Help! Help!
Thread Content
Hello everyone! I’m a new student and would like to ask for help from all you pros. There are two sets of throttling devices (standard nozzles) for measuring superheated steam with a diameter of Φ529*10. One set is designed for maximum/normal/minimum flow rates of 80/64/26.667 t/h, operating at an absolute pressure of 1.08 MPa and a temperature of 285°C, with a differential pressure of 40 KPa. Under current operating conditions, the flow rate ranges from 9 to 24 t/h during early mornings and at night, with a differential pressure between 1 and 2 KPa; during the day, the flow rate is between 21 and 36 t/h, with a differential pressure of 2 to 7 KPa, and the temperature and pressure are around 270°C/0.9 MPa. The other set is designed for maximum/normal/minimum flow rates of 200/100/66.666 t/h, with the same operating temperature and pressure, but a differential pressure of 60 KPa. Under current conditions, the flow rate is around 35 t/h during early mornings and at night, with a differential pressure of 1 to 2 KPa; during the day, it ranges from 60 to 80 t/h, with a differential pressure of 6 to 9 KPa. The range of the differential pressure transmitter is 0 to 30 KPa. Are the designs of these two sets of nozzles reasonable? If there are any deviations, are they too large or too small (especially during early mornings and at night)? Is it possible to calculate the theoretical error?
The actual working conditions deviate too far from the design. It is best to choose a throttle element with a larger differential pressure value and temperature and pressure compensation for the modification. In cases like yours, the values are mostly on the smaller side; there’s hardly any theoretical error. Even if there is any, it isn’t reliable. If the precision requirement is not high, it will suffice for casual use.
The design differential pressure of the nozzle does not match the range set on the transmitter; how can this be measured?
There is a significant difference between actual operating conditions and design conditions; the selected range is too large. It is recommended to re-select the device and add temperature and pressure compensation.