本文選題：等厚篩分 + 彈性篩分�。� 參考：《中國礦業(yè)大學(xué)》2017年博士論文

【摘要】：煤炭是我國的主要一次能源,選煤是實(shí)現(xiàn)煤炭高效清潔利用和可持續(xù)發(fā)展的基礎(chǔ)和前提,是潔凈煤技術(shù)最經(jīng)濟(jì)有效的方法,篩分作業(yè)是選煤工藝的關(guān)鍵環(huán)節(jié)。采用傳統(tǒng)等振幅剛性篩分方法進(jìn)行潮濕煤炭干法深度分級時,入料端物料堆積、篩面堵孔嚴(yán)重、分級效果差、篩分作業(yè)難以順利進(jìn)行,難以滿足現(xiàn)代大型選煤廠高效集約化的生產(chǎn)要求。為解決上述問題,本文將變振幅等厚篩分方法與多自由度彈性篩分方法相結(jié)合,提出變振幅等厚彈性篩分方法,優(yōu)化篩上料群分布,提高篩面的利用率,強(qiáng)化粘濕煤炭的松散與分層,消除篩面的堵孔,從而實(shí)現(xiàn)潮濕煤炭的高效干法深度篩分。通過理論分析建立了大跨距變振幅等厚篩動力學(xué)模型,基于多自由度振動理論建立了質(zhì)心運(yùn)動的三自由度振動微分方程,得到了質(zhì)心和篩體任意位置的位移方程式。通過振動測試分析了大跨距變振幅等厚篩不同運(yùn)行階段運(yùn)動學(xué)特性及穩(wěn)態(tài)運(yùn)行時沿料流方向篩體不同區(qū)域的空間運(yùn)動軌跡。振動篩啟動和停機(jī)階段出現(xiàn)較大振動和擺動;過渡運(yùn)行階段,出現(xiàn)拍振現(xiàn)象,振幅逐漸降低至工作振幅;穩(wěn)態(tài)運(yùn)行時篩體各區(qū)域的運(yùn)動軌跡均為橢圓,自入料端至出料端,平行篩面方向振幅差異較小,垂直篩面方向振幅逐漸減小,橢圓長軸與平行篩面方向的夾角逐漸減小。采用大跨度不平衡激振方法可以實(shí)現(xiàn)沿料流方向篩面振幅的遞減,且隨激振力系數(shù)、激振梁相對跨距增大,篩體各區(qū)域平行篩面方向振幅均逐漸增大,垂直篩面方向入料端振幅逐漸增大,出料端振幅逐漸減小,且兩者差異逐漸增大�；诟咚贁z像及圖片分析技術(shù)研究了變振幅等厚篩篩面不同區(qū)域顆粒運(yùn)動學(xué)特性及料群分布特性,揭示了變振幅等厚篩分形成機(jī)理:入料端振動強(qiáng)度大,強(qiáng)化了料群顆粒的松散和運(yùn)移,料群在篩面上迅速鋪展,出料端振動強(qiáng)度小,顆粒運(yùn)移速度變慢,料群停留時間增長,因而使得篩上料層趨于等厚。提出了多段采樣分析方法,分析了不同粒級物料在篩面各區(qū)域的透篩規(guī)律,揭示了變振幅等厚篩分強(qiáng)化料群分級機(jī)制。激振力系數(shù)、激振梁相對跨距的變化引起了料群篩分時間、運(yùn)移速度及透篩分布的改變,促使了篩上料層分布的時空演變:入厚出薄→近似等厚→入薄出厚,進(jìn)而影響了物料的篩分效果�；谏鲜鲅芯�,通過對變振幅剛性篩分顆粒運(yùn)移速度及篩上料層分布進(jìn)行調(diào)控,可以實(shí)現(xiàn)低水分煤炭的變振幅等厚高效深度篩分。設(shè)計(jì)了剛?cè)狁詈蠌椥詶U篩面,分析了簡諧位移激勵下剛?cè)狁詈蠌椥詶U運(yùn)動學(xué)特性,給出了彈性管位移幅值表達(dá)式及料流方向篩孔尺寸值域。借助高速攝像捕捉分析了彈性篩分過程中剛?cè)狁詈蠌椥詶U運(yùn)動行為、潮濕煤炭料群空間分布及行為特征,進(jìn)而揭示了堵孔消除機(jī)制:剛性桿與側(cè)板圓孔及彈性管的接觸碰撞引起了彈性管加速度幅值統(tǒng)計(jì)平均值的增大,強(qiáng)化了料群的松散,使得粘附的細(xì)粒物料從粗顆粒表面脫除;彈性管的空間旋轉(zhuǎn)對粘附成團(tuán)顆粒及覆蓋膜產(chǎn)生剪切作用;相鄰彈性管空間位置的改變及其彈性變形,使得篩孔尺寸值產(chǎn)生類周期性波動,加之彈性管對與其接觸的物料作用力方向隨機(jī),使得成團(tuán)顆粒及覆蓋膜破裂、卡堵顆粒從篩孔脫離。研究了工藝參數(shù)及入料特性對等振幅剛?cè)狁詈蠌椥詶U篩6 mm分級效果的影響規(guī)律,確定了操作參數(shù)的最佳取值范圍。提出了變振幅等厚彈性篩分方法,采用單因素試驗(yàn)研究了激振力系數(shù)、激振梁相對跨距對變振幅等厚彈性篩分效果的影響并確定相應(yīng)的最佳因素水平。通過分析選取了對變振幅等厚彈性篩分影響顯著的試驗(yàn)因素,采用多因素響應(yīng)面篩分試驗(yàn)分析了各因素對篩分效果的影響顯著性及交互作用,建立了篩分效率與上述因素之間的關(guān)聯(lián)模型。根據(jù)關(guān)聯(lián)模型分析確定了最佳操作條件,對內(nèi)蒙古鄂爾多斯潮濕煤炭進(jìn)行了6 mm變振幅等厚彈性篩分試驗(yàn),篩分效率為87.79%,總錯配物含量為6.77%,篩分效率試驗(yàn)值與模型預(yù)測值接近,驗(yàn)證了關(guān)聯(lián)模型預(yù)測結(jié)果的準(zhǔn)確性,表明采用變振幅等厚彈性篩分技術(shù)可以實(shí)現(xiàn)潮濕煤炭的高效干法深度篩分。
[Abstract]:Coal is the primary energy of our country. Coal preparation is the basis and prerequisite for efficient clean utilization and sustainable development of coal. It is the most economical and effective method of clean coal technology. Screening operation is the key link of coal preparation process. In order to solve the problems mentioned above, the variable amplitude equal thickness sieving method and the multi degree of freedom elastic sieving method are combined to solve the above problems. The variable amplitude and equal thickness elastic screening method is proposed to optimize the distribution of the material on the sieve. In order to improve the utilization of the screen surface, strengthen the loosening and stratification of the sticky coal and eliminate the plugging of the sieve surface, the high efficient dry method of sieving the wet coal is realized. The dynamic model of the thick sieves with large span and variable amplitude is established by theoretical analysis. Based on the theory of multi degree of freedom vibration, the three degree of freedom vibration differential equation of the mass center motion is established. The displacement equations of the centroid and the sieves at any position are analyzed. By the vibration test, the kinematic characteristics of the different stages of the large span and variable amplitude sieves and the different regions of the sieves in the direction of the steady state are analyzed. The vibration and swing of the sieves in the starting and stopping stages of the vibrating screen are larger than that in the stage of the starting and stopping of the vibrating screen. The amplitude of the amplitude gradually decreases to the working amplitude, and the motion trajectory of the sieves in the steady state is ellipse, from the end to the discharge end, the amplitude of the parallel screen direction is smaller, the amplitude of the vertical screen direction decreases gradually, and the angle between the elliptical long axis and the direction of the parallel screen gradually decreases. The method of large span unbalance excitation can be realized. At present, the amplitude of the sieve surface is decreasing along the direction of the material flow, and with the excitation force coefficient, the relative span of the excitation beam increases, the amplitude of the parallel sieve surface