【摘要】：綜采工作面是煤礦粉塵產生量最大的作業(yè)區(qū)域,采煤機割煤時局部粉塵濃度超過國家衛(wèi)生標準數十倍甚至上百倍,對煤礦工人的身體健康和生命安全構成嚴重威脅。因此,綜采工作面的粉塵防治工作已經成為目前煤礦安全生產的難題之一。通過理論分析、現場實測和數值模擬等方法研究了采煤機割煤時綜采工作面的粉塵運移規(guī)律,得出風流是影響粉塵運移的主要因素,即采煤機阻礙及工作面橫截面積變化造成風流擾動進而在采煤機機身上方產生渦流,致使截割粉塵被風流帶入人行道。因此,本文創(chuàng)新性地提出應用雙重空氣幕改善工作面風流分布,空氣幕將渦流阻隔在空氣幕與煤壁之間進而阻止粉塵運移至人行道;采用混合網格方法對綜采工作面幾何模型進行網格劃分,應用數值模擬方法對比研究了單條空氣幕與雙重空氣幕隔塵性能,最后分析出雙重空氣幕最佳工作狀態(tài),主要結論如下:開啟單條空氣幕,綜采工作面風流被空氣幕分向兩側,但空氣幕射流易受工作面氣流而使得射流內部速度分布不均,截割粉塵通過速度低位區(qū)擴散至人行道;開啟雙重空氣幕,近壁側空氣幕削弱遠避側空氣幕對含塵氣流的卷吸作用,同時能夠加強采煤機上方渦流區(qū),粉塵被限定于渦流區(qū)內難以逃逸;空氣幕射流速度大于3m/s,且近壁側空氣幕射流速度等于或者略大于遠壁側空氣幕射流速度,遠壁側空氣幕長度比近壁側空氣幕長度至少長1.2m左右,隔塵性能較好。雙重空氣幕將截割粉塵控制在空氣幕與煤壁之間,然后在二者之間布置一組噴霧系統(tǒng),該系統(tǒng)能夠在空氣幕與煤壁之間形成一道霧化液滴簾,能夠提高霧化液滴對粉塵顆粒的捕獲能力進而提高噴霧降塵效率。應用數值模擬方法研究了雙重空氣幕作用下噴霧系統(tǒng)霧化性能,選定遠壁側空氣幕和近壁側空氣幕長度分別為3.8m和2.6m,出口速度均為5.0m/s,通過改變噴霧參數,得出了參數變化對噴嘴霧化性能的影響規(guī)律,主要結論如下:雙重空氣幕將霧化液滴阻隔在空氣幕與煤壁之間,提高了液滴數量密度;增大噴嘴直徑,霧化液滴粒徑增大,液滴分布區(qū)域增大;增大噴霧壓力,霧化液滴粒徑減小,液滴運動速度增大,然而空氣幕阻隔效果減弱;增大霧化擴散角,霧化液滴粒徑減小,液滴濃度分布均勻,但是液滴運動速度降低;在受限空間內,水質量流量一定時,改變噴嘴直徑、噴霧壓力及霧化擴散角對液滴參數影響有限。通過分析數值模擬結果,給出了與雙重空氣幕匹配的幾組噴霧參數。
[Abstract]:Fully-mechanized coal mining face is the most productive area of coal dust. The local dust concentration of coal miner is tens or even hundreds times higher than the national health standard, which poses a serious threat to the health and life safety of coal miners. Therefore, dust prevention and control in fully mechanized coal face has become one of the difficult problems in coal mine safety production. Through theoretical analysis, field measurement and numerical simulation, this paper studies the law of dust migration in fully-mechanized coal face during coal cutting of shearer, and draws the conclusion that air flow is the main factor affecting dust migration. That is, the obstruction of shearer and the change of cross-sectional area of the working face cause the disturbance of air flow and then produce eddy current over the fuselage of the shearer, which results in the cutting dust being brought into the sidewalk by air flow. Therefore, this paper creatively proposes the application of double air curtain to improve the air flow distribution in the working face. The air curtain blocks the eddy current between the air curtain and the coal wall, and then prevents the dust from moving to the sidewalk. The geometric model of fully mechanized mining face is meshed by using mixed grid method. The dust isolation performance of single air curtain and double air curtain is compared by numerical simulation method. Finally, the optimal working state of double air curtain is analyzed. The main conclusions are as follows: when a single air curtain is opened, the air flow in a fully mechanized mining face is divided into two sides by the air curtain, but the air curtain jet is vulnerable to the air flow at the working face, which makes the velocity distribution of the jet uneven, and the cutting dust diffuses to the sidewalk through the low velocity zone; When the double air curtain is opened, the near wall air curtain weakens the entrainment effect of the remote side air curtain on the dust-containing airflow, at the same time, it can strengthen the eddy current area above the shearer, and the dust is confined to the eddy current zone and is difficult to escape. The jet velocity of the air curtain is more than 3 m / s, and the jet velocity of the air curtain near the wall is equal to or slightly larger than the jet velocity of the air curtain on the far wall. The length of the air curtain on the far side is at least 1.2 m longer than that of the air curtain on the near wall. The double air curtain controls the cutting dust between the air curtain and the coal wall, and then arranges a set of spray systems between the air curtain and the coal wall, which can form a droplet curtain between the air curtain and the coal wall. It can improve the ability of droplets to capture dust particles and improve the efficiency of spray dust reduction. The atomization performance of the spray system under the action of double air curtain was studied by numerical simulation. The length of the distal air curtain and the near wall air curtain were 3.8 m and 2.6 m, respectively, and the outlet velocity was 5.0 m / s. The spray parameters were changed. The main conclusions are as follows: the double air curtain blocks the atomized droplets between the air curtain and the coal wall, which increases the droplet number density; With the increase of the nozzle diameter, the droplet size increases and the droplet distribution area increases, the spray pressure increases, the droplet diameter decreases, the droplet velocity increases, but the air screen barrier effect weakens. With the increase of atomization diffusion angle, the droplet size decreases, the droplet concentration distribution is uniform, but the droplet velocity decreases. In the confined space, the influence of nozzle diameter, spray pressure and atomization diffusion angle on the droplet parameters is limited when the water mass flow rate is constant. By analyzing the numerical simulation results, several groups of spray parameters matching the double air curtain are given.
【學位授予單位】：安徽工業(yè)大學
【學位級別】：碩士
【學位授予年份】：2016
【分類號】：TD714.4

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