孔板流量計算公式

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：式中:Q=Kb(A式中:Q=Kb(Ah)i/2。6丁混 PTQ=QX純 混(1)Q 抽放的瓦斯混合量，m3/min；混Q 抽放的瓦斯純量，m3/min；純K——實際孔板流量特性系數(shù)，計算見（2）式;b——瓦斯?jié)舛刃Ｕ禂?shù)，計算見（3）式；6——氣壓校正系數(shù)，計算見（4）式；6T——溫度校正系數(shù)，計算見（5）式；△h 在孔板前后端所測之壓差，mmH2O；X——混合氣體中瓦斯?jié)舛龋?。式?K=189.76a0mD2(2)a0-標準孔板流量系數(shù)；m=(d]/D)2m-截面比；D——-管道直徑，米；d1-孔板直徑，米；b=[1/(1-0.00446X)]1/2(3)6=(P/760)1/2(4)式中:p 丄PT孔板上風端測得的絕對壓力，mmHg；PT=測定當?shù)貕毫Γ╩mHg）+[該點管內正壓（正）或負壓（負）（mmH2O）]/13.6760—標準大氣壓，mmHg；6t=293°/(273°+t°)1/2(5)式中:t°———瓦斯管內測點溫度，°C；293°■——標準絕對溫度，C；四寸管路d]=49.50mmD=98.28mm貝I」：m=0.2536查(表一)得a0=O.6327K=0.3001六寸管路d]=74.68mmD=151.20mm貝U：m=0.2439查(表一)得a°=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(shù)值表格化，査表得出b、6、6。pT 瓦斯?jié)舛刃Ｕ禂?shù)b值表二；瓦斯?jié)舛?%)012345678901.0001.0021.0041.0071.0091.0111.0141.00161.0191.021101.0241.0261.0281.0311.0321.0351.0381.0401.0431.045201.0481.0501.0531.0561.0581.0601.0631.0661.0681.071301.0741.0771.0801.0821.0851.0881.0911.0951.0971.100401.1031.1061.1091.1131.1161.1191.1221.1251.1281.131501.1341.1371.1411.1441.1481.1511.1541.1581.1621.164601.1681.1721.1761.1791.1821.1861.1901.1941.1981.202701.2061.2101.2141.2201.2221.2251.2291.2341.2381.243801.2471.2511.2561.2601.2631.2691.2741.2781.2831.287901001.2921.3441.2971.3021.3081.3131.3181.3241.3281.3341.339氣壓校正系數(shù)6值表三;壓力(mmHg)6p壓力(mmHg)6p壓力(mmHg)-p 6p壓力(mmHg)6p壓力(mmHg)6p1500.4442900.6174300.7525700.8667100.9671550.4522950.6234350.7565750.8707150.9701600.4583000.6294400.7615800.8747200.9731650.4663050.6334450.7655850.8787250.9771700.4723100.6394500.7695900.8817300.9801750.4803150.6434550.7745950.8867350.9841800.4883200.6494600.7786000.8897400.9871850.4933250.6544650.7826050.8927450.9901900.5003300.6594700.7866100.8967500.9931950.5063350.6634750.7916150.9007550.9972000.5133400.6694800.7946200.9037601.0002050.5193450.6744850.7996250.9077651.0032100.5253500.6784900.8036300.9107701.0062150.5323550.6834950.8076350.9147751.0092200.5383600.6895000.8116400.9187801.0132250.5443650.6935050.8156450.9227851.0162300.5503700.6985100.8196500.9257901.0192350.5563750.7025150.8236550.9287951.0232400.5623800.7075200.8276600.9328001.0262450.5683850.7125250.8316650.9358051.0292500.5743900.7165300.8356700.9398101.0312550.5793950.7205350.8396750.9428151.034

