Re: Small Pneumatic Conveying System
Hi Stephen,
I too have been trying to design a small portable system for another purpose. An answer to your problem may lie in a "insulation blower" used for blowing cellulose fibre into roof cavities. From your design diagram and description of your desired goal this may well be suitable. Readily available worldwide and relatively cheap. The only issues that may arise is impact damage to the beads as on these machines they pass THROUGH the blower itself, and the machines have an agitator (to break up clumps of insulation) which would need to be disengaged.
At the very least one of these machines may be able to be used as a basis with mods to suit your requirements.
Hope that helps. ■
Re: Small Pneumatic Conveying System
Dear Steven,
From your description, I understand that you have the opportunity to experiment.
Being a small scale installation, the experimenting can take place at approx. full scale.
You have to figure out how much air you need in a 1”pipe to get sufficient velocity at a required dosing capacity.
And additionally, you have to determine the necessary pressure to achieve the desired performance.
The first indication for the required velocity in the 1”pipe is the suspension velocity of the particles.
V-suspension= SQRT(4/3*d/c-drag*rho-material/1.293)
c-drag=0.05
Take the air volume as approx. 10*v-suspension in the 1”pipe.
Using an air flow meter (floating body in a tapered glass) and start experimenting.
Start with no material feed and measure.
Subsequently, increase the feed rate in small increments and then observe and measure again.
Repeat this for various airflows.
Because of the short length (5m), the pressure drop is mainly acceleration loss.
The installation needs also a filter system at the end for separating the material(dust) from the conveying air.
Whether the presence of oil will become a problem for the filter has to be found out.
There is also a choice to be made, whether you opt for a vacuum- or a pressure system.
Are you sure that 5m of conveying for only 60L of beads is worthwhile for a (small) pneumatic conveying system?
Interesting to know the result you get.
Have a nice day
Teus ■
Teus
Re: Small Pneumatic Conveying System
Dear Teus,
Apologies in advance but I am new to this technology.
I calculated as follows
The bulk density is 690g/L (or kg/m3)
I guessed the particle density is 1200g/L
The particle size is 5mm or 5e-3m
Drag factor you provided is 0.05
Plugging this in I get
vsuspension = SQRT(4/3*1200/0.05*5e-3/1.293) ~= 11m/s
For 1" pipe, the area = PIr2 = 5e-4m2
Thus volume flow = 11*5e-4 = 5.5e-3m3/s ~= 0.33m3/min = 11.7CFM
Based on this information and the results of the equation, I would need a compressor that produced 11.7 CFM, is that correct? I have attached a simple diagram of the layout I propose.
I have a need for a portable conveying system and I believe a pneumatic system to be the most sensible. Are there alternatives? ■
Re: Small Pneumatic Conveying System
Apologies, I forgot set-up diagram.
Kind Regards,
Stephen
Attachments
extraction_process_201109 (DOC)
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Re: Small Pneumatic Conveying System
Dear Stephen,
The suspension velocity of approx. 11 m/sec is correct.
Then the conveying air velocity needs to be approx 3*11=33 m/sec.
(Not the 10 times as I indicated in my previous reply)
The free air delivery (FAD) of the compressor is then calculated as:
33*pi/4*0.0266^2=0.01834 m3/sec
#1.1 m3/min
# 39 CFM
For a mixing eductor that you are intending to use see:
http://www.foxvalve.com/frameset-conveying.html
As you are new to this technology, you can also visit:
Pneumatic conveying, Performance and Calculations:
https://news.bulk-online.com/?p=65
Dense phase- or dilute phase pneumatic conveying:
https://news.bulk-online.com/?p=238
Pneumatic conveying, turbo- or positive displacement air mover:
https://news.bulk-online.com/?p=309
Energy consumption per ton of a pneumatic conveying system:
https://news.bulk-online.com/?p=331
Pneumatic conveying, an unexpected relationship.
https://news.bulk-online.com/?p=445
Pneumatic unloaders: Problems to avoid
https://news.bulk-online.com/?p=74
Influence of electro static charge on pneumatic conveying.
https://news.bulk-online.com/?author=15
If you know the required capacity, a first estimate of the pressure drop is possible, by assuming that the pressure is mainly caused by acceleration and elevation.
