Dear Sea Will,

There is no such thing as “the conveying air velocity”, as the air velocity changes along the pipeline, due to expansion.

The conveying air velocity needs to be optimal at any location in the pipeline.

This conveying air velocity is related to the suspension- or floating velocity of the particles.

As the floating velocity of the particles vary with the square root of the pressure,

the required conveying air velocity also changes with pressure.

This is the reason that a stepped pipeline becomes economical (energy wise)

If you relate your pipeline diameter to a conveying air velocity at the end of the pipeline, then the pneumatic conveying system will work.

(but will not be necessarily optimal)

As for "acceleration section", which one is then to choose?

After each bend there is (re)acceleration.

Pneumatic conveying is also cold blooded calculation.

success

teus ■

Dear Sea will,

The estimation of a conveying pipe line diameter is one step in a complex design process.

A simple design process could be represented as:

-design specifications s.a. material, capacity, conveying length, temperature, etc.

-Determination of material properties, related to pneumatic convey ability

-with reference to a floating velocity and/or built installations a conveying air velocity is chosen.

-Based on the length of the pipeline a loading ratio is calculated or assumed.

-Air volume is derived from the loading ratio and the capacity.

-Pipe diameter is calculated from (Air volume)/(Air velocity)

Starting with a preliminary design, subsequent calculations are necessary to get an acceptable accurate design.

The above design process can have shortcuts, if a lot of experience and field data are available,

Even an automated preliminary design can be programmed.

The variables in a pneumatic conveying system are to be coherent and therefore it has no sense to focus on one of the parameters and neglecting the others.

Success

teus ■

Dear Sea will,

The air velocity, I refer to is the air velocity at a certain location in the pipe line.

The most important “air velocities” are the air velocity at the beginning of the pipe line under design pressure conditions and the air velocity at the end of the pipe line under (mostly) atmospheric conditions.

A third air velocity is at the diameter change in the pipe line.

The air velocity after a diameter increase should still be high enough to keep the product in suspension at the local pressure.

I do not speak about “average velocity”.

When you speak about average velocity” , which average do you mean ?

All the best

teus ■