Expansion amount calculation
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The question is: For an expander with a designed inlet pressure of 0.55 MPa (absolute pressure), an expansion volume of 7000 cubic meters per hour, and an inlet temperature of -145 degrees Celsius, what is the volumetric flow rate in standard conditions if the inlet temperature is -133 degrees Celsius? How to calculate
First, it is necessary to know the molar volume at each state, and then it will be easy to calculate. 24526 / 2015.8 * 7000 Ans = 85168.17 m3/h
I calculated it using this formula; it gives 6420, which is incorrect
First, search on Baidu to find out what each parameter of this formula represents. The values to be substituted for temperature should be (273-145) and (273-133). Is 7000 in Nm3 or m3? If it is Nm3, then mass conservation doesn’t need to be taken into account. Also, it needs to be determined whether 0.55 Mpa refers to absolute pressure or gauge pressure.
PV=nRT applies to ideal gases. In this state, the gas deviates slightly from an ideal gas, with a compressibility factor of Z≈0.95. Therefore, to obtain accurate calculations, the PR equation should be used.
The title states that it’s absolute pressure; I’ll take another look at the other parameters