Calculation of nitrogen flow rate
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This post was last edited by ziyouruifeng on 2010-12-21 at 20:38. The required total flow rate of nitrogen is as follows: The nitrogen at 32 barg is divided into two streams: 1) Regulated to 6 barg with a flow rate of 850 Nm3/hr; 2) Regulated to 17 barg with a flow rate of 350 Nm3/hr. Question: What is the flow rate of nitrogen at 32 barg in Nm3/hr, and in m3/hr?
The answer can be obtained using the ideal gas law and mass conservation!
There are two possible scenarios for the question posed by the original poster: 1) If your flow meter displays the flow rate in standard volume units after conversion, then the flow rate has nothing to do with pressure; the flow rate at 32 bar is simply the sum of the two values, which is 1200 Nm3/Hr. 2) If you are dealing with flow rates under different pressure conditions, then pressure correction is necessary. By ignoring changes in temperature and gas properties, the calculation yields V = (17*350 + 6*850)/32 = 345 M3/Hr
The original poster is already in the 5th grade; questions like this should be easy to solve. The unit Nm3 for gas flow rate represents the volume under standard conditions, and it has nothing to do with pressure or temperature. The two people who commented above have already provided the basis for the calculation: the flow rate at 32 bar is simply the sum of those two values, which is 1200 Nm3/Hr. As for converting this value to the volume under the actual pressure, it can be calculated using the ideal gas law. For a simplified calculation (ignoring the effects of temperature and the compressibility factor), one can simply divide by the multiple corresponding to atmospheric pressure (1200/32=37.5). For a more accurate calculation, one needs to know the temperature of the gas at 32 bar, and then use the compressibility factor to calculate the result using the formula PV=ZnRT; you can carry out these calculations yourself, where Z represents the compressibility factor. Just a reminder: the friend in the third comment made a mistake in the second calculation step – 350 and 850 are already in standard cubic units, so there’s no need to multiply them by the pressure multiple
I just think we should have some straightforward, simple calculations! Process design requires calculations! Thank you all for your replies! !
At standard conditions: 1200 Nm3/hr; at 20 degrees Celsius and 32 bar, the flow rate is Q = 38.19 m3/hr, and the density is 37.24 kg/m3