2600.5854000.7255400.8436800.9468201.0372650.5904050.7295450.8476850.9498251.0402700.5964100.7345500.8506900.9538301.0432750.6014150.7395550.8546950.9568351.0472800.6074200.7435600,8587000.9608401.0502850.6124250.7485650.8627050.9638451.053溫度校正系數(shù)5值表四;溫度C0123 456789400.9680.9660.9640.9630.9610.9600.9580.9570.9550.954300.9830.9820.9800.9790.9770.9750.9740.9720.9710.969201.0000.9980.9970.9950.9930.9920.9900.9880.9870.985101.0171.0161.0141.0121.0101.0081.0071.0051.0031.00101.0351.0341.0331.0321.0291.0271.0251.0231.0211.019-01.0351.0371.0391.0411.0431.0451.0471.0491.0521.054-101.0561.0581.0591.0611.0631.0661.0681.0701.0721.074-201.0761.0781.0801.0831.0851.0861.0891.0911.0941.095-301.0981.0991.1031.1051.1081.1091.1151.1151.1171.119-401.1221.1231.1261.1291.1311.1331.1391.1391.1411.143例題：某鉆場瓦斯支管路D=25.4mm,孔板直徑d1=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20°C，求瓦斯流量？解：由公式Q混=K*b*(Ah)1/2*6p*6T求K值 m=(d]/D)1/2=(12.7/25.4)b=0.25查表一得： a0=0.6417 K=0.0190b值查表二得：b=1.074求6值PT=1.01*105/(9.8*13.6)-0.07*106/(9.8*13.6)=232.6mmHg求6卩查表三得：6=0.556p p求6T查表四得：6t=0.983則Q=0.019*1.074*301/2*0.556*0.983混=0.061m3/minQ=Q*X=0.061*30%=0.0183m3/min純 混(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(如下圖)。Piq臺流右向尸—、 抽放瓦斯管路中孔板流量計的安裝與使用：、在抽放瓦斯管路中安裝孔板時，孔板的孔口必須與管道同心，其端面與管路軸線垂直，偏心度〈1?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。、孔板流量計的上游(前端)，管道直線長度》20D，下游(后端)長度》10D;、要經常清理孔板前后的積水和污物，孔板銹蝕要更換；、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(shù)：、孔板前后端的壓差值(△h)；、測量地點的大氣壓力(P);、管道內的氣體壓力(P)正壓或負壓；、管道內的氣體溫度(t);、管道內的瓦斯?jié)舛?x)。三、抽放的混合瓦斯量計算：Q=9.81/>'K'b'(△h)i^6'6式中：Q 抽放的混合瓦斯量，m"min；K--二二一-孔板系數(shù)，取實際校正值；0.3072b 瓦斯?jié)舛刃Ｕ?shù)；b={1/(1—0.00446x》i/2x 混合瓦斯中的瓦斯?jié)舛龋?；△h 前后端壓差；6 溫度校正系數(shù)；t 6={293/(273+1)}i〃Tt 管道內的氣體溫度，°c；6 壓力校正系數(shù)；P 6=(P/101.325)i/2P――孔板前端管道內的絕對壓力，Kpa;七 Pt=P土P;(+),負壓取P 測量地點的大氣壓力；(+),負壓取PD 觀測點管道內的壓力，正壓取(-),Kpa;101.325 標準大氣壓，Kpa。四、抽放的純瓦斯量計算Qc=QX/100式中Qc 抽放的純瓦斯量，ms/min;Q 抽放的混合瓦斯量，ms/minX-----管道內的瓦斯?jié)舛龋ァ?/p>

采面 鉆場孔板測定數(shù)據記錄表時間鉆場(旳孔板前后端的壓差△h(KPa)PG(KPa)測量地點的大氣壓力P八 D(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-i/2Kb?(Ah)i/2?％?6p=9.81i/*0.3072*(l-0.00446*(^hW羅093/(273+t)d{(P±P)/101.3251/2DG管道內的氣體壓力PG負壓取負值；G（表一）實際孔板流量特性系數(shù)K值表管徑D(mm)1520253850751001251501752002252500.050.10.150.20.250.30.350.40.450.50.61550.00130.61510.00230.61370.00370.61370.00840.61280.01450.61090.03060.60900.05780.60780.09010.60670.12930.60550.17600.60430.22940.60350.28990.60270.35750.60180.43180.60100.51320.61920.00260.61880.00470.61840.00730.61730.01690.61620.02920.61400.06550.61170.11610.61050.18100.60930.26020.60810.35340.60690.46070.60590.58120.60500.71750.60400.86390.60300.02980.62570.63350.64260.65320.66540.68150.69920.71920.00400.62520.00710.62470.01110.62340.02560.62210.03330.61960.09920.61700.17550.61600.27400.61500.39390.61340.53470.61190.69790.61090.88040.61000.08520.60901.31090.60801.55760.00540.63300.00960.63250.01500.63130.02360.62930.04870.62610.13370.62380.23660.62230.36900.62090.53020.61950.72000.61800.93820.61721.18580.61651.46230.61571.77100.61502.10060.00690.64230.01220.64170.01900.64020.03290.63870.06330.63570.16960.63270.30010.63100.46770.62940.67180.62770.91200.62601.18790.62551.50230.62501.85310.62452.24060.62402.66420.00700.65280.01250.65240.02320.65120.04250.64920.07990.64600.206220.64280.35470.64110.57030.63940.81900.63771.11180.63601.44830.63551.83150.63502.25930.63452.73160.63403.24830.00990.66470.01770.66400.02750.66240.05250.66070.09720.6574