Pulp Stock minimum velocity in pipes

Question

Pulp Stock minimum velocity in pipes

Papelinas2212 (Industrial)

(OP)

28 Nov 12 06:09

Is there any minimum velocity for pulp stock in pipes that we shouldn´t go below? if so what´s the main reason, fibre settling?

thank you in advance

Daniel

Artisi (Mechanical) · Answer 1 · 2012-11-28 22:44:12

I have never really thought about minimum velocity for paper stock but don't believe that settlement would be a problem. You would be better to outline your problem / thoughts for a better response to your post so that it is understood what / where / why you are asking.

In the meantime the following link might be of some help. http://locator.gouldspumps.com/ps_0005.html

It is a capital mistake to theorise before one has data. Insensibly one begins to twist facts to suit theories, instead of theories to suit facts. (Sherlock Holmes - A Scandal in Bohemia.)

rmw (Mechanical) · Answer 2 · 2012-11-28 23:27:34

I can't remember where it is published right now but I have seen many times that the minimum range for keeping suspended solids in solution is 6-10 fps. I don't know why that wouldn't apply to pulp stock as well.

rmw

Artisi (Mechanical) · Answer 3 · 2012-11-29 01:22:05

No, paper stock is a vastly different "product" from the norm as far as suspended solids is concerned. Each paper stock type has an ideal velocity at which the friction loss falls below that of water for the same pipe diameter / velocity.
Paper stock at low velocity can be likened to plug flow.

It is a capital mistake to theorise before one has data. Insensibly one begins to twist facts to suit theories, instead of theories to suit facts. (Sherlock Holmes - A Scandal in Bohemia.)

Papelinas2212 (Industrial) · Answer 4 · 2012-11-29 07:47:57

Thanks Artisi and Rmw. The system has a big turndown, so the velocity in the pipe for the lowest flow, at 4% consistency, is around 0.15 m/s. Just wondering if it's ok to pump through a 150 m long pipe with a tortuous run.
cheers
Daniel

Artisi (Mechanical) · Answer 5 · 2012-11-29 08:32:50

I would think that a big turn down might create a few pumping problems , how will you reduce flow or is it just a function of the application, however depending on the stock type at 4% it may well not cause too many problems. You need to consider the amount of time it will be at low flow compared to design flow and maybe accept a bit more velocity thru the pipework at the higher flow so as to up the velocity a bit at the turn down flow.

It is a capital mistake to theorise before one has data. Insensibly one begins to twist facts to suit theories, instead of theories to suit facts. (Sherlock Holmes - A Scandal in Bohemia.)

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Pulp Stock minimum velocity in pipes