气压计几点法测矿井通风阻力的分析.pdf

问 题 探 讨 气压计基点法 测矿井通风阻力的分析 辽宁工程技术大学 王树刚 刘树存 摘 要 对采用气压计基点法测定矿井通风阻力时,巷道阻力常常出现负值及 满足不了测量精度5 要求的原因进行了分析,并导出了受扰动影响时巷道通风阻 力和引起巷道内空气压力波动长度的计算公式,提出采用气压计基点法测定矿井通 风阻力时测量精度可放宽到10 至20 以内。 关键词 动态风阻 静态风阻 矿井通风 基点法 同步法 1 引言 煤矿安全规程 规定生产矿井每3a至 少要进行一次矿井通风阻力测定。目前测定 矿井通风阻力普遍使用精密数字气压计,测 定方法主要分为基点法和同步法两种,较为 常用的还是基点法。气压计测定阻力就是利 用气压计读数测算巷道的静压差Ps,静压差 Ps和位压差Pz、 速压差Pv构成井巷的通风 阻力Pr。 用基点法测定某风道1～2段上的静压 差Ps。若已测得测点1、2在时刻t1、t2的相 对静压为P1、P2;基点气压计在时刻t1、t2 的读数为P01、P02 , 那么 Ps P 1- P2- P 01- P02 由此可看出,静压差仅考虑了基点附近 或地面产生扰动的影响,其它扰动因素如 风门的开启,运提设备的运行、 上下班人员的 集中行走等扰动源都未能考虑进去。从理论 上讲,为了免受井下气压扰动的影响,测定工 作应选在通风状况比较稳定的非生产班内进 行,且避开交接班时间,以便尽量减少井下人 员活动、 风门开启及运提设备开动的影响。 但根据生产矿井的实际情况,上述条件不大 可能得到保证。这样采用基点法测阻时引起 某些巷道的阻力值是动态值,并且其变化是 随机的 〔1〕。然而尽管用基点法测阻误差比 较大,但测定方便,避免了同步法形成的相互 牵制、 速度慢、 测量时间长等缺点,现场测试 中还是广泛采用。根据采用基点法多次测定 矿井通风阻力的经验,其测量精度一般都超 过5 ,测定中还发现局部巷道通风阻力出 现负值。本文将分别就基点法测阻的测算式 中位压差项、 速压差项和静压差项对测算结 果的影响进行分析。 2 基点法的测阻分析 2. 1 位压差项 表达式为Pzρ1 - 2g Z1-Z2 在正常生产情况下,风流的密度变化较 小,且很容易测算;位能差主要决定于两测点 间的标高差,测点的标高值准确与否直接影 响位能差的准确性。然而测点一般很少恰好 选在测量标高点处,这就需要量取所选测点 到测量标高标准点的距离,再推算测点的标 高。对于水平大巷,推算值误差一般不会大, 但对于倾斜巷道或起伏不平的顺槽,测量精 度不高时,往往会引起较大的误差,甚至阻力 会出现负值。如某段巷道的测算数据为 22 煤炭工程师 1997年第6期 COAL ENGINEER No. 6 1997 P1 3 405Pa ;P2 3 407Pa ; P01 - 36pa ;P02 - 40Pa。 ρ1 1. 17kg/ m3;ρ2 1. 16kg/ m3; V1 67. 6m/ min ;V2 56. 3m/ min ; Z1 - 286. 7m;Z2 - 285. 8m。 其阻力计算结果是Pr1 - 2 - 15. 92Pa , 出现了负值。进一步核对知Z2点标高应低 于Z1点标高,再到有关图纸上找到两测点, 根据其邻近的测量标高标准点推算出Z1 - 281. 0m ,Z2 - 283. 1m ,重新算得Pr1 - 2 18. 33Pa。 2. 2 速压差项 表达式为Pvρ 1V 2 1 2 - ρ2V 2 2 2 巷道中的架线,胶带、 风筒等都会影响风 表测风读数。在井巷风流中,由于动能值不 大,动能差更小,其绝对数值在阻力中所占比 重很小,不会引起阻力测定中较大误差对风 阻R或摩擦阻力系数α测值影响较大。但 当测点附近有风门开启时,测点间巷道的阻 力测值会产生较大波动。如测点间距L 76.9m巷道始测点之后与另一巷道连接处 设有风门的阻力测算数据为 P1 4 155Pa ;P2 4 146Pa ; P01 - 9. 8Pa ;P02 - 14Pa ; ρ1 1. 16kg/ m3;ρ2 1. 15kg/ m3; V1 75m/ min ;V2 119m/ min ; S1 8. 69m2;S2 13. 10m2; Z1 - 345. 5m;Z2 - 345. 2m。 其阻力计算结果是Pr1 - 2 0. 11Pa ,阻 力值偏小。根据测定当时的情况,风门附近 有人员作业,判断是由于风门开启造成了风 量变化,V1应修正为179. 4m/ min。 因此巷道通风阻力修正结果为Pr1 - 2 4. 42Pa。 2. 3 静压差项Ps 矿井巷道的摩擦风阻会因胶带运输机的 运转或矿车的运行等扰动因素而引起动态变 化[1]。如设巷道断面积为S m 2 , 周长为U m ,长度为Lm , 摩擦阻力系数为α0 kg/ m3 , 其中风速为Vm/ s。列车长为L1 m L1≤L , 运行速度为Vtm/ s。列车 高为am ,其侧面的摩擦阻力系数αg kg/ m3。列车宽为bm ,其顶面的摩擦阻力系 数为αb kg/ m3。列车的横断面面积为 St ab ,正面阻力系数为C ,列车经过的L1长 度范围内巷道风速为V1m/ s。巷道内空 气的平均密度为ρ kg/ m3 , 风量为Q m 3/ s 。 令 R0α0L U/ S 3 为巷道内无列车通过时 的摩擦风阻, R1α0L1 U -b / S- ab 3 为列车全部进入巷道后在列车长L1范围内 的巷道摩擦风阻, RyL12αaaαbb / S - ab 3 为列车摩擦风阻静态值, RcCρab/ [2 S - ab 3 ]为列车的正面风阻静态值。那么 整列列车在巷道内运行时,巷道总风阻R为 R α0 L -L1 U S 3 α0L1 U - b S - ab 3 [ 2αaL1aαbL1b S - ab 3 Cρab 2 S - ab 3 ] 1 -β 2s g n 1 -β L-L1 L R0R1 R yRc 1 - β 2s g n 1 - β 式中 βVt/V1,列车运行方向与风流方 向相同时, Vt取正值,相反时取负值;s g n1 -β是符号函数 s g n1 -β 1 1 -β 0 0 1 -β 0 - 1 1 -β 0mi 图1 列车运行引起压力坡线变化图 法同上。 