Pressure drop through the pipeline 1

[rutherford703]

This is about a cross country pipeline. We have pressure transmitters at both the entrance of the piping and the end of the piping. The pressure drop is the difference between the two pressure transmitters. With each pressure drop, we can get the corresponding flow rate. All data are listed in the attached excel file.

The fluid properties are as follow:

Composition: (wt%)
Bitumen: 60%
Water: 30%
fine solid: 10%
Fluid temperature: 53C
Fluid viscosity: 50 CP
Fluid density: 1070 kg/m3

Piping Data:
Piping ID: 35 inches
piping length: 40 km
Piping material: CS

The fluid can be treated as Newtonian fluid.

Based on the pressure drop calculation formula:
Delta P=K*l/d*(ro)*u^2/2/g
I will expect that I can get a constant number by calculating u^2/(delta p). However, the plot of u^2/(delta p) vs u clearly shows a u power 2 relationship. Can someone comment why?

Thanks in advance.

 

[BigInch]

Not frothy. I just know you can't move anything with cP of 25,000. He's got the right viscosity this time, but for the wrong fluid.

"People will work for you with blood and sweat and tears if they work for what they believe in......" - Simon Sinek

 

[Latexman]

At those flow rates (9000 gpm) they are probably using centrifugal pumps, so that usually means a cP < 1,000 to get a somewhat decent efficiency.

Good luck,
Latexman

 

[BigInch]

I usually find that a configuration for series on startup, then a switch to parallel operations after the pipeline and soil get hot and flow starts moving along faster than swine s... , relatively speaking of course, works well.

"People will work for you with blood and sweat and tears if they work for what they believe in......" - Simon Sinek

 

[rutherford703]

We are in the oilsand industry. The froth comes from the extraction process using hot water. No surfactants are added to stablize the froth. I don't think that the bitumen, water and solid will be separated during the hydrotransportation process. As I said, there is a viscosity number 540cp at 80C in the mass balance table and this number seems to be more reasonable. I realized that bitumen has an extreme viscosity-temperature property (viscosity reduces very quickly as temperature increases). All the nubmers are obtained from documentation, therefore, I have no idea regarding to the shear stress and shear rate for the test of the froth or bitumen. I believe that the design of the pipeline should be based on reasonable data assumption.

I have dealt with Bingham fluid and we have model to predict the pressure drop for Bingham fluid. I don't know if the froth belongs to power law fluid, Bingham fluid, or even psuedo-Newtonian fluid.

The normal velocities inside the pipeline are within the range of 0.7 ~ 1.3 m/s. As the rheology changes, the velocity inside the piping may also affect the Venturi meter reading which is compensated with fluid density.

 

[BigInch]

Most of the frothy bubbles should collapse when it sees the pressures inside the pipeline. You'd have to have a significant gas component in the mixture to see froth flow inside the pipeline.

So any change to the mixture won't be present in the full length of the pipeline until 10 to 20 hours afterwards. So I imagine that when you increase flow you see your largest pipeline differential pressure at time apx.=0 then 10 to 20 hours later, you get even higher flowrates at relatively low differential pressure, or you have to turn the pump power down to maintain a steady flowrate. If you decrease flow from a steady state, pipeline pressure differential starts to build as flow slows down and reaches a new steady state some 10 to 20 hours later.

"People will work for you with blood and sweat and tears if they work for what they believe in......" - Simon Sinek