Measurement of steam
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Our company’s steam metering always shows large errors. I wonder, guys, how is your steam metering? Most of the steam flow meters in our company are orifice plates
We also use orifice plates; it seems that the error is particularly large when the flow rate is low
It is more economical and reasonable to use vortex flow meters for diameters below 250, while orifice plates are better suited for larger diameters. There are several reasons why this is not allowed; steam measurement requires consideration of saturation and superheating, and superheating necessitates temperature and pressure compensation.
What the original poster said makes sense; we do the same thing – for larger diameters, we use orifice flow meters, while for smaller ones, we opt for socket welding. . After the system was put into operation, the steam flow rate was much lower than the design value, which is impossible according to calculations. It can only be attributed to inaccurate gauge measurements.
There are many reasons why it’s not allowed; are the parameters accurate? Was the compensation done correctly? When the flow rate is low, the error is significant; in such cases, segmented measurement can be employed. Have the orifice plate manufacturer calculate a new formula for low-flow conditions, and use two transmitters to carry out segmented measurement. Without calibration, the orifice plate still has the highest accuracy.
The range ratio of standard orifice plates is too small, the pressure difference is high, and a high Reynolds number is required; as a result, significant errors occur in situations involving low pressure and low flow rates, or when there are large variations in load. Our factory has long since phased them out in favor of integrated vortex street and balanced orifice plate systems, which yield fairly good results.
For measuring steam, ISA1932 nozzles can be used; compared to orifice plates, they have a smoother inlet surface that is less prone to deformation, resulting in lower pressure losses (0.6 times those of orifice plates). They are also resistant to impacts and do not deform easily, with a long calibration period of four years