮体,入选物料在流化床中按密度分层,轻物上浮,重物下沉,实现不同密度颗粒的分离。二元加重质气固搅拌流化床中,搅拌系统作用于流化床内,抑制气泡穿过加重质颗粒时相互兼并造成床层局部不稳定。搅拌系统可以有效改善流化床流化效果,使之形成稳定均匀的流化床层。选用石英砂与磁铁矿粉混合构成的宽粒级二元加重质,其中石英砂颗粒用于改善加重质性能,拓宽流化床分选密度。试验使用搅拌流化床操作系统,以空气与石英砂-磁铁矿粉二元加重质混合后形成似流体性质的气固两相悬浮体为分选介质,对二元加重质气固搅拌流化床的流化特性和分选特性进行研究。通过对不同粒度级石英砂和磁铁矿粉构成的二元加重质进行流化试验研究,在静床层高度H=160mm,搅拌转速V=50r/min,流化气速U=1.2Umf的试验条件下,确定最优的石英砂粒度级为0.45-0.3mm和0.3-0.15mm,其与磁铁矿粉的重量比为分别10%和12%时,床层密度标准差值为最小值,分别为Sρ=0.0425和Sρ=0.0454,流化床表现出最优的密度稳定性。通过MATLAB和Origin软件,绘制流化床密度分布云图、压降分布三维图和流化特性曲线等,客观形象展现二元加重质搅拌流化床的流化特性,为分选操作提供理论依据。对二元加重质气固搅拌流化床三个操作参数流化气速、床层高度和搅拌转速逐一进行单因素探索研究,结果表明各个操作因子分别为流化气速U=1.1Umf、床层高度H=160mm和搅拌转速V=75r/min时床层较为稳定。通过Design-Expert软件,运用Box-Behnken响应曲面法,以密度标准差和灰分离析标准差作为评价指标,当试验条件为流化气速U=1.1Umf、床层高度H=160mm和搅拌转速V=75r/min时,此时床层密度标准差Sρ=0.0362,流化床层稳定性接近最优状态。在此最优条件下,对13-6mm和6-5mm的原煤进行分选试验,精煤灰分分别为6.94%和9.50%,灰分离析标准差分别可以达到1.25和1.19,明显优于4mm以下粒度级细粒煤的灰分离析标准差值;可能性偏差E值分别为0.121g/cm~3和0.130g/cm~3,均可以评定试验效果较佳。4mm以下粒度级的细粒煤难以在此条件下实现有效分选。
[Abstract]:The distribution of water resources and coal is in reverse distribution in China. The scarcity of water resources is the biggest problem that restricts the traditional coal preparation technology. Dry coal preparation is a new type of high-efficient separation technology which applies gas-solid two-phase fluidization technology to the field of coal preparation. Its main characteristic is that the gas-solid two-phase suspension is used as the separation medium, and the steady airflow is uniformly entered in the fine granular medium bed, which makes the granular medium fluidized and forms a gas-solid two-phase suspension with a certain density and fluid-like properties. In fluidized bed, the selected materials are stratified according to density, light matter floats, heavy matter sinks, and the particles with different densities are separated. In a binary agitated gas-solid agitated fluidized bed, the mixing system acts on the fluidized bed, which inhibits the mutual annexation of bubbles through the aggravation particles and results in local instability of the bed. The mixing system can effectively improve fluidized bed fluidization effect and form a stable and uniform fluidized bed layer. The mixed quartz sand and magnetite powder are used to form a wide-grained binary admixture in which quartz sand particles are used to improve the aggravation performance and to widen the separation density of fluidized bed. The operation system of agitated fluidized bed was used in the experiment, in which the gas-solid two-phase suspension with fluid-like properties was formed by mixing air with dualistic aggravation of quartz sand and magnetite powder as the separation medium. The fluidization and separation characteristics of binary aggravation gas-solid agitated fluidized bed were studied. The fluidization test of binary aggradation composed of quartz sand and magnetite powder with different granularity was carried out under the conditions of static bed height of 160 mm, stirring speed of 50 r / min and fluidized gas velocity U=1.2Umf. The optimum quartz sand granularity is determined to be 0.45-0.3mm and 0.3-0.15mm. When the weight ratio of quartz sand to magnetite powder is 10% and 12 mm, the standard difference of bed density is minimum, S 蟻 0. 0425 and S 蟻 0. 0454, respectively. The fluidized bed shows optimal density stability. By means of MATLAB and Origin software, the density distribution cloud diagram of fluidized bed, the three dimensional pressure drop diagram and fluidization characteristic curve are drawn. The objective image shows the fluidization characteristic of binary aggravation agitated fluidized bed, which provides the theoretical basis for sorting operation. The fluidized gas velocity, bed height and stirring speed were studied one by one in a binary aggravation gas-solid agitated fluidized bed. The results show that the operating factors are fluidized gas velocity U 1. 1 Umf, bed height H=160mm and stirring speed V=75r/min respectively. By using Box-Behnken response surface method and Design-Expert software, the density standard deviation and ash segregation standard deviation are used as evaluation indexes, when the fluidized gas velocity U1.1 Umf, bed height H=160mm and stirring speed V=75r/min are used as the test conditions. At this time, the bed density standard deviation S 蟻 0.0362, the stability of fluidized bed is close to the optimal state. Under the optimum conditions, the ash content of 13-6mm and 6-5mm coal is 6.94% and 9.50% respectively, and the standard deviation of ash segregation can reach 1.25 and 1.19 respectively, which is obviously superior to the standard difference of ash segregation of fine coal below 4mm. The possibility deviation E value is 0.121g/cm~3 and 0.130g / cm ~ (-1), respectively, which can be used to evaluate that the fine coal with particle size below .4mm is difficult to realize effective separation under this condition.
