Density Measurement of Sludge Inline

M

Thread Starter

Maj

hi

I am looking for a proper sensor or method to measure the density of the sludge inline (range around 60000mg/l or 6%ss). ultrasonic sensors are expensive. so I am looking for another way like finding a relation between density and another factor so we can measure the density in order to do a feedback control.

I've looked on fiber optic reflective method, but the sludge is too dense so its difficult to get the light back (receive).

Thank you
Majdi
 
W
First I am assuming that this is sewage sludge. From the "range" you quoted, it is probably primary sludge, not secondary sludge unless it has been concentrated.

You have a real problem.

Nuclear gauges are out, for the reason that they can't measure the density differential in this application. The dry solids density of sewage sludges is approximately 1.2 g/cc. The apparent density of water is 1.15 g/cc for a nuclear gauge (if you want more, ask).

Ultrasonic sludge density meters sorta work in this application. But only sorta.

If you want to use pressure, you can't measure it in a pipeline. You need to do it in a tank.

I don't know a method that meets the 2-out-of-three rule (fast, good, cheap, pick any two).

Walt

Walt Boyes, Life Fellow, ISA; Fellow InstMC
Chartered Measurement and Control Technologist,
Member Assoc. of Professional Futurists
Spitzer and Boyes LLC
www.spitzerandboyes.com

**Spitzer and Boyes LLC publishes the Industrial Automation and Process Control INSIDER (www.iainsider.com)**
 
Hi

Thank you very much for this information and yes its sewage sludge, and the range of measurement for the sensor we looking for is 0.06 to 0.08 g/cc so I don't know if nuclear gauges will be able to measure that, and you are right ultrasonic is the most one used in this application but its expensive so I am going to pick good and cheap.

So still looking for a proper way to measure the sludge density in pipe, but also if you could provide me with information how to use pressure sensor if I want to measure it in the tank that will be great.

thank you very much again and I'm looking forward t hearing from you.

Majdi
 
I would suggest either a multi-variable vortex flowmeter or a coriolis flowmeter as the type of flowmeter that can provide flow and density of the fluid.

The coriolis meter will be much more expensive. They will transmit the density as a Hart or FieldBus variable. Both flowmeters have the advantage of being resistant to plugging up.
 
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