Wood Pellets
It is all dependant on the size of the blower you use in you vacuum system. ■
Pick-Up Velocity
Gert,
Please give the pipeline diameter at the pick-up point and also clarify the particle sizes that you have given (minimum and maximum). I could not understand what was meant by 1-1 mm. Do you also need conveying velocity in the pipeline? That will depend on the location of the bends in the pipeline and the pressure rating of the conveying blower.
Regards,
Amrit
Amrit Agarwal
Consulting Engineer
Pneumatic Conveying Consulting
Email: polypcc@aol.com
Ph and Fax: 304 346 5125 ■
Re: Pickup Velocity
Amrit,
The smallest particles measure 0,1mm and the largest 1mm in diameter. I used the calculations from your article and came up with the next results:
Pipe diameter: 14''
Inlet velocity: 50 ft/sec
I need help with the required pressure in the inlet for a vacuum system, I can't deside how big it should be. The system I'm designing should extract dust from a flow of pellets 200000 T/h
and I'm afraid that if the inlet velocity of the gas is too big or the vacuum too great then the system will start to pickup pellets aswell as dust.The whole lenght of the system from the inlet to the separator(cyclone) is not longer than 60 feet with 3 bends 90 degrees each.First bend is situated 5 feet from the start (inlet), then comes a straight horizontal section of 20 feet, then a 90 bend, then a 30 feet vertical part, then a bend again and a 5 feet horizontal section which ends in a cyclone. The fan comes after cyclone. The whole system should be able to extract 20000 T/h of dust. I'm still choosing the blower because I'm not sure about the pressure losses in the system and the material behaviour.
Regards
Gert ■
Re: Pickup Velocity
Gert,
From your write-up it looks as if you want to use the pneumatic conveying system to remove dust from the pellets. Is this true? If your incoming material contains separate fractions of dust and pellets the conveying system must be designed for handling both. Separation of such mixtures is normally done in equipment at the end of the conveying system. For high efficiency separation typical name of this equipment is "elutriator". Cyclones are used for lower efficiencies. They can be bought from vendors or designed in-house.
Regards,
Amrit Agarwal
Consulting Engineer
Pneumatic Conveying Consulting
Email: polypcc@aol.com
Ph and Fax: 304 346 5125 ■
Re: Pickup Velocity
Gert
You indicated that the particle size range for the product you want to remove is 0.1 to 1 mm. For that range, pick up velocities as low as 2000 fpm would work, it depends how the size range is distributed. More of the smallest size or more of the larger size. In worst case, 3000 fpm would adequatley handle the largest size.
You don't mention the particle size of the wooden pellet, but typically, pellets will have a pick-up velocity range of 3600- 4200 fpm.
In any system where dust is beign removed, there is usually some percentage of good pellet carryover. Usually < 0.5%. This asures that dust removal is maximized.
You also mentioned you were concernd about the high vacuum at the pick up point. In a vacuum system, the vacuum is the lowest value at the pick-up point and increases in the direction of the discharge.
Regards ■
Re: Pickup Velocity
Amrit,
I used the calculations you sent and came up with the following results:
solids conveying rate: 44100 lbs/h
Pipe diameter 10''
pickup velocity 45 ft/sec
Solids to mass flow ratio: 6,65
Gas mass flow rate: 6627 lbs/h
Equivalent pipe length: 120 ft
total pressure loss: 1 Psi
I decided to coose a blower: gas flow 10000 m3/h and pressure rize 2500 Pa, 3000 rpm , 18,5 kW
I'm not sure if the pressure is adequate to meet the requirements of my system.
Maybe somebody who has experience with vacuum conveying could say if I'm on the right track with my calculations.
Regards,
Gert ■
Re: Pickup Velocity
Handling pellet dust is not like handling ANY OTHER KIND OF DUST... beware. Do your homework. ■
Pneumatic Conveying
Can someone please send me the excel sheet for calculation of dilut & dense phase pneumatic conveying by Mr. Agarwal.
My email ID is ronnyfernandes@fwuk.fwc.com or ronnyfernandes@rediffmail.com
Thanks for the help!!!! ■
Pickup velocity
Hi,
Does anybody know the pickup velocity of wooden dust (particle size 0,1-1mm, density 150 kg/m3) coming from pellets and also suggest the pneumoconveying speed for that kind of bulk?
Regards
Gert ■