Addition of polymers to reduce pressure drop 2

[CARF]

Hi all,

Addition of polymers. It has been known for more than 50 years that addition of a small amount of polymers to a turbulent flow results in a significant reduction of pressure drop (or increase of flow rate for a given pressure drop).

By reducing the frictional pressure loss, pipeline boosters can increase throughput by more than 90% of the pipeline’s mechanical capacity... says a supplier.

Is this really true? Has anybody has experience with addition of polymers to reduce pressure drop? How much did it help?

Thanks!

 

[pennpoint]

MVD
OK! I am going to dive in here. (Fifty Years)
"Addition of polymers. It has been known for more than 50 years that addition of a small amount of polymers to a turbulent flow results in a significant reduction of pressure drop (or increase of flow rate for a given pressure drop)."
Really!!! What are these polymers and to what fluids are they effective.
I would really like to know of a polymer that will reduce the pressure drop I have had to overcome.

 

[MortenA]

There are lot of such stuff.

A 90% reduction in friction is close to max (and would be very expensive).

I would say that normally a 50-70% reduction would in many circumstances be economical (compared to investing in a new pipeline).

A well know supplier is Baker Huges / petrolite. Check this webpage out:

http://www.bakerhughes.com/bakerpetrolite/gasfluids/index.htm

Best regardd

Morten

 

[CARF]

So yes really !

They seem to reduce the amount of turbulence.

Anybody else has good / bad experiences?

Thanks,
MVD

 

[alfonsoa]

The use of Drag Reducing Agents (DRAs) is an excellent method to increasing the flow rate in crude oil pipelines. The effectiveness of the method depends on the type of crude oil. DRAs seem to be a cost effective solution for low viscosity, >24 API crudes. It seems that the only way to be sure DRAs work is to do a field test, which the two major DRAs manufacturers usually recommend.

 

[MortenA]

It is used in the pipeline from the Danish Gorm fields to onshore facilities - where the rate now is about double that of the original design flowarte.

You should however be carefull with your pressure surge calculations! This problem is not solved by DRA (Drag Reducing Agent)

Best regards

Morten

 

[CARF]

Thanks all,

So this stuff really works!
Please forgive my ignorance, but what are pressure surge calculations?
Same as pressure drop calculations?

MVD

 

[MortenA]

pressure surge or water hammer (but since it not water you have i used the other term) is when you e.g. close a valve and the pressure rises above your max. pressure in the pipeline due to the kinetic energy stored in the moving liquid. Other cases can also cause a pressure surge.

A bit of advice: You seem unawave of how to perform flow studies. I would recommend that you get help before recommending anything. There are many consultants out there that can help if your company does not have the knowledge.

Best regards

Morten

 

[es335]

MVD commented that the additive seems to reduce the turbulence. I am not sure, but it seems to me that turbulence is not reduced. It must be reduction of the shear stress through reduction of viscosity?!

The reason I do not believe that the turbulence is reduced is because a high turbulence gives a low loss as can be seen on a moody diagram where the friction factor is reduced as the Re increases.

But, if the DRA works in any other way, please let me know.

/C

 

[jmw]

Multi-product crude oil pipelines use "snot" (drag reducers) to help reduce the pipe friction and not, as i understand it, to reduce turbulence. They are added in quantities which are specific to the crude. This is a case when more is not better. Once the optimum amount has been added, adding more doesn't reduce the friction any further. I am told they are high molecular weight compounds which are ultimately broken down by the shearing action in pumps etc.

 

[CARF]

Hi all, this is what ConocoPhilips says about flow improvers:

Drag reducers -- also known as Drag Reducing Agents, DRAs and Flow Improvers -- are any material that reduces frictional pressure during fluid flow in a conduit or pipeline. Using DRAs allows increased flow using the same amount of energy or decreased pressure drop for the same flow rate of fluid in pipelines. The current class of DRAs, such as CSPI’s range of LiquidPower™ Flow Improver products which are marketed in the pipeline industry today, consists of long-chain hydrocarbon polymers that act as buffers along the pipe wall to decrease the amount of energy lost in turbulent formation.

By the way, many thanks for all your input !

see further:

http://www.liquidpower.com/ProductSolution/WhatAreDRAs.asp