Dear All,

My application requires me to measure the flow of a very viscous material in sugar industry viz sugar massecuite & Seed. The problem is that due to very high density of the material the pipe lines are over sized to avoid the jamming.

However,to install MAG i can't even reduce the line size because it will result in the jamming of line. Again due to oversized line size and low flow rate, velocity of material is 0.3 m/s which is a disaster considering the accuracy of the instrument which requires minimum velocity of 1 m/s.

What could be the solution for such kind of measurement.
Nerds please help me out!!!!!!!!!!

Regards & thanks in advance

 

The accuracy rating of the Siemens Ultrasonic clamp-on transit time flowmeter starts at 0.3 m/sec.

I've found their transit time flowmeter to provide accurate readings when used with pure liquids. The meter tolerates a fair degree of aeration. Zeroing is not an issue.

But for fluids with suspended solids, bubbles or heavy aeration that require the doppler sensors, the accuracy falls off dramatically, to 20%+, and zeroing becomes an issue.

The obvious advantage of clamp-on is that it generates no pressure drop and doesn't intrude into the process.

David

 

What about a straight tube coreolis, that shouldn't create a bottleneck, more expensive than a mag but it may be the only answer,

Regards
Roy

 

At the first thought similar to David but I think over sized pipe with low velocity viscous fluid will keep the flow partial in the pipe, that would be a tough application for any ultrasonic flow meter to work on. Ultrasonic Flow Meter from Ultraflux do have advantage over other ultrasonic technology as they can see much better low velocity as well as a level sensor on large pipe to see level and compute the actual rate of flow. You can have a look at their product and could be a solution though not very sure. All other technology will either ask for reduction in pipeline or inaccuracy in flow measurement due to dual phase.

 

I would take a serious look at CiDRA flow meters. They are unique and can measure void fraction and are non-invasive. They might work.

Walt Boyes
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I'd suggest what you actually have is a laminar flow profile with much of the fluid moving very much slower near to the pipe walls and probably not moving at all at the walls and for a distance away from the wall.

It means much of your actual flow is taking place not at 0.3m/sec but at a significantly higher flow velocity where the fluid is tunneling down the centre of the pipe with a much smaller effective flow cross section.

This is a common enough situation with difficult fluids such as chocolate.

However, one way to improve the situation may be by heating the fluid which will reduce the viscosity and allow you to utilise a smaller diameter pipe which will then open up your flow meter choices. Be sure to insulate the pipe very thoroughly since you don't want to create boundary layer cooling with increased viscosity at the pipe walls.

You should find that it won't take very much of a temperature rise to reduce the viscosity quite significantly and hopefully you will find a safe maximum temperature for your fluid that will allow you to do this.