巷道内出现新增的总局部动态风阻 Δ R 使两测点间压力分布发生变化,其结果 如在巷道两端设有调节风窗的压力坡线 图[2],如图1所示。采用基点法测阻,两个测 点的静压值不是同时读数,当在某一测点读 数时,如果恰好碰上局部扰动源的影响,会造 成气压计示值极不稳定,比原有压力有所上 升或下降。这样,就使两测点的压力变化不 同步,从而给阻力测算带来较大误差。 根据图1可以估算出巷道受扰动因素影 响引起静压变化的长度范围。设受到局部扰 动影响的某巷道,其断面均匀一致,则速压差 为零,受扰动前巷道通风阻力为 PrP1-P3P21-P23αL UQ2/ S 3 受扰动后巷道通风阻力为 P′ rP′1- P′ 3P21- P23αL UQ2/ S 3 因此 P1-P′ 1- P 3- P′ 3αL U Q 2 -Q2 / S 3 当3断面存在新增的局部动态风阻Δ R 静压发生变化时,如果P1P′ 1,那么受到局部 扰动影响的巷道前方或后方的长度为 L P ′ 3- P3 S 3 αU Q2-Q′ 2 例如某运输大巷断面积S 14m2,周长 U 14. 4m ,摩擦阻力系数α 0. 008kg/ m3, 受扰动前风量Q 48m3/ s ,受扰动时风量 Q′ 47. 5m3/ s ,3断面受扰动时静压与原有 压力差P′ 3- P3 9. 8Pa。则3断面前方受 影响的巷道长度为L 4 889m; 某采区巷道S 10m2;U 13m; α 0. 012kg/ m3;Q 32m3/ s;Q′ 31. 5m3/ s;P′ 3- P3 9. 8Pa. 该巷道3断面前方受扰动影响的长度L 1 979m。 由此可见,当井下出现局部扰动源时,巷 道受影响的范围是比较宽的。这与文献[2] 现场实测的结果相一致,即当采区内部的压 力下降时,而井底车场的基点压力反而上升。 因此采用基点法测阻时,很难消除井下各种 扰动因素的影响。 3 结束语 采用基点法测定矿井通风阻力时,由于 生产矿井各种客观条件一般不可能停产测 阻的限制,测算结果会产生较大的误差。由 位压差项和速压差项造成的阻力偏差或出现 负值,一般比较容易得到修正。但由于井下 各种偶然扰动因素造成的气压波动范围比较 宽,很多情况在测定当时不容易发现,所以静 压差项产生的误差很难得到修正。尽管测量 精度不能满足5 的要求,但参考其它行业 且从工程实际需要来看,测量精度可放宽到 10 至20 以内。笔者认为测定井下通风 主干线的阻力时应尽量采用同步法,测量局 部受扰动影响较小的地段,特别是回风段的 风阻时,可采用省时省力的基点法。 参 考 文 献 1 刘雪峰 1 巷道摩擦风阻的动态分析 1 煤矿安全, 198912 40～43 2 王德明 1 矿井通风阻力测定中的气压监测问题 1 煤炭工程师,19925 18～20 责任编辑 唐自强 42 煤炭工程师 1997年第6期 COAL ENGINEER No. 6 1997 ABSTRACTS IN ENG LISH Development and Experiments of a Drill Mounted on Heading Machine against Outburst in Mechanized Head2 ing Face in Highly gassy and outburst mines In mechanized heading faces in China’s highly gassy and outburst - prone mines ,the advance rate of mechanized drivage is severely restricted by some unsafe factors such as disallowed methane level and outburst of gas and coal. Developed by Chongqing Branch ,CCRI ,a fully hydraulic drill mounted on heading machine ,ing a complete set with the heading machine , can drill boreholes for gas drainage in the front of heading face by its special func2 tions so as to release the potential of outburst and realize rapid drivage safely. Development of a New Dust Removal Device by Grain Sizing of Drill Cuttings The paper briefly describes the aim and significance of the development of a new dust removal device by grain sizing of drill cuttings ,as well as the structure and operation principle of the device. The device has been tested with test results analyzed. Research on Dust Removal by Adding Glue in Water - ampul Stemmming Brief analysis was made for the dust - removal mechanism of waterampul stemming added with glue. Several comparison tests in mines showed that the water - ampul stemming added with glue can lower dust level after blasting more effectively than common wa2 ter - ampul stemming ,the relative efficiency of dust re2 moval can be as high as 97. 