RE: Pumps in Lime Slurry Service

[PwrPumpGuy]

Hello Group:
I work at an 1800MW combined cycle plant in NE Texas. We have a Side Stream Unit which we use to clean up our cooling tower water for re-use to limit the amount of total water usage. This SSU has a lime slurry system and soda ash system. The lime slurry system uses Gould's 3196 MT pumps to deliver the lime to our clarifiers. After about 2-3 months of service the lime collects in the piping, pump impeller, and casing so bad that we have to pull the pump and chip out the lime to regain capacity.

I am trying some coatings, but was wondering if anyone else has some experience with lime systems, and if this is a common issue. Is there a way to keep the lime from collecting and hardening inside the pump and impeller? The pump stays operating at all times and when the control valve to the clarifiers closes, the lime returns to the tank via a recirc. line. I could understand if the system was off for a period of time, but the slurry is constantly moving, and seems like it would not stick and harden the way it does.

Any tips or suggestions?

Thanks

 

[BigInch]

I can't help you with the measures to take with the pumps for lime coating, but I'm sure somebody will offer some advice soon. I just thought I'd mention why lime sticks. When lime, calcium oxide, is combined with water and CO2, it produces calcium carbonate, the main ingredient of oyster & marine shells, coral reefs and cements.

"If everything seems under control, you're just not moving fast enough."
- Mario Andretti- When asked about transient hydraulics

http://virtualpipeline.spaces.msn.com

 

[stanier]

Lime slurry is just as you say a pain in the derrier.

For pumps I suggest peristaltic type as they will break the crust.

For piping I suggest rubber loses laid in cable ladder. One plant even runs the rubber hoses across the road so that trucks and other vehicles keep breaking down the crust.

Check out your local water treatment facility. Everyone would have a lime plant.

 

[Artisi]

A rubber lined (slurry) pump will sometimes ovecome the problem - the thinking is that the rubber "frets" while the pump is in operation and the lime is less likely to stick.

 

[itdepends]

Check the quality of the water your using to make the lime slurry for anions that will precipitate with calcium.

 

[Ork1]

I recently took place in a very large grouting project where continuous pumping of grout 24/7 was the goal until fininshed.
A year long job...I found by coating very liberal amounts of anti-seize on the inside of casings, impellers, check valve assy. etc... worked very well at preventing build up of grout.
For your situation I do not know if this would work.

 

[djverder]

I concure with Stanier a peristaltic hose pump would solve your problem. We have sold many hose pumps into lime dosing industries and had no problem. As the hose is the only component in contact with medium, there is no expensive mchanical servicing only a hose change every few 1000 hours.

 

[unclesyd]

You might want to checkout the "Hydrokinetics" technology.

http://www.pipetech.no/hydrokinetics.asp

http://www.aimmtechnologies.com/services.html

 

[CJD1984]

We sell pumps for a living and I would concur with the peristaltic hose pump idea.

-NO SEALS!

-1 wetted part that is easily replaceable

and

-the rotor(s) is in constant compression with the hose preventing solidification in the hose.

Word of advice...select a pump that has a rotor that compresses the hose 360º and not just some parts of the hose.


CJD

 

[turbodare]

Rubber is more used to avoid abrasion. Problem is also piping.
try/search for water conditioner (maybe magnetic water treatment)

http://www.carefree.com.au/page/industrial.html

http://www.hop-pth.co.il