Dear Baiba Medne,

Calculating your existing system, results in approx. 42 tons/hr of cement at 2 bar.

Combined with an unloading time of 45 min, the bulk truck should contain approx 31.5 tons of cement.

Just increasing the airflow will not significantly change the capacity on the existing pipeline.

Using the 28 m3/min compressor brings an unloading rate of approx. 38 tons/hr, which is even less than the existing situation.

In addition, the filter installation on top of the silo must be adapted.

Increasing the unloading capacity of the bulktrucks requires a complete new design, including the outlet configuration of the bulk truck.

The next possible standard pipe size is 150 mm (6”).

In combination with a compressor of 18 m3/min, the capacity is then approx 78 tons/hr.

The bulktruck outlet must then also be changed to 150 mm.

The filter on top of the silo must be increased to 36 m2

Have a nice day

Teus ■

Dear Baiba Medne,

Yes, if the airflow is increased, maintaining the pipe diameter, then the air velocity increases also.

However, the velocity losses also increase, limiting the capacity at constant pressure drop.

Additionally, the losses due to product (Solid Loading Ratio) and keeping the cement in suspension decrease.

The sum of these changes can be positive or negative but is normally not very much.

From the calculations:

9.16 m3/min and 106 mm results in 6.8 m/sec at the beginning of the pipeline and 18.2 m/sec at the end

28 m3/min and 106 mm results in 20.3 m/sec at the beginning of the pipeline and 51.8 m/sec at the end

18 m3/min and 150 mm results in 6.7 m/sec at the beginning of the pipeline and 18.2 m/sec at the end

take care

Teus ■

Hi guys,

I see the bigger obstacle in the trailer pipe design. Most bulk trucks I am familiar with have 3-4 inch (80-100mm) pipes for air and 5" (125mm) for the cement ones. That is not even considering the valves. I would recommend renting a oilfree 18m3 2 Bar compressor that could help you try this out before you sink too much money into this project. ■

Dear Baiba Medne,

In a pneumatic conveying system, the delivered air from the compressor determines the air velocity in combination with the respective diameter(s).

The pressure is a consequence of this airflow and the pipeline resistance.

The pipeline pressure increases with the material flow (Solid Loading Ratio).

In practice, this is noticed by an increasing pressure when the material flow increases.

If you change one parameter, all values change too, unless you regulate the other parameters separately. F.i. By decreasing the feeding (lowering SLR) the pressure can be set to its original value.

The relations between parameters in a pneumatic conveying system are very complex, which is one of the reasons that there are so many calculation methods floating around in the world.

For your project (increasing the capacity of an existing installation) there are 2 steps to follow.

1)Determine whether the existing installation is under used (shows as too low pressure)

2)Make a new design, possibly using existing componenets.

To your question:

As the pressure drop in the clean air pipeline is small, the influence of the flow in the delivery pipeline is negligable.

greetings

Teus ■