孔板流量計算公式

1、孔板流量計的測定與計算在孔板流量計的前后端測出壓差后可按以下兩種方法進行計算；一、可按公式計算出瓦斯流量.計算公式：Q混=KbAh1/2*次1Q純二Q混X式中：Q混抽放的瓦斯混合量,m3/min；Q純抽放的瓦斯純量,m3/min；K實際孔板流量特性系數,計算見2式；b瓦斯?jié)舛刃Ｕ禂?計算見3式；治一一氣壓校正系數,計算見4式；計一一溫度校正系數,計算見5式；Ah在孔板前后端所測之壓差,mmH2O；X混合氣體中瓦斯?jié)舛?%.(2)K=189.76a0mD2式中：a0標準孔板流量系數；m=d1/D2m截面比；D管道直徑,米；di孔板直徑,米；b=1/10.00446X1/23*=Pt/7601/

2、24式中：Pt孔板上風端測得的絕對壓力,mmHg;Pt=測定當地壓力mmHg+該點管內正壓正或負壓負mmH2./13.6760標準大氣壓,mmHg；計=2937273+t1/25式中：t瓦斯管內測點溫度,C；293標準絕對溫度,C；四寸管路d1=49.50mmD=98.28mm貝U:m=0.2536查表一得a0=0.6327K=0.3001六寸管路d1=74.68mmD=151.20mm那么：m=0.2439查表一得a0=0.6294K=0.6718二、在計算過程中為加快計算速度,可把公式中的各項數值表格化,查表得瓦斯?jié)舛刃Ｕ禂礲值表二;瓦斯?jié)舛?%)01234567891.001.001.

3、001.001.001.011.011.0011.011.0202479146911.021.021.021.031.031.031.031.0401.041.04046812581.06635101.041.051.051.051.051.061.061.0951.061.072080368031.12581301.071.071.081.081.081.081.091.1581.091.104047025811.19470501.101.101.101.111.111.111.121.2341.121.136036936921.27881701.131.131.141.141.141.15

4、1.151.3281.161.1680471481424901.161.171.171.171.181.181.191.191.201008269260821.201.211.211.221.221.221.221.231.246040259831.241.251.251.261.261.261.271.281.287160394371.291.291.301.301.311.311.321.331.332728384491.344氣壓校正系數6P值表三;壓力(mmHg)說壓力(mmHg)布壓力(mmHg)4壓力(mmHg)說壓力(mmHg)布1500.442900.6174300.75257

5、00.8667100.96715542950.6234350.7565750.8707150.9701600.453000.6294400.7615800.8747200.97316523050.6334450.7655850.8787250.9771700.453100.6394500.7695900.8817300.98017583150.6434550.7745950.8867350.9841800.463200.6494600.7786000.8897400.98718563250.6544650.7826050.8927450.9901900.473300.6594700.78661

6、00.8967500.99319523350.6634750.7916150.9007550.9972000.483400.6694800.7946200.9037601.00020521021522022523023524024525025526026527027528028503450.6744850.7996250.9077651.0030.483500.6784900.8036300.9107701.00683550.6834950.8076350.9147751.0090.493600.6895000.8116400.9187801.01333650.6935050.8156450.

7、9227851.0160.503700.6985100.8196500.9257901.01903750.7025150.8236550.9287951.0230.503800.7075200.8276600.9328001.02663850.7125250.8316650.9358051.0290.513900.7165300.8356700.9398101.03133950.7205350.8396750.9428151.0340.514000.7255400.8436800.9468201.03794050.7295450.8476850.9498251.0400.524100.7345

8、500.8506900.9538301.04354150.7395550.8546950.9568351.0470.534200.7435600,8587000.9608401.05020.5380.5444250.7485650.8627050.9638451.0530.5560.5620.5680.5740.5790.5850.5900.5960.6010.6072溫度校正系數6T值表四;溫度0123456789C4030200.9680.9660.9640.9630.9610.9600.9580.9570.9550.954100.9830.9820.9800.9790.9770.9750

9、.9740.9720.9710.96901.0000.9980.9970.9950.9930.9920.9900.9880.9870.985-01.0171.0161.0141.0121.0101.0081.0071.0051.0031.001-11.0351.0341.0331.0321.0291.0271.0251.0231.0211.01901.0351.0371.0391.0411.0431.0451.0471.0491.0521.054-21.0561.0581.0591.0611.0631.0661.0681.0701.0721.07401.0761.0781.0801.0831.

10、0851.0861.0891.0911.0941.095-31.0981.0991.1031.1051.1081.1091.1151.1151.1171.11901.1221.1231.1261.1291.1311.1331.1391.1391.1411.143-40例題：某鉆場瓦斯支管路D=25.4mm,孔板直徑di=12.7mm,在井下實測,測得壓差為30mmH2O,瓦斯?jié)舛?0%,測得大氣壓力1.01X105pa,管內負壓0.07Mpa,瓦斯管內溫度為20C,求瓦斯流量解：由公式Q混水為*(Ah)1/2*十求K值m=(d1/D)1/2=(12.7/25.4)1/2=0.25查表一得：a0

