Jack,

Commercial software is certainly available but I have found none that I would consider both robust and reliable.

There is a built-in problem with commercial software. One can access the input and output sections but the calculation section is proprietary and inaccessible to the user. Accompanying documentation may include the correlations that are used, but without access to the program you must have blind faith in the results. In God I trust, others must show data.

Calculation methodology based on first principles is available in the literature. It is possible to write one’s own program, balancing the time invested with the desired degree of robustness and reliability. Many global companies, including suppliers of conveying plants, have taken this approach.

My thoughts,

Dennis Hauch ■

Because of the many different conveying system designs, there is no software package that can predict the performance of any pneumatic conveying system.

Dynamic Air, for example, has developed our own software package to design

and predict the performance of the Dynamic Air equipment design conveying a

specific material.

My suggestion for your question is to contact the manufacturer of the

equipment in question, make sure this manufacturer has tested the specific

material to be conveyed, and have the manufacturer do the performance

calculations based on his equipment and the test of the specific material to

be conveyed.

It should be noted that if the equipment manufacturer is unable to base the

performance calculations on the specific material to be conveyed, the

calculations potentially would be in error. This is because all materials

of the same chemical properties do not handle the same. Factors such as

bulk density, particle size, particle size distribution, particle shape, moisture content, etc. have a great influence on the pneumatic conveying

performance. In our system performance database, for example, we have

tested over 50 different types of silica sand. As an example, we have

observed huge differences in conveying performance between sand with rounded grains from riverbeds as compared to sub-angular grains from crushing operations. This is just one example.

I hope this helps!

DYNAMIC AIR INC.,

Gregory J. Steele, P.E.

Executive Vice President

Tel: (651) 486-3023 ■

Effectively, each company develop his one design method. I act as consultant and/or technical assistant on project and so to turnkey plant supplier since 20 years and I,ve developped a performant design method for pneumatic convying, with special application for different conveying system and thousands of differents products. If you need some more help, please contact me. ■

Jack,

Dennis is absolutely right. Don't trust any commercial software.

The real difficulty behind all these issues is that all materials have different behaviour, and especially that different materials exhibit a different trend in their balance between bend losses and straight pipe losses. No commercial software recognises this - they tend mostly to use "equaivalent straight pipe effect" for bends, which is way off the mark when you look in detail at the actual behaviour of the materials. Also, many are based on mathematical correlations which do not take account of the behaviours of individual materials - and again, all materials behave differently.

We do this work by taking a sample of the material, conveying it over a range of conditions in an instrumented line which measures straight pipe and bend losses separately, over a range of conveying conditions, then correlating the data to give straight pipe and bend loss models fitted to the actual data. Following this characterisation step, we use a simple computer programme to simulate the operation of the plant pipeline using this data.

It is simple, reliable, and it works. We have designed many plant pipelines with it, and never come unstuck.

The computer programme is so simple, you can have it for free if you let us do the characterisation tests for you. Mind you, you could easily write it yourself using an Excel spreadsheet - it only runs to about forty rows and twenty columns for most system! Our papers on the calculation system lay out all the calculations in detail.

The most demanding part is that you need to know the loss coefficients for the material, for both bends and straight pipes. These are of course what we determine from the characterisation tests.

If we work together in this way you can have the full data, the calculation method, and everything is open for you to see so you can have confidence in using it. Nothing is secret and therefore unknown, as Dennis rightly says is a problem with the commercial software.

The real beauty of this calculation system is that it is based on real data obtained from the tests, not a mathematical correlation or a guess based on some vague correlation with particle properties.

If you are interested let me know your contact details and I'll send you the papers describing the calculation system. Mail me on bm08@gre.ac.uk

Mike Bradley

Wolfson Centre, University of Greenwich ■

I agree with comments made by Dennis & Dr. Bradley.

The current collection of commercial conveying programs leaves much to be desired. I have taken combination of Zenz's method & some comments from Paul Solt's articles & turned it into a working spreadsheet. Works well but you need to fit a friction factor from plant data or test data.

This works well for dilute phase conveying. But what about dense phase conveying ? Everything seems to be black box there ???!!! ■

Jack:

It's no black box with the system we use.

In fact it works perfectly well for dense phase as well as lean phase conveying, because it is based on data taken from the test pipeline conveying the material over a range of conditions which might be used in the final design.

In many studies we test at both dense and dilute conditions, then using the data produced in order to simulate the plant pipeline we can simulate both dense and dilute operation there - often it is useful to be able to consider both from the point of view of energy consumption, wear and hence overall cost of ownership.

We've designed loads of dense phase systems with this approach - so no problem at all.

Let me know if you want more information on it.

Mike. ■