Lime Slurry Viscosity

[Csqiz]

Hi, I am currently designing an ejector system for dosing of lime slurry to water treatment process. The purpose is for pH adjustment. I faced a problem in identifying the head loss in the hose because I couldn't get a specific value for the lime slurry viscosity. The lime slurry is prepared at a concentration of 5% w/w, dosing velosity at the discharge of the ejector is 2m/s, and I am considering the slurry SG at 1.028. From what I read on the internet, the viscosity ranged from 40cP to 700cP. I am worried with the viscosity factor in the pipeline headloss, because the ejector is sensitive to the back pressure of the piping system.

Anyone can advise on the above, what would be the viscosity and the flow behavior at this concentration and velocity?

 

[LittleInch]

The only true way is to get a sample and send it for testing, but the 5% w/w ratio looks like the lower end of the viscosity range, somewhere between 10cP and 40 from what I can see.

So are you mixing 5% in your ejector or making 5% in this ejector?

Once you go over about 35% then you're into non Newtonian fluids and shear rate has a big impact and viscosity climbs above 150cP.

Slurry pumping you really need to keep it moving in the pipe > 1m/se and pref a bit higher.

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

 

[Csqiz]

Dear Sir,

I see. 5% will be the concentration drops into the ejector. At the ejector outlet, it will be further mixed with the motive water (10 times more) based on the ejector water requirement.

 

[LittleInch]

Then I would either use something like 40cP and 10cP to see the impact then get your particular mix tested if you want anything better. But still need to keep slurry moving.

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

 

[bimr]

One would doubt that the viscosity is the issue at 5% concentration. MOP No. 8 recommends a minimum velocity of 1.5 m/s. The pump should be an open impeller type. Ejectors should be avoided in transfer lines as the ejectors will foul. The length of hoses should be minimized and the piping should be at least 2-Inches diameter.

 

[pierreick]

Hi,
Are you sure about using an ejector for this application? Erosion is an issue.
Pierre

 

[Csqiz]

Hi,

Ya, it is quite confirmed that we are using ejector for the dosing system. The material would be SS316 or SS304, is erosion is still matters with this MOC?

 

[pierreick]

Hi,
Yes indeed!
Pierre

 

[LittleInch]

Why are you using an ejector?

Its the velocity in the line from the tank to the ejector which needs to be >1.5m/sec...

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

 

[bimr]

A flash mixer is more appropriate for this application.