I have a rather expensive problem, and would like to ask for a sanity check.
There is a DN250 oxygen line feeding our plant (it's a Steel plant with Electric arc furnaces), and the existing metering system is Orifice based, with pressure and temperature compensation. The supplier has declared the measurement system to be accurate enough over a 10:1 turndown starting from the peak flow rate of 23,000Nm3/hr. Below the minimum, the flow shall be deemed to be at the minimum. That is, once the supply valve is open, we are charged at 2,300Nm3/hr, whether we use it or not. The trouble is, we often run at 500Nm3 to 1000Nm3/hr when the plant is on standby.
The oxygen pressure is around 20 bar.
I have suggested to the supplier that our company pay for the installation of a better metering system, so that we are more likely to pay for what we use (obviously he is not keen to do this, since now he is making a fine profit...), and to that end, I put forward several coriolis mass flow catalogues. Fortunately for us, the contract has one little line that says we can do this. Their answer was that 'head office' doesn't approve those type of meters for custody transfer, which I thought was 'curious'.
The questions that I would like to put to you are as follows:
What is so wrong with Coriolis measurement, that a major oxygen supplier would refrain from using it? I assume for the time being that the head office is being quoted correctly.
What other metering options/ piping systems are possible?
Of course, we have them checking what options there are, but all the same, I would like to get some parallel comments.
Thank you.
There is a DN250 oxygen line feeding our plant (it's a Steel plant with Electric arc furnaces), and the existing metering system is Orifice based, with pressure and temperature compensation. The supplier has declared the measurement system to be accurate enough over a 10:1 turndown starting from the peak flow rate of 23,000Nm3/hr. Below the minimum, the flow shall be deemed to be at the minimum. That is, once the supply valve is open, we are charged at 2,300Nm3/hr, whether we use it or not. The trouble is, we often run at 500Nm3 to 1000Nm3/hr when the plant is on standby.
The oxygen pressure is around 20 bar.
I have suggested to the supplier that our company pay for the installation of a better metering system, so that we are more likely to pay for what we use (obviously he is not keen to do this, since now he is making a fine profit...), and to that end, I put forward several coriolis mass flow catalogues. Fortunately for us, the contract has one little line that says we can do this. Their answer was that 'head office' doesn't approve those type of meters for custody transfer, which I thought was 'curious'.
The questions that I would like to put to you are as follows:
What is so wrong with Coriolis measurement, that a major oxygen supplier would refrain from using it? I assume for the time being that the head office is being quoted correctly.
What other metering options/ piping systems are possible?
Of course, we have them checking what options there are, but all the same, I would like to get some parallel comments.
Thank you.
