Re: Design Pneumatic Conveying System For Pharmaceutical Powder…
Dear Joris,
I could not find a calculated velocity in your report.
But from a blower capacity of 175 m/sec and a pipe diameter of 21.46 mm, it is possible to do that.
21.46 mm = 0.02146 m # 3.141593/4 * 0.02146^2 = 0.0003617 m2
175 m3/hr = 175/3600 = 0.04861 m3/sec
velocity = Q/A = 0.04861 / 0.0003617 = 134.4 m/sec
This seems to be very high for particles of 14 micron and a bulk density of 400 kg/m3
Check for dimension errors between US units and SI units.
10 kg/hr over a length of 4.5 meter is a micro-installation.
When you say “blower” you are referring to a rootstype rotating lobe blower.
(see www.aerzener.de) .
I think that a small fan should also be considered for this job
success. ■
Teus
Re: Design Pneumatic Conveying System For Pharmaceutical Powder…
Teus,
Thank you for your quick response. My velocity calculation was indeed wrong. I connected the wrong cell in my excel file. I now have a pipediameter of 138.5 mm and a velocity of 3.23 m/s. Do you think this is possible?
You say that I'll be needing a fan. Is this a ventilator? Why do you need this while you have a rootsblower?
Is there something particular about microsystems which I should take into account?
Do you think that 175 is the optimal nitrogenflow? Is it not too fast? Maybe I could have attrition/erosion problems?
Thank you very much! You've been a great help!
Joris ■
Re: Design Pneumatic Conveying System For Pharmaceutical Powder…
Dear Joris,
Being used to pneumatic installations of 50 tons/hr to 1000 tons/hr, your installation of 10 kg/hr is “micro” to me. A matter of perception.
With a Solid Loading Ratio (SLR) of 0.0488, I expect only a minor pressure drop, due to material conveying.
A roots type blower, capable of 500 mbar is not necessary. A simple fan (or ventilator) can do the job as well.
Also your system seems to be considerably oversized.
(10 kg/hr over 4.5 m does not need a 5” pipeline)
Whether you will experience product deterioration depends on the vulnerability and the velocity of the material.
A particle of 14 micron and a product density of approx 800 kg/m3 will have a floating velocity in nitrogen (1.251 kg/m3) of about .0.488 m/sec.
A gas velocity of approx. 3.23 m/sec (7 times the floating velocity) seems a bit high, but OK.
A pressure drop calculation of your installation should result in a very low value for material conveying and gas resistance. The filter will be the main pressure drop and the presence of material will hardly influence the total pressure drop.(Indicating an oversized installation)
Success ■
Teus
Re: Design Pneumatic Conveying System For Pharmaceutical Powder…
just a note
Can you recalculate for a 20mm pipeline diameter?
keep the same saltation velocity.
have you considered any bend pressure drop ?
are you considering measuring and controling your nitrogen flow?
have you considered any control pressure drop?
Is the system fed with a screw feeder or you are trusting the orifice size to do the job?
Is your solid free flowing or will you need aerationn pans?
Do you have any idea of the solids flow roperties of the material?
like friction coefficient and arching dimension. impact and drum indexes.
how are you going to start your system and how are you going to stop it.
No neeed to solve all this problems , but mention them in your report , as data that needs to be aquired. your pofessor will love that. ■
Re: Design Pneumatic Conveying System For Pharmaceutical Powder…
Hi
I've been doing some calculations and my results are :
maximum pressure drop = 1000 Pa at 175 Nm3/hr
I'm looking for a ventilator (fan) that can do this. Does anyone know a site where I can find such a fan with information about the ventilatorcharacteristics ( flow in function of static pressure figure)?
Thanks a lot guys!
Joris ■
Re: Design Pneumatic Conveying System For Pharmaceutical Powder…
Dear Joris,
try
www.rucon.nl
Including calculations
success ■
Teus
Design pneumatic conveying system for pharmaceutical powder transport
Hi everybody!
I'm a student from Belgium and I'm working on a project about pneumatic conveying. I would like to know if I'm going in the right direction with my calculations.
Project :
Powder is moved from a mill to a separation mechanism by pneumatic transport. The pipe design is as follows : from the mill it starts with 1.5m vertical , then 1m with a precision angle of 10° and at last 2m horizontal.
I have to calculate the ideal pipediameter for pneumatic transport, pressure drop of this system , ideal nitrogenflow and a recommendation for the separation mechanism.
Specifications :
mass flow=10kg/h
density of powder = 400 kg/m3
particle diameter= 0.014mm
Blower can deliver 0 to 175 cubic meters per hour nitrogen
Calcalation method:
First I thought about the separation mechanism. I choose a bag filter. This was necessary to calculate the average density of the nitrogen in the pipe. My first estimation of pressure at the beginning of the pipe was : 101300 Pa (outside the filter) + 2000 Pa (pressure drop filter) + Equivalent length of the system*0.1kPa (this is a first estimation of the pressure drop in the pipes with dilute phase transport). With this I can calculate the average pressure in the pipes and with this the gas density.
Then I had to calculate the solids to gas ratio. I did this with a worst case flow of 175m3/h nitrogen. Is there a more ideal nitrogen flow? Maybe it's too much to work at the maximum of your blower? Solids to gas ratio is about 0.0488 kg powder/kg nitrogen.
Then I calculated with the Rizk formula on an iterative way what diameter would give a superficial velocity 50% higher than the saltation velocity. My calculations gave : Pipediameter = 21.46mm , Usalt=0.8464m/s , U= 1.2697m/s.
I calculated this with the rizk formule with pipediameter , particlediameter in mm and g in mm/s2. Is this correct?
With these numbers I calculated the pressure drop with the excellent atricle I got form Mr Amrit Agarwal : 371. 94 Pa. This pressure drop you could fill in back in the beginning of the calculation and do it all over again (iterative).
Do you guys think this is ok? I would like to know what you think about the ideal nitrogen flow. Can this pipe design be done better? What other design do you propose and why?
What kind of blower is it that can deliver 0 to 175 m3/h? Can somebody tell me where I can find the specifications of such a blower?
What kind of materials should I use for my design?
Thank you for your help
Joris Dewit
KU Leuven
Belgium ■