【学位授予单位】：中国矿业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TD94;TD45
[Abstract]:The distribution of water resources and coal is in reverse distribution in China. The scarcity of water resources is the biggest problem that restricts the traditional coal preparation technology. Dry coal preparation is a new type of high-efficient separation technology which applies gas-solid two-phase fluidization technology to the field of coal preparation. Its main characteristic is that the gas-solid two-phase suspension is used as the separation medium, and the steady airflow is uniformly entered in the fine granular medium bed, which makes the granular medium fluidized and forms a gas-solid two-phase suspension with a certain density and fluid-like properties. In fluidized bed, the selected materials are stratified according to density, light matter floats, heavy matter sinks, and the particles with different densities are separated. In a binary agitated gas-solid agitated fluidized bed, the mixing system acts on the fluidized bed, which inhibits the mutual annexation of bubbles through the aggravation particles and results in local instability of the bed. The mixing system can effectively improve fluidized bed fluidization effect and form a stable and uniform fluidized bed layer. The mixed quartz sand and magnetite powder are used to form a wide-grained binary admixture in which quartz sand particles are used to improve the aggravation performance and to widen the separation density of fluidized bed. The operation system of agitated fluidized bed was used in the experiment, in which the gas-solid two-phase suspension with fluid-like properties was formed by mixing air with dualistic aggravation of quartz sand and magnetite powder as the separation medium. The fluidization and separation characteristics of binary aggravation gas-solid agitated fluidized bed were studied. The fluidization test of binary aggradation composed of quartz sand and magnetite powder with different granularity was carried out under the conditions of static bed height of 160 mm, stirring speed of 50 r / min and fluidized gas velocity U=1.2Umf. The optimum quartz sand granularity is determined to be 0.45-0.3mm and 0.3-0.15mm. When the weight ratio of quartz sand to magnetite powder is 10% and 12 mm, the standard difference of bed density is minimum, S 蟻 0. 0425 and S 蟻 0. 0454, respectively. The fluidized bed shows optimal density stability. By means of MATLAB and Origin software, the density distribution cloud diagram of fluidized bed, the three dimensional pressure drop diagram and fluidization characteristic curve are drawn. The objective image shows the fluidization characteristic of binary aggravation agitated fluidized bed, which provides the theoretical basis for sorting operation. The fluidized gas velocity, bed height and stirring speed were studied one by one in a binary aggravation gas-solid agitated fluidized bed. The results show that the operating factors are fluidized gas velocity U 1. 1 Umf, bed height H=160mm and stirring speed V=75r/min respectively. By using Box-Behnken response surface method and Design-Expert software, the density standard deviation and ash segregation standard deviation are used as evaluation indexes, when the fluidized gas velocity U1.1 Umf, bed height H=160mm and stirring speed V=75r/min are used as the test conditions. At this time, the bed density standard deviation S 蟻 0.0362, the stability of fluidized bed is close to the optimal state. Under the optimum conditions, the ash content of 13-6mm and 6-5mm coal is 6.94% and 9.50% respectively, and the standard deviation of ash segregation can reach 1.25 and 1.19 respectively, which is obviously superior to the standard difference of ash segregation of fine coal below 4mm. The possibility deviation E value is 0.121g/cm~3 and 0.130g / cm ~ (-1), respectively, which can be used to evaluate that the fine coal with particle size below .4mm is difficult to realize effective separation under this condition.
【学位授予单位】：中国矿业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TD94;TD45
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