Dear Shin Ho Kwon,

I understand your description of an additional air system as a booster air system, where extra air is injected at the beginning of the conveying line.

Opposed to a system, whereby along the pipeline injectors are mounted and short pulses of air are injected, based on the local pressure drops.

This is a high specialized system of which the reports are a bit confusing regarding the efficiency.

Again, the SLR is defined as material mass flow divided by the air mass flow.

Changing the material mass flow or the air mass flow immediately changes the SLR and thereby the pressure drop of the system.

In general, adding booster air lowers the SLR, but can result in extra capacity at the same pressure.

In this situation, it is(was) a dense phase system.

A system with booster air injection, just after the pipe intake, consists of actually 2 systems in series.

1)A short system with a low air mass flow, normally through a smaller diameter pipe.

2)The rest of the conveying system with an air mass flow consisting of the compressor plus the booster through a larger pipe diameter.

In the first section, the SLR is high and in the second section, the SLR is lower.

The calculation is executed also as 2 systems in series, whereby the end of the first section is the beginning of the second section.

The feeding of a system dictates the resulting pressure in a system.

A pneumatic system design should result in the highest capacity against the lowest possible pressure.

(Or, if required, the highest possible capacity against the lowest energy consumption per conveyed ton)

Keep in mind that the SLR is just a calculation parameter value and not a goal in itself.

Answering your questions make me realize how complex the physical relationships in pneumatic conveying are, in spite of the simplicity of the principle.

Have a nice day

Teus ■