4 replies to this topic

[zddzzddz]

How do I calculate the outlet Liquid (LPG) temperature for pipe (the pipe is underground)? Pipe length is 16 Km and its diameter is 8 inch. The inlet Liquid LPG flows at a temperature of 46 C and a pressure of 25 Kg. Its outlet pressure is 2.3 kg (can I calculate??)

LPG Viscosity = 0.15 c.p.
LPG Specific gravity = 0.54
Pipe Wall Thickness of = 0.257

*Note the pipe underground at the 1M and the surround temperature in winter = 10 C, in summer is 15C how can I calculate the out let temperature in winter & summer?

[djack77494]

zd,
The unit kg is for mass, not pressure. I assume you mean to say your inlet pressure is 25 kg/cm^2. I also assume you mean gauge pressure. Please strive to be precise and accurate.

Yours is a basic heat transfer problem. 16 km is a considerable distance, and so your temperature should tend to approach the surrounding (ground) temperature. Though the rate of heat transfer is quite sensitive to ambient factors, such as the moisture content of the soil, you might try just thinking about the problem a bit and deciding what is the toughest scenario to deal with. Is it more difficult to think that the LPG may be at soil temperature or at its initial temperature? You could do whatever calculations you are interested in doing at both of these extremes in order to "bracket" the solution. (I'd strongly encourage you to do this.) Then just take the worst case. I recognize that you also have a significant pressure loss en route, and just the pressure drop will impact the temperature.

If you have access to simulation software, you might try using it. Simulators should very nicely handle this situation. Unfortunately, the most critical part of the whole process is the estimate of the heat transfer to ground. I can't help you with that.

[Padmakar Katre]

Dear,

Why you don't use the PipeSys extension in Hysys? It will yield more realistic results since it has an option to select the type of the soil, and type of insulaton used. So, I think PipeSys Extension is the better option in your case.

[Zauberberg]

You can also try to use 3E Plus freeware from Insulation Manufacturers Association: http://www.pipeinsulation.org/

I remember Schlumberger's PipeSIM was able to do this kind of calculations quite accurately.
Good luck,

[kuldeepd]

hope this helps
http://www.processca...ipe_Sizing.aspx