Are the data obtained from the orifice plate flowmeter data sheet at standard conditions or under actual operating conditions?
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This post was last edited by liu530014416 on 2023-2-20 at 10:04. Dear teachers, a orifice flow meter is to be installed on-site; the differential pressure transmitter brand is Yokogawa. The on-site measurement range is set to 0-6 Kpa, with the gauge reading taking the square root. The DCS measurement range is set to 0-20000 Nm3/h, and no compensation is applied to the DCS values. The DCS displays a measurement value of 9300. Does this value refer to the flow rate at a pressure of 0.22 Mpa and a temperature of 50°C, or to the flow rate under standard conditions, or yet to the flow rate under actual operating conditions (with a pressure of 0.2 Mpa and a temperature of 21.5°C)? Does the DCS need to compensate for this flow rate, temperature, and pressure?
Per the manufacturer, pressure correction is required if the pressure is not at the design value.
If the DCS range is set to 0-20,000 Nm3/h, then the measured value of 9,300 represents the flow rate under standard conditions. Since the medium is gas, temperature and pressure compensation should be performed ； This compensation calculation should already be included in the DCS flow calculation module (the flow calculation formula includes the actual operating pressure and temperature variables of the medium), so no additional temperature and pressure compensation calculation is required.
The DCS does nothing to this flow rate, although the unit is Nm3/h
To perform temperature and pressure compensation, it seems that the popup panel in your image corresponds to Zhejiang University’s DCS system; you can directly use the ideal gas compensation function block “PTCOMPX” for this purpose.
If the process conditions are controlled at the design values of 0.22 Mpa and 50°C, with the DCS set to a range of 0-20000, then the flow rate measured is the flow rate under standard conditions, right? Is that how it should be understood?
Teacher, there is a Yokogawa vortex flow meter on site used to measure the flow rate of saturated steam, with the output in terms of volume flow rate. There is also a pressure transmitter near the flow meter; which module should be used to convert this value into mass flow rate? Since the density of steam changes when its pressure changes, will the calculated mass flow rate of steam be accurate?
No compensation was made; the orifice plate was manufactured at 0.22 MPa and 50°C. Based on the description, what is indicated is the nominal value
Steam flow meters have a dedicated steam flow compensation function block, which is located right below the ideal gas function block; its name should be STMCOMXP – I can’t remember it exactly. Both temperature and pressure compensation must be performed; the mass flow rate obtained after compensation is then accurate.
After correction and compensation, what should be displayed on the DSC is the square root