总蒸汽流量计算方法

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1、总蒸汽流量计算方法我厂测量总蒸汽的流量计为喷嘴式流量计，它属于差压式的流量计的一种，根据该仪表的原理气体的流量与通过节流元件的差压的开方成正比（k值）.计算公式如下：Qm=kQm:蒸汽的质量流量k：修正值△P：通过喷嘴节流元件前后的差压р:在一定温度一定压力下蒸汽的密度1、由流量计所带仪表（差压变送器）测出通过节流元件的前后差压2、用压力变送器测量出蒸汽管道内蒸汽的压力，用热电阻测量出管道内蒸汽的温度3、机内编写一PO的功能块，其作用是对测量出的蒸汽流量进行密度补偿。即在不同的压力和不同的温度下，选择蒸汽在该温度压力下

2、的密度，以计算出其质量流量。详细取值情况如下（pi蒸汽压力，ti蒸汽温度，mp蒸汽的密度）：IFpi>=0.00ANDpi<=0.025THENIFti<140THENmp:=0.52;ELSIFti>=140ANDti<=150THENmp:=0.52;ELSIFti>150ANDti<=170THENmp:=0.49;ELSIFti>170ANDti<=190THENmp:=0.47;ELSIFti>190ANDti<=210THENmp:=0.45;ELSIFti>210ANDti<=230THENmp:=0.4

3、3;ELSIFti>230ANDti<=250THENmp:=0.42;ELSIFti>250ANDti<=270THENmp:=0.40;ELSIFti>270ANDti<=290THENmp:=0.39;ELSIFti>290ANDti<=310THENmp:=0.37;ELSIFti>310THENmp:=0.36;END_IFELSIFpi>0.025ANDpi<=0.10THENIFti<140THENmp:=0.78;ELSIFti>=140ANDti<=150THENmp:=0.78;ELSIFti>15

4、0ANDti<=170THENmp:=0.74;ELSIFti>170ANDti<=190THENmp:=0.71;ELSIFti>190ANDti<=210THENmp:=0.68;ELSIFti>210ANDti<=230THENmp:=0.65;ELSIFti>230ANDti<=250THENmp:=0.62;ELSIFti>250ANDti<=270THENmp:=0.60;ELSIFti>270ANDti<=290THENmp:=0.58;ELSIFti>290ANDti<=310THENmp:=0.56;

5、ELSIFti>310THENmp:=0.54;END_IFELSIFpi>0.10ANDpi<=0.20THENIFti<140THENmp:=1.32;ELSIFti>=140ANDti<=150THENmp:=1.32;ELSIFti>150ANDti<=170THENmp:=1.25;ELSIFti>170ANDti<=190THENmp:=1.19;ELSIFti>190ANDti<=210THENmp:=1.14;ELSIFti>210ANDti<=230THENmp:=1.09;ELSIFti>230AN

6、Dti<=250THENmp:=1.04;ELSIFti>250ANDti<=270THENmp:=1.00;ELSIFti>270ANDti<=290THENmp:=0.97;ELSIFti>290ANDti<=310THENmp:=0.93;ELSIFti>310THENmp:=0.90;END_IFELSIFpi>0.20ANDpi<=0.28THENIFti<140THENmp:=1.92;ELSIFti>=140ANDti<=150THENmp:=1.92;ELSIFti>150ANDti<=170THENm

7、p:=1.82;ELSIFti>170ANDti<=190THENmp:=1.73;ELSIFti>190ANDti<=210THENmp:=1.65;ELSIFti>210ANDti<=230THENmp:=1.58;ELSIFti>230ANDti<=250THENmp:=1.51;ELSIFti>250ANDti<=270THENmp:=1.45;ELSIFti>270ANDti<=290THENmp:=1.40;ELSIFti>290ANDti<=310THENmp:=1.35;ELSIFti>310THENm

8、p:=1.30;END_IFELSIFpi>0.28ANDpi<=0.33THENIFti<140THENmp:=2.03;ELSIFti>=140ANDti<=150THENmp:=2.03;ELSIFti>150ANDti<=170THENmp:=2.03;ELSIFti>170ANDti<=190THENmp:=1.92;E