Pump efficiency , old x new ? 1

[dkf]

Did any of the leading centrifugal pump manufacturers that supplies the petroleum industry make any relevant pump developpment ( in pump design and digital control machining)that results in significant efficiency increase over the last four/ five decades? Looking at still running pump stations that were built in the 60´s, makes me wonder if there is no room for a profittable change.
Putting it from a different angle, did anyone report significant advantage when replacing old but still in working condition pumps ?

TIA

DKF

 

[saxon]

dkf, There have been some minor hydraulic improvements in impellor design and at the suction impellor eye(due to CFD). The real cost savings have come about in the development of Hi-effciency motors and the implementation of VSD's.

Hope this helps.
saxon

 

[dkf]

Saxon, thank you for helping.
As you certainly perceived, I am an immigrant both to petroleum industry and english language.
Could you explain what CFD and VSD means?
Regards
dkf

 

[saxon]

dkf,
CFD: Computational Fluid Dynamics (computer analysis of fluid dynamics)
VSD: Variable Speed Drives

saxon

 

[PUMPDESIGNER]

If you are lucky d23 will see and comment, he is very experienced in the petroleum area.

d23 tells me that hydraulic efficiencies are not the highest priority in crude, reliability seems higher on the priority list.

I only deal with clear water, and efficiencies are often the big deal with our customers.

PUMPDESIGNER

 

[dkf]

Pumpdesigner, in clear water what were the hydraulic efficiency gains when you compare same model pumps that were manufactured 3 to 4 decades ago to present time?
It is difficult to believe that there were no significative improvements in design and in manufacturing.
Regards

dkf

 

[PUMPDESIGNER]

I can only speculate based on past reading, I have no hard facts to give you. Reading the Pump Handbook (Karassik, et al), and Stepanoff, you pick up little tiny hints here and there.

My lightly held non-authoritative image is as follows:

Karassik in the 1950s advanced the art of designing high suction energy pumps (High Suction Specific Speeds) with Nss values above 10,000, in fact he and two other guys (George F. Wislicenus and R.M. Watson) developed the whole concept of Nss in 1937.

Investment casting of impellers improved the efficiencies, in the 1990s some were still switching over to that process.

We certainly have the opportunity with CFD to improve our stuff, but I think the art of pump design is also dying down at the same time some improvements are being made, so while we move forward in one place, we fall behind in another. Adding to the negative side is the fact that corporations today do not value the knowledge held by their employees sufficiently, so they are losing that knowledge. Those MBAs (Master of Bussiness so called), think that the only form of knowledge in Engineering can be locked up in a computer.

But ahhhh, the art and wisdom contained in some of them old badgers cannot be written down or locked into a computer, it can only be handed down from one engineer to another, and the corporations are unwilling sometimes to spend the money for mentorship. Retire the old codger early, bring in the new guy with the CFD stuff, he costs less and does not need the old guy.

By the way, I am not one of the old guys, at least in my opinion.



PUMPDESIGNER

 

[dkf]

Pumpdesigner, I see your points.
I am trying to defy the new guys with all the CFD's and computers to show what they can do, if they can.
I am prospecting an opportunity to save thousands of KWHs, and if feasible open the market for a lot o business.

Thanks for your contribution

dkf

 

[ChickenSoop]

increasing the pump efficiency only works for the very select few pumps that operate at BEP.

The majority of pumps operate off of BEP, so increasing the pump's efficiency offers retalively little in comparison to optimizing one's system performance. Far more savings can be made by tuning in your system as a whole and making sure your troublesome applications stay on the pump curve.

 

[Artisi]

I would agree completely with ChickenSoop, concentrate on getting the pumps correctly sized and / or tune the system to operate at BEP of very close to it, or replace the unit with something more suitable and correctly sized.

In most pump systems everyman and his dog has included a safety margin or a fudge factor,(it's called covering your arse) just in case you have missed calculated. It usually starts with the client, add a little extra flow and head just in case, then the system designer adds a bit to be safe, the application / sales engineer then adds a bit to make sure, and then you add a little to the impeller trim just to be on the safe side.
So at the end of the day - the pump is usually oversized as is the driver, but that's OK according to those who are not paying the power bill, we might want to upgrade the system one day - but in the meantime you are burning up expensive power.
Some projects I have looked at over time, it would be far cheaper to replace the complete unit than to run the existing unit for another 12 months. But of course the bean-counters step in and you get the usual cry - that's a capital cost, we haven't budgeted for it and we can't afford it - just keep paying for the extra power because that's an operating expense and not my problem.




Naresuan University
Phitsanulok
Thailand

 

[dkf]

Artisi, thank you for contribution. I was not aware that oversizing and operating off the BEP could be that expensive. Now we still need to stimulate the pump manufacturing guys to show what they can do, or is it they already know its not that amount of money after all.
dkf