综采工作面双重空气幕控尘技术数值模拟研究
发布时间：2019-02-23 16:33
【摘要】：综采工作面是煤矿粉尘产生量最大的作业区域,采煤机割煤时局部粉尘浓度超过国家卫生标准数十倍甚至上百倍,对煤矿工人的身体健康和生命安全构成严重威胁。因此,综采工作面的粉尘防治工作已经成为目前煤矿安全生产的难题之一。通过理论分析、现场实测和数值模拟等方法研究了采煤机割煤时综采工作面的粉尘运移规律,得出风流是影响粉尘运移的主要因素,即采煤机阻碍及工作面横截面积变化造成风流扰动进而在采煤机机身上方产生涡流,致使截割粉尘被风流带入人行道。因此,本文创新性地提出应用双重空气幕改善工作面风流分布,空气幕将涡流阻隔在空气幕与煤壁之间进而阻止粉尘运移至人行道;采用混合网格方法对综采工作面几何模型进行网格划分,应用数值模拟方法对比研究了单条空气幕与双重空气幕隔尘性能,最后分析出双重空气幕最佳工作状态,主要结论如下:开启单条空气幕,综采工作面风流被空气幕分向两侧,但空气幕射流易受工作面气流而使得射流内部速度分布不均,截割粉尘通过速度低位区扩散至人行道;开启双重空气幕,近壁侧空气幕削弱远避侧空气幕对含尘气流的卷吸作用,同时能够加强采煤机上方涡流区,粉尘被限定于涡流区内难以逃逸;空气幕射流速度大于3m/s,且近壁侧空气幕射流速度等于或者略大于远壁侧空气幕射流速度,远壁侧空气幕长度比近壁侧空气幕长度至少长1.2m左右,隔尘性能较好。双重空气幕将截割粉尘控制在空气幕与煤壁之间,然后在二者之间布置一组喷雾系统,该系统能够在空气幕与煤壁之间形成一道雾化液滴帘,能够提高雾化液滴对粉尘颗粒的捕获能力进而提高喷雾降尘效率。应用数值模拟方法研究了双重空气幕作用下喷雾系统雾化性能,选定远壁侧空气幕和近壁侧空气幕长度分别为3.8m和2.6m,出口速度均为5.0m/s,通过改变喷雾参数,得出了参数变化对喷嘴雾化性能的影响规律,主要结论如下:双重空气幕将雾化液滴阻隔在空气幕与煤壁之间,提高了液滴数量密度;增大喷嘴直径,雾化液滴粒径增大,液滴分布区域增大;增大喷雾压力,雾化液滴粒径减小,液滴运动速度增大,然而空气幕阻隔效果减弱;增大雾化扩散角,雾化液滴粒径减小,液滴浓度分布均匀,但是液滴运动速度降低;在受限空间内,水质量流量一定时,改变喷嘴直径、喷雾压力及雾化扩散角对液滴参数影响有限。通过分析数值模拟结果,给出了与双重空气幕匹配的几组喷雾参数。
[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.
【学位授予单位】：安徽工业大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：TD714.4
本文编号：2429006
[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.
【学位授予单位】：安徽工业大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：TD714.4
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