Transportation of two fluids with different viscosity
Transportation of two fluids with different viscosity
(OP)
Could somebody help me about the hydraulic analisis for transportation in a pipeline of two liquids with differente viscosity. That liquids are transported in batches separated by pig. What viscosity must I consider? Pipeline is 200 miles lenght.





RE: Transportation of two fluids with different viscosity
RE: Transportation of two fluids with different viscosity
Good luck,
Latexman
RE: Transportation of two fluids with different viscosity
Other considerations would be number and locations of additional pumps along the route (if any).
As Latexman noted, the pump type may have an effect. If you were using centrifugals, the flow would most likely be substantially different. (and power requirements)
RE: Transportation of two fluids with different viscosity
RE: Transportation of two fluids with different viscosity
Fluid B is 300 cSt, 1.015 s.g.
Fluids are homogenized.
RE: Transportation of two fluids with different viscosity
RE: Transportation of two fluids with different viscosity
You have a very long pipeline (200 miles). So you send product A down this pipeline. After a while, you stop sending product A, and you want to send product B. To stop cross contamination, you send a pig down in between the products. When you have sent product B, you then send another pig and product A after it. And so on...
You want to know the viscosity, because you want to estimate the pressure drop.
Fluid A is homogeneous.
Fluid B is homogeneous.
Fluid A and fluid B are not mixed with one another.
Is this correct?
Some questions:
Can you have more than 1 pig in the line at the same time?
What is the maximum length of product B (the more viscous) at any one time?
How do you get the pigs back again???
RE: Transportation of two fluids with different viscosity
Just do your design calcs for fluid B. Having the higher viscosity AND s.g. makes it your worst case. Fluid A will make the pumps pull less power.
Good luck,
Latexman
RE: Transportation of two fluids with different viscosity
"The properties of gases and liquids''-Reid and Sherwood -McGraw-Hill --Chapt 9 of the 2nd Ed--Section 9-13'Estimation of Liquid-mixture viscosity'
Some insight to liq mix viscosity is given in the above reference.
I haven't looked, but Bird, Stewart and Lighthill might provide additional help.
RE: Transportation of two fluids with different viscosity
Your post is not quite true. If the pig is pumped down the line with the products it will create a significant drag on the vessel wall. The worst case may therefore be the most pigs in the line at any one time, hence the reason for my questioning.
The last question, I must admit was simply curiosity. 200 miles is a long way, especially if it's a straight length of pipe - do the pigs get taken out the line and sent back by airmail I wonder???
Still waiting for answers from cica58...
RE: Transportation of two fluids with different viscosity
Once a year an intelligent pig, together with an Intelligent Pig Engineer (what a great job title!) arrive (him on the chopper, the pig on a boat), and we send the pig down the line, back to shore where the survey is downloaded.
I guess Cica's pigs could go back to the start by lorry if he's onshore.
Maximum numbers of pigs in a line: we'll have up to 2 in our line at once; during pipeline commissioning pig trains can be much larger but I don't know exact numbers-pose the question on the Pipeline Board!
RE: Transportation of two fluids with different viscosity
Fluid B batche is 107000 bbl; Fluid A batche is 125000 bbl; the capacity of pipeline is 117500 bbl. Fluid B is pumped by screw pumps and fluid A by centrifugal pumps.
RE: Transportation of two fluids with different viscosity
You will need to contact the manufacturer of the pigs to determine the pressure drop v flowrate characteristics.
RE: Transportation of two fluids with different viscosity
You are correct on the design of Fluid A system, however it may be different on the design of Fluid B system. Market demand could dictate that they need two batches of Fluid B back-to-back. We don't know this for sure, but, it may be possible. And, who knows what will happen in the future? If they qualify product in lots on the basis of batches, they may want to put pigs between the two batches of Fluid B. The absolute worst case of *all* Fluid B and two pigs is probably only a few percentage points of conservatism. IMO, the complication of adding the 10,500 bbl of Fluid A to the design is not worth the effort for the design of either system.
Good luck,
Latexman
RE: Transportation of two fluids with different viscosity
What you say could be possible depending on the system. I was kind of assuming batches of the same product would be mixed in a storage tank at the far end, but you are correct in that this isn't necessarily true. As you say, the difference is probably not that great in % terms.
Cica58
One other point to make. If you are starting a new batch of A with the line full of B, it will effectively mean that the centrifugal pumps used for A will need to pump the line full of B (But with A in the pump heads). Both sets of pumps should be sized for pumping mostly (or all) fluid B (+ 2 pigs).
RE: Transportation of two fluids with different viscosity
RE: Transportation of two fluids with different viscosity
This isnt an unusual pipeline by any means. Many refinery facilities pump to offshore loading terminals and change the slate. They do not even use pigs to separate the fluids as the interface quantities involved are diluted at the other end in tankage.
Also the mining industry has tailings lines that can be carrying solids in a slurry or being purged with water.
RE: Transportation of two fluids with different viscosity