5 replies to this topic

[sah14002000]

Dear Sir;
I am involved in one project which includes one gas dehydration unit which use TEG(Triethylene Glycol) to dehydrate the gas .
In the process there is one circulation pump which shoud increase pressure of TEG(with purity of 99%) from 6 bara(and 37 C) to 118 bar.
The strange matter is that the temperature of TEG decrease in outlet of pump by 3 C.
the software which used for simulation is HYSYS and the equation of state is peng robinson.
the question is that in actual case and reality what happens for TEG. Does actualy TEG temperature decrease after pump?
I asked it from one who do the simulation and he confirmed that it happens in actual operation of plant,but i need some evidence.
can you help me?
Best Regards

[Art Montemayor]

First of all, this thread has nothing to do with what its title indicates ("Compressor Power Calculation"). I am changing the title to something that is descriptive.

There is no TEG temperature decrease caused by pumping it - no matter what Hysys output says or your simulation friend who asserts it. Hysys doesn't know any different since it basically is an ignorant computer program that has never operated a real-life TEG dehydration unit; your friend, I am forced to say, also doesn't appear to have that experience either. I have, and I can tell you from experience. Perhaps this thread belongs in the Simulation Forum, where theoretical and analytical topics abound.

[Propacket]

sah14002000,

It is a hysys glitch found in older versions of hysys. Your hysys version must be an older one as this problem has been eliminated in the newer versions. You need to calculate temperature rise due to pumping manually. The link below can help you caculate this. One thing that i can assure you is that temperature decrese due to pumping is not an actual phenomenon.

http://www.engineeri...ease-d_313.html

[aanita]

In practical case TEG pump discharge temperature increase, not decrease.
I checked my TEG pump discharge temperature, it is increasing.

Regards.

[djack77494]

Perhaps this thread belongs in the Simulation Forum, where theoretical and analytical topics abound.

I believe that would be the proper location. This anomaly, and I'm not sure how uncommon it is, serves as a warning of the dangers of blindly relying on a simulation to predict results. I use simulators all the time, and they are wonderful tools for the chemical engineer. But they are absolutely susceptible to the old rule of "garbage in = garbage out". Give your results "the sniff test". If they don't smell (or look) right, don't assume the results are correct because the simulator said they were. Simulators lie.

[sah14002000]

thanks my friends.
it seems that this case is a limitation by hysys.
the person who did the simulation, in final stage used on dummy heater to compensate temperature decrease in pump.