×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!
  • Students Click Here

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Jobs

Lime slurry info to prevent scaling

Lime slurry info to prevent scaling

Lime slurry info to prevent scaling

(OP)
I have to rework a lime addition system to our reactor clarifier.  I'm wondering if there are any articles regarding the best makeup of lime to prevent scaling in piping.  

1)  % of hydrated lime in slurry
2)  Flow rates in pipes to minimize scaling
3)  Temperature ranges.

Any help would be appreciated but some sort of technical resource would be helpful so I can show where I got the information for justification of the project.

RE: Lime slurry info to prevent scaling

You will always get scaling whatever you8 do. I have used flexible PVC hose laid in cable ladder. The operators shake them occassionally. I have seen open troughs used made out of pVC pipe cut in half. At least they dont clog. Any spilaage dropped in the clarifier any way.

Sharing knowledge is a way to immortality

RE: Lime slurry info to prevent scaling

Can you obtain 40% hydrated lime slurry easily?  If you can it is by far the easiest way to go.  If it is not available, then I have always set up my feed systems to use a 5-10% slurry.

You will want to use 5D pipe bends instead of elbows.  If you must use an elbow, install a cross and plug two of the legs.  That way when it plugs you can clear it easily.  Keep your flowing velocities over 3 fps (5 fps is better).

I like to install a recirculation loop from the slurry tank to the point of application and back to the slurry tank.  If the lime feed rate is X lbs/hr then I size the supply pump to deliver 3X.  The return line will take the 2X flow back to the tank.  Make sure you step the pipe size down on the return line.  I normally use an actuated plug or ball valve to pulse the lime feed into the reactor/clarifier.  Immediately downstream of the plug valve is a manual pinch valve that you use to adjust the lime slurry feed rate.  You will want the plug valve to be open for about 30 sec out of every 2 minute period.  Pace the operation of the valve off of the inlet flow meter.

Non-metallic hose and pipe are good for this application but require a tray for pipe support.  

Another option is to use peristaltic pumps with VF motors.  But you have to watch your lime velocity to make sure you don't settle out the solids.    

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!


Resources