Re: Dust Return Method
Dear Calvin.wck,
I wonder why the filtered dust on top of a silo has to be transported to a separate bin, instead of dropping the dust back into the silo.
If you want that anyway, a solution would be to install the filter with the exhaust fan on top of the FK feed bin. (Probably you have a dedusting filter on top of that bin anyway)
Then you only need a pipe from the top of the silo to the FK feed bin.
The fan maintains a downward draft for conveying.
The pipe from the silo must go up under an angle of 60 degrees and then downwards under the same angle with the horizontal or steeper.
Check the dimensions and ratings of pipes, filters and fans for proper operation.
Using gravity in a 50m high pipe works only when you are sure that there is nu upward draft or convection in the pipe.
Take care
Teus ■
Teus
Re: Dust Return Method
I have not say the whole story..it is quite complicate process.
The DC on the silo (~50m) is for gas discharge from grindlng mill at ground. The air come from mill first pass to cyclone and then fan and finally divert to DC. DC dust now, in fact, is return to silo.
But, the dust fineness actually is small enough to be pulverized fly ash as product. Thus, the dust can be return to product bin at ground level.
This is old design and we don't want to make a big modification under poor economic situation. Therefore, a connection between DC and product bin is wanted.
Then, a straight downward duct is come up.
1. Upward draft depends on the duct pressure in the process. I will check.
2. Convection, what is it?
Many thanks ■
Re: Dust Return Method
Convection is mass flow of a gas or a liquid, induced by temperature or pressure differences in the mass itself.
F.i. natural draft in a chimney, due to a higher temperature in the duct than outside the duct.
BR ■
Teus
Dust Collector
Because of high drop velocity a 50 meter long vertical duct will create lot of dust at ground level, requiring another dust collector. Obviously, this is not a good solution.
Discharge into the feed bin of the FK Pump will be better if a dust colllector is installed on this bin.
Another option is to use a small venturi eductor to convey the dust to the FK feed bin. This will replace the large duct with a small pipe but will still need a filter for the FK Bin.
Regards,
Amrit Agarwal
Consulting Engineer
Pneumatic Conveying Consulting
Email: polypcc@aol.com
Ph and Fax: 304 346 5125 ■
Re: Dust Return Method
Originally Posted by Calvin.wck
The dust return from dust collector will be diverted to feed bin of FK pump at ground level.
Could anyone suggest a method to transfer the dust from high level to ground level?
I think one easy way that transfer the dust in a straight duct by gravity, but whether any problem or issue should be addressed.
Thank you
How ever you choose to move forward with this, you're going to need duct to do so. I would suggest Nordfab as they provide a clamp together system that can be moved around with no problem. They can also assist with design if you need that - not sure if there's a charge, but you can probably find out by visiting their website: www.nordfab.com. Hope that helps! ■
Re: Dust Return Method
Before I design a dust return method, I need to esimate the dust content in exit gas from fly ash grindling mill. The mill is end discharge type.
From Duda cement data book, dust content in a grindling mill is 20-80g/Nm3. Do any peers have any advice for the dust content? ■
Dus Return Method
The amount of dust depend on the actual mill, product and design.
You mention that you have cyclones in front of the filter? so some of the dust is also seperated out there.
It would be helpfull if you maybe have a sketch of you system, and dimesions of airflow, cyclones filter etc.
Regards
Henrik Friis
Dantherm Filtration
hefr (at) danthermfiltration.com ■
Untitled
process flow
1. mill -> cyclone -> fan (200m3/m3) -> up 50m to dust collector (DC1) on silo top
2. pneumatic conveying (80Nm3/min) -> silo venting -> dust collector (DC1)
Therefore, there are two sources for the return dust.
I think the worse case is the dust coming from mill (80g/m3) plus from silo venting (g/m3).
This is my data for design.
But want to hear more idea from the peers. https://forum.bulk-online.com/images/icons/icon10.gif ■
Dust Return Method
One dust collector for air from fly ash grinding mill is placed at the top of silo (~50m from ground).
The dust return from dust collector will be diverted to feed bin of FK pump at ground level.
Could anyone suggest a method to transfer the dust from high level to ground level?
I think one easy way that transfer the dust in a straight duct by gravity, but whether any problem or issue should be addressed.
Thank you ■