Two steam orifice plate problems (large numerical discrepancies)
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This post was last edited by lianyuer on 2018-6-11 at 15:20. I’m seeking help from experts regarding an issue: we have a orifice plate for medium-pressure steam, which is used for trade settlement purposes. The manufacturer that supplies us with the steam also has an orifice plate, and both are located on the same pipeline at close distances to each other. However, the values obtained from them differ significantly. Could someone please help figure out why this is happening? Previously the values were the same, but since January this year, after the other party replaced the orifice plate, the difference in values became significant – ours are lower while theirs are higher. Their orifice plate values are transmitted to our control room via an MC-integrated recorder; temperature and pressure compensation for their flow meters is carried out within that recorder, while temperature and pressure compensation for our orifice plates is achieved through calculation formulas on the DCS. The attachment contains the data sheets for both companies along with the comparison values; please take a look~~ Thank you everyone~~
Flow computers offer reliable accuracy; using ordinary temperature and pressure compensation with DCS calculation formulas is not effective – it is more reliable to calculate steam density in order to determine volume
Check the parameter settings of the other party’s accumulator
Both calculation sheets are basically fine; the second one is probably more accurate. But there’s one question: the daily traffic volume of over 20 here – does that refer to over 20 tons? If so, the flow rate is too low; it has exceeded the minimum flow limit, and neither orifice plate can be used – an orifice plate replacement is required.
Judging from the data sheet, the flow rate is only 10-20 tons per day; such a flow meter can’t possibly be accurate! Below the minimum measurement range pull
It is best to consider the differential pressure values corresponding to each instantaneous flow rate to see whether they are all within the range for accurate measurement by the flow meter.
Look at the two calculation sheets: one shows a minimum flow rate of 2.5 t/h, while the other shows 1.5 t/h. We should go by the lower value; it’s normal for the flow rate to be below 1.5 t/h. If your data volume is less than 20T per day, that’s far too low even over 24 hours.
It’s not within the accuracy range; adding two more units won’t help either – it still won’t match