Pneumatic Conveying Fine Powders
From the description you have given it is difficult to understand why you are having the problems in pneumatic conveying of the fine powders that you have listed. All of these powders can be conveyed in dilute phase mode if the conveying system is designed correctly. In my opinion, dense phase conveying of these powders should be considered only if that option is economically more attractive.
You could design the dilute phase conveying system your self if you want to and know basic Excel. My article "Theory and Design of Dilute Phase Pneumatic Conveying Systems" gives this calculation method.
If you still need any help, you may contact me.
Regards,
Amrit T. Agarwal
Consulting Engineer
Pneumatic Conveying Consulting LLC
Email: polypcc@aol.com
Ph and Fax: 304 346 5125 ■
Try Dense Phase Conveying
If all of your materials are minus 325 mesh it is likely that they will all be capable of being conveyed in dense phase and hence at low velocity, quite naturally. For powders, low velocity dense phase conveying is nearly always significantly more economical than high velocity dilute phase conveying.
For 2 to 7 ton/h a single blow tank system would be ideal for conveying in batches. If the conveying distance is short this need only be a low pressure system using a positive displacement blower. ■
Dense Vs Dilute Phase Economics
Studies that I have done clearly show that dense phase becomes more economical than dilute phase only if an existing source of conveying gas/air is available. If a new blower or compressor is needed for dense phase, this additional investment tilts the economics in favor of dilute phase.
This is especially true if continuous conveying is required and not batch. In that case a rotary valve will be more economical than a blow tank.
But because these results can change based on conveying system design and requirements, it would be good to carry out an engineering and economics study before making a decision.
Regards,
Amrit T. Agarwal
Consulting Engineer
Pneumatic Conveying Consulting
Email: polypcc@aol.com
Ph and Fax: 304 346 5125 ■
Re: Conveying Fine Powders
Dear Mr Graham,
The powders, you mention should be easily being conveyed pneumatically as the mesh size is less than 325 (44 micron).
And also 2 to 7 tons/hr is rather low.
I cannot estimate a rough design for f.i. cement, as you do not state the distance and number of bends.
Dense or dilute phase is not important, if you use an (little) oversized blower with a frequency regulated drive, in order to adapt the air flow to the product being conveyed.
Depending on the setup of you equipment, you have to choose a way to mix the product with the conveying air. (f.i. rotary lock, blow tank, or other)
After you have calculated a pneumatic conveying lay-out for the worst product, the rest will follow.
Success ■
Teus
Re: Conveying Fine Powders
Mr. Gtaham
Before embarking on an academic economic study or exploring a completely different type of system, it may be prudent to first see if the existing system can be made to function as intended.
A large part of our business is to trouble shoot existing systems and make the necessary recommendations to correct any shortcomings.
If you would like some assistance in evaluating what you currently have before embarking in a new direction - please feel free to contact us.
Regards ■
Pneumatic Conveying System
Thanks for your quarries.
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Proposals Deptt.
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A Number Of Possible, Non-Pneumatic, Conveyor Types That Might …
This is a great question, Jim. There are a number of possible, non-pneumatic, conveyor types that might work as single solutions or in combination. But, we must be able to properly analyze the application before making a recommendation.
To best answer this question I need more info. First, what are the bulk densities of the ground/milled products? Second, what specific problems are being experienced? A number of possibilities come to mind when considering conveying of very fine powders, but to provide a valuable answer we need to know the details of what is currently happening. Third, what is the layout of the conveying run? Distance from the lines to the silos/truck load out area? Horizontal and vertical dimensions, obstructions, etc. Fourth, abrasiveness – we can make general assumptions about abrasiveness, but specific material origin and particle characteristics, size and shape can have a significant impact on abrasiveness.
Feel free to reach out to us via https://www.spiroflow.com or email me directly at dmackrill@spiroflow.com and we would be happy to talk more in detail about the best solutions for conveying fine powder.
Thanks,
Don ■
Conveying fine Powders
We have a new grinder for producing fine powders. WE are grinding varity of materials, cement, barite, zeolite, feldspar, limestone, etc. to fine powders, minus 325 mesh to minus 10 microns to demonstrate the grinder. Through put rates varies from 2 to 7 tons per hour depending on the material ground and size requested. We are setting up two processing lines, one with a Progress Industries classifier for very fine powders and one for using a 6 ' Strurtevant classifier for minus 325 mesh powders. We are having problems conveying the finished product from the classifiers to storage silios and bulk hauler trailers. We are considering eductors or dense phase systems. We need flexibility and reliability. Our experience with conveying fine powders is limited. Any recommendations? ■