Expander, Energy, enthalpy,
Expander, Energy, enthalpy,
(OP)
Hi,
In our ASU we have a turbo expander/compressor. The expander is driving the compressor.
Now, we are thinking about the energy released at the expander.
The energy needed for the compression of a surten amount of gas must be released by the gas in the expander. (for this moment, we are talking about 100% efficiency, we know that's a theoretical case)
We want to calculate the energy released in the expander but at this moment the formula to calculate does not come in to our mind.
Gas inlet expander: 50 bar -80dgr C
Gas outlet expander: 5 bar -165 dgr C
Gas flow through expander: 24000Nm3/h Nitrogen
Gas inlet compressor: 40 bar 18dgr C
Gas outlet compressor: 50 bar 40dgr C
Gas flow through compressor: 30000Nm3/h Nitrogen
Hopefully someone can help us with the formula.
Thanks!
Cryotechnic
In our ASU we have a turbo expander/compressor. The expander is driving the compressor.
Now, we are thinking about the energy released at the expander.
The energy needed for the compression of a surten amount of gas must be released by the gas in the expander. (for this moment, we are talking about 100% efficiency, we know that's a theoretical case)
We want to calculate the energy released in the expander but at this moment the formula to calculate does not come in to our mind.
Gas inlet expander: 50 bar -80dgr C
Gas outlet expander: 5 bar -165 dgr C
Gas flow through expander: 24000Nm3/h Nitrogen
Gas inlet compressor: 40 bar 18dgr C
Gas outlet compressor: 50 bar 40dgr C
Gas flow through compressor: 30000Nm3/h Nitrogen
Hopefully someone can help us with the formula.
Thanks!
Cryotechnic
"Math is the ruler of your potential succes...."





RE: Expander, Energy, enthalpy,
the equations you seek are located in your thermodynamic textbooks, perry's handbook, ME handbook, etc. the energy needed to drive the expander and to compress the gas is simply massflow x enthalpy difference (assuming 100% efficiency, but not the case) across the machine. if pure n2, then there are ample tables available to obtain enthalpy values. massflow is easily determined as well - hint 1 lb-mol occupies 379.5 cf at STP.
good luck!
-pmover
RE: Expander, Energy, enthalpy,
The equation of massflow x enthalpy difference I knew, the thing is, I couldn't find a equation with both the factors Pressure, and Temperature to calculate the enthalpy at the inlet and outlet (or enthalpy difference for that matter).
And yes, equation is a better word, I was looking for that, it didn't come to my head.
By the way... Whiz?
Thanks again.
Cryotechnic
"Math is the ruler of your potential succes...."