11、=0.6417K=0.0190b值查表二得：b=1.074求和值Pt=1.01*105/(9.8*13.6)-0.07*106/(9.8*13.6)=232.6mmHg求8查表三得：加=0.556求燈查表四得：6T=0.983貝UQ混=0.019*1.074*301/2*0.556*0.983=0.061m3/minQ純=Q混*X=0.061*30%=0.0183m3/min(舉例)YD-2型孔板流量計的應用與計算孔板流量計用以測定瓦斯管路中的瓦斯流量(如下列圖)Pi外氣流方向-11111111-1F-一、抽放瓦斯管路中孔板流量計的安裝與使用：(1)、在抽放瓦斯管路中安裝孔板時,孔板的孔口必須

12、與管道同心,其端面與管路軸線垂直,偏心度1-2%;(2)、安裝孔板的管道內壁,在孔板前后距離2D的范圍內,不應有凸凹不平,焊縫和墊片等.(3)、孔板流量計的上游(前端),管道直線長度?20D,下游(后端)長度?10D;(4)、要經常清理孔板前后的積水和污物,孔板銹蝕要更(5)、抽放瓦斯量有較大變化時,應根據流量大小更換相應的孔板.二、應用孔板流量計與計算管道內的瓦斯流量時,必須同時測量的參數：(1)、孔板前后端的壓差值(h);(2)、測量地點的大氣壓力(Pd);(3)、管道內的氣體壓力(Pg),正壓或負壓；(4)、管道內的氣體溫度(t);(5)、管道內的瓦斯?jié)舛?x).三、抽放的混合瓦斯量計算

13、：QH=9.811/2Kb?Zh)1/2?St?8p式中：Qh抽放的混合瓦斯量,m3/min;K孔板系數,取實際校正值；0.3072b瓦斯?jié)舛刃Ｕ?；b=1/(1-0.00446x)1/2x混合瓦斯中的瓦斯?jié)怵?;h孔板前后端壓第；St溫度校正系數；5t=293/(273+t)1/2t管道內的氣體溫度,C；5p-壓力校正系數；5p=(Pt/101,325)1/2Pt-孔板前端管道內的絕對壓力,Kpa;Pt=PDiPG；Pd測量地點的大氣壓力；Pg觀測點管道內的壓力,正壓取(+),負壓取(-),Kpa;101.325標準大氣壓,Kpa.四、抽放的純瓦斯量計算Qc=QhX/100式中Qc抽放的純

14、瓦斯量,m3/min;Qh插放的混合瓦斯量,m3/minX-管道內的瓦斯?jié)舛?.采面鉆場孔板測定數據記錄表年月時間鉆場(#)孑L板前后端的lifeh(KPa)管道內的氣體壓力Pg(KPa)測量地點的大氣壓力Pd(Kpa)管道內的氣體溫度(t)管道內的瓦斯?jié)舛葂(%)備注日班測定時間計算公式：QH=9.81-1/2?Cb7小)1/2?T?P=9.81-1佟0.3072*(1-0.004461)/(Zh)1/2*293/(273+t)1/2*(PbdPG)/101.3251/2管道內的氣體壓力Pg負壓取負值；表一實際孔板流量特性系數K值表管徑D(mm)ma0K0.050.10.150.20.250

15、.30.350.40.450.50.550.60.650.715a00.61550.61920.62570.63350.64260.65320.66540.68150.69920.71920.74060.76730.79610.8223K0.00130.00260.00400.00540.00690.00700.00990.01180.01340.01540.01740.01970.02210.024620a00.61510.61880.62520.63300.64230.65280.66470.68080.69840.71840.73980.76640.79530.8218K0.00230.

16、00470.00710.00960.01220.01250.01770.02070.02390.02730.03090.03490.03930.043725a00.61370.61840.62470.63250.64170.65240.66400.68010.69760.71760.73900.76550.79450.8215K0.00370.00730.01110.01500.01900.02320.02750.03220.03710.04250.04810.05440.06120.068138a00.61370.61730.62340.63130.64020.65120.66240.678

17、30.69540.71540.73710.76330.79230.8208K0.00840.01690.02560.02360.03290.04250.05250.06340.07480.08700.10010.11450.13010.146450a00.61280.61620.62210.62930.63870.64920.66070.67640.69340.71340.73500.76100.79000.8200K0.01450.02920.03330.04870.06330.07990.09720.11590.13550.15670.17930.20410.23110.259875a00

18、.61090.61400.61960.62610.63570.64600.65740.67270.68920.70920.73100.75650.78580.8185K0.03060.06550.09920.13370.16960.206220.24560.28720.33100.37850.42920.48450.54520.6116100a00.60900.61170.61700.62380.63270.64280.65410.66900.68500.70500.72700.75200.78150.8170K0.05780.11610.17550.23660.30010.35470.423

19、10.49650.57360.65760.74610.84360.95130.0726125a00.60780.61050.61600.62230.63100.64110.65240.66750.68350.70320.72520.75000.77940.8145K0.09010.18100.27400.36900.46770.57030.67700.79170.91201.02451.18261.33431.50211.6905150a00.60670.60930.61500.62090.62940.63940.65060.66600.68200.70150.72350.74800.7773

20、0.8120K0.12930.26020.39390.53020.67180.81900.97221.13741.31031.49761.69901.91622.15722.4268175a00.60550.60810.61340.61950.62770.63770.64880.66450.68050.69980.72180.74600.77510.8095K0.17600.35340.53470.72000.91201.11181.31971.54471.78002.03342.30712.60122.92793.2756200a00.60430.60690.61190.61800.62600.63600.64700.66300.67900.69800.72000.74400.77300.8070K0.22940.46070.69790.93821.18791.44831.71892.01302.31932.64913.00583.38843.81384.2651225a00.60350.