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目前,我厂蒸汽计量普遍采用孔板节流,差压变送器取得差压信号,经开方积算器将差压信号开方、累积,得到蒸汽重量流量。计算公式: M_(pmax)=0.01251α_0r_(Re)εd~2(h_(20max)ρ_p)~(1/2)[kg/h] ρ_p为一定压力下饱和蒸汽密度,下标代表压力数值(以下同)。 M_(com)=0.01251α_0r_(Re)εd~2(h_(20com)ρ_p)~(1/2)=0.01251α_0r_(Re)εd~2(h_(20max)ρ_p)~(1/2)(h_(20com)/h_(20max))~(1/2)=M_(pmax)(h_(20com)/h_(20max))~(1/2)[kg/h] (1) 实际差变输出电流I为0～10mA,代表差压为0～h_(20max),因此公式变为M_(com)=M_(pmax)(1/10)~(1/2)[kg/h]。此式是我厂实际使用的流量累积公式,M_(pmax)为流量系数。式中ρ_p是做为定值处理的,没有变化。实
At present, I plant steam metering commonly used orifice throttling, differential pressure transmitter to obtain the differential pressure signal, the square calculator will open the differential pressure signal, cumulative, steam weight flow. The formula is as follows: M pmax = 0.01251α_0r_Re d ε 2 ~ 2 h_20max ρ_p ~ 1/2 [kg / h] ρ_p is the saturated vapor density under a certain pressure, and the subscripts represent the pressure values with). (Com) = 0.01251α_0r_ (Re) εd~2 (h_ (20com) ρ_p) ~ (1/2) = 0.01251α_0r_ (Re) εd~2 (h_ (20max) ρ_p) (20com) / h_ (20max)) ~ (1/2) = M_ (pmax) (h_ (20com) / h_ (20max)) to (1/2) [kg / h] I is 0 to 10 mA, and the differential pressure is 0 to h_ (20max). Therefore, the equation becomes M_com = M_ (pmax) (1/10) to (1/2) [kg / h]. This formula is the cumulative flow of the actual use of our plant formula, M_ (pmax) for the flow coefficient. Where ρ_p is treated as a fixed value, no change. real