in each area of the sieves increases gradually, the amplitude of the vertical sieve surface increases gradually, the amplitude of the discharge end decreases gradually, and the difference of the two sides gradually increases. The kinematic characteristics and distribution characteristics of the particles in different regions of the sieves and sieves are revealed. The vibration intensity of the variable amplitude is large, and the loosening and migration of the particles are strengthened. The material group is spread rapidly on the sieve surface, the vibration intensity of the discharge end is small, the speed of the grain migration is slow, and the residence time of the material group is increased, thus the residence time of the material group is increased. A multi section sampling analysis method was put forward, and the screening law of different grain grade materials in each area of the screen was analyzed. The classification mechanism of the variable amplitude and equal thickness sieving reinforcement group was revealed. The excitation coefficient, the change of the relative span of the excited beam caused the change of the screening time, the movement speed and the distribution of the screen. The space-time evolution of the distribution of the material layer on the screen: the thickness of the thick, approximately equal thickness and thinning out of the thickness, and then the screening effect of the material. Based on the above research, the variable amplitude and high efficiency depth sieving of the variable amplitude and equal thickness of the low moisture coal can be realized by adjusting the velocity of the particle movement of the variable amplitude rigid screen and the distribution of the material layer on the sieve. The kinematic characteristics of rigid flexible coupling elastic rod under simple harmonic displacement are analyzed, and the displacement amplitude expression of elastic tube and the size range of sieve hole size in the direction of material flow are given. The motion behavior of rigid flexible coupling elastic rod in the process of elastic screening, the spatial distribution and behavior characteristics of damp coal material group are analyzed with the help of high speed camera. The mechanism of plugging removal is revealed: the contact collision between the rigid rod and the circular hole and the elastic tube causes the increase of the statistical average of the acceleration amplitude of the elastic tube, the loosening of the material group and the removal of the adhesive particles from the surface of the coarse particles; the space rotation of the elastic tube produces the shear effect on the adherent particles and the covering film; the adjacent projectile is adjacent to the elastic tube. The change of the space position of the tube and its elastic deformation make the size of the sieve size fluctuate periodically, and the force direction of the material that the elastic tube is exposed to is random, which makes the pellets and the covering film broken and the plugging particles are separated from the sieve hole. The 6 mm points of the process parameters and the feeding characteristics are studied. The optimal range of the effect of the level effect is determined. The variable amplitude equal thickness elastic sieving method is put forward. The effect of the excitation force coefficient, the relative span of the excited beam on the variable amplitude equal thickness elastic sieving effect and the corresponding optimum factor level are studied by single factor test. The variable amplitude equal thickness is selected by analysis. The effect of multiple factor response surface screening test was used to analyze the impact significance and interaction of various factors on the screening effect. The correlation model between the screening efficiency and the factors mentioned above was established. The optimum operating strip was determined according to the correlation model, and 6 wet coal in Ordos, Inner Mongolia, was carried out. The MM variable amplitude and equal thickness elastic screening test, the screening efficiency is 87.79%, the total mismatch content is 6.77%, the sieving efficiency test value is close to the model prediction value, which verifies the accuracy of the prediction results of the correlation model. It shows that the variable amplitude and equal thickness elastic sieving technology can be used to achieve the efficient dry method of sieving wet coal carbon.

【學(xué)位授予單位】：中國礦業(yè)大學(xué)
【學(xué)位級別】：博士
【學(xué)位授予年份】：2017
【分類號】：TD94

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