Positive displacement pump - No pulsation

[camel80]

Hi,

I typically use peristalitic pumps to pump thick sand slurry (60 to 75% solids weight for weight) with a yield stress of up to 120 pa. My flow rate requirements are 1 to 10 litres a second. I typically use the Bredel SPX range, which work well. However, the pulsation in the flow is not ideal. I need a positive displacement pump that can maintain a perfectly smooth continuous laminar flow from the end of the discharge pipe (i.e no variation in the projection of the slurry as it flows from the end of the pipe). I am thinking to buy a screw pump and mount it below my delivery tank which holds 4 m3 of slurry agitated with a mixer. However, i have no experience with these types of pumps and i'm not sure it can deliver a perfectly smooth flow. I also have to fix the flow rates so an inline flow meter would have to be used to set the pump speed to deliver the specified flow rate.

The distance I am pumping is 10m from the mixer tank to the discharge point. It can be increased slightly to help smooth the flow rate if necessary.

I'd appreciate any advice on other options to smooth the flow using any type of positive displacement pump. I've been banging my head against a wall for almost two years now.

Many thanks

 

[pennpiper]

You don't say where you are so it is hard to offer any real solution.
However, if possible (location) I suggest you rent a "Screw" pump and run some tests.

prognosis: Lead or Lag

 

[camel80]

I am based in Chile. They have all the big pump suppliers here.

 

[micalbrch]

60-75 % solids (sand!) with a screw pump will become a nightmare. I'm sure that will not work. Did you try a pulsation dampener (perhaps 2?) with your peristaltic pump?

 

[DubMac]

Try a Progressive Cavity pump; e.g. Moyno, Netzsch, etc. They have essentially pulsation-free and are made for solids.

 

[camel80]

Good point. There is a distributor of Moyno here who i'll chase up. Just worried about the abrasive nature of the sand slurry and how it will affect the life span of the pump. It also needs to be able to suck the thick slurry from the holding tank and not rely on gravity feeding. I will have a 45 degree cone on the bottom of my holding tank that would feed straight to the pump.

 

[Strong]

All pumps produce some level of pulsation. It's just a matter of what level of pulsation is acceptable. Have you considered or tried pulsation dampers (snubbers), such as described here:

http://www.watson-marlow.com/Documents/knowledge-hub/Brochures/us - USA/b-bredel-spx-us-05.pdf

Walt

 

[stanier]

Mono Pumps in Australia manufacture ceramic coated rotors and stators for their progressive cavity pumps. These pumps are used on slurries.

http://www.mono.com.au

“The beautiful thing about learning is that no one can take it away from you.”
---B.B. King

http://waterhammer.hopout.com.au/

 

[micalbrch]

DubMac: 60-75 % sand solids with a progressive cavity pump? What stator lifetime do you expect under these conditions? I've seen a lot progressive cavity pumps in operation. Most of them performed well but I have not seen any yet with such a high concentration of mineral solids.

 

[DubMac]

Agreed, pump life is going to be considerably shortened by 60-75% sand; that is incredibly high concentration, it would wear any pump out quickly.

I used to peddle Monoflo pumps many, many moons ago and was trained in their Manchester, England factory. I recall that natural rubber stator is the very best material for sand; back then the best they could do for a rotor would have been some sort of hardened stainless. The rotor actually rolls along the stator and does not scrape along it. While it will certainly wear out; I think I would try the PC pump first; certainly no pulsations.

If the owner wants somethng that will last the longest, a shovel and a laborer would be the best choice; although depending on the laborer's technique, pulsations could be a problem.

 

[moltenmetal]

Three smaller hose pumps, each running 60 degrees out of phase to the next. Works with piston and diaphragm pumps...and if you patent it, I want my cut!

 

[bmw318be]

Anyone has idea what is the limit of % of solid for internal gear pu
P slurry application ?

I wonder what is the different on progressive cavity and screw pump suitability applicationn, is scree pump is more for higher flow

 

[Pumpsonly]

You should start a new thread..

 

[bimr]

What is your process and why do you need a pump?

Is it possible to change the process to utilize a screw converyor?