Re: Moisture In Pneumatically Transported Powder
Suggest you discuss this with Dr. Peter Wypych of the University of Wollongong, Australia. He is very knowledgeable in this area.
Regards,
Amrit Agarwal
Consultant
Pneumatic Conveying Consulting Services
polypcc@aol.com ■
Re: Moisture In Pneumatically Transported Powder
The gamma ray measurement is not based on ateenuation, but absorption.
The absorption coefficient depends on the energy of the gamma source: as lower energetic radiation, as more influence of the water (hydrogen) content on the measurement.
Cobalt 60 radiation is not influenced by the water content: the density measurement increases on the same manner for dry matter as for water, but a very big amount of product is required in the measuring path.
Caesium 137 is a good compromise.
Americium 241 radiation is very sensitive but also strongly influenced by moisture variations.
The choice of the measuring principle depends on the amount of ptoduct (g/cm2) present in the measuring path.
Capacitance sensors: the measuring effect depends on the frequency. As they work at rather low frequencies, they use to be also influenced by salt content, pH, etc... . See rather in the microwave domain.
I think that you may get good advice from Berthold Technologies, as well for gamma ray principle, as for microwaves:
www.BertholdTech.com
Best Regards,
Jean-Marie Weber ■
Moisture in pneumatically transported powder
Hi!
I have been talking to a manufacturer of a device for measuring mass flow of pneumatically transported coal. The technique used is gamma attenuation. I want to use this technique to measure the massflow of peat in pneumatic transport. The moisture content of peat can change from 4 to 12 per cent.
The problem I suggested was that varying moisture content effects the signal significantly. He then replied that if the moisture content increases for example 10% the massflow also increases 10%. Is this true?
Another question concerns capacitance transducers for measuring mass flow. How large in the influence of a variation in moisture on the sensor signal? Is the dependance linear with the massflow varation?
Thank you!
Marcus Svanberg
Vattenfall Utveckling AB ■