5 . Development and Application of FD - 1No. 0. 6/ 60 Low Noise and Contra - rotating Auxiliary Fans The de2 velopment ,experiment and application of a new energy2 saving product recommended by the Coal Industry Min2 istry FD - 1No. 0. 6/ 60 low noise and contra - rotat2 ing auxiliary fans were described in this paper. It was demonstrated by practice that the fan can be used in ven2 tilation for driving large sectional roadways at long dis2 tance ,featured by advantages of large capacity ,high pres2 sure ,low noise ,high efficiency ,compact structure and easy assembling and disassembling compared with the similar products. Study on Optimzation of Branch Air Quantity in Ventilat2 ing Area Optimization isproposed for a new ventila2 tion system ,i. e. the branch air quantity in ventilation area in network can be reagrded as a air quantity region in which a rational branch air quantity can be selected so as to make the resistance of each path be similar and regulat2 ing value of air resistance and energy consumption be low2 est. Meanwhile ,a proper mathematics model has been set up. Taking No. 3 Shaft of Zhongxian Coal Mine as exam2 ple ,the air distribution calculated by the was cor2 rect and reasonable ,thusoptimized the ventilation system. Derivation of the ula Calculating flow Rate with Sprung Water by Boring. The ula calculating inflow rate with sprung water by boring has long been mistaken for empiric ula by many people.By applying the hydraulics principle ,the author demonstrates that the ula is a theoretical one through concrete deduction in this paper. Comparison of Schemes of Coal Mining under Buildings and Determination of Mining Depth in Majiagou Mine A proper mining scheme and mining depth are de2 termined through calculation of the amount of coal deposit under buildings and the remove cost in Majiagou Mine and analysisof the total and output of the mine in the area under buildings. Analysis of Measurement of Mine Ventilation resistance by Base Points with Air Gauge when measuring mine ventilation resistance by base points with air gauge ,the resistance in roadways often appeared as negative values and the measured value could not meet the needof pre2 cision as 5 . The cause was analyzed and ulas were de2 duced to calculate the ventilation resistance when affected by disturbance and the disturbed length of atmospheric pressure in a roadway. It was proposed that the measuring precision can be relaxed to within 10 ～20 when measuring mine ventilation resistance by base points with air gauge. 05 煤炭工程师 1997年第6期 COAL ENGINEER No. 6 1997