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Specialty Chemistry Forums => Chemical Engineering Forum => Topic started by: curiouscat on March 19, 2015, 02:00:24 PM

Title: Intuition fails me: Should a slurry pipe be small or large to avoid plugging?
Post by: curiouscat on March 19, 2015, 02:00:24 PM
Say you are pumping a slurry. Say, salt crystals in water. Perhaps 10% of the slurry is solids.

Now choking / plugging is always something you want to avoid. My naive intuition says use a large pipe size to avoid choking.

OTOH, for a certain flowrate a smaller pipe means a larger velocity. So that would be less likely to plug up.

What's the right way to think about this?
Title: Re: Intuition fails me: Should a slurry pipe be small or large to avoid plugging?
Post by: discodermolide on March 19, 2015, 03:03:00 PM
Perhaps a turbulent flow is the way to go here, keep the stuff in suspension. So higher velocity and perhaps a nitrogen blast to maintain turbulence?
Title: Re: Intuition fails me: Should a slurry pipe be small or large to avoid plugging?
Post by: Arkcon on March 19, 2015, 05:23:49 PM
Bulk flow is more of a chemical engineering question, we'll see how our experts weigh in.  My knee jerk reaction is that you'll want a wider pipe.  Flow is essentially zero at the inner surface for liquids, I have to guess the same or worse for a slurry.  So you want a wider tube so there is flow.  Unless the slurry is a non-Newtonian fluid.  But in that case, I have no idea at all. ;D
Title: Re: Intuition fails me: Should a slurry pipe be small or large to avoid plugging?
Post by: curiouscat on March 20, 2015, 05:47:16 AM
Bulk flow is more of a chemical engineering question, we'll see how our experts weigh in.  My knee jerk reaction is that you'll want a wider pipe.  Flow is essentially zero at the inner surface for liquids, I have to guess the same or worse for a slurry.  So you want a wider tube so there is flow.  Unless the slurry is a non-Newtonian fluid.  But in that case, I have no idea at all. ;D

It shouldn't be non Newtonian. What I worry most is solids settling out. It is a settling slurry. Make a pipe too large and essentially you have a settling problem.
Title: Re: Intuition fails me: Should a slurry pipe be small or large to avoid plugging?
Post by: Corribus on March 20, 2015, 10:07:15 AM
Knowing virtually nothing at all about this subject, I can still add that this might be a situation where there is be a tradeoff between the two factors and the optimum situation is somewhere in the middle.
Title: Re: Intuition fails me: Should a slurry pipe be small or large to avoid plugging?
Post by: DrCMS on March 20, 2015, 12:33:30 PM
I know a company that pumps ~1m3 per minute of a 65% solids slurry through an 11inch underground pipe for an uninterrupted 56miles.  The replacement cost from the last time they blocked it 10-15years ago was over £1M per mile. 
Title: Re: Intuition fails me: Should a slurry pipe be small or large to avoid plugging?
Post by: curiouscat on March 21, 2015, 01:13:20 AM
I know a company that pumps ~1m3 per minute of a 65% solids slurry through an 11inch underground pipe for an uninterrupted 56miles.  The replacement cost from the last time they blocked it 10-15years ago was over £1M per mile.

Thank my stars that my slurry is 5 to 10% my distance is a 100 ft or so. :)
Title: Re: Intuition fails me: Should a slurry pipe be small or large to avoid plugging?
Post by: discodermolide on March 21, 2015, 02:38:31 AM
I thought you had to transport it further!
Only 100 feet! You should not have a problem. Make sure its all downhill.