Re: Temperature Change Vaccum Conveying Dehumidifier
Dear marriv,
I'm looking to install an outdoor silo to stock a free flow plastic powder. The powder doesn't absorb humidity.
You probably want to say that the powder does not absorb water, either from humidity nor liquid water
I will use a vacuum conveyor to unload the outdoor silo to fill my indoor surge bin.
The outdoor air conditions can be:
-Pressure: atmospheric
-Temperature: -20 degrC to 35 degrC
-RH maximum = 100%, normally lower at approx. 85%
I'm concern about the temperature change during winter and the risk of condensation on the powder (-20oC outside to 20oC inside).
The worst situation occurs when the plastic powder underneath the outdoor silo is mixed with the outdoor air.
Assuming the powder has the same temperature as the outdoor air, then the outdoor air RH does not change, and no condensation occurs at that location.
However, if the powder has lower temperature than the outdoor air, then the outdoor air RH increases, due to the increased mixture temperature, and condensation can not occur at that location.
As you stated that the powder is not hygroscopic it will not absorb the condensed water.
This situation can happen when the silo is still cold and the outdoor temperature is increasing. (f.i. in spring)
Along the conveying pipeline the absolute pressure will decrease and thereby the RH humidity of the conveying air will decrease. (An important property of vacuum systems)
The conveying air gets drier.
Do you have suggestion about dehumidifier or heater to limit the risk of condensation?
To start with, a heater will not change the water content of the conveying air and when this air mixes with the cold powder, the original RH is restored.
A dehumidifier will dry the intake air before the mixing point underneath the outdoor silo, but will increase the vacuum, which will decrease the RH humidity anyway.
I do not know, whether a dehumidifier will work efficiently at atmospheric pressure and low temperature.
A proper pneumatic conveying calculation will show the RH of the conveying air at each location. ■
Teus
Temperature change vaccum conveying dehumidifier
Hello,
I'm looking to install an outdoor silo to stock a free flow plastic powder. The powder doesn't absord humidity.
I will use a vacuum conveyor to unload the outdoor silo to fill my indoor surge bin.
I'm concern about the temperature change during winter and the risk of condensation on the powder (-20oC outside to 20oC inside).
Do you have suggestion about dehumidifier or heater to limit the risk of condesation?
Mark ■