二元加重質(zhì)氣固攪拌流化床流化及分選特性
發(fā)布時(shí)間：2018-09-06 14:56
【摘要】：我國(guó)水資源和煤炭分布呈現(xiàn)逆向分布,水資源稀缺問(wèn)題是制約傳統(tǒng)選煤技術(shù)的最大問(wèn)題。干法選煤是將氣固兩相流態(tài)化技術(shù)應(yīng)用于選煤領(lǐng)域的一項(xiàng)新型高效分選技術(shù)。其主要特點(diǎn)是以氣固兩相懸浮體作為分選介質(zhì),在細(xì)顆粒介質(zhì)床中均勻通入穩(wěn)定氣流,使顆粒介質(zhì)流化,形成具有一定密度和似流體性質(zhì)的氣固兩相懸浮體,入選物料在流化床中按密度分層,輕物上浮,重物下沉,實(shí)現(xiàn)不同密度顆粒的分離。二元加重質(zhì)氣固攪拌流化床中,攪拌系統(tǒng)作用于流化床內(nèi),抑制氣泡穿過(guò)加重質(zhì)顆粒時(shí)相互兼并造成床層局部不穩(wěn)定。攪拌系統(tǒng)可以有效改善流化床流化效果,使之形成穩(wěn)定均勻的流化床層。選用石英砂與磁鐵礦粉混合構(gòu)成的寬粒級(jí)二元加重質(zhì),其中石英砂顆粒用于改善加重質(zhì)性能,拓寬流化床分選密度。試驗(yàn)使用攪拌流化床操作系統(tǒng),以空氣與石英砂-磁鐵礦粉二元加重質(zhì)混合后形成似流體性質(zhì)的氣固兩相懸浮體為分選介質(zhì),對(duì)二元加重質(zhì)氣固攪拌流化床的流化特性和分選特性進(jìn)行研究。通過(guò)對(duì)不同粒度級(jí)石英砂和磁鐵礦粉構(gòu)成的二元加重質(zhì)進(jìn)行流化試驗(yàn)研究,在靜床層高度H=160mm,攪拌轉(zhuǎn)速V=50r/min,流化氣速U=1.2Umf的試驗(yàn)條件下,確定最優(yōu)的石英砂粒度級(jí)為0.45-0.3mm和0.3-0.15mm,其與磁鐵礦粉的重量比為分別10%和12%時(shí),床層密度標(biāo)準(zhǔn)差值為最小值,分別為Sρ=0.0425和Sρ=0.0454,流化床表現(xiàn)出最優(yōu)的密度穩(wěn)定性。通過(guò)MATLAB和Origin軟件,繪制流化床密度分布云圖、壓降分布三維圖和流化特性曲線等,客觀形象展現(xiàn)二元加重質(zhì)攪拌流化床的流化特性,為分選操作提供理論依據(jù)。對(duì)二元加重質(zhì)氣固攪拌流化床三個(gè)操作參數(shù)流化氣速、床層高度和攪拌轉(zhuǎn)速逐一進(jìn)行單因素探索研究,結(jié)果表明各個(gè)操作因子分別為流化氣速U=1.1Umf、床層高度H=160mm和攪拌轉(zhuǎn)速V=75r/min時(shí)床層較為穩(wěn)定。通過(guò)Design-Expert軟件,運(yùn)用Box-Behnken響應(yīng)曲面法,以密度標(biāo)準(zhǔn)差和灰分離析標(biāo)準(zhǔn)差作為評(píng)價(jià)指標(biāo),當(dāng)試驗(yàn)條件為流化氣速U=1.1Umf、床層高度H=160mm和攪拌轉(zhuǎn)速V=75r/min時(shí),此時(shí)床層密度標(biāo)準(zhǔn)差Sρ=0.0362,流化床層穩(wěn)定性接近最優(yōu)狀態(tài)。在此最優(yōu)條件下,對(duì)13-6mm和6-5mm的原煤進(jìn)行分選試驗(yàn),精煤灰分分別為6.94%和9.50%,灰分離析標(biāo)準(zhǔn)差分別可以達(dá)到1.25和1.19,明顯優(yōu)于4mm以下粒度級(jí)細(xì)粒煤的灰分離析標(biāo)準(zhǔn)差值;可能性偏差E值分別為0.121g/cm~3和0.130g/cm~3,均可以評(píng)定試驗(yàn)效果較佳。4mm以下粒度級(jí)的細(xì)粒煤難以在此條件下實(shí)現(xiàn)有效分選。
[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.
【學(xué)位授予單位】：中國(guó)礦業(yè)大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2017
【分類號(hào)】：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.
【學(xué)位授予單位】：中國(guó)礦業(yè)大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2017
【分類號(hào)】：TD94;TD45
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