Pneumatic Conveying -High P. Low V. 1

[TedT]

I need to determine an economical velocity, supply air pressure, supply air quantity SCFM and friction loss per unit pipe length for:<br>
Material: e-s precipitator dust containing copper 32.8 LB/FT3, <br>
620 F material temp<br>
80% @ 0.05 microns, remainder up to 1 inch<br>
1-2% moisture by weight<br>
Material Flow 3,100 - 27,000 LB/HR<br>
Assume 200 FT straight delivery length plus bends.<br>
My main concerns are: What is a typical weight ratio LB Air/LB Material?<br>
What is a desired transport velocity?<br>
Where can I obtain friction factors? <p> <br><a href=mailto: ttracewicz@atsspartec.on.ca> ttracewicz@atsspartec.on.ca</a><br><a href= > </a><br>

 

[dprice]

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I presume with the problem statement development that you are in the conceptual phase of your project. If you are in the detailed phase I would need considerable more information to provide a sizing.<br>
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The air ratio is determined by whether economics dictate dense or dilute phase conveyance. You do not give a mineral breakdown of the dust. If it is mostly copper the erosion would be low against steels, therefore you could use either dilute or dense phase conveyance. Material to air ratiios can vary from 2:1 to 10:1 between dilute vs dense phase conveyance. With 200 feet of horizontal (?) conveyance length, dense phase may be the method of choice. In your case the pressure drop will be low and dense phase is not out of the question.<br>
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Desired transport velocity also is determined by selection of dilute or dense phase conveyance. If you are in the study phase of your project you should probably consider 5000-7000 fpm. This is a reasonable assumption.<br>
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Determination of friction factors for special materials may require laboratory modeling. If your preciptator is installed this may be the most cost effective way to assure project success. <br>
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I would consider with caution the particle size distribution you have listed. I do not know the basis of your numbers. The conveyance system should be designed with the "worst" case scenario in mind. But if you are in the scoping study phase your distribution looks rather good for conveyance. You can alleviate concerns about feed stream variation with some conditioning equipment. This is a normal precaution.<br>
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Regards<br>
<br>
Dan Price