velocity - pulp in suspension

[JP123]

Hi,

Does somebody know the recommended velocity in piping for water with pulp in suspension having 2-8% consistency?

Thank you.

 

[Artisi]

Are you talking about paper pulp?

 

[JP123]

yes

 

[Artisi]

Why are you interested in the pipe velocity when pumping paper stock - generally the worry is friction loss although the 2 are linked in an unusual way.
Uptill some years back all the published data considered that the friction losses for paper stock was higher and with some published data considered it to be much higher. In the 80's some research was started and undertaken in NZ as well as a couple of other locations which reversed the current theory and showed that once a certain velocity is reached the friction loss for paper stock became lower than water.

This research is now available via Goulds pumps and the following link gives a good overview of paper stock pumping including the friction losses for various types of paper stock.

http://www.gouldspumps.com/cat_pf_0005.html

The pumping of stock upto and including 6% is usually fairly straight forward and not too difficult but becomes a problem if the stock is aerated.

Over 6%, pumping can become a bit more of a problem, but it can be done with the right equipment.

 

[rkuhn]

You should take a look at:

- "Generalized method for determining the pipe friction loss of flowing pulp suspensions”, TAPPI TIS 0410-14 (1988)
- Lindsay, J.D. and Gullischsen J. “Pulp Pumping and Hydraulics”, IPST Technical Paper Series Number 562, Institute of Paper Science and Technology, Atlanta (1995).

http://smartech.gatech.edu/bitstream/1853/1856/1/tps-562.pdf

Cheers,
RK

 

[Artisi]

rkuhn (Mechanical)
Thanks for the excellent reference, which gives a good overview of stock pumping in the medium and high consistencey stock suspensions.

However, the OP was asking about low to "low" medium consistency 2 - 8% which is covered in chapter 2: 2.1 Pulp Suspension Behavior and is well covered in the Goulds link.

 

[unclesyd]

In addition to the above information you might want to look at the Discflo pump for pumping your stock. I know of two mills in this area that use this design.

http://www.discflo.com/I-paper.htm