# Thread: Pressure Drop in Pneumatic Conveying

1. ## Pressure Drop in Pneumatic Conveying

Pressure Drop in Horizontal & Vertical Conveying

My case is as follows:

Dia of pipe : 53mm
Length of pipe : 5m
Density of solids =2530 kg/m3
air mass flow rate = 0.0324kg/s
solid mass flow rate = 1.2184kg/s
Particle size = 30 micron

I want to find the pressure drop for this case in horizontal and vertical flow. Can anyone tell me what are pressured drop values . I want to do numerical simulation and compare the results.

Thanks
Regards
PP

2. Dear pandaba,

Based on your limited data, the pressure drop is calculated as:

Horizontal:
with 1 m2 filter: pressure drop = approx. 0.17 bar
without filter: pressure drop = approx. 0.082 bar

Vertical:
with 1 m2 filter: pressure drop = approx. 0.22 bar
without filter: pressure drop = approx. 0.13 bar

The compressor conveing pressure can differ a lot by extra clean air piping and ambient and material temperatures.
The material is unknown.

Have a nice day
Teus

3. Thanks teus for kind reply.

My case is flow of fly ash in a pipe . I need some data on particle - particle and particle-wall collision for pneumatic conveying of flyash.

Thanks and regards
PP

4. Dear pandaba,

The material pressure drop in your system is only a small part of the total pressure drop.

The Solid Loss Factor, which you are asking for, is related to the calculation algorithm that you are using.

If I give you the SLF, I am applying, as 4.58*10^-12, it does not mean anything to you.

What you can do is calculating with your own program the SLF, which matches the given pressure drops in the previous reply.

Success
Teus

5. Hi Teus,

I am again coming back to this discussion. I want to know What is meant by solid loss factor. Can you please explain a bit more .

Also how to predict the pressure drop in horizontal gas solid flow. I found from simulation that the gas velocity, particle dia , density , pipe dia and loading ratio have high impact on pressure drop. Considering all these , how to predict pressure drop.

6. Dear pandaba,

The Solid Loss Factor is a product related value that, in a formula, accounts for the energy losses, due to inter-particle- and wall collisions.

The calculated energy loss is, through the appropriate formulas, expressed in a pressure drop.

The total pressure drop is the sum of all partial pressure drops (air, elevation, suspension, acceleration, product)

There exists no direct way to calculate the pressure drop in pneumatic conveying, as a calculated pressure drop is influenced by itself (Caused by the expansion of the air)

An iterating, numerically integrating, algorithm can solve this problem. (Approx. 45 Mb VB software)

Take care
Teus

7. ## Check my software solution

Hi there, have a look at my state diagram and software. It is an iterativ, numerical overall calculation, that apart from an interpolated estimated value for the pressure loss additional information provides. So, the given data belong to a dense phase conveying system near the instable transition area, and the pressure loss in a horizontal pipe will be around 0.11 bar. These results are confirmed by published field data of similar conveying lines. However, the question remains, how precisely the parameters can be read from the relatively rough state diagram.

These are the published data for a comparable conveying system: Material SiO2, 10 microns, bulk solids throughput 4000 kg/h, gas flow 100 Nm3/h, pipe diameter 65 mm, horizontal pipe length 30 m, pressure loss 0.3 bar (that meets exactly the calculated value).

Moreover shows the state diagram, that different conveying conditions are possible, so, for instance a lower gas flow at higher pressure loss. How can one say which the stable conveying conditions are? A good example for the wide variation of conveying conditions was published by

Krambrock, W.: Dichtstromförderung. Chem.-Ing.-Tech. 54(1982)9, S.793-803

The diagram shows a field of possible conveying conditions at maximum mass flow of bulk solids which lie on the left (upper) border of the state diagram.

Kind regards
ManfredH
Last edited by ManfredH; 25th March 2012 at 15:05.

8. Originally Posted by pandaba
Pressure Drop in Horizontal & Vertical Conveying

My case is as follows:

Dia of pipe : 53mm
Length of pipe : 5m
Density of solids =2530 kg/m3
air mass flow rate = 0.0324kg/s
solid mass flow rate = 1.2184kg/s
Particle size = 30 micron

I want to find the pressure drop for this case in horizontal and vertical flow. Can anyone tell me what are pressured drop values . I want to do numerical simulation and compare the results.

Thanks
Regards
PP
Dear Pandaba,

Please refer to my article "Theory and Design of Dilute Phase Pneumatic Conveying Systems" for calculating the pressure drop values. In this article you will find that the pressure drop due to the flow of solids depends upon the solids friction factor. Unfortunately, this value has to be determined from actual test data for this solid, there is no analytical method available for its precise calculation. I can give you an approximate value if you send me a small sample.

Regards,

Amrit Agarwal
Pneumatic Conveying Consulting
polypcc@aol.com

9. ## Are friction factors in dense phase conveying really needed?

Originally Posted by Amrit Agarwal
Dear Pandaba,

Please refer to my article "Theory and Design of Dilute Phase Pneumatic Conveying Systems" for calculating the pressure drop values. In this article you will find that the pressure drop due to the flow of solids depends upon the solids friction factor. Unfortunately, this value has to be determined from actual test data for this solid, there is no analytical method available for its precise calculation. I can give you an approximate value if you send me a small sample.

Regards,

Amrit Agarwal
Pneumatic Conveying Consulting
polypcc@aol.com

Dear Amrit,
the state diagram, developed by me, does not use friction factors for the calculation of pressure losses, especially in the dense phase conveying of fine materials which are easy to fluidize. As the diagram indicates, is the main factor in such cases the state of the turbulent gasflow and the energy, that is provided through turbulent eddies and pressure gradients, for fluidizing a particular mass of bulk solids, that is thereby kept moving. Published field data show, that even moist sand of 200 microns, that is most likely considered for a cohesive material, fits in the state diagram, but with a very low gas flow rate at high pressure loss (plug conveying?!). For this reasons I am not sure whether at least in my diagram a friction factor is really needed. It is possibly a hidden parameter indicating stable conveying conditions or so.
Kind regards
ManfredH
Last edited by ManfredH; 24th March 2012 at 16:28.

10. Hi all

I have a requiremnt to fluidize coffee and the only information I have is physical properties of coffee.

I have assumed the drag co-efficient of coffee as 0.1(assuming spherical beans), and calculated the terminal velocity.

But I have no idea regarding the pick-up velocity or the required pressure drop to convey or fluidize coffee.

I would really appreciate if anyone can suggest the procedure or a book which can help me more.

Regards
Vineet