Dear Amrit,

Thank you for your reaction on this thread.

I think that you have point in stating that there are conflicting answers in the pneumatic conveying society , although only very little in this forum.

If you search the internet for articles and thesis on this subject, the variety of mathematical approaches is really mind blowing.

This should be a reason, why this forum should attract more people to join the discussion.

Let me try to summarize the existing calculation methods.

-Most of the calculations are based on the required energy (pressure drop) for a gas flow through the conveying pipe, whereby the influence of the presence of material is accounted for by a factor K, which calculates the material pressure drop as K times the gas pressure drop.

-Additional pressure drops (for elevation, kinetic energy, filters, bends, clean gas lines) are calculated separately.

-The K factor is measured in lab- or field tests and from those tests, scale factors are derived and regression formulas are constructed.

-Sometimes, bends and vertical pipe are accounted for by “equivalent length”.

Missing in these calculations are the dependency of the K- factor on the SLR and the direct calculation of the material velocity and the interaction between small- and coarser particles.

Also missing are the influence of:

-Compressor characteristics (internal leakages)

-Heat transfer between gas and particles and with the surroundings, leading to density changes of the gas and thereby to velocity changes.

-Sedimentation detection at too low gas velocities along the pipe wall.

-The influence of laminar- or turbulence conditions of the gas flow

-The influence of the SLR and the Re-number on the Solid loss factor.

As a pneumatic conveying calculation starts with 2 unknown variables (Capacity and pressure drop), one of them has to be set and the other calculated.

The requirement that the input and the output must be consistent, only an iterative calculation can solve this.

All these considerations, do not make the variety of programs wrong, because they can match the reality by incorporating the missing influential factors in the K-factor, acting as a “fudge factor”.

Understand that I do not think that your calculation method is wrong, because the basis is proven physics and sound mathematics.

You shared this program with the underlying theory and mathematics and thereby the restrictions.

Before I retired (9 years ago), I was a project manager and a technical manager in grain unloading and cement, alumina, fly-ash, etc. unloading and discharging.

To do my job properly, I had to investigate the physics and mathematics of pneumatic conveying, as well as the working and influence of the applied equipment (compressors, tanks, rotary locks, screw pumps)

I was able to do this, because I had a 1 to 1 scale laboratory of multiple machines and installations at my disposal.

And the opportunity to modify these machines for better performance, whereby the theory was tested and verified, which in return led to adaptations of the theory.

From this long time career, I made a document of the found pneumatic conveying theory and built a pneumatic conveying calculation program, with which it is possible to calculate, not only a pressure drop at a certain capacity, but all the influences of the selected equipment on the performance.

Once, I found by the calculations, where a blockage was expected in an alumina unloader, based on the calculated performance and the actual performance. After checking, we found the blockage and removed it, increasing the performance by approx. 20%

For an introduction to the program:

see: www.yarca.nl

Conflicting or confusing answers should not be a reason for growing lack of interest, but for a growing interest.

Lack of interest indicates: giving up.

And, through my work for Yarca pneumatic conveying software, servicing companies with consultancy and calculations, I experience that the customers are satisfied. ■