Centrifugal pumps for low shear application 1

[Alexander R.]

I have a question to people who are working with pump selection for low shear applications. My area of interest is oilfield produced water treatment. This water usually contain small droplets of dispersed oil which is separated by hydrocyclones. But to use hydrocyclones effectively inlet feed has to have certain pressure. For this purpose a pump need to be utlized. The important aspect is not to shear dispersed oil even more.
I am aware that mainly two types are used for this purpose: positive displacement or centrifugal pumps. I am asking what are the parameters are used for the pump selection?

 

[LittleInch]

You might want ot do a little investigation ito other types of pumps. A simple search finds articles like this:

https://hollandaptblog.com/2014/03/...t-can-we-do-to-minimize-it-in-sanitary-pumps/

I was checking that the better types of pumps would be a twin screw, a diaphragm pump (AODD would be typical) or a progressive cavity pump for such applications.

Your parameters would be the normal ones of flow and head / pressure requirement but also you're looking at low shear.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[bimr]

You seem to have skipped over the screw pump. Most skimmers use screw pumps because the pumps will not form an emulsion, are tolerant of debris, do not require priming, and will handle viscous oil.

The screw / centrifugal impeller with its open channel impeller design combines the gentle action of a screw pump and the high flow rates and cost efficiencies of a centrifugal pump.

https://www.environmental-expert.com/products/triton-screw-centrifugal-pumps-148204

http://www.pumpengineers.co.nz/index.php/Pumping-Products/hidrostal-pumps.html

http://www.eng-tips.com/viewthread.cfm?qid=333207

 

[georgeverghese]

Though it is less ideal than a Moyno or a screw pump, due to reliability issues in heavy duty oilfield applications, a low speed 800rpm centrifugal is typically used for this service.

 

[Alexander R.]

From the link to the article you posted, it looks like not exactly area of my interest. Article talks mainly about non-newtonian fluids, where shear is damaging and irreversible. Applications also imply relatively low flow rates to reduce the impact. My interest is produced water treatment. I dont need to eliminate shear at all, but to keep it minimal, plus dealing with high flow rates.
Also regarding twin screw pumps, I have surveyd some reports form the operating companies, and some have challenges with them regaridng maintencance. In certain cases they have to do maintenance on them every second month.

I look for API 610/676 compliant pumps as a requirement in the petroleum industry. Couldnt find if this screw centrifugal type has such approval. Also it looks like these pumps can develop rather low pressure, not more 6-7 barg.

 

[LittleInch]

The article provided data on which pumps are best in reducing shear, which is what you asked for - "pump selection for low shear applications"

You provided NO DATA on your desired flow rate or pressure and only now say you want a "high flow" with no numbers. Your high might be my low. Same with pressure.

You appear to want to clean up produced water. This is usually done at low pressures and hydrocyclones don't like high pressures - it makes the exit nozzle very small and liable to clog.

API 610/676 is your choice, it is not mandatory. Smaller pumps and "special" pumps often do not follow the requirements of 610, but are still valid choices. If you want to restrict yourself to a smaller choice of pumps then that is your choice.

As the article says and George says - if you want to use a standard centrifugal then do so but at as low a speed as you can get (< 1000rpm).

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[Alexander R.]

My bad that I didnt provide enough input data. I understand your arguments completely API requirement is the industry standard here, thats why I follow it. I see that general consensus is that centrifugal pumps will do the work if RPM is limited to under the 800-1000.
I found interesting article where pumps comparison is given with regards to shearing:

https://www.spe.org/en/ogf/ogf-article-detail/?art=25

Conclusion is also that at right conditions the centrifugal pumps can do well in water treatment aplications.

 

[Artisi]

Well general consensus is wrong about centrifugal pumps below 800- 1000 RPM.
Depending on your flow rate - not given- have you looked at perastaltic(hose pumps)

It is a capital mistake to theorise before one has data. Insensibly one begins to twist facts to suit theories, instead of theories to suit facts. (Sherlock Holmes - A Scandal in Bohemia.)

 

[Alexander R.]

No, I didnt look at this type of pump. My general input data is flow: 60 m3/h with differential pressure of 15 bar.

 

[bimr]

With your criteria of 15 bar and that the RPM is limited to under the 800-1000, a centrifugal is probably not an option. You should look into the pd pumps.

 

[georgeverghese]

Pls note there may be entrained sand / other solids in the produced water feed to these booster pumps, and if so, that may ruin pd pumps in a very short time.

 

[Artisi]

Any other surprises?

It is a capital mistake to theorise before one has data. Insensibly one begins to twist facts to suit theories, instead of theories to suit facts. (Sherlock Holmes - A Scandal in Bohemia.)

 

[Artisi]

Look at Bredel hose pumps,upto and maybe higher than 16 bar plus solids.

It is a capital mistake to theorise before one has data. Insensibly one begins to twist facts to suit theories, instead of theories to suit facts. (Sherlock Holmes - A Scandal in Bohemia.)