Regarding steam orifice plates
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For the saturated steam orifice plate flow meters in our plant, they were designed for a capacity of 18 T/h with a design operating pressure of 0.8 MPa. However, due to a reduction in load, the instantaneous steam flow rate is currently around 4 T/h, with a maximum of 7 T/h. The pressure also fluctuates significantly as a result of frequent shutdowns of the furnace. Does this lead to large measurement errors? Too big or too small? We now want to switch to orifice plates; what range of flow rates should we change to? Please advise.
According to the operating conditions mentioned by LZ, the orifice plate can be used to adjust the flow range. The density of saturated steam at 300 degrees is generally 0.8036 g/l; based on the rate of 7 T/h specified by LZ, the volumetric flow rate is approximately 5.6252 m3/h. A revised range of 0–6 m3 should suffice.
Changing it to a small orifice plate is a bit troublesome; you could consider reducing the flow rate range, for example to 8 T/H, and then calculate the corresponding pressure difference. If that pressure difference is acceptable, you can adjust the pressure measurement range of the differential pressure transmitter. This way, no hardware needs to be changed.