If you entered 10 psi into the simulation then you must make sure that you specified in Hysys that pressure is psig
You may think that amine concentration in simulation is as in plant, but how do you know for sure? Because somebody told you that amine concentration in plant is X % ? Was that X % actually measured in the lab, or is everybody just assuming that it is X ?
I see 6 possible causes for the big difference in actual and simulated temperature:
- wrong pressure used in simulation
- wrong amine concentration in simulation
- wrong amine type in simulation
- wrong thermodynamic data (fluid package) used in simulation
- temperature measurement in plant is not correct (instrument is wrong)
- pressure measurement in plant is not correct (instrument is wrong)
It is up to you to figure out which of the above is cause of the big difference between actual and simulated temperature. We don't have access to plant data or your simulation.
And don't simply belief what people or instruments in the plant say.