Re: Short Distance Problem (≪5m)
Dear Mohsenbulk,
1)
Starting with the formule:
m2 = m1 * (L1/L2)
gives,
m*L = constant
Where m = SLR * air mass flow
hence,
SLR = constant/(air mass flow * L)
However, in practice and verified by calculations, the following relationship is valid:
SLR = constant * L^(-factor)
The constant and the factor are related to the material to be conveyed.
Additionally the designed velocities of the compared systems have to be equal.
Moreover, the length of the installation must be long enough in order to achieve that the acceleration pressure drop is not dominant in the total pressure drop.
2)
For a conveying distance of 2 m of length, the acceleration pressure drop is the main partial pressure drop.
The calculation then becomes; How much material is accelerated to a certain velocity, what pipe diameter is needed and how is the air velocity (respectively airflow) determined?
The air velocity is determined based on the suspension velocity of the particles.
It might be possible that the particles do not reach the quasi-stationary velocity within the 2 meters
A pneumatic conveying calculation will show the results.
3)
Solid Loading Ratio (SLR) = (material mass flow)/(gas mass flow)
SLR is in (kg/sec material)/(kg/sec gas)
SLR is only a relationship, that often appear in theory and calculations and is to be considered as a calculation unit, describing an important property of a system.
Any experiment will be at a certain SLR. To be able to correlate the SLR to system- and material parameters, require many experiments and a consistent theory and calculation algorithm.
Also visit:
Pneumatic conveying, Performance and Calculations:
https://news.bulk-online.com/?p=65
Dense phase- or dilute phase pneumatic conveying:
https://news.bulk-online.com/?p=238
Pneumatic conveying, turbo- or positive displacement air mover:
https://news.bulk-online.com/?p=309
Energy consumption per ton of a pneumatic conveying system:
https://news.bulk-online.com/?p=331
Pneumatic conveying, an unexpected relationship.
https://news.bulk-online.com/?p=445
Have a nice day
Teus ■
Teus
Short Distance Conveying
For such short distance conveying the rules of thumb that you have are not applicable. You will have to run calculations.
2 or 3 meters is a very short conveying line. What is its diameter? We need about 20 pipe diameters of the conveying line to accelerate the solids to the minimum conveying velocity. Therefore, the acceleration pressure drop will be the major part of the pressure drop.
It is easy to run these calculations using the method given in my article. Suggest you get a copy.
Regards,
Amrit Agarwal
Consulting Engineer
Pneumatic Conveying Consulting
Email: polypcc@aol.com
Ph and Fax: 304 346 5125
, ■
Thanks For Replys And Questions
Dear Mr.Tuinenburg ,
thank you for your reply.
but I didn't understand from your Post that is a such high Phi applicable?
and do you mean that It is necessary for me to run a test program and calculations are not possible?
and dear Mr. Agarwal,
I knoe that rules of thumb are not applicable for me. But the question is that is there any other correlation for such a short distance?
I will be glad to have your paper if you don't mind email me that. I have emailed you with your requested agreements. please reply to that emil soon.
and does anybody have an experience with such short distances in dense phase?
Best regards,
Mohsen ■
Re: Short Distance Problem (≪5m)
Dear Mohsenbulk,
Can you explain what you mean with “that is a such high Phi applicable?”
If you want to know the relationship “SLR = constant * L^(-factor)”, then you have to know the conveying properties of the material.
The conveying properties of the material can only be derived from built installations or test installations.
Combined with a calculation algorithm, a series of installations (complying with the mentioned conditions of equal velocities and pressure) can be calculated.
The found curve can be converted into a regression line, being the requested relationship.
This regression formula deviates for short distances, because of the non-conformity in the division in respective pressure drops. (Acceleration is dominant for short lengths)
If you already have the conveying properties of the material, you can skip the field experiments and calculate straight away. A SLR relationship to conveying length is then also not necessary anymore, because a direct calculation is possible.
Have a nice day
Teus ■
Teus
Re: Short Distance Problem (≪5m)
Dear Mohsenbulk,
which product you will transport? And which capacity you need? May be in this forum thare are people who have experience with this product and with their help you need to do any test pipe to calculated properties of the product.
regards ■
Short Distance Conveying
Hello dears,
thank you all for your kind replies
I'm designing a test stand for my powder to obtain conveying data for this short distance.
My powder is cement portland 14 micron.
does anybody have any experience with that?
regards,
Mohsen ■
Re: Short Distance Problem (≪5m)
Dear Mohsen,
The conveying properties of Portland cement are known, there is no need whatsoever to set up a test facility.
The 14 microns, you mention is rather fine for cement.
The short distance (< 5m) allows a very high SLR.
If you supply more installation details of your intended project, it is possible to reply in a more specific and to the point way.
An indicative calculation is then easily made.
Best regards
Teus ■
Teus
Short Distance Problem (<5m)
Hi everybody,
my problem:
I am trying to design a pneumatic conveying system for a short distance(L=2m).
There is a correlation in "Pneumatic conveying design guide" for scaling for distance when you use conveying data method, that is :
mdot2=mdot1*(L1/L2)
the problem is that when I use this correlation for 2 m, it gives a very big Mdot and so a very big PHI(solid loading ratio) about +300 up to 1500!!!!!
It is written in the book that this correlation is approximately for about the same length and has used it for up to 0.3
my questions:
1) Is there any other correlation for a wider range of L1/L2 or for short distances about 2 meter?
2)Is there anybody here who have experienced and compared short and long distance mass fluxes(for example compare 2 and 50 m fluxes) and can give me a physical understanding or rule of thumb for that?
3)Does this high solid loading ratio have a physical meaning? can it be achieved experimentally?
thanks in advance
Regards,
Mohsen