JOULE-THOMSON EFFECT 6

[hianbotech]

We are designing a pipeline to send Extra heavy Oil diluted with a water composition of 0.135 % mol. We are making the hydraulics calculations in Pipephase. However we are getting from the program that the stream increases their temperature when the pressure drop. It is possible this effect on hydrocarbons???

See the study cases:

First Case
Operation Temperature (source) = 98° F
Ambient Temperature = 98° F
The pipeline has 300 meters; the initial pressure is 500 psig and arrives to the Plant at 50 psig. However the temperature is increased at 103 °F in the plant.

Second Case
Operation Temperature (source) = 66° F
Ambient Temperature = 66° F
The pipeline has 300 meters; the source pressure is 1281 psig and arrives to the Plant at 50 psig. However the temperature is increased at 77 °F in the plant.

We consult this issue with the provider of the simulation program, and they mentioned that this effect it is possible in some fluids. They gave me an internet address in order to see an possible explanation of this behavior:

http://www.madsci.org/posts/archives/jun2000/959891423.Ph.q.htmla

Joule Thompson effect

I would like to know if this thermal effect is possible in hydrocarbons.

 

[sailoday28]

23562, For the oil flow-- kinetic energy and elevation should have small effects on temp.

energy balance w(Hin-Hout)=heat loss to surrounings
Hin-Hout = UA(Delta T mean)/w

where H=specific enthalpy
w mass flow rate
Approximating Cp, specific heat at const press as a constant
Tin-Tout=UA(Delata T mean)/(wCp)

Right hand side of equation with high flow rate might be the reason for small temperature change.

Regards

 

[25362]

To sailoday28, yours is the logical answer, although it seems to assume a constant heat flux UA, while we know U is a direct -albeit non-linear- function of w. The temperature drop is evidently dependent on the flow rate, lower drops appear at higher flow rates (as well as lower residence times).

 

[sailoday28]

25362 (Chemical)
Perhaps instead of oversimplifying the heat transfer from the pipe,
--the heat loss to the surroundings should be=
integral of UPo(Tlocal-Tsurroundings)dx
where Po is pipe OD
Tlocal, Oil temp as a function of distance
Tsurroundings, the earth temp
x distance in direction of pipe.
U local overall ht trans coef.
A high WCp will still minimize the fluid temp change.