Pneumatic conveying in vertical pipe sections

Specificity of vertical pneumatic conveying

Section summary
1. Definition
2. Impact of vertical conveying on pressure drop

Pneumatic Transport
Types of pneumatic transport
Conveying phases
Dilute Phase transport
Dense Phase transport
Air mover
Roots Blower
After Cooler
Airlock Rotary Valve
Product inlet / Injector
Pick-up velocity
Conveying speed / velocity
Air volumetric and mass flowrate
Pipe Equivalent Length
Solids velocity in pipe
Solids Breakage
Pressure drop
Pipe Diameter or Bore
Design methods
Pipe Blockage
Powder Build-up
Selecting dilute or dense phase
Horizontal Conveying
Vertical Conveying

1. Definition

In a typical pneumatic conveying pipe layout, most of the pipe sections are horizontal. However, in certain situations, the elevation may not be negligible. It is specifically the case for factories having dry-mix towers which can reach 30 or 50 m height. This is all the more important to understand the impact of vertical conveying that it is very seldom to find a test center able to simulate such elevations, with maximum of 5 to 10 m generally.

2. Impact of vertical conveying on pressure drop

Dilute phase pneumatic transport

In conveying vertically a power or bulk solids in a vertical pipe, the interaction in between the pipe, the air and the solid transported will roughly be similar to the conveying in horizontal pipe, as the solids are dispersed in the carrying air.

The pressure drop will be slightly higher than the pressure drop in an horizontal line as the weight of the air and the weight of the solid in the vertical pipe needs to be compensated.

In shortcut methods, this is taken into account by having an equivalent length of 2 times the length of the vertical section : Le(vertical section) = 2*Lv. In a test plant for example, the Engineer may compensate the lack of elevation by adding more horizontal distance.

In more accurate model, the pressure drop due to the weight of gas and solid can be calculated.

Dense phase pneumatic transport

Manufacturers of pneumatic transport system are generally not too afraid of vertical section they cannot modify in their test line. The reason behind this is that friction of the solids with the pipe is much more intense in dense phase conveying versus dilute phase conveying, and more important in horizontal pipe compared to vertical pipe where the powder is not lying on the pipe.

Note : this page is under development and review, it will be updated soon.

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