Separating the material from the convey air requires a vertical can velocity in the receiving bin from approx 5 m/sec.
If there is any dust or oil mist generation, this must be addressed as well.
Success
Teus ■
Teus
Re: Small Pneumatic Conveying System
Hi Teus,
39 CFM from a portable compressor is not achievable hence I understand your direction towards a venturi. However we tried a venturi and it atomised the oil on the beads although we tried a crude filter to prevent this it did not work. Perhaps we had too great a pressure and flow rate from the compressor, I believe it was a screw compressor but I cant recall its specification? Maybe I could try a small compressor (6-8CFM) or portable blower with a venturi adapter?
The portability of the system is paramount, e.g. it needs to fit on a small van and be used externally, hence the use of compressors. I have yet to see portable blowers. I imagined a simple system with a compressor propelling the material.
What do you think?
Kind regards,
Stephen ■
Re: Small Pneumatic Conveying System
Dear Stephen,
8 CFM in a 1” pipe results in a conveying velocity of approx. 6.8 m/sec.
This is below the suspension velocity and will result in a choked pipeline.
As long as we do not have an idea of the required pressure, it is not opportune to discuss a compressor type.
It could well be that a fan can do the job.
If an educator is not an option, then you have to install a rotary lock, to separate the conveying pressure from the feeding bin.
Have you already considered a mechanical solution?
Have a nice day
Teus ■
Teus
Re: Small Pneumatic Conveying System
Hi Teus,
If I use an educator or an air-conveyor (https://www.stream-tek.com/products/...r-conveyor.php) it will move the beads but it will also generate significant oil mist (our test filled the laboratory with a cloud of oil droplets). How do I separate the beads from the oil-soaked air flow?
Kind regards,
Stephen ■
Re: Small Pneumatic Conveying System
Dear Stephen,
Pneumatic conveying has always a relative velocity between particles and conveying air.
Hence, any adhering oil will be blown off from the beads.
An eductor is a feeder device for a pressure powered pneumatic conveying system.
The air conveyer creates a vacuum and this vacuum can be used for a pneumatic vacuum conveying system.
Separating oil mist from an air stream requires an oil separator filter. (with the accompanying pressure drop)
BR
Teus ■
Teus
Small Pneumatic Conveying System
Hi,
Just a thought!
Have you considered a "tube-chain" conveyor?
Regards,
Dave ■
Small Pneumatic Conveying System
Hi Stephen,
Have you considered a "Tube-chain" conveyor?
Regards,
Dave ■
Re: Small Pneumatic Conveying System
If removal of oil from the beads is not acceptable, high velocity conveying such as dilute phase should not be used. Instead, use very low velocity dense phase conveying.
Regards,
Amrit Agarwal
Consulting Engineer
Pneumatic Conveying Consulting
Charleston, WV, USA
Email: polypcc@aol.com
Ph and Fax: 304 346 5125 ■
Pneumatic Conveyor For Bead
Send to me the picture of bead to e-mail: setavietnam@gmail.com, I can help you determine exactly blower you need.
With my best Regards,
Eng. Pham Van Quyet-Managing Director
Cell phone: (+84) 986 333 375
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Small Pneumatic Conveying System
Hi All,
■
I have a small project where I need to convey small oily beads (~3-4mm beads coated in oil) from a vessel to a container. The vessel is finished with a 1" T-piece into which the beads fall. I am playing with using a compressed air system to move the beads along a 1" pipe over a distance of about 5m. I have read through some of the threads on this interesting forum and realise that what I am asking is very small scale. The bead volume is of the order of 60L. I have used a venturi adapter in a trial and although it shifted the beads it also atomised the oil which was difficult to contain. We have had a preliminary trial with a compressed airline with limited results but not atomised oil. My question is this; should I use a portable blower, if there is such a thing? Or what type of compressor should I use? My understanding is that the beads will fall from the vessel due to gravity and the small vacuum created by the ?T-piece and be propelled by the air flow but I do not know how I should relate this airflow to the compressor or blower I should use. Any help would be appreciated. Kind Regards,
Stephen.